How High Purity Acetylene is Made

High purity acetylene has a wide range of uses, including flame spectroscopy, production of some plastics and chemicals, as a light source in places without access to electricity, and most commonly, as a fuel across industries. This article will help you understand how acetylene is purified to the levels required for some of these applications, and where to get the required equipment.

What is high purity acetylene?

Acetylene is a clear, flammable gas with the chemical formula C2H2. It’s used in welding and cutting metal since it’s an efficient fuel. It burns at about 6,000 degrees F, which is the hottest temperature any combination of flammable gases can burn at.

Commercial grade acetylene contains between 2 – 5% impurities. However, in some applications this is too high a level of contamination to perform as required. For examples, impurities can cause bad readings in flame spectroscopy and flaws in materials made from acetylene. When used as a fuel, impurities reduce fuel efficiency and leave behind residues from incomplete combustion.

Impurities in acetylene gas can also reduce the lifespan of equipment used with it, including gas cylinders used to store and transport the product. Using cleaner acetylene can reduce maintenance and replacement costs for equipment and infrastructure.

To prevent these problems from occurring, some applications use high purity acetylene. High purity acetylene has been processed and treated to remove impurities, achieving up to 99.6% purity.

How is acetylene produced?

The most common way acetylene is made on an industrial scale is by reacting calcium carbide with water in an acetylene plant. When combined, water and calcium carbide react to produce acetylene gas, calcium hydroxide, and heat. The gas is cooled, water vapor and other impurities are removed, and then the gas is compressed and stored in a cylinder. You can learn more about this process in our guide to acetylene production.

How is acetylene purified?

To make high purity acetylene, there’s several methods and processes to further remove contaminants. The first, and simplest, is to start with high quality calcium carbide. Commercially available calcium carbide can have different amounts of impurities in it. Using calcium carbide with a lot of contaminants to make acetylene will mean higher quantities of contaminants mixed in with the produced gas. Therefore, it’s important to use clean, high quality reactants so there will be fewer impurities to remove later.

There’s two steps that are added to the acetylene production process to remove contaminants: ammonia scrubbers, and acetylene purifiers. The next two sections will walk you through the details of what they do and how they work.

Ammonia scrubbers

Ammonia scrubbers remove ammonia from the acetylene gas using water. Impure acetylene gas enters a water-filled chamber. Ammonia in the gas dissolves into the water, leaving the acetylene behind.

The scrubber is designed to break up the gas bubbles into smaller diameters to increase the amount of ammonia removed. This increases the total amount of gas directly touching the water, so it’s easier for the ammonia to move from the gas into the water.

When the water becomes saturated with ammonia, it’s removed from the scrubber and replaced with fresh water until the gas is sufficiently ammonia-free. Next, the gas is sent to the acetylene purifier to remove more contaminants.

Acetylene purifiers

Acetylene purifiers send the gas through a filter, then through a purifying material designed to remove contaminants including the following:

• Phosphine
• Hydrogen/phosphorous compounds
• Hydrogen/sulfur compounds
• Ammonia (if an ammonia scrubber isn’t used)

The acetylene purifier is placed after the ammonia scrubber to increase the purifier efficiency. Removing most of the ammonia first extends the life of the purifying material.

Rexarc has used our decades of experience in acetylene plants to develop and refine a dry, purifying material we call Monkey Dust that efficiently removes contaminants from the gas.

Once the acetylene has had these contaminants removed, it’s passed through a purifier scrubber to remove any of the purifying material that got mixed into the gas. Then, it’s ready to be pressurized and stored for transport and use.

Where to get high purity acetylene equipment

If you’re looking for equipment to improve the purity of your acetylene, we offer solutions! We’re happy to talk with you about your individual needs, whether it’s an entire acetylene plant or spare parts and help with maintenance.