The storage and reaction of corrosive liquids is more than just using polyethylene tanks!
release date：2019-09-23 10:12:59 Views：24099
What is the difference between a tube condenser and a spiral plate heat exchanger? What is the heat exchange effect?
Column and tube condensers are divided into three types: carbon steel tube and tube condensers, stainless steel tube and tube condensers, and carbon steel and stainless steel mixed tube and tube condensers. According to the form, it is divided into tubular condenser, spiral plate heat exchanger, floating head heat exchanger, U-tube heat exchanger. According to the structure, it is divided into single-tube-pass condenser, double-tube-pass condenser and multi-tube-pass condenser. The heat transfer area is 0.5-500 square meters. Can be customized according to user needs. It is suitable for heat exchange equipment for various purposes in the chemical, light industry, metallurgy, pharmaceutical, food, chemical fiber and other industries. It is especially suitable for condensers to replace the original stainless steel condensers, enamel condensers, graphite condensers, etc. Glass condenser. The effect is remarkable after use.
Tube condenser features:
1. Corrosion resistance: Polypropylene has excellent chemical resistance. For inorganic compounds, regardless of acid, alkali, salt solution, except for strong oxidizing materials, it has no destructive effect on almost all solvents up to 100°C. It is insoluble at room temperature, and can be used on media such as alkane, hydroxyl, alcohol, phenol, aldehyde, ketone, etc.
2. Temperature resistance: The melting point of polypropylene plastic is 164-174℃, so the general use temperature can reach 110-125℃.
3. Non-toxic: no scaling, no pollution to the medium, and it can also be used in the food industry.
4. Light weight: It is extremely convenient for equipment installation and maintenance.
Tube heat exchanger
Tube heat exchanger is a kind of heat exchanger which is widely used in chemical and alcohol production. It is mainly composed of a shell, a tube sheet, a heat exchange tube, a head, a baffle, etc. The required materials can be made of ordinary carbon steel tube and tube heat exchangers, red copper, or stainless steel tube and tube heat exchangers. When performing heat exchange, a fluid enters from the connecting pipe of the head, flows through the pipe, and flows out from the outlet pipe at the other end of the head, which is called the tube pass; the other fluid enters from the connecting pipe of the shell, from The other pipe on the shell flows out, which is called the shell-side tube heat exchanger.
Fixed tube plate heat exchanger
The structure of the tube heat exchanger is relatively simple, compact, and inexpensive, but the outside of the tube cannot be mechanically cleaned. The tube bundle of the heat exchanger is connected to the tube plate, and the tube plate is respectively welded to the two ends of the shell, and a top cover is connected to the tube plate. The top cover and the shell are equipped with fluid inlet and outlet pipes. A series of baffles perpendicular to the tube bundle are usually installed outside the tube. At the same time, the connection between the tube and the tube sheet and the outer shell is rigid, and the inner and outer tubes of the tube are fluids of two different temperatures. Therefore, when the temperature difference between the tube wall and the shell wall is large, due to the difference in thermal expansion between the two, a large temperature difference stress is generated, so that the tube twists or loosens the tube from the tube sheet, or even destroys the heat exchanger.
In order to overcome the temperature difference stress, a temperature difference compensation device must be provided. Generally, when the temperature difference between the tube wall and the shell wall is more than 50℃, for safety reasons, the heat exchanger should have a temperature difference compensation device. However, the compensation device (expansion joint) can only be used when the temperature difference between the shell wall and the tube wall is lower than 60-70°C and the fluid pressure in the shell side is not high. Generally, when the pressure of the shell side exceeds 0.6Mpa, because the compensation ring is too thick, it is difficult to stretch and lose the function of temperature difference compensation, other structures should be considered.
floating head heat exchanger
One tube sheet of the floating head heat exchanger is connected to the shell with a flange, and the other tube sheet is not connected to the shell, so that the tube can be freely expanded and contracted when heated or cooled, but a top cover is connected to this tube sheet, which is called It is a "floating head", so this type of heat exchanger is called a floating head heat exchanger. Its advantages are: the tube bundle can be pulled out for cleaning; the expansion of the tube bundle is not restricted by the shell, so when the temperature difference between the two heat exchanger media is large, the thermal expansion of the tube bundle and the shell will not cause temperature difference stress . The disadvantage is that the structure is complex and the cost is high.
