AT527427A1 - Flue gas cleaning system for the reduction of nitrogen oxides and oxidation of carbon monoxide from the flue gas of a power plant - Google Patents

Abstract

Flue gas cleaning system for reducing nitrogen oxides (NOx) and oxidizing carbon monoxide (CO) from the flue gas of a power plant. The invention relates to a flue gas cleaning system (1) and a method for operating a flue gas cleaning system (1) for the selective catalytic reduction of nitrogen oxides (NOx) and oxidizing carbon monoxide (CO) from the flue gas (2) of a power plant (3). According to the invention, the flue gas cleaning system (1) comprises a catalyst (4) which contains a highly active layer (5) based on vanadium and is designed for operating temperatures of up to 720°C.

Description

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Description

Flue gas cleaning system for the reduction of nitrogen oxides and oxidation of carbon monoxide from the flue gas of a

power plant

The present invention relates to a flue gas cleaning system and a method for reducing nitrogen oxides (NOx) and oxidizing carbon monoxide (CO) from the

Flue gas from a power plant.

In many countries, legislation requires comprehensive treatment of flue gases from power plants, in particular a strong reduction of toxic NOx gases such as nitrogen monoxide (NO) and nitrogen dioxide (NO02). Nitrogen oxides are produced when fossil fuels are burned and are responsible for air pollution and the formation of smog. In flue gas cleaning systems, the flue gas from the power plant is therefore first cleaned by a dust collector to separate particles. The dust-free flue gas is then enriched with ammonia and passed through the SCR catalyst to reduce the proportion of nitrogen.

oxides to reduce.

Flue gas cleaning systems have DeNOx catalysts in which nitrogen oxides are reduced by selective catalytic reduction, thus removing the harmful NOx from the flue gas. The SCR process is based on a chemical reaction in which nitrogen oxides are converted into nitrogen and water. Ammonia (NH3) is used as a reducing agent.

turns.

Conventional DeNOx catalysts are designed for a maximum operating temperature of around 420 °C. If the maximum operating temperature is exceeded, the catalyst will be destroyed. To prevent destruction, conventional DeNOx catalysts are operated at temperatures below 420 °C.

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Since the flue gas still has temperatures of around 650 °C when it enters the flue gas cleaning systems, cooling is necessary. This is done by quenching the flue gas with the supply of fresh air. The flue gas is cooled to around 400 °C. The additional supply of fresh air reduces the efficiency and operational flexibility of the power plant.

The object of the invention is to provide a flue gas cleaning system

for the reduction of nitrogen oxides and oxidation of carbon monoxide from the flue gas of a power plant that does not suffer any loss of efficiency due to quenching

and yet offers a high level of operational flexibility.

The object of the invention, which is directed to a device, is achieved by a flue gas purification system for the selective catalytic reduction of nitrogen oxides and oxidation of carbon monoxide from the flue gas of a power plant, with a catalyst which contains a highly active layer based on vanadium and for operating temperatures

temperatures up to 720°C.

The highly active vanadium-based layer acts as a catalyst to promote the chemical reaction between the nitrogen oxides and the ammonia. Through contact with the catalyst, the nitrogen oxides are selectively converted into nitrogen and water, without damaging the catalyst.

is impaired.

At the same time, the oxidation of carbon monoxide also takes place in the flue gas cleaning system. Carbon monoxide is a poisonous gas that is also produced when fossil fuels are burned. The SCR catalyst with the vanadium coating also has an oxidizing effect, which leads to carbon monoxide being converted into carbon dioxide.

is transformed.

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The use of a flue gas cleaning system with a vanadium-based SCR catalyst makes it possible to significantly reduce the emissions of nitrogen oxides and carbon monoxide. The system therefore contributes to improving air quality and reducing the environmental impact of

power plants.

The highly active layer consists of a carrier material with a highly active coating based on vanadium, or of a carrier material which is homogenized with vanadium as a catalytically active material. Homogenously extruded honeycomb bodies can be used as the carrier material for the catalyst. Vanadium is an inexpensive and easily obtained material for selective catalytic reduction.

of nitrogen oxides.

The main advantage of the invention is that the flue gas cleaning system is designed for operating temperatures of up to 720°C and the catalyst can be operated directly after a gas turbine without cooling the flue gas. The design of the catalyst for operating temperatures of up to 720°C allows for flexible operation, which can also result in higher temperatures for short periods. The invention allows a flue gas cleaning system to be designed and built much more easily than the state of the art.

the.

In an advantageous further development of the invention, ammonia water (NH4,OH) can be fed as a reducing agent to the catalyst for the selective catalytic reduction of nitrogen oxides (NO0x). This simplifies the process configuration, since with this approach no ammonia water needs to be evaporated before it is fed into the feed network. The system is therefore easier to control and maintain, since

exhaust fans are no longer required.

Advantageously, the flue gas cleaning system is designed for

Designed for use in gas and steam power plants to

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To increase efficiency and operational flexibility. The Ka-

The catalyst is used directly after the gas turbine.

The object directed to a process is achieved by a process for the selective catalytic reduction of nitrogen oxides (NOx) and oxidation of carbon monoxide (CO) from the flue gas of a power plant, with a catalyst containing a highly active layer based on vanadium, wherein the catalyst is operated at temperatures of up to 720°C.

is driven.

The advantages described for the device claims apply

equally for the process claims.

In an advantageous further development of the process, ammonia water (NH4,OH) is fed to the catalyst as a reducing agent for the selective catalytic reduction of nitrogen oxides (NO0x).

The process is advantageously used in gas and steam power plants to increase the efficiency and

to increase operational flexibility.

In the following, the invention is described in more detail with reference to figures.

wrote. In it shows:

Figure 1 A schematic representation of a flue gas cleaning system according to the state of the art. Figure 2 An embodiment of the inventive

flue gas cleaning system.

Figure 1 shows a schematic representation of a power plant 3 with a flue gas cleaning system 1 for cleaning a flue gas 2. The flue gas cleaning system 1 is

arranged in the flue gas duct 8 behind a gas turbine 10,

and is part of a heat recovery steam generator 9.

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The waste heat steam generator 9 comprises a catalyst 7 for the selective catalytic reduction (SCR) of nitrogen oxides, which is installed in the flue gas duct 8, between two evaporator surfaces of the heat

exchanger 11 is arranged.

The catalyst 7 is a conventional SCR catalyst according to the state of the art. It is designed for an operating temperature of up to 420 °C and ammonia (NH3) as a reducing agent, and is arranged between the evaporator heating surfaces of the heat exchanger 11. In order to avoid thermal destruction of the catalyst 7, operating temperatures below 420 °C must be ensured. Since the flue gas still has temperatures of around 650 °C when it enters the waste heat steam generator 9, the exhaust gas 2 must be cooled. This is done by quenching the flue gas by supplying fresh air. The flue gas is cooled down to approx. 400 °C. The additional supply of fresh air reduces the efficiency and operational flexibility of the power plant.

Figure 2 shows an embodiment of the inventive

flue gas cleaning system.

The flue gas cleaning system 1 comprises a high-temperature DeNOx catalyst 4 for selective catalytic reduction

of nitrogen oxides (NOx) and oxidation of carbon monoxide (CO) from the flue gas 2. In order to achieve high temperature resistance, the catalyst 4 contains a highly active layer 5 based on vanadium, which makes it suitable for operating temperatures

temperatures between 420°C and 720°C.

The highly active layer 5 based on vanadium acts as a catalyst to promote the chemical reaction between the nitrogen oxides and the ammonia. Through contact with the catalyst 4, the nitrogen oxides are selectively converted into nitrogen and water. The catalyst 4 does not require cooling of the flue gas 2 and can be used directly after a

gas turbine.

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In an advantageous further development of the invention, ammonia water (NH4,OH) can be fed as a reducing agent to the catalyst for the selective catalytic reduction of nitrogen oxides (NO0x). The reducing agent 6 is used without cooling and evaporator. This simplifies the process configuration, since with this approach no ammonia water has to be evaporated before it is fed into the feed network. The system is therefore easier to control and maintain.

because exhaust fans are no longer required.

In a situation of increasing penetration of the electricity grids with renewable energy sources and the transition to hydrogen-based energy storage systems, the combustion of gas in existing gas turbine power plants will inevitably lead to an increase in NOx emissions. In this case, retrofitting such power plants with the catalyst according to the invention will be a simple and cost-effective solution.

be a solution.

Claims (6)

15 20 25 30 35 2023PF12152 patent claims 1. Flue gas cleaning system (1) for the selective catalytic reduction of nitrogen oxides (NOx) and oxidation of carbon monoxide (CO) from the flue gas (2) of a power plant (3), with a catalyst (4) containing a highly active layer (5) based on vanadium, and designed for operating temperatures up to 720°C. laid. 2. Flue gas cleaning system (1) according to claim 1, wherein ammonia water (NH4,OH) can be fed as a reducing agent (6) to the catalyst (4) for the selective catalytic reduction of nitrogen oxides (NOx). 3. Flue gas cleaning system (1) according to one of claims 1 to 4, which is designed for use in gas and steam power plants in order to increase the efficiency and the operating to increase flexibility. 4. Process for the selective catalytic reduction of nitrogen oxides (NOx) and oxidation of carbon monoxide (CO) from the flue gas (2) of a power plant (3), with a catalyst (4) containing a highly active layer (5) based on vanadium, wherein the catalyst (4) is operated at temperatures up to 720°C becomes. 5. The method according to claim 5, wherein ammonia water (NH,OH) is supplied as a reducing agent (6) to the catalyst (4) for the selective catalytic reduction of nitrogen oxides (NOx). 6. A process for removing nitrogen oxide (NOx) according to any one of claims 5 to 7, which is operated in gas and steam power plants in order to improve the efficiency and the operating to increase flexibility.