How to purge the system pipelines of a dry gas hydrogen production unit before commissioning? Can it be purged using blasting?
Thread Content
After completing one operating cycle, the dry gas hydrogen production unit is shut down for maintenance. Now that the maintenance is nearing completion, discussions have arisen regarding the plan to restart the unit and perform purging: can blasting be used as a method for purging the hydrogen production unit? Referring to reforming units and hydrogenation units, their hydrogen-handling systems use explosive purging during the purging process before operation. Therefore, it is generally believed that since almost all of the pipelines in hydrogen production units are part of hydrogen-handling systems, explosive purging must also be employed for purging these systems. However, there are those who hold different opinions. First, given the importance and relative sensitivity of the hydrogen production converter tubes and their upper and lower tail pipes, it is doubtful whether they can withstand the impact of blast purging ； Second, due to the plant-wide shutdown for maintenance, hydrogen production was scheduled to begin earlier, which necessarily meant that blasting and purging would take place sooner as well. At that time, the plant’s ventilation system was not yet operational according to the schedule, so there was no purified air available for blasting purposes. May I ask, how do other companies purge their hydrogen production equipment when restarting it after maintenance? Should it be a simple purge with nitrogen, or should blasting be used for purging? If blasting purging is used, should the converter tubes be included?
When performing hydrogen purging here, we use our own raw gas compressor to supply the gas; air is used for this purpose
During hydrogen purging, it is done using the compressor for the own raw material gas. Is it okay for the guy upstairs to use nitrogen?
Does this mean turning on the compressor to enable nitrogen circulation in the system? But this is not pipeline purging. If there are impurities in the system, such as rust, performing a nitrogen circulation in the system will not remove these impurities from it. Moreover, just performing a system nitrogen cycle does not allow one to determine whether the system pipelines are clean. During blasting purging, it is possible to clearly determine how much impurity is present in the pipeline, as well as whether the pipeline has been thoroughly cleaned through blasting purging.
You’ve already been working; do you still do blasting? Aren’t you tired?
Right now, people are arguing about whether to carry out the blasting or not, and there is no consensus. Are you saying that blasting and purging are required before a new unit starts operating, but that no such blasting is needed once it has operated for one cycle and undergone maintenance before starting up again?
Yes, we have been producing hydrogen using dry gas for many years. There was an explosion during the initial startup, but after that we used nitrogen to purge the system; we carried out two small cycles first, then moved on to larger cycles, adjusting the amounts of steam and hydrogen supplied, before feeding in material until the product met the required standards
It’s not the first time this operation is being carried out, so there’s no need for purging (hence there’s even less need for explosive purging); it’s sufficient if the displacement is satisfactory