1. Stirring, transmission and sealing parts (1) In order to ensure the stability of the transmission, the base of the kettle cover should be platform, and it is often simplified to three-point support because of its thin structure and poor rigidity. In addition to being used on low-speed enamel kettles, it is easy to cause stirring shafts, deceleration racks, and motor chatter on commonly-used reactors. As a result, the shaft seal fails, the material leaks, and wear of the moving parts of the equipment increases.
(2) Improper gear unit configuration. In the case of high shaft seal requirements, such as the use of mechanical seal, the shaft should be used in the smaller gear reducer, and some manufacturers will use the relatively low price of the turbine reducer, due to the large swing shaft, with a stirring shaft oscillation At this time, the mechanical seal failed due to the inability of working conditions. When the pressure inside the kettle is high, the shaft seal leaks even more. If the inside of the kettle is flammable, explosive, poisonous, and corrosive, it can be imagined.
(3) The reducer frame is too short to adjust the mechanical seal and test wheel space. When replacing the mechanical seal wearing parts, it is very inconvenient to disassemble the reducer and the motor. When the deceleration rack is long enough, it only needs to decompose the test wheel, and the others need not move. Although short racks save manufacturers or users a small amount of manufacturing costs, the cost of the man-hours used by the user to service the equipment is usually much higher than the cost savings. At least for the user, calculating the general ledger or long-term accounts is not cost-effective.
(4) There is no positioning bearing in the middle of the reducer frame. The agitator shaft swings too much and the shaft seal fails.
(5) The bottom bearing and the deceleration frame have different axes, or the shaft of the agitator shaft and the output shaft of the reducer are different, which causes the agitator shaft to distort and oscillate. The bottom bearing wears down due to wear and the shaft seal fails.
(6) No test wheel loosening cover. When there is no other measure to prevent the agitator shaft and the test wheel from escaping, the agitator shaft may loosen and cause an accident due to its own weight entering the reactor.
2. Parts and Joints 2.1 Kettle body and heat transfer section (1) The thin steel plate for the kettle body or heat transfer jacket, especially the higher-priced stainless steel plate, is extremely dangerous. The pressure resistance and rigidity of the kettle body are degraded, which can cause the equipment to explode.
(2) Thinned flange material that deforms when the rated load is not reached, resulting in failure of the flange face seal. Even if the sudden failure of the harmless medium at high pressure and high temperature has serious consequences, the harmful medium is even more.
(3) In order to save materials, the head does not press out straight edges, the rigidity of the head drops, and the capacity of the equipment decreases.
(4) In order to ensure the strength of the equipment, anti-corrosion performance and cleanliness of the tank, the double-sided welding of the cylinder, lining base and flange, etc., should also be simplified to external single-side welding. After the inside is less welded, the user is not easy to see in appearance, but the reliability of the equipment is reduced. The inner side of the unwelded joint will form a crack, and the inside of the kettle will easily infiltrate into the material, and it will be difficult to clean. The composition of the infiltrated matter is usually indefinite, and it may be possible for the deep seam corrosion equipment to remain for a long period of time, and may cause contamination of the product after shedding.
(5) The inner wall of the reactor and the inner parts of the kettle are not polished, the inner wall of the kettle is rough, and it is easy to rust and scale. It is difficult to clean the inner wall of the reactor or replace the product.
(6) Confuse the concepts of full volume and nominal volume. Usually the full volume of the equipment is all the space contained in the reactor vessel and the upper and lower heads, while the nominal volume is only the volume corresponding to the jacket of the kettle, which is the volume that can be fed. Obviously the latter is less than the former. Normally, the user requires a nominal volume based on the amount of feed, but a significant number of manufacturers intentionally fool it with full volume. When users do not care, they can make up a lot of money. After the user sees it, they can pretend to be misunderstood. There is a reason for the defense. However, the danger is that when the user is unaware of it, the overfilling of the charging factor exceeds the charging factor, causing the reaction vessel to overload its work. The danger is self-evident.
The sealing surface of the hand hole should be a tongue and groove, which is often changed into a flat surface.
When the hand hole with a tongue and groove is repeatedly opened and closed, the convex surface of the upper cover is easily slid into the tongue and groove, and is automatically positioned. Since the gasket is not easily damaged in the groove, even if it is damaged, the residual piece will remain in the groove, and will not Drop into the kettle. When there is pressure, the gasket is not easy to wash away. After simplification into the plane, the upper cover and the gasket cannot be automatically aligned and the closing and positioning are very troublesome. Each use, the gasket will be displaced, a little careless, it is easy to leak, the exposed gasket is easy to pollute, but also easy to damage. The fallen pieces may fall into the kettle and contaminate the product.
The screw of the hand hole should be a transmission type trapezoidal thread and be changed into a connection type fine thread.
Because the trapezoidal ridge pattern can withstand a large force, the enthalpy distance is large, and when the hand hole is closed, the number of rotation laps is small. In contrast, fine thread threads have many turns and are inconvenient to use; Due to the shallow thread, combined with the dual functions of wear and corrosion, it is easily damaged.
