First, shell and tube condenser
Shell and tube condenser, also known as tube condenser, is the most common condenser structure. Its principle is to flow gas or steam through the tube, inject cooling medium (usually water) in the outer shell, and reduce the temperature of gas or steam through the heat exchange between the tube and the shell, and finally achieve the effect of condensation. This condenser structure is more suitable for the treatment of high temperature and high pressure media, high reliability, but occupies a large space, easy to be affected by scale, slag scale and so on.
Second, plate condenser
Plate condenser, also known as heat exchange plate condenser, is a heat exchanger composed of plates, which has the advantages of compact structure and high heat exchange efficiency. Its working principle is that the medium is placed between the plate and the plate, and the cooling water is passed into the plate, and the condensation of gas or steam is realized through the efficient heat transfer of the plate. Plate condensers are suitable for small devices and require rapid heat exchange, but they are more difficult to clean and maintain.
Three, hollow component condenser
The common hollow component condensers are static washing type and high efficiency spray type. Its principle is to assemble hollow spheres or other shaped components into a whole, through the restriction and interception of these hollow components, so that the medium is fully dried and cooled in it, so as to achieve the effect of condensation. The advantages and disadvantages of the hollow component structure mainly depend on the shape and size of the component, and can be applied to some occasions where there are limitations on space and weight.
In short, different types of condenser structures have different scope of application and advantages and disadvantages for different media and use environments. Reasonable selection, maintenance and maintenance of condensers can improve the efficiency and life of equipment, and also ensure the safety of production and manufacturing.
First, water-cooled condenser
Water-cooled condenser is a common cooling method, and its main structure includes cooling pipe, water tank, water inlet, water outlet and cooling pump. In the process of use, the cooling water enters the water tank through the pump, and then flows through the cooling pipe, absorbing heat and then flowing out. Water-cooled condenser can be used in various industrial fields, such as power, chemical, metallurgy and so on.
Second, air-cooled condenser
The air-cooled condenser mainly relies on wind heat dissipation, and its structure includes heat sink, fan, motor and shell. When hot air flows through the heat sink, the fan takes it out and dissipates it through the housing, achieving a cooling effect. Air-cooled condenser is suitable for some occasions that need to be moved or inconvenient to install, such as outdoor environment.
Three, steam condenser
Steam condenser uses the principle of indirect condensation to dissipate heat, and its structure mainly includes steam chamber, cooling tube, shell and so on. In the process of use, the steam generated by the heat source transmits the cold amount through the cooling tube and becomes a liquid after contact with the outside world. Steam condensers can be used in many industries such as electric power, chemical industry and refrigeration, and are widely used in production and life.
Four, air condenser
The air condenser mainly uses air to cool the metal surface by heat exchange. Its structure mainly includes condensing tube, fan, shell and so on. When the hot gas is cooled through the inside of the condensing tube, it becomes a liquid in contact with the outside world. Air condensers can be used in some scientific research and laboratory applications.
The above is the main structure type of condenser, and each type of condenser has its own unique working principle and scope of application. When choosing a condenser, it is necessary to understand the specific working conditions and use environment, select the most suitable type of condenser, and ensure normal maintenance to achieve the best use effect.
.
According to the different cooling medium, condensers can be divided into four categories: water-cooled, evaporative, air-cooled and water-sprayed condensers.
(1) Water-cooled condenser
Water-cooled condenser uses water as the cooling medium, and the temperature rise of water takes away the condensing heat. Cooling water is generally recycled, but the system needs to be equipped with cooling towers or cool pools. According to its different structure types, water-cooled condenser can be divided into vertical shell and tube type, horizontal shell and tube type according to its different structure types, it can be divided into vertical shell and tube type, horizontal shell and tube type and so on. The common shell and tube type condenser is.
1, vertical shell and tube condenser
Vertical shell and tube condenser, also known as vertical condenser, is a water-cooled condenser widely used in ammonia refrigeration system at present. The vertical condenser is mainly composed of a shell (barrel), a tube plate and a tube bundle.
The refrigerant steam enters the gap between the tube bundle from the steam inlet at 2/3 of the height of the barrel, and the cooling water in the tube and the high-temperature refrigerant steam outside the tube exchange heat through the tube wall, so that the refrigerant steam is condensed into a liquid and gradually flows down to the bottom of the condenser and into the liquid reservoir through the outlet pipe. After absorbing heat, the water is discharged into the lower concrete pool, and then the pump is sent to the cooling water tower after cooling and recycling.
