Tuesday, July 12, 2011

CrazyEngineers Forum - Mechanical & Civil Engineering

CrazyEngineers Forum - Mechanical & Civil Engineering

Heat Recovery Steam Generator (HRSG) Project Discussion

Posted: 12 Jul 2011 04:31 AM PDT

Waste heat recovery generator is a concept which is self explanatory. In any power plant, water is a common fluid present with many cycles. The end product always results in waste water with higher temperature than the surroundings. Even if we talk about a chimney, which hardly contributes to 1-2 % efficiency in the plant also emits high temperature gases. The question is; can we really counter this problem? Can we really recover this otherwise wasted heat?

Even the answer to this question is even simpler, Heat Recovery Steam Generator (HRSG). As this we are talking about steam, let is restrict ourselves to water. To have a rough idea and to make a block diagram for this project can have four units each with their own efficiencies, termed as mechanical efficiencies.
1. Evaporator

2. Superheater

3. Economiser

4. Preheater (the image shows solar water preheater, can we include something on solar here too? )


The evaporator unit will be used to evaporate water; superheater will remove any trace of moisture. The two units will not have any effect in recovering any energy. Rather, they are the units which produce the required units of heat.
The preheater is actually the first block which plays a pivotal role in the whole heat transfer. When the cycle starts, it is in dead condition, it starts gaining heat as the time goes by. Then the economizer is used to again reuse the trapped heat in waste water. Economiser is nothing but a passage through which water can flow but through barriers called as baffles. The water in this process loses heat to cold water flowing through other pipes in economizer.

The heat transfer at all time be calculated using LMTD method or more properly by NTU effectiveness method.

This video can be useful


So our main aim is to make this whole bulky arrangement compatible on a small scale.
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