CN102992335B - Industrial production device and method for producing nanometer SiO2 rice hull ash - Google Patents

Abstract

The invention discloses an industrialized production device for preparing nano-silica rice husk ash and a method for using the same, including a fluidized bed boiler, a cyclone separator, a heat exchanger and a bag dust collector. The design of the fluidized bed boiler adopts The characteristics of variable cross-section furnace, segmented temperature control and air distribution, secondary air system, and increased dilute phase area. The operating temperature of the fluidized bed boiler is 670°C-720°C, the operating wind speed is 0.9-1.4m/s, and the excess air coefficient is 1.16-1.21. The invention not only can effectively utilize the energy of the rice husk itself for heating, improves the thermal efficiency of the boiler, saves energy, but also can prepare high-purity nano-structure SiO2 rice husk ash to ensure stable reaction conditions. After inspection, the prepared rice husk ash contains more than 90% amorphous high-purity SiO2, and its form is nanometer particles of 15-30nm.

Description

Industrialized production device for preparing nano-silica rice husk ash and its application method

technical field

The invention relates to the preparation of nano-structured _SiO2 rice husk ash, in particular to an industrialized production device of nano-structured _SiO2 rice husk ash and a method for using the same.

Background technique

my country's annual rice output is about 200 million tons, accounting for 1/3 of the world's total output, ranking first in the world. Rice husk is a by-product of rice processing, accounting for about 20% of the weight of rice grains, and produces about 40 million tons of rice husk every year, which is a huge resource. A large number of rice husk resources have not been fully utilized. In rural areas, field burning is the main treatment method, which pollutes the environment and wastes energy. In recent years, studies have shown that rice husk ash contains about 20% amorphous SiO ₂ , which has high activity and is an additive to building materials. After purification, it can be used as industrial basic raw materials such as fine ceramics, optical fibers and solar cells. High added value. Therefore, the process of utilizing the energy of rice husks and industrially producing amorphous high-purity SiO ₂ urgently needs to be improved and perfected.

The invention patent of application number 93116790.6 "the device for producing active rice husk ash" introduces the method of preparing rice husk ash by intermittent incineration device, but this technology has the following disadvantages: 1. It cannot feed continuously, and the two-step method is complicated to operate. It is beneficial to the promotion of industrialization; 2. The energy of the rice husk itself is not fully utilized, resulting in energy waste. The invention patent of application number 200410026459.5 "a rice husk incineration device and its output nano-structure SiO2 rice husk ash" uses a closed rice husk incineration device to prepare nano-structure SiO2 rice husk ash. The heat released by burning rice husks is limited by the closed incineration device, which cannot continuously feed materials, and it is difficult to solve problems such as industrialization promotion. Publication No. 102252325A "Circulating Fluidized Bed Boiler Combusting Rice Husk" aims at combustion for power generation, and does not involve the preparation process of rice husk ash.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, to provide a device that can industrially produce high-purity nanostructure SiO ₂ rice husk ash and its use method, and can effectively utilize the heat energy produced by rice husk incineration.

The present invention is realized through the following technical solutions.

An industrial production device for preparing nano-silica rice husk ash, comprising a boiler, a feeder, a separator and a dust collector, characterized in that the boiler is a fluidized-bed boiler with a variable-section furnace, and the fluidized-bed boiler The upper part of the hearth of 6 is provided with a dilute-phase area 18, and the diameter of the dilute-phase area is 920 mm; the lower part of the furnace is provided with a dense-phase area 17, and the diameter of the dense-phase area is 620 mm; The included angle is 12.5°; the total height of the fluidized bed boiler 6 is 6m; a cooling water jacket A4 and a cooling water jacket B20 are respectively installed in the dense phase area and the variable section area, and the height of each cooling water jacket is 400~ 500mm, the two cooling water jackets communicate with each other; the bottom part of the boiler is provided with a combustion chamber 16, and the ignition device 1, the primary air inlet (2) and the ash hopper A11 are arranged below the combustion chamber 16; the combustion chamber 16 and the dense phase area 17 is provided with an air distribution plate 15, one side of the dense-phase area 17 is provided with a screw feeder 3, a secondary air inlet 5 is provided in the variable cross-section area 19, and a primary cyclone separator is arranged in turn at the outlet of the boiler furnace 7. Secondary cyclone separator 8, heat exchanger 9 and bag filter 10; ash hopper B12 and ash hopper C13 are respectively arranged at the bottom of primary cyclone separator 7, secondary cyclone separator 8 and bag filter 10 and ash hopper D14.

