Selection of rotary valve
Rotary valve, also known as discharge valve and star discharge device, is a mechanical device that changes the valve from the open position to the closed position through the rotation of rotating parts such as rotating baffle.
1), butterfly valve: the flow direction is controlled by rotating the baffle or blade around the rotating shaft for a certain angle. Baffles or blades look a bit like butterflies. Butterfly valve can be cut off or adjusted, suitable for slurry or fluid with solid suspension.
2) Ball valve: Its valve core is a sphere with a round hole. When the valve is in the open position, the fluid is allowed to flow, and the ball is rotated 90 degrees to cut off the fluid flow. The ball valve can be cut off and adjusted with small pressure drop, which is suitable for viscous and corrosive fluids and slurry low-temperature fluids. Ball valves can also be used for high temperature and high pressure fluids.
3) Plunger valve: Its valve core is a conical or cylindrical plunger with a round hole in the middle. When the plunger hole is consistent with the flow direction, fluid can pass through, and when the plunger rotates 90 degrees in any direction, the flow path is cut off. Plunger valves are usually used for on/off control.
Working principle of rotary valve:
When the material in the upper silo falls due to its own weight and fills the space of the rotor blades, it rotates with the blades to the lower outlet and is discharged. Can be continuously supplied and discharged. Rotary valve can play the role of conveying and locking airflow in pneumatic conveying system. Due to the low-speed rotation of the rotor and the minimum clearance between the rotor and the inner cavity of the shell, the reverse flow of air is effectively prevented, thus ensuring the stability of air pressure in the system and the normal discharge of materials. Therefore, it is an important part of high-pressure gas conveying materials under the condition of pipe network. The rotary valve is used as the unloader of the material bin in the material collection system.
Characteristics of rotary valve
Cavitation resistance
Throttle will cause a lot of cavitation in the process industry, which may damage the pipeline and produce unacceptable noise level. At the same time, it will also interfere with the metering system, resulting in unclear or unreliable readings. Rotary valve adopts solid design, which greatly reduces the valve action failure caused by water hammer phenomenon, and at the same time, its valve core can absorb some redundant energy, which obviously reduces cavitation and related problems.
No external leakage
The external leakage of standard rotary valve is better than that of standard globe valve 100 times. The movement of the valve stem of the ball valve takes out dust and brings sand into the valve, thus damaging the graphite packing. In the rotary valve, the valve stem does not move in and out, but rotates, which will not hurt the packing and will not leak out. ?
smooth operation
The rotary valve can convey materials uniformly and continuously, with compact structure, stable operation and low noise. Moreover, because the bearing and gearbox are at a certain distance from the shell, the high temperature resistance and lubricity are improved.
To sum up, rotary valve is an indispensable equipment in machinery industry, and the industrial state and working intensity of machinery are controlled by rotary valve. The biggest feature of rotary valve is its wide adjustment range, and the ratio of adjustment range can be as high as 300 100. The accuracy of adjustment is also very strong. Rotary valves can be divided into manual rotary valves, automatic rotary valves and rotary regulating valves. These three kinds are used according to the difficulty of machinery. Generally, automatic rotary valves are used for long mechanical working hours. There are still many simple machines that use manual rotary valves.