Heating principle and control points of electric heater

The Joule effect of electricity is used to convert electric energy into heat energy to heat objects. They are usually divided into direct resistance heating and direct resistance heating. The supply voltage of the former is applied directly to the heated object, and when the current current is expired, the heated object is electrically heated by itself, and the ironing machine is heated. An object that can be heated by direct resistance is a conductor, but with a higher resistivity. Because the heat occurs in the heated object itself, due to internal heating, heat efficiency is very high. The direct resistance heating shall be made of special alloy material or nonmetallic material. The heating element will generate heat energy by heating element, and then be transmitted to the heated object through radiation, convection and conduction. Because the heated object and the heating element are divided into two parts, the variety of the heated object is usually unconstrained and the operation is concise.

The materials used for heating elements of direct resistance heating are usually high resistivity and small resistance temperature coefficient. They are small in deformation and difficult to be brittle at high temperature. Commonly used are iron aluminum alloy, nickel chromium alloy and other metal materials and silicon carbide, two, molybdenum and other non-metallic materials. The maximum working temperature of the metal heating element can be up to 1000~1500 degrees according to the data, and the maximum operating temperature of the non-metal heating element is up to 1500~1700 DEG C. The equipment facilities, heat furnace replacement, but it needs work pressure regulating equipment life than alloy heating element is short, usually used in high temperature furnace, the temperature data beyond the metal heating element of the highest operation temperature and promised to local some special occasions.

The electric heater control system in detail key:

1) electric heater for resistive heating, the appearance of mode is a flange type electric heater.

2) electric heater is composed of two series horizontal heater device, device for support leg device, select "delta" connection.

3) after heating the electric heater, it heats up, then heats the active medium in the container and causes the medium to reach the set temperature at the exit.

4) by electric heater temperature control meter ST1 temperature control, ST1 temperature collection export signal, by PID control, adjustable power output signal 4-20mA SCR trigger module, output power and control heater, stepless power to complete the output of 0-400kW.

5) internal temperature alarm appearance ST2 detection heater 6 temperature, when the flow rate is too low or no flow and other reasons, the heater showed dry conditions, at any point within the temperature beyond the surface within the temperature setting value control circuit and alarm lock, with alarm lamp. After that, it is necessary to manually reset the heater before restarting.

6) the system is equipped with pressure alarm chain system. The operation of the control cabinet is linked with the system pressure of the user. The interlocking signal is supplied by DCS, and the heater is allowed to start as long as the medium pressure is normal.

7) during the operation of the heater, the heater will be cut off and the alarm signal will go to DCS when the SCR is over heated due to the over temperature of the thyristor.

8) the body system is provided with a plurality of chains, which can be used in conjunction with other equipment, and the short connection is not necessary.