(1) Technical scope of application

Boiler recycling technology is widely used in industrial production with heating furnaces.

(2) Technical principles (transformation content)

① Introduction to boiler steam recovery technology

The steam condensate recovery device consists of a special pump for high-temperature condensate recovery, a motor, a recovery storage tank, a siphon forced pumping device, a cavitation elimination device, a steam-driven three-way valve, a liquid level sensor, a magnetic flap liquid level meter, a mirror, an oxygen removal device, a pressure gauge, a filter, a pressure regulating valve, a blowdown valve, a power control box, etc. The entire system is fully automatic. When the power is turned on, the equipment enters running state. The liquid level sensor detects that the liquid level in the tank is low, and the liquid level sensor sends a low liquid level signal to the electric box controller. The electric box controller turns on the condensate recovery pump and closes the pneumatic three-way valve. The siphon force pumping device starts to run. After siphoned the steam condensate from the heat using equipment through the steam trap to the steam and water separation tank, it enters the main tank after being separated from the steam and water in the tank. When the liquid level in the main tank reaches the high liquid level setting value, the pneumatic three-way valve opens. The high-temperature condensate recovery pump conveys high-temperature condensate and a small amount of secondary steam to the steam boiler through the pre-pump cavitation elimination device and filter. When the liquid level reaches the low liquid level setting value, the pneumatic three-way valve is closed, and the entire steam condensate recovery process is complete. Adjust the time relay in the electric box according to the working conditions of the gas equipment to set the siphon force pumping time. There is no water in the gas equipment during the entire steam condensate recovery process.

② Energy saving principles

Condensate water is softened and desalinated, is very pure and contains a large amount of heat, generally accounting for about 20-30% of the total heat of steam, and up to 40% for some equipment. Therefore, if high-temperature condensed water can be recycled as boiler makeup water, it will not only save industrial water, but also save a large amount of fuel. In this way, the boiler can save 20-40% of fuel, water and water treatment drugs when producing the same amount of steam.

(3) Application cases

(1) A brief explanation of the basic situation: The sintering waste heat boiler has never been equipped with waste heat generating units. All the steam from the waste heat boiler is sent to the steam pipe network for use by steam users. Due to the large surplus of steam, the outlet pressure is high, the steam cannot be sent out, and even the high pressure in the pipe network causes steam to escape. In order to further improve waste heat utilization efficiency, 2017 2#The sintering boiler has been approved for expansion and efficiency improvement. The steam output of the sintering boiler has been further increased. In addition, other production lines have successively increased the delivery of waste heat steam. Further surplus of steam will cause greater energy waste, and the problem of effective utilization of waste heat steam will become more prominent.

Implementation content and cycle: One set of steam turbine generator set and one set of bypass temperature and pressure reduction device will be added to the renovation project. During normal operation, the low-pressure steam generated by No. 2 sintering waste heat boiler enters the steam turbine to generate electricity (at the same time, the secondary low-pressure steam of the boiler can also be recovered, about 10-15T/H, and enters the steam supply port of the steam turbine to participate in power generation). After doing work, the low-pressure steam is condensed into condensed water and returned to the sintering boiler as pure water for continued recycling. When the steam turbine is out of service for maintenance or the steam quality does not respond to the steam turbine parameters during boiler start-up, the bypass desuperheating device is operated to send the low pressure steam to the steam pipe network for user use. The steam turbine is equipped with supporting devices such as oil system, vacuum system, steam condensation system, shaft seal cooling system and circulating cooling water system. Among them, the circulating water system is equipped with dosing and bypass filtering devices. The normal operation of the system ensures that the water quality meets the standard. After the bypass filtered and backwash water is second-stage precipitated in the sedimentation tank, clear water is discharged into the company's series water system for unified treatment to meet environmental protection requirements. There are 14 high-voltage switch cabinets, 1 high-voltage fast current limiter, 2 10kV/0.4kV 1000kVA dry-type transformers, and 1 set of low-voltage distribution/MCC cabinets in the electrical building. The electrical equipment is operating normally and fully meets the needs of electricity in the area. The DCS control system adopts neywellC300 series, and the steam turbine speed control system is the Hollysys DEH system. Currently, the normal operation period of the two systems is 15 months.

(3) Energy conservation and emission reduction effect and investment payback period: The project saves 126.0082 million kWh of electricity. Based on the power conversion coefficient of 2.88tce/10,000 kWh, the energy conservation amount is 36290 tons of standard coal. Based on the enterprise's electricity purchase unit price of 0.55 yuan/kWh, the project saves 69.3045 million yuan annually. The investment amount of this project is 46.0604 million yuan, so the investment payback period of this project is 0.7 years.

(4) Potential for replication and promotion, energy-saving potential (payback period)

Energy-saving transformation of the boiler system can bring huge economic benefits. Equipment such as steam recyclers can be safely and reliably applied to waste heat recovery technology. The technical transformation method is safe and reliable, and can effectively utilize the waste heat steam of the heating furnace. It has huge energy conservation potential, obvious energy conservation and emission reduction effects, broad promotion and application prospects, and huge replication potential.