MOL Group - Slovnaft · SLOVNAFT a.s. MGS-S-REF-I-21 R&M Division TECHNICAL SPECIFICATION -...

SLOVNAFT a.s.

R&M Division

This document is property of MOL Group. The use is only allowed with the written permission of MOL Group.

MOL Group

TECHNICAL SPECIFICATION

INSTRUMENTATION

21. Requirements for heater control & safety shut-down

MGS-S-REF-I-21.

Rev 1.00.00

SLOVNAFT a.s. MGS-S-REF-I-21 R&M Division

TECHNICAL SPECIFICATION - INSTRUMENTATION Rev.: 1.00.00

21 Requirements for heater control & safety shut-down Date: 30.11.2011

Page/Pages: 2/25

This document is property of MOL Group. The use is only allowed with the written permission of MOL Group

Release list

Rev. Date Description Edited Verified Approved

0.00.00 26.04.2002 Issue of documentation L.Viszkai R.Batha

0.00.01 20.05.2003 Document issue L.Viszkai R.Batha

0.00.02 20.01.2006

Revised on the basis of experiences of heater revamp projects

L.Viszkai R.Batha

0.00.03 31.03.2006 Revised on the basis of MOL comments L.Viszkai R.Batha

1.00.00 30.11.2011 General issue L. Viszkai R.Batha


Rev 1.00.00 3/25

Contents 1 General requirements ............................................................................................................................................ 4 2 Standards and specifications ................................................................................................................................ 4

2.1 EN standards .................................................................................................................................................. 4 2.2 ISO standards ................................................................................................................................................. 5 2.3 ISA standards ................................................................................................................................................. 5 2.4 API standards ................................................................................................................................................. 5 2.5 Technical specifications for instrumentation per MOL Group Refineries ....................................................... 5

3 Scope of supply ..................................................................................................................................................... 6 4 General requirements applicable to fired heaters ................................................................................................. 6

4.1 Gas burners .................................................................................................................................................... 6 4.2 Oil burners ...................................................................................................................................................... 6

5 Instrumentation requirements of fired heaters ...................................................................................................... 6 5.1 General requirements ..................................................................................................................................... 6 5.2 Start-up & operation and stopping & shutdown requirements ........................................................................ 7 5.3 Control & shutdown unit ................................................................................................................................. 8 5.4 Requirements of combustion safeguard and display ..................................................................................... 8 5.5 Requirements to be satisfied by flame Detectors ........................................................................................... 9 5.6 Alarm management ....................................................................................................................................... 9 5.7 Automatic safety shut-off valves ................................................................................................................... 10 5.8 Control valves ............................................................................................................................................... 10 5.9 Flue gas instrumentation .............................................................................................................................. 10 5.10 Tube-Skin and heater refractory temperature measurement .................................................................. 11

6 Fired heater monitoring, control & actuating system ........................................................................................... 11 6.1 Combustion air supply .................................................................................................................................. 11 6.2 Fuel gas supply of pilot burners.................................................................................................................... 11 6.3 Fuel gas supply of main burners .................................................................................................................. 11 6.4 Fuel oil supply ............................................................................................................................................... 12 6.5 Capacity control of forced draft fuel gas fired heaters .................................................................................. 12

7 Design requirements of fired heaters .................................................................................................................. 12 7.1 General requirements ................................................................................................................................... 12 7.2 Design criteria ............................................................................................................................................... 13 7.3 Utilities: ......................................................................................................................................................... 13 7.4 Alarm, control & shutdown signals ............................................................................................................... 13 7.5 Definition of start-up and stop process ......................................................................................................... 20

8 Required documentation to be supplied .............................................................................................................. 21 9 Instrumentation & shutdown functions of heat recovery systems ....................................................................... 22

9.1 Recuperators for combustion air pre-heating ............................................................................................... 22 9.2 Steam generating heat recovery boilers ....................................................................................................... 23

10 Combustion air blowers and their control system......................................................................................... 23 10.1 Installation requirements of air blowers ................................................................................................... 23 10.2 Input/output signals and alarms of air blowers to be displayed in the control system ............................. 23 10.3 Instrumentation of discharge side dampers of air blowers ...................................................................... 24

11 Appendix ....................................................................................................................................................... 24 11.1 Standards ................................................................................................................................................. 24 11.2 Slovak statutes ......................................................................................................................................... 24 11.3 Instrument air supply................................................................................................................................ 24 11.4 Utilities ..................................................................................................................................................... 24


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REQUIREMENTS FOR HEATER CONTROL AND SAFETY SHUT-DOWN

1 General requirements

This specification contains the minimum requirements, applicable to the detail engineering of instrumentation and process control equipment and to the assembly, manufacture and testing of control systems and equipment used for natural or forced draft fired heaters burning natural gas or refinery fuel gas (natural gas plus internally produced gas and possibly tail/waste gas) or refinery fuel oil.

The stipulations or deviations described in the Basic engineering documentation or Project Specifications and the general specifications for instrumentation & process control design may supersede the requirements described herein.

An exception(s) list shall be submitted if any deviation arises from these specifications.

Any deviation from the Basic engineering documentation or Project Specifications, the general specifications for instrumentation & process control design, and this specification shall only be allowed subject to the written approval.

Fulfilling the requirements of this specification will not relieve from the obligation of supplying suitably designed and constructed systems and equipment that ensure the monitoring, control, alarm indication and shutdown functions required for the safe, reliable and high efficiency operation of the heaters.

It is to be emphasized that depending on the technological application, the capacity, the number and arrangement, as well as the location of the burners, the type of fuels...etc. of the heaters, in the design of burner management system for each heaters there may be significant differences, so this book shall be considered as a “guide line”, however it is mandatory that the design complies in all respect with the requirements of applicable national legislations and standards.

2 Standards and specifications

2.1 EN standards

EN 746-2 Industrial thermo-processing equipment. Part 2: Safety requirements for combustion and fuel handling systems

EN 12952-8 Water-tube boilers and auxiliary installations. Part 8: Requirements for firing systems for liquid and gaseous fuels for the boiler

EN 267 Automatic forced draught burners for liquid fuels

EN 298 Automatic gas burner control systems for gas burners and gas burning appliances with or without fans

EN 161 Automatic shut-off valves for gas burners and gas appliances

EN 264 Safety shut-off devices for combustion plants using liquid fuels. Safety requirements and testing

EN 60079-10/14 Electrical apparatus for explosive gas atmospheres – Parts 10 & 14

EN 61508-2/-3 Functional safety of electrical / electronic / programmable electronic safety-related systems – Parts 2 & 3

EN 61511-1/-2/-3 Functional safety. Safety instrumented systems for the process industry sector – Parts 1, 2 & 3

EN 334 Gas pressure regulators for inlet pressures up to 100 bar

EN 1643 Valve proving systems for automatic shut-off valves for gas burners and gas appliances

EN 1854 Pressure sensing devices for gas burners and gas burning appliances

EN 60529 Degrees of protection provided by enclosures (IP code) (includes amendment A1:2000)

EN 60584 Thermocouples.

EN 60751 Industrial platinum resistance thermometers and platinum temperature sensors

EN 62305 Protection against lightning


Rev 1.00.00 5/25

EN ISO 5167-2 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full. Part 2: Orifice plates

EN ISO 5167-4 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full. Part 4: Venturi tubes

2.2 ISO standards

ISO 3511 Process measurement control functions and instrumentation, symbolic representation

2.3 ISA standards

ISA-S18.1 Annunciator sequences and specifications

ISA-S5.2 Binary logic diagrams for process operations

ISA-S20 Specification forms for process measurement and control instruments, primary elements and control valves

2.4 API standards

API 560 Fired heaters for general refinery services

API RP 556 Instrumentation and control systems for fired heaters and steam generators

API RP 535 Burners for fired heaters in general refinery services

API RP 536 Post combustion NOx control for equipment in general refinery services

API RP 553 Refinery control valves

API RP 550 Manual on installation of refinery instruments and control system

API RP 551 Process measurement instrumentation

API 531M Measurement of Noise from fired process heaters

2.5 Technical specifications for instrumentation per MOL Group Refineries

MGS-M-REF-I-1, MGS-S-REF-I-1, MGS-M-REF-I-9, MGS-S-REF-I-9,







MGS-M-REF-I-8, MGS-S-REF-I-8,


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3 Scope of supply

3.1 Unless required otherwise by the basic engineering documentation or project specification, the scope of supply for instrumentation and control systems shall include as a minimum the basic and detail engineering phases, the necessary engineering services, authority review & approval procedures, product design & manufacture, factory & site acceptance tests, erection supervision and commissioning as well as all instruments and control equipment included in this specification and indicated on the respective P&I drawing.

