JP2868824B2 - Temperature and atmosphere control device for firing furnace - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature and atmosphere control apparatus suitable for use in a temperature and atmosphere control of a firing furnace, for example, a calcining furnace for a powder molded product having an organic binder. .

(Prior art) Temperature control of the temperature inside a furnace such as a firing furnace comprising a temperature controller, a cold junction compensator for a thermocouple, a linearizer and a temperature controller comprising a linearizer and a temperature controller, and an operating device comprising a heating element. Devices are conventionally known.

In this temperature control device, the temperature inside the furnace detected by the temperature detector is linearized by a linearizer, and the temperature information after the linearization is supplied to the temperature controller. Next, the supplied temperature information is compared with a temperature rise / fall schedule between the temperature and the time stored in the temperature controller in advance. As a result of the comparison, if the supplied temperature information is lower than the set value that can be read from the heating / cooling schedule, increase the power supplied to the heating element, and if the supplied temperature information is higher than the set value, decrease the power supplied to the heating element. Thus, the actual furnace temperature is controlled so as to follow the preset furnace temperature rise / fall schedule.

(Problems to be Solved by the Invention) In the above-described furnace temperature control device, the schedule for raising and lowering the temperature is determined in accordance with factors such as a change in the furnace atmosphere that is predicted in advance. For example, in a calcining furnace for a molded body containing a large amount of an organic binder or the like, the organic binder in the molded body is scattered or disappears from the molded body at a certain temperature, so that the oxygen concentration rapidly decreases near that temperature. Since it is necessary to keep the temperature high and constant at the position where the temperature decreases, a temperature raising / cooling schedule for maintaining the temperature constant at that position is determined and used.

However, when the temperature control is performed according to the heating / cooling schedule determined by prediction as described above,
The actual temperature and atmosphere inside the furnace change depending on factors such as the shape of the molded product to be calcined, the internal volume of the furnace, the capacity and arrangement of the heating element, but the actual heating / cooling schedule does not change. However, there is a problem that the control in accordance with the temperature and atmosphere in the furnace cannot be performed.

That is, in the case of the calcining furnace described above, if the temperature rise rate of the powder molded product having the organic binder is too high, thermal distortion occurs due to the difference between the surface temperature and the internal temperature, and cracks are generated, or the organic binder is not used. Gas is generated during combustion, and if the amount of generated gas is large, the bonding force of the powder molded product is extremely reduced, so that the molded product is shattered and the organic binder does not flow to the surface of the powder molded product There were drawbacks. on the other hand,
If the rate of temperature rise is too slow, there is also a problem that the pre-firing time becomes long, which is extremely uneconomical. Further, when the oxygen concentration in the atmosphere of the calciner is too low, there is a problem that unburned organic binder remains inside the powder molded product and the strength is reduced.

An object of the present invention is to solve the above-described problems and to implement not only control of the temperature but also control of the temperature and atmosphere of a suitable firing furnace by performing control based on both values of the temperature and the atmosphere. It is an object of the present invention to provide a temperature atmosphere control device that can perform the above-described steps.

(Means for Solving the Problems) A first invention of a temperature and atmosphere control apparatus for a firing furnace of the present invention includes:
A temperature detector that measures the temperature in the furnace and outputs temperature information in the furnace, an atmosphere detector that measures the atmosphere concentration in the furnace, and outputs information on the atmosphere in the furnace, and the atmosphere information is preset. An atmosphere concentration discriminator that compares a set value of the atmosphere concentration for discrimination and outputs a discrimination signal, a temperature rise rate selection unit that switches a temperature rise rate based on the discrimination signal and outputs temperature rise rate information, A temperature controller that outputs a temperature control signal for controlling the temperature in the furnace based on the temperature information and the temperature rise rate information in the inside, and a power supply source that heats a heating element based on the temperature control signal. It is a feature.

