Clarifying doubts about the temperature difference between hydrogen and oxygen in electrolyzers

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The last edit to this post was made by Han Guang Duan Shui on 2009-11-10 at 09:39. At the end of October this year, the DQ-6 electrolyzer, which had been in use for nearly 20 years, was taken out of service. A new DQ-6 electrolyzer of the same type was purchased from Harbin Machinery United; it was installed, cleaned, steamed, treated with alkali solution, and tested – all proceeded normally, and it was put into operation. But then problems arose. Question 1: An old piece of equipment that has been in use for nearly 20 years has never had its temperature difference between the positive and negative terminals of the electrolyzer measured. Occasionally, I came across the operating procedures for the hydrogen production unit at Huaibei Power Plant (model DQ-4), which state: [4.5.5.3 The temperature difference between the two terminals of the electrolyzer should be less than 20°C]. So I immediately used an infrared thermometer to check the temperature of a new electrolyzer, and found that the temperature difference was 31–33 degrees. I have some concerns and would appreciate an explanation. Question 2: Since I have only been working at this company for a short time, the process engineers mentioned that in older electrolyzers, the temperature difference between the hydrogen and oxygen outlets was supposed to be no more than 5 degrees. However, the existing company operating procedures from 1991 and 2007 do not mention this temperature control requirement; the practice of keeping the temperature difference below 5 degrees is merely passed down orally. When the temperature difference exceeds 5 degrees, the alkali solution filter is cleaned to bring the difference back down to 1–2 degrees, and this condition can be maintained for about 15 days, due to poor flow of the alkali solution. Now, after driving for 16–24 hours, the temperature difference reaches 8–10 degrees. After investigating the cause, the filter was cleaned, and the temperature difference dropped to 2–4 degrees immediately; however, after another 16–24 hours, it rose back to 8–10 degrees. The filter has been cleaned almost 10 times now, but the problem persists. I saw the operating procedures of Huaibei Power Plant [7.2.5 Large temperature difference between the positive and negative terminals of the electrolyzer and at the hydrogen and oxygen outlets. 7.2.5.1 Causes: 7.2.5.1.1 Clogged filters, resulting in poor circulation of the alkaline solution.] 7.2.5.1.2 Blockage of the electrolyzer exhaust pipe or the alkali solution holes inside the cell. 7.2.5.1.3 The cooling water flow rate in the hydrogen-oxygen separator is uneven. 7.2.5.1.4 The electrolyte concentration is too high or too low. 7.2.5.2 Treatment: 7.2.5.2.1 Clean the filter or close the inlet and outlet valves of the filter, and operate by opening the bypass valve. 7.2.5.2.2　Tank stopback flushing. 7.2.5.2.3 Check whether the alkali solution concentration is normal. 7.2.5.2.4 Adjust the cooling water inflow rate to the hydrogen-oxygen separator. It was very enlightening; I tried to imitate the approach, but the system hasn’t been very stable since then. The temperature difference between the positive and negative electrodes remains unchanged, as does the temperature difference at the hydrogen and oxygen outlets. I called the manufacturer, and they said that a temperature difference of around ten degrees at the hydrogen and oxygen outlets is normal; they didn’t ask about the temperature difference between the positive and negative electrodes. I hope for an explanation! !