Water washing joint commissioning of the low-temperature methanol wash unit
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Recently, I came across some information indicating that in the water washing commissioning of low-temperature methanol washing units in certain facilities, bypass heat exchangers are not used, instead temporary pipelines are installed. I would like to ask those of you who have experienced this to share your views. This post was last edited by mountain16 on 2008-9-6 at 08:11.]
Coiled tube heat exchangers can be very troublesome once they get clogged
Our factory does the same thing; we’re just afraid of the heat exchanger getting clogged:handshake
If the construction quality of pipes, equipment, etc. is properly controlled during the construction process, I don’t think it’s necessary to install bypasses. Our factory didn’t add any bypasses during the initial joint commissioning, and coil heat exchangers aren’t as prone to clogging as the original poster might think; generally, clogging occurs over time due to scaling caused by corrosion products and other factors.
During the water-driven commissioning, the coil-type heat exchanger is not used; blockage is one issue, but another problem is the difficulty in draining water. Regarding blockages, I think that cleaning the pipes and equipment before driving should resolve the issue fairly well. It is rather troublesome to drain water from the coil-type heat exchanger; since there is a significant amount of water in the conversion gas before the system starts operating, and together with the water present in the system, it becomes even more difficult to remove water from the circulating methanol.
During the initial startup, water flushing is carried out in order to remove impurities from the towers, pipes, valves, and equipment. The structure of coil-type heat exchangers is relatively complex; any larger debris can be difficult to remove, leading to blockages in the heat exchanger. The consequences of such blockages can be severe. During initial startup, we use temporary pipes.
Of course, this approach is excellent; it completely prevents stolen goods from clogging the coil-type heat exchangers, and at the same time reduces the time required to drain the water inside the heat exchangers after the water circulation process is completed； But as we all know, there are many coil heat exchangers in the low-temperature methanol washing system, and most of them are multi-element heat exchangers. If temporary pipelines are used, it will be rather troublesome, require a lot of labor, and result in high material costs. More importantly, since the equipment is replaced by pipelines, the pipeline resistance decreases, and the water-flow testing cannot fully reflect the actual operating conditions of the system! So, in my opinion, as long as, after the construction is completed, people enter the large equipment to remove any large debris and waste such as slag that can be cleared manually, and the system is purged and cleaned for as long as possible to ensure the quality of this purification process, then there’s no need for concern! As for the difficulty in draining the water inside the coil heat exchanger after water intermodal transport is completed, I believe that by increasing the nitrogen pressure slightly during system drying and extending the drying time, it is possible to remove almost all of the moisture
We are still in the design phase here. Learning from those upstairs, I have another question: is there an ammonia cooler installed before the transformed gas enters the coil heat exchanger? This would allow sufficient cooling capacity to be provided during startup, so as to separate the water and reduce the amount of water that enters the system
As far as I know, there isn’t one. Generally, it involves a gas-liquid separation unit, along with a device for spraying methanol
Is the water interconnection cycle the same as that of methanol? Thank you
For water transportation, the secondary line should be washed first, followed by the main line