CN109745842B - Heating decomposing furnace for recycling calcium oxide - Google Patents
Heating decomposing furnace for recycling calcium oxide Download PDFInfo
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Abstract
The application relates to a heating decomposing furnace for recycling calcium oxide. Comprising the following steps: the heating device comprises a furnace body, a heating pipe and a heating pipe, wherein the furnace body is of a shell-and-tube structure; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks are connected with the discharging pipe, the cross sections of the collecting tanks are inverted trapezoids, the side walls of two adjacent collecting tanks and the plane where the bottom surface of the collecting tank is located enclose a triangular cavity, and air outlets communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices. The application provides a heating decomposing furnace for recycling calcium oxide in a sectional mode according to the decomposition temperature required by the desulfurized gypsum, and simultaneously generates high-concentration SO 2 Can be used for preparing sulfuric acid and elemental sulfur, realizes the recycling of sulfur, does not cause secondary pollution to ecological environment, and realizes the recycling of flue gas desulfurizing agent.
Description
Technical Field
The application belongs to the field of solid waste resource utilization, and particularly relates to a heating decomposing furnace for recycling calcium oxide.
Background
For SO in flue gas 2 The discharge standard of (2) reaches 35mg/Nm 3 The history says that the emission of the power plant reaches an ultra-clean level; at present, for SO, a coal-fired unit of a power plant 2 The flue gas purification mode is to utilize limestone-gypsum wet desulfurization technology and CaCO 3 And H 2 Under the action of O, SO is reacted with 2 With sulphate (CaSO) 4 *2H 2 O gypsum) is fixed in solid waste, which is currently about 95% of the national share. Although SO can be made by using this technique 2 The national most stringent environmental protection standard is reached,however, the limestone is used in a large amount for a long time, so that the limestone exploitation industry is flooded, a large amount of mountain bodies are hollowed out, the ecological environment of mountain vegetation and living human and animals is seriously damaged, and inferior gypsum is produced by using a limestone-gypsum wet desulphurization technology for about 2.15 hundred million tons each year; the gypsum has poor properties, contains a large amount of impurities and heavy metals which cannot be separated, so that the gypsum is rarely utilized, a large amount of waste desulfurized gypsum is accumulated, groundwater is polluted, and a large amount of land is occupied. Thus, the inventors found that: the limestone-gypsum wet desulfurization technology meets the requirements of flue gas purification of a power plant, but also causes the problems of secondary pollution of ecological environment and the like.
Disclosure of Invention
Aiming at the problem of secondary pollution to the ecological environment in the existing wet desulfurization technology of flue gas limestone-gypsum in a power plant, the application provides a heating decomposing furnace for recycling calcium oxide. The application provides a heating decomposing furnace for recycling calcium oxide in a sectional mode according to the decomposition temperature required by the desulfurized gypsum, and simultaneously generates high-concentration SO 2 Can be used for preparing sulfuric acid and elemental sulfur, realizes the recycling of sulfur, does not cause secondary pollution to ecological environment, and realizes the recycling of flue gas desulfurizing agent. The application realizes the recycling of the desulfurizing agent, and realizes the recycling of the desulfurizing agent and SO through a reasonable process arrangement mode 2 And (5) recycling.
In order to achieve the technical purpose, the application adopts the following technical scheme:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks are connected with the discharging pipe, the cross sections of the collecting tanks are inverted trapezoids, the side walls of two adjacent collecting tanks and the plane where the bottom surface of the collecting tank is located enclose a triangular cavity, and air outlets communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
The research of the application finds that: dihydrate gypsum (CaSO) 4 *2H 2 In the process of preparing the calcium oxide, three stages of dehydration, preheating and high-temperature reduction are generally carried out, so that the operations are needed to be completed together by a plurality of devices such as a calcium sulfate preheater, a decomposing furnace, a high-temperature separator, a condenser and the like, but the design is complex, and the raw materials and the energy utilization rate are low. Therefore, the application designs a heating decomposing furnace for recovering calcium oxide, which is divided into a low-temperature preheating section, a high-temperature decomposing section and a low-temperature cooling section from top to bottom, thereby realizing the recycling of desulfurizing agent (CaO) and high-concentration SO 2 Is used for recycling.
