Acetylene production process using calcium carbide

Acetylene plants are available in capacities from 25m³/hr to 200m³/hr and are quite automatic in nature. The reaction of calcium carbide with water leads to the production of acetylene in a Stationary Carbide to Water-type Automatic Acetylene Generator. Calcium carbide is fed from the top of the generator shell where the large quantity of water is already held and which yields the following reaction:

CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂

 The processing unit should be equipped with high-level non-return valves, pressure and temperature sensors for safety and control operations. The operation like production acetylene can only be done when perfect automation and controlled system are added to the system, vent valves should be highly sensitive and accurate. Flashback arrestors make the whole process run smoothly.

Acetylene gas can be produced by the following process:

1. Drums containing calcium carbide should be opened only just before filling and carbide to hoppers.
2. Carbide containing more than 15% dust and sizes exceeding beyond the limits specified should not be kept for charging in hoppers.
3. Keep the hopper change over switch to a manual position if the carbide is to be charged to a running generator.
4. Close the hopper equalizer valve. Ensure zero acetylene gas pressure into the hopper to be charged by opening the hopper vent valve.
5. Lift the skip containing calcium carbide with the help of pneumatic hoist.
6. Locate the skip manually above the hopper to be charged, lower the skip till inserted in the hopper slightly.

7. Draw the removable cap and poke with a brass rod, when charging is interrupted. Ensure that the skip was made empty.
8. Lift the skip.

9. Clean the carbide dust accumulated on the lids and hopper.
10. Replace the lid carefully. Stop nitrogen purging. Disconnect the nitrogen purging line.
11. Be sure that nitrogen purging is done continuously as long as the charging is undergoing.

Diagram of the acetylene production system

Pieces of the equipment described in the process:

Generator:

The reaction occurs in the generator where calcium carbide is reacted with water and produces acetylene gas and remains the calcium hydroxide as the slurry.

 Accessories fitted to the generator:

1. Twin Hoppers

2. For better mixing agitator is fitted with spark proof motor.
3. Feeder for continuous feeding of calcium carbide.
4. Arrestor to prevent any kind of flash generated in the system.
5. Automatic control sensors with the auto safety valve

Condenser:

Generated acetylene is cooled down

High-pressure drier:

Calcium carbide and water are reacted to form Acetylene and calcium hydroxide. The generator is equipped with automatic by-product discharger. High-pressure drier helps in drying the acetylene gas by using anhydrous calcium chloride.

Purifier:

It is used to separate hydrogen sulphide and phosgene that were produced along with acetylene. A wire mesh works as a surface for the gases to separate easily.

Scrubber:

It is a counter system, all the produced gas to pass through the counter flow of water to remove ammonia content and any water-soluble gases from acetylene.

Compressor:

Acetylene is highly flammable and so to compress it in three stage compressor is the highly dangerous task, but the technique of water surrounding and sealing will make the acetylene compressor work in sealed environment avoiding the contact of air.

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