The furnace lining of the fluidized bed boiler 6 is made of anti-corrosion refractory material.

The method for using an industrialized production device for preparing nano-silica rice husk ash has the following steps:

(1) Put in the quartz sand with a particle size of 0.6mm through the screw feeder 3 to form a quartz sand bed, the height of the material layer is 400-600mm, pass through the primary air, and heat up to 400°C at a heating rate of 5°C/min;

(2) Start the ignition device 1, and the screw feeder 3 will continue to supply the rice husk; after the ignition is successful, cut off the power supply, maintain the required temperature with the heat of rice husk combustion, adjust the secondary air supply to ensure the combustion efficiency, and cool it with circulation Water controls the temperature of the dense-phase zone 17 and the variable cross-section zone 19 in the furnace; the operating temperature of the fluidized bed boiler is 670°C-720°C, the operating wind speed is 0.9-1.4m/s, and the excess air coefficient is 1.16-1.21;

(3) The flue gas after rice husk combustion carries the burnt rice husk ash through the dense phase zone 17, the variable cross section zone 19 and the dilute phase zone 18 and enters the primary cyclone separator 7, the secondary cyclone separator 8, and the heat exchanger 9 And the bag filter 10, the rice husk ash is collected by the ash hopper A11 at the bottom of the furnace and the two-stage cyclone separator and the ash hopper B12, C13 and D14 at the bottom of the bag filter;

(4) The hot flue gas is cooled by the heat exchanger 9, and then discharged from the chimney after desulfurization treatment, and the waste heat is reused.

The step (1) is to raise the temperature to 400° C. by means of electric heating.

The preferred excess air ratio of the step (2) is 1.18.

The rice husk ash collected in the step (3) contains more than 90% of amorphous high-purity SiO ₂ , which is in the form of nanoparticles of 15-30 nm.

Compared with the prior art, the present invention has remarkable effects as follows:

The industrialized production device for preparing nano-silica rice husk ash of the present invention improves the thermal efficiency of the boiler and solves the problem of limited accumulation volume of rice husk due to the design of a variable-section boiler and the introduction of secondary air. Due to the addition of a secondary cyclone separator, the rice husk is fully burned and separated completely, and high-purity nanostructure _SiO2 rice husk ash is prepared; at the same time, due to the use of cooling water jacket and heat exchanger, the incineration temperature of the boiler can be effectively controlled , to ensure stable reaction conditions, and at the same time, this part of waste heat can be fully utilized, such as heating, hot water supply, steam power generation, etc., saving a lot of energy.

Description of drawings

Fig. 1 is nanostructure _SiO of the present invention The structural representation of rice husk ash production device;

Fig. 2 is the structural perspective view (SEM) of the rice husk ash prepared by the present invention;

Fig. 3 is a perspective view (TEM) of the honeycomb structure of rice husk ash prepared by the present invention.

