JPH10235142A - Method for control of the number of absorption column circulating pumps of flue gas desulfurization equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control waste of consumption electric power by minimizing an absorption amount to be sprayed more than it is required by a method wherein a specific function changing momently which expresses the number of operating circulation pumps to a boiler load is used, which is made to correspond to a set point of the boiler load to control the number of the operating circulation pumps. SOLUTION: In a desulfurizing controller 29, a first and a second functions expressing an absorption column inlet SO2 concentration and an absorption column inlet exhaust gas amount to respective boiler loads based on the absorption column inlet SO2 concentration 27a and the absorption column exhaust gas amount 28a when the controller is operated, and a third function expressing an SO2 amount to be absorbed to a boiler load obtained from both functions, are successively rewritten. Further, a fifth function expressing the number of operating circulation pumps 3 to the boiler load is rewritten based on the third function, and a fourth function expressing the number of operating circulation pumps 3 to the SO2 amount. Then, the newest fifth function is used, which is made to correspond to a boiler load set point 31 to control the number of operating circulation pumps 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the number of circulation pumps in an absorption tower of a flue gas desulfurization apparatus.

[0002]

2. Description of the Related Art Conventionally, a flue gas desulfurization apparatus using lime (limestone, slaked lime or quick lime) as an absorbent generally uses an absorbent 2 in a liquid reservoir 1 formed at a lower portion as shown in FIG. By operating a plurality (ten in the example of FIG. 9) of circulation pumps 3, the fuel is sprayed and circulated from a spray nozzle 4 disposed at an upper portion, and exhaust gas supplied from a coal-fired boiler (not shown). An oxidizing air blower 6 for supplying oxidizing air is connected to the liquid reservoir 1 of the absorption tower 5 which is brought into contact with the absorbent 2 sprayed from the spray nozzle 4 and then discharged. A stirrer 7 for stirring the absorbing liquid 2 in the tank is provided, and an absorbing liquid 23 supplied from a mother liquor tank 25 described later and lime 9 supplied from the silo 8 are mixed to form an absorbent slurry 10 and the absorbent The slurry 10 An absorbent slurry pit 11 for supplying to the liquid reservoir 1 of the tower 5 is provided, and a part of the absorbent 2 is supplied from the bottom of the absorbent tower 5 and supplied to the liquid reservoir 1 of the absorber 5. A neutralization tank 13 to which a part of the neutralizing agent 12 such as caustic soda is supplied and which mixes and stirs the absorbing solution 2 and the neutralizing agent 12 is provided, and a thickener 15 for concentrating the absorbing solution 14 extracted from the neutralizing tank 13. The absorption liquid 16 concentrated by the thickener 15 is supplied and the absorption liquid 1 is supplied.
A gypsum separator supply tank 17 for stirring the gypsum 6 is provided, and a gypsum separator 20 for dehydrating the absorbent 16 extracted from the gypsum separator supply tank 17 to produce gypsum 19 is provided. Dewatered water 21 is supplied and the water 21
A filtrate pit 22 for supplying a part of the absorbent to the thickener 15 is provided. Further, a supernatant absorbent 23 is supplied from the thickener 15 and a part of the absorbent 23 is supplied to a wastewater treatment apparatus 2.
4 and a mother liquor tank 25 for supplying to the absorbent slurry pit 11 and sending the remainder to the liquid reservoir 1 of the absorption tower 5.

[0005] In FIG. 9, reference numeral 18 denotes makeup water which is appropriately supplied to the absorption tower 5, and reference numeral 26 denotes an absorbent slurry pump for supplying the absorbent slurry 10 to the absorption tower 5.

In the case of a flue gas desulfurization apparatus as described above, the absorption liquid 2
Is circulated by the operation of the circulation pump 3, and the exhaust gas sent to the absorption tower 5 comes into contact with the absorption liquid 2 sprayed from the spray nozzle 4, whereby SO ₂ (sulfur oxide) is absorbed and removed. Later, it is discharged outside.

