Liquid ammonia sphere tank
Thread Content
Which expert can tell me how to perform gas replacement when cleaning and inspecting a liquid ammonia pressure storage tank? Is it simply a matter of continuously purging with nitrogen until it meets the standards? Is there a faster way?
Process pretreatment step 1: Maintain pressure while pouring out liquid ammonia. 2. Nitrogen displacement. 3. Isolate from the external environment of the process. 4. Open the upper and lower manholes for natural ventilation. 5. Flush with fire-fighting water. 6. Install fans for forced ventilation
First, fill it with water, and then displace it with nitrogen.
A tank with a capacity of 4,000 cubic meters, filled with water? So, how should this wastewater be treated? Is it appropriate to discharge it?
I’m not sure what the effect of nitrogen displacement will be, nor whether the construction period will be long; if the manhole is forced to be opened, environmental regulations will definitely not be satisfied
I. Cleaning: First, clean the ammonia tank, and then seal the manholes properly. II. Water filling: The ammonia tank must be filled with water, and the pressure should be increased to 1.5 MPa; it must remain stable for 2 to 3 hours without any leaks before nitrogen replacement can take place. III. Prepare nitrogen: To carry out the replacement of the ammonia tank, it is required that the nitrogen pressure be maintained at above 0.5 MPa ； The nitrogen entering the system is vented; replacement can only take place once testing shows that the purity of the nitrogen is above 99.5%. IV. Connection Process: Remove the blind flange on the ammonia tank to confirm that the process is connected. V. Nitrogen displacement: Perform nitrogen displacement of the ammonia tanks one by one: Open the nitrogen inlet valve for the tank, maintain the pressure inside the ammonia tank at around 0.3 MPa, and slowly drain all the water remaining in the tank ； Close the bottom valve of the tank and switch to venting from the top of the tank; continue to maintain the pressure in the ammonia tank at around 0.3 MPa ； After the displacement process for a certain period of time, contact the laboratory staff to take samples; the gas oxygen content in the tank is considered acceptable if it is <0.2%, at which point the nitrogen displacement can be stopped ； After the ammonia tank has been successfully replaced, maintain the pressure in the tank at around 0.3 MPa. Only after the incoming materials are unloaded can the residual pressure be released to carry out the ammonia unloading operation.
After emptying it, you can replace the contents with water, but nitrogen replacement is essential. Once the replacement is nearly complete, you can open the container to let air in; I’ve experienced such a testing procedure before.
I really don’t know any way to do it without filling it with water.