Methanol storage tank design
Thread Content
Now I am designing a methanol storage tank with a storage capacity of 600 cubic meters. I read the posts on the forum and found that many of them use internal floating roofs. However, after asking a few people in the room, they all recommended using a fixed-roof atmospheric pressure vessel + breathing valve with a design temperature of 45. I personally think that using an internal floating roof is definitely better, but the investment is high and the later management is definitely inconvenient. I don’t know if the fixed-roof normal pressure vessel + breathing valve solution is feasible. Please give me some suggestions.
It is completely feasible to use a fixed roof + breathing valve. Our factory has a total of 6 500-ton storage tanks for refined methanol and two 250-ton crude methanol storage tanks, both of which are in the form of fixed roof + breathing valve. When using a fixed roof + breathing valve type storage tank, two points should be noted.: 1. Considering the impact of high temperatures in summer, pipes need to be installed for external spraying to prevent large amounts of methanol from volatilizing. 2. The choice of liquid level gauge is very important. The float steel wire type is not accurate. It is recommended to use a radar level gauge, which is very good and easy to maintain.
Thank you very much to Huachang Refining. Now I can use the fixed top + breathing valve method, which has advantages in cost and management.
The 3,000 cubic meters and 800 cubic meters of methanol in our factory are also in the form of fixed top + breathing valve (3 pieces). Like Huachang Refining, it is equipped with a spray water device.
Thank you everyone. I have another question. What is the general amount of spray water? Are there any relevant regulations?
Consider using a fixed-roof or floating-roof methanol storage tank. There is no problem in terms of many processes, but the overall layout is different. Especially for small companies that use methanol, the space is limited. If it is a fixed-roof storage tank, according to the "Building Design Fire Protection Code", the minimum fire protection distance from the tank farm to the workshop is 25 meters. The fire protection distance of floating roof tanks can be reduced by 25%.； If you follow the "Petrochemical Enterprise Design Fire Protection Code", you can save more than ten meters. From a safety perspective, floating roof tanks are safer than fixed roof tanks.
There are two main considerations for using a fixed roof: first, cost issues and future maintenance; second, the current methanol reserves are not large, and there is no need to use an internal floating roof, which is only 600 cubic meters.
There are no relevant regulations on the amount of water sprayed. If you think about it, the purpose of spraying water is to cool down the methanol tank. The spray device is actually very simple. There is a ring pipe along the top of the storage tank filled with small holes. As long as the water sprays out, it can form a water film on the entire tank wall.
Atmospheric pressure vessels + breathing valves, design temperature 45°C. Our factory has 2 300 m3 vessels, 2 500 m3 vessels, and 2 10,000 m3 vessels. They all use normal pressure vessels + breathing valves, and the design temperature is 45°C. Our climate is very moderate and we have never sprayed water, not even in summer.