Pre-heating steam
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Should the pre-raising steam also be adjusted as the processing volume changes? How exactly will it change? My device uses the MIP process.
For the pre-heating steam, the orifice plate is already specified in the design; thus normal production can proceed, and no adjustments are needed after switching to an orifice plate on the bypass line
The design usually specifies the amount of steam required; for catalytic processes, this figure generally ranges from 3% to 20%, with the specific value varying depending on the process. . . Please review the preliminary design; you will find it in the section on operating parameters. . . :lol
If the designed processing capacity is 6000 T/D and the current processing capacity is 7000 T/D, does the pre-heating steam need to be adjusted? ? ?
There’s no need to adjust it, right? Whether the processing volume is high or low, the pre-heated steam output of our equipment is 8 tons per hour; it seems to have little to do with the processing volume.
1. The pre-heating steam is not a orifice plate but a control valve. 2. Since it is a control valve, regulation is possible; generally, the flow rate does not change much, so regulation is rare. If the flow rate decreases significantly, in order to maintain the linear velocity inside the lift pipe, the amount of steam used for pre-heating will also be increased accordingly. 3. Once the interlock system at the reaction unit activates, the pre-heating steam is automatically opened fully to prevent the lift pipe from becoming clogged. 4. In short, the amount of pre-heating steam is adjusted based on the density in the pre-heating section, the pressure drop, and the temperature distribution inside the lift pipe
What needs to be adjusted is the pre-lift mechanism: before the catalyst comes into contact with the high-temperature catalyst, it is pushed to the bottom of the lift pipe by pressure differences, and then transported upward by the pre-lift medium. As the processing volume increases, the catalyst circulation rate rises as well; therefore, the amount of pre-lift medium required also increases
I’d like to ask gently, what is your target steam pressure increase?
What the previous moderator said makes sense; the amount of steam supplied can be adjusted. As long as all the relevant parameters remain stable, there is generally no need to adjust the steam supply. The key is to check for any abnormalities. Additionally, sometimes the stripping volume needs to be adjusted when steam is switched to air or air is switched to steam. The specific circumstances are another matter!
For pre-raising here, 1.0 Mp steam and dry gas are used, while 3.5 Mp medium-pressure steam is employed for stripping and preventing coking at the tower top
Adjustments are generally not necessary; it mainly depends on whether the density in the pre-lift section and the linear velocity of the lift pipe are appropriate, and adjustments are made based on these values.
Adjustment is necessary because when the processing volume is high, the amount of oil and gas is also high, and it possesses a certain lifting force; therefore, when the processing volume decreases, the pre-lifting steam amount needs to be increased.
The steam supply here is adjusted frequently, mainly by adjusting the amount of pre-raising steam based on the density in the pre-raising section. Sometimes the processing volume decreases significantly; to maintain the linear velocity inside the lift pipe, the amount of steam used for lifting and atomization is increased accordingly. If the processing volume is high and the catalyst circulation rate is large, the amount of steam used for lifting must also be increased
About 10% is the volume of vapor resulting from intense catalysis and deep catalysis such as Dcc. . . :lol
Whether the pre-heating steam needs to be adjusted depends on the conditions of the installation; it is not necessary to adjust it in cases where flow orifice plates are used, while in cases where control valves are used, appropriate adjustments generally need to be made based on the production conditions. The amount of steam to be pre-heated should be adjusted according to the production capacity and the density of the pre-heating section.
We use control valves here; the pre-lift steam needs to be adjusted – it should be increased when the processing volume is high, in order to maintain the lifting force! Here, the amount of dry gas and pre-heated steam that we use for pre-raising is generally kept around 3 tons. When the processing volume was smaller, the ratio of dry gas to steam was 2/1; now that the processing volume has increased, it is 1.1/1.9
My device also uses the MIP process; although I don’t have any practical experience yet, I agree with what was said on the second floor – generally, the catalytic efficiency ranges from 3% to 20%. The exact amount used depends on the production load. However, during normal production, our equipment uses dry gas as the pre-lift gas; steam pre-lifting is only used at the start-up stage. This is because the use of steam increases the energy consumption of the device, the amount of wastewater discharged, and also raises the likelihood of hydrothermal deactivation of the catalyst.