Psa Operating Manual

PSA

(A Simplified Process Manual)

1.1 Introduction:

The UOP poly-bed unit uses Pressure Swing Adsorption process to purify raw hydrogen feed to produce 99.99% pure hydrogen. The raw hydrogen feed consists of methane, CO and ethylene as the main impurities which are removed in the process and returned as reject gas to either fuel gas or flare as desired.

The poly-bed unit consists of 4adsorber beds (1D74A

to D), a reject gas surge drum (1D75), and a control system consisting of automatic valve skid controlled by PLC through a user interface Vijeo Citect. The adsorbers use layers of two different adsorbents viz. H1 and H2-10.

The PSA adsorbent H1 loaded at the top is known as

Zeolite which primarily consists of Calcium Oxide, Sodium Oxide, Aluminum Oxide and Silicon Oxide. The H2 adsorbent which constitutes the bottom layer is Activated Charcoal / Carbon.

1.2 Design:

The unit is designed to run with either 4Beds or 3Beds inline. The 3Bed mode is provided to enable maintenance of any bed while keeping the unit in operation to improve the reliability of the unit. While the purity in both the cases remains the same, the % recovery decreases from 65% in 4Bed mode to 57% in 3Bed mode. The unit is capable of producing pure hydrogen from zero to design feed flow rates. Similarly the % recovery is maintained from 100% of design feed flow rates to as low as 25%, below which the % recovery drops slightly.

Below table lists the design data for 4Bed and 3Bed mode operation. 4 Bed mode 3 Bed mode Raw H2 Pure H2 Reject

Gas Raw H2 Pure H2 Reject

Gas H2 83.65 99.99 64.17 83.65 99.99 68.75 CO 0.04 < 1 ppm 0.09 0.04 < 1 ppm 0.08 N2 0.07 0 0.15 0.07 0 0.13 CH4 16.03 < 100 ppm 35.12 16.03 < 100 ppm 30.63 C2H2 0 0 0 0 0 0 C2H4 0.20 0 0.45 0.20 0 0.39 C2H6 0.01 0 0.02 0.01 0 0.01 C3+ traces 0 traces traces 0 Traces Design Flow Nm3/hr

20379 11081 9298 20451 9752 10699

Normal Flow Nm3/hr

16711 9087 7624 16770 7996 8773

Min. Flow Nm3/hr

5706 3103 2603 5726 2730 2996

1.3 General Description: The pressure swing adsorption process involves adsorption of

impurities at high pressure and desorption at low pressure. The process operates on a repeated cycle basis consisting of adsorption and desorption steps without temperature changes apart from those caused by heat of adsorption and desorption. At any given point of time (except for the 1sec overlapping period during bed switchover), only one bed is always in adsorption while the others are at various steps of regeneration.

1.3.1 Subcycles and Steps:

Each adsorber is led through the same cycle of adsorption and desorption steps. A complete cycle is divided into 4subcycles in 4Bed mode and 3subcycle sin 3Bed mode. And each subcycle is further divided into 6steps. Cycle: A cycle can be defined as the time period between the start of adsorption by a bed and the time the same bed comes into adsorption again, i.e. it includes adsorption, depressurization, purging and repressurizaton steps of any given bed. Subcycle: It is the period between the end of adsorption of two consecutive beds, i.e. total adsorption time of any bed minus the overlapping period. Step: A subcycle is divided into 6steps in both the 4Bed and 3Bed modes. When step 1 ends the unit switches to step 2, etc. After completion of step6 in one subcycle the process continues to step 1 of the next subcycle. Note: The subcycle following subcycle 4 in 4 bed mode and 3 in 3bed mode is subcycle1.

1.3.2 Valve Numbering system: The valves are numbered as per the following scheme. E.g.: XV 8951 A (raw hydrogen feed valve of adsorber A) XV : Refers to valve symbol 895 : The first three digits are common for all the valves

1 : The last digit refers to the valve function 1 for hydrogen feed valve 2 for pure hydrogen valve 3 for purge / equalization valve 4 for reject gas valve A : Refers to the adsorber to which the valve belongs to.

1.3.3 4Bed operation description:

Adsorber A is taken as reference to explain the various subcycles and steps that it undergoes in a complete cycle. The sequence by which the adsorbers come on adsorption is D74A -> B-> C-> D-> A and the cycle repeats itself. Each of the adsorbers follows the same subcycles and steps. The staggering of adsorbers ensures an uninterrupted supply of pure hydrogen.

The times mentioned in the illustration refer to the unit operating in 4 bed mode at design conditions. A complete cycle involves three major processes, a. Adsorption b. Regeneration: At the end of adsorption, adsorber would be loaded with impurities. The regeneration of the adsorber includes the following sequence.

- As the feed flow direction is from bottom to top the impurities are highest at the bottom and decreases towards the top of the vessel. Hence the top portion of the vessel contains a lot of pure hydrogen which can be recovered from being lost into the reject gas system. This is achieved by depressurizing the system in the direction of feed flow. The depressurizing gas is used to

1. Initially repressurize the other adsorbers 2. To purge the other adsorbers.

- As the bed gets depressurized the impurities from the bottom of the bed moves towards to the top. The depressurization is terminated as the impurities reach the top of the adsorber. At this moment the flow direction is reversed and the vessel is depressurized in the downward direction to reject gas pressure. Parts of the impurities are desorbed during this depressurization and are removed into the reject gas system.

- The adsorber is further regenerated by purging it with pure

hydrogen coming form another adsorber. The remaining impurities are sent to reject gas system during this step.

c. Repressurization: After the regeneration the bed is brought back to

adsorption pressure in two steps;

a. With pure hydrogen from another adsorber in its initial depressurization stage.

b. Later with hydrogen from the product header. c.

A detailed step wise description of the adsorption, regeneration and

repressuirzation cycle of an adsorber follows. The values of timers correspond to design conditions.

1.3.4.1 Step 1.1 through to Step1.6 (Adsorption): Time duration 160secs. Raw hydrogen enters D74A from the bottom of the adsorber through

XV-8951A (feed On/Off valve). All the impurities are selectively adsorbed on to the adsorbents and pure hydrogen flows into product line form the top of the bed through XCV-8952A (product control valve). The bed A remains in adsorption throughout subcycle1 (steps 1.1 to 1.6). End of step1.6 marks the end of adsorption period of Bed-A.

1.3.4.2 Step 2.1(Delay Timer-1): Time duration 1sec.

This delay timer is introduced to allow Adsorber A to switch from

adsorption stage to equalization stage-1.

1.3.4.3 Step 2.2 (Equalization-1-provide): Time duration 50secs. This is the first step of depressurization during which the pressure in

Adsorber A (from 36.2 to 22.5 Kg/cm2g) is used to repressurize (from 4.3 to 22.5Kg/cm2g) Adsorber C. The gas flows out of the top of Bed A through XCV-8953A to Bed C through XCV-8953C. The equalization-1 ends when both the beds reach a pressure of 22.5Kg/cm2g.

