阅读说明：本技术 炉排型循环流化床垃圾焚烧锅炉及其工作方法 (Grate type circulating fluidized bed waste incineration boiler and working method thereof ) 是由 蒋敏华 高洪培 袁野 王海涛 时正海 孙献斌 肖平 于 2020-07-27 设计创作，主要内容包括：本发明公开的一种炉排型循环流化床垃圾焚烧锅炉及其工作方法,属于生活垃圾焚烧烟气处理技术领域。锅炉前料仓与进料装置连接,进料装置与给料炉排连接,给料炉排末端与锅炉进料口连接；输送炉排的一端设在锅炉进料口下方,另一端与排渣管连接；输送炉排上设有流化布风装置,流化布风装置与一次风系统连接；炉膛与二次风管连接；炉膛上方与水平烟道连接,水平烟道与返料系统的入口连接,返料系统的返料出口通过返料立管与锅炉的返料口连接,返料系统的烟气出口连接至尾部烟道。提高了给料和排渣的稳定性,从而使燃烧均匀、稳定,减少了有害污染物的排放,提高了锅炉的效率,避免了停炉风险。(The invention discloses a grate type circulating fluidized bed waste incineration boiler and a working method thereof, and belongs to the technical field of household waste incineration flue gas treatment. The front stock bin of the boiler is connected with a feeding device, the feeding device is connected with a feeding grate, and the tail end of the feeding grate is connected with a feed port of the boiler; one end of the conveying grate is arranged below the feed port of the boiler, and the other end of the conveying grate is connected with the slag discharge pipe; the conveying grate is provided with a fluidization air distribution device which is connected with a primary air system; the hearth is connected with a secondary air pipe; the upper part of the hearth is connected with a horizontal flue, the horizontal flue is connected with an inlet of a material returning system, a material returning outlet of the material returning system is connected with a material returning opening of the boiler through a material returning vertical pipe, and a smoke outlet of the material returning system is connected to a tail flue. The stability of feeding and slag discharging is improved, so that the combustion is uniform and stable, the emission of harmful pollutants is reduced, the efficiency of the boiler is improved, and the risk of blowing out is avoided.)

1. A grate type circulating fluidized bed waste incineration boiler is characterized by comprising a boiler front bin (1), a feeding device (2), a feeding grate (3), a primary air system, a conveying grate (6), a slag discharge pipe (7), a hearth (9), a secondary air pipe (10), a horizontal flue (11), a material returning system and a material returning vertical pipe (18);

the front stock bin (1) of the boiler is connected with a feeding device (2), the feeding device (2) is connected with a feeding grate (3), and the tail end of the feeding grate (3) is connected with a feed inlet of the boiler; one end of the conveying grate (6) is arranged below the feed inlet of the boiler, and the other end of the conveying grate is connected with the slag discharge pipe (7); the conveying grate (6) is provided with a fluidization air distribution device which is connected with a primary air system; the hearth (9) is connected with a secondary air pipe (10); the upper part of the hearth (9) is connected with a horizontal flue (11), the horizontal flue (11) is connected with an inlet of a material returning system, a material returning outlet of the material returning system is connected with a material returning port of the boiler through a material returning vertical pipe (18), and a smoke outlet of the material returning system is connected to a tail flue.

2. The grate type circulating fluidized bed waste incineration boiler of claim 1, characterized in that the feeding grate (3) is arranged in the enclosed space, and the inlet of the feeding grate (3) is connected with a feeding sealing air pipe (8).

3. A grate-type circulating fluidized bed waste incineration boiler according to claim 1, characterized in that the feeding device (2) is a horizontally reciprocating pusher and the feeding grate (3) is an inclined reciprocating grate.

4. The grate-type circulating fluidized bed waste incineration boiler of claim 1, wherein the boiler feed openings include a heavy material feed opening and a light material feed opening, and a height of the light material feed opening is greater than a height of the heavy material feed opening.

5. The grate-type circulating fluidized bed waste incineration boiler of claim 1, characterized in that a slag discharge baffle (20) is provided at the junction of the conveying grate (6) and the slag discharge pipe (7).

