JPH02223623A - Denitration device and ammonia concentration controller in denitration device - Google Patents

Abstract

PURPOSE:To provide smooth control with a practical and low cost device by controlling the quantity of feed for an atomizing nozzle for aqueous ammonia based on the learning characteristics of necessary ammonia concentration stored in a sequencer. CONSTITUTION:The exhaust gas containing much NOx discharged from a diesel generator 4 is discharged to an ammonia mixing device 16. Atomizing ammonia is fed from a nozzle 15 to the mixing device 16. The exhaust gas vaporized into ammonia gas in a moment is fed to a catalyst reactor 17 to come in contact with a high temperature catalyst 17a. The feed quantity of aqueous ammonia fed to the mixing device 16 is controlled step by step or continuously according to the output of an engine 2 based on the learning characteristics stored in the sequencer by an aqueous ammonia feed quantity controller 15. It is thus possible to control feed quantity smoothly with low cost constitution.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an ammonia concentration control device in a denitrification device that controls the ammonia concentration of atomized ammonia water used for denitration of engine exhaust gas, and to such an ammonia concentration control device. This invention relates to a denitrification device that uses a control device for ammonia concentration.

[Prior Art] A conventional denitrification device and its ammonia concentration control device were constructed as shown in FIG.

In the figure, 1 is an alternating current generator driven by a diesel engine 2.

3 is an exhaust pipe, and a diesel power generator 4 is constituted by 1 to 3, which are nine or more. 5 is a liquefied ammonia tank, and 6 is a paper riser, in which liquefied ammonia supplied from the tank 5 is heated with heating steam and vaporized into ammonia gas.

6' is an ammonia regulator equipped with a valve B for controlling the ammonia supply device.

7 is an ammonia mixer, and dan is an exhaust gas heating/dilution device. In addition, the exhaust gas heating/dilution device is connected to the fuel supply device 8.
a, a blower 8b, and a mixer 8C, and depending on whether the exhaust gas supplied from the diesel generator is low or high temperature, one of the fuel supply device 8a or the blower 8b is operated to generate a low-temperature catalyst (described later) in the mixer 8C. It is heated or cooled to the appropriate temperature. 7a is a supply pipe that supplies ammonia gas discharged from the ammonia mixer 7 to a catalytic reactor 9, which will be described later.

Reference numeral 2 denotes a catalytic reactor, which is equipped with a low-temperature catalyst 9a made of titanium or the like in an exhaust gas passage. 10 is a muffler for suppressing noise emitted from the engine side, and 11 is an exhaust pipe. Reference numeral 12 denotes a NOx concentration sensor (No., analyzer) in exhaust gas, which detects the NOx concentration in the form of electrical quantity. The sensor 12 is connected to the supply pipe 12'
installed at the appropriate location. The ammonia concentration control device 13 is a computer (hereinafter abbreviated as CPU).

The control device 13 has a built-in necessary program, and controls the opening degree of the valve B of the ammonia regulator 6° in cooperation with the CPU 14 in response to the electrical signal for the NOx concentration given from the sensor 12. The amount (concentration) of ammonia supplied to the ammonia mixer 7 is controlled so that it becomes the ammonia concentration necessary to adjust the NOx in the exhaust gas to an appropriate value in accordance with the engine output. ing.

The liquefied ammonia is vaporized into ammonia gas by passing through a paper riser 6, and the supply amount is adjusted to JL by an ammonia regulator 6, and the temperature is adjusted to suit the catalyst through an exhaust gas heating and diluting device. The mixture is supplied to the catalytic reactor 2 in the mixer 7 with the exhaust gas containing a large amount of NOx discharged from the power generator.

Therefore, when this mixed gas comes into contact with the catalyst 9a of the catalytic reactor 2, NOX is reduced to nitrogen and water through the first-order chemical reactions of equations (1) and (2).