3.2 The technical solution shall ensure fuel and combustion air measurements and performance control functions for a minimum 5 to 1 capacity turndown ratio of the fired heater, unless required otherwise by the basic documentation or project specification.

3.3 The scope of supply shall include all the information, materials, erection consumables, special tools, instruments and certificates required for proper & safe start-up and for stable & high-efficiency continuous operation and ensuring the activation of alarm and shutdown (trip) functions, respectively, when limit values are exceeded.

4 General requirements applicable to fired heaters

4.1 Gas burners

4.1.1. All fired equipment and gas burners shall comply with the applicable requirements of EN 746-2 respectively, and designed with the applicable requirements of API Standard 560 taken into consideration.

4.1.2. Burners shall operate in the capacity control range stipulated by the basic documentation or project specification with steady flame, without fluctuation phenomena, flame-out and back-fire, with all these requirements included on mandatory basis in the mechanical & operating instructions of the fired heater and in the burner specification. This instrumentation specification is based on compliance with all the above requirements.

4.1.3. MOL Group requires the use of continuously burning ignition burners (hereinafter pilot burners) with a heat output less than 70 kW in order to avoid the necessity of double automatic safety shut-off valves, unless required otherwise by the project specification.

4.1.4. Fuel gas supplied by separate lines to the pilot burner(s) and main burner(s) shall be filtered by duplex filters installed in parallel, suitable for switching over during operation (one in service, the other stand-by), in order to prevent line plugging upstream of the burners. Alarm and reporting functions shall be implemented for filter plugging (high dP).

4.2 Oil burners

4.2.1. Oil burners shall comply with the applicable requirements of EN Standards 267 and 12952-8, respectively. The oil burners shall operate steadily without flame-out under the effect of the natural draft or forced/induced air flow expectable during the intended proper mode of operation. This instrumentation specification is based on compliance with all the above requirements

4.2.2. Fuel oil supplied to burner(s) shall be filtered by duplex filters installed in parallel, suitable for switching over during operation (one in service, the other stand-by), in order to prevent line plugging upstream of the burners. Alarm and reporting functions shall be implemented for filter plugging (high dP).

5 Instrumentation requirements of fired heaters

5.1 General requirements

5.1.1. Firing equipment and their instrumentation/control systems shall comply with the applicable requirements on safety and monitoring/controlling of the standards listed under Section 2.

5.1.2. Unless required otherwise by the safety requirement specification (SRS) of the safety book or the project specification, the Burner Management System (BMS), the automatic control and related shutdown (trip) instrumentation shall satisfy minimum SIL-3 and SIL-2 requirements as specified for safety integrity levels by EN Standard 746-2:2010 point 5.7.2/c.

5.1.3. Heater pilot or ignition burner light-off shall be provided by electric spark plug(s) manually controlled from local ignition panel(s) or local control board.

5.1.4. The Boolean logic used for shut-down (trip) functions shall be “Negative”, the permission and trip gates shall be logic “AND” gates. The logic blocks of BMS functions shall be combination type, not containing any “Flip-Flop” elements.


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5.1.5. All discrete shutdown inputs shall be logic “1” (closed contact) in fault-free (normal operating) status and logic “0” (open contact) in trip (fail) status. Exceptions to this rule shall be the limit switches (used e.g. for valve limit positions), which shall output logic “1” signals in limit position status with the use of proximity sensors.

5.1.6. The break or shorting of electric circuits shall not result in the automatic disabling or overriding of shutdown functions.

5.2 Start-up & operation and stopping & shutdown requirements

5.2.1. The common start-up steps and supervision of heater start-up shall be carried out on the local (field) control board and the burners lighted off and supervised from dedicated local ignition panels, unless required otherwise by the project specification (e.g. requiring the burner light-off tasks to be carried out and checked also on the local control board). The flame status signals of the burners shall also be indicated on the local control board. The local control board or panels shall be installed at safe locations allowing the monitoring of the burners and the related automatic safety shut-off valves and its operation.

5.2.2. The shutdown system shall be a step to ”non volatile lock-out status” if the firebox purging period has expired and no burner could be lighted within the period specified for ignition (there is no flame-on signal in the heater).

5.2.3. The expired or remaining time settings longer than 3 seconds shall be displayed numerically on the DCS monitors if the control/ESD (emergency shutdown) system is implemented with the use of fail-safe programmable logic controllers (PLC).

5.2.4. Damper shall be opened automatically and gradually after the lighting of the main burner if a remote operated open-close combustion air damper is installed for each burner.

5.2.5. The heat output during the start-up of the main burner (or the first main burner if more than one main burners are used) shall be restricted (at capacities exceeding 350 kW) in compliance with EN Standard 746-2. This capacity restriction is to be terminated when the (first) main burner is in normal operating mode.

5.2.6. Manual emergency stop pushbuttons shall be provided for fired heaters in the control room and on the local control board and at a safe distance from the heater in the field.

5.2.7. Shutdown inputs shall satisfy the safety requirement specification (SRS) of the safety book (e. g. shall be configured in 2003 voting system if max. 10 years spurious trip rate is specified), unless required otherwise by the basic design documentation or project specification. The use of maintenance override (MOS) switches is not permissible for 2003 voting shutdown inputs.

5.2.8. If a fuel gas knock-out drum is installed, its high-high level output shall be included in the common shutdown conditions of both the pilot and main burners.

5.2.9. The ESD system shall prohibit main burner re-starting for a pre-set period after the stop of any operating main burner.

5.2.10. Process override functions for trips shall be activated and deactivated automatically or deactivated by timers as far as possible. If this is not possible and manual operated process override is activated then the override periods shall be measured by the safety PLC and displayed on the DCS. The overridden status shall activate alarms at every expiry of pre-set periods (e.g. 8 hours).

5.2.11. Automatic timed override function shall be provided for the low-low and high-high gas pressure shutdown signals during the ignition of the first pilot and main burners if these signals are in trip status at the start period.

5.2.12. Automatic timed override function may be provided for the high-high firebox pressure shutdown signal tripping the main burners during the ignition of main burners. Process override switch (POS) may also be provided for the high-high firebox pressure shutdown signal subject to the implementation of periodic display, alarm and archiving functions for its activation.

5.2.13. If maintenance override switches (MOS) or process override switches (POS) are used, then the activated status of each shall be displayed periodically on the DCS (with timestamps). MOS switches shall be installed in some enclosure lockable with key and used only in accordance with the operating instructions. If certified, software switch on the maintenance display also can be used by maintenance personnel, protected by maintenance pass word. POS switches shall not be included in the burner management system (BMS) and used only for overriding the process trip signals of the heater subject to the operators’ case-by-case judgment.

5.2.14. DCS alarm shall be provided at least for the low combustion air to gas ratio low (alarm) set value and the project specification shall determine whether main burner shutdown is required at low-low set-value.

5.2.15. Ratio adjustment with the use of some rigid connection (e.g. mechanical rod) between the fuel gas and combustion air control valves is not permissible for the implementation of fuel gas to combustion air ratio


8/25 Rev 1.00.00

control. The implementation of ratio control based on flow measurements is required and the ratio is to be corrected according to the variations in the composition (heating value) of the fuel gas ..(selectable also by the operator from the fuel gas list stored in the database) and the O2 content of the flue gas. The variation in the heating value of the various qualities of fuel gas (internally produced in the process unit, imported from the refinery header, off-gases, etc.) shall be used as input for both combustion air to gas ratio control and ratio alarm functions.

