This heat exchanger is composed by several individual pieces of hot tubes. The number of hot tubes depends on the heat transfer area. To improve the heat transfer coefficient of air, fins are usually installed at the outside of the tube, and this can greatly reduce the required number of hot tubes.

Hot tube heat exchanger is mainly composed by shell, hot tube element, inlet and outlet interfaces of cold and hot fluids. The shell is a steel structure. One side of it is the channel of hot fluid, and the other side is the channel of cold fluid, which are separated by tube plate. Thermal insulation layer is installed between the cover plate and the upper and lower orifice plates on the shell.

Its characteristics are:

① The equipment resistance can be reduced by using hot tube heat exchanger;

② Long service life: firstly, this equipment is composed by hundreds of hot tubes. Each tube is working independently. The influence to the effect of the entire heat exchanger by the damaging of one or several hot tubes is very small; secondly, the hot tube is fixed on the tube plate, this can avoid the fatigue stress damage caused by thermal expansion and cold contraction;

③ Completely solving the leaking problem: each piece of hot tube is independent enclosed unit. Cold and hot fluids are outside the tube. The cold and hot fluids are separated by sealing plate. Even if one end of the tube is eaten through, this will only fail this hot tube, and the other end of the tube is good, which effectively avoids the mixing of cold and hot fluids and completely solves the leaking problem. It is safe and reliable.

④ Reducing the dew point corrosion: the wall temperature of each piece of hot tube is different. So a considerable number of heat tubes are working above the acid dew point. If the wall temperature is 1℃ more than the acid dew point, the dew point corrosion can be avoided. Furthermore, the hot tube preheater can adjust the temperature of tube wall by changing the heat exchange area at the cold and hot ends, so the maximum corrosion area can be avoided.

⑤ Reducing dust deposition and clogging, and solving the dust clogging problem: hot tube preheater avoids the dew point and the tube wall will not condensate, which greatly reduce the adhesive force of dust. Moreover, the heat exchanger can be designed into variable section structure which can guarantee the equal speed flow of fluid at the inlet and outlet, and achieve the purpose of self-dust cleaning. 

⑥ The installation of fins can make up the disadvantages of low heat exchange coefficient of common air-air heat exchanger, increase the heat transfer area, improve the heat transfer effect, and effectively recover low temperature wasted heat.

 

Our professional Chinese translators translated the material about Characteristics of Integral Hot Tube Heat Exchanger.

 

该换热器是由许多单根热管组成。热管数量的多少取决于换热面积的大小。为了提高气体的换热系数，往往采取在管外加翅片的方法，这样可使所需要的热管数目大大减少。

热管式换热器主要是由壳体、热管元件及冷、热流体进出接口组成。壳体是一个钢结构件，一侧为热流体通道，另一侧为冷流体通道，中间由管板分隔。壳体的上、下孔板与盖板间设有保温层。

其特点为：

①、使用热管换热器可以降低设备阻力低；

②、使用寿命长：一是本设备由数百根热管组成，热管单管作业，有一根或部分热管损坏，对整体换热器效果影响也可忽略不计；二是热管单支固定于管板上，避免由热胀冷缩造成的疲劳应力破损；

③、彻底解决泄漏问题：由于每根热管都是相对独立的封闭单元，冷、热流体都在管外，并由中间密封板严密的将冷、热流体隔开，即使管子一端被腐蚀穿，只能使该热管失效，而管子另一端是完好的，有效地避免冷、热流体的串流，彻底解决泄漏问题，使用起来安全可靠。

④、减轻露点腐蚀：每一根热管的壁温是一个值，这就使相当一批热管在酸露点以上工作，当壁温比酸露点高1℃以上时，就可以避免露点腐蚀，而且热管预热器可以改变冷热端换热面积来调整管壁温，避开最大腐蚀区。

⑤、减轻积灰、堵灰及解决灰堵问题：热管预热器避开了露点，管壁不结露，就大大减少了灰的附着力，而且换热器设计可采用变截面结构，保证流体进出口等流速流动，达到自清灰的目的。

⑥、可以翅片化，弥补一般气—气换热器换热系数低的弱点，增大传热面积，提高换热效果好，能有效的回收低温余热。

原件下载：