RU2217241C2 - Device for separation of solid particles from gas flow - Google Patents

Abstract

FIELD: separation of solid particles from gas flows; metallurgy; chemical industry; construction engineering; de-dusting of gases for classification of poly-dispersed materials by sizes. SUBSTANCE: proposed device has bent gas duct with gas flow inlet and outlet branch pipes and bin for receiving solid particles; device has housing bent over radius with pipe placed inside it; axis of this pipe is parallel to axis of housing and is shifted towards gas flow inlet branch pipe; pipe has slotted hole; gas flow outlet branch pipe is connected with end of pipe. Ratio of area of pipe section to sectional area of slotted hole is equal to or is lesser than one. Slotted hole is provided with baffle plate mounted on pipe; width of this baffle plate is more than radius of pipe and is lesser than radius of housing. Ratio of sectional area of gas flow inlet branch pipe to sectional area of bin inlet hole is equal to 1: (2-12). EFFECT: reduced overall dimensions ; simplified construction; ease in maintenance. 3 cl, 2 dwg

Description

 The invention relates to equipment for separating solid particles from a gas stream in the metallurgical, chemical, construction industries and can be used for dust removal of gases, as well as for classification by size of polydisperse materials.

 The GDR patent 208304 of 05/02/1984 is known, which describes a device for heating or cooling fine-grained material while simultaneously extracting material from a gas stream, having an inlet channel tangentially connected to a conical or cylindrical part of the heat exchanger. The lower part of the heat exchanger extends into the separator, the upper part of which is cylindrical, and the lower part is conical in shape. An outlet channel is tangentially placed on the cylindrical part.

 The disadvantages of the device are low productivity due to the large increase in resistance when a dusty gas stream passes through it; a sufficiently rigid structure, requiring the mandatory installation of expansion joints; relatively low efficiency; inability to provide a classification of captured particles by their size.

 According to British patent 2079190 dated 07/07/1980, an apparatus for separating solid particles from a gaseous medium is known, comprising a cyclone, the lower part of which has the shape of a tapered hopper tapering downward, forming a lower collecting chamber and having an outlet connected to the discharge pipe through a valve. The intermediate part of the cyclone has the shape of a cylinder and is tangentially connected to the inlet pipe. The upper part has the shape of a truncated cone. The gas outlet pipe passes coaxially through the upper wall. At the upper end of the upper part there are two diametrically opposite capture chambers located tangentially. Solids moving with gases in spirals are discharged through channels with valves. Most of the particles descend in spirals, pressing against the cylindrical and conical walls by centrifugal forces, into the lower region of the apparatus and are discharged through a pipe with a valve.

The disadvantages of the design of the apparatus and its operational qualities include:
- the design due to countercurrent movement of gas and solid particles allows the formation of harmful vortices, contributing to an increase in the resistance of the apparatus and a decrease in the degree of particle capture;
- the bulkiness of the structure when using large unit capacity on the units due to the limited (5 m / s) gas velocity per section of the apparatus, which entails an increase in capital costs during construction;
- the inability to operate on hot gases without the use of a system of compensators for thermal extensions.

 A device for separating solid particles from a gas stream is a patent of the Russian Federation 2126723 from 07/08/97, made in the form of a curved part of the duct with a nozzle for outputting separated solid particles on the outer surface of the curved part of the duct and protrusions in front of this nozzle on the inner surface of the curved part of the duct . The curved part of the duct has one turn and is in the same plane, creating a field of action of centrifugal forces on solid particles in the gas stream. The ledges made on the inner surface of the flue press solid particles to the outer surface of the flue, which are discharged through a pipe to output the separated solid particles.

 This patent is taken as a prototype.

The disadvantages of its design include:
- the bulkiness of the structure, when using large unit power on the units due to the large values of the radius of curvature of the curved part of the duct;
- increasing the overall dimensions of devices using the principle of separation of gas and solid phases due to centrifugal forces, reduces the efficiency of their dust collection and contributes to the growth of their resistance;
- the device has a limitation of the radius of curvature of the curved part of the duct - not more than four nominal diameters of the duct, because further, the dimensions of the device and the capital costs of its construction increase;
- difficulty of access for internal inspection and repair without reducing its efficiency.

 An object of the invention is to reduce the size of the device, which has a simple design, accessibility for maintenance and operation.

 The technical result is achieved by the fact that a device including a gas duct in the form of an outer casing, bent along the radius, with a nozzle for introducing a gas stream, a pipe with a slit-like hole placed inside the casing, the axis of which is parallel to the axis of the casing, a receiving hopper for solid particles, a nozzle for output the gas stream connected to the end of the pipe is made so that the axis of the pipe is shifted towards the pipe for introducing the gas stream, while the cross-sectional area of the pipe for introducing the gas stream refers to the cross-sectional area of the inlet ment of the hopper for particulate matter at the point of connection to the lower housing part 1: (2-12).

 The ratio of the cross-sectional area of the pipe to the cross-sectional area of the slit-like opening is equal to or less than unity.

 The slit-like hole is provided with a visor mounted on the pipe, while the width of the visor is greater than the radius of the pipe and less than the radius of the housing.

 The cross-sectional area of the pipe for introducing gas flow refers to the cross-sectional area of the inlet of the hopper for solid particles at its junction with the lower part of the housing as 1: (2-12).

 Figure 1 shows the device in the form of a bent in one turn of the duct; figure 2 is a view along arrow A.

