What are methods for Gas cooler tubes washing in CNG station? 2

[molana2011]

We use reciprocating compressors in the CNG station for providing fuel of automobiles. There is some oil on the gas cooler tubes (inner surfaces) and we want to clean and remove these oil (it is possible for oil leak to these coolers from compressors). What are methods for cleaning and washing the oil on the tubes? What's the best method?

 

[molana2011]

material tubes: carbon steal

 

[molana2011]

Material of tubes: carbon steel

 

[maddocks]

steam jet, water lance, chem wash, solvent wash,

 

[molana2011]

what kind of chemical or solvent is propper for this application.
waht is the condition(percent, purity, temp., ...)?

 

[pmover]

molana2011,

cleaning fouled gas cooler tubes for a CNG station is not that complicated. the CNG is clean gas; however, the recip compressor apparently has oil carryover. is the oil cooked onto the tubes? suggest you conduct simple tests as to which method as mentioned by maddocks will effectively remove the oil. you may also consider contacting the oil supplier and asking how best to remove the oil. you may also want to investigate the cost of a replacement gas cooler (compare with cleaning costs); therefore, the clean gas cooler can be installed while the fouled cooler is undergoing cleaning.
lastly, the oil carryover is not acceptable and suggest you investigate the source of oil contamination [oil feed rate to cylinders (if applicable) and adjust if needed] and make the needed corrections. it seems there is a problem at the compressor. a coalescing filter may also be considered between the compressor and cooler for removal of oil if the oil carryover cannot be stopped. perhaps a non-lubricated compressor needs to be considered.

hope this helps.
-pmover

 

[molana2011]

if we want to clean th tubes with chemical solution, what is the best method? what is best chemical?

 

[maddocks]

There are a couple of options but you should talk with a chem wash supplier. Best option is to take a lube oil sample to your chem wash guys and have them build up a program. Here's my random thoughts:

1.) A toluene wash will help to dissolve lube oil.
2.) Methanol is a good solvent if the lube oil is synthetic.
3.) You could use a caustic followed by neutralizer and then followed by water, but if there is any sulphiding of the tubes, this will scrub that off as well and may loosen up some dirt, rust, gunk, etc.
4.) You may want to consider an acid wash but I'm not the right guy to tell you this.
5.) Heck, you could even see if it dissolves in diesel - a simple hot diesel flush may clean the tubes adequately.

The part I don't know, is how you are going to assess the job and know if you are complete.

 

[molana2011]

maddocks

1- if we select option 3, what is the concentration of caustic?
and what is the nature of "neutralizer"?

2-is it possible to use ethanol for this applicaton? (in contrast with option 2)

 

[maddocks]

I'm honestly not sure on the concentration or even the exact program to be used with caustic - as stated, discuss with a chem wash services supplier in your area.

In theory, you could use ethanol - I think you'd want to do some solubility testing of your compressor lube oil with the ethanol to see what the effect is. The other thing to consider is that residual ethanol (small amounts) in the tubes and header boxes will end up in the gas phase exiting the compressor station. Is this acceptable?

 

[molana2011]

it is not acceptable.
you said in the option 2 " caustic followed by neutralizer"
what is the neutralizer? is it a weak acid or other thing?
if we use caustic, can caustic to remove cooked oil in the tubes?