阅读说明：本技术 一种反α形火焰配风式层燃炉燃烧系统及方法 (Reverse alpha-shaped flame air distribution type grate-fired furnace combustion system and method ) 是由 杜谦 高建民 栾积毅 赵义军 冷浩 崔朝阳 赵广播 吴少华 秦裕琨 于 2020-11-20 设计创作，主要内容包括：一种反α形火焰配风式层燃炉燃烧系统及方法,它属于锅炉技术领域。它包括前拱、后拱、炉排和配风系统；前拱和后拱分别倾斜布置,前拱的顶部高度小于后拱的顶部高度,后拱的长度小与前拱的长度,且前拱与后拱的夹角为钝角,前拱、后拱和分隔板分隔为前区和后区,前区为燃烧区,后区为冷却区；所述配风系统包括主管、风机、排烟管和多个配风管；排烟管和多个配风管的一端与主管连接,多个配风管的另一端分别由前拱或后拱伸入燃烧室,每个配风管上设有一个调节阀,排烟管的另一端伸入冷却排烟区,主管与现有锅炉的空气预热器连通,主管和排烟管上分别设有一个风机。本发明减少氮氧化合物生成,减少排烟损失。(A combustion system and a method of a reverse alpha-shaped flame air distribution type grate-fired furnace belong to the technical field of boilers. It comprises a front arch, a rear arch, a fire grate and an air distribution system; the front arch and the rear arch are respectively obliquely arranged, the top height of the front arch is smaller than that of the rear arch, the length of the rear arch is smaller than that of the front arch, an included angle between the front arch and the rear arch is an obtuse angle, the front arch, the rear arch and the partition plate are divided into a front area and a rear area, the front area is a combustion area, and the rear area is a cooling area; the air distribution system comprises a main pipe, a fan, a smoke exhaust pipe and a plurality of air distribution pipes; the one end of discharging fume pipe and a plurality of air distribution pipes is connected with being responsible for, and the other end of a plurality of air distribution pipes stretches into the combustion chamber by preceding arch or back arch respectively, is equipped with an governing valve on every air distribution pipe, and the other end of discharging fume the pipe stretches into cooling exhaust area, is responsible for the air heater intercommunication with current boiler, is responsible for and is equipped with a fan on the pipe of discharging fume respectively. The invention reduces the generation of nitrogen oxides and reduces the loss of smoke exhaust.)

1. An anti-alpha-shaped flame air distribution type grate-fired furnace combustion system comprises a front arch (1), a rear arch (2) and a fire grate (3); a fire grate (3) is arranged below the front arch (1) and the rear arch (2);

the method is characterized in that: the front arch (1) and the rear arch (2) are respectively obliquely arranged, the top height (H1) of the front arch (1) is smaller than the top height (H2) of the rear arch (2), the length of the rear arch (2) is smaller than that of the front arch (1), the included angle between the front arch (1) and the rear arch (2) is an obtuse angle, the front arch, the rear arch and the partition plate are divided into a front area and a rear area, the front area is a combustion area, the rear area is a cooling area, and the combustion area between the front arch (1) and the rear arch (2) can generate anti-alpha-shaped flame;

the combustion system also comprises an air distribution system, and the air distribution system comprises a main pipe (4-1), a fan, a smoke exhaust pipe (4-2) and a plurality of air distribution pipes (4-3); one end of the smoke exhaust pipe (4-2) and one end of the air distribution pipes (4-3) are connected with the main pipe (4-1), the other ends of the air distribution pipes (4-3) extend into the combustion chamber through the front arch (1) or the rear arch (2) respectively, each air distribution pipe (4-3) is provided with an adjusting valve, the other end of the smoke exhaust pipe (4-2) extends into the cooling smoke exhaust area, the main pipe (4-1) is communicated with an air preheater of the existing boiler, and the main pipe (4-1) and the smoke exhaust pipe (4-2) are provided with a fan respectively.

2. The combustion system of the inverted α -shaped flame air distribution grate furnace of claim 1, wherein: one air distribution pipe (4-3) of the air distribution pipes (4-3) extends into the pyrolysis zone below the front arch (1).

3. The combustion system of the inverted α -shaped flame air distribution grate furnace of claim 2, wherein: the included angle (beta) between the front arch (1) and the horizontal plane is 25-30 degrees.

