A waste incineration flue gas treatment system

Abstract

The invention discloses a waste incineration flue gas treatment system, wherein a slag pipe is provided at the bottom of the incinerator, and the residue is discharged from the incinerator through the slag pipe, and a vertical flue is provided at the top of the incinerator, the vertical flue is connected to the expansion flue, one end of the horizontal flue is connected to the upper side of the expansion flue, and the other end is connected to the reaction tower; the inner diameter of the expansion flue is larger than the inner diameter of the vertical flue, and a first ejector and a second ejector are provided above the side of the vertical flue; the first ejector sprays calcium-based deacidifying agent particles, which are in a fluidized state between the vertical flue and the expansion flue, and contact and react with the flue gas generated in the incinerator; the second ejector sprays the concentrated liquid generated by the biochemical treatment of the landfill leachate, absorbs heat, reduces the flue gas temperature, and realizes the sedimentation of the calcium-based deacidifying agent particles and fly ash particles into the slag pipe. The present invention has the characteristics of high stability and significant flue gas purification effect, realizes dechlorination in the furnace, slows down the high-temperature chlorine corrosion of the heating surface, and prolongs the service life of the equipment.

Description

Technical Field

[0001] The invention relates to the technical field of garbage incineration, and in particular to a garbage incineration flue gas treatment system. Background Art

[0002] Incineration disposal is the current mainstream way to harmlessly reduce and recycle urban solid waste. The high-temperature flue gas generated by garbage incineration exchanges heat with the working medium (water) through the waste heat boiler to generate steam, which enters the steam turbine to generate power. Most of the industry uses mechanical grate furnace incinerators and horizontal waste heat boilers, equipped with flue gas treatment systems including semi-dry deacidification reaction towers, etc., which have wide applicability, technical parameters, fuels, and combustion methods are not restricted, but there are problems such as complex structure and large footprint.

[0003] Due to the composition characteristics of municipal solid waste, the flue gas generated by incineration disposal contains a large amount of HCl gas, which can easily cause high-temperature corrosion of the heating surface of the waste heat boiler. At high temperatures, the alkali metals in the fly ash will undergo complex chemical reactions to form low-melting-point aluminosilicates or eutectic mixtures. The softened or even molten ash particles move with the flue gas and will adhere to the heating surface to form a coking layer when they collide with it. Over a long period of time, the coking layer gradually grows on the heating surface, the heat exchange efficiency decreases, the flue gas temperature further increases, and the coking phenomenon intensifies. Summary of the invention

[0004] The technical problem to be solved by the present invention is: In view of the above-mentioned problems in the prior art, a waste incineration flue gas treatment system with compact structure, high stability and significant flue gas purification effect is provided.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A waste incineration flue gas treatment system, comprising: an incinerator, a vertical flue, an expansion flue, a reaction tower and a horizontal flue; a slag dropping pipe is provided at the bottom of the incinerator, and the residue after the waste incineration is discharged from the incinerator through the slag dropping pipe; a vertical flue is provided at the top of the incinerator, and the vertical flue is connected to the expansion flue, one end of the horizontal flue is connected to the upper side of the expansion flue, and the other end of the horizontal flue is connected to the reaction tower, and the flue gas generated in the incinerator flows through the vertical flue, the expansion flue and the horizontal flue in sequence and then enters the reaction tower; the expansion flue The inner diameter of the vertical flue is larger than that of the vertical flue, and a first injector and a second injector are provided above the side of the vertical flue; the first injector is used to spray calcium-based deacidifying agent particles, and the calcium-based deacidifying agent particles are in a fluidized state between the vertical flue and the expansion flue, and contact and react with the flue gas generated in the incinerator to achieve flue gas deacidification; the second injector is used to spray the concentrated liquid produced by the biochemical treatment of the landfill leachate, and the concentrated liquid absorbs heat, reduces the flue gas temperature, and enables the calcium-based deacidifying agent particles and the fly ash particles in the flue gas to settle into the slag drop pipe.

[0007] As a further improvement of the present invention, the second injector is located below the first injector, the flue gas temperature at the first injector is lower than 750°C, the flue gas temperature at the second injector is lower than 850°C, and the angle β between the injection angle of the second injector and the horizontal direction is 60°±5°.

