JPS60190217A - Operation control of wet desulfurization and denitration apparatus - Google Patents

Abstract

PURPOSE:To suppress the charge amount of a stock material to a necessary min. degree, in the operation control of a wet desulfurization and denitration apparatus, by applying feed forward control and feed back control to the charge amount of a chemical agent for generating ClO2-gas on the basis of NOx-concn. CONSTITUTION:SOx/NOx-containing exhaust gas generated in a boiler 1 is cooled by a cooling tower 2 and mixed with ClO2-gas in a duct 2d to be sent to a disulfurization and denitration tower 3. At this time, the outputs of a biler fuel meter 11 and a conversion meter 12 for converting NOx-concn. to O2-concn. are read in an operation part 14 where the amount of ClO2-gas required in denitration is calculated to be outputted to an adder 17. On the other hand, the output of a conversion meter 13 for converting NOx-concn. to O2-concn. is outputted to a limiter 16 and the adder 17 through an output NOx-concn. controller 15. A limiter 18 controls supply valves 9a-9c from the feed forward signal and a feed back signal inputted to the adder 17 and controls the generation amount of the Cl2-gas. By this method, exhaust gas mixed with ClO2-gas is desulfurized and denitrated to be exhausted from a chimney 6.

Description

[Detailed Description of the Invention] [Field of Application in Industry-1-] The present invention provides Cj
! 02 relates to a method for controlling the operation of a wet desulfurization and denitrification equipment that adjusts the amount of gas generated.

[Prior art]

Combustion exhaust gas containing NOx and SOx exceeding a certain amount cannot be directly released into the atmosphere due to pollution regulations.

For this reason, various exhaust gas desulfurization and denitration methods have been proposed and implemented in the past, but in the wet type desulfurization and denitration equipment that has been widely used in the past, Na011. Cj! O7
Desulfurization and denitration are carried out using the following reactions.

First, the chemical reaction of desulfurization is represented by the following formula (1).

502 + 2Na011-=Na2503 + N2
0 =ill Also, the chemical reaction of denitrification is as follows (2), (3)
It is represented by the formula.

2NO+Cj! 02 +H20-1NOz +1IN
Or +IICA...(2)NO2+2Na25O3
-2Na2 S01 +'A N2 = 131 (The reaction shown in equation 11 can achieve almost complete desulfurization by supplying sufficient Na011, and the generated Na2503 is used as Na2 so shown in equation (3).On the other hand Cj2O, used in equation (2), may be produced in advance and fed into a bomb or from a tank, but from a cost perspective, it is also possible to generate cxO2 using the reaction in equation (4) below.・U, a method of supplying this is adopted.

2NaC60341+2504 +SO2'2CeC)
z +2NallSO4...(4) By the way, Ca produced by the reaction shown in formula (4)
O2 and Na2503 are +21. (In order to accelerate the reaction shown in Equation 31 and increase the denitrification rate, a slightly excessive supply was conventionally used.However, such a supply power method is not only wasteful from an economic point of view, but also 6
7!02 accelerates corrosion of the equipment, and the amount of reducing absorbent used to prevent it from being released into the atmosphere does not increase. For this reason, recently, 1) 1 to N in the gas at the inlet side of the desulfurization and denitrification equipment is
The ability to supply sufficient C7!02 necessary and sufficient to oxidize O based on the absolute amount of O was proposed, and the present applicant has already filed an application for 11th patent (Japanese Patent Laid-Open No. 55-127128).
(No.), and has also been put into practical use.

However, even in this method, the absolute amount of NO in the exhaust gas at the inlet side of the desulfurization and denitrification equipment fluctuates depending on the operating conditions of the boiler and other various disturbances.Based on the measured value of the absolute amount of NO, NaCj! 0311+
2 The supply of chemicals such as SOt and SOz is controlled in a feed-forward manner, but even if the delay in chemical reactions is taken into account, the amount of NO and the amount of C7 necessary for its oxidation are reduced in the desulfurization and denitrification tower.
! It is extremely difficult to completely match the amount of 02,
For reasons such as the fact that there is a measurement error in the absolute
! The supply meter for 02 is slightly excessive, and in actual operation, the Noxa degree at the exhaust gas outlet of the desulfurization and denitrification equipment is too low than the management target value, and each Cβ02
There was a problem in that a large amount of gas raw material and an absorbent for excess ClO2 gas were used, resulting in high running costs.

