JP4548777B2 - Method for predicting remaining amount of refractory and method for operating ash melting furnace using the same - Google Patents

Description

  The present invention provides an ash melting furnace for melting and treating ash such as waste incineration ash and fly ash, and has found an appropriate operating condition of the ash melting furnace, and has made it possible to perform a low-cost and highly reliable operation. The present invention relates to a method for operating a melting furnace, and further relates to a method for predicting a remaining amount of refractory for predicting a remaining amount of refractory lined on the inner wall of an ash melting furnace.

In the field of waste treatment, the need for melting treatment using an ash melting furnace is increasing for the purpose of detoxifying, reducing the volume, and recycling resources. In the ash melting furnace, the workpiece is melted to produce slag. This slag encloses harmful substances contained in ash and is recovered as a useful resource and can be reused as a ground improver, roadbed material, aggregate for asphalt, and the like.
In the operation of the ash melting furnace, it is necessary to maintain a plurality of operating conditions such as the amount of work to be processed, input power, slag temperature, furnace temperature, etc. at appropriate values and perform safe and reliable operation. However, in the conventional operation of the ash melting furnace, the actual situation is that the operator performs empirical control based on the measurement values of various measuring devices provided in the ash melting furnace. For this reason, it is difficult to perform stable driving at all times, depending on the driving experience and skill of the operator.

Therefore, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-251520), an optimal operation control method of an ash melting furnace for melting municipal waste and waste incineration residue with high efficiency and low running cost is proposed. is suggesting. First, the power to be supplied to the ash melting furnace or the supply amount of the melt is set, and the amount of melt to be supplied to the ash melting furnace or the power to be supplied to the ash melting furnace is calculated based on the set value. The input power and the melt supply amount are controlled to the set value and the calculated value, or the melt supply amount and input power to the ash melting furnace are controlled to the set value and the calculated value.
In general, in an electric ash melting furnace, the amount of molten material to be processed and the control of the input power are basically controlled objects, and if one of these is determined, the other is calculated in conjunction with this, As a result, optimal operation control of the ash melting furnace that is not affected by the skill of the operator is realized.

On the other hand, in the case of an ash melting furnace for treating ash such as waste incineration ash and fly ash, operation at the melting point of ash or higher is required, so the slag temperature is 1500-1600 ° C. near the outlet in the furnace. Is maintained at a high temperature. In such an ash melting furnace, the refractory placed on the inner wall of the furnace is significantly eroded due to the high temperature atmosphere in the furnace and the influence of corrosive components such as chlorides contained in the ash, and the refractory is in a short time. Since it would erode, it was necessary to replace the refractory periodically in order to operate a safe and reliable furnace.
However, since the erosion amount of the refractory varies depending on the properties of the input ash, the operating condition of the furnace, etc., it has been difficult to determine an appropriate replacement time.

  Therefore, Patent Document 2 (Japanese Patent Laid-Open No. 2003-294372) proposes a refractory material diagnostic apparatus that grasps the amount of damage to the refractory in the ash melting furnace. This measures the difference between the inlet side temperature and the outlet side temperature of the cooling water that cools the refractory material, and measures the flow rate of the cooling water and the temperature in the furnace. The current amount of heat removal from the cooling water is corrected from the past amount of heat removal from the cooling water and the amount of wear of the refractory material, and the amount of damage to the refractory is obtained by calculation. Thereby, it becomes possible to grasp | ascertain the consumption condition of a refractory correctly.

JP 2004-251520 A JP 2003-294372 A

As described above, in order to perform an appropriate operation in a general ash melting furnace, as described in Patent Document 1, the amount of melted material and the control of input power are basically controlled, By connecting these objects to be controlled and maintaining an appropriate value, optimum operation control, that is, the molten state of the object to be processed is maintained in an appropriate state, and an efficient operation is performed.
However, when ash such as incineration ash or fly ash is a processing target, one of the most important factors related to the operation of the furnace is the refractory erosion amount of the furnace in addition to the control target. This is because in the case of an ash melting furnace, the refractory is significantly eroded due to the high temperature atmosphere in the furnace, the influence of corrosive components, etc., and the maintenance cost associated with the replacement of the refractory becomes high. Therefore, in order to perform safe and reliable operation in the ash melting furnace, it is necessary to accurately grasp the refractory erosion amount. Since the operation method according to Patent Document 1 does not take into account the amount of refractory erosion, it has been difficult to apply it to an ash melting furnace.

Moreover, in the apparatus described in Patent Document 2, only the refractory erosion amount is grasped, and the operation of the ash melting furnace has to be relied upon by the operator's technique.
Therefore, in view of the above-described problems of the prior art, an object of the present invention is to provide a method for operating an ash melting furnace that has high reliability and low running cost.
It is another object of the present invention to provide a method for diagnosing the remaining amount of refractory that can accurately calculate the remaining amount of refractory, and a method for operating an ash melting furnace using the same.