[0008] As a further improvement of the present invention, the cross-sectional area of ​​the vertical flue is S, and the cross-sectional area of ​​the expansion flue is S'=k×S, k>1.

[0009] As a further improvement of the present invention, the distance between the first ejector and the inlet of the expansion flue is h , m;

[0010] Formula (1),

[0011] In the formula, C d is the drag coefficient, which is taken as 0.5; g is the acceleration due to gravity, take 9.8m / s 2 , Φ is the particle size of calcium-based deacidifying agent particles, m; r Ca is the density of calcium-based deacidifier particles, kg / m 3 ; S is the cross-sectional area of ​​the vertical flue, m 2 ; L is the length of the expansion duct, m; Q is the flue gas flow rate, m 3 / s; r is the smoke density, kg / m 3 ; k It is the ratio of the cross-sectional area of ​​the expansion flue to the cross-sectional area of ​​the vertical flue.

[0012] As a further improvement of the present invention, the distance between the second injector and the first injector in the vertical direction is x , m;

[0013] Formula (2),

[0014] In the formula, v 0 is the initial velocity of the concentrated liquid injected by the second injector, m / s; v t is the vertical velocity at time t, m / s; a is the acceleration in the vertical direction, m / s 2 ; r is the smoke density, take 0.3kg / m 3 ; C dis the drag coefficient, which is taken as 0.5; g is the acceleration due to gravity, take 9.8m / s 2 ; is the droplet size of the sprayed concentrated liquid, m; β is the angle between the second ejector and the horizontal direction, °; t is the evaporation time of the concentrate, s.

[0015] As a further improvement of the present invention, the evaporation time of the concentrated solution is t Calculated by formula (3),

[0016] Formula (3),

[0017] In the formula, ρ 液 is the density of the concentrate, take 1000kg / m³; Cp is the specific heat capacity of the concentrated solution, which is taken as 4200 J / (kg·K); is the droplet size of the concentrated liquid sprayed by atomization, m; l is the thermal conductivity of flue gas, W / (m·K); l s is the thermal conductivity of the concentrated liquid, W / (m·K); V is the latent heat of vaporization of the concentrated liquid, J / kg; T is the flue gas temperature at the second injector, K; T s is the concentrate temperature, K.

[0018] As a further improvement of the present invention, the first injector is externally connected to an injection pipeline, and calcium-based deacidifying agent particles are sprayed in by a Roots blower, and the calcium-based deacidifying agent is quicklime or slaked lime.

[0019] As a further improvement of the present invention, the calcium-based deacidifier particles are stored in a calcium-based deacidifier bin, and a disc feeder distribution motor and a loss-in-weight scale feeder are installed at the outlet of the calcium-based deacidifier bin to achieve real-time recording and dynamic adjustment of the dosage of the calcium-based deacidifier particles.

[0020] As a further improvement of the present invention, HCl concentration measuring points are provided at the installation location of the second injector and at the outlet of the expansion flue to calculate the utilization rate of the added calcium-based deacidifying agent particles. α ,

[0021] Formula (4),

[0022] In the formula, Q is the flue gas flow rate, m 3 / s; c 1 、c2 are the actual HCl concentrations in the flue gas at the installation location of the second injector and at the outlet of the expansion flue, kg / m 3 ; m is the dosage of calcium-based deacidifying agent per unit time, kg / s; oh is the effective content of the calcium-based deacidifier, 36.5 is the molecular weight of HCl, and n is 1 / 2 of the molecular weight of the calcium-based deacidifier.

[0023] As a further improvement of the present invention, the amount of calcium-based deacidifying agent particles measured by the weight loss scale feeder, the HCl concentration data at the installation location of the second injector and the outlet of the expansion flue are uploaded to the DCS control system to calculate the utilization rate of the calcium-based deacidifying agent. α .

[0024] As a further improvement of the present invention, according to the flue gas flow Q , Real-time calculation of calcium-based deacidification agent utilization α , the actual HCl concentration in the flue gas at the installation location of the second injector c 1 and the preset HCl concentration in the flue gas at the outlet of the expansion flue c 3. Calculate the amount of calcium-based deacidifying agent M currently required for the waste incineration flue gas treatment system, which is used as the feedforward control signal of the PID regulator of the loss-in-weight scale feeder to achieve accurate on-demand addition of calcium-based deacidifying agent and avoid waste caused by excessive addition.

