Flexible and adjustable combustion system of ammonia-doped pulverized coal boiler

Abstract

The utility model discloses a flexible and adjustable ammonia-doped pulverized coal boiler combustion system, which comprises a pulverizing device, a combustor and a horizontal boiler which are connected in sequence, a plurality of ammonia injection devices are arranged below the horizontal boiler, each ammonia injection device comprises a nozzle with adjustable angle, flow and / or flow velocity, and the nozzle is connected with the combustor. The input end of the ammonia injection device is connected with the ammonia storage device through an ammonia conveying pipeline; and the tail part of the horizontal boiler is connected with the SNCR denitration device. According to the utility model, the combustion efficiency of pulverized coal is improved by doping ammonia, and particularly, stable combustion is ensured by adjusting the proportion of ammonia under the condition that the coal quality changes greatly; ammonia and nitrogen oxide can react to generate nitrogen and water, so that the emission of NOx is reduced; ammonia is injected from the lower portion of the boiler, the mixing uniformity of pulverized coal particles and air is improved, an outlet of the combustor is in a local air-rich area, combustion and burnout of pulverized coal are facilitated, the carbon content of fly ash is reduced, and the higher the ammonia doping proportion is, the higher the burnout rate of the pulverized coal is.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of combustion equipment, and concretely relates to a flexible and adjustable ammonia-doped pulverized coal boiler combustion system. BACKGROUND

[0002] At present, the ammonia-doped pulverized coal boiler related research gradually develops from the laboratory to the pilot stage, ammonia as fuel has the problems of high NOx emission, slow burning rate, difficult ignition and the like, the current ammonia coal mixed combustion regulation technology is biased towards fuel grading and air grading, and is not perfect in the specific way of doping ammonia, the mixing uniformity of ammonia needs to be improved, and the effect of reducing NOx emission by doping ammonia cannot be fully played. SUMMARY

[0003] The utility model solves the technical problems that: provide a kind of flexible and adjustable ammonia-doped pulverized coal boiler combustion system, solve the problem such as poor ammonia combustion effect of existing system, realize the flexibility of strengthening ammonia combustion atmosphere in wide range regulation process, better match with the temperature, atmosphere and other environments in boiler furnace, thereby improve the beneficial effect of ammonia on pulverized coal combustion efficiency and the effect of reducing NOx emission.

[0004] According to the technical scheme of the utility model, the utility model provides a kind of flexible and adjustable ammonia-doped pulverized coal boiler combustion system, including the powder preparation device, combustor and horizontal boiler that are connected in sequence, the horizontal boiler lower portion is provided with several ammonia injection devices, ammonia injection device includes angle, flow and / or adjustable nozzle of flow rate, the input end of ammonia injection device is connected ammonia storage device by ammonia delivery pipeline;Horizontal boiler tail portion is connected with SNCR denitration device.

[0005] Further, the pulverized coal inlet of the combustor is connected with a primary air pipeline, and the upper portion of the combustor is connected with a hot secondary air pipeline.

[0006] Further, the ammonia delivery pipeline has at least one ammonia preheating pipeline.

[0007] Further, the ammonia injection device is multiple or multiple groups distributed along the length direction of the horizontal boiler.

[0008] Further, the output end of the ammonia injection device is directed to the main combustion zone in the horizontal boiler.

[0009] Further, the SNCR denitration device is installed at the tail portion of the horizontal boiler.

[0010] Further, temperature detectors, oxygen concentration detectors and ammonia gas concentration detectors are arranged in the horizontal boiler and the SNCR denitration device, and the temperature detectors, oxygen concentration detectors and ammonia gas concentration detectors are connected with a monitoring system.

[0011] Further, the burner is connected with a primary air pipe and a secondary air pipe, the primary air pipe is connected with a primary air flow control device, and the secondary air pipe is connected with a secondary air flow control device; the pulverizing device, the ammonia injection device, the primary air flow control device and the secondary air flow control device are connected with the monitoring system.

[0012] Compared with the prior art, the utility model has the beneficial technical effects as follows:

[0013] 1、The utility model discloses a multi-stage ammonia injection is strengthened fuel and air space matching is set up, and the flexibility of ammonia combustion atmosphere in wide range adjustment process is strengthened, and the influence of ammonia injection position and mode is mainly related to the temperature of injection position and local atmosphere (O2 content, NOx content etc.

