CN217875860U - Sludge drying and incinerating system based on bubbling fluidized bed - Google Patents

Abstract

The utility model belongs to the technical field of sludge treatment, a sludge drying and incinerating system based on a bubbling fluidized bed is related to, including bubbling fluidized bed, the spray drying unit, the dust collecting unit, flue gas purification unit and mud tank, the high temperature flue gas outlet of bubbling fluidized bed is communicated with the high temperature flue gas inlet of spray drying unit after the heat transfer of gas-gas heat exchanger, the gas outlet of spray drying unit is communicated with the dust collecting unit in order to collect the dry sludge dust carried in the gas outlet discharge flue gas of spray drying unit, the solid outlet of spray drying unit and the solid outlet of dust collecting unit are respectively communicated with the sludge collector, the outlet of sludge collector is communicated with the feed inlet of sludge mixing device, the discharge gate of sludge mixing device is connected with the sludge feed inlet of bubbling fluidized bed, the gas outlet of dust collecting unit is connected with the flue gas purification unit for flue gas purification; the sludge tank is respectively communicated with a sludge jet orifice of the spray drying unit and a feed inlet of the sludge mixing device.

Description

Sludge drying and incinerating system based on bubbling fluidized bed

Technical Field

The utility model belongs to the technical field of the sludge is dealt with, a sludge drying burns system based on bubbling fluidized bed is related to.

Background

Sludge disposal generally includes concentration, dewatering, stabilization (anaerobic digestion, aerobic digestion, composting), and drying, incineration, and the like. The main purposes of sludge concentration, dehydration and drying are to reduce the moisture of the sludge, and dry matters are not reduced and changed; sludge stabilization mainly decomposes and reduces the content of organic matters in dry matters, and the moisture content is hardly changed; the sludge incineration is to completely eliminate organic matters, combustible substances and moisture, and is the most thorough stabilization and reduction.

At present, sludge incineration mainly adopts a technology of reducing the water content of sludge to a certain degree to enable the sludge to reach a certain calorific value and then carrying out incineration disposal, namely, sludge drying is carried out first and then incineration is carried out. The sludge drying method mainly comprises natural drying, mechanical drying and heat drying, and the natural drying occupies a large area and is greatly influenced by climate and is not adopted generally. The mechanical drying is mainly to remove water among sludge particles by a mechanical method, and mainly comprises centrifugal dehydration, vacuum filtration dehydration, plate-frame filter-pressing dehydration, belt-type filter-pressing dehydration and the like, but the mechanical drying reduces the water content of the sludge to about 60% at most, and simultaneously a large amount of medicament is added, and the heat value of the sludge after the mechanical drying generally does not meet the requirement of incineration disposal. The heat drying is to further remove the moisture in the dewatered sludge by utilizing heat energy, is a heat transfer process between the sludge and a heating medium, and comprises two modes of direct drying and indirect drying. At present, indirect drying technology is widely applied, a thin layer drying machine, a paddle drying machine and other indirect drying equipment are adopted, and sludge attached to the other surface of a metal cavity is evaporated by heating a heating medium in the metal cavity; and the other direct drying mode is to directly dry the sludge mainly by smoke. Compared with the prior art, the indirect drying efficiency is not high, and the parts are easily damaged due to high temperature and high pressure; the direct drying efficiency is high, but the sludge is easy to deteriorate. In addition, sludge incineration may be generally performed in cooperation with incineration or independent incineration, wherein the sludge independent incineration apparatus includes a multi-stage furnace, a rotary kiln, and a fluidized bed.

At present, the sludge drying and incinerating technology which is most widely applied usually adopts a sludge indirect drying technology to be matched with an independent incinerating system, but the existing sludge drying and incinerating system has the following defects: 1) The sludge drying cost is high, and the sludge drying efficiency is low; 2) The high-temperature flue gas heat of the sludge incineration system can not be recycled, the incineration cost is higher, and the energy utilization rate is low.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model aims at providing a sludge drying burns system based on bubbling fluidized bed combines bubbling fluidized bed to have combustion efficiency height, economic nature good, the excess air coefficient is little, fuel consumption is little, easily realize burning advantages such as control to harmful gas, and mud is dealt with to the direct mummification mode of supporting mud. Direct drying mud in the spray drying unit of the high temperature flue gas that tympanic bulla fluidized bed incineration mud produced, then send into tympanic bulla fluidized bed after mixing dry sludge and wet mud and burn, arrange the flue gas purification unit again and purify the back and discharge the flue gas behind the dry sludge, sludge incineration and sludge drying's cooperation has been realized, it is with high costs to have solved sludge drying, the unable recovery of the heat of inefficiency and sludge incineration, the problem that energy utilization is low, and can directly burn partial wet mud, sludge treatment's cost has further been reduced.

