The stainless steel plate heat exchanger is composed of many stamped stainless steel sheets, which are combined by a guide rod and the pressing devices at both ends through a sealing washer. The number of plates in the middle can be adjusted arbitrarily according to the production conditions. The cold and hot fluids convect each other on both sides of the thin-walled heat transfer plates to exchange heat. Plate heat exchangers are ideal equipment for liquid-liquid and liquid-vapor heat exchange. It has the characteristics of high heat exchange efficiency, small heat loss, compact and lightweight structure, small footprint, easy installation and cleaning, wide application and long service life.The effectiveness of the cleaning agent should be regularly checked during the cycle of the plate heat exchanger, which can be measured using PH test paper. If the solution is maintained at a pH of 2 to 3, then the cleaning agent is still effective. If the PH value of the cleaning agent reaches 5-6, it is necessary to add an appropriate amount of cleaning agent. The PH value of the final solution remained unchanged for 30 minutes at 2-3 hours, proving that the cleaning effect was achieved. The cleaning agent can be recycled and reused, and the discharge will cause waste.