REFRIGERATION PLANT PACKAGE

Prepared by : Sujeet TambeProcess Design Engineer

CONTENTS :• INTRODUCTION AND BASICS OF REFRIGERATION

• REFRIGERANT SELECTION CRITERIA (ASHRAE STANDARD)

• AUXILLARY EQUIPMENTS IN REFRIGERATION CYCLE

• LOAD CALCULATION (PEAK LOAD AND AVERAGE LOAD)

• PRILIMINARY PROCESS DESIGN

• EQUIPMENT DESIGN AND SPECIFICATION

• SPECIFICATION OF COMPLETE REFRIGERATION PACKAGE

• P & ID TYPICAL REFRIGERATION PLANT

• START-UP AND SHUT-DOWN

• TROUBLE SHOOTING AND CHECKLIST

INTRODUCTION AND BASICS :

Thermodynamic principal : It’s a process of removing heat from lower temperature level to higher temperature level.

Applications : Air conditioning, Food industry, Chemical industry, Space science.

Classifications : i) Vapor compression (mechanical) ii) Vapor absorption iii) Steam ejector

INTRODUCTION AND BASICS : Refrigeration capacity :

1 tonne of refrigeration is the rate of heat removal required to freeze a metric ton (i.e., 1000 kg) of water at 0 °C in 24 hours. Based on the heat of fusion being 333.55 kJ/kg,

Capacity calculation :

Q = m x Cp x (Tin – Tout) kcal/hr

INTRODUCTION AND BASICS :

INTRODUCTION AND BASICS :

REFRIGERATION SELECTION CRITERIA :

I. A high latent heat of vaporization

II. High density of refrigerant gas

III. Non corrosive, Non toxic and Non flammable

IV. Critical temperature and triple point outside the working range

V. Environment friendly

VI. Ease of leakage detection

VII. Low cost

Choice of the refrigerant should be made considering following criteria

REFRIGERATION SELECTION CRITERIA :

I. All CAFs (chlorofluorocarbon), bromides are harmful to the ozone layer So all the CFCs to be phased out by 2030

ASHRAE classification

I. As per ASHRAE/ANSI standard 34-197 First digit on the right side is the no. of fluorine atoms Second digit from right is one more than the no. of hydrogen atoms Third digit from right is one less than the no. of carbon atoms

REFRIGERATION SELECTION CRITERIA :

I. All CAFs (chlorofluorocarbon), bromides are harmful to the ozone layer So all the CFCs to be phased out by 2020

ASHRAE classification

REFRIGERATION SELECTION CRITERIA : ASHRAE classification

AUXILIARY EQUIPMENTS : CIRCUITS IN REFRIGERATION CYCLE

I. Chilled water circuit

II. Refrigerant circuit

III. Oil circuit

IV. Cooling water circuit

AUXILLARY EQUIPMENTS:

• CHILLED WATER CIRCUIT : Chilled water pumpsChilled water tanks

• REFRIGERANT CIRCUIT : Compressor Refrigerant condenser Refrigerant receiver

Economizer Expansion valveRefrigerant evaporator (chiller)Accumulator

• OIL CIRCUIT : Oil coolerOil seperatorOil heater

COOLING WATER CIRCUIT : Cooling water pumpsCooling tower

LOAD CALCULATION (PEAK LOAD/AVERAGE LOAD):

REFER THE EXCEL SHEET FOR SAMPLE LOAD CALCULATION

PRILIMINARY PROCESS DESIGN

REFER THE EXCEL SHEET FOR SAMPLE PROCESS DESIGN CALCULATION

SPECIFICATION OF COMPLETE REFRIGERATION PACKAGE

REFER THE SAMPLE REFRIGERATION SPECIFICATION

P & ID

PRE-OPERATIONAL CHECKS

• Make sure there is sufficient water in the cooling tower.

• Condenser water inlet and outlet valves of the pumps are fully open.

• Chilled water pump inlet / outlet valves are fully open.

• Check the electricity supply.

• The oil level in the oil separator is above normal operating level.

• Oil separator outlet and compressor outlet valve are full open

• All valves in refrigerant circuit is full open.

• Ensure free moving of all the motor shaft.

START-UP PROCEDURE

• Switch on the main incoming switch in refrigeration plant.

• Switch on compressor PLC panel, which you want to run. Ensure emergency push button is released.

• Switch on the main panel and select Auto / Semi auto / Manual mode in PLC main panel.

• For manual selection all the motors have to be started individually.

• Switch on the cooling tower fan

• Switch on any 2 cooling water pumps.

• Switch on any 2 chilled water primary pumps.

• Initially when the chilled water temperature is same as ambient, try to bypass the process so that pull down time can be reduced.

• Start the compressor motor.

• Keep watch on the suction pressure, discharge pressure and oil pressure.

• Minimum pressure difference should be maintained for normal operation or compressor will trip.

• Manully unload the compressor gradually and bring down to 30%, eventually compressor will get tripped.

• In auto, go to main PLC panel and press ‘plant stop’.

• Close the compressor suction valve to tight shut off.

• Stop the cooling water circulation.

SHUT-DOWN PROCEDURE

TROUBLESHOOTING

(1) SUCTION PRESSURE LOW

TROUBLESHOOTING

(2) OIL DIFFERENTIAL PRESSURE LOW

TROUBLESHOOTING

(3) LIQUID LEVEL HIGH (ACCUMULATOR & ECONOMIZER)

DAILY CHECKLIST

• Check suction, discharge oil, economizer pressure and temperature.

• Check oil level in oil seperator.

• Check motor FLA for compressor and all the motors.

• Check condenser water in and out temperature.

• Check receiver liquid level.

WEEKLY CHECK LIST

• Check the oil level in the oil seperator. The oil level should be in the top of bottom glass.

MONTHLY CHECK LIST

• Lubricate the pumps and motors as per the manufacturer s instruction manual

PROCEDURE OF REPLACEMENT OF OIL

• Unload the compressor to minimum capacity if in the operation.

• Close the compressor suction valve and allow the compressor to trip on low suction pressure.

• Close the oil seperator outlet valve.

• Completely isolate the oil seperator and oil cooler and then start draining the dirty oil a container.

• Clean the strainer and filters and if necessary replace it.

• Top up / replace the oil and pressurize the system again.