6. The grate type circulating fluidized bed waste incineration boiler of claim 1, wherein the primary air system comprises a primary air pipe (4) and an air chamber (5), the air chamber (5) comprises a front section air chamber (5-1), a middle section air chamber (5-2) and a tail section air chamber (5-3), and the front section air chamber (5-1), the middle section air chamber (5-2) and the tail section air chamber (5-3) are respectively connected with the primary air pipe (4) through regulating valves; the air volume of the middle section air chamber (5-2) is larger than that of the end section air chamber (5-3) and larger than that of the front section air chamber (5-1).

7. The grate type circulating fluidized bed waste incineration boiler of claim 1, wherein the secondary air pipes (10) comprise a plurality of first secondary air pipes (10-1) and a plurality of second secondary air pipes (10-2), the plurality of first secondary air pipes (10-1) are uniformly distributed on one side of the hearth (9) along the height direction of the hearth (9), and the plurality of second secondary air pipes (10-2) are uniformly distributed on the other side of the hearth (9) along the height direction of the hearth (9).

8. The grate-type circulating fluidized bed waste incineration boiler of claim 1, wherein the return system comprises a separator central drum (12), a separator (13), an outlet flue (14), a separator lower riser (15) and a return feeder (16); the separator central cylinder (12) is connected with an outlet flue (14), and the outlet flue (14) is connected with a tail flue; an inlet of a separator (13) is connected with a horizontal flue (11), an outlet below the separator (13) is connected with a lower vertical pipe (15) of the separator, the lower vertical pipe (15) of the separator is connected with an inlet of a material returning device (16), an external bed heat exchanger (17) is arranged in the material returning device (16), the material returning device (16) is connected with a material returning air chamber (19), and an outlet of the material returning device (16) is connected with a material returning port of a boiler through a material returning vertical pipe (18).

9. A grate-type circulating fluidized bed waste incineration boiler according to claim 1, characterized in that the conveying grate (6) is of chain type.

10. The method for operating a grate-type circulating fluidized bed waste incineration boiler as recited in any one of claims 1 to 9, comprising:

the garbage materials in the front storage bin (1) of the boiler are conveyed to the feeding grate (3) through the feeding device (2), then are conveyed to a feeding port of the boiler through the feeding grate (3), and are fluidized and combusted on the conveying grate (6) under the action of a primary air system and a fluidized air distribution device, secondary air enters a hearth (9) through a secondary air pipe (10) to support combustion, non-combustible large particles and slag generated after combustion are conveyed to a slag discharge pipe (7) through the conveying grate (6) to be discharged, dust-containing flue gas enters a material returning system through a horizontal flue (11) above the hearth (9), and after being treated by the material returning system, the flue gas enters a tail flue through a flue gas outlet, and returning materials return to the hearth (9) through a returning vertical pipe (18).

Technical Field

The invention belongs to the technical field of domestic garbage incineration flue gas treatment, and particularly relates to a grate type circulating fluidized bed garbage incineration boiler and a working method thereof.

Background

Since 2010, the cleaning and transporting amount of the household garbage is increased year by year, and a large amount of solid waste has great harm to the environment, mainly manifested by land encroachment, atmosphere pollution, soil and water body pollution, and the caused harm is difficult to recover. The existing municipal domestic waste disposal technology has low level, needs a large amount of capital for domestic waste disposal, has serious environmental pollution and the like, and becomes one of the important bottlenecks which influence the domestic living environment of China and restrict the urban development. At present, three methods of landfill, composting and incineration are basically adopted in China in the aspect of solving the problem of municipal solid waste. Compared with landfill and compost, the incineration method has the characteristics of volume reduction, weight reduction, on-site treatment, high treatment speed, heat energy recovery, high harmless degree and the like, so that the domestic garbage incineration power generation is taken as an important way for developing new energy and domestic garbage disposal in various countries.

At present, the household garbage incineration technology is mainly divided into three types, namely, moving grate incineration technology, circulating fluidized bed incinerator technology and rotary kiln incineration technology. The rotary furnace has high requirement on the sealing property of equipment, high cost and high price, and is mainly applied to burning medical domestic garbage or dangerous waste. The grate furnace has the greatest advantages of stable and reliable operation and small fly ash amount, and most of solid household garbage can be directly fed into the furnace for combustion without any pretreatment. However, the following problems still exist at present: the investment cost of the equipment is high, and the occupied area is large; the distribution and combustion of the temperature of the fire grate and the upper hearth are unstable and uneven, the burnout rate is low, and the original emission concentration of pollutants such as NOx is overhigh; the tail smoke environment-friendly equipment is complex and high in operation cost.

