The impeller of the fan

 

(57) Abstract:

The impeller is designed for smoke exhausters sinter production. The impeller has a Central and lateral disks, between which set the main blade. At each input end of the main blades welded one-sided welded seam protective blade with tilt 20-30 to the working surface of the main blades. Protective blades have a trapezoidal shape with a height equal to 0.4-0.6 of the width of the input side of the main blades, and is adjoined by a large base to a Central disk. The elevation of the top edge of the protective blade above the work surface of the main blades is the Central disc of 0.015 to 0.02, and at the opposite end of the protective shoulder - 0,007-0.01 length of the main blades. The working surface and the ends of the protective blades deposited by the highly rigid alloy with a thickness of hardfacing layer constituting 0.1-0.2 thickness of the protective blades. This embodiment of the exhauster will allow for the possibility of multiple replacement of worn protective blades without damage to the main blades, i.e., increased maintainability, reliability of the wheel and extends its service life. 2 C.p. f-crystals, 3 ill.

The invention relates to the field inpulsive mainly in the construction of smoke exhausters sinter production (exhausters).

All of the exhaust gas exhaust ducts metallurgical production, kiln units, boilers, thermal power plants, etc. are most prone to wear exhausters sinter production, and are worn primarily vanes of the impeller.

Dust in the wheel exhauster, as shown by repeated examination of worn impellers, is concentrated in a narrow cords and cut the blades from the Central disk stripe width of less than 20 mm

Known methods for the protection of impeller blades from abrasive wear by applying on the surface of the highly rigid metal inapplicable exhausters due to the high peripheral speed of the wheel, and therefore the larger the centrifugal forces that destroy the protective coating (see A. D. Brooke, Exhaust gas treatment facilities, Meters, mechanical engineering, 1984, S. 42, 55, 88).

Transported the gas flow entering the impeller in the axial direction and, resting on okaloosae the Central area of the disk changes the direction of the velocity at radial, with dust particles, many orders of magnitude more inertia than the gas molecules, reach almost to the surface of the Central disk. At the entrance to milepost blades. The pressure force of the particles on the blade, as is known, is equal to the product of its mass and acceleration, reaching in the area of primary contact tens of thousands of m/s2.

From this it follows that the preliminary acceleration of particles in the tangential direction on a smaller radius substantially reduces their impact on the rotor blades. This task technique is solved by setting before the rotor blades of additional protective blades on a smaller radius of the wheel, which perceive the primary impacts of dust particles and thus protects blades from severe wear.

Known impeller of the centrifugal fan single-inlet, including suspension and front discs fastened between the rotor blades, in which the host drive is running in front of the rotor blades installed easily removable blade crown with a lattice having compared with workers in 2-3 times more protective of blades smaller width with angle output 22-25oexceeding the exit angle of gas flow with blades (see and.with. N 259315, CL 27, 12/02, IPC F 04 C).

Dust particles, affecting mainly on the protective blades, dispersed them in angelopolis to the radius ensures the creation of the vortex zone along the surface of the support disc, what contributes to the dispersion of the particles in the interscapular area.

The most significant drawbacks of this solution include:

vortex area, created a large number of protective blades, occupies a significant interscapular space, resulting in lower pressure gas flow:

- install the blade crown flat on your host drive is suitable only for low-power centrifugal fans for General purposes, as the high speed gas flow in this design of the impeller causes the separation of a gas stream to the front of the disk, forming a vortex zone, which increases aerodynamic drag wheels:

Thus, solving the task of protecting the blades from wear and tear, this design significantly reduces the generated pressure.

In addition, when the vibration of the impeller due to uneven wear of the blades, the screw fastening parts is unreliable, and their separation from the wheel when the speed of rotation of 1000 rpm will inevitably lead to accidents.

Thus, easy pealing protective blades reduces the reliability of the fan.