U-tube heat exchanger
U-shaped tube heat exchanger, each tube is bent into a U shape, and both ends are fixed on the same tube plate, and each tube can be freely expanded and contracted, thereby solving the problem of thermal compensation. The tube pass is at least two passes, the tube bundle can be drawn out for cleaning, and the tube can expand freely. The disadvantage is that the inner wall of the tube is difficult to clean, the tube is difficult to replace, and there are few tubes arranged on the tube sheet. The advantages are simple structure, light weight, and suitable for high temperature and high pressure conditions.
Spiral plate heat exchanger is a kind of high-efficiency heat exchanger equipment, suitable for steam-vapor, vapor-liquid, liquid-liquid, heat transfer to liquid. It is suitable for industries such as chemistry, petroleum, solvents, medicine, food, light industry, textiles, metallurgy, steel rolling, and coking. According to the structure, it can be divided into non-detachable (type Ⅰ) spiral plate heat exchanger and detachable (type Ⅱ, Ⅲ type) spiral plate heat exchanger.
Spiral plate heat exchanger structure and performance
1. This equipment is made of two rolls to form two uniform spiral channels. The two heat transfer media can flow in full countercurrent flow, which greatly enhances the heat exchange effect. Even with two small temperature difference media, it can reach the ideal The heat transfer effect.
2. The connecting pipe on the shell adopts a tangential structure, and the local resistance is small. Because the curvature of the spiral channel is uniform, the liquid flow in the equipment does not have a big turn, and the total resistance is small. Therefore, the design flow rate can be increased to make it more High heat transfer capacity.
3. The end surface of the spiral channel of the I-type non-detachable spiral plate heat exchanger is sealed by welding, so it has a higher sealing performance.
4. The structure principle of the II type detachable spiral plate heat exchanger is basically the same as that of the non-detachable heat exchanger, but one of the channels can be detached for cleaning, which is especially suitable for heat exchange with viscous and precipitated liquids.
5. The structural principle of the III-type detachable spiral plate heat exchanger is basically the same as that of the non-detachable heat exchanger, but its two channels can be detached and cleaned, which has a wide range of applications.
6. When a single device cannot meet the requirements for use, multiple devices can be used in combination, but the combination must meet the following requirements: parallel combination, series combination, and the same distance between devices and channels. Mixed combination: One channel is connected in parallel and one channel is connected in series.
The basic parameters of spiral plate heat exchanger:
1. The nominal pressure PN of the spiral plate heat exchanger is specified as 0.6, 1, 1.6, 2.5Mpa (that is, the original 6, 10, 16, 25kg/cm) (refers to the super large working pressure of a single channel). The test pressure is the working pressure 1.25 times.
2. The material of the contact part of the spiral plate heat exchanger with the medium, carbon steel is Q235A, Q235B, and the stainless steel acid port is SUS321, SUS304, 3161. Other materials can be selected according to user requirements.
3. Allowable working temperature: t=0-+350℃ for carbon steel. The t of stainless steel acid steel is -40-500℃. The range of heating and pressure reduction is in accordance with the relevant regulations of the pressure vessel. When selecting this equipment, proper process calculations should be used to make the fluid in the equipment channel reach a turbulent state. (General liquid flow rate 1m/Sec gas flow rate 10m/Sec). The equipment can be placed horizontally or vertically, but it can only be placed vertically when used for vapor condensation; for caustic soda industry, overall heat treatment must be performed to eliminate stress.
4. When selecting equipment, appropriate process calculations should be used to make the liquid in the equipment channel reach a turbulent state (generally liquid velocity≥0.5m/s; gas≥10m/s).
5. The equipment can be placed horizontally or vertically, but it can only be placed vertically when used for steam condensation.
