Discuss the preparations needed for chlor-alkali plant overhauls and the precautions to take

The maintenance of acidic units is carried out separately from that of alkaline units. Regarding the chlorohydrogen treatment, during previous overhauls, it was due to the tight schedule set by higher authorities. As a result, chlorine drying and maintenance work on the accident system were carried out simultaneously, which led to sodium hypochlorite mixing with acid in the sewage ditch. This leads to large-scale release of chlorine gas, worsening the conditions in the maintenance area, and it is also unpleasant for people.

The most important thing is to thoroughly fill the hydrogen system with nitrogen; safety must come first.

The question is a bit too broad. But usually this is how we do it. It is mainly carried out in three steps: 1. Prior to the operation: Develop proper safety inspection plans, such as inspection work permits, fire permits, permits for working inside tanks, and other safety-related documents. It is also necessary to ensure that all equipment that needs to be replaced during the inspection has arrived and has passed quality checks, followed by proper cleaning and replacement. Whether all labor protection and maintenance supplies are available, etc. 2. During the process: Parking must be done safely, in strict accordance with the parking procedure sheet; the equipment must be thoroughly purged, especially the chlorine system, the electrolyzer system, the hydrogen system, as well as the nitrogen purging and chlorine drying sulfuric acid systems. Carry out maintenance strictly in accordance with the maintenance operation sheet, and wear appropriate personal protective equipment. Ensure the quality of maintenance, and carry out pressure testing and leak checking before starting up. 3. Afterward: Drive strictly in accordance with the driving operation procedures, paying close attention especially to the equipment and devices that have been repaired.

1. When maintaining the hydrogen system, it is necessary to ensure that the hydrogen system is completely purged with nitrogen. 2. When maintaining the chlorine system, it is necessary to ensure that the chlorine present in the pipes and equipment of that system is completely removed using a fan. 3. When maintaining the caustic soda storage tank, ensure that the hydrogen gas in the upper part of the tank is exhausted. 4. When maintaining the sulfuric acid storage tank, ensure that the acidic gases at the top of the tank are removed.

1. Prepare maintenance manuals to specify the exact timing and details of the maintenance work; gather the materials needed for maintenance and assign the personnel responsible for it. 2. Develop start-up and shutdown procedures. 3. After shutting down the system, carry out material replacement, cleaning, and purging of various systems. The hydrogen system is purged with nitrogen, the chlorine system is purged with air, and the sulfuric acid system is cleaned with water. Analysis must be qualified. 4. For pipelines and equipment that require welding during maintenance, combustible gas analysis must be conducted, and various permits and certificates related to the maintenance work must be obtained. Blind flanges must be used for maintenance work on pipeline equipment connected to materials. 5. Conduct a system airtightness pressure test before driving. The hydrogen system was purged with nitrogen, and the analysis showed it to be satisfactory. 6. Prepare the raw materials and additives in accordance with the system’s startup sequence; brine is usually prepared 36 hours in advance for startup. Strictly follow the startup procedure as outlined, and continuously analyze the purity of chlorine and hydrogen after electrolysis startup. Once the process control requirements are met, proceed with the startup of the liquefaction and synthesis systems. During driving, it is important to pay close attention to the hydrogen content in chlorine, the purity of chlorine gas and hydrogen gas, as well as changes in system pressure and temperature. 7. Unified command, careful operation, safety first. This post was last edited by yzhms on 2009-3-24 22:36.]

First, a maintenance plan needs to be established. And ensure sufficient inventory, with all the materials and tools required for maintenance ready, as well as the necessary personnel. Also, prepare the materials needed for the next drive. Stop the operation on the scheduled date; replace the brine in the electrolytic cells. After stopping, purge the hydrogen system with nitrogen and evacuate the chlorine system. On posts where gases are present, a fire hazard analysis must be conducted and a fire work permit obtained. It is necessary to follow the operating procedures; no unauthorized commands or operations are allowed, and fixed safety supervisors must be assigned to each maintenance site. Remember, safety first.

Evacuate the gas from the chlorine system to prevent explosions after startup due to the accumulation of hydrogen in areas that are difficult to reach by certain equipment. Purge the hydrogen system with nitrogen, and carry out pressure testing and leak checks before starting up (last time, our plant was forced to delay startup because of a leak in the concentrated acid cooler)

Just combine what the people upstairs have said – what each one says makes sense, but nothing is comprehensive or detailed enough. Who has been in charge of the start-up, shutdown, and major overhauls of the chlor-alkali system? So organize his things and take them out – that’s what’s good. Thank you!

