JPH06264062A - Operation of coke oven dry quencher - Google Patents

Abstract

PURPOSE:To provide a CDQ operation method which does not suffer from control delay by making an allowance for the delay required when controllable factors such as the amount of cut coke, the amount of combustion air and the amount of water poured into a prechamber influence on objective functions such as the gas temperature at the inlet of a waste heat boiler and the amount of recovered steam. CONSTITUTION:By using a model in which the controllable factors include at least the amount of cut coke, the amount of combustion air and the amount of water poured into a prechamber, and an allowance for the extent of the influence of these factors on the amount of recovered steam as an objective function and the delay before this influence is made, at least the amount of cut coke, the amount of combustion air and the amount of water poured into a prechamber are controlled by feed forward control so that the largest possible amount of steam in the given state of operation may always be obtained even when the state of operation of the coke oven dry quencher changes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a coke oven dry fire extinguishing system (hereinafter referred to as CDQ), and more particularly, to a control delay in consideration of a delay time until a control factor affects an objective function. There is no CDQ operating method.

[0002]

2. Description of the Related Art Instead of spraying and extinguishing the red hot coke discharged from a coke oven, the sensible heat of the red hot coke can be recovered, dust can be prevented from scattering, and the coke strength can be improved and the water content can be reduced. C with the advantages of
DQ is used.

In this CDQ, for example, as shown in FIG. 1, a prechamber 12 into which red hot coke discharged from a coke oven (not shown) is charged from a coke bucket, for example.
And a cooling chamber 16 for cooling the red hot coke that sequentially descends from the pre-chamber 12 by contacting it with a circulating cooling gas composed of an inert gas such as nitrogen blown from below by a blower 14, and the cooling chamber 16 It has a fire extinguisher 10 from which the coke cooled by is discharged from below.

On the other hand, the circulating gas which has reached a high temperature due to contact with the red hot coke is dedusted by the dust remover 20, introduced into the waste heat boiler 22, cooled by exchanging heat and then again by the cyclone 24, for example. Dust is removed and blown into the cooling chamber 16 by the blower 14.

Heated in the waste heat boiler 22,
The high temperature, high pressure recovered steam is sent to a turbine generator or the like (not shown).

In this CDQ, the coke cutout amount is set so that the coke level in the pre-chamber 12 maintains a predetermined level.

On the other hand, since the coke oven kiln removal work is continuously performed, one kiln worth of red hot coke is introduced into the pre-chamber 12 at a predetermined introduction pitch during the kiln removal work.
However, while the kiln removal work was suspended, no red hot coke was added.

Therefore, during the kiln removal operation, the supply air introduction valve 26 blows combustion air into the upper part of the fire extinguishing tower 10 to burn the combustible gas mixed in the circulation gas and raise the temperature of the circulation gas. In addition to suppressing the decrease in the amount of recovered steam, the concentration of combustible gas in the circulating gas is decreased outside the explosion limit.

The operation factors in such CDQ are mainly the amount of combustion air introduced from the supply air introduction valve 26, the amount of pre-chamber water for pouring water into the pre-chamber 12 for cooling, and the inside of the pre-chamber 12. The amount of coke cut-out for controlling the coke level is, but when each is increased or decreased, both the inlet gas temperature of the waste heat boiler 22 and the specific heat of the circulating gas change, and therefore the recovered steam also increases or decreases. Moreover, these response times are different from each other.

The CDQ operator controls three factors, that is, the combustion air amount, the pre-chamber water injection amount, and the coke cut-out amount so as to always obtain the maximum amount of recovered steam.

As a conventional control method, as shown in, for example, Japanese Patent Laid-Open No. 3-157485, the amount of residual combustible gas in the red hot coke, the amount of combustible gas in the circulating gas at the entrance of the fire extinguishing tower, and the current blowing are used. A method has been proposed in which the optimum combustion air amount is predicted and calculated from the combustion air amount, and the combustion air amount is automatically controlled.

Further, in Japanese Patent Application Laid-Open No. 3-9988, the amount of C in the circulating gas is changed from the fluctuations of the pitch of charging red hot coke, the amount of coke stock in the prechamber, and the amount of coke discharged from the lower part of the cooling chamber.
A method of estimating the amount of combustible gas such as O and H2, and feed-forward controlling the amount of combustible gas to the circulating gas suction section below the prechamber so that the concentration of the combustible gas in the circulating gas is minimized. Is proposed.

[0013]

However, in all of the above-mentioned conventional methods, the combustion air amount, which is a control factor,
When the amount of coke cut out is increased or decreased, the delay time until it affects the waste heat boiler inlet gas temperature, the circulating gas specific heat and the amount of recovered steam is not considered, so a time lag occurs, for example, the combustion air amount. If it becomes excessive, O ₂ will be present in the circulating gas and there is a risk of explosion. or,
Even when there is sufficient combustible gas and O ₂ does not exist, the waste heat boiler inlet gas temperature exceeds the control value upper limit, and the boiler tube life is shortened. Further, there is a problem that the amount of recovered steam fluctuates due to a delay in the control of the amount of combustion air, which is not preferable in terms of energy supply and demand balance.