Therefore, in order to solve such a problem, the present invention generates a plasma arc in the furnace by passing a current between the anode and cathode electrodes arranged in the furnace body, and the plasma arc heat or between the electrodes is generated. In an ash melting furnace that melts main ash and fly ash by Joule heat of flowing current, and predicts the remaining amount of refractory lining the inner wall of the ash melting furnace,
First estimating means for detecting far-infrared light in a two-wavelength region radiated from the molten slag liquid surface in the furnace and estimating a molten slag temperature based on the detected infrared light;
In order to cool the furnace body, the heat dissipation amount of the furnace body is calculated from the cooling water amount and the cooling water temperature flowing through the inside of the furnace body, the calculated heat dissipation amount of the furnace body and the ash input amount per hour, between the electrodes Second slag temperature estimating means for estimating the molten slag temperature using the thermophysical equation of ash from the input power of the power source applied to
A third molten slag temperature estimating means for obtaining a slag resistance from the current and voltage flowing between the electrodes and estimating a molten slag temperature from a temperature characteristic of the slag resistance;
A fourth molten slag temperature estimating means for estimating the refractory surface temperature from the furnace temperature based on the correlation between the furnace temperature and the refractory temperature;
Obtain the refractory surface temperature from the estimated molten slag temperature obtained from any one or more of the estimation means,
The amount of erosion at the contact surface between the refractory brick and the slag in the furnace is determined by the basicity of the slag formed by replacing the fly ash mixing ratio corresponding to the ratio of CaO and SiO ₂ ,
As a parameter to replace the slag flow velocity in the ash melting furnace corresponding to the boundary layer thickness of the slag liquid level, the ash treatment load factor (ash treatment amount / reference ash treatment amount) is obtained.
Based on the refractory surface temperature, basicity, and processing load factor obtained above, calculate the erosion rate of the refractory,
Based on the initial value of the refractory and the erosion rate, the remaining amount of refractory is predicted ,
The refractory estimated based on the following one-dimensional heat passage model equation (Equation 6) from the estimated molten slag temperature obtained from any one or more of the first estimating means to the fourth melting slag temperature estimating means The erosion rate of the refractory is calculated from the following erosion rate equation (Equation 5), in which the basicity and the processing load factor are added as correction factors.
A method for predicting the remaining amount of refractory is proposed, wherein the remaining amount of refractory is predicted based on the initial value of refractory and the erosion rate.
One-dimensional heat passage model formula (Formula 6).
T _s : slag temperature, T _w : water temperature, α _sr : heat transfer coefficient between slag and refractory brick (heat transfer coefficient α _sr between slag and refractory brick was obtained from temperature measurement result in actual furnace), λ: fire resistance Brick thermal conductivity, subscripts 1, 2: Refractory brick type (erosion rate formula)
A, B, C: constant, E: activation energy, v: treatment load factor, η: basicity, x: erosion amount, t: time At this time, the surface temperature of the refractory may be directly measured. However, since this measurement is difficult during driving or the like, it is obtained by the estimation method.

The present invention flows through a current between the disposed the anode and the cathode to the furnace body electrodes to generate a plasma arc in the furnace, bottom ash by Joule heat of the current flowing between the plasma arc heat or the electrode And an operation method of an ash melting furnace for melting fly ash,
An operation data collection step for collecting operation data of the ash melting furnace;
Remaining amount prediction step defined in "Method for predicting remaining amount of refractory" according to claim 1, wherein the remaining amount of refractory is predicted based on the operation data;
An operation condition step for deriving an operation condition from the remaining amount of the refractory and the operation data;
And a step of operating the ash melting furnace based on the operating conditions.

According to the present invention, the predicted current refractory remaining amount, the refractory remaining reference value that satisfies the safety standard of the refractory remaining amount from the current operation data, and the appropriate operating conditions that satisfy the operation plan such as the operation day target calculates, for which to perform the operation of ash melting furnace on the basis of this operating condition, it is possible to prolong life of the refractory life, further reduction of maintenance costs is FIG.

Then, before Symbol slag temperature of the residual amount prediction method of the refractory senses far-infrared light of two wavelengths range emitted from the slag liquid surface, two-wavelength thermometer for calculating the slag liquid surface temperature based on this It is good to measure by.
Thus, by calculating the erosion rate using the current operation data, the erosion rate can be obtained easily and accurately, and the remaining amount of the refractory can be predicted with high accuracy.

In the operation condition step, the operation condition is derived from the predicted refractory residual amount and a preset refractory residual reference value.
In addition, the said refractory residual reference value means the minimum refractory thickness which can operate an ash melting furnace normally. According to the present invention, based on the predicted current remaining amount of refractory, operating conditions are derived so that the refractory remaining amount after operation satisfies the refractory remaining reference value.

The operation method of the ash melting furnace according to claim 1, further comprising: a monitoring terminal provided in the ash melting furnace; and a monitoring server connected to the monitoring terminal via a communication network,
The monitoring terminal performs the operation data collection step, transmits the collected operation data to the monitoring server, and performs the remaining amount prediction step and the operation condition step based on the operation data received by the monitoring server. Then, the derived operating conditions are transmitted to the monitoring terminal, and the ash melting furnace is operated based on the operating conditions at the monitoring terminal.
Thus, further cost reduction can be expected by operating the ash melting furnace using a remote monitoring system constructed via a communication network. In addition, the present invention can manage a plurality of ash melting furnaces in an integrated manner, thereby improving efficiency.

  Delete

Furthermore, the refractory surface temperature is calculated from the slag temperature based on a one-dimensional heat passage model. At this time, the slag temperature is preferably measured by a two-wavelength thermometer that detects far-infrared light in a two-wavelength region emitted from the slag liquid surface and calculates the slag liquid surface temperature based on this. Accurate slag temperature can be measured while minimizing the influence of dust and furnace gas.
In this way, by making it possible to replace the refractory surface temperature, which is difficult to measure, with the slag temperature, the remaining amount of the refractory can be predicted easily and accurately.