It is known and accepted as a prototype Rabocheye main blades and protective blade, the number of which is equal to the number of main blades, in which the protective blades are arranged in the radial direction between the ends of the main blades, inclined in the direction opposite to the direction of the peripheral speed of the wheel and welded to the Central disk on sites with a pseudo-spherical and flat surfaces in the zone of rotation from axial to radial flow velocity (see A. D. Brooke, Exhaust gas treatment facilities, Meters, mechanical engineering, 1984, S. 60).

Protective blade of this design form the vortex zone is significantly smaller, i.e. less influence on the technological parameters of the exhauster.

The disadvantage of the prototype is that when replacing the protective blades (most wearing parts of the impeller), inevitably damaged the surface of the Central disk in the most intense and responsible part, which significantly reduces the reliability of the wheel and reduces its service life.

The basis for this invention is the task: by improving the design of the impeller to increase the reliability and extend the service life of the wheel without substantial deterioration of the technological parameters of the exhauster.

The problem is solved in that Rami and protective blade, the number of which is equal to the number of main blades, according to the invention the protective blade having a trapezoidal shape with a height of 0.4 - 0.6 of the width of the input side of the main blades rigidly mounted on the input ends of the main blades angle = 20-30oto the working surface and adjacent to a large base to the Central disk, and the elevation of the top edge of the protective blade above the work surface of the main blades is the Central disc h = 0,015 - 0,02, and at the opposite end of the protective blades h = 0,007-0.01 length of the main blades.

Moreover, the protective blades are welded to the ends of the main blades unilateral welded seam.

Moreover, the working surface and the ends of the protective blades deposited by the highly rigid alloy with a thickness of hardfacing layer constituting 0.1 - 0.2 thickness of the protective blades.

When the smoke exhauster highest abrasive wear are protective of the scapula. Their attachment to the ends of the main blades eliminates damage to the Central disk when replacing the protective blades. Fastening by welding provides reliable fixation, and the one-seam located at the end of the main blades, allows you to trim worn protective blades without Powerade without damaging the main elements of the impeller.

Due to the fact that the dust particles due to their inertia when entering bezlopastny space are concentrated in the Central disk, protective blade adjacent to the Central disk and when their length, equal to 0.4 - 0.6 of the width of the main blades, almost the entire flow of dust gets on the protective blades, however, if their length exceeds 0.6 of the width of the main blades, it is not only useless in terms of protection, but also harmful, because it increases the voltage in the main blades from the centrifugal force.

The location of protective blades with an angle to the working surface of the main blades provides education along the surface of the main blades of the vortex zone, necessary for scattering dust flow on the inter-layer space, with a decrease of the angle between the planes of the blades improves the flow of protective blades of the gas flow and increases their interaction on the dust particles in the recent acceleration in the tangential direction, but at the same time increases and the width of the protective blades, necessary for the formation of the vortex zone of optimum thickness, which in turn increases the weight of the protective blades, and hence the centrifugal force acting on the main blade. is Oh zone along the working surface of the main blades is determined primarily by elevation of the upper edge of the protective blades (h) above the working surface of the main blades.

The Central disk, the concentration of dust particles in front of the blades is greatest, and therefore the thickness of the vortex zone should be the greatest, but with the increase in the thickness of the vortex zone, increases the volume it occupies megapastor space, and with it the energy costs of her education, which reduces the differential pressure created by the impeller, i.e., the pressure at the outlet of the fan.

When the ratio (h) to the length of the main blades, more than 0.02 from the Central disk and 0.01 at the other end, with a sufficient degree of scattering dust loss of energy of the gas flow on the formation of the vortex zone would be unreasonably large, and with respect to, less than of 0.015 and 0.007, respectively, the scattering will be insufficiently effective.

Thus, the optimum elevation of the upper edge of the protective blade above the work surface of the main blades is the Central disc h = 0,015 - 0,02, and at the end of the protective blades h = 0,007 - 0.01 length of the main blades.

Due to the fact that the cross-sectional area of the vortex zones formed by the blades, does not exceed 4% of the area of the gas inlet in bezlopastny space, and the volume of these vortex zones is less than 1% of the volume megapastor space, negatiive abrasive particles impact mainly on the protective blades, giving them the working surface of high hardness (HU = 1000) greatly increases their lifespan, and therefore the overhaul life of the exhauster.

