Method and system for utilizing waste heat of flue gas to produce porous soil improvement material with acidity

Abstract

The present invention discloses a method and a system for utilizing waste heat of flue gas to prepare porous soil improvement materials with acid, which relate to the technical fields of material preparation and environmental protection. The method comprises the following steps: weighing and mixing raw materials according to parts by weight, adding water to prepare a slurry with a solid-liquid ratio of 30-50%, sending the flue gas into a rotary spray drying device at 180-300 °C after dust removal by a multi-tube dust collector, adjusting the flow direction of the flue gas flow entering the rotary spray drying device through a hot air volute and a hot air distributor, feeding the slurry into the rotary spray drying device to form porous soil particles, and simultaneously adsorbing part of SOx and NOx contained in the flue gas. In view of the problem of high preparation cost of porous materials, the present invention changes the idea of preparing porous materials based on the gelling principle in the traditional process, combines the rapid foaming and forming characteristics of a starch and ammonium sulfate mixture with the rapid production capacity of a rotary spray drying device, and realizes product preparation based on waste heat and recyclability.

Description

Technical Field

[0001] The present invention relates to the technical fields of material preparation and environmental protection, and particularly relates to a method and system for preparing porous soil improvement materials by utilizing flue gas waste heat and acid. Background Art

[0002] The preparation methods of traditional porous materials mainly rely on the gelling reaction to generate bonding effects. Substances such as silicates in the components undergo pozzolanic reactions through high temperature or autoclaving, generating hydrated calcium silicate, hydrated calcium aluminate, and aluminate with gel properties, enabling the components to bond to each other and form clusters more easily. The preparation equipment for porous materials is generally a rotary kiln and a disk granulator. Therefore, the produced finished product particles have large particle sizes, and they need to be crushed and screened again when preparing improvement materials.

[0003] In many industrial productions, a large amount of waste heat is generated. If this waste heat is not fully utilized and is discharged into the air, it will cause a considerable waste of resources. In terms of the current situation of waste heat utilization in China, there is still much room for improvement. Low-temperature waste heat accounts for more than half of the total waste heat resources, and the utilization rate of low-temperature waste heat in China is low. Therefore, based on flue gas waste heat, developing the coupling of material preparation and waste heat utilization is an effective way to reduce the cost of porous preparation and solve the problem of low waste heat utilization rate.

[0004] The invention patent with the publication number (CN112552023A) discloses a kind of iron tailing expanded ceramsite. This method uses fly ash, iron tailings, and quartz sand as the main raw materials, and obtains ceramsite through natural curing, drying with flue gas waste heat, and high-temperature firing. However, the ceramsite prepared by this method cannot be quickly formed, and finally, it is fired at a high temperature, resulting in a relatively high preparation cost and being less environmentally friendly.

[0005] The invention patent with the publication number (CN111646771A) discloses a solid-phase foamed fly ash-free ceramsite and its preparation method. This method cures the ceramsite green balls in a steam curing device, and the air humidity in the curing device should be greater than 70%. The curing temperature program is: curing at 40 - 70°C for 0.5 - 2h, then curing at 70 - 100°C for 2 - 4h, then curing at 150 - 200°C for 8 - 12h, and finally naturally cooling to room temperature to obtain the finished product. This method has a long curing time and a complex preparation process.

[0006] Therefore, low-temperature foaming and rapid forming are the main problems restricting the utilization of this formula in flue gas waste heat, and a simple preparation process and equipment are important conditions for ensuring the low-cost production of porous materials. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for low-cost preparation of porous soil improvement materials by using flue gas waste heat as the heat source, fly ash or coal gangue as the main raw material, and a rotary spray drying device as the main equipment, and comprehensively and resourcefully utilizing the acidic components in the flue gas.

[0008] To achieve the above object, the present invention provides a method for utilizing flue gas waste heat to prepare a porous soil improvement material with acid, and the raw materials include the following components in parts by weight:

[0009] Fly ash: 60 - 85 parts;

[0010] Starch: 5 - 10 parts;

[0011] Ammonium sulfate: 1 - 3 parts;

[0012] Quartz sand: 2 - 10 parts;

[0013] The preparation steps are as follows:

[0014] S1, Weigh and mix the above raw materials evenly according to parts by weight, and add water to adjust them into a slurry with a solid - liquid ratio of 30 - 50%;

[0015] S2, After the flue gas is dust - removed by a multi - tube dust collector, it is sent into a rotary spray drying device at 180 - 300 °C;

[0016] S3, Adjust the flow direction of the flue gas flow entering the rotary spray drying device through a hot - air volute and a hot - air distributor to enhance the gas - liquid mixing ability;

[0017] S4, Feed the slurry into the rotary spray drying device, and use a rotary atomizer to spray it to form porous soil particles, while adsorbing part of the SOx and NOx contained in the flue gas.

