How Acetylene Is Produced in an Acetylene Plant

The short answer

Acetylene (C₂H₂) is produced by the exothermic reaction of calcium carbide (CaC₂) with water. In an industrial acetylene plant, carbide is fed into a water-filled generator, the acetylene gas released is cooled, purified and dried, then compressed and charged into dissolved-acetylene (DA) cylinders where it is stored safely dissolved in acetone or DMF over a porous mass.

The governing reaction, and the heat it releases, is:

Because the reaction is strongly exothermic, temperature control is central to a safe plant — IIGAS generators hold the reaction at about 58–60 °C by automatic water metering, with the carbide feed tripping if the tank reaches 70 °C.

The 8-step acetylene production process

A modern automatic plant takes carbide to a filled cylinder in eight continuous stages. Every stage on an IIGAS plant is instrumented and interlocked so it fails safe.

1. 1
   1 · Acetylene generator

   Calcium carbide is screw-fed into the water-filled generator shell. A pressure switch stops and starts the feed so generation follows demand exactly, and the reaction is held at ~58–60 °C.
2. 2
   2 · Cooling chamber

   The gas passes wet flashback arrestors into a low-pressure condenser. Water cooling drops the temperature and condenses moisture, while an ammonia scrubber strips the ammonia formed during generation.
3. 3
   3 · Low-pressure drier

   Anhydrous calcium chloride trims the moisture to the optimum level for efficient purification.
4. 4
   4 · Purifying chamber

   Purifying media remove phosphine, sulphur compounds and acidic fumes, taking the gas to 98.5% purity — or 99.5% with an optional molecular-sieve unit.
5. 5
   5 · Scrubber

   A water wash removes any purifying-chemical particles carried over with the gas before compression.
6. 6
   6 · Acetylene compressor

   A three-stage compressor with cooling coils at every stage — the whole assembly submerged in a water tank — raises the pressure while keeping the gas cool. Acetylene is never compressed with air present.
7. 7
   7 · High-pressure driers

   Mechanical separation plus chemical drying remove the last moisture and lube-oil vapour; a back-pressure valve holds the line at 12–14 kg/cm²g until the gas is fully dry.
8. 8
   8 · Cylinder charging manifold

   The dry gas passes a dry-type flashback arrestor to static-free uniflow valves, and cylinders fill under a continuous cooling-water spray into their porous mass and solvent.

Why acetylene is dissolved, not just compressed

Acetylene cannot be safely stored as a compressed gas above about 1.5 bar on its own — it can decompose violently. That is why it is stored dissolved: DA cylinders are packed with a porous mass and charged with acetone or DMF, and the acetylene dissolves into the solvent. This is what makes the gas safe to store and transport, and it is why the final plant stage fills into prepared cylinders rather than ordinary high-pressure bottles.

What controls purity and yield

Two things decide the economics of an acetylene plant: how much gas you get per kilogram of carbide, and how pure it is. IIGAS plants run at over 98% generator efficiency (92% guaranteed minimum) on a 6–8 litre-of-water-per-kg-carbide ratio, and can run on low-cost carbide dust as well as graded lump to cut feedstock cost.

IIGAS is the only company in India producing ultra-high-purity acetylene (99.96%) from carbide-to-water at industrial scale.