[0014] 2、The utility model discloses that the pulverized coal combustion efficiency is improved through mixing ammonia, especially under the condition that the coal quality changes greatly, and stable combustion is guaranteed through adjusting the proportion of ammonia, ammonia and nitrogen oxide can react to generate nitrogen and water, and reduce NOx emission, ammonia is sprayed into the internal flame area of boiler from the lower part of boiler, and the mixing uniformity of pulverized coal particles and air is increased, the burner outlet is local rich air area, and it is favorable to the combustion and burnout of pulverized coal, the carbon content of fly ash is reduced, and the higher the proportion of mixing ammonia is, the higher the burnout rate of pulverized coal is. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the system structure schematic drawing provided by the utility model.

[0016] Mark explanation in the drawing:

[0017] 1, pulverizing device;2, ammonia storage device;3, ammonia injection device;4, burner;5, horizontal boiler;6, SNCR denitration device;7, monitoring system;8, ammonia preheating pipe. DETAILED DESCRIPTION

[0018] The utility model provides a kind of flexible adjustable ammonia mixed coal powder boiler combustion system, or a kind of coal powder boiler combustion system mixed with ammonia and ammonia adjustment method belongs to combustion technical field.The ammonia mixed coal powder boiler combustion system of the utility model includes: pulverizing device, ammonia storage device, ammonia injection device, burner, horizontal boiler, SNCR denitration device and monitoring system, wherein pulverizing device is directly connected with burner, and it enters inside boiler with air;Ammonia storage device and ammonia injection device are connected in series, and ammonia is injected into inside boiler from below boiler at specific angle and rate, and mixed combustion with coal powder and air;SNCR denitration device is connected to the tail of boiler;The temperature, oxygen concentration and ammonia concentration of inside boiler and SNCR denitration device are monitored and controlled by monitoring system.The scheme mixes ammonia and traditional energy coal powder, which helps to absorb surplus renewable energy generation and reduces carbon emission intensity of fossil fuel combustion.

[0019] Please refer to Figure 1 The utility model provides a kind of flexible adjustable ammonia mixed coal powder boiler combustion system, including the pulverizing device 1 of being connected in turn, burner 4 and horizontal boiler 5, the pulverizing device 1 is used to provide coal powder, burner 4 is located on horizontal boiler 5 and is connected with horizontal boiler 5 inside hearth intercommunication, when working, coal powder is transported into burner 4, and then into horizontal boiler 5.Horizontal boiler 5 is the structure of transverse size is long, and coal powder and air will flow and burn in it.Several ammonia injection devices 3 are arranged below horizontal boiler 5, and the nozzle of ammonia injection device 3 includes angle, flow and / or adjustable flow rate, and the input end of ammonia injection device 3 is connected with ammonia storage device 2 through ammonia delivery pipeline;Optionally, ammonia injection device 3, ammonia delivery pipeline and / or ammonia storage device 2 are provided with device for controlling ammonia flow;So that NH3 can be injected into horizontal boiler 5 from lower part in the required specific way (adjustable parameters include injection angle, flow, flow rate, etc.).Among them, the nozzle with adjustable angle, flow and / or flow rate refers to the nozzle with at least one of angle, flow and / or flow rate adjustment function, such nozzle (and related components) is prior art, but not seen in the field of ammonia mixed boiler.

[0020] Ammonia injection device 3 is preferably distributed as multiple or multiple groups along the length direction of horizontal boiler 5.As shown in Figure 1 Horizontal boiler 5 can be divided into main combustion zone, burnout zone and post-flame zone according to combustion condition, main combustion zone is located at the section of horizontal boiler 5 close to burner 4, and ammonia injection device 3 is distributed in main combustion zone, burnout zone and post-flame zone;One ammonia injection device 3 or multiple (a group) ammonia injection devices 3 can be optionally arranged at each distribution point in length direction.In the illustrated embodiment, ammonia delivery pipeline includes main pipeline and parallel branch pipeline, the input end of main pipeline is connected with ammonia storage device 2, and each ammonia injection device 3 is connected with the end of each branch pipeline.

