On the application of spiral thread tube heat exchanger in API production

With the rapid development of APIs, China has become a major producer and exporter of APIs for pharmaceutical use in the world At present, China is facing the golden development period of pharmaceutical APIs and intermediates, "breakthrough, development and innovation" is the development trend of API industry, how to achieve energy saving and consumption reduction is particularly important to improve the competitiveness of enterprises, and the condenser, which plays a decisive role in the production process of APIs, has an important impact on this Currently, the types of heat exchanger used in China There are many kinds of heat exchangers, such as tubular, plate, tube plate, etc most of the working conditions of the heat exchanger are asymmetric flow heat exchange, that is, the flow of two kinds of fluid through the heat exchanger is different, which requires two different heat exchange areas The design mechanism of plate heat exchanger is symmetrical flow heat transfer, which can not provide different heat exchange areas for the fluid The world's * screw thread tube JAD heat exchanger was developed and invented in secespol group of Poland in 1988 When the heat exchanger was designed, the heat exchange area on both sides was specially different to meet the requirements of complex working conditions in view of the asymmetric flow heat exchange in the market This paper introduces the characteristics and application of secespol heat exchanger Compared with the traditional tubular heat exchange tube bundle, each heat exchange tube of secespol heat exchanger is uniformly wound in the shell with spiral structure according to certain rules On the one hand, this structure extends the length of the heat exchange tube and makes the heat exchange sufficient; on the other hand, it greatly changes the flow state of the fluid, enhances the turbulence effect and strengthens the heat transfer At the same time, the design of spiral wound elastic tube bundle can effectively eliminate the turbulent buffeting, thermal stress and other stresses of heat exchanger, and realize the stress self elimination Figure 1 is a partial section of the secespol heat exchanger 1.2 performance characteristics 1.2.1 heat exchange and energy saving The spiral tube heat exchanger has the reverse winding of the heat exchange tube between layers This unique winding structure design greatly changes the flow state of the fluid and forms a strong turbulence effect in the shell Due to the strengthening effect of the spiral flow in the tube, the heat transfer film coefficient of the tube side is also increased, and then the comprehensive heat transfer coefficient is improved Under the condition of steam water exchange such as steam heating water, the heat transfer coefficient K value of conventional shell and tube heat exchanger is generally 6000W / (㎡) ℃ The heat transfer coefficient K value of secespol heat exchanger can be as high as 14000W / (㎡· ℃), which is more than three times of that of conventional shell and tube heat exchanger Because of its unique spiral winding structure, the extended length of the heat exchange tube bundle is 4-6 times of the shell length When heating, the heat medium can stay in the heat exchange tube for a long time, and when condensing, the cooled medium can also be cooled more fully without secondary heat exchange, which ensures the full exchange of heat, improves the utilization rate of energy and saves energy There are three kinds of thread elastic pipes with the diameter of 8mm, 10 mm and 12 mm, and the wall thickness is only 0.6 mm 1.2.2 the unique 100 ° connection heat exchanger adopts 100 ° connection between the central axis of two flanges at the same end, which can make the heat exchanger fully participate in heat exchange without dead angle; make the fluid automatically wash the pipeline, reduce the blocking tendency, buffer the fluid and reduce the noise Because of its unique 100 ° connection and screw thread structure, unique surface treatment process and countercurrent heat exchange of the media on both sides, it has the characteristics of high flow rate (in the process of steam water heat exchange, the design flow rate on the water side of the shell side can be as high as 5.5m/s), small temperature gradient and small fouling coefficient In the design of internal structure, the allowable criteria of acoustic resonance (Eisinger criterion and Bevins criterion) are taken into account to effectively suppress the vibration of acoustic standing wave, Zui greatly reduces the operating noise, and the heat exchanger can operate in low noise state 1.2.3 the heat exchange tube bundle and shell of high temperature and high pressure secespol heat exchanger are all made of stainless steel, with uniform expansion coefficient, which will not cause the deformation of heat exchanger due to the instability of pressure and temperature The heat exchanger is resistant to high temperature and high pressure, and does not need to be equipped with temperature and pressure reducing device Zui has high temperature resistance of 400 ℃ and pressure resistance of 2.0MPa Based on the principle of Owen turbulence buffeting frequency criterion, the small gap design of Zui heat exchange tube bundle and spiral winding elastic tube bundle effectively eliminate the phenomenon of turbulence buffeting thermal stress and extend the service life of heat exchanger 1.2.4 the secespol heat exchanger has a compact structure and small volume spiral winding mode When it meets the same heat load conditions, the volume of the secespol heat exchanger is only about 1 / 10 of the traditional shell and tube heat exchanger, which occupies a small area and saves space At the same time, because of its small size and light weight, it is more convenient to install and disassemble, reducing the installation cost 1.2.5 low scaling tendency and convenient maintenance Because of the tube side winding design of the secespol heat exchanger, the fluid in the tube passes through in a spiral way, which reduces the possibility of wall adhesion and scaling tendency The reverse flow of the shell side fluid passes through the tube crosswise, which continuously separates and merges between adjacent tubes, layers and layers, strengthening the turbulence of the shell fluid, reducing the probability of sedimentation at the same flow rate, and ensuring the design Long cycle and high load operation of standby The fouling tendency of secespol heat exchanger is very low, but it doesn't mean that it doesn't scale Once scaling occurs, the equipment is relatively small and the cleaning is very simple Usually, chemical cleaning method is used, and the prepared low concentration dilute nitric acid is soaked for 2-3 hours, so the maintenance cost is very low Because of the advantages of advanced heat exchange technology, secespol heat exchanger is widely used in the field of solvent recovery and condensation of pharmaceutical raw materials
The application of dichloromethane in the process of atmospheric distillation in a large pharmaceutical factory in Northeast China: the secespol heat exchanger is used to cool down with 25 / 30 ℃ normal temperature circulating water, while the traditional heat exchanger needs to use two-stage condensation The motor power during the operation of the secespol heat exchanger is smaller than that of the traditional heat exchanger, because the use of two-stage condensation requires an additional motor and the cost of the refrigerator For one-time investment, one-time investment is reduced The application of toluene distillation process in a pharmaceutical group in Liaocheng, Shandong Province: the toluene steam of the original process is condensed and cooled from 110 ℃ to 45 ℃, using two-stage condensation, the heat exchange area of the first stage condenser is 42 ㎡, and the heat exchange area of the second stage cooler is 28 ㎡ After the secespol condenser is adopted, a jadx9.88 is selected, the heat exchange area is only 10.8m2, and the condensation temperature is 3 ℃ lower than the original process, and the actual toluene recovery rate is increased by 2% The volume of the heat exchanger is 1 / 20 of the original equipment, the equipment investment is reduced by 50%, and the installation cost is reduced by 80% Conclusion: secespol spiral wound tube heat exchanger is a kind of heat exchanger, which occupies a small area It can not only effectively reduce the investment in the new plant, especially in the reconstruction and expansion of the old plant, but also the compact spiral wound structure is more conducive to the plane layout of the equipment Spiral wound tube heat exchanger has the characteristics of sufficient heat exchange and small difference between cold and hot ends, which can not only save energy, but also optimize the system and process, with good energy saving effect.