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2022 / 07 / 04
Highly saline wastewater is usually defined as wastewater with a total dissolved solids (TDS) mass fraction greater than 3.5%. In addition to inorganic salts in the form of Cl-, SO42- and Na+ ions, this type of wastewater also contains ions such as Ca2+, Mg2+, NH4+, HCO3-, which are prone to chemical change into scale, and impurities such as chemical oxygen demand (COD) and suspended solids (SS). 5% of the total volume of wastewater was generated in China in 2015, with an emission of about 997.5 million tons. If high-salt wastewater enters the water body directly, it will eutrophicate the water body and algae will multiply rapidly, which will lead to the deterioration of water quality and the death of fish and other organisms in large quantities. In November 2007, the State promulgated the National Environmental Protection Eleventh Five-Year Plan, which requires the promotion of wastewater recycling in key industries such as iron and steel, electric power, chemical industry and coal, and efforts to achieve less or zero discharge of wastewater. In February 2017, the National Energy Administration issued the "Thirteenth Five-Year Plan for Demonstration of Coal Deep Processing Industry", which requires new demonstration projects without sewage bodies to resourcefully utilize high-salt wastewater by using technologies such as crystallization and salt separation. Zero discharge" treatment of high salt wastewater at home and abroad generally adopts evaporation pond natural evaporation, multi-effect evaporation crystallization, mechanical steam recompression evaporation process. The natural evaporation of evaporation ponds is to evaporate water by using the natural evaporation of solar energy, so that the salt is left at the bottom of the pond for regular cleaning. Mechanical steam recompression evaporation process because of steam compressor temperature rise 8 ~ 10 ℃, often used with falling film evap
2022 / 06 / 30
I. Deformation strengthening (or strain strengthening, work hardening) Definition After the material has yielded, with the increase in the degree of deformation, the strength and hardness of the material increases and the plasticity and toughness decrease is called deformation strengthening or work hardening. Mechanism As plastic deformation proceeds, the density of dislocations increases, so that the dislocations in the movement of the mutual cut intensifies, the result is that the fixed cut step, dislocation entanglement and other obstacles, so that the resistance to dislocation movement increases, causing deformation resistance to increase, to continue plastic deformation caused by difficulties, thus increasing the strength of metal Law: the degree of deformation increases, the strength of the material, hardness, plasticity, toughness, dislocation density increases, according to the formula picture, it can be seen that the strength and dislocation density ρ one-half of the square is proportional to the larger the dislocation of the Burns vector b, the more significant the strengthening effect. Methods Cold deformation, e.g. cold pressing, rolling, shot peening, etc. Example Cold drawing of steel wire increases its strength exponentially. Practical implications of deformation strengthening (pros and cons) (1) Advantages. ① Deformation strengthening is an effective method of strengthening metals. For some materials that cannot be strengthened by heat treatment, deformation strengthening can be used to improve the strength of the material and can increase the strength exponentially. ② is an important factor in the processing and forming of certain workpieces or semi-finished products, so that the metal is uniformly deformed, making it possible to shape workpieces or semi-finished products, such as cold-drawn steel wire, stam
Can caustic soda be produced using a three-effect counter-flow falling film evaporation process?
