JPH06233915A - Denitration equipment of combustion exhaust gas - Google Patents

Abstract

PURPOSE:To denitrate NOx in exhaust gas even when the temp. of the exhaust gas is high or low by arranging a denitration device-incorporating type exhaust gas boiler, a plasma denitration device and an NOx adsorbing device packed with an NOx selective adsorbent in series. CONSTITUTION:The combustion exhaust gas 14 of a gas turbine 23 is charged into a catalytic denitration device-incorporating type exhaust gas boiler 31 to be subjected to heat exchange and NOx is reduced by the injection of ammonia 61 to discharge the exhaust gas as treated gas 17. NOx in the discharged treated gas 17 is directly decomposed into NO2 and O2 by a plasma denitration device 32 or oxidized to become treated gas 18. Oxidized NOx in the treated gas 18 is adsorbed in an NOx adsorbing device 33 packed with an NOx adsorbent and the adsorbed gas is desorbed by regeneration gas 15 to be recovered as desorbed gas 16. Treated gas 19 from which NOx is removed by the NOx adsorbing device 33 is discharged to the atmosphere from a flue 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a denitration facility for exhaust gas from a combustion exhaust gas source.

[0002]

2. Description of the Related Art One mode of conventional exhaust gas denitration equipment will be described with reference to FIG. 5 by taking the case of treating NOx in a gas turbine exhaust gas as an example. In FIG. 5, the gas turbine 2
The exhaust gas 14 of No. 3 is injected with ammonia 61 and introduced into the exhaust gas boiler 31 with a built-in denitration device, and the introduced exhaust gas 1
No. 4 performs heat exchange in the boiler 31, NOx is removed, and the discharged processing gas 17 is discharged to the atmosphere by the chimney 41. The following reactions occur in the exhaust gas boiler 31 incorporating the denitration device. 4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (1) 6NO + 4NH ₃ → 5N ₂ + 6H ₂ O (2) That is, NO is reduced using ammonia as a reducing agent to generate water. Therefore, it is used as a pollution control device for combustion exhaust gas.

[0003]

However, in the above-mentioned conventional denitration equipment, as shown in FIG.
The denitration reaction, which is the above reaction, does not occur unless the atmosphere is at a high temperature of about 0 ° C. That is, when the temperature of the denitration device is low, such as when the gas turbine is started, ammonia cannot be injected, so that denitration cannot be performed. The horizontal axis of FIG. 6 shows the start time of the gas turbine in minutes,
The vertical axis represents the exhaust gas temperature (° C.) and the NOx concentration (ppm), the solid line represents the exhaust gas temperature, and the broken line represents the NOx concentration. This indicates that when the exhaust gas temperature reaches 350 ° C to 380 ° C, ammonia is injected and NOx is decomposed.

In view of the above-mentioned state of the art, the present invention is to provide an exhaust gas denitration equipment capable of denitrifying NOx in the exhaust gas not only when the exhaust gas temperature from the combustion exhaust gas source is high but also when it is low. is there.

[0005]

Means for Solving the Problems (1) Generation of combustion exhaust gas, which is characterized in that an exhaust gas boiler incorporating a denitration device, a plasma denitration device, and a NOx selective adsorbent-filled NOx adsorption device are arranged in series. Denitration equipment for exhaust gas from the source. (2) A pipe for supplying combustion exhaust gas from a combustion exhaust gas generation source or exhaust gas extracted from a denitration device built-in exhaust gas boiler to the NOx adsorption device is provided, and desorbed NOx-containing gas from the NOx adsorption device is generated as combustion exhaust gas. A denitration equipment for exhaust gas from a combustion exhaust gas generation source according to the above (1), characterized in that a pipe is provided for supplying to the combustion air supply pipe of the source. Is.

[0006]

In the exhaust gas treatment facility of the present invention, the temperature of the combustion exhaust gas is 3 when the combustion gas generation source is in steady operation.
Since it becomes 50 ° C or higher, a considerable amount of NOx is removed by injection of NH ₃ as a reducing agent in the exhaust gas boiler with built-in denitration device. NOx directly decomposed or oxidized, and the oxidized NOx is further installed in the downstream.
Ox adsorbent (activated alumina, activated carbon, various zeolites)
The exhaust gas, which is adsorbed and removed by the NOx adsorbing device filled with NOx and has almost zero NOx, is released into the atmosphere.

