Method of exhaust and water filling of centrifugal pump

 

The centrifugal pump will carry out the actual operation of exhaust and water filling when starting and running, and that can make the machine and equipment run better. So I will explain the water filling and exhaust methods of the machine and equipment to you next. Let's have a look.
Because the centrifugal pump generates vacuum pump after the pressure in the pump is pumped out by the centrifugal impeller, so in addition to the centrifugal pump and the self-priming pump with the centrifugal impeller immersed in water, water must be filled into the pump before each pump start, which is also known as the diversion channel. There are two ways to fill water: one is to fill water into the pump immediately (at this time, the air outlet should be opened to drain the gas in the pump); The second is to extract the steam from the pump, create a certain vacuum value (at this time, close the water outlet stop valve), and introduce water resources.
1. Install gate valves at the inlet and outlet to fill water. In this way, a gate valve is installed at the water inlet, and water can be filled into the pump after connecting the water pipe.
2. Fill with water by hand pump. Some water pumps are equipped with built-in hand pumps, and small and medium-sized hand pumps can also be purchased or made by ourselves. The stop valve must be installed on the inlet pipe. After the gate valve is closed tightly, fill the water press with a small amount of water to develop the diversion channel. After the water output of the hand pump, it indicates that the water pump has been filled with water and can be started.
3. Use vacuum technology to exhaust and fill water. The self-exhaust of centrifugal pump is the same as the negative pressure exhaust of mechanical pump, so the water-ring mechanical pump exhaust is used to fill the water channel.
Therefore, when the centrifugal pump cannot carry out the actual operation of exhaust and water filling normally, it must be repaired immediately to prevent endangering all normal applications of the machinery and equipment, or it will continue to cause a certain level of damage to the machinery and equipment.

How to select a vacuum pump?

The centrifugal pump manufacturer tells you the difference between

The centrifugal pump manufacturer pointed out that in order to better discharge the gas in the moisture absorption pipe and generate a certain vacuum value when the centrifugal pump is working, the exhaust pipe must be used. For small pumps, the pump casing and water inlet must be filled with water before operation. In order to better avoid the jump of water injection, the bottom end of the water inlet is equipped with a unilateral pump bottom valve that opens when the water flows upward and closes when it flows downward; Generally, large centrifugal pumps with water seepage specifications above 300 mm are not equipped with bottom valve of water pump, but only use professional vacuum equipment to vacuum drinking water. There is no doubt that the operation of the feed pump will cause inconvenience, resulting in waste.
Principle: Centrifugal pump works by using impeller rotation and then water to produce centrifugal movement. Before running the pump, make sure that the pump casing and the moisture absorption pipe are filled with water. Then run the motor to make the pump shaft push the impeller and water for high-speed running fitness exercise. The water will produce centrifugal movement and be thrown to the edge of the impeller. The water will be injected into the compressed water pipeline of the pump through the flow passage of the volute pump casing.
Structure: Centrifugal pump works by using impeller rotation and centrifugal movement of water. The manufacturer of centrifugal pump pointed out that the basic structure of centrifugal pump is composed of six parts, namely, impeller, pump housing, pump shaft, rolling bearing, sealing ring and ferrule joint.
Centrifugal pump manufacturer
The centrifugal pump manufacturer said that the structural type of the self-priming centrifugal pump has been improved, and it has got rid of the insufficiency of the general pipeline centrifugal pump. The characteristic of self-priming centrifugal pump is that the pump shell is double volute structure. The detergent port is located on the edge of the pump impeller, and there is a large capacity vapor liquid separation chamber on the liquid outlet. Other structures are similar to single pole single suction centrifugal pumps, including sealing rings, mechanical seals, shafts and rolling bearings. When the self-priming pump is in operation for the first time, the water diversion channel must be introduced into the pump casing, and the introduction amount can exceed the pump centerline in the pump casing. After that, the fully automatic suction pipe can be operated at any time and anywhere without introducing the diversion canal, so the application is more convenient than the pipeline centrifugal pump.
Principle: The principle of self-priming pump is to fill the pump casing with water (or there is water in the pump casing itself) before the pump runs. After running, the impeller runs at a high speed to make the water in the impeller channel flow to the volute. At this time, the channel generates a vacuum pump to open the seepage check valve. The gas in the suction pipe enters the pump and reaches the edge through the impeller channel.
Structure: Self priming centrifugal pump is a kind of centrifugal pump, but it is different from centrifugal pump in that it has "self priming" characteristics. The basic structure of the self-priming pump is composed of a suction chamber, a liquid storage chamber, a scroll chamber, a liquid collecting hole, a vapor liquid separation chamber, etc.

