How is it possible to disconnect the liquid ammonia tank from the truck at the end of the loading/unloading process without any ammonia leakage?
Thread Content
How is it possible to disconnect the liquid ammonia tank from the truck at the end of the loading/unloading process without any ammonia leakage? Although the entire loading and unloading process takes place in a sealed environment, I think a small amount of ammonia will leak out when the connection to the tank truck is finally severed.
Theoretically, it’s sufficient to use a vacuum pump to remove all the gas from the pipe, but I’m not sure how it’s done in practice
It is common to install vent valves on the loading and unloading pipelines to burn off the gas in the flare, and to replace it with nitrogen. I hope this helps!
Generally, a purge return line is provided, which uses nitrogen to blow the remaining liquid ammonia back into the liquid ammonia tank; the connection is only severed after the line has been emptied, preventing any ammonia leakage.
Is it sufficient to use a nitrogen cylinder to supply nitrogen?
Generally, a nitrogen purging pipeline is installed in the tank farm, without the need for nitrogen cylinders.
Typical liquid ammonia storage tanks are equipped with ammonia coolers; the ammonia is filled under pressure using a pump. During filling, the gas phase pipeline from the tanker is connected to the return line of the ammonia tank, where it is liquefied by the ammonia cooler. Once the filling is complete, the valve on the liquid phase pipeline is closed, and nitrogen from the gas phase pipeline is used to purge the system into the flare.
Learn a bit; I’ve never seen it in practice
In fact, companies don’t use nitrogen for purging very often. Our procedure is as follows: 1. After filling is complete, close the liquid-phase control shut-off valve and the emergency cut-off valve on the filling pipeline. 2. Close the liquid-phase emergency shut-off valve and the end ball valve of the tank truck. 3. Shut down the ammonia compressor: Open the compressor circulation valve, close the compressor outlet valve, stop the ammonia compressor, and then close the compressor inlet valve. 4. Shut off the vapor emergency shut-off valve and the end ball valve of the tank truck. 5. Open the pressure relief valve of the ammonia removal tank. 6. Open the valve that connects the liquid phase to the gas phase in order to relieve pressure of the liquid ammonia inside the dip pipe. 7. After the pressure has been released, close the ball valves at the ends of the gas and liquid transfer hoses. 8. Open the vapor emission valve of the tank truck and direct the gas to a bucket containing half a bucket of water for recovery. 9. Open the liquid-phase on-site discharge valve of the tank truck and discharge it into a bucket containing half a bucket of water for recovery. 10. Retract the hose; after checking to ensure that all safety measures for the tank truck have been retracted and that there are no unsafe factors, hand over the tank truck’s start key to the driver and leave the filling area. No objections were raised regarding the various safety standards
What a professional and detailed question. The approach for Building 10 is supported; the recycling method is simple and not overly complicated, which shows that practical experience is involved.