In the plasma denitration apparatus of the present invention, N
Ox is partially decomposed directly or oxidized by plasma by the following reaction. 2NO ₂ → 2NO + O ₂ (3) 2NO + O ₂ → N ₂ + 2O ₂ (4) NO + O ₃ → NO ₂ + O ₂ (5) NO ₂ + O ₃ → NO ₃ + O ₂ (6) Oxidized nitrogen oxides are in the wake. It is adsorbed and removed by the provided NOx adsorbing device filled with the NOx adsorbent.

Further, when the temperature of the combustion exhaust gas at the time of initial starting or stopping of the combustion gas generation source is low, even if NH ₃ is injected as a reducing agent, as shown in FIG. 6, denitration in the exhaust gas boiler incorporating the denitration device is carried out. Therefore, the low-temperature combustion exhaust gas passes directly through the exhaust gas boiler with a built-in denitration device, and NOx in the exhaust gas is decomposed or oxidized in the plasma denitration device, and the oxidized NOx is absorbed by the NOx adsorption device as described above. Exhaust gas that has been adsorbed and removed and has almost zero NOx is released into the atmosphere.

The NOx adsorbing device filled with the NOx adsorbent in the equipment of the present invention adsorbs NOx in the exhaust gas at an exhaust gas temperature of about 100 ° C. or lower, and is desorbed by heating the NOx adsorbing device adsorbing NOx to several hundred degrees. It In the present invention, as the heat source gas for heating the NOx adsorption device, the combustion exhaust gas from the combustion gas generation source (for example, gas turbine, boiler, etc.) in the equipment of the present invention or the extracted exhaust gas from the exhaust gas boiler incorporating the denitration device is used. Is. By doing so, it is not necessary to newly provide an external heat source, so that enlargement of equipment can be avoided.

Further, the NO desorbed from the NOx adsorption device
The x-containing gas is designed to be injected into the combustion air supplied to the combustion gas generation source. Therefore, when attention is paid to NOx, it becomes a closed circuit, and NOx is released to the outside without the need for further processing by another device. The NOx in the exhaust gas can be reduced to almost zero, which also prevents the facility of the present invention from becoming large.

[0011]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIG. Hereinafter, referring to FIG. 1, NO in the exhaust gas of the gas turbine
A case of processing x will be described as an example. In FIG. 1, the combustion exhaust gas 14 of the gas turbine 23 is introduced into an exhaust gas boiler 31 incorporating a catalytic denitration device, the introduced combustion exhaust gas 14 undergoes heat exchange, NOx is reduced by injecting ammonia 61, and the treated gas is treated gas. It is discharged as 17. The NOx (several ppm to several tens of ppm) in the discharged processing gas 17 is directly decomposed or oxidized into N ₂ and O ₂ by the plasma denitration device 32 as shown in the above formulas (3) to (6) and treated. It becomes gas 18.

The oxidized NOx in the processing gas 18 is NO
It is adsorbed in the NOx adsorption device 33 filled with the x adsorbent, desorbed by the regeneration gas 15 and recovered as the desorbed gas 16. On the other hand, the processing gas 19 from which NOx has been removed by the NOx adsorbing device 33 is discharged to the atmosphere from the chimney 41 with NOx close to zero. In FIG. 4, 11 is air, 12 is fuel, 13 is combustion gas, 21 is an air compressor, and 22 is a combustor.

When the gas turbine 23 is started or stopped, the gas temperature of the combustion exhaust gas 14 has not reached the temperature (350 ° C. or higher) for denitration in the exhaust gas boiler 31 with a built-in denitration device. After passing through the built-in exhaust gas boiler 31, it is directly denitrated by the plasma denitration device 32, and the same treatment is performed thereafter. Therefore, this equipment makes it possible to denitrate the combustion exhaust gas 14 generated at the time of starting or stopping as well as the steady operation of the gas turbine 23.