1.3.4.4 Step 2.3 (Isolation): Time duration 13secs.

In this step Adsorber A remains isolated with all the valves in closed

position. Essentially in this step the Bed A is idle but is provided to allow Bed-D to finish its dump step and make it available to receive purge from Bed A.

1.3.4.5 Step 2.4 (Providing Purge): Time duration 96secs.

This is the second step of depressurization during which the pressure

in Adsorber A (from 22.5 to 10.5 Kg/cm2g) is used to purge Adsorber D (at 4.3kg/cm2g). The gas flows out of the top of Bed A through XCV-8953A to Bed C through XCV-8953D. The provide purge step ends when both the Bed A reach a pressure of 10.5Kg/cm2g. The dump valve of Bed D switches from controlled open to full open at the end of this step.

1.3.4.6 Step 2.5 (Delay Timer-5): Time duration 1sec.

In this step Bed A gets isolated with all the valves in closed position.

The end of timer -5 also marks the end of repressurization of Bed C.

1.3.4.7 Step 2.6 (Delay Timer-6): Time duration 1sec. This timer allows both Bed B and C to be on Adsorption so as to

ensure bump less switchover.

1.3.4.8 Step 3.1 through to 3.3 (Depressurization to reject gas system / Dump): Time duration 64secs.

Bed A after providing pure H2 to other beds in equalization and

provide purge step is mostly left with impurities. The bed is therefore depressurized towards bottom to a pressure of 4.3Kg/cm2g through XCV-8954A. At the ned of step the pressure in the bed is +/_ 0.5kg/cm2g of the reject gas surge drum pressure. Some of the impurities are desorbed and sent to reject gas system during this process.

1.3.4.9 Step 3.4 (Purge): Time duration 94secs.

Adsorber A is purged by pure hydrogen coming from Bed B through

XCV-8953B and entering Bed A through XCV-8953A. The impurities are purged off and sent to reject gas system through XCV-8954A. The dump valve remains full open to minimize any pressure losses.

1.3.4.10 Step 3.5( Delay Timer-5): Time duration 1sec

The end of timer -5 marks the end of repressurization of Bed D. Bed

A dump valve remains fully closed in this step having completed purge step. However the equalization valve XCV-8953A goes fully open waiting for H2 to commence repressurization.

1.3.4.11Step 3.6 (Delay Timer-6): Time duration 1sec.

This timer allows both Bed C and D to be on Adsorption so as to

ensure bump less switchover.

1.3.4.12 Step 4.1 (Delay Timer-1): Time duration 1sec. This delay timer is introduced to allow Adsorber C to

switch from adsorption stage to equalization stage-1. However Bed A product control valve XCV-8952A opens slightly to allow a small stream of pure hydrogen to aid the pressurization of Bed A. The opening is capacity dependant and remains fixed.

1.3.4.13 Step 4.2 (Equalization -1-receive): Time duration 50secs.

This is the first step to repressurize Bed A through H2

received from Bed C. Hydrogen flows from Bed C through XCV-8953C to Bed A through XCV-8953A. However a small stream of hydrogen from the product header continues to flow through XCV-8952A. The end of equalization is brought about with Beds A and C reaching a pressure of 22.5Kg/cm2g.

1.3.4.14 Step 4.3 through to 4.5 (Repressurization): Time duration 109secs.

This is the second and final stage of repressurization where in

the hydrogen taken from the product header through XCV-8952A is used to pressurize the Bed A to reach the adsorption pressure. The rate of repressurization is controlled as a function of subcycle time.


This timer allows both Bed D and A to be on Adsorption so

as to ensure bump-less switchover. The feed XV-8951A and product XCV-8952A goes full open in this step.

As a reference, comparative timer values are provided for design and present operating conditions. However the present conditions shall change with change in capacity and Kf (which is normally kept constant). The present operating conditions used to illustrate the timers are,

Feed : 6.7 KNM3/hr

Kf : 780 Step No.

Operation Design Timers (in secs)

Present Timers (in secs)

1.1 Adsorption 160 306 1.2 1.3 1.4 1.5 1.6 2.1 Delay Timer-1 1 1 2.2 Equalization provide 50 65 2.3 Isolation 13 70 2.4 Provide Purge 94 168 2.5 Delay Timer-5 1 1 2.6 Delay Timer-6 1 1 3.1 Dump 64 136 3.2 3.3 3.4 Purge 94 168 3.5 Delay Timer-5 1 1 3.6 Delay Timer-6 1 1 4.1 Delay Timer-1 1 1 4.2 Equalization receive 50 65 4.3 Repressurization 109 240 4.4 4.5 4.6 Delay Timer-6 1 1

1.3.5 Differences in 4Bed and 3Bed operations:

The cycles in 4 and 3bed operations are similar except for the source of hydrogen that is used for purging and repressurization. The major differences are tabulated below.

Operation 4 Bed mode 3 Bed mode Provide purge Hydrogen is taken from

the depressurizing adsorber

Hydrogen is taken form the product header. There is no providing purge step.

Sequence Adsorption is followed by equalization and then isolation

Adsorption is followed by isolation and then equalization.

Dump Dump is done from 10.5 to 4.3 Kg/cm2g

Dump is done from 22.9 to 4.3 Kg/cm2g

Pressure stage at 10.5 Kg/cm2g

This is the pressure at which depressurizing switches form provide purge to dump.

This pressure stage does not exist.

Equalization: Receive and provide

The bed receives and provides with the 3rd bed during equalization steps.

While the bed equalizes with the 3rd bed while providing pressure it equalizes with the immediate bed while receiving.

1.3.6 3-Bed operation description: Adsorber A is taken as reference to explain the various subcycles

and steps that it undergoes in a complete cycle. Bed D is considered to be offline. The sequence by which the adsorbers come on adsorption is D74A -> B-> C-> A and the cycle repeats itself. Each of the adsorbers follow the same subcycles and steps. The staggering of adsorbers ensures an uninterrupted supply of pure hydrogen. The times mentioned in the illustration refer to the unit operating in 3 bed mode at design conditions.

1.3.6.1 Step 1.1 through to Step1.6 (Adsorption): Time duration 216 secs.

Raw hydrogen enters D74A from the bottom of the adsorber through

XV-8951A (feed On/Off valve). All the impurities are selectively adsorbed on to the adsorbents and pure hydrogen flows into product line form the top of the bed through XCV-8952A (product control valve). The bed A remains in adsorption throughout subcycle1 (steps 1.1 to 1.6). End of step1.6 marks the end of adsorption period of Bed-A.

1.3.6.2 Step 2.1 to 2.2 (Isolation): Time duration 86secs.

Bed A having completed adsorption step remains isolated with all

valves in closed position waiting for Bed C to be purged.

1.3.6.3 Step 2.3 (Equalization-provide): Time duration 46secs. This is the first step of depressurization during which the pressure in

Adsorber A (from 36.2 to 22.9 Kg/cm2g) is used to repressurize (from 4.3 to 22.9Kg/cm2g) Adsorber C. The gas flows out of the top of Bed A through XCV-8953A to Bed C through XCV-8953C. The equalization-1 ends when both the beds reach a pressure of 22.5Kg/cm2g.


