JPH01278596A - Control method of furnace temperature of coke oven - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the furnace temperature of a coke oven, and in particular, the present invention relates to a method for controlling the furnace temperature of a coke oven. The present invention relates to a furnace temperature control method for so-called programmed heating operation in which the amount of heat supplied (fuel gas flow rate) is changed according to the furnace temperature pattern.

[Prior art] In a coke oven, the set furnace temperature pattern of the combustion chamber for each period of the carbonization process is determined based on the firing time, the furnace temperature, and charging specifications such as the amount of charged coal and its moisture content. A program heating method has been proposed in which the amount of heat supplied (fuel gas flow rate) is controlled using this as a target value.

The coke oven heating control method described in JP-A-59-20379 and the coke-oven fire-off time and outlet temperature control method described in JP-A-61-47791 are one of the program heating methods. This is a method previously proposed by the applicant.

However, in this program heating method, as in the case of the conventional coke oven oven group average furnace temperature control method, the furnace temperature of the combustion chamber is determined by the carbonization state of both side coking chambers (the elapsed time from the coal charging time). In addition, there is a large response delay between the fuel gas flow rate and the furnace temperature in the combustion chamber. A method has not yet been established.

[Object of the Invention] In performing the above programmed heating, the present invention predicts the future set furnace temperature by a response delay time, and feeds back the estimated value of the state quantity of the furnace temperature process obtained by a finite time settling observer. By controlling the set value of the fuel gas flow rate control system, fluctuations in the fuel gas flow rate are minimized, hunting of the controlled furnace temperature is prevented, and response delay time of the controlled furnace temperature to changes over time in the set furnace temperature pattern is minimized. The present invention provides a method for keeping the controlled furnace temperature at a set furnace temperature while minimizing the temperature.

[Structure and operation of the invention]

That is, the present invention provides a method for operating a coke oven in which a predetermined oven temperature pattern of a combustion chamber used in a carbonization process is determined based on operating conditions and charging specifications of the coke oven.
Response delay time between the fuel gas flow rate and the furnace temperature of the combustion chamber, a finite time settling observer that estimates the state quantity of the furnace temperature process using the fuel gas flow rate and the furnace temperature of the combustion chamber, and feedback of the estimated state quantity. The operating term and the integral operating term as the forward-facing element of the main loop are determined in advance, and the atmospheric temperature (furnace temperature) of the combustion chamber is detected by multiple PR thermocouples installed at the top of the hairpin part of the combustion chamber, and the average value is calculated. The control furnace temperature is determined by data processing to smooth the change over time, the future set furnace temperature is predicted by the response delay time, and the state quantity of the furnace temperature process obtained by the finite time settling observer is calculated. By feeding-hacking the estimated value and controlling the set value of the fuel gas flow rate control system, the response delay time of the controlled furnace temperature to changes over time in the set furnace temperature pattern is minimized, and the controlled furnace temperature is maintained at the set furnace temperature. This is a coke oven furnace temperature control method characterized by the following.

When performing the above furnace temperature control, a dead band and dead band output JG upper and lower limiters are provided for the set value correction amount of the fuel gas flow rate control system to minimize fluctuations in the fuel gas flow rate and prevent hunting in the controlled furnace temperature. This is a coke oven furnace temperature control method characterized in that the controlled furnace temperature is maintained at a set furnace temperature.

The present invention will be explained in detail below. FIG. 1 is a diagram showing an example of a control configuration diagram of a furnace temperature control system of a coke oven according to the present invention. The set furnace temperature pattern of the combustion chamber for each hour of the carbonization process is determined based on charging specifications such as fire-off time, kiln outlet temperature, amount of charged coal and its moisture content, and this is used as a target value in the present invention. The fuel gas flow rate is controlled using the furnace temperature control method. The method of determining this set furnace temperature pattern was described in the above-mentioned Japanese Patent Application Laid-open No. 5
The methods described in No. 9-20379 and Japanese Unexamined Patent Publication No. 61-47791 can be used.

