KOBELCO COMPRESSOR

GENERAL DESCIPTION

OUTLINE

Oil free compressed air is delivered from “AL”, the package type screw compressor unit, which includes two compressor elements, coolers, silencers, motors and a controller, etc. two compressor elements, the 1st and the 2nd stage elements, are speeded-up to their optimum speed respectively by the gear apparatus driven by the electric motor.

Free-air sucked from the inlet of the unit passes through the suction filter and is compressed to about a pressure of 2 kgf/cm2 G in the 1st stage and to the delivery pressure in the 2nd stage.

To cool down the compressed hot air the intercooler and the aftercooler are installed between the 1st and the 2nd stage, and after the 2nd stage respectively. Also, to cool down both stage elements, water jackets are used in their casings. The male and the female rotors are supported by ball and roller bearings in the 1st and the 2nd stage elements, and each rotors are synchronized by a pair of timing gears.

The lubricating oil is injected into these bearings, timing gears and speed-up gears through the oil cooler and the oil filter. The oil comes from the oil tank by the oil pump which is driven by the motor “M-2”. The quantity of the delivery air is controlled by the capacity control valve using an automatic close and open.

MAIN LINE FLOW

The suction silencer “S-1”, the suction filter “F-1” and the capacity control valve “CV-1” are installed in the air line before the 1st stage. The suction silencer minimizes the noise which comes from the 1st stage element through “CV-1”. The suction filter has the ability of straining dust which is larger than approximately 10 microns. Loading of this filter is indicated by a red field in the dust indicator “DI-1” which is on the front gauge board. The system of the thermocouple “TE-1” and the temperature switch “TIA-1” senses and indicates the air temperature leaving the 1st stage.

This system sends an “alarm” signal to the controller when this temperature rises more, “AL” stops immediately. The moisture, which is generated in the process of cooling down the hot compressed air through the intercooler “H-1”, is separated by the drain separator “DS-1” and gathered in the drain trap and automatically drained. The pressure and the temperature of the cooled air, after the intercooler, are shown on the pressure gauge “PI-1” and the temperature gauge “TI-4” on the front gauge board. The pressure of this cooled air, of about 2 kgf/cm2G, is used to act the balance piston in the 1st stage element and the capacity control valve.

After leaving the intercooler the cooled air is compressed to the delivery pressure in the 2nd stage. The hot compressed air leaving the 2nd stage passes through the silencer “S-2” and the check valve “V-1” and is cooled down to about 10°C plus the supplied cooling water temperature through the aftercooler “H-2”.

AIR FLOW DIAGRAM

C-2 2ND Stage comp.

CV-1, 2 Capacity control valve

H-1 Intercooler

H-2 Aftercooler

DS-1, 2 Drain separators

Ad-1, 2 Drain trap

SI-4 Silencer

F-1, 3 Filters

SV Safety valve

SHV Shuttle valve

SOL 4-Way solenoid

PA-4 Disch, press. switch

TIA-1, 2 Disch. Temp. switch

TE-1, 2 Thermocouple

DI-1 Dust indicator

The system of the thermocouple “TE-2” and the temperature switch “TIA-2” senses and indicates the air temperature leaving the 2nd stage. This system sends an “alarm” signal to the controller when this temperature is too high, and when this temperature rises more, “AL” stops immediately. Some of the compressed air after the 2nd stage is led to the balance piston in 2nd stage element. The moisture generated in the aftercooler is separated by the drain separator “DS-2” and gathered in the drain trap and automatically drained.

The discharge pressure of the 2nd stage is indicated on the pressure gauge “PI-2” on the front gauge board. The 4-way solenoid valve “SOL” works to close the capacity control valve “CV-1” and to open the valve “CV-2” receiving the signal from the discharge pressure switch “PA-4” when the discharge pressure rises up to the preset max. pressure. As a result, the enclosed air, between the check valve and the 1st stage, bleeds off to the atmosphere through the valve “CV-2” and the silencer “S-3”, and “AL” is UNLOADED. Switching over the 3-way valve “v12” “v13” makes it possible to inspect the inlet and outlet pressure of the intercooler and the aftercooler.

