CN211694898U - High-temperature waste incineration furnace grate system based on material circulation - Google Patents

Abstract

The utility model discloses a high temperature waste incineration furnace grate system based on material circulation belongs to msw incineration and clean burning technical field. Comprises a grate furnace, a primary air fan, a primary air steam preheater, an air preheater, an economizer, a flue gas treatment system, a chimney, a conveying fluidized fan and a separator; the fine sand material is added in the grate furnace and used as a heat carrying medium, so that the internal combustion of the grate furnace is enhanced, the uniformity of the temperature in the whole furnace is improved, and the formation of a concentrated high-temperature area is avoided. Meanwhile, the primary air is heated by the steam heater and the air preheater, so that the combustion intensity in the grate furnace is further improved, local low-temperature areas are reduced, and the emission of harmful substances is effectively reduced.

Description

High-temperature waste incineration furnace grate system based on material circulation

Technical Field

The utility model belongs to the technical field of msw incineration and clean burning, concretely relates to high temperature msw incineration grate furnace system based on material circulation.

Background

The national domestic garbage clearing and transporting amount in 2016 is about 21500.5 ten thousand tons. A large amount of solid wastes bring great harm to the environment, which is mainly manifested by land invasion, pollution to the atmosphere, soil and water, and difficult recovery of the caused harm. It is specifically stated in "thirteen five" hazardous waste pollution control that the access of available or incineratable hazardous waste to landfills is strictly restricted. At present, although the proportion of waste incineration treatment in China is rapidly improved, because the classification of waste sources in China is not effectively carried out, smoke dust, fly ash and slag are generated in the combustion process, and a large amount of dioxin and heavy metal elements are contained in the fly ash. These pollutants are extremely harmful to the atmosphere, the soil, the sea and the fresh water ecosystems, especially they can also be bio-enriched through the food chain, eventually creating environmental problems. After the garbage is incinerated, the final products are discharged smoke, fly ash and incineration residues. The incineration ash is generally divided into two types, bottom ash and fly ash, and the bottom ash generally comprises furnace slag and grate ash. The bottom ash accounts for about 80 percent of the total amount of the ash, and mainly comprises slag, black and nonferrous metals, ceramic fragments, glass and other incombustible matters and unburned organic matters. The fly ash is residue collected in a flue gas purification system and a heat recovery system, and accounts for about 20% of the total amount of ash.

The domestic garbage is easy to generate secondary pollution in the incineration process, and the fly ash is a main carrier of the secondary pollution. Since the fly ash contains various harmful heavy metal substances and salts such as Cd, Pb, Cu, Zn and Cr which can be leached by water, and high-concentration dioxin organic pollutants with the strongest toxicity are also enriched, the municipal solid waste incineration fly ash is definitely specified to be dangerous waste by national records of dangerous wastes, namely the number of the municipal solid waste incineration fly ash is HW18, and the fly ash must be treated strictly according to the standard of the dangerous waste. The control technology of special pollutants such as heavy metal, dioxin and the like is mainly divided into control before incineration, control during incineration and control after incineration. Before incineration, the control mainly comprises the steps of enhancing pretreatment (garbage classification and sorting) of the garbage, adding special additives and reducing generation of heavy metals and dioxin in the garbage incineration process. The control in incineration is mainly started from two aspects: on one hand, the temperature distribution, the combustion atmosphere and the residence time are controlled through a reasonable combustion organization, so that heavy metals stay in bottom slag or fly ash as much as possible, and the subsequent ash treatment is facilitated. On the other hand, a more effective adsorbent is developed, and a proper adsorption temperature interval is selected for removing the heavy metal adsorbent. After incineration, the fly ash containing more harmful substances is mainly treated in a related way so as to reduce the harmless degree of the fly ash. The post-incineration control technology has various ways, and mainly comprises a solidification stabilization treatment technology, a chemical treatment technology and a heat treatment technology. Compared with the control technology before and after incineration, if the generation of special pollutants can be reduced in the incineration process, the subsequent treatment cost can be greatly reduced, and the investment and the operating pressure of treatment equipment are reduced.

