Changsha Box type Resistance Furnace (Efficient and Energy saving)

The principle of temperature automation control for Changsha box type resistance furnace (high-efficiency and energy-saving)

The temperature automation control of high temperature or laboratory resistance furnaces plays an important role in production, research and development, and laboratory scientific research. Based on the deviation of the furnace temperature from the given temperature, automatically turn on or off the heat source energy supplied to the furnace, or continuously change the size of the heat source energy to stabilize the furnace temperature within a given temperature range, in order to meet the needs of the heat treatment process.

The commonly used adjustment rules for temperature automatic control include two position, three position, proportional, proportional integral, and proportional integral derivative. High temperature electric furnace resistance furnace temperature control is a feedback regulation process that compares the actual furnace temperature and obtains a deviation from the required furnace temperature. By processing the deviation, a control signal is obtained to adjust the thermal power of the resistance furnace, thereby achieving temperature control. PID control, which generates control effects based on the proportion, integration, and differentiation of deviations, is a widely used form of control in process control.

The control program for high-temperature muffle furnace or laboratory resistance furnace system is designed using a dual interrupt nesting method. Firstly, generate a timed interrupt for the T0 counter as the sampling period for this system. Start A/D in the interrupt service program, read in sampled data, perform digital filtering, upper and lower limit alarm processing, PID calculation, and then output control pulse signals. The pulse width is determined by the T1 counter overflow interrupt. When waiting for T1 interruption, convert the current sampling value into the corresponding temperature value and put it into the display buffer, and then call the display subprogram. After returning from T1 interrupt, return to the main program from T0 interrupt and continue displaying the sampling temperature, waiting for the next T0 interrupt.

According to the operating conditions of the production site, this temperature control method has relatively high accuracy, stable system performance, and meets the actual needs of production. Main equipment of high-temperature electric furnace: thermocouple or thermistor, intelligent PID temperature controller, thyristor triggered power regulator, etc.

Main technical features:

The resistance furnace consumes heat energy converted from electrical energy. Part of it is dissipated into space due to various factors such as the construction materials and heat transfer of the electric furnace, while the other part is used to heat the workpieces inside the furnace. The first part forms the power loss of the electric furnace, while the latter part forms the effective power of the electric furnace.

When the electric furnace starts to heat up, the bricks inside the furnace absorb a large amount of heat to increase their own temperature. When the furnace is stopped and cooled down, this part of the heat is dissipated into the space; This part forms the heat storage loss of the furnace body. An electric furnace should have low empty furnace loss and high effective power. Less heat storage loss. The size of empty furnace loss is an important indicator for measuring the efficiency of electric furnaces. Electric furnaces with small empty furnace loss can achieve high technical productivity and low unit energy consumption ratio. The efficiency of general industrial resistance furnaces. Small electric furnaces have lower efficiency, while large electric furnaces have higher efficiency. Box type electric furnaces ranging from 10-100 kW have an efficiency of about 65-85%, and empty furnace losses account for about 35-15% of the total power. The time it takes for a high-temperature electric furnace to rise from room temperature to operating temperature has a significant impact on the economic indicators of the furnace. If the heating time is short, the furnace will be put into normal use for a longer period of time, resulting in higher daily productivity and lower electricity consumption per kilogram of workpiece. Therefore, it is recommended to use lining materials with low thermal inertia and reduce the heat storage capacity of the furnace body to accelerate the heating rate of the electric furnace. The heat storage capacity of the furnace body has a great impact on the periodic operation of the furnace, especially for electric furnaces produced in one or two shifts per day.

The impact on continuous operation furnaces is not significant. Heating capacity is the main technical indicator of an electric furnace. Heating capacity refers to the effective power of the electric furnace, which theoretically calculates the weight of the material that can be heated to the rated temperature within one hour, calculated in kilograms per hour.

Specification parameters:

Furnace specifications:

Changsha Box type Resistance Furnace (Efficient and Energy saving)Special furnace dimensions can be customized according to customer requirements!

The correct operation process of high-temperature box type resistance furnace

The specific process operation of the box type resistance furnace is as follows:

1. Check the "shift handover record" before starting work.

2. Operators should wear the prescribed protective equipment and be familiar with the "safety operating procedures".

3. Check the lubrication condition of the axle and slide rail of the furnace door opening mechanism.

4. Check the installation and fastening of the furnace lining, resistance wire, and thermocouple lead out rod, and verify if the instruments are functioning properly.

5. Check that the resistance wires at the bottom of the furnace, the bottom plate of the furnace, the transmission mechanism of the movable furnace bottom, and the motor lead wires are in good condition.

6. Check the cleanliness of the furnace and clean the oxide scale.

7. Newly repaired furnaces should be dried according to the "process specifications".

8. Cut off the power and proceed with the baking process according to the "process specifications".

9. Close the door of the box type resistance furnace.

10. Insulate according to the "process regulations".

11. Power on heating.

12. Cut off the power after work.

13. Produce the furnace according to the "process specifications".

14. Reinstall the furnace and repeat the above procedure.

When the box type resistance furnace is operated continuously, the "handover record" must be carefully filled out, and the handover must be clearly handed over to the successor in person.

16. Maintain and upkeep the equipment according to the "Equipment Maintenance Regulations".