On the other hand, high concentration SO is generated during the high temperature reaction of calcium sulfate 2 Gas and water vapor, in order to effectively guide out the gas, realize the recycling utilization, and avoid influencing the subsequent reaction rate. The application designs an air guide device, which effectively realizes high concentration SO by utilizing the pressure difference between a triangular cavity formed between upper material collecting grooves and a rectangular cavity between lower material discharging pipes 2 The gas is enriched and rapidly led out from the lower part of the collecting tank.
Because the collecting trough is arranged in an inverted trapezoid, when the adding amount of calcium sulfate is large, a large downward pressure is generated on the collecting trough, therefore, in some embodiments, the application is further provided with the supporting plate or the supporting rod on the side wall of the collecting trough SO as to improve the stability of the collecting trough, and meanwhile, if a plurality of groups of supporting plates or supporting rods are arranged between two collecting troughs in parallel, a Venturi effect can be formed, and the high-concentration SO is further accelerated 2 And (5) enriching and guiding out the gas.
If the installation position of the supporting plate or the supporting rod is too high, the space is narrow, the installation is not facilitated, and the supporting effect on the collecting tank is small. Therefore, in some embodiments, the supporting plate or the supporting rod is positioned on the plane of the bottom surface of the collecting tank, so that the supporting effect on the collecting tank is obvious while the installation is facilitated.
In some embodiments, the inner diameter of the blanking pipe is equal to the length of the bottom edge of the cross section of the collecting tank so as to ensure the triangular cavity formed between the collecting tanks and the blanking pipe belowPressure difference between rectangular cavities promotes high concentration SO 2 And (5) enriching and guiding out the gas.
In some embodiments, the blanking pipes are arranged vertically, and the area between the blanking pipes is a rectangular cavity.
In some embodiments, the gas outlet is positioned below the collecting tank, and the gas outlet is positioned in the triangular cavity area, which is more beneficial to high concentration SO 2 The rapid transportation of the gas ensures the vast majority of high concentration SO 2 The gas can be removed.
In some embodiments, the collection trough may be in the shape of a paper cup, a paper cup-like shape (circular bottom surface, quadrilateral top surface), or a long trough, as shown in fig. 3, 4, 5.
In some embodiments, the bottom of the pyrolysis zone is further provided with a fluidization device, the fluidization device is a hollow pipe, and a plurality of nozzles are arranged on the side wall of the hollow pipe, and the nozzles are arranged in a line.
In some embodiments, two nozzles are co-located and discharging in the hollow conduit, as shown in fig. 7;
the hollow pipeline extends into the decomposing furnace through a flange plate (the flange plate is positioned at the bottom of the high-temperature stage) on the side wall of the decomposing furnace, and the direction of the nozzle is downward, so that the introduced reducing gas fully reacts with the calcium sulfate.
In some embodiments, the decomposing furnace is divided into three sections, namely a low-temperature preheating section, a high-temperature decomposing section and a low-temperature cooling section from top to bottom. After the desulfurized gypsum enters the heating decomposition furnace, the desulfurized gypsum firstly passes through a low-temperature preheating section under the action of self gravity, is heated to 350-450 ℃ by utilizing the waste heat of flue gas, the external moisture and molecular combination moisture of the desulfurized gypsum are firstly removed, and the generated water vapor is led out by an air guide device in the heating decomposition furnace; then anhydrous calcium sulfate enters a pyrolysis section, the calcium sulfate is heated to 800-1200 ℃, and a fluidization device is arranged at the bottom to reduce the concentration of reducing gas (CO/H) 2 /CH 4 Etc.) or industrial sulfur-containing exhaust gas is introduced into a pyrolysis section, and according to the present related research, the decomposition temperature of calcium sulfate can be obviously reduced under the condition of the existence of reducing substances such as coke, sulfur and the likeThe temperature is reduced to about 1100 ℃ at 1350 ℃.
The application also provides a system for recovering calcium oxide, comprising: any one of the above decomposing furnaces.
The application also provides a method for recovering calcium oxide, which comprises the following steps:
preheating the dihydrate gypsum to 350-450 ℃ to form anhydrous gypsum;
heating the anhydrous gypsum to 800-1200 ℃ to form high-temperature calcium sulfate;
the high-temperature calcium sulfate reacts with solid carbon material and reducing gas at 800-1200 ℃ in a contact way, and calcium oxide and high-concentration SO are respectively collected 2 Gas and a part of excess reducing gas.
