Detailed introduction
　　Tube-and-tube heat exchangers (shell-and-tube heat exchangers) are the most common type of heat exchangers. They are widely used in food, chemical, pharmaceutical, petroleum and other industries, and are a kind of general equipment. Tube heat exchanger (shell and tube heat exchanger) is mainly composed of shell, tube sheet, heat exchange tube, head, baffle and so on. Tube heat exchangers (shell and tube heat exchangers) are made of ordinary carbon steel, copper, or stainless steel. The most commonly used tubular heat exchangers are made of stainless steel, such as stainless steel heat exchangers, stainless steel condensers and stainless steel coolers. Fixed tubesheet heat exchanger is the most commonly used tubesheet heat exchanger.