1. NO inhibition in pulverized coal combustion_xThe method for discharging is characterized in that high-alkali coal ash is used as an inhibitor and added into the coal dust to inhibit NO in the combustion of the coal dust_xAnd (4) generating.

2. The method for inhibiting NO in pulverized coal combustion as claimed in claim 1_xA method of emission, characterized in that said high alkali coal ash is obtained by:

1) the method comprises the following steps of (1) obtaining raw coal of a temple, placing the raw coal in a constant-temperature drying oven, and drying for 12 hours at the temperature of 105 ℃ to obtain dried raw coal;

2) putting the dried raw coal obtained in the step 1) into a muffle furnace, and fully combusting to obtain the high-alkali coal ash.

3. The method for inhibiting NO in pulverized coal combustion as claimed in claim 1_xThe discharging method is characterized in that the adding mass percentage of the high-alkali coal ash in the coal dust is 3.26-9.21%, wherein the high-alkali coal ash and the coal dust are uniformly mixed by mechanical stirring when being added.

4. The method for inhibiting NO in pulverized coal combustion as claimed in claim 1_xThe discharging method is characterized in that the combustion temperature of the pulverized coal is medium-high temperature.

5. The method of claim 1 for inhibiting NO in pulverized coal combustion_xThe emission method is characterized in that the adding mass percentage of the high-alkali coal ash in the coal dust is 6.33%.

6. The method of claim 1 for inhibiting NO in pulverized coal combustion_xThe discharging method is characterized in that the combustion conditions of the pulverized coal are as follows: atmosphere 21% O₂+ 79% Ar, flow 1L/min, programmed temperature from room temperature to 800 ℃, heating rate 10 ℃/min.

7. Use of the method according to claim 1 for NO combustion in high alkali coal boilers in coal-fired utilities, thermal power plants_xAnd (4) emission reduction.

Background

Since the 21 st century, heat and power supply by burning fossil fuels such as coal still dominate the world, however, smoke generated by coal burning contains a large amount of nitrogen oxides, which are one of the main causes of photochemical smog and acid rain, and cause great harm to the nature and human beings.

The existing selective catalytic reduction method for removing nitrogen oxides has high denitration rate, but the one-time investment cost is too high, and a large amount of dust carried in flue gas easily blocks a pipeline and covers the surface of a catalyst to inactivate the catalyst, so that the selective catalytic reduction method cannot be industrially applied in the industries such as ceramics, cement and the like; and selective non-catalytic reduction, the denitration rate is low, the problem of ammonia escape is easy to occur, the environment is polluted, and the cost is additionally increased. The low-nitrogen combustion technology has the advantages of low initial investment, almost zero running cost, short reconstruction construction period, no need of great modification of the boiler, small influence on the running of the boiler, low denitration efficiency and difficult guarantee of standard emission only by adopting a single low-nitrogen combustion technology. In the wet oxidation denitration, a sodium chlorite method is widely used, the denitration effect is good, but the investment and the operation cost are high. The ozone oxidation method is a novel technology, is used more abroad, is in an increasing trend at present in domestic application, is used in various enterprises such as medium petrochemical industry, medium petroleum industry, Chinese chemical industry and the like, has the characteristics of convenient modification, flexible operation, no need of modifying a boiler, no influence on the operation of the boiler and the like, can improve the yield and the quality of a chemical fertilizer when being matched with ammonia desulphurization, but has high power consumption in operation and is greatly influenced by the restriction of an oxygen source. Therefore, it is important to find a method which can be applied in industry, has low cost and low energy consumption and can effectively remove nitrogen oxides.

Disclosure of Invention

In view of the above, the present disclosure provides a method for inhibiting NO in pulverized coal combustion_xMethod of emission and use to address existing NO_xThe emission control technology has the problems of high cost, low removal rate, complex operation and the like.

In one aspect, the invention provides a suppression coalNO in powder combustion_xThe method for discharging is characterized in that high-alkali coal ash is used as an inhibitor and added into the coal dust to inhibit NO in the combustion of the coal dust_xAnd (4) generating.

