The common faults of plate heat exchanger include liquid string, leakage, excessive pressure drop and heating temperature can not meet the requirements.

1、 Sluicing

1. Causes

① Due to the improper selection of the plate, the corrosion of the plate leads to cracks or perforation.

② The operation conditions did not meet the design requirements.

③ The residual stress after cold stamping and too small clamping size in assembly cause stress corrosion.

④ There is a slight leakage at the plate leakage groove, which causes the harmful substances in the medium to concentrate and corrode the plate, forming a string of liquid.

2 treatment method

① Replace the cracked or perforated plate, and find the plate crack with light transmission method on site.

② Adjust the operation parameters to meet the design conditions.

③ When the heat exchanger is repaired and assembled, the clamping size should meet the requirements, not the smaller the better.

④ Reasonable matching of plate materials.

2、 Leakage

1. Causes

① The clamping size is not in place, the size is not uniform (the size deviation should not be greater than 3 mm) or the clamping bolt is loose.

② Some of the gaskets are separated from the sealing groove, the main sealing surface of the gasket is dirty, the gasket is damaged or the gasket is aged.

③ Plate deformation, assembly dislocation caused pad running.

④ There are cracks in the plate sealing groove or the secondary sealing area.

2 treatment method

① In the non pressure state, re clamp the equipment according to the clamping size provided by the manufacturer, the size shall be uniform, and the deviation of the pressing size shall not be greater than ± 2 n (mm) (n is the total number of plates), and the parallelism between the two pressing plates should be kept within 2 mm.

② Mark the leakage part, then disassemble the heat exchanger, check and solve one by one, and reassemble or replace the gasket and plate.

③ Disassemble the heat exchanger and repair or replace the deformed plate. When there are no spare parts, the deformed parts can be temporarily removed and then reassembled.

④ When reassembling the disassembled plate, clean the plate surface to prevent dirt from adhering to the gasket sealing surface.

The pressure drop of the third stage is too large

1. Causes

① The pipeline of the running system is not cleaned normally, especially in the newly installed system, many dirt (such as welding slag, etc.) enter the inside of the plate heat exchanger. Due to the narrow cross-sectional area of the flow channel of the plate heat exchanger, the sediment and suspended solids in the heat exchanger gather in the corner hole and the diversion area, which leads to the large reduction of the flow channel area and the main pressure loss in this part.

② When the plate heat exchanger is selected for the first time, its area is too small, resulting in high flow velocity and high pressure drop between plates.

③ After the plate heat exchanger has been running for a period of time, the pressure drop is too large due to the scaling on the plate surface.

2 treatment method

① Clean the dirt or plate scaling in the flow channel of heat exchanger, and clean the new system once a week according to the actual situation.

② The secondary circulating water * * is soft water after softening treatment. Generally, the mass concentration of suspended solids in the water is not more than 5 mg / L, the diameter of impurities is not more than 3 mm, and the pH is not less than 7.

When the water temperature is not more than 95 ℃, the concentration of Ca and Mg should not be more than 2 mmol / L;

When the water temperature is higher than 95 ℃, the concentration of Ca and Mg should not be greater than 0.3 mmol / L, and the mass concentration of dissolved oxygen should not be greater than 0.1 mg / L.

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

Fourth, the heating temperature can not meet the requirements

1. Causes

① Insufficient medium flow in primary side leads to large temperature difference and low pressure drop in hot side.

② The cold side temperature is low, and the cold and hot end temperature is low.

③ The flow distribution of parallel plate heat exchangers is uneven.

④ The fouling inside the heat exchanger is serious.

2 treatment method

① Increase the flow of heat source or increase the diameter of heat medium pipeline.

② Balance the flow of multiple plate heat exchangers in parallel operation.

③ Remove the plate heat exchanger and clean the surface of the plate.