Acetylene is one of the most popular gases used across industries for oxy-acetylene welding and cutting. It is also used as a raw material for the production of various chemicals such as polyester plastics, polyurethane, and more. Acetylene gas is colorless and odorless when pure. Industrial acetylene has a distinctive odor and is combustible in nature. Today, this gas is produced in large volumes using acetylene gas plants. Are you eager to know its production process? This post discusses the process in detail.
Chemical Reaction and Raw Materials
Acetylene is made of two hydrogen and two carbon atoms and is chemically represented as C2H2. This hydrocarbon is produced by one of two processes— chemical reaction or thermal cracking, using different types of raw materials. Calcium carbide is the most popular raw material used for the commercial production of acetylene. It is created by mixing lime and coke in a blast furnace. The product manufactured is calcium carbide. It is reacted with water to create acetylene gas, and this reaction can be easily formulated as CaC2 + 2H2O → C2H2 + Ca (OH)2. Acetylene, calcium hydroxide and heat are the byproducts of this reaction.
The thermal cracking process, on the other hand, makes use of natural gases, including naphtha, crude oil, bunker C, and more. These gases are subjected to a high temperature for producing acetylene, hydrogen, carbon dioxide, carbon monoxide, and more. Acetylene is separated by dissolving the product in solvents such as anhydrous ammonia, water, acetone, or chilled methanol.
This post focuses only on the production of acetylene in plants using the chemical reaction process.
Detailed Information on the Production of Acetylene in Acetylene Gas Plants
Acetylene plants may vary in design; however, in general, they are equipped with the following components and parts, which play a significant role in acetylene production:
- Hopper Filling Cart
- Air Operated Hoist
- Acetylene Generator
- Cooler Condenser
- Ammonia Scrubber
- Medium Pressure Drier
- Acetylene Purifier
- Purifier Scrubber
- Acetylene Compressor
- High Pressure Driers
- High-Pressure Filter
- Back Pressure Relief Valve Air Compressor
- Flame Arresters
- Charging Manifolds
- Air Compressor
- Pneumatic Acetone Pump
- Pneumatic Slurry Pump
The process begins with the loading of calcium carbide in a cart. Different sizes of calcium carbide are used in the process. Here is the process described in steps:
- After loading the cart, it is loaded to the acetylene generator hopper.
- In the next step, the calcium carbide is mixed with water and acetylene gas is produced instantly. The calcium carbide is added using a carbide feed mechanism that operates by sensing the pressure inside of the generator body. As the pressure drops after the carbide is added additional carbide is added to sustain the reaction and keep acetylene flowing in the process stream.
- The gas produced in the process is passed through the cooler condenser, which uses pipes surrounded by water to cool the acetylene stream as it passes through the pipes inside the cooler.
- The ammonia scrubber uses water to remove ammonia in the acetylene stream. By doing this before the purifier the purification material will last 5 times longer. Because both the cooler and ammonia scrubber lower the temperature of the acetylene stream there is little water left in the stream.
- The medium pressure drier is then used to extract moisture until the correct amount needed for the purification process is left. Calcium chloride is the medium used to remove the moisture.
- Later, the dried acetylene is passed through the acetylene purifier, where impurities such as phosphine, arsine, H2S are removed from the gas. If industrial acetylene is needed the purification process can be bypassed.
- Finally, the purified acetylene goes through the purifier scrubber to remove any purifying material that may have escaped the purifier.
- The acetylene then enters the compressor and is raised from inlet pressure to desired final cylinder pressure by passing through 3 stages of compression.
- The acetylene stream passes through a set of high-pressure driers that remove any traces of oil and perform moisture removal. Without this final moisture removal, water would be transferred to the cylinders.
- As the acetylene travels at high pressure to the manifolds it passes through flame arresters on each side of every shutoff valve. In high pressure, acetylene valves are the cause of most ignitions and the flame arresters are positioned to stop the flame as quick as possible therefore limiting the potential for damage to the system.
- The acetylene is compressed into a cylinder that has liquid acetone and a porous monolithic mass filler. This acetone in the filler allows there to be 25 times more acetylene in the cylinder than if there was no acetone.
- The ratio of acetone and acetylene will always be constant, but the total amount of acetone will vary due to cylinder size.
- The air compressor supplies compressed air to operate the acetone pump, lime slurry pump and the actuated ball valves in the acetylene plant.
It is obvious that some of these parts may fail over time, so it is important to replace them with OEM parts. Overall, it is important to source your acetylene gas plants from a reliable acetylene plant manufacturer such as Rexarc. In addition to acetylene gas plants, the company also offers a wide range of components and spare parts for the plants, such as auto-acetone scales, automatic lubricators, carbide hopper fill carts, process skids, automated high-pressure driers, calcium chloride, and more.