On the other hand, a part of the absorbing liquid 2 which has absorbed SO ₂ from the exhaust gas is supplied from the bottom of the liquid reservoir 1 of the absorption tower 5 to a neutralization tank 13 where the neutralizing agent 12 Is mixed and stirred, the mixed and stirred absorption liquid 14 is sent to the thickener 15, concentrated in the thickener 15, and the concentrated absorption liquid 16 is supplied to the gypsum separator supply tank 1.
7 and sent to a gypsum separator 20 where the moisture is removed to produce gypsum 19.

The water 21 dehydrated by the gypsum separator 20
Is returned to the thickener 15 through the filtrate pit 22,
The supernatant absorbent 23 which is discharged when the absorbent 14 is concentrated in the thickener 15 is supplied to a wastewater treatment device 24 and an absorbent slurry pit 11 through a mother liquor tank 25, and is also supplied to a liquid reservoir of the absorption tower 5. Sent to 1.

The absorbent 23 supplied to the absorbent slurry pit 11 is mixed with the lime 9 supplied from the silo 8 in the absorbent slurry pit 11 and is converted into the absorbent slurry 10 by the operation of the absorbent slurry pump 26. The liquid is supplied to the liquid reservoir 1 of the absorption tower 5.

[0008]

However, in the conventional flue gas desulfurization apparatus as described above, the number of operating circulation pumps 3 is determined by the boiler load command (generator output command) [MW].
Irrespective of this, the absorption liquid 2 is controlled to be substantially constant as the number of units in consideration of the margin for the desulfurization performance, and is sprayed more than necessary.
However, there is a disadvantage that the power consumption is increased due to the increase in the amount of waste and the waste is increased.

Therefore, recently, a method has been proposed in which the number of operating circulating pumps 3 is controlled in advance according to the boiler load target value.

In an actual power plant or the like, various types of coal are used alone or as a blend as fuel for a boiler. If the coal type is different even with the same boiler load, it is introduced into a flue gas desulfurization unit. Since the SO ₂ concentration and the amount of exhaust gas in the exhaust gas change, the number of operating circulating pumps 3 should be increased or decreased according to the change in the coal type, that is, the change in the SO ₂ concentration in the exhaust gas and the amount of exhaust gas. Is ideal, but in the case where the number of operating circulation pumps 3 is controlled in advance according to the boiler load target value as described above, the number of operating circulation pumps 3 depends on the type of coal used as fuel for the boiler. Is not changed, and the number of operating units is set as a function of the boiler load with some allowance so that any coal type can come. At present, it is inevitable that there will be more.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a flue gas desulfurization apparatus capable of securing desired desulfurization performance while suppressing waste of power consumption by minimizing the amount of absorbent sprayed more than necessary. It is an object of the present invention to provide a method for controlling the number of circulating pumps in the absorption tower.

[0012]

SUMMARY OF THE INVENTION According to the present invention, an absorbent using lime as an absorbent is sprayed and circulated by operating a plurality of circulation pumps while being brought into contact with exhaust gas discharged from a coal-fired boiler. an absorbent tower circulating pump units control method for flue gas desulfurization apparatus comprising an absorption tower for absorbing and removing SO ₂ in the exhaust gas, based on the actual absorption tower inlet SO ₂ concentration detected and the absorption tower inlet gas amount a first function representing the absorption tower inlet SO ₂ concentration to the boiler load, and a second function representing the absorption tower inlet gas amount to the boiler load,
Said first, rewrites every moment and a third function representing the SO ₂ amount to be absorbed for boiler load obtained based on the second function, and the third function, flue gas desulfurization device-specific SO ₂ The fifth function representing the number of operating circulating pumps with respect to the boiler load is updated every moment based on the fourth function representing the number of operating circulating pumps with respect to the amount, and the fifth function that is the latest is used and given. The present invention relates to a method for controlling the number of circulating pumps of an absorption tower of a flue gas desulfurization device, wherein the number of operating circulating pumps is controlled in advance in accordance with a boiler load target value.