In order to achieve the above purpose, the utility model provides a following technical scheme:

a sludge drying and incinerating system based on a bubbling fluidized bed comprises a bubbling fluidized bed for incinerating sludge, a spray drying unit, a dust collecting unit, a flue gas purifying unit and a sludge tank for loading sludge, wherein a flue gas outlet of the bubbling fluidized bed is communicated with a high-temperature flue gas inlet of the spray drying unit after heat exchange through a gas-gas heat exchanger, a gas outlet of the spray drying unit is communicated with the dust collecting unit so as to collect dry sludge dust carried in flue gas discharged by a gas outlet of the spray drying unit, a solid outlet of the spray drying unit and a solid outlet of the dust collecting unit are respectively communicated with a sludge collector, an outlet of the sludge collector is communicated with a feed inlet of a sludge mixing device, a discharge port of the sludge mixing device is connected with a sludge feed inlet of the bubbling fluidized bed, and a gas outlet of the dust collecting unit is connected with the flue gas purifying unit for flue gas purification;

and the sludge tank is respectively communicated with a sludge jet orifice of the spray drying unit and a feed inlet of the sludge mixing device.

Further, a first cyclone separator is arranged between the gas-gas heat exchanger and the spray drying unit and used for removing fly ash in high-temperature flue gas.

Furthermore, the gas-gas heat exchanger comprises a flue gas channel and a fluidizing air channel which are oppositely arranged, the inlet of the flue gas channel is connected with the flue gas outlet of the bubbling fluidized bed, the outlet of the flue gas channel is connected with the high-temperature flue gas inlet of the spray drying unit, the inlet of the fluidizing air channel is connected with the fluidizing fan, and the outlet of the fluidizing air channel is connected with the combustion air inlet of the bubbling fluidized bed.

Further, the dust collection unit comprises a second cyclone separator and a first bag-type dust collector, the gas outlet of the spray drying unit is communicated with the gas inlet of the second cyclone separator, the gas outlet of the second cyclone separator is communicated with the gas inlet of the first bag-type dust collector, the gas outlet of the bag-type dust collector is communicated with the gas inlet of the flue gas purification unit, and solid outlets of the second cyclone separator and the first bag-type dust collector are respectively communicated with the sludge collector.

Further, the flue gas purification unit comprises a flue reactor, a second bag-type dust collector, a spray tower, a flue gas whitening device and a chimney which are sequentially arranged along the flue gas transmission direction, wherein a slaked lime injection port and an activated carbon injection port are arranged on the flue reactor, the slaked lime injection port is communicated with a slaked lime storage tank, and the activated carbon injection port is communicated with the activated carbon storage tank.

Further, the slaked lime storage tank is communicated with the bubbling fluidized bed to provide slaked lime for a sludge combustion process in the bubbling fluidized bed for deacidification.

Furthermore, a pipeline for recovering the slaked lime is arranged from the solid outlet of the second bag-type dust collector to the slaked lime injection port of the flue reactor so as to realize the recycling of the slaked lime.

Further, an ozone injection device is arranged on a flue between the second bag-type dust collector and the spray tower.

Furthermore, the upper area of the inner part of the spray tower is provided with a plurality of layers of alkali liquor nozzles, and the alkali liquor nozzles are connected with an external alkali liquor storage tank.

The beneficial effects of the utility model reside in that:

1. the utility model exchanges heat of the high-temperature flue gas from the bubbling fluidized bed through the gas-gas heat exchanger, thereby not only reducing the temperature of the flue gas, but also ensuring that the oxygen content in the flue gas entering the spray drying unit is lower than 10 percent without supplying a large amount of air to the flue gas, thus ensuring that the spray drying is also safe and reliable under the condition of small sludge granulation diameter, controlling the temperature of the high-temperature flue gas in the range that organic matters in the sludge are not easy to be directly pyrolyzed, and ensuring the heat value of the dried sludge entering the furnace; utilize gas-gas heat exchanger not only to realize the cooling of high temperature flue gas, still realized combustion air's heating, let in the combustion air entry of bubbling fluidized bed with the combustion air of gas-gas heat exchanger heating, provide the oxygen that the mud burning needs when heating mud, greatly improve energy utilization.

