Spiral plate heat exchangers come in two types: detachable and non-detachable. The structure of the non-detachable spiral plate heat exchanger is relatively simple, with both ends of the spiral channel welded shut. The detachable spiral plate heat exchanger, except for the sealing structure at both ends of the spiral channel, is identical to the non-detachable type. To facilitate mechanical cleaning, the detachable spiral channel is open at one end and sealed with a flat cover and gasket to prevent fluid leakage into the atmosphere or fluid short-circuiting within the same channel. To enhance the pressure-bearing capacity of the spiral plate, a spacer column is used to support the plates. The fluid inlet and outlet on the cylinder body include normal and tangential nozzles. Tangential nozzles are commonly used in China due to their low fluid resistance and ease of flushing out impurities. The use of a rotary support is convenient, allowing the heat exchanger to be placed vertically or horizontally. The A and B fluids for heat exchange flow through both sides of the spiral plate, with one fluid flowing from the outside inward along the spiral channel and exiting through the central outlet, while the other fluid flows from the central inlet along the spiral channel and exits from the inside out. The two fluids flow in a pure countercurrent manner. The structural dimensions of the spiral plate heat exchanger are: plate width of 1800 mm, outer diameter of 1700 mm, heat transfer area of 250 m², and distance between plates of 20 mm. The allowable operating pressure can reach 2.5 MPa. The working temperature depends on the selected material, which mostly includes carbon steel, stainless steel, aluminum, copper, and titanium
In China, the shift heat exchangers and the heat exchangers at the bottom of the synthesis tower in small and medium-sized synthetic ammonia plants have been successively replaced by spiral plate heat exchangers instead of shell-and-tube heat exchangers. For the electrolyte heaters and concentrated alkali coolers in caustic soda plants, the equipment cost of using spiral plate heat exchangers is only one-third of that of shell-and-tube heat exchangers. Furthermore, this type of heat exchanger exhibits excellent performance in tower top condensation, quenching oil cooling, fuming sulfuric acid cooling, and fatty acid cooling. This equipment is effective for steam condensation and convective heat transfer without phase change, and can also be used for boiling heat transfer