[0025] Formula (5),

[0026] In the formula, Q is the flue gas flow rate, m 3 / s; c 1 is the actual HCl concentration in the flue gas at the installation location of the second injector, kg / m 3 ; c 3 is the preset HCl concentration in the flue gas at the outlet of the expansion flue, kg / m 3 ; α The utilization rate of calcium-based deacidifier, oh It is the effective content of calcium-based deacidifier.

[0027] As a further improvement of the present invention, a plurality of convection heat exchangers are arranged in the horizontal flue to realize heat exchange and cooling of the flue gas; the flue gas temperature at the outlet of the expansion flue is 640°C±40°C.

[0028] As a further improvement of the present invention, a pressure detection component is provided at the outlet of the expansion flue, and the second injector sprays the concentrated liquid intermittently according to the airflow pressure at the outlet of the expansion flue.

[0029] As a further improvement of the present invention, the reaction tower adopts a semi-dry deacidification reaction tower.

[0030] As a further improvement of the present invention, a plurality of ash hoppers are provided at the bottom of the horizontal flue.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] The waste incineration flue gas treatment system of the present invention is provided with a vertical flue on the top of the incinerator, and the vertical flue is connected with the expansion flue, one end of the horizontal flue is connected with the upper side of the expansion flue, and the other end of the horizontal flue is connected with the reaction tower. The flue gas generated in the incinerator flows through the vertical flue, the expansion flue and the horizontal flue in sequence and then enters the reaction tower, thereby realizing the deacidification and purification treatment of the waste incineration flue gas. Furthermore, the inner diameter of the expansion flue is larger than that of the vertical flue, and a first injector and a second injector are arranged above the side of the vertical flue; the first injector is used to spray calcium-based deacidifier particles, and the calcium-based deacidifier particles move in the vertical flue and the expansion flue under the action of gravity and the thrust of the flowing flue gas. Since the flue gas flow rates in the vertical flue and the expansion flue are different, the upward thrust exerted on the calcium-based deacidifier particles is also different. Therefore, the acceleration directions of the calcium-based deacidifier particles under the thrust of the flowing flue gas and gravity are different, so that the calcium-based deacidifier particles are in a fluidized state in the two sections of the flue. The calcium-based deacidifier particles in the fluidized state stay in the flue for a long time, can absorb and reduce the concentration of HCl gas in the flue gas, slow down the high-temperature chlorine corrosion of the rear end heating surface, extend the service life of the equipment, and reduce the inspection pressure and maintenance cost. The concentrated liquid produced by biochemical treatment of landfill leachate is sprayed into the furnace by atomization using the second injector. The concentrated liquid is then sprayed back into the furnace to evaporate and absorb heat, thereby lowering the smoke temperature. The calcium-based deacidifier and fly ash particles are adsorbed and captured, so that the calcium-based deacidifier and fly ash particles are quickly combined and solidified into particles with larger particle size, which are separated from the fluidized state and fall downward to the grate and discharged into the slag pipe into the slag pit for removal from the system, further reducing the risk of ash coking on the heated surface and improving the stability of system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structural principle of a waste incineration flue gas treatment system in a specific embodiment of the present invention;

[0034] Legend: 1. Incinerator; 2. Vertical flue; 3. Expansion flue; 4. Horizontal flue; 5. Reaction tower; 6. First ejector; 7. Second ejector; 8. Slag drop pipe; 9. Convection heat exchanger; 10. Ash hopper. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0036] In the description of the present invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0038] Example