In order to ensure that the cooling water can be evenly distributed to each tube port, the distribution tank at the top of the condenser is provided with a uniform water plate and each tube port at the upper part of the tube bundle is equipped with a deflector with a inclined groove to make the cooling water flow down along the inner wall of the tube with a film water layer, which can both improve the heat transfer effect and save water. In addition, the shell of the vertical condenser is also provided with a pressure equalizing pipe, pressure gauge, safety valve and air discharge pipe and other pipe joints in order to connect with the corresponding pipelines and equipment.
The main features of the vertical condenser are:
1. Due to the large cooling flow rate and high velocity, the heat transfer coefficient is high.
2. Vertical installation covers a small area and can be installed outdoors.
3. The cooling water flows through and the flow rate is large, so the water quality is not high, and the general water source can be used as cooling water.
4. The scale in the pipe is easy to remove, and there is no need to stop the refrigeration system.
5. However, because the temperature rise of the cooling water in the vertical condenser is generally only 2 to 4 ° C, the logarithmic average temperature difference is generally about 5 to 6 ° C, so the water consumption is large. And because the equipment is placed in the air, the pipe is easy to be corroded, and it is easier to be found when leaking.
2, horizontal shell and tube condenser
Horizontal condenser and vertical condenser have similar shell structure, but there are many differences in general, the main difference is the horizontal placement of the shell and the multi-channel flow of water. The outer tubes of both ends of the horizontal condenser are closed with an end cover, and the end cover is cast with a water-distributing rib designed to cooperate with each other, and the whole bundle is divided into several tube groups. Thus, the cooling water enters from the lower part of the end cover, flows through each tube group in order, and finally flows from the upper part of the same end cover for 4 to 10 return trips. In this way, the flow rate of the cooling water in the tube can be increased, so as to improve the heat transfer coefficient, and the high-temperature refrigerant vapor can enter the tube bundle from the inlet pipe of the upper part of the shell to carry out sufficient heat exchange with the cooling water in the tube.
The condensed liquid flows from the lower outlet pipe into the reservoir. The other end cover of the condenser is also permanently provided with an air drain valve and a water drain cock. The exhaust valve in the upper part is opened when the condenser is put into operation to discharge the air in the cooling water pipe and make the cooling water flow smoothly, remember not to be confused with the vent valve to avoid accidents. The water drain cock drains the water stored in the cooling water pipe when the condenser is decommissioned to avoid freezing and cracking the condenser due to freezing of water in winter. The shell of the horizontal condenser is also provided with a number of pipe joints connected with other equipment in the system, such as air intake, liquid outlet, pressure balancing pipe, air discharge pipe, safety valve, pressure gauge joint and discharge pipe.
Horizontal condensers are not only widely used in ammonia refrigeration systems, but also in freon refrigeration systems, but their structure is slightly different. The cooling pipe of ammonia horizontal condenser uses smooth seamless steel pipe, while the cooling pipe of Freon horizontal condenser generally uses low-ribbed copper pipe. This is due to the low heat release coefficient of freon. It is worth noting that some freon refrigeration units generally do not have a liquid storage cylinder, only a few rows of pipes at the bottom of the condenser are used as a liquid storage cylinder.
Horizontal and vertical condensers, in addition to the different placement and water distribution, the temperature rise and water consumption of water are also different. The cooling water of the vertical condenser is the highest gravity flowing down the inner wall of the tube, and it can only be a single stroke, so in order to obtain a large enough heat transfer coefficient K, a large amount of water must be used. The horizontal condenser uses a pump to send the cooling water pressure to the cooling pipe, so it can be made into a multi-stroke condenser, and the cooling water can get a large enough flow rate and temperature rise (Δt=4 ~ 6℃). Therefore, the horizontal condenser can obtain a large enough K value with a small amount of cooling water.
However, if the flow rate is excessively increased, the heat transfer coefficient K value is not increased much, and the power consumption of the cooling pump is significantly increased, so the cooling water flow rate of the ammonia horizontal condenser is generally about 1m/s, and the cooling water flow rate of the freon horizontal condenser is mostly 1.5 ~ 2m/s. The horizontal condenser has high heat transfer coefficient, small cooling water consumption, compact structure and convenient operation and management. However, the water quality of the cooling water is required to be good, and the scale is not convenient to clean, and it is not easy to find when leaking.
The vapor of the refrigerant enters the cavity between the inner and outer tubes from the top, condenses on the outer surface of the inner tube, and the liquid flows down the bottom of the outer tube successively and flows into the reservoir from the lower end. The cooling water enters from the lower part of the condenser and flows out from the upper part through each row of inner pipes in turn, in a countercurrent mode with the refrigerant.
