In the Asahi Kasei natural bipolar ion-exchange membrane soda-making process, which control interlock points are prone to cause shutdowns?

Chain shutdown due to poor control of chlorine-hydrogen pressure difference

Chain situation: II-C-1.1 Automatic shutdown of the rectifier – The DC power for electrolysis in each electrolyzer is automatically shut off under the following conditions. (1) Abnormal potential difference in the electrolyzer (EdIZA-230) (2) Direct current in the electrolyzer exceeds the normal level (IIZA-230) (3) Grounding of the electrolyzer (rectifier) (4) Insufficient flow rate of saltwater or alkaline solution (FICZA-231, FIZA-232) (5) The fresh saltwater supply valve is open (ZV-241). The direct current used for electrolysis in all electrolyzers is automatically turned off under the following conditions. (1) Excessively high pressure of chlorine or hydrogen (PICZA-216, PIZA-217, PICZA-226, PIZA-227). (2) Abnormal difference in gas pressure (PDIZA-200). (3) Abnormal liquid level in the anode fluid circulation tank or cathode fluid circulation tank (LICZA-260, LICZA-270). (4) Shutdown of instrument power supply (YL-100). (5) Shutdown of instrument air supply (PIZA-520). (6) Emergency stop button (YL-103). (7) Failure in downstream processes. II-C-1.2 Other interlock systems: (1) When a rectifier stops, the corresponding hydrochloric acid supply valve (FCV-211) closes. (2) When a rectifier stops, the corresponding brine supply valve (FCV-231) maintains a normal flow rate, and LICZA-260 shuts down when an HH alarm is triggered. (3) When a rectifier stops, the corresponding brine supply valve (ZV-231) is switched to the brine concentrate valve (ZV-241). (4) When all rectifiers stop, the following devices operate simultaneously. (A) The brine supply valve leading to the secondary saline water (FCV-265) is closed. (B) The HCl main valve (ZV-350) is closed. (C) The pure water valve (FCV-221) is closed. (D) The N2 distillation valve (ZV-279) is opened, and (FCV-279) is opened. (5) When the liquid level in the dechlorination tower (LICZA-310) is higher than the normal value, the liquid level control valve of the waste brine feed (LCV-260) closes.

There are many chains. Generally, several aspects must be properly controlled. Chlorine-hydrogen pressure difference, acid addition amount, water addition amount, abnormal cell potential (offset of the center point), manual shutdown in case of abnormalities.

1. Low flow rate of anode solution/cathode solution. 2. Excessively high/low pressure difference between chlorine and hydrogen. 3. Low pressure of instrument air. 4. UPS power failure. 5. Low liquid level in the anode solution/cathode solution sumps. 6. Rectifier power failure. 7. Cell equilibrium voltage. 8. Emergency stop button activated. 9. Excessively high pressure of chlorine/hydrogen. 10. ZV241 automatically activated, etc. Last edited by yzhms on 2009-2-24 17:57.]

There is a sequential logic diagram in the design process; take a look at it and you’ll understand.

The friend on the third floor explained it in great detail. Your operators must have received training; otherwise, it’s hard to say what will happen. Generally, when operating the equipment, it’s important to maintain a stable pressure difference between chlorine and hydrogen. The function of interlocks is to protect the equipment, especially the ion exchange membrane. Once an interlock activates, it causes the system to stop operating. One thing to note is that if there’s a shutdown of a single tank, and the DCSS detects this in time, it’s possible to adjust the pressure difference and avoid a system shutdown due to the interlock. If this opportunity is missed for even a short period, the entire system will shut down. This post was last edited by yzhms on 2009-2-24 at 17:58

One more thing: the power supply failed, and both the chlorine compressor and the hydrogen compressor stopped working. It can also cause chain stoppages.

The friend on the 3rd floor already explained it in great detail; it’s quite good!

Hehe, I think the interlock systems that are prone to causing shutdowns include: 1) EDIZA-230, which is related to cell voltage; it’s easy for us to read the values related to it. This interlock needs to be disabled during electrolyzer leak testing, when filling the electrolyzer with liquid, and during shutdowns – and this makes it easy for an interlock-induced shutdown to occur. 2) Chlorine-hydrogen pressure and pressure differences; strict control is required for these aspects, mainly to protect the membrane. Other issues that may arise less frequently include saltwater flow rate, alkali solution flow rate, oil pressure, instrument power supply, low instrument air pressure, grounding protection, and levels in circulation tanks D270 and D260, among others