Three screw pump precautions

Three screw pump precautions

Three screw pump precautions

First, the speed of the three screw pump is selected

The flow rate of the three-screw pump is linear with the speed. Compared with the low-speed screw pump, the high-speed screw pump can increase the flow rate and lift, but the power is obviously increased. The high speed accelerates the wear between the rotor and the stator. The screw pump is prematurely disabled, and the high-speed screw pump has a short stator length and is extremely wearable, thereby shortening the service life of the screw pump.

The speed is reduced by the reducer or the stepless speed regulation mechanism, so that the surveying speed is kept within a reasonable range of less than three hundred revolutions per minute, and the service life can be extended several times compared with the high speed running screw pump.

Second, the quality of the screw pump

At present, there are many kinds of screw pumps on the market. Relatively speaking, the imported screw pump has reasonable design and excellent materials, but the price is high, the service is not in place, the price of accessories is high, and the order period is long, which may affect the normal production. run.

Most of the domestically produced products are imitation imported products, and the quality of the products is mixed. When selecting domestically produced products, when considering the cost performance, the products with low speed, long lead, good transmission parts and long service life are selected.

Third, to ensure that debris does not enter the pump body

The solid impurities mixed in the wet sludge will cause damage to the rubber material stator of the screw pump, so it is very important to ensure that the debris does not enter the pump cavity. Many sewage plants install the pulverizer in front of the pump, and some installations are also installed. The grille device or the filter screen blocks the debris from entering the screw pump, and the grille should be cleaned in time to avoid blockage.

Fourth, maintain a constant export pressure

The screw pump is a positive displacement rotary pump. When the outlet end is blocked, the pressure will gradually increase, so that the predetermined pressure value is exceeded. At this time, the motor load increases sharply. The load of the transmission machinery related parts will exceed the design value. When the motor burns out, the transmission parts break. In order to avoid damage to the screw pump, a bypass relief valve is usually installed at the outlet of the three-screw pump to stabilize the outlet pressure and keep the pump running normally.

Five, avoid breaking materials

The three-screw pump is never allowed to operate under the condition of breaking the material. Once it happens, the rubber stator burns due to dry friction and instantaneously generates high temperature. Therefore, the pulverizer is intact and the grille is unblocked, which is one of the necessary conditions for the normal operation of the screw pump. To this end, some screw pumps also have a shut-off device installed on the pump body. When the material is broken, due to the self-priming function of the screw pump, a vacuum will be generated in the cavity, and the vacuum device will stop the screw pump.

The three-screw pump is formed by the pump body and the screw. When the driving screw rotates, the driven screw that meshes with it is rotated together, and the screw meshing space volume at one end of the suction chamber is gradually increased, and the pressure is lowered. The liquid enters the volume of the meshing space under the pressure difference. When the volume is increased to a maximum to form a sealed chamber, the liquid is continuously moved axially within the sealed chambers until one end of the chamber. At this time, the screw meshing space volume at one end of the discharge chamber is gradually reduced, and the liquid is discharged. The working principle of the three-screw pump is similar to that of a gear pump, except that the gear is replaced by a screw in the structure. The table shows the characteristics and application range of various screw pumps. The three-screw pump has small flow and pressure pulses, low noise and vibration, and self-priming capability, but screw processing is difficult. The pump has a single suction type and a double suction type, but the single screw pump has only a single suction type. The three-screw pump must be equipped with a safety valve (the single-screw pump does not have to be equipped with a belt) to prevent the pump or prime mover from being damaged due to some reason such as the discharge pipe being blocked and the pump outlet pressure exceeding the allowable value.

The three screw pump is a screw type positive displacement pump. In the three-screw pump, since the main screw and the spiral groove on the driven screw are engaged with each other and they cooperate with the inner surface of the three holes of the bushing, a plurality of dynamic sealing chambers are formed between the inlet and the outlet of the pump, and these dynamic seals are formed. The chamber will continuously move the liquid axially from the pump inlet to the pump outlet and boost the delivered liquid step by step. Thereby forming a continuous, smooth, axially moving pressure liquid. The liquid conveyed by the three-screw pump is a lubricating liquid containing no solid particles, no corrosive oil and similar oil, and the viscosity is 1.2~100oE (3.0~760cst). The high viscosity liquid can also be transported by heating and viscosity reduction, and the temperature thereof. Not more than 150oC.