5.2.16. Ratio control shall be implemented in the high-reliability redundant DCS controlling also the other sections of the process unit. If no DCS system is available, ratio control shall be provided by a conventional (4-20 mA) signal range controller mounted on the main board, with minimum set-point (SP) – process variable (PV) – output (MV) display, manual – auto – cascade switching facility and the necessary set of algorithms.

5.2.17. Isolation valves installed in hook-up lines upstream of (pressure, differential pressure) sensors used for shutdown functions shall be applied only in sealed open position. The use of such seals shall be specified in the operating instructions.

5.3 Control & shutdown unit

The burner control unit shall comply with the applicable requirements of EN Standard 298.

The burner control unit shall operate reliably within the voltage fluctuation range of –15% to +10% and at ambient temperatures ranging from 0°C to 60°C.

Provisions shall be made for preventing unauthorized personnel to misadjust the trip values and timers.

5.3.1 Safety Control Cabinet

5.3.1.1 Control cabinet

The control cabinet shall comply with the requirements of Specification MGS-M-REF-I-7 & MGS-S-REF-I-7.

5.3.1.2 Fail-safe PLC (FSC)

5.3.1.2.1 General requirements

The fail-safe PLC shall comply with the requirements of MGS-M-REF-I-6.2 & MGS-S-REF-I-6.2.

The probability failure level (PFD value) of the fail-safe PLC shall comply with the safety requirement specification (SRS) of safety book or the project specification satisfying SIL-3 and SIL-2 requirements as specified for safety integrity levels by EN Standard 746-2:2010 point 5.7.2/c.

The fail-safe PLC shall be 2002D voting type, fault-tolerant, increased available, self-diagnosing system. The diagnostic coverage shall include also the I/O interfaces.

5.3.1.2.2 Hardware requirements

Redundant I/O’s shall be provided for all ESD and control/trip functions.

The HOST communication link to the DCS shall also be redundant.

User HM interface (e.g. monitor) is not required.

5.3.1.2.3 Software requirements

The cycle time of the control/trip program shall less than 100 msec.

The PLC shall perform the following functions as a minimum:

o Control, start-up, stopping and emergency shutdown of heater.

o Alarm displays with timestamps.

o First-out monitoring in compliance of Specification “F3A” of ISA Standard S18.1 if it is displayed on annunciator panel.

o Sequence of events (SOE) logic display and print-out on DCS (ICS).

5.4 Requirements of combustion safeguard and display

5.4.1. The integration of flame detectors and flame signals used for pilot and main burners into the emergency shutdown system shall comply with the requirements of EN Standard 746-2 applicable to flame detectors.

5.4.2. Dedicated continuous light and sound alarm annunciation (also alarm display on the DCS operator screen) shall be actuated in the control room during normal operation upon any flame detector alarm (no flame is detected or failed device) until it is acknowledged by the operating personnel.

5.4.3. The ”Flame ON” signals of the burners and the “No Flame in the heater” shall be indicated by dedicated indicator lamps and a continuous alarm light, respectively, on the local control board.


Rev 1.00.00 9/25

5.4.4. If the number of unsuccessful ignition attempts of the pilot burner (or of the first pilot burner when more than one pilot burners are used) reaches 3 occasions, as specified by EN Standard 746-2, the shutdown system shall be step back to the status preceding heater purge.

5.4.5. If the number of unsuccessful ignition attempts of the main burner (or of the first main burner when more than one main burners are used) reaches 3 occasions, as specified by EN Standard 746-2, the shutdown system shall be step back to initial shutdown “non volatile lock-out status”.

5.4.6. Both the pilot burner and the related main burner shall operate with steady flames for a pre-set (simultaneous burning) period during the ignition of a pilot/main burner assembly with the safety time specified for main burner start-up (light-off) also taken into account. The safety time required during the normal operation of main burners shall be applied only subject to the existence of the “Flame ON” signal from the pilot burner dedicated to the main burner and the expiry of the pre-set simultaneous burning period.

5.4.7. If a flame detector has a “Flame ON” output signal before pilot burner ignition period, then the burner control system shall stop the continued running of the program in “non volatile lock-out status” and the program available for re-starting is after the extinction of the “Flame ON” signal.

5.4.8. All changes in the outputs of flame-detectors shall be reported by the system with timestamps.

5.5 Requirements to be satisfied by flame Detectors

5.5.1. Flame-detectors shall perform self-checks periodically and supplied with certifications (TÜV, DVGW, GASTEC, AFNOR, IMQ, etc.).

5.5.2. Detector failure or the break or shorting of interconnecting lines shall result in “Flame OFF” signal.

5.5.3. The location and design of flame-detectors shall prevent the occurrence of malfunction due to the presence of dust, condensate and other contaminants present inside the heater.

5.5.4. The setting angle of flame-detector shall be adjustable.

5.5.5. Output of flame-detectors shall generate an open circuit (logically ”zero” signal) upon malfunctioning or absence of flame.

5.5.6. Flame-detectors shall be cooled and cleaned by an instrument air jet unless required otherwise by the basic design documentation or project specification.

5.5.7. Flame-detector amplifiers shall include flame intensity indication.

5.5.8. 230 VAC UPS supply voltage shall be used for the amplifier of flame detectors.

5.5.9. Flame-guards shall function only in connection with the flame of the burners monitored by them and not be actuated as a result of external heat or light effects (e.g. incandescent refractory, lamp light, etc.). In consideration of gas firing being used in majority and the short response time required, MOL Group prefers the use of UV flame-detectors, but the flame spectrum of the fuel shall also be taken into account, however ionization type flame detector also can be used for pilot flame.

5.6 Alarm management

5.6.1. Alarm philosophy and priority shall satisfy the MGS-M-REF-I-6.9 & MGS-S-REF-I-6.9 requirements.

5.6.2. Shutdown signals of the main burners shall be displayed with first-out indication in accordance with ISA S18.1 type “F3A” specification and pre-alarms with ISA S18.1 “A” type solution if realized on the annunciator panel. First-out alarm indication with steady light can also be realized on DCS operator panel.

5.6.3. Taking into consideration that fired heaters may be started up only under the supervision of field operators from the local control board with the use of steady (continuously illuminated) status indicator lamps, the first-out annunciator panel used for the signals for the automatic shutdown functions during remote supervision (Service Class III) is required only in the control room. As required by the project specification, the light and sound alarms of the first-out annunciator panel shall be provided either by a dedicated indicator lamp and alarm horn assembly connected to the ESD system or by first-out alarm display on the operator screen of the DCS system and alarm horn..

5.6.4. Transmitters or limit switches and switching instruments used for pre-alarm functions shall provide open contacts when limit values are exceeded. The transmitters or switching instruments of pre-alarm functions shall provide alarm signal and sound the alarm horn before the actuating and emergency shutdown devices are activated (i.e. provide pre-warning for the operators).

5.6.5. The individual limit switch blocks of analogue inputs in the fail-safe PLC shall include alarm outputs for instrument failure and PLC card failure but these shall not be connected to the shutdown outputs of the limit switches (unless required otherwise by the basic documentation or project specification). Discrepancy monitoring and display functions shall be provided for analogue and the binary status shut-down inputs used in voting system.


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5.6.6. Independent pre-alarms shall be provided for all shutdown signals at least on the DCS.

5.6.7. The DCS shall generate sequence of events (SOE) reports (by means of SOE cards in the fail-safe PLC or the DCS system) for all pre-alarm and shutdown signals.

5.7 Automatic safety shut-off valves

5.7.1. Automatic safety shut-off valves shall comply with the applicable requirements of EN Standard 161 for fuel gas and -EN Standard 264 for fuel oil and the requirements of EN Standard 746-2 applicable to safety block valves shall also be taken into consideration.

5.7.2. Ball valves or taper-plug shall be used as automatic safety shut-off valves.

5.7.3. Electro-pneumatic or electro-hydraulic actuators shall be used for field-mounted final control elements (shut-off valves, control valves). Direct-acting electric actuators (direct-acting solenoids, motor drives) are not acceptable.

5.7.4. The fail action of automatic safety shut-off valves used for blocking of gas supply shall be “fail-close” (FC) in the case of power/utility failure.

5.7.5. The closing time of automatic safety shut-off valves operating with rated supply pressure, nominal supply voltage and within the specified ambient conditions shall not exceed the values specified in the applicable EN Standards.

