Movement of the slide valve in the catalytic device
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This post was last edited by luobinh on 2011-9-20 at 10:23. Please discuss whether it is necessary to move the slide valve of the catalytic unit regularly, and what would be the appropriate frequency and range of such movements? Advantages and disadvantages of active and inactive? We are concerned that operating the slide valve at small angles over a long period of time may cause it to stick, so we require that it be manually moved rapidly and significantly once a week via the DCS; some units do this on a daily basis. Moving the slide valve frequently can lead to operational fluctuations, as well as pose a risk of accidental operations. On the other hand, not moving it at all may result in sticking. We welcome any advice from everyone.
Activities are certainly necessary, but the frequency needs to be discussed. It is necessary to consider the range of movement of the valve stem in automatic mode; in fact, with normal purge steam, it is sufficient to carry out such activities every ten days or once every half month. If the device does not experience fluctuations, no coking will fall off, and there is no need to worry about poor operation of the slide valve. However, if coking is present, the larger range of movement makes it easier for fluidization to be disrupted; it is therefore recommended not to adjust it too frequently or with excessive amplitude.
The double-acting slide valve will move automatically as the main air flow changes due to variations in the properties of the raw material. The pilot plug valve (sliding valve) can be manually operated. The single-acting slide valve (regeneration slide valve) is adjusted according to the production plan; it is not recommended to move it, as this would cause unnecessary fluctuations. (However, it can help improve the operational skills for subsequent positions.) Under normal production conditions, significant fluctuations are not allowed in the high-temperature butterfly valve (at the smoke extractor inlet). Based on my personal advice, it’s sufficient to move the plug valve a bit; there’s no need to make any other changes. The key is to strengthen regular inspections and pay attention to the normal operation of the purge air and steam.
This device operates twice a week, which is quite necessary; the fluctuations are minimal, so there’s no need to worry.
I believe it is highly necessary to move the double-acting slide valve by 5% every day, in order to ensure that the valve functions properly in case of an accident
I don’t think this is necessary, as your slide valve is used to adjust the amount of catalyst circulating, thereby changing the reaction temperature. When the feed rate is adjusted, the reaction temperature also changes accordingly, and in such cases adjustments are needed. Unless your facility is operating at full capacity, after the reaction temperature has been adjusted there’s no need for further adjustments. You can also manually adjust the opening degree of the slide valve from time to time, but not by too much, to avoid causing significant fluctuations in the overall operation.
There’s no need to try setting it to automatic; those set to manual are difficult to control, so it’s better not to make major changes.
Ours involves adjusting the manual operation every two weeks by about 3%, and the key is to strengthen regular inspections to ensure that the blowing air and steam are functioning properly.