CN210473547U

CN210473547U - Gas boiler removes CO and takes off NOx integration purifier

Info

Publication number: CN210473547U
Application number: CN201920207241.1U
Authority: CN
Inventors: 李坚; 梁全明; 梁文俊; 何洪
Original assignee: Beijing University of Technology; Beijing Municipal Institute of Labour Protection
Current assignee: Beijing University of Technology; Beijing Municipal Institute of Labour Protection
Priority date: 2019-02-18
Filing date: 2019-02-18
Publication date: 2020-05-08
Anticipated expiration: 2029-02-18

Abstract

CO and NO removal for gas boiler_xAn integrated purification device belongs to the field of treatment of gaseous pollutants. The return flue of the gas boiler enters the catalytic reaction device through the flue gas outlet of the boilerThe gas port is connected, and the gas outlet of the catalytic reaction device is connected with the fan through the waste heat recovery system; a urea solution injection device (15) is arranged in the return flue and is connected with a urea storage tank through a metering device and a control device; a guide plate, a CO oxidant layer and a denitration catalyst layer which are all up to the shaft are sequentially arranged in the catalytic reaction device to form a multi-section reactor. The injection point of the denitration reducing agent is positioned in the return flue of the gas boiler at the temperature of 300 ℃ and 500 ℃, so that the urea is decomposed, and the decomposition product NH₃The catalyst is uniformly mixed in the rear section flue, and CO is removed and denitrated simultaneously by a CO oxidant and a denitration catalyst, so that the denitration efficiency of the catalyst is improved, the service life of the catalyst is prolonged, and clean energy-saving emission is finally realized.

Description

CO and NO removal for gas boilerxIntegrated purification device

Technical Field

The utility model discloses contain a certain amount of Nitrogen Oxide (NO) based on in the gas boiler flue gas_x) And carbon monoxide (CO) and other gaseous pollutants, and NO corresponding CO emission standard is provided_xThe purifying method and apparatus for realizing ultralow exhaust belongs to the field of gaseous pollutant treating technology.

Background

With the economic development and the adjustment of energy structures in China, natural gas has the advantages of high calorific value, cleanness, no waste residue generation after combustion and the like compared with energy such as coal, petroleum and the like, and a gas-fired boiler becomes the direction of popularization and development in the future. And the gas boiler inevitably generates NO during the operation_xAnd CO generated by insufficient combustion of fuel. Wherein NO_xThe carbon dioxide is the main precursor of greenhouse effect, acid rain, ozone layer damage, water eutrophication, photochemical smog and haze, and CO is a common toxic and harmful gas, and is a clean fuel, so that direct emission not only causes energy waste, but also has negative effects on human health and atmospheric environment.

Under the conditions of atmospheric pollutant emission limit and increasingly strict environment-friendly law enforcement, the characteristics of the components of the flue gas of the gas boiler are combined, and the CO and NO in the flue gas of the gas boiler are removed_xThe integrated purification method and device have no practical application in the market, so that research and development of the integrated purification method and deviceSynergistic removal of CO and NO from flue gas_xThe integrated control technology has important significance for the clean emission of the gas boiler. At present, NO literature and patent report exists for synergistically removing CO and NO in flue gas of gas-fired boilers_xAnd the like gaseous pollutants.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the defects of the prior art, the utility model discloses a two catalysis methods provide a gas boiler removes CO and takes off NO_xThe integrated purification method and the integrated purification device realize clean and energy-saving emission of flue gas.