5.7.6. Because of the dust contamination present in the refinery fuel gas network and liable to deposit as a solid surface the torque provided by the actuators of automatic safety shut-off valves used infrequently but required to function reliably when needed shall be at least 10 times higher than the torque of the actuators used in normal operation. The rotating shaft, the block valve and all mechanical components shall be sized in accordance with this requirement.

5.7.7. Automatic safety shut-off valves shall operate reliably even at +5% to –5% fluctuations in the 230 VAC UPS or 24 VDC UPS supply voltage and in the –25°C to +60°C ambient temperature range.

5.7.8. The shock-protection of automatic safety shut-off valves shall comply with the requirements of the end user relevant local standards, their explosion-proof protection with EN Standard 60079-10/14, respectively, and protection class provided by enclosure with EN Standard 60529.

5.7.9. Powered block valves used for gas shall close upon power failure, the vent valves shall open.

5.7.10. MOL Group requires an automatic (FO) emergency bleed valve to be installed for venting the space between two automatic (FC) emergency gas supply block valves into a non-pressurized space.

5.7.11. The actuation (control signal) of the automatic safety shut-off valves, including the outputs of the fail-safe PLC shall be independent of each other.

5.7.12. Limit switches shall be installed at least for indicating the closed position of the automatic safety shut-off valves and the emergency bleed valve (not closed position).

Note: MOL Group requires the use of automatic safety shut-off valves consisting of solenoid valves and air-operated taper-plug or ball valves for the above functions.

5.8 Control valves

5.8.1. Unless required otherwise by the basic documentation or project specification, only stepless 4-20 mA signal range controller may be used for all analogue control functions, including the capacity control of main burners switching of analogue control mode between manual / auto / cascade modes and gas-air ratio control for gas/fuel oil burners.

5.8.2. The fail action of gas and fuel oil control valves shall be fail-closed and the fail action of combustion air control dampers shall be fail-open.

5.8.3. MOL Group requires fuel oil burner(s) for basic firing mode, unless required otherwise by the basic documentation or project specification.

5.9 Flue gas instrumentation

5.9.1. The on-line flue gas oxygen content analyzer shall use zirconium dioxide detector and installed on the stack.

5.9.2. The remote units of on-line NOx, CO and SOx analyzers (if required by the basic documentation or project specification) shall be installed in a container.

5.9.3. Upon total heater shutdown (in the case of complete flame failure or low-low temperature) the heating current shall be switched off and instrument air purge shall be supplied for cooling the probe of the O2 analyzer and preventing it poisoning (except if this requirement is not specified by the sensor supplier).


Rev 1.00.00 11/25

5.10 Tube-Skin and heater refractory temperature measurement

Thermocouples (Type “K” according to EN Standard 60584-2) shall be used for this function, introduced through the wall of the heater with the use of drilled blind flanges and the sensor wires connected to an instrument head.

6 Fired heater monitoring, control & actuating system

The applicable requirements of MGS-M-REF-I & MGS-S-REF-I and API RP 550 specifications shall be taken into consideration for the design of the monitoring, control, regulating and shutdown system of fired heaters.

6.1 Combustion air supply

Combustion air for fired heaters may be supplied by self-inspirating (natural draft) or forced draft.

6.1.1. Natural draft heaters

Flow control of combustion air can be provided by remote-operated butterfly valves installed upstream of each burner, unless specified otherwise by the basic documentation or project specification.

6.1.2. Forced draught heaters

Combustion air for forced draught heaters shall be supplied by combustion air blower(s). The flow control of combustion air shall be based on flow measurement (use of Venturi-tube meters is preferred) and the regulation of butterfly valves or the speed of blowers supplied with frequency converters or the vane angle of blowers.

The flow measurement of combustion air shall be pressure and temperature compensated.

Provisions shall be made to prevent the oscillation of flow controllers reaching rates resulting in the shutdown of the main burner(s).

Combustion air for pilot burners may also be supplied with instrument air controlled with pressure reducer and/or manual needle valve in the case of forced draft pilot burners.

6.2 Fuel gas supply of pilot burners

6.2.1. Fuel gas for pilot burners of heaters fired with several burners may be supplied by a common fuel gas system with pilot gas lines branching off for each pilot burner.

6.2.2. Automatic safety shut-off valves shall be installed either upstream of each pilot burner and in the common pilot gas header or only in the pilot gas header if thorough ignited burner groups are configured.

6.2.3. Pressure reduction for the fuel gas system of pilot burners shall be provided by 2 pressure regulators (1 in operation, 1 stand-by). Ball valves shall be installed for switching over the pressure reducers. Pressure reducers shall satisfy the applicable requirements of EN Standard 334.

6.2.4. The capacity (flame) of pilot burners shall be controlled by regulating the flow of fuel gas available at the pressure set by the pressure reducer(s) with the use of manual throttle valves.

6.2.5. The shutdown function of pilot burners at low-low gas pressure shall be realized for each heater with the use of low-low pressure detectors installed in the pilot gas header upstream of the two automatic safety shut-off valves and bleed valve group in the number required by the SIL category and spurious trip rate of the safety requirement specification (SRS) in the safety book (e. g. shall be configured in 2003 voting system if max. 10 years spurious trip rate is specified), unless required otherwise by the basic design or project specification.

6.2.6. MOL Group requires an automatic (FO) emergency bleed valve to be installed for venting the space between two automatic (FC) automatic safety shut-off valves into a non-pressurized space.

6.2.7. Pressure detectors shall satisfy the applicable requirements of EN Standard 1854.

6.2.8. If the pilot and main burner is guarded by one flame detector, the fuel gas and combustion air flow (or pressure min./max.) of pilot burner shall be detected for shut down function of pilot burner.

6.3 Fuel gas supply of main burners

6.3.1. Pressure control and temperature & pressure compensated flow measurement shall be provided for the fuel gas header of each heater.

6.3.2. The start flow rate of the fuel gas main burners shall be set by the ratio controller of the DCS system (or the analogue 4-20 mA ratio controller) with the status signals provided by the fail-safe PLC taken into consideration (in the case of start-up by-pass line or direct supply line). The start-up capacity of the fuel gas main burners shall be controlled subject to shutdown set-points with the use of flow limit switches and the monitoring of the start-up positions of the fuel gas control valve.


12/25 Rev 1.00.00

6.3.3. The shutdown function of the fuel gas main burners at high-high gas pressure shall be realized by burner or commonly, as required by the project specification, with the use of high-high pressure detectors installed in the gas header in the number required by the SIL category and the specified availability.

6.3.4. The shutdown function of the fuel gas main burners at low-low gas pressure shall be realized with the use of low-low pressure detectors installed in the gas header upstream of the two automatic safety shut-off valves & one bleed valve group and flow or pressure control valve in the number required by the SIL category and the specified availability.

6.3.5. Two automatic safety shut-off valves and one bleed valve group required by MOL Group shall be considered as automatic safety shut-off valves for fuel gas of main burners. At least one pressure transmitter shall be installed for leak detection between the two automatic safety shut-off valves with their outputs processed and evaluated by the PLC based logic system providing a heater start-up prohibit command if gas leak through the automatic safety shut-off valves are detected. The technical solution of leak detection shall satisfy the applicable requirements of EN Standard 1643.

6.3.6. The analogue display of the pressure drop across the duplex fuel gas filter shall be provided on the DCS as well as alarm display at high pressure differential set-point (in order to warn the operators of impending filter plugging and the need of filter switching over).

6.4 Fuel oil supply

6.4.1. If necessary the fuel oil pre-heating and temperature regulation shall be implemented for adjusting the viscosity of the fuel oil as required for atomization.

6.4.2. The flow of fuel oil supplied to the heater shall be measured (preferably with Coriolis meter) and totalized.

6.4.3. Low temperature and pressure trip for the fuel oil header shall be provided with the use of temperature and pressure detectors installed in the number required according to the SIL category and the specified availability. .

6.4.4. Low pressure trip for the atomizing medium (steam) header shall be provided with the use of pressure sensors installed in the number required in accordance with the SIL category and the specified availability as well as low pressure differential alarm for the fuel oil/atomizing steam by means of a sealed dP transmitter.

