The problem of catalytic tripyramidal lining
Thread Content
During the shutdown for maintenance of the unit, extensive lining repairs were carried out in the area above the discharge port of the three-cone structure. During the heating up of these two components, it is necessary to ensure that the lining dries out simultaneously – will the main air flow at the critical nozzle be sufficient for this purpose? I hope to get some guidance from all the teachers; thank you!
When baking the lining, open the vent at the bottom of the fine powder container
It’s not allowed anymore; environmental inspections are so thorough and strict! The company requires that during operation: no flying in the air, and no emissions on the ground!
At the start of operation, it is only possible to line the repair area at the three-spinners by opening the vent at the bottom of the fine powder tank; the amount of main air flow at the critical nozzle is too low to meet the requirements for lining.
This is an issue worth exploring; during startup, it might be possible to consider opening the valve below the fine powder tank. It is hoped that the air flow will still be somewhat low, but there should be no problems with lining drying during the first startup, and there will be no issue with catalyst fine powder. If conditions permit, it is possible to consider having the lining dried at the manufacturing plant before it is sent to the site; the advantage is that the lining dries to a higher quality, while the disadvantage is that transportation may cause damage to the lining. The linings of the two devices are dried; it’s difficult to ensure thorough drying in all areas, so it’s sufficient to keep control over the key parts – as long as those are properly dried, that’s good enough. Taking the waste heat boiler as an example, it is estimated that no plant can dry it to the desired level according to the theoretical drying curve; the same is true for the three-spinner.
In the past, it was indeed possible to increase ventilation to improve drying efficiency, but due to strong environmental regulations, direct emission is no longer allowed. But that doesn’t mean it can’t be done; it just needs to be added to the process after flue gas desulfurization and denitrification in order to reduce environmental pollution!
The temperature curves during the startup of the baked lining are all set manually based on the temperature required for the area where the lining is being replaced; in fact, no proper calculations have been carried out taking into account the actual operating conditions! Therefore, in many cases, ensuring the temperature in those areas is met falls within the capabilities available, and every effort is made to do so! However, you mentioned that for certain parts before starting operation, the manufacturer carries out pre-heat treatment. We did indeed use this method here in the past, and the results were good, but the costs were relatively high. As far as I remember, this approach was only used when new equipment was put into use; it wasn’t used again afterwards!
If cost is not a concern, local treatment using electric heating is the only option; this method is used in many detailed applications and is very popular abroad.