In order to achieve the above purpose, the utility model discloses a following technical scheme:

CO and NO removal from flue gas of gas-fired boiler_xIntegrated purification device, characterized in that CO and NO are produced simultaneously_xThe gas boiler is provided with a return flue, the tail end of the return flue is a boiler flue gas outlet, the boiler flue gas outlet is connected with an air inlet of the catalytic reaction device, and an air outlet of the catalytic reaction device is connected with the fan through a waste heat recovery system; a urea solution injection device is arranged in the return flue or/and the boiler flue gas outlet, and is connected with a urea solution storage tank through a urea solution metering device and a flow control device; the catalytic reaction device is of a long tubular or barrel-shaped structure, the central shafts at the two ends of the catalytic reaction device are respectively provided with an air inlet and an air outlet, and the two ends of the catalytic reaction device are of a funnel shape protruding outwards; a guide plate, a CO oxidant layer and a denitration catalyst layer which are all arranged from the air inlet end to the air outlet end in sequence are arranged in the long tubular or barrel-shaped structure of the catalytic reaction device from the air inlet end to the air outlet end to form a multi-section reactor;

further preferably, the injection point of the urea solution injection device, namely the injection point of the denitration reducing agent, is positioned in the section of the return flue of the gas boiler corresponding to the temperature of 300-500 ℃, the urea is decomposed by utilizing the temperature of the flue, and the decomposition product NH is generated₃And the flue gas is uniformly mixed with the flue gas in the rear section of the flue.

And a plurality of CO oxidant layers or/and denitration catalyst layers are/is further arranged in the catalytic reaction device to form multi-stage catalytic reaction.

The gas inlet and the gas outlet of the catalytic reaction device are provided with sampling ports.

Further, the guide plate, the CO oxidant layer and the denitration catalyst layer are fully distributed on the radial surfaces of the CO oxidant layer and the denitration catalyst layer in the catalytic reaction device;

the further guide plate is used for enabling the gas passing through the guide plate to be uniformly distributed in the radial surface of the catalytic reaction device.

The flow control device is a pump or a pump and a valve.

Further, the CO oxidant layer comprises the following components in percentage by weight: 0-1 wt% of Pt, 0-0.5 wt% of Pd and 0-10 wt% of CeO₂0-1.5 wt% of Cu, 0-1.5 wt% of Mn, 0-1.5 wt% of Fe and the balance of carrier TiO₂The above Pt, Pd and CeO₂Cu, Mn and Fe are not all 0, and Pt, Pd and CeO are more preferable₂The mass ratio of Cu to Mn to Fe is 2:1:10:3:1: 2; the CO oxidant is in the shape of round pellets, thin strips, honeycomb extrusion or honeycomb coating.

The denitration catalyst layer comprises the following components in percentage by weight: 0-8 wt% of V₂O₅、0-20wt％WO₃、0-6wt％In₂O₃、 0-10wt％CeO₂0-2 wt% Br (Br is present in the form of ammonium bromide), the balance being support TiO₂And V is₂O₅、WO₃、In₂O₃、CeO₂Br is not 0; preferably V₂O₅、WO₃、In₂O₃、CeO₂The mass ratio of Br to Br is 2:10:1:2: 0.5; the shape of the denitration catalyst is honeycomb extrusion type or honeycomb coating type, and the temperature range of the denitration efficiency of more than 90 percent is 150-360 ℃.

The device is adopted to simultaneously remove CO and NO in the flue gas_xThe method is characterized by comprising the following steps:

the injection point of the denitration reducing agent urea is positioned in a return flue of the gas boiler at 300-500 ℃, the urea is decomposed by utilizing the temperature of the flue, and the decomposition product NH₃Uniformly mixing the flue gas and the flue gas in a rear section flue; the temperature of the flue gas entering the catalytic reaction device after passing through the flue gas outlet of the boiler is 150-200 ℃, the flue gas passes through the CO oxidant layer (9) to convert CO generated by insufficient fuel combustion into harmless COCO₂Simultaneously utilizes oxidation heat release to improve the temperature of the flue gas and reduce O in the flue gas₂Content, which creates favorable conditions for subsequent denitration reaction, improves the denitration efficiency of the catalyst and prolongs the service life of the catalyst; after that NO in the flue gas_xThe ammonia generated by the urea which is the reducing agent sprayed in before efficiently reacts under the action of the denitration catalyst layer to generate clean gas N₂And H₂O, denitration efficiency thereof>90 percent; and collecting heat energy of the flue gas after the denitration reaction by using a waste heat recovery system, and finally connecting a draught fan to discharge the flue gas into a chimney.

