JPS5967304A - Operating method of blast furnace - Google Patents

Abstract

PURPOSE:To economize the energy required for blasting by determining the optimum blast pressure at which the difference between the power consumption of a driving source of a blower in a set blast quantity and the quantity of the power recovered by a furnace top pressure turbine is minimized by using the performance curve, etc. of said turbine and controlling the driving source of the blower so that said blast pressure is obtd. CONSTITUTION:The highly pressurized air to be blown into a blast furnace 20 is generated by using a blower 16, and the energy of the furnace top gas discharged from the top of the furnace 20 is recovered by using a furnace top turbine 26, by which the blast furnace is operated. The optimum blast pressure at which the difference between the power consumption of the driving source for the blower in a set blast quantity and the quantity of the power recovered by the turbine 26 is minimized is determined by using the performance curve, etc. of the turbine 26. The driving source of the blower 16 is controlled with a control device 40 so that said optimum blast pressure is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for operating a blast furnace, and in particular, a method for generating high-pressure air to be blown into a blast furnace using a blower, which is suitable for use in blast furnace equipment equipped with a blower and a furnace top pressure turbine. The present invention also relates to an improved method of operating a blast furnace in which the energy of top gas discharged from the top of a blast furnace is recovered using a top pressure turbine.

In recent blast furnaces, top pressure turbines have been installed as part of energy saving efforts, and the top gas discharged from the top of the blast furnace is guided to the top pressure turbine, and the energy in the top gas is converted into electricity. I'm trying to collect it.

That is, in blast furnace equipment that employs the conventional air blowing method and energy recovery method using a furnace top pressure turbine, as shown in FIG. The amount of air is adjusted and guided to a blower turbine 14, and a blower 16 such as a blower, which rotates in conjunction with the blower turbine 14, is rotated to generate high-pressure air to be blown into the blast furnace. . Although the drive source for the blower 16 is a steam turbine in the example of FIG. 1, a gas turbine, an electric motor, or the like may also be used.

The high-pressure air generated by the blower 16 is guided to a hot stove 18 and heated to a high temperature, and then blown into a blast furnace 20. The high-temperature, high-pressure air blown into the blast furnace 20 is used to burn coke, undergoes a reduction reaction of ironstone, and is discharged from the top of the furnace as top gas. Since the discharged furnace top gas still has a high pressure, it is guided to a dust remover 22 such as a dust catcher and a venturi scrubber 24, where the dust in the furnace top gas is removed, and then, for example, a radial type Electric power is recovered by being led to the furnace top pressure turbine 26 and rotating the starting point 28. At this time, it is necessary to keep the rotation speed of the furnace top pressure turbine 26 constant, so on the inlet side of the furnace top pressure turbine 26,
A regulating valve 30 for adjusting the turbine inlet gas pressure is provided, and a septum valve 32 for adjusting the turbine inlet gas amount is provided in the flow path bypassing the furnace top pressure turbine 26 or the septum. The furnace top gas that has passed through the valve 32 is further purified by an electrostatic precipitator 34.
It is stored in the gas holder 36.

According to such a method of operating a blast furnace using a furnace top pressure turbine, a part of the energy of the furnace top gas can be recovered, but conventionally, the control of the furnace top pressure turbine 26 is Since this was done independently based on the performance curve of the furnace top pressure turbine, it was not possible to follow the fluctuations in the furnace top gas amount and furnace top pressure due to changes in blast furnace operation, and it was not possible to optimize the power output. The current situation was that no collection was taking place.

That is, the performance curve of the furnace top pressure turbine 26 is, for example, as shown by the solid line A in FIG. (5
), the furnace top gas amounts are Q and TI, and the furnace top pressure P
When it is TI, the operating point of the turbine (marked C) is also that! ! The turbine efficiency reaches its maximum when the performance curve A is reached.

However, if the furnace top pressure PT is too small, e.g.
As shown in Figure 2 (03), the furnace top pressure changes from PTI to PT2 (P
When Tl>J-'T2), the furnace top pressure turbine 2
Since the amount of gas that 6 can swallow is only QT2, it is necessary to bypass the surplus gas ΔQ, T=Q, T1-QT2 through the septum valve 32. Therefore, the operating point of the furnace top pressure turbine 26 is (Q, T2, ]'T2), but the pressure energy of the surplus gas ΔQT is wasted.

