Why don't people turn coal into gas through processing, and then use it for combustion, heating or power generation?

The secondary conversion of coal has one of the biggest disadvantages: the waste of water resources and the consumption of energy in the conversion process. Coal chemical industry in China is mainly distributed in water-deficient areas. This has caused irreversible damage to the environment.

Coal for electricity, so-called power coal. This part is directly burned; Coal is used in building materials industry, and it is also a kiln for heating cement, glass and ceramics. Coking coal is used as reducing agent in iron and steel industry, but it is not directly burned, while anthracite is mainly used as raw material in chemical industry. Nitrogen fertilizer and coal tar are prepared by distillation and gasification of dry pulverized coal or coal water slurry.

Among them, the two major industries that directly burn coal, together with other demands, account for about 75% of the total coal consumption. The short-term goal of the National Energy Administration is to reduce the proportion of coal consumption in China's primary energy consumption from about 65% to below 60%. (The proportion of India and South Africa is about 70%, and that of the United States is about 22%).

Not all coal burning is uneconomical; There is a problem of cost accounting. If the comprehensive economic efficiency of direct coal combustion is higher than the efficiency of coal conversion into other thermal energy products, then society will tend to direct coal combustion. The so-called waste of coal direct combustion refers to the possible benefits that coal itself can be used as the basic raw material of other industrial products, which exceeds the value brought by combustion.

The deep processing of coal, on the one hand, is used to prepare various carbon materials and reducing agents (coking); On the other hand, it is to remove harmful substances and extract various other chemical components, such as benzene, phenol, methanol and ethylene glycol in coal. The utilization direction of thermal energy fuel includes coal to natural gas, direct liquefaction of coal, indirect liquefaction and so on.

But all these processes have an economic benefit constraint. For example, coal chemical industry needs a lot of water resources, and some categories even reach the ratio of 1: 10. Therefore, at present, domestic authorities are very cautious when approving coal chemical projects.