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Brief introduction of the transformation direction of fan water pump power saving technology

2019/11/09

[This article is provided by Shangyu Fan xwqcc.cn]

Fan water pump power saving technology transformation direction

As iron and steel enterprises are energy-intensive industries, the individual power consumption of fans and pumps is relatively small. In the past it was not enough. In fact, due to the wide use and large number of fans and pumps, their power consumption and proportion are still quite large. Steel enterprises use hundreds of thousands of centrifugal and axial fans and water pumps with a power of more than 5.5 kW, and their installed capacity is also on the scale of tens of millions of kilowatts. The current use efficiency of fans and pumps is mostly lower than the 70% and 60% requirements of the State Council's "No. 2 Power Saving Directive", and a considerable part as low as 20% ^ -40%. It is estimated that inefficient machine pumps account for About 40% of the total. It is completely possible to take a small investment, mature and reliable energy-saving measures, and implement extensive transformation to achieve energy savings of more than 20% on the premise of conducting efficiency test analysis and formulating targeted solutions. In recent years, iron and steel enterprises have eliminated low-efficiency pumps, promoted high-efficiency energy-saving pumps, reasonably selected and matched them, carried out power balance and efficiency side tests, made the pump systems economical, realized optimized distribution of pipe networks, reduced throttling losses, and adopted Some new energy-saving technologies have made rapid progress and achieved remarkable results. The main transformation directions are as follows.

Reasonable selection and matching

Fans, pump pressures, and excess heads are one of the main reasons for their low operating efficiency. The negative pressure of No. 4 exhaust fan of Shougang Tangle Plant is on average about 30% higher. Not only the power consumption is large, but also the sintered section layer is compacted and the air permeability is poor. In June 1986, the plant adopted a turning impeller transformation method to reduce the diameter of the fan rotor from 2400mm to 2180mm. The original two 1600k W motors were replaced by a 1600k W motor, which saved 400k W · h / ( Taiwan · h). Shanghai Meishan Metallurgical Company's 2 X 1060m 'blast furnace equipped with domestic steam turbine drives 3 sets ((1 spare) 580 axial flow fixed vane blowers with speed adjustment as a means, the characteristics do not match the working state of the blast furnace, within the speed adjustment range The air volume and air pressure requirements of the blast furnace cannot be met at the same time, and each unit evacuates 800 ~ 10001n '/ min air volume, that is, 25% -30% of the blast energy is released, and the annual loss is 350,000 yuan. They take changes to each The energy-saving reform measures for the installation angle of the stationary blades of the row have achieved the effect of reducing the air release by more than 400m '/ min for 7 single units, and correspondingly reducing the power consumption of the power turbine by 1600kw.

For the defect of single-stage pump with too high lift, cutting the impeller to reduce the H-Q curve to make it run in the high-efficiency area is a cost-saving measure that is simple, easy to implement, and quick to produce. But the pump flow, head, shaft power and the outer diameter of the impeller have a certain relationship. Therefore, the cutting impeller should be performed one by one to avoid cutting too much at one time.

Sometimes the pump's head is high, but the power saving effect of simply cutting the impeller is not ideal. At this time, according to the requirements of flow and head, the method of combining the increase of the leaf diameter and the speed reduction can be used to achieve the purpose of power saving. For example, a 20SH-9B water pump in a factory has a rated head of 42m, a flow rate of 1764m '/ h, and a rated efficiency of 74%. However, the head of the pump in actual operation is only 29m, so the efficiency is only about 58%. During the test, it can be clearly seen that the pump head is too high and the pipeline system does not match. For example, simply using cutting or speed adjustment, because the pump is already a B-type impeller, it is not suitable to cut, so the impeller diameter B type can be changed to The positive type, that is, the diameter of the impeller is expanded from 600mm to 682mm, and then the speed is reduced from 970r / min to 740r / min (six-pole motor to eight-pole motor) according to the flow needs. In this way, under the condition that the pressure of the main pipe is unchanged, the operating efficiency is increased from 58% to 77%, the electric power is reduced from 332kW to 20ok W, and the water and electricity consumption per cubic meter is reduced from 0.1457kW · h to 0.195kW · h, It can save 470,000 kWh of electricity throughout the year.

The total investment of 8,000 yuan can be recovered in only three months. For multi-stage pumps with high lift, pumping operation method can be adopted. For example, the current GC-type multi-stage pump for boiler water supply often has more pressure, so it can pump one to two stages to achieve the purpose of improving efficiency and reducing losses. When drawing a level, you can detach any level in the middle. When you draw two levels, you can detach the middle two or four or three or five. The first and last two levels are not removed.