1. Simple structure: The three-screw pump itself consists of only three screws, but it has various structures. Generally, the small flow rate, the pump body and the bushing of the 0.2-6.5m3/h pump are combined into one horizontal installation, and the shaft seal is mechanically sealed. . The pump bushing above the medium flow is fixed in the pump body as a separate part. The large flow pump is mostly made into a double suction structure. The shaft has two types of end mechanical seals and packing seals depending on the medium to be transported. The prime mover of the marine pump is an AC marine motor. 2. Long service life: The main screw of the three-screw pump is driven by an electric motor. There is a layer of oil film protection between the main and slave screws and between the screw and the bushing. Because the mechanical friction of the pump is extremely small, the service life is semi-permanent. 3. The liquid to be pumped in the pump is linearly and linearly moved at a constant speed, so the pressure pulsation is small, the flow rate is stable, and the noise is low. Since the inertia of the rotating part is small, the starting torque and vibration are small. 4. It has high inhalation capacity. 5. In order to ensure the safety of the pump, motor and pipeline system, the screw pump above medium flow has safety valve. When the pressure exceeds the set pressure of the safety valve, the high pressure oil will return to the inlet of the pump.

Gear pumps are divided into external gear pumps and internal gear pumps

Gear pumps are divided into external gear pumps and internal gear pumps.

The two gears of the internal gear oil pump have different shapes and different numbers of teeth. One of them is a ring gear, which can float in the pump body, and the middle one is the driving gear, which is eccentric with the pump body. The number of annular teeth is one tooth more than the driving gear, and the driving gear drives the ring gear to rotate together, and uses the change of the space between the two teeth to transport the liquid. Another internal gear pump is a ring gear

More than two teeth than the driving gear, a fixed crescent-shaped partition is placed between the two gears to clearly separate the suction and discharge space. In the case where the discharge pressure and flow rate are the same, the internal gear pump has a smaller outer shape than the external gear pump. What are the working principles and characteristics of the gear oil pump? The gear pump is a type of positive displacement rotary pump. The working principle is: the gear pump has a pair of intermeshing gears, the gear (drive wheel) is fixed on the drive shaft, and the shaft end of the gear pump protrudes out of the shell by the prime mover. Drive, the other gear (driven wheel) of the gear pump is mounted on the other shaft. When the gear of the gear pump rotates, the liquid enters the suction space along the suction pipe, and is squeezed by the two gears along the upper and lower casing walls to the discharge space. (Before the teeth mesh with the teeth), then enter the pressure tube to drain. The main features of the gear pump are compact structure, small size, light weight and low cost. However, compared with other types of pumps, it has the disadvantages of low efficiency, high vibration, high noise and easy wear.

The gear oil pump is used to transport liquids with high viscosity, such as lubricating oil and combustion oil, it is not suitable to transport liquids with low viscosity (such as water and gasoline), and it is not suitable to transport liquids containing particulate impurities (affecting the service life of the pump). Lubrication system oil pumps and hydraulic system oil pumps are widely used in engines, steam turbines, centrifugal compressors, machine tools and other equipment. Gear pumps have high process requirements and are not easily matched.

Selection of air-cooled hot oil pump unit

At present, the design uses air-cooled hot oil pump hot and cold water unit, often based on the calculated cooling and heating load, considering the simultaneous use coefficient and the cold (heat) loss factor, the number of units is selected according to the unit nameplate calibration value. Since the amount of cold (heat) of the air source hot oil pump unit changes with the change of outdoor parameters, this selection method may cause the unit to be selected too large and cause waste; or the selection is too small to make the cooling (heat) insufficient. , can not meet the requirements of use. For this reason, it is recommended to use the hourly cooling load of the air conditioner and the hourly change curve of the heating and cooling capacity of the hot oil pumping unit, and the satisfactory results will be obtained.

Noise management of hot oil pump unit

Noise control for single or multiple hot oil pump units. The noise propagation characteristics of the air-cooled hot oil pump unit are analyzed. Combined with the noise control engineering example of the hot oil pump unit, the design method, design points and treatment effects of the closed sound insulation muffler are introduced. Because of the operation, management and maintenance of the air-cooled hot oil pump, it has the dual functions of cooling and heating, and the heat dissipation of the unit does not require a cooling tower. Therefore, more and more applications are applied. However, the noise of the hot oil pump unit is likely to have a certain impact on the surrounding environment. In recent years, there have been more incidents of noise from the hot oil pump in Shanghai and other places, which has become a common type of fixed source noise pollution problem in cities in the near future. Therefore, understanding the noise propagation characteristics of single or multiple hot oil pumps and discussing the methods of noise prevention and control of hot oil pump units has certain universal practical significance.
From the noise source of the hot oil pump unit, the noise characteristics, the noise control example of the hot oil pump unit, the noise control and the technical control of the technology, the noise control project example of the hot oil pump unit has certain promotion value and significance, and the heat is well solved. Under the premise of ventilation, heat dissipation, air inlet and exhaust, and ensuring the normal operation of the hot oil pump, a fully enclosed sound insulation muffler is used to reduce the A sound level noise of the hot oil pump by about 20 dB, so that the hot oil pump is used in some special occasions. The noise reduction engineering design that reduces the noise to the required level provides a successful example that can be used for reference, especially in the design of the sound insulation muffler when the exhaust air pressure of the hot oil pump is low or the specific residual pressure is not known. There can be a specific calculation basis for the wind exhaust system.

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