VPSA Technology Help in Tail Gas Utilization

time 2018-09-07

The first coke oven gas ethylene glycol production project in the world 

Recently, Jianyuan coal coking co. LTD. Held the start ceremony of 240,000 tons per year ethylene glycol project in the ordos city. The project uses coke oven gas as the feed gas, which marked the world's first Ethylene glycol from coke oven gas project officially broke ground.

As raw material, 64500 nm3 /h coke oven gas has process of storage, pressurized, pure oxygen no-catalytic conversion, decarburization-desulfurization, desulfurization, syngas purification, ethylene glycol synthesis and rectification, than products 240000 tons ethylene glycol per year. Beijing Peking University Pioneer Technology Co., Ltd. Supplies CO separation plant (25098Nm3 / h, purity> 99%) and H2 plant (53512Nm3 / h, purity> 99%) for coke oven gas in this project.

After pretreatment, coke oven gas contains about 11% nitrogen and 5% methane, both of them are in a high content level, making it more difficult to purify CO. Using CO purified from coke oven gas to product ethylene glycol, the quality of CO directly affects the operation cost. In actual operation, due to the difference in coal quality and coke oven conditions, the gas composition may fluctuate within a certain range. For example, when the content of nitrogen  increases, the CO separated by cold box may fail to meet the requirement, or the operation cost will increase dramatically. Therefore, whether the equipment has a strong separation ability of N2/ CO is the key and difficult point to keep the quality of CO. 

In the early stage of the process design, the company has a strict comparison between PSA and cold box.
PKU Pioneer has rich engineering reference of separating H2, CO in the field of ethylene glycol in the recent years.
And, even with a high content of nitrogen, the PSA CO plant will not be affected, can still run with high purity, high yield and low energy consumption. This technical advantage cannot be achieved by other gas separation technologies. Even the foreign gas giants can’t realize this goal in this field.

At present, coke oven gas recovery is mainly applied in the fields of gas, power generation and ammonia production, but the economic benefits are general and the value of coke oven gas isn’t utilized to the maximum extent. Over the past ten years, China' s methanol production industry of coke oven gas has developed rapidly, but domestic methanol production capacity is seriously excessive. The process of ethylene glycol synthesis from coke oven gas provides a new way for the efficient utilization of coke oven gas. Coke oven gas can be transformed into chemical products with better benefits. From the comparison of the added value of derivative chemicals, ethylene glycol is one of the important routes of the new coal coke chemical industry. The PSA separation technology of CO and H2 provides technical guarantee for the coke oven gas producing ethylene glycol, solves the problem of efficient purification of CO in raw gas and obtains economically feasible gas separation solutions.

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