JP3190938B2 - Flue gas desulfurization equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flue gas desulfurization device,
In particular, the present invention relates to a flue gas desulfurization apparatus provided with a computer system suitable for providing operating conditions satisfying environmental regulation values even when the apparatus is abnormal.

[0002]

2. Description of the Related Art In recent years, as power plants have increased, the size of boilers using fossil fuel as a main fuel has also increased, and the effect of power generation boilers on air pollution has been increasing. Among pollutants to expand this air pollution, sulfur oxides occupying a great influence (hereinafter abbreviated as SO _x or SO _2.) Emissions regulations are in strict tends year by year. In particular, in a coal-fired power plant in which the installation ratio among thermal power plants has been increasing in recent years, flue gas desulfurization apparatuses are installed in all new plants. Therefore, the operation of the desulfurization device is indispensable for the operation of the power plant also in terms of its operation, and if the exhausted SO _X concentration or the dust concentration exceeds the regulation values due to the abnormality of the desulfurization device, the operation of the power plant cannot be performed.

However, on the other hand, the recent rapid growth of domestic power demand has reduced the margin of supply,
In particular, there is almost no margin for supply during the peak power season in the summer season, and shutting down one large power plant may lead to the worst case of blackout. For this reason, in the operation of the flue gas desulfurization device, it has become necessary to aim at the optimal operation of the power plant even when the operation state is abnormal.

[0004] Problems of the prior art will be described below with reference to the drawings. The flue gas desulfurization unit installed in the thermal power plant uses an absorption slurry containing limestone (CaCO ₃ ) as an absorbent, absorbs SO _x by gas-liquid contact with exhaust gas, and oxidizes the absorption reaction product with air. The wet limestone-gypsum method recovered as gypsum is the mainstream. FIG. 2 shows a system diagram of this system. The exhaust gas from the boiler is introduced into the absorption tower 3 from the desulfurization fan 1 via the exhaust gas flue 2, and SO _x contained in the exhaust gas by gas-liquid contact in the absorption liquid slurry and the absorption tower 3.
Dust is removed. Cleaned processing gas is demister 5
After the accompanying mist is removed in the above, the air is discharged to the atmosphere by the flue 4.

On the other hand, the absorption slurry containing limestone in the absorption tower circulation tank 6 is circulated by the absorption tower circulation pump 7,
It is sprayed into the absorption tower 3 from the upper part of the absorption tower 3. Limestone required for absorption is stored as a limestone slurry in a limestone slurry tank 8, pressurized by a limestone slurry pump 9, and supplied to an absorption tower circulation tank 6 via a limestone slurry pipe 10. On the other hand, SO ₂ absorbed in the absorption tower 3 reacts with limestone to form calcium bisulfite, and the absorption tower circulation tank 6
Inside, it is oxidized by the air 11 blown into the tank 6 to form gypsum. This gypsum slurry is extracted from the absorption tower 3 by the conduit 12, then dehydrated and finally recovered as powdered gypsum.

In the above system, the amount of exhaust gas flowing into the desulfurizer and the SO ₂ concentration are measured by the flow meter 13 and the inlet SO ₂ concentration meter 14, respectively. The outlet SO ₂ concentration is measured by the outlet SO ₂ concentration meter 15. The SO ₂ concentration in the desulfurization apparatus outlet (chimney inlet) needs to operate the desulfurizer so as not to exceed the environmental regulation value.

[0007]

In the above-mentioned system, no consideration is given in the prior art to the operation control of the power plant when the performance is deteriorated due to an abnormality in the auxiliary equipment of the desulfurization apparatus. When the operation of the power plant is continued, the outlet SO ₂ concentration exceeds the environmental regulation value. In addition, when the power plant is stopped, there is a great social impact from the viewpoint of stable power supply as described above.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a desulfurization apparatus capable of controlling the operation of a power plant when the performance of the desulfurization apparatus deteriorates due to an abnormality in an auxiliary machine or the like.

[0009]

The above object of the present invention is achieved by the following constitution. That is, in the flue gas desulfurization apparatus for removing sulfur oxides in an exhaust gas discharged from the combustion device such as a boiler, the exhaust gas quantity relating to the performance of the desulfurization apparatus, inlet SO ₂ concentration, the outlet SO ₂ concentration, the absorption solution pH, A desulfurization performance prediction means for predicting a desulfurization performance according to a power generation plant load such as a generator output and a fuel switch from a process amount such as a limestone slurry amount, an absorption tower circulating liquid amount and an oxidizing air amount, and a prediction by the desulfurization performance prediction means Power plant optimum load setting means for setting an optimum load of the power plant that is allowed based on the environmental regulation value by comparing the value with a preset environmental regulation value, based on the set value of the power plant optimum load setting means. This is a flue gas desulfurization device provided with a power plant load output control means for controlling the load output of the power plant.

The factors controlling the SO ₂ concentration at the outlet of the desulfurizer are the exhaust gas amount, the SO ₂ concentration at the inlet, the amount of the circulating liquid in the absorption tower, and the pH of the absorption tower.
The lower the O ₂ concentration, the larger the amount of circulating liquid in the absorption tower, and the higher the pH of the absorption tower, the more the performance in the absorption tower 3 is improved.
O ₂ concentration can be reduced.

[0011]

[Action] Exhaust gas volume related to desulfurization unit performance, inlet SO
₂ concentration, outlet SO ₂ concentration, absorbing solution pH, limestone slurry amount,
The desulfurization performance according to the power plant load such as generator output and fuel switching is predicted from the process amount such as the amount of circulating liquid in the absorption tower and the amount of oxidized air, and this predicted value is compared with a preset environmental regulation value. Set the optimum load of the power plant that is allowed based on the environmental regulation value. The load output of the power plant is controlled based on the plant optimum load set value.

Since the control system operates even when the process amount is abnormal, the desulfurization performance of each load under the abnormal condition is predicted, whereby the outlet S at each load is estimated.
O ₂ can be predicted concentrations. Since the power generation plant load at which the predicted value of the outlet SO ₂ concentration satisfies the environmental regulation value can be set and controlled, the operation exceeding the environmental regulation value and the power plant not being stopped completely are not performed.

[0013]

FIG. 1 shows the configuration of an arithmetic unit according to the present invention.
In this embodiment, it is composed of four operation units and a data unit necessary for prediction calculation.

First, the first computing section (current performance checking means) 21 calculates the desulfurization performance from the continuously measured plant quantities, and obtains the coefficient k in the following procedure. η = 100 × {(SO ₂ ) ₁ − (SO ₂ ) ₂ } / (SO ₂ ) ₁ (1) η: Desulfurization rate (SO ₂ ) ₁ : Inlet SO ₂ concentration measured by the SO ₂ concentration meter 14 ( ppm) (SO ₂ ) ₂ : Outlet SO ₂ concentration (ppm) measured by the SO ₂ concentration meter 15 η = k × f ₁ {(SO ₂ ) ₁ } · f ₂ (L) · f ₃ (G) · _{f 4 (pH) (2)} L: the absorption tower circulating fluid volume (m ³ / h) G: gas volume (m ³ / h) pH: absorption tower _{pH k = η / [f 1} {(SO 2) 1}・ F ₂ (L) ・ f ₃ (G) ・ f ₄ (pH)] (3) The coefficient k is set as a design value. K at
The following performance prediction calculation is performed by using, so that highly accurate calculation can be performed.

The calculating section (desulfurization performance predicting means) 22 predicts and calculates the performance at each load by using the equation (2), and uses the circulating liquid amount L and the absorption tower pH which are the current process amounts as data. Internal data storage 2 as exhaust gas properties
5 shows the properties (gas amount G, SO ₂ concentration (SO ₂ ) ₁ ) of each load exhaust gas for each fuel type stored in _{No. 5} . Using these data, the desulfurization performance at each load was predicted and calculated, and the smoke outlet SO ₂
Find the concentration.

As an example of the abnormality of the desulfurization apparatus, for example, when one of the four absorption tower circulating pumps 7 fails, the circulating liquid amount L of the absorption tower is reduced to ／ of the rated value, and the desulfurization performance is reduced. Will decrease.

Next, based on the environmental regulation value data 27 and the smoke outlet SO ₂ concentration at each load calculated by the computing unit 22 in the computing unit (optimum load setting means for power plant) 23, an optimal regulation value is satisfied. Calculate and set the load of the power plant. Finally, a calculation unit (power plant load output control means) 2
In step 4, the optimum load is output to the control device.

The specific operation of the present embodiment will be described below using an example. First, consider the case of the following abnormal phenomenon. Abnormal phenomenon (1) Absorption tower circulation pump 1 failure Abnormal phenomenon (2) 〃 2 failures Regarding fuel and properties of boiler SO ₂ condition at each load of 100%, 75%, 50%, 25% of the following power plant Consider.

[0019]

[Table 1]

From the combination of the above abnormal phenomena (1) and (2) and the boiler operating conditions (a) and (b), the outlet SO ₂ concentration is calculated by the above equation (2) under four conditions.

[0021]

[Table 2]

Here, assuming that the regulation value is 100 ppm, the load which satisfies the regulation value is set by the arithmetic unit 23 as follows. Case 1 (abnormal (1), fuel (a)) 25% Case 2 (abnormal (1), fuel (b)) 100% Case 3 (abnormal (2), fuel (a)) 0% (stop) Case 4 ｛Abnormal (2), fuel (b)｝ 50%

In the above-described embodiment of the present invention, the load of the power plant is considered as a measure in response to an abnormality of the desulfurization apparatus. It is also possible to respond by switching to.

[0024]

According to the present invention, when an abnormality occurs in a desulfurization unit, a performance prediction calculation is performed based on the degree of the abnormality and the operating state (boiler, fuel used) at that time, so that the optimum power generation plant without exceeding the regulation value is obtained. There is an effect that the load can be set.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a calculation system according to an embodiment of the present invention.

FIG. 2 is a system diagram of a flue gas desulfurization device.

[Explanation of symbols]

2 Exhaust gas flue 3 Absorption tower 6 Absorption tower circulation tank 7 Absorption tower circulation pump 8 Limestone slurry tank 13 Exhaust gas flow meter 14 Inlet SO ₂ concentration meter 15 Outlet SO ₂ concentration meter

Claims (2)

(57) [Claims] 1. A flue gas desulfurization device for removing sulfur oxides in exhaust gas discharged from a combustion device such as a boiler,
Exhaust gas quantity related to the performance of the desulfurization apparatus, inlet SO ₂ concentration,
The output of the generator from the process amount such as outlet SO ₂ concentration, absorption liquid pH, limestone slurry amount, absorption tower circulation liquid amount, oxidizing air amount, etc.
Desulfurization performance prediction means for predicting the desulfurization performance according to the power plant load such as fuel switching, and comparing the predicted value of the desulfurization performance prediction means with a preset environmental regulation value to allow based on the environmental regulation value. A power plant optimum load setting means for setting an optimum load of the power plant, and a power plant load output control means for controlling a load output of the power plant based on a set value of the power plant optimum load setting means are provided. And flue gas desulfurization equipment. 2. The flue gas desulfurization apparatus according to claim 1, wherein the desulfurization performance prediction means, the power plant optimum load setting means, and the power plant load output control means operate even when the process amount is abnormal.