Regarding petrochemical plants, what devices and measures are in use to address the hydrogen balance between reforming and hydrogenation? How to do hot standby?
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The hydrogen production rate of the reforming unit is approximately 6–7%. For fuel-type refineries that use a combination of small-scale reforming and large-scale hydrogenation, it is entirely possible to meet the hydrogen requirements of the hydrogenation units under National IV standards, as well as those related to high-viscosity diesel in summer. However, there are several challenges: 1. If there are issues with the reforming unit, the hydrogenation unit will stop operating due to a lack of hydrogen supply; thus, the smaller unit forces the larger unit to shut down as well. 2. Even under National IV standards, it is not possible to meet the hydrogen demands of the hydrogenation unit when it operates at full capacity in winter (for low-viscosity diesel). 3. Under National V standards, the hydrogen requirements of the hydrogenation unit still cannot be met, resulting in a significant shortage of hydrogen in winter. Possible solutions and questions for consideration: 1. Install new hydrogen production units that offer high operational flexibility and cost efficiency, in order to address the differences in hydrogen demand between winter and summer. What types of units are suitable for this purpose? Examples include PSA, dry gas hydrogen production (steam cracking) + PSA, membrane separation, etc. How do others combine these units together? Which plan is better? 1. High hydrogen production rate, simple operation and maintenance, high operational flexibility, and a minimum number of units required to solve the problem. 2. When utilizing hydrogen sources from other nearby factories, it is necessary to determine specific criteria such as hydrogen purity, as well as levels of chloride ions, CO, and CO2. 3. What damage does excessive CO and CO2 levels cause to hydrogenation catalysts? What are the internal control standards in this regard? Manager Discussion Group
The hydrogen used in our equipment is produced hydrogen and reformed hydrogen. I hadn’t really thought about this issue before.
It depends on the hydrogen production raw materials available in your area – natural gas, coal gas, methanol, or coking dry gas – as only then can the specific benefits and costs be calculated.
My personal opinion: 1. It is not practical to use reformed hydrogen for diesel hydrogenation, as diesel hydrogenation itself requires a relatively large amount of hydrogen. It is not recommended to use PSA alone; PSA is used for purification, not to increase the hydrogen source. The investment for dry gas hydrogen production plus PSA is relatively high, and the hydrogen supply is stable; however, you are a fuel-based refinery. Membrane separation, like PSA, is used for purification; moreover, current membrane separation technology is not as powerful as it is advertised to be. 2. If there is an external hydrogen source, this should be considered first; the hydrogen content required for diesel hydrogenation is low, with 90% generally being sufficient. 3. We keep CO + CO2 below 20PPM
We reorganize the hydrogen supply for diesel hydrogenation and gasoline hydrogenation, and use methanol-to-hydrogen production to make up for any shortages in hydrogen supply. Methanol-to-hydrogen production offers a wider range of operational adjustments, making it easier to control the amount of hydrogen supplied; moreover, starting up and shutting down this process is also more convenient