Emergency feed water supply

[curtis2004]

Hi everyone,
I'm working on a project to supply 200 HP (~7,000 #/hr steam) wood chips fired 100 psi steam boiler. This is solid fuel boiler and I need to provide emergency water supply in case of power failure, since my 5 HP electric motor driven feed water pupms will be down.
To provide emergency power generator seems to be too expensive in this case (~ $30,000)and I'm considering other means to provide water to boiler in order to protect from overheating. Did anyone dealt with this kind of issue?
Thank you,
Curtis

 

[TBP]

A steam driven feed pump. Reciprocating piston, turbine, injector...

 

[jte]

http://www.northerntool.com/shop/tools/product_200418135_200418135

 

[curtis2004]

Steam turbine driven won't work as a back-up because you need to worm up your turbine first.
Injector seems not reliable and difficult to control in order not flood whole steam supply piping system.
Engine driven seems good. Do you need electric power to start it? What is water temperature it can withstand? I need something suitable for 180-200F.

Thank you
C.

 

[ash9144]

Any of the pumps TBP listed would be fine. You just need to figure out how to use them.

Since your scenario is a power failure you would be looking to bring the boiler down to a safe condition not continue running. So why don't you install a tank elevated above your boiler with enough water to bring boiler down then you can use gravity to feed the boiler.

 

[curtis2004]

Ash9144,
My boiler will have 100 psi MAWP (80 psi working). So water supply should have be able to supply 7,000# @ 105 psi pressure. In order to generate this pressure I have to list my feed water tank to 210 feet high.
All these required by NBIC paragraph 2.5.1.
I left with only option of supplying generator (or UPS) to power emergency feed water pump. If anyone has another alternative please share with us.
Thank you all for help,
Curtis

 

[TBP]

If you installed a steam turbine driven pump, why wouldn't you just run it as your primary?

 

[ash9144]

Yes you could put your water tank 200' up in the air or you can put a little thought into this and do something crazy like pressure up your tank with nitrogen.

 

[TBP]

People pushed water into solid fuel fired steam boilers for well over a century before electric motors became commonplace.

This is not rocket science. Nothing needs to be invented, or re-invented. It's ALL been done before, and written down.

Pick-up an old Audel's "Power Plant Engineer's Guide" on ebay. All will be revealed...

 

[Drexl]

Hi I seriosly doubt you will get a turbine driven pump if cost is an issue.

 

[GenB]

I need to get paid for this one.
your boiler needs 10-13 GPM or as you say a 5HP motor,
It comes with a little sacrifice,
1- get to raise your normal water just an inch or 2 to baffle the emergency
2-a 4000 or better generator cheap one will run at least 1 HP motor
good for 50 hp boiler
2 or 3 or even 4 generators
does not account for 30,000 Dlls.
I forgot: enough w/ a generator ... engine run pumps,
come on.

 

[MJCronin]

I reject your premise:

"This is solid fuel boiler and I need to provide emergency water supply in case of power failure,"

Not all solid fuel boilers are the same. Coal burns for a long, long, long time. Wood chips....um not so much.

You state your problem as fuel burning while feedwater is denied. Was you boiler originally designed for "wood chips" ????

....or was this boiler a shade-tree "rework" of an oil or gas fired boiler ? If it was a home-brewed "rework" it may have not been a good idea to begin with.

Please explain..

 

[curtis2004]

Is is designed and will be built (in Feb. 2011) to burn wood ships.
You are right about difference between coal and wood chips.
But we are inclined toward supplying 15 kW genset unit for the following reasons:
1. Boiler is fully automated by PLC, so manual or semi-manual emergency solutions out of window.
2. Based on NB code you have to provide two independent source of feed water pumps. So supplying cheap, "emergency only" pums are not satisfactory. In fact any emergency pump has to supply water at MAWP+3% at 100% rate.
3. We could provide gasoline/diesel engine driven pump, but there will be other automation and control issues (how will you control water level of boiler?).
Summirizing all above and comparing boiler operation with and without PLC controls, we have decided to go with genset unit, although it cost a "few thousand dollars" more than most economical solution. It is a huge difference if you compare reliablity, and functionality of genset unit.

Thank you for all,

Curtis

 

[RR79]

Can you have two motor driven pumps, each one connected to a different network power?

RR

 

[Duwe6]

Industry standard is a "Terry Turbine" simple single-row steam turbine to drive a boiler feed pump. To meet Code [which is also probably State Law], this steam-driven BFW pump has to be running/capable of instantly running 100% of the time after Startup of boiler. Typically, steam BFW pump handles base-load and electric one is for emergencies [after startup].

http://www.dresser-rand.com/products/steam/singlestage/AVT.php