4 questions about gas plant!

[mojex]

I am a junior Chemical engineer. A few days ago an expert natural gas engineer asked me some tricky question to evaluate me, I searched whole internet sites and ebook that I had but no luck! I really apreciate your help. these are questions:
1- Why compressors in gas compressor station have shelter(a roof witt no wall!!!)?! why we need this structure?!
2- take a look at "compressor coverage chart" below. This for compressor type selection, as you know! this is question: if we get to point "A", what should we do? i.e. there are several compressor type available in this area, which one should we choose? (note: we know that the gas flow dosn't have flactuation (it is constant)).

[link Point to another website Only the registered members can access] 3- in vertical gas/liquid separator, the HHL always set to 0.7 (0.7 of seam to seam length), if liquid level reach this value, PSV get action! so, this is question: why it set to 0.7?!
4- (honestly I didn't search question No.4 (This one) in internet. it may be answerd somewhere, sorry for that, but I really disappointed by internet and books about above questions, so I didn't search this one):
He (The senior Natural gas enginner) said that one day he was in gas plant (I don'y know it was normal operaion, startup,shutdown, commissioning or...) and a saw a suited person goes under the shower that locate in all gas plants, tap his shoes on ground and the shower starts working and water wets all his suit. this is question: why he did that?! (Note" there was no chemical solution os ... on his suit or body)

sorry for such a long questions, but i didn't find the answers so i thought that this is the right place to ask, thank in advance for you help.

[mojex]

no one? plzzzzzzzzzzzzzz!

[pikab00m]

my guess for the 1st question is: if the compressor would be put between 4 walls and a ceiling, the vibrations would act like some sort of echo and would damage the whole thing, anything else, I really have no idea.
as for the HHL, maybe it's related to the STAS, search more, good luck and when you're done, tell us the correct answers you found.
See you!

[ColinR33]

Hi Mojex, please see my comments below:

1- Why compressors in gas compressor station have shelter(a roof witt no wall!!!)?! why we need this structure?!
This depends on where they are located. Often a shelter roof only is for shade in hot climates where solar radiation can add significant heat to the process and metal temperatures can reach 80-85C in the sun. It also provides shelter from rain, hail, etc. In colder climates like Canada (where I am), Russia (where I have done a lot of work) the compressors are installed in heated buildings as it is not fun to work on these units in -40C weather, and the operation of the units themselves becomes difficult, requiring substantial heat tracing and insulation. Also, the materials of construction of the compressors themselves and other parts of the package may not be able to deal with the cold temperatures and embrittlement becomes an issue.

2- take a look at "compressor coverage chart" below. This for compressor type selection, as you know! this is question: if we get to point "A", what should we do? i.e. there are several compressor type available in this area, which one should we choose? (note: we know that the gas flow dosn't have flactuation (it is constant)).
Be careful with this chart, I have seen people with no practical experience use it and select the wrong compressor and not understand why no vendors will quote that type, and argue with me for an extended time saying that they want a centrifugal compressor because the chart says that is the correct choice, and yet no vendor will quote it because it is a better application for a recip. A lot of it comes from experience. It is good to check with the vendors themselves about what is the best application. There are many rules of thumb for this.

3- in vertical gas/liquid separator, the HHL always set to 0.7 (0.7 of seam to seam length), if liquid level reach this value, PSV get action! so, this is question: why it set to 0.7?!
Not sure about this, I haven't seen this before. Are you sure you are not referring to the 'K' value? Typically the 'K' value for a compressor suction scrubber is set to 0.7x the value of a regular separator to provide a margin of safety in the design as liquid carryover in this service will result in catastrophic failure of the compressor in most instances.

4- (honestly I didn't search question No.4 (This one) in internet. it may be answerd somewhere, sorry for that, but I really disappointed by internet and books about above questions, so I didn't search this one):
He (The senior Natural gas enginner) said that one day he was in gas plant (I don'y know it was normal operaion, startup,shutdown, commissioning or...) and a saw a suited person goes under the shower that locate in all gas plants, tap his shoes on ground and the shower starts working and water wets all his suit. this is question: why he did that?! (Note" there was no chemical solution os ... on his suit or body)
Could be just to rinse off residue/dirt/asbestos fibres/dust from crawling around, depends on where he was, there are many possibilities here, you would really have to ask the fellow who was under the shower (I have doused myself from fire hydrants to cool off in some plants when the temperature was 54C, not really an approved thing to do but that or heat stroke ;-).

Cheers,

sorry for such a long questions, but i didn't find the answers so i thought that this is the right place to ask, thank in advance for you help.[/QUOTE]

[tokiero]

1st: I guess, just because thats enough, in other words - cost effective solution)))
2nd: In such point you can use everything that you want))) but engineers prefer to taking in account other factors. For example, sometimes, u cant use recip compressor, because u have limited space for installation; or, for example, if u wanna be cost effective, u may decide to use recip, because it has less initial cost (in general).
3rd: just tradition? our industry is quite conservative, as u know))