Shulou(Shulou.com)11/24 Report--

On August 10, 2022, the methanation catalyst jointly developed by CNOOC CNOOC Group Co., Ltd. (hereinafter referred to as Gas and Power Group) and Southwest Chemical Research and Design Institute Co., Ltd. (hereinafter referred to as Southwest Institute), for the first time in Xinjiang Qinghua large-scale coal-to-natural gas project, achieved 110% stable operation at full load, and the methane concentration obtained was 61.7%, which was nearly 3 percentage points higher than that of imported technology. This marks a major breakthrough in the methanation technology of large-scale coal-to-natural gas independently developed in China (see China Energy News).

Qinghua, Xinjiang (Source: Sohu) this is a very important event to celebrate in the field of energy security in China. It means that China has reached the international leading level and successfully achieved the leading position in terms of coal-to-natural gas catalysts. Do you think that's all? No, let's look back to March this year, Southwest Chemical Research and Design Institute Co., Ltd. (referred to as "Southwest Institute") signed a 1.5 billion cubic meter / year coal-to-natural gas project CNGC-2 gas regulator and CNJ-8 methanation catalyst supply contract with Qinghua Energy Group Co., Ltd. The successful signing of the contract marks the first time that the catalyst, the core part of the coal-to-natural gas project, has been fully nationalized. In a short period of less than half a year, China has made a great breakthrough in the field of coal-to-natural gas catalyst.

Researchers analyze catalyst samples (source: Sina Finance) it is well known that China is rich in fossil energy resources and has the characteristics of "lack of oil, less gas and rich coal" in energy reserves, which makes the energy consumption structure of our country relatively fixed. In addition to Shanghai, coal resources are distributed in most provinces in China, among which Inner Mongolia, Shaanxi and Shanxi are important coal-producing areas. However, although China is a big coal country, there is a high proportion of low-quality coal with "high sulfur, high ash and high melting point" in its coal reserves, accounting for 1/3 of the total reserves in Shanxi Province alone. These inferior coals have been difficult to be used cleanly for a long time, so how to achieve their efficient and clean use has become the goal of energy people.

On the other hand, there is a great demand for natural gas in our country. In 2021, China's natural gas consumption was 372.6 billion cubic meters, but its output was only 205.2 billion cubic meters, resulting in an energy shortfall of 167.4 billion cubic meters. According to the forecast of the National Energy Administration, China's natural gas supply and demand will still face a large gap in the short and medium term. It is obvious that if inferior coal can be converted into natural gas on a large scale, it will not only help to narrow the energy gap and produce huge economic benefits, but more importantly, it can provide greater help for environmental protection.

At present, the ways to convert coal into energy products are coal power generation, coal-to-oil, coal-to-methanol and dimethyl ether, coal-to-natural gas and so on. Among these ways of utilization, the coal-to-natural gas has the highest energy conversion efficiency.

Coal mining in open-pit coalfields (source: Zhihu @ scientific knowledge) so how is coal-made natural gas produced? Mainly through the following steps:

① raw coal reacts with oxygen and steam from the air separation unit in the gasifier to obtain crude synthetic gas. The main components of crude synthetic gas are hydrogen, carbon monoxide, carbon dioxide, methane, hydrogen sulfide, oil and advanced hydrocarbons.

After rapid cooling and washing, the ② crude synthetic gas is sent to the conversion unit, and after partial transformation and process waste heat recovery, it enters the acid gas removal unit to remove hydrogen sulfide, carbon dioxide and other impurities.

The ③ then feeds the gas into the methanation unit. Qualified natural gas products are obtained in the methanation unit, then compressed and dried and sent into the natural gas pipeline network.

④ will also produce sulfur, crude phenol and other by-products in this process.

Simple flow chart of coal-to-natural gas (Ma Lili et al. 2019) ↑↑↑ in short, coal-to-natural gas is obtained by methanation with inferior coal as raw material and through gasification, transformation, purification and other processes to make syngas reach the hydrogen-carbon ratio of synthetic methane. As shown in the flow chart, the methanation process is not only the end of the process, but also the most critical and important part. If methanation is done well, more natural gas will be converted and its commercial value will be high. Therefore, the catalyst needed for methanation has become a top priority-as long as the catalyst is good, gas is indispensable!

In recent years, China has been committed to the localization of the whole technology chain of coal-to-natural gas production, and has achieved localization in coal gasification, transformation, deacidification and other technology. however, the development of methanation technology is difficult and no breakthrough has been made for many years. By 2019, four commercial coal-to-natural gas projects have been put into operation (Qinghua Project in this article is one of them), but their methanation processes are all using foreign technology, for which China has paid huge technology transfer fees. In 2010, the Southwest Hospital began to establish a project for coal-to-natural gas project, and it is only in 2022 that coal-to-natural gas will be fully localized, and the hardships can be imagined. The emergence of domestic methanation technology will promote commercial coal-to-natural gas projects in the future.

Although China has made great progress in coal-to-natural gas technology, there are still some problems to be solved urgently. For example, in terms of energy consumption, carbon dioxide emissions in coal-to-natural gas production are still very high, and the demand for water is also very high, while most of the coal-producing areas in China are lack of water. These contradictions limit the development of coal-to-natural gas industry, especially in the context of double carbon, the problem becomes more acute. How to go further on the road of localization technology, how to solve the problems exposed in production, and how to apply the existing achievements of the laboratory to industrial production? this is a new journey that coal-to-natural gas engineers will face and embark on.

This article is from the official account of Wechat: stone popular Science Studio (ID:Dr__Stone), author: Xingyu

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