Application value of frequency conversion technology in boiler heating system

Variable frequency speed regulation is a kind of equipment that can realize stepless speed regulation of motor, which has incomparable advantages of asynchronous motor voltage regulation and cascade speed regulation, and is widely used in boiler system. Variable frequency speed regulation is mainly used for fan speed regulation and water pump speed regulation in heating boiler system. Generally, in the boiler combustion system, wind speed, air volume, temperature and other indicators are controlled and adjusted according to production needs to meet user requirements and operating conditions. The most common control method is to adjust the opening of the damper and baffle to adjust the controlled object. In this way, regardless of the production demand, the fan must run at full speed, and the change of working conditions will cause the throttle loss of energy consumed by the damper and baffle.

In the production process, not only the control accuracy is limited, but also a lot of energy waste and equipment loss are caused. As a result, the production cost increased, the service life of the equipment shortened, and the maintenance and repair costs of the equipment remained high. In the heating boiler system, there are circulating pumps, make-up pumps and other pumps. According to different production requirements, throttling devices such as regulating valve, return valve and stop valve are usually used to control flow, pressure and water level signals. This not only wastes a lot of energy, damages the sealing performance of pipes and valves, but also accelerates the wear and cavitation of pump cavity and valve body, and seriously damages equipment and affects production.

At present, fans and water pumps are mostly driven by asynchronous motors, which have the disadvantages of large starting current, large mechanical impact and poor electrical protection characteristics. It not only affects the service life of the equipment, but also fails to protect the equipment immediately in case of mechanical failure of the load, which often leads to pump damage and motor burning.

In recent years, due to the urgent need for energy conservation and the continuous improvement of heating quality, as well as the characteristics of frequency converter (referred to as frequency converter), such as simple operation, maintenance-free, high control accuracy and strong functionality. Now, with the variable frequency drive scheme starting to gradually replace the control scheme of damper, damper and valve. Using frequency converter to regulate the speed of asynchronous AC motor is a new technology developed rapidly in the late 1980s. Its advantages are: good mechanical characteristics of speed regulation, wide speed regulation range, smooth regulation characteristic curve, continuous and stable speed regulation, especially when applied to large-capacity loads such as fans and pumps, it can achieve significant energy-saving effect.