1. Air end(compressor unit) 2. Air inlet system
3. Air discharge system
4. Cooling and lubrication system 5. Control system
6. Electrical system 7. Safety system 8. Instrument panel.
AIR INLET SYSTEM:-
It consists of a dry-type air filter, a restriction gauge and an air inlet valve. The butterfly type air inlet valve directly controls the amount of air-intake into the air-end in response to the operation of the silicon control.
DISCHARGE SYSTEM:-
The compressor discharges the compressed air-oil mixture through a discharge check valve into the combination receiver-sump. The
discharge check valve prevents air in the receiver from returning to the compression chamber after the machine has been shut down.
RECEIVER SUMP:-
It has got three main functions
1. Acts as the primary oil separator 2. Serves as the compressor oil sump 3. Houses for oil separator element
Oil collected at the bottom of the separator is return to the compressor by a pressure difference between the separator and the compressor inlet. The pressure drop across the separator element shows more than 15psi the separator element needs replacement.
MINIMUM PRESSURE VALVE:-
A minimum pressure valve is located at the downstream of the separator (just above the sump) assures a minimum receiver pressure of 3-4kg/cm2 during all conditions. This pressure is necessary for proper air-oil separation and to assure proper air-oil circulation in the system.
CHECK VALVE:-
It is located after minimum pressure valve to prevent compressed air in the service line from bleeding back into the receiver on shutdown and during operation of the compressor in an unload condition.
PRESSURE RELIEF VALVE:-
It is located at the wet side of the separator. It will release sump pressure if the sump pressure exceeds 2.5kg/cm2 more than that of compressor working pressure.
HIGHER PRESSURE SHUTDOWN SWITCH:-
The purpose of compressor is to shutdown the compressor at 2kg/cm2 more than that of working pressure. It prevents the pressure relief valve from opening under routine conditions, thereby preventing oil loss through the pressure relief valve. A temperature switch will also shutdown the compressor if the discharge temperature reaches116oC.
BLOW-DOWN PRESSURE SWITCH:-
It senses service line pressure when the line pressure reaches a pre-set valve pressure switch signals the solenoid valve to unload the machine.
BLOW-DOWN VALVE:-
Blow-down valve vents sump pressure to the atmosphere during unloading and shut off.
SILICON CONTROL:-
Regulates the amount of air required to the compressor through air intake manifold of the air-end. This regulation is determined by the amount of air being used in the service line.
THERMAL VALVE:-
It regulates the temperature of oil getting into the air-end by by-passing the same to oil-cooler in case the temperature of oil exceeds preset value.
COMPRESSOR COOLING & LUBRICATION SYSTEM:-
Oil flows from the bottom of the receiver/sump to the thermal valve. The thermal valve is fully open when the oil temperature is below preset temperature. The oil passes through the thermal valve, main filter,
bearing filter and to the compressor unit where it lubricates, seals and cools the rotors and the compression chamber.
As the discharge temperature rises above preset temperature due to heat of compression the thermal valve begins to close and a portion of the oil then flows to the cooler for cooling. From the cooler the oil passes to compressor unit through filters.
NOTE: The pressure in the receiver/sump causes flow of oil from the high pressure area in the sump to an area of lower pressure in the compressor unit.
BEARING FILTER:-
It has a replacement element and an integral pressure by-pass valve. When the pressure drop exceeds 5 kg/cm2 the filter needs servicing.
OIL STOP VALVE:-
The oil stop valve prevents oil flow to compressor when the compressor is shut off. When the compressor is operating, the oil stop valve is held open by the pilot pulse from the air end allowing a free flow of oil from the receiver/sump to the air end. On shut-of, the air end pressure gets reduced significantly causing the oil stop valve to close and cut off oil supply to air end.
IMPORTANT POINTS TO REMEMBER:-
9 If lub. oil is coming out from the suction air filter of the compressor while stopping the compressor, then it is the failure of oil stop valve change it.
9 Overheating of compressor may be due to insufficient oil in the sump (or) oil cooler choke (or) cooling motor fan failure (or) thermostat valve failure etc; check the causes and rectify problem.
9 If differential pressure in the oil separator exceeds15psi, then change the element.
9 Compressor should run in the right direction as per arrow mark in the air end.
9 Frequent loading and unloading of compressor is due to air cooler puncture or blow down valve malfunction or line leakage or more consumption of air. Causes to be checked and rectify the problem.
DO:-
9 Top up oil up to mark.
9 Ensure safety systems are in place.
9 Check the direction of rotation as per arrow mark.
DON’T :-
9 Don’t allow to run the compressor with reverse rotation. The compressor may cease immediately.
9 Don’t allow to run the compressor with overheating problem.
9 Don’t allow to run the compressor with excess differential pressure of oil.
II. HOISTING SYSTEM OF RIG E-760
1. DRAW WORKS
Model: - E760 Draw works capacity - 1000 hp
Motor capacity - 750 kw/1000 hp
Motor speed - 1000 rpm
Draw works speed -ratio - 21.3:1
The draw works is powered with two DC motors of 1000 hp each.
Either of these motor can be put into operation at a time. The additional motor is only for standby operation. Draw works is the heart of the drilling operation without which no work can be performed on the derrick floor. It requires more care and maintenance due to involvement of different mechanisms, rugged use, severity and frequency of operation.
More over it doesn’t have any standby.