Regarding the material of the heat exchange water cooler
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A 200,000 tons/year methanol production plant features a shift gas water cooler in the shift section; it is designed with a shell-and-tube structure, where the shift gas flows through the shell side while the cooling water flows through the tube side. Given the corrosive nature of the shift gas condensate, the entire equipment is made of stainless steel. Let’s discuss this: if the process gas is allowed to flow through the tube side and the cooling water flows through the shell side, then only the heat exchange tubes need to be made of stainless steel, while the shell can be made of 16MR. This reduces the amount of stainless steel used and thus lowers the investment costs. Why then didn’t the designers adopt this approach?
You’re absolutely right; the people at the design institute don’t care about your investment at all – it’s good that they have no responsibility in that regard
1. The transformed gas flows through the tube side; the heat exchanger’s tube sheet still needs to be made of stainless steel, so no savings can be achieved in this regard； 2. When the transformed gas flows through the tube side, there is also the issue of an increased pressure drop; should this be taken into account in terms of system pressure distribution? ； 3. Will using the transformed gas in the tube side change the heat transfer coefficient, and will this result in larger equipment?
Brief analysis: 1. The design institute decided that the transformed gas should flow through the shell side and the cooling water through the tube side primarily based on the properties of these media; this decision also complies with the relevant regulations for the design of shell-and-tube heat exchangers. 2. The reason why cooling water flows through the tube side is, in my opinion, based on the following considerations: · It is easier to clean when impurities in the cooling water adhere heavily to the surface of the equipment; additionally, the high concentration of impurities in the cooling water leads to the formation of scale, and such scale is easier to deal with once it forms. ·The transformed gas is a cooled fluid, and it is advisable to route it through the shell side to facilitate heat dissipation and enhance the cooling effect. ·The transformed gas contains saturated steam, and it is advisable to pass it through the shell side to facilitate the removal of condensate. This post was last edited by zjyang168168 on 2007-12-25 11:38.]
This post was last edited by Fengye Hong on 2009-6-4 22:45. In our company, the coolant flows through the tube side of the heat exchanger, while the cooling water flows through the shell side. The tube side is cleaned regularly after shutdown, but it doesn’t get dirty. The tube side is made of 304 material, and the shell side is made of 16MN material; this configuration yields very good results
The last edit to this post was made by MapleRed on 2009-6-4 at 22:46. If dirty cooling water leads to scaling, it is obvious that scaling in the shell side is easier to remove than that in the tube side； From a different perspective, we could also consider installing filters at the cooling water inlet or adding scale inhibitors to the water. Whether from the standpoint of cleaning and removing scale or from the perspective of initial investment, I prefer the approach of using gas flow in the tube side and cooling water flow in the shell side.
The design institute probably considered that cooling water flowing in the shell side is prone to scaling; most of the transformed gases flow in the tube side
Cooling water flowing in the shell side tends to cause scaling, and dealing with this is troublesome due to the presence of baffles and similar elements. The pipe system is easy to clean
It should be that more of the transformed gas flows through the tube side, making it easier to clean the tube side.
The cooling water flows through the tube side, as it is clean. It is not prone to clogging; if the converter is placed in the tube side, the converted gas will form scale during the cooling process, leading to the degradation of various impurities. It can easily clog the pipes. It’s not easy to clean.