System and method for preparing high purity carbon monoxide and hydrogen-enriched co-production liquid methane

Abstract

The invention relates to the field of low-temperature gas separation, in particular to a system and method for preparing high purity carbon monoxide and hydrogen-enriched co-production liquid methane. The system mainly comprises a raw material gas purification unit, a low-temperature liquefying separation unit, a CO product compressor and a mixed refrigerant compressor. The low-temperature liquefying separation unit comprises a main heat exchanger, a methane washing tower, a dehydrogenation tower, a demethanization tower and a denitrification tower. A first evaporator is arranged at the bottom of the dehydrogenation tower; a second evaporator is arranged at the bottom of the demethanization tower; a first condenser is arranged on the top of the demethanization tower; a third evaporator is arranged at the bottom of the denitrification tower; and a second condenser is arranged on the top of the denitrification tower. According to the system and method, while high purity products rich in H2 and CO are obtained through four-tower process flow, high purity liquid methane can be obtained; the adaptability of a device to raw material gas is high; the requirement for raw material gas purities of the device is lowered; and part of CO is extracted from the tail stage or the middle stage of the CO product compressor to be used as a cold source and a heat source of a rectifying tower circularly according to the pressure of CO product gas, a nitrogen compressor and an expander are omitted, the number of devices is small, and the investment is small.

Description

technical field [0001] The invention relates to the field of gas low-temperature separation, in particular to a system and method for producing high-purity carbon monoxide and hydrogen-rich gas to co-produce liquid methane. Background technique [0002] CO and H 2 It is an important synthetic raw material in the chemical process, and is widely used in the synthesis of a series of organic chemical products and intermediates, while CO and H 2 The preparation of coal, natural gas or oil is generally used as raw materials, and it is obtained through a certain method transformation. In the preparation process, the effective components CO and H are removed. 2 In addition, a certain amount of CH 4 , N 2 , CO 2 Such impurities exist in the form of mixtures, and chemical synthesis processes usually require high-purity CO, which requires a suitable method to separate and purify the mixture. [0003] CO and H 2 The separation methods mainly include pressure swing adsorption, mem...

AI Technical Summary

Problems solved by technology

[0004] Liquid methane is a clean and efficient energy source with high calorific value and easy transportation. The CO and H released by China 2 In the low temperature separation and purification method, only CO and H are considered 2 Separation and purification, in the case of high content of nitrogen and methane, methane is discharged together with other impurities as fuel, the value of methane has not been rationally utilized, and the application number is 201510014562.6, the name is a synthesis gas separation to produce hydrogen and high The Chinese patent of the method and device for pure carbon monoxide uses multi-tower separation in the case of complex impurity content, but needs to add nitrogen cycle compression and expansion machines, the process is complicated, there are many machines, high energy consumption, and there is no proposal for methane Reasonable use

Images