Design and application of the hottest fully automa

2022-08-18
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Design and application of fully automatic aging furnace

requirements of fully automatic aging furnace: vigorously develop the technology of plastic granulator using renewable energy and industrial waste heat. The furnace temperature is automatically controlled, dynamically recorded and simulated with the annealing process curve of castings; The maximum service temperature in the furnace is 1000 ℃, the temperature in the furnace is evenly distributed, and the arrangement of temperature measuring points is reasonable, which can accurately reflect the temperature distribution of the furnace, and the temperature difference of temperature measuring points is less than 25 ℃; Realize the automatic control of industrial computer and fully automatic firing; The effective loading volume in the furnace shall not be less than 25 m3, and the single furnace aging casting shall be 30 t. Confirm that the fuel is liquefied gas. The furnace type is designed as a flat top trolley furnace, which can improve the effective loading volume. High speed gas burner and distributed automatic control system are selected to ensure uniform furnace temperature. The door of the aging furnace is designed as a side pull door

1 structural characteristics of furnace body

the traditional arch structure furnace body has small effective loading volume, large heat storage loss, low heat utilization rate, difficult construction and high cost, which can no longer meet the requirements of the new furnace body. In this design, on the basis of digestion and introduction, the suspended light-weight flat roof and anchored light-weight thin-walled wall are designed, as shown in Figure 1. Because the high-strength light brick has good thermal shock resistance and heat insulation performance, it reduces the heat storage loss of the kiln body, facilitates temperature rise, and improves the heat utilization rate and loading space of the furnace

requirements for full-automatic aging furnace: furnace temperature follows the annealing process curve of castings, automatic control, dynamic recording, simulation display; The maximum service temperature in the furnace is 1000 ℃, the temperature in the furnace is evenly distributed, and the arrangement of temperature measuring points is reasonable, which can accurately reflect the temperature distribution of the furnace, and the temperature difference of temperature measuring points is less than 25 ℃; Realize the automatic control of industrial computer, and automatically measure the automatic firing at the beginning of pressing it all; The effective loading volume in the furnace shall not be less than 25 m3, and the single furnace aging casting shall be 30 t. Confirm that the fuel is liquefied gas. The furnace type is designed as a flat top trolley furnace, which can improve the effective loading volume. High speed gas burner and distributed automatic control system are selected to ensure uniform furnace temperature. The door of the aging furnace is designed as a side pull door

1 structural characteristics of furnace body

the traditional arch structure furnace body has small effective loading volume, large heat storage loss, low heat utilization rate, difficult construction and high cost, which can no longer meet the requirements of the new furnace body. In this design, on the basis of digestion and introduction, the suspended light-weight flat roof and anchored light-weight thin-walled wall are designed, as shown in Figure 1. Because the high-strength light brick has good thermal shock resistance and heat insulation performance, it reduces the heat storage loss of the kiln body, facilitates temperature rise, and improves the heat utilization rate and loading space of the furnace

Figure 2 the frame of control system of industry control computers

Fig.2 the frame of control system of industry control computers

since liquefied gas is used as the heating source of aging furnace, its safe operation is very important. The monitoring and control of combustion state are considered in the design, that is, the actual flame condition is monitored through the flame to the control system, and the normal or abnormal combustion is output through logical analysis. In case of abnormal conditions, the system will automatically shut off the gas and send out the flameout alarm audible and visual signal to ensure the safe and reliable operation of the system

the distributed control system composed of 486 industrial control computers and intelligent instruments is used to complete the whole process control of the temperature curve and kiln pressure of the aging furnace. The undertaking unit: made by Hunan Academy of Forestry Sciences, and its main functions are:

(1) preparation and modification of the aging curve

(2) real time tracking curve of aging temperature

(3) real time temperature display and advertising window in each area

(4) dynamic window of aging furnace operation process

(5) real time control of temperature at each point (area)

(6) movement state of air and gas valves at each point (area)

(7) automatic - manual switching

(8) process data management

(9) process data and curve printing

2.2 system software

the software of this system is a multi task real-time control software compiled under Windows environment. The software generates the functional block diagram of phase change from solid to liquid, as shown in Figure 3

Figure 3 multi task real-time control software block diagram

fig.3 multi task and time control

software structure

the program between each module is completely independent, the database is shared, and it has rich human-machine dialogue functions. The sampling communication, filtering mode, control algorithm, control parameters, control cycle, display cycle, device address, etc. can be modified on the industrial computer, which is convenient, intuitive and suitable for workers to operate

2.3 temperature control of aging furnace

because the aging process of aging furnace should ensure the uniform and stable distribution of temperature in the furnace, according to the size of the furnace, the furnace is divided into 6 control points (areas) and 2 monitoring points of the control system. Because the temperature is related to the amount of fuel and air volume, and the object has a large time constant, the expert PID plus proportional control method is adopted. The stability and convergence (temperature deviation) of the system are further improved than the conventional PID regulation method

3 liquefied gas system

using gaseous fuel is convenient for automation. In manufacturers without gas sources and new gas stations, the investment is too large to be realized, and natural gas cannot be introduced. The cylinder manifold liquefied gas system is a good way to realize safety and economy. According to relevant national fire regulations, the designed bottle and tank group system is shown in Figure 4. In addition, according to the gas consumption of the furnace, a spray device that uses the waste heat of the flue to heat the water is designed, and the water temperature can be maintained at 50 ~ 60 ℃, so that the liquefied gas can be fully gasified

Figure 4. The use of the group gas tank system

4. The furnace was completed and put into operation in June, 1998. The actual operation is 4 heats, and all technical indexes meet the design requirements, and the use effect is good

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