Treatment Method For Internal Leakage Of Spiral Plate Heat Exchanger

Treatment method for internal leakage of spiral plate heat exchanger:

The spiral plate heat exchanger is composed of two closed and independent spiral channels, and it is difficult to determine the point of leakage if there is leakage in the channel. In order to find out the leakage point accurately, the method of drilling is adopted. When drilling, the drilling position should be set on the same spiral channel at one end of the heat exchanger, and it should be arranged in a cross shape. When drilling, it should also try to prevent iron filings from falling into the heat exchanger so that the The passage is clear.

Irrigation pressure leak detection method:

Use a pressure water pump to pour water into the heat exchanger from a channel that has not been drilled, and form a certain pressure. At this time, water will emerge from the position where the heat exchanger leaks and flow to another channel (the hole that is drilled) channel), and drip water from the hole closest to the leak point (at this time, the end of the heat exchanger drilled through the hole should be placed downwards), and the position of the dripping water can be used to determine which layer If there is internal leakage, then cut a section of the undrilled side head of the same layer of the heat exchanger as an observation hole, and the specific leakage point can be accurately determined from the observation hole.

Repair of internal leakage:

1. Hole digging: After determining the position of the internal leakage point, start cutting the hole from the place corresponding to the leakage point on the outermost layer of the heat exchanger. The order is from the outside to the inside, until the layer with the internal leakage point is cut. until. The hole cut out should be elliptical, and the size of the outer layer should be larger and gradually smaller towards the inside. Generally, the size of the holes on each layer differs by 40mm. If the location of the leak point is deep, the hole cut out on the outer layer should be larger. .

2. Slag cleaning: After cutting the holes, the oxidation slag left on each layer of the board should be carefully cleaned. This is the key to whether the back-up board and each layer of the spiral board can be welded tightly when welding the back-up board. The key is to use a chisel and a small hand grinding wheel for trimming the mold to clean the oxidized slag, and pay attention to remove the cleaned slag as much as possible to prevent it from falling into the heat exchanger.

3. Replacement board: In order to ensure the quality of the repair, the sheets cut from each layer of the heat exchanger are no longer used, and the replacement board is reassembled. The additional repair board should be used with the heat exchanger spiral plate For the same material and plate thickness, its periphery should be 15mm to 20mm larger than the holes cut on each layer of the heat exchanger, and it should also be elliptical, and it should be made into an arc consistent with the arc of each layer of the heat exchanger. .

4. Welding internal leaks and repair boards:

1) When welding internal leaks, carefully check whether the leaks are cracks or sand holes. If necessary, use a hand grinding wheel to clean the leaks and grind out grooves to ensure welding quality.

2) J422 electrode is used for welding repair, the diameter of the electrode is 3.2mm, and the current is controlled between 100-120A. Weld the leak point first and then weld each layer of repaired board, and weld layer by layer from the inside to the outside.

3) The elliptical patching plate is welded close to the inner arc surface of the heat exchanger, and its purpose is "to facilitate operation and ensure welding quality".

4) In order to make the elliptical back-up plate fit into the heat exchanger smoothly, a section of round steel can be welded on the back-up plate, and the oval back-up plate can be spot-welded before removing it.

5) Short round steel braces are welded between each layer of back-up plates (mainly to increase the mutual stiffness of elliptical back-up plates). The number of short round steel braces to be welded on each repaired board is determined by the size of the repaired board. Generally, 23 pieces are welded on the repaired boards of the outer layers, and 1~ 2.

6) *Because the outer steel plate is δ12mm thick, the original cut steel plate can be directly installed in the original position for alignment and welding.

7) It should be done during welding. After welding each layer of elliptical repair boards, the welding position should be carefully checked. If there are blisters, repair welding should be carried out to ensure the welding quality of each layer.

Pressure test and plugging the borehole:

After the inner leakage point and the back-up plate are welded, use a pressure water pump to fill the channel with the last drilled hole, and form a pressure of 0.5-1.0MPa, and keep it for a certain period of time, and there should be no pressure relief. Plugging the drilled hole: it is used to drill short round steel sections with the same diameter, plugging and welding the position of the drilled hole and the observation hole, and then conduct a hydraulic pressure test on the passage, the pressure is 0.51. No leakage occurred. Matters needing attention in the pressure test process: 1) Before cutting holes in the heat exchanger, use steam to blow off the chemical substances remaining in the heat exchanger to avoid burning during gas cutting and safety accidents. 2) Before repairing the heat exchanger, it should be confirmed whether it is severely corroded, and whether it is necessary to repair it.