 

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Advantages and disadvantages of magnetic pump

 

Advantages of magnetic pump:
1. Since the drive shaft of the magnetic pump does not need to penetrate the pump casing, but uses the magnetic field to drive the inner magnetic rotor through the magnetic field and the thin-walled transmission torque of the isolation sleeve, thus fundamentally eliminating the leakage channel of the shaft seal and achieving complete sealing.
2. The magnetic pump has overload protection when transmitting power.
3. The magnetic material and magnetic circuit design of the magnetic pump have high requirements, while the other parts have low technical requirements.
4. The maintenance and overhaul workload of magnetic pump is small.
Disadvantages of magnetic pump:
1. The efficiency of the magnetic pump is lower than that of the ordinary centrifugal pump, and it cannot operate at 30% of the lower rated flow, and it is more forbidden to idle.
2. Due to the poor wear resistance of the isolation sleeve material of the magnetic pump, the magnetic pump is generally used to transport the medium without solid particles and the magnetic particle material is forbidden to enter the pump.
3. The magnetic pump with general structure is allowed to transport the liquid containing solid particles with diameter less than 0.15mm (100 mesh) and mass fraction less than 5% (auxiliary system shall be added when exceeding).
4. The pump and motor are connected by a coupling. The coupling requires a high accuracy for the installation of the center line. Improper alignment will lead to the damage of the bearing at the inlet and the wear of the isolation sleeve against unilateral side leakage.
5. The magnetic drive of the magnetic pump has two modes: synchronous drive and asynchronous drive. The inner and outer magnetic rotors of the synchronous drive are equipped with permanent magnets, so the temperature of the liquid transported must be lower than the allowable temperature of the permanent magnet. A certain margin must be reserved. Although cobalt and samarium permanent magnets can reach 350 degrees Celsius, the actual use temperature generally does not exceed 260 degrees Celsius. High temperature on the other side may cause permanent magnet loss of magnetism. The magnetic pump with special structure can reach 450 degrees Celsius.
6. The magnetic pump has high requirements for the material and manufacturing process of the isolation sleeve. If the material is not selected properly or the manufacturing quality is poor, the isolation sleeve cannot withstand the wear of the inner and outer magnetic rotors, resulting in wear. Once it breaks, the medium conveyed will overflow, causing equipment failure and affecting the normal operation of the device.
7. When the temperature of the medium conveyed by the magnetic pump exceeds the specified value, it is necessary to provide cooling outside. For example, the heat insulation chamber is set, the pump chamber is filled with coolant with a pressure higher than the sealing pressure, and the inner magnetic rotor and bearing are cooled. The isolation sleeve with a interlayer can also be used. The interlayer is filled with coolant, or the pump body is equipped with a cooling jacket and a cooling coil. The single structure is complex and the cost is high.

Let your vacuum equipment work healthily and happily

What is molten salt submerged pump

RY-type molten salt pump is a single-stage, single-suction cantilever submerged pump, which is suitable for conveying molten salt (KNO3 53%, Na2NO240%, NaNO37%) with high temperature (temperature ≤ 600 ℃), for industrial departments such as ionic membrane caustic soda, alumina, etc., and also for conveying liquid with other high-temperature special media. RY-type molten salt pump is a series of molten salt pump products independently developed on the basis of years of production of high-temperature submerged pump and molten salt submerged pump, referring to the structure of similar foreign products. It is a special high-temperature pump for molten salt circulation system or molten salt transportation.
The structure of molten salt pump mainly consists of power system, transmission system and conveying system. The power system mainly includes motor and motor support. It is the power source of molten salt pump. The transmission system includes the main shaft and bearing bracket, which is responsible for completing the power transmission. The high-speed operation of the motor is converted into the operation of the impeller to generate the power to transport high-temperature molten salt. The conveying system is mainly composed of conveying pipes, which is used to complete the transportation of high-temperature molten salt.
Before determining the type selection of molten salt pump, the composition of molten salt used should be analyzed first. Including the type of molten salt, service temperature, melting point, gasification point, etc. On the whole, the material of the pump should be resistant to high temperature and corrosion, and its strength and service life should be considered. The gas released by molten salt decomposition at high temperature is more corrosive. Taking the common binary molten salt as an example, the operating temperature of the trough molten salt power station and the tower molten salt power station are different. The operating temperature of the trough molten salt heat storage system is between 220 ℃ and 400 ℃. According to this temperature, 304 and 316 stainless steel can be selected as the material of the molten salt pump; For tower type molten salt power station, the working temperature of molten salt is between 220 ℃ and 550 ℃, and 316, 347 stainless steel or 718 chromium-nickel alloy steel that is more resistant to high temperature and corrosion is required.
The high-speed flow of molten salt will also cause rapid corrosion of the impeller blades of the molten salt pump. The corrosion damage rate is proportional to the medium flow rate. The higher the flow rate, the faster the corrosion rate. Therefore, the flow rate of molten salt should be properly controlled within the safe range.

Take you to understand the use of vacuum pump filter