[0039] like Figure 1 As shown, the waste incineration flue gas treatment system of the present invention comprises: an incinerator 1, a vertical flue 2, an expansion flue 3, a reaction tower 5, a horizontal flue 4 and a reaction tower 5. A slag pipe 8 is provided at the bottom of the grate of the incinerator 1, and the residue after the waste incineration is discharged from the incinerator 1 through the slag pipe 8. A vertical flue 2 is provided at the top of the incinerator 1, and the vertical flue 2 is connected to the expansion flue 3. One end of the horizontal flue 4 is connected to the upper side of the expansion flue 3, and the other end of the horizontal flue 4 is connected to the reaction tower 5. The flue gas generated in the incinerator 1 flows through the vertical flue 2, the expansion flue 3 and the horizontal flue 4 in sequence and then enters the reaction tower 5. The inner diameter of the expansion flue 3 is larger than the inner diameter of the vertical flue 2. A first injector 6 and a second injector 7 are provided above the side of the vertical flue 2, and the first injector 6 is located above the second injector 7. The first injector 6 is used to spray calcium-based deacidification agent particles, which are in a fluidized state between the vertical flue 2 and the expansion flue 3, and react with the flue gas generated in the incinerator 1 to achieve flue gas deacidification. The second injector 7 is used to spray the concentrated liquid produced by the biochemical treatment of the landfill leachate. The concentrated liquid absorbs heat and reduces the flue gas temperature, achieving the incineration consumption of the concentrated liquid, and achieving the combination and solidification of the calcium-based deacidification agent particles with the fly ash particles in the flue gas, and then settles to the grate and is pushed into the slag drop pipe 8.

[0040] In this embodiment, a vertical flue 2 is provided on the top of the incinerator 1, and the vertical flue 2 is connected to the expansion flue 3, one end of the horizontal flue 4 is connected to the upper side of the expansion flue 3, and the other end of the horizontal flue 4 is connected to the reaction tower 5. The flue gas generated in the incinerator 1 flows through the vertical flue 2, the expansion flue 3 and the horizontal flue 4 in sequence and then enters the reaction tower 5, thereby realizing the deacidification and purification treatment of the waste incineration flue gas. Furthermore, the inner diameter of the expansion flue 3 is larger than that of the vertical flue 2, and a first injector 6 and a second injector 7 are arranged above the side of the vertical flue 2; the calcium-based deacidifier particles are sprayed by the first injector 6, and the calcium-based deacidifier particles move in the vertical flue 2 and the expansion flue 3 under the action of gravity and the thrust of the flowing flue gas. Since the inner diameters of the vertical flue 2 and the expansion flue 3 are different, the flue gas flow rates in the two flues are also different, and the upward thrusts on the calcium-based deacidifier particles are also different. Therefore, the acceleration directions of the calcium-based deacidifier particles under the thrust of the flowing flue gas and gravity are different, so that the calcium-based deacidifier particles are in a fluidized state in the two sections of the flue. The calcium-based deacidifier particles in the fluidized state stay in the flue for a long time, can absorb and reduce the concentration of HCl gas in the flue gas, slow down the high-temperature chlorine corrosion of the rear end heating surface, extend the service life of the equipment, and reduce the inspection pressure and maintenance cost. The concentrated liquid produced by biochemical treatment of landfill leachate is sprayed by the second injector 7, and the concentrated liquid is sprayed back into the furnace to evaporate and absorb heat, thereby reducing the smoke temperature, and then the calcium-based deacidifying agent and fly ash particles are quickly combined and solidified into particles with larger particle size, which are separated from the fluidized state and fall downward to the grate, discharged into the slag pipe and into the slag pit, and removed from the system, further reducing the risk of ash and coking on the heated surface and improving the stability of system operation.

[0041] In this embodiment, the reaction tower 5 adopts a semi-dry deacidification reaction tower. A plurality of horizontally arranged convection heat exchangers 9 are provided in the horizontal flue 4 to realize heat exchange and cooling of the flue gas. Specifically, the convection heat exchanger 9 can be in the form of a combination of a high-temperature evaporator, a low-temperature evaporator, a high-temperature superheater, a medium-temperature superheater, a low-temperature superheater and a multi-stage economizer, which can not only realize the cooling of the flue gas, but also realize the multi-stage utilization of the flue gas thermal energy. Among them, the high-temperature evaporator is close to the outlet of the expansion flue 3, and the flue gas temperature at the outlet of the expansion flue 3 is about 640°C. A plurality of ash hoppers 10 are provided at the bottom of the horizontal flue 4 to collect the fly ash particles deposited in the horizontal flue 4.

