The coke oven gas-to-LNG plant designed by Anhui Huadong Chemical and Medical Engineering Co., Ltd. with the technologies supplied by Shanghai Huaxi Chemical Industry Science & Technology Co., Ltd. was successfully commissioned on October 12, 2013 at the first time. The plant was capable of producing conforming LNG product and the total hydrocarbon content of LNG exceeded 98%.
The plant had a coke oven gas processing capacity of 18,000m3n/h and could produce LNG at 6000m3n/h. The process was composed of coke oven gas pre-treatment, fine desulfurization, one-stage isothermal methanation, dehydration, copious cooling and other steps.
Among them, coke oven gas pretreatment, fine desulfurization and one-stage isothermal methanation were the technologies developed by Shanghai Huaxi.
The successful start-up of the plant allowed the great amount of byproduct, i.e. coke oven gas, near Wuhai of Inner Mongolia, to be well applied. Such a plant was cost effective, had social benefits and could reduce environment pollutions. Especially, as the price of LNG rose significantly in recent days, the coke oven gas-to-LNG plant is bound to make an increasing profit.
The core technologies adopted by the plant:
1. Advanced pretreatment and desulfurization technology: The leading and advanced coke oven gas pretreatment technologies and the rich engineering experience of Shanghai Huaxi (incorporate the coke oven gas pretreatment function into over 20 sets of unit and the maximum coke oven gas pretreatment capacity of single set could reach 260,000m3/h) were a guarantee for the impurity content of the pretreated coke oven gas to fully meet the requirement of methanation reaction and satisfy the requirement of LNG for extremely low impurity content and they also guaranteed the long-term safe operation of the methanation part as well as the cryogenic cooling part.
2. Advanced one-stage isothermal methanation technology: The one-stage isothermal methanation technology developed independently by Shanghai Huaxi was adopted. In this technology, two to three less adiabatic reactors, three to four less steam generator systems and one less large cyclic compressor were used than the multi-stage isothermal methanation technologies used by overseas LURGE, TOPSO, DAVID and others companies. With the technology, the investment could be saved by more than 70% and it also helped clients save nearly RMB10,000,000 yuan patent fees. The required energy consumption during operation was also decreased significantly. It was a pioneering technology in China and even in the world. It has carved out a new area for reuse of coke oven gas, significantly increasing the added value of coke oven gas resources.
The coke oven gas-to-LNG production project has become one of the hot integrated application technologies of coke oven gas and the methanation technology was also the key in coke oven gas-to-LNG production project or coal-to-LNG production project. So far this technology has not been put into long-term commercial application yet. Shanghai Huaxi’s isothermal methanation reactor technology was featured by short process, low energy consumption and low investment. The LNG plant that adopted this technology went into operation smoothly in Qujing Qilin Gas Energy Co., Ltd. and Etuokeqijianyuan Coking Co., Ltd., offering a new process for domestic coke oven gas-to-LNG production in the future and providing valuable data and experiences for industrialization of coke oven gas-to-LNG production.