Gas Turbine Configuration 2

[morojlu]

Dear all
As there is no specific standard regarding the distance between Gas Turbines in a power plant what distance is regularly considered for various models and sizes of Gas Turbines?

Thank you

 

[rmw]

That is kind of like asking 'how high is up?'

Among other things that have to be considered is the configuration of the GT itself. Does it have parts or components that have to have side clearance in order to be removed? Such as an oil cooler Hx bundle.

How about the ability to get cranes, cherry pickers, etc., in between the units in the absence of an overhead crane so as to be able to lift major components, turbine casings, compressor housings, starting devices, etc., out during maintenance.

Lots of things to consider, many of which would be easier to answer if we were to know what types and styles of GT's that you were needing information on.

rmw

 

[abeltio]

besides the maintenance considerations indicated by rmw...
consider the predominant wind, and be careful if the units are installed in-line... like this:
inlet1-exhaust1 -- inlet2-exhaust2 -- inlet3-exhaust3
----> wind

if the predominant wind is as shown by the arrow... part of the exhaust of unit1 will be sucked into unit2...etc.

it has happened.

another consideration for the space is the removal of the generator field which is always done pulling it from the generator.

sidewise... need to consider the location of the crane AND the flatbed truck to seat the rotor in if required.
also, the sides of the unit become the laydown area for the parts removed...
consider removing the roof as well if the unit is packaged.

btw... the best installations i have ever seen had the units INSIDE a building.
the amount of maintenance saved (weather protection) and the ability to perform maintenance under any climate offset the initial cost.
and when such a building is there... the overhead crane comes in naturally...
unfortunately... a lot of plants are designed and built to be cheap in the sale price... but once the other factors are considered... the concept of most CONVENIENT design and not CHEAPEST design becomes obvious.




saludos.
a.

 

[yates]

Although all the guys have given very good reasons for calculating gas turbine separation, when they are installed parallel in a power plant, the incompressible distance is usually given by specified clearance between high voltage phases at transformer output.

 

[PatrickMorton]

The greatest resource for answering this question is the actual manufacturer of the equipment. They will provide the minimum space required for servicing, as well as, what is required for effective operation.

 

[abeltio]

patrickmorton,
sorry, i beg to differ.
the oem's are usually struggling to present a project that will sell.
real estate comes at premium prices in most places... so there is a lot of pressure to minimize the footprint of the plant... although deep inside the designers know that the maintenance crew will be sending "greetings" to their female ancestor in the first degree for many years to come.

the best plants that i've seen were designed with long term maintainability in mind by educated owners (or responsible consultants).

cheers.


saludos.
a.

 

[PatrickMorton]

abeltio,
I do agree that the best design criteria would come from the end user but that was not the question. The question was in regard to a standard or required spacing between units and that information would come from the OEM as for their requirements to ensure the proper operation (i.e. airflow requirements) and the successful maintenance.

The designer is at liberty to place the units in any configuration they desire, however, it will be the OEM that will dictate if the location and spacing fit within their design parameters to meet operational performance.

Regards,

Patrick

 

[abeltio]

there are standards (or regulations) of course for minimum distances:
between stacks and inflammable materials
for risk of explosion
between high voltage equipment
between gas turbines and public roads (local standards)
between gas turbines and urban areas (local standards)
the last 2 based on allowable noise levels.



saludos.
a.

 

[norzul]

Just to add & for sharing purpose. We had procured 4 GTs for our cogen project. Had lengthy discussion with OEM on the safe distance requirements. As mentioned by the OEM (GENP), the formula that they normally use is 1.5 X DH

DH = (2 X H X W)/(H+W); H = Height of GTG air intake; W = Width of GTG air intake. For example, if H=W=5 m, then
DH=(2X5X5)/(5+5)=5m; Hence, safe distance = 1.5 X 5 = 7.5m.

It means that there should not be any physical obstruction (e.g. pipe rack, stuctural, etc) in front of the air intake.

For the side physical obstruction, the formula is DH/2 i.e. 2.5m.


In addition to the above, we also faced an issue regarding close proximity of the cooling tower to the GTG. This will of course affect the GT performance by:-

1) increasing inlet air temperature (less the air density less the GT net power)
2) increasing inlet air RH. The RH level will be not reduced by any installed droplet catcher or coalescer stage. High RH level will cause sensitive dust collected in the high efficiency filter stage to expand, or swell reducing the free area available for air to pass through. This reduced permeability, in turn, increases the restriction that the air filters impose on the turbine airflow (higher pressure drop). Furthermore some contaminants may chemically react with humidity increasing again pressure drop. Salt will deliquesce, too.
3)drift loss. This should be minimised installing a high-efficiency drift eliminators in the cooling tower. The GT filter house will be provided with its own drift-eliminator and coalescer stage to minimise droplet carry over. But finest droplets will generate again a higher pressure drop.
4) Furthermore additional problems may arise. Is the water safe? What chemicals are used? What microorganisms are in the water? Mist landing and then drying on steel surfaces can pose corrosion problems, too.

For this issue, the OEM's (GENP) recomendation is to locate cooling towers as far from GT inlets as possible and to avoid to have cooling towers located directly upwind of the GTG, in the prevailing wind direction.

In our case the distance is about 100m and not in the direction of prevailing wind.