Issues related to slag flushing water heat exchangers in steel mills
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The slag flushing water heat exchangers in steel mills are used for waste heat recovery. What type of heat exchanger should be chosen? Is a conventional fixed-tube-sheet heat exchanger suitable? Additionally, what considerations should be taken into account regarding material selection and design due to water quality issues? What is the common form of pre-filter for slag flushing water? What are the common treatment methods for water quality?
That’s a good idea; I’ve worked in a steel plant doing maintenance, so I know a bit about it. There are a few questions I’d like to address: 1. What is the purpose of this hot water? 2. Technically, a cyclone well sedimentation tank, self-cleaning filters, heat exchangers, and transfer pumps are required. What are the costs, space requirements, and management aspects of these components in relation to their value in terms of recycling? 3. This technology can also be applied to the recovery of heat from the slag wastewater generated by blast furnace water guns. As for heat exchangers, the specially designed tubular type is better, as it submerges the entire heat exchanger in hot water. Prevent impurity impact and blockage. The key lies in the value of reusing the waste heat from this section. (out of curiosity, staying tuned :) )
Simple immersion has too low a heat transfer efficiency; forced circulation is necessary. I am considering using a shell-and-tube heat exchanger, with the slag flushing water flowing inside the tubes, but this could lead to blockages. . .
It can be considered to be placed at the water outlet; none of these are problems. The key lies in whether the utilization of this heat energy and the investment in facilities are feasible.
Late reply! For slag water from steel mills, it is advisable to avoid using shell-and-tube heat exchangers, as the slag water can easily clog the heat exchange tubes; basically, cleaning becomes necessary after just 3 months of use. Later on, the scale layer had to be removed manually every two weeks on average, and the problem was that it couldn’t be cleaned completely! We designed a heat recovery exchanger for tetrafluoro slag water use at the Yongfeng Power Plant in Texas. They had previously been using 4 metal shell-and-tube exchangers with a surface area of 500 square feet each, and it took over a week each time to clean them! The post-production effects and traffic can no longer meet the requirements
The reply on the 5th floor is very useful as a reference. It turns out that our company has also carried out replacements of pipes for steel slag water; in that case, the slag water flowed through the pipe side. A filtering device was included in the design of the heat exchanger, but the performance was not satisfactory due to severe clogging. Therefore, shell-and-tube heat exchangers are not recommended. If anyone has a new design, please feel free to share it as a reference!
The waste heat recovery units for steel plant slag water (tetrafluoroethylene heat exchangers) produced by our company have just been completed in terms of debugging and installation, as the heating season has already passed! The detailed specifications haven’t been released yet; if you’re interested, you can add my phone number! For easier communication later on!
You can use the wide-channel heat exchangers we produce; they are not prone to clogging and can be flushed. Feel free to communicate further
This post was last edited by koalabear on 2018-3-16 at 16:03. The main difficulties in waste heat recovery are three: 1. Clogging, as everyone above has mentioned. Because it contains particles and slag wool, it gets clogged easily. 2. Corrosion: carbon steel and various stainless steels definitely won’t work. 3. Wear and tear: As the slag particles flow with the water, they can wear out the heat exchanger; I’ve seen heat exchangers that started leaking just 2 months after being put into use. Therefore, the slag-water heat exchanger is a relatively challenging piece of equipment. The key still lies in what technical approach is used for the recovery of waste heat from slag flushing water. Based on the research and development history, the following approaches exist: 1. After filtering the slag water, send it to the user’s heating system; 2. Filter the slag water and then exchange heat with the heating water in a heat exchanger; 3. Send the slag water directly to the heat exchanger for heat exchange; 4. Send the slag water to a flash tank, where steam is generated first, and this steam then exchanges heat with the heating water.
If the heat exchanger gets clogged, we can resolve the issue and ensure its continuous operation without blockages. Further exchanges are welcome. shcsb11@163.com
Under such operating conditions, PTFE materials may not be suitable in terms of wear resistance.