4N O+ 4N H3+ 02→ 4 N20 6820・ ・ ・ (1) 6 N O
2+ 4 N H3→ 7N 2 + 121
420 ・ ・ ・ (2) That is, in the route up to the exhaust gas discharge described above, the concentration of the ammonia gas supplied from the ammonia mixer 7 is controlled by the control device 13, while the concentration of the ammonia gas supplied from the ammonia mixer 7 is controlled by the controller 13. Since the temperature of the exhaust gas is controlled by the exhaust gas heating and diluting device and is always appropriate, the value of NOx in the exhaust gas discharged to the atmosphere from the exhaust pipe 11 via the muffler 10 is controlled to the desired value. It is below the value.

That is, the control device 13 detects the ammonia concentration from the sensor 12, and outputs a control signal in coordination with the CPU 14 based on the output of the engine 2 to control the degree of opening of the valve B. The concentration of ammonia gas supplied to the mixer 7 is controlled.

On the other hand, depending on the load condition of the diesel generator, the exhaust gas heating and dilution device operates as follows.

The temperature of the exhaust gas mixed with ammonia gas is made to be the appropriate temperature of the low temperature catalyst 9a.

In other words, when the load is in a steady state, 7 power generation bags? The temperature of the exhaust gas discharged from the lf4 is, for example, 200 to 250 degrees Celsius, so it only passes through the equipment, but when the load is low, the temperature of the exhaust gas discharged from the power generation equipment is, for example, 200-250℃. , since the temperature is about 100 to 150°C, the fuel supply device 8a in the equipment is activated to heat it to 200 to 250°C. On the other hand, when the load is high, the temperature of the exhaust gas is, for example, , the temperature will be as high as 300℃,
Next time, operate the blower 8b in the equipment and blow 200~25
Cool to 0°C.

[Problems to be Solved by the Invention] By the way, the ammonia concentration control device in the conventional denitrification device has the following drawbacks (problems).

That is, the ammonia concentration is controlled by the control device 13 and the ammonia regulator 6' in cooperation with the CPU 14 based on the ammonia concentration detected by the sensor 12, and the control device t! Although the control is accurate and appropriate, the control mechanism is complicated, making the control device expensive and large.

For this reason, it is not economically suitable as an ammonia concentration control device for a denitrification device for a medium-capacity engine power generator in the 500KW class or less, for example, and there has been a demand for a control device that can control ammonia concentration with a cheaper configuration. .

Similarly, conventional denitration equipment as a whole equipped with such an ammonia concentration control device has the following problems (
There was a problem.

■Liquefied ammonia is subject to the High Pressure Gas Control Law, and it is necessary to have a qualified person at the installation site to handle it carefully.

■A paper riser is required to vaporize liquefied ammonia, and an exhaust gas heating/dilution device is required to adapt to low-temperature catalysts, making the equipment larger, more complex, and more expensive.

(2) Such denitrification equipment can be said to be large-scale because it was developed for use in large power plants of, for example, 5000 kW.

However, in recent years, standards related to pollution prevention have tended to become stricter in each jurisdiction, and even for low-output diesel generators in the 500KW class, which were previously exempt from regulations, the NO5 value has been reduced, for example. , 500 ppm or less, and in this case, it is difficult to apply conventional large-scale equipment as is.

There is a need to perform this with a small, low-cost denitrification device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a denitrification device and an ammonia concentration control device in the denitrification device that solve the above-mentioned problems of conventional devices.

[Means for Solving the Problems] The present invention provides a denitration device for engine exhaust gas, in consideration of the fact that NO2 contained in the engine exhaust gas increases in accordance with the output of the engine. The present invention relates to an ammonia concentration control device in a denitrification device, which controls the amount of ammonia water supplied in atomized form to a required amount in accordance with the output of an engine.