Further, a second invention of the temperature and atmosphere control apparatus of the firing furnace of the present invention measures a temperature in the furnace and outputs temperature information in the furnace, and a temperature detector for measuring the atmosphere concentration in the furnace. An atmosphere detector that outputs atmosphere information of the atmosphere, an atmosphere controller that compares the atmosphere information with a preset atmosphere concentration set value, and outputs an atmosphere control signal for controlling an atmosphere in the furnace; A carrier gas supply device that supplies a carrier gas into the furnace by opening and closing a control valve based on a control signal, compares the atmosphere information with a preset discriminating atmosphere concentration set value, and outputs a discriminating signal. An atmosphere concentration discriminator, a temperature rise rate selection unit that switches the temperature rise rate based on the discrimination signal and outputs temperature rise rate information, and controls the furnace temperature based on the furnace temperature information and the temperature rise rate information. To do A temperature controller for outputting a temperature control signal, and characterized by comprising a power supply source for heating the heating body based on the temperature control signal.

Further, the third embodiment of the temperature-atmosphere control device of the firing furnace of the present invention.
The present invention measures a temperature in the furnace, a temperature detector that outputs temperature information in the furnace, an atmosphere detector that measures an atmosphere concentration in the furnace, and outputs atmosphere information in the furnace, and the atmosphere information. An atmosphere controller that outputs an atmosphere control signal for controlling the atmosphere in the furnace by comparing a preset concentration value for atmosphere with the atmosphere, and opens and closes a control valve based on the atmosphere control signal to enter the furnace. A carrier gas supply device for supplying a carrier gas, a maximum temperature rise rate obtained from the temperature information, and a signal converted from the atmosphere control signal so that the control signal is increased when the atmosphere concentration is lower than the atmosphere concentration set value. A temperature rise rate selection unit that determines the temperature rise rate from the temperature and outputs temperature rise rate information, and outputs a temperature control signal for controlling the furnace temperature based on the temperature information in the furnace and the temperature rise rate information. A degree controller and is characterized by comprising a power supply source for heating the heating body based on the temperature control signal.

(Operation) In the configuration of the first invention described above, in addition to the same temperature controller as the conventional apparatus, a means for detecting the atmospheric concentration of the firing furnace such as an oxygen concentration meter and an oxygen partial pressure gauge is provided. The firing is carried out by switching the temperature rise rate set by the temperature controller in accordance with the furnace atmosphere detected by the detecting means. Therefore, for example, when calcining a molded body containing an organic binder, it becomes possible to control the temperature in accordance with the state of the amount of combustion gas generated in the organic binder and the like, and a temperature at which sufficient calcining or the like can be performed with the shortest calcining time Atmosphere control can be achieved.

Further, in the structure of the second invention, the temperature rise rate is controlled by the atmosphere in the same manner as in the first invention, and a means for supplying a carrier gas into the furnace is further provided so that the atmosphere in the furnace can be controlled. Therefore, better control of the furnace atmosphere can be achieved.

Further, in the configuration of the third invention, similarly to the first invention and the second invention, the control of the temperature rise rate by the atmosphere and the control of the furnace atmosphere by the supply of the carrier gas are performed, and the furnace temperature is further controlled. Since the configuration is such that fine control of the rate of temperature rise can be performed based on both the furnace atmosphere and the furnace atmosphere, the temperature atmosphere can be more suitably controlled than the first and second inventions.

