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100 Area > 100 Area 3/23 > Flashcards

100 Area 3/23 Flashcards

1
Q

What determines the production rate for LTDC reactors?

A

The chlorine feed rate from C/A.

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2
Q

What is the purpose of the chlorine analyzer?

A

To signal the ethylene trim to feed at the correct rate based on free chlorine in the reactor.

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3
Q

What is the normal range of chlorine throughput in the LTDC reactor?

A

0-6200 scfm

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4
Q

Why do we run an excess of chlorine in the LTDC reactor?

A

Ethylene is more expensive and all chlorine made in C/A must be used. So a small excess of chlorine ensures as much ethylene reacts as possible and is not wasted to the GTO vent.

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5
Q

What is the normal range of ferric chloride in the LTDC reactor product?

A

40-80 ppm

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6
Q

What is the purpose of the N7 addition to the LTDC feed spargers (F104)?

A

Nitrogen creates lift in the reactors and prevents back flow into the feed lines.

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7
Q

For a feed 3670 scfm of Chlorine to MRE101, what would be a reasonable flow on F102? On F103?

A

F102 - 3370 scfm

F103 - 300 scfm

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8
Q

What is the normal main chlorine feed pressure (P100) to the LTDC reactors?

A

60 psig

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9
Q

What is the normal ethylene feed pressure P102 to the LTDC reactors?

A

75 psig

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10
Q

List the indications of high ethylene feed to chlorine ratio in LTDC.

A

Rise in GTO temp, R102 A/B shows higher than 1.0, A11 reading low chlorine, less caustic being used in wash train.

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11
Q

What adjustments can be made to recover from high ethylene in the LTDC reactor?

A

Lower F102 feed rate.

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12
Q

List the indications of low ethylene feed to chlorine ratio in LTDC.

A

A11 shows high chlorine, low r102 ratio, lower PH in wash train, more caustic spent.

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13
Q

What adjustments can be made to recover from low ethylene in the direct reactor?

A

Increase F103 feed rate.

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14
Q

What would be the possible causes of a below spec reading on A12 while F114 shows a higher than normal flow, and what are the steps to recover from each?

A

Ferric is running low or a lower tap needs to be used.

If the lowest tap and dip leg have already been used. Switch ferric pots.

Take a sample.

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15
Q

Controls main ethylene flow rate to reactor.

A

F102 A/B

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16
Q

Regulates chlorine pressure coming from C/A. Adjusts chlorine flows to directs.

A

P100

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17
Q

Regulates chlorine feed pressure to each reactor. Drops pressure from 60 psi to 55 psi.

A

P101 A/B

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18
Q

Regulates feed pressure from MHE121. Drops pressure from 980 psi to 200 psi for Direct and Oxy ethylene feeds.

A

P103

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19
Q

Monitors EDC level in directs. Protects reactors from over-filling causing high GTO pressure and under-filling causing high temperatures and loss of thermosiphon.

A

L111 A/B

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20
Q

Monitors vent flow from reactor to MHE-105.

A

F112 A/B

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21
Q

Regulates excess oxygen in reactor dilution space. Adjusts N7 at F107 to dilute oxygen concentration.

A

A13-1 A/B, A13-2 A/B

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22
Q

Regulates dilution N7 flow to keep vent gas at 2-7% Oxygen. Runs in cascade with A13.

A

F107 A/B

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23
Q

Measures oxygen concentration in chlorine received from C/A.

A

AA411 X/Y

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24
Q

Monitors temperature at the top of MRE-101/102. Indication only.

A

T111

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25
Q

Regulates total N7 flow to both chlorine & ethylene sparge purges. Primarily used at startup and low rates to create lift and induce thermosiphon.

A

F104

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26
Q

Monitors temperature at the bottom of MRE-101/102. Indication only.

A

T112

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27
Q

Monitors reactor pressure. Indication only.

A

P111 A/B

28
Q

Monitors ethylene feed temperature to directs. Indication only.

A

T102

29
Q

Monitors chlorine feed temperature to directs. Indication only.

A

T101

30
Q

Regulates pressure on both reactors to dry vent. Controls residence time. High pressure can slow chlorine feed from C/A. Low pressure can result in loss of condensation in exchangers.

A

P112

31
Q

Regulates the amount of residual chlorine in the LTDC crude EDC. Sends signal to F103 A/B to increase or decrease ethylene flow.

A

A11 A/B

32
Q

Regulates ethylene pressure to directs. Reduces header pressure from 200 psi to 75 psi.

A

P102

33
Q

Monitors nitrogen flow to ethylene sparges. Prevents EDC backflow & sparge plugging. Used during low level and startup.