In some embodiments, the carbon material has a particle size of 60 μm-3mm and is at least one of pulverized coal, activated coke, activated semicoke, activated carbon, carbonized material, or graphite;
in some embodiments, the reducing gas has a temperature of 1200 ℃ to 1500 ℃ and a main component of N 2 、CO、H 2 、CH 4 、CO 2 。
The application has the beneficial effects that:
(1) The application provides a heating decomposing furnace for recycling calcium oxide. According to the property and the material composition of the desulfurization gypsum, the temperature interval of the decomposing furnace is reasonably arranged, dehydration and decomposition reaction of the desulfurization gypsum are realized in different temperature intervals, and the recycling of the desulfurizing agent (CaO) and high-concentration SO are realized 2 Is used for recycling. Has wide application prospect.
(2) The method has the advantages of simplicity, low cost, universality and easiness in large-scale production.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application.
FIG. 1 is a schematic view of a calcium sulfate heating decomposing furnace according to example 1; wherein, (1) a calcium sulfate storage bin, (2) a heating decomposing furnace and (3) a filtering device;
fig. 2 is a plan view of the air guide device of example 1, wherein 1. Collecting trough, 2. Supporting plate, 3. Blanking pipe, 4 calcium sulfate powder, 5 gas outlet.
FIG. 3 is a perspective view I of the air guide device of example 1;
FIG. 4 is a perspective view II of the air guiding device of embodiment 1;
fig. 5 is a perspective view iii of the air guide device of embodiment 1;
figure 6 shows a view of the flow splitting device of example 2, wherein 6 is a flange, 7 is a hollow conduit, 8 is a nozzle.
Fig. 7 example 3 nozzle structure arranged side by side.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
As described in the background art, the limestone-gypsum wet desulfurization technology can cause secondary pollution of the ecological environment. Therefore, the application provides a heating decomposing furnace for recycling calcium oxide, which mainly comprises:
the main product of limestone-gypsum wet desulfurization technology and semi-dry desulfurization technology is gypsum (CaSO 4 *2H 2 O), two molecules of water of crystallization are adsorbed on the basis of sulphate. According to related studies, it was shown that gypsum dihydrate (CaSO) was heated when the temperature was 65 deg.c 4 *2H 2 O), the structured water starts to be released, but the dehydration speed is increasedIs relatively slow. When the water vapor pressure reaches 971mmHg at about 107 ℃, the dehydration rate becomes fast. As the temperature continues to rise, the dehydration is accelerated, and at 170-190 ℃, the dihydrate gypsum dehydrates at a rapid rate to become alpha-hemihydrate gypsum (alpha-CaSO) 4 *0.5H 2 O), or beta-hemihydrate gypsum (beta-CaSO) 4 *0.5H 2 O). When the temperature continues to rise to 220 ℃ and 320-360 ℃, hemihydrate gypsum (CaSO 4 *0.5H 2 O) is continuously dehydrated to become alpha-soluble anhydrous gypsum (alpha-CaSO) 4 ). The dehydration process of the desulfurized gypsum thus occurs slowly over a wide temperature range. The desulfurization gypsum is first dehydrated and preheated, and the desulfurization gypsum (CaSO) 4 *2H 2 O) firstly, entering a calcium sulfate storage bin for storage, feeding the calcium sulfate storage bin into a heating decomposition furnace through a gas locking feeder, dividing the inside of the decomposition furnace into three sections according to different temperatures, namely a low-temperature preheating section, a high-temperature decomposition section and a low-temperature cooling section, firstly, passing through the low-temperature preheating section under the action of gravity of the self after the desulfurized gypsum enters the heating decomposition furnace, heating to 350-450 ℃ by utilizing the waste heat of flue gas, and firstly, removing external moisture and molecular combined moisture of the desulfurized gypsum, wherein the generated water vapor is led out through a gas guide device in the heating decomposition furnace; secondly, anhydrous calcium sulfate enters a pyrolysis section, the calcium sulfate is heated to 800-1200 ℃, and meanwhile, a fluidization device is arranged at the bottom, so that the (CO/H) 2 /CH 4 Etc.) or industrial sulfur-containing exhaust gas is introduced into a pyrolysis section, according to the present related research, the decomposition temperature of calcium sulfate can be obviously reduced from 1350 ℃ to about 1100 ℃ under the condition that the reducing substances such as coke, sulfur and the like exist, and the reaction equation is shown as follows
