General repair methods when a reactor is damaged

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A common piece of equipment in chemical plants – the reaction vessel – is a type of composite reaction container that can be damaged for various reasons during operation, leading to the suspension of production. Today, we will focus on the general repair methods for when a reaction kettle is damaged, as well as the specific repair approaches for glass-lined reaction kettles and stainless steel reaction kettles. 　　I. Fault symptoms: Shell damage (corrosion, cracks, holes)
Causes of the fault:
1. Exposure to media radiation (pitting corrosion, intergranular corrosion) ； 　　2. Thermal stress leads to cracking or alkali embrittlement ； 　　3. Wear thinning or uniform corrosion. 　　Solution: 1. Tanks lined with corrosion-resistant materials require re-lining or local welding repairs ； 　　2. Stress must be relieved after welding, and any cracks that occur need to be repaired ； 　　3. If it exceeds the minimum allowable thickness specified in the design, the main body needs to be replaced. 　　II. Fault symptoms: Excessive temperature and pressure
Causes of the fault:
1. Malfunctioning instruments; inadequate control ； 　　2. Misoperation ； Improper proportioning of raw materials ； Causes a severe reaction ； 　　3. Side reactions occur due to poor heat transfer or stirring performance ； 　　4. Malfunction of the intake valve: excessive intake pressure. 　　Solution: 1. Inspect and repair the automatic control system, and strictly follow the operating procedures ； 　　2. In accordance with the operating procedures, carry out emergency pressure relief, feed materials in the prescribed quantities and at scheduled times, and take strict precautions to avoid misoperations ； 　　3. Increase the heat transfer area or remove scale to improve heat transfer; repair the mixer to enhance mixing efficiency ； 　　4. Close the main steam valve and cut off the steam to repair the valve. 　　III. Fault symptom: Sealing leakage 　Cause of the fault: 　Packing seal 　1. Wear or corrosion of the stirring shaft at the packing area, resulting in an excessive gap ； 　　2. Improper position of the oil ring or blocked oil passages prevent the formation of an oil seal ； 　　3. The gland isn’t tightened properly; the packing is of poor quality; or it has been used for too long ； 　　4. Corrosion of the stuffing box. 　　Mechanical seal: 1. Deformation of the end faces of the stationary and rotating rings, resulting in damage ； 　　2. The end-face specific pressure is too high, causing thermal deformation of the friction pair ； 　　3. The wrong material is used for the sealing ring, the clamping force is insufficient, or the V-shaped sealing ring is installed in the wrong direction, resulting in a loss of sealing performance ； 　　4. Excessive deviation between the axis and the end face of the stationary ring ； 　　5. Unstable operating pressure and temperature; hard particles enter the friction pair ； 　　6. The shaft string length exceeds the specified limit ； 　　7. Sealing leakage at the joints where the rotating and stationary rings are fitted or bonded. 　　Treatment method: Packing seal
1. Replace or repair the agitator shaft, and machine it on a machine tool to ensure the required surface roughness ； 　　2. Adjust the position of the oil ring and clean the oil circuit ； 　　3. Compress the packing, or replace it ； 　　4. Repair or replace ； 　　Mechanical seal 　　1. Replace the friction pair or re-grind it ； 　　2. The specific pressure should be adjusted appropriately; the cooling system should be strengthened to remove heat in a timely manner ； 　　3. The material used for the sealing ring should be appropriate, and its installation must be proper to ensure sufficient compression force ； 　　4. Stop the machine, realign it, ensuring that the deviation from verticality is less than 0.5 mm ； 　　5. Strictly control the process parameters; particles and crystals must not enter the friction pair ； 　　6. Adjust and maintain to bring the shaft’s play within the standard range ； 　　7. Improve the installation process: either ensure an appropriate amount of interference, or use a good-quality adhesive that provides strong adhesion. 　　IV. Fault symptoms: Abnormal noises inside the tank. Causes of the fault: 1. The agitator rubs against the components inside the tank (such as coiled tubes, thermometer tubes, etc.) or against the tank walls ； 　　2. Agitator loose ； 　　3. Liner bulging, colliding with the agitator ； 　　4. The mixer is bent or the bearings are damaged. 　　Solution: 1. Stop the machine for maintenance and alignment, ensuring a certain distance between the mixer and its attachments ； 　　2. Stop the machine for inspection and tighten bolts ； 　　3. Repair blisters or replace the lining ； 　　4. Inspect or replace the shaft and bearings. 　　V. Fault symptom: Enameled stirrer comes off 　Cause of the fault: 　1. Corrosion and fracture caused by the medium ； 　　2. The rotation directions of the motors are opposite. 　　Solution: 1. Replace the enamel shaft or repair it with fiberglass-reinforced plastic ； 　　2. Shut down to change direction. 　　VI. Fault phenomenon: Air leakage from the flange of the enamel kettle 　　Cause of the fault: 　　1. Damage to the porcelain surface of the flange ； 　　2. Unreasonable selection of washer material, incorrect installation of joints, gaps, misalignments ； 　　3. The clips are loose or insufficient in number. 　　Treatment methods: 1. Repair, apply anti-corrosion paint or resin ； 　　2. According to the process requirements, select the washer material; the joints of the washers must overlap, and their positions should be uniform ； 　　3. As required by the design, there must be a sufficient number of clamps, which must be tightened properly. 　　VII. Fault symptoms: Scaling and micro-pores on the porcelain surface. Causes of the fault: 1. Acidic impurities enter the jacket or stirrer shaft tube, resulting in hydrogen embrittlement ； 　　2. The porcelain layer is not dense, posing a risk of micro-pores. 　　Treatment method: 1. Neutralize with sodium carbonate, then rinse with water or carry out repairs; in cases of severe corrosion, replacement is required ； 　　2. Those with a low number of micropores can be repaired, while severe cases require replacement. 　　VIII. Fault symptoms: The motor current exceeds the rated value.
Causes of the fault:
1. Bearing damage ； 　　2. Low temperature in the kettle, and the material is viscous ； 　　3. The spindle speed is relatively high ； 　　4. The agitator diameter is too large. 　　Solution: 1. Replace the bearing ； 　　2. Adjust the temperature in accordance with the operating procedures; the viscosity of the material should not be too high ； 　　3. Keep the spindle speed within a certain range ； 　　4. Make appropriate adjustments. 　　The above are the general maintenance methods for reaction kettles. Below are the specific maintenance methods for glass-lined reaction kettles and stainless steel reaction kettles: Glass-lined reaction kettle: https://attach01.hcbbs.com/forum/201810/17/170141zq8d6607381aq2ea.jpg Glass-lined reaction kettles possess both the mechanical strength of ordinary metal equipment and the stability of glass, and they are widely used in chemical production. However, due to inherent quality issues of the enamel itself, as well as various external forces and stresses during use, the corrosiveness of the medium, sudden changes in operating conditions, transportation, and other factors, it is very easy for damage such as flaking of the enamel surface, cracking, and perforations to occur, thereby affecting the proper operation of the equipment. 　　How to repair it One repair method is re-glazing. This approach requires removing the damaged equipment and sending it to the manufacturer, which is time-consuming, labor-intensive, and costly. 　　For example, the repair time for a glass-lined reactor is 30 days; the repair cost for a 5000L reactor is approximately 20,000 yuan, while the repair cost for a 1000L vessel is about 0.6 million yuan. The repair cost for one tower section is roughly 0.2 million yuan. Moreover, with each re-enameling process, the steel plate becomes thinner, and its strength significantly decreases. Generally, for normally used glass-lined reactors, re-enameling should not be performed more than three times—especially in cases where there is extensive chipping or for larger equipment such as reactors, tower sections, storage tanks, etc. 　　When there is minor damage, it is not necessary to replace the entire equipment; instead, an appropriate repair method should be used. Failure to do so can lead to the reactor being corroded by the solvents inside it, with the damage to the enamel surface spreading rapidly, resulting in unexpected losses such as production shutdowns, safety accidents, and environmental pollution. 　　Another repair method is to use various patching materials directly. This method is mainly used to repair local damage to the surface linings of glass-lined equipment and its components. This method for repairing time periods is inexpensive. If polymer repair materials (titanium alloy enamel repair agents) are used to fix corrosion, enamel loss, or perforations in glass-lined equipment, the repair can be completed within a single day, with repair costs ranging from around 100 to 1000 yuan. 　　The specific procedure is as follows: 1. Surface treatment. This is a crucial step for ensuring successful repair. After identifying the area to be repaired, remove any debris from the damaged portion. Use tools such as files, grinding machines, or angle grinders to clean up the areas where the enamel has worn off or where holes have formed. There should be no residue from corrosion, such as enamel or metal shavings, on the surface; the metal should show its natural color, and the surface should be roughened – the rougher, the better. 　　2. Cleaning　Wipe clean the surface to be repaired using a cleaner (acetone or alcohol). The cleaning area should be larger than the surface to be cleaned, in order to prevent the cleaned surface from being contaminated again. 　　3. Glue preparation 　　The domestic series of glass-lined repair compounds are two-component, paste-like substances: A is the main component, while B is the curing agent. Place the main ingredient and curing agent in a clean container at a ratio of 3:1, then stir thoroughly until they are well mixed (adjust the amount of adhesive according to the size of the area to be repaired). 　　4. Applying the adhesive First, apply a small amount of the repair agent evenly to the surface of the equipment that needs repair. When applying the adhesive, move in one direction while applying pressure; grind and press it firmly as you apply it to eliminate any bubbles and allow air to escape, ensuring that the repair agent makes tight contact with the surface of the equipment. 　　After applying it for the first time, apply the remaining repair material to the parts of the device that need repair, so that they reach the desired dimensions. If machining is required after curing, be sure to leave a margin. 　　5. Curing 　　The repaired area of the equipment is baked using an iodine-tungsten lamp; after 6 to 12 hours of baking (depending on the ambient temperature), the degree of curing can be checked by listening for the sound of tapping. Once the repair material has cured, it can be used. 　　Stainless steel reaction vessels: https://attach01.hcbbs.com/forum/201810/17/170156kx4k5311lx23yoi1.jpg. Stainless steel reaction vessels feature rapid heating, high-temperature resistance, corrosion resistance, cleanliness, no environmental pollution, the ability to function without a boiler for automatic heating, and ease of use. 　　When using a stainless steel reactor, it is necessary to close the valve for the refrigerant inlet pipe, drain all remaining refrigerant from within the reactor and its jacket, then add the material and start the mixer. Then turn on the steam valve and the electric heating source; once the desired temperature is reached, first turn off the steam valve and the electric heating source, and after 2–3 minutes, turn off the mixer. 　　After processing is complete, and all residual condensate in the pot and jacket has been drained, it should be rinsed promptly with warm water to remove any stuck material. Afterwards, the inner walls of the container should be thoroughly cleaned with alkaline solution at 40°C to 50°C, followed by rinsing with clean water. 　　When there is no material (heat-absorbing medium) inside the stainless-steel reactor vessel, i.e., when it is empty, the steam valve and electric heating power must not be turned on. Special care must be taken to ensure that the steam pressure does not exceed the rated operating pressure. 　　Repair: During use, stainless steel reaction vessels are often subject to mechanical impacts and sudden temperature changes, which can cause defects such as glaze loss, cracks, bubbles, pores, and other damages to the surface coating. Such defects are absolutely unacceptable in equipment coated with enamel; once they occur, repairs must be carried out. On-site repair compounds using polymer composites are two-component composites based on polymer resins, alloy steel powder, or wear-resistant ceramic powder, along with a curing agent. Compared to ordinary resin-based repair agents, polymer composite materials rely on their own finer polymer structure, which gives them stronger adhesion as well as excellent corrosion and anti-erosion properties. The polymers can even penetrate into the metal, forming a tighter protective layer of polymer composite material. Repair process: Surface cleaning → Rust removal → Cleaning with anhydrous alcohol → Application of the base repair compound → Application of the topcoat repair compound → Curing → Use. 　　Maintenance
When maintaining stainless steel reactors, it is necessary to constantly monitor the operating condition of the entire equipment and the reducer. If there is a shortage of lubricating oil in the reducer, it must be replenished immediately. The electrically heated medium oil should be replaced every six months. Safety valves, pressure gauges, distillation ports, heating rods, electrical instruments, etc., located on parts such as the jacket and lid must be inspected regularly. In case of any malfunctions, they should be replaced or repaired without delay. When the equipment is not in use, its inner and outer surfaces must be thoroughly cleaned with warm water. The vessel body should be frequently wiped down to keep its exterior clean and its interior surface shiny, thereby ensuring its durability.