Dust sucker

[Steelforbrains]

My company has been asked to quote building some portable dust collectors, which we have never made. The customer wants us to quote providing the frame and tank. They are providing the blower. These are the specs that they would like to have:

1300 CFM
5 HP blower
24" diameter tank to house 3 "bags" mounted vertically approximately 60" tall
Two 4" intakes
One 6" output (to go to the blower)
Removable top and bottom semi-elliptical covers
All 304 SS construction

I am trying to determine the required thickness of the tank walls. I tried using the formula from Roark's for a cylinder under external pressure. I do not know what pressure differential to use. If I use 15 psi for a "full vacuum" I determine that I need 5/16" plate. This seems rather thick compared to similar units that I have seen.

How can I determine the theoretical pressure inside of the tank?

How do I size the Semi-elliptical end covers?

 

[gr2vessels]

I am using phosphorus from fish and it helps, see below.

A suggestion for the design pressure would be the differential pressure for the rupture of the clogged/blocked fiter bag. Perhaps add 10% more pressure for contingency (note, the mentioned differential pressure will be the design external pressure, most likely much less than 15 psi).
Also, if you set-up a vacuum breaker valve upstream the filter, you can use that set pressure as design external pressure for your filter housing. If you can limit the suction pressure to the blower (you should protect the blower anyway), you can also use that set pressure as design external pressure.
cheers,
gr2vessels

 

[Steelforbrains]

Thank you gr2vessels. Is there any way that I can determine the vacuum pressure based on the theoretical CFM's and HP of the blower? I pulled out my old fluid mechanics books but they were a little too dusty to read.

 

[gr2vessels]

The suction pressure of the blower is a particular equipment property and usually is limited by the manufacturer. In your application, the actual suction vacuum could go down to say 500-600 mbara, but I suspect that your bags will "crack" at less vacuum than that. As a conservative design I suggest you to use 50-55 kpag external design pressure (or 7.5-8.0 psi external pressure). By the way, how are you going to protect the blower from sucking in all the collected dust in case of bag rupture?
cheers,
gr2vessels

 

[pmover]

steelforbrains,

will the type of blower being planned for this installation be a consideration (i.e. positive displacement or centrifugal)?

if centrifugal, i suspect there MAY be a need of continuous flow through the blower; hence, limiting the inlet pressure. IF positive displacement, then inlet pressure to blower could be very low.

These conditions imply that that blower is downstream of pressure vessel. with the blower information (including performance curves), then you ought to be able to determine a differential pressure for your design.

perhaps a query to the blower mfg/client would be helpful.

good luck!
-pmover