JPH02180615A - Control of waste gas desulfurization apparatus - Google Patents

Abstract

PURPOSE:To carry out economical operation of the title apparatus by selecting optimum conditions from the data of waste gas flow rate into an absorption tower, the concentrations of SO2 at an inlet and an outlet of the absorption tower, the concentration of an absorbent in an absorbent solution, pH of the absorbent solution, and the number of driving circulation pumps and controlling the operation. CONSTITUTION:Desulfurization efficiency is computed by a computer 10 based on actual, operational data such as a waste gas flow rate into an absorption tower 1, pH of an absorption solution 2, the concentrations of SO2 at an inlet 8 and an outlet 9 of the absorption tower, the concentration of an absorbent in the absorbent solution 2, and the number of operating circulation pumps, etc. Operational conditions are so altered as to have the computed desulfurization efficiency superior to a set desulfurization efficiency, and real-time operational conditions are so selected as to have ability superior to the set desulfurization efficiency. Then, operation cost under each operational condition is computed and an operational condition is so set as to have minimum operation cost and basing on the operational condition, the actural supply amount of the absorbent, pouring amount of an activating agent, a number of the circulation pumps to be driven are controlled and as a result, most economical operation is thus achieved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a flue gas desulfurization device that allows desulfurization to be carried out in the absorption tower in a suitable manner based on the flow rate of the exhaust gas coming into the absorption tower, the 502yA degree in the exhaust gas, etc. The present invention relates to a control method for a flue gas desulfurization device that is employed to control the exhaust gas desulfurization equipment.

[Prior art] A device that detects the flow rate of exhaust gas sent to the absorption tower of a flue gas desulfurization equipment and the SO2 concentration in the exhaust gas, and uses these detected values as data to efficiently perform the desulfurization action in the absorption tower. For example, a flue gas desulfurization device having the configuration shown in FIG. 7 has been proposed (Japanese Patent Application No. 16351/1986)
No. 9).

In the flue gas desulfurization equipment shown in Fig. 7 above, the absorption liquid stored in the lower part of the absorption tower a is circulated through a plurality of circulation pumps d to the spray stage C arranged in multiple stages at the upper part of the absorption tower a. The spray nozzles of each spray stage C are guided by line e, and a boiler, etc., which is inserted into the absorption tower a in order to make it come into contact with the absorption liquid in the absorption tower a, etc. The exhaust gas inlet pipe 9 is provided with an exhaust gas flow meter for detecting the exhaust gas flow rate and an inlet 5O21 degree meter 1 for detecting the degree of SOz'# in the inlet gas.
The gas outlet pipe j that discharges exhaust gas from the top is provided with an outlet 302 m degree k for detecting 5O2a degrees in the outlet gas, and each detection signal from the exhaust gas flow ff1ilh and the inlet 5O2iG degree i is calculated a1. , the computer I calculates the absolute port of the inlet SO2, and the S02
The number of spray stages C required for old absorption is determined, and the number of operating circulation pumps d is determined by opening and closing the shutoff valves m on each circulation line e.
The detection signal from the ia temperature meter k is sent to the above-mentioned rule 4 to feed back the results based on the number of operating spray stages C and the number of circulation pumps d. 0 is a mist eliminator, 0 is a cooling spray stage, p is a circulation line, q is a circulation pump, and r is a flow meter.

Therefore, when controlling the above-mentioned conventional flue gas desulfurization equipment, the flow rate of the flue gas entering the absorption tower a and the 5O
2i degrees is detected, the mother of S 02 is determined based on the detected value, and the number of circulation pumps d to be used is determined according to the determined SO2 peak, thereby achieving economical operation. That's what I do.

[Problems to be Solved by the Invention] However, in the conventional control method for the flue gas desulfurization equipment described above, desulfurization is attempted to be performed efficiently by changing the number of operating circulation pumps. In this method, the amount of absorbent supplied and the selection of the injection port for the activator, which are important in evaluating the optimum operating conditions, are not considered, and therefore it cannot be said to be sufficient for selecting the optimum operating conditions.

