Gas engine generator & Gas Turbine generator
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dbuckley
Senior Member
- Location
- Canterbury, New Zealand
broadgage
Senior Member
- Location
- London, England
In the USA the term "gas engine generator" is very often used to describe a generator worked by a gasoline engine (petrol engine in the UK)
This may not be srictly correct use of terminology, but is widely used.
In the UK it would normally mean an engine burning natural gas, or propane. Such engines are not very common in the UK, but certainly exist, in the USA they are popular.
A gas turbine engine, similar to an aircraft engine, can burn either light oil, or natural gas. Some can be changed from oil to gas as needed, others are designed for one fuel only.
Gas turbine engines, burning natural gas, are widely used in power plants, they are not normally used in small sizes.
IMHO, in an international context, the term "gas" should be avoided lest confusion be caused.
One should refer to gasoline, or to natural gas, or to propane.
This may not be srictly correct use of terminology, but is widely used.
In the UK it would normally mean an engine burning natural gas, or propane. Such engines are not very common in the UK, but certainly exist, in the USA they are popular.
A gas turbine engine, similar to an aircraft engine, can burn either light oil, or natural gas. Some can be changed from oil to gas as needed, others are designed for one fuel only.
Gas turbine engines, burning natural gas, are widely used in power plants, they are not normally used in small sizes.
IMHO, in an international context, the term "gas" should be avoided lest confusion be caused.
One should refer to gasoline, or to natural gas, or to propane.
Reciprocating prime movers ( gasoline, diesel. propane,natural gas etc.) spin up fast. They can be putting out power in 10 seconds or less.
Gas turbines take longer. Many minutes, longer time the bigger the machine is.
It's the reason you never see gas turbines as standby/emergency power sources.
Gas turbines take longer. Many minutes, longer time the bigger the machine is.
It's the reason you never see gas turbines as standby/emergency power sources.
K8MHZ
Senior Member
- Occupation
- Electrician
Well, all the gas turbine generators I have seen spin at 3600 rpm just like steam turbines and piston engines. They were also huge, like 8 or 10 feet in diameter. I don't think a small turbine could run that slow. Things get much more complex when you are trying to make 60Hz AC with a generator that is not spinning at 3600 rpm, so complex that it is almost non-existent.
That trend may be coming to an end, though, as inverters are becoming more and more popular which allows for the frequency to be determined by the electronics, not the speed of the generator.
K8MHZ
Senior Member
- Occupation
- Electrician
Here is a picture of the gas turbines at the plant I worked at while it was being built:
The four 'small' squares you see are the intakes for the turbines. The bottom of the intake is about 2 1/2 stories high, the top around 6 or 7.
To the far left you will notice a blue building in line with the turbines. There is also a generator in there powered by steam made from the heat of the exhausts of the two gas turbines on the left. It's called a 'Hertzig' or Heat Recovery Steam Generator. (HRSG)
The blades for the turbines, each 5 or 6 feet tall, were cast from nickel based super alloy at the Howmet Casting facility about 35 miles from the plant. I used to work in R&D there at what is now the Operhall Research Facility. We made turbine engine parts for anything from jet fighters to huge land based turbine engines like the ones at Zeeland.
The land in the picture is about 14 of the 30 acres the plant, a peaker, occupies. The turbines are fed by a 16 inch natural gas line. The first day I was at the plant, the line erupted during testing, blew a 10 foot hole in the ground and got the site evacuated.
On a more solemn note, I was working there with a GE engineer from Iraq when we invaded that country. He was stuck here and his family was stuck there. That had to be very rough on the guy.
The four 'small' squares you see are the intakes for the turbines. The bottom of the intake is about 2 1/2 stories high, the top around 6 or 7.
To the far left you will notice a blue building in line with the turbines. There is also a generator in there powered by steam made from the heat of the exhausts of the two gas turbines on the left. It's called a 'Hertzig' or Heat Recovery Steam Generator. (HRSG)
The blades for the turbines, each 5 or 6 feet tall, were cast from nickel based super alloy at the Howmet Casting facility about 35 miles from the plant. I used to work in R&D there at what is now the Operhall Research Facility. We made turbine engine parts for anything from jet fighters to huge land based turbine engines like the ones at Zeeland.
The land in the picture is about 14 of the 30 acres the plant, a peaker, occupies. The turbines are fed by a 16 inch natural gas line. The first day I was at the plant, the line erupted during testing, blew a 10 foot hole in the ground and got the site evacuated.
On a more solemn note, I was working there with a GE engineer from Iraq when we invaded that country. He was stuck here and his family was stuck there. That had to be very rough on the guy.
Last edited:
GeorgeB
ElectroHydraulics engineer (retired)
- Location
- Greenville SC
- Occupation
- Retired
I don't know if it is still true, but many of the GE units (built here in Greenville SC) ran the turbine substantially faster than the generator with gears between. When I worked for Duke Power in the 70's, we had "free turbines" driven by the exhaust gasses of the gas turbine. The gas turbine speed was independent of the free turbine (which was connected to the generator and, IIRC, turned 1800 rpm. Waste heat from the free turbine outlet went to "heat recovery boilers" which made low temperature steam for our OLD steam turbine generators.
K8MHZ
Senior Member
- Occupation
- Electrician
I just realized that a decade has gone by since I was at that plant! The computer that kept everything in phase used MS-DOS 3.1 as an operating system. So what I was working on would hardly be considered state of the art by today's standards.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
You say that as if there was something newer available.
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
ReallY?
ReallY?
Never say never:grin:
I could name (5) in central offices for AT&T in the Bay Area, SF. These are older (>30yrs) installations. They have moved away from using them, don't see any in new installations, usually diesel or
gas.
Pro: a lot of KW in a small footprint.
Cons: designed for continuous running, very maintenance intensive.
TT
ReallY?
Never say never:grin:
I could name (5) in central offices for AT&T in the Bay Area, SF. These are older (>30yrs) installations. They have moved away from using them, don't see any in new installations, usually diesel or
gas.
Pro: a lot of KW in a small footprint.
Cons: designed for continuous running, very maintenance intensive.
TT
robbietan
Senior Member
- Location
- Antipolo City
The GE Frame 6 gas turbines I worked with had a 32 MW capacity with turbines running at 5100 rpm and the generator running at 3600 rpm. The set-up needs only 10 minutes to reach full speed from a "cold start"
ATSman
ATSman
- Location
- San Francisco Bay Area
- Occupation
- Electrical Engineer/ Electrical Testing & Controls
wow, what was the voltage, 12KV?
When I was a new grad off the EE school, I had the chance to work on a European GT; Brown Boveri 11L 15MW, 13.8 kV, single-shaft, 3600rpm unit. The unit ramps up to synch speed in 6-8 minutes and auto-synch to the system immediately!
There is :grin:They just have not told us yet:roll:
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