ECH

Epichlorohydrin（ECH）

1. Product Overview
The glycerin-based epichlorohydrin process (calcium method) uses 99.5% glycerin, hydrogen chloride, and lime emulsion as raw materials. The product meets the requirements for premium-grade epichlorohydrin as specified in the national standard "Epichlorohydrin for Industrial Use" (GB/T 13097-2015). By-products include liquid calcium chloride antifreeze or dihydrate calcium chloride (flake form).

2. Process Flow
2.1 Chlorohydrination Section
Glycerin from the tank farm is preheated to a specified temperature and then fed into the reactor. (catalyst is initially added at a certain ratio, with subsequent intermittent additions as required). Simultaneously, HCl gas from outside the battery limits is introduced into the reactor, and the reaction temperature is maintained at 60-120℃.The reaction continuously generates dichloropropanol (which exists in two isomeric forms: 2,3-dichloro-1-propanol and 1,3-dichloro-2-propanol, with the latter accounting for over 90% of the total dichloropropanol mass; both isomers yield epichlorohydrin upon cyclization). Material inside the reactors is then transferred by liquid pump to the chlorination distillation section.
The chlorination reaction equation is as follows:

C₃H₈O₃+2HCl→C₃H₆Cl₂O+2H₂O

2.2 Dichloropropanol Purification Section
The dichloropropanol-containing material fully reacted in the reactors is transferred by the reactor discharge pump to the stripping column, where it is heated by the reboiler to vaporize hydrogen chloride and part of the water generated during the reaction. The overhead vapor is condensed through the overhead condenser, and the condensate is returned to the stripping column as reflux, while the uncondensed hydrogen chloride is sent to the glycerin absorption system. The bottom material from the distillation column is delivered by the distillation column bottom pump to the DCH crude distillation column.
The material from the distillation column bottom pump is heated in the crude distillation column by the reboiler. The distilled water and dichloropropanol are condensed through the overhead condenser. The condensed dichloropropanol flows to the DCH crude distillation column overhead receiver and is then pumped to the DCH oil phase tank. The bottom material from the DCH crude distillation column is sent by pump to the DCH refining column for further purification.
The material from the crude distillation column bottom pump is heated in the refining column by the reboiler. The distilled dichloropropanol is condensed through the condenser, and the condensate enters the DCH refining column overhead receiver, from which it is pumped to the DCH oil phase tank. The bottom material from the DCH refining column is returned to the reaction system by pump, with a portion periodically sent to the dichloropropanol recovery  tower for recovery of dichloropropanol from the material. The residual liquid is transferred to the incineration system or sent off-site for disposal.
2.3 Cyclization Section
The dichloropropanol oil phase and azeotropic liquid from the tank farm, together with lime emulsion from outside the battery limits, are mixed and reacted in a pipeline before entering the cyclization tower. The crude epichlorohydrin stripped by steam is condensed into the oil-water separator, where the liquid layers separate after settling. The upper aqueous phase is returned to the cyclization tower, while the lower layer is crude epichlorohydrin, which is sent to the cyclization distillation section. The tower bottoms are cyclization liquor, which, after de-alkalization and impurity removal, is concentrated to a 32% calcium chloride mother liquor for sale as antifreeze (if this portion of the cyclization liquor is not sold as a product, it may be sent to the wastewater treatment facility for discharge after treatment, generating a 14% calcium chloride mother liquor generated).
The cyclization reaction equation is as follows:

2C₃H₆Cl₂O+Ca(OH)₂→2C₃H₅C1O+CaCl₂+2H₂O

2.4 Cyclization Distillation Section
The crude epichlorohydrin obtained from the cyclization reaction is subjected to vacuum distillation. It first enters the dehydration column, where the reboiler temperature is controlled to distill off low-boiling water and a small amount of epichlorohydrin. The overhead vapor is condensed, and the condensate is collected in a phase separation tank. The aqueous phase is sent to the cyclization oil-water separator for layer separation, while the oil phase is returned to the dehydration column (depending on production requirements, the oil phase may be periodically or continuously partially withdrawn to the light component tower to remove low-boiling organics before being returned to the dehydration column). The bottom material from the dehydration column is fed to the distillation column, where the reboiler temperature is controlled to distill off the product epichlorohydrin. The overhead vapor is condensed, and the condensate is collected in a finished product receiver tank for sale. The bottom material from the distillation column is sent to the epichlorohydrin recovery column to recover epichlorohydrin from the column bottoms.
2.5 Filter Pressing Process
The cyclization wastewater suspension from the cyclization section is transferred to the cyclization liquor tank and then fed by the cyclization liquor feed pump to the filter press for filter pressing. The resulting lime filter cake is disposed of as general solid waste, while the calcium chloride clear filtrate is sent either to the concentration unit or to the wastewater treatment facility.
The process block diagram is as follows:

2.6 Evaporation, Drying and Packaging Section
The calcium chloride clear solution from the filter pressing section is transferred by pipeline to the 15% calcium chloride feed tank for storage. Hydrochloric acid is added to the 15% calcium chloride feed tank to remove calcium hydroxide from the solution, in order to prevent fouling of downstream heat exchangers. The calcium chloride solution is then sent to the cyclization section for evaporation. After cyclization evaporation, the calcium chloride solution (approximately 25%–27%) is sent to the evaporation, drying and packaging section for two-effect evaporation.The calcium chloride solution first enters the II-effect evaporation feed preheater and is preheated to 90℃. Low-pressure steam (0.6 MPa) is supplied to the I-effect evaporator (at 130℃) to obtain a calcium chloride solution of approximately 34%. The vapor generated from the I-effect evaporator is used to heat the II-effect evaporator (at 90℃), producing a calcium chloride solution of approximately 40%. The process vapor from evaporation is condensed through the II-effect evaporator condensers (first-stage and second-stage cooling). The condensed wastewater is collected in the II-effect wastewater collection tank and sent by the wastewater discharge pump to the wastewater treatment section. The calcium chloride solution at this stage is transferred to the 40% calcium liquor conditioning tank, and then pumped out by the 40% calcium chloride conditioning pump for decolorization and filtration. The filtrate is transferred to the rising film buffer tank, preheated to 90℃ through the rising film feed preheater, and then fed into the rising film evaporator. The rising film evaporator is supplied with steam at 1.3 MPa and 180℃, producing calcium chloride at approximately 65%–70%, which is then sent to the 70% calcium liquor buffer tank.The calcium chloride is fed through a flaker, and the flaked material enters a fluidized bed dryer, where it is mixed with dry air introduced from the bottom of the fluidized bed for fluidized drying to produce 75% calcium chloride. The hot air is discharged from the top of the fluidized bed to a dust scrubber, and then vented to the atmosphere through a collection box. The dried calcium chloride flakes are conveyed by a calcium flake cooler and a bucket elevator to a rotary screen, and then sent through a finished product silo to a bagging machine for packaging as finished product (25kg/bag). Oversized particles separated by the rotary screen are packaged by a chute.