[0021] In a typical embodiment, the output end of the ammonia injection device 3 is directed towards the main combustion zone in the horizontal boiler 5; the specific direction can be pre-set and / or adjusted in real time according to actual needs. The ammonia delivery pipeline preferably has at least one ammonia preheating pipeline 8, for example located at the main pipeline, and is further preferably preheated using the surplus heat energy of the boiler system, for example having a heat exchanger on the ammonia preheating pipeline 8 to exchange heat with the boiler flue gas, etc. The ammonia storage device 2 stores one of ammonia gas, liquid ammonia or ammonia water, which is preheated and then fed into the ammonia injection device 3, and the position, angle and rate of ammonia injection into the horizontal boiler 5 are accurately controlled.

[0022] The pulverized coal inlet of the burner 4 is connected with a primary air pipeline, and the fine coal powder prepared by the coal pulverizing device 1 is sent to the burner 4 by the primary air. The primary air pipeline is opposite to the hearth of the horizontal boiler 5, for example, the pipeline between the coal pulverizing device 1 and the burner 4 is the primary air pipeline. The burner 4 is connected with a hot secondary air pipeline above the burner 4, which is used to input the secondary hot air. This kind of primary air and secondary air setting mode is convenient for adjusting the air volume, atmosphere and flame condition in the hearth, etc.

[0023] The tail of the horizontal boiler 5 is connected with the SNCR denitration device 6. Specifically, for example, the SNCR denitration device 6 is directly installed at the tail of the horizontal boiler 5. The horizontal boiler 5 and the SNCR denitration device 6 are managed by the monitoring system 7. Temperature detectors, oxygen concentration detectors and ammonia concentration detectors are arranged in the horizontal boiler 5 and the SNCR denitration device 6, and the temperature detectors, oxygen concentration detectors and ammonia concentration detectors are connected with the monitoring system 7. Specifically, the burner 4 is connected with a primary air pipeline and a secondary air pipeline (for example, the hot secondary air pipeline mentioned above), the primary air pipeline is connected with a primary air flow control device, and the secondary air pipeline is connected with a secondary air flow control device; the coal pulverizing device 1, the ammonia injection device 3, the primary air flow control device and the secondary air flow control device are connected with the monitoring system 7. In other words, the monitoring system 7 sets temperature detectors, oxygen concentration detectors and ammonia concentration detectors for the horizontal boiler 5 and the SNCR denitration device 6, and the temperature detectors, oxygen concentration detectors and ammonia concentration detectors feed back information to the coal pulverizing device 1, the ammonia injection device 3 and the primary and secondary air inlets of the burner 4 according to the actual working conditions.

[0024] The concept, principle and beneficial technical effects of the present application are further explained based on a more specific preferred embodiment.

[0025] The coal pulverizing device grinds the coal into fine coal powder with a particle size of about 1 μm to 300 μm, which is sent into the boiler through the burner with the primary air.

[0026] The burner inlet is provided with primary air, which functions to inject a coal powder gas stream into the furnace through the burner to provide basic oxygen for the combustion of the coal powder; the burner is provided with hot air above the secondary air, which is used to control the total air volume, to achieve low-nitrogen combustion by stratified air supply and optimization of the air volume. The ratio of the secondary air to the primary air is 2.2-2.5, which jointly adjusts the center height of the furnace flame and controls the flame deflection. During the combustion process, the flame shape changes greatly with the increase of NH3. When the ammonia content is less than 20%, the flame remains a normal vortex flame; when the ammonia content exceeds 40%, the ammonia injection rate is reduced to avoid the internal recirculation zone of the flame being completely penetrated by high-speed NH3; when the ammonia mixing ratio is 50%, the oxygen concentration of the secondary air is increased to 30% to maintain the furnace temperature level equivalent to the conventional coal-fired condition.

[0027] The in-furnace temperature of the coal-fired boiler is as high as 1300-1600°C, and the residual heat energy of the coal-fired boiler system is used to preheat the ammonia gas and air, thereby improving the ignition and combustion characteristics of the ammonia gas. The ammonia storage device stores one of ammonia gas, liquid ammonia or ammonia water, which is preheated and then sent to the ammonia injection device below the horizontal boiler to be injected into the main combustion zone at a specific position, angle and rate, mixed with the coal powder and air for combustion. The ammonia gas jet should not penetrate the coal powder gas stream and the air gas stream, so as to fully promote the inhibition of the generation of NOx in the oxidation process of the ammonia gas to the coke and to improve the local combustion temperature to promote the oxidation of the coke.

