1. The main principles and energy-saving effects of high-efficiency and energy-saving motors
A high-efficiency energy-saving motor, literally explained, is a general-purpose standard motor with high efficiency value. It adopts new motor design, new technology and new materials, and improves output efficiency by reducing the loss of electromagnetic energy, thermal energy and mechanical energy; that is, effective output A motor whose power is a higher percentage of the input power.Compared with standard motors, high-efficiency and energy-saving motors have obvious energy-saving effects. Under normal circumstances, the efficiency can be increased by an average of 4%; the total loss is reduced by more than 20% compared with ordinary standard series motors, and energy saving is more than 15%.Taking a 55-kilowatt motor as an example, a high-efficiency and energy-saving motor saves 15% of electricity compared to a general motor. The electricity bill 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 main advantages of high-efficiency and energy-saving motors in use are: (1) 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. (2) The stable operation time of the equipment or device becomes longer, and the economic efficiency of the product is improved; (3) 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; (4) Greatly Reduce environmental pollution; (5) The power factor of the motor is close to 1, and the quality factor of the power grid is improved; (6) 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.
2. The main role and selection conditions of high-efficiency energy-saving motors in power plants
Power plants are responsible for most of the power supply tasks in the country. At the same time, the production process of power plants is completely mechanized and automated, requiring many machines driven by electric motors to serve as their main and auxiliary equipment, so they are large consumers of electrical energy.At present, the competition in the power industry is very fierce, but the key is the competition in manufacturing costs, so the work of reducing consumption and increasing efficiency is extremely important.There are three main economic and technical indicators for generator sets: power generation, coal consumption for power supply, and power consumption.These indicators are all related to each other.For example, a 1% change in the factory power consumption rate has an impact coefficient of 3.499% on the coal consumption for power supply, and a 1% drop in the load rate affects the factory power consumption rate to increase by 0.06 percentage points.Based on the installed capacity of 1000MW, if it is operated under the rated operating conditions, the factory power consumption rate is calculated at 4.2%, the factory power consumption capacity is 50.4MW, and the annual power consumption is about 30240×104kW.h; if the power consumption of the factory is used A reduction of 5% can save about 160MW.h of electricity consumed by the plant every year. Calculated at an average on-grid electricity price of 0.35 yuan/kW.h, it can increase the income of electricity sales by more than 530 million yuan, and the economic benefits are very obvious.From a macro perspective, if the average power consumption rate of thermal power plants decreases, it will relieve the pressure on resource shortage and environmental protection, improve the economic efficiency of thermal power plants, curb the increasing power consumption rate, and ensure the sustainable development of my country's national economy. It is of great significance.
Although high-efficiency motors are more efficient than standard motors, in terms of cost and manufacturing costs, under the same circumstances, the price of high-efficiency motors will be 30% higher than ordinary motors, which will inevitably increase the initial investment of the project.Although the price is higher than that of ordinary Y series motors, considering the long-term operation, as long as the motor can be selected reasonably, the economy is still obvious.Therefore, in the selection and bidding of power plant auxiliary equipment, it is necessary to select the appropriate equipment with a target and use high-efficiency energy-saving motors.
A lot of optimizations have been made in the process major, and the electric water supply pump has been cancelled; the electric induced draft fan has been cancelled and driven by the steam driven induced draft fan; but there are still many high-voltage motors as the driving device of the main 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 large economic benefits:
(1) For the motors with long operating hours and more than annual operating hours in engineering power plants.
For motors that run more than 5000 hours per year and have a load rate of more than 70%, it is more appropriate to use high-efficiency and energy-saving motors.Take a 20000kW motor as an example. If you switch to an energy-saving and high-efficiency motor with an average efficiency increase of 1%, the annual average operating time is 5000 hours, and the power saving can reach 100 million kWh.
(2) The plant voltage level is high (6kV or 10kV in this project), and at the same time it consumes large power motors with large plant power.
According to statistics, eight types of fans and pumps in thermal power plants nationwide, namely blowers, induced draft fans, primary fans, powder exhaust fans, boiler feed water pumps, circulating water pumps, condensate pumps and mortar pumps, have a total capacity of 15000 MW per year. The total electricity consumption is 520 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 300-500 billion kWh/year, which is equivalent to the total annual power generation of 6-10 large-scale thermal power plants with an installed capacity of 1000MW.
The auxiliary motors of this project mainly include: blower and primary fan of air and smoke system, coal mill of pulverizing system, condensate pump and circulating water pump of circulating water and water supply system, etc. The high pressure of these large-capacity fans and water pumps Electric motors; the total power consumed by these high-voltage auxiliary machines accounts for 65%-70% of the total plant power consumption. They are also the main power-consuming equipment with large capacity and high power consumption.Deeply tapping the power-saving potential of high-voltage motors is the key and starting point for reducing power consumption and plant power consumption.
(3) Supporting motors corresponding to equipment that play a key role in each system. These equipment adopt new high-efficiency and energy-saving motors, which will greatly improve the reliability of power supply.
These equipment mainly include: steam turbine system condensate pump, generator stator cooling water pump, closed loop cooling water pump, mechanical vacuum pump, shaft seal fan, turbine main oil pump, AC lubricating oil pump; boiler system blower, primary fan, coal mill; Absorption tower circulating pumps and oxidation fans within the scope of desulfurization contractors; ash removal and instrument air compressors for material conveying systems; various belt conveyors; circulating water pumps for circulating water systems; air conditioning chillers for HVAC systems, etc.The important equipment of these process systems is the main object of optimization using new high-efficiency energy-saving motors.