[0018] Further, the fly ash in the weight ratio of the raw materials is replaced by coal gangue powder, and the component of the coal gangue powder is 60 - 85 parts.

[0019] Further, the liquid material obtained in step S1 is transported to the rotary atomizer by a screw pump, and the rotary atomizer sprays the liquid material into a mist by high - speed rotation.

[0020] Further, the dust - removed flue gas in step S2 is introduced into the rotary spray drying device, adjust the solid - liquid ratio to 30 - 50%, adjust the frequency of the rotary atomizer to 30 - 40 Hz and the pump speed to 20 - 40 rpm, and the equipment simultaneously completes drying and granulation to obtain spherical particles.

[0021] Further, in step S3, at the hot - air volute at the upper part of the rotary spray drying device, the hot air enters the rotary spray drying device tangentially along the hot - air volute. A plurality of independent hot - air distributors are arranged at the intersection of the straight pipe of the hot - air volute and the shell. By adjusting the hot - air distributors, part of the flue gas rotates along the barrel wall, and part of the flue gas is guided to the rotary atomizer to promote uniform gas - liquid mixing.

[0022] The present invention also provides a rotary spray drying device, which includes a flue gas inlet, a hot air distributor, a hot air volute, a rotary atomizer, a housing, a flue gas outlet and a discharging device. Among them, the hot air volute is installed at the upper part of the housing, the discharging device is installed at the lower part of the housing, the flue gas outlet is led out from the center of the middle part of the housing and the central opening in the housing is arranged downward; the flue gas inlet is tangentially communicated with the hot air volute, the hot air distributor is arranged at the junction of the flue gas inlet and the hot air volute, and the rotary atomizer is installed at the center of the top of the hot air volute.

[0023] The present invention also provides a system for utilizing the waste heat of flue gas and acid to produce porous soil improvement materials, which includes a stirring tank, a screw pump, a multi-tube dust collector, a bag filter, a fan and the above-mentioned rotary spray drying device. Among them, the outlet of the stirring tank is connected to the inlet of the screw pump, the outlet of the screw pump is connected to the rotary atomizer arranged in the rotary spray drying device, the outlet of the multi-tube dust collector is connected to the inlet of the rotary spray drying device, the outlet of the rotary spray drying device is connected to the inlet of the bag filter, the outlet of the bag filter is connected to the inlet of the fan, and the outlet of the fan is connected to the discharge port or the rear equipment.

[0024] Compared with the prior art, the advantages of the present invention are as follows: The method for utilizing the waste heat of flue gas and acid to produce porous soil improvement materials designed by the present invention aims at the problem of high preparation cost of porous materials, changes the idea of preparing porous materials based on the gelling principle in the traditional process, combines the rapid foaming and forming characteristics of the starch and ammonium sulfate mixture with the rapid production capacity of the rotary spray drying device, and realizes the rapid forming and foaming of the materials; develops a technical solution for coupling flue gas purification and waste heat utilization, realizes the preparation of products based on waste heat and recyclability through the recovery and reuse of flue gas waste heat, and reduces the energy cost. The present invention can reduce the preparation cost of porous materials, achieve energy conservation and emission reduction, and achieve the purpose of treating waste with waste. The present invention solves the problems in the preparation of porous materials such as high preparation cost, complex process, difficult low-temperature foaming, long curing time, large particle size of finished products, easy caking, and the need for re-crushing and screening when configuring improvement materials, and realizes the goal of preparing low-cost, high-efficiency, large-batch, and small-particle-size porous soil improvement materials. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the overall structure of the porous soil improvement material preparation system;

[0026] Figure 2 It is a top view of the rotary spray drying device;

[0027] Figure 3 It is a cross-sectional view of the rotary spray drying device.

[0028] Figure 4 It is a micrograph of the porous soil improvement material prepared by the present invention;

[0029] Figure 5 Macrosopic cross-sectional view of the porous soil improvement material prepared for the present invention;

[0030] Figure 6 Porous soil improvement materials prepared in batches for the present invention.

