JP2010223561A - Method of controlling dew point for baking furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of controlling a dew point capable of controlling a dew point with high accuracy while preventing attachment of a binder-derived organic decomposed matter to a dew point measuring means for a gas in a furnace in baking ceramics in the baking furnace. <P>SOLUTION: In a binder removing process, the dew-point control is performed by sampling a furnace supply gas supplied into the baking furnace 1, measuring the dew point by a dew-point meter 3 for control, and performing feedback adjustment of error to a set dew point, and in a sintering process, the dew-point control is performed by sampling the furnace gas, measuring the dew point by the dew-point meter 3 for control, and performing feedback adjustment of the error to the set dew point. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dew point control method optimum for a ceramic firing furnace.

  In general, the ceramic firing step includes a debuy step for removing the binder added for forming the raw material, a sintering step for bonding the raw material particles from which the binder has been removed in the step, and sintering the formed body. And a cooling step of cooling the product after sintering.

  In order to exhibit the properties required for each product, firing under firing conditions corresponding to each property is required.

  In addition, in order to produce a product having predetermined characteristics uniformly and with a high yield, a firing facility that realizes optimum firing conditions with high accuracy is required.

  Conventionally, it is known that the dew point in the firing furnace affects the degree of sintering of ceramic raw material particles.

  Regarding dew point control in a firing furnace, for example, a technique for optimally controlling a low dew point dry gas and a high dew point wet gas flow rate by PID control while measuring the dew point in the furnace (Patent Document 1) is disclosed. .

  However, the organic decomposition product derived from the binder generated from the molded body in the debaking process of the conventional firing furnace is caused by the in-furnace gas composed of the in-furnace gas sampling pipe, the in-furnace gas sampling control mechanism, and the control dew point meter. A phenomenon of adhesion to the dew point measuring means was observed, and there was a problem that precise dew point control could not be performed with the dew point measuring means to which the organic matter adhered. Specifically, when an organic decomposition product derived from a binder adheres to the furnace sampling pipe and the furnace gas sampling control mechanism, the control dew point meter measures because the deposit has the property of absorbing and releasing moisture. Deviation occurs between the dew point and the dew point in the firing furnace, making precise control impossible. Further, since the organic decomposition product deteriorates the control dew point meter, there is a problem that it is necessary to frequently replace the control dew point meter.

  When the dew point of the gas supplied in the furnace is controlled instead of the furnace gas, the dew point in the furnace fluctuates due to the influence of moisture generated from the furnace material, and the control accuracy deteriorates to about ± 5 ° C. there were. Specifically, dew point control is particularly important in the sintering process at a high temperature, but once moisture in the atmosphere before the start of firing and moisture derived from the binder of the molded body in the debuy process are once adsorbed to the furnace material, Even in a high-temperature sintering process including a temperature raising process, the temperature rise inside the furnace material is delayed, so that moisture is continuously released, which causes a problem in dew point control.

JP-A-1-316417

  The object of the present invention is to solve the above problems, and when performing ceramic firing in a firing furnace, the organic decomposition product derived from the binder does not adhere to the dew point measuring means of the furnace gas, and the dew point of high accuracy is achieved. It is to provide a dew point control method that can be controlled.

  The dew point control method of the firing furnace of the present invention made to solve the above problems is a debuy process for removing the binder added for raw material molding, and the raw material particles from which the binder has been removed in the above process are combined. A dew point control method for a ceramic firing process having a sintering process for sintering a formed body, and in the debuy process, the dew point is sampled by sampling the furnace supply gas supplied into the firing furnace. The dew point is controlled by feeding back and adjusting the error from the set dew point. In the sintering process, the gas in the furnace is sampled, the dew point is measured by the control dew point meter, and the error from the set dew point is feedback adjusted. It is characterized by performing dew point control.

  The invention according to claim 2 is the dew point control method for a firing furnace according to claim 1, wherein the firing furnace is a batch furnace, and in the debuy process, the furnace supply gas is purged into the furnace gas sampling pipe. It is a feature.

  According to a third aspect of the present invention, in the dew point control method for a firing furnace according to the first or second aspect, the dew point is measured by sampling the supply gas in the furnace and measuring the dew point with a monitor dew point meter. By comparing the measured dew point value with the measured dew point value measured by the control dew point meter in the same process, the functional deterioration of the control dew point meter is detected.

  The dew point control method for a firing furnace according to the present invention is based on a dew point that is obtained by sampling the furnace supply gas supplied to the firing furnace in the debuy process in which the cracked gas derived from the binder is contained in the furnace gas. The dew point is controlled by feedback and adjusting the error from the set dew point, and the furnace gas is sampled in the sintering process when the debuy process is completed and the cracked gas derived from the binder is no longer contained in the furnace gas. Then, the dew point is measured by the control dew point meter, and dew point control is performed to feedback and adjust the error from the set dew point. Thereby, highly accurate dew point control can be performed, avoiding the phenomenon that the organic decomposition product derived from the binder adheres to the dew point measuring means of the in-furnace gas.