In this case, a plurality of spray nozzles, a plurality of solenoid valves dedicated to each spray nozzle for controlling the supply of ammonia water, a plurality of solenoid valves for supplying compressed air, and a sequencer are provided. The output and required ammonia concentration characteristics are obtained and stored in the sequencer, and in response to increases and decreases in engine output, the ammonia water exclusive to each spray nozzle is adjusted based on the ammonia concentration characteristics stored in the sequencer. It is conceivable to provide an ammonia concentration control device in a denitrification device in which the number of solenoid valves for each supply of compressed air is increased or decreased in stages.

Further, a plurality of branch pipes, collecting pipes, and ammonia water supply sources each having one spray nozzle and each separate electromagnetic valve for supplying ammonia water to the spray nozzle, and a plurality of branch pipes and ammonia water supply sources having one spray nozzle and separate electromagnetic valves for supplying ammonia water to the spray nozzle, and It is equipped with a compressed air supply source that supplies compressed air and a sequencer, and the characteristics of the engine output and required ammonia concentration are obtained through advance learning and stored in the sequencer, and the above-mentioned Based on the ammonia concentration characteristics stored in the sequencer, the number of solenoid valves dedicated to each branch pipe for supplying ammonia water is gradually increased or decreased. The electromagnetic valve may be used as an ammonia concentration control device in a denitrification device whose opening degree is set to supply a constant amount.

In addition, one spray nozzle, a solenoid valve that supplies ammonia water to the spray nozzle, a motor-equipped opening valve, a motor for controlling valve opening/closing, a motor control device, an ammonia water supply source, and a solenoid valve for the spray nozzle. The system is equipped with a compressed air supply source that supplies compressed air via a sequencer, and the characteristics of engine output and required ammonia concentration are obtained through prior learning and stored in the sequencer, so that it can respond to increases and decreases in engine output. Based on the ammonia concentration characteristics stored in the sequencer, the motor is controlled by the control device to increase/decrease the opening degree of the motorized on-off valve for supplying ammonia water in one step or continuously; ,
The solenoid valve for supplying compressed air may be used as an ammonia concentration control device in a denitrification device, which is set to an opening degree that supplies a constant amount of air.

Furthermore, the amount of ammonia water supplied in the atomized form mixed with the catalytic reactor having a high temperature catalyst and the exhaust gas is controlled in accordance with the output of the engine, and ammonia water is outputted in the atomized form to achieve the desired ammonia concentration. a water supply amount control device, the engine is configured to mix exhaust gas from the engine with atomized ammonia water discharged from the control device in an ammonia mixer, vaporize the mixture, and then supply the mixture to the catalytic reactor. It is also possible to configure an exhaust gas denitrification device.

[Example] The present invention will be specifically described below with reference to Examples shown in FIGS. 1 to 4.

FIG. 1 shows a basic system diagram of the present invention, and in the figure, components equivalent to those of the conventional system are denoted by the same reference numerals as those in FIG. 5.

15 is an ammonia water supply amount control device, for example, 25
% concentration of ammonia water and compressed air from a compressor (not shown) are supplied and ammonia water is made into atomized water.The ammonia concentration is finally determined by the amount of ammonia water that becomes atomized and is output from engine 2. correspondingly, the NOx in the exhaust gas is below the regulation value (for example
The ammonia concentration is controlled so that the ammonia concentration is set to the level necessary to maintain the ammonia concentration (below 00 ppm).

The specific structure of this ammonia water supply amount control device will be described later with reference to FIGS. After mixing 17 liters of ammonia water with atomized ammonia water to be mixed with 7 liters of ammonia water, the catalytic reactor 1'? It is assumed that the vessel 17 is equipped with a high temperature catalyst 17a.

18 is a connecting pipe between the catalyst reactor 17 and the muffler.

If a gas-water heat exchanger 19 is provided in the pipe as shown by the broken line, it is possible to utilize the calorific value of the exhaust gas as a water heater.

Next, the specific structure of the upper element of the ammonia water supply amount control device will be explained with reference to FIGS. 2 to 4.

FIG. 2(a) shows this first embodiment.

Reference numerals 19a to 19c denote ammonia spray nozzles each having a nozzle at the tip thereof, and ammonia water is supplied to each spray nozzle through dedicated solenoid valves 20a to 20c, and each spray nozzle is supplied with dedicated solenoid valves 21a to 21c. Compressed air is supplied through the Although not shown in the figure,
Equipped with a separate sequencer, the characteristics of engine output and required ammonia concentration are obtained and memorized through prior learning, and based on the above-mentioned memorized characteristics of ammonia concentration, in response to increases and decreases in engine output. Each solenoid valve 19a to 19C so as to gradually increase or decrease the number of solenoid valves for supplying ammonia water and compressed air exclusive to each spray nozzle;
It is assumed that the opening/closing control of 20a to 20C is performed.

The above components 19a to 21c constitute the upper part of the ammonia water supply amount control device of the first embodiment.

This effect will be explained with reference to FIG. 2(b).

In the figure, A shows the amount of NOx in the exhaust gas vs. engine output characteristics when no denitration action is performed on the engine exhaust gas, and B shows the denitrification action performed by sequentially operating each spray nozzle 19a to 19c. C and D respectively represent the amount of ammonia water supplied and the total value of compressed air supplied in each case of B--the output characteristics of the engine.

For ammonia water attached to each spray nozzle 19a to 19c,
Each solenoid valve 19a, 20a for compressed air.

The intervals in which 19b, 20b, 19c, and 20c are opened are controlled in a linear manner by the sequencer.

In other words, the solenoid valves 19a and 20a operate in the engine output sections P, →P4. In addition, the solenoid valves 19b and 20b are in section P.
2→P4. The solenoid valves 19c and 20c have one spray nozzle sequentially in sections P and -+P4.

If the ammonia water concentration is controlled to increase stepwise from two to three spray nozzles 19a to 19c, the concentration of ammonia water sprayed from each spray nozzle 19a to 19c will be as shown in C, and the amount of compressed air supplied will be D. They increase in stages as shown in .

As a result, if ammonia water with ammonia concentration controlled in this way is supplied to the ammonia mixer 16 and chemically reacted in the catalytic reactor 17, NOx in the exhaust gas is reduced to B.
For example, as shown in FIG.

In addition, in Figure 2 (b), the engine output is P, and below, the NOx in the exhaust gas is at the regulation value (for example,
500 ppm) or less, so when the output is below P1, the atomized ammonia water is not supplied and released! However, even if the engine output is below P, if the NOx value of the exhaust gas is above the regulation value, the single-mouth spray nozzle 19a is started to operate.

FIG. 3 shows a second embodiment of the ammonia water supply amount control device V5 of the present invention.

As shown in the figure, one spray nozzle 21. Connecting pipe 22
．． Collecting pipe 23. For example, three branch pipes 24a, 25a,
25c and the solenoid valves 24b and 2 inserted into each branch pipe.
5b, 25c, an ammonia water supply pipe, a compressed air supply pipe 28, and a solenoid valve 29 are connected, and the supply amount of compressed air is determined by, for example, the spray nozzle 3 in the embodiment shown in FIG.
The ammonia water is supplied in a constant amount fixed to the main amount, and the solenoid valves 24b, 25b, 26c are sequentially connected to the solenoid valve 2.
Even if the opening is controlled by a separately installed sea breaker in accordance with 0a to 20c, the output characteristic will be similar to that shown in FIG. 2(b), resulting in the output characteristic of C.

In this case, the supply amount of compressed air has a characteristic as shown in D.

In addition, as shown in FIG. 4, the air supply side for supplying air to one spray nozzle 21 similar to that in FIG. Valve 28. Motor 28a.