As described above, according to the present invention, the remaining amount of refractory, the refractory remaining reference value that satisfies the safety standard of the refractory remaining amount from the current operation data, and the appropriate operating condition that satisfies the operation plan such as the operation day target Since the ash melting furnace is operated based on the operating conditions, it is possible to extend the life of the refractory and further reduce the maintenance cost.
Moreover, further cost reduction can be expected by operating the ash melting furnace using a remote monitoring system constructed via a communication network. In addition, the present invention can manage a plurality of ash melting furnaces in an integrated manner, thereby improving efficiency.
Furthermore, by predicting the remaining amount of refractory using an approximate expression based on the Arrhenius equation, which adds the basicity and processing load factor as correction factors to the temperature characteristics of the refractory surface, the erosion rate can be easily and accurately estimated. The remaining amount of refractory can be predicted with high accuracy.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
In the present embodiment, a plasma ash melting furnace will be described as an example of the target ash melting furnace. However, the present invention is not limited to this, and incineration ash or fuel ash melting furnace, Any ash melting furnace capable of melting ash such as fly ash may be used.

  FIG. 1 is a side sectional view of a plasma ash melting furnace which is an embodiment of an ash melting furnace to which the present invention is applied, and FIG. 2 is a flowchart showing an operation method of the ash melting furnace according to the first embodiment of the present invention. 3 is a flowchart showing a method for determining operating conditions in the operating method of FIG. 2, FIG. 4 is a flowchart showing a method for calculating the remaining amount of refractory bricks in Example 1, and FIG. 5 is used for the furnace operation of the present invention. 6 is a schematic cross-sectional view showing an example of a slag thermometer, FIG. 6 is an overall configuration diagram showing a remote monitoring system equipped with an ash melting furnace according to Embodiment 2 of the present invention, and FIG. 7 uses the remote monitoring system of Embodiment 2. It is the flowchart which shows the driving method which was.

A plasma melting furnace to which the present invention is applied will be described with reference to FIG.
In the plasma ash melting furnace 10, a refractory brick 11 </ b> B is lined on the inner wall of the furnace body 11, and the outer surface thereof is covered with an iron skin 11 </ b> A. A main electrode 13 is inserted in the upper part of the furnace body 11, and a furnace bottom electrode 14 is inserted in the furnace bottom so as to face the main electrode 13. An insulating sleeve 12 is disposed around the main electrode 13 to prevent a short circuit. In the plasma ash melting furnace 10, a direct current is passed between these electrodes by a direct current power source 15 to generate a plasma arc in the furnace. The ash charged from the ash inlet 16 provided on the furnace wall becomes molten slag 18 by plasma arc heat and Joule heat of current flowing between the electrodes, and is discharged from the tap 17.

The plasma ash melting furnace 10 is equipped with various detection devices. For example, a slag thermometer 20 installed in a measurement opening 19 provided in the furnace lid, a thermocouple 21 embedded in the furnace wall for detecting a refractory brick temperature, and cooling water flowing through the inside of the tap 17 A temperature detector that detects the inlet and outlet temperatures, a temperature detector that detects the furnace temperature, an ammeter and a voltmeter that measure the current and voltage between the electrodes, a meter that measures the ash to be put into the furnace, etc. Is mentioned.
In this embodiment, an appropriate operation condition is obtained based on the current operation data acquired by these detection devices and the ash melting furnace is operated based on this operation condition.

In order to obtain proper operating conditions, it is necessary to collect accurate operating data. For example, a radiation thermometer using infrared rays, a thermocouple, etc. can be used as the slag thermometer, but when the furnace is in a high temperature, corrosive atmosphere and a lot of dust is present like an ash melting furnace. It is preferable to use the slag thermometer shown in FIG.
The slag thermometer 20 is disposed outside the furnace through a transmission window 19 a fitted in the measurement opening 19. The slag thermometer 20 has a condensing lens 202 disposed at the furnace side end of the casing 201, and a visible light separating mirror 203 is disposed at a predetermined angle so as to face the condensing lens 202. The The visible light separation mirror 203 reflects visible light in a direction orthogonal to the optical axis of the condenser lens 202. Further, a hole 203a is formed in a part of the visible light separation mirror 203 so that a part of the light beam emitted from the slag liquid surface 18a can pass therethrough. Further, a visible light refraction mirror 204 is disposed at a position facing the visible light separation mirror 203, and the visible light incident thereon is refracted in a direction substantially orthogonal to the incident light. A visual recognition window 211 is provided on the upper surface of the housing 201, and the slag liquid surface 18a can be easily visually recognized from the visual recognition window 211, and the hole 203a, that is, the temperature measurement location can be accurately confirmed as a black spot.

On the other hand, a beam splitter 205 is provided on the downstream side of the optical path of the housing 201 so that light that has passed through the hole 203a is incident thereon. The beam splitter 205 distributes the incident infrared light into two or more light beams, transmits one infrared light, and reflects the other infrared light in a direction orthogonal to the incident light. A first thermopile 208 and a second thermopile 209, which are light detection elements, are disposed on the optical path of the distributed infrared light, and infrared light in a specific wavelength region is disposed in front of each light traveling direction. A first band-pass filter 206 and a second band-pass filter 207 that transmit only the light are provided. The first and second band pass filters 206 and 207 transmit only infrared light in two different wavelength ranges. These bandpass filters are preferably set by selectively using infrared light in a wavelength region that is not absorbed by the furnace gas. Preferably, the wavelength range selected by the first and second band pass filters 206 and 207 is preferably a different wavelength range within the range of 8 to 14 μm.
The voltage signals detected by the first and second thermopiles 208 and 209 are transmitted to the signal processing device 210, and the slag temperature is calculated from the output voltage ratio of the obtained two voltage signals.

