Seeking advice on issues such as the selection of exhaust gas collection exhaust fans.
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Seeking help: The exhaust gases from various workshops in our facility converge into a main pipe located in a ductwork system. It is planned to install an exhaust fan at the end of this main pipe, with the exhaust from the fan being directed to the boiler for combustion. 1. The diameter of the main pipe is DN250, with a length of approximately 350 meters. The diameter of the branch pipes in each workshop is DN100. There are around 15 DN250 elbows and around 18 DN100 elbows. 2. How should the outlet air pressure of the exhaust fan be selected? Should the resistance caused by the 350-meter straight pipe length and the fittings at the fan inlet be overcome? For example, if the resistance is calculated to be 18 KPa, is it okay to choose a wind pressure of 25 KPa at the outlet of the exhaust fan? 3. After discussion, a conventional centrifugal exhaust fan was selected; it has an air volume of 4000 m3/h, and its maximum air pressure is only 4 KPa, which is not sufficient to reach 25 KPa. Can the 8-09-8.5D high-pressure blower achieve 17.8 KPa at an air flow rate of 4000 m3/h? The calculated inlet resistance of the fan is approximately 18 KPa; can this fan draw in the gas?
For general-purpose fans, there may not be a suitable machine matching your parameters. You can send a piping layout diagram, and I can help you calculate the pressure loss. The 18 kPa you calculated is the static pressure of the fan; since air is being drawn outwards, the actual static pressure will be higher. When selecting a fan, you shouldn’t focus on its total pressure but rather on its static pressure
It hasn’t been arranged yet; it’s still in the planning stage. Should a fan be used or a water ring compressor? It is under discussion. Do you mean that if the pressure loss in the fan’s inlet pipes and fittings is 18 KPa, then choosing a wind pressure of 25 KPa at the fan’s outlet is too low? Isn’t that enough?
Water ring pump! Don’t joke with me – who gave you this idea? It’s sufficient to use a centrifugal fan. 25 kPa may not be sufficient; you need to first convert it to static pressure, and then take into account the decrease in density at negative pressures (for air, -5 kPa corresponds to 0.75 times the standard density). If the fan’s specification sheet indicates 25 kPa, it might still not be enough, as what is specified there could be the maximum pressure, rather than the pressure and flow rate under actual operating conditions. 25 kPa is quite tight – there isn’t any margin left.
There is no problem with water ring compressors, as they are used to transport flammable and explosive gases. Fans, on the other hand, are not suitable for this purpose, as their impellers can generate static electricity sparks. Moreover, water ring compressors are generally used as the driving mechanism to transport flare gas into the flare for combustion.
There is no problem with water ring compressors, as they are used to transport flammable and explosive gases. Fans, on the other hand, are not suitable for this purpose, as their impellers can generate static electricity sparks. Moreover, water ring compressors are generally used as the driving force for sending flare gas into the flare for combustion.
It’s because the industries involved are different. I mean, there’s no need to use a water ring pump for this vacuum – with a negative pressure of just over twenty thousand pascals, an explosion-proof fan with an FRP casing and metal impellers can be used
Metal impellers are prone to generating static sparks, etc.; since flammable and explosive gases are being transported, using fans poses a risk.