Abstract: A detailed analysis was conducted on the causes of problems such as flower spots on the conversion furnace tubes, rapid decrease in heat transfer efficiency of the waste heat boiler, and overheating of the medium temperature shift reactor bed in a domestic natural gas hydrogen production unit, and corresponding solutions were proposed. The results showed that the main reasons for the occurrence of flower spots in the converter tube include：①high sulfur and chlorine impurity content in the feed gas, ②low processing load of the device and frequent adjustment of the device processing capacity, ③improper catalyst loading, resulting in "bridging" phenomenon, ④catalyst coking, ⑤improper adjustment of the converter furnace nozzle, ⑥the impact of rapid heating/cooling speed on the strength of the conversion catalyst during repeated start-up and shutdown processes. The reason for the rapid decrease in heat transfer efficiency of the waste heat boiler is that the anti-coking additive K2O in the catalyst is taken away to form scaling, resulting in a decrease in heat transfer rate.The rapid decrease in heat exchange efficiency of the waste heat boiler is the main reason for the bed overheating of the medium temperature shift reactor. To address these issues, measures such as strictly controlling the frequency and rate of load adjustment, controlling the rate of change in feed gas flow rate and temperature rise/fall rate, optimizing the combustion state of the converter, implementing medium pressure steam thermal circulation, and injecting water into the inlet of the medium temperature shift reactor are proposed. The comprehensive implementation of the above measures can ensure the continuous and stable operation of the hydrogen production unit.

Key words: steam reforming, hytrogen production, flower spot, waste heat boiler, medium temperature shift reactor