My unit is a diaphragm electrolyzer; I was in charge of starting up the system! I’m not sure what specific content you need?

For the major maintenance, it is necessary to determine the scope of the work and carry out maintenance on each system separately. However, after shutting down the plant, the chlorine and hydrogen systems must be thoroughly purged with nitrogen. When working on the liquid chlorine system, it is advisable to use blind flanges to isolate the liquid chlorine storage tanks. At the same time, absorbent alkali for handling accidents and alkali for startup operations (in the ion exchange membrane production process) should be prepared in advance.

I am in charge of safety at the company. I believe that for chlor-alkali plant overhauls, in addition to preparing materials, construction resources, and lifting equipment, we must also develop plans for safe shutdown, safe maintenance, and safe restart of the plant. Specifically: 1. Drive safely ； 1. System startup sequence scheduling 2. System pressure and temperature, material discharge 3. Disconnection of system power supply 4. Disconnection of pipelines and tank areas II. Safe maintenance 1. Cleaning and purging 2. Inspection 3. Handover of the equipment to the maintenance team in a safe condition 4. Procedures for safe maintenance III. Safe startup 1. Pressure testing after maintenance 2. System inspection and verification 3. Safe startup plan

Preparation for maintenance and shutdown: 1. Develop a reasonable and detailed maintenance plan, inspect each piece of equipment one by one; for those included in the maintenance plan, detailed maintenance procedures and safety measures must be established, with a dedicated person responsible for them； 2. Prepare the tools and machinery; identify what tools are needed, as well as any large-scale equipment, and arrange for them in advance if they are not available ； 3. Prepare a detailed material plan; for non-standard components, they must be processed more than a month in advance to ensure that they are all on site by the day before the maintenance work begins ； 4. Mobilize the team, carry out ideological work and safety awareness campaigns, and work overtime to complete tasks safely and efficiently. 5. Ensure proper purging of the hydrogen system, especially in all dead corners; if there is a long-term shutdown or welding work needs to be done on the hydrogen system, it should be purged with nitrogen for more than half an hour ； For those that cannot be purged through system displacement, steam or nitrogen should be used for staged purification ； 6. Chlorine should be sent to the accident chlorine handling system; pay attention to the concentration of the alkaline solution. If the chlorine system requires maintenance, it must be thoroughly purged, and during maintenance, a fan can be used to continuously draw air into the accident chlorine system ； 7. After all pumps and equipment have been shut down, the materials in the areas that need maintenance should be removed, the necessary materials should be prepared, and various permits and documents should be obtained ； Responsibilities and procedures for maintenance personnel: Each section leader is responsible for implementing the plans for all maintenance tasks in their respective section, as well as enforcing the necessary safety measures ； The deputy plant manager is responsible for overseeing the implementation of safety and maintenance plans ； Safety officers conduct on-site inspections to supervise any instances of improper instructions, unlawful operations, failure to carry out fire hazard analyses in a timely manner, or failure to follow the required procedures for issuing permits. They also check whether safety protective equipment is being worn properly ； The technician is responsible for evaluating the personnel at the maintenance site, the use of materials, the condition of the maintenance site itself, and the completion of tasks; they also keep records of task completion, canceling one entry once a task is completed ； The materials officer is responsible for securing any temporarily unavailable materials, as well as designing and manufacturing non-standard parts. They also keep track of the models and specifications of special parts to prepare relevant information for future management purposes ； The branch plant manager is responsible for overall coordination; in cases where there is a shortage of personnel or equipment, resources are allocated accordingly based on the progress of the maintenance tasks. After the maintenance is completed, the branch factory organizes various work teams and technicians to conduct item-by-item inspections; once everything passes, they sign to confirm it (after the system starts operating normally, lessons are learned and awards are given). Commissioning: A detailed commissioning plan is developed based on the results of the inspection and maintenance work, with dedicated personnel responsible for its implementation. This includes performing leak tests on the system before commissioning, ensuring that the hydrogen system is free of oxygen and operates properly, that all pumps are functioning correctly, that the chlorine compressor and hydrogen compressor operate normally, that the power supply system, control system, and interlocks have been properly tested, that utility systems such as tap water, circulating water, electricity, gas, and steam are in good working order, that the necessary personnel are on site, and that the brine meets the required standards. . . . Wait, proceed according to the normal driving plan.