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Key words: frequency converter, cement plant, energy-saving retrofit Inverter converts constant voltage constant frequency provided by grid voltage into converter whose voltage and frequency can be changed by control, so that the motor can be better driven by the power of variable voltage. Work performance.
In the cement manufacturing industry, most of the motors in most cement plants, especially high-power motors, mostly meet the different air volume requirements through mechanical adjustment methods that adjust the opening angle of the windshield during the production process. Yes: 1) The motor and fan have high rotation speed, heavy load intensity, and serious waste of electrical energy; 2) poor adjustment accuracy and inaccurate control; 3) high starting current impact on the power grid; 4) large mechanical shock during starting and low equipment life 5) Large noise, serious dust pollution, etc. Therefore, the high power consumption of these high-power and continuous-operation motors is an important factor in the high cost of cement manufacturing. According to statistics, the cost of electricity accounts for about 30% of the total cost in cement manufacturing costs. Therefore, it is necessary to make some technological energy-saving transformations for the corresponding high-power motors, and to use the effect of electricity saving to reduce the cost of cement production. Improve the operating profit margins and market competitiveness.
After the frequency conversion reformation, it has the following features: 1) It does not need full-load operation, and it has good power-saving effect; 2) It has a soft-start function, reduces the load intensity, and prolongs the service life of the equipment; 3) The starting current is small, which is equivalent to increasing the capacity of the power grid; 4) The accuracy of air volume adjustment is accurate; 5) There is no need to bypass ventilation to reduce cement dust pollution; 6) Protect motor and other equipment in time to ensure reliable operation of the equipment.
The basic principle of variable frequency speed control technology is based on the relationship between the motor speed and the input frequency of the power supply:
n=60f(1-s)/p, (where n, f, s, and p respectively represent the rotation speed, input frequency, motor slip ratio, and number of motor pole pairs); the motor speed can be changed by changing the operating power frequency of the motor. purpose. Inverter is based on the above principle using AC-DC-AC power conversion technology, power electronics, microcomputer control and other technologies in a comprehensive electrical products. According to the basic laws of fluid mechanics, it can be known that fans and pumps are all square torque loads. The rotational speed n, flow Q, pressure H, and axial power P have the following relationships: Qâˆn, Hâˆn2, Pâˆn3; The flow is proportional to the speed, and the pressure is proportional to the square of the speed. The shaft power is proportional to the cube of the speed.
For the energy saving effect of frequency conversion speed regulation for fans and pump equipment, the following two methods are usually used for calculation:
1, according to the fan, pump square torque load relationship: P / P0 = (n / n0) 3 calculations, where P0 rated speed n0 when the power; P is the speed n power.
Take the three wind turbines that have been transformed as an example. After the transformation, the rotation speeds were 1173 r/min, 1068 r/min, and 1017 r/min, respectively. The energy saving rate (excluding inverter self-consumption of about 2%) is:
Y1=1-(1173/1485)3-2%=48%,
Y2=1-(1068/1485)3-2%=60%,
Y3=1-(1017/1485)3-2%=66%.
2, according to the current and voltage directly calculated before the transformation of the voltage is 380V, the current is 216A, 209A, 217A, operating conditions are still running in 24 hours, the annual operating time of 300 days, the power factor is based on 0.85 calculation.
The annual electricity of these three units before the transformation is:
Wg20=1.73×380×216×0.85×24×300=869030kW·h
Wg21=1.73×380×209×0.85×24×300=840867kW·h
Wg22=1.73×380×217×0.85×24×300=873053kW·h
After the transformation, the voltages were 300V, 260V, and 260V, respectively. Currents are 152A, 140A, and 130A, respectively.
The annual electricity consumption of these three units are:
Wg20=1.732×300×152×0.85×24×300=483352kW·h
Wg21=1.732×260×140×0.85×24×300=385388kW·h
Wg22=1.732×260×130×0.85×24×300=357860kW·h
Compared with the power saving:
Wg20=W1-W11=869030-483352=385678kW·h
Wg21=W1-W11=840867-385388=455299kW·h
Wg22=W1-W11=873053-357860=515193kW·h
Calculated by 0.5 yuan per degree of electricity, the use of frequency conversion speed G20 per year can save electricity 192,839 yuan,
G21 can save electricity 227,649 yuan.
G22 can save electricity 257,596 yuan.
Practice has proved that the frequency conversion transformation of the cement industry has significant power-saving effects and is an ideal speed control method. It not only improves the equipment efficiency, but also meets the production process requirements, and therefore greatly reduces equipment maintenance and repair costs, and also reduces the production cycle. The direct and indirect economic benefits are very obvious. The one-time investment of the equipment can usually be recovered only by saving electricity charges in a few months after the frequency conversion.
and precision machining parts.
The produced parts are widely used in Auto Parts : Agricultural, Marine; Architectural, Machinery, Medical; Food Machinery, Valves and so on. The material which we used Aluminium; Bronze; Brass; Copper; carbon steel; stainless steel and so on.
At the same time, we can offer the CNC MACHINING; Phosphating; Blackening Processing; Hot Dip Galvanizing: Powder Coating: Painting: Plating, Assembly for customers. 85% products are sold to overseas, the customers are from America, Canada, Europe Union, ect. i 15% products are sold in National Market. There are about 200 employees in our company now and around 10 technicians from medium to senior. We have the manufacturers and tester equipments, such as medium frequency furnaces; shot blaster; hardness tester; Spectrum Analysis tester; Metallurgical analysis tester, CMM; crack detection; surface roughness tester ISO9001: 2008 and TS16949 systerm to be sure the quality.
Analyze the energy-saving transformation of frequency converter in cement plant
The frequency converter converts the constant voltage constant frequency provided by the grid voltage into a converter whose voltage and frequency can be changed through control, so that the motor can perform better performance under the power supply of the variable frequency voltage.