Industrial boilers have low energy-saving potential

Recently, Zhongshan, Guangdong and Qixia, Shandong have all issued timetables to dismantle, shut down, or reform coal-fired boilers with high energy consumption. 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 move from end-to-end governance to source control. According to relevant figures from the Industrial Boiler Branch of China National Electrical Equipment Industry Association, industrial boilers have great potential for energy conservation and emission reduction.

Poor energy efficiency with low potential

Hou Yuxuan, a researcher in the environmental protection industry of China Investment Advisors Co., Ltd., stated that China's industrial boilers have a wide range of products with small average capacity, and are mainly coal-fired. Although the design efficiency of coal-fired industrial boilers in China 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 advanced level in foreign countries. A coal-fired boiler through the condensate recovery, increase the air temperature in the furnace and install coal slag layered combustion and other technical transformation, to achieve the maximum degree of energy-saving emission reduction effect, one year down to save production costs about 200 million.
The reasons for the low operating efficiency of China's coal-fired industrial boilers are relatively complex. To sum up, there are several main aspects: First, the design and manufacturing reasons, in the design of more emphasis on the part of the pressure element, and the part of the combustion device is less important than the part of the pressure component. The second reason is the use of boilers. When the boiler user selects the boiler, the selected capacity does not match the actual capacity used. Third, the type of coal used for combustion is inconsistent with the type of coal used in the design of the boiler, and coal quality indicators such as the calorific value, volatile matter, or granularity of the coal being used do not meet the boiler design coal requirements. Fourth, the relevant laws and regulations concerning industrial boiler energy conservation supervision are not perfect, and the technical standards are lagging behind.

According to the data, China's current coal-fired industrial boilers exceed 470,000 units, making it 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 inefficient operation of boilers, energy waste is very serious, and coal consumption is estimated to be about 60 million tons per year, which has great potential for energy conservation. In addition, due to the large amount of smoke, SO2, NOx and other pollutants emitted by industrial boilers, it has become one of the major coal-burning pollution sources in China's atmosphere. Therefore, the energy-saving transformation of industrial boilers, especially coal-fired industrial boilers, is of great significance for achieving the overall goal of energy-saving and emission reduction in China.

It is understood that as early as 2004, the National Development and Reform Commission has listed coal-fired industrial boiler kiln reform as the first of the ten key energy-saving projects in the “11th Five-Year Plan” and formulated the project in the “Energy Conservation Medium and Long Term Special Plan”. Exemplary implementation. 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 among the top nine key energy-saving projects.

The use of clean coal energy-saving technology into the mainstream of industrial boilers can <br> <br> force from two aspects: First, for technological transformation. In the future, some old coal-fired boilers with low efficiency and serious environmental pollution will be eliminated and the existing coal-fired boilers will be technologically modified according to local conditions. In areas rich in natural gas and other resources, coal is converted to gas. In areas with limited gas resources, solar collectors are used instead of small coal-fired boilers. The second is the use of clean combustion technology. Use clean coal instead of raw coal to improve coal quality.

Domestically, there are many mature technologies for energy-saving transformation of industrial boilers. Pulverized coal combustion is an advanced coal-fired technology. It has the advantages of high combustion speed, high burnout rate, and low smoke heat loss, and can be widely used in industrial boilers. The pulverized coal particles are even and suspended and burned in the air. Compared with the laminar combustion, the combustion air ratio is low, the burnout rate is high, and the heat loss of the smoke emission is small; the pulverized coal industrial boiler adopts completely closed powder feeding and air supply. Ash removal technology, good insulation performance, greatly reducing the heat loss due to hot air and flue gas leakage, is conducive to improving the thermal efficiency of the boiler.

Guo Fanli, research director of China Investment Consulting, said that compared with traditional coal-fired boilers, the energy-saving rate of new energy-saving and environment-friendly pulverized coal industrial boilers has reached more than 30%, and the concentrations of pollutants such as smoke, sulfur dioxide, and nitrogen oxides are all lower than the national standards. , And the operation is simple, the boiler operation, coal transportation, combustion, desulphurization dust, slag, etc. to achieve a fully automated control, coal and slag do not fall, do not need to pile up sites.

It is understood that industrial boilers can be developed in the future in the direction of oil-fired gas boilers, coal-water slurry boilers, and biomass-fired boilers. However, for a long time to come, coal-fired industrial boilers will still be the leading products in China. With the changes in energy supply structure and the increasingly stringent requirements for energy conservation and environmental protection, the use of clean fuels and clean combustion technology will be highly efficient, energy-saving, and low-pollution. Industrial boilers will be the trend of product development. Domestic still needs to vigorously develop the integrated technology of high-efficiency combustion of industrial boilers, flue gas dust removal and desulfurization, and at the same time develop high-quality steam coal technology and large-scale coal washing technology, improve the quality of thermal coal, and solve the problem of boiler combustion and pollution in the whole process.