Hi all,

I wondered if you could help me. I am currently working with a power plant engineering & constructor, designing a 300MW CCGT Power Plant, with additional duct firing taking it to 350MW.

There are currently two routes we will take for the purchase of the equipment, one is for a power equipment provider (i.e. Siemens or Alstom) to provide the equipment for the 'power island' (the GT, the HRSG, the ST and the electrical generator) and the other is for the plant constructor to design and build the plant using a byspoke component by component approach. The advantages with the latter approach certainly will be price, but also possibly schedule. The major advantage with the former approach however is the full performance guarantee 'wrap' we will get, as the power island (and the key equipment in achieving the guarantee) is from one supplier.

If we go for the latter approach, the plant performance guarantees will be capped by the individual component suppliers at around 10% of the individual purchase price of that component and it would probably mean that the indivual components will have to be tested, rather than the whole site, in order for any deficit to be identified to a particular equipment supplier (it should be noted that the 10 may even be split 50-50 with supply schedule, giving us even less performance guarantee as an LD).

I think the GT and ST should be fairly straightforward to individually test, due to ASME performance test code 22 for gas turbines and performance test code 6 & 6A for steam turbines, but does anyone know how we would test the HRSG? I am keen to know what typical performance guarantees we would impose (and what the amount of the cap should be) and how quickly the penalties should reach the cap. My final decision is, as the component approach is cheaper, how much cheaper would it need to be to not go for the approach where the power island is bought from a single OEM, which would give us a full performance guarantee wrap, with far better LD provisions?

Thanks in anticipation.
 

Doesn't the boiler PTC apply to HRSGs also?
I am not sure that you are better off going with one source.  The performance gar. is weak at best.  Sure they miss the firing rate so they give you bit of money. And then you are stuck buying extra fuel forever.
The timetable issues worry me more.

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Plymouth Tube

ASME PTC 4.4 is the correct code for testing HRSGs.  Also note that the correct test code for steam turbines in combined cycles is ASME PTC 6.2 (not PTC 6 or 6A).  The initial issue of PTC 6.2 was in 2004.

Best of luck!

For a combined cycle plant, there are many overlapping uncertainties in performance of each of the major components, but as a whole package they tend to  compensate each other, so the overall plant performance guarantee is usually easier to meet. Testing each indicvidual component and holding each OEM to the staed contract guarantee is not easy , and may be easy for some OEM's to weasle out of, due to uncertainties in other equipment.

For example, the CTG unused energy ( exhaust gas to HRSG) plus gas temperature and flowrate stratification at the CTG exhaust can be used by the HRSG oem to skip out of his apparent performance obligations.

 The cooling tower vendors have been notorius for undersizing the fill and  fans for the towers, but skip out of  penalties either becasue environmental conditions are far from design or ( more common) the condenser actual new cleanliness factor is 0.95 while the performance guarantee was based on a 0.85 cleanliness factor.

The EPC vendor policy and structure is better suited for an overall plant performance guarantee, to minimize time spent testing equipment and getting final payment ASAP. Likewise , their structure of the test protocol always yields a test plan that forces all test uncertainty to be in their favor.  The only  consistent plant performance issues that uniformly screw the client , that I have seen, is in the use of test uncertainies and the lack of correcting for the new condenser cleanliness factor of 0.95.