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Selection Guide for Bellows Heat Exchanger



Selection of water bellows heat exchanger steps:
It is assumed that the heating water inlet temperature T1; the inlet temperature T2; the heated water inlet temperature t1, the outlet temperature t2, and the heated water flow rate G2. You can choose the following steps:
(1) Calculate the required heat transfer Q;
(2) calculate the heating water flow rate G1;
(3) According to the heat transfer Q, the primary selection of bellows heat exchanger model, check the performance parameters of the following parameters: heat transfer area A; pipe flow area Si; shell flow area S0.
(4) Calculate the flow rate V and the shell flow velocity V0;
(5) According to Vi, V0 from the curve in Figure 6-35, find ai and a0;
(6) Calculate the heat transfer coefficient K;
(7) Calculate logarithmic mean temperature difference;
(8) Check the heat transfer, if you can meet the requirements, or should choose a new model, repeat the above (3) to (8) steps.
(9) According to Vi, V0 check the pressure drop curve Figure 6-36, Vi and V0 under the case of pressure drop to see if the pressure drop to meet the requirements. If the requirements are met, the selection is correct, otherwise it should be re-selected, repeat steps (3) to (9).
Selection of Steam - Water Heat Exchanger
Has the condition: saturated vapor pressure ps; saturation temperature ts; circulating water inlet temperature t1; outlet temperature t2; circulating water flow G Follow the steps below to select:
(1) calculate the heat transfer Q;
(2) According to the vapor pressure ps, heat transfer Q and circulating water flow G, the initial selection, and get the following parameters:
1) heat transfer area A;
2) Circulating water circulation area Si.
(3) calculate the circulating water velocity Vi;
(4) Calculate the heat transfer coefficient K. According to the flow rate Vi check curve Figure 6-37, you can get the heat transfer coefficient K.
(5) Calculate logarithmic mean temperature difference Δtm
(6) Check the heat transfer, if you can meet the requirements, or re-selection, repeat (2) to (6) steps.
(7) According to the flow rate Vi, check the curve 1 in Figure 6-36, the pressure drop △ p, if the pressure drop within the allowable range, the selection is correct, or should be re-selected, repeat (2) to (7 )A step of.
Selection of Oil - Water, Oil - Steam Bellows Heat Exchanger
Oil-water, oil-steam corrugated pipe heat exchanger selection is relatively complex, because the type of oil more, the different levels of viscosity, is bound to affect its heat transfer effect. Therefore, in the selection of bellows heat exchanger, this paper only gives some of the medium heat transfer coefficient for the choice of reference. Table 6-11 shows the correspondence between the heat transfer coefficient and the flow rate of the medium with low viscosity of light oil organic liquid. Table 6-12 shows the heavy oil, heavy organic liquid viscosity and other high heat transfer coefficient and the flow rate between the corresponding relationship, for reference only. According to the reference value given, the selector can calculate the heat transfer area, and then select the heat exchanger according to the heat transfer area.
Selection should pay attention to several issues
Each company in the preparation of their own product selection samples or product brochures, have their own unique way. Therefore, the user in the selection, should read the selection of samples or instructions, based on the understanding to be selected, otherwise the choice of models may not meet the requirements, or the request is too high, virtually increased The cost of the product.
1. Design pressure, design temperature, nominal pressure
The pressure of the bellows heat exchanger is any combination, Allow the working pressure, according to Table 6-13 to obtain the nominal temperature selected at the design temperature. While the design pressure is generally not less than the large allowable working pressure. For example: Model WBH600-2.5 / 1.6-39 ~ QX, on behalf of the tube, shell nominal pressure were 2.5MPa and 1.6MPa, if the pipe design temperature of 150 ℃, shell design temperature of 250 ℃, the tube Cheng Chao large working pressure is 2.45MPa, shell area oversized working pressure 2.23MPa, then take the pipe design pressure 2.5MPa, shell design pressure of 2.4MPa.
2. take over the flange
At present, the pipeline to take over the flange a lot of standards, such as the Department of Mechanical JB standard, standard GB, the Ministry of Chemical Industry Engineering Standard HGJ series. Therefore, the selection should be consistent with the standard series used by the user's pipeline, including the pressure level, the nominal diameter, the temperature used. In general, the nominal pressure of the water-water heat transfer and the flange is the nominal pressure level corresponding to the pipe or shell line where the pipe is taken over; the nominal pressure of the steam-water heat transfer is greater than the pipe The pressure level of the flammable, explosive, corrosive medium, the nominal pressure of the flange used than the pipe in the pipe or the shell of the nominal pressure level of the secondary level Of the pressure level.
3. Preferred model
Selection of units in the choice of heat exchanger models, the main assessment of the heat exchanger should be large heat transfer and the corresponding pressure drop to meet the requirements. In the installation conditions permitting, as far as possible the choice of small diameter, lengthened heat exchanger, so not only can improve the heat transfer effect, and can reduce the cost of equipment. If the heat transfer can meet the requirements, and the flow pressure drop beyond the allowable range, the nominal diameter of the heat exchanger should be increased, while the length of the heat transfer tube.
If the actual temperature of the selected unit is slightly different from the performance parameter in the same sample or in the product specification, if the logarithmic mean temperature difference is higher than the value in the performance parameter table, you can also refer to the data selection in the table. If the logarithmic average temperature difference is low In the performance parameter table, for the sake of safety, the length of the heat transfer tube can be increased or the nominal diameter of the heat exchanger can be increased.
The selection of the bellows heat exchanger is a comprehensive process that not only allows the selected bellows heat exchanger to achieve the required heat transfer area, but also the pressure drop, flow rate, installation position, as long as comprehensive consideration A suitable bellows heat exchanger. Spiral plate heat exchanger