2C+CaSO 4 ＝CaS+CO 2
CaS+3CaSO 4 ＝4CaO+4SO 2
S 2 +CaSO 4 ＝CaS+2SO 2
CaS+3CaSO 4 ＝4CaO+4SO 2
The reaction time of the materials in the high-temperature heating section is 10 s-60 s, and the reaction products mainly comprise calcium oxide powder (CaO) and high-concentration SO 2 Gas, high concentration SO produced 2 The gas is discharged out of the heating decomposing furnace through the gas guide device and is used for preparing acid industrially or preparing sulfur by carbothermic reduction, SO 2 The concentration of the gas is about 5% -30% and the temperature range is about 700-1000 ℃. The high-temperature heat exchange medium is high-temperature flue gas, and is provided by burning fossil fuel by the high-temperature flue gas of a power plant or an incinerator. The calcium oxide powder (CaO) formed by the pyrolysis section enters a low-temperature cooling section from an air guide device, the temperature of the calcium oxide powder is reduced to 40-100 ℃, and the cooling medium can be air or water; and discharging the cooled calcium oxide powder from the heating decomposing furnace. The materials are prepared from dihydrate gypsum (CaSO) under the action of a heating decomposing furnace 4 *2H 2 And O) calcining to form calcium oxide (CaO) powder, and sending the powder to a desulfurizing tower to continuously perform desulfurization treatment so as to realize recycling of the desulfurizing agent. The carbon materials for reducing the reaction temperature can be added in a calcium sulfate storage bin and enter a heating decomposition furnace together through a gas locking feeder, and the carbon materials with the particle size of 60 mu m-3mm can be various types of carbon materials such as coal dust, active coke, active semicoke, active carbon, carbonized materials, graphite and the like.
The heating pipes are horizontally staggered, the calcium sulfate powder material is arranged outside the heating pipes, and the gas-phase heat exchange medium is arranged inside the heating pipes. The high temperature flue gas needed by the decomposing furnace is generated by burning fossil fuel by a burner, the temperature of the flue gas is between 1100 and 1300 ℃, the flue gas enters a high temperature decomposing section of the heating decomposing furnace for providing the environment temperature needed by decomposing calcium sulfate powder, the temperature of the flue gas discharged from the high temperature decomposing section is between 500 and 700 ℃, and the flue gas enters a low temperature preheating section for preparing the dihydrate gypsum (CaSO) 4 *2H 2 O) dehydration reaction; the temperature of the flue gas discharged from the low-temperature preheating section of the heating decomposing furnace is between 200 and 500 ℃, and the flue gas is sent into a flue gas treatment system and is discharged after the purification reaches the standard. According to the actual condition of the plant used by the device, the reducing gas (CO/H) generated by the plant can be used 2 /CH 4 Etc.) or sulfur-containing exhaust gas is introduced into a low-temperature cooling section of the heating decomposing furnace, the waste heat of the hot calcium oxide powder is recovered, the temperature is heated to 700-1100 ℃, and then the waste heat is introduced into the shell side of the high-temperature decomposing section to participate in gypsum decomposition reaction, so that the reaction temperature of calcium sulfate decomposition is reduced. Cooling Duan Li the temperature of the calcium oxide powder with water, air or other cooling mediumThe heat exchange coefficient of the cooling medium and the calcium oxide powder is greatly improved, the heat exchange effect is enhanced, and water or air for recovering the waste heat of the calcium oxide powder can be used for generating electricity by a waste heat boiler, participating in the combustion reaction of a combustor and the like. The cooled roasting slag enters a filtering device, filtrate is used as a desulfurizing agent for recycling, and filter residues are returned to a combustor to be burned as fuel.
