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Research on the application of high-efficiency and energy-saving motors in power plants

Date:2022-07-18   Author:XINDA MOTOR

Main principles and energy-saving effects of high-efficiency and energy-saving motors

High-efficiency and energy-saving motor, literally explained, is a general-purpose standard motor with high efficiency value. It adopts new motor design, new technology and new material to improve output efficiency by reducing the loss of electromagnetic energy, thermal energy and mechanical energy; that is, effective output Motors with a higher power percentage than the input power. Compared with standard motors, high-efficiency and energy-saving motors have obvious energy-saving effects. Usually, the efficiency can be increased by 4% on average ; the total loss is reduced by more than 20% compared with ordinary standard series motors, and electric energy can be saved by more than 15% . Taking a 55-kilowatt motor as an example, the high-efficiency and energy-saving motor saves 15% of electricity compared with ordinary motors, and the electricity fee is calculated at 0.5 yuan per kilowatt-hour. The cost of replacing the motor can be recovered by saving electricity within two years of using the energy-saving motor.

Compared with standard motors, the advantages of high-efficiency and energy-saving motors in use are:

High efficiency and good energy-saving effect; adding a driver can realize soft start, soft stop, stepless speed regulation, and the power saving effect is further improved;

The stable operation time of the equipment or device is longer, and the economy of the product is improved;

Because the design of reducing loss is adopted, the temperature rise is small, thereby prolonging the service life of the equipment and improving the reliability of the equipment;

Greatly reduce the pollution to the environment;

The power factor of the motor is close to 1, which improves the quality factor of the grid;

There is no need to add a power factor compensator, the motor current is small, the transmission and distribution capacity is saved, and the overall operating life of the system is extended.

Main functions and selection conditions of high-efficiency and energy-saving motors in power plants

Power plants are responsible for most of the country's power supply tasks, and the production process of power plants is completely mechanized and automated, requiring many machines driven by electric motors to serve their main and auxiliary equipment, so they are large consumers of power. At present, the competition in the power industry is very fierce, but the key is the competition of manufacturing costs, so the work of reducing consumption and increasing efficiency is extremely important. There are three main economic and technical indicators of generator sets: power generation, coal consumption for power supply and power consumption. These indicators are all interrelated and affect each other. For example, every 1% change in the power consumption rate of the factory has an influence coefficient of 3.499% on the coal consumption of power supply, and every 1% decrease in the load rate affects the power consumption rate of the factory to increase by 0.06%. If the installed capacity is 1000MW, if it is operated under the rated working conditions, the power consumption rate of the factory is calculated at 4.2%, the power consumption capacity of the factory will reach 50.4MW, and the annual power consumption will be about 30240×104kW.h; if the power consumption of the factory is calculated If it is reduced by 5%, it can save about 160MW.h of electricity consumed by the plant every year. Calculated based on the average on-grid electricity price of 0.35 yuan/kW.h, it can increase the electricity sales revenue by more than 5.3 million yuan, and the economic benefits are very obvious. From a macro point of view, if the average power consumption rate of thermal power plants decreases, it will alleviate the pressure of resource shortage and environmental protection, improve the economic benefits of thermal power plants, restrain the growing power consumption rate, and ensure the sustainable development of my country's national economy. of great significance.
Although high-efficiency motors are more efficient than standard motors, from the perspective of construction cost and manufacturing costs, under the same circumstances, the price of high-efficiency motors will be 30% higher than that of ordinary motors, which will inevitably increase the initial investment of the project. Although the price is higher than that of ordinary Y series motors, from the perspective of long-term operation, as long as the motor can be reasonably selected, the economy is still obvious. Therefore, in the selection and bidding of auxiliary equipment in power plants, it is necessary to select suitable equipment with high efficiency and energy saving motors. The technology major has done a lot of optimization, canceling the electric feed water pump; canceling the electric induced draft fan, and using the steam-driven induced draft fan to drive; but there are still many high-voltage motors as the driving equipment for major equipment such as water pumps, fans, compressors, and belt conveyors. Therefore, it is recommended to evaluate and select the motor energy consumption and efficiency of auxiliary equipment from the following three aspects to obtain great economic benefits  :  

1 For the motor with long running time and more than annual operating hours in engineering power plants

For motors with a running time of more than 5,000 hours per year and a load rate of more than 70%, it is more appropriate to use high-efficiency and energy-saving motors. Taking a 20000kW motor as an example, if it is changed to an energy-saving high-efficiency motor with an average efficiency increase of 1%, the annual average running time is calculated as 5000 hours, and the power saving can reach 1 million kWh .

2. High voltage level for factory use (6kV or 10kV in this project)

At the same time, a high-power motor that consumes a large amount of factory electricity 

According to statistics, eight types of fans and pumps in thermal power plants across the country, namely supply fans, induced draft fans, primary fans, powder discharge fans, boiler feed pumps, circulating pumps, condensate pumps and mortar pumps, have a total capacity of 15,000MW of supporting motors, with an annual output of 15,000MW. The total electricity consumption is 52 billion kWh, accounting for 5.8% of the national thermal power generation. The energy saving potential of improving the operating efficiency of these fan and water pump systems can reach 30-50 billion kWh/year, which is equivalent to the total annual power generation of 6-10 large thermal power plants with an installed capacity of 1000MW.

Auxiliary motors in this project mainly include: blowers and primary blowers for air and fume systems, coal mills for pulverizing systems, condensate pumps and circulating pumps for circulating water and water supply systems, etc. These large-capacity blowers and high pressure pumps Motors; the total power consumption of these high-voltage auxiliary machines accounts for 65%-70% of the total power consumption of the plant, and they are also the main power-consuming equipment, with large capacity and high power consumption. Exploiting the power saving potential of high-voltage motors is the key and starting point for reducing power consumption and plant power consumption.


Supporting motors corresponding to equipment that play a key role in each system

These devices use new high-efficiency and energy-saving motors

Will greatly improve the reliability of power supply 

These equipments mainly include: condensate water pump of steam turbine system, generator stator cooling water pump, closed-circuit cooling water pump, mechanical vacuum pump, shaft seal fan, steam turbine main oil pump, AC lubricating oil pump; supply fan, primary fan, coal mill of boiler system; Absorption tower circulating pump and oxidation fan within the scope of desulfurization contractor; ash removal and medical air compressor of material conveying system; various belt conveyors; circulating water pump of circulating water system; air-conditioning chiller of HVAC system, etc. The important equipment of these process systems is the main object of optimization by adopting new high-efficiency and energy-saving motors.