阅读说明：本技术 钢渣微粉的组合式高效选粉机及分选方法 (Combined efficient powder concentrator for steel slag micro powder and sorting method ) 是由 顾金土 王建军 施存有 杨进荣 方文仓 郑方伟 杜小荣 赵钢 黄兴荣 鲍福军 于 2021-01-28 设计创作，主要内容包括：本发明公开了一种钢渣微粉的组合式高效选粉机及分选方法,包括壳体,壳体上端设有进料口,壳体的侧端设有进风口,壳体内设有导向叶片,导向叶片内侧依次设有外转子和内转子,外转子上端设有撒料装置；所述导向叶片和外转子之间设有粗选室,外转子和内转子之间设有细选室；所述壳体下方设有分别与粗选室和细选室相对应的粗粉出料口和细粉出料口。分选方法为通过导向叶片和外转子之间形成的粗选室完成对粉料的第一次粗选,通过同向旋转的外转子和内转子之间形成的细选室来完成对粉料的第二次细选；以此来完成对粉料的分级筛选。本发明具有能够有效提高选粉效率以及能够精确控制选取物料颗粒粒径的特点。(The invention discloses a combined high-efficiency powder concentrator for steel slag micro powder and a separation method, wherein the combined high-efficiency powder concentrator comprises a shell, a feed inlet is formed in the upper end of the shell, an air inlet is formed in the side end of the shell, guide blades are arranged in the shell, an outer rotor and an inner rotor are sequentially arranged on the inner sides of the guide blades, and a material scattering device is arranged at the upper end of the outer rotor; a roughing chamber is arranged between the guide vane and the outer rotor, and a fine-selecting chamber is arranged between the outer rotor and the inner rotor; and a coarse powder discharge port and a fine powder discharge port which respectively correspond to the coarse separation chamber and the fine separation chamber are arranged below the shell. The sorting method comprises the steps that the first rough sorting of powder is completed through a rough sorting chamber formed between a guide vane and an outer rotor, and the second fine sorting of the powder is completed through a fine sorting chamber formed between the outer rotor and an inner rotor which rotate in the same direction; thereby completing the grading screening of the powder. The invention has the characteristics of effectively improving the powder selection efficiency and accurately controlling the particle size of the selected material particles.)

1. The combined high-efficiency powder concentrator for the steel slag micro powder is characterized in that: the material spraying device comprises a shell (1), wherein a feeding hole (2) is formed in the upper end of the shell (1), an air inlet (3) is formed in the side end of the shell (1), guide vanes (4) are arranged in the shell (1), an outer rotor (5) and an inner rotor (6) are sequentially arranged on the inner sides of the guide vanes (4), and a material spraying device (7) is arranged at the upper end of the outer rotor (5); a roughing chamber (8) is arranged between the guide vane (4) and the outer rotor (5), and a fine-selecting chamber (9) is arranged between the outer rotor (5) and the inner rotor (6); a coarse powder discharge port (10) and a fine powder discharge port (11) which respectively correspond to the coarse separation chamber (8) and the fine separation chamber (9) are arranged below the shell (1).

2. The combined high-efficiency powder concentrator of steel slag micropowder according to claim 1, characterized in that: a middle coarse powder discharge hole (12) is also arranged below the fine separation chamber (9).

3. The combined high-efficiency powder concentrator of steel slag micropowder according to claim 1, characterized in that: the outer rotor (5) is connected with an outer rotor transmission device (13).

4. The combined high-efficiency powder concentrator of steel slag micropowder according to claim 1, characterized in that: the inner rotor (6) is connected with an inner rotor transmission device (14).

5. The separation method of the combined high-efficiency powder concentrator for steel slag micropowder of any one of claims 1 to 4 is characterized in that: the primary roughing of the powder is finished through a roughing chamber formed between the guide vane and the outer rotor, and the secondary fine sorting of the powder is finished through a fine sorting chamber formed between the outer rotor and the inner rotor which rotate in the same direction; thereby completing the grading screening of the powder.

6. The separation method of the combined high-efficiency powder separator for steel slag micropowder according to claim 5, characterized by comprising the following steps: the particle size of the material to be screened is controlled by controlling the number of blades of the outer rotor and the inner rotor, the linear speed of rotation and the air flow rate, so that accurate classification is realized.

7. The separation method of the combined high-efficiency powder separator for steel slag micropowder according to claim 5, characterized by comprising the following steps: the maximum feeding amount (kg/h) of the powder concentrator is calculated by the following formula:

w ═ K × (1+ L) × T; in the formula: k is a reserve coefficient, and K is 1.2; l is a cyclic load rate, and is 200-250%; t is the design yield (T/h) of the finished product;

powder selecting air quantity (m) of powder selecting machine³The formula for the calculation of/h) is:

Q＝W/C_s(ii) a In the formula: c_sGas ratio (C) of powder concentrator_s＝2～2.5kg/m³)；

The formula for calculating the fractional particle size (cm) is:

d_o＝(18μ×R×U_r/ρ)^(1/2)/10V_r1。

8. the separation method of the combined high-efficiency powder separator for steel slag micropowder according to claim 5, characterized by comprising the following steps: gas drag force F between rotor blades_rAnd centrifugal force F_tThe calculation formulas of (A) and (B) are respectively as follows:

F_r＝600π×(d_i/2)×μ×U_r；

F_t＝(4π/3)×(d_i/2)³×ρ×(100V_r1)²/R；

in the formula: d_iIs the particle size of the material particles, cm; mu is the viscosity of the powder selecting gas, Pa.s; u shape_rIs the radial air velocity between the rotor blades, m/s; rho is the mass density of the material, g/cm³(ii) a R is the radius of the rotor, cm; v_r1Is the tangential circumferential operating speed of the rotor, m/s.

