Co-generation Information Needed

HI !

There are several generation possibilities, you should review the threads all ready active. If you need some suggestions please ask, after you reviewed active threads. JOIN IN ON THE OTHER THREADS IT WILL BE A LEARNING EXPERIENCE !

thanks

goldrushnugget999

We manufacture standby generators and had a cabineted unit for farms that redirected the hot air from the radiator & gen.set for heating e.g. into a barn. This is very basic recovery of wasted energy but works very well and was popular. Of course in hot weather this facility is wasted.

Sear sir: Please inform me where do you use it, and ambience of your area. henryzhang1@hotmail.com

We would like to know where we could utilized this kind of energy.Probably , we prefer to utilized it for cooling purposes or for operating the chiller unit.We have 4 gas fired generator which are installed at outside our main building .

Do you need annyother information we welcome it.

Nadeem Usmani

There is a nice fancy way of using a stirling generator, coupled to a Stirling heat pump as cooling machine. The hot exhaust can be used to drive the generator.

With the lower heat level of the engine cooling water you better heat up domestic water, make shure that you keep this water above 70°C before distributing it. (preventing bacteriological growth)

Thank you Gyen for your valuable information. I will look into it deeply.

Nadeem

HI !

IF You have 4 gas fired generators, WHAT HEAT RECOVERY are you using to co-generate other power or from that waste heat ?

THANKS

goldrushnugget999

Hi Goldrus,

We have four gas fired of 300KVA. We have not yet calculated how much heat we are wasting.Is there some simple calculation to know the haet wasted?

Nadeem Usmani

HI !

IN REPLY # 12 your answer is posted about 60 to 70 % heat is wasted. you need to find out what your company needs additional power for? than start asking questions on this blog. or start a new one. I'me shure the fine responders will help you attain the goal that you will have. maby a new product.

Make an inventary of the heat needs in your organisation.

List the heat level and the used power instantanious (KW) and total energy consumed (KWh).

You will easely find installations which could be fed with the heat from the genset.

You will have approx 400 KWh of heat that could be gained.

If your organisation can't do a trhing with the heat, ask the neighbours.

Going into Stirling heat recovery and transformation to electricity would bring you to far, if you would like to havepressurised air as a by product I would be pleased to work something out.

HI ! Gwen ! I Agree with the inventory but he should add an extra step.

IF the questioner could put a hood over the 4 gas fired generators and get a TEMPATURE MEASUREMENT you could couple that with a company wish list of power needs to be satisfied, the heat could be converted to satisfy those needs.

IT'S up to your company on WHAT power needs need to be solved. than call for suggestions on how to solve the problem.

thanks

goldrushnugget999

You could run the exhaust through a water reservoir and heat the water to a vapor. This would distill the water then you could use it as drinking water. You could also distill it to a higher elevation and use the water as a reserve power source to run electrical generators and still use it as a water source.

Don Kingery

We have two natural gas fired Waukesha engines that are used to generate electricity. The exhaust is run through a heat recovery boiler generating hot water which is then used to run a Trane absorber which makes 40 degree chilled water for office air conditioning. There are also heat exchangers used to cool the engines which are used to generate even more hot water to run another Trane Absorber. In the winter if cooling is not needed then we can use the hot water to heat buildings. Contact Waukesha or Trane corporations for more info.

A reciprocating generator loses heat from the exhaust, the jacket cooling, the oil cooler, and what is radiated to space. Roughly, of the input energy, 25% goes out the exhaust, 25% to the radiator from the jacket, 10% from the oil cooler and 5% to space. The remaining 35% produces useful mechanical energy to drive a generator. Traditionally the exhaust and jacket heat goes to a heat recovery boiler to produce low pressure steam (15 psi) -- which captures virtually all the jacket heat and about 80% of the exhaust heat. The oil is cooled separately and that energy is lost as the oil is kept at about 180 degrees - too low a grade of heat for useful purposes. The heat radiated into the space (along with the noise) makes the room with the generator an unpleasant place to be in.

Ideally the low pressure steam is used to supplant heat that would otherwise be provided by a boiler. A hospital, for example, needs reheat energy year round for its ventilation system. If there is insufficient need for heating during summer months, an absorber could be used. Absorbers are expensive and require cooling towers, the unit itself is about 80% more expensive than an equivalent size electrically driven chiller. Low pressure absorbers also have low efficiency rates. A coefficiency of performance of about 67% is standard (for every unit of heat put into it, you get .67 unit of cooling out). Centrifugal chillers by comparison are 8 to 10 times more efficient -- but they use electricity. High pressure, dual effect, absorbers are about 70% more efficient, but it is not very practical to produce high pressure steam from a reciprocating engine. Dual effect absorbers are significantly more expensive than standard absorbers.

You could send the low pressure steam to a condensing steam turbine. I don't have the numbers off hand for the efficiency (it depends a lot of the quality of the turbine), I think 10% would be best you could hope for. The turbine/generator would probably be in the same price range as the absorber and you would need a cooling tower for the condenser.

Thank you Howetwo,

Your information is valuable to me. The concept of absorber is not practical for me.I don't have estimation or cost data. Utilizing heat for running chiller is quite feasible.Could you explain more on the performance of centrifugal chiller or any chiller for that matter.

Nadeem Usmani

Centrifugal chillers can be built that deliver cooling with efficiencies as low as .50 kW per ton (12,000 btuh per hour for a ton of cooling, a kilowatt is 3,412 btu per hour) at a standard condition of condenser water being supplied at 85 degrees F to the chiller and chilled water being delivered at 45 degrees F. This gives a COP of 7.0 for the chiller itself. Of course there has to be motors for the chilled water, condenser water and cooling tower fan -- which lower the overall efficiency of the system. I have measured plant efficiencies at a couple of installations and saw it range from .85 kW per ton at low load and to .58 kW per ton at high load (using high efficiency chillers and taking into account the chiller, pumps and tower fan power draw).

Chillers can be driven by steam turbines. The ones I have seen all used turbines that ran at least at 120 psi, which as I have mentioned is difficult to get from reciprocating engines.

As a rough estimate, single stage absorbers are 50% to 80% more expensive than equivalent sized centrifugals. A single stage absorber can make do with about the same size cooling tower as a similar size centrifugal as it can send hotter water to it and operate with hotter return. A two stage absorber cannot and needs a much bigger tower. Two stage absorbers are perhaps 40% more expensive than single stage units.

One could have a direct fired two stage absorber where the generator engine exhaust was ducted through it to produce cooling (instead of the absorber having its own burner).

HI !

A few comments above there was a comment that the requesters oil temp would 180 or so degrees. Our sterling engine friends might have a few good words to say on the use of that temperature oil to use in a sterling engine to drive additional power possibilities. You should give him an e-mail to see what he has to say on that subject.

THANKS

goldrushnugget999

Perhaps a good idea to mention the unit. 180° C/F ?

Oil at 180°C is not that good for the oil (at least when you want to use the oil a lubricating fluid). It would be a nice start for a Sterling unit althow it is still low for a decent efficiency.

That would be 180 deg F, about 82 degrees C.

HI !

THE oil at 180f would be a good start , than cycle some of the engine heet in also. the oil heat base is important to maintain a steady tempature to build from. than the engine heat can make up the difference to the temp you need to efficently run the sterling engine to run the fridge you are looking at. the rest of the heat can be used for other needs mabe even recycle the sterling heat to include with your other heat to build a heat source for a third purpose. mabe you can build a solar heat absorber to help sustain all the heat you need. the fine cr4 engineers could help with that also. PUT your thinking cap on and start desinging a complete system to satisfy your needs and start building. time is passing & Winter is comming.

good luck in your indevor

goldrushnugget999