1. technical name

Intelligent monitoring and control technology for boiler combustion

2. scope of application

Online monitoring and fine control of balanced distribution of primary air and powder in coal-fired boilers of various capacity in thermal power plants are especially suitable for complex coal quality and varying operating loads.

3. technical content

.1 Technical principles

This technology uses advanced electrostatic induction technology to accurately monitor the flow parameters of primary air and powder in the boiler (pulverized coal flow rate, concentration and flow distribution, etc.). It realizes online fine control of uniform distribution of air and powder through a new air and powder adjustment technology, and ultimately fine adjustment of pulverized coal production and optimization of combustion air distribution. This technology can improve boiler combustion conditions, reduce the total air volume and primary air volume, thereby reducing smoke exhaust losses and reducing auxiliary power consumption; after the combustion is uniform, the combustion deterioration area in the furnace can be eliminated, thereby reducing the carbon content of fly ash and reducing The CO produced by combustion achieves efficient and low-NOx combustion.

3.2 main innovations

(1) The electrostatic sensor adopts an annular design with the same inner diameter as the primary air duct, which has no disturbance to the flow of air and powder. No measuring elements extend into the inside of the pipe. There is no wear and a very long service life. The multi-array electrode design and a variety of data processing algorithms are effectively combined to achieve high measurement accuracy and stability; only by sensing the electrostatic charge carried by the coal dust itself, no electrical signal or energy is injected into the pipe, passive measurement is safe and reliable.

(2) The new air and powder balance adjustment device, based on accurate and reliable online monitoring data of air and powder, can perform online and fine control of the imbalance of air and powder distribution, completely changing the traditional method that can only rely on manual test measurement and then offline manual adjustment. The backward method of adjusting shrinkage cavity has the advantages of no jamming, no powder accumulation, no additional resistance in the pipeline, good adjustment linearity, and flexible adjustment with electric actuators. It is an effective means to finely control the distribution of air and powder in the pulverizing system.

(3) Based on the accurate measurement data of pulverized coal flow rate and concentration, by automatically calculating and counting the wind and powder flow deviation at the outlet of the boiler burner, the system can automatically and intelligently adjust the wind and powder deviation to achieve balance and output power distribution in the burner under various operating conditions.

4. Energy conservation and greenhouse gas emission reduction effects

After accurate monitoring of boiler pulverized air and fine optimization of combustion, the boiler thermal efficiency can be increased by about 0.5%~ 1.0%, coal consumption can be reduced by at least 1.5gce/kW·h, NOx emission can be reduced by 10%, and the cost of denitration catalyst can be saved. From the perspective of social benefits, according to the annual thermal power generation capacity of 492.49 billion kW·h in 2018, 1.5g standard coal can be saved per kilowatt hour, which can save 7.37 million tons of coal, reduce CO2 emission by 19.18 million tons, and reduce nitrogen oxide emission by about 10%. It has important social value in efficient and clean utilization of coal resources, reduction of greenhouse gases and reduction of environmental protection costs.

5. Technology demonstration

At present, it has been used on about 50 units across the country, including 25 600MW units and 10 1000MW units.

This technology was successfully applied on the No. 1 1000MW unit of State Power Investment Corporation Pingdingshan Power Generation Branch in 2015. It is also a complete application case for online monitoring, leveling and optimization of pulverized coal on the first million-unit (opposed combustion) in China. The project has achieved good energy conservation and emission reduction effects. The balance of air and powder, combustion deterioration and CO emissions have been significantly improved. The boiler efficiency has been increased by 0.9%, and coal consumption has been reduced by 2.81 gce/kW·h.

In 2017, at the Jianbi Power Plant of National Energy Group 13#It has been successfully applied to the unit (tangential combustion at four corners), and the implementation has achieved significant energy conservation and emission reduction effects. The heat load is more uniform, local wall temperature overtemperatures are effectively improved, furnace efficiency is increased by 0.37%, and NOx is reduced by more than 10%.

In 2022, it will be applied in the fine combustion state control project of boiler burners under deep peak shaving of National Energy Group Shenhua Jiujiang Power Plant. For the first time, the engineering application and practice of the fine combustion state control technology of the combustor was realized under the 30% deep adjustment condition of a 1000MW ultra-supercritical opposition-fired boiler. It was verified that this technology can improve the stability of the boiler under long-term low-load operation conditions. Combustion performance and solve problems such as excessive temperature of the heated wall, large wall temperature deviation, large amount of desuperheating water consumption, large deviation of desuperheating water on both sides, and increased NOx emissions.

6. investment estimation

Intelligent monitoring and control technology for boiler combustion includes online monitoring technology for pulverized coal flow rate and concentration, air and powder balance adjustment device, and automatic balance control system. Taking a 600MW coal-fired unit as an example, the hardware investment of the pulverized coal flow rate and concentration monitoring system is 2.8 million yuan (including implementation), the hardware investment of the air-powder balance adjustment device is 2.3 million yuan (including implementation), and the balance control system (combustion optimization software) is 1.2 million yuan (including implementation), and the system is invested at a time of about 6.3 million yuan; Based on the analysis of 4000 utilization hours per year and the annual power generation of 2.4 billion kWh, the converted cost is 10.5 yuan per kilowatt.

After the system is put into operation, there is almost no need for manual maintenance every day. Only a small amount of spare parts is needed, ranging from several thousand to tens of thousands of yuan. The service life of the equipment is about 10 years.

7. investment recovery period

Taking a 600MW coal-fired unit as an example, based on the analysis of annual utilization of 4000 hours and annual power generation of 2.4 billion kWh, intelligent combustion monitoring and control technology can achieve optimal combustion operation control after blended combustion, saving power generation coal consumption by 1.5 gce/kWh of electricity compared with the original extensive method, saving 3600 tons of coal annually; reducing NOx emissions and reducing environmental protection costs by about 1.28 million yuan annually; reducing plant power consumption by about 10%, saving 800,000 yuan annually; Comprehensively reduce operating costs by 4.24 million yuan/year, and the investment recovery period is within 2 years.

8. Prospects for transformation and promotion of technological achievements

This technology adopts array electrostatic induction pulverized coal flow rate concentration technology, new pulverized coal equalization and leveling device and advanced fine optimization control technology, which can provide all-round pulverized coal intelligent combustion monitoring, equalization control and fine combustion control solutions. At home and abroad, the same industry is in a leading position. Efficient and clean utilization of coal has become one of the important national strategies. There are about 2000 coal-fired power units with an installed capacity of more than 300MW in my country. The proportion of units that have implemented refined intelligent combustion monitoring, control and optimization technology does not exceed 3%, so this technology has a large domestic market capacity and application prospects