Help needed on Sequence of operation on a Cold-Storage

[sriji]

Respected All,
i am a Automation Control Systems Engineer(PLC,SCADA,VFD..etc) i had undertaken a Control systems Project for a Cold storage Plant, i had 0 experience in Refrigeration Plants,
i need clarifications & advice's on Sequence of operation. configuration of Plant is
1.) 7 Cold-Chambers ( for storing vegetables,Cheese,ice creams,ready to eat products)
2.)3 reciprocating compressors ( 2- KC-42,1-KC-21)
3.)2-WATER-COOLED CONDENSOR
4.) Temperature has to be acheived -30*c
5.) Refrigerant is AMMONIA.

I Need to design the logic for Starting of the compressors based upon SUCTION PRESSURE.
so if anybody can explain me the relation of temperature & Suction pressure.

THANKS for any help

[RANGER1]

sriji, Pressure & temperature are related. A pressure temperature chart is required for ammonia, you should be able to find one on internet. -33deg C = 0kpa pressure. Also suction pressure/temperature have to run colder than lowest required room temperature, so maybe for -30 C room you would have suction at approx. -35 to -36 C suction pressure equivilent

[Brian_UK]

Do not try to re-invent the wheel. Also do you have enough knowledge around you to safely operate NH3 plant?

[sriji]

Do not try to re-invent the wheel. Also do you have enough knowledge around you to safely operate NH3 plant?

Thanks for the reply Sir, i don't have any experience in refrigeration Systems, i have experience in MACHINE AUTOMATION(CNC,SPM,etc..) only,http://www.refrigeration-engineer.com/forums/images/smilies/redface.png i am not able getting a proper support from the Local
Technicians, so i have to learn everything on my own.

[sriji]

Thank you very much for your reply sir, Please forgive me for asking very silly questions, on what basis do i need to start a compressor.

[Brian_UK]

Hello sriji,

There are various methods and schemes I expect, can I point you to some documentation that may help you?

Read some from Danfos which gives descriptions of what there controller read and write to operate compressor and fans etc..
http://www.danfoss.com/Products/Categories/Literature/RA/Electronic-Controls/Electronic-Controls-Compressor-and-Condenser-Controls/Capacity-Control/62269b71-d9a7-414b-99d8-cd2ddde24342.html

[sriji]

Hello sriji,

There are various methods and schemes I expect, can I point you to some documentation that may help you?

Read some from Danfos which gives descriptions of what there controller read and write to operate compressor and fans etc..
http://www.danfoss.com/Products/Categories/Literature/RA/Electronic-Controls/Electronic-Controls-Compressor-and-Condenser-Controls/Capacity-Control/62269b71-d9a7-414b-99d8-cd2ddde24342.html

Thank you very much for your help Sir.