In the method for controlling the number of circulating pumps in the absorption tower of the flue gas desulfurization apparatus, before the operation is started, the first function and the second function are set based on the data of the trial operation in accordance with the type of coal to be used. Assuming the third function based on the first and second functions, and assuming the fifth function based on the third function and the fourth function. In addition, at the start of operation, the number of circulating pumps operated can be controlled in advance in accordance with the given boiler load target value by using the assumed fifth function.

According to the above means, the following effects can be obtained.

During operation of the flue gas desulfurization unit, a first function representing the absorption tower inlet SO ₂ concentration with respect to the boiler load, based on the detected actual absorption tower inlet SO ₂ concentration and the absorption tower exhaust gas amount, a second function representing the absorption tower inlet gas amount with respect to the load, the first, together with a third function representing the SO ₂ amount to be absorbed for boiler load obtained based on the second function is rewritten every moment , and said third function, based on a fourth function representing the number of operating the circulation pump for FGD specific SO ₂ amount, the fifth function representing the number of operating the circulation pump for the boiler load occasionally The updated fifth function is used every moment, and the number of operating circulation pumps is controlled in advance in accordance with the given boiler load target value.

As a result, when various types of coal are used alone or as a blended fuel as boiler fuel in an actual power plant or the like, even if the boiler load is the same, the flue gas desulfurization occurs due to the change in coal type. Although the SO ₂ concentration and the amount of exhaust gas in the exhaust gas introduced into the apparatus change, in the present invention, the circulation pump is preceded from the boiler load target value by a fifth function which is updated every moment based on the latest data. Since the number of operating pumps is controlled, the number of operating circulating pumps is always the optimum number at that time,
Absorbing liquid is not sprayed more than necessary, power consumption is suppressed, and waste is eliminated.

[0017] Also, the number of operating the circulation pump at the time of starting the operation of the flue gas desulfurization apparatus, it is not possible to use data of actual absorption tower inlet SO ₂ concentration and the absorption tower inlet gas amount of the detected Before the start of operation, in correspondence with the type of coal to be used from now on, assuming the first function and the second function based on data in the test operation, the first and second functions are based on the first and second functions. Assuming a third function,
The fifth function is assumed on the basis of the third function and the fourth function, and at the start of operation, the assumed fifth function is used to correspond to the given boiler load target value. Then, the number of operating circulating pumps is controlled in advance, and thereafter, as described above, the fifth function is rewritten momentarily based on the latest data, and the boiler is operated by the latest fifth function. The number of operating circulation pumps may be controlled in advance from the load target value.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 8 show an embodiment of the present invention.
In the figure, portions denoted by the same reference numerals as those in FIG. 9 are the same.
The basic configuration is the conventional one shown in FIG.
It is the same as that of FIG.
As shown in FIGS. 1 to 8, the concentration analyzer 27 and the flow rate detector 28
And the actual absorption tower inlet SO detected by_TwoConcentration 27
a and the desulfurization control device based on the
In the installation 29, the absorption tower inlet SO for the boiler load_Two
First function F representing density 27a₁(X) (see FIG. 3)
And the amount 28a of exhaust gas at the inlet of the absorption tower with respect to the boiler load.
Second function F _Two(X) (see FIG. 4) and the first,
Second function F₁(X), F_TwoSought based on (x)
SO to be absorbed for boiler load_TwoQuantity (= absorption tower entrance
SO_TwoConcentration 27a × absorption tower inlet exhaust gas amount 28a × desulfurization effect
Rate F)_Three(X) (see FIG. 5)
Rewrite every moment (about once every 30 seconds)
Three functions F_Three(X) and SO specific to flue gas desulfurization equipment_TwoVs quantity
Function F representing the number of operating circulation pumps 3
_Four(X) (see FIG. 6), and
Function F representing the number of operating circulation pumps 3
_Five(X) (see FIG. 7) every moment (for example, every 30 seconds).
Degree) rewrite, the latest fifth function F_FiveUse (x)
And the boiler load value given from the boiler control device 30
The desulfurization control device corresponding to the standard value 31 (see FIG. 8)
29 by a circulating pump control signal 32 output from
It is configured to control the number of operating circulation pumps 3 in a row.
On the point.