  In the dew point control method for a firing furnace according to claim 2, the firing furnace is a batch furnace, and in the de-bye step, the furnace supply gas is purged into the furnace gas sampling pipe. Thereby, it is possible to prevent the organic decomposition product derived from the binder from entering from the inside of the furnace into the piping for sampling the gas in the furnace by diffusion in the debuy process, and to adhere to the dew point measuring means of the furnace gas. It can be strictly prevented.

  In the dew point control method for a firing furnace according to claim 3, control is performed by measuring the same sample (in-furnace supply gas) with a control dew point meter and a monitor dew point meter in a debuy process, and comparing each measured value. It is possible to detect functional deterioration of the dew point meter.

FIG. 3 is an explanatory diagram of a debuying process according to the first embodiment. FIG. 3 is an explanatory view of a sintering process of the first embodiment. FIG. 6 is an explanatory diagram of a debuying process according to the second embodiment. FIG. 10 is an explanatory diagram of a sintering process of Embodiment 2. FIG. 10 is an explanatory diagram of a debuying process according to a third embodiment. FIG. 10 is an explanatory view of a sintering process of Embodiment 3. FIG. 10 is an explanatory diagram of a debuying process according to a fourth embodiment. FIG. 10 is an explanatory diagram of a sintering process of Embodiment 4.

  Preferred embodiments of the present invention are shown below. The dew point control method of the present invention includes a debuy process for removing a binder added for forming a raw material, and a sintering process for bonding the raw material particles from which the binder has been removed in the above process to sinter the compact. It is a dew point control method suitable for dew point control in a ceramic firing process having Below, the dew point control method which concerns on this invention is demonstrated with each form of Embodiment 1-4.

(Embodiment 1)
FIG. 1 is an explanatory view of a debuying process, and FIG. 2 is an explanatory view of a sintering process.

  1 and 2, reference numeral 1 denotes a firing furnace body, 2 denotes furnace supply gas adjusting means, 3 denotes a control dew point meter, 4 denotes furnace gas sampling piping, 5 denotes a furnace gas sampling control mechanism, and 6 denotes a furnace. An internal supply gas pipe, 7 is an internal furnace gas sampling pipe, 8 is an internal furnace gas sampling control mechanism, 9 is a dew point control means, and 12 is a gas sampling pump. The furnace supply gas adjusting means 2 includes a dry gas supply means 2a, a wet gas supply means 2b, a dry gas flow rate adjusting means 2c for adjusting each gas flow rate, and a wet gas flow rate adjusting means 2d.

  In this embodiment, it is aimed to keep the dew point in the firing furnace 1 within a control range of −3 to 13 ° C. and a control accuracy of ± 1 ° C. The target dew point is input to the dew point control means 9 as a set value. The dew point control means 9 receives the output data of the control dew point meter 3, performs mass flow control of the dry gas flow rate adjusting means 2c and the wet gas flow rate adjusting means 2d by PID control, and is supplied from the dry gas supply means 2a. The flow rate control between the dry gas and the wet gas supplied from the wet gas supply means 2b is performed. In this embodiment, gas is supplied into the firing furnace 1 at a flow rate of 1000 L / min in the debuy process and 100 L / min in the sintering process.

  The in-furnace gas sampling control mechanism 5 is an on-off valve that opens and closes the in-furnace gas sampling pipe 4, and the in-furnace supply gas sampling control mechanism 8 is an on-off valve that opens and closes the in-furnace supply gas sampling pipe 7.

  In the debuy process shown in FIG. 1, the in-furnace gas sampling control mechanism 5 is closed, and the organic decomposition product derived from the binder contained in the in-furnace gas contains the control dew point meter 3, the in-furnace gas sampling pipe 4, The phenomenon of adhering to the gas sampling control mechanism 5 is avoided. Further, the in-furnace supply gas sampling control mechanism 8 is opened, and the in-furnace supply gas is guided to the control dew point meter 3 to perform dew point control.

  In the sintering step shown in FIG. 2, the in-furnace gas sampling control mechanism 5 is opened, and the in-furnace gas is guided to the control dew point meter 3 to perform dew point control. At this time, the furnace supply gas sampling control mechanism 8 is closed.

  In this way, in the debuy process in which the organic gas derived from the binder is contained in the furnace gas, the furnace supply gas supplied to the firing furnace is sampled, the dew point is measured by the control dew point meter, and the set dew point is determined. The dew point is controlled by feedback adjustment of the error, and in the sintering process when the debuy process is completed and the organic gas decomposed from the binder is not contained in the furnace gas, the furnace gas is sampled for control. By measuring the dew point with a dew point meter and performing dew point control to feedback and adjust the error from the set dew point, the organic degradation products derived from the binder are controlled by the dew point meter for control 3, the gas sampling pipe 4 in the furnace, and the gas sampling control in the furnace. The phenomenon of adhering to the mechanism 5 can be avoided. Specifically, when an organic decomposition product derived from a binder adheres to the furnace sampling pipe and the furnace gas sampling control mechanism, the control dew point meter measures because the deposit has the property of absorbing and releasing moisture. Deviation occurs between the dew point and the dew point in the firing furnace, making precise control impossible. However, according to this configuration, the dew point control is improved to ± 1 ° C level in the de-buy process and firing process. Can be made.

