General Features & Process Description

Heavy Water Plant at Tuticorin is a constituent unit of Heavy Water Board, Mumbai under Department of Atomic Energy, Government of India. It employs the ammonia-hydrogen exchange process (mono-thermal). The plant is located at a distance of about 14 km from Tuticorin Railway Station. Work on HWP Tuticorin was commenced in September 1971 and the plant was commissioned in July 1978.

Process description :

Synthesis gas (a mixture of three parts of hydrogen and one part of nitrogen) containing deuterium, produced in an adjacent Ammonia Plant, is routed through the plant at a flow rate of about 48 T/hr. at a pressure of about 191-216 kgs./cm2. The pressure of the gas is first raised by 40 kg/cm2 to take care of pressure drop in the HWP. It is then cooled in a heat exchanger by the outgoing cold gas to Ammonia Plant. The gas is thereafter passed through a purification unit. In this unit the impurities contained in the gas such as water, carbon monoxide, carbon dioxide and oxygen are removed and the gas is saturated with ammonia. The cooled and 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 fed from the top of the tower in the presence of potassium amide catalyst dissolved in liquid ammonia. 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 cracked gases obtained by cracking of enriched ammonia.


A part from 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%. However, for reasons of better recovery efficiency, the concentration of deuterium in ammonia from the final enrichment section is kept at around 60%. The enriched ammonia so obtained is cracked and a portion of this enriched synthesis gas is burnt with dry air to produce off-grade heavy water and the off-grade heavy water is further distilled in an upgrading plant to produce nuclear grade heavy water.

At present, naptha is being replaced with LNG( liquified natural gas) and necessary modifications are worked out and plant will restart with LNG as Fuel. Further, Distributed Control System will be replacing the pneumatic system and Necessary modifications are in progress.

Salient Features of Heavy Water Plant
Process Used NH3-H2 Exchange (Monothermal)
Capacity of the Plant 49 MT / Year
Date of Commissioning July 1978
Capital Cost of the Plant Rs. 3741 Lakhs
Plant Area 8.40 Hectares
Number of Employees 253 (As on 01.02.2012)
Operating Pressure 250 kg/cm²
Synthesis Gas Flow Rate 48 Te/Hr
Total Weight of Structure 2840 Te
Total Weight of Equipments 1700 Te
Weight of Heaviest Equipment 365 Te
Maximum Diameter of Equipment 2.8 M approx.
Maximum Height of Towers 40 M approx.
Total Length of Piping 27.25 Km
Total Length of Electrical Cables 90 Km
Substation Capacity 11 MVA
Connected Load 13.76 MW
Power Consumption 210 MWH / Day
Water Consumption 1200 M3 / Day
Naphtha Consumption 48 Te.Day
D.M Water Consumption 100 M3 / Day

Last updated on: 07-Feb-2019