Patent document No. CN107191941A discloses a household garbage incineration treatment process and system for reducing incineration flue gas pollutants, which is to transfer household garbage into a garbage incinerator for primary combustion, simultaneously add petroleum coke and calcium carbonate into the garbage incinerator, and perform secondary combustion on flue gas generated by the primary combustion and odor generated when the household garbage is stored. The system requires secondary combustion, the treatment system is complex, and the operating cost is high. Patent document CN101029727A discloses a cyclone melting furnace for fly ash from waste incineration. The corresponding garbage is preheated, dried and ignited under the action of high-temperature air in the primary air box, so that the high-temperature combustion process of the garbage is completed. The system does not relate to a specific scheme corresponding to high-temperature air heating and the relation between the overall combustion temperature and the resultant heavy metal and dioxin.

Disclosure of Invention

In order to solve the defect that exists among the above-mentioned prior art, the utility model aims to provide a high temperature waste incineration grate furnace system based on material circulation has reinforceed the inside burning of grate furnace, has promoted the homogeneity of whole stove internal temperature, has avoided concentrating the regional formation of high temperature, has effectively reduced harmful substance's emission.

The utility model discloses a following technical scheme realizes:

the utility model discloses a high-temperature waste incineration grate furnace system based on material circulation, which comprises a grate furnace, a primary air fan, a primary air steam preheater, an air preheater, an economizer, a flue gas treatment system, a chimney, a conveying fluidized fan and a sorting machine;

the primary air fan is connected with the primary air steam preheater, the primary air steam preheater is connected with the air inlet of the air preheater, and the air outlet of the air preheater is connected with the primary air inlet of the grate furnace; a sand material feeding port is formed in a hearth of the grate furnace, and a tail heating surface of the grate furnace is communicated with a sorting machine through a slag falling pipe; a light material outlet and a conveying fluidization fan of the separator are connected with a sand material feeding port through a fine sand material conveying pipe for conveying fine sand materials; a heavy material outlet of the separator is connected with a slag discharge pipe; the smoke outlet of the tail heating surface is connected with the smoke inlet of the air preheater, and the smoke outlet of the air preheater is sequentially connected with the economizer, the smoke treatment system and the chimney.

Preferably, the sand material inlet is arranged above the drying section of the fire grate.

Preferably, the classifier is a fluidized classifier, and the classifier is connected with a conveying fluidized fan.

Preferably, the fine sand material is quartz sand, river sand or coal ash.

Preferably, the particle size of the fine sand material is < 10 mm.

Preferably, a quick discharging and detaching device is arranged at the bent pipe of the fine sand conveying pipe.

Preferably, the fine sand conveying pipe is provided with a plurality of air supply branch pipes.

Compared with the prior art, the utility model discloses following profitable technological effect has:

the utility model discloses a high temperature waste incineration grate furnace system based on material circulation adds fine sand material in the grate furnace, carries the medium as the heat, has reinforceed the inside burning of grate furnace, has promoted the homogeneity of whole stove internal temperature, has avoided concentrating the formation of high temperature region. Meanwhile, the primary air is heated by the steam heater and the air preheater, so that the combustion intensity in the grate furnace is further improved, the local low-temperature area is reduced, and the decomposition rate of harmful substances is improved.

