RU2163708C1 - Installation for rice hull preliminary burning - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: installation is used for production of silicon dioxide. Installation has heating chamber 1 with door 2, burning tank 3 with cover 4, shaft 5, mixing blades 6, grinding rolls 7, and levers 8. Shaft 5 is driven to rotation. Rice hull is loaded through loading device 17. Heating chamber is heated up to temperature of 300-500 C. Burning of rice hull is performed till emission of smoke is stopped completely. Heating is stopped and burned and ground rice hull is unloaded into takeup bunker 21. Burned hull contains iron oxide, not more than 0.05% and carbon black, 5-7% of initial mass of hull. EFFECT: higher efficiency. 5 cl, 2 dwg

Description

 The invention relates to the field of processing of rice husk into silicon dioxide and can be used for heat treatment of bulk materials.

The technological requirements for the equipment for the preliminary firing of rice husks are as follows: the possibility of mixing and grinding at a process temperature of 300-500 ^o C, the removal and utilization of the resulting smoke, the prevention of the introduction of metal oxides from equipment parts into the processed husk, high productivity.

 There is no specialized equipment for pre-firing rice husks. Using existing equipment for heat treatment of bulk materials is inefficient and environmentally friendly.

 A known apparatus for heat treatment of granular material (see A.S. 4876459/33 5 F 27 B 15/00 from 10.23.90), containing a heating chamber and screw conveyors, loading and unloading devices.

 The use of this apparatus is not environmentally friendly, since there are no devices for trapping exhaust gases and soot; a significant amount of iron oxides is rubbed from screw conveyors (up to 0.1-0.2%); alteration of the heating device is required to raise the temperature to the necessary; the use of this apparatus is not economical and inefficient for the firing process, since there is no possibility of simultaneous grinding.

 A drum dryer is known (see A. p. 4857687/06 5 F 26 B 11/04 of 07/10/90) with a rotating body and the possibility of grinding the dried material with gears.

The use of this apparatus for the heat treatment of rice husk requires additional alteration of the heating device in order to increase the operating temperature to 300-500 ^o C, as well as the additional manufacture of smoke removal device; the gears grinding the processed raw materials, when the temperature rises to 300-500 ^o C and due to intense friction between themselves bring a significant amount (up to 0.5-1.0%) of iron oxides in the processed product.

 Known thermo-radiation rotary dryer (see RF patent 2053471 6 F 26 B 17/22, application 50468181/13 of 03/03/92), containing a housing with a cover, means for feeding and discharging the product, a zone heating device with gas burners, agitators plunger type and profiled elements for grinding the processed product.

The disadvantages of the described dryer is that the heating is carried out by burning gas (this introduces undesirable additional impurities CO, CO ₂ , soot into the smoke and into the product), and grinding of the finished product at the end of the drying cycle.

The aim of this invention is to provide a device that allows heat treatment of rice husk at 300-500 ^o C with minimal pollution with metal oxides, with the possibility of simultaneous grinding (in order to intensify the firing process and smoke), with the possibility of trapping soot and neutralizing, utilizing the resulting gases containing CO, CO ₂ , organic acids, aldehydes.

 This goal is achieved by the fact that the firing tank with a lid is placed in the heating chamber and the gases formed are aspirated, passing them through a dry soot filter collector and through water in a settling tank, in which the substances remaining in the smoke are dissolved; levers with mixing blades fixed to them additionally have grinding rolls that are made of heat-resistant and heavy alloys (for example, hard alloys of the VK4, VK6, VK8 type) that roll along the wall of the calcining vessel; in order to have a minimum number of rotating, rubbing parts, the loading device is made on the principle of gravity, and the discharge device is on the principle of vacuum suction.

 During the firing process, the rice husk is embrittled and easily milled even under the influence of the gravity of the rolls.

 In FIG. 1 shows a diagram of the installation, which consists of a heating chamber 1 with a door 2, a firing tank 3 with a cover 4, a shaft 5, mixing blades 6, grinding rolls 7, levers 8 (see Fig. 2), exhaust pipe 9, valve exhaust pipe 10, coarse smoke filter 11, soot filter collector 12, pump 13, sedimentation tank with water 14, longitudinally movable gear 15, axle shafts 16, loading nozzle 17, loading nozzle valve 18, discharge nozzle 19, nozzle valve unloading 20, hopper receiving 21, discharge valve b Uncker receiving 22, vacuum pump 23, valve of the vacuum pump 24.

The principle of operation of the installation is as follows. The vacuum pump 23 is turned off, the valves of the vacuum pump 24, the discharge hopper 22, the discharge pipe 20 are closed, rotate the shaft 5 from the gearbox 15 using the axle shaft 16, fill in the required amount of rice husk through the loading device 17, 18, turn on the heating of the heating chamber 1, when the temperature reaches 200-220 ^o C turn on the pump 13, raise the temperature to 400 ± 10 ^o C and carry out firing until the smoke ceases completely, turn off the heat, after 3-4 minutes stop the mixing process, turn off the pump 13, close the valves 10 on p smoke outlet, loading 18, using a vacuum pump 23, create a vacuum in the hopper by the receiver 21, close the valve of the vacuum pump 24, turn off the pump 23, open the valve of the discharge pipe 20 and burnt and crushed husk moves to the receiving hopper 21.

 The result is a burnt husk with an iron oxide content of not more than 0.05% and soot in an amount of 5-7% of the initial husk mass.

Claims (5)

 1. Installation of pre-firing rice husks, including a heating chamber with a door, a firing vessel body with a lid, containing a longitudinal rotating shaft with levers and mixing blades, a torque transmission device to the shaft, loading and unloading nozzles, grinding devices mounted on the levers holding mixing blades, in front of the mixing blades.  2. Installation according to claim 1, characterized in that the grinding device is made in the form of rolls installed with the possibility of rotation and rolling along the body of the firing tank.  3. Installation according to claim 2, characterized in that the rolls are made of heat-resistant and heavy material, for example, from hard alloys of the VK4, VK6, VK8 type.  4. The installation according to claim 1, characterized in that it further comprises a device for exhausting smoke, sedimentation of soot from the smoke and a sump tank with water for passing gases through the water.  5. Installation according to claim 1, characterized in that the device for transmitting torque from the gearbox to the shaft is made in the form of a removable axis passing through the door of the heating chamber, and the gearbox is made with the ability to move in the longitudinal direction.

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