Development Status and Prospects of Circulating Fluidized Bed Boilers

First, the development of circulating fluidized bed boiler technology

In 1960, China began to use fluidized bed boiler technology. After more than 50 years of development, the technology of fluidized bed boilers in China has been increasingly advanced and developed.

The development of China's fluidized bed boiler technology has gone through three processes: reforming old boilers, developing new boilers, and designing and manufacturing circulating fluidized bed boilers.

The first period: During the period when the fluidized bed boiler was first applied, due to lack of funds, the quality of the selected fuel was not high. During this period, the focus was to transform the chain boiler and block boiler used in a part of the plant to form a bubbling fluidized bed boiler. . In practical production, there are many bubbling fluidized bed boilers. The most obvious deficiency is that the efficiency of coal combustion is very low. In the process of combustion, fly ash with excessive carbon content is formed, which seriously harms the ecological environment.

In the second period, based on the bubbling fluidized bed and improved to increase the thermal efficiency of the bubbling fluidized bed by 30%, a new type of boiler, a lignite fluidized bed boiler, was developed. The boiler improved its thermal efficiency to at least 80%. .

The third period: design and manufacture of innovative circulating fluidized bed boilers, and the joint application of two boilers in the first and second periods. As a result, the carbon content in the fly ash is greatly reduced, and the effect of purifying the air has been achieved to a certain extent. After continuous optimization by relevant scientific and technological workers, circulating fluidized bed boilers are widely used in boiler plants.

Second, the development prospects of circulating fluidized bed boiler technology

(1) The development prospect of supercritical and large-scale

Circulating fluidized bed supercritical has its own special combustion characteristics, which can determine its own direction of development. The heat flow of pulverized coal in a circulating fluidized bed boiler is generally lower than that of a circulating fluidized bed boiler. Therefore, the required water wall is relatively high. In the application of a circulating fluidized bed boiler, the solid heat transfer coefficient formed is inversely proportional to the temperature of the boiler. In addition, there is an inverse relationship between solid concentration and solid heat transfer coefficient. In other words, the lower the boiler temperature, the higher the solid heat transfer coefficient. This connection can effectively control and regulate the temperature of the water wall, ensure that the circulating fluidized bed boiler has the ideal application effect, and can promote the development of supercritical large-scale circulating fluidized bed boiler technology.

In general, the advantages of a supercritical boiler are less coal loss, higher operating efficiency, and less pollutant emissions. For a circulating fluidized bed boiler technology that uses a first-class fly ash separation and circulating combustion technology, the boiler system is very simple and facilitates the implementation of large-scale production technologies. In addition, both the water-cooled separator and the lower-row cyclone developed in China, as well as the foreign-developed square separator, can be integrated with the boiler body, so that a large-scale model can be realized.

(2) Development prospects of anti-wear technology upgrade

In boilers operating at high temperatures, high-temperature solid materials are operated at high speeds. Therefore, thermal shocks can severely abrade the bearing surfaces in the furnace. Therefore, the exploration of the anti-wear technology of the boiler is beneficial to the extension of the service life of the equipment. At present, the application of high-performance refractory materials is the most effective anti-wear measures, the use of high-performance refractory materials can ensure the extension of the metal application life and the safety of fluidized bed operation.

(3) Development prospects of deep desulfurization

Circulating fluidized-bed boilers are characterized by low-temperature combustion and fractional feed air combustion, and thus contribute to the formation of oxygen-nitrogen compounds. Compared to boilers of the same period, the oxygen-nitrogen content can be reduced by 20%, and the concentration of nitric oxide can be controlled at 300 milligrams. Below the cubic meter, under the influence of China's emission improvement targets, the development direction of the CFB boiler technology is the deep denitrification of the boiler. Among the pollutants released by China's thermal power plants, the target for reducing sulfur dioxide emissions is 400 mg/m3. Compared with traditional wet desulfurization, adding limestone to a circulating fluidized bed can achieve an ideal desulfurization effect. However, it is required to treat ash. For this reason, an important development prospect of circulating fluidized bed boilers is the deep desulfurization of CFB boilers.

(4) Prospects for the development of comprehensive energy applications

The problem of shortage of energy is worldwide. Therefore, the comprehensive application of energy is a development prospect of the circulating fluidized bed boiler technology. Comprehensive application of energy covers a very wide range, for example, the use of circulating fluidized bed boiler technology to optimize the application of a part of low-level energy; processing and integration of other energy, raw materials and circulating fluidized bed boilers, so as to effectively apply energy; comprehensive application The ash formed by the combustion of circulating fluidized bed boilers. In view of the current situation, the comprehensive application of the ash formed by the combustion of a circulating fluidized bed boiler is a difficulty in development. This is because the addition of limestone to the boiler to achieve desulfurization can achieve an ideal shedding effect, but it will increase the amount of ash. Exploring a suitable way to deal with desulphurization ash slag in circulating fluidized bed boilers is a key issue in the technical analysis of circulating fluidized bed boilers at home and abroad, and it is also a development prospect of circulating fluidized bed boiler technology.

In short, if we want to further develop the circulating fluidized bed boiler technology, we must constantly optimize and improve the circulating fluidized bed boiler technology. At present, circulating fluidized bed boiler technology has very large application advantages, and it is believed that it will have a very promising development prospect in the future market.