2. The utility model provides a mud need not whole mummification, only needs to burn in can sending into the bubbling fluidized bed after the mud mixing arrangement misce bene with wet mud futilely through the wet mud of spray drying unit drying part, very big reduction the energy that is used for sludge drying.

3. The utility model discloses in adopt the combination of flue reactor + second sack cleaner, make flue gas and lime hydrate, active carbon mix more evenly on the one hand, on the other hand passes through the sack and adsorbs, increases the reaction time of lime hydrate, active carbon and flue gas, and the sack cleaner of here not only is regarded as collection device, still regards as reaction unit for the heavy metal and the deacidification effect of removing of flue gas are better. And the invention aims at the high moisture content in the flue gas after the flue gas dries the sludge, and the dry deacidification is adopted under the working condition, so the deacidification effect is better. The invention combines the burning pre-deacidification process by directly spraying slaked lime into the bubbling fluidized bed with the dry deacidification on the flue reactor and the slaked lime recycling process, thereby realizing the complete deacidification effect.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and/or combinations particularly pointed out in the appended claims.

Drawings

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in detail with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic structural view of a bubbling fluidized bed-based sludge drying and incinerating system in example 1;

FIG. 2 is a schematic view of the structure of the bubbling fluidized bed in example 1.

Reference numerals: the device comprises a bubbling fluidized bed 1, a feeding device 1.1, a combustion air inlet 1.2, a starting combustion device 1.3, an auxiliary combustion device 1.4, a fluidized bed body 1.5, a fluidized fan 2, a gas-gas heat exchanger 3, a first cyclone separator 4, an ash bin 5, a mud tank 6, a screw pump 7, a spray drying unit 8, a sludge collector 9, a second cyclone separator 10, a sludge mixing device 11, a first bag-type dust collector 12, a slaked lime storage tank 13, a flue reactor 14, a hazardous waste bin 15, a second bag-type dust collector 16, a liquid oxygen tank 17, an ozone generator 18, a spray tower 19, an induced draft fan 20, a flue gas whitening device 21, a chimney 22, an activated carbon storage tank 23, a first deacidification channel a, a second deacidification channel b and a third deacidification channel c.

Detailed Description

The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in any way limiting the scope of the invention; for a better explanation of the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc., indicating directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore, the terms describing the positional relationships in the drawings are only used for illustrative purposes and are not to be construed as limiting the present invention, and those skilled in the art can understand the specific meanings of the terms according to specific situations.

Please refer to fig. 1-2, which are a sludge drying and incinerating system based on a bubbling fluidized bed, comprising a bubbling fluidized bed 1 for incinerating sludge, a spray drying unit 8, a dust collecting unit, a flue gas purifying unit and a sludge tank 6 for loading sludge, wherein a flue gas outlet of the bubbling fluidized bed 1 is communicated with a high-temperature flue gas inlet of the spray drying unit 8 after heat exchange by a gas-gas heat exchanger 3, a gas outlet of the spray drying unit 8 is communicated with the dust collecting unit to collect the dust in the flue gas discharged from a gas outlet of the spray drying unit 8, a solid outlet of the spray drying unit 8 and a solid outlet of the dust collecting unit are respectively communicated with a sludge collector 9, an outlet of the sludge collector 9 is communicated with a feed inlet of a sludge mixing device 11, a discharge port of the sludge mixing device 11 is connected with a sludge feed inlet of the bubbling fluidized bed 1, a gas outlet of the dust collecting unit is connected with the flue gas purifying unit for purifying flue gas, and the sludge tank 6 is respectively communicated with a sludge jet port of the spray drying unit 8 and a feed inlet of the sludge mixing device 11.