An air guide device in a calcium sulfate heating decomposing furnace consists of a collecting groove, a supporting plate and a discharging pipe, wherein materials move downwards from top to bottom, and the air guide device plays roles in conveying materials and guiding air. The thermal decomposition tower is used for thermal decomposition of solid particle materials, SO that the materials have obvious material lines after passing through the blanking pipe, gas phase spaces are formed between the adjacent blanking pipes, and water vapor and high-concentration SO (SO) are generated by decomposition 2 Rising into the air space, discharging the heated decomposing furnace through flange holes or pipelines arranged on the wall surface of the heated decomposing furnace shell, and continuously and reliably operating the whole process.
Example 1:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks 1 are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks 1 are connected with a blanking pipe 3, the cross sections of the collecting tanks 1 are inverted trapezoids, the side walls of two adjacent collecting tanks 1 and the plane where the bottom surfaces of the collecting tanks 1 are located enclose a triangular cavity, and air outlets 5 communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
The operation mode of the device is as follows: the calcium sulfate powder material is arranged outside the heating pipe, and the gas phase heat exchange medium is arranged inside the heating pipe. The high temperature flue gas needed by the decomposing furnace is generated by burning fossil fuel by a burner, the temperature of the flue gas is between 1100 and 1300 ℃, the flue gas enters a high temperature decomposing section of the heating decomposing furnace for providing the environment temperature needed by decomposing calcium sulfate powder, the temperature of the flue gas discharged from the high temperature decomposing section is between 500 and 700 ℃, and the flue gas enters a low temperature preheating section for preparing the dihydrate gypsum (CaSO) 4 *2H 2 O) dehydration reaction; the temperature of the flue gas discharged from the low-temperature preheating section of the heating decomposing furnace is between 200 and 500 ℃, and the flue gas is sent into a flue gas treatment system and is discharged after the purification reaches the standard. According to the actual condition of the plant used by the device, the reducing gas (CO/H) generated by the plant can be used 2 /CH 4 Etc.) or sulfur-containing exhaust gas is introduced into a low-temperature cooling section of the heating decomposing furnace, the waste heat of the hot calcium oxide powder is recovered, the temperature is heated to 700-1100 ℃, and then the waste heat is introduced into the shell side of the high-temperature decomposing section to participate in gypsum decomposition reaction, so that the reaction temperature of calcium sulfate decomposition is reduced. The temperature of the calcium oxide powder is further reduced by using water, air and other cooling mediums at the low temperature for cooling Duan Li, the cooling medium and the calcium oxide powder are in inverse potential heat exchange as a whole, the heat exchange coefficient can be greatly improved, the heat exchange effect is enhanced, the water or air for recovering the waste heat of the calcium oxide powder can be used for generating power by a waste heat boiler, participating in the combustion reaction of a combustor and the like, and the heat exchange coefficient of the material side is 20-70W/(m) according to experimental conditions 2 * K) The method comprises the steps of carrying out a first treatment on the surface of the The moving speed of the material in the heating decomposing furnace is 2-5 cm/min. The cooled roasting slag enters a filtering device, filtrate is used as a desulfurizing agent for recycling, filter residues are returned to a burner to be burned as fuel,
wherein the collecting trough is in a paper cup shape, as shown in fig. 3.
In an air guide device in the calcium sulfate heating decomposing furnace, materials move from top to bottom, and the air guide device plays roles in conveying materials and guiding air. The thermal decomposition tower is used for thermal decomposition of solid particle materials, SO that the materials have obvious material lines after passing through the blanking pipe 3, gas phase spaces are formed between the adjacent blanking pipes 3, and water vapor and high-concentration SO generated by decomposition are generated 2 Rising into the gas space, discharging the heated decomposing furnace through flange holes 5 or pipelines arranged on the wall surface of the heated decomposing furnace shell, and continuously and reliably operating the whole process, wherein the actual experimental conditions show that: the decomposing furnace of the application generates SO 2 The amount of (C) is in the range of 0.2 to 0.6kg/h kg (CaSO) 4 *2H 2 O) and the amount of water vapor is in the range of 0.1 to 0.4kg/h kg (CaSO) 4 *2H 2 O); the flow rate of the gas in the exhaust pipeline is controlled to be 3-10 m/s.
