Talking about Increasing the Efficiency of Large and Medium Axial Flow Pumps

Abstract: Based on the factors affecting the efficiency of medium and small axial flow pump devices, this paper proposes technical measures to improve the efficiency of medium and small axial flow pump devices. Practice has proved that as long as the energy-saving measures for axial-flow pumping stations are seriously implemented and the efficiency of pumping stations is increased to meet the ministerial standards, it is entirely possible to achieve them.

The Yuncheng Zuncun Yellow River Lifting Irrigation District has an area of ​​1.6 million mu of irrigated land, a total head of lift of 165.8m and an installed capacity of 62,000 kW. The plant is mainly wheat and cotton. The existing irrigation area has eight stations and eight stations. Axial flow pump is one of the main water lifting tools. Due to the reasons of design, construction, and management, most of its equipment is “disease-free work”, which has high energy consumption and low efficiency. Once the peak period of water consumption is reached, water tension is extremely serious. In recent years, 10 medium and small axial pumping stations have been tested. The average device efficiency is only 396%, and the energy consumption is 7.33kW/(kt*m), which greatly exceeds the ministerial standard. The waste is very serious. Therefore, the potential for energy saving is very large. We will initially discuss the issues concerning the optimization of the efficiency of the small and medium-sized axial-flow pumping stations in the Zuncun Irrigation District.

1 Factors influencing the efficiency of the pumping station The efficiency of the pumping station refers to the comprehensive efficiency of the pump, motor, transmission, and pipeline in and out of the pumping station. The relationship is as follows: n = n = pumping pipe transmission pool costs 2.2. 1 Benefit calculation If you do not consider the impact of past investments, you should only calculate the portion of the investment resulting from the conversion when calculating benefits. The existing benefits should not be included. Still take the project cited above as an example. After investing 600,000 yuan in the transformation of the project, there are two aspects of the benefits: First, 2000 acres of new water, annual irrigation benefits of 80,000 yuan.

The second is to reduce the annual operating cost of the existing 10,000 mu of water from 300,000 yuan to 240,000 yuan. The benefit brought by the entire transformation investment should be: 80,000 yuan + (300,000 yuan - 240,000 yuan) = 140,000 yuan.

If the area of ​​water area is not increased after the renovation, only the annual operating cost of the existing water area will be reduced, and the benefit brought by the reform investment should be 60,000 yuan.

2.2.2 Investment and annual operating cost calculation This method is to treat all previous investments as submerged, only the investment required for the renovation project. In the above example, the investment should be calculated in accordance with the method of calculation of the investment of RMB 600,000. The annual operating cost should not be the power fee, maintenance fee, and management fee required for the entire project every year after the transformation. The annual operating costs required to transform the benefits. In the above example, when 2000 acres of newly added water land were reconstructed, the annual operating cost of the reconstruction project should be 50,000 yuan for the electricity, maintenance, and management fees needed to irrigate the 2000-mu land each year.

If there is no increase in water after the renovation, only the annual operating cost of the existing land is reduced, then the annual operating cost of the renovation project can be calculated by zero.

3 Evaluation of Two Calculation Methods Among the above two methods, although the overall concept is clear, the first one is complicated, especially for small and medium-sized projects. Due to the lack of basic data, the investment in the process of building and operation and fixed assets The formation of the situation is very difficult to grasp truthfully, and therefore the calculation results will be very inaccurate. Although the second method does not reflect the economic benefits of the entire project after the transformation, it can reflect the economic benefits of the transformation investment more intuitively and practically, and can provide the superior authorities with the decision whether to invest in the transformation of existing projects. Therefore, we believe that the second method is better for the technical upgrading of irrigation irrigation projects.

Industry, engineers.

Wang Guang: To improve the efficiency of large- and medium-sized axial flow ocean devices, we can see from the formula that the efficiency of pumps, motors, transmissions, pipelines, access to and from the pool is high, and the efficiency of the entire device is high; conversely, the efficiency of the entire device is low. It can be seen that to improve the efficiency of pumping stations, we must first improve the efficiency of pumps, motors, transmissions, pipelines, and water inlets. 1.1 Influence of motor efficiency According to the survey, more than 70% of pumping stations have problems of “big horse-drawn cars”. In the energy-saving transformation of the pump station, some people think that adjusting the large machine with a small pump is a key measure to increase the efficiency of the device. The theoretical data and experimental analysis prove that the adjustment of the motor has little effect on the device efficiency. This is because the motor is an efficient power machine. When the load rate is around 075, the motor efficiency reaches its maximum value. When the load rate is less than 0 5, the efficiency begins to decrease, but the load rate of the motor is generally above 06.

By testing the efficiency of the motor, the results show that: regardless of the structure of the motor, it basically reaches the required value of the performance curve. Therefore, it is of little significance to eliminate the motor.

1.2 The effect of low efficiency and high consumption of water pump The key to improving the efficiency of the pump and reducing the hydraulic loss is the key. Water pump hydraulic losses include friction losses, local losses and shock losses. Due to the design, construction, management, and other reasons, coupled with the large sediment-bearing volume of the Yellow River, the pumps often work below the design operating point. When the water flow enters the blades, it is not tangent to the blades. At the inlet of the impeller, at the exit, and Pressing out of the room causes an increase in the impact loss, causing the water pump to operate in an inefficient zone. As a result, the operating point of the pump is deviated from the high efficiency zone and the efficiency of the pump is greatly reduced.

1.3 Influence of pipelines The main factors affecting pipelines are the phenomenon of “more than one long and one long”, more than three valves and more valves, more elbows and more anti-aircraft artillery outflows; one long pipe, which is more than three long and one long, “causes the efficiency of the pipeline. Decline, which is another major factor in the decrease of efficiency of pumping station equipment, such as anti-aircraft gun-type effluent drop mostly in the range of 06~1.1m, it can be seen that waste is also very serious, but in Zuncun Yellow River Irrigation Area is generally submerged outflow. There is more water in the elbow, so the pipeline has little effect.

1.4 Influence of Transmission Mode For a long time, the axial pump transmission mode pump is a direct drive and the transmission efficiency is ideal.

1.5 Influence of Pool Efficiency Pool efficiency has a great influence on the efficiency of the pump station installation and is often overlooked. According to the test data analysis, there are impurities imported, affecting the efficiency of the device by 5% to 20%; the deposition of the fore tank affects the efficiency of the device by 5% to 8%; in addition, the flow state of the influent also has a great influence on the efficiency of the pool.

2 Technical Measures to Improve the Efficiency of Pumping Stations Based on the above analysis, to improve the efficiency of pumping stations, we must do a good job in the following aspects.

21 do a good job of adjusting the pump supporting the main measures are: 1 pump reasonable support, to avoid the big horse car, strictly control the pump speed, according to the actual power distribution with the head, with speed, if the pump head is much larger than the lift head actual lift, can The water pump runs at a reduced speed, but it must not exceed 60%, so that the water pump is always working in an efficient area.

2 do a good job of aging replacement pump replacement work.

3 pay attention to the small stop change of the pump, often maintenance, replacement of wearing parts, such as insert ring, change the impeller, etc., these small repair small change, small investment, large profits, should be paid attention to.

22 to cancel the "three more and one long", to promote the pipeline ramp obliquely, reduce the elbow, shorten the pipeline, resolutely cancel the anti-aircraft gun-type water, while optimizing the pipeline design, appropriate expansion, promotion and use of economic diameter, to ensure that the pipeline is not leaking Without leakage, the loss along the pipeline and local losses are minimized.

23 Improve inlet and outlet flow patterns, reduce losses, improperly design the shape and size of the inlet basin, cause vortexes, backflow, etc. in the pool. Optimize inlet and outlet basin design parameters, perform technical transformation of inlet and outlet basins, and ensure water flow. Smooth, smooth connection, ensure that the water pump pipe in the pool has enough submerged depth to prevent the occurrence of harmful vortexes and eliminate the high water level of the pool.

24 Take effective energy-saving measures, such as dredging the front pool, removing weeds during operation, cleaning the trash rack, installing automatic weed removal machines, improving water quality, and lifting the door when running. These are all effective measures. In addition, while the technical transformation of the pumping station increases the efficiency of the pumping station, it is also necessary to pay attention to increasing the water discharge flow of the pump and ensuring the agricultural production water and industrial water use.

In addition, it can also exchange large pumps, so that it can not only reduce the water after the pump speed reduction, but also solve the contradiction between the big machine with a small pump, killing two birds with one stone.

Direct drive reduces transmission losses.

3 Concluding remarks After the 1st Nu Jiuzun Village Yellow River Irrigation District has completed the energy-saving renovation of the 5 pumps of the secondary station, the efficiency of the pouring plant in the spring of 2001 was increased from 39.6% to 59% in the spring, saving 43% in electricity costs. As long as the axial pump technology reform and various energy-saving measures are seriously implemented and the efficiency of the pump station is increased, it is entirely realistic to meet the ministerial standards.

Industry, engineers.

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