6.4.5. The analogue display of the pressure drop across the duplex fuel oil filter shall be provided on the DCS as well as alarm display at high pressure differential set-point (in order to warn the operators of impending filter plugging and the need of filter switching over).

6.5 Capacity control of forced draft fuel gas fired heaters

6.5.1. The capacity control of the heater shall be implemented on the basis of controlling the outlet temperature of the fluid circulating through the tubes of the heater by regulating the fuel flow, unless required otherwise by the basic documentation or project specification.

6.5.2. Combustion air flow control shall be implemented by a actuating butterfly valve or the vane angle or speed (with frequency converter drive) of the air blower on the basis of flow measurement with Venturi-tube.

6.5.3. The fuel gas and oil /combustion air flow and ratio control – corrected on the basis of the oxygen content of flue gas between pre-set limits – shall be implemented on the DCS or ICS or with a 4-20 mA analogue controller complete with the automatic provision of excess air at all times.

7 Design requirements of fired heaters

7.1 General requirements

7.1.1. Engineering documentation shall include all the equipment, instruments and devices required for the measurement, control, status indication, alarm and shutdown functions of the heater and to be installed on the local control board, the auxiliary console of the operator station or the main board (hereinafter control room operator panel), including the emergency shutdown system (fail-safe PLC) and the terminals, galvanic isolators & barriers in the Marshalling cabinet (hereinafter control room equipment) as well.

7.1.2. Unless required otherwise by the basic design engineering, package or the project documentation, the control (event detection, monitoring/supervision, event reporting /logging / alarm annunciation, including the fuel to combustion air ratio control) of the process unit – inclusive of the fired heater – is to be taken into consideration as implemented on a Distributed Control System (DCS) or Integrated Control System (ICS).

7.1.3. The system drawing of the heater control and safety shut-down system see on attachment No. 1.


Rev 1.00.00 13/25

7.2 Design criteria

7.2.1. Each instrumentation item shall be provided with a bilingual (English and the end user language) datasheet indicating the tag number, the service description of the measurement and/or control function and the process & construction data (refer to MGS-M-REF-I-5 & MGS-S-REF-I-5 for the specification sheets to be used).

7.2.2. The weather-proof enclosure of field instruments shall satisfy minimum IP65 requirements as specified by EN Standard 60529.

7.2.3. All hook-up lines containing fluid liable to solidify or freeze shall be heat traced as required for the ambient temperature range of –25°C to +60°C.

7.2.4. Field indicator instruments operating at 70 barg (1000 psig) or higher pressure and all glass tube type level gauge regardless of pressure shall be fitted with check valves closing at high flow rates in order to prevent the escape of process fluids in the case of instrument failure/breakage.

7.2.5. The load rate and isolation of all control/shutdown outputs shall be finalized in the basic design engineering documentation, package or project specification.

7.2.6. All control/shutdown analogue inputs and outputs shall be galvanic isolated and intrinsically safe and used 4-20 mA signal range.

7.2.7. Analogue loops shall include HART communication.

7.2.8. All thermocouples shall be Type “K” according to EN Standard 60584-2 and all resistance temperature detectors shall be Platinum 100 (Pt 100) type according to EN Standard 60751.

7.2.9. The use of field-mounted temperature switches (bimetal temperature switches, contact temperature sensors, etc.) is not allowed.

7.2.10. All explosion-proof instrumentation items, local control board and equipment shall be intrinsically safe and certified accordingly, or – where this is not possible – flame-proof (Eexd) enclosures or enhanced (Eexe) protection shall be used and certified in accordance with the hazardous area classification given in the basic design engineering documentation or project specification. All explosion-proof instruments and equipment shall be certified in compliance with ATEX 94/9 EC (EU 100A) requirements.

7.2.11. Regardless of the hazardous area classification of the surroundings, all measuring, transmitting or switching instruments penetrating inside or connected with the internal space of the heater shall be provided with intrinsically safe protection or flame-proof enclosures as required for Zone-1 areas. The explosion-proof class of the instrumentation items outside the heater shall comply with the requirements imposed by the hazardous area classification of the heater’s surroundings.

7.2.12. The instrumentation system shall comply with the specifications of EN Standard 60079 respectively, as applicable on the basis of ex-proof protection requirements defined in the basic design engineering documentation or project specification, and secondary lightning/surge/transient protection shall satisfy the requirements of EN Standard 62305 and the valid rules and statues.

7.2.13. The design of the local control board and ignition panel as well as PLC cabinet and Marshalling cabinet shall comply with requirements of specifications MGS-M-REF-I-7, MGS-M-REF-I-13, MGS-S-REF-I-7 and MGS-S-REF-I-13.

7.2.14. The hardware and software configuration of the fail-safe PLC shall comply with requirements of Specifications MGS-M-REF-I-6.2 & MGS-S-REF-I-6.2.

7.2.15. The sensors, transmitters, switches and alarm or display items as required for the start-up, safe operation and shutdown of the heater shall be installed in the process area or the control rooms wired into the terminal boards, operator consoles and equipment. Status signals shall be displayed on the local and/or remote control boards as well as on the DCS or ICS screens. Alarms to be displayed on the DCS transmitted by redundant serial signal communication in the case of ESD systems using fail-safe PLC.

7.2.16. The safety instrumented technical solution of the burner management/interlock system shall be developed by the heater Designer/Vendor and the basic design engineering contractor.

7.3 Utilities:

Electric power supply for instrumentation: see App.

7.4 Alarm, control & shutdown signals

The alarm and shutdown transmitters and switches or pushbuttons and indicator / display and final control elements listed in the following table may be used for the control-shutdown and status indication of fired heaters. It is to be emphasized that the individual application may vary from the items listed below. Actual signal sensor and alarm devices as well as final actuating elements and their functions will be finalized in the project or package unit specification and the basic design engineering documentation, respectively.


14/25 Rev 1.00.00

Notes: Only the signals required for one burner (marked “A”) are listed below.

“LIP or LB”; If the project specification or basic documentation requires no separate ignition panel (LIP) for each burner, the items required for the ignition and supervision of the burners will be installed in the common local control board (LB).

Item Description Source of command

signal

Alarm Lamp/DCS

Source of alarm signal

Actuation and source of signal

1. Heater permission to start end operation

MB-RM-FM (Key lockable push button)

RM-FM (Start & operation condition of heater)

2. Heater ready to start MB-LB-DCS RM-FM

3. Gas-tight test of SOV´s Ready to start

LB-DCS RM-FM

4. Gas-tight test of SOV´s Start

LB-LM-FM (Push button)

RM-FM (SOV´s of fuel gas header open/close)

5. Gas-tight test of SOV´s in progress

LB-DCS RM-FM

6. Remaining gas-tight test time of SOV´s

DCS RM-FM

7. First SOV gas-tight test failure

LB-DCS RM-FM RM-FM (Program back to lock-out status)

8. Second SOV gas-tight test failure

LB-DCS RM-FM RM-FM (Program back to lock-out status)

9. Gas-tight test of SOV´s OK (and completed)

LB-DCS RM-FM RM-FM (Purging condition)

10. Heater purging Ready for start-up

LB-DCS RM-FM

11. Heater purging Start

LB-LM-FM (Push button)

RM-FM (Purge timer start)

12. Purge in progress LB-DCS RM-FM

13. Remaining purging time of heater

DCS RM-FM

14. Heater purge completed

LB-DCS RM-FM

RM-FM (Start condition of pilot burner and purged status timer start)

15. Heater purged state remaining time

DCS RM-FM

16. Heater purged state time expired

LB-DCS RM-FM RM-FM (Heater lock-out)

17. Heater pilot burners Ready for start-up

LB-DCS RM-FM

18. Pilot burner “A” Ready to start

LIP v. LB- DCS RM-FM


Rev 1.00.00 15/25


signal

Alarm Lamp/DCS



19. Pilot burner “A” Start

LIP v. LB- LM-FM

RM-FM Start ignition safety time & ignition transf. and SOV open for pilot burner “A”)