This delay timer enables Bed A to close on equalization valve at the

end of equalization step and to prepare for the second step of depressurization i.e. dump.

1.3.6.5 Step 2.5 (Dump): Time duration 82secs. Part of the impurities gets desorbed in this step as the bed A is

depressurized to reject gas system from the bottom through XCV-8954A. The bed is depressurized from 22.9 to 4.3 Kg/cm2g in this step.

1.3.6.6 Step 2.6 (Delay Timer-6): Time duration 1sec

During this step the dump valve of Bed A goes to full open from controlled open to ensure complete depressurization. This delay timer allows Beds B and C to remain parallel in adsorption to enable bump less switchover form B to C.

1.3.6.7 Step 3.1 (Purge): Time duration 85secs.

Bed A is purged with pure hydrogen from the product header

towards the bottom. The pure hydrogen valve XCV-8952A is capacity open (fixed opening) while the dump controller XCV-8954A remains full open to minimize the pressure losses.


As the Bed A finishes its purge step, this timer allows the dump

control valve to close and prepare the bed for repressurization.

1.3.6.9 Step 3.3 (Equalization-receive): Time duration 46secs. This is the first step to repressurize Bed A through H2 received from

Bed B. Hydrogen flows from Bed B through XCV-8953B to Bed A through XCV-8953A. However a small stream of hydrogen from the product header continues to flow through XCV-8952A. The end of equalization is brought about with Beds A and B reaching a pressure of 22.9Kg/cm2g.

1.3.6.10Step 3.4 (Delay Timer-4): Time duration 1sec.

This timer allows the bed A to switch form equalization step to

repressurization step. The equalization valve XCV-8953A is closed, while the product control valve XCV-8952A remains capacity open.

1.3.6.11Step 3.5 (Repressurization): Time duration 82secs.

This step marks the final repressurization to adsorption pressure.

Pure hydrogen from product header enters through XCV-8952A, which

changes to controlled open (variable) from capacity open (fixed open). At the end of this step the pressure in Bed A reaches the adsorption pressure.


This step essentially brings Bed A to adsorption alongside Bed C to

enable bump less switchover of beds.

1.4 Timers: The PSA logic uses different timers as mentioned above to mark the

end of a particular step. The logic would allow step advance only when a particular process condition is reached within a preset timer value. However due to the difference in the duration of cycle time and the operational sequence between 4 and 3 Bed modes the timers are defined differently in these cases. Some of these are constant while the others are calculated based upon the overall cycle time.

1.4.1 4 Bed mode timers: The following timers are relevant when PSA operates

in 4Bed mode. a. Timer-1 (Delay Timer): This is a constant timer which allows a bed

in adsorption to close the feed and product valves and prepare itself for equalization-provide step.

b. Timer-2 (Equalization Timer): This timer is set to ensure that the

equalization of pressure in the beds is complete. The time out of this timer closes the equalization valves of both the beds.

c. Timer-3 (Dump Timer): The dump step is terminated at the time out

of timer 3 and the pressure in the adsorber reaching +/- 0.5 Kg/cm2g of reject gas surge drum. This timer is set as a fixed fraction of subcycle time.

d. Timer-4 (Purge Timer): The purge is terminated when the pressure

of the bed providing purge reaches 10.5Kg/cm2g. The purge flow and hence the timer are capacity controlled and hence are a function of subcycle time.

e. Timer-5 (Delay Timer): It is the difference between the completion of purge and repressurization timers. The time out of this timer is one of the prerequisites to signal the end of repressurization step.

f. Timer-6 (Delay Timer): This is a constant timer which enables two

beds to be online to ensure a bump less switchover.

g. Timer-7 (Repressurization Timer): This signals the end of

repressurization of the incoming bed. This is capacity dependant and hence is a function of subcylce time.

1.4.2 3 Bed mode timers: The basic difference between 4bed and 3Bed timers is that, while

the 4bed mode has separate timers for dump and repressurization steps, the same are merged into one in 3 Bed mode. The sequence of timers also stands different. The significance of the timers however remains the same.

a. Timer-1: Purge Timer (Capacity Controlled) b. Timer-2: Delay Timer (Constant) c. Timer-3: Equalization Timer d. Timer-4: Delay Timer (Constant) e. Timer-6: Delay Timer (Constant) f. Timer-7: Dump + Repressurization (Capacity controlled) Note: There is no Timer#5 in 3Bed mode of operation. Valve Sequence Charts: Following charts are made available for reference.

a. Valve sequence charts for 4 Bed and 3 Bed mode of operation with A/B/C/D beds out is enclosed for reference.

b. Prerequisite conditions for step advance in 4 Bed mode.

4 Bed Mode

1.1 1.2 1.3 1.4 1.5 1.6 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6 4.1 4.2 4.3 4.4 4.5 4.6Time in secs 1 50 13 94 1 1 1 50 13 94 1 1 1 50 13 94 1 1 1 50 13 94 1 1

Delay T1 T1 T1 T1Eqln 1 T2 T2 T2 T2Dump T3 T3 T3 T3Purge T4 T4 T4 T4 Delay T5 T5 T5 T5Reprn T7Delay T6 T6 T6

XV-8951AXV-8952AXV-8953AXV-8954A

XV-8951BXV-8952BXV-8953BXV-8954B

XV-8951CXV-8952CXV-8953CXV-8954C

XV-8951DXV-8952DXV-8953DXV-8954D

Legend:Fully Open

Capacity Open

Controlled Open

T7 T7 T7

3-Bed (Bed A out)

1.1 1.2 1.3 1.4 1.5 1.6 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6Time in secs 85 1 46 1 82 1 85 1 46 1 82 1 85 1 46 1 82 1

Purge T1 T1 T1Delay T2 T2 T2Eqln 1 T3 T3 T3Delay T4 T4 T4

Dump+ Repress T7 T7 T7Delay T6 T6 T6

XV-8951BXV-8952BXV-8953BXV-8954B

XV-8951CXV-8952CXV-8953CXV-8954C

XV-8951DXV-8952DXV-8953DXV-8954D

Legend:Fully Open

Capacity Open

Controlled Open

3 Bed Mode (Bed B Out)

1.1 1.2 1.3 1.4 1.5 1.6 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6Time in secs 85 1 46 1 82 1 85 1 46 1 82 1 85 1 46 1 82 1



XV-8951AXV-8952AXV-8953AXV-8954A

XV-8951CXV-8952CXV-8953CXV-8954C

XV-8951DXV-8952DXV-8953DXV-8954D

Legend:Fully Open

Capacity Open

Controlled Open

3 Bed Mode (C Out)

1.1 1.2 1.3 1.4 1.5 1.6 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6Time in secs 85 1 46 1 82 1 85 1 46 1 82 1 85 1 46 1 82 1



XV-8951AXV-8952AXV-8953AXV-8954A

XV-8951BXV-8952BXV-8953BXV-8954B

XV-8951DXV-8952DXV-8953DXV-8954D

Legend:Fully Open

Capacity Open

Controlled Open

3 Bed Mode (C Out)

1.1 1.2 1.3 1.4 1.5 1.6 2.1 2.2 2.3 2.4 2.5 2.6 3.1 3.2 3.3 3.4 3.5 3.6Time in secs 85 1 46 1 82 1 85 1 46 1 82 1 85 1 46 1 82 1