6. When used in the caustic soda industry, an overall heat treatment must be carried out to eliminate stress.
7. When the difference in flow values on both sides of the channel is large, unequal-spaced channels can be used to optimize the process design.
Spiral plate heat exchanger anti-clogging principle
Spiral plate heat exchanger is not easy to be blocked compared with general tubular heat exchanger, especially suspended particles such as sand, small shells, etc., are not easy to deposit in the spiral channel, which is mainly reflected in:
1. Because it is a single-channel impurity deposition in the channel once it forms a circulating flow, it will increase to wash it away;
2. Because there is no dead angle in the spiral channel, impurities are easily washed out.
Spiral Plate Heat Exchanger Features
1. High heat transfer efficiency (good performance) It is generally believed that the heat transfer efficiency of spiral plate heat exchangers is 1-3 times that of tubular heat exchangers. There is no flow dead zone in the uniform cross-section single channel. The disturbance of the fixed distance column and the spiral channel reduces the critical Reynolds number of the fluid. The heat transfer coefficient of the spiral plate heat exchanger can reach 3000W/(㎡. K).
2. The spiral plate heat exchanger for effective recovery of low temperature heat energy is made of two rolls to form two uniform spiral channels. The two heat transfer media can flow in full countercurrent flow, which greatly enhances the heat exchange effect, even if two small The temperature difference medium can also achieve the ideal heat exchange effect, carry out waste heat recovery, and make full use of low-temperature heat energy.
3. Strong operational reliability. The end surface of the spiral channel of the non-detachable spiral plate heat exchanger is welded and sealed, so it has a high tightness and ensures that the two working media are not mixed.
4. Low resistance The connecting pipe on the shell adopts a tangential structure, and the local resistance is small. Because the curvature of the spiral channel is uniform, the liquid flows in the equipment without major turning, and the total resistance is small, so the design flow rate can be increased to make it Possess high heat transfer capacity. Relatively low pressure loss, processing large-volume steam or gas; self-cleaning ability, because the medium flows in a spiral, dirt is not easy to deposit; easy to clean, can be washed with steam or lye, simple and easy, suitable for installing cleaning devices; The medium goes through a single channel, allowing the flow rate to be higher than other heat exchangers. 5. Multiple units can be used in combination. When a single device cannot meet the requirements for use, multiple units can be used in combination, but the following requirements must be met when combined: parallel combination, series combination, and the same distance between equipment and channels. Mixed combination: One channel is connected in parallel and one channel is connected in series.
Spiral tube plate heat exchanger installation instructions
1. For equipment installation, engineering and technical personnel who are familiar with the process of the system should be asked to guide, and determine the installation process plan in accordance with this manual, product quality certificate and system process characteristics. During installation, it should be considered that the direction of the pipeline should be used to absorb thermal expansion as much as possible, and the installation should be level and aligned, and no additional stress should be generated to avoid adverse effects on the equipment. The pipeline connection should make the two processes completely countercurrent to improve the heat transfer effect.
2. The pipeline system should be cleaned before installation, and no mud, sand, debris, etc. should be left in it; check whether the heat exchanger is damaged during transportation and whether there is any large debris falling into the pipe opening.
3. After the equipment is installed, the equipment and system should undergo a hydraulic test.
4. After the water pressure test is completed, the equipment should be insulated.
5. The circulation must be softened or treated with medicine. (According to the low-pressure boiler water quality standard GB1576-96), due to improper water treatment, the scale can be removed by chemical cleaning.