The present invention has been made to solve the above-mentioned conventional problems. Control factors such as the amount of coke cut out, the amount of combustion air, and the amount of water injected into the prechamber are controlled by the waste heat boiler inlet gas temperature and the recovered steam. It is an object of the present invention to provide a CDQ operating method with no operational delay in consideration of the delay time until it affects the objective function such as the quantity.

[0015]

According to the present invention, in the CDQ operating method, at least the coke cutting amount, the combustion air amount, and the prechamber water injection amount are used as control factors, and each of these factors becomes a recovery vapor amount of the objective function. Even if the operating condition of the coke oven dry fire extinguishing equipment changes, the maximum recovery steam amount under that operating condition is always obtained by using a model that considers the magnitude of the effect and the delay time until the effect appears. As described above, the above object is achieved by feed-forward controlling at least the coke cut-out amount, the combustion air amount, and the pre-chamber water injection amount.

[0016]

In order to solve the above problems and find an operating method for obtaining the maximum amount of steam, the present invention shows factors affecting the amount of steam, such as the pre-chamber water injection amount and the combustion air amount, as shown in FIG. The CDQ operation model as shown was constructed and the operation analysis was performed. In the figure, ST is the amount of recovered steam, V is the circulating gas amount, BIT is the boiler inlet gas temperature, GCP is the specific heat of the circulating gas, T / H is the amount of coke cut out, PT is the prechamber temperature, and AIR is the input (combustion) air. Volume, WAT is the prechamber water injection volume, W is the prechamber inventory volume, a _i is the sensitivity constant, τ _i is the delay time, ε ₁ is a factor representing the state of coke burn-off, ε ₂ is the input coke temperature, AIR and WAT is the controlling factor.

Here, the recovered steam amount ST is determined by the circulating gas amount V, the boiler inlet gas temperature BIT and the circulating gas specific heat GPC, and the boiler inlet gas temperature BIT is the coke cutting amount T / H and the pre-chamber. It is determined by the temperature PT and the combustion air amount AIR, and the circulating gas specific heat GCP is determined by the prechamber water injection amount WAT, the combustion air amount AIR, and the factor ε ₁ representing the coke burn-off state.

The sensitivity constant, which indicates the magnitude of the influence of each of these factors on the dependent variable, and the delay time until the influence appears are different. Therefore, an experiment was conducted focusing on one of the above factors and changing the manipulated variable. At that time, factors other than the coke burn-off state ε ₁ and the input coke temperature ε ₂ were set constant. Since it is difficult to keep ε ₁ and ε ₂ constant, these were regarded as disturbances.

Next, the obtained set data is sequentially shifted (with a time delay) and a regression analysis is performed to find the delay time when the correlation coefficient R is maximum and the regression coefficient at that time. And the sensitivity constant.

Specifically, it has been found that, for example, the following equation is established between the recovered steam amount ST and the main factors (circulation gas amount V, boiler inlet gas temperature BIT, circulation gas specific heat GCP). .

ST [t / h] = V [N m ³ / h] × (BIT-BOT) [° C.] × GCP [Mcal / N m ³ · ° C.] × 10 ⁻³ / 625 [t / Mcal] ... (1)

Here, BOT is the boiler outlet gas temperature (almost constant during operation), and 625 [t / Mcal] is the steam enthalpy.

In this equation (1), the sensitivity constant between ST and each factor can be obtained by fixing the other two factors, and the sensitivity constant a ₁ between the circulating gas amount V and the recovered vapor amount ST can be obtained. = 3.91 × 10 ⁻⁴ [t / N m ³ ], the sensitivity constant between the boiler inlet gas temperature BIT and the recovered steam amount ST a ₂ =
0.103 [(t / h) / ° C], sensitivity constant between circulating gas specific heat GCP and recovered vapor amount ST a ₃ = 231 [(t / h)]
/ N m ³ · ° C] was obtained. This can be summarized as the following formula (2).

ST = 3.91 × 10 ⁻⁴ · V + 0.103 · BIT + 231 · GCP (2)

As described above, there is a positive correlation between each of the circulating gas amount V, the boiler inlet gas temperature BIT, and the circulating gas specific heat GCP, and the recovered steam amount ST.

On the other hand, the circulating gas amount V is the coke cutting amount T /
Since it is uniquely defined by H, the same analysis was performed for the control of the boiler inlet gas temperature BIT under the condition of V = Vmax. For example, the prechamber temperature PT was 6 minutes (= τ ₄ ) has a positive correlation, and the combustion air amount AIR has a positive correlation with the boiler inlet gas temperature BIT and a time delay of 2 minutes (= τ ₅ ), and the coke cutting amount T
/ H is boiler inlet gas temperature BIT and time delay 8 minutes (= τ
_A positive correlation was found in ₆ ).

When the factors controlling the boiler inlet gas temperature BIT are summarized as above, the following equation is obtained.