XV-8951AXV-8952AXV-8953AXV-8954A

XV-8951BXV-8952BXV-8953BXV-8954B

XV-8951CXV-8952CXV-8953CXV-8954C

Legend:Fully Open

Capacity Open

Controlled Open

36.2

22.5

10.5

4.3

Ads

orbe

r 1

-D 7

4 A

ADSORBTION

PURGE

REPRESSURISISOLATION

PROVIDING PURGE

DUMP

4.3

22.5

36.2

10.5

Ads

orbe

r 1

-D 7

4 B

ADSORBTION

PURGE

REPRESSURISATION

ISOLATIONPROVIDING PURGE

DUMP

10.54.3

22.5

36.2

Ads

orbe

r 1

-D 7

4 C

ADSORBTION

PURGE

REPRESSURISATION

ISOLATION

PROVIDING PURGE

DUMP

36.2

22.5

10.54.3A

csor

ber

1-D

74

D

ADSORBTION

PURGE

REPRESSURISATION

ISOLATIONPROVIDING PURGE

DUMP

A

BC D C

A A

A

C

C

B

B B

D D

D

4 Bed Mode

36.2

22.9

4.3

Ads

orbe

r 1

-D 7

4 W

4.3

22.9

36.2

Ads

orbe

r 1

-D 7

4 Y

36.2

22.9

4.3Ads

orbe

r 1

-D 7

4 Z

PROVIDING ISOLATIO

DUMP

PUR

REPRESSURIS

ADSORBTIO

ADSORBTIO

ADSORBTIO ISOLATIO

ISOLATIO

DUM

DU

PUR

PUR

REPRESSURISA

REPRESSURISPROVIDING

PROVIDING

W

YZ

WY

Z

3 Bed Mode

Step End of step condition required for step advance

1.1 Delay timer T1 of 1sec 1.2 Equalization timer T2 of 50sec ( BedB & D)1.3 PT-8963 ( 10.5 to reject gas +/- 0.5 pressure) and T31.4 PT-8964 ( 22.5 to 10.5) and T41.5 PT-8962 ( E1 end to product pressure) & T7 ; Delay timer T51.6 Delay Timer T6 of 1sec2.1 Delay timer T1 of 1sec 2.2 Equalization timer T2 of 50sec ( BedA & C)2.3 PT-8964 ( 10.5 to reject gas +/- 0.5 pressure) and T32.4 PT-8961 ( 22.5 to 10.5) and T42.5 PT-8963 ( E1 end to product pressure) & T7 ; Delay timer T52.6 Delay Timer T6 of 1sec3.1 Delay timer T1 of 1sec 3.2 Equalization timer T2 of 50sec ( BedA & C)3.3 PT-8961 ( 10.5 to reject gas +/- 0.5 pressure) and T33.4 PT-8962 ( 22.5 to 10.5) and T43.5 PT-8964 ( E1 end to product pressure) & T7 ; Delay timer T53.6 Delay Timer T6 of 1sec4.1 Delay timer T1 of 1sec 4.2 Equalization timer T2 of 50sec ( BedA & C)4.3 PT-8962 ( 10.5 to reject gas +/- 0.5 pressure) and T34.4 PT-8963 ( 22.5 to 10.5) and T44.5 PT-8961 ( E1 end to product pressure) & T7 ; Delay timer T54.6 Delay Timer T6 of 1sec

2.1 Controllers and Control Logic: The control logic includes capacity time control. The capacity control,

controls subcycle time and inturn controls the repressurization time, dump time and purge times. The reject gas flow automatically adjusts to raw hydrogen feed rate.

Capacity signal:

The actual feed flow signal (FT-3101) is taken every second and is

scaled to the range of the flow transmitter and dampened. An average signal is calculated per subcylce. It is protected by a minimum and maximum value.

Subcycle Time:

The capacity signal obtained as above is used to calculate the subcycle

time and the long adsorption time alarm and shutdown values. However the operator can influence the subcycle time by changing the capacity factor Kf. Kf can be varied between 500 and 1500 in steps of 50. Increasing Kf increases subcycle time and vice versa. The unit is protected by a minimum and maximum subcycle time.

Manual Time:

In this mode the operator can fix the adsorption time, independent of

Kf and feed flow rate. PSA has 3 internal and 1 external controllers. All the beds use the same set of controllers although the valves receiving the signal defer relevant to the step and the state of the adsorber. However no two adsorbers use the same controller simultaneously for the same purpose.

c. Internal Controllers:

There are three internal controllers in the unit. These switch from manual to Auto (with remote set point governed by PLC) and back. The switchover is a function of step number. (1) Repressurization Controller:

This controller is in manual mode in steps n.1, n.2 & n.6 (n is the

subcycle number). During these steps the product control valve XCV-8952 A/../D of the bed in repressurization stays on manual at a fixed output governed by capacity control. During steps n.3, n.4 and n.5 the loop switches to auto. The remote set point is calculated as a function of repressurization time.

Set point: The starting set point is the end pressure of equalization-1 of the repressurizing adsorber. The set point increases to product pressure at the end of repressurization time. (Note: the product pressure is indicated by PT-3117 and incase of failure of this transmitter the pressure of adsorber inline will be considered as the set point)

PV: The pressure signal of the bed being repressurized. Output: XCV-8952 of the repressurizing adsorber would receive this output.

(2) Dump Controller:

The dump time is a fraction of adsorption time and is protected by a

minimum value. Dump takes place during steps .1, .2, .3.and the controller is in Auto during these steps.

Set point: The remote set point is calculated as a function of the

running dump time. The starting set point is the pressure of the dumping adsorber and it ramps down to surge drum pressure at the end of dump.

PV: The pressure signal of the bed dumping. Output: The output signal goes to XCV-8954 of the bed under

dumping. (3) Purge Controller:

The purge time is a fraction of adsorption time and is

protected by a minimum value. Dump takes place during step .4 and

the controller is in Auto during this step. During purge XCV-8954 of the receiving adsorber is in fully open position.

Set point: The remote set point is calculated as a function of the

running purge time. The starting set point is the pressure of the providing purge adsorber and it ramps down to end of providing purge pressure at the end of purge.

PV: The pressure signal of the bed providing purge. Output: The output signal goes to XCV-8953 of the providing and

receiving purge adsorbers.

d. External Controller: The reject gas controller falls under this category. The Control of the

reject gas pressure remains unchanged irrespective of switchovers. It controls the reject gas flow to fuel gas. It is calculated as a function of the surge drum pressure taken during step-6 (the lowest pressure within a subcycle) and subcycle time. The controller can be operated in manual /in auto with flow set point / in cascade with flow in cascade with pressure.

Note: The initial openings of XV-8952 of the repressurizing adsorber during equalization-1 and valves controlling providing purge and dump are capacity dependant. These are calculated by the control system as a function of operating conditions.