(Embodiment) FIG. 1 is a diagram showing a state in which a temperature atmosphere control device of the present invention is combined with a calcining furnace as an example of an actual baking furnace. In FIG. 1, reference numeral 1 denotes a molded body to be calcined containing, for example, an organic binder, 2 denotes a support for mounting the molded body 1, and 3 denotes a temporary housing for accommodating the molded body 1 and the support 2 therein. The furnace 4 is a heater for calcining the molded body 1 provided on the furnace wall of the calciner 3, and 5-1 to 5-3 are temperature detectors for measuring the furnace temperature at each position. , 6 is an atmosphere in the furnace, here, an oxygen sensor for measuring oxygen concentration, 7 is a magnitude of electric power supplied to the heater 4 based on the outputs of the temperature detectors 5-1 to 5-3 and the oxygen sensor 6. Is a temperature / atmosphere control unit that controls the rate of temperature rise by changing the temperature.
Reference numeral 8 denotes a diffusion fan for making the temperature and atmosphere in the furnace uniform, 9 denotes a carrier gas supplier for supplying a gas corresponding to the furnace atmosphere into the furnace, and 10 denotes a carrier gas supplier 9 and a calciner. 3, a carrier gas control section provided in the pipe 10, 12 a pipe for discharging the atmosphere in the furnace to the outside, and 13 a pressure in the furnace provided in the pipe 12. A pressure detector 14 for adjusting the furnace pressure in accordance with the furnace pressure measured by the pressure detector 13.

FIG. 2 is a block diagram showing the configuration of the first embodiment of the temperature and atmosphere control apparatus of the present invention. In FIG. 2, the temperature information in the furnace at each position detected by the temperature detectors 5-1 to 5-3 provided in the furnace is linearized by the linearizer 21, and the temperature information after the linearization is obtained. Supply to the temperature controller 22. The cold junction compensator 23 is used to correct the supplied temperature information. On the other hand, the oxygen concentration information in the furnace detected by the oxygen sensor 6 provided in the furnace is output from the linearizer 24.
After that, the density information after the straight line is supplied to the atmosphere density determination unit 25. In the atmosphere concentration determination section 25,
The supplied oxygen concentration information in the furnace is compared with preset oxygen concentration information, and an atmosphere concentration discrimination signal indicating whether the oxygen concentration in the furnace is equal to or higher than a predetermined value is generated. The obtained atmosphere concentration determination signal is supplied to the temperature rise rate selection unit 26. When the oxygen concentration in the furnace is equal to or higher than a preset oxygen concentration, the temperature increase rate selection unit 26 sets the first temperature rise rate preset in the selection unit 26 and sets the oxygen concentration in the furnace in advance. When the oxygen concentration is equal to or less than the set oxygen concentration, the selection unit 26 controls so as to switch to the second temperature increase rate set in advance.

As described above, the first temperature selected by the temperature rise rate selection unit 27
Or the second rate of temperature rise is integrated in the integrator 27,
The temperature is supplied to the temperature control unit 22 as temperature information indicating the temperature with respect to the elapsed time from the start of the temperature rise. The temperature controller 22 compares the temperature information actually detected by the temperature detectors 5-1 to 5-3 with the temperature information supplied from the integrator 27, and outputs a control signal such that the two coincide with each other. Heater 4 to 28
By controlling the temperature, the temperature and atmosphere in the furnace are controlled.

3 (a) and 3 (b) are graphs showing a control method in the temperature and atmosphere control apparatus of the present invention shown in FIG. 2, and FIG. 3 (a) shows the elapsed time from the start of temperature rise and the actual time. FIG. 3B is a graph showing the relationship between the oxygen concentration in the furnace and FIG. 3B is a graph showing the relationship between the elapsed time and the expected temperature as a result of the control. As shown in FIGS. 3 (a) and 3 (b), in a region where the actually measured oxygen concentration value in the furnace is larger than the oxygen concentration value preset in the atmosphere concentration discriminating unit 25, the first temperature rise rate is set. In the region where the actually measured oxygen concentration value is smaller than the preset oxygen concentration value, the temperature is switched to the second temperature increase rate, and the temperature is raised to the final temperature. After maintaining at the final temperature for a predetermined time, the temperature is lowered as usual and the calcination is completed.

FIG. 4 is a block diagram showing a configuration of a second embodiment of the temperature and atmosphere control apparatus of the present invention. In the example shown in FIG. 4, the same members as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. In the example shown in FIG. 4, as in the example shown in FIG. 2, not only the temperature control is performed by switching the temperature rise rate according to the oxygen concentration, but also the oxygen concentration information in the furnace obtained from the oxygen sensor 6 is transmitted to the atmosphere controller. The carrier gas is supplied to the furnace 31 and compared with an atmosphere set value preset in the atmosphere controller 31, and a carrier gas containing oxygen is supplied into the furnace according to the result. That is, when the oxygen concentration in the furnace is lower than the atmosphere set value, a predetermined amount of carrier gas is supplied from the carrier gas supply device 32 into the furnace by opening the control valve 33. Atmosphere controller 31 generates a control signal to close 33 and supplies it to control valve controller 34.