Thus, in the present embodiment, the measurement visual field can be accurately confirmed while measuring the temperature of the slag liquid surface 18a.
According to the present embodiment, since one optical axis is separated by using the beam splitter 205, there is almost no measurement error due to the temperature distribution of the object and the attached matter. In addition, because it does not use pyroelectric elements, it does not become unstable due to fluctuations in the chopping motor, improving measurement stability, and enabling measurement with the response time of the thermopile itself, resulting in rapid temperature changes. You can follow. Furthermore, since the visible light separation mirror 203 having the hole 203a is used, the measurement visual field can be easily confirmed.

Next, an operation method of the plasma ash melting furnace 10 will be described with reference to FIG.
First, current operation data of the ash melting furnace is collected from the various measuring instruments (S1). As the operation data, ash input (main ash, fly ash), power supply, fly ash mixing ratio, slag temperature, amount of cooling water in the tap or furnace body, cooling water temperature, refractory brick temperature, in-furnace Examples include temperature, current, voltage, and the like. The remaining amount of refractory bricks is predicted based on at least one of these operation data (S2). At this time, when the remaining amount of the refractory brick is predicted based on the slag temperature, it is preferable to use the slag thermometer shown in FIG. If a slag thermometer is not installed, the amount of ash input (main ash, fly ash), power supply, fly ash mixing ratio, slag temperature, tap water or each cooling water amount of the furnace body, cooling water temperature, fire resistance The slag temperature may be estimated by any one or more of brick temperature, furnace temperature, current, voltage, and post-slag slag temperature (two-color thermometer measurement).

When predicting the remaining amount of refractory bricks based on the slag temperature measured by the slag thermometer, first, the refractory surface temperature is estimated by Equation (6) (described in Example 3). Then, the erosion rate of the refractory is calculated using the equation (5) (described in Example 3), and the erosion amount of the refractory is obtained by integrating the erosion rates, and this erosion is determined from the initial value of the refractory brick thickness. The remaining amount of refractory bricks is obtained by subtracting the amount.
Moreover, when estimating from driving | running | working data, without installing a slag thermometer, slag temperature is estimated from ash injection amount and electric power, for example using Formula (12) (described in Example 3), and slag temperature measurement is performed below. The erosion amount of the refractory is obtained by performing the same calculation as in the case.

Furthermore, an operation condition that satisfies the operation processing amount target, the operation day target, and the brick remaining amount safety standard is calculated from the predicted value of the remaining amount of refractory bricks and the current operation data, and an operation schedule is created (S3). At this time, the current operation data includes ash input (main ash, fly ash), power supply, fly ash mixing ratio, slag temperature, tap water or each cooling water amount and cooling water temperature of the furnace body, fire resistance Examples include brick temperature, furnace temperature, current, and voltage. At least one or more of these operation data is used.
Then, the melting furnace is operated and maintained based on the calculated operating conditions (S4).

Here, an example of the operating condition determination method of the plasma melting furnace will be described with reference to FIG.
First, an operation plan composed of a target value of ash input amount, a target value of operation time, a current residual amount of refractory bricks, and a target value of residual brick amount after operation are input (S11), and after operation from these input values The remaining amount of brick is calculated (S12).
Then, the remaining brick amount after operation and the target value of the remaining brick amount after operation are compared (S13), and if the calculated value is larger, the ash input amount pace and the reference power are notified (S14), Based on this, the furnace operation is performed. On the other hand, when the calculated value is smaller, the reference power is changed (S15), it is determined whether or not the reference power exceeds the lower limit value of the melting appropriate power (S16), and the reference power is larger. In step S12, the remaining brick amount after operation is calculated again. If the reference power is smaller, notification is made that operation under this condition is impossible (S17), and processing such as reviewing the operation plan is performed.

FIG. 4 shows an example of a method for calculating the post-operation brick residual amount. As shown in the figure, the ash input amount pace in the ash melting furnace is calculated from the target value (S21) of the ash input amount and the target value (S22) of the operation time (S23), and based on the ash input amount pace. The reference power is calculated (S24). Furthermore, in addition to the ash input amount pace and the reference power, the current brick remaining amount (S25) is input, and the predicted value of the brick remaining amount after operation is calculated from these (S26).
In this way, calculating the operating conditions that meet the safety standards for the remaining amount of refractory bricks and the operation days target from the remaining amount of refractory bricks and the current operation data, and by operating, the life of the refractory bricks is extended, and maintenance costs Can be reduced.

Next, the case where the operation method of the ash melting furnace which concerns on a present Example is performed using a remote monitoring system is demonstrated.
FIG. 6 shows a remote monitoring system equipped with an ash melting furnace according to Embodiment 2 of the present invention.
This remote monitoring system includes each plant 300A, 300B, 300C,... Equipped with a plasma ash melting furnace 10 and a monitoring terminal 30, and a management center 400 equipped with a monitoring server 40. The monitoring terminal 30 and the monitoring server 40 Are connected by a communication network 50 such as the Internet or a dedicated line. Further, when data is transmitted and received between the monitoring terminal 30 and the monitoring server 40, communication is performed via firewalls 31 and 41 and routers 32 and 42 for the purpose of communication control and information protection, respectively.

