Recently, Guangdong Zhongshan, Shandong Qixia and other places have issued a timetable to dismantle, shut down or renovate high-energy coal-fired boilers. Previously, the "Announcement on the Implementation of Special Emission Limits for Air Pollutants" issued by the Ministry of Environmental Protection also showed that China's environmental improvement will be from the end of governance to the source control. Relevant persons of the Industrial Boiler Branch of China Electrical Equipment Industry Association said that industrial boilers have great potential in both energy conservation and emission reduction.

Inefficient, energy saving potential

Hou Yuxuan, a researcher in the environmental protection industry of China Investment Consulting, said that China's industrial boilers have a large volume and a small average capacity, and they are mainly coal-fired. Although the design efficiency of China's coal-fired industrial boilers is not much different from that of foreign countries, the actual operating efficiency is only about 65%, which is 10% to 15% lower than the foreign advanced level. A coal-fired boiler has achieved the maximum energy-saving and emission-reducing effect through condensate recovery, increased furnace air temperature and stratified combustion of the installed coal hopper. The production cost is reduced by more than 2 million yuan in one year.

The reasons for the low operating efficiency of coal-fired industrial boilers in China are complicated. To sum up, there are mainly several aspects: First, the reasons for design and manufacture, the design part pays more attention to the part of the pressure component, and the part of the combustion device is not as important as the pressure component. The second is the reason for the use of the pot. The boiler user does not match the actual capacity used when selecting the boiler. Third, the coal type used does not match the design coal type of the boiler. The coal quality index such as the calorific value, volatile matter or particle size of the coal used does not meet the boiler design coal requirements. Fourth, the relevant system and regulations for industrial boiler energy conservation supervision are not perfect, and the technical standards are relatively lagging behind.

The data shows that China's current coal-fired industrial boilers exceed 470,000 units, which is the second largest coal-fired user in China. It consumes more than 400 million tons of standard coal per year, accounting for about a quarter of China's total coal consumption. At the same time, due to the low efficiency of boiler operation, energy waste is quite serious, and the annual consumption of coal is about 60 million tons, which has great energy saving potential. In addition, industrial boilers emit a large amount of soot and SO2 and NOX pollutants, which has become one of the major soot pollution sources in China. Therefore, energy-saving renovation of industrial boilers, especially coal-fired industrial boilers, is of great significance for achieving the overall goal of energy conservation and emission reduction in China.

It is understood that as early as 2004, the National Development and Reform Commission has listed the reform of the coal-fired industrial boiler kiln as the first of the ten major energy-saving projects in the “Eleventh Five-Year Plan” and formulated the project. Demonstration embodiment. In the “Twelfth Five-Year Plan for Industrial Energy Conservation” formulated by the Ministry of Industry and Information Technology, the industrial boiler kiln energy-saving renovation project is also listed as the first among the nine key energy-saving projects.

Adopt clean coal technology to become mainstream

The energy-saving transformation of industrial boilers can be made in two aspects: First, technological transformation. In the future, some old-style coal-fired boilers with low efficiency and serious environmental pollution will be eliminated, and the existing coal-fired boilers will be technically modified according to local conditions. Coal-to-gas is used in resource-rich areas such as natural gas, and solar collectors are used to replace small coal-fired boilers in areas with poor gas resources. The second is to use clean combustion technology. Replace clean coal with clean coal to improve coal quality.

There are many mature technologies in the domestic energy-saving renovation of industrial boilers. Pulverized coal combustion is an advanced coal-burning technology. It has the advantages of fast burning speed, high burning rate and low heat loss of flue gas. It can be widely used in industrial boilers. The pulverized coal particles are uniform and suspended in the air. Compared with the layered combustion, the combustion air ratio is low, the burnout rate is high, and the flue gas discharge heat loss is small; the pulverized coal industrial boiler adopts full-closed powder feeding, air supply and The ash discharge technology has good thermal insulation performance, which greatly reduces the heat loss caused by hot air and flue gas leakage, and is beneficial to improve the thermal efficiency of the boiler.

Guo Fanli, research director of CIC Consulting, said that compared with traditional coal-fired boilers, the energy-saving rate of new energy-saving and environment-friendly pulverized coal industrial boilers reached more than 30%, and the concentrations of pollutants such as soot, sulfur dioxide and nitrogen oxides were lower than national standards. And the operation is simple, the boiler operation, coal transportation, combustion, desulfurization and dust removal, slag discharge, etc. realize full automatic control, coal and slag do not fall to the ground, and there is no need to stack the site.

It is understood that industrial boilers can be developed in the future in the direction of fuel gas boilers, coal water slurry boilers and biomass fuel boilers. However, for a long period of time in the future, coal-fired industrial boilers will still be the leading products in China. With the changes in energy supply structure and increasingly strict requirements for energy conservation and environmental protection, efficient, energy-saving and low-polluting technologies using clean fuels and clean combustion technologies are adopted. Industrial boilers will be the trend of product development. Domestically, it is still necessary to vigorously develop integrated technologies for efficient combustion of industrial boilers, flue gas dedusting and desulfurization, and at the same time develop high-quality coal-fired technology and large-scale coal washing technology to improve the quality of thermal coal and solve the problem of boiler combustion and pollution in the whole process.