课题换热器毕业设计翻译.doc

1、 Comparison of Water-water Heat Exchanger Between Shell-and-tube Type and Plate Type Abstract : The closed-cycle cooling water system in the water of heat exchanger selection, discusses in detail the shell and tube heat exchanger with plate structure a nd properties of technical and economic compari

2、son of selection for the water of heat exchangers provide a reference. Keywords: heat exchanger performance comparison Power plants have been built from the domestic point of view, for the closed cycle cooling water system of the water of heat exchanger there are two types, one is shell and tube hea

3、t exchanger, and the other is a plate heat exchanger. Shell and tube heat exchanger is commonly used in heat exchangers form, in power plant design has been widely used, but some imported units in the domestic power plant, gas-steam combined cycle power plants and nuclear power plants have adopted m

4、ulti-plate heat exchanger . As the plate heat exchanger compact, light weight, high heat transfer efficiency, a growing interest in it. In this paper, shell and tube and plate heat exchanger to compare two kinds of patterns and make selection of reference. A shell-and plate heat exchanger structure

5、Introduction (1) Shell and tube heat exchanger Shell and tube heat exchanger is a former Marine Room, tubes, tube, after the composition of the water room. Tubes used to pump-type tubes, which consists of front and rear tube plate, baffle plate, rod, will be away from the tube, heat-exchange compone

6、nt. Rod and tube plate, split-flow plate using threaded connections, heat exchange tube and tube sheet welding using sealed expansion joint increases. In the shell side of the water at the entrance to the tube bundle to set anti-scour plate, in order to prevent the cooling water directly to scour Tu

7、be. Bundle into or out of order to reduce friction when the tube in the bundle with the slide. In order to check the clean room, trash, sediment and tube blockage in the water chamber before and after an inspection hole on the end cap. In order to monitor the water of heat exchanger operation, being

8、 the cooling water side (except salt water side) and the cooling water side (sea side) imports and exports are set temperature and pressure measuring points, in addition to interfaces with the exhaust and turn on the water. (2) The plate heat exchanger Plate heat exchanger is a corrugated-shaped by

9、a group composed of parallel metal plates in the plates four corners have the access hole, the side panels were clamped in a fixed plate with a connecting tube and activities of pressed board framework, and used to clamp clamping bolts. The connecting pipe with the hole right in the channel plate, a

10、nd with hot-swappable external piping connected to two kinds of liquids, heat transfer plates and the activities of pressed sheet hanging below the beam at the top of the bearer by the bottom of the beams so that it aligned location. There is a heat transfer plate itself has a specific shape and is

11、solid tight gasket seal to prevent external leakage, and to heat exchange of the two kinds of liquids by means alternately counter-current flow on heat transfer plates to another within the channel between the . Ripples on the plate not only improve the level of fluid turbulence, and the formation o

12、f many points of contact in order to withstand the normal operating pressures. Fluid flow, physical properties, pressure drop and temperature difference determines the number and size of plate. 2. Heat exchanger design conditions Heat exchanger should be designed to meet the maximum output power fro

13、m the start-up to load when you run a variety of needs, and left a certain margin to ensure the heat exchanger at maximum load, the maximum water temperature and maximum thermal resistance when the dirt, in the prescribed maintenance cycle, able to complete the task given cooling. With the introduct

14、ion of domestic-type 300 MW coal-fired units, for example, the cooling device requires cooling water inlet temperature is not greater than 37.5 , from the cooling device out of the cooling water is heated before the maximum temperature is about 42.8 , its basic parameters are as follows: In addition

15、 to the cooling water salt water Design pressure 1.0 MPa Flow 1800 m3 / h Out of water temperature 42.8/37.5 Pressure drop of 0.06 MPa Cooling water Seawater (seawater and river water alternately change) Design pressure 0.5 MPa Inlet temperature 33 Water temperature Circulating water Drop of pressur

16、e 0.05 0.06 MPa 3.Shell and plate heat exchanger in comparison 3.1 Comparison of design parameters According to the design of heat exchanger, respectively, made the following three conditions of the program: Program 1:two 100% capacity, Tube shell heat exchanger Program 2:two 100% capacity plate hea

17、t exchanger Program 3:three 50% capacity plate heat exchangers Parameters of the program in Table 1. Table 1.The design parameters of the scheme of heat exchanger 3.2 The open-cycle cooling water (water of the cooling water side heat exchanger) system, equipment selection Comparison According to she

18、ll and tube and plate heat exchanger and cooling of different structural forms of water, need to choose a different electric filter and the open-cycle cooling water pumps, shown in Table 2. Table 2.The filter and pump parameters of each scheme selection No Item Unit Program 1 （ Tube shell type） Prog

19、ram 2 （ Plate-type） Program 3 (Fifty percent plate-type) 1 Type of water and heat transfer Tube shell type Plate-type Plate-type 2 The amount of removing salt water m3/h 1800 1800 900 3 Water of heat exchanger installed units / run units 2/1 2/1 3/2 4 Each of the cooling area m2 1023 785.7 314.6 5 H

20、eat transfer coefficient W/(m2 k) 3579 4435 6 Desalted water entrance temperature The desalted water outlet temperature 42.8 37.5 42.8 37.5 42.8 37.5 7 The entrance temperature of circulating water The outlet temperature of circulating water 33 36.5 33 39 33 39 8 The flow rate of circulating water m

21、3/h -3000 1632 821.4 9 Materials Titanium tube, titanium composite board Titanium tube Titanium tube 10 Size mm 1800 9800 4300 1300 3470 3100 1300 2530 11 Weight kg 27002 5010 3720 Devices Item Unit Program 1 （ Tube shell type） Program 2.3 （ Plate-type） Open cycle pump Type 24sh- 19 A(resistance to

22、seawater) 20 sh- 13 A(resistance to seawater) Flow m3/h 2304 3600 1440 2232 Lift mH2O 31.5 20 34 26 Motor power kW 280 315 Installation units 台 2 2 Operation units 台 1 1 电动 滤网 Type vertical(resistance to seawater) vertical(resistance to seawater) Flow m3/h -3000 1700 Strainer aperture mm 6 3 4 3.3 C

23、omparison of flow and heat transfer design Shell and tube heat exchanger heat exchanger tubes are the basic building blocks, which has in the pipe flow of a fluid and through the pipe apart from the provision of heat transfer between a fluid surface. According to both sides of the fluid nature of pi

24、pe materials, will have a corrosive, water quality, poor water on the pipe flow, water quality, a good addition to brine on the shell side of the tube, so only use seawater corrosion-resistant tubes titanium tube, while cleaning dirt is more convenient, diameter from a heat transfer fluid mechanics

25、point of view, given the use of small-diameter tubes the shell, you can get a larger surface density, but most current experience of the dirt deposited on the surface of the pipe layer, in particular, the cooling water pipe poor, silt and dirt and sea creatures exist, are likely to form a sediment i

26、n the wall, will worsen the regular cleaning of heat and work as a necessary restrictions on the tube diameter and the smallest is about cleaning 20 mm, Titanium tube usually taken 25 mm, for a given fluid, dirt formed mainly by the impact of the wall temperature and flow rate, in order to get a rea

27、sonable maintenance cycle, the water velocity inside tube should be 2 m / s or so (depending on the requirements to allow pressure drop ). As a general cooling water use sea water, river water etc., are prone to causing fouling on the shell and tube heat exchanger, should be based on sediment concen

28、tration of water required to set up a regular rubber ball cleaning device cleaning. Plate heat exchanger cooling water and cooling water have been on both sides of convection in the corrugated board, corrugated chevron corrugated using these heat transfer plates of corrugated bias, that is adjacent

29、heat transfer plate has the same tilt angle but in a different direction ripple. Cross-sectional area along the flow direction is constant, but because of the ever-changing flow direction resulted in changes in shape of flow channel, which leads to turbulence. The general heat transfer plates of cor

30、rugated depth of 3 5 mm, turbulent flow area is about 0.1 1.0 m / s, corrugated thin thickness of 0.6 1 mm, adjacent cubicles have many points of contact in order to to withstand normal operating pressures, the adjacent panels are in the opposite direction of the chevron grooves, two grooves formed

31、at the intersection point of contact that would also eliminate vibration, and in the promotion of turbulence and heat exchange at the same time, eliminating the due fatigue cracks caused by internal leakage. Chevron corrugated high degree of turbulence and high turbulence can give full play to clean

32、 them can be particularly effective to minimize the deposition of dirt, but the corrugated point of contact are more poor water quality when the liquid containing suspended solid particles, mixed animals and plants, etc., due to plate gap is very narrow, so as far as possible to ensure that all part

33、icles 2 mm or more before entering the heat exchanger, we must filter out, if the filter can not effectively play its role, it prone to clogging. 3.4 Comparison of heat transfer coefficient Tube shell heat exchanger, a tube of fluid passing through the lateral wall with the pipe flow of another flui

34、d heat exchanger, each vertical cross-flow, the heat transfer coefficient is generally 1000 3000 w / (m2.k) . Plate heat exchanger, cooling water, cooling water side by side with the uniform turbulent flow, two kinds of reverse flow of fluid, due to the role of ripples caused by turbulence, resultin

35、g in a high heat transfer rate, high resistance to pressure drop and high shear stress field, which will led to the formation of inhibiting fouling in the heat transfer surface. The heat transfer coefficient is generally 3500 5500 w / (m2.k), this can save heat exchanger heat transfer area. 3.5 Comp

36、arison of temperature difference Shell and tube heat exchanger terminal temperature difference (ie, cooling water inlet temperature and the cooling water outlet temperature difference is) for about 5 . Plate heat exchanger, because of its structural features can be economically achieved as low as 1

37、of temperature difference. 3.6 Comparison of cooling water Shell and tube heat exchanger cooling water and is generally the ratio of the cooling water is 1.2 2.5:1. Plate heat exchanger, due to two kinds of media flow path is basically the same heat transfer efficiency and high, plate heat exchanger

38、s can greatly reduce the amount of cooling water, cooling water and is generally the ratio of the cooling water of 0.8 1.1:1, so that Pipeline valves and pumps can reduce the running costs of the installation. 3.7 Comparison of installation and maintenance Plate heat exchanger with small size and li

39、ght weight characteristics, easy maintenance, without lifting set up maintenance facilities, and therefore less installation area. The artificial maintenance of plate heat exchanger including the folding machine to open, using spray guns and brushes clean plates and gaskets, inspection plates and ga

40、skets, if necessary, replacement plates and gaskets. Plate heat exchangers to clean an annual general meeting, and whether or not the actual needs should be done. When the application of river water, seawater cooling water, poor water quality, due to the presence of silt and dirt, as well as the rap

41、id growth of micro-organisms caused by surface contamination and the risk of clogging. In other countries, application of river water for cooling water, cleaning frequency is high, with an average 3.3 times per year. Shell and tube heat exchanger tube bundle is composed of its own weight were relati

42、vely large in size, in the maintenance pumping tube bundle when the need to stay out as long as the distance, it covers an area of more, with the necessary lifting needed to overhaul facilities. Shell and tube heat exchanger design life is generally 30 years, overhaul cycle, four years, when the hea

43、t exchanger leakage occurs, (which may be between the tube and tube sheet caused by leaking or broken pipe leakage) can be used blocked tube way in a short time return to work performance, shell and tube heat exchanger to allow plugging of 7% margin. For the cleaning of pipes as needed using rubber

44、ball cleaning device of mechanical cleaning on a regular basis. 4. heat exchangers in the domestic power plant operation (1) Huaneng Yueyang Power Plants two units 362 MW unit, the British manufacturer, plate heat exchanger is supplied complete with the host. Plant is located along the Yangtse, recy

45、cled water for the Yangtze River, where the Yangtze River water is characterized by coarse less sand and more plants and more of this recycled water into the steam room before the set up filters to deal with three plants and so on, but according to plant reflection of plate heat exchangers easily bl

46、ocked, because the rotating filter according to analysis of poor sealing, leakage into the plants, the fundamental issue is the three filtering poor prognosis. (2) Shanghai Wujing Power Plant 6 project hosts the Shanghai production of 300 MW of imported type unit, the unit closed cooling water syste

47、ms, heat exchanger shell and tube water of the cooling water from the circulating water system supply, recycled water to take The Huangpu Rivers water, water, garbage, debris more, so water of heat exchanger entrance to set up two open-rotary filter, 11 aircraft fitted with the original design of th

48、e filter for the imported equipment, filter pore size 3 4 mm, due to poor water quality in the Huangpu River, frequently blocked the operation can not be self-cleaning, after numerous debugging invalid, this artificial split in the operation, the total cleaning equipment, labor intensive, but also a

49、ffect the safe operation of unit Basically, every other day, need to manually cleaning. Analysis was mainly due to small pore size filters, filters in the structure design is not suited to Chinas water quality. To address the above issues, adopted a new electric automatic backwash filters, filter pore size of 6 mm in good condition