[0031] Among them, 1 - Rotary spray drying device, 2 - Stirring tank, 3 - Screw pump, 4 - Multi-tube dust collector, 5 - Bag filter, 6 - Fan, 7 - Raw materials, 8 - Products, 9 - Drain outlet, 10 - Flue gas, 11 - Flue gas inlet, 12 - Hot air distributor, 13 - Hot air volute, 14 - Rotary atomizer, 15 - Housing, 16 - Flue gas outlet, 17 - Discharging device. Detailed implementation manners

[0032] Hereinafter, for the convenience of those skilled in the art to understand the technical solution of the present invention, further description will be made with reference to the accompanying drawings. It should be understood that these descriptions are exemplary and not intended to limit the scope of the present invention.

[0033] In the following detailed description, for the purpose of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0034] Embodiment 1:

[0035] This embodiment is a method for preparing a porous soil improvement material by using the waste heat of flue gas as a heat source, fly ash or coal gangue as the main raw material, and a rotary spray drying device as the main equipment, and comprehensively and resourcefully utilizing the low-cost acid in the flue gas. It consists of the following steps, and the raw materials participating in the distribution include the following components in weight ratios:

[0036] Fly ash: 60 - 85 parts;

[0037] Starch: 5 - 10 parts;

[0038] Ammonium sulfate: 1 - 3 parts;

[0039] Quartz sand: 2 - 10 parts;

[0040] The preparation steps are as follows:

[0041] First step, weigh and mix the raw materials according to the weight parts, and add water to prepare a slurry with a solid-liquid ratio of 30 - 50%;

[0042] Second step, after the flue gas is dusted by a multi-tube dust collector, send it into the rotary spray drying device at 180 - 300 °C,

[0043] In the third step, adjust the flow direction of the flue gas after entering the rotary spray drying device through the hot air volute and the hot air distributor to enhance the gas-liquid mixing ability;

[0044] In the fourth step, introduce the slurry into the rotary spray drying device, spray it out by using a rotary atomizer, and adsorb part of the SOx and NOx in the flue gas while the particles are formed.

[0045] In specific implementation, the liquid material prepared according to the weight ratio of 80 parts of fly ash, 10 parts of starch, 3 parts of ammonium sulfate and 10 parts of quartz sand in step S1 is transported to the rotary atomizer by a screw pump. The rotary atomizer sprays the liquid material into a mist by high-speed rotation, increasing the gas-liquid heat exchange contact area, so as to quickly foam, dry and form the material in a short time.

[0046] In addition, in specific implementation, introduce the flue gas after dust removal in step S2 into the rotary spray drying device, adjust the solid-liquid ratio to 50%, adjust the frequency of the rotary atomizer to 40 Hz and the pump speed to 20 rpm. The device simultaneously completes drying and granulation to obtain spherical particles with a porosity of 48%.

[0047] In addition, in specific implementation, in step S3, at the hot air volute at the upper part of the rotary spray drying device, the hot air enters the rotary spray drying device tangentially along the volute. A plurality of independent hot air distributors are arranged at the intersection of the straight pipe of the volute and the cylinder body. By adjusting the hot air distributor, part of the flue gas rotates along the barrel wall, increasing the residence time of the hot flue gas in the device, improving the thermal energy utilization efficiency, and preventing the material from being directly sucked out by the outlet. Part of the flue gas is guided to the rotary atomizer to promote uniform gas-liquid mixing, disperse and preheat the droplets, increase the gas-liquid heat exchange area and efficiency, reduce the product particle size and increase the product output.

[0048] As Figures 4-6 shown, are the micrograph, the macroscopic cross-sectional view of the porous soil improvement material prepared by the present invention and the overall shape of the porous soil improvement material. As shown in the figure, the particle size of the porous soil improvement material designed by the present invention can achieve mass production.

[0049] In summary, the present invention addresses the problem of high preparation cost of porous materials, changes the traditional process idea of preparing porous materials based on the gelling principle, combines the rapid foaming and forming characteristics of the starch and ammonium sulfate mixture with the rapid production capacity of the rotary spray drying device to achieve rapid material forming and foaming; develops a flue gas purification coupled with waste heat utilization technical solution, and through the recovery and reuse of flue gas waste heat, realizes the preparation of products based on waste heat and recyclability, and reduces the energy cost. The present invention can reduce the preparation cost of porous materials, achieve energy conservation and emission reduction, and achieve the purpose of treating waste with waste. The present invention solves the problems in the preparation of porous materials such as high preparation cost, complex process, difficult low-temperature foaming, long curing time, large particle size of finished products, easy caking, and the need for re-crushing and screening when configuring improved materials, and realizes the goal of preparing low-cost, high-efficiency, large-batch, and small-particle-size porous soil improvement materials.