Preferably, the high-alkali coal ash is obtained by the following steps:

1) the method comprises the following steps of (1) obtaining raw coal of a temple, placing the raw coal in a constant-temperature drying oven, and drying for 12 hours at the temperature of 105 ℃ to obtain dried raw coal;

2) putting the dried raw coal obtained in the step 1) into a muffle furnace, and fully combusting the dried raw coal to obtain high-alkali coal ash;

more preferably, the adding mass percentage of the high-alkali coal ash in the coal dust is 3.26-9.21%, wherein the high-alkali coal ash and the coal dust are uniformly mixed by mechanical stirring during adding.

Further preferably, the temperature of the pulverized coal combustion is medium-high temperature.

More preferably, the adding mass percentage of the high-alkali coal ash in the coal dust is 6.33%.

Further preferably, the combustion conditions of the pulverized coal are as follows: atmosphere 21% O₂+ 79% Ar, flow 1L/min, programmed temperature from room temperature to 800 ℃, heating rate 10 ℃/min.

On the other hand, the invention also provides an application of the method, and the method is applied to NO during combustion of high-alkali coal boilers in coal-fired enterprises and thermal power plants_xAnd (4) emission reduction.

The invention provides a method for inhibiting NO in pulverized coal combustion_xThe method of emission is based on reducing high temperature combustion NO in pulverized coal_xThe source strategy of the pollution emission inhibitor realizes the inhibition of the NO in the flue gas generated by the combustion of the pulverized coal in the boiler under the conditions of medium and high temperature_xAnd (4) generating. The method can realize resource utilization of the high-alkali coal ash waste, save the consumption of catalyst resource production, reduce the cost and simultaneously ensure higher emission reduction effect; the adopted inhibitor has no toxicity, does not produce secondary pollution, and can realize the aim of protecting the environment;

the method provided by the invention can be widely applied to various coal-fired enterprises and thermal power plants, especially after the liquid-state slag-discharging cyclone burner is arranged, the method can be widely applied to the emission reduction of NOx burned by a high-alkali coal boiler, and the circular economic benefit is obvious.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 is a NO provided in accordance with a disclosed embodiment of the invention_xSchematic diagram of time-varying conditions;

FIG. 2 is a NO provided in accordance with a disclosed embodiment of the invention_xGenerating a total amount schematic diagram;

FIG. 3 is a schematic diagram of a reaction mechanism provided in an embodiment of the disclosure.

FIG. 4 is a microscopic reaction path diagram for the heterogeneous reduction of carbocoal nitrogen and NO provided by the disclosed embodiments of the invention.

FIG. 5 is a microscopic reaction path diagram of the heterogeneous reduction of the semi-coke nitrogen and NO by Na, provided by the disclosed embodiment of the invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings, in which like numerals refer to the same or similar elements throughout the different views, unless otherwise specified. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with certain aspects of the invention, as detailed in the appended claims.

Against prior art NO_xThe technical problems of over-high cost, low removal rate, complex operation and the like of the emission control technology are solved, and the embodiment provides a method for inhibiting NO in pulverized coal combustion_xThe method for discharging the high-alkali coal comprises adding ash generated by combustion of the high-alkali coal into the coal powder as an inhibitor to inhibit NO in the combustion of the coal powder_xAnd (4) generating. Ash generated by burning the high-alkali coal is the high-alkali coal ash;

the high-alkali coal ash is obtained by the following steps:

1) the method comprises the following steps of (1) obtaining raw coal of a temple, placing the raw coal in a constant-temperature drying oven, and drying for 12 hours at the temperature of 105 ℃ to obtain dried raw coal;

2) putting the dried raw coal obtained in the step 1) into a muffle furnace, and fully combusting the dried raw coal to obtain high-alkali coal ash; the preferred combustion temperature is 575 ℃, which is a necessary condition for ensuring the reduction of alkali metal volatilization and the sufficient combustion of the high alkali coal.

The adding mass percentage of the high-alkali coal ash in the coal dust is 3.26-9.21%, the high-alkali coal ash and the coal dust are uniformly mixed by mechanical stirring when in adding, and NO is_xThe inhibitor is physically mixed with the coal powder, so that the required denitration investment cost is low, and the equipment is simple and convenient;

proved by verification, when the addition amount of the high-alkali coal ash is 6.33 percent, NO is generated in the combustion process at 800 DEG C_xThe emission reduction efficiency can reach 32 percent at most.

