NATURAL GAS COMPRESSOR 1

[kalizzy]

Hi!
Im starting a new project completely different to what i m used to do, It is a natural gas engine, turbocharged, 2300 HP, 16 V-cylinder. The associated compressor is a reciprocating type, two-stage, double acting, four cylinders per stage. So the motor fuel is natural gas and the purpose for the compressor is to "compress" natural gas for a gas pipe. I m having doubts:
1. I've been reading about API 618 and API 11P, i m not sure what standard is applicable for my compressor. It's quite confusing.
2. My work is to support in the development of the spec and data sheet for buying this equipment, but i really have no idea about this topic because i always worked with pumps, no compressor. is there any reference, page, handbook or something to guide about this?
3. Im concerned about the moc (materials of construction) too, is there any standard applicable?
4. At the moment is the only information we have as long the buyer stablish their op. conditions and so on, but i'm triying to involve first in this topic to give my best when the project will be developed.

Thanks in advance!! Your precious experience is always gratefull

 

[LittleInch]

Well you know how to start big.

But need some more info here.

1, what's your pressure ratio? (i.e. why a mother of a reciprocating compressor)

What's your "gas". Dry sales gas or some other gunk coming straight off a first stage separator full of nasties?

That will determine the best specification to use.

Try goggling af ew vendors websites and reading anything they give out as design guides or brochures.

I'll be honest here - this sounds like something you need to fess up to and say you just don't have the experience and knowledge to successfully deliver something worth millions of dollars or employ a company that does. There will be many things you just don't know and are then at the mercy of vendors who don't care.

 

[kalizzy]

Hey, thanks for your reply!


Yes, I understand the lack of information, and I’m working on completing it.


The natural gas comes from a liquefied system. The objective is to compress natural gas for a pipeline used in domestic applications or similar purposes.


Thanks for the advice! However, it's important to mention that the selection, sizing, and other technical decisions are not my responsibility. As a junior engineer, I’m not able to handle this project on my own. I’m part of a team full of senior engineers, but sometimes it’s challenging to ask everything from the start, especially when you don’t have enough experience to fully understand the project.


I’m looking for some reference materials to better understand what’s happening in the project.

 

[Snickster]

I was lead mech for project to install 4450 Bhp natural gas compressors with natural gas recip engine about 25 years ago in Larose La, and another project to install a row of four 2200 HP natural gas pipeline compressors and pipeline station near gulf in southern la. a couple of years later. I have all specs and relevant data. I will need to go through my files and post the information later.

 

[Snickster]

Here is specifications and sequence of operation for 4450 HP packaged high speed reciprocating gas pipeline compressor which was installed in an old Enron pipeline compressor station in St. Rose La just north of NOLA.

In regards to your question of API 618 versus 11P, I believe the difference is API 11P states that its scope is for packaged compressor skids in the oil and gas production sector (such as pipeline compressor stations where this was installed) and packaged meaning that they are such a size that they are custom built by a supplier to specifications - compressor, motor and auxiliaries are custom selected for the given operating conditions and assembled onto a skid by a skid supplier. API 618 states scope is for refining, chemical and petro-chemical industries (i.e. plants) and I believe are more pre-manufactured off the shelf type units.

 

[Snickster]

Here is specs for 4 -2200 hp compressor packages for a natural gas pipeline station. This project was after the previous spec project so it was copied from that one and modified which is why it looks very similar.

Also attached is scope of work for installations and SDODR which provides a list of documents required to be submitted for review and approval by the compressor package supplier.

 

[Snickster]

Here are two old Enron Specs for reciprocating gas compressors - one for non-separable integral engine/compressors - and one for packaged mounted separable engine-compressor units. I'm not that familiar with differences in API 618 versus API 11P (we typically used API 11P for upstream pipeline services) but from the following post of Eng Tips it appears that API 618 is an overkill for upstream oil and gas services so API 618 appears a more stringent standard. I think that as you get into the very large horsepowers like 2000 plus which you see in transmission pipeline compressor stations, you can only get a packaged system where driver and compressors are separate structures. Try doing a search of "API 618 versus API 11P"

Reciprocating Compressors: API618 or not?? - Gas compression engineering

Hello everyone, I am responsible for developing a set of Rotating Equipment standards for my company. The standards shall be suitable for use on all our onshore upstream oil & gas facilities (brownfield and greenfield). Currently we are operating a mix of both med/high speed short throw recips...

www.eng-tips.com

 

[Snickster]

Here is a good little discussion on reciprocating compressors from Dresser Rand

 

[Snickster]

Here is another compressor project specification to API 11P and an issued for purchase Rev 1 of one of the specs I had previously attached so it has most up-to-date information. If you think you might want to go with API 618 I may have a go-by spec for that too.

 

[LittleInch]

Hey, thanks for your reply!


Yes, I understand the lack of information, and I’m working on completing it.


The natural gas comes from a liquefied system. The objective is to compress natural gas for a pipeline used in domestic applications or similar purposes.


Thanks for the advice! However, it's important to mention that the selection, sizing, and other technical decisions are not my responsibility. As a junior engineer, I’m not able to handle this project on my own. I’m part of a team full of senior engineers, but sometimes it’s challenging to ask everything from the start, especially when you don’t have enough experience to fully understand the project.


I’m looking for some reference materials to better understand what’s happening in the project.

Ok, that makes it clearer. From your OP I thought you were trying to do all this yourself...

So is this re gassified LNG? If so it will be virtually pure methane and VERY dry. You will need to tell all the vendors, valve suppliers etc about that as seals and elastomers can dry out or lose lubrication when transporting re gasified LNG.

Snickster has given you some excellent reading material and these large piston compressors are not to be played with. Get it wrong and the consequences are significant.

 

[georgeverghese]

You're off to a good start, this gas is probably not at or below water or hydrocarbon dewpoint.
Pistons with labyrinth type piston rings last much longer than those with conventional piston rings, but such machines carry a CAPEX premium, but these payoff very well in the long run with increased reliability and minimal maintenance.
Pay attention to the disposal of leak gas past the stuffing boxes, process controls. Acoustics analysis would be in vendor's scope, but your mechanical engineers may need to insist on some details.
Keep compression ratio on the conservative low side, say 2.1 to 2.2. For the cheaper piston ring type design, you'll need some allowance on temp creep to TSHH as these rings / liners wear out. Air cooled interstage coolers are much more reliable than nasty open loop cooling water operated units.
PS :
(a)Insist on removable cylinder liners, they often wear out unevenly.
(b)2300hp may be ISO rating, so what is site rating and have you got a fouling margin ? - 10% on site rating would be good, industry practice on gas engines however, is nil if I remember correctly.