System for preparing solid-gas flow state dry ice based on CO2 cascade refrigeration twice throttling

Abstract

The invention discloses a system for preparing the solid-gas flow state dry ice based on the CO2 cascade refrigeration twice throttling. The system comprises a high-temperature-stage refrigeration loop, a low-temperature-stage refrigeration loop and a CO2 twice throttling structure; and according to a closed preparation loop disclosed by the invention, solid-gas flow state dry ice is prepared froma small amount of initial CO2 raw material gas, so that the cost is reduced, the production continuity is ensured, the fluidity of a prepared solid-gas flow state dry ice product is better than thatof a dry ice solid, the temperature uniformity of a cooled object is improved, and a cascade refrigeration and twice throttling system with accurate temperature control improves the stability of the solid-gas flow state dry ice product preparation. The system for preparing the solid-gas flow state dry ice based on the CO2 cascade refrigeration twice throttling has the advantages of stability, reliability, high refrigerating capacity, low operation cost, environmental friendliness and the like.

Description

technical field [0001] The invention belongs to the technical field of refrigeration, in particular to a CO-based 2 Cascade refrigeration twice throttling system for preparing solid-gas dry ice. Background technique [0002] Dry ice is CO 2 In the solid state form, its temperature at normal pressure is -78.5°C, its latent heat of vaporization is 573kJ / kg, and 1kg of dry ice turns into CO at 25°C 2 The gas can absorb 653kJ of heat; in contrast, 1kg of liquid nitrogen (-196°C) to 25°C nitrogen absorbs 411kJ of heat, which is only 60% of dry ice. It can be seen that dry ice has a large cooling capacity, coupled with its rapid sublimation under normal pressure, and is safe and non-toxic, so it is widely used in the freezing industry. [0003] At present, the preparation of dry ice industry mainly uses high-pressure CO 2 Liquid as raw material; CO 2 The liquid is discharged from the storage tank and forms a solid-gas two-phase state after being throttled by the throttle valv...

AI Technical Summary

Problems solved by technology

[0004] The preparation and utilization process of dry ice is simple and reliable, but there are still four disadvantages: one is that the raw material is CO 2 liquid, requires upstream CO 2 The gas liquefaction link increases the cost; second, the dry ice preparation process requires frequent replacement of liquid CO 2 Storage tanks cannot achieve continuous production and application; third, when dry ice is used for freezing, it is mainly statically sublimated and has no fluidity, which is not conducive to the control and uniform distribution of cooling capacity; fourth, the raw materials cannot be recycled, and waste is relatively large. many and bad for the environment

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