Reciprocating Compressor

Compressors are used to supply highly compressed air for working of drills and other machineries in mines.

1. Reciprocating compressor Pawan Kumar Pradhan (117MN0781) Amritesh (717MN1023) NIT ROURKELA

2. CONTENT What is air compressor? Reciprocating Compressor Types Indicator diagram Starting Operation Carbon and explosion Compressor efficiency Specifications References

3. What is an air compressor? A compressor is a device which is used to increase the pressure of air from low pressure to high pressure by using some external energy. An air compressor is a device that converts power (using an electric motor, diesel or gasoline engine, etc.) into potential energy stored in compressed air. Compressed air is used as power mainly to operate drills and other machinery in mines, both surface and underground. In u/g coal mines it is preferred for drifting in stone due to better performance than electric drills. They can be of two types: Reciprocating Compressor Rotary Compressor

4. Reciprocating Compressor A reciprocating compressor consist of a piston working to and fro in a cylinder, and then discharge at the required pressure into a receiver. During the return stroke, air at atmospheric pressure is drawn into the cylinder through the inlet valves in readiness for compression. During delivery, the pressure of air compressed in the cylinder has to be slightly more than the receiver pressure for the delivery valve to open. During suction, the pressure of air in the cylinder must be lower than the atmospheric air so that pressure difference across the inlet valve forces it off its seat.

5. Types of reciprocating compressor Single-Acting Compressor: It is a compressor that has one discharge per revolution of crankshaft. Double-Acting Compressor: It is a compressor that completes two discharge strokes per revolutions of crankshaft. Most heavy duty compressors are double acting.

6. Indicator Diagram C – Piston travel starts, compression starts. D – Delivery valve opens. A – Delivery of compressed air ends. B – Suction valve opens, atmospheric air suction starts.

7. Starting the reciprocating compressor Before starting a reciprocating compressor: Routine check up should be made of oil level in engine and compressor. Fuel and water in the radiator. Check for loose nuts and bolts. The receiver drain cock should be opened and the clutch disengaged.

8. Operating the reciprocating compressor After starting a Reciprocating compressor: After starting, the engine is run for several minutes to warm up, and then clutch is engaged. After the compressor is turned on without choking, the drain cock is closed. If it threatens to stall, the clutch should be disengaged or the compressor unloaded by hand control and further time allowed to warm up.

9. Carbon and explosion The heat generated during working of a compressor causes vaporisation of the lubricating oil. So, the non-volatile residue in combination with dirt present in the air is liable to build up hard or gummy deposits that will interfere with valve operation and sometimes chokes the passage. If exhaust valve leaks some of the hot compressed air which has just been forced out od the cylinder will come back in the cylinder and be recompressed resulting in very high pressure locally and excessive temperature will boil off and vaporise the lubricant. Under these conditions if enough oil vapour is present in air it can cause explosion.

10. Compressor Efficiency Volumetric Efficiency = Mechanical Efficiency= Overall Efficiency =  

11. Specification Specification Stages 2 Type Electric No. of cylinders 2 Motor 3 HP Air receiver 150 L Crank stroke 80 mm Working pressure 8 Bar Discharge 250 LPM Weight 90 Kg EMTEX JV-0.25/1.25

12. References Deshmukh D.J. (2014), Elements of Mining Technology Vol. III , Denett Publications, Nagpur, pp. 176-177 Sarkar S., Lecture on Compressor , Dept. of Mechanical Engineering, IIT(ISM) Dhanbad, pp. 2,8 https://www.industrybuying.com/air-tank-compressor-emtex-PNE.AIR.19812916/?q=reciprocating+air+compressor&cat= https://makeagif.com/gif/ldght-ltrddy-reciprocating-compressor-rwe7du

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