Common faults and treatment methods of spiral tube plate heat exchanger
During the production process, because the tube sheet of the spiral tube sheet heat exchanger is corroded by moisture, cavitation and trace chemical media, leakage often occurs at the weld of the tube sheet, resulting in the mixing of water and chemical materials, and the temperature of the production process is difficult. Control, resulting in the production of other products, seriously affecting product quality, and reducing product grades. After the condenser tube sheet weld leaks, the company usually uses traditional repair welding methods to repair it. Internal stress is prone to occur in the tube sheet and is difficult to eliminate, resulting in leakage of other heat exchangers. The company checks the repair of the equipment by suppressing it. , Repeated repair welding and experiments, 2 to 4 people need a few days to complete the repair. After a few months of use, the tube sheet welds corroded again, which brought waste of manpower, material and financial resources to the enterprise and increased production costs. Through the corrosion resistance and erosion resistance of the Fuschlan polymer composite material, and the protection of the new heat exchanger in advance, this not only effectively controls the welding seam and blisters of the new heat exchanger, but also avoids the chemical substances after use. Corrosion of the metal surface and welding points of the heat exchanger, in the future regular maintenance, you can also apply the Fuschlan polymer composite material to protect the exposed metal; even if there is leakage after use, it can be repaired in time through the Fuschlan technology. Avoid long-term surfacing welding and maintenance affecting production. It is precisely because of this refined management that the probability of heat exchanger leakage problems is greatly reduced, which not only reduces the purchase cost of heat exchanger equipment, but also ensures product quality and production time, and improves product competitiveness.
Spiral plate heat exchanger internal leakage treatment method:
Spiral plate heat exchanger is composed of two closed and independent spiral passages. If cross leakage occurs in the passage, it is difficult to determine the cross leakage point. In order to accurately detect the leakage point, the method of drilling is used. When drilling, the drilling position should be set on the same spiral channel at one end of the heat exchanger, and it should be arranged in a crisscross shape. The passage is unobstructed.
Irrigation to suppress leak detection method:
In a channel that has never been drilled, use a pressure water pump to fill the heat exchanger with water and form a certain pressure. Channel), and drip water from the layer that is super close to the leakage point. If there is internal leakage, cut a section of the undrilled side head of the same layer of the heat exchanger as an observation hole, and the specific leakage point can be accurately determined from the observation hole.
Repair of internal leakage:
1. Digging holes: After determining the position of the internal leakage point, start cutting holes from the place where the super outer layer of the heat exchanger corresponds to the leakage point. The sequence is from the outside to the inside, until the layer with the internal leakage point is cut. until. The cut hole should be elliptical, and the size of the outer layer is larger, and the size is gradually smaller inward. Generally, the size of the hole on each layer is different by 40mm. If the position of the leakage point is deeper, the hole cut in the outer layer should be larger .
2. Slag removal: After the holes are cut, the oxide slag left on each layer of the board should be carefully cleaned, which is whether the repair board and each layer of spiral plate can be welded tightly when the butt-welding patch board The key is to clean the oxide slag with the chisel and the small hand grinding wheel used to trim the mold. Pay attention to the cleaned slag as far as possible and prevent it from falling into the heat exchanger.
3. Equipped with replenishing board: In order to ensure the quality of repair, the sheets cut from each layer of the heat exchanger are no longer used, and the replenishing board is re-equipped. The additional replenishing board should be used with the heat exchanger spiral plate. With the same material and plate thickness, its periphery should be 15mm-20mm larger than the holes cut on each layer of the heat exchanger, and it is also elliptical, and made into an arc that is consistent with the curvature of each layer of the heat exchanger. .
4. Welding internal leakage point and replenishment board:
1) When welding internal leaks, carefully check whether the leaks are cracks or blisters. If necessary, use a hand wheel to clean the leaks and grind out the grooves to ensure the quality of welding.
2) Use J422 electrode when repairing welding. The diameter of the electrode is 3.2mm. The current is controlled between 100-120A. Weld the missing spot first and then weld each layer of the repairing board, sequentially welding from the inside to the outside layer by layer.
3) The elliptical patch plate is closely attached to the inner arc surface of the heat exchanger for welding, and its purpose is to "convenient operation and ensure welding quality". 4) In order to smoothly install the elliptical repairing plate into the heat exchanger, a piece of round steel can be welded on the repairing plate, and the elliptical repairing plate can be removed after spot welding.
5) Short round steel braces are also welded between each layer of replenishment plates (mainly to increase the mutual rigidity of the oval replenishment plates). The number of short round steel braces welded on each layer of the repairing plate is determined by the size of the repairing plate. Generally, 23 welds are welded on the larger outer layer of the repairing plate, and the inner layer of the repairing plate is welded 1~ 2 pcs.