The advantages of this condenser are simple structure, easy to manufacture, and because of the single tube condensation, the medium flow direction is opposite, so the heat transfer effect is good, when the water flow rate is 1 ~ 2m/s, the heat transfer coefficient can reach 800kcal/(m2h℃). Its disadvantage is that the metal consumption is large, and when the number of longitudinal tubes is large, the lower tube is filled with more liquid, so that the heat transfer area can not be fully utilized. In addition, the compactness is poor, the cleaning is difficult, and a large number of connected elbows are required. Therefore, this condenser has rarely been used in ammonia refrigeration units.
(2) evaporative condenser
The heat transfer of evaporative condenser is mainly carried out by the evaporation of cooling water in the air to absorb the latent heat of gasification. According to the air flow mode can be divided into suction type and pressure type. In this type of condenser, the cooling effect caused by the evaporation of refrigerant in another refrigeration system is used to cool the refrigerant steam on the other side of the heat transfer partition wall, causing the latter to condense and liquefy. Evaporative condenser is composed of cooling tube group, water supply equipment, fan, water baffle and box, etc. The cooling tube group is a serpentine coil group made of seamless steel pipe bent and installed in a rectangular box made of thin steel plate.
The two sides or top of the box are provided with a fan, and the bottom of the box is also used as a cooling water circulation pool. When evaporative condenser works, the refrigerant steam enters the serpentine tube group from the upper part, condenses and releases heat in the tube, and flows into the reservoir from the lower outlet tube. The cooling water is sent to the sprinkler by the circulating water pump, sprayed from the surface of the upper steering wheel tube group of the serpentine coil group, and evaporated through the tube wall to absorb the condensed heat in the tube. A fan located on the side or top of the box forces air to pass over the coil from bottom to top, promoting the evaporation of water and carrying away the evaporated water.
Among them, the fan is installed on the top of the box, the serpentine tube group is located on the suction side of the fan is called suction evaporative condenser, and the fan is installed on both sides of the box, the serpentine tube group is located on the air output side of the fan is called pressure feed evaporative condenser, the suction air can evenly pass through the serpentine tube group, so the heat transfer effect is good, but the fan operates under high temperature and high humidity conditions, prone to failure. Although the air passing through the serpentine tube group is not uniform, the working conditions of the fan motor are good.
Evaporative condenser features:
1. Compared with the water-cooled condenser with direct current water supply, it saves about 95% water. However, compared with the combination of water-cooled condenser and cooling tower, the water consumption is similar.
2, compared with the water-cooled condenser and cooling tower combined system, the condensation temperature of the two is similar, but the evaporative condenser has a compact structure. Compared with air-cooled or water-cooled condenser with direct current water supply, its size is relatively large.
3, compared with the air-cooled condenser, its condensing temperature is low. Especially in dry areas. When running all year round, it can work by air cooling in winter. The condensing temperature is higher than that of the water-cooled condenser with direct current water supply.
4, condensate coil is easy to corroded, easy to scale outside the pipe, and maintenance is difficult.
In summary, the main advantages of evaporative condenser are small water consumption, but the circulating water temperature is high, the condensing pressure is large, the cleaning scale is difficult, and the water quality is strict. Especially suitable for dry water shortage areas, it should be installed in places with open air circulation, or installed on the roof, not installed indoors.
(3) Air cooled condenser
Air-cooled condenser uses air as the cooling medium, and the temperature rise of air takes away the condensing heat. This condenser is suitable for extreme water shortage or no water supply, commonly found in small freon refrigeration units. In this type of condenser, the heat released by the refrigerant is carried away by the air. The air can be natural convection, or forced flow can be used by fans. This type of condenser is used in freon refrigeration units in places where water supply is inconvenient or difficult.
(4) Shower condenser
It is mainly composed of heat exchange coil and shower water tank. The refrigerant vapor enters from the lower inlet of the heat exchange coil, while the cooling water flows from the gap of the shower tank to the top of the heat exchange coil, and flows down in a film shape. The water absorbs the condensing heat, and in the case of natural convection of air, the condensation heat is taken away due to the evaporation of water. After being heated, the cooling water flows into the pool, and then is recycled after cooling by the cooling tower, or a part of the water is drained, and a part of the fresh water is added to the shower tank. The condensed liquid refrigerant flows into the reservoir. The drip-water condenser is the temperature rise of water and the evaporation of water in the air to take away the condensing heat. This condenser is mainly used in large and medium-sized ammonia refrigeration systems. It can be installed in the open air or under the cooling tower, but it should be avoided from direct sunlight. The main advantages of shower condenser are:
1. Simple structure and convenient manufacture.
2, ammonia leakage is easy to find, easy to maintain.
3, easy to clean.
4, low water quality requirements.
The disadvantages are:
1. Low heat transfer coefficient
2, high metal consumption
3, covers a large area