Coal tar distillation operation guide

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Operating Instructions for Coal Tar Distillation (SJ—019) 1. Scope: These instructions specify the operating methods for the tar distillation production unit in our company. Suitable for coal tar distillation operations. II. Referenced standards and quality requirements (enterprise standards): Raw material: Coal tar, YB/T 5075–93. Parameter names and values: Density (20°C): 1.13–1.22 g/cm3; Moisture, %: not more than 4.0%; Ash content, %: not more than 0.13%; Naphthalene content (anhydrous basis), %: not less than 7.0%. III. Overview of the processing process: Coal tar with low moisture content (below 4%) is first allowed to settle, clarify, and lose water. It is then heated by a pump and a steam preheater to a temperature of 110–120°C, after which it enters the convective section of a tubular furnace to be heated further to 120–135°C. Finally, it goes into a primary evaporator for evaporation and dehydration. Some of the light components evaporate rapidly due to the reduced pressure; oil, water, and gas escape from the top. After passing through the cooler and oil-water separator, the light oil goes into the light oil tank while the wastewater goes into the wastewater tank. After dehydration, the moisture content in the coal tar (anhydrous tar) drops below 0.4%, and it is then stored in the anhydrous tar tank. Anhydrous tar is pumped out from the bottom of the anhydrous tar tank using a two-stage pump and sent to the radiant section of the tubular heater, where it is heated to 370–390°C before entering the secondary evaporator (tower) for vaporization and separation. The carbon black oil extracted from the bottom of the tower flows by gravity to a high-level tank for carbon black oil, where it is used by the carbon black factory after being vaporized and cooled. Naphthene oil reflux is used at the secondary tower top to control the tower top temperature. The mixed oil and gas at the top of the secondary tower enters the fractionation tower. The anthracene oil fraction is collected by overflow from the bottom of the tower; after cooling, it enters the anthracene oil tank. Part of it is used as reflux at the top of the secondary tower, while another part is sent to the carbon black oil storage tank. The fraction tower side stream is used to extract the triple mixture oil fraction; after cooling, it enters the triple mixture oil tank for washing in the next processing step. Light oil escapes from the top of the distillation column, is cooled by condensation, then enters the oil-water separator before going into the light oil tank for use as reflux in the column; the wastewater is sent to the wastewater tank. IV. Operating Procedures for Tar Distillation (Method) 1. Process control parameters and operational parameters 1) Process control parameters for tar distillation fractions: Light oil: Phenol content