What causes the excessive level of benzene chloride?
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Recently, the chloride level in crude benzene has exceeded the limit. What is the reason for this? How should this be solved?
The factors contributing to the high chloride ion content in crude benzene include: 1) Excessively high chloride ion levels in the recycled washing oil and new washing oil; 2) High chloride ion levels in coke oven gas, primarily due to the use of surface coal in the coal mixture; 3) High chloride ion levels in the condensate water from superheated steam; 4) High chloride ion levels in the water used for separating crude benzene; 5) Chloride ions introduced into the system when equipment is cleaned with hydrochloric acid; 6) Chloride ions introduced as a result of leaks in heat exchange equipment. (2) Control measures or methods for identifying the causes: 1) Keep the chloride ion content in the newly washed oil entering the plant below 15 × 10⁻⁶; 2) Improve the quality of the oil by enhancing the slag removal process during washing, and strictly control the quality of the recycled washing oil; 3) Maintain proper temperatures at the top of the benzene removal tower and during the cooling and separation of crude benzene, and improve the oil-water separation process; 4) Regularly analyze the chloride ion content in steam condensate to keep the chloride ion content in the water used in the furnace system under control; 5) Check whether there are any leaks in the crude benzene condensation coolers; 6) Thoroughly wash and purge the equipment to be used for cleaning, in order to prevent cleaning fluids from entering the system; 7) Ensure high quality coal is used, so as to reduce or eliminate the impact of surface coal on the chloride ion content in gas and crude benzene.
1) What should be the maximum allowable chloride ion content in the recycled washing oil, the new washing oil, and coke oven gas? Are there any standards for this?