Heat Recovery Steam Generator (HRSG) Project Discussion

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
[​IMG]
2. Superheater
[​IMG]
3. Economiser
[​IMG]
4. Preheater (the image shows solar water preheater, can we include something on solar here too? )
[​IMG]

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
[video=youtube;hdqrfCN0qbo]https://www.youtube.com/watch?v=hdqrfCN0qbo[/video]

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

Replies

  • ISHAN TOPRE
    ISHAN TOPRE
    reserved for facts as and when they will emerge in discussion.
  • Richard O'Connor
    Richard O'Connor
    Great informative post, made good reading thank you 😀
  • ShrinkDWorld
    ShrinkDWorld
    what is the question ? I did not understand your problem..
  • ISHAN TOPRE
    ISHAN TOPRE
    @Gaurav ->
    ishutopre
    So our main aim is to make this whole bulky arrangement compatible on a small scale.
    Can we do that? 😀
  • Richard O'Connor
    Richard O'Connor
    ishutopre
    @Gaurav -> Can we do that? 😀
    We can do anything when we put our minds to it 😀

    A Plate Heat Exchanger (PHEX) is generally the most compact type of heat exchanger which is widley available. Their flexible design also means that it can be cheap for a manufacturer to create a one off or bespoke product as there aren't any tooling costs (unless you ask for something really special!) so that may be an avenue you could explore. A wash over plate could be used in the evaporator tank for example, and incorporating a bolt-up PHEX into the superheater might help make it slightly more compact than a shell and tube style. For any additional ideas at this stage, I'll have to hand you over to the more clever members of the forum ;-)
  • parsh
    parsh
    this is a nice idea but not cheap.

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