Backfill solenoid valves are used in the filtration systems of dust collectors, gas turbines and desulfurization equipment. They are commonly used to clean filters such as cartridge filters, envelope filters, ceramic filters, and crushed metal fiber filters. Here, we discuss how these valves work in a typical application for dust collection systems.
Overview of dust collectors
Dust collectors are systems used to remove solid granular contaminants or to recover valuable solids or powders from exhaust gases before being discharged into the atmosphere. The dust collector usually consists of a blower, a dust filter, a filter cleaning system and a dust removal system. One of the most efficient and cost-effective dust collectors available is the cloth collector, commonly known as a baghouse.
In a bag house, gas full of particles passes through cloth bags and deposits dust on the outer surface of the bag (Figure below). The bags are constantly cleaned to ensure that the bag house pressure resistance is within a predetermined range and to ensure that the dust collection efficiency is adequate. The most common method of cleaning is called a jet pulse or jet pressure filter.
In this method, the dust is removed by a high-pressure explosion of air that enters the upper part of the tube bag filter, see Figures 1 and 2.) which in turn feeds the nozzles at the top of each bag. Slowly (1). This creates a shock wave that passes through the bag, causing the bag to expand and crush the dust cake that has accumulated in the bag. Although this compressed air pulse temporarily stops the flow of air through the filter tube bag, it does not interfere with the flow of charge particles inside the baghouse due to its rapid release. Therefore, Jet Pulse house cleaners can work continuously. The shock wave travels down the tubular filter bag in about half a second. Therefore, the pulsating air must be strong enough to travel the entire length of the bag and break the dust cake. Using the solenoid filter solenoid valve (2), the dust collector valve (2) can be opened and closed quickly. The use of a back filter solenoid valve allows the control of pressure drop through the filter as well as the pulse sequence.
Principles of operation, principles of surgery, principles of operation
Backfill solenoid valves are solenoid valves designed specifically for dust collection systems. When the solenoid valve is activated, the air trapped above the diaphragm is quickly evacuated, causing a large pressure difference in the diaphragm. This opens the diaphragm suddenly. When the solenoid valve is energized, air exits through a hole in the upper chamber of the diaphragm, which balances the pressure and closes the valve immediately.
Rapid opening and closing of the valve is very important for effective cleaning of filters and economical consumption of compressed air. This is possible by keeping the weight of moving parts small and thus having a small inertia. These valves have very high kV values. When the air velocity becomes audible (344 m / s) it reaches the maximum flow velocity.
The main parameters in the selection of the back filter solenoid valve
Tank volume : The amount of air stored in the power supply tank, which in turn depends on the size of the valve.
Tank pressure : The air pressure in the tank, which is also the inlet pressure of the valve.
Maximum allowable pressure : Maximum line or system pressure for safe operation.
Electric pulse length : When the valve is activated.
Total pulse length : the time between opening and closing the valve.
Peak pressure : The maximum pressure reached at the end of the blower pipe that generates the shock wave.
Pressure drop tank : The difference in tank pressure before and after the shock wave. To maintain the sound flow in the impact pipes, it is necessary to limit the pressure drop to a maximum of 50% of the absolute pressure of the tank. If installed, the easiest way to reduce the pulse time is if the pressure drop is too high.
Performance ratio : The ratio of tank pressure and peak pressure in percentage. The value of this parameter depends on the valve kV and the opening time.
Volume per pulse : The volume of air at atmospheric pressure passing through the valve per pulse. The higher this parameter, the better the filter bags are cleaned and the more bags can be cleaned in each valve.
These types of solenoid valves are offered with a different selection of structural materials from the body and sealing materials. All building materials have special properties that make them suitable for different applications. Choosing the right body and sealing material for your media is essential.
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