〔the purpose〕

The present invention has been made in view of the above circumstances, and its purpose is to introduce chemical injections to generate Cβ02 gas necessary for denitrification based on the relative amount of NOx measured at the exhaust gas inlet of the desulfurization and denitrification equipment. In addition to feedforward control, NOx is measured at the exhaust gas output 1 of the desulfurization and denitrification equipment.
In order to correct the C7!02 gas amount so that the concentration approaches the control target value, a large amount of chemical stage is feed-hacked fffll
Another object of the present invention is to provide a method for controlling the operation of a wet desulfurization and denitrification apparatus, which enables efficient operation of the apparatus by minimizing the amount of raw materials input.

〔composition〕

The wet desulfurization and denitrification equipment according to the present invention is a wet type desulfurization and denitration equipment that adjusts the amount of ClO2 gas generated by changing the raw material input amount, based on the relative amount of NOx in the exhaust gas flowing into the JJ gas inlet side of the desulfurization and denitration equipment. C4 required for denitrification
The amount of O□ gas is determined, and in order to achieve this, the amount of raw material input is feedforward controlled, and the degree of NOx in the exhaust gas is actually measured at the exhaust gas outlet side of the desulfurization and denitrification equipment, and this actual value is It is characterized in that the amount of raw material input is feedback-controlled a11 in order to correct the supply p of C7!02 gas so as to match a predetermined management target value.

〔Example〕

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, in which the lower part is a desulfurization and denitrification equipment, 1 is a combustion boiler, 2 is a cooling tower, 3
is a desulfurization and denitrification tower, 4 is a dehydrator, 5 is an exhaust fan, 6 is a chimney, 7 is
is a ClO□ gas generator. S generated from boiler 1
The combustion exhaust gas containing Ox and NOx is first led to the cooling tower 2 via the duct 1a and cooled. In the cooling tower 2, water from a water tank 2a is sprayed by a pump 2b from a nostle 2c placed at the top of the cooling tower 2, and the combustion exhaust gas is cooled from 60°C to about 80°C by contact with this water. ing. The cooled combustion exhaust gas is sent to the desulfurization and denitrification tower 3 through the duct 2d, but on the way, C7+02 gas from the ClO2 gas generator 7 is mixed in the duct 2d. 0
The gas is introduced into the lower part of the desulfurization and denitrification tower 3 in a state where it is partially reacted and mixed with the two gases. The ClO2 gas generator 7 is as shown in the above formula (7+) < NaC110311+2 SOt + 5
07! By injecting a predetermined amount of each chemical in 02 by operating the valves 9a, 9b, and 9c, 07! It is configured to generate O2 gas, and the amount of Cl1O2 gas generated depends on the amount of the above-mentioned chemical input, in other words, each valve 9a, 9b, 9
It is determined by the control amount of c. The desulfurization and denitrification tower 3 has a
A plurality of lower shelves 3a are arranged, and a nozzle 3b is installed at the top.
The liquid tank 3 is supplied from the nozzle 3b with the pump 3G.
Na011.d pumped from d. An aqueous solution containing Naz SOz is sprayed, and the mixture is introduced into the tower and mixed with the rising combustion exhaust gas (1), (2), (3).
) Desorption (Jj de(n'i) is carried out by the reaction shown in the equation. The desulfurized and denitrated combustion exhaust gas is dehydrated from the duct h3e through the dehydrator 4, and is discharged into the atmosphere from the chimney 6 at the shallow end 5. Note that the desulfurization and denitrification equipment mentioned above is conventionally known.In the method of the present invention, the desulfurization and denitrification equipment as described above is used. NOx '18 degrees 02jN calculator 12 installed in the duct la leading to the combustion frame 11 and the cooling 132, and the 1 unit duct 15 installed from the exhaust fan 5 on the exit side to the chimney 6
Each detection (g) from the NOx concentration 02 conversion at13 is read into the arithmetic control unit 10 at a predetermined timing and timing, and the following control is performed based on this.
At 0, the boiler combustion amount is 1tll and the NOx concentration is 02
The output of the converter 12 is inputted into the calculation unit 14 to determine the absolute level of NOxOx in the combustion exhaust gas at the entrance to the desulfurization and denitration equipment based on the unit theoretical combustion gas amount determined by the type of fuel inputted in advance. Next, calculate the amount of Cβ02 gas required to oxidize this absolute amount of NOx, in other words, denitrify it, and calculate this C7! Adder 17 adds a signal corresponding to the Oz gas amount.
Output to. On the other hand, the output signal of the NOx concentration 02 conversion meter 13 is read into the outlet NOx concentration controller 15 at a predetermined timing, and a correction signal necessary to make it coincide with a predetermined management target value is output to the limiter 16. Limiter 1
6 outputs a signal within the required range to the adder 17. Adder 1
In 7, the Cj! inputted to this! A signal corresponding to the required amount of 02 gas, that is, a feedforward signal, and a correction signal, that is, a feedhack signal are added together, and a signal corresponding to the sum is output to the limiter 18. In the limiter 18, each chemical supply valve 9a, 9b controls the input signal within a necessary range.

