Chemical Engineering  >  KEROSENE MEROX UNIT CHAPTER-2 1 CHAPTER-2

KEROSENE MEROX UNIT CHAPTER-2 1 CHAPTER-2 - Notes - Chemical Engineering

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KEROSENE MEROX UNIT 
CHAPTER-2  1 
CHAPTER-2 
 
PROCESS  DESCRIPTION 
 
 
 
2.1 HYDROCARBON FLOW 
 
2.1.1 CAUSTIC PREWASH (15-VV-VI-001) 
 
Kerosene from crude distillation unit is pumped by 15-PA-CF-003A/B to caustic pre wash. 
This vessel is half filled with 3 ? be caustic solution for the neutralization of acidic 
compounds in the kerosene feed. These acidic compounds are H2, CO2 naphthenic acids. If 
allowed to get to the reactor they will consume caustic and oxygen and also effect catalyst 
activity. There are two inlet nozzles provided. The bottom nozzle having holes facing 
downward is provided for inlet nozzles provided. The bottom nozzle having holes facing 
downward is provided for adequate mixing of the kerosene feed and the caustic solution. 
The top nozzle having holes pointing upward is used during caustic change out only. A 
skim line is provided just below the kerosene/caustic interface to rid of any insoluble 
foreign materials accumulated at the interface. A mesh blanket at the top of vessel is 
provided to minimize caustic carry over to the reactors. 
 
 
2.1.2 MEROX REACTOR (15-R-00-001) 
 
The merox reactor contains the merox catalyst supported on a bed of activated charcoal. 
They provide means to uniformly distribute the kerosene feed and air mixture over the 
alkali catalyst bed at a pre determined residence time. The alkaline medium is provided by 
intermittently injecting caustic solution without disrupting the normal kerosene flow. The 
catalyst beds also act as filters and the reactor design will allow the entrained caustic be 
separated out at the bottom of the reactor. 
 
 
2.1.3 CAUSTIC SETTLER (15-VV-VI-001) 
 
This is a horizontal vessel where entrained caustic is gravity separated from the treated 
Kerosene. It is also the hold up tank for the wash caustic. Accumulated spent caustic in the 
settler is dumped out and can be reused in other part of the Refinery. 
 
 
2.1.4 WATER WASH (15-VV-VI-002) 
 
This is the 1
st
 of three vessels for the after treatment of the merox treated Kerosene. 
Kerosene is distributed through the bottom distributor into the deminerlized water 
continuously being injected into the vessel. Soluble soaps or surfactant are removed from 
the Kerosene. The caustic if it survives the caustic settler will also be extracted out. A 
Page 2


KEROSENE MEROX UNIT 
CHAPTER-2  1 
CHAPTER-2 
 
PROCESS  DESCRIPTION 
 
 
 
2.1 HYDROCARBON FLOW 
 
2.1.1 CAUSTIC PREWASH (15-VV-VI-001) 
 
Kerosene from crude distillation unit is pumped by 15-PA-CF-003A/B to caustic pre wash. 
This vessel is half filled with 3 ? be caustic solution for the neutralization of acidic 
compounds in the kerosene feed. These acidic compounds are H2, CO2 naphthenic acids. If 
allowed to get to the reactor they will consume caustic and oxygen and also effect catalyst 
activity. There are two inlet nozzles provided. The bottom nozzle having holes facing 
downward is provided for inlet nozzles provided. The bottom nozzle having holes facing 
downward is provided for adequate mixing of the kerosene feed and the caustic solution. 
The top nozzle having holes pointing upward is used during caustic change out only. A 
skim line is provided just below the kerosene/caustic interface to rid of any insoluble 
foreign materials accumulated at the interface. A mesh blanket at the top of vessel is 
provided to minimize caustic carry over to the reactors. 
 
 
2.1.2 MEROX REACTOR (15-R-00-001) 
 
The merox reactor contains the merox catalyst supported on a bed of activated charcoal. 
They provide means to uniformly distribute the kerosene feed and air mixture over the 
alkali catalyst bed at a pre determined residence time. The alkaline medium is provided by 
intermittently injecting caustic solution without disrupting the normal kerosene flow. The 
catalyst beds also act as filters and the reactor design will allow the entrained caustic be 
separated out at the bottom of the reactor. 
 