Therefore, the present invention provides data such as the flow base of the exhaust gas entering the absorption tower, the SO2 concentration at the absorption tower inlet, the SO2 concentration at the absorption tower outlet, the agricultural degree of the absorbent (absorbent in the absorption liquid), the number of operating circulation pumps for the absorption liquid pH1, etc. The idea is to select the best one under the current operating conditions and control it to achieve economical operation.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a flow m of exhaust gas entering the absorption tower, an absorption liquid pH 1 of each 5O at the entrance and exit of the absorption tower.
Zy! Obtain current operating data such as degree A, absorbent concentration in the absorbent, and number of circulating pumps in operation, create a desulfurization performance simulation model using a computer based on these data, and then compare it with the set desulfurization rate to determine the setting. If the desulfurization rate is below the desulfurization rate, at that point, we will change the calculated operating conditions such as the number of circulation pumps in operation, the amount of activator injected, and the amount of absorbent supplied, perform a real-time simulation, and perform an operation that can achieve performance that exceeds the desulfurization rate set above. Select the conditions, calculate the operating cost for each operating condition, and set the operating condition with the minimum operating cost.
Based on this set value, operating conditions such as the number of circulating pumps in operation are controlled in real time.

[Function] A model formula for desulfurization efficiency is created in the computer from the current operating data and compared with the set desulfurization rate to select operating conditions that can achieve performance that exceeds the set desulfurization rate. Desulfurization efficiency can be achieved by controlling the number of operating units, the amount of activator injection, and the amount of absorbent supplied, but in the present invention, once the above operating conditions are set, the operating cost is calculated for each operating condition. Since the system is operated under the operating conditions that result in the minimum operating cost, it is possible to perform the optimum operation under the current operating conditions and with a small operating cost.

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

Fig. 1 shows an outline of the flue gas desulfurization equipment used to carry out the method of the present invention, in which a spray nozzle 4 is installed in the upper part of an absorption tower 1 which has a liquid reservoir section at the lower part to store an absorption liquid 2. A plurality of spray stages 3 having a By operating the circulation pump 6, the absorption liquid 2 is guided to the spray stage 3 and sprayed from the spray nozzle 4. On the other hand, a gas inlet pipe 8 is connected to a position between the liquid level of the absorption liquid 2 in the absorption tower 1 and the spray stage 3 so as to introduce exhaust gas from the boiler 7, and a gas outlet pipe 9 is connected to the top of the tower.
A booster fan 1 installed in the middle of the gas inlet pipe 8
The boiler exhaust gas pressurized at 0 is brought into contact with the absorption liquid 2 spouted from the spray nozzle 4 of each spray stage 3,
S02 in the exhaust gas is absorbed by the absorbent in the absorption liquid, and the gas is discharged from the gas outlet pipe 9. S02 reacts with CaCo1 as an absorbent and enters the absorption liquid 2 as calcium sulfite. An air blowing pipe 11 having an air blowing port 12 is disposed at the lower part of the tower 1, and an air supply pipe 13 is connected to the air blowing pipe 11, and CaCa as an absorbent is supplied into the absorption liquid 2. A line 14 and a line 15 for injecting an activator (for example, NaOH) are connected to the absorption tower 1, and a liquid handling pipe 16 is connected near the bottom of the absorption tower 1. Also, the exhaust gas inlet pipe 8, there is an exhaust gas flow meter 17 for detecting the flow rate of exhaust gas,
Inlet 5O2a degree meter 18 that detects 5O2a degrees in exhaust gas
and 5O in the gas discharged to the gas outlet pipe 9.
An outlet 5 ozlfi temperature meter 19 is provided to detect 2a degrees, and each circulation line 5 is further provided with a pHH meter 19 to detect the pH of the absorption liquid.
2O2, an absorbent concentration meter 21 for detecting the absorbent concentration in the absorption liquid is provided.

22 is the value from the exhaust gas flow meter 17 and the inlet SO7 concentration meter 1
23 is an adder, 24 is an absorbent supply input 14
25 is a control valve regulated by the flow rate regulator 24; 26 is a flow rate regulator 27 that regulates the injection amount of the activator;
28 is a flow rate regulator that adjusts the amount of absorption liquid taken out from the absorption liquid extraction pipe 16; 29 is a control valve that is regulated by the flow rate regulator 28; It is a valve.