The reference signs of the present invention are as follows:

1———ignition device 2———primary air inlet

3———Screw feeder 4———Cooling water jacket A

Detailed ways

The present invention adopts conventional production equipment and preparation technology, and the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the structural representation of nanostructure _SiO2 rice husk ash production device of the present invention. As shown in Figure 1, the boiler of the present invention is a fluidized-bed boiler 6 with a variable-section furnace. The upper part of the fluidized-bed boiler 6 is provided with a dilute-phase zone 18, and the diameter of the dilute-phase zone is 920mm; the lower part of the furnace is provided with a dense-phase Zone 17, the diameter of the dense-phase zone is 620mm; the middle part of the furnace is provided with a variable cross-section zone 19, and the vertical angle of the variable cross-section zone 19 is 12.5°; the total height of the fluidized bed boiler 6 is 6m, and the furnace lining is made of anti-corrosion refractory materials ; A cooling water jacket A4 and a cooling water jacket B20 are respectively installed in the dense phase area and the variable section area. The height of each cooling water jacket is 400-500mm, and the two cooling water jackets are connected to each other; There is a combustion chamber 16, and an ignition device 1, a primary air inlet 2, and an ash hopper A11 are arranged under the combustion chamber 16; an air distribution plate 15 is arranged at the connection between the combustion chamber 16 and the dense phase area 17, and one side of the dense phase area 17 A screw feeder 3 is provided, a secondary air inlet 5 is provided in the variable cross-section area 19, and a primary cyclone separator 7, a secondary cyclone separator 8, a heat exchanger 9 and a bag filter 10 are sequentially provided at the outlet of the boiler furnace ; At the bottom of the primary cyclone separator 7, the secondary cyclone separator 8 and the bag filter 10, there are ash hoppers B12, ash hoppers C13 and ash hoppers D14 respectively.

The working principle of the present invention is as follows: the quartz sand bed material with a particle diameter of 0.6mm is placed at the bottom of the fluidized bed boiler 6, and the height is 400-600mm. The primary air 2 is turned on, and the air entering the furnace is uniformly distributed through the air distribution plate 15 so that the bed layer reaches a microfluidization state. When the temperature is raised to 400°C at a heating rate of 5°C/min, start the ignition device 1 under the bed, use light diesel oil to ignite, and feed a small amount of rice husks into the fluidized bed boiler 6 through the screw feeder 3, and increase the air volume (250m ³ /h) Make the bed reach a stable fluidized state. When the bed temperature reaches 600°C, increase the feed rate of the feeder, and at the same time turn off the ignition device 1 under the bed, and adjust the air volume, cooling water volume and feed rate according to the bed temperature change. Feed amount. Adjust the feed rate and the cooling water flow rate of the cooling water jacket 4 to stabilize the bed temperature at a suitable working condition (670°C-720°C), put in the secondary air 5, and the actual operating wind speed is 0.9-1.4m/s. The rice husk burns volatiles in the dense phase area, releasing a large amount of heat, and goes to the dilute phase area for further combustion with the flue gas. The high temperature flue gas generated after combustion passes through the primary cyclone separator 7, the secondary cyclone separator 8, and the heat exchanger. 9 and bag dust collector 10, the flue gas after cooling down is discharged from the chimney after desulfurization and other treatments meet the national emission standards. The rice husk ash is collected in the ash hopper 11-14 at the bottom of the furnace, cyclone separator and bag filter. The hot flue gas is cooled after passing through the heat exchanger, and its heat is used to supply hot water for the factory building and nearby residential areas, and can also be used for hot steam or power generation.

The rice husk ash prepared by the present invention is determined, and its chemical composition SiO ₂ content is all higher than 90%, the highest can reach 97.1%, the amount of residual carbon is lower than 2%, and the combustion efficiency of the boiler reaches more than 93%. The X-ray diffraction pattern shows that there is no obvious diffraction peak of crystalline SiO ₂ , which indicates that SiO ₂ in the prepared rice husk ash exists in an amorphous state. Using SEM technology (Figure 2) to observe the inner and outer surfaces and cross-sections of the rice husk ash prepared by the present invention, it shows that the structure is compact, and it can be clearly observed that the inner surface is thin, the network structure is denser, the channels are rich and clearly visible, and the outer surface is slightly Thick, coarse structure, undeveloped channels; between the inner and outer surfaces is an interlayer, the interlayer is composed of criss-cross plates, in a loose honeycomb shape, containing a large number of holes, the size of these holes is about 10 μm. When using TEM technology (Figure 3) to zoom in and observe, it is found that a large number of extremely fine particles piled together are arranged in a honeycomb shape, and the particle size is about 15-30nm. These nano-scale _SiO2 particles and micron-scale pores make rice husk ash have a large specific surface area and high activity, which is suitable for special application requirements.

