What is the usage experience among experts: dry gas pre-lifting used alone, steam pre-lifting used alone, or a combination of the two?
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Conduct a survey to find out which units are still using dry gas pre-boosting, and which units are using steam alone What devices use dry gas alone rather than both dry gas and dry gas vapor? Is there any comparison in terms of usage effects?
The effect should be similar; it’s just that when dry gas is used, the pressure in the subsequent absorption and stabilization system becomes too high
The compressor load issue should be taken into consideration; the effect will be similar
The condition for dry gas pre-raising to reduce coking is that hydrogen must be activated at 704 degrees； When the carbon content in the regenerant is below 0.15%, passivation is completed within one second. It is considered that for devices with a regenerator at 716 degrees and heavy metals at 3000 PPM, adopting a dry gas pre-boosting process yields better results. Currently, all the units are operating at full capacity, and the dry gas cycle inevitably consumes part of the compressor capacity. The safety factor using dry gas also decreases. Our device uses only pre-heated steam.
The condition for dry gas pre-raising to reduce coking is that hydrogen must be activated at 704 degrees； When the carbon content in the regenerant is below 0.15%, passivation is completed within one second. It is considered that for devices with a regenerator at 716 degrees and heavy metals at 3000 PPM, adopting a dry gas pre-boosting process yields better results. Currently, all the units are operating at full capacity, and the dry gas cycle inevitably consumes part of the compressor capacity. The safety factor using dry gas also decreases. Our device uses only pre-heated steam.
Personal opinion: I disagree with what you say. In terms of heat capacity, the heat melting capacity of dry gas is much lower than that of steam; therefore, to reach 500°C, more heat is required from steam. The amount of catalyst in circulation should not decrease but rather increase. An increase in the catalyst circulation volume means increased catalyst activity, and many plants want to increase the amount of catalyst in circulation
The specific heat of dry gas is roughly similar to that of water vapor; for example, the specific heat of superheated steam at 250 degrees and 1.0 MPaG is about 0.52, while that of dry gas is around 0.6–0.7. Additionally, their average molecular weights are comparable, at around 18, and these are all important factors that enable the two to be used interchangeably (with minimal impact from such substitution). However, when the temperature of dry gas rises from 40 degrees to around 500 degrees, a large amount of heat is required, which allows for an increase in the circulation rate of the catalyst—a scenario that is generally desirable. Unfortunately, the proportion of dry gas used in this context is too small. The main reason for introducing dry gas pre-boosting is its ability to passivate heavy metals; the main drawback, however, is the increase in the load on the gas compressor and the systems downstream of it.