In addition to the above-mentioned configuration, the present invention has a function of determining the desulfurization efficiency in the absorption tower 1 from the current operating data, comparing it with the set desulfurization rate, and further selecting operating conditions that can achieve performance exceeding the set desulfurization rate based on the comparison result. And, it has the ability to calculate the operating cost for each set operating condition and set the operating condition with the minimum operating cost! H! Using t30, the current operating data is the current exhaust gas flow rate from the exhaust gas flow meter 17, the current inlet S02 concentration from the inlet 302a change course 18, the current outlet S02 concentration from the outlet 5O2S degree meter 19, and the pH.
In order to use the current absorbent concentration from the absorbent concentration meter 21 and the current number of circulating pumps in operation, an electrical connection is made to input these current data into the calculator 30. Connecting.

Figure 2 shows an example of the internal configuration of the above-mentioned Kunsan-Kou 30.
1 is the model equation setting part for desulfurization efficiency η and absorption liquid pt+, 32
33 is the calculated desulfurization rate and the set desulfurization rate η from the desulfurization rate setting device 34.

35 indicates the calculated operating conditions to be changed based on the results of the comparison in the comparison section 33, 36 indicates the number of circulation pumps in operation, and 37 indicates the activator (usually caustic soda NaOH). ) injection amount, 38 is the value of the absorbent concentration meter, 39 is an operating condition setting section, 40 is an operating cost calculation section that calculates the operating cost for each operating condition, 41 is a minimum operating cost operating condition setting section, and 41 is a minimum operating cost operating condition setting section. Control commands are sent from the minimum cost operating condition setting unit 41 to the absorbent supply m adjustment valve 24, the activator injection amount wA adjustment valve 26, and the circulation pump 6.

Now, the exhaust gas from the boiler 7 passes through the inlet pipe 8, is pressurized by the booster fan 10, and is introduced into the absorption tower 1. Absorption tower 1
Inside, the exhaust gas that has entered the absorption tower 1 is guided to the spray stage 3 by the operation of a plurality of circulation pumps 6, and the absorption liquid 2 is sprayed from the spray nozzle 4.
302 in the exhaust gas is absorbed and removed by the absorbent (CaCOl) in the absorption liquid, and the gas is discharged from the gas outlet pipe 9, and the absorption liquid is used for circulation. The absorbent that has absorbed SO2 in the exhaust gas reacts with Sα and enters the absorption liquid 2, where it is oxidized by the blown air and is extracted from the liquid extraction pipe 16 as a slurry.

Inside the absorption tower 1, S02 in the exhaust gas that is sequentially introduced
However, in the method of the present invention, which attempts to set the operating conditions that provide the optimal desulfurization efficiency under the current operating conditions, the calculation Ia30 from the data obtained in the current operating conditions Have students create a simulation model of desulfurization efficiency. That is, as mentioned above, the data obtained in the current operation includes the current D1 gas flow base, the current inlet 5O21 degrees, the current outlet 5OJJ degrees,
Using the current pH of the absorption liquid, the current concentration of the absorption agent in the absorption liquid, and the current number of circulation pumps in operation, these data are
The desulfurization efficiency η is calculated by the measuring unit 32 according to the model formula. In other words, Pn: Number of operating circulation pumps G
= Input log gas: Inlet S02 concentration: Reservoir volume: Absorption S02 base 100-η = j-G-Y・io.

B: Legal liquid volume PC: Absorbent supply base Pa: Activator (NaO!-1>Injection amount) In this case, the relationship between desulfurization efficiency and the number of operating circulation pumps is as shown in Figure 3, and the number of operating pumps is The desulfurization efficiency improves as it increases. In the figure, ■ is the curve when the exhaust gas flow rate is low, ■ is the curve when the exhaust gas flow rate is high, and ■ is the curve when the exhaust gas flow rate is high.

In addition, the relationship between desulfurization efficiency and absorption liquid 1)H is as shown in Figure 4, and the relationship between absorption liquid pH and absorbent concentration in the absorption liquid is as shown in Figure 5. The relationship is such that if the absorbent concentration in the liquid is determined, the pH of the absorbent liquid is determined. In Figure 5,
If the absorption S02 is small, the curve ■' is the absorption S02.
In the middle, the curve ■' is for the case where the absorption Sα is large. Furthermore, the relationship between desulfurization efficiency and Na 211 degrees in the absorption liquid is as shown in FIG.

When a simulation model of desulfurization efficiency is created by the above calculation, the created desulfurization efficiency η and the set desulfurization rate η
, are compared in the comparison unit 33, and if η is smaller than or equal to η, an instruction to change the calculated operating conditions is issued and the calculated operating conditions 35 are changed.
After changing the value 36 of the number of circulating pumps in operation, the value 37 of the activator injection side, and the value 38 of the absorbent supply m, recalculation was performed and a real-time simulation was performed to find η>η.

