Green ammonia storage tanks are typically constructed as double-walled, double-integrity tanks with insulation on the outer wall. These tanks are designed to hold liquid ammonia at low temperatures (around -33°C) and are equipped with pressure and vacuum relief valves for safety. The outer tank is designed to contain the entire liquid content in case of a leak from the inner tank. The construction often involves using low-temperature certified carbon-manganese steel, impact-tested at or below -40°C.
Key Features and Construction Details:
Double Containment: The tank structure includes a gas-tight inner steel tank (the "cup") and an outer containment structure, often a concrete cup wall, to prevent leaks from the inner tank.
Insulation: The outer tank is insulated with materials like polyurethane foam or glass wool to maintain the low temperature required for liquid ammonia storage.
Foundation: The tank is typically erected on an elevated, piled concrete slab foundation to prevent frost heave.
Pressure Relief: Two pilot-operated pressure relief valves and two vacuum relief valves are installed to protect against overpressure or vacuum.
Materials: Low-temperature certified carbon-manganese steel is a common material for the inner and outer tank shells, as well as for the suspended deck.
Roof: The roof may be bare and painted on the outside.
Welding: All welding is performed in accordance with applicable standards.
Example of a Large Tank:
The NEOM project in Saudi Arabia involves the construction of large ammonia storage tanks with a diameter of 76 meters and a height of 40 meters, featuring a gas-tight inner steel tank with a dome roof and an outer pre-stressed concrete cup wall.
Safety and Standards:
Ammonia storage tanks are designed and built according to standards like API 620 Appendix R.
The tanks are also designed to withstand internal pressures of 14 kPag.
The outer tank is designed to contain the entire liquid content in case of a leak from the inner tank.
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