20. Pilot burner “A” ignition running

LIP v. LB-DCS RM-FM

21. Pilot burner “A” gas SOV open command given

LIP v. LB-DCS RM-FM

22. Heater pilot burner header gas SOV´s open command given

DCS RM-FM

RM-FM (Opening of pilot burner header gas SOV´s)

23. Pilot burner “A” remaining ignition time

DCS RM-FM

24. Pilot burner “A” ignition failure

LIP v. LB-DCS RM-FM

25. Number of ignition failures of pilot burner

DCS RM-FM

26. Number of ignition failures of pilot burner = 3

LB-DCS RM-FM RM-FM (Program back to purge)

27. Pilot burner “A” Stop

LIP v. LB-LM-FM

RM-FM (Closing of pilot burner “A” and gas header SOV´s)

28. Main gas burners common start conditions OK

DCS RM-FM

29. Main gas burner “A” Ready to start

LIP v. LB-DCS RM-FM

30. Main gas burner “A” Start LIP v. LB-LM-FM

RM-FM (Opening of main gas burner “A” SOV´s)

31. Main gas burner ”A” SOV open command

DCS RM-FM

32. Main gas burner ”A” SOV open command

LIP v. LB-DCS RM-FM

33. Heater’s main gas burners header SOV’s open command given

DCS RM-FM

RM-FM (Opening of main burner header gas SOV’s)

34. Main gas burner “A” Stop

LIP v. LB-LM-FM

RM-FM (Closing of main burner “A” and header gas SOV’s)

35. Main gas burners Restart inhibit

LIP-LB-DCS RM-FM

36. Remaining blocking time for main gas burners

DCS RM-FM


16/25 Rev 1.00.00


signal

Alarm Lamp/DCS



37. Number of ignition failures of main gas burners

DCS RM-FM

38. Number of ignition failures of main gas burner = 3

LB-DCS RM-FM RM-FM (Heater lock-out)

39. Fuel oil burners common start conditions OK

DCS RM-FM

40. Fuel oil burner “A” Ready to start

LIP v. LB-DCS RM-FM

41. Fuel oil burner “A” SOV open command

LIP v. LB-LM-FM

RM-FM (Opening of fuel oil burner ”A” and header SOV’s)

42. Fuel oil burner “A” SOV open command

LIP v. LB-DCS RM-FM

43. Fuel oil burner “A” SOV close command

LIP v. LB-LM-FM

RM-FM (Closing of fuel oil burner “A” and header SOV’s)

44. Heater “Emergency stop” from control room

MB-RM-FM RM-FM (Heater lock-out)

45. Heater “Emergency stop” from local board

LB-LM-FM LM-FM (Heater lock-out)

46. Heater “Emergency stop” from field

Field-LM-FM LM-FM (Heater lock-out)

47. Heater “emergency stop” command given

DCS RM-FM

48. Heater ESD Stop state

LB-DCS RM-FM

49. Heater gas pressure for pilot burner low

DCS LM-FM LM-FM (Pilot gas burner Stop)

50. Heater fuel gas K.O. drum level high

DCS LM-FM LM-FM (Heater Stop)

51. Heater fuel gas pressure for main burner low

DCS LM-FM LM-FM (Main gas burner Stop)

52. Heater fuel gas pressure for main burner high

DCS LM-FM LM-FM (Main gas burner Stop)

53. Heater main burner fuel gas pressure for gas tight test low/high

DCS LM-FM

LM-FM (Program back to “Heater lock-out” status)

54. Heater’s pilot burner fuel gas filter, diff. pressure high

DCS LM-FM

55. Heater’s main burner fuel gas filter, diff. pressure high.

DCS LM-FM

56. Heater’s fire box pressure high

DCS LM-FM LM-FM (Main burners Stop)

57. Heater’s flue gas outlet temp. high

DCS LM-FM LM-FM (Main burner Stop)


Rev 1.00.00 17/25


signal

Alarm Lamp/DCS



58. Heater’s combustion air for purging flow rate low

DCS LM-FM LM-FM (Purge Stop)

59. Heater combustion air fan run signal and current normal (2oo2)

DCS MCC-CS

MCC-CS (Purge and main burners run condition)

60. Heater’s combustion air flow rate low-low


61. Combustion air damper for burner “A” open/close command

RM-FM (Comb. air damper for main burner “A” Open when main burner start and close when main burner stop)

62. Combustion air damper for main burner “A” open position

DCS LM-FM LM-FM (Heater purge condition)

63. Combustion air damper for main burner “A” close position

DCS LM-FM

LM-FM (Main burner “A” start and trip condition)

64. First main gas burner Start flow rate high

DCS LM-FM LM-FM (First main burner start inhibit)

65. Main gas burners flow control valve in start position

DCS LM-FM LM-FM (First main burner start condition)

66. Pilot burner “A” flame exists LIP v. LB-DCS LM-FM

LM-FM (Permission to start and purge inhibit & Main burner “A” start condition)

67. Main burner “A” flame exists

LIP-LB-DCS LM-FM

LM-FM (Permission to Start and purge inhibit & Main burner “A” run condition)

68. No flame in heater LB-DCS RM-FM

RM-FM (Heater and O2 analyzer Stop & Purge condition)

69. Heater circulation fluid flow rate low


70. Heater circulation fluid pump run signal missing AND current min. (2oo2)

DCS MCC-CS MCC-CS (Main burners Stop)

71. Heater’s circulation fluid outlet temp. high


72. Fuel gas + fuel oil to combustion air flow rate ratio low or high

DCS RM-CS RM-CS (Main burner Stop)


18/25 Rev 1.00.00


signal

Alarm Lamp/DCS



73. Heater damper on the stack open position

DCS LM-FM

LM-FM (Heater start and purge condition)

74. Heater damper on the stack closed position

DCS LM-FM

LM-FM (Heater Stop)

75. Heater SOV closed position (when open command given)

DCS RM-FM RM-FM (Discrepancy alarm)

76. Heater SOV open position (when close command given)

DCS RM-FM

LM-FM (SOV opening discrep. alarm and trip before ignition step)

77. Heater SOV’s stroke tests command

DCS RM-FM RM-FM (SOV stroke test command)

78. Heater SOV’s stroke test failure

DCS RM-FM RM-FM (Actual burner trip)

79. Heater fuel oil burner fuel oil pressure low

DCS LM-FM LM-FM (Fuel oil burner Stop)

80. Heater fuel oil burner fuel oil temperature low


81. Heater fuel oil atomizing steam pressure low


82. Heater fuel oil to atomizing steam dP low


83. Heater fuel oil filter dP high

DCS LM-FM

84. Heater local ignition panel lamp test command

LIP-LM-FM

85. Heater local board lamp test command

LB-LM-FM

86. Heater control room lamp test command

MB-RM-FM

87. Heater dedicated MOS enable command

MB-RM-FM (Key lockable switch)

RM-FM (MOS condition in the related MOS group)

88. Heater MOS command

RM-FM (DCS or Key lockable switch in control room)

RM-FM (Service override of the related sensor)

89. Heater MOS status indication

DCS RM-FM

90. Heater MOS status remaining time indication

DCS RM-FM


Rev 1.00.00 19/25


signal

Alarm Lamp/DCS



91. Heater MOS status periodic alarm (in every 8 hours)

DCS RM-FM

92. Heater dedicated POS command

MB-RM-FM (Key lockable switch)

RM-FM (Override of the related sensor by operator)

93. Heater POS status indication

MB-DCS RM-FM

94. Heater POS status remaining time indication

DCS RM-FM

95. Heater POS status periodic alarm (in every 8 hours)

DCS RM-FM

Abbreviations:

FM = Supplied by the vendor of the heater control system

LM = Field-mounted item

LB = Local control board

LIP = Local ignition panel

MB = Main board (remote control board)

RM = Control room mounted item

CS = Supplied by Client

MCC = Motor control cabinet

DCS = Distributed control system

ICS = Integrated control system

The heater Designer/Vendor determines whether additional measurement and detection point are required for the control system of the heater or some of the above points may be omitted.


20/25 Rev 1.00.00

7.5 Definition of start-up and stop process

Heater start-up, shutdown and operating steps:

It is to be emphasized that the individual application may vary from the steps, conditions and functions listed below. The final solution shall be determined in the basic engineering documentation or project specification.

