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amanda121287
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Join Date: Apr 2018
Posts: 1

Packing Vent Temperature of Reciprocating Compressor

04/17/2018 3:51 AM

We are operating the reciprocating compressors of ARIEL JGT/4. They have trip security on the packing vent temperature.

Suction Temperature: 35 deg C

Discharge Temperature: 100 deg C

Alert on packing vent temperature: 121 deg C

Trip on packing vent temperature: 135 deg C

Last week we were facing the problem of high packing vent temerature which reached upto 132 deg C. We replaced the packing and initially the temperature rose to 125 deg C but gradually decreased to 65 deg C. I have following queries;

1- Why the packing vent temperature is higher than discharge temperature when the packing is leaking ? As after passing through packing rings the temperature must drop due to throttling effect, also ideally speaking it may not increase beyond the value of discharge temperature

2- The metal (cast iron) back up ring (radial cut) has zero clearance with the piston rod, what is the rule of thumb about the metal back up ring clearance with piston? As i believe that initial temperature rise is because of rubbing between the ring and piston rod which subsided with passage of time.
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#1

Re: Packing Vent Temperature of Reciprocating Compressor

04/17/2018 5:42 AM

A1) The difference is probably due to measurement errors. 132 or 135? Does it matter (rhetorical question - NNTR)?

A2) It is probably due to the fitting "running in". If there is a <...rule of thumb...>, then the manufacturer is the best source of information. It will be either in the Maintenance Instructions that came with it, or it can be obtained over the telephone direct from the equipment manufacturer, which is always the best source of advice: no-one knows more about the equipment than the original equipment manufacturer, as has been stated in these columns countless times before.

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tonyhemet
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Location: Hemet, Land of milk and honey.
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#4
In reply to #1

Re: Packing Vent Temperature of Reciprocating Compressor

04/18/2018 1:51 AM

Is :

Contact manufacturing plant listed in the cr4 list of things necessary to do, before adding a posting ?
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#5
In reply to #4

Re: Packing Vent Temperature of Reciprocating Compressor

04/18/2018 9:51 AM

Dunno. Ask lyn.

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SolarEagle
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Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
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#2

Re: Packing Vent Temperature of Reciprocating Compressor

04/17/2018 10:10 AM

https://www.scribd.com/doc/293417179/Ariel-JGH-JGE-JGK-JGT-Operating-Manual-Rev-Mar-2011

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rwilliams
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Join Date: Jul 2016
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#3

Re: Packing Vent Temperature of Reciprocating Compressor

04/17/2018 11:55 PM

You may not be accounting for the heat gain of the friction of the rotating shaft on the packing.

That would generally add to the temperature of your product air, which should approximately match the general machine temperature, once the process is in equilibrium. As you surmise, some cooling of the machine frame would be expected, since the major source of the heat in the process is the heat of compression of the product air.

The packing equipment is a relatively small mass compared the the rest of the machine, so just a small amount of extra friction heat could easily translate into higher temperatures.
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