[0042] In this embodiment, while retaining multiple horizontally arranged convection heat exchangers 9, a vertical flue 2 and an expansion flue 3 arranged vertically up and down are set at the front end of the system, and the semi-dry deacidification reaction tower included in the flue gas treatment system is set below the ash hopper of the waste heat boiler. This design not only retains the technical parameters, fuel, and combustion methods of the horizontal boiler without restrictions, and has the advantages of wide applicability, but also shortens the length of the overall layout, can save steel frame structure consumables, and reduce construction costs.

[0043] In this embodiment, the flue gas temperature at the first injector 6 is lower than 750°C. It is ensured that the calcium-based deacidifier particles will not be broken, agglomerated, crystallized, or fused due to high temperature after being injected, which will greatly reduce the dechlorination efficiency, and prevent the calcium-based deacidifier particles from quickly combining into larger particles and falling down to the grate of the incinerator, thereby extending the time for the calcium-based deacidifier particles to undergo fluidization reaction in the flue. At the same time, when the softened and molten fly ash particles carried in the high-temperature flue gas flow to the calcium-based deacidifier injection port with the flue gas, they will collide with the fluidized calcium-based deacidifier particles in this section of the flue, and be intercepted and difficult to migrate to the rear horizontal convection heat exchange surface, thereby reducing the risk of ash accumulation and coking at the rear end and improving the equipment operation stability.

[0044] Furthermore, the flue gas temperature at the second injector 7 is lower than 850°C, and the angle β between the injection angle of the second injector 7 and the horizontal direction is about 60°, so that the injected concentrated liquid can be quickly diffused and mixed evenly in the flue gas, and the residence time of the flue gas at a position above 850°C can be avoided to be shortened, so as to avoid affecting the decomposition of dioxins.

[0045] In this embodiment, the cross-sectional area of ​​the vertical flue 2 is S, and the cross-sectional area of ​​the expansion flue 3 is S'=k×S, k>1. The cross-sectional area of ​​the expansion flue 3 above the vertical flue 2 is larger than that of the vertical flue 2, so at the same flue gas flow rate, the flue gas flow velocity in the expansion flue 3 is lower.

[0046] Furthermore, the distance between the first ejector 6 and the inlet of the expansion flue 3 is h , m;

[0047] Formula (1),

[0048] In the formula, C d is the drag coefficient, which is taken as 0.5; g is the acceleration due to gravity, take 9.8m / s 2 , Φ is the particle size of calcium-based deacidifying agent particles, m; r Ca is the density of calcium-based deacidifier particles, kg / m 3 ; S is the cross-sectional area of ​​the vertical flue 2, m 2 ; L is the length of the expansion flue 3, m; Q is the flue gas flow rate, m 3 / s; p Smoke density, kg / m 3 ; k It is the ratio of the cross-sectional area of ​​the expansion flue 3 to the cross-sectional area of ​​the vertical flue 2.

[0049] After the calcium-based deacidifier particles enter the expansion flue 3 with the flue gas, the flue cross-sectional area expands, the flue gas velocity decreases, and the thrust of the flue gas decreases, which is less than the gravity of the calcium-based deacidifier particles. Therefore, the upward movement speed of the calcium-based deacidifier particles gradually decreases and moves downward. After falling to a certain position in the vertical flue 2, it moves upward again, and this cycle forms a fluidized state. During this period, the calcium-based deacidifier particles react with HCl in the flue gas to reduce the HCl concentration in the flue gas and slow down the high-temperature chlorine corrosion rate of the downstream heating surface. The flue gas carries fly ash particles in a softened or molten state, which collide and combine with the fluidized calcium-based deacidifier particles during the upward movement of the flue gas, preventing them from flowing to the downstream heating surface.

[0050] By setting requirements on flue design parameters and physical parameters of calcium-based deacidifier, it can be ensured that the injected calcium-based deacidifier particles will not flow with the flue gas to the rear horizontal convection heat exchange surface.

