Because of the high price of titanium, the heat exchange tube in the traditional packed-box titanium tube heat exchanger is made of titanium, and the tube plate is made of titanium steel composite plate. Due to the non-weldability of titanium and steel, it is more difficult to manufacture titanium tube heat exchangers, so the tube boxes of stuffing box heat exchangers usually do not use titanium steel composite plates, but carbon steel or low alloy steel tube boxes. The overall rubber lining solution saves cost and reduces machining difficulty. In order to reduce the manufacturing cost and the difficulty of machining and manufacturing, in the traditional design scheme of the stuffing box titanium tube heat exchanger, all parts that are not in contact with seawater are not made of materials, so the tube sheet skirt at the floating tube sheet of the heat exchanger Carbon steel is usually used, which can avoid the welding of titanium and carbon steel, and reduce costs. Although the structural design of the traditional stuffed box titanium tube heat exchanger reduces the cost and manufacturing difficulty, it also brings serious equipment leakage problems.
At present, the most common leakage phenomenon occurs in the sealing leakage at the floating tube sheet. According to user feedback, the traditional structure of the packed box titanium tube heat exchanger has severe corrosion at the floating tube sheet. The reason for the analysis is mainly due to the fact that the carbon steel part of the floating tube sheet is exposed outside the filler during the compaction of the filler. There is a gap between the floating tube sheet and the inserted tube box at the seal. The contact caused rapid corrosion of the place by seawater, which directly caused heat exchanger leakage, and carbon steel was extremely resistant to seawater corrosion. Some data show that when the seawater is in direct contact with carbon steel, the carbon steel part of the floating tube sheet will be corroded in a very short time. In severe cases, only the thin titanium part remains in the corroded area. Once the above leakage occurs, it is difficult to repair, even if the equipment can be found in the early stage of repair and maintenance, and the repaired welding can be repaired, but due to various conditions and metal welding characteristics, after repair The operation of the equipment will again cause large-scale corrosion in a short time, and the equipment will be at risk of leakage at any time. Once the stuffed box type titanium tube heat exchanger is corroded and leaked due to the carbon steel part, in order to eradicate the danger, the equipment must be replaced.
Another common leak is caused by the rupture of the titanium tube, and the rupture of the titanium tube is usually caused by scratches or bumps on the heat exchange tube. Because titanium is expensive, in order to reduce costs, the wall thickness of the heat exchange tube selected for the titanium tube heat exchanger is usually thin, generally about 0.5mm. In such leakage cases, it is often found that there are a lot of large particles of sand and even shells in the heat exchanger tube box. The reason for analysis is mainly that in actual use, seawater containing a large amount of debris does not Stopping the flow, it is easy to cause scratches or wear on the titanium tube. In addition to affecting the heat exchange effect, the life of the heat exchanger is also greatly reduced, making the extremely thin titanium tube rupture prematurely, causing leakage. Due to structural reasons and difficult to clean up and other environmental conditions, repairing by repair welding is more difficult, and the leakage problem can only be solved by sealing the leakage pipe nozzle, which seriously affects the heat exchange effect of the heat exchanger.
The third common leak is mainly caused by problems at the joint between the titanium tube joint and the tube sheet. The main cause of this type of leak is caused by welding quality problems or damage to the tube joint caused by vibration of the heat exchange tube, and its repair is very difficult.
In actual use, titanium welding deformation is large, and it is difficult to correct the shape, especially when it is cold-processed, it is prone to cracks; when bending deformation, the elastic rebound is large, and it is not easy to get the correct shape. Deformation speed is intensified, and the deformation speed has a great influence on the limit degree and quality of the processed parts. Because titanium has many defects, titanium equipment is more unfavorable for rework, and sometimes even more rework, and the actual effect is worse. In view of these characteristics of titanium, in order to ensure its technological performance, the technical requirements for titanium equipment are extremely strict. In addition to the requirements for the composition, manufacturing, assembly, and testing methods of raw materials, it also proposes according to the type of titanium equipment. Special manufacturing requirements, and strictly follow the manufacturing process regulations for machining and manufacturing.