Control furnace temperature (output) for step input of fuel gas flow rate
The response exhibits an S-shaped step response without excess as shown in FIG. As shown in Figure 2, the increase in step response y (k) for each sampling period is expressed as g++
gz+ ...+gn 1gn'l+ gn. 2゜・
..., then the pulse transfer function of the system is "gn+
lZ-""'-1-g,,2Z-(n+21+,,.

...... (1) It is expressed as an infinite series. Here, after n samples, the increase is g at a constant ratio, t=n+1. Approximately, when n+2゜... decreases, and the attenuation ratio is P, the pulse transfer function is: G(Z)=g+Z-'±gzZ-2+...+gn-+
Becomes Z-south n-11. Here, if the steady-state key of the process is G(1), P is given by the following P as a solution to equation (2).

Also, the following P2 is given as P.

P,; The degree of P2 is expressed as e-l(PI P2)l/PI. In this case, n is set so that e is a predetermined limit (for example, e−O,
05) Decide from reaching the target and P at that time.

(or P2) as P.

Therefore, the equation of state for the system is y(k+1)
−A ・y(k) + h −u(k)
--(5) However, the output equation is y (k) −c−x(k) ・
...(7) However, c=(1000...00] ...
...(8). Here, y(k) is xt(k)
, xz(k) , −x, , (k) (5)
The state variable inside the model of the equation is H, u (k) is the setting value of the fuel gas flow rate control system as the manipulated variable, and y (k) is
is the controlled furnace temperature as output.

For the controlled objects (5) and (7), the following objective function J
−Σ(yr−y(k))2+ ω・(u(k)−u (
k-1))2)...(9) yr: Set furnace temperature, 01 Find the optimal operation amount that minimizes the weighting coefficient. Introducing as a new state variable, y(k+1) −P −y(k) + tB Δ
u(k)...(11) However, when converted as follows, the objective function in (9)2 becomes J ='
W′(k) ・W −”;(k)+ω(Δu(k
)) 21...03) w=c" ・C. The feed hack gain ■ that minimizes this is
It is given by the Rica Sochi equation% formula%. Therefore, the optimal correction amount Δu (k) of the set value of the fuel gas flow rate control system is given by the following equation by introducing the response delay time.

Δu (k) Fortune (yr(k→L)−y(k))−綽−
+(x7(k) Therefore, a process model is incorporated into the control algorithm, and the estimated value of the state variable hector y (k) 9 (
Find k). For this purpose, formulate the following formula.

Q(k+1)−n(k+1)+1(y(k+1)
−c−r(k+1) 1...θ force However, y'(k44) is calculated as follows9
(k+1) is an a priori estimated value.

9°(k+1)−8・Q(k)+l−(△u(k)
The coefficient hector f of 10u (k-1))...08) (+7)2 is the control furnace temperature y (k+1
), which is the observer gain that corrects 9°(k+1), and the coefficient hector that provides a finite time settling observer is found as follows.

fT=[lPP2...P'' publication]...
...09) The response delay time between the fuel gas flow rate and the controlled furnace temperature is determined by approximating the step response shown in Figure 2 by (dead time 10-order delay element), and then calculating the dead time as the response delay time. Set as the initial value of time, calculate the cross-correlation function between the set furnace temperature and the controlled furnace temperature from the control results, and set the delay time τ at which the correlation function reaches its peak. Using the following formula, correct the response delay time and determine.

r-=L O+ T O--Q (11 or more determines the feed hack loop structure and control law of the furnace temperature control system.

Next, from the perspective of protecting the furnace body, the amount of correction of the set value of the fuel gas flow control system is determined in order to minimize fluctuations in the fuel gas flow rate, prevent hunting in the controlled furnace temperature, and ensure furnace temperature control accuracy. A dead band is provided for the output, and an upper and lower limiter is provided for the dead band output. The dead zone is determined so that when the amount of correction of the set value of the fuel gas flow rate control system is small and falls within the dead zone width, this coincides with the case where the control deviation of the furnace temperature is also small and stable.

Further, the limit between set value corrections by the upper and lower limiters is determined to be the same as the set value correction amount in traditional fuel gas flow rate-amount control, which is a conventional general method.