Controlling the injection amount of urea so that decomposition product NH is generated₃The amount of the nitrogen-containing gas is just equal to that of NO in the smoke_xThe reaction produces nitrogen and water.

The flue gas purification device in the step 2) is a horizontal reactor, a guide plate, a CO oxidant and a denitration catalyst are distributed in the horizontal reactor, and sampling ports are distributed in a gas inlet and a gas outlet. The CO oxidant and the denitration catalyst are arranged in a reactor box body, so that the number of reaction devices and the pressure drop are reduced.

The utility model discloses an effect and advantage:

1. the injection point of the denitration reducing agent is positioned in a return flue (300-₃And the flue gas is uniformly mixed with the flue gas in the rear section of the flue.

2. The CO oxidant and the denitration catalyst are arranged in a reactor box body to reduce the number of devices and pressure drop; the flue gas firstly passes through a CO oxidant to convert CO generated by insufficient combustion of fuel into harmless CO₂The flue gas temperature is raised by utilizing the heat released by oxidation, so that favorable conditions are created for subsequent denitration reaction, the denitration efficiency of the catalyst is improved, the service life of the catalyst is prolonged, the oxygen content in the flue gas is consumed, the conversion concentration of pollutants is effectively reduced, and the standard reaching rate of pollutant emission is improved.

3. The utility model discloses an used CO oxidant and denitration catalyst all satisfy gas boiler flue gas purification requirement.

4. The flue gas purification device has the advantages of simple structure, convenient construction, compact layout and easy control.

Drawings

FIG. 1 shows a gas boiler for removing CO and NO_xIntegrated purifier sketch map, the essential element includes: the device comprises a combustor 1, a gas boiler 2, a return flue 3, a boiler flue gas outlet 4, a urea solution metering device 5, a control device 6, a urea storage tank 7, a guide plate 8, a CO 9 oxidant layer, a denitration catalyst layer 10, a waste heat recovery system 11, a fan 12, a sampling port 13, a catalytic reaction device 14 and a urea solution injection device 15.

FIG. 2 shows a gas boiler for removing CO and NO in accordance with embodiment 1 of the present invention_xIntegrated small simulation evaluation schematic.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings, but the present invention is not limited to the following description. The following catalyst preparation methods may be prepared by one or more of the methods of the prior art in combination, such as by stacking 201510232554.9 for the denitration catalyst with other methods of the prior art.

Example 1

CO and NO removal for gas boiler_xThe integrated purification device comprises a reducing agent preparation system consisting of a urea dissolving tank, a urea storage tank 7, a metering device 5, a conveying device, a control device 6 and the like, and a flue gas purification device consisting of a flue, a guide plate, a purification reactor box body, a CO oxidant, a denitration catalyst and the like, wherein the small waste heat recovery device collects heat energy and finally is connected with a draught fan to be discharged into a chimney. The utility model discloses well denitration reductant's injection point is located gas boiler return flue (300) and supplyes 500 ℃), utilizes the flue temperature to decompose urea, and decomposition product NH₃And the flue gas is uniformly mixed with the flue gas in the rear section of the flue. The CO oxidant and the denitration catalyst are arranged in a reactor box body to reduce the number of devices and pressure drop; the flue gas firstly passes through a CO oxidant to convert CO generated by insufficient combustion of fuel into harmless CO₂Meanwhile, the temperature of the flue gas is increased by utilizing the heat released by oxidation, favorable conditions are created for subsequent denitration reaction, the denitration efficiency of the catalyst is improved, the service life of the catalyst is prolonged, and CO and haze precursor-NO in the flue gas are effectively reduced_xAnd the emission amount is finally realized, and clean energy-saving emission is realized.

2. CO and NO removal for gas boiler_xIntegrated small simulation experiment

CO and NO removal for gas boiler_xThe integrated small-sized simulation evaluation system consists of N₂、O₂、NO、CO、CO₂(raw flue gas contains), NH₃Iso-high pressure steel cylinder, mass flow controller and display, gas mixer, quartz reactor, tubular electric furnace, thermocouple, temperature controller, NH₃The device comprises a washing bottle, a glass tee joint, an injection pump, a heat tracing band, heat preservation cotton, a testo350 smoke analyzer and the like, wherein pipelines are connected by polytetrafluoroethylene pipes with the diameter of 3 mm.

The catalyst bed is supported in a constant temperature area of the electric heating furnace by quartz wool, an opening above the quartz tube is plugged by a rubber plug, a first thermocouple penetrates through the rubber plug and directly abuts against a gas-solid critical part of the upper end surface of the CO oxidant, the temperature of the catalyst bed is controlled, the denitration reaction is ensured to be carried out under the condition of certain smoke temperature, and the controlled temperature is recorded as T₁A second thermocouple penetrates through the rubber plug and is positioned in a gap between the CO oxidant and the denitration catalyst, the temperature of the flue gas passing through the CO oxidant bed layer is tested, and the measured temperature is recorded as T₂The performance evaluation device is shown in fig. 2. Wherein, the dosage of the CO oxidant is 1.5mL, the dosage of the denitration catalyst is 1.5mL, and the total amount of the flue gas is 1500 mL/min^-1The total space velocity (GHSV) is 30000h^-1. The reaction gas consists of 0.01-0.05% volume fraction of NO and NH₃0.01-0.05% of volume fraction, 0.00-0.02% of CO volume fraction, and CO₂2.0 to 10.0% by volume, O₂1.0-10.0% by volume, H₂5-15% of O by volume and N₂The test temperature range is 150-200 ℃ for balance gas. Detection of O by using testo350 flue gas analyzer₂NO, CO and CO₂And (4) inlet and outlet concentration. When the valve 1 is closed and the valve 2 is opened, the O in the inlet smoke is measured₂、NO、CO、CO₂Concentration, when the valve 1 is opened and the valve 2 is closed, the simulated flue gas passes through the catalyst bed layer, and the O after the reaction is measured at the moment₂、NO、CO、CO₂And (4) concentration.

Specific composition of the CO oxidant layer in the following examples: pt, Pd, CeO₂Six of Cu, Mn and Fe2 percent, 1 percent, 10 percent, 3 percent, 1 percent and 2 percent respectively, and the balance being carrier TiO₂。

The denitration catalyst layer specifically comprises the following components: v₂O₅、WO₃、In₂O₃、CeO₂The mass percentage of the five Br (Br exists in the form of ammonium bromide) is respectively 2 percent, 10 percent, 1 percent, 2 percent and 0.5 percent, and the rest is carrier TiO₂。

Example 1

The experimental conditions are as follows: set temperature T₁At 150 ℃, the volume fraction of NO in the reaction gas component is 0.01 percent, NH₃Volume fraction of 0.01%, volume fraction of CO of 0.01%, CO₂Volume fraction 2.0%, O₂Volume fraction 3.5%, H₂ O volume fraction 10%, N₂Is the balance gas. At this time, the temperature T of the space between the CO oxidizing agent and the denitration catalyst₂The temperature was 151 ℃, the CO oxidation rate was 82%, and the denitration efficiency was 91%.

Example 2

The experimental conditions are as follows: set temperature T₁At 160 ℃, the volume fraction of NO in the reaction gas component is 0.02 percent, NH₃Volume fraction of 0.02%, volume fraction of CO of 0.01%, CO₂Volume fraction 3.0%, O₂Volume fraction 4.5%, H₂Volume fraction of O12%, N₂Is the balance gas. At this time, the temperature T of the space between the CO oxidizing agent and the denitration catalyst₂The temperature was 161 ℃, the CO oxidation rate was 87%, and the denitration efficiency was 93%.

Example 3

The experimental conditions are as follows: set temperature T₁At 175 ℃, the volume fraction of NO in the reaction gas component is 0.03 percent, NH₃Volume fraction of 0.03%, volume fraction of CO of 0.02%, CO₂Volume fraction 4.0%, O₂Volume fraction 5.5%, H₂Volume fraction of O12%, N₂Is the balance gas. At this time, the temperature T of the space between the CO oxidizing agent and the denitration catalyst₂The temperature was 177 ℃, the CO oxidation rate was 91%, and the denitration efficiency was 96%.

Example 4

The experimental conditions are as follows: set temperature T₁At 190 ℃ by volume of the reaction gas component NONumber 0.04%, NH₃Volume fraction of 0.04%, volume fraction of CO of 0.02%, CO₂Volume fraction 6.0%, O₂Volume fraction 7.5%, H₂Volume fraction of O15%, N₂Is the balance gas. At this time, the temperature T of the space between the CO oxidizing agent and the denitration catalyst₂The temperature was 192 ℃, the CO oxidation rate was 94%, and the denitration efficiency was 98%.

Example 5

The experimental conditions are as follows: set temperature T₁At 200 ℃, the volume fraction of NO in the reaction gas component is 0.05 percent, NH₃Volume fraction of 0.05%, volume fraction of CO of 0.02%, CO₂Volume fraction 10.0%, O₂Volume fraction 10.0%, H₂Volume fraction of O15%, N₂Is the balance gas. At this time, the temperature T of the space between the CO oxidizing agent and the denitration catalyst₂The temperature is 202 ℃, the CO oxidation rate is 96 percent, and the denitration efficiency is 99 percent.

Claims

1. CO and NO removal from flue gas of gas-fired boiler_xIntegrated purification device, characterized in that CO and NO are produced simultaneously_xThe gas boiler (2) is provided with a return flue (3), the tail end of the return flue (3) is a boiler flue gas outlet (4), the boiler flue gas outlet (4) is connected with the gas inlet of a catalytic reaction device (14), and the gas outlet of the catalytic reaction device (14) is connected with a fan (12) through a waste heat recovery system (11); a urea solution injection device (15) is arranged in the return flue (3) or/and the boiler flue gas outlet (4), and the urea solution injection device (15) is connected with a urea solution storage tank (7) through a urea solution metering device (5) and a flow control device (6); the catalytic reaction device (14) is of a long tubular or barrel-shaped structure, the positions of central shafts at two ends of the catalytic reaction device are respectively provided with an air inlet and an air outlet, and two ends of the catalytic reaction device (14) are of a funnel shape which protrudes outwards; a guide plate (8), a CO oxidant layer (9) and a denitration catalyst layer (10) which are all up to a shaft are sequentially arranged in the long tubular or barrel-shaped structure of the catalytic reaction device (14) from the air inlet end to the air outlet end to form a multi-section reactor.

2. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xThe integrated purification device is characterized in that the injection point of the urea solution injection device (15), namely the injection point of the denitration reducing agent, is positioned in the section of the return flue (3) of the gas boiler with the corresponding temperature of 300-500 ℃.

3. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xThe integrated purification device is characterized in that a plurality of CO oxidant layers (9) and/or denitration catalyst layers (10) are arranged in a catalytic reaction device (14) to form multi-stage catalytic reaction.

4. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xThe integrated purification device is characterized in that a gas inlet and a gas outlet of the catalytic reaction device (14) are provided with sampling ports (13).

5. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xThe integrated purification device is characterized in that the guide plate (8), the CO oxidant layer (9) and the denitration catalyst layer (10) are fully distributed on the radial surfaces of the catalytic reaction device (14).

6. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xThe integrated purification device is characterized in that the guide plate (8) is used for enabling the gas passing through the guide plate (8) to be uniformly distributed in the radial surface of the catalytic reaction device (14).

7. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xIntegrated purification device, characterized in that the flow control means (6) is a pump or a pump and a valve.

8. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xIntegrated purification device, characterized in that CO is oxidizedThe agent is in the shape of round pill, thin strip, honeycomb extrusion type or honeycomb coating type.

9. The method for removing CO and NO from flue gas of gas-fired boiler according to claim 1_xAn integrated purification apparatus, characterized in that the shape of the denitration catalyst is honeycomb extrusion type or honeycomb coating type.