The number of operating circulation pumps 3 at the time of starting operation of the flue gas desulfurization apparatus is determined by the actual concentration of SO ₂ concentration 27a at the inlet of the absorption tower detected by the concentration analyzer 27 and the flow rate detector 28. Exhaust gas volume at inlet of absorption tower 28
Although the data of a cannot be used, before starting operation, the coal type to be used is known in advance,
Assuming the first function F ₁ (x) and the second function F ₂ (x) based on the data at the test run, corresponding to the coal type,
Assuming the third function F ₃ (x) based on the first and second functions F ₁ (x) and F ₂ (x), the third function F ₃ (x)
The fifth function F ₅ (x) is assumed based on ₃ (x) and the fourth function F ₄ (x).
Using the assumed fifth function F ₅ (x), the circulating pump control output from the desulfurization control device 29 corresponding to the boiler load target value 31 given from the boiler control device 30 as described above. The number of operating circulation pumps 3 is controlled in advance by the signal 32.

Next, the operation of the illustrated example will be described.

During operation of the flue gas desulfurization unit, the concentration analyzer 2
7 and the flow rate detector 28, based on the actual absorption tower inlet SO ₂ concentration 27a and the absorption tower inlet exhaust gas amount 28a, the desulfurization controller 29 indicates the absorption tower inlet SO ₂ concentration 27a with respect to the boiler load. One function F
₁ (x) (see FIG. 3) and a second function F ₂ (x) (FIG. 4) representing the exhaust gas amount 28a at the inlet of the absorption tower with respect to the boiler load.
) And the first and second functions F ₁ (x), F ₂ (x)
To be absorbed for the boiler load required based on
The third function F ₃ (x) (see FIG. 5) representing the O ₂ amount is rewritten every moment, and the third function F ₃ (x)
And the circulation pump 3 for the SO ₂ amount inherent in the flue gas desulfurization unit
Function F ₄ (x) representing the number of vehicles operated (see FIG. 6)
, The fifth function F ₅ (x) (see FIG. 7) representing the number of operating circulation pumps 3 with respect to the boiler load is rewritten from time to time, and the latest fifth function F ₅ (x)
Is used, and the number of operating circulating pumps 3 is preceded by a circulating pump control signal 32 output from the desulfurization control device 29 in accordance with a boiler load target value 31 (see FIG. 8) given from the boiler control device 30. Is controlled.

As a result, when various types of coal are used alone or as a blended fuel as boiler fuel in an actual power plant or the like, even if the boiler load is the same, the flue gas desulfurization occurs due to a change in coal type. Although the concentration of SO _{2 and the} amount of exhaust gas in the exhaust gas introduced into the apparatus change, in the illustrated example, a fifth function F ₅ (x) which is updated every moment based on the latest data (the broken line in FIG. This indicates an example in which coal having a lower sulfur content than that of the solid line is used), and the number of operating circulation pumps 3 is controlled in advance from the boiler load target value 31. The operating number is always the optimal number at that time, the absorbing liquid 2 is not sprayed more than necessary, power consumption is suppressed, and waste is eliminated.

