light industry

First, the basic situation
The factory original equipment steam boiler with chain grate boiler, induced draft fan electric 72KW and blower motor 55kW, grate motor for 5, 5kW, grate motor by DC speed control to adjust the size of the amount of coal, blast and a draught of air through the damper to achieve. The method of reducing starting voltage is adopted in the blower and the air guide motor.
Two, now the boiler wind system operation status analysis
1, the ability to adapt to the load changes in the production process is poor
Due to the change of production load and climate, the boiler system is required to follow the change of the boiler system.
With DC speed adjusting, into the coal mass and speed is proportional to, air flow through the regulating damper, throttle opening size and volume regulation is not proportional, ratio of wind and coal cannot adapt to the efficient load changes.
2, the existing wind system can not meet the technical requirements of the boiler operation
Adjustable damper is small, air rate is reduced; but to increase the pressure, in order to make the coal seam is blown broken, resulting in furnace on wind, it is necessary to make thicker coal seam, this coal can not ensure full combustion, resulting in increased coal consumption.
3, a serious waste of energy
The general adjusting door is not convenient, often make the air and wind system are in a state of excess supply. Air supply excessive, outside air (40 DEG C) too much into the furnace (above 500 DEG C) need to absorb a lot of heat, send into the coal waste, send wind motor current is higher, resulting in a waste of energy; draught excess, caused a lot of hot air cited wind system away, although after the economizer, the exhaust gas temperature is still excessive, caused the coal waste, also cited wind motor current up to rated value, the electric energy wasted.
4, motor start impact power grid
Although the starting method is adopted, the starting current is 3-4 times higher than the rated current, and the operation is complex, the maintenance quantity is large, the equipment failure rate is high, and the maintenance cost is increased.
Three, variable frequency speed control system is the inevitable trend of energy saving, energy saving and improving the thermal efficiency of chain grate furnace.
1, variable frequency and adjust the wind has incomparable superiority.
(1) energy saving effect is remarkable
According to the characteristics of the centrifugal fan, the wind speed change is proportional to the speed of the wind turbine, and the power is proportional to the cube of the rotating speed. Therefore, when the load is adjusted, the rotating speed is changed, so that the shaft power is obviously decreased, and the energy saving effect is obvious.
According to the characteristics of the centrifugal fan, the wind speed change is proportional to the change of the speed, and the power is proportional to the cube of the rotating speed. Therefore, when the load is adjusted, the rotating speed is changed, so that the shaft power is obviously decreased, and the energy saving effect is obvious.
(2) fully meet the technical requirements
Air volume and speed time is proportional to the square, air volume control and pressure size controllable, can fully meet the combustion system of a wind adjusting process requirements can be large reductions in the amount of fly ash, improve the heat exchange efficiency, reduce environmental pollution, coal saving.
2, the efficiency of the wind turbine is calculated by the following formula
ηp=C1(Q/n)-C2(Q/n)2
Type of Q for the wind, n for speed, C1C2 constantType of Q for the wind, n for speed, C1C2 constant
The throttle control air volume, speed and flow rate of trapped n unchanged, Q decreased, so the efficiency of P
Decreased, and through the speed control of air volume, air volume and speed is proportional to, constant ratio (Q/n), so the efficiency ETA P always keep best.
Obviously, the use of frequency control, the fan will greatly improve the efficiency of the work.
Four, economic benefit analysis
1, saving electricity
75KW fan and 55KW blower to run the frequency of 40HZ, for example, the operating speed of 80% of the rated speed, the wind power consumption of P2=0.83Pn=0.512Pn
According to the annual production period of 12 months, considering the kind of loss to power saving 30% calculation.
W= (75KW+55KW+5.5KW) * 30 * 24 * 12 * 30%=351216KW.h.
With the electricity price of 0.5 yuan per kilowatt hour, the electricity can be saved every year.
351216 * 0.5 yuan =175608 yuan
2, saving coal
3, the wind coal ratio with convenient, can well adapt to the load change, the best way to improve the thermal efficiency of combustion. In the case of production of the equivalent amount of steam, the provincial coal 5%, one year to save coal by 60T per day of coal, the price by 200 yuan /T calculation, can save the cost per day by coal 60T calculation, the price by 200 yuan /T calculation, can save:
60 * 5% * 30 * 200 * 12=216000 yuan.
After the transformation of frequency conversion, the direct economic benefits of a year to achieve
175608+216000=391608 element
Five, equipment investment
55KW 75KW
Name type quantity
Frequency converter ECF100-T3-75kw 1 ECF100-T3-55kw 1
Converter and accessories price
Transport premium
Installation fee
total
Total aggregate
Frequency converter service life of up to five years, the return on investment is calculated as follows:
75KW day electricity tariff: 75 x 24 x 30% x 0.5=270 yuan
55KW day electricity tariff: 55 x 24 x 30% x 0.5=198 yuan
139608, investment recovery (270+198), 30=9.9
Investment recovery 139608÷（270+198）÷30=9.9month