OIL LINE FLOW

The oil pump “GP” driven by the motor “M-2” supplies lubricating oil to the gear apparatus and both stage elements from the oil tank “OT”. The strainer “ST” installed on the inlet line of the oil pump form dust. The oil is filtered by the oil filter “F-2”, and cooled down through the oil cooler “H-3”. The relief valves “PV-1” and “PV-2” are attached to the gear casing and regulate the oil pressure approximately 2 kgf/cm2. Normal oil pressure is from 1.6 to 2.5 kgf/cm2.

OIL FLOW DIAGRAM

C-1 1st stage compressor

C-2 2nd stage compressor

M-1 Main motor

M-2 Motor, oil pump

GP Oil pump

OT Oil tank

ST Strainer

F-2 Oil filter

H-3 Oil cooler

PV-1, 2 Relief valve

B Breather

TE-3 Thermocouple

TIA-3 Temp. Switch

PA-5 Oil pressure switch

PI-3 Oil pressure gauge

LG Oil level gauge

The system of the thermocouple “TE-3” and the temperature switch “TIA-3” senses and indicates the oil temperature leaving the oil cooler. The system sends an “alarm” signal to the controller when this temperature rises up to 60°C and when this temperature rises up to 65°C, “AL” stops immediately. The oil pressure is indicated on the oil pressure gauge “PI-3” on the front gauge board. The oil pressure switch “PA-5” works to stop :AL: when the oil pressure drops below 1.5 kgf/cm2. The breather “B” is attached in the end of the oil filling pipe to make smooth the oil returning flow to the oil tank from both stage elements.

WATER LINE FLOW

The supplied cooling water runs in the following lines:

a) Oil cooler - 1st stage – 2nd stage b) Intercooler c) Aftercooler

The flow switch “FS”, and the water temperature switch “TA-6” are installed in the line of a), and stop the compressor when the water flow rate is not enough. Needle valves “V-7” and “V-8” are installed in the line of b) and c). The valve “V-7” is very important to keep the air temperature leaving the intercooler, i.e. 2nd stage suction temperature to prevent generation of moisture which is harmful for the 2nd stage element.

COOLING WATER FLOW DIAGRAM

C-1 1st stage compressor

C-2 2nd stage compressor

H-1 Intercooler

H-2 Aftercooler

H-3 Oil cooler

FS Flow switch

TA-6 Temperature switch cooling water

SAFETY DEVICES

Safety devices are complete to protect “AL” from critical operation.

NAME CAUSE RESULTTemp. switch (1) 1st disch. Temp. rises up to the preset temp. Prealarm shut downTemp. switch (2) 2nd disch. Temp. rises up to the preset temp. Prealarm shut down

Temp. switch (3)Oil temp. rises up to 60°C PrealarmOil temp. rises up to 65°C Shut down

Press. switch Oil press. Drops to 1.5kgf/cm2 Shut downSafety valve Disch. press. rises up to the preset press. Air spouting

Thermal relay for oil pump Over current Shut down

Thermal relay for fan Over current Alarm

Thermal relay for compressor

motorOver current Shut down

Coil thermoswitch,

compressor motor

Over current Shut down

Flow switchCooling water shortage

Shut down

Temp. switch Shut down

SAFETY DEVICES TABLE

NAME INDICATION MAINTENANCEDust indicator Red indicator appears at full range Cleaning or exchange of

suction filter elementOil level gauge Transparent gauge Keep oil level between

“MAX” and “MIN”Drain trap Transparent bowl Check that condensation is not

stagnant

DEVICIES FOR MAINTENANCE

3

1

4

2

5

1) 1ST discharge pressure gauge 2) 2nd discharge pressure gauge3) Oil pressure gauge 4) Dust indicator 5) Thermometer (2nd suction temperature)

6

14

7

8 9

11

13 12 10

6) Hour meter for running time 7) Load counter 8) Hour meter for loaded time 9) 1st discharge temperature switch 10) 2nd discharge temperature switch 11) Oil temperature switch 12) Lamp test switch 13) Reset switch 14) Bell cancel switch

MAINTENANCE

DAILY OR WEEKLY 1) Make records of operation condition of “AL” by filling up the Table in next page.