PSA CONTROL SYSTEM 3.1 General:

PSA is controlled through a fully redundant MODICON PLC

system. The SCADA system is designed as a human interface to operate the PLC. The SCADA is built using Vijeo Citect SCADA software version 6.1.

This manual gives information on,

a. Screen Displays b. Functional Keys ( Soft Switches) c. Operating instructions d. Access controls

3.1.1 SCADA login and navigation: It is designed to give access as per the user

class as per the following. Administrator: Can make any changes in the system including software configuration. Supervisor: Can make PID controller settings. Operator: Can read all information and trend configuration. Logon into the system with the appropriate login as per user access level. Once into the navigation page, one can access information with the help of keyboard shortcut keys or by using the menus. The different menus are pages, trends, alarms, files and tools. The content of each is shown in the sample diagram.

3.2 Screen Displays:

Graphics: Ten customized displays are available to enable the operator to monitor and operate the unit. Each of the graphics also includes corresponding functional keys (software switches).

User Access: System login is provided to differentiate the access level. Trend Displays: Predefined trends are available to enable the operator to monitor and troubleshoot the unit. However new trend pages can be configured as and when necessary by logging in with the required access controls. Alarm Display: This page gives the description of all the previous alarms.

3.2.1 Graphics Display: All the screens are identical in structure with,

• Header: It gives the status of the unit and remains common for

all the Graphics. • Main Area: This differs with each graphic and corresponds to the

name of the display, providing specific status and operational data of the unit in addition to instructions to operate the unit.

• Footer: This gives the description of the last three alarms

The status (header) area displays the following (when appropriate): ‐ Unit RUNNING or SHUTDOWN

‐ 3 or 4-BED operation

‐ AUTO TIME CONTROL or MANUAL TIME CONTROL

‐ Preset ADSORPTION TIME in ____ seconds

‐ AUTO TIME in ___seconds

‐ START-UP mode

‐ SWITCHOVER INHIBIT

‐ SW (adsorber number) PENDING ‐ (Adsorber number) DOWN in 3-Bed mode

‐ AUTO PROCESS or SEMI-AUTO PROCESS or MANUAL PROCESS

‐ Actual STEP ( Number) ‐ END OF STEP in Semi-auto mode ‐ MANUAL VALVE operation.

3.2.1.1 Graphic Display-1: Directory Shows the list of all the 10 displays available to the operator.

F1: Directory F2: Overview PSA F3: Operations F4: Switchover F5: Valves F6: Controllers F7: Reject Gas Control F8: Hardware Modicon F9: Trouble Shooting Guide F10: Summary Each Graphic can be accessed by

1. By using the functional keys F1 to F10 on the keyboard to directly access

the required page. 2. By clicking on the link provided on the Directory page. 3. By clicking on the PREV PAGE or NEXT PAGE links provided on each of

the graphics.

3.2.1.2 Graphic Display-2: Overview PSA The following are displayed:

‐ Picture of Adsorbers with actual pressures. D74A: PT8961 D74B: PT8962 D74C: PT8963 D74D: PT8964

‐ Last Adsorption time of each of the beds. ‐ Raw Hydrogen flow (FT-3101) ‐ Product Pressure (PT-3117) ‐ Reject Gas Pressure (PT-3115)

3.2.1.3 Graphic Display-3: Operations

This page enables the operator to carry on the following operations of the PSA.

a. Capacity Control Factor-Kf:

To change Kf values click on the soft switch in the Capacity Control

Factor window and type in the required number and click OK. Changing the Kf value proportionally changes unit sub cycle time

which in turn affect the pure hydrogen production rate. Kf is directly proportional to the pure hydrogen production rate for a given feed rate. However the Kf value is limited to values between 500 and 1500 by design and step changes of 50 are only accepted.

b. Operating Modes:

This enables the operator to choose the mode of operation between Auto/Semi-Auto/Manual. Manual mode can be selected only when the unit is under shutdown, while the unit can run in either Semi-auto or Auto modes. However Semi-auto mode may not be recommended during normal operation as it would require operator intervention after the end of each step.

‐ MANSTP: (Can be used when the unit is under shutdown only).

Pressing it toggles the operating mode between Manual and Semi-Auto.

‐ Auto: ( Can be used when the unit is running) This key toggles the operating mode between AUTO and SEMI-AUTO

c. Startup Mode: By clicking the STARTUP soft-switch the “Low product pressure” and “Long Adsorption time” trips are bypassed. This is normally

used for unit startup purposes only. This is indicated in the status area when it is selected. By clicking it again the previous condition can be restored.

d. TIM CON:

This switches the time control of the unit from Auto to Manual and

back. The actual mode is displayed in the status window. When in Auto mode the sub-cycle time is governed by the Kf factor and Raw Hydrogen flow rate. The unit is protected by a minimum and maximum sub-cycle time (Tsc min and Tsc max). The mode can be switched by clicking the TIME CON.

3.2.1.4 Graphic Display-4: Switch Over This page displays the picture of Adsorbers and actual pressures.

D74A: PT8961 D74B: PT8962 D74C:PT8963 D74D:PT8964

It also contains instructions and soft switches for the following operations: a. Unit startup with and without pressure:

Guidelines for startup of the unit are provided when there is/no

pressure. The following soft switches are provided to enable the startup operation.

‐ RUN/STOP: It enables the operator to start or stop the unit. A

RUN/STOP request needs to be confirmed through the CONFIRM key within 60 seconds.

‐ CONFIRM: Used to Confirm the RUN/STOP request.

‐ Auto: When the unit is running this key toggles the operating mode between AUTO and SEMIAUTO.

‐ STARTUP: Used to bypass the “Long Adsorption Time” and “Low

Product Pressure” trips. This is generally used for unit startup purposes. ‐ INHIBIT: Manual or Automatic (caused by a combination of valve

error and pressure profile alarm or an Adsorber’s pressure transmitter failure) switchover of unit from 4-Bed mode to 3-Bed mode can be avoided by selecting the Switch over INHIBIT switch. It can be enabled by clicking the switch again.

‐ TIM CON: This switches the time control of the unit from Auto to

Manual and back. The actual mode is displayed in the status window. When in Auto mode the sub-cycle time is governed by the Kf factor. The mode can be switched by clicking the TIME CON.

‐ T ADS: Operator can specify the Adsorption time by clicking onto T

ADS and feeding in the required number and pressing OK. This can be done when the time control is in Manual mode. In such case the operator can fix the adsorption time independent of Kf and Raw hydrogen flow rate. However the unit is protected by a minimum and maximum sub-cycle time (Tsc min and Tsc max).

‐ Kf: To change Kf values click on the soft switch besides Kf and type in

the required number and click OK. Changing the Kf value proportionally changes unit subcycle time which in turn affect the pure hydrogen production rate. Kf is directly proportional to the pure hydrogen production rate for a given feed rate. However the Kf value is limited to values between 500 and 1500 by design and step changes of 50 are only accepted.

b. Manual Switchover: Guidelines along with the requisite keys are made available to enable the operator to manually switch the unit from 4-Bed to 3-Bed mode and Vice-versa. A table containing the corresponding values to be fed into the system as per the required switchover is also displayed on the graphic.