Figure 3 shows the steps of the furnace temperature control method described above in a diagrammatic form. First, calculate the average value of the combustion chamber atmospheric temperature (furnace temperature) detected by multiple PR thermocouples installed at the top of the hairpin part of the combustion chamber. , and the moving average value of the past combustion cycle time is set as the control furnace temperature.

With the finite time settling observer ((17), 09) 2),
The pre-estimated state value is corrected using the controlled furnace temperature, and the corrected estimated value is used as the estimated value of the state quantity of the furnace temperature process.

The preset response delay time and future set furnace temperature are predicted, and the amount of correction of the set gas amount of the fuel gas flow control system is calculated using formula 00 using the estimated values of the current and previous state variables and the controlled furnace temperature. , the amount of correction is limited by a dead zone and upper and lower limiters.

The set gas amount is input from the fuel gas flow rate control system, the set gas amount is determined using the above-mentioned correction amount, and is output to the fuel gas flow rate control system. The process model (08
) is estimated using the following formula.

The furnace temperature of the coke oven is controlled by controlling the fuel gas flow rate based on the deviation between the set gas amount and the actual measurement value.

[Effects of the Invention] Figures 4(a) and 4(b) show an example of the results of an operation carried out according to the present invention as described below.

FIG. 4(a) shows the control results for a set furnace temperature pattern that is constant over time.

When the fuel gas flow rate is constant under the conditions of continuous charging (1→2→3→...charging) of a coke oven, the wood furnace temperature fluctuates by about 180'C during the carbonization cycle. When the control method was implemented, the control deviation was very stable at about ±8°C, and the amount of heat consumption could be reduced by about 6%.

FIG. 4(b) shows the control results for the set furnace temperature pattern that changes over time.

The delay in response of the controlled furnace temperature to changes over time in the set furnace temperature pattern was extremely small, and the controlled furnace temperature was kept at the set furnace temperature and stable, and the amount of heat consumed could be reduced by about 10%.

As described above, the furnace temperature control according to the present invention has the unique effect of providing extremely stable coke oven operation as shown in FIG. 4.

[Brief explanation of the drawing]

Figure 1 is a control configuration diagram of the furnace temperature control system, Figure 2 is a diagram showing the step response of the controlled furnace temperature to the fuel gas flow rate, Figure 3 is a flowchart showing the procedure of the furnace temperature control method, and Figure 4 is the furnace temperature control system. FIG. 3 is a diagram showing the results of operation under temperature control.

Claims (1)

[Claims] 1. In a coke oven operation in which a set furnace temperature pattern of a combustion chamber in a carbonization process is predetermined based on the operating conditions and charging specifications of the coke oven, the fuel gas flow rate and the furnace temperature of the combustion chamber are A finite time settling observer that estimates the state quantity of the furnace temperature process using the response delay time between the temperature and the fuel gas flow rate and the furnace temperature of the combustion chamber, a feedback operating term of the estimated state quantity, and a forward-looking element of the main loop. An integral operating term is determined in advance, and the atmospheric temperature (furnace temperature) of the combustion chamber is detected by multiple PR thermocouples installed above the hairpin part of the combustion chamber, the average value is determined, and its change over time is smoothed. The control furnace temperature is obtained by processing the data to determine the control furnace temperature, predicting the future set furnace temperature by the response delay time, and feeding back the estimated value of the state quantity of the furnace temperature process obtained by the finite time settling observer. A coke oven characterized in that the control furnace temperature is maintained at the set furnace temperature by minimizing the response delay time of the controlled furnace temperature to the temporal change in the set furnace temperature pattern by controlling the set value of the flow rate control system. Temperature control method. 2. When performing the above furnace temperature control, upper and lower limiters are provided for the dead zone and the dead zone output for the set value correction amount of the fuel gas flow rate control system to minimize fluctuations in the fuel gas flow rate and prevent hunting in the controlled furnace temperature. A coke oven furnace temperature control method characterized in that the controlled furnace temperature is maintained at a set furnace temperature.