[0051] In this embodiment, the vertical distance between the second injector 7 and the first injector 6 is x , m;

[0052] Formula (2),

[0053] In the formula, v 0 is the initial velocity of the concentrated liquid injected by the second injector, m / s; v t is the vertical velocity at time t, m / s; a is the acceleration in the vertical direction, m / s 2 ; r is the smoke density, take 0.3kg / m 3 ; C d is the drag coefficient, which is taken as 0.5; g is the acceleration due to gravity, take 9.8m / s 2 ; is the droplet size of the sprayed concentrated liquid, m; β is the angle between the second ejector and the horizontal direction, °; t is the evaporation time of the concentrate, s.

[0054] The evaporation time t of the concentrated liquid is calculated by formula (3):

[0055] Formula (3),

[0056] In the formula, ρ 液 is the density of the concentrate, take 1000kg / m³; Cp is the specific heat capacity of the concentrated solution, which is taken as 4200 J / (kg·K); is the droplet size of the concentrated liquid sprayed by atomization, m; l is the thermal conductivity of flue gas, W / (m·K); l s is the thermal conductivity of the concentrated liquid, W / (m·K); V is the latent heat of vaporization of the concentrated liquid, J / kg; T is the flue gas temperature at the second injector 7, K; T s is the concentrate temperature, K.

[0057] By arranging the second injector 7 at a suitable position on the vertical flue 2, the injected concentrated liquid can reach the fluidized layer before completely evaporating in the flue gas, so as to adsorb and capture the calcium-based deacidifying agent and fly ash particles, and promote their combination into large particles for sedimentation.

[0058] In this embodiment, the first injector 6 is connected to an injection pipe, and the calcium-based deacidifying agent particles are injected by a Roots blower. During the operation of this system, the Roots blower is used to continuously inject quicklime particles into the vertical flue 2 by blowing air; in other embodiments, the calcium-based deacidifying agent particles can also be slaked lime.

[0059] Specifically, the calcium-based deacidifying agent particles are stored in a calcium-based deacidifying agent bin, and a pan feeder distribution motor and a loss-in-weight scale feeder are installed at the outlet of the calcium-based deacidifying agent bin to achieve real-time recording and dynamic adjustment of the dosage of the calcium-based deacidifying agent particles.

[0060] At the same time, HCl concentration measuring points (not shown in the figure) are provided at the installation location of the second injector 7 and the outlet of the expansion flue 3 to calculate the utilization rate of the added calcium-based deacidifying agent particles. α ,

[0061] Formula (4),

[0062] In the formula, Q is the flue gas flow rate, m 3 / s; c 1 、c 2 are the actual HCl concentrations in the flue gas at the installation location of the second injector and at the outlet of the expansion flue, kg / m 3 ; m is the dosage of calcium-based deacidifying agent per unit time, kg / s; oh is the effective content of the calcium-based deacidifier, 36.5 is the molecular weight of HCl, and n is 1 / 2 of the molecular weight of the calcium-based deacidifier. In this embodiment, quicklime is sprayed as the calcium-based deacidifier, and the value of n is 1 / 2 of the molecular weight of CaO, n=28

[0063] Furthermore, by uploading the calcium-based deacidification agent particle dosage measured by the loss-in-weight scale feeder, the HCl concentration data at the installation point of the second injector and the outlet of the expansion flue to the DCS control system, it can be used to quickly and accurately calculate the utilization rate of the calcium-based deacidification agent. α .

[0064] In this embodiment, according to the flue gas flow Q , Real-time calculation of calcium-based deacidification agent utilization α , the actual HCl concentration in the flue gas at the installation location of the second injector c 1 and the preset HCl concentration in the flue gas at the outlet of the expansion flue c 3. Calculate the amount of calcium-based deacidifying agent M currently required for the waste incineration flue gas treatment system, which is used as the feedforward control signal of the PID regulator of the loss-in-weight scale feeder to achieve accurate on-demand addition of calcium-based deacidifying agent and avoid waste caused by excessive addition of calcium-based deacidifying agent particles.

[0065] Formula (5),

[0066] In the formula, Q is the flue gas flow rate, m 3 / s; c 1 is the actual HCl concentration in the flue gas at the installation location of the second injector, kg / m 3 ; c 3 is the preset HCl concentration in the flue gas at the outlet of the expansion flue, kg / m 3 ; α The utilization rate of calcium-based deacidifier, oh It is the effective content of calcium-based deacidifier.