(Embodiment 2) Another embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. 2 is different from FIG. 1 in that NOx adsorbed by the NOx adsorption device 33.
A pipe is provided to use the combustion exhaust gas 14 or the extraction gas from the exhaust gas boiler 31 with a built-in denitration device as the regeneration gas 15 for desorbing the desorption gas 16, and the desorption gas 16 from the NOx adsorption device 33 is used as the combustion air for the gas turbine 23. 11 is that the pipe is provided so as to supply to the supply pipe 11.

Denitration of the combustion exhaust gas 14 of the gas turbine 23 in the equipment shown in FIG. 2 is performed in the same manner as in the first embodiment. The only difference is that the regeneration gas used for desorption of the NOx adsorbed in the NOx adsorption device 33 does not need to be provided with a high temperature gas generation source for the regeneration gas by using the high temperature exhaust gas in the system. However, the size of the entire facility can be prevented, and the desorbed NOx-containing gas from the NOx adsorbing device 33 is mixed with the combustion air of the gas turbine 23 to form a closed circuit for NOx, which is not exhausted to the outside at all. That is the point.

The high temperature combustion exhaust gas 14 is the NOx adsorption device 3
Of course, it can be used as the regenerated gas 15 of No. 3, but the exhaust gas temperature in the exhaust gas boiler 31 with a built-in denitration device can be used as the regenerated gas 15 because it is sufficiently high depending on the position. An example of the distribution of the exhaust gas temperature in the exhaust gas boiler 31 incorporating the denitration device is shown in FIG. As shown in FIG. 3, it can be seen that the exhaust gas boiler 31 with a built-in denitration device can be sufficiently used as the regeneration gas 15. That is, FIG. 4 shows the relationship between the regenerated gas temperature and the desorption amount of NOx. If the exhaust gas temperature of about 350 ° C. or higher in the exhaust gas boiler 31 with built-in denitration device is extracted, the NOx desorption device 33 will be desorbed. The rate can be about 70%.

[0017]

With the NOx denitration equipment of the present invention, denitration can be performed not only when the temperature of the combustion exhaust gas is sufficiently high but also when the temperature of the combustion exhaust gas is low. Further, since the high temperature exhaust gas in the equipment can be used as the NOx desorption regeneration gas of the NOx adsorption device, not only the effect of avoiding the enlargement of the equipment can be avoided, but the desorbed NOx-containing gas is used as the combustion exhaust gas generation source. By injecting into combustion air, NOx is not released into the atmosphere at all.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a denitration equipment of the present invention.

FIG. 2 is an explanatory view of another embodiment of the denitration equipment of the present invention.

FIG. 3 is a temperature distribution chart of exhaust gas in an exhaust gas boiler incorporating a denitration device in the denitration equipment of the present invention.

FIG. 4 is a chart showing the relationship between the NOx adsorption device regeneration temperature and the NOx desorption rate.

FIG. 5 is an explanatory diagram of one mode of conventional denitration equipment.

FIG. 6 is a diagram showing an operating region of a heat removal boiler incorporating a denitration device.

Front page continued (72) Inventor Nobuaki Murakami 5-717-1, Fukahori-cho, Nagasaki-shi, Nagasaki Sanhishi Heavy Industries Ltd. Nagasaki Laboratory (72) Inventor Naoyasu Matsuo 5-3, Atsunoura-cho, Nagasaki-shi, Nagasaki Western Japan Hishijukosan Building, 4th floor, within Choryo Design Co., Ltd.

Claims (2)

[Claims] 1. A denitration facility for exhaust gas from a combustion exhaust gas generation source, comprising an exhaust gas boiler incorporating a denitration device, a plasma denitration device, and a NOx adsorption device filled with a NOx selective adsorbent, which are arranged in series. 2. The NOx adsorption device is provided with a pipe for supplying combustion exhaust gas from a combustion exhaust gas source or exhaust gas extracted from an exhaust gas boiler incorporating a denitration device, and the NOx adsorber
The denitration equipment for exhaust gas from a combustion exhaust gas generation source according to claim 1, wherein a pipe for supplying the desorbed NOx-containing gas from the x-adsorption device to a combustion air supply pipe of the combustion exhaust gas generation source is provided.