A

F105 A/B

34
Q

Regulates ethylene trim flow. Cascaded to A11 normally. Adjusts ethylene trim flow to control excess chlorine present in crude EDC.

A

F103

35
Q

Monitors EDC crude flow from directs to recovery. Indication only.

A

F111 A/B

36
Q

Regulates ferric-entrained EDC flow back to directs.

A

F114 A/B

37
Q

Monitors chlorine temperature to directs. Indication only.

A

T101 A/B

38
Q

Regulates chlorine feed flow. One reactor feed cascades to P100 to control header pressure while one runs in flow control to even out load. Adjusts ethylene trim when cascaded to F103 A/B.

A

F101 A/B

39
Q

Monitors residual iron in crude EDC. Indication only.

A

A12 A/B

40
Q

Describe the liquid EDC flow path from the bottom of the reactor to the wash train.

A

Liquid EDC flow up the MTK-101/102 surge pot and gravity drains to MTK-105 where it is pumped to the wash system by MPU-101 A/B.

41
Q

Describe the flow path of the vents leaving the top of the reactor to the vent header.

A

Vents exit the top of the reactor and enter the tube side of MHE-105. 80% of vents are condensed to liquid while 20% goes to MHE-106. -20°C propylene in MHE-106 condenses nearly all vapors which then flow to MTK-115. Remaining vapors leave MTK-115 and pass through MHE-105 to cool incoming process before going to dry header.

42
Q

EDC condensed in MHE-105 drains to ________.

A

MTK-105

43
Q

EDC condensed in MHE-106 drains to ________.

A

MTK-115

44
Q

The direct reactors are vented to remove excess acetylene; True or False.

A

False

45
Q

What prevents reactor vents from the bottom of MHE-105 from bypassing MHE-106 and proceeding directly to the vent header?

A

A seal leg

46
Q

Can MHE-105 be bypassed while the reactors are running?

A

Yes

47
Q

What would be the effects of a low level on MHE-106?

A

If the process tubes are not covered with propylene there will be less heat transfer and process will heat up. This will results in less condensation and more EDC lost to the dry vent header and burned in the GTOs.

48
Q

How is the level in MTK-115 controlled?

A

MTK-115 is gravity drained to MTK-105 and follows its level.

49
Q

If the level transmitter on MHE-106 fails, and P114 is reading off scale high, what has most likely happened?

A

Propylene level is too high and possibly rising into the propylene vent piping. Process will heat up and lose condensation due to loss of evaporation space.

50
Q

If the level transmitter on MHE-106 fails and P114 is reading normal value, but T113 is reading significantly higher normal, what has most likely happened.

A

Low propylene level resulting in process tubes not being covered and lack of heat transfer. Process will heat up.

51
Q

If PCV113 fails open, what are the undesirable consequences?

A

Pressure loss on MTK-105 output line to wash train. SV111 would close to prevent water from backing up in to the recovery system.

52
Q

Explain in detail how MHE-106 works. Include both the process and utility side of the exchanger.

A

Vents from MHE-105 and MTK-105 enter the tube side.
liquid propylene on the shell side covers tubes but leaves vapor space for evaporative cooling to take place. Process in the tubes condenses into liquid as propylene absorbs the process heat and flashes to vapor. Process liquid drains to MTK-115.

53
Q

Monitors vent gas flow to recovery system.

A

F112

54
Q

Regulates pressure on MHE-106. Controls the temperature of process exiting MHE-106

A

P114

55
Q

Monitors the process outlet temperature of MHE-106

A

T113

56
Q

Regulates the level in MTK-105 by letting more or less process out to the wash train.

A

L112

57
Q

Regulate line pressure out of MTK-105 to wash train. Prevents back flow of process into MTK-105.

A

P113

58
Q

Monitors liquid EDC flow from directs to MTK-105.

A

F111

59
Q

Monitors oxygen concentration going to dry vent header from recovery system. Used to troubleshoot A13 oxygen analyzers.

A

A14

60
Q

Why do we wash crude EDC from LTDC reactors?

A

To remove ferric chloride.

61
Q

What do we use water as the washing medium?

A

Water is cheap, readily available, separates well from EDC, and easily absorbs ferric.

62
Q

What are the effects of too much ferric in the LTDC EDC product?

A

More acidic washtrain, higher likelihood of rag in wash train, plug analyzers.

63
Q

How much excess chlorine is normally run in directs?

A

200-400 ppm

64
Q

What happens if the Chlorine header pressure is too high?

A

C/A will have to begin neutralizing chlorine.

65
Q

What is the purpose of MPU-101 A/B?

A

To pump Crude EDC from MTK-105 to wash train. This is the driving force for the washtrain EDC.

100 Area (4 decks)

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