[0067] In this embodiment, a pressure detection assembly (not shown in the figure) is provided at the outlet of the expansion flue 3, and the second injector 7 sprays the concentrated liquid intermittently according to the airflow pressure at the outlet of the expansion flue 3. The calcium-based deacidifying agent particles collide and combine with the softened and melted fly ash particles to form a mixture particle with a higher content of alkaline oxides, thereby increasing the melting point and making it easier to solidify. The concentrated liquid is sprayed back into the furnace to evaporate and absorb heat, which reduces the flue gas temperature, and then the calcium-based deacidifying agent and the fly ash particles are quickly combined and solidified into particles with larger particle size, which are separated from the fluidized state, fall downward to the grate, and are discharged into the slag drop pipe and enter the slag pit for removal from the system, further reducing the risk of ash coking on the heated surface.

[0068] Furthermore, the residence time of the calcium-based deacidifying agent in the fluidized state in the furnace can be controlled by adjusting the period of the concentrated liquid gap back-spraying. In this embodiment, a pressure sensor can be set at the outlet of the expansion flue 3, and whether the concentrated liquid needs to be sprayed is determined based on the real-time airflow pressure at the outlet of the expansion flue 3 and the pressure difference before the calcium-based deacidifying agent particles are sprayed into the inlet. If the pressure difference is higher than a certain set value, it means that the calcium-based deacidifying agent particle content in this section of the flue is high, the resistance is increased, and the concentrated liquid needs to be sprayed to make some of them combine into large particles and settle.

[0069] The waste incineration flue gas treatment system of this embodiment can reduce the footprint of the boiler, save steel frame structure consumables, and reduce construction costs while retaining the advantages of the horizontal arrangement of the convection heat exchange device. By spraying calcium-based deacidification agent particles into the vertical flue 2 and the expansion flue 3 for fluidization reaction, dechlorination in the furnace is achieved, high-temperature chlorine corrosion of the heating surface is slowed down, the service life of the equipment is extended, and the maintenance pressure and maintenance cost are reduced. At the same time, the injected calcium-based deacidification agent particles can collide and combine with the molten fly ash to form larger particles that settle to the grate and are discharged into the slag pit with the movement of the grate, avoiding a large amount of fly ash adhering to the heating surface, which is beneficial to slowing down coking and improving the stability of boiler operation.

[0070] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A waste incineration flue gas treatment system, characterized in that: include: An incinerator (1), a vertical flue (2), an expansion flue (3), a horizontal flue (4) and a reaction tower (5); a slag dropping pipe (8) is provided at the bottom of the incinerator (1), and the residue after the garbage incineration is discharged from the incinerator (1) through the slag dropping pipe (8); a vertical flue (2) is provided at the top of the incinerator (1), and the vertical flue (2) is connected to the expansion flue (3); one end of the horizontal flue (4) is connected to the upper side of the expansion flue (3), and the other end of the horizontal flue (4) is connected to the reaction tower (5); the flue gas generated in the incinerator (1) flows through the vertical flue (2), the expansion flue (3) and the horizontal flue (4) in sequence and then enters the reaction tower (5). 5); the inner diameter of the expansion flue (3) is larger than the inner diameter of the vertical flue (2); a first injector (6) and a second injector (7) are provided above the side of the vertical flue (2); the first injector (6) is used to spray calcium-based deacidifying agent particles, the calcium-based deacidifying agent particles are in a fluidized state between the vertical flue (2) and the expansion flue (3), and contact and react with the flue gas generated in the incinerator (1) to achieve flue gas deacidification; the second injector (7) is used to spray the concentrated liquid generated by the biochemical treatment of the landfill leachate, the concentrated liquid absorbs heat, reduces the flue gas temperature, and enables the calcium-based deacidifying agent particles and the fly ash particles in the flue gas to settle into the slag drop pipe (8); The second injector (7) is located below the first injector (6), the flue gas temperature at the first injector (6) is lower than 750°C, the flue gas temperature at the second injector (7) is lower than 850°C, and the angle β between the injection angle of the second injector (7) and the horizontal direction is 60°±5°; The distance between the first ejector (6) and the inlet of the expansion flue (3) is h , m; Formula (1), In the formula, C d is the drag coefficient, which is taken as 0.5; g is the acceleration due to gravity, take 9.8m / s 2 , Φ is the particle size of calcium-based deacidifying agent particles, m; ρ Ca is the density of calcium-based deacidifier particles, kg / m 3 ; S is the cross-sectional area of ​​the vertical flue (2), m 2 ; L is the length of the expansion duct (3), m; Q is the flue gas flow rate, m 3 / s; ρ is the smoke density, kg / m 3 ; k is the ratio of the cross-sectional area of ​​the expansion flue (3) to the cross-sectional area of ​​the vertical flue (2), k >1; The vertical distance between the second injector (7) and the first injector (6) is x , m; Formula (2), In the formula, v 0 is the initial velocity of the concentrated liquid injected by the second injector (7), m / s; v t is the vertical velocity at time t, m / s; a is the acceleration in the vertical direction, m / s 2 ; ρ is the smoke density, take 0.3kg / m 3 ; C d is the drag coefficient, which is taken as 0.5; g is the acceleration due to gravity, take 9.8m / s 2 ; is the droplet size of the sprayed concentrated liquid, m; β is the angle between the second ejector and the horizontal direction, °; t is the evaporation time of the concentrate, s.

