Natural Gas Engines 1

[syancey]

Due to the abundant supply of natural gas, it seems that natural gas engines are becoming very popular. Not only for electrical power applications but for compressor applications as well. I am curious if anyone out there has hands on experience with large (1500hp and up) natural gas fired reciprocating engines? If so, I would like to open up a discussion on the benefits of natural gas powered engines and some of the problems directly related to using natural gas as an energy source. I have currently been involved in three projects, two in the Sates and one in Canada. All three were quiet unique and challenging. One project involved 10 engines, each producing 4.2 MW of electricity. My area was delivering the natural gas at the right volume and pressure. Sounds easy. Not so. The project was a stand alone (off the grid) and was the adjacent plant so provider of electrical power. The power requirements would vary from 4-35 MW. And this could happen instantly. The idea was to keep the gensets from tripping out and bringing the whole plant down. Can you image synchronizing 10 gensets? And keeping them synchronized with 4 to 10 MG step changes? Anyway I would welcome anyone with similar experience or problems. <br>
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Steve Yancey<br>
King Mechanical

 

[FireLover]

I have experience with automotive natural gas engines (SI 4 stroke). That is a different kind of animal than gen sets though. Seems gen sets have only a few operating points, and the challenges are very fast transients between these operating points. In automotive, there are nearly an infinite number of operating points (rpm vs load), with transients and cold starts being somewhat of a challenge. The highest rating I worked on was 300 Hp @ 2100 rpm / 900 ft-lbs @ 1200 rpm from a 10 Liter I6 Turbocharged engine.

A big issue was dealing with the quality of the fuel. Natural gas can mean a lot of things! This had a big impact on performance, combustion quality, etc. Oil in the fuel was also a problem, in terms of fuel system durability. I wonder if this has been a problem in your projects.

As far as knock, you never had to worry about that with NG, since it is hard to ignite anyway. Getting the fuel to the engine wasn't really a problem since automotive stored it at 3600 psi. But driving range was, it is just hard to store gaseos fuel.

 

[jmw]

The point about gas quality is one that interests me. &quot;Natural&quot; gas quality varies according to source so when it is shipped to consumers they depend on consistent quality if their ovens, central heating ect aren't going to do something unexpected, dangerous and expensive. This means the gas is blended. Among other things this can mean using relative density measurement as a means to determine the wobbe index/calorific value etc as a real on line process measurement. In gas blening stations the measurement is part of the blend control set-up. I am interested in its application to measuring the quality of the fuel gas (natural, bio VOC etc) for use as an engine control parameter. If anyone knows something about that, please be heard. Otherwise i'll be interested to discover if fuel gas quality variation is one of the problems you have documented.

 

[evelrod]

On the way into town this morning, I noticed a little blue diamond with LNG in it on the rear bumper of every state/gov't. car that I saw (several). Would this indicate that the state of California has figgured out how to make this combo. viable? (CA is NOT noted for doing things right the first time, you know)



Rod

 

[jmw]

LNG, LPG, good ideas but.....
LPG is quite common in parts of Europe. In some countries cars must be dedicated to LPG or to petrol as a fuel and in others they can be dual fuelled.
In the UK, you might have a long walk between gas stations and what kind of can do you have to have take your fuel back to the car in? LPG was seen as a nice cheap and clean fuel but the big suspicion was that if any one started to use it seriously then wham! up goes the fuel tax...
Why am i unsurprised that people don't trust government?