The combustion temperature is crucial to the migration of heavy metals and the formation of dioxins, and heavy metals are classified into three categories according to volatility: non-volatile elements, semi-volatile elements and volatile elements. Nonvolatile elements such as Mn, Ni, Cu, Cr and the like are mainly distributed in low slag after being burnt; semi-volatile elements such As Cd, Pb, Zn, As and the like are partially or completely gasified in the incineration process, and physical changes such As nucleation, heterogeneous condensation and the like occur in the subsequent cooling process, and finally the semi-volatile elements are enriched on fine particles and fired to form heavy metal fine particles which are not easy to be captured by a dust remover; volatile elements such as Hg, Se, etc. are highly susceptible to gasification during incineration, primarily in gaseous form, and are vented to the atmosphere. The volatilization release rate of metal can be greatly improved by increasing the incineration temperature, certain heavy metal can be promoted to be separated out like gas phase by increasing the combustion temperature, nano-to micron-sized particles are formed in the condensation process, and the particles can be collected in the dust removal and desulfurization processes. In general, researchers believe that PCDD/Fs (dioxins) are formed by two mechanisms. One 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 novo process (source generation), under the catalytic action in fly ash. For different dioxin generation mechanisms, the dioxin in the fly ash is thoroughly decomposed and destroyed in a high-temperature environment, so that the aim of reducing the dioxin is fulfilled. Research results show that when the combustion temperature is higher than 1200 ℃, the decomposition rate of dioxin can be obviously improved. The decomposition characteristics of the conditions such as temperature and atmosphere on the fly ash melting process show that the higher the melting temperature, the higher the decomposition rate, and the higher the oxidative atmosphere decomposition rate than the inert atmosphere.

Therefore, the utility model discloses a temperature of fine sand material circulation and air promotes, the fire grate furnace internal combustion can all be reinforceed, promote the homogeneity of whole stove internal temperature, the formation of concentrating the high temperature region has been avoided, reduce local low temperature region, it is long that the material is in the regional dwell time of high temperature, when the combustion temperature promotes to 1100 ~ 1200 ℃, dioxin decomposition rate can show the improvement, and simultaneously, the heavy metal is further through appearing, nucleation, by follow-up pollutant desorption equipment entrapment in the reunion process gets into the flying dust, the flue gas that discharges reaches emission standard more easily.

Furthermore, the sand material feeding port is arranged above the drying section of the fire grate, the feeding is not influenced by the position of the inlet, and meanwhile, fine sand materials are easy to roll along with the fire grate to fill the whole hearth, so that the aim of enabling the temperature distribution to be more uniform is fulfilled.

Furthermore, the fluidized separator is selected as the separator, so that fine sand materials with small and light density and slag materials with large and heavy density can be effectively separated, and the efficiency is high.

Furthermore, quartz sand, river sand or coal ash residue have strong heat storage capacity and low cost, the particle size of the fine sand material is less than 10mm, on one hand, the fine sand material is easy to heat and store heat, and meanwhile, the small particle size of the fine sand material also ensures that the fine sand material can be carried by flue gas and cannot be accumulated on the surface of the grate.

Furthermore, because the local resistance of the elbow is large, the speed of fluidized fine sand is reduced at the elbow, the energy is reduced, the blockage is easily caused, and the quick discharging and detaching device is arranged at the elbow of the fine sand conveying pipe, so that the elbow can be conveniently treated, and the maintenance is convenient.

Furthermore, a plurality of air supply branch pipes are arranged on the fine sand conveying pipe, so that the blockage caused by bridging can be effectively reduced, the efficiency and distance of fine sand conveying are improved, and the reliability and stability of the system are improved.

Drawings

FIG. 1 is a schematic view of the system configuration and process flow of the present invention;

in the figure: 1-primary air fan, 2-primary air steam preheater, 3-air preheater, 4-economizer, 5-flue gas treatment system, 6-chimney, 7-tail heating surface, 8-hearth, 9-conveying fluidized fan, 10-fine sand conveying pipe, 11-sorting machine, 12-slag falling pipe and 13-sand material feeding port.