‐ SW REQ: By clicking on this soft switch the operator requests

for a manual switchover. ‐ ‐ Process number Link: Allows the operator to select the vessel to be

taken offline or to switch back from 3-Bed to 4-Bed mode. This is done by clicking the link following the Select Process Number and entering the required and pressing OK.

‐ ‐ SW CON: Click on SW CON to confirm the requested switchover.

The following numbers are to be entered against the Select Process Number to achieve the desired switchover. Switch over required Process Number 3 to 4-Bed mode 0 D-74A out (4 to 3-Bed mode) 1 D-74B out (--------do----------) 2 D-74C out (--------do----------) 3 D-74D out (--------do----------) 4 Note: Certain process conditions are to be fulfilled along with the above mentioned switchover operational request before the unit actually switches over. A message “Switch over Pending” would appear onscreen in such a case. Please refer to process manual to identify the condition required of the bed to be taken in/off line (E.g. The bed being taken inline should always be at reject gas pressure before unit switches from 3 to 4-Bed mode).

c. Manual Step Advance: This explains the method to advance the steps manually when the unit is in Manual or Semi-Auto mode.

‐ MAN STP: It can only be used when the unit is under shutdown. Clicking on it toggles the unit operation mode between Manual and Semi-Auto.

‐ STEP: When the unit is in Manual or Semi-Auto mode this key allows the operator to advance the unit by one step at a time w.r.t. valve sequence.

Note: When the unit is in Semi-Auto mode, “END OF STEP” message appears in the status area after which the operator can choose STEP switch to manually advance the step.

3.2.1.5 Graphic Display-5: Valves This page displays the following:

1. The picture of all the Adsorbers with actual pressures.

D74A: PT8961 D74B: PT8962 D74C: PT8963 D74D: PT8964

2. Indications of all the valve positions. The default codes are

Green : Valve open Red : Valve Closed Yellow : Valve Error Following are the tag numbers of the valve positions w.r.t. their service Feed : ZSL-8951 A/B/C/D Product : ZSL-8952 A/B/C/D Equalization : ZSL-8953 A/B/C/D Dump : ZSL-8954 A/B/C/D

3. % opening of control valves Product : XCV-8952 A/B/C/D Equalization : XCV-8953 A/B/C/D Dump : XCV-8954 A/B/C/D Note: The feed valves are ON/OFF valves.

4. Manual Valve Operation:

Functional keys and guidelines enabling the operator to perform manual valve operation are provided on this graphic. Manual valve operation is possible, ‐ On all valves when the unit is under shutdown ‐ On valves of the Offline adsorber in 3-Bed mode.

a. MAN VLV: Clicking on MAN VLV toggles between manual valve

operation and auto valve operation. The actual status is displayed in the status area.

b. Valve Number Link: Click on the link following “select valve number” and enter the required number and press OK. Please note that the number of the valve should include the last two digits of the actual valve number followed by 1 for Bed-A 2 for Bed-B 3 for Bed-C 4 for Bed-D E.g.: Enter 541 for dump valve (XCV-8954A) of Bed-A.

c. VAL CON: This confirms the valve operation and pressing this

toggles the valve operation between open and close positions.

d. Input % opening Link: If the valve is an analog valve the operator can feed in % opening. This can be done by clicking on this link and inputting the required value and pressing OK.

Note: When the operator switches back to normal position by clicking on the MAN VLV again, all the values will go to close position.

3.2.1.6 Graphics Display-6: Controllers

This graphic essentially displays the following parameters of the three controllers i.e. Repressurization, Purge and Dump. PV : Process variable SP : Set Point Out : Output Pres : Pre Set Time Elap : Elapsed Time

The display of the above mentioned parameters gives the operator an insight into the performance of each controller and helps him trouble shoot the unit. Please note that the controllers are the same for all the vessels. However no two vessels utilize the same controller at the same time. The controller performance should be monitored with respect to the relevant vessel. Note: By logging in as a supervisor one can tune all the PID parameters of the controllers. These are displayed on the side of the controllers. To adjust the value of, KP : Proportional Band TI : Integral Time KD : Derivative Gain TD : Derivative Time By clicking on the value, enter the value in the popup window and click OK.

3.2.1.7 Graphic display-7: Reject Gas Controls The graphic displays includes,

a. Picture of surge drum and its pressure

b. PSA reject gas to flare, PV-3115

- % opening of the valve

- Auto/Manual as appropriate - Additionally the valve would turn Green when in open condition and - Red when in closed condition.

c. PSA reject gas to fuel gas, FV-3116

‐ % opening of the valve ‐ Auto/Manual/Cascade as appropriate ‐ Additionally the valve would turn Green when in open condition and

Red when in closed condition

d. PV-3115 controller window.

‐ Soft switch can be used to toggle the flare control between Manual and Auto.

‐ When in Auto, Reject Gas pressure (to flare) can be set by clicking on the link and inputting the value and pressing OK.

‐ When in Manual, Reject Gas to flare control valve output can be set by clicking on the link and inputting the value and pressing OK.

e. PV-3115 status window: This window displays the setpoint and the actual value of surge drum pressure.

f. FV-3116 controller window.

- PW*: The required reject gas pressure can be set by clicking on the link and inputting the value in Kg/cm2g. and pressing Ok. ‐ Soft switch to toggle the flare control between Manual and Auto. ‐ Soft switch to toggle the flare control between Auto and Cascade. ‐ When in Auto, Reject Gas flow (in Nm3/hr to fuel gas) can be set by

clicking on the link and inputting the value and pressing OK. ‐ When in Manual, Reject Gas to fuel gas control valve output can be

set by clicking on the link and inputting the value and pressing OK.

g. FV-3116 status window: It displays

o Setpoint of flow of reject gas to fuel gas in Nm3/hr. o The actual value of reject gas flow to fuel gas in Nm3/hr o PW*: Required reject gas pressure o PW: Measured reject gas pressure.

3.2.1.8 Graphic Display-8: Hardware Modicon

‐ Shows all modicon cards with their status as Green : Card Healthy Red : Card Failure For both the main and redundant PLC systems.

‐ Indicates PLC status (e.g.: Shows if the standby is on standby or inline) ‐ ‐ Indicates the power supply cards status

Green : Card Healthy Red : Card Failure Note: Any failure or abnormality noticed in the PLC system should be reported to maintenance personnel immediately.

3.2.1.9 Graphic Display-9: Troubleshooting Guide

This display essentially includes broad remedial measures for each of the condition causing an alarm or trip of the system. It also displays all the alarms and trips of PSA. The guidelines can be obtained by simply clicking on the respective alarm or trip.

3.2.1.10 Graphic Display-10 : Summary This Graphic lists the following process data for each of the adsorbers.

‐ Actual last adsorption time of respective adsorber in secs. ‐ Actual last adsorption pressure of respective adsorber in Kg/cm2g.

‐ Pressure of the adsorber when it is providing gas for equalization. ‐ Pressure of the adsorber when it is receiving gas for equalization. ‐ Preset Purge time in secs ‐ Actual Purge time in secs. ‐ Preset repressurization time in secs. ‐ Actual repressurization time in secs. The above information is essential for trouble shooting of the unit. In addition to the displays above a few auxiliary displays are designed to enable the operator monitor the unit better and to make possible certain basic changes in the software by the administrator.