4. The combustion system of the inverted α -shaped flame air distribution grate furnace of claim 3, wherein: the included angle (theta) between the rear arch (2) and the horizontal plane is 40-45 degrees.

5. A low-nitrogen combustion method of a combustion system of a reverse alpha-flame air-distribution grate-fired furnace according to any one of claims 1 to 4, characterized in that: it comprises the following steps: the hot air from the air preheater is sent into the main pipe (4-1) by the drive of the fan, after the hot air is mixed with the high-temperature flue gas from the cooling area by the drive of the fan, the slag after the pulverized coal combustion falls into the tail end of the rear arch (2), the fan brings the unburned volatile components and the unburned gas of the slag into the main pipe (4-1) through the smoke exhaust pipe (4-2) and mixes the slag with the hot air in the main pipe (4-1), and the mixed high-temperature gas is sent into the combustion area through the air distribution pipe (4-3) and is combusted in a recycling mode, so that the combustion is more sufficient.

Technical Field

The invention relates to a boiler and a boiler combustion method, in particular to a combustion system and a combustion method of a reverse alpha-shaped flame air distribution type grate-fired furnace, and belongs to the technical field of boilers.

Background

The grate-fired furnace is widely used due to simple structure, convenient operation and low requirements on the quality of the furnace operator, the occupation ratio of the grate-fired furnace in an industrial boiler is up to 90% according to statistics, the grate-fired furnace is applied to various industrial fields such as building materials, chemical engineering, printing and dyeing, heat treatment, pharmacy and the like, and is an important combustion mode of the boiler in China. The heat loss of the grate-fired furnace is a factor influencing the combustion efficiency of the grate-fired furnace, and the existing grate-fired rate has the following problems:

1. the existing grate-fired furnace has poor combustion control and difficult coal bed burnout, and data show that the carbon content of the furnace ash can reach 30-40% under many conditions. For example, in the patent application of the invention, namely 'a reciprocating grate stoker' (application number: 201310365289.2, application date: 2013.08.19), coal is ignited by using rear arch reradiation, and the grate is lengthened to burn the coal out, so that the problem of difficult coal burning out is not thoroughly solved, and the size of a furnace body is increased.

2. The alpha flame formed by the front arch and the rear arch is adopted, and because the airflow with high volatile content at the front part and the high-temperature oxygen-enriched airflow at the rear part are difficult to realize good mixing and are combustible gas, the unburned gas in the flue gas is more, and the problem of larger excess air coefficient in the flue gas exists, thus causing larger heat loss of the flue gas; (ii) a Meanwhile, under the low-load working condition, alpha flame is difficult to form, and more gas is neutralized by smoke and unburnt gas. The heat loss of the exhaust smoke occupies a great proportion in the heat loss of the boiler, and the reduction of the heat loss of the exhaust smoke is one of the energy-saving directions of the boiler. For example, the invention patent of a composite control system for the emission of nitrogen oxides of a grate-fired furnace (patent number: ZL201610963638.4, application date: 2016.10.28) adopts a PLC control system embedded with a grate-fired furnace staged combustion control system, obtains the temperature field distribution in the height direction of the grate-fired furnace under different loads through field measurement and numerical simulation, and establishes a grate-fired furnace temperature field database, thereby not completely solving the problem of excessive unburnt gas.

3. The alpha flame of the grate-fired furnace draws the high-oxygen and high-temperature flue gas in the rear arch into the pyrolysis zone, so that a large amount of nitrogen oxides are generated. Currently, grate-fired furnaces NO_xThe emission control technology mainly takes flue gas recirculation and selective non-catalytic reduction (SNCR) as main technologies or a combination technology thereof. The smoke recycling technology has the problems of increasing the carbon content of ash, further reducing the temperature of a hearth and the like, and the heat efficiency of the grate-fired furnace is reduced. The SNCR technology uses ammonia water with lower reaction temperature as a reducing agent due to limited hearth space and low furnace temperature of a grate-fired furnace, so that the problems of difficult searching of effective ammonia spraying points, insufficient reduction reaction time, rising of ammonia escape rate and the like are frequently encountered, and the problem of serious atmospheric pollution caused by ammonia escape is also solved. For example, the invention patent application of a flue gas recirculation coupling denitration system for a chain grate furnace (application number: 201610817509.4, application date: 2016.09.12) adopts a coupling technology, and has the problems of non-uniform temperature distribution, limited space and low temperature of a hearth, which are easily caused.

