First, the basic structure of the self-priming centrifugal pump is composed of six parts.
The basic structure of the self-priming centrifugal pump is composed of six parts: impeller, pump body, pump shaft, bearing, sealing ring and stuffing box.
1. The impeller is the core part of the self-priming centrifugal pump. It has a high rotational speed and the blade on the impeller plays a major role. The impeller must pass the static balance test before assembly. The inner and outer surfaces of the impeller are required to be smooth to reduce the frictional loss of water flow.
2, the pump body is also called the pump casing, it is the main body of the pump. It acts as a support and is attached to the bracket on which the bearing is mounted.
3. The function of the pump shaft is to connect the coupling to the motor and transfer the torque of the motor to the impeller, so it is the main component that transmits mechanical energy.
4. The bearing is a member that supports the pump shaft on the pump shaft, and has two kinds of rolling bearings and sliding bearings. Rolling bearings use butter as a lubricant to refuel properly. Generally 2/3 ~ 3 / 4 of the volume will be too much heat, too little and there is noise and heat! The plain bearing uses a transparent oil as a lubricant and refuels to the oil line. Too much oil will ooze along the pump shaft and float, too few bearings will overheat and burn out! During the operation of the pump, the temperature of the bearing is high at 85 degrees and generally runs at about 60 degrees. If it is high, it is necessary to find the cause (whether there are impurities, whether the oil is black or not, whether it is water) and deal with it in time!
5, the seal ring is also known as the leak reduction ring. The gap between the impeller inlet and the pump casing is too large, so that the water in the high pressure zone of the pump flows to the low pressure zone through the gap, which affects the water output of the pump and reduces the efficiency! Too small a gap will cause friction between the impeller and the pump casing. In order to increase the backflow resistance and reduce the internal leakage, and delay the service life of the impeller and the pump casing, a sealing ring is arranged at the joint of the inner edge of the pump casing and the external aid of the impeller, and the gap of the sealing is preferably maintained between 0.25 and 1.10 mm.
6. The stuffing box is mainly composed of packing, water sealing ring, packing tube, packing gland and water sealing tube. The function of the stuffing box is mainly to close the gap between the pump casing and the pump shaft, so that the water flow in the pump does not flow to the outside and the outside air does not enter the pump. Always keep the vacuum inside the pump! When the pump shaft and the packing friction generate heat, the water seals the water to the water seal ring to cool the packing! Keep the pump running properly. Therefore, it is especially important to check the stuffing box during the running inspection of the pump! The packing should be replaced after about 600 hours of operation.
Second, the self-priming centrifugal pump's overcurrent components
The overflow components of the self-priming centrifugal pump include: a suction chamber, an impeller, and an extrusion chamber. The impeller chamber is the heart of the pump and the core of the flow components. The pump works by the impeller on the liquid to increase its energy. The impeller is divided into three categories according to the direction in which the liquid flows out:
(1) The radial flow impeller (centrifugal impeller) liquid flows out of the impeller in a direction perpendicular to the axis.
(2) The oblique flow impeller (mixed flow impeller) liquid flows out of the impeller in a direction inclined along the axis.
(3) The axial flow impeller liquid flows in a direction parallel to the axis.
The impellers are divided into two categories according to the way of inhalation:
(1) Single suction impeller (ie impeller draws liquid from one side).
(2) Double suction impeller (ie impeller draws liquid from both sides).
The impellers are divided into three categories according to the form of the cover:
(1) Closed impeller.
(2) Open impeller.
(3) Semi-open impeller.
Among them, the closed impeller is widely used, and the aforementioned single suction impeller double suction impeller belongs to this form.
Third, the working principle of self-priming centrifugal pump
The working principle of the self-priming centrifugal pump is that the self-priming centrifugal pump can send the water out due to the centrifugal force. Before the pump is working, the pump body and the inlet pipe must be filled with water to be in a vacuum state. When the impeller rotates rapidly, the blade causes the water to rotate quickly, and the rotating water flies from the impeller under the action of centrifugal force. After the water is thrown, the central portion of the impeller forms a vacuum region. The water of the water source is pressed into the water inlet pipe through the pipe network under the action of atmospheric pressure (or water pressure). This cycle is not enough, you can achieve continuous pumping. It is worth mentioning here that the self-priming centrifugal pump must be filled with water in the pump casing before it can be started. Otherwise, the pump body will be heated, vibrated, and the water output will be reduced, causing damage to the pump (referred to as “cavitationâ€. ") caused equipment accidents!
There are many types of self-priming centrifugal pumps, and the following methods are common in the classification methods. 1 According to the impeller suction method: single-suction self-priming centrifugal pump double-suction self-priming centrifugal pump. 2 according to the number of impellers: single-stage self-priming centrifugal pump
Multi-stage self-priming centrifugal pump. 3 According to the structure of the impeller: open-type impeller self-priming centrifugal pump semi-open impeller self-priming centrifugal pump closed impeller self-priming centrifugal pump. 4 according to the working pressure: low-pressure self-priming centrifugal pump medium-pressure self-priming centrifugal pump high-pressure self-priming centrifugal pump side vertical self-priming centrifugal pump.
Fourth, the following describes several important performance curves of self-priming centrifugal pumps.
The performance parameters of the pump are such as a certain relationship between the flow rate Q head H axis power N speed n efficiency η. The relationship between the magnitude changes between them is represented by a curve, which is called the performance curve of the pump.
