Improved method for producing food grade liquid carbon dioxide product and distillation and purification tower

Abstract

The invention relates to a method for producing carbon dioxide and in particular discloses a method for producing a food grade liquid carbon dioxide product. The method comprises the following steps of: (1) compressing; (2) dealkylating; (3) purifying; (4) liquefying; and (5) performing distillation and purification, wherein flashing gas rises and passes through structured packing of a lower corrugated plate, structured packing of an upper corrugated plate, tube pass of a lower heat exchanger and tube pass of an upper heat exchanger, and finally, the flashing gas becomes a gas mixture containing a little uncooled carbon dioxide gas and lots of methane, ethylene and oxygen and is exhausted from the top of the distillation and purification tower. By the method, the yield of the food grade liquid carbon dioxide product is improved.

Description

technical field [0001] The present invention relates generally to methods for producing carbon dioxide, and in particular to improved methods for producing food-grade liquid carbon dioxide products. Background technique [0002] image 3 A flow chart showing a production method of a food-grade liquid carbon dioxide product comprises the following steps: [0003] (1) Compression process 30 [0004] The carbon dioxide raw material gas containing mechanical water, methane, ethylene, benzene and other impurities with a carbon dioxide content of about 99.2% from outside the boundary area is washed with water, and the chemical reaction that is mediated by the regulating valve 2 controlled by the orifice flowmeter 1 is slightly adjusted. The excess oxygen is mixed and enters the pre-cooler 10 for pre-cooling. After the mechanical water is removed by the first water separator 20, it enters the compression process 30. The pressure is raised to 0.1-0.35Mpa by the first-stage compress...

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Problems solved by technology

[0026] The gas mixture containing a small amount of uncondensed carbon dioxide gas and a large amount of methane, ethylene, and oxygen discharged from the top of the distillation purification tower 101 in the distillation purification process 100, after being throttled and expanded by the regulating valve 1013, the temperature decreases, and enters the heat exchange at the top of the distillation purification tower 101 The shell side of the heat exchanger 1012 exchanges heat with the flash steam rising in the tube side of the heat exchanger 1012. Part of the uncondensed carbon dioxide gas in the flash steam is condensed and falls into the bottom of the distillation and purification tower 101. During this process, due to economical The low-temperature gas after the expansion of the stream is not enough to completely cool the gaseous carbon dioxide in the flash gas, and the cooling capacity is insufficient, resulting in serious loss of carbon dioxide

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