3.2.1.11 Graphic Display-11: Administrator Screen This screen is dedicated to the administrator (by logging in the initial login page as administrator). Certain advanced features of Vijeo Citect can be executed through this screen. 3.2.1.12 Graphic Display-12: Alarm Display This page lists the last several alarms. The one displayed at the top will always be the latest. This page includes the following navigational tools on the side of alarm list.

• Acknowledge all alarms on the current page • Acknowledge the alarm that is selected • Silence alarm sound • Page top of the alarm list: to get to the latest alarm • Up/down navigation of the page. • Apply filter to the alarm list: to sort out alarms as per

requirement/system wise to enable troubleshooting • Clear Filter to return to the full list.

3.2.1.13 Graphic display-13: Trend Display The graphic displays the trends of the PSA parameters. Several predefined trend pages are provided to enable systematic trouble shooting and monitoring of

the unit. However new trend pages when required, can be configured when logged in with the right access. The X-axis has the time scale, which can be varied and the y-axis has the relevant value scales which can also be varied. A window with the tag numbers of the displayed trends with the current actual values and scales of the Y-axis (as these are parameter specific while the x-axis is common for all) is provided at the bottom of the page. The group of predefined trend pages can be accessed by,

• Select the trend group menu on the screen. A popup menu with the entire predefined trend pages appears.

• Click on the required trend group and click OK.

3.3 Annexures: Different annexures are provided herewith. They include, - Login and navigation pages. - Menu content pages. - Control displays. - Alarm - Trend pages

5

Start up Page

6

Login Page

7

NAVIGATION MENU

11

GRAPHIC 1: FUNCTION KEY: F1

12


13


14


16


18


19


20


21


22


23

GRAPHIC 11: ADMINISTRATOR SCREEN.

24

GRAPHIC 12: ALARM DISPLAY

25

GRAPHIC 13: TREND DISPLAY

26

TREND CONFIGURATION

PSA Startup Procedure (System without pressure): 1. Ensure that the Unit is fully lined up in the field. 2. Ensure that all the consumer systems CVs or XVs are closed (DCS). 3. Temperature at D-22 overhead is less than -120ºC. 3. Close FV-3101 and PV-3117 on manual (DCS). 4. Close FV-3316 on manual (PSA Graphic-7) by, - Use REJECT MAN switch to take CV on manual. - Click on the link following OUT REJ and enter “0” and click ‘OK”. 5. Put PV-3115 on auto at 4.2 Kg/cm2g. (PSA Graphic-7) by, - Use FLARE MAN switch to take CV on auto. - Click on the link following SP FLA and enter “4.0” and click “OK”. 6. Use PSA Graphic-4 to, - Bypass Low product pressure trip by selecting STARTUP mode. - To inhibit switchover by using INHIBIT switch. - Feed in a Kf of 780 by clicking on the link following Kf. - Leave the time control on auto mode by selecting TIM CON switch. 7. Open FV-3101 by 2% and bring the pressures on the beds as per Annexure-1

i.e. the pressures in the beds must be as per the step you have chosen to start with. The beds can be pressurized by opening the feed valves and controlling the pressurization by the opening of FV-3101. To get to any step number,

- Go to manual mode by pressing MAN STP on PSA graphic -4. - Keep clicking on STEP switch until the desired step number is achieved.

With each click of STEP switch the unit progresses by one step at a time. 8. When the desired pressure profile is reached and specific step number is fed in, - Click on RUN/STOP to select run mode.

- Click on CONFIRM to confirm the startup requirement. Note that the confirm switch is pressed within 60secs of selecting the run mode. The unit will start running now.

9. Gradually open FV-3101 observing PC-3370 (Cold box delta P should not be

less than 3.0 Kg/cm2g). If needed FC-3253 may be manipulated. 10. Put FC-3101 and PC-3117 on auto to maintain adequate flow to PSA and to

maintain adsorption pressure. Also put PC-3119 on auto at 38 Kg/cm2g to ensure the excess pure hydrogen is dumped to fuel gas. Always ensure that PC-3119 output has margin so as to absorb fluctuations in consumption of pure H2 and to protect PSA from low product pressure.

11. As the reject gas flow is established, set PW* at 4.0Kg/cm2g and put FC-3116

on auto-cascade. 12. After PSA stabilizes take AI-3123 in line and monitor CH4 for the

performance of PSA. PSA startup with pressure:

Bring the vessel pressures inline with the step as per Annexure-1. Follow the above procedure from step (8) onwards.

Shut Down Procedure: The unit can be shutdown easily by,

- Click on RUN/STOP to select run mode.

- Click on CONFIRM to confirm the shutdown requirement. Note that the confirm switch is pressed within 60secs of selecting the stop mode. The unit will shutdown immediately.

- Close FV-3101 on manual to Zero %.

Switch Over from 4Bed to 3Bed mode:

The unit automatically switches from 4 to 3 Bed mode when,

a. Pressure transmitter failure of the vessels (PT - 8961, 8962, 8963, 8964).

e. Simultaneous valve error and pressure profile alarm. f.

It can be manually done at any step by, ‐ On graphic#4 press SW REQ ‐ Input the adsorber number as displayed on the graphic) in the process

select link and press OK. ‐ Press SW CON. ‐

The respective bed would automatically go offline as per the logic. Preferably the bed may not be switched over when it is under adsorption. The process numbers that need to be entered for respective beds are, Adsorber A: 1, B: 2, C: 3, D: 4 Switch Over from 3Bed to 4Bed mode:

The switchover form 3 to 4 Bed mode can only be done manually. The bed being taken inline must be at reject gas pressure. This can be done either by depressurizing through PSV bypass if the pressure is high or by pressurizing through XCV-8952 if the pressure is low. It can be done by,

‐ On graphic#4 press SW REQ ‐ Input “zero” in the process select link and press OK. - Press SW CON

If the pressure in the adsorber = reject gas pressure +/- 1.0 Kg/cm2g, a message SWOVER PENDING will appear on the screen. When the corresponding step comes in the adsorber will be taken inline automatically.

Annexure-1

STEP

PSA in 4-Bed mode

End of step pressures in Kg/cm2g

PSA in 3-Bed mode

End of step pressures in K / 2 A B C D X Y Z

1.1 36.2 4.3 10.5 36.2 36.2 4.3 36.2

1.2 36.2 22.5 10.5~4.3 22.5 36.2 4.3~22.9

36.2

1.3 36.2 ~ 27.6 4.3 22.5 36.2 22.9 22.9

1.4 36.2 27.6~36.2

4.3 10.5 36.2 22.9 22.9

1.5 36.2 27.6~36.2

4.3 10.5 36.2 36.2 4.3

1.6 36.2 36.2 4.3 10.5 36.2 36.2 4.3

2.1 36.2 36.2 4.3 10.5 36.2 36.2 4.3

2.2 22.5 36.2 22.5 10.5~4.3 36.2 36.2 4.3~22.92.3 22.5 36.2 ~ 27.6 4.3 22.9 36.2 22.9

2.4 10.5 36.2 27.6~36.2

4.3 22.9 36.2 22.9

2.5 10.5 36.2 27.6~36.2

4.3 4.3 36.2 36.2

2.6 10.5 36.2 36.2 4.3 4.3 36.2 36.2

3.1 10.5 36.2 36.2 4.3 4.3 36.2 36.2

3.2 10.5~4.3 22.5 36.2 22.5 4.3~22.9

36.2 36.2

3.3 4.3 22.5 36.2 ~ 27.6 22.9 22.9 36.2

3.4 4.3 10.5 36.2 27.6~36.2

22.9 22.9 36.2

3.5 4.3 10.5 36.2 27.6~36.2

36.2 4.3 36.2

3.6 4.3 10.5 36.2 36.2 36.2 4.3 36.2

4.1 4.3 10.5 36.2 36.2 W Y Z 4.2 22.5 10.5~4.3 22.5 36.2 B C D

4.3 ~ 27.6 4.3 22.5 36.2 A C D

4.4 27.6~36.2

4.3 10.5 36.2 A B D

4.5 27.6~36.2

4.3 10.5 36.2 A B C

4.6 36.2 4.3 10.5 36.2

Trip System: PSA has the following trips

Cause Alarm Display Remarks

1. Low product pressure Low product pressure shutdown Set: < 30kg/cm2g

Note: Bypassed in Start up mode 2. Long Adsorption Time Set : 140% of calculated time

Bed A Long Adsorption shutdown Note: Bypassed in Start up mode

Bed B Long Adsorption shutdown

Bed C Long Adsorption shutdown

Bed D Long Adsorption shutdown

3. Low instrument air pressure

Low IA pressure alarm for > 10 sec

PSLL-8990 Low instrument air pressure shutdown

4. Modicon I/O shutdown Modi I/O shutdown Fatal modicon i/o failure

Simultaneous errors on various components

5.Transmitter Failure Signal below 3mA Bed A out and PT-8962 failure Transmitter shutdown PT-8963 failure Transmitter shutdown PT-8964 failure Transmitter shutdown Bed B out and PT-8961 failure Transmitter shutdown PT-8963 failure Transmitter shutdown PT-8964 failure Transmitter shutdown Bed C out and PT-8961 failure Transmitter shutdown PT-8962 failure Transmitter shutdown PT-8964 failure Transmitter shutdown Bed D out and PT-8961 failure Transmitter shutdown PT-8962 failure Transmitter shutdown PT-8963 failure Transmitter shutdown

Alarm System: PSA has the following alarms. Cause Effect Remarks

1.Low product pressure 1. Low product pressure alarm display Set: < 33kg/cm2g

2.Long purge Set : Preset time + 5sec Bed A Long purge alarm display Bed B Long purge alarm display Bed C Long purge alarm display Bed D Long purge alarm display 3.Long dump Set : Preset time + 5sec Bed A Long dump alarm display Bed B Long dump alarm display Bed C Long dump alarm display Bed D Long dump alarm display 4.Long repressurisation Set : Preset time + 5sec

Bed A Long repressurisation alarm display

Bed B Long repressurisation alarm display

Bed C Long repressurisation alarm display

Bed D Long repressurisation alarm display

5.Long adsorption time Set : 120% of calculated time

Bed A Long cycle time alarm display Bed B Long cycle time alarm display Bed C Long cycle time alarm display Bed D Long cycle time alarm display

6.Transmitter failure Set : Input signal < 3mA

PT-8961 ( Bed A) Switch Bed A out & display alarm

PT-8962 ( Bed B) Switch Bed B out & display alarm

PT-8963 ( Bed C) Switch Bed C out & display alarm

PT-8964 ( Bed D) Switch Bed D out & display alarm

7.Valve failure

Bed A XV8951A Valve XV-8951A failure alarm

XCV8952A Valve XCV-8952A failure alarm



Bed B XV8951B Valve XV-8951B failure alarm

XCV8952B Valve XCV-8952B failure alarm



Bed C XV8951C Valve XV-8951C failure alarm

XCV8952C Valve XCV-8952C failure alarm



Bed D XV8951D Valve XV-8951D failure alarm

XCV8952D Valve XCV-8952D failure alarm



8.Pressure profile error Bed A Dump profile pressure profile error Repress profile pressure profile error Provide Purge profile pressure profile error E1 up profile pressure profile error E1 down profile pressure profile error

Isolation profile pressure profile error Purge profile pressure profile error Bed B Dump profile pressure profile error Repress profile pressure profile error Provide Purge profile pressure profile error E1 up profile pressure profile error E1 down profile pressure profile error Isolation profile pressure profile error Purge profile pressure profile error Bed C dump profile pressure profile error Repress profile pressure profile error Provide Purge profile pressure profile error E1 up profile pressure profile error E1 down profile pressure profile error Isolation profile pressure profile error Purge profile pressure profile error Bed D dump profile pressure profile error Repress profile pressure profile error Provide Purge profile pressure profile error E1 up profile pressure profile error E1 down profile pressure profile error Isolation profile pressure profile error Purge profile pressure profile error

9.Process switchover Process switch over alarm for 60sec

Manual Bed-A Switch over pending / Bed A out

Bed B Switch over pending / Bed B out

Bed C Switch over pending / Bed C out

Bed D Switch over pending / Bed D out

Auto PT-8961 ( Bed A) Switch Bed A out & display alarm

PT-8962 ( Bed B) Switch Bed B out & display alarm

PT-8963 ( Bed C) Switch Bed C out & display alarm

PT-8964 ( Bed D) Switch Bed D out & display alarm

Pressure profile alarm + Valve failure

Bed A Dump profile Process switch over alarm Alarm display for 60 sec

Repress profile Process switch over alarm Alarm display for 60 sec

Provide Purge profile Process switch over alarm Alarm display for 60 sec

E1 up profile Process switch over alarm Alarm display for 60 sec

E1 down profile Process switch over alarm Alarm display for 60 sec

Isolation profile Process switch over alarm Alarm display for 60 sec

Purge profile Process switch over alarm Alarm display for 60 sec

Bed B Dump profile Process switch over alarm Alarm display for 60 sec







Bed C Dump profile Process switch over alarm Alarm display for 60 sec





Isolation profile Process switch over alarm Alarm display for 60

sec


Bed D Dump profile Process switch over alarm Alarm display for 60 sec







10.PLC switchover

PLC A Primary switch out PLC switchover alarm Alarm display for 60 sec

PLC B Primary switch out PLC switchover alarm Alarm display for 60 sec

11.No-standby PLC PLC A offline No standby PLC alarm PLC B offline No standby PLC alarm 12.Low instrument pressure Set : < 4.0 Kg/cm2g

PSLL 8990 Low instrument air pressure alarm

13.Power supply failure PS 48A PS 48A failure alarm PS 48B PS 48B failure alarm PS 24A PS 24A failure alarm PS 24B PS 24B failure alarm

Psa Operating Manual

Documents

Transcript of Psa Operating Manual