 
2.1.3 CAUSTIC SETTLER (15-VV-VI-001) 
 
This is a horizontal vessel where entrained caustic is gravity separated from the treated 
Kerosene. It is also the hold up tank for the wash caustic. Accumulated spent caustic in the 
settler is dumped out and can be reused in other part of the Refinery. 
 
 
2.1.4 WATER WASH (15-VV-VI-002) 
 
This is the 1
st
 of three vessels for the after treatment of the merox treated Kerosene. 
Kerosene is distributed through the bottom distributor into the deminerlized water 
continuously being injected into the vessel. Soluble soaps or surfactant are removed from 
the Kerosene. The caustic if it survives the caustic settler will also be extracted out. A 
KEROSENE MEROX UNIT 
CHAPTER-2  2 
skimmer line is provided to free the Kerosene/water interface of foaming and foreign 
materials. 
 
 
2.1.5 SALT FILTER(15-VV-VI 003) 
 
The salt filter serves as a water absorber/coalescer of the water/caustic phase material from 
the merox treated kerosene. It is packed with ¼” rock salt. The SS screen wrapped 
distributor is located at the bottom of the vessel. This vessel is effective in removing all the 
free water and up to 30% dissolved water in the kerosene. The brine water is then 
periodically drained out from the bottom of the vessel. 
 
 
2.1.6 CLAY FILTER (15-VV-VI-004) 
 
Clay filter is provided to decolourize remove metals such as copper absorb surfactants and 
remove particulate matters. Clay life will vary from about 0.1 to 15M
3
 of kerosene treated 
per Kg of clay loaded. Normally clay first loses its ability to decolourize then to remove 
metals then to remove surfactants and finally to remove particulate matters. The vessel is 
usually packed with clay of 30 x 60-mesh attapulgus type. Water causes the clay to assume 
a mud like consistency which restricted flow and is manifested by increasingly high 
pressure drop across clay bed when the pressure drop reaches 1 KG/CM
2
 the clay should 
be dumped and replaced with new load. 
 
 
2.1.7 BACK PRESSURE CONTROLLER (15-PIC-4908) 
 
The pressure on the Kerosene/ATF merox unit is controlled by 15-PIC-4908. The unit 
should run at adequate pressure to ensure air solubility in the kerosene through out the unit 
so that all vessels remain liquid full. The decreases in pressure due to pressure drop across 
various vessels should be observed. 
 
 
2.2 CAUSTIC FLOW 
 
1. 3? Be caustic is inventoried in the caustic pre wash vessel to neutralize H2S and 
organic acid oils in the Kerosene feed. As the caustic becomes “Spent” and less 
effective in acid neutralization it must be replaced with fresh solution. Caustic 
change out frequents about 7 to 10 days. Each time about 60-70% of the solution is 
replaced. 
 
2. Fresh 10 ? Be caustic is intermittently used to wash the reactor beds. This is to 
provide the alkaline medium for merox reactions. The caustic injection can be done 
without interrupting the kerosene flow. 
 
3. Injection rate should be set 20LVS of the kerosene feed rate. Duration of 15-20 
minutes is normally sufficient. However the frequency can only be determined by 
Page 3


KEROSENE MEROX UNIT 
CHAPTER-2  1 
CHAPTER-2 
 
PROCESS  DESCRIPTION 
 
 
 
2.1 HYDROCARBON FLOW 
 
2.1.1 CAUSTIC PREWASH (15-VV-VI-001) 
 
Kerosene from crude distillation unit is pumped by 15-PA-CF-003A/B to caustic pre wash. 
This vessel is half filled with 3 ? be caustic solution for the neutralization of acidic 
compounds in the kerosene feed. These acidic compounds are H2, CO2 naphthenic acids. If 
allowed to get to the reactor they will consume caustic and oxygen and also effect catalyst 
activity. There are two inlet nozzles provided. The bottom nozzle having holes facing 
downward is provided for inlet nozzles provided. The bottom nozzle having holes facing 
downward is provided for adequate mixing of the kerosene feed and the caustic solution. 
The top nozzle having holes pointing upward is used during caustic change out only. A 
skim line is provided just below the kerosene/caustic interface to rid of any insoluble 
foreign materials accumulated at the interface. A mesh blanket at the top of vessel is 
provided to minimize caustic carry over to the reactors. 
 
 
2.1.2 MEROX REACTOR (15-R-00-001) 
 
The merox reactor contains the merox catalyst supported on a bed of activated charcoal. 
They provide means to uniformly distribute the kerosene feed and air mixture over the 
alkali catalyst bed at a pre determined residence time. The alkaline medium is provided by 
intermittently injecting caustic solution without disrupting the normal kerosene flow. The 
catalyst beds also act as filters and the reactor design will allow the entrained caustic be 
separated out at the bottom of the reactor. 
 
 
2.1.3 CAUSTIC SETTLER (15-VV-VI-001) 
 
This is a horizontal vessel where entrained caustic is gravity separated from the treated 
Kerosene. It is also the hold up tank for the wash caustic. Accumulated spent caustic in the 
settler is dumped out and can be reused in other part of the Refinery. 
 
 
2.1.4 WATER WASH (15-VV-VI-002) 
 
This is the 1
st
 of three vessels for the after treatment of the merox treated Kerosene. 
Kerosene is distributed through the bottom distributor into the deminerlized water 
continuously being injected into the vessel. Soluble soaps or surfactant are removed from 
the Kerosene. The caustic if it survives the caustic settler will also be extracted out. A 
KEROSENE MEROX UNIT 
CHAPTER-2  2 
skimmer line is provided to free the Kerosene/water interface of foaming and foreign 
materials. 
 
 
2.1.5 SALT FILTER(15-VV-VI 003) 
 
The salt filter serves as a water absorber/coalescer of the water/caustic phase material from 
the merox treated kerosene. It is packed with ¼” rock salt. The SS screen wrapped 
distributor is located at the bottom of the vessel. This vessel is effective in removing all the 
free water and up to 30% dissolved water in the kerosene. The brine water is then 
periodically drained out from the bottom of the vessel. 
 
 
2.1.6 CLAY FILTER (15-VV-VI-004) 
 
Clay filter is provided to decolourize remove metals such as copper absorb surfactants and 
remove particulate matters. Clay life will vary from about 0.1 to 15M
3
 of kerosene treated 
per Kg of clay loaded. Normally clay first loses its ability to decolourize then to remove 
metals then to remove surfactants and finally to remove particulate matters. The vessel is 
usually packed with clay of 30 x 60-mesh attapulgus type. Water causes the clay to assume 
a mud like consistency which restricted flow and is manifested by increasingly high 
pressure drop across clay bed when the pressure drop reaches 1 KG/CM
2
 the clay should 
be dumped and replaced with new load. 
 
 
2.1.7 BACK PRESSURE CONTROLLER (15-PIC-4908) 
 
The pressure on the Kerosene/ATF merox unit is controlled by 15-PIC-4908. The unit 
should run at adequate pressure to ensure air solubility in the kerosene through out the unit 
so that all vessels remain liquid full. The decreases in pressure due to pressure drop across 
various vessels should be observed. 
 
 
2.2 CAUSTIC FLOW 
 
1. 3? Be caustic is inventoried in the caustic pre wash vessel to neutralize H2S and 
organic acid oils in the Kerosene feed. As the caustic becomes “Spent” and less 
effective in acid neutralization it must be replaced with fresh solution. Caustic 
change out frequents about 7 to 10 days. Each time about 60-70% of the solution is 
replaced. 
 
2. Fresh 10 ? Be caustic is intermittently used to wash the reactor beds. This is to 
provide the alkaline medium for merox reactions. The caustic injection can be done 
without interrupting the kerosene flow. 
 
3. Injection rate should be set 20LVS of the kerosene feed rate. Duration of 15-20 
minutes is normally sufficient. However the frequency can only be determined by 
KEROSENE MEROX UNIT 
CHAPTER-2  3 
operation experience on individual units as caustic demand varies with feed 
characteristics. The spent caustic will separates from the kerosene in the caustic 
settler before being pumped out to a point caustic storage. 
 
 
2.3 AIR FLOW 
 
Air is injected by means of the air compressors 12-KR-00-001A/B through the air sparger 
located upstream of the reactor. The kerosene feed rate and the mercaptan sulphur loading 
governs the air injection rate. Air must be completely dissolved in the Kerosene by 
sufficient system pressure. Undissolved air will cause channeling in the packed beds the 
charcoal salt and clay filters. It must be vented off the system and appropriate action must 
be taken to avoid this situation. Occasionally venting from the top of reactor and clay filter 
is generally practiced. 
  
  
 
 
 
 
 
 
 
 
 
 
 
 
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