The ash components generated by the combustion of the high-alkali coal are shown in table 1;

TABLE 1T 28 ℃ RH 98% general temple coal ash component

The above method was experimentally verified by the following conditions:

1) respectively putting the different coal samples obtained by mixing the coal samples with the alkaline coal ash with different mass percentages into a tubular furnace, wherein the atmosphere is 21 percent O₂+ 79% Ar, the flow rate is 1L/min, the temperature is programmed to 800 ℃ from room temperature, and the heating rate is 10 ℃/min;

2) using flue gas analyzer notesRecording NO in the course of the experiment_xThe generation of (2);

3) collecting experimental data, making a broken line graph after normalization processing, and obtaining NO by integrating the area of the broken line_xThe total amount is generated.

The invention is further illustrated with reference to specific examples, which are not intended to limit the scope of the invention.

Example 1

(1) Adding about 2g of raw coal of the temple into 0.0675g of alkaline coal ash, mechanically stirring to uniformly mix the raw coal and the alkaline coal ash, and weighing about 50mg of the raw coal as a test sample;

(2) putting the coal sample into a tube furnace for combustion in an atmosphere of 21% O₂+ 79% Ar, the flow rate is 1L/min, the temperature is programmed to 800 ℃ from room temperature, and the heating rate is 10 ℃/min;

(3) recording NO in the course of experiment by using flue gas analyzer_xThe generation of (2);

(4) by comparing NO in raw coal combustion process_xEmission of NO_xThe emission reduction efficiency is about 2.21 percent.

Example 2

(1) Adding 0.1015g of alkaline coal ash into about 2g of raw coal of the temple, mechanically stirring to uniformly mix the raw coal and the alkaline coal ash, and weighing about 50mg of the raw coal as a test sample;

(2) putting the coal sample into a tube furnace for combustion in an atmosphere of 21% O₂+ 79% Ar, the flow rate is 1L/min, the temperature is programmed to 800 ℃ from room temperature, and the heating rate is 10 ℃/min;

(3) recording NO in the course of experiment by using flue gas analyzer_xThe generation of (2);

(4) by comparing NO in raw coal combustion process_xEmission of NO_xThe emission reduction efficiency is about 7.49 percent.

Example 3

(1) Adding 0.1351g of alkaline coal ash into about 2g of raw coal of the temple, mechanically stirring to uniformly mix the raw coal and the alkaline coal ash, and weighing about 50mg of the raw coal as a test sample;

(2) putting the coal sample into a tube furnace for combustion in an atmosphere of 21% O₂+ 79% Ar at a flow rate of 1L/min, programmed from room temperature to 800 deg.CThe temperature rate is 10 ℃/min;

(3) recording NO in the course of experiment by using flue gas analyzer_xThe generation of (2);

(4) by comparing NO in raw coal combustion process_xEmission of NO_xThe emission reduction efficiency is about 32.41%.

Example 4

(1) Adding about 2g of raw coal of the temple into 0.1690g of ash, mechanically stirring to uniformly mix the raw coal and the ash, and weighing about 50mg of the raw coal as a test sample;

(2) putting the coal sample into a tubular furnace for combustion, wherein the atmosphere is 21% O2+ 79% Ar, the flow rate is 1L/min, the temperature is programmed to 800 ℃ from room temperature, and the heating rate is 10 ℃/min;

(3) recording NO in the course of experiment by using flue gas analyzer_xThe generation of (2);

(4) by comparing NO in raw coal combustion process_xEmission of NO_xThe emission reduction efficiency is about 32.93 percent.

Example 5

(1) Adding 0.2029g ash into about 2g of raw coal of temple, mechanically stirring to mix uniformly, and weighing about 50mg as a test sample;

(2) putting the coal sample into a tube furnace for combustion in an atmosphere of 21% O₂+ 79% Ar, the flow rate is 1L/min, the temperature is programmed to 800 ℃ from room temperature, and the heating rate is 10 ℃/min;

(3) recording NO in the course of experiment by using flue gas analyzer_xThe generation of (2);

(4) by comparing NO in raw coal combustion process_xEmission of NO_xThe yield increased by about 11.43%.