In other words, the calculated desulfurization efficiency η is the set desulfurization rate η
Driving regulations exceeding 3 are set in the driving condition setting section 39. This operating condition is a combination of the number of circulation pumps in operation, activator injection, and absorbent supply level.
Several types of operating conditions such as 0... can be set.

Next, the operating cost calculation unit 40 calculates the operating cost for each of the set operating conditions. This calculation includes electric power, caco as an absorbent, NaOH1 as an activator, and even H2S.
It is calculated by multiplying the usage proviso of O and the unit price. Based on this operating cost calculation, the operating conditions for the minimum operating cost are set as above)■0■・・・・・・
Select one from among them and set it in the operating cost minimum operating condition setting unit 41, and then set it based on this to the absorbent flow meter 24, the activator flow meter 26, and the circulation pump 6 in FIG. and give control commands. This makes it possible to control the amount of absorbent supplied, the amount of activator injected, and the number of circulation pumps in operation in real time.

In addition, the comparative judgment based on the desulfurization rate in the comparison section 33 is made at the outlet S0.
A comparative judgment of 2 may also be used.

[Effects of the Invention] As described above, according to the control method for the flue gas desulfurization equipment of the present invention, the desulfurization efficiency is calculated based on various data in the current operating condition, and the Select the operating conditions that result in desulfurization efficiency, calculate the operating cost for each selected operating condition, select the operating condition with the minimum operating cost, and calculate the amount of absorbent supplied in real time based on this.
Since the amount of activator injection and the number of circulation pumps in operation are controlled, it is possible to operate under the operating conditions that have the highest desulfurization efficiency and lowest operating costs under the current operating conditions, making it the most economical operation. It can have a great effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a flue gas desulfurization apparatus used in carrying out the method of the present invention, and FIG. 2 is a schematic diagram showing the interior 47. Figure 3 is a diagram showing the relationship between desulfurization efficiency and the number of operating circulation pumps, Figure 4 is a diagram showing the relationship between desulfurization efficiency and absorbent pH, and Figure 5 is a diagram showing the relationship between desulfurization efficiency and absorption liquid pH. Figure 5 is a diagram showing the relationship between desulfurization efficiency and absorption liquid pH. Figure 6 shows the relationship between the desulfurization efficiency and the concentration of the absorbent in the absorbent. FIG. 7 is a diagram showing an example of implementing the conventional JJF smoke desulfurization equipment control method. DESCRIPTION OF SYMBOLS 1... Absorption tower, 2... Absorption liquid, 3... Spray stage, 4... Spray nozzle, 5... Circulation line, 6...
...Circulation pump, 8...Gas inlet pipe, 9...Gas outlet pipe, 11...Air blowing pipe, 14...Absorbent supply line, 15...Activator injection line, 17...・In the exhaust gas flow 1.18... Inlet S02 concentration meter, 19... Outlet 5Oz 1 degree meter, 20... pH meter, 21... Absorbent thermometer, 24, 26.28... Flow ii! J! 1 section meter,
30... Calculator, 31... Model formula setting section, 32.
...Desulfurization efficiency measurement section, 33...Comparison section, 34...
Desulfurization rate setting device, 35... Calculated operating conditions, 39...
- Operating condition setting section, 40...Operating cost calculation section, 41...
・Minimum operating cost operating condition setting section.

Claims (1)

[Claims] (1) Calculate the desulfurization rate using a computer based on current operating data such as the flow rate of exhaust gas entering the absorption tower, the pH of the absorption liquid, the SO_2 concentration at the inlet and outlet of the absorption tower, the concentration of the absorbent in the absorption liquid, and the number of operating circulation pumps. , change the operating conditions so that the desulfurization rate obtained by this calculation exceeds the set desulfurization rate, select real-time operating conditions that can achieve performance exceeding the set desulfurization rate, and then calculate the operating cost for each operating condition. A control method for a flue gas desulfurization equipment, characterized in that the operating conditions that result in the minimum operating cost are set by calculating the operating conditions, and the current amount of absorbent supplied, the amount of activator injected, and the number of operating circulation pumps are controlled based on this. .