Low top temperature of the fractionation tower and high dry point of gasoline
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After the modification of the compressor in our unit, the amount of condensate in the second stage of the compressor increased by 7 tons. Currently, the temperature at the top of the fractionator is 100°C, and the dry point of the gasoline is 204°C. At present, the amount of overhead recycle has been increased, as has the rate of cold reflux; however, the dry point remains at 203°C and shows no sign of decreasing. We kindly request guidance from all experts.
Increase the amount of stripping steam to raise the partial pressure of oil vapor； Lower the reaction temperature to reduce the gas-phase load ； Increasing the pressure at the top of the fractionation tower can be controlled by adjusting the turbine speed ； Increase the flow rates to various stages, such as the flow returning to the tower at the top and the flow returning to the tower in the middle section
Cold reflux: if crude gasoline is used for cold reflux, there is no need for it when the overhead circulation volume is normal. Cold reflux increases the load on the tower top, which hinders the control of the dry point of the gasoline
The dry point of gasoline in the secondary processing equipment is 204°C, which exactly meets the requirement specified in the GB 17930-2016 standard for automotive gasoline, namely that the final boiling point should not be higher than 205°C.
We are now asking for less gasoline to be produced, with the temperature to be kept below 203 degrees
Reducing gasoline production mainly involves lowering the reaction temperature; relying solely on the top temperature and reflux pressure is not very effective for control
Increase backflow at the first stage to enhance heat extraction in the middle stage
It is recommended to also consider the equipment issues related to the trays or floating valves in the top circulation section of the tower
The two-stage condensed liquid should be pumped to E301; returning it to E201 will cause excessive load on the first stage and second stage of the vapor compressor, as well as shaft alignment issues. The condensed liquid is sent back to the distillation section; it may seem that stopping one pump saves energy, but in reality it increases the load on the vapor compressor, resulting in **higher energy consumption**. Also: By how many degrees is the temperature at the top of the distillation tower reduced to 100°C? Has there been any change in the pressure at the top of the tower?
Refer to the changes in various parameters and compare them with previous production results, to see if there is any possibility of salt deposition.