Don’t underestimate the conversion of coke oven gas into natural gas

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Don’t underestimate the use of coke oven gas to produce natural gas. Author/Source: Huahua Network – Coal Chemical Industry. Date: October 20, 2018. Clicks: 44. In recent years, China has implemented an access control system for the coking industry, and the comprehensive utilization of coke oven gas has become crucial for the survival and development of coking enterprises. Meanwhile, natural gas is gaining increasing popularity as a clean energy source, and many **consider liquefied natural gas to be the preferred fuel. The share of natural gas in energy supply is increasing rapidly, with liquefied natural gas in particular growing at a rate of about 12% per year, making it one of the fastest-growing energy sources globally. According to a report by the International Energy Agency, as domestic production will not be sufficient to meet demand, our country will become the world’s largest importer of natural gas in 2019, with most of that gas being liquefied natural gas. Against this backdrop, projects to convert coke oven gas into natural gas have gradually emerged in China. Indeed, the current development of converting coke oven gas into natural gas is highly timely. At the **level, the growth rate of China’s natural gas production (including unconventional natural gas) is far from sufficient to meet the demand for natural gas consumption. In 2017, China’s natural gas imports reached 92 billion cubic meters, with a foreign dependence rate of nearly 39%. Under these circumstances, as long as the price is acceptable to the market, the production of natural gas from coke oven gas will develop steadily. At the same time, it can at least reduce the dependence on natural gas by 1–2 percentage points. For coking enterprises, converting coke oven gas into natural gas is undoubtedly a way to break through the pressures of environmental protection and survival. In the past, coking plants would vent and burn coke oven gas, which not only wasted energy but also caused severe air pollution. Recycling it to produce natural gas is not only an environmentally friendly measure but also yields significant economic benefits; moreover, it provides clean energy for society, making it a win-win approach. In terms of economic benefits, the price of coke oven gas itself is generally only around 0.5 yuan per cubic meter; after purification, methanation, and liquefaction, the cost rises to about 2 to 2.5 yuan per cubic meter. In the central and eastern regions of our country, where the prices at natural gas distribution stations are high, the cost of using pipeline natural gas is much higher than these prices. This means that producing natural gas from coke oven gas holds a significant competitive advantage in these regions. It is reported that the return on investment for producing natural gas from coke oven gas is about 28% higher than that for producing methanol from coke oven gas. Not only that. The methane content in natural gas produced from coke oven gas can exceed 99%, which is significantly better than that of conventional pipeline natural gas. In fact, our country does indeed possess the advantages to vigorously develop the production of natural gas from coke oven gas. Firstly, our country is the world’s largest producer of coke and coke oven gas. China has a wide distribution of coke production areas; except for Tibet and Hainan, coke is produced in all other provinces, with an annual output of over 1.5 million tons each. Provinces such as Shanxi, Hebei, Shaanxi, Shandong, and Inner Mongolia have an annual output of over 30 million tons. There are over 600 coke production enterprises in our country, with more than 200 of them having an annual production capacity of over 1 million tons. These enterprises are spread across 28 provinces, municipalities, and autonomous regions across the country. This is incomparable to gas sources such as shale gas (mainly in Sichuan and Chongqing), coalbed methane (mainly in Shanxi), and gas produced from coal (mainly in Xinjiang and Inner Mongolia). In 2016, China’s coke production was approximately 480 million tons, accounting for about 67.44% of the world’s total coke production. After the capacity reduction in 2017, coke production amounted to 431.426 million tons, remaining the highest in the world. For every ton of coke produced, approximately 430 cubic meters of coke oven gas are generated; half of this is used to fuel the furnace again, while the other half can be used to produce natural gas. Secondly, breakthroughs have been achieved in China’s technology for converting coke oven gas into natural gas. At present, there are mainly two process technologies in China for producing natural gas from coke oven gas: the methanation process, represented by the \"Methanation of coke oven gas to produce natural gas\" method developed by Southwest Chemical Engineering Research and Design Institute Co., Ltd., and the separation process, represented by the \"Combined purification and separation of coke oven gas to produce natural gas\" method developed by the Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Among them, the methanation process can be further divided into two types: carbon-free methanation process and carbon-supplemented methanation process. Since the volume fraction of methane in coke oven gas is only 23%–27%, using a methanation process without carbon supplementation results in an excess of hydrogen, preventing full and efficient utilization of the raw materials. The carbon supplementation methanization process makes full use of the various effective components in coke oven gas by adding carbon to the feed gas, thereby methaneating the entire feed gas. This approach can increase natural gas production by about 30%, and it facilitates subsequent gas separation and cryogenic liquefaction; it is thus an ideal method for converting coke oven gas into natural gas. Third, the production of natural gas from coke oven gas in our country has already taken initial shape. Our country has been using coke oven gas to produce natural gas since 2012. The first enterprise responsible for this project is Inner Mongolia Hengkun Chemical Co., Ltd., affiliated with Xinwen Mining Group, with a daily production capacity of 360,000 cubic meters. By 2016, China had nearly 30 plants for converting coke oven gas into natural gas, with a daily production capacity of 12.6 million cubic meters. In the same year, there were 172 natural gas plants in China, with a daily production capacity of 96.96 million cubic meters. In other words, the production capacity of natural gas from coke oven gas already accounts for 13% of the total natural gas production capacity. Apart from conventional natural gas, coke oven gas has become the second largest source of natural gas for plants in China. Nevertheless, for the production of natural gas from coke oven gas to continue developing, it still needs favorable policy support. As is well known, the utilization of shale gas and coalbed methane was already included in the 13th Five-Year Development Plan. Yet, despite statistics from the China Coking Industry Association showing that the total production capacity for converting coker gas into natural gas reached 3.6 billion cubic meters per year by 2015, with estimates suggesting it is now at 5 billion cubic meters per year, this sector still hasn’t caught the attention of the planning and statistical authorities. Furthermore, **the government provides subsidies for both shale gas and coalbed methane extraction, but there is no funding at all for the use of coke oven gas. Although it has not yet received sufficient attention in China, as an environmental protection project that involves the recycling of by-products, natural gas production from coke oven gas is a clean energy source with great market potential, especially given the continuous rise in domestic natural gas prices.