On the other hand, if the furnace top pressure PT is too large, for example, as shown in Figure 2 (
As shown in q, the furnace top pressure changes from PTI→PT3(PTl(PT
3) When the temperature reaches K, the gas (2) that the furnace top pressure turbine 26 can swallow is Q, T3, but the actual furnace top gas amount is not QT t L, so the regulating valve 30 is adjusted. Then, increase the turbine inlet gas pressure from PT3 to PTI, △PT
I just need to lower it. Therefore, 1 furnace top pressure turbine 2
The operating point of No. 6 is (QT t, PTI), but the turbine efficiency decreases due to the drift caused by throttling the governor valve 30. This turbine efficiency is determined by the gas l ratio QTI/Q, T
The smaller a is, the greater the degree of reduction. Therefore,
Due to the pressure loss and the reduction in turbine efficiency due to throttling the governor valve 30, the recovered power is reduced by the amount of energy loss 21E.

In this way, bypassing a part of the furnace top gas or lowering the pressure by throttling the regulating valve 30 is an energy loss for power recovery by the furnace top pressure turbine 26.
This ends up consuming extra energy in the blower 16, but conventionally, the furnace top pressure turbine 26
The driving source of the blower 16, for example, the governor valve 12, has not been controlled in relation to the operating state of the blower.

The present invention was made to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a blast furnace operating method that can minimize the overall energy consumption required for air blowing.

The present invention provides a method for operating a blast furnace in which a blower is used to generate high-pressure air to be blown into a blast furnace, and a top pressure turbine is used to recover the energy of top gas discharged from the top of the blast furnace. In this step, using the performance curve of the furnace top pressure turbine, etc., find the optimum blowing pressure that minimizes the difference between the power consumption of the blower drive source and the recovery power M of the furnace JII pressure turbine at the set blower IH. The above object is achieved by controlling the drive source of the blower so that the optimum blowing pressure is obtained.

In addition, the control of the blower drive source using the optimum air blowing pressure is not performed when the furnace condition of the blast furnace is unstable, so that the furnace condition can be recovered quickly. .

Furthermore, the performance curve of the furnace top pressure bin, etc. is modified in accordance with actual operating data, so that control is performed in accordance with actual operating conditions.

Referring to the drawings, the blast furnace operation according to the present invention will be explained below by taking as an example a case where a blower turbine is rotated by high-humidity, high-pressure steam and electricity is recovered using a radial furnace top pressure turbine, similar to the conventional example. The method is explained in detail.

When carrying out the blast furnace operating method according to the present invention, the third
As shown in the figure, a blower boiler 10 similar to the conventional example. Governor valve 12, blower turbine 14, blower 16, hot air stove 1
8, Blast furnace 20, Dust remover 22, Venturi scrubber 24
, a furnace top pressure turbine 26, a generator 28, a speed regulating valve 30, a septum valve 32, an electric precipitator 34, and a gas boulder 36. The measured value of the inlet pressure of the furnace top pressure turbine 26, etc. are input, and the blower drive source (air blower turbine 14) at the set air flow rate is determined using the performance curve of the furnace top pressure turbine 26, etc.
The amount of power consumed T1 and the amount of recovered power T of the furnace top pressure turbine 26
Difference between 2 and Ta=T1-T2 (corresponds to net power consumption)
A control device 40 is provided which determines the optimum blowing pressure such that the minimum blowing pressure is obtained and controls the opening degree of the governor valve 12 of the blowing turbine 14 so that the optimum blowing pressure is not obtained.

Hereinafter, the operation of the control device 40 will be explained.

Operating conditions of blast furnace 20 (air volume, air pressure, air temperature, etc.)
The amount of gas at the top of the furnace and the pressure at the top of the furnace fluctuate due to the change in the amount of air flow Qb.
The relationship with r T 3 is illustrated in FIG. 4. That is, the power consumption T in the blower turbine 14
1 increases gradually as the blowing pressure pb increases, but on the other hand, the amount of recovered power T2 recovered by the furnace top pressure turbine 26, as explained using FIG. 2 above, If the operating point on the performance curve is exceeded, the regulating valve 30 will be throttled down to lower the turbine inlet pressure, and the turbine efficiency will also decrease, so the blowing pressure Pb* will peak at a certain point and then decrease. do. Therefore, the net power consumption amount T3 becomes a curve having the minimum value. 1st, for each air blowing tQb, the optimum air blowing pressure Pb* that minimizes the net power consumption T3
If exists, then K. Now, an example of the relationship between each air blowing amount Qb and the optimum air blowing pressure Pb* is as shown in FIG.

