Selection of renovation options for low-pressure steam drums
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This post was last edited by lxq700918 on 2009-10-15 at 21:40. Dear everyone: A horizontal stainless-steel low-pressure steam drum is currently in use in conjunction with a high-pressure cooling system. It was found that this steam drum does not have an interface for 2.4 MPa steam. After consulting with the relevant design team, it was proposed to make modifications by opening holes in the equipment itself in order to allow for steam injection and thus ensure that the steam pressure meets the requirements during startup and shutdown. However, the design team rejected this idea. Instead, they suggested adding a temperature and pressure reducing valve to the 0.35 MPa steam pipeline network located outside the urea production area, in order to compensate for the steam pressure. The following are some questions regarding this approach: 1. What are the reasons why opening holes in the equipment is not feasible from both the perspective of pipeline design and equipment design? 2: From a production perspective, can the designer’s solution meet the requirement of measuring the steam pressure of the 202C shell? (The low-pressure steam drum of this device is located at a height of 33 meters above the frame.) 3: Is it necessary to install a temperature and pressure reducing device? Steam at 2.4 MPa is saturated steam, so no temperature reduction is required; will a single pressure reducing valve be sufficient to meet the production requirements?
Please reply. Is the horizontal drum an used item? Should only a low-pressure drum be used? Will it be used vertically and connected to the high-temperature cooler, with an interface of at least 600 MM? Do we need to create a new flange opening of 600 MM? If a 600 MM opening can be created, why can’t we have a 250 MM steam inlet? How large is the high-temperature cooler? A demister also needs to be added to the drum; modifications are required, as well as pressure strength tests – it’s quite troublesome. It’s better to purchase a new one; carbon steel drums aren’t expensive. Steam at 2.4 MPa needs to be introduced into the low-pressure drum (at least into the shell side of the high-temperature cooler), this is to preheat the high-temperature cooler and to raise the pressure during shutdown. During shutdown, the pressure is raised to 0.56 MPa to maintain heat and pressure and prevent backflow of liquid. How could the design team not be aware of this? It’s certainly possible to introduce steam at 2.45 MPa into a pipeline at 0.35 MPA, but this slows down the increase in pressure in the low-pressure drum and makes operations inconvenient. With the entire pipeline system at 0.56 MPA, leaks are likely to occur.
This post was last edited by lishouqiang_198 on 2009-10-14 at 11:14. Those who value water should note that this device is used; it is arranged horizontally, with 6 air tanks connected to each other in the upper section where high-potassium coolant flows. In the lower section, the coolant enters through one main pipe and then splits into 4 branches. The design principle is that modifications involving making openings in the device are generally not carried out, which is why I raised this issue! Additionally, our piping work is currently in progress (on-site connection completed on 2009.10.14); the renovation project has not yet started. We will schedule a PP meeting at an appropriate time so that everyone can help analyze and resolve the issues.
It’s installed horizontally, which means it takes up more space. There’s only one steam drum, and it already has existing connections, so no need to create new ones. What is your production capacity? It’s recommended to use steam at 2.45 MPA; it’s better to feed it into the steam drum. Does the steam go into the shell side of the high-pressure cooler?
Based on an analysis of meeting the modification requirements mentioned by the original poster, I personally believe it is appropriate to adopt the designer’s proposal of \"adding a temperature-reducing pressure regulator on the steam pipeline network at 0.35 MPa outside the urea production area in order to compensate for the steam pressure.\" According to the designer’s plan, on the one hand, it meets the requirements for renovation; on the other hand, from the perspective of pressure vessel management, it is recommended not to make holes in the equipment lightly.