Baviera Steam System 11

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     St eam Sys t ems

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     BAVIERA STEAM SYSTEMS

    1.- INTRODUCTION. Drawing BSS sh 08

    The Baviera steam system for corrugators achieves, at the same time, energyefficiency and production flexibility.

    Condesates are recovered with high pressure and temperature, and pumpedback directly to the boiler, achieving this way energy efficiency  optimization(fuel savings).

    Pressures along the corrugator are controlled digitally and remotelly, achievingthis way the necessary flexibility  (production quality & waste reduction). Thisflexibility is especially important with light weight papers and recycled papers

    (difficulties in glue penetration suggests inverse pressure regulation of theDouble Backer)

    Several controls guarantee adecuate condensate drainage under anycircumstance, ensuring optimal heat transfer .

    Due to its conception and to the kind of components used (Spirals, HybridTraps, condensate pump, etc.), the Baviera Steam System is a long lifemaintenance free system.

    2.- HEAT TRANSFER

    The system supplies direct steam to the whole corrugator. There is oneindividual Hybrid Trap or Spiral at each roll or steam chest, in order to optimizeheat transfer - that is to say, to obtain the maximum corrugator heating -.

    2.1.- Double backer. Spirals

    Spirals are robust steam traps with absolutelly no mobile parts and, therefore, along life with no maintenance needs.

    Spirals give a continuous condensate drainage and, at the same time, acontinuos and controlled blowthrough steam flow that ensures a perfectdegasification.

    Please find a detailed explanation of spirals and their functionality further in thedocument.

    2.2.- Single facers and preheaters. Hybrid Traps

    Hybrid Traps are the combined result of Spirals’ and free ball steam traps’evolution. Hybrid Traps are two way traps:

      First way: free ball steam trap

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       Second way: Baviera Spiral

    The combination of the free ball and the Baviera Spiral system results in ahighly efficient steam trap with no maintenance, long life, high energy efficiency

    and optimal heat transfer.

    3.- ENERGY PROFIT. FUEL SAVING

    Baviera Steam Systems are closed steam circuits were condensates arerecovered at high pressure and temperature, achieving energy savings thatround 20% of fuel consumption.

    3.1.- High pressure condensates recovery. CRU

    Baviera Steam Systems include a Condensate Recovery Unit (CRU) thatrecovers condensate with high pressure and temperature, and feeds it backdirectly to the boiler with no energy losses to the atmosphere.

    This equipment provides an aproximate 20% energy saving (fuel saving). TheCRU is normally placed in the boiler room.

     A further description of the CRU equipment and its funcionality is includedfurther in the document.

    3.2.- Double Backer condensates recovery. SPP & TSP

    In order to make compatible the free pressure regulation of the Double Backer(or the Single Facers) with pressurized, closed circuit, condensate recovery,Baviera Steam Systems include electro pneumatic steam pumps (SPP & TSP).

    These steam pumps use life steam to pump condensates from the DoubleBacker or Single Facer, up to the condensate recovery unit CRU.

     A further description of SPP and its funcionality is included further in thedocument.

    4.- FLEXIBILITY

    Baviera Steam Systems give total flexibility to the corrugator, by enabling freepressure regulation with no energy losses to the atmosphere.

    This is particullary important in the Double Backer because of the glue’sdifficulties to penetrate the liner when dealing with light weight papers andrecycled papers.

    This flexibility is some times important in Single Facers too, especially whendealing with light weight papers and small flutes.

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     CONDENSATE RECOVERY UNIT. CRU

    Energy efficiency optimization of steam systems on corrugators demandscondensate recovery at pressure with direct reinjection of condensates to the

    boiler, maintaining their high temperature.

    Since condensates of all rolls and steam chests in a corrugator are purged withvery high temperature and pressure, pressurized recovery of thesecondensates, avoiding their depressurization and its associated cooling down(with flash steam production), is the best way to avoid energy losses,maximizing energy efficiency and, therefore, reducing fuel consumption.

    Baviera condensate recovery system’s design is the result of more than 25years of experience within this field. It is a system that achieves energy profitoptimization and, at the same time, heat transfer optimization, since several

    control systems make compatible both features.

    Moreover, because of the long experience with this kind of systems, allcomponents that make up the condensate recovery unit are robust andpractically exempt from any kind of maintenance.

    The Baviera condensate recovery unit is placed in the boiler house. It has avertical tank, sealed at 18 bar, where condensates are recovered with pressure,around 8 bar, so that condensates are fed to the boiler at a temperature thatrounds 175ºC.