 The inventive device consists of a pipe 1 having ledges 2, a gas duct 3, a pipe 4 with a slit-like hole 5, mounted on the pipe 4 of the visor 6, located under the gas duct 3 of the receiving hopper 7 with the shut-off device 8. The pipe 4 has pipes 9 and 10.

 The claimed device operates as follows.

 In the inlet pipe 1 of the device direct a gas stream with suspended solids in it, for example gases from calcination furnaces in alumina production.

 By the ramp-like ledges 2, the gas stream is thrown to the outer wall of the duct bent along the radius of the casing 3. When a gas-dust stream passes through a bent section under the action of centrifugal forces, solid particles and gas flow separate.

 The dust-free gas stream through the slit-like opening 5 enters the pipe 4 and is directed through the pipes 9 and 10 for subsequent cleaning. Visor 6 helps to reduce the breakthrough of dust particles with exhaust gases.

 Dust particles through the hopper 7 with the locking device 8 are supplied for further processing or in the capacity of a commercial product.

 The radius of curvature of the curved part of the outer casing of the duct does not depend on the nominal diameter of the duct, but is determined only by the diameter of the pipe to remove dust-free flow and the gap between two curved surfaces in one turn: the inner surface is pipe 4 for removing dust-free flow and the outer surface is pipe 1 for input gas flow with solid particles and a curved duct 3.

 Another parameter of the gas duct - its length is determined by the optimal design, in which the process of separation of solid and gas phases is guaranteed to be completed with high efficiency at gas flow rates in the range of 2-16 m / s, depending on the particle size distribution of solid particles and their concentration in the gas stream.

 On this way, in one turn, at the optimal gas flow rate, solid particles have time to be pressed against the inner surface of the outer duct bent into one turn, curved into one turn, which is necessary to discharge them through the receiving hopper 7 with shut-off element 8 for unloading.

 Inside the curved part of the duct is a pipe 4 for output dust free gas flow. The pipe has a slit-like opening 5 along its entire length for introducing a dust-free gas stream. The area of the slit-like opening 5 is equal to or greater than the cross-sectional area of the pipe 4 for the output of dust-free gas flow. At the same time, a constant gas flow rate is maintained or, if the design of the device allows, the speed decreases, which accordingly reduces the resistance of the system and energy consumption.

 If the area of the slit-like opening 5 is less than the cross-sectional area of the pipe 4 for removing dust free gas flow, then with increasing gas velocity in the hole, the hydraulic resistance of the system and energy consumption will increase.

 The hole in the pipe 4 for the output of dust-free gas stream is located in its lower part so as to increase the angle of rotation of the gas stream, and therefore, increase the efficiency of separation of solid and gas phases.

 To accelerate the separation of solid particles from the gas stream and pressing the particles to the outer surface of the duct body, ramps 2 can be installed: the first - along the direction of the gas flow at the entrance to the duct, and the second - at the beginning of the bend of the duct.

 To increase the efficiency of separation of solid and gas phases on the pipe 4 for output dedusted gas flow in front of the slit-like opening 5, a visor 6 is installed.

 The visor 6 reduces the likelihood of a breakthrough of solid particles with gases and helps to change the direction of the particles moving in the gas stream. Visor 6 is a barrier that a particle moving by inertia along the radius of curvature cannot overcome. This increases the efficiency of dust cleaning. When the width of the visor 6 is less than the radius of the pipe 4, the opening 5 does not completely overlap, which does not provide sufficient protection against the breakthrough of particles. When the width of the visor 6 is greater than the radius of curvature of the gas duct 3, the resistance of the system increases, especially if the distance between the edge of the visor 6 and the opposite wall of the gas duct is less than the gap of the slit-like opening 5 in the pipe 4 for the removal of dust-free gas flow.

 The pipe 4 for output of dust-free gas flow has one or two nozzles 9 and 10 for output of this stream, connected to the ends of the pipe 4.

 The ratio of the cross-sectional area of the pipe 1 for introducing gas flow to the cross-sectional area of the inlet of the receiving hopper 7 for solid particles at its junction with the lower part of the duct 3 is set to 1: (2-12). This provides an effective cleaning of the gas stream from solid particles. With a ratio of these areas less than 1: 2, the efficiency of separation of solid particles from the flow decreases sharply, and with an increase in the ratio of areas more than 1: 12, in addition to reducing the efficiency of separation of solid particles, capital investments increase.

 The use of the inventive device allowed for low capital costs to effectively clean the exhaust gases from large particles and reduce the load on the bag filter. Thereby, the efficiency of the bag filter is increased, the service life is increased, and operating costs are reduced.

Claims (3)

1. A device for separating solid particles from the gas stream, including a gas duct, which is made in the form of an outer casing, curved along the radius, with a pipe for introducing a gas stream, a slotted hole pipe placed inside the casing, the axis of which is parallel to the casing axis, a receiving hopper for solid particles, a pipe for outputting a gas stream, connected to the end of the pipe, characterized in that the axis of the pipe is shifted towards the pipe for introducing a gas stream, while the cross-sectional area of the pipe for introducing a gas stream adi input hopper opening cross section for the solids in the place of its connection to the lower housing part 1: (2 ÷ 12). 2. The device according to claim 1, characterized in that the ratio of the cross-sectional area of the pipe to the cross-sectional area of the slit-like opening is equal to or less than unity. 3. The device according to claim 1 or 2, characterized in that the slit-shaped hole is provided with a visor mounted on the pipe, while the width of the visor is greater than the radius of the pipe and less than the radius of the housing.

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