Device and method for recovering ammonia and tert-butyl alcohol in cyclohexanone ammoximation production process

Abstract

The invention discloses a device and a method for recovering ammonia and tert-butyl alcohol in a cyclohexanone ammoximation production process. The device consists of an oximation reaction system, a reaction product pre-separation system, a tert-butyl alcohol rectification recovery system, a reaction tail gas condensation system and a reaction tail gas absorption system. According to the invention, the reaction tail gas absorption system adopts two-stage absorption of tert-butyl alcohol and water, so that the desalted water amount for absorption is greatly reduced, the ammonia, tert-butyl alcohol and water amount to the tert-butyl alcohol rectification recovery system are reduced, the water amount in the cyclohexanone-oxime aqueous solution is reduced, and the toluene circulation amount and energy consumption of a downstream cyclohexanone-oxime refining system are favorably reduced; the reaction product pretreatment system is arranged, so that the treatment load of the tert-butyl alcohol rectification recovery system can be reduced, and the condensation effect of the rectification tower I is improved; double-effect rectification is adopted in the rectification recovery system, anda condensation, absorption and vacuum pressurization combined process is adopted in rectification of non-condensable gas, so that the vacuum load and chilled water consumption are reduced; and the steam consumption can be saved by 40-50%, the cooling water consumption can be reduced by 35-50%, the chilled water consumption can be reduced by 10%, the desalted water consumption can be reduced by more than 50%, the treatment load of related facilities can be reduced, and the energy can be saved.

Description

technical field [0001] The invention relates to the technical field of caprolactam, in particular to a cyclohexanone ammoximation production technology, in particular to an ammonia and tert-butanol recovery device and method in the cyclohexanone ammoximation production process. Background technique [0002] Cyclohexanone oxime is a key intermediate product in the production of caprolactam. Using titanium silicon molecular sieve as a catalyst to carry out ammoximation reaction of cyclohexanone, ammonia and hydrogen peroxide is a process for preparing cyclohexanone oxime. In the method disclosed in USP5227525 , the added tert-butanol is used as a solvent and does not participate in the reaction. The amount of tert-butanol used as a solvent is 2 to 5 times that of cyclohexanone. After the reaction is completed, tert-butanol exists in the reaction solution and reaction tail gas, and tert-butanol needs to be recovered And recycling, recovery process energy consumption is high; Si...

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Problems solved by technology

[0006] 3. A large amount of desalted water is required to absorb ammonia and tert-butanol. The aqueous solution containing ammonia and tert-butanol with low concentration is discharged from the reaction tail gas absorption system tower, which needs to be sent to the tert-butanol rectification recovery system for recovery. ammonia, tert-butanol, increased the processing load and energy consumption of the rectification recovery system, and increased the amount of water in the cyclohexanone oxime aqueous solution discharged from the rectification system, thereby increasing the downstream cyclohexanone oxime refining The processing load and energy consumption of the system, as well as the wastewater discharge of the device

[0007] 4. The rectification of tert-butanol adopts single-effect rectification, and the energy is not fully utilized; or simply adopts conventional two-effect rectification, a large amount of ammonia is dissolved in the feed reaction liquid and directly enters the vacuum rectification tower, and a large amount of ammonia does not condense Gas not only affects the condensation effect of the vacuum distillation tower condenser, but also increases the consumption of chilled water

[0008] 5. The ammonia-containing non-condensable gas discharged from the cooling water condenser is treated by low-temperature cooling and condensation, or low-temperature cooling and condensation plus simple showering. It is difficult to greatly reduce the amount of gas entering the vacuum facility, thereby increasing the energy of the vacuum facility. consumption

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