Cogeneration and Chimney Gases

Yes, it's called co-generation. The exhaust is used to heat or even boil the water. Naturally, the exhaust gas after this is much cooler than before, so your plant design must take this in account.

I would think that a well-designed Horizontal Thermosyphon Reboiler should give a reliable steam flowrate that should also support stable operation of a turbine.

Of course, you have to first filter the exhaust to remove some of the combustion residue if such might have adverse effect on the tube materials. Smoke - if any - in the exhaust might also cause some fouling problems in the Tube side.Otherwise it should be okay.

you can by using HRSG ie heatrecovery Steam generator which comes with a divertor valve ,contact steam boiler manafacturers in your area.

crm

This energy can be definitely utilized in number of ways as suggested by Gurus.

You may describe the energy used by the process and the plant in the poocess flow digrams.

You will definitely find best techno-commercial solution of using the part of energy back.

Any heat recovery project is definitely worth the effort...because it conserves natural resources and adds to profits.

It is possible to recover the heat from the exhaust gases through a waste heat recovery steam generator if you require steam for process applications. The volume you indicate appears too less for a steam generator to be economically viable. alternately it can be an air-air heat exchanger if you need hot air for process applications.

The key input here is to have cleanest possible exhaust entering the HE. The glass material have a tendency to coat the tubes on the heat exchanger and thus reduce the coefficient of heat transfer over a period of time.

Best way forward is to talk to heat exchanger manufacturers or a consultant if you have one.

Satish

Dear Massey 726,

Thank you very much of you reply and points of view of this cogeneration. The excess oxygen is about 3.5% at the flue tunel.

Please advise how to convert from heat to cold water ? ( As we dont need hot water in our South East Asia area)

Regards

Hi Aikhh,

You will need to produce either hot water or steam from your exhaust gas stream this energy will then be used to heat an absorption chiller. Crazy as it sounds the heat produces the cooling effect through making changes to the concentration of a strong solution of lithium bromide which is circulated between several vessels on the unit. Unlike the vapour copression cycle machines there is very little electrical energy used 'on board' the unit as only a small solvent transferr pump is employed.

You should understand however that the COP is sub- unity ( unlike the vapour comression m/cs) ; typically 0.70 for a single effect m/c or 0.85 (ish) for a dual effect version The choice of which is really dictated by the available supply temperature. As you will easily have more than 100C I would suggest the dual effect version.

You will have to dissipate the absobed energy (from the chilled water load plus the applied heating effect; some for a 1000kW chiller your air blast coolers will be dumping 2250 kW. This cooling water will be leaving the machine at around 35C and should be returned at 25C therefore the delta T is quite small and the Q will be correspondingly high; therefore largish pumps and pipes! You could always consider aidiabatic assistance to the air blast cooling unit but where this is cost effective will depend upon your prevailing ambient air conditions.

'Thermax' (India) produce an excellent absorber and you should visit their web site.

Best wishes.

Hi Aikhh,

As a follow on to my last comment and with due reflection to the contributor who mentioned Organic Rankine Cycle as an option it would be possible to combine both the absorption machine and ORC in what would become a CHP installation. Much would depend upon the thermal fluid used in the turbine circuit as the temperature of the condenser cooling circuit could be raised to say 90C by reheating from the thermal flud source and then used to heat a single effect absortion chiller. In this way you would benefit from some electrical energy plus the cooling effect you desire.

However as I said in my first response you will be wanting to achieve best return on capital and the ORC kit is expensive so you will still be more comfortable concentrating on the production of chilled water in the first place. You could always add the CRC at a later date!

You quote your excess oxygen level as 3.5% and at this value there is no chance of refiring the flue gases so you will be limited to an output temperature as dictated by the hot gas stream.

Good luck.

Hi Massey 726,

Thank you very much of your reply.

Nooter Eriksen HSRG's Give them a google!

the best thing would be an ORC system. Ormat makes smaller system, you are looking at 300 kw.