[0028] The ammonia coal and air are strongly disturbed and suspended in the furnace for combustion, and the combustion process of the fuel is completed in about a few seconds. The boiler combustion condition is mainly monitored and adjusted by the monitoring controller to monitor and adjust the temperature, oxygen concentration and ammonia concentration in the boiler and the SNCR denitration device, so as to ensure that the NOx emission and ammonia escape meet the environmental requirements.

[0029] About 90% of the ash produced after combustion in the form of fine ash is discharged from the furnace along with the flue gas after heat exchange on each stage of the heating surface of the boiler. Under the condition of controllable ammonia escape, the escaped ammonia gas is fully utilized for the SNCR, and a low-temperature SNCR device is additionally installed in the boiler flue gas post-processing system to achieve energy saving and emission reduction.

[0030] The utility model discloses a multistage ammonia injection enhances the flexibility of ammonia combustion atmosphere in wide range adjustment process through setting up time and space matching of ammonia injection and air, the influence of ammonia injection position and mode is mainly related with the temperature of injection position and local atmosphere (O2 content, NOx content etc.) and the combustion and residence time after NH3 injection, research shows that compared with NH3 from combustor into furnace, the NOx emission detected at the export is lower when NH3 is injected into furnace from side wall, and, the closer injection position is to combustor, the lower total NOx emission is, the influence of ammonia injection position is also observed in multi-combustor test furnace (2.39MW), when NH3 is injected from the combustor located at the lower part of furnace, the generated NOx concentration is lower than that when NH3 is injected from all combustors evenly, based on this, ammonia is determined to be sprayed into the internal flame area of boiler from the position directly below the boiler, the utility model discloses improve the combustion efficiency of pulverized coal through ammonia mixing, especially in the case of great change of coal quality, ensure stable combustion through adjusting the proportion of ammonia, ammonia and nitrogen oxide can react to generate nitrogen and water, reduce NOx emission, ammonia is sprayed into the boiler from below, increase the mixing uniformity of pulverized coal particles and air, the combustor export is local rich air area, is favorable to the combustion and burnout of pulverized coal, the carbon content of fly ash is reduced, and, the higher the proportion of ammonia mixing is, the higher the burnout rate of pulverized coal is.

Claims

1. A flexible, adjustable, ammonia-doped, pulverized coal boiler combustion system, characterized by, The device comprises a pulverizing device (1), a burner (4) and a horizontal boiler (5) connected in sequence, a plurality of ammonia injection devices (3) are arranged below the horizontal boiler (5), the ammonia injection devices (3) comprise nozzles with adjustable angles, flow rates and / or flow velocities, input ends of the ammonia injection devices (3) are connected to an ammonia storage device (2) through an ammonia delivery pipeline, and a tail portion of the horizontal boiler (5) is connected to an SNCR denitration device (6).

2. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system of claim 1, wherein, The burner (4) is connected to a primary air pipeline at a coal powder inlet thereof, and is connected to a hot secondary air pipeline above the burner (4).

3. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system of claim 1, wherein, The ammonia delivery pipeline comprises at least one ammonia preheating pipeline (8).

4. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system of claim 1, wherein, The ammonia injection devices (3) are arranged in multiple groups along a length direction of the horizontal boiler (5).

5. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system in accordance with claim 1, wherein, Output ends of the ammonia injection devices (3) are directed to a main combustion zone in the horizontal boiler (5).

6. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system of claim 1, wherein, The SNCR denitration device (6) is installed at a tail portion of the horizontal boiler (5).

7. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system of claim 1, wherein, Temperature detectors, oxygen concentration detectors and ammonia concentration detectors are arranged in the horizontal boiler (5) and the SNCR denitration device (6), and the temperature detectors, the oxygen concentration detectors and the ammonia concentration detectors are connected to a monitoring system (7).

8. The flexible, adjustable, ammonia-doped, pulverized coal fired boiler combustion system of claim 7, wherein, The burner (4) is connected to a primary air pipeline and a secondary air pipeline, the primary air pipeline is connected to a primary air flow control device, the secondary air pipeline is connected to a secondary air flow control device, and the pulverizing device (1), the ammonia injection devices (3), the primary air flow control device and the secondary air flow control device are connected to the monitoring system (7).

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