[0050] Example 2:

[0051] The difference between this example and the above example is that fly ash in the raw material weight ratio is replaced by coal gangue powder, and the component of the coal gangue powder is 60 - 85 parts. Specifically in implementation, it can be carried out according to the following steps:

[0052] First step, weigh 75 parts of coal gangue, 8 parts of starch, 2 parts of ammonium sulfate, and 5 parts of quartz sand by weight respectively, and mix them evenly;

[0053] Second step, add water to the materials in the first step and mix them evenly into a slurry, and adjust the solid-liquid ratio of the slurry to 30%;

[0054] Third step, pass the high-temperature flue gas through a dust removal device, and then introduce it into the rotary spray drying device;

[0055] Fourth step, the frequency of the rotary atomizer is 30 Hz, the pump speed is 35 rpm, use the rotary atomizer to spray out the slurry, and finally cool it naturally to room temperature, then the porous soil matrix material is obtained, and the porosity of the obtained material can reach 36%.

[0056] Other implementation steps are the same as those of the above Example 1, and will not be elaborated here.

[0057] Please refer to Figure 2 and 3 As shown, the present invention also provides a rotary spray drying device 1 for the above method of using flue gas waste heat and acid to prepare porous soil improvement materials. Specifically, as Figure 2 、 3As shown above, the rotary spray drying device includes a flue gas inlet 11, a hot air distributor 12, a hot air volute 13, a rotary atomizer 14, a housing 15, a flue gas outlet 16 and a discharging device 17. Among them, the hot air volute 13 is installed on the upper part of the housing 15, the discharging device 17 is installed on the lower part of the housing 15, the flue gas outlet 16 is led out from the center of the middle part of the housing 15, and the central opening in the housing 15 is arranged downward to lead out the flue gas, so as to prevent liquid droplets from being directly sucked into the flue gas outlet 16. The flue gas inlet 11 is tangentially communicated with the hot air volute 13, the hot air distributor 12 is arranged at the junction of the flue gas inlet 11 and the hot air volute 13, and the rotary atomizer 14 is installed at the center of the top of the hot air volute 13.

[0058] In summary, the rotary spray drying device 1 provided by the present invention has a simple structure, is convenient and efficient to use, solves the problems existing in traditional equipment in the preparation of porous materials, such as high preparation cost, complex process, difficult low-temperature foaming, long curing time, large particle size of finished products, easy caking, and the need for re-crushing and screening when configuring improved materials, and realizes the effect of preparing low-cost, high-efficiency, large-batch, and small-particle-size porous soil improvement materials.

[0059] In addition, as Figure 1 shown, based on the above method for using flue gas waste heat and acid to produce porous soil improvement materials, the present invention also provides a system for using flue gas waste heat and acid to produce porous soil improvement materials, which mainly includes a stirring tank 2, a screw pump 3, a multi-tube dust collector 4, a bag filter 5, a fan 6 and the above-mentioned rotary spray drying device 1. Among them, the outlet of the stirring tank 2 is connected to the inlet of the screw pump 3, the outlet of the screw pump 3 is connected to the rotary atomizer 14 arranged in the rotary spray drying device 1, the outlet of the multi-tube dust collector 4 is connected to the inlet of the rotary spray drying device 1, the outlet of the rotary spray drying device 1 is connected to the inlet of the bag filter 5, the outlet of the bag filter 5 is connected to the inlet of the fan 6, and the outlet of the fan 6 is connected to the discharge port or the rear equipment.

[0060] The following is the working process of this system:

[0061] The raw materials 7 are mixed evenly according to the formula and then water is added in the stirring tank 2 to prepare a slurry, which is pressurized and transported to the rotary atomizer 14 in the rotary spray drying device 1 through the screw pump 3 for atomization. The flue gas 10 passes through the multi-tube dust collector 4 for dust removal and then enters the rotary spray drying device 1. The flue gas enters from the flue gas inlet 11, and after the flue gas flow direction is adjusted by the hot air distributor 12, it enters the hot air volute 13 and is evenly mixed, quickly foamed, dried and formed with the atomized slurry sprayed by the rotary atomizer 14. The product 8 flows into the lower conical part along the housing 15 and is discharged from the discharging device 17. The flue gas is led out from the flue gas outlet 16 and enters the bag filter 5 to collect the product 8 with a smaller aerodynamic equivalent diameter in the flue gas, and then is sent to the discharge port 9 through the fan 6 for discharge. The dust collected by the multi-tube dust collector 4 can be used as an ingredient of the raw materials 7.