Configured by connecting a motor control device 30 and a solenoid valve 31,
If the control device 30 controls the amount of ammonia water, which is determined by the opening degree of the motor 28a and therefore the opening/closing valve 28, in stages according to FIG. 2(A) using a separately installed sequencer, the result shown in FIG. 2(B) can be achieved in this case as well. Output characteristics shown in B and C are obtained.

In this case as well, the supply amount of compressed air has a characteristic like D'.

Note that if the motor 28a is continuously controlled by the control device 30, the output characteristics will not be gradual.

It can be a continuous characteristic.

[Operation] Next, the operation of the denitrification apparatus equipped with the ammonia concentration control device (ammonia water supply amount control device) shown in FIG. 1 will be explained.

Exhaust gas containing a large amount of NoX discharged from the diesel power generator 4 is discharged to the ammonia mixer 16. On the other hand, the mixer 16 is supplied with ammonia water and atomized ammonia supplied from the nozzle 151 using compressed air from a compressor (not shown) through the above-described route.

Since the temperature of the exhaust gas is as high as 350 to 500°C, it is instantaneously vaporized into ammonia gas, which is then sent to the catalytic reactor 1.
7.

Therefore, by contacting the high-temperature catalyst 17a in the reactor 17, No is reduced to harmless nitrogen and water through a chemical reaction based on the basic formulas shown in equations (1) and (2).
Exhaust gas that has reached the appropriate ppm NO value is passed through silencer 1.
0 and is exhausted to the atmosphere from the exhaust pipe 11. During this time, the hot water supply system including the gas water heat exchanger 19 can supply the required hot water using the high temperature exhaust gas passing through the pipe 18.

During this period, the concentration of ammonia gas is determined by the amount of ammonia water supplied to the ammonia mixer 16 as shown in FIG. control in stages to achieve the required value.

Although not shown in the same figure, the motor 28a in FIG.
By continuously controlling this output characteristic, the ammonia concentration of the ammonia gas supplied to the catalytic reactor 17 is controlled to a required value. The NOx value is controlled to be below a regulation value (for example, 500 ppm).

In addition, when looking at each of the spray nozzles constituting the apparatus-L5, the supply amount of ammonia water is controlled to be a constant amount for each control section.

[Effects of the Invention] The present invention mixes compressed air and ammonia water sprayed through a nozzle with high-temperature exhaust gas discharged from an engine to form vaporized ammonia, which is brought into contact with a high-temperature catalyst. In an engine denitrification device that reduces NOx in exhaust gas to nitrogen and water, ammonia water supply amount control is used to control the ammonia concentration to an appropriate amount corresponding to the engine output. Since it is a control device for ammonia concentration in a denitrification device, it has excellent first-order effects.

■In the present invention, the characteristics obtained by learning the necessary ammonia concentration corresponding to the NOx in the exhaust gas and the engine output obtained by learning the ammonia concentration control in advance are stored in the sequencer. Based on this, the amount of ammonia water supplied to the spray nozzle is controlled stepwise or continuously, so the configuration for this control is an inexpensive one that has a sequence as its main part. Since the configuration can be changed, it becomes a practical and inexpensive device for use in, for example, a 500 kW class diesel power generator.

(2) Furthermore, if the supply amount of ammonia water is continuously controlled, the supply amount of the ammonia concentration can be controlled smoothly.

Furthermore, a denitrification device equipped with such an ammonia concentration control device has the following effects compared to conventional ones.

(2) Since ammonia water is used instead of conventional ammonia gas as the ammonia for reducing Nox, it is easy to handle as long as a commercially available product can be used.

■Since a high-temperature catalyst is used and the ammonia water is brought into contact with it to vaporize it, the conventional exhaust gas heating and dilution device is no longer necessary, and the paper riser is replaced with a simple ammonia spray nozzle. As a result, the device has become smaller, simpler, and cheaper.

