Introduction to the crude benzene process in the chemical production workshop and process control parameters

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This post was last edited by wangshaobo on 2025-5-24 at 16:44. For the benzene washing process: The gas coming from the thiamine production section has a temperature of around 55°C. To cool this raw gas and further remove tar and naphthalene from it, the gas flows from top to bottom through the tubes of the final cooler, where it exchanges heat with the circulating water and refrigerant water in the upper and lower sections, resulting in a temperature reduction from 55°C to 24–27°C. After that, the gas enters the bottom of the benzene washing tower, where it comes into counterflow contact with the oil-poor liquid sprayed from the top of the tower. The benzene in the gas is absorbed by the circulating washing oil; after that, the gas passes through the mist removal section of the tower to have any mist droplets removed, and then leaves the tower via the outer pipes and is sent to various users. The rich oil at the bottom of the benzene washing tower is pressurized by a rich oil pump, then passes through a crude benzene condenser and an oil-to-oil heat exchanger before entering a tubular heater where it is heated to 180–190°C. The heated rich oil subsequently enters a debenzing tower for distillation to remove benzene. A portion of it can be returned to the top of the benzene washing tower for spraying to reduce resistance. The crude benzene oil-water mixture vapor evaporating from the top of the debenzing tower enters the crude benzene condenser, where it exchanges heat with rich oil and cooling water until the temperature reaches 25–30°C, after which it goes into the crude benzene oil-water separator for separation. The separated crude benzene is sent to the crude benzene reflux tank; part of it is pumped by a crude benzene reflux pump to the top of the benzene removal tower for reflux, while the rest overflows into the crude benzene metering tank. The products are analyzed and tested in the metering tank; those that pass the tests are sent to the crude benzene storage tank for loading and sale, while those that fail the tests are pumped back to the top of the debenzening tower via a crude benzene reflux pump. The separated oil-water mixture enters a control separator, where the washed oil is sent to an underground discharge tank; from there, it is pumped to an oil-poor tank using a submersible pump. The water separated from the crude benzene flows automatically into the water seal tank of the final cooler. The heat-poor oil after benzene removal flows out from the bottom of the benzene removal tower, flows automatically into the oil-oil heat exchanger where it exchanges heat with the rich oil, and then enters the poor oil tank. After being pressurized by a poor oil pump, it passes through a poor oil cooler and is cooled to 27–30°C using circulating water or chilled water, before being sent to the benzene washing tower to spray and wash the gas. To improve the distillation efficiency and obtain multiple products, naphthalene oil side streams are taken from the 5th, 7th, and 9th trays of the debenzing tower. Direct steam with a temperature of 155–160°C and a pressure of ≥0.4 Mpa is heated to around 400°C in a tubular furnace; part of this steam is used as a heat source for the oil washing regenerator, while another part is used as a heat source at the bottom of the debenzing tower. During the operation of the benzene washing tower, to ensure the quality of the circulating washing oil, 1-1.5% of lean oil is taken from the bottom of the benzene removal tower or from the oil-rich pipeline after being heated by a tubular heater, and fed into the regenerator where it is regenerated using superheated steam generated by the tubular heater. The oil-gas mixture enters the bottom of the benzene removal tower as a source of vapor for benzene removal, while the residue is removed periodically. The remaining ammonia water and light tar sent from the cold drum section are sprayed onto the upper and lower sections of the final cooler; the liquid returned along with the gas condensate flow into the condensate water seal tank, from where it overflows into the condensate storage tank. The condensate is then pumped by a condensate circulation pump to the mechanical ammonia water clarification tank in the cold drum section. II. Process Parameters – Benzene washing section 1. Temperature parameters: (1) Temperature of the gas coming from ammonium sulfate: ≤55°C (2) Temperature of the gas entering the benzene washing tower: 24–27°C (3) Temperature of the circulating water: 32–40°C (4) Temperature of the cooling water: 16–23°C (5) Temperature of the lean oil entering the benzene washing tower: 26–30°C; in summer, this temperature is 2–3°C higher than that of the gas, and in winter it is 4–7°C higher. (6) Temperatures of the bearings in various pumps: