Front plate temperature increasing device for detachable plate heat exchanger
Such as the use of brazed plate heat exchanger or laser all welded plate heat exchanger, the purchase of large equipment (about times the price of detachable plate heat exchanger), and can not be disassembled, not easy maintenance.
Plate heat exchanger has the above advantages, but it can not completely replace the shell and tube heat exchanger. The heating carrier is 1.1MPa and 230 DEG C, the heating carrier is hot water, the water supply temperature is 92 DEG C, the return water temperature is about 70 DEG C, the water supply pressure is 0.5MPa, and the return water pressure is 0.14MPa. During the overhaul period in 2006, the original shell and tube heat exchanger was transformed into plate cooler.
Therefore, the ultimate in add cooling device of traditional removable plate heat exchanger in front of the scheme, in this scheme, the heat transfer efficiency is low, but high temperature resistant shell and tube heat exchanger as steam desuperheater, a department of heating return (about 10% of total water flow of the left and right) after overheating steam down to 150~180 DEG C, and the remaining departments into the heat exchanger heating backwater heating, this scheme fully utilizes the two heat exchanger of the upper hand, while heating the water side of the parallel operation mode, a series is more effective in reducing the pressure drop, more energy. The plate heat exchanger only need to loosen the clamping screw, in the original space within the scope of 100% contact heat exchange plate surface, easy maintenance. The shell type heat exchanger, two kinds of fluid in the shell and tube sides in the activities, on the whole is cross flow activities, namely in the shell is a mixture of activities in the tube into multiple activities, so the general small correction coefficient of uniform heat transfer temperature (about 0.8).
For the heat exchange station in the unit area of the central control, substation building and laboratory building, Department of pump room and dosing between winter heating had been used for shell and tube heat exchanger. Because the original shell and tube heat exchanger equipment is obsolete, the maintenance quantity is big, and the steam consumption increases year by year. Easy operation and maintenance of plate heat exchanger is composed of a plurality of a plate assembly, only need to increase and decrease the number of plates can easily adjust the heat transfer area size, the use of very flexible manipulation, flexibility, and tube shell type that need to set aside a lot of space to pull out test tube. The heat transfer efficiency of heat exchanger is very high, there are many international companies can provide the minimum heat exchanger products uniform temperature log Delta Tm=1 C. Because of the large perturbations of the thinning of the film thickness, which can prevent the deposition of impurities in the heat transfer surface adhesion, thereby reducing the fouling resistance, and the thickness of the plate is only 0.6~0.8mm, the heat resistance is small, in the heat exchanger, cold and hot fluid respectively from both sides of the plate through the fluid flow is small, not on the tube shell heat exchanger is that the total heat transfer coefficient of bypass flow, so high. The movement of the fluid in the plate heat exchanger is generally in the form of cocurrent or countercurrent flow, and the correction coefficient of heat transfer is 0.95.
By using the 1.1MPa heat exchanger station; superheated steam temperature of 230 DEG C, the gasket temperature limit (EPDM gasket temperature of 150 DEG C, EPDM high temperature resistant gasket is 180 DEG C, high temperature resistant PTFE gasket temperature is only 220 degrees Celsius, and the price is expensive, 8 times of high temperature EPDM the left and right), so the traditional gasket detachable heat exchanger does not apply to the requirements of working conditions.
The plate exchanger is generally made of grooved or corrugated medium, activity in the flow channel is three-dimensional activities with complex structure, its activities and activities are changing the direction of speed, caused a great disturbance in the low Reynolds number (Re=50~200) can induce turbulence (column and tube type heat exchanger for Reynolds the number reached more than 2000). If the water / water as heat transfer medium, up to 8360~25080kJ/m2, the total heat transfer coefficient of heat exchanger; h; C is 3~5 times that of shell and tube heat exchanger heat transfer coefficient, but the volume of the equipment is only of shell and tube heat exchanger is about 30%. Both the direction and the mode of the fluid will affect the logarithmic uniform temperature difference. However, the minimum temperature difference between the hot and cold logistics is too large to cause the heat exchanger area of the heat exchanger is very large. On the one hand is due to heat exchanger medium cleanliness requirements higher, it requires the impurity particles in the medium diameter less than 1.5~2mm; on the other hand is due to plate type heat exchanger (commonly known as the early detachable heat exchanger) only for working pressure less than 1.6MPa, for temperatures between 120~165 degrees Celsius conditions.
