Carbon dioxide refrigerating unit for artificial stratum freezing system

Abstract

The invention discloses a carbon dioxide refrigerating unit for an artificial stratum freezing system. An oil separator is sequentially connected with a liquid cooling oil cooler, an oil filter, a lubricating oil pump and a starting single-stage screw compressor; an outlet of the single-stage screw compressor is started to be connected with an air inlet of the oil separator. The oil separator is connected with a water-cooling condenser, the water-cooling condenser is connected with an economizer, the economizer is connected with a condensation evaporator, and an air outlet of the condensation evaporator is connected with the starting single-stage screw compressor; a pipeline returning from the freezing pipe is connected with a carbon dioxide liquid reservoir, an air outlet of the carbon dioxide liquid reservoir is connected with an air inlet of a condensation evaporator, a liquid outlet of the condensation evaporator is connected with a liquid return opening of the carbon dioxide liquid reservoir, and a liquid outlet of the carbon dioxide liquid reservoir is connected with a carbon dioxide shield pump. The unit is a safe, environment-friendly, energy-saving and effective carbon dioxide refrigerating unit, and the technical effect is more prominent when the unit is applied to an artificial stratum freezing system with carbon dioxide as a refrigerating medium.

Description

technical field [0001] The invention relates to a refrigeration unit using carbon dioxide as a refrigerant for an artificial formation freezing system. Background technique [0002] Artificial stratum freezing is to use refrigeration technology to freeze the water in the stratum, turn the natural rock and soil into frozen soil, and increase its strength and stability, so that the excavation and construction of tunnels, shafts or underground works can be carried out under the protection of the frozen wall. . [0003] Among the existing freezing methods, the most common and widely used method is to use calcium chloride aqueous solution as a refrigerant for freezing. There are certain efficiency and construction cost problems in the freezing of calcium chloride aqueous solution. In order to overcome the shortcomings of this method, an artificial formation freezing system using carbon dioxide as a refrigerant has appeared. For example, a Chinese utility model patent with publ...

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Problems solved by technology

[0004] First of all, during its "second cycle", the resistance along the way and the local resistance of the refrigerant are relatively large, and the resistance will cause the pressure of the refrigerant to drop below the temperature corresponding to the refrigerant after being condensed into a liquid and before entering the throttle valve. Vaporization occurs due to saturation pressure, resulting in changes in refrigerant flow, which ultimately adversely affects the cooling effect of carbon dioxide

[0005] Secondly, in the "second cycle" process, after the refrigerant absorbs heat and evaporates into a gaseous state, it will flow together with the unevaporated refrigerant liquid, causing the compressor to absorb liquid, which will cause serious damage to the compressor.

[0006] Third, the carbon dioxide liquid is pumped to the freezing pipe, which cannot adapt to the change in the volume ratio of carbon dioxide gas and liquid caused by the load change of the freezing pipe

The carbon dioxide liquid that does not need to be condensed directly enters the liquefaction structure, which will occupy the heat transfer area and affect the heat transfer efficiency

[0007] At present, there is no unit product or scheme with satisfactory effect, which can be safely, effectively and practicably applied to the artificial formation freezing system using carbon dioxide as the refrigerant

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