Circulating fluidized bed domestic garbageThe boiler fuel has strong adaptability, and the dense-phase zone has a large amount of high-temperature materials, so the combustion efficiency is high. Meanwhile, due to the adoption of a low-temperature and staged combustion mode, the generation amount of NOx is less. In the aspect of environmental protection, the high-efficiency in-furnace SNCR denitration, in-furnace dry desulfurization and deacidification processes are adopted, and the system is simple and reliable. With the requirement of further improving the conventional pollutant indexes of the household garbage incineration plant, compared with a grate furnace, the circulating fluidized bed household garbage boiler has the advantages of low NOx and SO content₂And the removal of pollutants such as HCl and the like has obvious advantages in investment and operation cost. However, the existing circulating fluidized bed domestic garbage boilers generally have the problems of unstable feeding and combustion, large fly ash amount, high maintenance frequency and the like. How to solve the problem of stable feeding and slag discharging of the fluidized bed domestic garbage boiler and further exert the advantages of combustion efficiency and environmental protection becomes the research and development focus of the next stage.

Disclosure of Invention

In order to solve the defects in the prior art, the invention aims to provide the grate type circulating fluidized bed waste incineration boiler and the working method thereof, which improve the stability of feeding and deslagging, so that the combustion is uniform and stable, the emission of harmful pollutants is reduced, the combustion efficiency of the boiler is improved, and the risk of furnace shutdown is avoided.

The invention is realized by the following technical scheme:

the invention discloses a grate type circulating fluidized bed waste incineration boiler which comprises a boiler front bin, a feeding device, a feeding grate, a primary air system, a conveying grate, a slag discharge pipe, a hearth, a secondary air pipe, a horizontal flue, a material returning system and a material returning vertical pipe, wherein the feeding device is arranged in the front bin;

the front stock bin of the boiler is connected with a feeding device, the feeding device is connected with a feeding grate, and the tail end of the feeding grate is connected with a feed port of the boiler; one end of the conveying grate is arranged below the feed port of the boiler, and the other end of the conveying grate is connected with the slag discharge pipe; the conveying grate is provided with a fluidization air distribution device which is connected with a primary air system; the hearth is connected with a secondary air pipe; the upper part of the hearth is connected with a horizontal flue, the horizontal flue is connected with an inlet of a material returning system, a material returning outlet of the material returning system is connected with a material returning opening of the boiler through a material returning vertical pipe, and a smoke outlet of the material returning system is connected to a tail flue.

Preferably, the feeding grate is arranged in the closed space, and the inlet of the feeding grate is connected with a feeding sealing air pipe.

Preferably, the feeding device is a horizontal reciprocating type plate pushing machine, and the feeding grate is an inclined reciprocating grate.

Preferably, the boiler feed openings comprise a heavy material feed opening and a light material feed opening, and the height of the light material feed opening is greater than the height of the heavy material feed opening.

Preferably, a slag discharge baffle is arranged at the joint of the conveying grate and the slag discharge pipe.

Preferably, the primary air system comprises a primary air pipe and an air chamber, the air chamber comprises a front section air chamber, a middle section air chamber and a tail section air chamber, and the front section air chamber, the middle section air chamber and the tail section air chamber are respectively connected with the primary air pipe through regulating valves; the air volume of the middle section air chamber is larger than that of the end section air chamber and larger than that of the front section air chamber.

Preferably, the secondary air pipe includes a plurality of first secondary air pipes and a plurality of second secondary air pipes, and a plurality of first secondary air pipes along the furnace direction of height equipartition in one side of furnace, and a plurality of second secondary air pipes along the furnace direction of height equipartition in the opposite side of furnace.

Preferably, the material returning system comprises a separator central cylinder, a separator, an outlet flue, a separator lower vertical pipe and a material returning device; the separator central cylinder is connected with the outlet flue, and the outlet flue is connected with the tail flue; the inlet of the separator is connected with the horizontal flue, the outlet below the separator is connected with the vertical pipe at the lower part of the separator, the vertical pipe at the lower part of the separator is connected with the inlet of the material returning device, an external bed heat exchanger is arranged in the material returning device, the material returning device is connected with a material returning air chamber, and the outlet of the material returning device is connected with a material returning port of the boiler through the material returning vertical pipe.

Preferably, the transfer grate is chain-type.

