Large plate heat exchanger

Clean the dirt or plate scaling in the heat exchanger channel of the plate heat exchanger. For the newly operated system, clean it once a week according to the actual situation. When cleaning the scale (mainly CaCO3) on the surface of the plate, select 0.3 aminosulfonic acid solution or 0.8 nitric acid solution containing 0.3 Urotropine, 0.2 aniline and 0.1 potassium thiocyanate as the cleaning solution, and the cleaning temperature is 40 ~ 60 ℃. When the equipment is not disassembled for chemical immersion cleaning, open the cold medium inlet and outlet of the heat exchanger, or install DN25 cleaning ports on the medium inlet and outlet nozzles when installing the equipment, inject the prepared cleaning solution into the equipment, and clean the residual acid with clean water after immersion to make the pH ≥ 7. When disassembling and cleaning, soak the plate in the cleaning solution for 30 min, then gently brush the scaling with a soft brush, and clean it with clean water after Zui. Avoid damaging the plate and rubber pad during cleaning. If the mechanical backwashing method without disassembly is adopted, a pipe orifice shall be connected to the medium inlet and outlet pipelines in advance, the equipment shall be connected with the mechanical cleaning vehicle, the cleaning solution shall be injected into the equipment in the opposite direction of medium flow, the circulating cleaning time shall be 10 ~ 15 min, and the medium flow rate shall be controlled at 0.05 ~ 0.15 M / s. After Zui, clean water shall be recycled several times to control the mass concentration of CL in clean water below 25 mg / I.

② The secondary circulating water Zui is better to use the soft water after softening treatment. Generally, the mass concentration of suspended solids in the water shall not be greater than 5 mg / L, the diameter of impurities shall not be greater than 3 mm, and the pH shall not be greater than 7. When the water temperature is not greater than 95 ℃, the concentration of Ca and Mg shall not be greater than 2 mmol / L; When the water temperature is greater than 95 ℃, the concentration of Ca and Mg shall not be greater than 0.3 mmol / L and the mass concentration of dissolved oxygen shall not be greater than 0.1 mg / L.

③ For the central heating system, the method of primary to secondary water replenishment can be adopted.

The heating temperature cannot meet the requirements

Causes: ① insufficient medium flow at the primary side leads to large temperature difference and small pressure drop at the hot side. ② The cold side temperature is low, and the cold and hot end temperatures are low. ③ The flow distribution of multiple plate heat exchangers operating in parallel is uneven. ④ The scale inside the heat exchanger is serious.

Treatment methods: ① increase the flow of heat source or increase the diameter of heat source medium pipeline. ② Balance the flow of multiple plate heat exchangers operating in parallel. ③ Disassemble the plate heat exchanger and clean the scaling on the plate surface.