Detailed Description

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

the utility model relates to a high-temperature waste incineration furnace grate system based on material circulation, as shown in figure 1, comprising a grate furnace, a primary air fan 1, a primary air steam preheater 2, an air preheater 3, an economizer 4, a flue gas treatment system 5, a chimney 6, a conveying fluidized fan 9 and a separator 11;

the primary air fan 1 is connected with the primary air steam preheater 2, the primary air steam preheater 2 is connected with the air inlet of the air preheater 3, and the air outlet of the air preheater 3 is connected with the primary air inlet of the grate furnace; the hearth 8 of the grate furnace is provided with a sand material inlet 13, and the sand material inlet 13 can be arranged above the drying section of the grate. A heated surface 7 (comprising a primary evaporator, a high-temperature superheater, a medium-temperature superheater, a low-temperature superheater, a secondary evaporator and the like) at the tail part of the grate furnace is communicated with a separator 11 through a slag falling pipe 12;

a light material outlet of the separator 11 and a conveying fluidized fan 9 are connected with a sand material feeding port 13 through a fine sand material conveying pipe 10 for conveying fine sand materials; a heavy material outlet of the separator 11 is connected with a slag discharge pipe; the classifier 11 can be a fluidized classifier, the classifier 11 is connected with the conveying fluidized fan 9, and the conveying fluidized fan 9 can provide fluidized airflow for the classifier 11. The fine sand material can be selected from quartz sand, river sand or coal ash with the particle size less than 10mm, a quick discharging and detaching device can be arranged at the bent pipe of the fine sand material conveying pipe 10, and a straight pipe section with overlong length can be arranged as appropriate, so that the fine sand material conveying pipe is convenient to overhaul and maintain in the blockage process. Considering the on-way resistance of the straight pipe section and the local resistance of the bent pipe section, the fine sand conveying pipe 10 is provided with a plurality of air supply branch pipes to prevent blockage caused by bridging.

The flue gas outlet of the tail heating surface 7 is connected with the flue gas inlet of the air preheater 3, and the flue gas outlet of the air preheater 3 is sequentially connected with the economizer 4, the flue gas treatment system 5 (comprising a semi-dry desulfurization reaction tower, a dust remover, a low-temperature SCR system, wet desulfurization and the like) and the chimney 6.

The following explains the working principle and the working flow of the high-temperature waste incineration furnace grate system based on material circulation:

the garbage is placed in a grate furnace for incineration, the generated flue gas enters a tail heating surface 7 after passing through a hearth 8 of the grate furnace, enters an air preheater 3 and an economizer 4 after being cooled, then enters a subsequent flue gas purification system 5, and is discharged into a chimney 6 through an induced draft fan after being treated. Primary air firstly enters a primary air steam preheater 2 through a primary air fan 1, the primary air can be heated to about 200 ℃ (190-210 ℃) by utilizing steam generally, and if the temperature continues to rise, the required steam quantity is too large, the steam temperature is too high, and the system operation is influenced. And then, the primary air heated by steam further enters an air preheater 3 arranged behind a tail heating surface 7, the air preheater 3 adopts a compact and high heat exchange coefficient design due to the limitation of the space of a flue at the tail of the grate furnace, the primary air heater is used for heating the primary air by the air preheater 3 at 300-400 ℃, and the smoke temperature is too high, so that the smoke discharge loss is relatively large. The high-temperature primary air after secondary heating is introduced into the fire grate from the lower part of the fire grate to be combusted. Theoretically, the combustion temperature can be increased by 70-80 ℃ every time the primary air is increased by 100 ℃. Therefore, the combustion temperature of the grate furnace hearth 8 can reach 1100-1200 ℃. Meanwhile, after the temperature of primary air is integrally increased, the garbage fuel is easier to dry, the integral combustion strength is improved, the combustion on the upper part of the grate is more uniform, the local low-temperature area is reduced, and the possibility of decomposition of dioxin is further improved. In addition, most of the existing semi-dry desulphurization adopted by the garbage grate furnaces requires the flue gas temperature to be 10-20 ℃ higher than the acid dew point, and corrosion is considered, so the flue gas temperature cannot be too low, the heat exchange area of the economizer 4 is reduced, and the flue gas temperature can be kept about 190 ℃ (180-200 ℃). If other flue gas treatment systems 5 are adopted, the corresponding heating surface design can be changed correspondingly.