The bubbling fluidized bed 1 comprises a fluidized bed body 1.5, a feeding device 1.1 connected to the fluidized bed body 1.5, a combustion air inlet 1.2, a starting combustion device 1.3 and an auxiliary combustion device 1.4, wherein the fluidized bed body 1.5 is of a cylindrical structure, the lower part of the fluidized bed body is a fluidized bed material zone, the upper part of the fluidized bed body is a hearth, sludge is fed to the fluidized bed material zone through the feeding device 1.1 to be incinerated, and the combustion air inlet 1.2 is positioned at the bottom of the fluidized bed material zone and provides oxygen for sludge combustion; the start-up combustion device 1.3 is located at one end, close to a bed material fluidization area, of the hearth and used for ignition of sludge combustion, the auxiliary combustion device 1.4 is located at one side of the bed material fluidization area and used for supplying heat to sludge when the heat value of the sludge is insufficient and self-sustaining combustion cannot be maintained, a flue gas outlet of the fluidized bed body 1.5 is formed at one end, far away from the bed material fluidization area, of the hearth, and a slaked lime injection port connected with a slaked lime storage tank is further arranged on the hearth.

In this embodiment, a first cyclone separator 4 is further disposed between the gas-gas heat exchanger 3 and the spray drying unit 8, a solid outlet at the bottom of the first cyclone separator 4 is connected to an ash bin 5 to collect fly ash in high-temperature flue gas separated by the first cyclone separator 4, the fly ash is treated as general solid waste, the gas-gas heat exchanger 3 includes a flue gas channel and a fluidizing air channel which are disposed oppositely, an inlet of the flue gas channel is connected to a flue gas outlet of the bubbling fluidized bed 1, an outlet of the flue gas channel is connected to a high-temperature flue gas inlet of the spray drying unit 8, an inlet of the fluidizing air channel is connected to a fluidizing fan 2, an outlet of the fluidizing air channel is connected to a combustion air inlet of the bubbling fluidized bed 1, and the fluidizing fan 2 extracts ambient air and sends the ambient air into the gas-gas heat exchanger 3 to perform indirect heat exchange with the high-temperature flue gas discharged from the bubbling fluidized bed 1, thereby cooling the high-temperature flue gas and heating the combustion air, and having the effect of achieving two purposes at one goal.

In this embodiment, the dust collecting unit includes a second cyclone 10 and a first bag-type dust collector 12, the gas outlet of the spray drying unit 8 is communicated with the gas inlet of the second cyclone 10, the gas outlet of the second cyclone 10 is communicated with the gas inlet of the first bag-type dust collector 12, the gas outlet of the bag-type dust collector 12 is communicated with the gas inlet of the flue gas purification unit, and the solid outlets of the second cyclone 10 and the first bag-type dust collector 12 are respectively communicated with the sludge collector 9

In this embodiment, the flue gas purification unit includes a flue reactor 14, a second bag-type dust collector 16, a spray tower 19, a flue gas whitening device 21 and a chimney 22, which are sequentially arranged along a flue gas transmission direction, wherein the flue reactor 14 is provided with a slaked lime injection port and an activated carbon injection port, the slaked lime injection port is communicated with a slaked lime storage tank 13, and the activated carbon injection port is communicated with an activated carbon storage tank 23; the slaked lime storage tank 13 is also communicated with the bubbling fluidized bed 1 to provide slaked lime for sludge combustion in the bubbling fluidized bed 1; a pipeline for recovering slaked lime is arranged from a solid outlet of the second bag-type dust collector 16 to a slaked lime injection port of the flue reactor 14 to realize cyclic utilization of slaked lime, a solid outlet of the second bag-type dust collector 16 is connected with a hazardous waste bin 15 to recover slaked lime and activated carbon after reaction to be used as hazardous waste treatment, an ozone injection device is arranged on a flue between the second bag-type dust collector 16 and the spray tower 19, a multi-layer alkali liquor nozzle is arranged in the upper inner area of the spray tower 19 and connected with an external alkali liquor storage tank, and a sewage outlet connected with an external sewage treatment pipe network is arranged at the bottom of the spray tower 19.

