Membrane separation method and device for recycling hydrogen from purge gas of synthetic ammonia liquid ammonia storage tank

A technology for releasing gas and membrane separation, applied in hydrogen separation, using solid contact hydrogen separation, etc., can solve the problems of poor effect, can not guarantee the safety of membrane use, poor technical and economical, low pressure, etc., to ensure long-term stable operation , to ensure the stability of the device operation, to ensure the effect of not being damaged

Inactive Publication Date: 2012-06-27
TIANBANG NAT ENG RES CENT OF MEMBRANE TECH
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AI Technical Summary

Problems solved by technology

The traditional method of ammonia synthesis plant is to pass the liquid ammonia storage tank relaxation gas through the equal pressure recovery tower to absorb the ammonia in water and then burn or discharge it, which causes a lot of waste of resources
Due to the relatively small discharge of ammonia tank release gas, low pressure (1.5-2.5 MPa), and high ammonia content, when hydrogen is recovered by cryogenic method or pressure swing adsorption method, the equipment investment is large, the energy consumption is high, and the hydrogen recovery rate is high. Low, complex operation, poor technical and economical, rarely used
There are two main problems to be solved in the membrane separation method: poor pre-treatment low-pressure ammonia washing effect cannot guarantee the safety of the membrane; low-pressure operation has a low hydrogen recovery rate
Before these two problems are solved, the industrial application of membrane separation method is limited.

Method used

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  • Membrane separation method and device for recycling hydrogen from purge gas of synthetic ammonia liquid ammonia storage tank
  • Membrane separation method and device for recycling hydrogen from purge gas of synthetic ammonia liquid ammonia storage tank

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] The vented gas from the liquid ammonia storage tank first enters the low-pressure high-efficiency packed ammonia absorption tower 1, where the gas contacts with the desalted water pumped in by the water pump 6 countercurrently in the packing layer, and the ammonia (NH 3) is absorbed by water and becomes ammonia water, which is discharged from the bottom of the tower. The deammoniated gas is discharged from the top of the tower and then enters the gas-liquid separator 2, so that the mist entrainment generated during the water washing process is separated. The purpose of water washing is mainly to purify the vent gas of the liquid ammonia storage tank, remove the ammonia therein, so that the residual ammonia content meets the safety requirements of the membrane separator 4, and the ammonia content of the gas after washing should be lower than 20ppm. The gas from the top of the tower is usually around 25°C. The gas-liquid two-phase balance in the water washing process mak...

Embodiment 2

[0042] The purge gas is heated to 55° C. in a heater, and the specific implementation is the same as in Example 1.

[0043] After testing, the hydrogen recovery rate of the present invention reaches 93.66%, and the hydrogen mole fraction of the recovered gas reaches 89.57%. The specific data are shown in Table 2.

[0044] Table 2

[0045]

[0046] It can be concluded from the test data that it is completely feasible to recover the hydrogen in the vent gas of the liquid ammonia storage tank by the membrane separation method, and the investment payback period is less than 3 months. Promotion and application value.

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Abstract

The invention relates to a membrane separation method for recycling hydrogen from purge gas of a liquid ammonia storage tank of synthetic ammonia. The method is characterized by comprising the following steps of: 1) absorbing treatment of the ammonia of the purge gas; 2) gas-liquid separation treatment; 3) membrane separation treatment; and 4) gas aftertreatment. According to the invention, the key problem that the application of the membrane separation method in the purge gas hydrogen recycling field is blocked, namely, the problems of deep ammonia removal at low pressure and low hydrogen recycling rate of membrane separation in case of low pressure difference, are solved. Meanwhile, by using a complete automatic control system, each technical parameter of the device is monitored in real time and the membrane separation device is ensured to stably operate for a long period. Compared with deep cold method and pressure swing adsorption method, the membrane separation method for recycling the hydrogen, provided by the invention, has the advantage of overcoming defects of large equipment investment, high energy consumption, low hydrogen recycling rate, poor technicality and economics and the like in the traditional hydrogen recycling method.

Description

technical field [0001] The invention belongs to the field of synthetic ammonia industry, and in particular relates to a membrane separation method and a device for recovering hydrogen from the release gas of a synthetic ammonia liquid ammonia storage tank. Background technique [0002] The synthetic ammonia industry is a basic chemical industry and occupies a very important position in the chemical industry. Synthetic ammonia is widely used in the production of chemical fertilizers, various ammonium salts, nitric acid, explosives, plastics, synthetic fibers, paints, photosensitive materials and other products. At present, the annual output of synthetic ammonia in China is more than 50 million tons, accounting for about one-third of the world's output. With the global population reaching 7 billion people and showing a rapid growth trend, the demand for increasing crop production and expanding the green area of ​​the environment determines the increase in the demand for synth...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B3/56
Inventor 徐徜徉李屹尹中升杨文皓单世东邝怡超
Owner TIANBANG NAT ENG RES CENT OF MEMBRANE TECH
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