That is, as the operating conditions of the blast furnace 20 change, the amount of air blown Q
) + is set, the optimum air blowing pressure Pb* is determined so that the energy cost related to air blowing is minimized, and if the drive force of the blower 16, for example, the governor valve 12 is adjusted accordingly, the furnace top pressure can be adjusted. The turbine efficiency of the turbine 26 is always maximized, and the amount of steam sent to the blower turbine I4 is also kept to a minimum.

The control device 40 performs these calculations and adjusts the opening degree of the governor valve 12, and is used to adjust the net power consumption T3.
The optimum blowing pressure Pb* is determined so that the force is minimized, and when there is a difference between the optimum blowing pressure Pb* and the set blowing pressure pb, the opening degree of the governor valve 12 of the blowing turbine 14 is adjusted. , it is only necessary to include a control circuit that incorporates a sequence of operations for controlling the blowing pressure Pb to approach the optimum blowing pressure P b *.

In addition, when the condition of the blast furnace is unstable, it is more important to quickly recover the condition than to minimize energy costs, so temporarily drive the blower at the optimum blow pressure PI)*. It is better to stop controlling the source. On the other hand, when the furnace condition is stable.

The blower drive source is controlled based on the optimum air blowing pressure Pbne.

In addition, even if the air flow rate Q b is constant, the air blowing temperature, charging conditions, or pressure loss of each equipment changes, so the furnace top pressure, furnace top pressure turbine inlet pressure, valve opening, surplus gas amount, etc. From the measured values, the performance curve of the furnace top pressure turbine 26, etc. may be corrected, and the optimum blowing pressure may be corrected using the corrected performance curve.

According to the present invention, the turbine efficiency of the furnace top pressure turbine 26 is always maximized, and by adjusting the governor valve 12 by the control device 40, the amount of steam from the blower boiler 10 can be suppressed to the necessary minimum. Costs can be lowered. The energy saving effect due to this saving in the amount of steam is very large.

In the above description, the drive source for the blower turbine 14 is the blower boiler 10, but the drive source for the blower is not limited to this, and may be any other drive source such as a gas turbine or an electric motor. . In this case, the control target of the control device f40 is the governor valve 12, and its drive source is the target.

Further, in the above description, a radial flow type furnace top pressure turbine was used as the furnace top pressure turbine, but the type of turbine is not limited to this, and axial flow type turbines, variable blade angle turbines, etc. may also be used. The control method according to the invention is applicable because a performance curve is provided that maximizes the turbine efficiency.

Next, examples of blast furnace equipment in which the blast furnace operating method according to the present invention is adopted will be described in detail.

As shown in FIG. 6, this embodiment is similar to the conventional example,
Blowing boiler 10, governor valve 12, blowing turbine 14,
Blower 16, hot stove 18, blast furnace 20, dust remover 22, venturi scrubber 24, furnace top pressure turbine 26, generator 2
8. In the blast furnace equipment having a regulating valve 30, a septum valve 32, an electrostatic precipitator 34, and a gas holder 36, the hot blast furnace 1
It was placed on the exit side of 8. Blow volume Q +) and blow pressure pb
An air blower detector 42 for detecting the discharge pressure of the air blower 16, which is disposed on the outlet side of the air blower 16, b d
and a blower detector 4 for detecting power consumption tT1
4, a furnace top pressure detector 46 installed at the top of the blast furnace 20 for detecting the furnace top pressure PT, and a turbine inlet gas installed at the inlet side of the furnace top pressure turbine 26. Pressure Ptr
and a turbine inlet detector 48 for detecting the turbine inlet gas amount Q, tr, and a turbine corresponding to the recovered power %l: T2, which is disposed on the outlet side of the furnace top pressure turbine 2G. A turbine output detector 50 for detecting the output, turbine input gas pressure Ptr, turbine output (
The blower turbine 14 and the furnace top pressure turbine 2 are modified according to actual operational data such as recovery kb force limit T2).
Using the performance curve of No. 6, the difference between the power consumption 'I'1 of the blower turbine 14 and the recovered power amount T2 of the furnace top pressure turbine 26 at setting air r-i: Q11 '[,' a
(=T+-'v2) is minimized, and the optimum air blowing pressure P]]* is determined? a control rack rJ that controls the governor valve 12 so that the
2.

52r.

The operation of the embodiment will be explained below.

The air blowing amount Q detected by the air blowing detector 42 disposed on the outlet side of the hot air stove 18 is inputted to a computing unit 52a, and the blowing pressure Pb is inputted to a computing unit 5.2b. The calculator 52h sets the operable blowing pressure Pb within a certain range, subdivides the range, and instructs to calculate the blower power consumption 'j#, T1 for each blowing pressure pb. For example, the range of operational air pressure PI) is 2.7 kq.
/ cl G < P b <4.5 kv /cr
l (3, blowing pressure Pb = 2.70.2.72.2.7
4・・・・・・・・・4.48.4.50 ky/
9/'ctl to 0.02, such as cr/I G
The following calculation is performed by setting the blowing pressure pb in steps of G.