The number of operating circulation pumps 3 at the time of starting the operation of the flue gas desulfurization apparatus is determined by the actual concentration of SO ₂ concentration 27a at the inlet of the absorption tower detected by the concentration analyzer 27 and the flow rate detector 28. Exhaust gas volume at inlet of absorption tower 28
Since the data of “a” cannot be used, before the start of operation, the first function F ₁ (x) and the second function F ₂ ( x), the first and second functions F
₁ (x), F ₂ (x) based on the third function F
₃ (x), the fifth function F ₅ (x) is assumed based on the third function F ₃ (x) and the fourth function F ₄ (x), and At the start, the circulating pump control signal output from the desulfurization control device 29 using the assumed fifth function F ₅ (x) and corresponding to the boiler load target value 31 given from the boiler control device 30 32, the number of operating circulating pumps 3 is controlled in advance, and thereafter, the fifth function F ₅ (x) is updated every moment based on the latest data, and the latest The number of operating circulation pumps 3 may be controlled in advance from the boiler load target value 31 using the fifth function F ₅ (x).

In this way, a desired desulfurization performance can be secured while minimizing the amount of the absorbing liquid sprayed more than necessary and suppressing waste of power consumption.

The method for controlling the number of circulating pumps in the flue gas desulfurization apparatus according to the present invention is not limited to the above-described example, and various changes can be made without departing from the scope of the present invention. Of course.

[0027]

As described above, according to the method for controlling the number of circulating pumps of the absorption tower of the flue gas desulfurization apparatus of the present invention, the amount of the absorbing liquid sprayed more than necessary is minimized and the power consumption is reduced. , While maintaining the desired desulfurization performance.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of an embodiment of the present invention.

FIG. 3 is a diagram illustrating a first function F ₁ (x) in an example of an embodiment of the present invention.

FIG. 4 is a diagram illustrating a second function F ₂ (x) in an example of an embodiment of the present invention.

FIG. 5 is a diagram illustrating a third function F ₃ (x) in an example of an embodiment of the present invention.

FIG. 6 is a diagram illustrating a fourth function F ₄ (x) in an example of an embodiment of the present invention.

FIG. 7 is a diagram illustrating a fifth function F ₅ (x) in an example of an embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a boiler load target value schedule according to an example of an embodiment of the present invention.

FIG. 9 is an overall schematic configuration diagram of a conventional example.

[Explanation of symbols]

2 Absorbent 3 Circulation pump 5 Absorption tower 9 Lime 27a Absorption tower inlet SO ₂ concentration 28a Absorption tower inlet exhaust gas amount 31 Boiler load target value F ₁ (x) First function F ₂ (x) Second function F ₃ ( x) Third function F ₄ (x) Fourth function F ₅ (x) Fifth function

Claims (2)

[Claims] 1. An absorption liquid using lime as an absorbent is sprayed and circulated by operating a plurality of circulation pumps, and is brought into contact with exhaust gas discharged from a coal-fired boiler to absorb and remove SO ₂ in the exhaust gas. an absorbent tower circulating pump units control method for flue gas desulfurization apparatus comprising an absorption tower for, based on the actual absorption tower inlet SO ₂ concentration detected and the absorption tower inlet gas amount, the absorption tower inlet SO for boiler load
It represents a first function representing the ₂ concentrations, and a second function representing the absorption tower inlet gas amount to the boiler load, the first, the SO ₂ amount to be absorbed for boiler load obtained based on the second function The third function is rewritten momentarily, and the third function and the SO
Based on the fourth function representing the number of operating circulating pumps with respect to the _two quantities, the fifth function representing the number of operating circulating pumps with respect to the boiler load is updated every moment, and the latest fifth function is used. A method of controlling the number of circulation pumps operated in a flue gas desulfurization apparatus in advance in accordance with a boiler load target value to be operated. 2. Before the start of operation, a first function and a second function are assumed based on data on a test operation in accordance with the type of coal to be used. Assuming a third function based on, the fifth function is assumed based on the third function and the fourth function, at the start of operation, using the assumed fifth function, 2. The method according to claim 1, wherein the number of operating circulation pumps is controlled in advance in accordance with the given boiler load target value.