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The flow rate of the stainless steel gear pump can be adjusted by changing the characteristic curve of the stainless steel gear pump pipeline, the series and parallel connection of the pump, the flow rate can be adjusted by adjusting the pipeline valve, and the installation height of the stainless steel gear pump can be adjusted. , And adjusting the pipe diameter of the stainless steel gear pump can change the flow rate of the stainless steel gear pump.
1 The main method of flow adjustment of stainless steel gear pump
1.1 Change the pipeline characteristic curve
The simple way to change the flow rate of a stainless steel gear pump is to use the opening of the pump outlet valve to control. The essence is to change the position of the pipeline characteristic curve to change the pump's working point.
1.2 Change the characteristic curve of stainless steel gear pump
According to the law of proportionality and the law of cutting, changing the speed of the pump and changing the pump structure (such as cutting impeller outer diameter method, etc.) can change the characteristic curve of the stainless steel gear pump, so as to achieve the purpose of adjusting the flow rate (at the same time changing the pressure head). But for the already working pump, the method of changing the pump structure is not convenient, and because the structure of the pump is changed, the versatility of the pump is reduced, although it is economical and convenient to adjust the flow rate at some time [1], and it is also very convenient in production Use less. Here only analyze the method of changing the speed of the stainless steel gear pump to adjust the flow. Analyze from Figure 1, when the pump speed is changed to adjust the flow rate from Q1 to Q2, the pump speed (or motor speed) drops from n1 to n2, and the pump characteristic curve QH and pipeline characteristic curve He=H0 at the speed of n2 +G1Qe2 (the pipeline characteristic curve does not change) intersect at point A3 (Q2, H3), point A3 is the new operating point after the flow rate is adjusted by speed regulation. This adjustment method has obvious, fast and reliable adjustment effect, can prolong the service life of the pump, save energy, and then reduce the speed of operation can effectively reduce the NPSHr of the stainless steel gear pump, keep the pump away from the cavitation zone and reduce the stainless steel gear The possibility of pump cavitation [2]. The disadvantage is that changing the speed of the pump requires frequency conversion technology to change the speed of the prime mover (usually {HotTag} motor). The principle is complicated, the investment is large, and the flow adjustment range is small.
1.3 The serial and parallel adjustment methods of pumps
When a single stainless steel gear pump cannot meet the delivery task, parallel or series operation of stainless steel gear pumps can be used. Using two stainless steel gear pumps of the same model in parallel, although the pressure head changes little, the total delivery flow is increased. The total efficiency of the parallel pumps is the same as that of a single pump; the total pressure head increases when the stainless steel gear pumps are connected in series. The total efficiency of the series pump is the same as that of a single pump.
2 Energy consumption analysis of pumps under different adjustment methods
In the analysis of energy consumption under different adjustment methods, the article only analyzes the two adjustment methods currently widely used in valve adjustment and pump variable speed adjustment. Since the purpose of parallel and series operation of stainless steel gear pumps is to increase the pressure head or flow rate, they are not used much in the chemical industry. The energy consumption can be analyzed in conjunction with Figure 2, and the method is basically the same.
2.1 Power consumption when the valve adjusts the flow
When the stainless steel gear pump is running, the power N of the motor input to the pump shaft is:
N=vQH/η
Where N——shaft power, w;
Q——The effective pressure head of the pump, m;
H——The actual flow of the pump, m3/s;
v——The specific gravity of fluid, N/m3;
η——The efficiency of the pump.
When the valve is used to adjust the flow from Q1 to Q2, the shaft power consumed at operating point A2 is:
NA2=vQ2H2/η
vQ2H3——The actual useful power, W;
vQ2(H2－H3)——Power loss on the valve, W;
vQ2H2(1/η-1)——The power lost by the stainless steel gear pump, W.
2.2 Power consumption when adjusting the flow rate at a variable speed
In the variable speed analysis, due to the proportional law of the stainless steel gear pump, according to its application conditions, the following analysis refers to the variable speed range of the stainless steel gear pump within ±20%, and the efficiency of the stainless steel gear pump itself does not change much [3] . When the motor is used to adjust the flow rate to flow rate Q2 at a variable speed, the shaft power consumed by the pump at operating point A3 is:
NA3=vQ2H3/η
The same transformation can be obtained:
NA3=vQ2H3+vQ2H3(1/η-1) (2)
Where vQ2H3—— actual useful power, W;
vQ2H3(1/η-1)——The power lost by the stainless steel gear pump, W.
3 Conclusion
Regarding the two main flow adjustment methods that are currently used for stainless steel gear pumps: outlet valve adjustment and pump variable speed adjustment, the energy saving of pump variable speed adjustment is much greater than that of outlet valve adjustment. This can be seen from the power consumption analysis and work of the two. Consumption comparison analysis sees. Through the relationship between the flow rate and the head of the stainless steel gear pump, the energy consumption relationship under the two adjustment methods can be directly reflected. Decreasing the flow rate through pump variable speed adjustment is also beneficial to reduce the possibility of cavitation in the stainless steel gear pump. When the flow rate decreases, the energy-saving efficiency of the variable speed adjustment is also greater, that is, the greater the power loss of the valve adjustment, but when the pump variable speed is too large, the pump efficiency will be reduced, which exceeds the range of the pump proportional law. Therefore, in practical applications It should be considered from many aspects, and a good flow adjustment method should be integrated between the two.
Through the characteristic curve diagram of stainless steel gear pump and piping system, several main methods of flow adjustment of stainless steel gear pump are analyzed: outlet valve adjustment, pump variable speed adjustment and pump series and parallel adjustment. The characteristic curve diagram is used to analyze the energy consumption loss of the outlet valve adjustment and the pump variable speed adjustment, and the comparison is made. It is pointed out that the stainless steel gear pump uses the variable speed adjustment flow rate to save energy consumption and energy efficiency better than the outlet valve adjustment flow rate. It is related to the change in flow rate. In actual application, attention should be paid to the range of variable speed adjustment, in order to apply stainless steel gear pump variable speed adjustment.
Stainless steel gear pump is a general fluid machinery widely used in chemical industry systems. It has a wide range of performance adaptation (including flow rate, pressure head and adaptability to the nature of the conveying medium), small size, simple structure, easy operation, low operating cost and many other advantages. Generally, the flow rate and pressure head of the selected stainless steel gear pump may be inconsistent with the requirements in the pipeline, or due to changes in production tasks and process requirements, the pump is required to adjust the flow rate, which is essentially to change the work of the stainless steel gear pump point. The working point of the stainless steel gear pump is determined by the characteristic curve of the pump and the characteristic curve of the piping system together. Therefore, changing any characteristic curve can achieve the purpose of flow regulation. At present, the flow adjustment methods of stainless steel gear pumps mainly include regulating valve control, variable speed control, and pump parallel and series adjustment. Due to the different principles of various adjustment methods, in addition to their own advantages and disadvantages, the energy loss caused is also different. In order to find a better, low-energy, energy-saving flow adjustment method, {TodayHot} has a comprehensive understanding of the flow rate of stainless steel gear pumps The relationship between adjustment methods and energy consumption.
Our company mainly produces KCB series stainless steel gear pumps, YCB series arc stainless steel gear pumps, 2CY series spur-type high-pressure stainless steel gear pumps, YZB-type supercharged stainless steel gear pumps, which can be customized to meet a variety of different materials and different working conditions. The stainless steel gear pump used under.
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