Multiple Fans System

[luisss749]

Hi I'm working on a industrial exhaust ventilation system, the system consists of 4 branches that meet at a single point at the entrance of a dust collector, the operation of each one of these branchs can be combined at the end we can get 6 stages of work, after the dust collector we have a pipeline to the suction fan and a duct at the fan outlet.
The idea to separate all stages branches and merge them into a single point in the dust collector is analyze whether you can select a system fan or fans able to provide the flow and pressure required for each stage at any given time and get energy savings.

Air requirements for each stage are as follows:
Q = CFMs, SPfan = inWg
1. Q = 16950, SPfan = 10,390
2. Q = 2800, SPfan = 9,675
3. Q = 2800, SPfan = 9,786
4. Q = 2800, SPfan = 10,309
5. Q = 8550, SPfan = 8.220
6. Q = 11350, SPfan = 10,309

Using centriware 2.0 (flakt woods) i get the following fans for each stage:
P=Kw, n=rpm, eff.=%
1.- GTHB-3-090, P=26.43, n=1422, eff=80.1
2.- GTHB-3-040, P=4.22, n=3102, eff=77
3.- GTHB-3-040, P=4.28, n=3117, eff=76.9
4.- GTHB-3-040, P=4.54, n=3188, eff=76.2
5.- GTHB-3-063, P=10.27, n=1857, eff=83.8
6.- GTHB-3-071, P=17.06, n=1819, eff=83.6

As you can imagine i can't work with bigger fan with VF (surge problems), so i belive the solution is in using multiple fans array
I wonder, in your experience is this technically and economically feasible?
is this a common solution for industrial exhaust ventilation system?
wich iterature can you recommend to select/design (if feasible) a system with multiple fans? (Preferably with examples)

 

[lilliput1]

You can use multiple fans but to operate in parallel, each fan has to be similar and be controlled at same speed and number of fans operating need to be controlled to match load requirement. You would need to add a recirculation damper control or intake air bypass to make sure the last operating fan do not operate in the surge region. Consider adding a spare fan. Provide automatic shutoff damper with time delay at each fan inlet to allow servicing of fan turned off.

 

[kbaumhov]

If the dust you're collecting is combustible, a fan in the dust laden airstream should be spark proof. You may also restrict yourself to a radial bladed fan wheel to keep the blades from caking (depending on dust). If the fan is on the clean air side, you can use a more efficient wheel style.

 

[trashcanman]

This is a network problem with parallel fans. I would find a publication or book on how to solve such problems. I don't think EPANET will help because it is only for water.

 

[willard3]

Buffalo Forge "Fan Engineering" covers the operation and control of fans in parallel.