5 (a) and 5 (b) are graphs showing a control method in the temperature control device of the present invention shown in FIG. 4, and FIG. 5 (a) shows the elapsed time from the start of heating and the actual furnace. FIG. 5B shows the relationship between the elapsed time and the expected temperature as a result of the control. In this embodiment,
As shown in FIG. 5 (a), not only is the first temperature rise rate and the second temperature rise rate switched before and after the atmosphere discriminator concentration set value, but also the oxygen When the concentration is reduced, a carrier gas containing oxygen is supplied into the furnace to control the concentration so as not to be lower than the atmospheric concentration set value.

In this embodiment, not only can the calcining schedule and the like be finely controlled, but also because the oxygen atmosphere does not become lower than the concentration set value for the atmosphere, the unburned matter of the organic binder can be prevented from remaining in the powder compact during calcining or the like. Cracks can be prevented more effectively.

FIG. 6 is a block diagram showing the configuration of a third embodiment of the temperature and atmosphere control apparatus of the present invention. In the example shown in FIG. 6, the same members as those shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. In the example shown in FIG. 6, unlike the examples shown in FIGS. 2 and 4, the oxygen concentration information and the temperature information are supplied to the atmosphere controller 31, and first, the temperature and the oxygen concentration provided in the atmosphere controller 31 in advance. a programmable look-up table consisting of, for generating an oxygen concentration control signal y _c. Together with the oxygen concentration control signal y _c is supplied to the control valve controller 34, the control signal y _c is inverted from _{y c '= 100-y c} , 0% when for maximum increase of oxygen concentration, the oxygen The control signal y _c ′ is set to 100% when the density is reduced to the minimum.

On the other hand, the temperature information obtained from the temperature detectors 5-1 to 5-3 is obtained from a programmable look-up table indicating the relationship between the temperature and the temperature rise rate provided in advance in the temperature controller 22, from the maximum temperature at each temperature. Rise rate information max (dθ / d
t) occurs.

Then, in the integrator 27, based on the control signal y _c ′ and information max (dθ / dt) of the maximum temperature rise rate, ｛max (dθ / dt) ×
The calculation of y _c ′｝ / 100 is performed to determine the rate of temperature rise at each temperature. Finally, the obtained rate of temperature rise is supplied to the temperature controller 22 to perform temperature control in the same manner as in the embodiment shown in FIGS.

7A and 7B are graphs showing a control method in the temperature control device of the present invention shown in FIG.
FIG. 7A shows the elapsed time from the start of heating and the actual oxygen concentration in the furnace, and FIG. 7B shows the relationship between the elapsed time and the expected temperature as a result of the control. In this embodiment, as shown in FIG. 7A, a plurality of atmosphere control setting values are provided, and the temperature rise rate can be finely controlled based on the setting values. Also,
Further finer temperature control can be performed.

(Effect of the Invention) As is clear from the above description, according to the present invention, not only the temperature control system, but also the atmosphere control system and the carrier gas control system are provided, so that only the temperature control is performed. Instead, by controlling based on both the temperature and the atmosphere, it is possible to control the temperature and the atmosphere of the firing furnace in a preferable manner.