[0062] In summary, the system for utilizing flue gas waste heat and acidic materials to produce porous soil improvement materials provided by the present invention addresses the problem of high preparation costs of porous materials. By changing the traditional approach of preparing porous materials based on the gelling principle, and combining the rapid foaming and forming characteristics of the starch and ammonium sulfate mixture with the rapid production capacity of the rotary spray drying device, rapid material forming and foaming are achieved. A technical solution for coupling flue gas purification and waste heat utilization is developed. Through the recovery and utilization of flue gas waste heat, product preparation based on waste heat is realized, reducing energy costs. Through the present invention, the preparation cost of porous materials can be reduced, energy conservation and emissions reduction can be achieved, and the goal of treating waste with waste can be attained.

[0063] The embodiments described above are merely for describing the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. Method for preparing porous soil improvement material by utilizing waste heat of flue gas and acidity, Characterized in that, The raw materials include the following components in parts by weight: Fly ash: 60 - 85 parts; Starch: 5 - 10 parts; Ammonium sulfate: 1 - 3 parts; Quartz sand: 2 - 10 parts; The preparation steps are as follows: S1 Weigh and mix the above raw materials evenly, and add water to adjust them into a slurry with a solid - liquid ratio of 30 - 50%; S2 After the flue gas is dust - removed by a multi - tube dust collector, it is sent into a rotary spray drying device at 180 - 300 °C. The rotary spray drying device includes a flue gas inlet, a hot air distributor, a hot air volute, a rotary atomizer, a housing, a flue gas outlet and a discharging device. Among them, the hot air volute is installed at the upper part of the housing, the discharging device is installed at the lower part of the housing, the flue gas outlet is led out from the center of the middle part of the housing, and the central opening in the housing is set downward; the flue gas inlet is tangentially connected to the hot air volute, the hot air distributor is arranged at the junction of the flue gas inlet and the hot air volute, and the rotary atomizer is installed at the center of the top of the hot air volute; S3 Adjust the flow direction of the flue gas flow entering the rotary spray drying device through the hot air volute and the hot air distributor to enhance the gas - liquid mixing ability; S4 feeds the slurry into a rotary spray drying device, and uses a rotary atomizer to spray and form porous soil particles, while adsorbing part of the SO x and NO x contained in the flue gas.

2. The method for preparing porous soil improvement material by utilizing waste heat of flue gas and acidity according to claim 1, Characterized in that, The fly ash in the weight ratio of the raw materials is replaced by coal gangue powder, and the component of the coal gangue powder is 60 - 85 parts.

3. The method for preparing porous soil improvement material by utilizing waste heat of flue gas and acidity according to claim 1 or 2, Characterized in that, The liquid material obtained in step S1 is transported to the rotary atomizer by a screw pump, and the rotary atomizer sprays the liquid material into a mist by high - speed rotation.

4. The method for preparing porous soil improvement material by utilizing waste heat of flue gas and acidity according to claim 3, Characterized in that, The dust - removed flue gas in step S2 is introduced into the rotary spray drying device, the solid - liquid ratio is adjusted to 30 - 50%, the frequency of the rotary atomizer is adjusted to 30 - 40 Hz, and the pump speed is adjusted to 20 - 40 rpm. The equipment simultaneously completes drying and granulation to obtain spherical particles.

5. The method for preparing porous soil improvement material by utilizing waste heat of flue gas and acidity according to claim 4, Characterized in that, In step S3, at the hot air volute at the upper part of the rotary spray drying device, the hot air enters the rotary spray drying device tangentially along the hot air volute. A plurality of independent hot air distributors are arranged at the intersection of the straight pipe of the hot air volute and the housing. By adjusting the hot air distributors, part of the flue gas rotates along the barrel wall, and part of the flue gas is guided to the rotary atomizer to promote uniform gas - liquid mixing.

6. A system for preparing porous soil improvement material by utilizing waste heat of flue gas and acidity, Characterized in that, It includes a stirring tank, a screw pump, a multi-tube dust collector, a bag filter, a fan, and the rotary spray drying device described in claim 1. Among them, the outlet of the stirring tank is connected to the inlet of the screw pump, the outlet of the screw pump is connected to the rotary atomizer provided in the rotary spray drying device, the outlet of the multi-tube dust collector is connected to the inlet of the rotary spray drying device, the outlet of the rotary spray drying device is connected to the inlet of the bag filter, the outlet of the bag filter is connected to the inlet of the fan, and the outlet of the fan is connected to the discharge port or the rear equipment.

Images