Disclosure of Invention

In order to solve the above problems, the present invention provides a combustion system of a reverse alpha-shaped flame distribution type grate-fired furnace and a low-nitrogen combustion method.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an anti-alpha-shaped flame air distribution type grate-fired furnace combustion system comprises a front arch, a rear arch, a grate and an air distribution system; fire grates are arranged below the front arch and the rear arch; the front arch and the rear arch are respectively obliquely arranged, the top height of the front arch is smaller than that of the rear arch, the length of the rear arch is smaller than that of the front arch, an included angle between the front arch and the rear arch is an obtuse angle, the front arch, the rear arch and the partition plate are divided into a front area and a rear area, the front area is a combustion area, the rear area is a cooling area, and the combustion area between the front arch and the rear arch can generate reverse alpha-shaped flame; the air distribution system comprises a main pipe, a fan, a smoke exhaust pipe and a plurality of air distribution pipes; the one end of discharging fume pipe and a plurality of air distribution pipes is connected with being responsible for, and the other end of a plurality of air distribution pipes stretches into the combustion chamber by preceding arch or back arch respectively, is equipped with an governing valve on every air distribution pipe, and the other end of discharging fume the pipe stretches into cooling exhaust area, is responsible for the air heater intercommunication with current boiler, is responsible for and is equipped with a fan on the pipe of discharging fume respectively.

A low-nitrogen combustion method comprising: the hot air that comes from air heater is sent into the person in charge by the fan drive, after mixing with the high temperature flue gas that comes out from the cooling space by the fan drive, the slag after the buggy burning falls into the end of encircleing after, the fan takes the slag not burnt volatile and not burnt gas into the main pipe and mixes with the hot-air in the main pipe through the pipe of discharging fume, the high temperature gas after the mixture sends into the combustion space through the air distribution pipe, the recirculated combustion, the burning produces anti alpha shape flame, it is more abundant to make the burning.

Compared with the prior art, the invention has the following beneficial effects:

the front arch is lower than the rear arch, the inclination angle of the front arch is smaller than that of the rear arch, the front arch is relatively long and lower, the rear arch is relatively short and higher in design, inverse alpha-shaped flame is formed during pulverized coal combustion, an air distribution system is arranged to enable combustion flue gas to be mixed with preheated air for recirculation combustion, the problem that unburned gas is too much is solved, meanwhile, the high-temperature flue gas is beneficial to combustion, the combustion temperature of a burnout area is improved, and the carbon content of ash slag and the incomplete combustion loss of a solid phase are reduced. The combustion area between the front arch and the rear arch generates reverse alpha-shaped flame, thereby avoiding high-oxygen and high-temperature flue gas from being involved in a pyrolysis area (the lower end of the front arch) and reducing the generation of nitrogen oxides.

Aiming at the unburned volatile components and unburned gas generated by combustion on the fire grate, mixed high-temperature gas of high-temperature flue gas from a cooling area and hot air from an air preheater is introduced from a front arch or a rear arch at the corresponding position of the fire grate, and accurate air distribution in the combustion process is realized by utilizing a distribution system.

And thirdly, after the coal is added into the boiler, the water is evaporated firstly, then the volatile components are volatilized, and the volatilization speed is high when the temperature is high. The volatile components are all hydrocarbons, and what substances are formed after the volatile components are volatilized greatly differs from the volatile components in an oxygen-rich environment or an oxygen-poor environment. When volatilized in the presence of oxygen, the hydrocarbon becomes a hydroxyl compound in the presence of oxygen, and the hydroxyl compound and oxygen form an aldehyde. Direct combustion of a portion of the aldehyde to H₂O and CO₂(ii) a The other part is decomposed into H₂And CO, then combusted, and H₂And CO is readily combustible. When the volatile component is volatilized in the absence of oxygen, hydroxyl compounds are not formed due to the absence of oxygen, and thermal decomposition is carried out to form H₂And carbon black (C). H₂Readily combustible to form H₂O, thereby causing difficulty in ignition; by introducing high-temperature oxygen-enriched flue gas, volatilization is promoted to be analyzed out and easily ignitable components are formed, and the ignition problem of a pyrolysis zone (a zone below the front arch) of the front arch is solved.

