recovering energy from warm waste water

[plumberet]

Like to know whether there are smart ways of recovering low quality heat energy from waste warm water ( ~40deg C ).

Thanks.

 

[vpl]

See thread391-208254.

Patricia Lougheed

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[dcasto]

Use to heat buildings. Warm air to boilers. Warm up fuel gas.

 

[waross]

A lot of heat exchangers run at about 10 degree temperature difference. Subtract 10 degrees from 40 degrees to allow a temperature gradient and it will probably become futile to try to extract any heat.
About the only practical use may be to preheat cold air entering the building.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[davefitz]

Can also be used as a heat source for a heat pump; more efficient to use a heat pump than an electric resistance heater. For example, at many power plants the wastewater stream can be eliminated by use of a ZLD zero liquid discharge system. The electric heaters needed for that system's falling film evaporator and crystalyzer are inefficient if configured as resistance heaters, but not such a bad penalty if configured as heat pumps.

 

[IEAANNEX49]

Yes. It depends on the simultaneous heating and cooling loads of a facility. Neutralized waste water can be filtered and heat extracted by plate and frame heat exchanger. Common uses are to preheat well water and/or makeup air.

 

[UBbaja]

Perhaps you could use the water to cool another medium instead of heating...