What are the structural features of the stripper lining in a urea plant?

The structure of the urea stripping tower differs from that of the synthesis tower; only the high-pressure tube sheet, tube bank, and spherical head are lined. The main types of linings include loose lining, explosive composite lining, and surfacing lining. The materials for the lining are mainly 316L stainless steel and industrial pure titanium. For current applications, stripping towers are mostly lined with explosive lining. Although mechanically loose linings are convenient for leak detection, their manufacturing process is complex, their fit is poor, and they cannot withstand large fluctuations in temperature and pressure. Although cladded linings can withstand large fluctuations in temperature and pressure, their fabrication requires specialized welding equipment and a large amount of expensive welding materials, resulting in high costs. Moreover, these linings cannot be tested for leaks, which is why they are used less frequently. Although the manufacturing quality of burst-proof composite linings is difficult to control and leak detection is challenging, they offer good fit and lower production costs, which is why they are widely used. The stripping towers adopted in the CO2 stripping process are equipped with a 8 mm thick explosive-type 316L stainless steel lining, while the NH3 stripping towers mostly have a 5 mm thick explosive-type titanium lining. For the surfacing of pure austenitic stainless steel linings, the surfacing layer should have a thickness of at least 3 mm to meet the requirements for corrosion resistance. Lining leak detection tubes are generally installed on the upper and lower sides of the welds; their purpose is to conduct leak checks during manufacturing and maintenance, as well as to monitor for leaks in the equipment during production.