Meanwhile, fine sand materials are added into the furnace grate through the sand material feeding port 13 and enter the tail flue 7 along with flue gas to form material circulation to serve as a heat carrying medium, so that the upper temperature and the lower temperature of the hearth are balanced, the integral combustion strength of the boiler is improved, the combustion concentration on the furnace grate is avoided, the regional temperature is greatly increased, and the coking possibility is reduced. The fine sand material enters the tail heating surface 7 along with the flue gas, falls into the slag falling pipe 12 under the action of gravity, enters the separator 11, takes fine particles as heavy materials, and forms a gas-solid suspension with certain density under the action of uniform ascending airflow, and has the property similar to fluid. When entering the separator 11, the particles will be layered under the action of the buoyancy and gravity of the average density of the bed layer, and if the density of the particles is higher than the average density of the bed layer, the particles will sink, otherwise, the particles will float. Therefore, the fine sand with small density and light weight floats on the surface of the bed layer due to the buoyancy, is guided out from the upper layer of the separator 11, falls into the fine sand conveying pipe 10 and returns to the hearth 8. The great heavier slag charge of density sinks in the bed bottom, is derived by sorter 11 lower floor, gets into the scum pipe, and then has formed the material circulation of fine sand material, and the better heat on having transmitted the grate has promoted the whole burning intensity of grate furnace for temperature distribution is more even.

It should be noted that the above description is only one of the embodiments of the present invention, and all equivalent changes made by the system described in the present invention are included in the protection scope of the present invention. The technical field of the present invention can be replaced by other embodiments described in a similar manner, without departing from the structure of the present invention or exceeding the scope defined by the claims, which belong to the protection scope of the present invention.

Claims (7)

1. A high-temperature waste incineration furnace grate system based on material circulation is characterized by comprising a grate furnace, a primary fan (1), a primary air steam preheater (2), an air preheater (3), an economizer (4), a flue gas treatment system (5), a chimney (6), a conveying fluidized fan (9) and a separator (11);

the primary air fan (1) is connected with the primary air steam preheater (2), the primary air steam preheater (2) is connected with the air inlet of the air preheater (3), and the air outlet of the air preheater (3) is connected with the primary air inlet of the grate furnace; a sand material feeding port (13) is formed in a hearth (8) of the grate furnace, and a tail heating surface (7) of the grate furnace is communicated with a separator (11) through a slag falling pipe (12); a light material outlet of the separator (11) and a conveying fluidization fan (9) are connected with a sand material feeding port (13) through a fine sand material conveying pipe (10) for conveying fine sand materials; a heavy material outlet of the separator (11) is connected with a slag discharge pipe; the smoke outlet of the tail heating surface (7) is connected with the smoke inlet of the air preheater (3), and the smoke outlet of the air preheater (3) is sequentially connected with the economizer (4), the smoke treatment system (5) and the chimney (6).

2. The high-temperature waste incineration furnace grate system based on material circulation as claimed in claim 1, wherein the sand material inlet (13) is arranged above the drying section of the grate.

3. The high-temperature waste incineration furnace system based on material circulation as claimed in claim 1, characterized in that the separator (11) is a fluidized separator, and the separator (11) is connected with a conveying fluidized fan (9).

4. The high-temperature waste incineration furnace grate system based on material circulation of claim 1, wherein the fine sand material is quartz sand, river sand or coal ash.

5. The high temperature waste incineration furnace grate system based on material circulation of claim 1, wherein the grain size of the fine sand material is < 10 mm.

6. The high-temperature waste incineration furnace grate system based on material circulation as claimed in claim 1, wherein a fast discharging and detaching device is arranged at the elbow of the fine sand conveying pipe (10).

7. The high-temperature waste incineration furnace grate system based on material circulation as claimed in claim 1, wherein the fine sand conveying pipe (10) is provided with a plurality of air supply branch pipes.

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