The nozzle is inclined and the discharge port is in the direction of deviation. A considerable number of chemical machinery manufacturers do not pay attention to the welding of the flange, do not understand the direction of the flange. The problem of the equipment taking over the flange can cause the counter-rotating handwheel to be skewed and the follow-on pipe to be deflected. The installation of valves, pipe fittings and pipes is very inconvenient, which not only consumes labor and expense, but also has an unattractive pipeline and is not easy to operate. The material flow is not Smooth, residual material in the dead zone, pollution of the next batch of products.
3. Causes of Defects in the Reaction Vessels The defects in the manufacturing process of the reaction vessel are caused by the failure to manufacture and process according to container standards, component standards, and drawings. There are actually two main reasons!
(1) Economic reasons The main users of the medium and small reactors are many fine chemical plants. These plants are mostly ordered to small and medium-sized chemical machinery factories due to the small scale of equipment and the reduction of equipment procurement costs. While some chemical machinery factories are driven by interests, in order to expand profits, the material costs and working hours are reduced as much as possible, and the manufacturing process is simplified, and even a handful of others are interested in cutting corners.
(2) Technical reasons The degree of crossover and integration of various specialties is low, especially the lack of adequate communication between crafts and mechanical specialties. The device may have some kind of defect at design time! The chemical machinery factory has a low level of technology and has not mastered the technical specifications.
In addition to intentional behavior, many manufacturers do not realize that their own manufacturing methods that they deem irrelevant will bring hidden dangers to future production, endanger safety, and inconvenience maintenance. It has never been thought that the manufacturing process will be simplified or saved in a one-time, short-term, time-saving manner, which will bring many unsafe, inconvenient and inconvenient long-term, even long-term, months to subsequent users and maintenance personnel.
4. Suggestions (1) Promote theoretical studies and technical training to improve business standards. Strengthen the reactor process design, mechanical design and even the user's communication between the manufacturers. Not only do designers and manufacturers have to learn, but users themselves must also learn. Many problems require users to supervise and warn and defend users' rights as consumers.
(2) Adopting new technologies to reduce manufacturing difficulties and reduce maintenance costs on the premise of improving and ensuring the quality of equipment. For example: cancel the middle and high-speed stirring bottom bearing, instead of stabilizing the ring or balance sheet. Use flexible couplings, etc. Both can reduce the concentricity of components on the center axis of the kettle.
(3) Adhere to the approval of design and manufacturing qualifications; quality control and supervision of the design process and manufacturing process; and sound procedures.
(4) As far as possible in the machinery plant acceptance, equipment trial operation. After the problem is discovered, the relatively strong machining capacity and lifting conditions of the machine plant can be used to improve and remedy the problem. If problems are found in chemical plants, they often have to be used because of limited conditions.
(5) Try to use tools, especially special tools, to reduce manual errors.
(2) Improper gear unit configuration. In the case of high shaft seal requirements, such as the use of mechanical seal, the shaft should be used in the smaller gear reducer, and some manufacturers will use the relatively low price of the turbine reducer, due to the large swing shaft, with a stirring shaft oscillation At this time, the mechanical seal failed due to the inability of working conditions. When the pressure inside the kettle is high, the shaft seal leaks even more. If the inside of the kettle is flammable, explosive, poisonous, and corrosive, it can be imagined.
(3) The reducer frame is too short to adjust the mechanical seal and test wheel space. When replacing the mechanical seal wearing parts, it is very inconvenient to disassemble the reducer and the motor. When the deceleration rack is long enough, it only needs to decompose the test wheel, and the others need not move. Although short racks save manufacturers or users a small amount of manufacturing costs, the cost of the man-hours used by the user to service the equipment is usually much higher than the cost savings. At least for the user, calculating the general ledger or long-term accounts is not cost-effective.
(4) There is no positioning bearing in the middle of the reducer frame. The agitator shaft swings too much and the shaft seal fails.
(5) The bottom bearing and the deceleration frame have different axes, or the shaft of the agitator shaft and the output shaft of the reducer are different, which causes the agitator shaft to distort and oscillate. The bottom bearing wears down due to wear and the shaft seal fails.
(6) No test wheel loosening cover. When there is no other measure to prevent the agitator shaft and the test wheel from escaping, the agitator shaft may loosen and cause an accident due to its own weight entering the reactor.
2. Parts and Joints 2.1 Kettle body and heat transfer section (1) The thin steel plate for the kettle body or heat transfer jacket, especially the higher-priced stainless steel plate, is extremely dangerous. The pressure resistance and rigidity of the kettle body are degraded, which can cause the equipment to explode.
(2) Thinned flange material that deforms when the rated load is not reached, resulting in failure of the flange face seal. Even if the sudden failure of the harmless medium at high pressure and high temperature has serious consequences, the harmful medium is even more.
(3) In order to save materials, the head does not press out straight edges, the rigidity of the head drops, and the capacity of the equipment decreases.
(4) In order to ensure the strength of the equipment, anti-corrosion performance and cleanliness of the tank, the double-sided welding of the cylinder, lining base and flange, etc., should also be simplified to external single-side welding. After the inside is less welded, the user is not easy to see in appearance, but the reliability of the equipment is reduced. The inner side of the unwelded joint will form a crack, and the inside of the kettle will easily infiltrate into the material, and it will be difficult to clean. The composition of the infiltrated matter is usually indefinite, and it may be possible for the deep seam corrosion equipment to remain for a long period of time, and may cause contamination of the product after shedding.
(5) The inner wall of the reactor and the inner parts of the kettle are not polished, the inner wall of the kettle is rough, and it is easy to rust and scale. It is difficult to clean the inner wall of the reactor or replace the product.
(6) Confuse the concepts of full volume and nominal volume. Usually the full volume of the equipment is all the space contained in the reactor vessel and the upper and lower heads, while the nominal volume is only the volume corresponding to the jacket of the kettle, which is the volume that can be fed. Obviously the latter is less than the former. Normally, the user requires a nominal volume based on the amount of feed, but a significant number of manufacturers intentionally fool it with full volume. When users do not care, they can make up a lot of money. After the user sees it, they can pretend to be misunderstood. There is a reason for the defense. However, the danger is that when the user is unaware of it, the overfilling of the charging factor exceeds the charging factor, causing the reaction vessel to overload its work. The danger is self-evident.
The sealing surface of the hand hole should be a tongue and groove, which is often changed into a flat surface.
When the hand hole with a tongue and groove is repeatedly opened and closed, the convex surface of the upper cover is easily slid into the tongue and groove, and is automatically positioned. Since the gasket is not easily damaged in the groove, even if it is damaged, the residual piece will remain in the groove, and will not Drop into the kettle. When there is pressure, the gasket is not easy to wash away. After simplification into the plane, the upper cover and the gasket cannot be automatically aligned and the closing and positioning are very troublesome. Each use, the gasket will be displaced, a little careless, it is easy to leak, the exposed gasket is easy to pollute, but also easy to damage. The fallen pieces may fall into the kettle and contaminate the product.
The screw of the hand hole should be a transmission type trapezoidal thread and be changed into a connection type fine thread.
Because the trapezoidal ridge pattern can withstand a large force, the enthalpy distance is large, and when the hand hole is closed, the number of rotation laps is small. In contrast, fine thread threads have many turns and are inconvenient to use; Due to the shallow thread, combined with the dual functions of wear and corrosion, it is easily damaged.
The nozzle is inclined and the discharge port is in the direction of deviation. A considerable number of chemical machinery manufacturers do not pay attention to the welding of the flange, do not understand the direction of the flange. The problem of the equipment taking over the flange can cause the counter-rotating handwheel to be skewed and the follow-on pipe to be deflected. The installation of valves, pipe fittings and pipes is very inconvenient, which not only consumes labor and expense, but also has an unattractive pipeline and is not easy to operate. The material flow is not Smooth, residual material in the dead zone, pollution of the next batch of products.
3. Causes of Defects in the Reaction Vessels The defects in the manufacturing process of the reaction vessel are caused by the failure to manufacture and process according to container standards, component standards, and drawings. There are actually two main reasons!
(1) Economic reasons The main users of the medium and small reactors are many fine chemical plants. These plants are mostly ordered to small and medium-sized chemical machinery factories due to the small scale of equipment and the reduction of equipment procurement costs. While some chemical machinery factories are driven by interests, in order to expand profits, the material costs and working hours are reduced as much as possible, and the manufacturing process is simplified, and even a handful of others are interested in cutting corners.
(2) Technical reasons The degree of crossover and integration of various specialties is low, especially the lack of adequate communication between crafts and mechanical specialties. The device may have some kind of defect at design time! The chemical machinery factory has a low level of technology and has not mastered the technical specifications.
In addition to intentional behavior, many manufacturers do not realize that their own manufacturing methods that they deem irrelevant will bring hidden dangers to future production, endanger safety, and inconvenience maintenance. It has never been thought that the manufacturing process will be simplified or saved in a one-time, short-term, time-saving manner, which will bring many unsafe, inconvenient and inconvenient long-term, even long-term, months to subsequent users and maintenance personnel.
4. Suggestions (1) Promote theoretical studies and technical training to improve business standards. Strengthen the reactor process design, mechanical design and even the user's communication between the manufacturers. Not only do designers and manufacturers have to learn, but users themselves must also learn. Many problems require users to supervise and warn and defend users' rights as consumers.
(2) Adopting new technologies to reduce manufacturing difficulties and reduce maintenance costs on the premise of improving and ensuring the quality of equipment. For example: cancel the middle and high-speed stirring bottom bearing, instead of stabilizing the ring or balance sheet. Use flexible couplings, etc. Both can reduce the concentricity of components on the center axis of the kettle.
(3) Adhere to the approval of design and manufacturing qualifications; quality control and supervision of the design process and manufacturing process; and sound procedures.
(4) As far as possible in the machinery plant acceptance, equipment trial operation. After the problem is discovered, the relatively strong machining capacity and lifting conditions of the machine plant can be used to improve and remedy the problem. If problems are found in chemical plants, they often have to be used because of limited conditions.
(5) Try to use tools, especially special tools, to reduce manual errors.
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