Input to 9c setting device 19a, 191), 19c,
The amount of each chemical introduced is controlled to adjust the amount of fl2 gas generated. In the above embodiments, a configuration was described in which the amount of medicine inputted was automatically controlled, but it is of course possible to control the amount of chemical input manually.

Figure 2 shows the output side of the wet desulfurization and denitrification equipment when the power method of the present invention is used, and Figure 3 shows the output side of the wet desulfurization and denitrification equipment when the 1 it power method is used.
III I) NOx actually measured on the outlet side of the JJI wind turbine
A graph showing changes in concentration, with time (minutes,
The graph also shows NOx mH degree (ppm) on the vertical axis. As is clear from this graph, when using the conventional method, the NOx value was significantly lower than the NOx 4 degrees 60 yen 1m set as the τi theoretical target value (♀゛11 line part), and the cost of using chemicals was high. However, when using the method of the present invention, although there is a slight deviation, the NOx concentration is approximately in line with the management target value, and the generation of C7!02 gas is accurate without excess or deficiency. It is clear that controlled and efficient operation is being carried out.

〔effect〕

As described in Section 2 below, in the method of the present invention, the amount of Cff 02 gas required for the JJQ nitrate is determined based on the relative amount of NOx in the slag entering the desulfurization and denitrification equipment, and the Cj! In addition to controlling the input 111 of the Oz gas source 'X1, the concentration of NO in the υ1 gas at the outlet side of the desulfurization and denitrification equipment is actually measured, and the input amount is controlled by the fee 1-hack in order to match this with the management target. This not only prevents the risk of the NOx concentration in the combustion exhaust gas after denitrification exceeding the management target value, but also prevents the NOx concentration from dropping more than necessary from the management target value and increasing the use of chemicals. The present invention has excellent advantages such as being able to reduce running costs.
It plays the fruit of J.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the implementation state of the method of the present invention, Fig. 2 is a graph showing the change in outlet NOxb four degrees in the method of the present invention, and Fig. 3 is a graph showing the change in outlet NOx concentration according to the conventional method. . D...Wet desulfurization and denitrification equipment 1...Boiler 2...
Cooling tower 3... Desulfurization and denitrification tower 4... Dehydrator 5...
・Jjl wind machine 6...Chimney 7...C7!02 gas generator 9a, 9b, 9c...Valve 10...Arithmetic control section 11...Combustion amount needle 12...NOx concentration 0
2 conversion total 13...Nox concentration 02 conversion BL 14.
...Calculation section 15...NOx concentration controller 16...Limiter 17...Addition section 18...Limiter 19
a, 19b, 19c...Setting device patent applicant Tomio Kono, patent attorney representing Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] 1. In the operation control force method of the wet desulfurization membrane model 1'i equipment, which adjusts the CA'02 gas generation rate by changing the raw material input amount, the relative NOx in the antagonistic gas flowing into the exhaust gas input side of the desulfurization and denitrification equipment is c z ' required for denitrification based on the amount
o 2 Determine the amount of gas and feed the raw material input amount to achieve this.
A wet desulfurization and denitrification device characterized in that the OX concentration is actually measured and the raw O'-1 input group is feedback-controlled in order to correct the supply amount of Cβ02 gas so that the measured value matches a predetermined control target value. Operation control method.