HAZard and OPerability Study(HAZOP) Study for Various Packages of Hydra zine Hydrate Plant

Gujarat Alkalies and Chemicals Limited (GACL), has a proposed plan of following installations for Hydrazine Hydrate Unit at Gujarat Alkalies and Chemicals Limited (GACL), Dahej.

  1. Hot Oil Package.
  2. Ammonia Scrubber.
  3. ETP

Hot Oil Package:

The package consists of 2 nos. of independent Circuits for supplying Thermic Fluid to Hydrolysis column reboilers and Ammonia Column Reboiler respectively.

Therminol-55 is used as Thermic Fluid. Each thermic fluid circuit consists of Hot Oil pump, thermic fluid heater and expansion tank. A common blowdown tank is provided to empty out the thermic fluid circuits. Common Flue Gas stack is provided for both the thermic fluid heaters.

Ammonia Scrubber

Ammonia vapours from Ammonia Storage and Handling section is used as reactant in reaction section (Unit 100) and Acetamide recovery section (Unit 200). 

In reaction section (Unit 100), ammonia vapours are required to be sparged into the reactors, which are operating in batch mode. Also, ammonia is required in Acetamide recovery section (Unit 200), which is also operating in batch mode. Unreacted ammonia from Unit 100 and Unit 200 is recovered and recycled back to the Ammonia Storage and Handling section.

Ammonia Storage & Handling System consist of Anhydrous Ammonia Unloading Compressor (K-3801 A/B), Anhydrous Ammonia Liquid Storage Tanks (ST-3805 A / B), Ammonia Vaporizers (E-3802 A/B, E-3803 and E-3804 A/B), Vaporized Ammonia KOD (ST-3806) and Waste Ammonia Dilution Tank (ST-3807).


ETP (Effluent Treatment Plant) is a process design for treating the industrial waste water for its reuse or safe disposal to the environment.

• Influent: Untreated industrial waste water.

• Effluent: Treated industrial waste water.

• Sludge: Solid part separated from waste water by ETP.

Hazard and Operability (HAZOP) Study is a technique to evaluate the potential hazards which are associated with the Existing facilities and for proposed new facilities of Operation and Maintenance. This study is carried out by a team of engineers from different disciplines. The team looks at each section of a plant or system or operation, considers potential hazards from intended operation and analyses their consequences against any existing safeguards.

HAZOP is a brainstorming technique, where team members contribution based on their collective experience and lessons learnt from their past.

HAZOP for any project or modification serves many purposes including

  • Identify the hazards inherent to the proposal.
  • Identify the credible human and/or equipment instrument failures likely to lead to accident scenarios/Operability Problems.
  • Qualitatively assess the risk and provide recommendations to overcome the hazards if required.
  •  In addition to these issues, HAZOP identifies items which could improve unit operations and efficiency