Example 2:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks 1 are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks 1 are connected with a blanking pipe 3, the cross sections of the collecting tanks 1 are inverted trapezoids, the side walls of two adjacent collecting tanks 1 and the plane where the bottom surfaces of the collecting tanks 1 are located enclose a triangular cavity, and air outlets 5 communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
Because the collecting trough 1 is arranged in an inverted trapezoid, when the adding amount of the calcium sulfate 4 is larger, larger downward pressure is generated on the collecting trough 1, therefore, in the embodiment, the application is further provided with the supporting plate or the supporting rod 2 on the side wall of the collecting trough 1 SO as to improve the stability of the collecting trough 1, and meanwhile, if the supporting plate or the supporting rod 2 is arranged in parallel between the two collecting troughs 1, venturi effect can be formed, and high-concentration SO is further accelerated 2 And (5) enriching and guiding out the gas.
The bottom of the pyrolysis zone is also provided with a fluidization device, the fluidization device is a hollow pipeline 7, the side wall of the hollow pipeline is provided with a plurality of nozzles 8, and the nozzles are arranged in a line.
The hollow pipeline 5 extends into the decomposing furnace through a flange 6 (the flange is positioned at the bottom of the high-temperature stage by stage) on the side wall of the decomposing furnace, and the direction of a nozzle 8 is downward, so that the introduced reducing gas fully reacts with calcium sulfate, and the decomposing efficiency is improved;
wherein the collecting trough is paper cup-like (rectangular top surface and circular bottom surface), as shown in fig. 4.
The device of this example operates in the same manner as in example 1.
Example 3:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks 1 are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks 1 are connected with a blanking pipe 3, the cross sections of the collecting tanks 1 are inverted trapezoids, the side walls of two adjacent collecting tanks 1 and the plane where the bottom surfaces of the collecting tanks 1 are located enclose a triangular cavity, and air outlets 5 communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
If the installation position of the supporting plate or the supporting rod 2 is too high, the space is narrow, the installation is not facilitated, and the supporting effect on the collecting tank 1 is small. Therefore, in this embodiment, the supporting plate or the supporting rod 2 is located on the plane where the bottom surface of the collecting trough 1 is located, which is beneficial to installation and has obvious supporting effect on the collecting trough 1.
In this embodiment, two nozzles are arranged at the same position of the hollow pipe 7, as shown in fig. 7.
Wherein the collecting groove is a long groove, as shown in figure 5
The device of this example operates in the same manner as in example 1.
Example 4:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks 1 are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks 1 are connected with a blanking pipe 3, the cross sections of the collecting tanks 1 are inverted trapezoids, the side walls of two adjacent collecting tanks 1 and the plane where the bottom surfaces of the collecting tanks 1 are located enclose a triangular cavity, and air outlets 5 communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
In this embodiment, the inner diameter of the discharging pipe 3 is equal to the length of the bottom edge of the cross section of the collecting trough 1, SO as to ensure the pressure difference between the triangular cavity formed between the collecting troughs 1 and the rectangular cavity between the discharging pipe 3 below, and promote high concentration SO 2 And (5) enriching and guiding out the gas.
The device of this example operates in the same manner as in example 1.
Example 5:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks 1 are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks 1 are connected with a blanking pipe 3, the cross sections of the collecting tanks 1 are inverted trapezoids, the side walls of two adjacent collecting tanks 1 and the plane where the bottom surfaces of the collecting tanks 1 are located enclose a triangular cavity, and air outlets 5 communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
The blanking pipes 3 are vertically arranged, and the areas between the blanking pipes 3 are rectangular cavities.
The device of this example operates in the same manner as in example 1.
Example 6:
a heating decomposition furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; the heating furnace is characterized in that a plurality of groups of air guide devices are further arranged in a cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks 1 are arranged on the upper portions of the air guide devices, the bottoms of the collecting tanks 1 are connected with a blanking pipe 3, the cross sections of the collecting tanks 1 are inverted trapezoids, the side walls of two adjacent collecting tanks 1 and the plane where the bottom surfaces of the collecting tanks 1 are located enclose a triangular cavity, and air outlets 5 communicated with the side walls of the furnace shell are arranged on the side walls of the air guide devices.