    The KSB pump feeds the boiler from the lower side of the CRU. Although thepump works with high temperature condensates, its natural air cooledmechanical seal, placed far away from the hydraulic, works around 50ºC so thatthe working conditions of the mechanical seal are excellent resulting, in fact, amaintenance free pump with a long lifespan.

    The system has the following controls

    - Level control: 4-20 mA level control acting on the automatic M valve, thatis placed in the pump impulsion. M valve is controlled by condensatelevel in the CRU and, eventually, also by the boiler level, when the signal

    is availiable. The KSB pump works continuously while the M valveregulates the boiler feeding flow.

    - Differential pressure control: There is an electronic and digital differentialpressure control, where you can check and control the differentialpressure of the installation (main steam supply pressure – condensaterecovery pressure).

    The differential pressure control acts on the automatic L valve,guaranteeing that, in any situation, the differential pressure of theinstallation is always higher than the set point, normally set at 4 bar. Thisis the condition that guarantees compatibility between optimal energysaving and optimal heat transfer.

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     - Condensate temperature control: Condensate temperature control acts

    on automatic valve L. It is important during machine start ups and shutdowns. By opening the automatic L valve, during start ups, quickdegasification and cold condensate removal occurs through the Hot Well,

    enabling a quicker heating up of the corrugator. During shut downs,condensate temperature control enables quick depressurization, allowinga quicker drying of the system.

    - Low pressure steam recycling: If there are low pressure steam services(showers, air heating, etc.), the T automatic valve of the CRU suppliessteam coming from the upper side of the CRU for these services.

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     BAVIERA SPIRAL

    Spirals are robust steam traps with absolutelly no mobile parts and, therefore, along life with no maintenance needs.

    In Baviera Steam Systems, each steam chest is provided with an individualBaviera spiral (or with a Hybrid Trap per Hot Plate Section).

    Spirals are specially designed to control a continuous drainage of producedcondensate, together with a controlled blow through steam flow (about 1-2%).This combined flow (condensate and blowthrough steam) guarantees optimaldegasification and, therefore, the highest temperature from heat transfer.

    The mechanism by which Baviera Spirals are able to drain condensate andblowthrough steam in a controlled way, has to do with the length and small

    diameter of the spiral through which condensate has to flow: condensates flowsdue to differential pressure in the installation (main steam pressure –condensate back pressure). The length and small diameter of the spiral acts asa brake or resistance, being this the sole slowing down mechanism of the spiral.

     Although all spirals have the same external dimensions, there are spirals withdifferent lengths and diameters, corresponding to different steam consumptions(spiral sizes).

    In our drawings or layouts, all spiral numbers or sizes are specified for eachparticular point in the corrugator.

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     HYBRID TRAP

     A Hybrid Trap is a combination of one free ball trap and one Baviera spiral.Hybrid Traps are two way traps: the free ball allows condensate to come out

    continuously and the Baviera spiral regulates the desired blow through steam.

    Rolls in single facers turn at machine speed, so contained condensate is liableto centrifugation. In spite of having the siphon or internal pipe for condensatecollection correctly positioned, it is, in any case, liable to experience smallvibratory movements that often will take it away from its right position. Thisvibrations make the siphon to be continuously taking in, together, condensateand steam. Under this circumstances, a conventional drainage (designed forcondensate removal and cold air removal, not steam) would experience asteam blocking, what would increase the inner condensate ring thickness.

    The integrated spiral of the Hybrid Trap provides a blowthrough steam (around5% of its roll steam consumption) that removes this steam “parcels”, avoidingsteam blockings and the corresponding decrease in heat transfer, that is to say:

    Hybrid Traps allow faster heating of the rolls, quicker changes in their regulatedpressure and bigger flexibility upon different production conditions leading,therefore, to higher heat transfer and higher energy efficiency.

    (DUCTILE CAST IRON FLANGED)

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     (STAINLESS STEEL SCREWED)

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     (STAINLESS STEEL FLANGED)

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     DOUBLE BACKER CONDENSATE RECOVERY. SPP

    The use of steam pumps for condensate recovery in the hot plates sections

    makes compatible condensate recovery in closed circuit with totally freepressure regulation in each Hot Plates Section.

    The operation of an electro-pneumatic steam pump is very easy:

    When the level controller detects condensate has reached the maximum levelof the tank, the injection valve (VI) opens and pushes, with life steam,condensate through a check valve to the high pressure condensate recoveryunit. This injection cycle lasts around 5-10 seconds and the filling cycle around3-7 minutes (depending on the Hot Plates Section and on the regulatedpressure, production speed and other parameters).

