Steam Powered Rotary Cooker

Positive Solution

Hello Dan,



I have a job that we are practically designing from scratch. We have some questions that I hope you can answer. Any help is appreciated.



I have a customer that has a commercial steam powered rotary cooker. It needs to be supplied with 400 lbs/hr of steam at a pressure of 10 - 12 PSI. The cooker has already been installed at ground level.  (Digging a pit is not an option here.) We would have to run a riser up about 20 feet to the ceiling, across about 100 feet and DOWN 20 feet to the cooker. After the cooker would be a trap, condensate tank and check valve. The owner does not want to dig up his floor or run pipe along his floor so he wants us to run the return lines next to the supply main. So we would have to bring the return lines UP 20 feet to the ceiling, across 100 feet and back down to the boiler return tapping.



Using the charts supplied in the Art of Steam Heating book, I can figure out the pressure drop. That's where the questions begin:

1) Can I supply steam to a unit that is below the normal water line?

2) I know I can run steam vertically and horizontally but can I pipe so that the steam runs downward?

3) Can I bring the return lines up to the ceiling? and would the condensate tank be able to pump the condensate up to the ceiling and back to the boiler?

4) Where should I install the main vent? I was thinking directly after the cooker so that the steam rushes to the cooker.

5) Would we need a F & T trap or regular steam trap.

6) Is it okay to operate a 15 lb maximum low pressure boiler with an operating pressure control set at Cut-In 9 lbs and Cut-Out 11 lbs.

7) What boiler should I select? How do you convert pounds per hour into BTU?

8) How much should we pitch the steam main measured in inch per feet?



I attached a picture of the unit.



Again, any help is greatly appreciated.



Vincent

NY Heating

Jamie Hall

You probably

should be talking to a registered mechanical engineer -- but they are expensive, and, sadly, they don't always know what they're doing.



Given that, I'll answer what I can...



1.  Yes, no problem.  The traps will take care of that.



2.  Steam doesn't know anything about down and up and horizontal.  All it knows is high pressure to low pressure.



3.  Yes.  However, this is where it gets a little funky: you could, in principle, depend on a syphon or an ejector.  However, they are unreliable.  This is an ideal application for a condensate return pump -- a contraption which I otherwise avoid like the plague.



4.  As noted in 3, you are best off with a condensate return pump.  The receiver for which is vented to the atmosphere anyway; you might, however, want another main vent just before the cooker, set back a bit from where the main turns down.



5.  This one, I'm going to dodge the issue.  I would say an F&T, but I'm just a bit out of my depth on it.



6.  As far as I know, yes.  In fact, I've seen, sadly, residential boilers set to those pressures...



7.  Another out of my field.



8.  I would be inclined to pitch the main pretty much same as any other main -- see LAOSH.

jpf321

install manual?

didn't the cooker come with an install/piping diagram like a boiler does? are you piping according to their specs?



i'm not sure if it helps at all .. but I did find this once .. a diagram for steaming crabs.  http://www.comfort-calc.net/Crabs/Crab%20Boiler%20Piping.JPG

Positive Solution

No literature

Unfortunately, there is no manual or rating plate. All I know is that I need 400 lbs/hr at 10 PSI and that is according to the owner of the building.

jpf321

#7 ... units wizard here

I can't vouch for it's correctness (and they have obfuscated the Javascript) .. however .. http://wea-inc.com/wiz-cond.htm



Enter 400 in the lb/hr box for 10psig and hit calculate ..



I just happened to find this one yesterday ;-)

jpf321

crab steamer again ...

I wanted to drawyour attention to the original Crab Steamer web page since it has more notes that the drawing .. the most striking note in your case is that condensate should be sent to drain if you aren't using boilers for heating pruposes .. i'm not sure if that's health dept code, buildings, common sense .. but he states it plain as day in 2nd paragraph. http://www.comfort-calc.net/Crab_Steaming.html .. he also points out that b/c you need a whole lotta freshwater, you should pretreat your water before it enters the boilers.

REX

columbia high pressure boiler

Columbia high pressur boilers,used in drycleaner plant.....a lot of flow,you can reduce pressure as needed by pressure reducer to your equipment.