In some embodiments, the gas outlet 5 is positioned below the collecting tank 1, and the gas outlet 5 is positioned in the triangular cavity area, which is more beneficial to high concentration SO 2 The rapid transportation of the gas ensures the vast majority of high concentration SO 2 The gas can be removed.
The device of this example operates in the same manner as in example 1.
Example 7
A method of recovering calcium oxide comprising:
preheating the dihydrate gypsum to 350-450 ℃ to form anhydrous gypsum;
heating the anhydrous gypsum to 800-1200 ℃ to form high-temperature calcium sulfate;
the high-temperature calcium sulfate reacts with solid carbon material and reducing gas at 800-1200 ℃ in a contact way, and calcium oxide and high-concentration SO are respectively collected 2 Gas and a part of excess reducing gas.
The carbon material has the particle size of 60 mu m-3mm and is coal powder;
the temperature of the reducing gas is 1200-1500 ℃ and the main component is N 2 、CO、H 2 、CH 4 、CO 2 。
Finally, it should be noted that the above-mentioned embodiments are only preferred embodiments of the present application, and the present application is not limited to the above-mentioned embodiments, but may be modified or substituted for some of them by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. While the foregoing description of the embodiments of the present application has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the application, but rather, it is intended to cover all modifications or variations within the scope of the application as defined by the claims of the present application.
Claims (9)
1. A heating decomposing furnace for recovering calcium oxide, comprising: the furnace body is of a shell-and-tube structure, and a plurality of groups of heating pipes, a fluidization device and exhaust holes are arranged in the furnace body; a plurality of groups of air guide devices are arranged in the cavity between the heating pipe and the furnace body, the air guide devices are hollow shells, a plurality of groups of collecting tanks are arranged at the upper parts of the air guide devices, the bottoms of the collecting tanks are connected with the blanking pipe, the cross sections of the collecting tanks are reverse trapezoids, the side walls of two adjacent collecting tanks and the plane where the bottom surface of the collecting tank is located enclose a triangular cavity, and the side walls of the air guide devices are provided with air outlets communicated with the side walls of the furnace shell;
the gas outlet is positioned below the material collecting groove, and the gas outlet is positioned in the triangular cavity area;
the decomposing furnace is divided into three sections, namely a low-temperature preheating section, a high-temperature decomposing section and a low-temperature cooling section from top to bottom, wherein the bottom of the high-temperature decomposing section is also provided with a fluidization device, the fluidization device is a hollow pipeline, the side wall of the hollow pipeline is provided with a plurality of nozzles, and the nozzles are arranged in a line;
the hollow pipeline extends into the decomposing furnace through a flange plate on the side wall of the decomposing furnace, and the direction of the nozzle is downward.
2. The decomposing furnace as claimed in claim 1, wherein a support plate or a support rod is further provided on a side wall of said collecting tank.
3. The decomposing furnace as claimed in claim 2, wherein said support plate or support rod is located on a plane where a bottom surface of the aggregate tank is located.
4. The decomposing furnace as claimed in claim 1, wherein said blanking pipe has an inner diameter equal to a length of a bottom edge of a cross section of the collecting tank.
5. The decomposing furnace as claimed in claim 1, wherein said discharge pipes are vertically arranged, and a region between the discharge pipes is a rectangular cavity.
6. A system for recovering calcium oxide, comprising: the decomposing furnace as claimed in any one of claims 1 to 5, wherein a gas outlet of said decomposing furnace is connected to a gas inlet of the carbothermic reduction column.
7. A method for recovering calcium oxide using the system for recovering calcium oxide of claim 6, comprising:
preheating the dihydrate gypsum to 350-450 ℃ to form anhydrous gypsum;
heating the anhydrous gypsum to 800-1200 ℃ to form high-temperature calcium sulfate;
the high-temperature calcium sulfate reacts with solid carbon material and reducing gas at 800-1200 ℃ in a contact way, and calcium oxide and SO are respectively collected 2 Gas and a part of excess reducing gas.
8. The method of claim 7, wherein the solid carbon material has a particle size of 60 μm to 3mm and is at least one of pulverized coal, activated coke, activated semicoke, activated carbon, carbonized material, or graphite.
9. The method according to claim 7, wherein the reducing gas has a temperature of 1200 ℃ to 1500 ℃ and a main component of N 2 、CO、H 2 、CH 4 、CO 2 。
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