As a type of plate heat exchanger, plate condenser is a heat exchanger specially designed for condensing conditions. When the amount of condensation is small and the temperature is high, we can use ordinary plates for the condenser. The designed plate condenser will bring unparalleled superiority.
Ordinary plate replacement is generally designed for liquid-liquid heat exchange conditions, both sides of which are liquid on both sides. The plate structure generally adopts a herringbone wave design. Figure 1 shows our GJ-AM series plate type, which is a universal plate heat exchanger with a wide range of use and high heat transfer efficiency. Analyzing the layout structure, it can be easily seen that the ripple is a herringbone wave , Using a uniform size of the corner hole design.
Special condensers are generally optimized for vapor-liquid conditions, that is, hot fluid is steam with a large volume flow, and cold fluid is circulating cooling water (or other cooling medium, generally liquid). Figure 2 shows our GJ-L series plate type, which is a special plate condenser specially designed for condensing conditions. It uses a concave-convex design and a special corner hole design.
By comparing the characteristics of the two types of plate corrugations, flow channels, corner holes, etc., as follows:
1: Ripple. The ordinary plate replacement is generally a herringbone wave design, the main purpose is to make the fluid reach turbulence and enhance heat transfer. The design of different wave angles is mainly used to balance heat transfer and resistance loss. The plate condenser uses a special corrugated design. The steam side ripple mainly supports the flow channel, and the cooling water side ripple plays a role in enhancing heat transfer.
2: runner. Ordinary plate replacement generally uses a 2-4mm plate spacing design, which can be designed as shallow dense corrugations, which can achieve higher turbulence and enhanced heat transfer. The plate condenser uses a wide and narrow flow channel design, with large and straight wide steam flow channels, and small and tortuous narrow cooling water flow channels, which greatly improves the steam and water heat transfer capacity.
3. Corner holes. Ordinary plate corner holes are usually the same size, which also meets the characteristics of liquid-liquid fluid heat exchange on both sides. Unlike plate condensers, their unique feature is that the steam inlet is very large, because the volume of the condensing vapor is very large. It is huge, which is dozens or even dozens of times of the cooling fluid, and the volume of the condensate shrinks sharply, so the condensate connection can be designed smaller. The plate condenser adopts an optimized design of the steam inlet and the condensate water outlet, which can meet the demand for a large amount of steam condensation, even for a large number of low-temperature steam.
Through a simple comparison, we then answer the question whether the plate heat exchanger can be used as a plate condenser. The answer is: a small amount of condensation and a small volume can be used, but for large flows and large volumes, we recommend that the special plate type be preferred. Condenser.
Due to the late development of plate condensers in China, many domestic manufacturers use ordinary plate heat exchangers to replace plate condensers, and they have found that the results are okay. Of course, this effect refers to the comparison with the column condenser, not the professional plate condenser. Therefore, many people mistakenly think that ordinary plate replacement can completely replace the plate condenser. In fact, ordinary plate heat exchangers have certain limitations as condensers. The specific reasons are as follows:
1: Ordinary plate heat exchangers are usually as large as four corner holes. Because the density of gas and liquid is very different, considering that the steam flow rate cannot be too fast under the same mass flow rate, a particularly large inlet is required. We can imagine a common plate heat exchanger with four corner holes that are DN500. It will be a very huge plate, which will not only increase the manufacturing difficulty, but also cause waste of resources, because the four corner holes are particularly large, but the area they occupy does not participate in heat transfer. Therefore, when the steam flow is relatively large, it is difficult to find a plate with a particularly large plate area and corner holes. At this time, the ordinary plate heat exchanger cannot replace the plate evaporator.
2: During the condensation process, we always want the pressure drop of the condensing steam to be as small as possible, because if the steam pressure becomes smaller, the corresponding condensation temperature will also become smaller. At this time, the temperature difference between the hot and cold fluids will become smaller and the required heat exchange area will be smaller. Increase. Cause unnecessary waste. Due to the small corner holes of ordinary plate heat exchangers, the steam inlet velocity is often too fast and the pressure drop is increased. The steam pressure decreases and the area increases.
3: The wave form of the plate condenser is different from that of the ordinary plate heat exchanger. The chevron wave is mainly used to enhance turbulence and heat transfer. The main purpose of the wave is to discharge the condensate quickly, reduce the thickness of the liquid film, and reduce the thermal resistance. To enhance heat transfer. In addition, the distance between the condensing side of the plate condenser and the circulating water measurement board is not the same. This design allows the steam to widen the flow channel and reduce the flow rate, thereby reducing the pressure drop, and the circulating water flows to the narrow flow channel, thereby increasing the flow rate. , To strengthen the role of heat transfer.
In summary, ordinary plate heat exchangers can be used as plate condensers, but due to the limitation of the flow of condensing gas, the flow rates are too large, and the pressure drop will be higher than that of plate condensers. Therefore, when selecting a plate condenser and an ordinary plate heat exchanger, the plate condenser should be the first choice. If limited by conditions, the ordinary plate heat exchanger can also be temporarily replaced.