  As shown in FIG. 6, the internal configuration of the monitoring terminal 30 includes a communication unit 30 a that performs communication between networks such as a LAN in a plant, and communication with the monitoring server 40 via the communication network 50. A storage unit 30b that stores various operation data, an operation data collection unit 30c that acquires the operation data from the plasma ash melting furnace 10, and a display unit 30d that can display an operation plan such as an LCD or a CRT display. Yes. The operation data acquired from the plasma ash melting furnace 10 is the amount of ash input (main ash, fly ash), power supply amount, fly ash mixing ratio, slag temperature, tapping or each cooling water amount and cooling water of the furnace body. Examples include temperature, refractory brick temperature, furnace temperature, current, voltage, and the like. At least one of these operation data.

On the other hand, the internal configuration of the monitoring server 40 includes a communication unit 40a that communicates with the monitoring terminal 30 via the network 50, a database 40b that stores operation data accumulated from the monitoring terminal 30 of each plant, and the operation A calculation unit 40c for calculating an operation plan of the ash melting furnace from the data.
The calculation unit 40c has a function of calculating an operation plan such as replacement time, maintenance time, and cleaning time of the furnace members of each plasma ash melting furnace 10 based on the operation data.

FIG. 7 shows a flow of a melting furnace operation method using the remote monitoring system shown in FIG.
First, on the monitoring terminal 30 side, current operation data is collected from various measuring devices installed in the ash melting furnace (S31), and the collected operation data is transmitted to the monitoring server 40 via the communication network 50 ( S32).
The monitoring server 40 side receives the operation data (S33) and stores the operation data in the database 40b (S34). Then, necessary operation data is extracted from the database 40b, and the remaining amount of refractory bricks is predicted from the operation data (S35).

On the other hand, the monitoring terminal 30 transmits the operation plan targets such as the main ash and fly ash input amount, the operation days, etc. to the monitoring server 40, and the monitoring server 40 obtains the remaining amount predicted value obtained by the remaining amount prediction. Then, the operation condition satisfying the brick residual standard is calculated from the operation data and the operation plan target (S37). The calculated operating conditions are transmitted to the monitoring terminal 30 (S38), and the monitoring terminal 30 performs operation and maintenance of the plasma melting furnace based on the operating conditions (S39).
As described above, the maintenance cost can be further reduced by using the remote control system.

  Example 3 describes a method for predicting the remaining amount of refractory bricks from an erosion prediction formula based on the erosion mechanism using operation data of the ash melting furnace.

(Erosion mechanism of refractory bricks)
First, the mechanism of refractory brick erosion will be described. Here, erosion of refractory bricks mainly composed of SiC will be considered as an example. As shown in FIG. 8, the SiC refractory brick reacts with oxygen to become SiO ₂ (the following chemical reaction formula [1]), and then SiO ₂ reacts with CaO, Na ₂ O, and K ₂ O in the slag. Thus, it was assumed that CaSiO ₃ was generated (the following chemical reaction formula [2]), dissolved in slag, and SiO ₃ ²⁻ diffused into slag.
SiC + 0.5O ₂ → SiO ₂ [1]
CaO (Na ₂ O, K ₂ O) + SiO ₂ → CaSiO ₃ [2]

In this mechanism, the rate of erosion is diffusion of SiO ₃ ²⁻ , and the erosion rate equation of the refractory brick is expressed as the following equation (1).
Here, m is the dissolved amount, C ₀ is SiO ₃ ²⁻ saturation concentration in the slag, and C is SiO ₃ ^{2 in the} slag.
^- concentration, D is the diffusion coefficient, A is the reaction area, [delta] is the boundary layer thickness, t represents time.

(Diffusion coefficient)
The diffusion coefficient D of the equation (1) is expressed as the following equation (2) using the Arrhenius equation and is a function of temperature.
Where D is the diffusion coefficient, D ₀ is the frequency factor, E is the diffusion activation energy, R is the gas constant,
T represents temperature. As a result of conducting an erosion experiment using an electric furnace with respect to the relationship between the erosion rate and the temperature, it was found that the erosion amount increased with increasing temperature as shown in FIG. 9, and the activation energy of diffusion was experimentally grasped. In addition, since the viscosity of slag is also expressed by the following equation (3) using the Arrhenius equation, the activation energy E obtained from this experiment includes the effect of slag viscosity change due to temperature. Conceivable.
Here, μ represents the viscosity, _Aw represents a constant, _Ew represents the activation energy of the viscosity, R represents the gas constant, and T represents the temperature.

(concentration)
Contact surface between the refractory bricks and the slag 8 is a saturation concentration of SiO ₃ ^2-, it diffuses at a density difference between SiO ₃ ^{2-concentration} in the slag. Since the SiO ₃ ²⁻ concentration in the slag is determined by the basicity (= CaO / SiO ₂ ), in this embodiment, the SiO ₃ ²⁻ concentration in the slag is expressed by basicity, which is a general index representing ash and slag. It was to be. This basicity can be replaced by the mixing ratio of CaO and SiO ₂ . FIG. 12 shows the relationship between the basicity of the slag and the amount of erosion obtained from the erosion experiment. According to this, the amount of erosion increased as the basicity increased, and in this example, it was approximated as an exponential function and introduced into the erosion rate equation.

