Production Process of Acetylene

Working of acetylene generators using chemical reaction process

Chemical reaction process is used to make acetylene at normal temperatures.  A typical sequence of operations is detailed below for converting various raw materials into acetylene by the chemical process:-

• Acetylene generators use a rotating screw conveyor for feeding calcium carbide granules in the reaction chamber, which is filled with water. The granules measure around 0.08 in x 0.25 in (2 mm x 6 mm), which makes available the perfect sized exposed surface for the reaction to take place. The feed rate is decided by the desired rate of gas flow and could be managed a pressure switch in the chamber.
• The solution of calcium carbide granules and water is stirred constantly by a set of rotating paddles inside the reaction chamber. It also stops granules from swimming on the surface and possible could over-heat and ignite acetylene.
• Acetylene gas floats to the surface and is collected under low pressure. When acetylene leaves the reaction chamber, it is cooled by a spray of water. Moreover, the water spray is also used for adding water to the reaction chamber for continuing the reaction as new calcium carbide is added. When the gas is cooled, it passes through a flash arrester, which stops any ignition due to accident.
• On reacting with the water, the calcium carbide forms slurry of calcium carbonate, which deposits at the bottom of the chamber. At regular intervals, the reaction must be stopped to remove the deposited slurry.  The slurry is removed from the chamber and pumped into a pond, where calcium carbonate gets separated and the water is drawn off.  The thickened calcium carbonate is then dried and sold for use as an industrial waste water treatment agent, acid neutralizer, or soil conditioner for road construction.

Storage and Handling

Great care is required for handling and storage of acetylene gas because it is of highly explosive nature.  When transported through pipes, it is ensured that pressure is very low and length of the pipeline is kept very short. Special storage cylinders are used for storing acetylene for use in oxy-acetylene welding and metal cutting operations. The cylinders are filled with absorbent material, like diatomaceous earth, and a small amount of acetone.  Acetylene is pumped into the cylinders at a pressure of about 300 psi (2,070 kPa) and it gets dissolved into acetone. When it is dissolved, it loses its capacity to explode and is now safe for transportation.   On opening the cylinder valve, the pressure drop makes acetylene to vaporize into gas again and flow through the connecting hose to the welding or cutting torch.