The invention discloses a working method of the grate type circulating fluidized bed waste incineration boiler, which comprises the following steps:

the garbage material in the front stock bin of the boiler is delivered to a feeding grate through a feeding device, then is delivered to a feeding port of the boiler through the feeding grate, is fluidized and combusted on a conveying grate under the action of a primary air system and a fluidized air distribution device, secondary air enters a hearth through a secondary air pipe to support combustion, non-combustible large particles and slag generated after combustion are conveyed to a slag discharge pipe through the conveying grate to be discharged, dust-containing flue gas enters a material returning system through a horizontal flue above the hearth, the dust-containing flue gas is treated by the material returning system, the flue gas enters a tail flue through a flue gas outlet, and the returned material returns to the hearth through a material returning vertical pipe.

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

the existing fluidized bed domestic garbage boiler has the problems of unstable feeding and slag discharging and the like due to the nature of garbage fuel, and the unstable material circulation process can cause unstable combustion, overhigh CO emission, unsmooth slag discharging, hardened materials and even the risk of furnace shutdown. The grate type circulating fluidized bed waste incineration boiler utilizes the advantages of the grate system and the chain system on the feeding and deslagging system, and household waste fuel is fed into a hearth by the feeding grate and is discharged by the conveying grate in a transmission manner while being combusted. Different from the traditional spiral feeding mode of the fluidized bed garbage furnace, the feeding grate can stably feed garbage materials with multiple components and complex shapes into a hearth for combustion. Meanwhile, the conveying grate can stably discharge the slag blocks which are difficult to fluidize and burn in the household garbage smoothly. The stable feeding and deslagging can thoroughly solve the problems of unstable combustion and high CO emission concentration of the original system. The problem of hardening of the system caused by the fact that materials cannot be smoothly discharged can be reduced due to stable slag discharge, and the operation stability of the system is greatly improved. The fluidized bed furnace hearth form and the material returning system integrally depend on high-concentration material particles to realize heat and mass transfer, so that the temperature uniformity of the whole furnace hearth is greatly improved, meanwhile, the reciprocating combustion mode under the action of the material returning system prolongs the retention time of fuel, is favorable for the sufficient combustion of the fuel, and improves the boiler efficiency. Meanwhile, the secondary air can supplement oxygen for the hearth, so that oxygen-deficient areas are reduced, the insufficient combustion condition is avoided, the generation of CO can be controlled, and the overall combustion uniformity is improved.

On the environment-friendly level, the uniformity and the residence time of the overall temperature of the hearth are very important for the formation of dioxin. In general, PCDD/Fs (dioxin) is formed by two mechanisms, one mechanism is from homogeneous reaction, and the temperature range is 500-800 ℃. The main processes are the rearrangement of chlorinated precursors, such as Chlorophenol (CP) and chlorobenzene (CBz). The PCDD/Fs in this process is called homogeneous PCDD/Fs or high-temperature PCDD/Fs. The PCDD/Fs can also form a reaction through a heterogeneous reaction, and the temperature range is 200-400 ℃. Heterogeneous reactions are mainly formed by CP, CBz, or carbon in fly ash, i.e. de novoprocess (source generation), under the catalytic action in fly ash. For different dioxin generation mechanisms, the high-temperature environment can realize the complete decomposition and damage of dioxin and precursors thereof, thereby achieving the purpose of reducing dioxin. At present, the widely used 3T (temperature, time, turbulence) + E (excess air factor) control technology mainly means that the hearth can reach 850 ℃, 2s or more harsh treatment working conditions. In terms of turbulence intensity, the product of the geometry of the high-temperature zone of the fluidized bed and the flow velocity of the flue is greater than that of the grate furnace, and thus the turbulence is more severe. In addition, for the coupling of temperature and residence time, the combustion mode of fluidized bed also has more advantages, because it is the mode of room combustion and relies on high concentration material to carry out heat and mass transfer, furnace temperature controllability is stronger, and the whole homogeneity is better, easily obtains higher temperature, and then more is favorable to the decomposition of dioxin and predecessor. The more uniform the temperature of the hearth is, the longer the residence time of the high-temperature area is, and the decomposition rate of dioxin can be remarkably improved. In conclusion, the invention adopts the fire grate system to convey the fuel, utilizes the chain system to distribute air and discharge slag to the fuel, and carries out fluidized combustion through the fluidized bed hearth and the material returning system, thereby ensuring stable combustion, more uniform temperature of the whole hearth and longer combustion residence time. And then realize on the premise of not adding the active carbon adsorption device of afterbody, realize that the dioxin of domestic waste incineration under the different loads discharges up to standard.

Furthermore, the feeding grate is arranged in the closed space, and the inlet of the feeding grate is connected with a feeding sealing air pipe, so that a feeding system can be sealed, the foreign odor is ensured to leak, the environmental pollution is prevented, and the operation environment is improved.

Furthermore, the feeding device adopts a horizontal reciprocating type plate pushing machine, so that the efficiency is high, the stability is high, and the feeding speed is controllable; the feeding grate adopts an inclined reciprocating grate, is suitable for burning garbage materials with high moisture and ash content, and has the advantages of stable, energy-saving and reliable feeding, and no local excess or oxygen deficiency because the fuel is always matched with air supply. High overall combustion efficiency and low carbon content in ash.

Furthermore, the height of the light material feeding port is higher, the combustion effect can be enhanced, the height of the heavy material feeding port is lower, and the damage to the conveying grate below the conveying grate is avoided.

Further, arrange the sediment baffle on the one hand and can control the material and arrange the sediment under the chain effect, on the other hand can make the flue gas can return furnace, plays certain sealed effect.

Furthermore, the air chamber is divided into a front section air chamber, a middle section air chamber and a tail section air chamber, and the air volume is reasonably distributed, so that the combustion efficiency can be further improved. The front section air chamber is mainly used for sealing the gap between the chain furnace and the hearth, the middle section air chamber is the main body of the whole air distribution device and provides oxygen required by fuel combustion, fluidized combustion of garbage materials can be realized, and the tail section air chamber is mainly used for providing air required in the chain deslagging and burnout process.

Furthermore, a plurality of secondary air pipes are arranged at different heights on two sides of the hearth in a layered mode, and oxygen can be supplemented to different areas of the hearth in a multi-layer air distribution mode, so that CO generation can be further controlled, and the overall combustion uniformity is improved.

Furthermore, the material returning system adopts a mode of combining the separator and the external bed heat exchanger, and the problem of insufficient heating surface in the hearth can be solved by the high-temperature superheater in the external bed heat exchanger. Meanwhile, most of corrosive atmosphere and elements prone to coking exist in the form of gas phase and submicron particles, and cannot be trapped by the separator and enter the external bed. Therefore, the problems of high-temperature corrosion and coking of the flue gas in the process of burning the household garbage can be well solved by using the external bed heat exchanger.

Furthermore, the conveying grate is of a chain type, the structure is stable and reliable, the whole structure is convenient to arrange the air distribution device, the air distribution holes are uniformly arranged, and the fluidization effect is good.

The working method of the grate type circulating fluidized bed waste incineration boiler improves the feeding and slag discharging stability, so that the combustion is uniform and stable, the discharge of harmful pollutants is reduced, the efficiency of the boiler is improved, the risk of blowing out is avoided, and the working method has good application prospect.

Drawings

FIG. 1 is a schematic view of the overall structure of embodiment 1 of the present invention;

FIG. 2 is a view A-A of FIG. 1;

FIG. 3 is a view B-B of FIG. 1;

fig. 4 is a schematic view of the overall structure of embodiment 2 of the present invention.

In the figure: 1-a boiler front storage bin, 2-a feeding device, 3-a feeding grate, 4-a primary air pipe, 5-an air chamber, 5-1-a front section air chamber, 5-2-a middle section air chamber, 5-3-a tail section air chamber, 6-a conveying grate, 7-a slag discharge pipe, 8-a feeding sealing air pipe, 9-a hearth, 10-a secondary air pipe, 10-1-a first secondary air pipe, 10-2-a second secondary air pipe, 11-a horizontal flue, 11-1-a first horizontal flue, 11-2-a second horizontal flue, 12-a separator central cylinder, 13-a separator, 13-1-a first separator, 13-2-a second separator, 14-an outlet flue and 15-a separator lower vertical pipe, 16-a material returning device, 17-an external bed heat exchanger, 18-a material returning vertical pipe, 19-a material returning air chamber and 20-a slag discharging baffle.

Detailed Description

The invention will now be described in further detail with reference to the following drawings and specific examples, which are intended to be illustrative and not limiting: