Asking for help about frequency conversion energy saving
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I would like to ask everyone, if the sulfuric acid pump and chlorine water pump used in the chlorine treatment process are added with frequency converters, will the energy saving effect be obvious? The power of these pumps does not exceed 20KW, and their annual production capacity is 150,000 tons of ion membrane caustic soda.
1. If the pump's motor power is large and the outlet flow rate often runs at low flow rate (valve position of the outlet control valve 40-80%), consider installing a frequency converter on the pump to save electricity. 2. In addition, it can be seen from fluid mechanics that P (power) = Q (flow rate) ╳ H (pressure), the flow rate Q is proportional to the square of the rotation speed N, the pressure H is proportional to the square of the rotation speed N, and the power P is proportional to the cube of the rotation speed N. If the efficiency of the water pump is certain, when the flow rate is required to decrease, the rotation speed N can decrease proportionally, and at this time the shaft output power P decreases in a cubic relationship. That is, the relationship between the power consumption of the water pump motor and the rotation speed is approximately a cubic ratio. For example: The power of a water pump motor is 55KW. When the speed drops to 4/5 of the original speed, its power consumption is 28.16KW, saving 48.8%. When the speed drops to 1/2 of the original speed, its power consumption is 6.875KW, saving 8 * * %.
Adding a frequency converter saves power when controlling the loop valve to control the conveying fluid. There is no power saving when using the outlet valve to control flow. Frequency converters are mainly easy to adjust and sensitive.
A lot has been said above in theory, but I will emphasize one point: depending on the load of your device, if there is not much margin for the pump, there is no need to install a frequency converter.
Due to the large investment in variable frequency speed regulation devices, if the power of the centrifugal pump motor is only 20kw, the energy savings will be very small, and there is no need to install variable frequency speed regulation. If you want to install frequency conversion, it is recommended that it is at least 100kw to be valuable.
I don't agree with the point above. A 20KW inverter only costs a few thousand to ten thousand yuan, and a 50KW inverter costs around 40,000 yuan. It should be emphasized that the frequency converter itself is not energy-saving, and the efficiency is only about 92%. The key to energy saving or not is to see whether it is often operated under low load conditions. The reason has been analyzed on the second floor (flow rate and speed are not strictly linear relationships. You can check the operating curve chart in the water pump data, and it can only be estimated approximately). Investment and return should not only be measured in absolute terms, but also in proportion. In addition, the upconverter can realize stepless and non-contact adjustment, which is beneficial to the use of water pumps and valves (replacing regulating valves) in corrosive environments. If the LZ pump does not need to adjust the flow through the valve under operating conditions, or the pump itself only runs intermittently for a short period of time, the upconverter will not benefit.