Efectos del cambio climático en los diferentes sectores

Prior to opening of the Feed Gas inlet and outlet KV valves (41/42/43-KV-043, 41/42/43-KV-055, 41/42/43-KV-046 and 41/42/43-KV-057), blowdown KV valve (41/42/43-KV-053) will open to the wet hydrocarbon burn pit after 648 mins later starting from Step 1. The 41/42/43-KV-053 will be closed after 30 second pass from detecting open limit switch. This will ensure that accumulated free water, if any, in the Feed Gas line is flushed out from the feed gas system. This will protect the dehydrator bed from degradation due to free water carry-over.

Normal operation

1) Regeneration and Adsorption sequence step

One cycle of the regeneration is 648 minutes (10.8 hrs) and consists of the following 14

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steps. Once sequence passes through Step 0, the Step 0 cannot be reached again during normal sequence operation in Auto Modeexcept in case of 5 Dehydrators modes and skipped.

2 Dehydrator Pressurization - 10

3 Connect Dehydrator to Regeneration - -

4 Dehydrator Heating – Ramp up (1st stage)

144 Æ 248 10

5 Dehydrator Heating (1st stage) 248 30

6 Dehydrator Heating – Ramp up (2nd stage)

248 Æ 400 Æ 550

15

7 Dehydrator Heating (2nd stage) 550 320

8 Disconnect Regen Gas Electric Heaters (B66-E-0105A/B) from Regeneration

12 Dehydrator Depressurization - 10

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13 Standby time - Approx.

110- 14 Connect Dehydrator to Adsorption -

Total - 648

NOTE 1: Each step timers can be extended anytime.

NOTE 2: Standby timers can be skipped by the operator when it is manual mode.

2) Automatic operation

The dryer sequence shall have two operation modes, Auto and Manual selectable by the Auto/Man Selector Switch (41/42/43-HS-104). When it is in Auto position, Start Sequence (41/42/43-HS-100) shall start the sequence, which always starts from Dehydrator A in regeneration and Dehydrator B, C, D, E and F in adsorption mode. The regeneration process shall move from one step to another in sequential order from A, B, C, D, E and F and continue until it is stopped by the Stop Sequence (41/42/43-HS-101).

As the sequence starts in Auto mode, all the sequence related valves are initialized to close position and then the sequence continues step by step. During AUTO sequence operation, sequence gives open/close command to KV, change the controller setpoint and turn on/off electric heater automatically. When a sequence is in Auto mode, the operator must not manually manipulate any sequence valve. If operator wants to manipulate the discrepancy valve, the Sequence Manual mode should be selected by operator and changes controller mode to Manual individually. The timer for each step is keep counting to proceed to next step. The transition to next step will be done automatically if all permissive condition is cleared.

All individual valve position status, both open and close, shall be repeated to DCS and the sequence monitors all the time that they are in the appropriate position as the sequence programmed. If there is a discrepancy between the sequence command and the actual valve position or a discrepancy between the start/stop command for Electric

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Heater and it’s feed back, the sequence shall be turned to Sequence Manual mode and allow to proceed the sequence manually by operator. The timer keeps counting and generate the discrepancy alarm in DCS. It will continue to sending command to valves until operator disconnect the valve from sequence by changing controller mode to manual. After DCS receives the expected feedback of the sequence and all controller modes is in AUTO, operator is able to put back Sequence mode to AUTO.

If the operator wants to stop the sequence intentionally by any reason, it is allowed to stop the sequence using the Stop Sequence Switch (41/42/43-HS-101). In order to resume the sequence from the stopped position, the Start Switch (41/42/43-HS-100) shall be used.

The status of the Sequence Stopped (41/42/43-YL-102) shall be indicated in DCS when it is stopped by the Stop Switch. (41/42/43-HS-101)

The mode status of each dehydrator if it is in regeneration or adsorption modes shall be indicated in DCS by the Dehydrator Status (41/42/43-YI-100A/B/C/D/E/F). The timers shall be indicated with the unit of “minutes”.

All timers and counters shall be available for operator in DCS graphic by the Phase Timer.

The duration after depressurization to adsorption operation of the dehydrator is called

“Stand-by” mode, and therefore it is called Available Stand-by Time (41/42/43-KI-008).

The Stand-by time finishes by means of the timer when the total regeneration time is expired (648 min. = 10.8 hrs).

3) Manual operation

During sequence Manual mode, the sequence also sends command to valves as well as AUTO mode unless controller mode is changed to Manual by operator. The operator can

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This manual mode operation is provided for trouble shooting of the sequence valve position and for a step by step operation and not intended to manipulate a manual operation of all the sequence valves. The step by step operation means the sequence can not proceed to the next step automatically. Therefore, the Go to Next Step HS (41/42/43-HS-105) shall be highlighted in DCS once all valve position matches to the expected position in each step. The HS is not to be pressed until all permissive condition is cleared, including timer. The sequence can start and stop during this manual mode.

Also, a series of the regeneration mode from step-1 through step-14 can be performed in auto by the regen start switch (41/42/43-HS-100) without operator’s interference in this manual mode.

4) Five (5) dehydrator’s operation (one dehydrator is out of service)

When one dehydrator is out of service, four (4) beds are in adsorption mode and one (1) in regeneration mode. In this operation, the adsorption mode lasts for 54 hours, and one cycle of the regeneration is 13.5 hours (Only stand-by time changes to 4.7 hours instead of 110 minutes.) The total feed gas flow rate shall be reduced to 80% in this operation.

To change to the five dehydrator’s operation, the selector switch for five dehydrator’s operation (41/42/43-HS-107) and the selector switch for a skipped dehydrator (41/42/43-HS-108 A/B/C/D/E/F) shall be used any time. Once the selector switch for five dehydrator’s operation is initiated, the DCS logic will be ready for switching, and the five dehydrator’s operation starts when one of the dehydrators goes to step 13 “stand by time” in regeneration mode by final command before step is moved to step 13, i.e., step-1. Any of five dehydrator operation command or skipped dehydrator command during step 13 will be applied when next dehydrator’s step 13 is started.