Therefore, for example, when the present invention is applied to a calciner,
Cracking and breakage at the time of pre-firing due to the organic binder can be prevented, unburned materials during pre-firing do not remain, and the pre-firing time can be shortened.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a temperature atmosphere control device of the present invention is combined with a calciner as an example of an actual firing furnace. FIG. 2 is a diagram showing a configuration of a first embodiment of the temperature atmosphere control device of the present invention. 3 (a) and 3 (b) are graphs each showing a control method in the first embodiment shown in FIG. 2, and FIG. 4 is a second diagram of the temperature and atmosphere control apparatus of the present invention. 5 (a) and 5 (b) are graphs each showing a control method in the second embodiment shown in FIG. 4, and FIG. 6 is a temperature and atmosphere control of the present invention. FIG. 7 is a block diagram showing the configuration of a third embodiment of the apparatus. FIGS. 7A and 7B are graphs each showing a control method in the third embodiment shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Molded body 2 ... Support base 3 ... Calcining furnace 4, ... Heater 5-1-5-3 ... Temperature detector 6 ... Oxygen sensor, 7 ... Temperature / atmosphere control part 8 ... ... Diffusion fan, 9 ... Carrier gas supply 10,12 ... Pipe line, 11 ... Carrier gas regulator 13 ... Pressure detector, 14 ... Pressure regulator 21,24 ... Linearizer, 22 ... Temperature Controller 23: Cold junction compensator, 25: Atmospheric concentration discriminator 26: Temperature rise rate selection unit, 27: Integrator 28: Power supply source 31, 31: Atmosphere controller 32: Carrier gas supply Equipment 33 Control valve 34 Control valve controller

Claims (3)

(57) [Claims] A temperature detector for measuring a temperature in the furnace and outputting temperature information in the furnace; an atmosphere detector for measuring an atmosphere concentration in the furnace and outputting information on the atmosphere in the furnace; An atmosphere concentration discriminator that outputs a discrimination signal by comparing the information with a preset atmosphere concentration set value for discrimination, and a temperature rise rate selection that outputs a temperature rise rate information by switching a temperature rise rate based on the discrimination signal. A temperature controller for outputting a temperature control signal for controlling the temperature in the furnace based on the temperature information in the furnace and the temperature increase rate information, and a power supply source for heating a heating element based on the temperature control signal A temperature and atmosphere control apparatus for a firing furnace, comprising: A temperature detector for measuring a temperature in the furnace and outputting temperature information in the furnace; an atmosphere detector for measuring an atmosphere concentration in the furnace and outputting information on the atmosphere in the furnace; An atmosphere controller for comparing the information with a preset atmosphere concentration set value and outputting an atmosphere control signal for controlling the atmosphere in the furnace; and opening and closing a control valve based on the atmosphere control signal to control the furnace. A carrier gas supply device that supplies a carrier gas into the inside; an atmosphere concentration discriminator that compares the atmosphere information with a preset discrimination atmosphere concentration set value and outputs a discrimination signal; and a temperature rise based on the discrimination signal. A temperature rise rate selection unit that outputs a temperature rise rate information by switching a rate, and a temperature controller that outputs a temperature control signal for controlling a furnace temperature based on the temperature information inside the furnace and the temperature rise rate information. , A temperature atmosphere control device for a firing furnace, comprising a power supply source for heating a heating element based on the temperature control signal. 3. A temperature detector for measuring a temperature in the furnace and outputting temperature information in the furnace, an atmosphere detector for measuring an atmosphere concentration in the furnace and outputting atmosphere information in the furnace, and the atmosphere An atmosphere controller for comparing the information with a preset atmosphere concentration set value and outputting an atmosphere control signal for controlling the atmosphere in the furnace; and opening and closing a control valve based on the atmosphere control signal to control the furnace. A carrier gas supply device for supplying a carrier gas into the inside, a maximum temperature rise rate determined from the temperature information, and a signal converted from the atmosphere control signal so that the control signal increases when the atmosphere concentration is lower than the atmosphere concentration set value. A temperature rise rate selection unit that determines a temperature rise rate from the above and outputs temperature rise rate information; and outputs a temperature control signal for controlling the furnace temperature based on the temperature information in the furnace and the temperature rise rate information. A temperature controller which, firing furnace temperature atmosphere control apparatus characterized by comprising a power supply source for heating the heating body based on the temperature control signal.