Drawings

FIG. 1 is a schematic of the present invention.

Detailed Description

The first embodiment is as follows: referring to fig. 1, a combustion system of a reverse alpha-shaped flame air distribution type grate-fired furnace according to the present embodiment includes a front arch 1, a rear arch 2 and a grate 3; a fire grate 3 is arranged below the front arch 1 and the rear arch 2; also comprises a wind distribution system 4; the front arch 1 and the rear arch 2 are respectively obliquely arranged, the top height HA of the front arch 1 is smaller than the top height HB of the rear arch 2, the length of the rear arch 2 is smaller than that of the front arch 1, an included angle between the front arch 1 and the rear arch 2 is an obtuse angle, the front arch, the rear arch and the partition plate are divided into a front area and a rear area, the front area is a combustion area, the rear area is a cooling area, and the combustion area between the front arch 1 and the rear arch 2 can generate reverse alpha-shaped flame; the air distribution system 4 comprises a main pipe 4-1, a fan, a smoke exhaust pipe 4-2 and a plurality of air distribution pipes 4-3; one end of the smoke exhaust pipe 4-2 and one end of the air distribution pipes 4-3 are connected with the main pipe 4-1, the other ends of the air distribution pipes 4-3 extend into the combustion chamber from the front arch 1 or the rear arch 2 respectively, each air distribution pipe 4-3 is provided with a regulating valve, the other end of the smoke exhaust pipe 4-2 extends into the cooling smoke exhaust area, the main pipe 4-1 is communicated with an air preheater of the existing boiler, and the main pipe 4-1 and the smoke exhaust pipe 4-2 are respectively provided with a fan.

The second embodiment is as follows: referring to fig. 1, one air distribution pipe 4-3 among the plurality of air distribution pipes 4-3 of the present embodiment extends into the pyrolysis zone below the front arch 1. The preheating zone, the pyrolysis zone and the ignition zone are respectively arranged below the front arch from left to right, the middle part is a main combustion zone, and the right side is a burnout zone 5. The problem that the pyrolysis area of the front arch 1 is difficult to catch fire is solved by introducing high-temperature mixed flue gas into the pyrolysis area of the front arch 1. High-temperature gas is introduced into the pyrolysis area of the front arch to ignite the hot gas, so that the ignition problem is solved; the cooling area is utilized to reduce the temperature of the ash discharged from the fire grate and reduce the physical heat loss of the ash, and simultaneously, the oxygen-enriched high-temperature flue gas discharged from the cooling area is led into the front arch and the rear arch, so that the part of gas is fully utilized. Other components and connections are the same as in the first embodiment.

The third concrete implementation mode: as explained in conjunction with fig. 1, the angle β between the front arch 1 and the horizontal plane in this embodiment is 25 ° to 30 °. The length of the front arch 1 is increased as much as possible, so that the burning flame forms an anti-alpha flame on the front arch 1 and the rear arch 2. Other components and connection relationships are the same as those in the second embodiment.

The fourth concrete implementation mode: referring to fig. 1, the rear arch 2 of the present embodiment has an angle θ of 40 ° to 45 ° with respect to the horizontal plane. The length of the front arch 1 is larger than that of the rear arch 2, so that the burning flame forms an anti-alpha flame on the front arch 1 and the rear arch 2. Other compositions and connection relations are the same as those of the third embodiment.

The fifth concrete implementation mode: referring to fig. 1, a low-nitrogen combustion method of a combustion system of a reverse α -shaped flame air distribution type grate-fired furnace according to the present embodiment includes the following steps: the hot air from the air preheater is driven by the fan to be sent into the main pipe 4-1, the hot air is mixed with the high-temperature flue gas from the cooling area driven by the fan, the slag after the pulverized coal combustion falls into the tail end of the rear arch 2, the fan brings the unburned volatile components and the unburned gas of the slag into the main pipe 4-1 through the smoke exhaust pipe 4-2 and mixes the slag with the hot air in the main pipe 4-1, and the mixed high-temperature gas is sent into the combustion area through the air distribution pipe 4-3 and is combusted in a recycling mode, so that the combustion is more sufficient.