Re: Air Flow Vs. Pressure?
If you can set up your system to maintain a fairly constant pressure level, a centrifugal blower will change airflows while keeping a fairly constant pressure level. If I understand your system, you can isolate the line that runs empty by a valve of some type. A multi-stage centrifugal blower (www.gardnerdenver.com) such as a Lamson or Hoffman unit will change airflows. These are not a common blower type of pneumatic conveying, but they can be used if designed properly. Hope this helps. ■
Re: Air Flow Vs. Pressure?
I think what you need is a control system to maintain equal flow in the three lines. For this, I would suggest you use Laval nozzles in each of the lines from the Air Receiver and use a pressure control valve and a vent valve on the Air Receiver. Since the air mover is supplying constant air flow, any excess air flow will be vented while maintaining constant air flows to the other 2 lines.
Regards,
Amrit Agarwal
Consultant
polypcc@aol.com
Pneumatic Conveying Services LLC
Ph and Fax: 304 346 5125 ■
Re: Air Flow Vs. Pressure?
Dear Sir, you can use Laval nozzles in each of the three lines. Laval nozzles ensure a constant flow not depending on the pressure in the system behind the nozzles. The nozzles have strictly defined inner form and each nozzle is calculated and designed for the pressure in front of it and for needed air flow. If you need two or more different air flows in each line you can use the airflow control system with Laval nozzles developed and designed by our company for pneumatic conveying systems.
Best regards
Petr Rayman
RAYMAN Ltd.
Ocelarenska 1781
272 01 Kladno
Czech Republic
E-mail: petr.rayman@rayman.cz ■
Re: Air Flow Vs. Pressure?
This can be done with the use of 3 Laval nozzles. This will give an equal split with up to 80% downstream usable pressure. The pressure downstream on each line will not effect the split.
B Snowdon ■
Re: Air Flow Vs. Pressure?
The Laval nozzles give out a constant gas flow. This often results in wide pressure pulsations depending upon line layout and feed rate. These pulsations can result in excessive pipeline vibrations. To prevent these problems, use pressure control valves at the Laval nozzles inlet and interlock them with the discharge pressure transmittors so that the inlet pressure to the Laval nozzles is automatically changed to maintain pressure pulsations within an acceptable range.
Regards.
A. T. Agarwal
Consultant
Pneumatic Conveying Technologies
polypcc@aol.com
Ph and Fax: 304 346 5125 ■
Air Flow vs. Pressure?
Hi,
I have an application which involves a single compressor delivering a given volume of air at 2bar (say volume = "y" m/min). The air is delivered to an Air Receiver and I want to extract the air (split equally 3 ways, i.e. 1/3"y" m/min) to three different destinations for the purposes of pneumatic conveying of solids.
At some point, one of the three lines will discharge before the others, resulting in a low pressure and a 'rush' of air to that point, thereby starving the other two of air. I therefore require some sort of control valve to ensure this rush of air is limited and does not allow the other two to be starved of air.
Does anyone know of some sort of 'flow-control' device that can be utilised that is not adversely affected by variations in pressure drop? I understand that the complicating factor here is that the flow will increase automatically as one of the lines starts to empty, i.e. a pressure drop begins to occur.
Any assistance will be greatly appreciated! ■