Shell and tube type (also called tubular heat exchanger) is a shell and tube heat exchanger mainly comprises a shell, tube and tube plate and the head part, the shell is round, with internal parallel tube or spiral pipe, tube fixed at both ends of the tube plate. In the shell and tube heat exchanger for heat transfer of two kinds of fluid, a kind of flow in the tube, the stroke is called the tube; a tube outside the flow, the stroke is called the shell. The heat transfer surface is the wall of the tube bundle. Different models of the pipe, the process is generally 16mm 20mm diameter or 25mm three models, pipe wall thickness is generally 1mm, 1.5mm, 2mm and 2.5mm. Imported heat exchanger, the minimum diameter of 8mm, wall thickness is only 0.6mm. Greatly improve the efficiency of heat transfer, in 2012 also gradually spread in the domestic market. Shell and tube heat exchanger, spiral tube design, can maximize the increase of turbulence effect, increase the heat transfer efficiency. The asymmetry of inner shell and tube can reach 4.6 times. It is widely used in the field of steam water heat exchanger. The maximum heat transfer efficiency can reach 14000w/m2.k, greatly improve production efficiency and save cost. At the same time, because of shell and tube heat exchanger for metal structure, with the launch of the new version of GMP China, 316L stainless steel heat exchanger as the main body, will become the beverage, food, and pharmaceutical industry required.
The structure and characteristics of the existing equipment at present, the heat exchanger station in atmospheric tower on the use of oil and gas aluminizing, coating, chemical plating, dual phase steel and special materials and technology to solve the petrochemical equipment heat exchanger corrosion problem, but often because of difficult processing, welding or material prices are too expensive and not in the device extension use. The characteristics of good corrosion resistance by using titanium material, the comprehensive advantages of plate heat exchanger has high heat transfer efficiency, compact structure and safe and reliable, can solve the corrosion problem of gas oil gas heat exchanger, greatly reduce the frequency of replacement of equipment, reduce equipment operating and maintenance costs, ensure long period safe and reliable operation of equipment. Titanium plate heat exchanger with corrugated plate of titanium sheet forming as the heat transfer element, and the plates are assembled together by welding.
In recent years, the domestic heat exchanger tube is used for atmospheric tower top oil and gas heat exchanger, but the life is still only about 3 months. However, due to the thermal expansion problems caused by the temperature change, the ceramic coating has caused the ceramic layer to burst and fall off. Therefore, many domestic manufacturers have to use titanium tube heat exchanger to solve the corrosion problem to ensure the long term operation of the unit, but the use of titanium tube expensive, only one station on the atmospheric tower titanium plate shell heat exchanger structure and characteristics of titanium plate heat exchanger is a new type of heat exchanger in plate exchanger the heat exchanger shell and tube exchangers merits.soon, using titanium sheet as heat transfer components, the shape of shell and tube type heat exchanger is similar. The oil and gas heat exchanger at the top of the tower is in the bad environment, and the gas and liquid phase change is still in operation. When using carbon steel as a heat exchanger material, under the action of uniform corrosion in the heat exchanger tube quickly corrode and leak, if the 304 and 316 austenitic stainless steel as a heat exchanger material, often due to chloride induced stress corrosion cracking, and lower equipment life, frequent replacement of equipment for long period production and the economic benefit of refineries caused huge losses, this problem has become one of the difficult problems in the atmospheric and vacuum distillation unit.