IJI] Then, the computing unit 52C calculates the blower 16 to the hot air stove 18 for each blowing pressure Pb output from the computing unit 52b.
By adding the pressure loss between, the discharge pressure Pbd of the blower 16 is calculated. Next, the discharge pressure Pbd is stored in the computing unit 52d that stores the efficiency curve of the blower 16 according to the air flow rate Qb.
is input to calculate the blower efficiency η, and the calculation unit 52e
Then, the power consumption tT1 of the blower at each blowing pressure pb is calculated from the values of the blower efficiency η and the discharge pressure Pbd.

On the other hand, for each blowing pressure 1)b, the furnace top pressure pi is calculated by the calculator 52f, and
By adding the pressure drop between 4 and 4, the venturi scrubber outlet pressure P v s is calculated by the calculator 52F.

Father, calculation unit 521] was used to determine the top gas composition and the wind blower Q.
The top gas amounts Q and t are calculated from b, and the water vapor from the venturi scrubber 24 is added to the calculation unit 521 to obtain the venturi scrubber output log gas state ``Qvs''.

Next, using the computing unit 52j that stores the performance curve of the furnace top pressure turbine 26, the venturi scrubber outlet pressure Pvs is directly determined as the inlet pressure P of the furnace top pressure turbine 26.
Calculate the acceptable gas In: Qt r o for the top pressure turbine 26 when added as f, r.

Next, using the calculator 521, the venturi scrubber outlet gas amount Q, v s , the acceptable gas amount Q,
t r o and the minimum gas amount Q smin required for controlling the septum valve 32 are compared and divided into the following three cases.

(1) When Q, vs-Qsmin=Qtro In this case, the furnace top pressure turbine 26 is operated at the operating point on the performance curve as shown in FIG. 2 (5) above, so
The venturi scrubber outlet pressure Pvs is accepted as is.

Specifically, the computing unit 52t calculates the turbine efficiency ηtr=1.
0, and the turbine population pressure Ptr=Pvs using the calculator 52m.
Then, the turbine inlet gas amount Q t is determined by the calculator 52n.
r=Qvs-Qsmin, and the amount of gas passing through the septum valve Qs-Qsmin is set by the calculator 52o.

(1) Qvs-Qsmin) Qtro In this case, as shown in Figure 2 (c) above, the surplus gas △Q
,,Qv 5 -Qt r o is generated, and this surplus gas ΔQ is flowing through the septum valve 32. Therefore, in the computing unit 52t, the turbine efficiency ηtr=1.0, and in the computing unit 52m-cti, the turbine population pressure Ptr=Pvs
In the computing unit 52n, the turbine inlet gas -51)
Let Qtr=Qtro, and in the calculator 52o, the amount of gas passing through the septum valve Qs=Q, vs-Qtro.

[) Qvs-Qsmin (In the case of Qtro In this case, as shown in Figure 2 (QK) above, the venturi scrubber outlet pressure Pvs is too high, so (Qvs
By throttling the governor valve 30 at the turbine artificial pressure Ptr-4 corresponding to the gas intake of -Qsmin), the furnace top pressure turbine 26 swallows the amount of gas. However, by throttling the speed regulating valve 30, the gas amount ratio (Q, v Fl-QSIHi n )/Qtro
Since the turbine efficiency ηtr decreases accordingly, the efficiency deteriorates.

Therefore, the computing unit 52t calculates the turbine efficiency ηtr from the gas amount ratio using the turbine efficiency curve. or,
The computing unit 52m calculates the turbine population pressure Ptr according to the gas t (Qvs-Q, 5m1n) using the turbine performance curve. Further, the computing unit 52n calculates the turbine inlet gas [IQtr=Qvs-Qsmi
n, and the computing unit 52o calculates the amount of gas passing through the septum valve Q.
Let s=Q, 5m4n.

Next, the recovered power amount (power generation amount) T2 of the furnace top pressure turbine 2G for each blowing pressure Pb is determined by the calculator 52p.

The difference T3 = TI - T2 between the power consumption Tl of the blower and the recovery power T2 of the furnace top pressure turbine obtained previously is the net power consumption. Find the value of power consumption T3, then select the minimum net power consumption T a min from among the net power consumption (,1,, +173) for each blowing pressure pb, and set the blowing pressure at this time to the optimum blowing pressure. Let the wind pressure be Pb*.

The controller 52[ compares the optimum blowing pressure Pb* calculated by the calculator 52q with the actual blowing pressure pb detected by the blowing detector 42, and if Pb*>Pb, The discharge pressure Pbd of the blower 16 is controlled by increasing the opening degree of the governor valve 12, leaving it as it is when pb*-pb, and narrowing down the governor valve 12 when pb*<pb. Then, the blowing pressure 1) b is controlled so as to approach the optimum blowing pressure Pb*. Specifically, the amount of change in the discharge pressure Pbd of the blower 16 is set to the optimum blowing pressure Pb.
It is calculated by adding the increase/decrease in pressure loss between the blower 16 and the hot blast stove 18 to the difference between the blower discharge pressure Pbd and the blower pressure Pbd, and the opening degree of the governor valve 12 is adjusted by 1 depending on the amount of change in the blower discharge pressure Pbd.
1 river coffin 1j.

If the air blowing pressure 1(1)b is different, the above calculation may be repeated and a new optimum blowing pressure 1. 'l:) *
is calculated, and the governor valve 12 is controlled according to the difference between this maximum droplet blowing gate) * and the measured value P + ) of the blowing pressure.

Note that if the blower efficiency η, the performance curve of the furnace top pressure turbine 26, the turbine efficiency ηtr, etc. stored in the computing units 52d, 52j, 52, etc. do not match the actual operation, the optimum blowing pressure P b There is a possibility that t may deviate from the actual optimum value. In addition, the performance curve at the time of installation and the performance curve when actually operated do not completely match (g), and turbine characteristics change over time, and usually due to deterioration of mechanical parts etc. This reduces turbine efficiency. Therefore, the air blower detector 42, the air blower detector 4
4. The furnace top pressure detector 46, turbine inlet detector 48, and turbine output detector 50 measure operational data such as turbine pressure Ptr, turbine output (power generation) il)Tz, and the computing unit 52s calculates each transmission. The performance curve, efficiency curve, etc. for the air volume Qb are recalculated, and each of the arithmetic units 52 (1, 52
j, 52j, etc., the performance curve is changed to match the actual turbine characteristics, and the optimum blowing pressure Pb* is calculated using the new performance curve.

Note that in the above description, a description of the common temperatures of air and gas is omitted, but in actual calculations, a calculation formula that takes into account temperature correction for each temperature is used.

As explained above, the present invention has the excellent effect of minimizing the energy cost for blowing air into the blast furnace.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a schematic configuration of blast furnace equipment in which a conventional air blowing method and an energy recovery method using a top pressure turbine are adopted; A diagram showing an example of the relationship between the performance curve of the turbine, the operating point of the blast furnace, and the operating point of the furnace top pressure turbine, and FIG. 3 shows the basic configuration of blast furnace equipment in which the blast furnace operating method according to the present invention is implemented. FIG. 4 is a block diagram showing the optimum blowing pressure for the blast furnace operating method according to the present invention;
Figure 5 is a diagram showing an example of the relationship between recovered power and iE consumption power, and Figure 6 is a diagram illustrating an example of the relationship between air blowing volume and optimal air blowing pressure according to the present invention. It is a block 5 diagram showing the configuration of an embodiment of blast furnace equipment in which the blast furnace operating method is adopted. 10...Blower boiler, 12...Governor valve, 14...Blower turbine, 16...Blower, 18...Hot blast furnace, 20...Blast furnace, 22...Dust remover, 24... - Venturi scrubber, 26... Furnace top pressure turbine, 28... Generator, 30... Governor valve, 32... Septum valve, 40.52... Control device.

Claims (3)

[Claims] (1) Use a blower to generate high-pressure air to be blown into the blast furnace, and use a furnace top pressure turbine to
In a blast furnace operation method that uses pressure to recover the energy of the top gas discharged, the performance curve of the top pressure turbine is used to calculate the power consumption of the blower drive source and the top pressure turbine at a set air flow rate. A method for operating a blast furnace, characterized in that the optimum blowing pressure is determined such that the difference from the amount of recovered power is minimized, and the driving source of the blower is controlled so as to obtain the optimum blowing pressure. (2) The blast furnace operating method according to claim 1, wherein the control of the blower drive source using the optimum blowing pressure is not performed when the furnace condition of the blast furnace is unstable. (3) The performance curve, etc. of the furnace top pressure turbine is modified according to actual operational data.
Blast furnace operating method described in section.