    Just after the injection cycle (that lasts 10 seconds), the recipient or tank istotally emptied and the decompression valve (VD) opens during 5 seconds inorder to decompress the tank and start again a new filling cycle, filling the tankwith condensates coming from the corresponding hot plates sections.

    Furthermore, there is a degasification spiral (spiral nº 25) that continuouslyallows the incondensable gases deareation.

    Therefore, the condensate recovery system with electro-pneumatic steam pump

    works as per the following cycles (these times may change from plant to plant):

    - Cycle nº 1: Filling of the recipient, lasting for 3 to 7 minutes.- Cycle nº 2: Pumping with life steam, lasting for 5 to 10 seconds.- Cycle nº 3: Decompression, lasting for 5 seconds.- The complete cycle starts again.

    The system has a VE valve whose only aim is to deviate the condensates fromthe hot plates sections up to the atmospheric condensate recovery at nightwhen the steam supply to the corrugator is closed, or in the morning, duringstart ups, when a minimum pressure has not been reached yet.

    The whole process is electrically and digitally controlled by a PLC. Thematerials used (check valves, VI, VD, spirals) are of good quality and with noneed of maintenance, so that a system which is apparently complex - as itconsists of several condensate recovery units - , is indeed a system free ofmaintenance and without erosion because of time.

    You can find further information on Baviera SPP, in the following explanationvideo: http://www.rbaviera.com/SPPmovie.pps 

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    STEAM PUMPS FOR SINGLE FACERS. SPPSF

    When dealing with light weight papers and especially with small flutes, it isconvenient (it can even be indispensable) to regulate pressure in the Single

    Facers.

    The use of electro pneumatic steam pumps for condensate recovery in SingleFacers makes compatible closed circuit condensate recovery at pressure withtotally free pressure regulation in Single Facers.

    The operation of an electro-pneumatic steam pump is very easy:

    When the level controller detects that condensate in the injection tank hasreached its maximum level, injection valve (VI) automatically opens and pushescondensate, with life steam, to the Condensate Recovery Unit (boiler house)

    through the high pressure condensate recovery.

    While life steam injection is taking place, the aspiration tank buffers comingcondensate. If, after having ended the injection cycle, condensate in theaspiration tank reaches its maximum level, the decompression valve (VD)opens during 5 seconds in order to decompress the condensate tank andenable condensate flow from the aspiration tank to the condensate tank.

    Furthermore, there is a degasification spiral in each tank that continuouslyallows the air and rest of incondensable gases deareation.

    Therefore, the condensate recovery system with electro-pneumatic steam pumpworks as per the following cycles (these times may change from plant to plant):

    - Filling cycle: 2 to 7 minutes.- Injection cycle: 5 to 10 seconds.- Decompression cycle: 3 to 5 seconds.- The filling cycle starts again.

    This equipment has a VE valve whose only aim is to deviate the condensatesfrom the single facer up to the atmospheric condensate recovery at night whenthe steam supply to the corrugator is closed, or in the morning during start ups

    when a minimum pressure in the steam supply has not been reached yet.

    The steam pump for single facer has an active control of the differentialpressure between the single facer and the aspiration tank. The differentialpressure control eventually acts over the VD valve, in case it falls below the setpoint.

    The whole process is electrically and digitally controlled by a PLC. Thematerials used (check valves, VI, VD, pressure differential transmitter, spirals,etc.) are of good quality and with no need of maintenance.

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    STEAM PUMP FOR SINGLE FACER

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     HEAT TRANSFER PROCESS CONTROL

    Work with recycled and light papers, very sensitive to heat, makes almostnecessary a close control of temperatures in the corrugating process in order to

    achieve optimization of all production qualities.

    Moreover, paper overheating must be avoided, for economy and qualityreasons. This is possible through an active temperature control system, such asthe following described:

     A central processing unit monitorizes and controls the main temperatures of thecorrugating process, measured through infrared transmitters, and shows themthrough local and remote screens. The systems keeps critical temperaturesalong the corrugating process in their set point, acting on the rolls’ wraps andregulating pressures (when wrap control isn’t possible or enough).

    Recipes can be stored in the system in order to automatically reproduce certainproduction conditions, by simply loading a production program from the system.Historical graphs are stored in order to keep close control of productiontemperature parameters. All the system is controlled from the control cabin andfrom the local screens. The system is prepared to allow remote upgrades of thesystem’s software through remote connections.

    Please find below an orientation list showing some papers’ best productiontemperatures, and a second screen showing the points of the corrugatingpressure where temperatures are measured and controlled. For further

    information, please contact us on [email protected] or +34 96 155 37 48.

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