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Failure and repair of graphite heat exchanger
- 2020-01-14-

Graphite heat exchangerThere are two types: block hole type and shell and tube type. The main disadvantage of the block-hole graphite heat exchanger is that once a leak occurs, it is difficult to find and repair. The disadvantage of the shell-and-tube graphite heat exchanger is that the strength of the graphite tube is relatively low, and the steam pressure used cannot exceed 0.15MPa; the flow rate of the heated medium is low and can only be controlled at 2~3m/s; the temperature difference between the inlet and outlet can only be controlled at 2~4℃, the heat exchanger has a large volume.

During use, if improper use will cause the tube to break or the bonding seam leaks, Golden Triangle Graphite Equipment Manufacturing Co., Ltd. analyzes the reasons for the following 4 points: 1. Excessive force during the cleaning process causes damage to the tube. 2. When the system heats up, Because the heating rate is too large, the shell side pressure of the graphite heat exchanger will rise sharply, and the graphite tube will be broken by the impact. 3. Uneven heating of graphite heat exchanger tubes. 4. Due to the increase in the use time of graphite heat exchangers, some fouling will occur on the tubes. The expansion coefficient of fouled graphite heat exchange tubes and unscaled graphite heat exchange tubes is different, and the temperature difference stress is overloaded, causing graphite The heat exchange tube is broken.

For this reason, Golden Triangle Graphite has developed a method for plugging the graphite tube.

1. Expansion plug blocking method-1# expansion plug made of 316L machined bolts, nuts and large washers. After checking the leakage point, plug it with 1# expansion plug from both ends, tighten the nut to deform the rubber sleeve, and the middle bulge is tightly integrated with the pipe wall to achieve the purpose of plugging. The advantages of this method are fast, time-saving and labor-saving. But the service life is generally not more than half a year.

2. Pipe thread plugging method-use a tap to machine the thread on the inner wall of the damaged graphite tube, and then use a threaded

The patterned graphite plug is coated with acid-resistant cement to plug it. The tap is best to use pipe thread. The material of the stopper can be metal or non-metal, but due to the different expansion coefficients of metal and graphite tube, graphite material is better. Because graphite is relatively brittle, special care must be taken when processing the plug. The graphite used for processing the plug must have a sufficiently high carbon content. It is best to use impermeable graphite pipe thread plugs to plug the holes in the tube plate at both ends of the damaged graphite tube. As this method is difficult to implement, it must be operated by experienced construction personnel. After construction, the cement can be put into use after it is completely cured.

3. Double plug clogging method-at both ends of the fixed tube sheet and the sliding tube sheet where the damaged tube is checked, two graphite plugs are used to plug each end with glue to block it. This method takes a long time and takes about 12 hours from completion to use. This is a more thorough and long-life method. This method does not have high requirements for plugs, and can be processed with general carbon bricks, or even with third-grade carbon bricks with a carbon content of 80%, and the processing is simple, with a success rate of 100%.