Cost of Boiler Condensate

Condesate cost=

cost of raw water to the facility +

cost of chemicals to treat the water +

cost of BTUs to heat raw water to condensate temperature

In the distant past, when I have done the exercise, the cost was $/1000 gallons of condensate and the plant's number was approximately $6/1000 gallons for a coal fired steam system. I would be very curious what cost you end up with today and the fuel used.

I don't think so.

There are costs of increased heating, water use and chemical use.

Not returning the condensate increases blowdown. The boiler operator probably knows the number of concentrations they are running, so the blowdown rate could be determined. Increased blowdown increases feedwater heating and water use.

The boilers may have a blowdown heat recovery system -- which can recover up to 90% of the continuous blowdown heat loss.

The blowdown typically goes to a steam separator and cooler. The cooler most likely uses domestic water for cooling before dumping to the drain -- a further increase in water use. Find out the temperature the blowdown has to be cooled to (140F is our locality's requirement) before it is sent down the drain to determine this water usage.

The condensate and blowdown loss results in increased water use which means more water softening and boiler chemical use. The cost of chemical and softening per water usage rate may be known by the boiler operator. If not it can be determined by looking at boiler logging of make-up water and reviewing chemical and salt costs over the same period -- unless you have a fixed water treatment contract.

With direct steam injection heating there would not be the heating losses associated with condensate return. No flash steam losses and no heat loss in the condensate lines. The amount of flash steam depends on the pressure of the steam being used and the temperature the heater is operating at. Flash steam can also be diverted to a lower pressure steam line or run through a condenser to capture the heat.

To estimate heat losses in condensate pipe, look at the temperature of the returned condensate in the surge tank, adjusting for the percentage of make-up being added.

A pharmaceutical factory in Dagenham justified a substantial investment in condensate recovery sets and condensate piping on the basis of the value of reusing condensate. The pantomime (it is that time of the year, after all) went someting like this:

• So, er, <scratches head> say 40p per tonne at the meter coming in off the mains. Say 60p per tonne to reduce it to 7ppm TDS, near enough. Bung it in the boiler. The heat value in it was, oh yes, an additional £1.68 per tonne by the time it appeared as hot condensate at a steam trap compared with the temperature coming in. That's a lot. Now, say £1.50 per tonne for the volumetric charge of throwing it away as sewage. Hmmmmmmm. Instead of doing that, consider re-using it. Quick back-of-the-envelope flowsheet <scratch, scratch> ...... Now, add up all the flows to be saved <scratches away with pencil and calculator> . Apply a fudge factor for any changes to current water treatment regimes. Which equals, er <scratch, scratch, tap , tap> , so much. OK. Take out a bit more for the additional maintenance costs for all those new Ogden pumps and all that pipe lagging <scratch, scratch>. Dum, de, dum.... Now, divide into a project justification investment payback criterion that is occasionally adjusted by the Senior Management Team for the purposes of investment evaluation. Ok. Now, how much is intended to be invested, where's that shopping list, oh, here it is - £100,000? Work up a scheme and estimate, paying attention to the justification <scratch, scratch> for the investment. Yep. It's a good-'un. Job's done. Apply. Off it goes. <A few days pass> Wow - authorised!

And that was in 1992 prices!

There is no or very little cost. You have to heat the hot water anyway. Whether you are using direct or indirect method of hot water generation the heat is still the same. The cost maybe a few pennies per ton of steam for lost water treatment chemicals.

cost of lost boiler condensate .

You first calculate the cost of steam heating 1 kg water from ambient to 90C or 95C or 100C or whatever temperature your condensate is at whatever efficiency your boiler is 80% or 85% or 90%..

That is your cost of draining 1 litre condensate at the stated temperature & boiler efficiency. The rates will vary obviously with changes in ambient temperature, condensate temperature and boiler efficiency + when rates of fuel change.

My cost in Pakistan varies Rs.0.10 - Rs. 0.15 per litre. Average Rs.0.12 per litre of 90C condensate at 85% boiler efficiency or Rs.1200/m3 of condensate = US$ 19.35

or Rs.1200/m3 of condensate = US$ 19.35 Sorry Rs.120/m3 = US $ 1.94

using a direct sparging hydro heater to generate hot water?

If you have no option then it is suggested you use a 3-way Temperature control mixing valve to save cost on storage tank and standing radiation losses.

If you have an option to convert to in-direct heating with coils then do it so condensate can be returned to boiler feed tank via condensate power pump. Additionally install a flash vessel and utilize the flash steam from the boiler blowdown as direct injection + if you can utilize the flash steam of steam traps closer to this unit.

Next time please be specific as regards the quantity of water you are heating, ambient temperature, final temperature, your cost gas/cft or m3 or your cost of fuel, the calorific value of your fuel, your type & efficiency of boiler etc., to get a detailed working.

sorry to say that we are still in the development of this software to be as easy method in determining the cost of condensate loss.

Will keep you posted when we are in a trial run of this technology.

Latest Instruments in the market is the steam flowmeter to determine your steam consumption. see spirax sarco website.

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