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I second the hardness testing. T91 is touchy about hardness in both ways - apply heat and force to straighten the tube you will see some work hardening. But if you get it too hot or over heat-treat it, you can also end up with it being too soft. A reasonable range for your finished product is...

All of the piping schools that I have come across are those offered by a company to bring their new hires or reassigned personnel up to speed in rapid fashion (or at least faster than on the job training). The class at Shell is probably a lot like the ones offered from time to time at Fluor or...

I assume that you've got a gas- or oil-fired boiler here since most solid fuel boilers are going to require at least one FD fan to move or support the solid fuel in the furnace. This seems like a very bad idea to me. For starters, I don't see how you can effectively accomplish a purge of the...

I believe another term for this type of cooling tower is: wet surface air cooler or WSAC If anyone's interested in such an animal, there's some good info at this manufacturer's website: http://www.niagarablower.com/wsac.htm (I am in no way affiliated with this supplier, by the way). I've...

A CCPP deaerator operates, in theory, just like all deaerators (direct contact heating of feedwater with steam and venting of non-condesables). By "ancient deaerator" I assume that you are referring to a STANDALONE deaerator whose source of heating steam is from a pressure controlled source...

In conventional power plants (regenerative Rankine cycle), the deaerator is part of the feedwater heater train and thus sees an decrease in its operating pressure as the plant load drops unless specifically pegged to a constant pressure. These DAs routinely operate at 150 psig and higher at...

I concur with davefitz here entirely. With the exception of low pressure boilers, steam-water separation is accomplished with static, mechanical separators. Typically there are two stages of separation. The first stage occurs at or near the normal water level and the second at the steam...

Davefitz: You'll probably find that most SCR catalyst vendors base their guarantees on a 20:1 NO to NO2 ratio (i.e., NO2 is 5% or less). This is common for most GT exhausts without oxidation catalysts. The addition of the oxidation catalyst (OC) will definitely affect that ratio, but the...

There are many examples of fresh air fired HRSGs that allow for continuous steam generation at or near normal combined cycle levels. However, I'm not aware of a system larger than a LM2500 in which this has been done in a non-interruptible approach. For a unit the size of a GE Frame 9E...

I have not heard of it being added to coal, but it is offered and used in heavy liquid fuels, as gaterine noted, to counter the effects of vanadium slagging in the furnace. Depending on the type of coal burner that your boiler uses, it may provide a similar type of effect.

If you deaerator (DA) is operating correctly (under pressure with an open orifice/vent), you should see no deterioation of the condensate quality except for what is added by any make up water introduced to the DA. Since you're using demin water for makeup, the addition of hardness should be...

Cast steel should be fine for this application. It sounds like more of a chemistry problem or hydraulic problem. How's the oxygen content in the system? Is this occuring in the suction or discharge or both sections of the pump?

Well, I think that your right to be a little confused here. For those conditions, the boiler should be rated for at least 4.53 MMBtu/hr heat input (that's a net figure). The gross heat input should be higher due to heat loss and other inefficiencies. So it should be rated at 135 HP or higher...

I would like to suggest that there may be a better alternative to water washing for this application. Several contractors are available that can do CO2 blasting - high pressure dry ice pellets. The ice pellets are very effective at removing the deposits and you are left with non-hazardous...

If we're worst-case-scenario-ing the question, then I would say you'd have to assume a total loss for the one and significant damage to the other two, given the boiler size and proximity. For a downtime estimate, I'd call the boiler vendor or good local repair company and find out how long it...

Item D - if the HRSG is properly designed and/or specified with an adequate approach temperature for ALL operating cases, steaming in the economizer is not an issue. Commissioning also goes smoother with the feedwater control valves located upstream. And ZERO flexibility? That is far too...

davefitz: I feel that we're getting a little off-track from the original questions raised by ericwong which by now have been answered. The debate about horizontal versus vertical HRSGs could go on for days and days and still be inconclusive. Each design has its merits and each has its flaws...

1. The use of T91, and more importantly P91, for superheater and reheater tubes and headers/piping will help increase fatigue life in the hot end of the HRSG. Reducing the wall thickness reduces the thermal stresses imposed on the system every time the unit undergoes a temperature cycle...