It helps to find disorder easily and to locate the cause of it readily. 2) The temperature of compressed air between the intercooler and the 2nd stage

element, i.e. the 2nd suction temperature indicated on the “T1-4” thermometer should be approximately 15°C above the atmospheric temperature by adjusting the valve “V-7” to prevent the 2nd stage element from corrosion caused by the moisture generated in the intercooler. This temperature can be raised by throttling “V-7”, but it shall not exceed 60°C in any case.

3) Check that condensation is not stagnant in the transparent bowls of two drain traps and working interval of traps is 1-2 seconds. In the case of stagnation, turn the adjustment screw clockwise.

4) Open the cooling water outlet valve outside the unit completely provided by the user. Adjust the temperature rise of cooling water through the unit to about 10°C by the cooling water inlet valve outside the unit. Cooling water supplied temperature and pressure shall not exceed 35°C and 5kgf/cm2 respectively.

5) Check that the oil pressure is about 2 kgf/cm2 by the pressure gauge “PI-3”. It is adjustable by turning the hex. Bolt which appears by taking off the cap of the relief valve “PV-1” in front of the gear apparatus. Turning it clockwise makes oil pressure up, but it shall not exceed 2.5 kgf/cm2.

6) Check the dust indicator “DI-1” during loading. If the red cylinder in it appears completely, clean or exchange the suction filter element for new one immediately, but never remove it during operation.

7) Check the level of oil in the oil tank by the level gauge “LG”. Always maintain it just under the “MIN” line or rise above the “MAX” line.

8) Check that the air temperature around the unit is below 40°C, ventilate the compressor room sufficiently.

9) Check that the air pressure switch unloads “AL” at equal to or less than the design pressure indicated in the data plate on the rear door of the unit. Check that an unloading interval (time between one unload and next unload) is not shorter than 45 seconds. The shorter it is, the more the number of action of the capacity control valve, the 4-way solenoid valve and the check valve consequentially the shorter the life of them.

ITEMS NORMALDust indicator Not red field at all1st discharge

pressure 1.9-2.7 kgf/cm2G

2nd discharge pressure (MAX) Under 7

1st discharge temperature

(MAX)Under 210

2nd suction temperature Max. 60°C

2nd discharge temperature

(MAX)Under 200

Oil temperature Under 65

Oil pressure 1.6-2.5 kg/cm2

Oil level Between “MAX” and “MIN”

Atmospheric temperature Max. 40°C

Cooling water inlet

temperatureMax. 35°C

Cooling water inlet pressure Max. 5 kgf/cm2

Working interval of drain

traps1-2 second

RECORD OF OPERATING CONDITION

EVERY SIX MONTHS OR LESS

1) Regrease to the main motor regularly in accordance with the caution plate on the unit cover. Type of grease shall be “SHELL ALVANTA No.2”.

2) Clean the top cover of “AL” and the main motor.3) Remove and inspect the suction filter element during stopping and service it, if

necessary. 4) Remove the breather element and wash it in cleaning solvent and dry it

completely. 5) Inspect all pipes, tubes and hoses. Replace the damage parts and retighten leaking

connections. 6) Drain condensate in the control air filter “F-3” by turning the knob at the bottom

counterclockwise during loading operation.

EVERY YEAR

1) Dismantle two drain traps and clean the parts in them. 2) Inspect the coil-spring and the pin the check valve “V-1”. Exchanger the check valve

assembly for new one if the “LOAD COUNTER” indicates the number more than 500000 for one year.

3) Test that the safety valve works accurately. 4) Replace the diaphragm, v-packings and the Teflon seat, and inspect the sleeve bearings in

the capacity control valve. 5) Check the operation data recorded by the user and judge whether the cleaning of the

water side of coolers is necessary or not. Chemical cleaning is the best way and renews tetoron hoses in the water line after this cleaning. Never forget to fasten again the hose bands after 30 minutes operation in this case.

1) Drain separator “DS-1”

2) Aftercooler “H-2”

1

2

1) Control air filter

2) Oil cooler

1

2

1) Temperature switch cooling water 2) Discharge pressure switch 3) Oil pressure switch

1) 1st stage element 2) Breather

1

3

2

1

2

1) 2nd stage element

2) Thermocouple

1

2