Specifically, taking wet sludge with water content of 80% and 300t/d as an example for treatment, the dry basis heat value of the sludge is 10000kJ/kg, and the method specifically comprises the following steps:

sludge pretreatment: dividing wet sludge in a sludge tank 6 into two paths, and arranging a screw pump 7 for conveying the wet sludge at an outlet of the sludge tank 6, wherein one path of 178t/d wet sludge (with the water content of 80%) is conveyed to a spray drying unit 8 for drying, and obtaining dried 44t/d dry sludge (with the water content of 20%); directly feeding the other path of 122t/d wet sludge (with the water content of 80%) into a sludge mixing device 11, uniformly mixing the wet sludge with 44t/d dry sludge in a sludge collector 9 to form 166t/d sludge with the water content of 64%, and feeding the 166t/d sludge into a bubbling fluidized bed 1 for incineration treatment;

sludge incineration: adopting a bubbling fluidized bed 1 to incinerate 166t/d (the water content is 64 percent and the lower heat value is 2000 kJ/kg) sludge, and introducing combustion air (10000 Nm) ³ H,500 ℃) keeps the bed layer fluidized and provides oxygen required by sludge combustion, controls the oxygen content of the flue gas at the outlet of the incinerator to be 8 percent, sprays natural gas into the incinerator through an auxiliary combustion device 1.4 to maintain the combustion temperature at 885 ℃ so as to ensure the sludge to be burnt out, and generates 20000Nm high-temperature flue gas ³ /h；

Recovering waste heat of the gas-gas heat exchanger: the high-temperature flue gas generated by the bubbling fluidized bed 1 exchanges heat with fluidized air through the gas-gas heat exchanger 3, the fluidized air is heated to 500 ℃ from normal temperature, the high-temperature flue gas is reduced to below 650 ℃ from 885 ℃, the high-temperature flue gas cooled by the gas-gas heat exchanger 3 is dedusted by the first cyclone separator 4, the dedusting efficiency is more than or equal to 80%, the fly ash collected by the first cyclone separator 4 is sent into the ash bin 5 to be treated as general solid waste, and the high-temperature flue gas is sent into the drying unit 8;

sludge drying: introducing high-temperature flue gas and spraying sludge, wherein the high-temperature flue gas and the sludge are directly contacted in a drying unit 8, the sludge is dried, 85% of dried sludge particles are collected from the bottom of the drying unit 8 and enter a sludge collector 9, the particle temperature is 70-90 ℃, about 15% of the dried sludge particles are taken away by the flue gas, the flue gas temperature is about 140 ℃, the flue gas is sent to a dust collecting unit for dust removal, the dust collecting unit sends the dust collected in the flue gas to the sludge collector 9, the moisture content of wet sludge is reduced from 80% to 20% by matching of the drying unit 8 and the dust collecting unit, the dry sludge is collected, and the flue gas discharged by the dust collecting unit enters a flue gas purifying unit; specifically, the drying unit 8 can be a spray drying tower, a drying tank or a drying box and other devices suitable for spray drying, a sludge granulating device capable of granulating sludge is arranged in the drying unit 8, a certain number of granulators are adopted according to the treatment capacity, auxiliary compressed air is adopted, wet sludge can be granulated into particles with the diameter of 100-1000 um, the spraying direction of the sludge and the flow direction of high-temperature flue gas form a certain angle, and when the high-temperature flue gas is sprayed, the wet sludge can be dried instantly;

flue gas purification: the flue gas purification unit is used for deacidifying, deodorizing, denitrating and whitening the flue gas and then discharging.

Specifically, in this embodiment, the deacidification is realized by combining the incineration pre-desulfurization process in the bubbling fluidized bed 1 with dry desulfurization in the flue reactor 14, which is a flue pipeline with a U-shaped end, and the spray tower 19. Because of the dry desulfurization, the reaction time and the temperature requirement, the slaked lime is only sprayed in the bubbling fluidized bed 1, the deacidification efficiency is not high, therefore, the invention adopts three deacidification channels to spray the slaked lime (Ca (OH) ₂ ) To improve the deacidification efficiency.