The relationship between the performance parameters of the pump and the mutual constraints: First, the top speed of the pump is pre-conditional.
The pump performance curve has three main curves: flow-head curve, flow-power curve, and flow-efficiency curve.
A, flow-lift characteristic curve
It is the basic performance curve of a self-priming centrifugal pump. The self-priming centrifugal pump with a specific speed less than 80 has the characteristics of ascending and descending (both middle convex and curved on both sides), which is called the hump performance curve. A self-priming centrifugal pump with a specific speed between 80 and 150 has a flat performance curve. Self-priming centrifugal pumps with a specific number of revolutions above 150 have a steep drop performance curve. Generally speaking, when the flow rate is small, the lift is high, and as the flow rate increases, the lift gradually decreases.
B, flow-power curve
The shaft power is increased with the flow rate. When the flow rate Q=0, the corresponding shaft power is not equal to zero, but is a certain value (about 60% of normal operation). This power is mainly consumed by mechanical losses. At this time, the water pump is full of water. If it is operated for a long time, the temperature inside the pump will rise continuously. The pump casing and the bearing will heat up. In severe cases, the pump body may be thermally deformed. We call it “squeaky headâ€. The lift is a large value for zui. When the outlet valve is gradually opened, the flow rate will gradually increase and the shaft power will increase slowly.
C, flow-efficiency curve
Its curve is like a hill shape. When the flow rate is zero, the efficiency is also equal to zero. As the flow rate increases, the efficiency gradually increases. However, after increasing to a certain value, the efficiency decreases. The efficiency has a high value of zui. Near the high efficiency point, the efficiency is relatively high, and this area is called the high efficiency zone.
5. Reasonable allocation, safe operation and high quality water supply
The above four aspects understand the self-priming centrifugal pump construction, working principle, characteristic curve, how to properly configure the power of the motor water pump, is the key to ensure the safe operation of the pump, high-quality water supply, reduce production costs, rationally configure the pump power, play the water pump The safe operation of the zuijia work area, the actual situation of the water supply of our factory, has already explained the importance, reliability and economy of the rational allocation of equipment.
1. The importance of reasonable configuration of pump equipment. The main task of the water plant is to ensure the production and domestic water consumption of the people of the city. The southern factory has a large water supply of 900,000 tons. The water intake and water output can meet the regional pressure, but in the past ten years, with the municipal relocation, water With the migration of large households, the amount of water supply is decreasing day by day. With the improvement of people's quality of life, the demand for water quality is getting higher and higher, and the factory water reaches 0.3 NTU.
How to ensure high-quality water supply, the company has taken a series of measures: (a) adjust the reasonable configuration of pump equipment, and implement a combination of human and machine. (b) Increase scientific and technological innovation and invest a large amount of funds to transform the original backward water purification equipment. (C) Investing funds, renovating old equipment, old pipe networks, improving hydraulic conditions, and installing static mixers. (D) Install forty instruments and use modern monitoring systems to monitor and control the whole process of water quality to ensure high quality water. These measures fully demonstrate the importance of proper configuration of pump equipment and water purification equipment.
2. The reliability of the safe operation of the pump equipment. In order to ensure the safe operation of the pump equipment, the company has more standardized management of the pump equipment, annual overhaul, monthly secondary maintenance, once-a-day primary maintenance system, these ISO9002 quality management, is guaranteed pump equipment In order to ensure the reliability of safe operation, the training and improvement of the technical quality of the operators and the implementation of the safety operation procedures must be strictly implemented. The implementation of these safety operation systems is to ensure the reliability of the operation of the pump equipment. Guarantee.
3. Economical operation of safe operation of pump equipment. When it comes to economics, it is the cost of water production, including electricity, antimony, chlorine, and ammonia. It is necessary to use zui's safe operation mode, zui's low dispatching mode, and low water cost to control the economic activities of enterprises. Economic benefits, the company has accumulated a certain amount of experience in this regard. Such as: zui safe operation mode, Shanghai's urban water supply pipe network is interoperable, there is a company center dispatching room to control the water supply pressure in the area, too high is likely to cause bursting, causing property losses to the people and the country, the water pressure is too low, Affect the water consumption of some users, resulting in a bad image of the company. Therefore, the pressure in the area during the day is around 30-35 kPa, and the pressure in the night area is kept below 30 kPa. According to the requirements of pipe network pressure, the high lift pump is opened during the day, and the combination of high and low lift at night is used to effectively control the water pressure of the factory and ensure the water supply of the regional pipe network and the high-rise of the hotel. It not only saves electricity but also controls the pressure reasonably. These methods ensure the economical operation of the pump equipment.
With the continuous development of technology, the modernization of pumps has also been continuously improved, reducing many artificial management operations. Most of them now use the automatic operation mode of computer monitoring, which puts higher requirements on the operator's own quality. Because the abnormal condition of a water pump will affect the network of the entire water supply system, causing serious consequences. After several years of practical work and theoretical study, the knowledge learned is applied to the practical work, and the allocation and scheduling of water quantity are arranged reasonably. The characteristics of each pump are used to achieve the large water output of the pump using less power. , reached zui good running status. And to achieve safety, quality, low consumption water!
Rongcheng Jingyi Oceanic Technology Company Limited , https://www.jingyifoods.cn