Heavy Water Plant at Hazira, employs the ammonia-hydrogen exchange monothermal process. The plant is located at a distance of about 16 km from Surat city. Work on HWP (Hazira) commenced in August 1986   and the plant was commissioned in February 1991

Process description

This plant comprises of two streams consisting of

two separate isotopic exchange units, final  enrichment units, final production units & cracker units, but a common ammonia synthesis unit. Feed synthesis gas (a mixture of one part of nitrogen and three parts of hydrogen containing deuterium from the Ammonia plant is routed through the plant at a flow rate of about 96 T/hr. at a pressure of about 181-220 kgs./sp.cm.

The pressure of the gas is first raised by 40 kg/sq.cm. by a booster, to take care of pressure drop in the plant. Its is then cooled in a heat exchanger by the outgoing cold gas returned from the plant. The gas is thereafter passed through a purification unit. In this unit the oxygenated impurities contained in the gas are removed and the gas is saturated with ammonia.The purified synthesis gas saturated with ammonia is then passed through the first isotopic exchange tower working at minus 25 degree celsius where deuterium in the gas is transferred to a counter current stream of liquid ammonia containing potassium amide catalyst fed from the top of the

tower.The deuterium enriched ammonia from the bottom of the exchange tower is then fed to the second isotopic exchange tower where it gets further enriched by coming in contact with the enriched synthesis gases obtained by cracking of enriched ammonia.  A part of the enriched gas and liquid from the second isotopic exchange tower is then taken to the final enrichment section where the concentration of deuterium in the ammonia can be further increased as desired upto 99.8%.  Finally, the enriched ammonia so obtained is made free of the catalyst and is cracked. A portion of this enriched synthesis gas is burnt with dry air to produce heavy water.  However, for reasons of better recovery efficiency the concentration of deuterium in ammonia in the final enrichment section is kept low so as to produce heavy water of about 60% which is then vacuum distilled to produce heavy water of nuclear grade.