The first deacidification channel a is formed by a slaked lime storage tank 13 and an active carbon storage tank 23 which are respectively connected with a slaked lime injection port and an active carbon on a flue reactor 14The injection ports are communicated through a pipeline, the slaked lime injection port and the activated carbon injection port are positioned at the initial section of the flue reactor 4, and slaked lime and activated carbon, ca (OH) are sprayed into the flue reactor 14 ₂ The dry powder is sprayed into the flue reactor 14, the flue gas temperature is about 140 ℃ and the humidity is 35-45%, the dry powder and the flue gas are fully mixed in the flue reactor 14, and Ca (OH) is generated due to high flue gas humidity ₂ The dry powder reacts with the acid gas in the flue gas more quickly to produce stable substances, and the activated carbon and the slaked lime with micro-fine particle size enter the second bag-type dust collector 16 along with the flue gas, are attached to the bag and react with the SO in the flue gas ₂ Chemical reaction to further complete deacidification;

the second deacidification channel b is used for leading the slaked lime from the slaked lime storage tank 13 to be sprayed into a hearth of the fluidized bed body 1.5, ca (OH) ₂ The dry powder is sprayed into the fluidized bed body 1.5 to react with acid gas generated by incinerating sludge to produce stable substances. Ca (OH) ₂ The dry powder is subjected to furnace incineration pre-denitration, and compared with a mode without furnace pre-denitration, the method reduces 50% of acid gas in the flue gas to the maximum extent;

the third deacidification channel c introduces a recovery pipeline from the solid outlet of the second cloth bag dust remover 16 to the position of the lime spraying opening and the active carbon spraying opening on the flue reactor 14, and Ca (OH) in the second cloth bag dust remover 16 is added ₂ Recycling the waste water to increase the utilization rate of the active carbon and the slaked lime, and collecting the unreacted Ca (OH) by the second bag-type dust collector 16 ₂ And part of the flue gas is sprayed into the flue reactor 14 again to react with the flue gas in a circulating way.

The deacidification efficiency of the flue reactor 14 matched with the second cloth bag reactor 16 can reach 50%, and the deacidification effect can be completely achieved by combining with the in-furnace incineration pre-deacidification.

Ca(OH) ₂ The principle of the dry powder reacting with acidic substances in the smoke to generate stable substances is as follows:

treatment of SO ₂ The principle of (1): SO ₂ +Ca(OH) ₂ ＝CaSO ₃ +H ₂ O

2CaSO ₃ +O ₂ ＝2CaSO ₄

Principle of handling HCl: ca (OH) ₂ +2HCl＝CaCl ₂ +2H ₂ O

Principle of HF treatment: 2HF ca (OH) ₂ ＝CaF ₂ +2H ₂ O

An ozone spraying device for denitration and deodorization is arranged between the second bag-type dust collector 16 and the spray tower 19, the ozone spraying device comprises an ozone generator 18 and a liquid oxygen tank 17 for providing liquid oxygen for the ozone generator 18, and the ozone generator 18 provides ozone for a flue between the second bag-type dust collector 16 and the spray tower 19. The strong oxidant (ozone) generated by the ozone generation system is adopted to forcedly oxidize NO in the flue gas _x The reaction produces high-valence nitrogen oxides (N) which are easily dissolved in water ₂ O ₅ ). In addition, the ozone has strong oxidation effect on the peculiar smell of VOCs (volatile organic compounds) such as ammonia, hydrogen sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide and the like, thereby achieving the effect of deodorization.

Ozone treatment of NO _x The principle of (1) is as follows:

O ₃ denitration: NO + O ₃ ＝NO ₂ +O ₂

NO+O ₃ ＝NO2+O ₂

NO ₂ +O ₃ ＝NO ₃ +O ₂

NO ₂ +NO ₂ ＝N2O ₄

NO ₃ +NO ₂ ＝N ₂ O ₅

3NO ₂ +H ₂ O＝2HNO ₃ +NO

N ₂ O ₅ +H ₂ O→2HNO ₃

The mechanism of the deodorization is: mainly uses the oxidation principle of ozone as a strong oxidant to carry out chemical reaction with chemical substances emitting peculiar smell. For example: when the malodorous gas is NH ₃ When in use, ammonia reacts with water to generate ammonia water, then the ammonia water is converted into nitric acid through the nitrification of nitrite bacteria and nitrate bacteria under the aerobic condition, and nitrate is reduced into nitrogen by nitrate reducing bacteria under the facultative anaerobic condition.

The spray tower 19 employs an alkali of 30%And (4) liquid. The spray tower 19 serves three main purposes. Firstly, the high-valence nitrogen oxides (N) generated in the denitration stage are removed ₂ O ₅ ) (ii) a Secondly, removing a small amount of sulfur dioxide (SO) remained in the deacidification stage ₂ ) Hydrogen sulfide (H) ₂ S), hydrogen chloride (HCl); and thirdly, washing the residual VOCs dissolved in water in the deodorization stage.