However, in the weld brittle carbide layer, the number of microcracks in proportion to the square of the thickness of the hardfacing layer. When the voltage from the action of centrifugal forces, which impellers exhausters value 1500-1800 kg/cm, microcracks lead to spalling of the surface layer, if the thickness of more than 0.2 thickness of the blade, and when the relative thickness of the deposited layer, a lower 0,1, - the effectiveness of protective blades from abrasive wear is markedly reduced.

The optimum thickness of the carbide layer is 0.1 - 0.2 thickness of the protective blades.

Since the radius of the location of protective blades in the present invention is approximately half the outer radius of the impeller, which limits the magnitude of the stresses from centrifugal forces in the deposited layer of protective blades within the allowable values.

Thus, the present invention provides frequent replacement of worn protective blades without damaging the main elements of the impeller, which poses the Oia disks, and increases maintainability and reliability.

The essence of the invention is illustrated by the attached drawings, which shows:

Fig. 1 - General view of the impeller of the smoke exhauster;

Fig. 2 - section a-a of Fig. 1;

Fig. 3 is a section along B-B of Fig. 1.

The impeller of the smoke exhauster includes a Central disk 1 and the two side disk 2, between which set the main blade 3. To the input ends of the main blades welded protective blade 4 angle = 30oto the working surface 5 of the main blades. Protective blades have a trapezoidal shape and is adjoined by a large base to the Central disk 1. Length of protective blades (the altitude of the trapezoid) is 0.6 of the width of the input side of the main blades. The elevation of the top edge of the protective blades above the working surface 5 of the main blades is the Central disc - h = 0,02, and at the end of the protective shoulder - h = 0.01 length of the main blade 3.

Protective blades 4 are welded one-sided welded rear-side blades.

The working surface of the protective blades 4 deposited by the highly rigid alloy electrode of brand T-620. The thickness of the hardfacing layer 6 is 0.2, the thickness of the protective blades.

Coming from the gas stream dust particles as well as gas, are inhibited in the axial direction, but slower due to the much greater mass of the particles, therefore, reach almost to the Central disk 1. Carried by a stream of gas to the main blades 3, dust particles hit moving in the circumferential direction of the protective blades 4 mounted on the input ends of the main blades 3, are accelerated to the peripheral speed of the input ends of the main blades and are made in bezlopastny space.

Due to the inclination of the protective blade 4 relative to the main blade 3, and the elevation of the upper edges of the protective blades above the working surface 5 of the main blades, the most significant in the Central disk - along-thirds of the length of the main blade 3 and a half its width is formed a narrow vortex zone, russei and with the working surface of the main blades, in addition, a further increase in the peripheral speed of dust particles occurs due to the interaction with the accelerating gas stream, and the working surface of the main blades 5 are practically not subjected to abrasive wear.

During operation of the exhauster is periodically inspection of the impeller. When the wear of the blades is greater than the allowed value, they are cut and replaced with new ones, aimed carbide layer. When the main blades are practically not damaged.

Thus, the proposed design of the impeller substantially improves its maintainability and reliability, with repeated replacement of protective blades without damaging the main parts of the impeller ensures a significant increase in its operating life.

1. The impeller of the fan, the contains of the Central and lateral disks installed between the main blades and protective blade, the number of which is equal to the number of main blades, characterized in that the protective blade having a trapezoidal shape with the height component of 0.4 - 0.6 of the width of the input side of the main blades rigidly mounted on the input ends of the main blades with m elevation of the upper edge of the protective blade above the work surface of the main blades is the Central disc of 0.015 - 0,02, and at the opposite end of the protective shoulder - 0,007 - 0.01 length of the main blades.

2. The impeller of the fan under item 1, characterized in that the protective blades are welded to the front ends of the main blades unilateral welded seam.

3. The impeller of the fan under item 1, characterized in that the working surface and the ends of the protective blades deposited by the highly rigid alloy with a thickness of hardfacing layer constituting 0.1 - 0.2 thickness of the protective blades.

 

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