High temperature circ - which is best? (PAH)

Dave Yates (PAH)

Sitting here thinking - which supply house should I call for advice & it struck me - The Wall (D'oh!)

We have a client who is utilizing a steam boiler to pull water off and run it through a heat exchanger. The HX has 3" supply & return lines and they've been using a centrifugal pump that ends up needing to be rebuilt every few weeks. The lines run for several hundred feet out to equipment on the plant floor.

Any wet-rotor pumps come to mind for such high-temp applications?


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Constantin

McMaster Carr seems to stock some

Look under centrifugal pumps... some of theirs are rated for service up to 250°F and the motors can be totally enclosed in cages next door. Not wet-rotor but may be the right thing for this application.

Mark Eatherton1

YO, Professor Yates...

I wouldn't suggest that you consider using a wet rotor pump due to all the free ferrous oxides (nice name for RUST) floating about in the system. I've seen PILES of Grundfos pumps in front of a hot condensate system exactly like you're speaking of.

Maybe you should conside elimination of the hot condensate system and utilize the steam at hand to do the job instead?

If not that, then I'd look to someone in the steam biz to specify a good pump for your application.

May tell some water treatment would make the pumps last longer?

What on the pump is failing so often? Lemme guess, the seal!?!

A pump needing that much service indicates to me (In the words of Tony Connor) a water quality issue disguised as a mechanical problem...

Good to see you my friend.

ME

Dave Stroman

I use Taco for 2 reasons.

1- Most of the impellers have large vanes so there will pass larger pieces of crud.

2- Once the cart. is full of water, it stays there. Grudfus flows system water through the cart. I just seem to have better luck with Taco in this application. I have even heard of putting a Taco pump on a clean system for a while until the cart. is full. Then moving it to the dirty system. Never tried it.

Dave in Denver

bob_25

Why not

use a steam to water heat exchanger(converter) and eliminate the pump? bob

ScottMP

Dave

We've done this a few times in resdience,s and used a Taco Bronze 110. The motor is set back and dos'nt get the full heat and the bronze holds up to the condensate. I've got one running that way for about ten years now.

Scott

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Dave Yates (PAH)

system description

File this under Ripley's believe it or not, in which case you ain't been around long enough to see the oddities this trade has to offer!(G)

A fairly new Burnham steam boiler that serves but this one purpose: a pump scavenges water from the base of the boiler and sends it up to a HX mounted above the boiler. The hydronic side of the HX travels via 2" pipe out to equipment on the plant floor (Cherman presses that apply the coatings you see on either carbonless or carbon multi-layered forms. The presses have hydronic rollers that must maintain 190 F.). The original installer choked the cross-over down to 3/4" & aside from the failed pump seeing 210 F water, I think it's this "dam" that is causing the blown seals.

The Taco 0012 is rated for both high temp and head & we had to move fast as lightening to maintain production. We'll look at a by-pass PRV next (attn: Bill with Danfoss!)and an increase in the nearly dead-heading piping set up.

BTW, the previous outfit had also installed outdoor reset on the office commercial HW baseboard (same scenario, only a different steam boiler piped to another HX - this one steam to hot water). A lack of understanding that BB does not work properly on full outdoor reset led to some mighty upset secretaries who sit under a wall of aluminum framed single pane glass. The reset was a waste of money & they were burning through mod-motors. Now they're warm and snug(G). The owners thought they needed a new heating system and were about to hire an engineering firm to the tune of 40G's to give them plans. For 40G's, we can install some new high eff boilers & have change left over(G).

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DanHolohan

At what pressure

are they running the boiler?

David Van Wickler_3

Taco 1600 series

have an outboard bearing and have optional high temperature mechanical seal kits for 300F operation.

I specify them on all cogen jobs where the temps can hit easily 260F for period during low parasitic loads.

David Van Wickler_3

OR TACO KV

series have copper lines that provide discharge pressure fluid for the mechanical seals.

for higher flow rates, etc. you can istall a brazed plate hx and pipe a little bronze pump between the HW storage tank and the heat exchanger.

I've also used it for buidling recirc preheating. The recirc. pump is run cont. and provides a tremndous preheat. One job had about 30,000 Btuh through a little BPHX and was cooling 300F water to the mechanical seals down to 180F.

Needless to say we sell a lot of pumps to the cogen guys.

Give me a call if you need help.

631 585 6800

[Deleted User]

Dave.

For that application, we use a 3-piece B&G. An HV will get you to approx 40 gpm. Close to the 45 of the 0012. We have the pump guys fit the bearing assembly w/ a Viton Seal & bronze impeller. Good service w/ minimum problems over many years.

Dave Yates (PAH)

closed loop

Back at cha pal! Gonna be out your way this summer & need to chat about where to take an almost 90 year old to do some quality time trout fly fishing.

It's a closed hydronic loop & we built one heck of a sweet injection panel last year when the second press three-phase Cherman electric boiler tossed its framistan. The rats nest of hydronic piping installed on the first press needs viagra now just to even think about pumping(G). We mounted Grundfoss pumps on a SS board, which was then enclosed inside a SS cabinet that sits quietly on the floor adjacent to the press. Thanks to our friends at Danfoss, we're maintaining 190 F inside all three rollers. No pictures allowed to be taken of the final installation (trade secret stuff), but I've got a pic of the panel somewhere - in my laptop I think.

We're dealing with the closed hydronic loop side of the HX.

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Dave Yates (PAH)

cranked

down the first day I laid eyes on it. They had it set for 5/8 PSI initially, but all its seeing is that HX. It'll run up to 1.5 Lb.

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Dave Yates (PAH)

first choice

but not available on short order. That's the first problem. The second problem is finding anyone locally who can put the assembly parts together (on paper) for ordering the correct combination.

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[Deleted User]

Dave.

Southern Utilities in D.C. Ask for Steve. 202-289-1141. Should have in stock. Any problem. Have him call me.

Dave Yates (PAH)

appreciated

Ron,

Next beer's on me! Thanks for the reference & we'll definately put that in our card file for future needs. I've had a tough time (in the past) getting qualified help on building pump assemblies or identifying existing assemblies for pump curve performance. There's an apartment complex here in York you'd have to see to appreciate. It looks like a mad scientist with an array of pumps from varying manufacturers was let out of the asylum for just long enough to wreak havoc in the mechanical rooms! Couple that up with an ever-evolving revolving-door of maintenance people who utilize their REM account for switching out impeller assemblies based upon "what's in stock" and you can begin to appreciate our frustration. Even Sherlock Holmes would have been stumped on occasion(G).

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