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The Key Points

Several key points and questions emerged from each of the roundtable sessions, which were discussed in detail during the cluster session, involving members of the audience.

| | Nov 30, 2011 | 6:19 pm
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Several key points and questions emerged from each of the roundtable sessions, which were discussed in detail during the cluster session, involving members of the audience.

The questions were directed at the members of the audience:

Should we opt for centrifugal or absorption chillers in a bid to create a cogen regimen? How should we make use of power plants to recover waste heat in power generation?

  • Is there a need to understand CHP and cogeneration better and to differentiate between the two?
  • Is clarity needed on?…
    • When to use turbines
    • When to use engines
    • The objective of cogeneration
  • What needs to be done to enhance knowledge?
  • Do suppliers have a role in providing education and training?

What is the impact of doing the either (centrifugal or absorption) on capex, IRR and maintenance?

Wherever you have water and steam, you have a “messy” operation, simply because there is lot of salt and impurities to clean all the time, plus chemicals. Is there agreement on this? What are the possible recommendations and observations?

If absorption is the way forward, should we opt for double-effect or single-effect?

  • It depends on the application, availability of funds and the availability of technology to produce the double effect.
  • As long as it is financially feasible, double-effect is better. If not, single-effect is better.
  • The roundtable participants generally agreed that they do not disagree with having double-effect.
  • The advantage of double-effect is a better COP.
  • The disadvantage is cost and availability of technology to produce lower-vacuum vessels.
  • If Delta P is high, you need thicker steel plates to make the vessels.
  • If you have thick steel, you need a machine to roll it. Indeed, if steel becomes very thick, you might not be able to find a rolling machine that can roll very thick steel. Even if you find a special machine to do it, the cost goes up.
  • Double-effect needs three different levels of pressure vessels rather than two.

Similarly, how many kilowatts can you generate from a steam turbine to feed a centrifugal chiller?

  • What is the capacity of absorption chillers that can be produced is the right way of asking the question.
  • Knowing the electrical power output of a gas turbine (MW), you can approximate the capacity of your absorption machines by multiplying the MW power of the gas turbine by 0.7 or 0.6 to get the MW cooling of the absorption machines.
  • In the case of diesel generators, you produce about 50% of the absorption cooling from a gas turbine due to lower exhaust temperature.

Can we zero in on a formula to establish a relationship between power generation and cooling capacity in centrifugal chillers?

It is possible but hard to pinpoint specific figures due to variations in equipment efficiency.

Trigen using diesel engine: is it ideal for small capacity? What is the maximum capacity of diesel engine? If choosing the diesel option, the flow depends on how big the diesel engine is.

  • Trigen using diesel engine is a viable option.
  • The most crucial aspect for selecting an engine manufacturer are:
    • Good track record in Saudi Arabia
    • Strong after-sales support

If opting for the steam turbine approach, is it recommended to go for a double-stage steam turbine? And what power can be generated from a double-stage steam turbine?

  • High-efficiency steam turbines driving centrifugal compressors constitute a good alternative. What percentage of the chiller cost is the turbine cost?
  • What is the highest COP possible?
  • Double-effect absorption chillers have a COP of 1.25 to 1.35. What is the average price per tonne of double-effect absorption?

In the case of rental solutions, is it possible to develop a mobile heat-recovery system?

The general consensus among members of the roundtable is that it is not feasible to develop a mobile heat-recovery system.

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