Step Operator functions Control/Shutdown System functions

1. Press “Heater start-up & operation permission” pushbutton ( Shut-down system activation).

Switch shutdown system to start-up / operating status (activated status).

2. Press “Heater leak test start” pushbutton. Open/close automatic safety shut-off valves in fuel gas line of main burner(s) for leak test.

3. Set up conditions for ”Heater purge”. Fully open manual operated air dampers at each burner register.

Open air control damper or set blower speed at FCD (ratio controller function). Open flue gas damper (DCS function). Open remote operated air on/off dampers.

4. Press ”Purge Start" pushbutton Start purge timer and then purged status timer.

5. Set up conditions for ”Heater pilot burner ignition”. Open the relevant manual pilot gas on-off valves at burner register.

Set combustion air on/off damper to closed ignition position. Set air control damper or blower speed at FCD to ignition position/value (ratio controller function).

6. Press ”Pilot burner ignition” pushbutton and ignite pilot flame(s).

Open automatic safety shut-off gas valves at each pilot burner and ignite pilot flames (in the case of remote electric ignition).

7. Press ”Pilot burner stop” pushbutton. Close automatic safety shut-off valves relevant to pilot burner.

8. Set up conditions for ”Fuel gas main burner ignition”. Open the relevant manual on-off valves at burner register.

Set main burner fuel gas control valve to start-up (start flow rate) position (ratio controller function).

9. Press ”Main fuel gas burner start” pushbutton.

Open the relevant fuel gas automatic safety shut-off valve and combustion air on-off damper (if exist) of main burner(s) and stop the ignition burner. Gradually set air control damper or blower speed at FCD to normal operating position/value (ratio controller function).

10. Set the manual air damper at the relevant burner and the flue gas damper to normal operating position.

Set combustion air to fuel gas ratio to normal operating value corrected on the basis of flue gas O2 content (ratio controller function) and heater draft control (if exist).

11. Periodic function test of automatic safety shut-off valves by partial stroke test.

12. Set up conditions for ”Fuel oil burner ignition”. Open manual on-off valves at the relevant burner, start fuel oil pre-heating, Open atomization steam and set oil lances to operating position.

Set fuel oil pressure & temperature and atomization steam pressure to operating values (DCS function).

13. Press ”Fuel oil burner start” pushbutton. Open the relevant automatic safety shut-off valves of fuel oil burner, gradually modify combustion air control damper or blower speed (by frequency converter) and fuel oil and fuel gas flow to new operating position/value (DCS function).

14. Press ”Fuel oil burner stop” pushbutton. Close the relevant automatic safety shut-off valve of fuel oil burner, gradually modify air control damper or blower speed (by frequency converter) and fuel oil and fuel gas flow to oil burner start position/value (DCS function).


Rev 1.00.00 21/25

Step Operator functions Control/Shutdown System functions

15. Press ”Main fuel gas burner stop” pushbutton.

Close the relevant automatic safety shut-off valves of main burner. Set main burner fuel gas control valve to start-up position. Close the relevant comb. air on-off damper (if exist) and set the comb. air control damper (or set blower speed at FCD) to ignition position and open fully flue gas damper.

16. Press ”Heater emergency stop” pushbutton. Close all pilot & main burner fuel gas and fuel oil automatic safety shut-off valves and step back BMS sequence and control system to “Non volatile lock-out status” preceding start-up and operation.

Note: Pressing the “Heater Emergency Stop” pushbutton shall interrupt any currently ongoing phase of heater operation and the control/shutdown system will step back into the status preceding “Heater start-up & operation ready to start” (Heater non volatile lock-out status).

8 Required documentation to be supplied

8.1. Piping & Instrumentation Diagram (P&ID) indicating the battery limits of the fired heater and its auxiliary systems, the related design & supply limits, all process data (flow, pressure, temperature values), all instruments with process connections, control/shutdown functions and signal connections in compliance with MGS-M-REF-I-10 & MGS-S-REF-I-10 and ISO 3511 requirements as well as the isolation, vent, drain and test valves of all instruments in compliance with API 560 requirements.

8.2. Operating description of the system in sufficient detail for ensuring the safe start-up, stopping and operation of all units and equipment, including the mode of tagname generation and the solution employed for system configurations (in compliance with Specification MGS-M-REF-I-30.2 & MGS-S-REF-I-30.2).

8.3. Cause & Effect Matrix of control and shutdown functions as part of the basic design engineering package, containing all the inputs (from transmitters, limit switches, pushbuttons, selector switches, etc.) as “Cause” by rows and all the final control and actuator elements as “Effect” by columns.

8.4. Narrative of ESD functions (in compliance with Specification MGS-M-REF-I-30.8 & MGS-S-REF-I-30.8).

8.5. Set-values list in tabulated form for the limit switches of alarm, control & shutdown functions and timers (in compliance with Specification MGS-M-REF-I-30.7 & MGS-S-REF-I-30.7).

8.6. Complete Boolean logic diagram (containing all control, shutdown & emergency alarm and status indication functions) of the fired heater and its auxiliary systems (in compliance with Specification MGS-M-REF-I-30.6 & MGS-S-REF-I-30.6). The specifications of ISA Standard S5.2 shall be taken into consideration for the symbols of logic elements.

8.7. Instrument schedule containing in tabulated form the following items as a minimum for each instrument:

Function/Service

Instrumentation items with their main characteristic and parameters, minimum such as; tag name, measuring range, signal range, explosion-proof protection class, set-points, etc. (in compliance with Specification MGS-M-REF-I-30.4 & MGS-S-REF-I-30.4).

8.8. Instrument datasheets according to ISA Standard S20, completed for ordering in compliance with the requirements of the applicable MOL Group guidelines (Specifications MGS-M-REF-I-5, MGS-M-REF-I-30.9, MGS-S-REF-I-5 & MGS-S-REF-I-30.9) on format and contents.

8.9. Sizing calculation sheets (in compliance with ISO Standard 5167-2 for orifice plates, with ISO 5167-4 for Venturi tubes, with manufacturer’s instructions for control valves, etc.).

8.10. Loop drawings (in compliance with Specification MGS-M-REF-I-30.14 & MGS-S-REF-I-30.14).

8.11. Scaled layout drawings of electrical equipment, PLC & marshalling cabinets, local and remote control boards, junction boxes, etc. complete with material take-off lists (in compliance with Specification MGS-M-REF-I-30.11 & MGS-S-REF-I-30.11).

8.12. Terminal assignment diagrams of equipment, control boards and junction boxes.

8.13. Single-line cabling diagrams (in compliance with Specification MGS-M-REF-I-30.15 & MGS-S-REF-I-30.15).

8.14. Cable wiring diagrams (in compliance with Specification MGS-M-REF-I-30.17 & MGS-S-REF-I-30.17).

8.15. Cable schedule (in compliance with Specification MGS-M-REF-I-30.16 & MGS-S-REF-I-30.16).


22/25 Rev 1.00.00

8.16. Routing and cabling diagrams of interconnections between heater site (junction boxes, local control board), control room (equipment, remote control board) and high voltage electrical system, etc. (in compliance with Specifications MGS-M-REF-I-30.18, MGS-M-REF-I-30.19, MGS-S-REF-I-30.18 and MGS-S-REF-I-30.19).

8.17. PLC software documentation (when PLC shutdown system is used) with the minimum contents specified below:

PLC program package (PLC-FLD, diagnostics, application, verification)

Source program of the system supplied

8.18. DCS and PLC I/O list related to the fired heater (in compliance with Specification MGS-M-REF-I-30.25 & MGS-S-REF-I-30.25).

8.19. Grounding system diagram (in compliance with Specification MGS-M-REF-I-30.10 & MGS-S-REF-I-30.10).

8.20. Hook-up drawings (in compliance with Specification MGS-M-REF-I-30.21 & MGS-S-REF-I-30.21).

8.21. Connection drawing of electric power supply for instrumentation & control systems (in compliance with Specification MGS-M-REF-I-30.20 & MGS-S-REF-I-30.20).

