Large temperature drop in the main steam pipeline of the refinery
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The main steam pipeline of the refinery (450 degrees) has several branches, serving reformation, diesel, cracking, wax oil, atmospheric and vacuum distillation, sulfur, and coking; among these, the sulfur branch has a stream of steam (390 degrees) fed into the main pipeline. It has been found that the inlet temperature of the wax oil is too low to meet the production requirements. The insulation along the main pipe from the cracker to the wax oil section was inspected; although there were areas where the insulation had settled and was of poor quality, it was similar to the insulation in other parts, and there was no sign of particularly poor insulation in this section. I’d like to ask, what other possibilities could there be?
:No one answered regarding the handshake?
The use of superheated steam is relatively uncommon. It would be best if the poster provided a flowchart showing the pressure, flow rate, and temperature at the two steam supply points, as well as the flow rate, pressure, and temperature at each user endpoint. Major diameter, length ； Diameter and length of the branch pipe. It facilitates analysis and discussion. Based on experience, here are some suggestions: “It has been found that the temperature at the wax oil inlet is too low, and it does not meet the production requirements.” Is the low temperature indicated by the instruments? (If the sampling point is located in an area that has been expanded, the temperature might drop.) You can borrow a quick temperature meter from an electrician to measure the surface temperature at the valve’s flange. It is even possible to trace back step by step to the appropriate point to see where the temperature dropped sharply. PS: For saturated steam, I have done this before – the surface temperature of the pipe at the valve connection is higher than the saturation temperature corresponding to that pressure, and it is even higher than the temperature shown by the instruments at the user’s end. It is highly suspected that the real reason is not an insufficient temperature of the steam branch pipe, but rather a mismatch between flow rate and branch pipe diameter, a lack of steam at the user end, or an insufficient total supply of steam, all of which prevent the heating temperature at the user end from rising. Additionally, if the metal sheet outside the insulation layer is damaged, there will be a noticeable increase in steam consumption after heavy rain. Local damage shouldn’t have such a big impact. Once the real cause is found and the problem is solved, please reply to this post. Everyone should also be eager to learn*.
1. Check the layout of the pipelines to see if there are any that are close to the ground level. Our company has encountered cases where the heat transfer oil experienced a significant drop in temperature due to heavy rain causing water accumulation, as the pipelines were located low above the ground. Steam pipes should be placed on elevated structures. 2. Check the insulation condition for any signs of aging due to prolonged use or issues resulting from improper material selection. 3. Check the instruments at the temperature measurement points; if there are no issues, it may be due to the low temperature of the heating medium in the branch unit or some other reason. 4. Check if there is any weather impact
In addition to external losses, the low local steam consumption results in a slow flow rate, leading to a large temperature drop as well.
Use relevant software to determine whether the steam flow rate is reasonable, such as HYSYS
Is there more steam being produced, which could lead to condensation? If not, check whether there are any blockages in the pipes Otherwise, the temperature wouldn’t increase much, as long as the insulation is in good condition