(Boundary layer thickness)
Although the boundary layer thickness is a function of the flow velocity, it is difficult to measure the slag flow velocity in the plasma ash melting furnace, so it is necessary to select a parameter in place of the flow velocity in practice. The ash supplied to the plasma ash melting furnace floats on the slag liquid surface (slag line) and melts. Therefore, when the ash treatment load increases, the amount of melting at the slag liquid surface increases and slag is processed from the slag liquid surface. The flow rate increases. When the slag flow velocity at the slag liquid surface increases, the boundary layer of the slag line, which is the contact portion between the refractory brick and the slag liquid surface, becomes thin, so that the diffusion rate increases. Therefore, in this example, the ash treatment load factor represented by the following formula (4) was selected as a parameter instead of the flow velocity.

Here, v is a processing load factor.
FIG. 13 shows the results of organizing the relationship between the ash treatment load factor and the erosion rate from the operation data and the erosion amount measurement data in the test furnace. The erosion rate increased with increasing ash treatment load factor. In this example, it was approximated as an exponential function and introduced into the erosion rate equation. According to the literature (Hirotaka Shintani, Ikuo Kawakami, “Erosion of fused quartz refractory bricks with CaO-Al ₂ O ₃ —SiO ₂ system slag”, Journal of Ceramic Industry Association VoL94No.11 (1986), P1183-1185), Although it is reported that the flow rate of slag is proportional to the power of 0.5 to 0.7, the results of this experiment show a larger change, and the boundary layer becomes extremely thin due to the entrainment (stripping) effect. Possible possibility.

(Erosion rate formula)
Based on the erosion mechanism of the refractory brick with rate limiting diffusion of SiO ₃ ^2−, the erosion rate equation shown in the following equation (5) was created using the operating parameters of the plasma ash melting furnace.
Here, A, B, and C are constants, T is the refractory brick surface temperature, E is the activation energy, v is the processing load factor, η is the basicity, x is the amount of erosion, and t is the time. The influence of slag basicity and activation energy was determined from erosion experiments using a plasma ash melting furnace, and the influence of flow velocity was determined from the results of actual erosion measurements.

The refractory brick surface temperature T was estimated using the slag temperature by the following equation (6) using a one-dimensional heat passage model.
Here, T _s is the slag temperature, T _w is the water temperature, α _sr is the heat transfer coefficient of the slag and the refractory brick, λ is the heat conductivity of the refractory brick, and the subscripts 1 and 2 are the types of the refractory brick. . The heat transfer coefficient α _sr of the slag and refractory brick was obtained from the temperature measurement result in the actual furnace.

(Measurement of slag temperature)
In order to obtain the refractory brick surface temperature T, a method using the slag temperature is described in this embodiment, but since slag is high in temperature and very erosive, continuous measurement with a thermocouple is difficult. Therefore, in this embodiment, a slag thermometer that can minimize the influence of dust is used. Since a commercially available two-wavelength radiation thermometer has a wavelength of about 1 μm and cannot throw a high dust atmosphere in the furnace, far-infrared light is detected in this embodiment.
FIG. 10 shows a schematic view of a slag thermometer used in the third embodiment. The slag thermometer 20 includes a bandpass filter 220 and a sensor 221, detects far-infrared light radiated from the slag surface 18 a, and the energy intensity in the two wavelength ranges in accordance with Planck's energy radiation law for each temperature. Is used to estimate the temperature from the energy ratio of the two selected wavelengths, and can be calculated by the following equation.

Here, ε is the emissivity of the slag, E (T) is the intensity of the radiation from the black body at the temperature T, τ is the transmittance, Ts is the slag temperature, and the suffixes λ ₁ and λ ₂ are the wavelengths.
In order to confirm the transmission characteristics of the infrared light emitted from the slag surface 18a in the dust atmosphere and the transmission characteristics in the gas atmosphere, the light from the slag liquid surface 18a was dispersed using Fourier transform infrared spectroscopy. During the non-ash treatment, no dust or infrared absorbing gas is generated, and all infrared light emitted from the slag liquid surface 18a is transmitted. FIG. 11 shows the measured transmittance (permeation intensity during ash treatment / permeation intensity during non-ash treatment). As shown in the figure, it is clear that the transmittance is 0.9 or more in the wavelength range of 8 to 15 μm, and is hardly affected by dust in the furnace or gas absorption. Therefore, in the slag thermometer according to the present embodiment, it is preferable to use infrared light in the range of 8 to 15 μm.

Moreover, the method to estimate slag temperature by heat balance is shown. Although the slag liquid surface temperature can be measured by a slag thermometer, a measurement error may occur due to the permeation window becoming cloudy due to factors such as salt adhering to the permeation window for measurement. Therefore, the slag temperature at the tap outlet was estimated using the balance between heat input and output heat of the plasma melting furnace, and the reliability of the slag temperature was improved by comparing with the measured slag temperature. The heat input of the plasma melting furnace is electric power, and the output is an amount of heat for melting ash and a furnace body cooling heat power. The slag temperature T _s obtained from the heat balance is a steady-state slag temperature on the balance obtained from the ash input amount and the electric power, and can be expressed as the following formula (8).