8.22. Connection drawings of instrument air supply for instrumentation (in compliance with Specification MGS-M-REF-I-30.22 & MGS-S-REF-I-30.22).

8.23. Schedule of electrical/instrumentation interfaces (in compliance with Specification MGS-M-REF-I-30.23 & MGS-S-REF-I-30.23).

8.24. Schedule of process connections to instrumentation (in compliance with Specification MGS-M-REF-I-30.24 & MGS-S-REF-I-30.24).

8.25. Specification of other erection materials (junction boxes, cables, transmitter boxes, etc.) in compliance with Specification MGS-M-REF-I-30.12 & MGS-S-REF-I-30.12.

8.26. Shop test reports of instrumentation items.

8.27. List of erection materials (in compliance with Specification MGS-M-REF-I-30.13 & MGS-S-REF-I-30.13).

8.28. Un-priced cost estimate (in compliance with Specification MGS-M-REF-I-30.27 & MGS-S-REF-I-30.27).

8.29. Information to be supplied for the Refinery Information (RIS) system, if necessary (in compliance with Specification MGS-M-REF-I-30.28 & MGS-S-REF-I-30.28).

8.30. Spare parts list of instrumentation items.

8.31. Vendor manuals of instrumentation items with the minimum contents specified below:

User Guide

Operating Instructions

Functional block schemes

Circuit & wiring diagrams required for maintenance

8.32. Detailed engineering documentation for construction and as-built documentation satisfying the detailed requirements on contents stipulated in Specification MGS-M-REF-I-8 & MGS-S-REF-I-8 and on format in Specification MGS-M-REF-I-9 & MGS-S-REF-I-9.

Documents required for authority approval issued by competent national notified body based on national statue.

Notes: All documents shall be delivered in the number of copies specified in the supply contract (in the end user language or in English if specially agreed).

9 Instrumentation & shutdown functions of heat recovery systems

The heat recovery systems of fired heaters utilize the heat content of flue gas exiting from the fired heater.

Categories of heat recovery systems:

9.1 Recuperators for combustion air pre-heating

Recuperators for combustion air pre-heating can be used in forced draft fired heaters. Forced flow is ensured by air-side forced air blowers or flue gas side suction fans.

Instrumentation:

Temperature measurement of flue gas at inlet of the heat recovery section

Temperature measurement of flue gas at outlet of the heat recovery section

Temperature measurement of combustion air at inlet of the heat recovery section

Temperature measurement of combustion air at outlet of the heat recovery section

Open-close control of flue gas damper at inlet of heat recovery section and open-closed position indication


Rev 1.00.00 23/25

Open-close control of combustion air damper at inlet of heat recovery section and open-closed position indication

Position indication of damper at suction of combustion air blower(s) switching between inlet from heat recovery section and atmosphere

Bearing temperature, vibration measurement, etc. of combustion air blower(s) (if specified by supplier)

Trip to open position of flue gas damper to stack and trip to close of flue gas damper at inlet of heat recovery section upon high-high flue gas pressure (plugging of heat recovery unit) or high-high & low-low flue gas temperature and stopping of flue gas suction fan when flue gas is routed directly to the stack.

If flue gas pressure or temperature remain at high-high for a preset maximum period even when the flue gas is routed directly to the stack, then the main burner(s) of the heater shall be shut down.

9.2 Steam generating heat recovery boilers

Steam generating heat recovery boilers can be used in forced draft fired heaters. Forced air flow is ensured by air-side blowers or flue gas side suction fans.

Instrumentation

The following functions shall be provided as a minimum in addition to those listed under Item 9.1. above (with the exception of combustion air parameters):

Boiler feed water (BFW) level control and heat recovery boiler shutdown at low-low level based on continuous (analogue) level measurement by means of displacer chamber type (with the correction of the 4-20 mA level transmitter output signal according to steam pressure in the case of medium pressure steam generation) with the installation of level detectors in the number required according to the SIL category and specified availability.

BFW flow measurement

Flow measurement of produced steam (with pressure & temperature compensation)

Pressure control of produced steam

Trip to open position of flue gas damper to stack and trip to close of flue gas damper at inlet of heat recovery section upon high-high steam pressure or low-low BFW level and stopping of flue gas suction fan when flue gas is routed directly to the stack.

Actual measurement, alarm & shutdown signals and control actions shall be finalized during the specification of the technological functions of the fired heater and the heat recovery system.

10 Combustion air blowers and their control system

In the case of forced draft fired (primarily air blast) heaters the combustion air is supplied by air blowers.

10.1 Installation requirements of air blowers

Air blowers shall be sized for ensuring that one (1) blower will be capable of supplying the necessary air flow during normal operation.

Two (2) air blowers shall be installed and both form 100% hot standby spare for each other.

Automatic switching over (auto-start) with overlap shall be ensured for the failure of either air blower if required by the basic design engineering documentation or the project specification.

Remote operated shut-off valves (dampers complete with limit switches) or mechanical one-way damper(s) shall be installed in the discharge lines of air blowers in order to ensure the automatic switching over of air blower and to avoid the reverse rotation of the air blowers.

The automatic switching-over of the air blowers and the control of the discharge side remote operated shut-off dampers shall be designed so as not to result in interruption of air supply to the fired heaters, i.e. not to activate the low-low combustion air pressure and/or low-low air flow shutdown conditions in the burner management and heater control systems. The simultaneous running (overlap) period of the air blowers shall be determined as a function of the actuation time of the shut-off valves. The installation of throttle dampers complete with limit switches (if required) and heated bird screen in the suction ducts of the air blowers shall be in the scope supply.

10.2 Input/output signals and alarms of air blowers to be displayed in the control system

Air blower running signals

Electric failure of air blowers

Air blower current consumption as option


24/25 Rev 1.00.00

Manipulated value for air blowers (only in the case of speed control by frequency converter drive or vane angle regulation)

Limit position alarms for vane angle actuator (only in the case of vane angle regulation)

Common alarm of frequency converter drive (only in the case of speed control by frequency converter drive)

Frequency & speed as option (only in the case of speed control by frequency converter drive)

Start command (only in the case of speed control by frequency converter drive)

Stop command (only in the case of speed control by frequency converter drive)

Remote start enabled signal (only in the case of speed control by frequency converter drive)

10.3 Instrumentation of discharge side dampers of air blowers

Valve open signal

Valve closed signal

Open command for damper as option

Close command for damper as option

11 Appendix

11.1 Standards

STN 06 1950 Industrial gas heating appliances. Technical regulations

STN 06 1510 Air heaters for solid, liquid and gas fuels. General requirements

STN 07 0623 Technical documentation of boilers

STN 07 0624 Erection of boilers and boiler equipment

STN 07 0703 Gas boiler houses

STN 33 2000-4-442 Electrical installations of buildings. Part 4: Protection for safety. Chapter 44: Protection against over voltages. Section 442: Protection of low-voltage installations against faults between high-voltage systems and earth.

STN 33 2000-4-41 Low-voltage electrical installations Part 4-41:Protection for safety Protection against electric shock

11.2 Slovak statutes

Ministry of Labour, Social Affairs and Family of the Slovak Republic: Public notice no. 508/2009 for assuring occupational health and safety at work with pressure, lifting, electric and gas technical equipment, which lays down the technical equipment, considered being dedicated technical equipment.

11.3 Instrument air supply

Pressure range: 0,45-0,6 MPa

Temperature range: 30-45 °C

Dew point: -25°C

Note: The typical characteristics of instrument air supply are specified in the book No.: MGS-M-REF-I-4 & MGS-S-REF-I-4 however the characteristics are refinery and individual heater specific, so the exact characteristics are specified in the project specification.

11.4 Utilities

ad. 7.3 Electric power supply for instrumentation:

230 VAC ±5%, 50 Hz±3% UPS

24 VDC ±5% (convertor 230 VAC/24 VDC powered by UPS)

Field switches: 24 VDC

Solenoids: 24 VDC or 230 VAC UPS

Heat tracing: 230 VAC non-UPS

Lighting: 230 VAC non-UPS


Rev 1.00.00 25/25

MOL Group - Slovnaft · SLOVNAFT a.s. MGS-S-REF-I-21 R&M Division TECHNICAL SPECIFICATION -...

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