■Since the exhaust gas can be discharged at a high temperature with NoX below the required value, it can be used as a water heater by incorporating a heat recovery system such as a gas water heat exchanger in the exhaust process. It is possible to have

[Brief explanation of the drawing]

Figure 1 is a system diagram showing an example of application of the present invention, Figure 2 (A) -
FIG. 4 is a connection diagram showing each of the first to third embodiments of the present invention;
FIG. 2(b) is a characteristic diagram of each engine output. Further, FIG. 5 is a system diagram showing a conventional example. 2; Upper of the engine: Ammonia water supply amount control device 17: Catalytic reactor 17a: High temperature catalyst 19a to 19c, 21: Spray nozzles 20a to 20c, 21a to 21c: Solenoid valves 24b to 26
b, 29, 31: Solenoid valve 28a: Motor 30: Control device Applicant Shinko Oki Co., Ltd. Agent Patent attorney Haruya Saito and 2 others Figure 1 PoF? 2P3 EkaP

Claims (1)

[Claims] 1. In the engine exhaust gas denitrification device, NO_x contained in the engine exhaust gas is mixed with the exhaust gas, taking into account that NO_x contained in the engine exhaust gas increases in accordance with the engine output.
1. A control device for ammonia concentration in a denitrification device, characterized in that the amount of ammonia water supplied in atomized form is controlled to a required amount in accordance with the output of an engine. 2. Multiple spray nozzles 19a, 19b, 19c,...
・A plurality of electromagnetic valves 20 for controlling ammonia water supply exclusive to each spray nozzle 19a, 19b, 19c, .
a, 20b, 20c, . . . , a plurality of solenoid valves 21a, 21b, 21c, . The ammonia concentration characteristics stored in the sequencer are stored in the sequencer, and in response to increases and decreases in engine output, each spray nozzle 1
9a, 19b, 19c, ... Exclusive solenoid valves 20a, 20b, 20c for supplying ammonia water and compressed air, respectively.
. . .; 21a, 21b, 21c, . . . The device for controlling ammonia concentration in a denitrification device according to claim 1, wherein the number of internal openings is increased or decreased in steps. 3. One spray nozzle 21 and separate electromagnetic valves 24b, 25b for supplying ammonia water to this spray nozzle 21
, 26b, a plurality of branch pipes 24a, 25a, 26
a, a compressed air supply source that supplies compressed air to the collecting pipe 23 and the ammonia water supply source as well as the spray nozzle 21 via the solenoid valve 29, and a sequencer; Based on the characteristics of the ammonia concentration stored in the sequencer, the solenoid valves 24b, 25b, 26b for ammonia water supply exclusive to each branch pipe are activated in response to increases and decreases in engine output. , . Concentration control device. 4. One spray nozzle 21, a solenoid valve 31 that supplies ammonia water to the spray nozzle 21, a motorized on-off valve 28, a motor 28a for controlling valve opening and closing, a motor control device 30, an ammonia water supply source, and spraying Nozzle 21
is equipped with a compressed air supply source that supplies compressed air through a solenoid valve 29, and a sequencer, and the characteristics of the engine output and required ammonia concentration are obtained through prior learning and stored in the sequencer, and the engine output is adjusted. The control device 30 controls the motor 28a to adjust the opening degree of the motorized on-off valve 28 for supplying ammonia water stepwise or continuously based on the characteristics of the ammonia concentration stored in the sequencer in response to the increase or decrease in the ammonia concentration. 2. The ammonia concentration control device in a denitrification apparatus according to claim 1, wherein the solenoid valve 29 for compressed air supply is set to an opening degree to supply a constant amount. 5. A catalytic reactor with a high-temperature catalyst and a supply amount of ammonia water mixed with the exhaust gas are controlled in accordance with the output of the engine, and an amount of ammonia water that achieves the required ammonia concentration is output in the form of a spray. and an ammonia water supply amount control device, and the exhaust gas from the engine is mixed with the ammonia water sprayed from the control device in an ammonia mixer, vaporized, and then supplied to the catalytic reactor. A denitrification device for engine exhaust gas, which is characterized by: