Plate heat exchanger plate heat exchanger is a new and efficient heat exchanger consists of a series of corrugated metal sheets with a certain shape made of stacked. Formed between the various plates of thin rectangular channel, through heat exchange plates. Plate heat exchanger is liquid - liquid, liquid - ideal for steam heat exchange equipment. It has a high heat transfer efficiency, heat loss, compact and lightweight, small footprint, easy installation and cleaning, widely used, and long service life. Under the same pressure loss, the heat transfer coefficient than the column tube heat exchanger 3-5 times higher, covers an area one-third tubular heat exchanger, heat recovery can be as high as 90%. 1 Introduction to the plate heat exchanger (Plate Type Heat Exchanger), this equipment by the plate heat exchanger, balance tank, centrifugal sanitary pumps, hot water installations (including steam piping, hot water is injected into the device), the bracket and meter boxes and other components. Sterilization of milk or other heat-sensitive liquids used for cooling. To deal with the material before entering the balance tank, the centrifugal pump into the heat exchanger of Health, after preheating, sterilization, heat, cooling the segments, who have not reached the sterilization temperature materials, instrumentation control commutation by pneumatic return valve, then Back to the balance tank reprocessed. Material from the instrument sterilization temperature control box for automatic control and continuous recording, in order to monitor and check the sterilization process. This device is suitable for pre-sterilized milk, pasteurization. Plate heat exchanger type main (removable) and brazed frame into two categories, mainly in the form chevron plate corrugated board, corrugated board and horizontal flat plate-shaped tumor three. 2 The basic structure of a plate heat exchanger plate heat exchanger structure ⒈ plate and the plate heat exchanger gasket fixed clamping plate ⒉ ⒊ ⒋ activities pressing plate clamping bolts guide rod after ⒌ ⒍ ⒎ column under the guide rod 3 Features (Compare with plate heat exchanger shell and tube heat exchanger) a. heat transfer coefficient due to different corrugated plates are inverted, a complex flow channel, the fluid in the flow passage between the corrugated board was rotating three-dimensional flow, can low Reynolds number turbulence (General Re = 50 ~ 200), the heat transfer coefficient is so high, generally considered to be 3 to 5 times the shell and tube. b. logarithmic mean temperature difference, small temperature difference at the end of the shell and tube heat exchangers, the two fluids in the flow tube and shell, respectively, on the whole cross-flow flow, logarithmic mean temperature difference correction factor is small, and the plate heat exchangers are mostly current or countercurrent flow pattern, the correction coefficient is usually around 0.95, In addition, cold and hot fluid flow in the plate heat exchanger are parallel to the heat transfer surface, without bypass, thus making the plate heat exchanger the end of the temperature difference is small, water heat exchanger can be less than 1 ℃, and shell and tube heat exchanger is generally 5 ℃ fff. Plate heat exchanger c. compact plate heat exchanger structure, small footprint, the unit volume heat transfer area is 2 to 5 times the shell and tube, and also did not want to shell and tube bundle maintenance reserve out of place, thus achieving the same heat transfer, plate heat exchanger shell and tube area is about to change heat 1/5 ~ 1/8. . c easy to change heat transfer area or the process, as long as the increase or decrease a few plates, can be achieved by increasing or decreasing the heat transfer area of ??the object; sheet arranged alter or replace a few plates, can achieve the desired combination of flow adapt to new conditions exchanger, shell and tube heat exchangers and heat transfer area is almost impossible to increase. d. light weight plate heat exchanger plate thickness of only 0.4 ~ 0.8mm, while the thickness of the shell and tube heat exchanger tubes of 2.0 ~ 2.5mm, than the plate heat exchanger shell and tube housing much heavier frame, plate heat exchanger tube is generally only about 1/5 of the weight of shell. e. low prices the same material, in the same heat transfer area, plate heat exchangers prices 40% to 60% lower than the shell and tube about. f. make convenient plate heat exchanger heat transfer plate is the use of punching, high degree of standardization and mass production, shell and tube heat exchangers are generally handmade. g. Easy to clean frame plate heat exchanger as long as loose bolts can loosen the plate beam, remove the plate for mechanical cleaning, which requires frequent cleaning equipment heat transfer process is very convenient. Plate heat exchanger i. Heat loss is small plate heat exchanger heat transfer plate only wrapper plate exposed to the atmosphere, and therefore heat loss is negligible and does not require insulation measures. The shell and tube heat exchanger heat loss, need insulation. h. the capacity of the smaller shell and tube heat exchanger is 10% to 20%. i. pressure loss per unit length of the large heat transfer surface due to the small gap between the heat transfer surface irregularity, and therefore greater than the pressure loss of the conventional smooth tube. j. difficult to scale because of the internal fully turbulent, so easy to scale, and its scaling factor is only a shell and tube heat exchanger 1/3 ~ 1/10. k. working pressure should not be too large, medium temperature is not too high There may leak using plate heat exchanger gasket seal, working pressure is generally not more than 2.5MPa, medium temperature should be lower than below 250 ℃, otherwise it may leak. l. easily blocked because of a very narrow passage between the plates, generally only 2 ~ 5mm, when the heat transfer medium contains large particles or fibrous material, easy to plug the passage between the plates. Under the four general categories, we distinguish the structure of the main plate heat exchanger, which is based on the shape to distinguish, can be divided into four categories: ① detachable plate heat exchanger (also known with gasketed plate heat exchangers device), ② welded plate heat exchangers, ③ spiral plate heat exchanger, ④ coil heat exchanger (also known as cellular heat exchanger). Among them, welded plate heat exchanger is divided: half-welded plate heat exchangers, all-welded plate heat exchangers, shell heat exchanger, brazed plate heat exchangers. Frequently used classification has the following: 1> according to the number of units of space heat transfer area, the plate heat exchangers are compact heat exchangers, shell and tube mainly with heat exchangers to compare conventional shell and tube occupies a large heat exchanger. 2> The process according to use, there are different terminologies: plate heater plate cooler, plate condensers, plate preheater; 3> According to the process portfolio, divided into one-way and multi-way plate heat exchanger plate heat exchanger ; 4> according to the flow direction of the two media, divided into downstream (and flow) heat exchanger, countercurrent heat exchanger, cross-flow (cross-flow) heat exchanger, the latter two are more used; 5> in accordance with the size of the gap flow channel, into conventional gap plate heat exchanger and wide-gap plate heat exchanger; 6> According to the corrugated plate heat exchanger, respectively, in more detail, no longer tired, please refer to: Plate Heat Exchanger corrugated sheet form. 7> according to whether it is a suite of products can be divided into single plate heat exchangers, plate heat exchanger unit. 5. a refrigeration applications: as a condenser and an evaporator. . b HVAC: with the intermediate heat exchanger boiler use intermediate heat exchangers and other high-rise buildings. Plate heat exchanger c chemical industry: soda ash industry, ammonia, alcohol fermentation, synthetic resin cooling. d Metallurgical Industry: aluminate liquor is heated or cooled, the steelmaking process cooling. e machinery industry: a variety of quenching liquid cooling, cooling lubricants reducer. f power industry: high voltage transformer oil cooling, generator bearing oil cooling. g paper industry: bleaching process heat recovery, heating wash liquid and so on. h textile industry: rayon alkaline aqueous cooling, boiling nitrocellulose cooling. i food industry: juice sterilization cooling, animal and vegetable oils, such as heating and cooling. j oil Process: soap atmospheric drying, heating or cooling liquid for various processes. . k central heating: heat and power plant waste heat for district heating, heating bath water. l Other: petroleum, pharmaceuticals, shipbuilding, desalination, geothermal, solar energy utilization. 6 Select the selection calculation plate or corrugated plate type should be based on the actual needs of the heat exchanger occasion may be. Allowed to flow pressure drop is small, the resistance should be used in small form factor, whereas a large selection of resistance plate. According to the fluid pressure and temperature determine the selection removable or brazed. Should not be selected to determine the area is too small plate veneer sheet, in order to avoid an excessive number of plates, the flow rate between the plates is small, the heat transfer coefficient is too low for larger heat exchanger should pay attention to this issue. Processes and runner selection process refers plate heat exchanger flow direction of a medium of the same set of parallel flow channels, while the Dow flow plate heat exchanger inside the adjacent medium flow path consisting of two plates. In general, the number of flow paths in parallel or in series connected together, to form a cold, different combinations of the heat medium passages. Combination process should be based on heat transfer and fluid resistance calculation, determined to meet the requirements under the process conditions. Try to make the cold, hot water heat transfer coefficient equal to or near tract, resulting in optimal heat transfer. Because the heat transfer coefficient for a larger value of the convective heat transfer coefficient equal or close to the heat transfer surfaces on both sides when. Although the range between the plates of plate heat exchanger flow rate, but in the heat transfer and fluid resistance calculation, the average velocity is still calculated. Because of "U" shaped single process to take over all fixed clamping plate, easy disassembly. When checking the pressure drop plate heat exchanger design selection, generally have certain requirements to drop, so and should be checked. If you check the pressure drop exceeds the allowable pressure drop, the need to re-calculate the design selection until meet the technical requirement. Calculation method to calculate the heat transfer coefficient and pressure drop of about performance curve is calculated by various manufacturers of products available. Performance curve (correlation criterion) generally comes from the performance testing of the product. For lack of performance test plate, but also through a reference size method, to obtain plate-type criterion correlation characteristics based on plate type geometry, some common software international are using this method. Selection Software on the plate heat exchanger selection software, generally based on their own plate manufacturers have their own selection software. Common international software HTRI, HTFS and so on. General public rarely calculation software, some domestic sites such as heat exchangers provide support website provides online plate heat exchanger calculation software is available for reference use. 7 principles of plate heat exchanger structure diagram dismantling detachable plate heat exchanger is made up of many corrugated sheet metal stamping at regular intervals, surrounded by the gasket seal, and overlapping with the frame and clamping screw pressed together, plates and mats four corners of the sheet apertures formed fluid distribution pipe and collecting pipe, while a reasonable manner to separate hot and cold fluids to flow respectively in both sides of each plate a flow passage through the heat exchange plates. 8 design features an energy-efficient: the heat transfer coefficient in 3000 ~ 4500kcal / m2 · ° C · h, 3 ~ 5 times higher than shell and tube heat exchanger thermal efficiency. 2. Compact: plate heat exchanger plates closely spaced, compared with other types of heat exchangers, plate heat exchangers less floor space and space, an area of ??the same heat transfer plate heat exchanger tubes only 1/5 shell heat exchanger. 3, easy to clean, easy accessibility: the plate heat exchanger will be clamped by the clamping bolt clamping plate board sheet, therefore easy disassembly, cleaning can be opened at any time, and because the plate surface smooth, high degree of turbulence and difficult to scale. 4, long life: plate heat exchanger made of stainless steel or titanium plates repression, can withstand a variety of corrosive media, pads can easily be replaced, and convenient, removable for maintenance. 5, adaptability: plate heat exchanger plates as an independent element, upon request free to change the process, in various forms; applicable to a variety of different process requirements. 6, no strings liquid, plate heat exchanger liquid-liquid seal tank vent channel settings, a variety of media will not collude, even leak occurs, the media always discharged outside. BR-series products, the whole structure is equipped with ordinary (non-washable conditions often uses) and suspension structure (washable conditions more frequent use of) two. Common structure by chevron corrugated board sheet, gasket, main parts hold-down plate, the upper and lower bolts, bolts and other components. Suspended structure by chevron corrugated board sheet, gasket, main parts fixed clamping plate, the intermediate plate, pressing plate activity, the stent, positioning the upper and lower beams, bolts and other components. Plate heat exchanger plate heat exchanger with a high heat transfer coefficient, pressure drop is small, compact, light weight, small footprint, convenient size and process composition, parts versatility, choose materials, and easy to implement wide-scale production, etc. characteristics, has been widely used in food, machinery, metallurgy, petrochemical, and shipping, etc., and become the city's leading central heating engineering heat transfer equipment. In order to ensure the normal operation of the plate heat exchanger to extend key components (such as plate, pads) life and understand the emergence of the plate heat exchanger failure and its causes and treatment is very important.