In summary, the above examples No_xChange over time and NO_xThe total amount of the product is shown in FIGS. 1 and 2.

As can be seen from the attached figures 1 and 2, in the examples 1 to 4, the NO content gradually increases from 3.26 percent to 7.79 percent along with the addition of the high-alkali coal ash_xIs gradually reduced from 15.04 to 10.24mg, wherein when the ash addition amount is respectively 6.33% and 7.79%, NO is generated in the combustion process at 800 DEG C_xThe emission reduction efficiency reaches 32 percentThe above.

Inhibition of NO in coal combustion process by adding high alkali coal ash to coal fines at medium and high temperatures_xPrecursor generation to effect NO_xAnd (4) the purpose of emission reduction. The embodiment specifically adds the coal ash generated after the high-alkali coal is completely combusted into the high-alkali coal again, and because the high-alkali coal ash contains more metal oxides, the active components of the high-alkali coal ash are mainly alkali metal and alkaline earth metal compounds, the high-alkali coal ash has the function of fixing semicoke nitrogen, and the NO is reduced by inhibiting the conversion of the semicoke nitrogen to gas phase and tar_xThe generation of the precursor, and simultaneously the basic metal has the function of catalyzing heterocyclic nitrogen in the semicoke to reduce NO out of phase, thereby achieving the purpose of controlling NO_xAnd (4) generating.

Specifically, the basic metal element suppresses NO_xThe production mechanism includes two aspects: firstly, the active components (mainly sodium element) such as alkali metal and alkaline earth metal compounds contained in the high-alkali coal ash have the function of fixing the semicoke nitrogen, and NO is reduced by inhibiting the conversion of the semicoke nitrogen to gas phase and tar_xGenerating a precursor; secondly, the alkali metal sodium lowers the highest energy barrier of the reaction path 1 for the heterogeneous reduction of the semicoke nitrogen to NO by 35.7kJ/mol, the highest energy barrier of the reaction path 2 by 40.9kJ/mol and N in the path 2 by 7.2kJ/mol calculated according to the Density Functional Theory (DFT)₂The energy barrier is separated out, the heat release of the whole reaction is increased by 53.2kJ/mol, and the subsequent reaction is favorable to occur in thermodynamics, thereby achieving the purpose of controlling NO_xThe purpose of generation, and show that NO reduction rate increases with increasing ash addition amount_xThe amount of precipitation was reduced and the reaction path calculated theoretically is shown in FIG. 3. However, if the ash is added in an excessively high amount, the NO reduction rate cannot be further increased, but the heterogeneous reduction of NO is suppressed, resulting in NO_xThe amount of precipitation increased as in example 5. In example 5, when the ash content was 9.21%, NO was observed during combustion at 800 deg.C_xThe emission is increased by 11.43 percent compared with that of the raw coal, because the excessive alkali metal and alkaline earth metal ions in the coal ash occupy the active sites at the edge of the semicoke nitrogen molecules, the ability of the semicoke after the pyrolysis of the raw coal to adsorb NO is reduced, and the ability of the semicoke to reduce NO out-phase is reduced, thereby reducing the NO_xThe amount of precipitation.

In conclusion, the addition of a proper amount of high alkali coal ash is helpful for controlling NO_xThe amount of NO discharged during combustion at 800 ℃ when the ash content is 6.33%_xThe maximum emission reduction efficiency can reach 32 percent. Excessive high-alkali coal ash is added to weaken the capability of the semicoke nitrogen after pyrolysis of the raw coal for heterogeneous NO reduction, so that NO is generated_xIncreased emissions, adverse control of NO_xAnd (4) discharging.

The method provided by the embodiment can realize resource utilization of high-alkali coal ash waste, saves resource consumption of catalyst production, reduces cost, can realize the aim of environmental protection, can be widely applied to various coal-fired enterprises and thermal power plants, and can be used for burning NO in a high-alkali coal boiler after being particularly provided with a liquid-state slag-discharging cyclone burner_xThe emission reduction and the recycling economic benefit are obvious.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.