Air duct heater leakage solution

Duct heater leaks primarily manifest in two ways: at the tube ends and within the tubes themselves.

1. Tube End Leakage

Cause 1: Excessive Thermal Stress

During the duct heater's startup and shutdown processes, if the temperature rise and fall rates exceed the specified range, thermal stress in the tubes and plate can increase, leading to damage at welds or expansion joints and causing end leaks.

Cause 2: Tubesheet Deformation

If the tubesheet is deformed, leakage can occur when it connects to the tubes. Insufficient tubesheet thickness is one cause of tubesheet deformation.

What controls the heating rate of the duct heater?

This depends on the heater's structure. A frequency converter can only change the frequency of the AC power, thereby changing the motor's rotational speed and thus the motor's output power. Since the heater does not rotate, a frequency converter cannot control the heating rate.

There are two simple methods:

1. Use diode half-wave rectification to change the effective value of the AC power, thereby varying the heating power and heating rate. This method is the most commonly used and has the advantages of a simple circuit structure and easy operation.

2. Voltage transformation: Use a small transformer for voltage transformation. The advantage is that it can be adjusted in multiple gears. The disadvantage is that the circuit structure is more complicated and the production cost is high.