Further removal of N ₂ O ₅ The principle of (1):

first reacting with water: n is a radical of ₂ O ₅ +H ₂ O→2HNO ₃

And (3) neutralization reaction with alkali liquor: naOH + HNO ₃ ＝NaNO ₃ +H ₂ O

The concentration of nitrogen oxide (NOx) at the outlet of the spray tower 19 should reach 100mg/m ³ (equivalent to 11% oxygen content dry smoke, 24h mean value) below. The smoke whitening device 21 is used for reducing the humidity of smoke, achieving the aim of whitening the smoke, eliminating visual pollution and condensing water vapor in part of the smoke into water, and is a common device in the final treatment stage of the smoke in the prior art; further, an induced draft fan 21 for providing power is further arranged between the spray tower 19 and the flue gas de-whitening device 21, the flue gas is purified by the flue gas purification unit and then discharged from a chimney 22, and the emission substances and emission values thereof are as follows: dust<10mg/Nm ³ 、HCl<10mg/Nm ³ 、HF<0.7mg/Nm ³ 、SO ₂ <50mg/Nm ³ 、NOx(as NO ₂ )<200mg/Nm ³ 、CO<100mg/Nm ³ 、Pb+Sn<0.5mg/Nm ³ 、PCDD/PCDF<0.1ng/Nm ³ 。

The working principle of the invention is as follows:

after entering a sludge mixing device 11 from a sludge collector 9 and being uniformly mixed with wet sludge from a sludge tank 6, dry sludge is sent into a bubbling fluidized bed 1 for burning and burning, combustion air is introduced into a fluidized bed body 1.5 to keep the bed layer fluidized and provide oxygen required by sludge burning, natural gas is sprayed into the incinerator through an auxiliary combustion device 1.4 to maintain the burning temperature at 870-900 ℃ so as to ensure that the sludge is burnt out, high-temperature flue gas is generated, and the discharged ash after burning enters an ash collecting bin (not shown in the figure) to be collected and then is uniformly recycled.

The high-temperature flue gas generated by the bubbling fluidized bed 1 exchanges heat with fluidized air through the gas-gas heat exchanger 3, the fluidized air is heated to 350-600 ℃ from normal temperature, the high-temperature flue gas is reduced to be below 650 ℃, the high-temperature flue gas cooled by the gas-gas heat exchanger is dedusted by the first cyclone separator 4, the dedusting efficiency is not less than 80%, the fly ash collected by the first cyclone separator 4 is sent into the ash bin 5 to be treated as common solid waste, and the high-temperature flue gas is sent into the drying unit 8.

Wet sludge with the water content of 80 percent is discharged from a sludge tank 6 and then is pressed into a granulator through a sludge pumping system (a screw pump 7), and a certain amount of compressed air is added for mixing and spraying to form sludge particles with the diameter of about 100-1000 mu m. The sludge particles (the spraying temperature is normal temperature) are sprayed into the drying unit 8, and simultaneously, high-temperature flue gas flow (about 550-650 ℃) is introduced to fully contact and mix with the sludge particles for direct drying. The whole drying process lasts for about ten seconds, and the sludge particles finally become dry sludge particles with the water content of about 20-30%. 85% of particles (about 70-90 ℃) in the dry sludge are directly discharged from the bottom of the drying unit 8 and enter the sludge collector 9, 15% of particles enter the dust collection unit along with the dried flue gas (about 140 ℃) for dust removal, and the dust collection unit sends the dust collected in the flue gas to the sludge collector 9. Reduce the moisture content of wet mud through drying unit 8 cooperation dust collection unit to collect dry mud, the flue gas that the dust collection unit discharged gets into the gas cleaning unit.