BIT = 0.15 · PT (τ ₄ = 6 minutes) + 0.005 · AIR (τ ₅ = 2 minutes) + 0.44 · T / H (τ ₆ = 8 minutes) + C (3)

Regarding the control of the specific heat of circulation gas GCP,
The combustion air amount AIR has a positive correlation with the circulation gas specific heat GCP with a time delay of 2 minutes (= τ ₇ ), and the pre-chamber water injection amount WAT has a circulation gas specific heat GCP with a time delay of 6 minutes (= τ ₈ ). There was a positive correlation.

From the above, when the factors relating to the specific heat GCP of the circulating gas are arranged, the following equation is obtained.

GCP = 2.02 × 10 ⁻⁶ · AIR (τ ₇ = 2 minutes) +0.003 · WAT (τ ₈ = 6 minutes) + ε ₁ -C (4)

Regarding the control of the prechamber temperature PT, the prechamber water injection amount WAT is a time delay of 4 minutes (= τ
_{In (9} ), a negative correlation was found with the prechamber temperature PT.

From the above, when the factors relating to the pre-chamber temperature PT are arranged, the following relationship is obtained.

PT = −79.4 · WAT (τ ₉ = 4 minutes) + ε ₂ + C (5)

When the results obtained by the above analysis are applied to FIG. 2, it becomes as shown in FIG.

From the analysis result of FIG. 3, when the operating condition of the CDQ is changed, that is, when the red hot coke charging schedule is changed, or when the red hot coke burn-off condition is changed, etc. If action is taken, it is possible to predict how many times the boiler inlet gas temperature BIT will change and how many tons the recovered steam amount ST will change. Therefore, if the action such as the combustion air amount AIR is taken according to the predicted value, it is possible to obtain the maximum amount of recovered steam under the operating conditions without exceeding the control upper limit value of the waste heat boiler inlet gas temperature BIT. Becomes

[0037]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

In the figure, 30 is a process computer to which the amount of coke stock in the prechamber 12,
Coke cutout amount T / H from the lower part of the fire extinguishing tower 10 by the flow meter 32, circulating gas component analysis value by the gas analyzer 34, waste heat boiler inlet gas temperature BIT by the thermometer 36, prechamber water injection amount WAT, flowmeter 38 Generated steam amount S
Operation data such as T and steam temperature by the thermometer 40 is transferred and input every minute.

The process computer 30 predicts what temperature the waste heat boiler inlet gas temperature BIT will be, for example, 5 minutes after the present condition by the fluctuations in the coke cutout amount T / H and the prechamber temperature PT, and the waste heat boiler The feed-forward control is performed by setting the combustion air amount AIR and the prechamber water injection amount WAT so as to be as close as possible to the control upper limit value of the inlet gas temperature BIT.

At this time, in order to prevent an explosion due to an excessive amount of combustion air, the O ₂ concentration in the circulating gas is, for example, 0.02.
When it becomes more than%, an interlock is provided to instantly shut off the combustion air amount AIR.

FIG. 4 shows the effect of increasing the amount of recovered steam when the present invention is carried out. The horizontal axis of FIG. 4 is the waste heat boiler inlet gas temperature BIT, and the vertical axis is the circulating gas specific heat GCP.
Is taken to draw a line of equal recovery steam. Operation point before action execution When the mark ● indicates that the prechamber water injection amount WAT is increased by 1.0 t / h, this action affects the waste heat boiler inlet gas temperature BIT 10 minutes later.
Therefore, the action to increase the combustion air amount AIR to bring the waste heat boiler inlet gas temperature BIT as close as possible to the upper limit is:
It will be 4000 N m ³ / h.

[0043]

As described above, according to the present invention, control factors such as the amount of coke cut out, the amount of combustion air, and the amount of water injected into the prechamber are used as objective functions such as the waste heat boiler inlet gas temperature and the amount of recovered steam. Since the delay time until the influence is taken into consideration, the CDQ operation without the control delay can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a system in which a CDQ operating method according to the present invention is implemented.

FIG. 2 is a block diagram showing an operation model for explaining the principle of the present invention.

FIG. 3 is a diagram of an operation model showing an example of analysis results according to the present invention.

FIG. 4 is a diagram showing the effect of increasing the amount of recovered steam when the present invention is carried out.

[Explanation of symbols]

 10 ... Fire extinguisher, 12 ... Prechamber, 14 ... Blower, 16 ... Cooling room, 22 ... Waste heat boiler, 26 ... Supply air introduction valve, 30 ... Process computer.

Claims (1)

[Claims] 1. At least the amount of coke cut out, the amount of combustion air, and the amount of water injected into the prechamber are used as control factors, and the magnitude of the influence of each of these factors on the amount of recovered steam of the objective function and the delay time until such influence is taken into consideration. Even if the operating condition of the coke oven dry fire extinguishing equipment changes, at least the maximum amount of recovered steam under the operating condition can be obtained by using this model. A method for operating a dry fire extinguishing system of a coke oven, which is characterized by feed-forward control of water amount.