Absorption Chiller

Certainly absorption chillers are available and they do work. The main drawback will be the capital cost of installing one and piping it up to where the coolth is needed. Oh, and do the users of the coolth take their service from elsewhere at the moment? If so, then where's the payback point?

Consider also maximising the return of this hot condensate to the boiler house and re-using it as boiler feed. Re-using hot condensate is far more valuable than producing cold demineralised water afresh and injecting that into the boiler, for the obvious savings to be had in demineralising and heating the water. There are steam-driven condensate lift pumps available and they are usually worth the expenditure on this basis alone, achieving payback periods in terms of months, rather than years.

Condensate return piping can be notoriously difficult to keep from corroding so some care with material selection will pay dividends. Some form of reject arrangement at the boiler house, perhaps on the basis of the measured conductivity of the condensate, is recommended, and local plant economics will determine the conductivity at which the reject should operate. The economic calculation is iterative and subject to review at intervals as energy prices change.

I agree that there is probably a bigger economic benefit to getting the condensate back to the boiler and reusing it instead of heating and treating all the cold water required for make-up. Absorption chillers are also less efficient with a lower temperature heat source. Also, if you do an economic analysis, consider the difference in chiller maintenance costs.

I worked in a plant that operated an absorption chiller succesfully for 40 years. It was replaced when oil prices made it uneconomical to burn fuel oil to make steam to produce chilled water. At this point it was replaced by an evaporatative chiller which consumed much less energy on a kwh basis than the absortion unit, which in addition to the boiler operating costs had the added cost of running the cooling water tower recirculation pumps that were quite large. The absorbtion chiller had almost no maintainance reliaibilty issues and was very consistent in its operation. It produced chilled water at 45F for A/C and 36 F for process cooling. The only major issue was keeping the steam ejectors clean as every once in a while debri from the steam piping would block the throat section of the ejector leading to a sharp drop in cooling capacity.