  Further, since the control dew point meter is not deteriorated by the organic decomposition product derived from the binder, the frequency of exchanging the control dew point meter, which was conventionally required every 8 months, can be greatly reduced.

(Embodiment 2)
FIG. 3 is an explanatory view of a debuy process, and FIG. 4 is an explanatory view of a sintering process.

  In the present embodiment, the dew point control apparatus of the first embodiment is further provided with a purge means for the furnace gas sampling pipe 4. The purge means includes a purge gas supply pipe 9 branched from the furnace supply gas pipe 6 and a purge control mechanism 10. The purge control mechanism 10 is an open / close valve that opens and closes the purge gas supply pipe 9.

  In the debuy process shown in FIG. 3, the purge control mechanism 10 is opened to purge the furnace gas sampling pipe 4 using the furnace supply gas.

  In the sintering process shown in FIG. 4, since the in-furnace gas sampling control mechanism 5 is opened and the in-furnace gas is guided to the control dew point meter 3 and dew point control is performed as described above, the purge control mechanism 10 is closed. The purge is stopped as a state.

  In this way, in the debuy process, the furnace supply gas is purged into the furnace gas sampling pipe, so that the organic decomposition products derived from the binder diffuse from the furnace into the furnace gas sampling pipe in the debuy process. It is possible to prevent the penetration of the gas and to adhere to the dew point measuring means of the in-furnace gas in the furnace gas collecting pipe.

(Embodiment 3)
FIG. 5 is an explanatory view of the debuy process, and FIG. 6 is an explanatory view of the sintering process.

  In this embodiment, the dew point control device of the first embodiment is further provided with a dew point meter 11 for monitoring supply gas. The monitor dew point meter 11 always measures the dew point of the in-furnace supply gas.

  In the debuy process shown in FIG. 5, since the in-furnace supply gas sampling control mechanism 8 is opened and the in-furnace supply gas is guided to the control dew point meter 3 and the control dew point is measured. Both the meter 3 and the monitor dew point meter 11 measure the dew point of the in-furnace supply gas.

  In the sintering process shown in FIG. 6, the furnace gas sampling control mechanism 5 is opened as described above, the furnace gas is guided to the control dew point meter 3 to perform dew point control, and the furnace supply gas sampling control mechanism 8 is Closed.

  Since the dew point meter 11 for monitoring always measures the dew point of the in-furnace supply gas, the monitor dew point meter 11 does not deteriorate due to the organic decomposition product derived from the binder generated in the furnace. On the other hand, as described above, the control dew point meter 3 measures the dew point of the gas supplied in the furnace in the debuy process, but the dew point of the gas in the furnace is measured in the sintering process. When a trace amount of binder that cannot be completely decomposed is decomposed in the sintering process, the control dew point meter may be deteriorated.

  In order to maintain the dew point control accuracy satisfactorily, it is required to immediately detect and deal with the deterioration of the control dew point meter 3. According to the configuration of the present embodiment, the dew point meter for control uses the control dew point meter and the monitor dew point meter to measure the same sample (in-furnace supply gas) and compare the measured values with each other. It is possible to detect the deterioration of the function. In addition, when there are a plurality of furnaces, a monitor dew point meter can be shared.

(Embodiment 4)
FIG. 7 shows an explanatory view of the debuy process, and FIG. 8 shows an explanatory view of the sintering process.

  This embodiment includes both the constituent elements of the second embodiment and the third embodiment.

1 Firing furnace body 2 Furnace supply gas adjustment means 2a Dry gas supply means 2b Wet gas supply means 2c Dry gas flow rate adjustment means 2d Wet gas flow rate adjustment means 3 Control dew point meter 4 Furnace gas sampling pipe 5 Furnace gas sampling Control mechanism 6 Furnace supply gas pipe 7 Furnace supply gas sampling pipe 8 Furnace supply gas sampling control mechanism 9 Dew point control means 10 Purge control mechanism 11 Supply gas monitoring dew point meter 12 Gas sampling pump

Claims (3)

A dew point control method for a ceramic firing process, which includes a debuy process for removing a binder added for forming a raw material, and a sintering process for bonding raw material particles from which the binder has been removed in the above process to sinter a formed body. Because
In the debuy process, the dew point is measured by sampling the furnace supply gas supplied into the firing furnace, measuring the dew point with a control dew point meter, and feedback adjusting the error from the set dew point.
In the sintering step, a dew point control method for a firing furnace is characterized in that the dew point is controlled by sampling an in-furnace gas, measuring the dew point with the control dew point meter, and feedback adjusting an error from the set dew point.   2. The dew point control method for a firing furnace according to claim 1, wherein the firing furnace is a batch furnace, and the furnace supply gas is purged into the furnace gas sampling pipe in the debuy process. The firing furnace is a batch furnace, the supply gas in the furnace is sampled, and the dew point is measured with a dew point monitor.
2. The functional deterioration of the control dew point meter is detected by comparing the dew point measured value by the monitor dew point meter in the debuy process with the dew point measured value by the control dew point meter in the same process. Or the dew point control method of the baking furnace of 2.

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