Claims (6)

1. An industrialized production device for preparing nano-silica rice husk ash, comprising a boiler, a feeder, a separator and a deduster, characterized in that, the boiler is a fluidized-bed boiler of a variable-section furnace, and the fluidized The upper part of the furnace of the bed boiler (6) is provided with a dilute-phase zone (18) with a diameter of 920 mm; the lower part of the furnace is provided with a dense-phase zone (17) with a diameter of 620 mm; the middle part of the furnace is provided with a variable cross-section zone ( 19), the vertical angle of the variable section area (19) is 12.5°; the total height of the fluidized bed boiler (6) is 6m; a cooling water jacket A (4) and Cooling water jacket B (20), the height of each cooling water jacket is 400-500mm, and the two cooling water jackets are connected to each other; the bottom part of the boiler is provided with a combustion chamber (16), and the bottom of the combustion chamber (16) An ignition device (1), primary air inlet (2) and ash hopper A (11) are provided; an air distribution plate (15) is provided at the junction of the combustion chamber (16) and the dense phase area (17), and the dense phase area ( 17) is provided with a screw feeder (3) on one side, a secondary air inlet (5) is provided in the variable cross-section area (19), and a primary cyclone separator (7) and a secondary cyclone are provided in turn at the outlet of the boiler furnace. Separator (8), heat exchanger (9) and bag filter (10); at the bottom of the primary cyclone separator (7), secondary cyclone separator (8) and bag filter (10) respectively set Ash hopper B (12), ash hopper C (13) and ash hopper D (14). 2. The industrial production device for preparing nano-silica rice husk ash according to claim 1, characterized in that the furnace lining of the fluidized bed boiler (6) is made of anti-corrosion refractory material. 3. the using method of the industrialized production device preparing the nano-silica rice husk ash of claim 1 has the following steps: (1) Put in quartz sand with a particle size of 0.6mm through the screw feeder (3) to form a quartz sand bed, with a material layer height of 400-600mm, pass through the primary air, and heat up to 400 at a heating rate of 5°C/min ℃; (2) Start the ignition device (1), and the screw feeder (3) will continue to supply rice husks; after the ignition is successful, cut off the power supply, maintain the required temperature with the heat of rice husk combustion, and adjust the secondary air supply to ensure combustion efficiency. The temperature of the dense-phase zone (17) and the variable cross-section zone (19) in the furnace is controlled by circulating cooling water; the operating temperature of the fluidized bed boiler is 670°C-720°C, the operating wind speed is 0.9-1.4m/s, and the excess air coefficient 1.16~1.21; (3) The flue gas after rice husk combustion carries the burnt rice husk ash through the dense phase area (17), the variable cross-section area (19) and the dilute phase area (18) and enters the primary cyclone separator (7), the secondary cyclone Separator (8), heat exchanger (9) and bag filter (10), rice husk ash passes through the ash hopper A (11) at the bottom of the furnace and the two-stage cyclone separator and the ash hopper B (12) at the bottom of the bag filter ), ash hopper C (13) and ash hopper D (14) for collection; (4) The hot flue gas is cooled by the heat exchanger (9), and then discharged from the chimney after desulfurization treatment, and the waste heat is reused. 4. The method for using an industrial production device for preparing nano-silica rice husk ash according to claim 3, characterized in that the step (1) is to raise the temperature to 400° C. by means of electric heating. 5. The method for using an industrial production device for preparing nano-silica rice husk ash according to claim 3, characterized in that the preferred excess air coefficient in the step (2) is 1.18. 6. The method for using an industrial production device for preparing nano-silica rice husk ash according to claim 3, wherein the rice husk ash collected in the step (3) contains more than 90% amorphous high-purity SiO ₂ , Its morphology is nanoparticles of 15-30nm.

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