Here, Q _p is power, H is enthalpy of ash, the C _p specific heat of the ash, M ash processing speed (or ash throughput), Q _r denotes the furnace body method heat. For measurements at a high temperature of H and C _p is the thermal properties of the ash is difficult, it was determined by comparing the slag temperature measurements. Since equation (8) is composed only of the operating conditions of the plasma melting furnace, it is not necessary to newly install a measuring device, and a practical slag temperature can be estimated.

In the operation of the test furnace, when the temperature of the slag liquid surface 18a near the tap outlet measured by the slag thermometer and the tap outlet slag temperature estimated from the heat balance using the operation data are compared, the two are in a state of fluctuation, etc. Are almost the same. However, during long-term continuous operation, there may be an error in the temperature measurement value by the slag thermometer due to deposits on the measurement hole and dirt on the window, so it is possible to detect the error by using both at the same time. It becomes. In addition, when the ash properties change, the thermal properties of the ash change, so an error may occur in the slag temperature estimated from the heat balance, and this error can be detected by using it together with the slag thermometer. It becomes.
As described above, in the slag temperature measurement of the present embodiment, it is possible to perform accurate temperature measurement by using the two types of temperature measuring means in combination, and in the case where an error occurs, by pursuing the cause of the error, It is possible to grasp the malfunction.

(Fire brick erosion prediction)
Using the erosion rate equation (the above equation (5)), the erosion amount in the operation of the test furnace was estimated. The erosion rate equation was estimated using both the measured value of the developed slag thermometer and the slag temperature estimated from the heat balance. FIG. 14 shows the change over time in the amount of erosion. The predicted erosion amount was in good agreement with the erosion amount measured after operation, and the validity of the erosion rate equation using the slag temperature measured by the slag thermometer and the slag temperature estimated from the thermal balance could be confirmed.

(Erosion speed and operating conditions)
FIG. 15 shows changes over time in operating conditions and erosion rates in the operation of the test furnace. When slag temperature rises, refractory brick erosion progresses, and to suppress refractory brick erosion, it is considered effective to lower slag temperature by lowering power when slag temperature rises. . In addition, when the ash is not treated, it hardly erodes, and when the operation cannot be stopped due to the schedule of repair work, etc., it is possible to extend the life of the refractory brick by reducing the amount of ash input. It is.

(Calculation of remaining refractory bricks)
The calculation formula for the remaining amount of refractory bricks in the plasma melting furnace is obtained by the following formula (9).
Here, input parameters: initial brick thickness, erosion amount: erosion amount per hour (mm).
The calculation formula for the amount of erosion is shown below. The input data is only the power and ash input amount, and the rest is a coefficient, and the coefficient is changed by adjustment. The calculation cycle is 1 hour and is stored in the database sequentially.

The following equation (10) is used for the erosion rate equation.
Here, A, B, C and D are coefficients, T _r [° C.] is the refractory brick temperature, v [kg / m ² h], η and η ₀ [−] are basicity.

The refractory brick surface temperature was considered as one-dimensional heat conduction, and was calculated by the following equation (11).
Here, T _r [° C.] is the brick surface temperature, T _s [° C.] is the slag temperature, T _w [° C.] is the water temperature, and α _sr [kcal / m ² h ° C.] is the heat transfer coefficient between the slag and the refractory brick. , Α _w [kcal / m ² h ℃] is the water heat transfer coefficient, λ _r [kcal / mh ° C] is the refractory brick thermal conductivity, λ _s [kcal / mh ° C] is the stamp thermal conductivity, x _r [m ] Is the brick thickness and x _s [m] is the stamp thickness.
Further, the processing load factor is calculated by the above equation (4).

Further, the calculated slag temperature is expressed as in the following equation (12). This is the slag temperature on the balance calculated from the ash input and power.
Where Q _p [kW] is electric power, H _f [kcal / kg] is ash latent heat, C _p [kcal / kg ° C.] is ash specific heat, T _s [° C.] is calculated slag temperature, M [t / h] Is the amount of ash input, Q _g [kWh / t] is the amount of heat exhausted from the exhaust gas, Q _r [kW] is the amount of heat for cooling the furnace body, and T _s0 [° C.] is the slag temperature constant.

Here, Table 1 shows test furnace data in which the remaining amount of the plasma melting furnace shown in FIG. 1 is predicted using the remaining amount prediction method according to the present embodiment.
Thus, the slag temperature is a slag surface temperature measured using a radiation thermometer. Moreover, the erosion rate was calculated by the said Formula (10), and the refractory brick residual prediction value was calculated by the said Formula (9). From the values obtained from these equations, the remaining amount of brick can be obtained easily and accurately.

It is a sectional side view of the plasma ash melting furnace which is one Example of the ash melting furnace to which this invention is applied. It is a flowchart which shows the operating method of the ash melting furnace which concerns on Example 1 of this invention. It is a flowchart which shows the method of determining an operating condition in the driving | running method of FIG. It is a flowchart which shows the calculation method of the firebrick remaining amount in the present Example 1. FIG. It is a schematic sectional drawing which shows an example of the slag thermometer used for the furnace operation of this invention. It is a whole block diagram which shows the remote monitoring system which comprised the ash melting furnace which concerns on Example 2 of this invention. It is a flowchart which shows the driving | operation method using the remote monitoring system of the present Example 2. It is explanatory drawing which shows the erosion process of the refractory brick containing SiC. It is a graph which shows the relationship between slag temperature and the erosion rate of a refractory brick. It is the schematic of the radiation thermometer used for the present Example 3. It is a graph which shows the permeation | transmission characteristic of the infrared light in a dust atmosphere and gas atmosphere. It is a graph which shows the relationship between the basicity of slag and the erosion amount of a refractory brick. It is a graph which shows the relationship between the processing load factor of ash, and the erosion rate of a refractory brick. 6 is a graph showing a change with time of an estimated erosion amount calculated from an erosion rate equation shown in Example 3 and a measured value of the erosion amount in a test furnace. It is a graph which shows the time-dependent change of the operating condition and erosion rate in a test furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Plasma melting furnace 11 Furnace main body 13 Main electrode 14 Furnace bottom electrode 15 DC power supply 16 Ash inlet 17 Outlet 18 Molten slag 19 Measurement opening 20 Slag thermometer 21 Thermocouple 40 Management server 40b Database 50 Communication network

Claims (5)

A current is passed between the anode and cathode electrodes arranged in the furnace body to generate a plasma arc in the furnace, and the main ash and fly ash are melted by the plasma arc heat or the Joule heat of the current flowing between the electrodes. In the ash melting furnace to be processed, in the method for predicting the remaining amount of refractory for predicting the remaining amount of refractory lining the furnace inner wall of the ash melting furnace,
First estimating means for detecting far-infrared light in a two-wavelength region radiated from the molten slag liquid surface in the furnace and estimating a molten slag temperature based on the detected infrared light;
In order to cool the furnace body, the heat dissipation amount of the furnace body is calculated from the cooling water amount and the cooling water temperature flowing through the inside of the furnace body, the calculated heat dissipation amount of the furnace body and the ash input amount per hour, between the electrodes Second slag temperature estimating means for estimating the molten slag temperature using the thermophysical equation of ash from the input power of the power source applied to
A third molten slag temperature estimating means for obtaining a slag resistance from the current and voltage flowing between the electrodes and estimating a molten slag temperature from a temperature characteristic of the slag resistance;
A fourth molten slag temperature estimating means for estimating the refractory surface temperature from the furnace temperature based on the correlation between the furnace temperature and the refractory temperature;
Obtain the refractory surface temperature from the estimated molten slag temperature obtained from any one or more of the estimation means,
The amount of erosion at the contact surface between the refractory brick and the slag in the furnace is determined by the basicity of the slag formed by replacing the fly ash mixing ratio corresponding to the ratio of CaO and SiO ₂ ,
As a parameter to replace the slag flow velocity in the ash melting furnace corresponding to the boundary layer thickness of the slag liquid level, the ash treatment load factor (ash treatment amount / reference ash treatment amount) is obtained.
Based on the refractory surface temperature, basicity, and processing load factor obtained above, calculate the erosion rate of the refractory,
Based on the initial value of the refractory and the erosion rate, the remaining amount of refractory is predicted ,
The refractory estimated based on the following one-dimensional heat passage model equation (Equation 6) from the estimated molten slag temperature obtained from any one or more of the first estimating means to the fourth melting slag temperature estimating means The erosion rate of the refractory is calculated from the following erosion rate equation (Equation 5), in which the basicity and the processing load factor are added as correction factors.
A method for predicting a residual amount of a refractory, comprising predicting a residual amount of a refractory based on an initial value of the refractory and the erosion rate.
One-dimensional heat passage model formula (Formula 6).
T _s : slag temperature, T _w : water temperature, α _sr : heat transfer coefficient between slag and refractory brick (heat transfer coefficient α _sr between slag and refractory brick was obtained from temperature measurement result in actual furnace), λ: fire resistance Brick thermal conductivity, subscripts 1, 2: Refractory brick type (erosion rate formula)
A, B, C: constant, E: activation energy, v: treatment load factor, η: basicity, x: erosion amount, t: time   The slag temperature is measured by a two-wavelength thermometer that detects far-infrared light in a two-wavelength region radiated from the slag liquid surface and calculates the slag liquid surface temperature based on the detected far-infrared light. The method for predicting the remaining amount of refractory as described. A current is passed between the anode and cathode electrodes arranged in the furnace body to generate a plasma arc in the furnace, and the main ash and fly ash are melted by the plasma arc heat or the Joule heat of the current flowing between the electrodes. In the operating method of the ash melting furnace to be processed,
An operation data collection step for collecting operation data of the ash melting furnace;
Remaining amount prediction step defined in "Method for predicting remaining amount of refractory" according to claim 1, wherein the remaining amount of refractory is predicted based on the operation data;
An operation condition step for deriving an operation condition from the remaining amount of the refractory and the operation data;
And a step of operating the ash melting furnace based on the operating conditions. Wherein in the operating condition step, and refractory residual amount that the predicted, preset refractory claim 3 Symbol mounting method of operating ash melting furnace is characterized in that to guide the operating conditions than the remaining reference values. The operation method of the ash melting furnace according to claim 3, comprising a monitoring terminal provided in the ash melting furnace, and a monitoring server connected to the monitoring terminal via a communication network,
The monitoring terminal performs the operation data collection step, transmits the collected operation data to the monitoring server, and performs the remaining amount prediction step and the operation condition step based on the operation data received by the monitoring server. Then, the derived operating conditions are transmitted to the monitoring terminal, and the ash melting furnace is operated based on the operating conditions at the monitoring terminal.