Coal water slurry technology includes pulping technology, conveying technology and fuel technology. Coal water slurry (CWS) is a new clean fuel to replace petroleum. It is made of coal, water and additives (including dispersant, defoamer and stabilizer) through physical processing in a certain proportion. Coal water slurry has good fluidity and is convenient for loading, storage, pipeline transportation and spray combustion. Compared with pulverized coal combustion, it produces less nitrogen oxides, SO2 and ash, and can replace oil or gas for industrial boilers, utility boilers and industrial kilns, achieving good economic and environmental benefits. Ultra-low ash coal water slurry can also be directly used in diesel engines and gas turbines.
The international coal water slurry technology has entered the stage of large-scale industrialization and commercial application. The United States, Sweden, Italy, Japan, Canada and other countries believe that the application of coal water slurry technology is mature, and once it can compete with oil prices, it can be put into industrial production. Since 1980s, these countries have shifted their research focus to the preparation and application of ultra-low ash coal water slurry.
China began to study coal-water slurry instead of oil in 1980s, and Huamei Coal-water Slurry Technology Joint Center undertook the national key project of "Burning Coal-water Slurry for Industrial Boilers and Power Plant Boilers in the Seventh Five-Year Plan". Two 50,000-ton/year experimental pulp mills, Zaozhuang Bayi Mine and Fushun Shengli Mine, were built first. The coal-water slurry plant of Beijing Mining Bureau was completed and put into operation in March 1992, which is the first demonstration plant of coal-water slurry in China. The production line and main technical equipment are imported from Sweden, with an annual output of 250,000 tons of coal water slurry. At the same time, a washing workshop with an annual processing capacity of 300,000 tons of raw coal is built in China, and Datong coal is used as pulping raw material. The completion of this plant indicates that China's coal water slurry production has entered the advanced ranks in the world. Subsequently, China and Japan established a 250,000 t/a Yanzhou coal water slurry plant with an investment of 400 million yuan.
The concentration of coal water slurry produced in China is generally 65%~70%, the viscosity is 500~ 1500 centipoise, and the combustion efficiency is above 95%. It has been used instead of oil or gas in industrial boilers, power station boilers, cement and drying kilns, and large forging furnace, which shows that the combustion performance is stable and the comprehensive combustion efficiency is equivalent to that of coal-fired pulverized coal boilers.
With the in-depth development of coal-water slurry technology, replacing oil with coal is an important decision in line with the characteristics of China's energy structure, and the prospect is very bright.