6) Because the super outer layer steel plate is δ12mm thick, so
1. Hydrochloric acid
Hydrochloric acid is the common name of hydrochloric acid. It is an aqueous solution of hydrogen chloride (HCl) gas. The solute is a strong monobasic acid. A common chemical and chemical raw material, there are many applications, including household cleaning, food additives, rust removal, leather processing, etc. The main component of gastric acid is also dilute hydrochloric acid. Hydrochloric acid is not only an important product of salt chemical industry, but also an important raw material for the production of silicon materials. The world's annual output of hydrochloric acid is about 20 million tons. Commercially available hydrochloric acid generally has a mass fraction of 37% (about 12mol/L). Need to store this liquid, the solubility should reach more than 38%, the temperature is 0-80 degrees, steel-lined plastic storage tanks can be used.
Sulfuric acid (chemical formula: H?SO?). Sulfuric acid is the most active binary inorganic strong acid. It can react with many metals. It crystallizes at 10.36℃. The mass fraction is generally around 75%. Polyethylene storage tanks can be used, but the purity is 95%. Carbon steel storage tanks or stainless steel storage tanks must be used for the above.
Ethanol (chemical formula: C2H5OH (C2H6O), commonly known as alcohol, is a flammable, volatile, colorless transparent liquid at room temperature and pressure. Its aqueous solution has a special, pleasant fragrance and slightly irritating Properties, boiling point: 78.4 °C, when the solubility is 30%, steel-lined plastic storage tanks can be used.
Chlorobenzene is a colorless liquid with a boiling point of 131.7°C. During the First World War, it was mainly used to produce picric acid required for military explosives. From 1940 to 1960, it was used in large quantities to produce DDT (DDT) insecticide. After 1960, DDT was gradually replaced by other pesticides with high efficiency and low residual toxicity, and the demand for chlorobenzene was declining. Polyethylene tanks cannot be used to store the liquid, but carbon steel tanks, stainless steel tanks, and glass fiber reinforced plastic tanks can only be used.
Acetic acid is acetic acid, also called acetic acid (0%-38%), glacial acetic acid (98%), chemical formula CH3COOH, is an organic monobasic acid, is the source of sour taste and pungent smell in vinegar. Pure anhydrous acetic acid (glacial acetic acid) is a colorless hygroscopic solid with a freezing point of 16.6°C (62°F), and becomes a colorless crystal after solidification. Although acetic acid is a weak acid based on its ability to dissociate in an aqueous solution, acetic acid is corrosive and its vapor is irritating to the eyes and nose. The annual worldwide demand for acetic acid is about 6.5 million tons. About 1.5 million tons are recycled and reused, and the remaining 5 million tons are made directly from petrochemical raw materials or made through biological fermentation. Polyethylene tanks can be used to store acetic acid, but polyethylene tanks cannot be used for glacial acetic acid.
The editor first introduces the storage of the above 5 kinds of liquids, so everyone should listen to the guidance of professionals when choosing storage tanks, and do not choose blindly~
23 2019-09Sodium hydroxide storage tankProduct features of sodium hydroxide storage tank:1: Material: There are two series. A: All plastic: all made of modified polyethylene. B: Steel-lined...
23 2019-09How to prevent corrosion outside the steel-lined plastic storage tankSteel-lined plastic storage tanks have the advantages of no welding seams, no leakage, non-toxicity, anti-aging, impact resistance, corrosion resistan...
23 2019-09Reflective heat insulation cooling paint to ensure the safety of petroleum storage tanksOil tanks and oil storage tanks are exposed to the open air, and the surface and internal temperature of oil storage tanks on the ground rises rapidly...
23 2019-09Aoen Steel Lined Plastic Anticorrosive Storage TankChangzhou Aoen steel-lined plastic anticorrosive storage tank has excellent corrosion resistance, and has good corrosion resistance to non-oxidizing a...