2. The waste incineration flue gas treatment system according to claim 1, characterized in that: Evaporation time of the concentrate t Calculated by formula (3), Formula (3), In the formula, ρ 液 is the density of the concentrate, take 1000kg / m³; Cp is the specific heat capacity of the concentrated solution, which is taken as 4200 J / (kg·K); is the droplet size of the concentrated liquid sprayed by atomization, m; λ is the thermal conductivity of flue gas, W / (m·K); λ s is the thermal conductivity of the concentrated liquid, W / (m·K); V is the latent heat of vaporization of the concentrated liquid, J / kg; T is the flue gas temperature at the second injector (7), K; T s is the concentrate temperature, K.

3. The waste incineration flue gas treatment system according to claim 1 or 2, characterized in that: The first injector (6) is externally connected to an injection pipe, and uses a Roots blower to inject calcium-based deacidifying agent particles, wherein the calcium-based deacidifying agent is quicklime or slaked lime.

4. The waste incineration flue gas treatment system according to claim 1 or 2, characterized in that: A plurality of convection heat exchangers (9) are arranged in the horizontal flue (4) to achieve heat exchange and cooling of the flue gas; the flue gas temperature at the outlet of the expansion flue (3) is 640°C±40°C.

5. The waste incineration flue gas treatment system according to claim 1 or 2, characterized in that: HCl concentration measuring points are provided at the installation location of the second ejector (7) and at the outlet of the expansion flue (3) to calculate the utilization rate of the added calcium-based deacidifying agent particles. α , Formula (4), In the formula, Q is the flue gas flow rate, m 3 / s; c 1 、c 2 are the actual HCl concentrations in the flue gas at the installation location of the second injector (7) and at the outlet of the expansion flue (3), kg / m 3 ; m is the dosage of calcium-based deacidifying agent per unit time, kg / s; ω is the effective content of the calcium-based deacidifier, 36.5 is the molecular weight of HCl, and n is 1 / 2 of the molecular weight of the calcium-based deacidifier.

6. The waste incineration flue gas treatment system according to claim 5, characterized in that: The preset HCl concentration in the flue gas at the outlet of the expansion flue (3) is c 3. The amount of calcium-based deacidifying agent particles currently required for the waste incineration flue gas treatment system M Calculated by formula (5), Formula (5), In the formula, Q is the flue gas flow rate, m 3 / s; c 1 is the actual HCl concentration in the flue gas at the installation location of the second injector (7), kg / m 3 ; c 3 is the preset HCl concentration in the flue gas at the outlet of the expansion flue (3), kg / m 3 ; α The utilization rate of calcium-based deacidifier, ω It is the effective content of calcium-based deacidifier.

7. The waste incineration flue gas treatment system according to claim 1 or 2, characterized in that: A pressure detection component is provided at the outlet of the expansion flue (3), and the second injector (7) sprays the concentrated liquid intermittently according to the airflow pressure at the outlet of the expansion flue (3).

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