Petrochemical industry is the basic industry and pillar industry of the national economy, and its development speed and scale have a direct impact on all aspects of the social economy. The chemical industry is characterized by a wide range of categories, complex processes, diverse products, and many kinds, large quantities and high toxicity of pollutants dis- charged in production.

Chemical industry plays an important role in the national ec- onomy of many countries, and is the basic industry and pillar industry of many countries. The development speed and scale of the chemical industry have a direct impact on all sectors of the social economy. The annual output value of the world's chemical products has exceeded 150 billion dollars.

The power station industry is a factory that converts all kinds of primary energy contained in nature into electric energy (secondary energy). At the end of the 19th century, with the growth of power demand, people began to propose the idea of establishing power production centers.

The pharmaceutical industry is an important part of China's national economy. It is a combination of traditional industries and modern industries, with the primary, secondary and ter- tiary industries as a whole. Its main categories include: che- mical raw materials and preparations, Chinese medicinal mat- erials, Chinese herbal pieces, Chinese patent medicines, a ntibiotics, and biological products.

Metallurgical industry refers to the industrial sector that mines, selects and sinters metal ores, smelts them and processes them into metal materials.

Natural gas is stored in underground porous rock formations, including oilfield gas, gas field gas, coalbed gas, mud volcanic gas and biogenic gas, and a small amount is also produced from coal seams. It is a high-quality fuel and chemical raw material.