The flue gas passes through the following steps in the flue gas purification unit in sequence: the flue reactor 14 is matched with a second bag-type dust collector 16 for deacidification treatment, then ozone is introduced into a flue between the second bag-type dust collector 16 and a spray tower 19 for denitration and deodorization treatment, then the flue enters the spray tower 19 for alkali liquor washing, then the flue enters a flue gas white removal device 21 for flue gas white removal treatment under the action of a draught fan 20, and then the flue gas white removal device is discharged through a chimney 22.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims (9)

1. The utility model provides a sludge drying system of burning based on bubbling fluidized bed which characterized in that: the device comprises a bubbling fluidized bed (1) for incinerating sludge, a spray drying unit (8), a dust collecting unit, a flue gas purifying unit and a sludge tank (6) for loading sludge, wherein a flue gas outlet of the bubbling fluidized bed (1) is communicated with a high-temperature flue gas inlet of the spray drying unit (8) after heat exchange through a gas-gas heat exchanger (3), a gas outlet of the spray drying unit (8) is communicated with the dust collecting unit so as to collect dry sludge dust carried in flue gas discharged from a gas outlet of the spray drying unit (8), a solid outlet of the spray drying unit (8) and a solid outlet of the dust collecting unit are respectively communicated with a sludge collector (9), an outlet of the sludge collector (9) is communicated with a feed inlet of a sludge mixing device (11), a discharge outlet of the sludge mixing device (11) is connected with a sludge feed inlet of the bubbling fluidized bed (1), and a gas outlet of the dust collecting unit is connected with the flue gas purifying unit for flue gas purification;

the sludge tank (6) is respectively communicated with a sludge jet orifice of the spray drying unit (8) and a feed inlet of the sludge mixing device (11).

2. The bubbling fluidized bed based sludge drying and incinerating system according to claim 1, wherein: and a first cyclone separator (4) is also arranged between the gas-gas heat exchanger (3) and the spray drying unit (8).

3. The bubbling fluidized bed based sludge drying and incinerating system according to claim 1, wherein: the gas-gas heat exchanger (3) is provided with a flue gas channel and a fluidized air channel which are oppositely arranged, an inlet of the flue gas channel is connected with a flue gas outlet of the bubbling fluidized bed (1), an outlet of the flue gas channel is connected with a high-temperature flue gas inlet of the spray drying unit (8), an inlet of the fluidized air channel is connected with the fluidized fan (2), and an outlet of the fluidized air channel is connected with a combustion air inlet of the bubbling fluidized bed (1).

4. The bubbling fluidized bed based sludge drying and incinerating system according to claim 1, wherein: the dust collection unit comprises a second cyclone separator (10) and a first bag-type dust collector (12), the gas outlet of the spray drying unit (8) is communicated with the gas inlet of the second cyclone separator (10), the gas outlet of the second cyclone separator (10) is communicated with the gas inlet of the first bag-type dust collector (12), the gas outlet of the bag-type dust collector (12) is communicated with the gas inlet of the flue gas purification unit, and the solid outlets of the second cyclone separator (10) and the first bag-type dust collector (12) are respectively communicated with the sludge collector (9).

5. The bubbling fluidized bed based sludge drying and incinerating system according to claim 1, wherein: the flue gas purification unit comprises a flue reactor (14), a second bag-type dust collector (16), a spray tower (19), a flue gas whitening device (21) and a chimney (22) which are sequentially arranged along the flue gas transmission direction, wherein a slaked lime jet orifice and an activated carbon jet orifice are arranged on the flue reactor (14), the slaked lime jet orifice is communicated with a slaked lime storage tank (13), and the activated carbon jet orifice is communicated with an activated carbon storage tank (23).

6. The bubbling fluidized bed based sludge drying and incinerating system according to claim 5, wherein: the slaked lime storage tank (13) is also communicated with the bubbling fluidized bed (1) to provide slaked lime for deacidification in a sludge combustion process in the bubbling fluidized bed (1).

7. The bubbling fluidized bed based sludge drying and incinerating system according to claim 5, wherein: a pipeline for recovering slaked lime is arranged from the solid outlet of the second bag-type dust collector (16) to the slaked lime injection port of the flue reactor (14) to realize the recycling of the slaked lime.

8. The bubbling fluidized bed based sludge drying and incinerating system according to claim 5, wherein: an ozone spraying device is arranged on a flue between the second bag-type dust collector (16) and the spray tower (19).

9. The bubbling fluidized bed based sludge drying and incinerating system according to claim 5, wherein: the inner upper area of the spray tower (19) is provided with a plurality of layers of alkali liquor nozzles, and the alkali liquor nozzles are connected with an external alkali liquor storage tank.

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