2022 / 06 / 29
At present, the evaporation process of domestic ion membrane caustic soda has ascending film evaporation process, double-effect descending film evaporation process and three-effect counter-current descending film evaporation process. As the rising film evaporation process is only one effect evaporation, steam utilization rate is low, heat energy is not reasonably used, the relative gas consumption is high, from the perspective of economic interests, the practicality of single effect rising film evaporation process is restricted. Double-effect counter-current falling film evaporation is more widely used, three-effect counter-current falling film evaporation process is less used at present, but three-effect counter-current has the advantages of low energy consumption, high steam utilization rate and large equipment capacity, etc., which is a more suitable evaporation technology. Three-effect countercurrent falling film evaporation process to produce 50% caustic soda in the application of enterprises. Advantages of three-effect counter-current. The three-effect counter-flow falling film evaporation system makes full use of the heat of the raw steam and the temperature of the 50% caustic soda solution produced by the first-effect evaporator, and twice makes use of the heat of the secondary steam produced by the system. The steam condensate from the first-effect evaporator is used to heat 36.5% and 41.8% of the alkali produced by the third-effect evaporator and the second-effect evaporator, making full use of the heat from the condensate. The high temperature 50% alkali produced by the first effect evaporator is used to preheat 36.5%,41.8% alkali produced by the third effect evaporator and the second effect evaporator, so that the temperature of 50% alkali can be lower than 90℃ after the preheating is completed, which makes full use of the heat energy of the
Chemical equipment pressure vessel damage causes
2022 / 06 / 28
Chemical equipment pressure vessel belongs to special equipment, the destruction of more factors, but also in line with the principle of specific analysis of specific problems, to take effective measures to actively prevent fatal chemical equipment pressure vessel damage. Chemical equipment pressure vessel operating environment is relatively complex, subject to corrosion and cracking and deformation and other causes of damage caused by quality problems, easy to cause fatal injury. Therefore, as opposed to the damage after the fact to deal with. More attention should be paid to prevention and control in advance to ensure the safe and stable operation of chemical equipment and pressure vessels, effectively extending the service life of the vessel. Due to the diverse forms and causes of damage to chemical equipment pressure vessels, the need to strengthen innovation in preventive measures and management tools to effectively play the role of chemical equipment pressure vessel management value. 1. Chemical equipment pressure vessel accident characteristics Pressure vessels belong to the pressure equipment, refers to the greater danger and involves the safety of life pressure class special equipment and safety accessories, including pressure piping and boilers, etc.. Pressure vessels are of various types and can be classified according to the way they are pressurised, dividing them into internal and external pressure vessels. If the classification method is chosen for the pressure size, it can be divided into high pressure, low pressure and medium pressure and ultra-high pressure vessels. If the classification method chosen is the operating temperature, then it includes low temperature, high temperature and ambient temperature vessels. If it is classified according to the production method, it includes different classification methods such as forging, welding and casting containers, which are classified differently, but any che
The causes and solutions for the generation of transverse cracks in welds
2022 / 06 / 27
What causes transverse cracking? How can it be solved? I believe I have some methods to minimise transverse cracking. And it is a very inexpensive method. Please see my analysis and explanation below. What causes "transverse cracking"? Many people have investigated and researched, but have not been able to find out the real cause and a complete solution. Based on the results of my research over the years in China and abroad, I have found that transverse cracking is mainly caused by two welding methods, submerged arc welding (SAW) and gas shielded flux cored welding (CO2+FCAW), especially CO2 gas shielded flux cored welding. I believe that the causes are not single factors, but at least two or more causes of safety accidents, such as someone jumping from a height because the ground is sloping unevenly, and as a result, they break their back. If the ground is flat it's fine to jump, and conversely the person doesn't jump down even if there is a knife on the ground it's fine! This means that it took at least two factors to cause a safety accident. I think it is most appropriate to use the word cancer as a metaphor for transverse cracks. When our ancestors created the word cancer, they told us that the word for cancer is a disease in itself, and that it is the result of three mouthfuls of toxins piling up to form cancer. Transverse cracks are rare in our regular welding, for example: porosity, slag, unfused, biting edges, etc. are common, as if we often have a bit of cold and flu and diarrhoea; occasionally there are longitudinal cracks and cold cracks on the edge of the weld toe, also like we accidentally break hands and feet in sports, which is also easy to understand and prevent, while cancer is rare, but when you see it it is already It is too late to see it, it is a death sentence and it is almost hopeless. Transverse cracks are also like cancer cells that spread and metastasise, and
2022 / 06 / 24
Recently, the State Administration of Market Supervision and Administration (State Standardization Administration) approved the release of GB 30871-2022 "Safety Code for Special Operations of Hazardous Chemical Enterprises" (hereinafter referred to as "Code"), which will be officially implemented from October 1, 2022. The Code is applicable to enterprises producing and operating (with storage) hazardous chemicals, chemical and pharmaceutical enterprises. The scope of operation is not only limited to the inspection and maintenance process, but extended to the whole process of production and operation of enterprises. The revision and implementation of the Code will strengthen the control of major risks in the whole process of special operations, implement the main responsibility of enterprises for safe production, and effectively prevent and curb the occurrence of major production safety accidents. Special operations have become the "hardest hit" areas for accidents The risk of special operations, such as fire work and restricted space work, in hazardous chemical enterprises is high, and accidents are prone to occur and frequent, easily leading to personal injuries or equipment damage and causing serious accident consequences. According to statistics, about more than 40% of chemical production safety accidents are related to special operations. Special operations have become the "hardest hit" area for production safety accidents in chemical enterprises in China, and are also a key and difficult area for safety supervision. The daily inspection of the implementation of the special operation management system and the analysis of the causes of accidents show that there are still some shortcomings in the identification and control of risks in the management of special operations, especially in the management of fire and restricted space operations, and that the safety measures stipulated in the current st
What matters need to be noted in the use of chemical storage tanks?
2022 / 06 / 22
1. Chemical storage tanks so that the storage of flammable gases, flammable liquids storage tanks, should be equipped with the necessary fire-fighting equipment, smoking in the tank is strictly prohibited, open fire lighting, heating, as well as its ignition sources into the tank area. Chemical storage tanks 2, the storage of flammable, explosive, toxic, corrosive and other media storage tanks, should strictly implement the relevant provisions of the management of dangerous goods. 3, storage tank inspection and repair before the electrical equipment related to the tank must be cut off the power supply, must handle the equipment handover procedures. 4, the internal medium of the storage tank exhausted, should be closed in and out of the valve or add a blind isolation and its connected pipeline and equipment, and has a clear sign of isolation. 5, for holding flammable, corrosive, toxic, or asphyxiating media storage tanks, must be replaced, neutralization, disinfection, cleaning and other processing, and in the processing of analysis and testing, the analysis results should meet the relevant norms, standards. With flammable media is strictly prohibited with air replacement. 6, tank operations must be for the tank work permit. For a longer period of time to interrupt the continuation of operations, should be re-applied for the tank work permit. 7, thirty minutes before entering the tank operation to take a sample analysis, its oxygen content in the 18-23% (volume ratio) between. 8, into the tank to clean up toxic, corrosive residues, to wear good personal protective equipment. 9, the need to build scaffolding and lifting devices, must be solid and reliable, in the operation is strictly prohibited to throw material tools inside and outside, in order to ensure safe operation. 10, lighting in the tank should be used at a voltage of no more than 24 pay explosion-proof lamps and lanterns. 11, whe
Enterprise safety production - Nine measures for chemical safety production in summer
2022 / 06 / 21
Summer is the period of dangerous chemicals accident prone and more frequent period, the following nine sources of danger must pay attention! "Safety responsibility is more important than a mountain", and enterprises are the main body responsible for safety management. Safety first is not an empty slogan, but a top priority in our daily work, requiring alarm bells to ring and a long grasp, and the participation and cooperation of all employees. Black Light Technology uses advanced information technology represented by the Internet of Things and big data to empower the chemical industry, strengthen weak risk prevention and control capabilities, crack the traditional management model of enterprises "can't see, can't manage, can't manage" and other painful and difficult problems of safety production, and become a way to promote the traditional chemical industry to achieve digitalisation, intelligence, automation The road to transformation and upgrading of production lines. There are various safety factors that threaten chemical production safety, such as people, materials, environment and management, but no matter which factors, they are all related to "people" in the end. I. Leak prevention In the summer production, once the original material leakage, not only cause environmental accidents and material loss, and most likely to cause poisoning, especially the leakage of materials directly on the operator's body, the danger is greater. To eliminate leaks, the following should be done. 1, cautious operation: material conveying valves and pipeline disassembly or connection, must pay attention to the valve switch to prevent material leakage in the outside or local hold pressure and lead to spraying material and lead to leakage accidents. 2, some glass sight glass, emptying valve (mouth), level meter and switch valve must have protective measures to prevent collision, open wron
Cleaning process for plate heat exchangers
2022 / 06 / 20
Cleaning process for plate heat exchangers 1. Isolating the equipment system and discharging the water inside the heat exchanger. 2. Use high-pressure water to clean the pipeline of silt, algae and other impurities and then close the system. 3. Install a ball valve (not less than 1 inch = 2.54 cm) between the isolation valve and the exchanger, with both inlet and return ports. 4. Connect the transfer pump and connecting conduit so that the cleaning agent is pumped in from the bottom of the heat exchanger and out from the top. 5. Start pumping the required cleaning agent into the heat exchanger (the ratio can be adjusted to suit). 6. Repeat the cycle of cleaning to the recommended cleaning time. As the cycle progresses and the deposits dissolve, the gas produced during the reaction will increase and the excess air should always be expelled through the bleeder valve. As the air is expelled, the space inside the heat exchanger will increase and appropriate water can be added. Do not inject a large amount of water at the beginning, as this may cause an overflow. 7. The effectiveness of the cleaning agent should be checked regularly during the cycle and can be determined using PH test paper. If the solution remains at a PH value of 2-3 then the cleaner is still effective. If the pH value of the detergent reaches 5-6, then a suitable amount of detergent needs to be added. If the final solution remains at a pH value of 2-3 for 30 minutes without any significant change, the cleaning effect has been achieved. Note: the cleaning agent can be recycled and reused, discharge will cause waste. 8. 8. After reaching the cleaning time, recycle the cleaning solution. And repeatedly rinse the exchanger with water until it is rinsed clean to neutral, and use PH test paper to determine the PH value of 6~7. 9. After completing the cleaning, you can both s
How falling film evaporators prevent fouling and maintain stable operation of equipment
2022 / 06 / 15
How falling film evaporators prevent fouling and maintain stable operation of equipment Falling film evaporation has the advantages of high heat transfer coefficient and small heat transfer temperature difference. Compared with other forms of evaporators, falling film evaporator heat transfer coefficient is higher, heat transfer effect is also better, and the one-time investment cost is less, and is now widely used in food, medicine, chemical industry, energy and other fields. After years of development, as well as the progress of science and technology, the falling film evaporator continues to meet the needs of the pharmaceutical industry and other industries, and the performance is constantly being improved. At present, the falling film evaporator model on the market is various, many manufacturers can provide customized services according to the needs of users, to meet the actual needs of users. It is worth mentioning that the evaporation tube of the falling film evaporator is generally easy to appear fouling and other problems, either light or heavy, which directly reduces the heat exchange efficiency of the falling film evaporator, and even makes it difficult for the equipment to operate normally, causing greater economic losses. Therefore, how to prevent scale and scale removal, keep the equipment stable operation, is the bottleneck that industry enterprises need to crack. It is understood that the current measures to prevent evaporator equipment scaling mainly include crystal seed method, add scale inhibitor method, add acid method, purification pretreatment method, control solid-liquid ratio method, etc., of which pretreatment method is one of the common methods to prevent scaling, its hardness and alkalinity removal process, can remove calcium, magnesium ions and sulfate, carbonate ions in concentrated salt wastewater, to prevent calcium carbonate and calcium sulfate scaling. By actively taking anti-scaling measur
Reactor safety hazards cannot be ignored
2022 / 06 / 14
Reactor safety hazards cannot be ignored Reactors are intermittent reactors with stirring devices. Depending on the pressure required for the process, chemical reactions can be carried out under open, closed atmospheric, pressurised or negative pressure conditions. The safety of the reactor and the production site environment are particularly important in the production and synthesis of chemical products. In recent years, reactor explosions caused by negligence have given the chemical industry a wake-up call. Seemingly safe materials can also cause safety accidents if they are not placed in the right quality. Some of the safety hazards of reactors are as follows. Feeding errors If the cooling cannot be synchronised, the heat will build up and cause a local thermal decomposition of the material, resulting in a rapid reaction of the material and a large amount of hazardous gas explosion. Pipe leakage When feeding, for atmospheric reaction, if the emptying pipe is not opened, when pumping liquid material into the kettle, positive pressure will be formed in the kettle, which will cause the material pipe connection to break apart and the material to leak out causing personal injury and burn accident. When unloading, if the material in the kettle is not cooled to the required temperature (generally below 50°C), the higher temperature material will easily deteriorate and cause splashes and burns to the operator. Heating up too fast The material in the kettle is heated too fast, the cooling rate is low and the condensation effect is poor, all of which may cause the material to boil, forming a mixture of vapour and liquid phase, generating pressure and unloading the material from weak links such as the vent pipe, vapour phase pipe and the pressure discharge system such as the safety valve and rupture disc. If the material cannot be unloaded quickly
The installation of tower packing
2022 / 06 / 10
The installation of tower packing Packing development, manufacturing is generally completed by the packing manufacturer, packing performance data is also provided by the manufacturing plant, its quality should also be guaranteed by the manufacturing plant, here without further ado. 1.Processing before packing installation (1) filler oil removal There is a thin oil layer on the surface of the new filler, which may be formed by the lubrication oil used in the processing of metal filler; it may also be to avoid corrosion of carbon steel filler in the process of transportation and storage and the addition of anti-rust oil. The presence of this layer of oil is absolutely unacceptable for some systems, for example in air separation systems, where the oil layer washes off and coexists with liquid oxygen and can cause an explosion. For aqueous systems, the oil can prevent the formation of a liquid film, and for some alkaline systems it can also cause foaming of the solution. To facilitate the removal of the oil layer, a water-soluble lubricant is preferable for the filler process. Carbon steel filler should be stored in a dry and closed place, should not be removed in advance to prevent rusting. (2) Ceramic filler debris removal New ceramic packing and refilling of ceramic packing should be sieved out of which the debris, sometimes need to be removed by hand one by one, bulk ceramic packing in the transportation process inevitably broken, large pieces of broken packing can still be used, its flux has decreased, the pressure drop has increased, but the separation efficiency will not decline. (3) tower support ring removal Plate tower to fill tower, the original tower plate, liquid drop tube and support ring removal. Horizontal bearing circle should be cut as clean as possible. Horizontal bearing circle retained, in the tower wi
Operating procedures for tower cleaning
2022 / 06 / 09
A distillation column is a contact device for the distillation of tower vapours, this device is also known as a distillation column. Concerning the types of distillation towers, today's presentation is about the cleaning of distillation towers. To ensure that the distillation tower is washed clean, to avoid cross-contamination and to ensure the quality of the product, the following protocols should be followed. Solvent reflux: according to the needs of the actual situation, at the end of the distillation operation, the distillation kettle can be inhaled to the appropriate amount of solvent, rising temperature and atmospheric pressure reflux, will be adsorbed in the tower material as far as possible all brought out! The principle of solvent selection is to use the recovery solvent of the process! Clear water overflow: directly from the distillation kettle's feed valve to the kettle to add the appropriate amount of water or through the tower top vacuum will be sucked into the kettle, with water preliminary washing; according to the actual situation to decide whether the washing water will be put away! Alkaline water washing: vacuum to the kettle to suck in about 1% of alkali, then raise the temperature to 100-110°C, full reflux for 60min and collect the fraction, wash the pipes and equipment with alkaline water. Hot water overflow: add an appropriate amount of water to the distillation kettle, raise the temperature and reflux for 30min, then collect the whole to achieve the purpose of washing away the alkaline water from the equipment and pipes. Vacuum drying: Vacuum drying is used to dry the distillation tower, the operator can observe through the sight glass to confirm that there is no water accumulation in the distillation kettle, the temperature of the gas phase in the kettle reaches 80~90℃, and the drying operation can be considered over af
Maintenance and overhaul management of chemical plant equipment
2022 / 06 / 08
Maintenance and overhaul management of chemical plant equipment The implementation of the production of the link, production equipment is indispensable. The continuity of chemical enterprises is very large, also has high temperature, high pressure and other characteristics. If there are certain problems with the equipment in the chemical workshop, it will lead to many consequences, which will bring adverse effects to the production, and in serious cases will cause the problem of casualties. Therefore, for chemical enterprises, need to do a good job of maintenance and overhaul of various equipment, so as to lead the development of chemical enterprises. A, the importance of maintenance of chemical plant equipment overhaul (a) can make the chemical plant equipment to extend the service life Equipment in the chemical plant plays an important role, the number of times the staff work on maintenance and overhaul of equipment is extremely frequent, the danger is also relatively large, the technical performance is very high, the whole work process is tedious, the repair work has real-time. The staff need not only professional skills, but also qualifications in the maintenance of chemical plant equipment. Enterprises need to hire professional personnel to maintain and overhaul the equipment, so that not only can the wear and tear of chemical workshop equipment effectively reduce, but also make the application of chemical workshop equipment to improve the life. (2) Provide corresponding guarantee for the operation and management of chemical enterprises The equipment in the chemical plant must be well maintained and inspected, which is very important for the operation of chemical enterprises. The link between the production equipment and the inlet pipe is effective, with materials entering at one end and exiting at the other. The process of transferring the original material places great
2022 / 06 / 07
Chemical equipment is usually divided into which two categories, an inventory of common chemical equipment Chemical production in order to process raw materials into a certain specification of finished products, often need to go through a series of chemical processes such as raw material pretreatment, chemical reactions and separation and refinement of reaction products, the machinery used to achieve these processes is called chemical equipment. Chemical equipment is generally divided into two categories: static equipment and dynamic equipment. Static equipment Static equipment refers to equipment that is installed in a static state and does not require power transmission during production operations. Static equipment is widely used in the production of mass transfer, heat transfer, media heating, chemical reactions and other processes and storage of materials. Such as various vessels, towers, reactors, heat exchangers, etc. The investment in the static equipment part accounts for about 50%-60% of the total investment in the plant. 1.1 Distillation tower Distillation is a chemical unit operation that uses the difference in volatility of the components in a liquid mixture to separate them, according to the distillation method can be divided into simple distillation, balanced distillation, distillation and special distillation and other ways. If partial gasification or partial condensation is carried out several times, a purer lighter or heavier component can eventually be obtained, which is called distillation. The distillation tower is a tower-type vapour-liquid contact device for distillation, there are two main types of plate tower and packed tower. Plate tower by the cylindrical tower body and according to a certain spacing in the tower of a number of horizontal installed in
2022 / 06 / 06
Safety | A brief overview of fire safety issues for chemical equipment in hazardous chemical enterprises Abstract. With the development of our economy, chemical enterprises have become an important part of our enterprises, and the safety of chemical equipment in chemical enterprises will be paid more and more attention to. This paper analyzes the causes of fire in chemical equipment, and then makes suggestions on how to fire safety from various aspects. Chemical products are flammable, explosive and corrosive. The occurrence of fire or leakage is extremely dangerous. Therefore, extra attention should be paid to the fire safety of chemical equipment in chemical enterprises. Chemical enterprises have different sizes of chemical equipment dangers, and only an in-depth understanding of the reasons for their dangers can ensure that nothing can go wrong! A, China's chemical enterprises equipment prone to fire causes 1. Chemical equipment itself Chemical equipment needs to work for a long time in high temperature, high pressure, high corrosive environment, chemical production equipment in the design of unreasonable, processing defects in the long production process generated by fatigue catalyst, more likely to produce breakage, the risk of fire and explosion. Chemical substances, if not properly stored and handled, are also prone to chemical reactions, leading to the breakage of chemical equipment, which can lead to a series of explosions and fires and other serious situations. 2. Unqualified operation of chemical equipment The complexity and dangerous nature of chemical equipment means that staff must have the appropriate knowledge and skills to ensure that fires and equipment safety problems are reduced when operating the equipment. However, the current situation of chemical enterprises in China is characterised by the low cultural qual
Safety | What is the safety management of mechanical chemical equipment?
2022 / 06 / 02
Safety | What is the safety management of mechanical chemical equipment? Chemical machinery and equipment is the general term for the machines and equipment used in chemical industry production. In order to process raw materials into finished products of a certain specification, chemical production often requires a series of chemical processes such as raw material pretreatment, chemical reactions and the separation and refinement of reaction products, etc. The machinery used to achieve these processes is often classified as chemical machinery. The safe operation of machinery and equipment is of great importance to the production of the entire chemical industry. The chemical industry has its own industry characteristics, and in production, the requirements for machinery and equipment are higher. The responsibility and task of safety management of chemical machinery and equipment is of great significance. Adhere to the "prevention-oriented, maintenance as a supplement" management principles, early detection, timely adoption of effective preventive measures to ensure the safety of machinery and equipment, normal, stable operation. Combined with the author's work by testing the safety management of mechanical chemical equipment for a simple analysis. A, in stages of fault analysis 1.1 Equipment normal operation before Equipment by the installation and commissioning and through the technical appraisal, acceptance and operation for a period of time, due to the nature of the equipment itself and the need for break-in, there will be regular failures, the main reasons are: defects in the details of the design, parts in the process of casting there are processing defects, technical personnel contact the new equipment improper operation, and equipment tacit understanding is still to be cultivated. At the same time, the problem of poorly installed components in the installation o
The choice of stainless steel reactor sealing form
2022 / 06 / 01
The choice of stainless steel reactor sealing form Stainless steel reactor with its excellent corrosion resistance and low price, to win more and more customers love and trust; Therefore, the choice of the seal at the combination of stirring and reactor is particularly important for the sealing effect, use of safety, cost savings, etc., now the following recommendations on how to choose the right form of seal: 1. First of all, we must clarify the basis of seal selection: *** is the working pressure in the kettle, the second is the nature of the working material. Another is the working temperature of the equipment. 2. Secondly, we should clarify the type of seal used in stainless steel reactors: there are two types of seals used in reactors, i.e., the usual shaft seal, *** is the packing seal, the second is the mechanical seal, mechanical seal is divided into single seal (i.e., single-end mechanical seal) and double seal (i.e., double-end mechanical seal), a full set of single seal also includes the water jacket, double seal is more complex, in addition to the water jacket (must have circulating cooling water), but also In addition to the water jacket (must have circulating cooling water), it also includes the supporting bracket, balance tank, etc. 3. 3. how to choose the right seal: at room temperature and pressure, the material is not volatile and not flammable and explosive conditions of use, to choose the packing seal; in the pressure is less than 4 kg, the material is volatile and flammable and explosive general conditions of use, to choose a single machine seal; in the working pressure of more than 4 kg (but less than 10 kg), the material is volatile and flammable and explosive very strong conditions of use, then 4. advantages and disadvantages of various seals 4. the advantages and disadvantages of various seals: packing seal price *** cheap, but only suitable for *** common use conditions and materials; single machine seal price is moderate, ca
Waste classification and disposal industry ushers in a golden period of development
2022 / 05 / 30
In recent years, China's urban domestic waste treatment capacity has been significantly improved. The "14th Five-Year Plan" for the development of urban domestic waste classification and treatment facilities proposes that by the end of 2025, the national urban domestic waste incineration capacity will reach about 800,000 tons / day, and the urban domestic waste incineration capacity will account for about 65%. Capital Securities pointed out that investment in environmental infrastructure will become an important area of stable growth. Sewage treatment, domestic garbage treatment, solid and hazardous waste treatment and resource recovery field of environmental protection companies will usher in more business opportunities. At the same time, the improvement of the price charging system in the field of environmental protection is expected to further improve the profitability of environmental protection enterprises. Industry insiders pointed out that with the accelerated implementation of the waste classification system, the waste classification industry ushered in huge development opportunities, especially in the field of intelligent waste classification, cutting-edge technology (such as AI, Internet of Things, machine vision, etc.) enabled waste classification solutions have become a windfall, favored by all parties capital
Stainless steel pickling passivation process control
2022 / 04 / 26
1. Pretreatment of pickling passivation Before pickling and passivation of stainless steel workpiece, if there is surface dirt, etc., it should be cleaned by mechanical cleaning, and then degreasing and degreasing. If the pickling solution and passivation solution cannot remove grease, the presence of grease on the surface will affect the quality of pickling passivation. Therefore, degreasing and degreasing cannot be omitted, and lye, emulsifier, organic solvent and steam can be used. 2. Control of Cl- in pickling solution and rinse water Some stainless steel pickling solutions or pickling pastes use corrosive media containing chloride ions such as hydrochloric acid, perchloric acid, ferric chloride and sodium chloride as the main agent or auxiliary agent to remove the surface oxide layer, and trichloroethylene is used for grease removal. Chlorinated organic solvents such as these are not suitable for preventing stress corrosion cracking. In addition, industrial water can be used for preliminary flushing water, but strict control of halide content is required for final cleaning water. Deionized water is usually used. If the petrochemical austenitic stainless steel pressure vessel is used for hydraulic test, the C1- content should not exceed 25mg/L. If this requirement cannot be met, sodium nitrate can be added to the water to make it meet the requirements. If the C1- content exceeds the standard, it will be Destruction of the passive film of stainless steel is the root cause of pitting corrosion, crevice corrosion, stress corrosion cracking, etc. 3. Process control in pickling passivation operation Nitric acid solution alone is effective for removing free iron and other metal contaminants, but it is ineffective for removing iron oxide scale, thick corrosion products, tempering films, etc. HNO3+HF solution should generally be used. For convenience
Selection, replacement and cleaning of cooling tower packing
2022 / 04 / 25
1. What is the cooling tower fill? The cooling tower packing is the core component of the cooling tower. The packing increases the heat dissipation in the cooling tower, prolongs the residence time of the cooling water, and increases the heat exchange area, which plays an important role in the cooling effect of the circulating water. 2. Filler selection Some studies have shown that the heat dissipation capacity of water-spraying fillers can reach more than 70% of that of conventional cooling towers, so the choice of fillers is very important. There are many factors affecting the selection of fillers. It is necessary to comprehensively consider many factors such as cooling tower form, thermal characteristics, cooling tasks, circulating cooling water quality, ventilation conditions, thermal resistance characteristics of fillers, support methods of fillers, and cost of fillers. 1) Select according to the cooling water quality When there is a possibility of leakage of raw material oil in the water or fibers in the water or the concentration of suspended solids in the cooling water is greater than 100mg/L, the drip packing should be selected; when there is no leakage and the water quality is well controlled or the concentration of suspended solids in the cooling water is less than 50mg/L, it should be selected. Film type packing; when the site is limited and the water may leak raw material oil pollutants or the concentration of suspended solids in the cooling water is between 50mg/L and 100mg/L, the drip film mixed packing type should be used. 2)According to the cooling tower type selection The packing of the counter-flow cooling tower is usually arranged above the air inlet of the tower. The use of film type or drip film type can reduce the total height of the tower and reduce the cost. Generally, it is preferred for engineering design; while the height of the packing of the cross-flow cooling
Anti-corrosion measures for metal valves
2022 / 04 / 23
Metal valves can be said to be the key component structures that are prone to corrosion and failure in engineering equipment. Usually, the sealing surface, valve stem, diaphragm, small spring and other valve parts of metal valves are generally used, and the valve body and valve cover are suitable for two or three. Materials, valves used for high-pressure, highly toxic, flammable, explosive, and radioactive media, use less corrosive materials. Under complex working conditions such as atmosphere or solution, metal valves not only have uniform corrosion on the metal surface at all times, but also pitting corrosion, crevice corrosion, intergranular corrosion, delamination corrosion, stress corrosion, and fatigue corrosion at local locations of the metal. , selective corrosion, wear corrosion, cavitation corrosion, friction corrosion, hydrogen corrosion and other local corrosion. 1 Choose corrosion-resistant materials according to the corrosive medium In the actual production, the corrosion of the medium is very complicated. Even if the valve material used in the medium is different in the concentration, temperature and pressure of the medium, the corrosion of the medium on the material is also different. When the temperature of the medium increases by 10°C, the corrosion rate increases by about 1 to 3 times. The medium concentration has a great influence on the corrosion of valve materials. For example, when lead is in sulfuric acid with a small concentration, the corrosion is very small. When the concentration exceeds 96%, the corrosion rises sharply. Contrary to carbon steel, the corrosion is severe when the concentration of sulfuric acid is about 50%, and when the concentration increases to more than 6%, the corrosion decreases sharply. For example, aluminum is very corrosive in concentrated nitric acid with a concentration of more than 80%, but it is seriously corroded in medium and low concentrations of nitric acid. Although stainl
Preventive Measures for Defects of Stainless Steel Pressure Vessel Heads
2022 / 04 / 22
In the process of pressing the stainless steel pressure vessel head, the force is complex, and various defects are prone to occur. According to the reasons for the formation of different defects, taking corresponding preventive measures is an important link to ensure the quality of the head. 1. Preventive measures for crack defects Different measures are taken according to different situations of stainless steel pressure vessel head cracks. The cracks in the straight edge section are mainly controlled by the speed of the hemming, the pressure, and the punching speed; the cutting process is strictly controlled, and the edges of the blank are polished and smoothed to prevent Port cracks; welds and heat-affected zone cracks, it is necessary to strictly control the welding process parameters, slow down the cooling rate, appropriately increase the shape factor of the weld, and use low-current multi-layer multi-pass welding as much as possible to avoid cracks in the center of the weld. Prevent undercut, control welding height, and conduct reasonable heat treatment on the weld area, etc. 2. Preventive measures for bulging defects Measures to prevent bulging include: adopting a secondary stretching process to reduce residual stress; adopting a tapered edge blanking ring; improving the heating quality of the blank to make the blank heated evenly. Measures taken to prevent overburning include: using electric furnaces, gas furnaces and oil furnaces with a uniform temperature field, placing the furnace head in the center as much as possible, uniformly distributing the thermocouples of the electric furnace and the nozzles of the oil and gas furnace, and checking the temperature field in the furnace. Check regularly. To prevent the occurrence of wrinkles, the following measures should be taken: adding pressure rings, especially the pressure vessel factories with self-made heads, lack of professional equipment; control the gap between the upper and lower molds; contr
Classification and composition of atmospheric storage tanks
2022 / 04 / 21
Atmospheric pressure storage tanks are widely used in oil refining and chemical enterprises to store crude oil, refined oil, intermediate raw materials and chemical products and other media. Atmospheric pressure storage tank introduction 1 Classification of atmospheric storage tanks According to the geometry, the storage tanks can be divided into vertical cylindrical storage tanks, horizontal cylindrical storage tanks and spherical storage tanks; according to the installation location, the storage tanks can be divided into above-ground storage tanks, semi-ground storage tanks and underground storage tanks Storage tank: According to the material of the tank, storage tanks can be divided into metal storage tanks and non-metallic storage tanks; according to the design pressure, storage tanks can be divided into atmospheric storage tanks, low pressure storage tanks and pressure storage tanks. Storage tanks with design pressure less than or equal to 6.9kPa (gauge pressure at the top of the tank) are atmospheric storage tanks; storage tanks with design pressure greater than 6.9kPa and less than 0.1MPa (gauge pressure at the top of the tank) are low-pressure storage tanks; design pressure is greater than or equal to 0.1 The storage tank with MPa (tank top gauge pressure) is a pressure storage tank. The atmospheric storage tank in this paper refers to a vertical cylindrical above-ground steel welded storage tank. According to the structure of the tank roof, atmospheric storage tanks can be divided into fixed roof tanks, internal floating roof tanks and external floating roof tanks. Fixed-roof tanks are further divided into self-supporting vault tanks and self-supporting cone-roof tanks. 2 Atmospheric pre
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