Direct Steam Injection Hot Water Heating (ME)

jp_2

how do you measure your efficiency?

Mark Eatherton

Anyone have any experience or know of a system?

I have a customer. This customer and his son started a fish farm back east some place. They are required to keep a rather large quantity of water ready for emergency replacement should a bacterial incident occur. The water they are using is extremely hard and has a tendency to lime scale just about everything they have attempted to use. He asked me today to look into the possibility of a direct injection system with steam. In other words, he has a large open tank of water, and he wants to directly inject steam into the water to raise it from the 40 degrees F it comes out of the ground, up to the optimum 72 degree F water temperature the fish are living in. I explained that the size of the physical plant would be rather large, and he is not concerned with that issue. I told him with it being a single pass, that the water would have to be extremely softened, and he was not concerned with that either.

Anyone have any experience in this area?

TIA

ME

Brad White

Sparger Tube

What you describe is commonly done within a deaerator, Mark. Steam is injected via a perforated tube called a sparger tube, below the water-line.

The driving steam into solution carries and "boils off" excess dissolved air to "deaden" the water prior to boiler feeding. The non-condensibles (free air and other gasses) are vented off to atmosphere, but the latent recovery is nearly 100% as it all goes into the water. Of course this eventually makes it's way back to the boiler as feedwater...


I cannot say that this is good for fish ("Hey! Where is my oxygen!").

Is an immersion coil not a possibility?

If not controlled, a nice poached Bacalao or Ciaopino can be whipped up in a hurry.

tim smith

Direct steam heating

A little Mark. Noodle cookers and chemical baths. Using just low pressure steam and regulating flow with steam valve controled by aquastats etc. Boilers don't tend to last long with the once through approach for condensate and all that fresh water makeup.

bob_46

Mark

I don't see what he would gain by heating the water that way. If you don't return the condensate to the boiler it will lime up just like the water heater.

Henry

Direct steam injection

MAking hot water in anyway with steam is not green and very costly. A high pressure steam boiler typicaly produces steam at 70% eff. Even when direct steam injection to produce water, losses in the piping etc the efficiency is down to 65%. For every $ one gets 65cents of hot water. A condensing boiler with an imertsion coil would be at 96%. While a direct contact heater could work at 99%. The problem with direct contact heaters would be scale and acidity, not good for fish!

Our instalations in the university tanks were of the condensing boilers types.

Tony Conner_2

Where...

... are you getting your numbers? 70% eff for HP steam boilers? C'mon ... if you can't hit 80% boiler eff (at least), something is wrong. And I know it can be done, because I've done it - repeatedly. The boiler should be able to hit percentage efficiencies in the low 80's.

There's nothing particularly inefficient or expensive regarding steam. You just need to design & install it correctly. Direct injection steam works just fine - if done properly. It doesn't need to be high pressure steam for this application. Low pressure will work, and in some ways is better. As mentioned above, boiler water treatment issues will need to be addressed in this application. The make-up water will need to be softened, and deaerated. The costs associated with that will a big factor in determining whether this project goes ahead or not.

Tony Conner_2

Standard...

... boiler efficiency calculation: Net heat output of the boiler divided by the heat input of the fuel, over the same time period.

Marty

.

Tilapalia ?? the kind of fish that is?

Multiple heat exchangers off a boiler. shell and tube for ease of cleaning, divide the load in a way that one at a time can be taken offline for cleaning on a schedule.

Rich Kontny_5

Ludell

Mark,

Look up "Ludell" a company now owned by Ellis, They make hot water this way with direct firing into the water with natural gas and using the condensate as the domestic water source.

They claim mid 90s for efficiency. I have visted there mfg. facility here in Milwaukee. We provide some of the OEM products for there gas trains etc.

Have since seen their products in commercial laudries and cement batch plants.

Rich

tim smith

Ludell heaters

One of my clients, large seafood processor put one in for one of their plants, has been quite reliable for them.

bob_46

Careful

Once you add steam to water I don't believe that it's still potable. The use of steam for humidification is frowned on if the boiler water is treated at all. Something about amines.

ttekushan_3

yeah. I see these numbers thrown about.

especially at "pusher" web sites with a lot of hydronics to sell. No citations, no valid peer review studies with equivalent installations anywhere to be seen. Certainly no consideration of embodied energy over the product lifecycle against realistic product life expectancy.

Yet all over the country (university of Utah, Ohio State University, Kent State, and some of the Ivy League campuses and many more) steam distribution is being EXPANDED for campus needs including DHW and district heating/cooling. All of the newer buildings use HW heating from steam shell and tube heat exchangers. Their reason for doing this is that the steam is the most efficient means of transporting heat energy currently available.

Come on. Steam's a gas thats lighter than air that carries about 1000 btu/pound total enthalpy in which transport pressure drop is quite small and where losses @125psig are about 1% per piping MILE. Discrete economizers of all sorts are available and regularly used in facilities where management is serious about steam. [When a facility's management refuses to invest in these sorts of things its clear that the energy wasted by their steam processes is a self fulfilling prophecy.] Flue gas condensers get you in the 97% heat utilization territory while keeping the extraordinarily low reticulation energy requirements inherent with steam distribution.

Steam's green alright. But conventional wisdom, vague impressions, and shocking levels of ignorance or sloppiness on the part of operations compromises its performance over time. Just like what will happen to the new (and therefore infallible, so I've heard) technologies out there. There appears to be a motivation to keep conventional wisdom and these vague impressions in the minds of management and the buying public right where they are.

-Terry

Tony Conner_2

There...

... are lots of food-grade water treatment programs. The use of amines at least used to depend on what kind (there are several) and the ppm. It should also be noted that not nearly all water treatment programs utilize amines. There are numerous ways to skin this particular cat.

Mark Eatherton

Yellow Perch

is the fish of choice...

ME

Mark Eatherton

Thanks to everyone for their input...

I think that due to chemical considerations he's going to look at a different alternative.

ME

Unknown

Sweet

How True