9. The separation method of the combined high-efficiency powder separator for steel slag micropowder according to claim 5, characterized by comprising the following steps:

when F is present_r＝F_tAt this time, the particle diameter d₀Referred to as cut particle size or graded particle size;

when F of the material_r＞F_tWhen the material particles pass through the rotor blades, the next fine separation process is carried out; when F of the material_r＜F_tDuring the process, the material particles fall into the collecting cone under the action of centrifugal force, gravity, traction force and other resultant forces to realize classification.

10. The separation method of the combined high-efficiency powder separator for steel slag micropowder according to claim 9, characterized by comprising the following steps:

the radial airflow velocity (m/s) between the rotor blades is calculated as:

U_r＝Q/S/3600；

in the formula: q is the air quantity (m) of the powder concentrator³H); s is the passing area (m) between the rotors²)；

Area of passage between rotors (m)²) The calculation formula of (2) is as follows:

S＝π(2R/10)×L-(n×L×H)；

in the formula: n is the number of blades; l is the length of the blade, m; h is the thickness of the blade, m; r is the rotor radius, cm.

Technical Field

The invention relates to a powder concentrator, in particular to a combined efficient powder concentrator for steel slag micro powder and a separation method.

Background

Because the steel slag is difficult to grind and activate, the steel slag is generally mechanically activated by adopting a loop flow high-fine ball mill with a roller press for pre-grinding, so that the specific surface of the steel slag reaches 450-500 m²Kg, which is much higher than the specific surface area of ordinary cement. Aiming at the steel slag with larger specific area, a high-efficiency steel slag powder selector is needed for sorting, and the milled materials are quickly and timely dispersed, graded and separated by utilizing the flowing of gas, so as to separate coarse and fine powdery materials. The prior steel slag powder separator has low uniformity of material distribution and air distribution, so that the final separation efficiency is low and can only be kept at 45-50%; in addition, the existing steel slag powder separator needs to improve the feeding concentration in order to ensure the high quality and the high yield of the screened material, but the influence of the interference of the dispersion and the grading process of the material is increased when the feeding concentration is too highAnd when the size is large, collision and agglomeration among particles are increased, and the powder selecting efficiency is reduced. Meanwhile, the existing efficient steel slag sorting machine cannot adjust the particle size distribution of material particles and cannot realize accurate grading sorting. Therefore, the prior art has the problems of low powder selection efficiency and incapability of accurately controlling the particle size of the selected material particles.

Disclosure of Invention

The invention aims to provide a combined efficient powder concentrator for steel slag micro powder and a separation method. The invention has the characteristics of effectively improving the powder selection efficiency and accurately controlling the particle size of the selected material particles.

The technical scheme of the invention is as follows: the combined high-efficiency powder concentrator for the steel slag micro powder comprises a shell, wherein a feed inlet is formed in the upper end of the shell, an air inlet is formed in the side end of the shell, guide blades are arranged in the shell, an outer rotor and an inner rotor are sequentially arranged on the inner sides of the guide blades, and a material scattering device is arranged at the upper end of the outer rotor; a roughing chamber is arranged between the guide vane and the outer rotor, and a fine-selecting chamber is arranged between the outer rotor and the inner rotor; a coarse powder discharge port and a fine powder discharge port which respectively correspond to the coarse separation chamber and the fine separation chamber are arranged below the shell, and meanwhile, wear-resistant materials are adopted for the outer rotor and the inner rotor; an inner surface of the housing; wear-resisting processing increases life is carried out to casing upper end feed inlet.

In the combined high-efficiency powder concentrator for the steel slag micro powder, a middle coarse powder discharge hole is also formed below the fine separation chamber.

In the combined type high-efficiency powder concentrator for the steel slag micro powder, the outer rotor is connected with an outer rotor transmission device.

In the combined type efficient powder concentrator for the steel slag micro powder, the inner rotor is connected with an inner rotor transmission device.

A sorting method of a combined high-efficiency powder concentrator for steel slag micro-powder comprises the steps of finishing primary rough sorting of the powder through a rough sorting chamber formed between a guide blade and an outer rotor, and finishing secondary fine sorting of the powder through a fine sorting chamber formed between the outer rotor and an inner rotor which rotate in the same direction; thereby completing the grading screening of the powder.

In the separation method of the combined high-efficiency powder concentrator for the steel slag micro powder, the particle size of the material to be screened is controlled by controlling the number of blades of the outer rotor and the inner rotor, the linear speed of rotation and the air flow rate, so that accurate classification is realized.

In the separation method of the combined high-efficiency powder concentrator for steel slag micro powder, the maximum feeding amount (kg/h) of the powder concentrator is calculated according to the formula:

w ═ K × (1+ L) × T; in the formula: k is a reserve coefficient, and K is 1.2; l is a cyclic load rate, and is 200-250%; t is the design yield (T/h) of the finished product;

powder selecting air quantity (m) of powder selecting machine³The formula for the calculation of/h) is:

Q＝W/C_s(ii) a In the formula: c_sGas ratio (C) of powder concentrator_s＝2～2.5kg/m³)；

The formula for calculating the fractional particle size (cm) is:

d_o＝(18μ×R×U_r/ρ)^(1/2)/10V_r1。

in the separation method of the combined high-efficiency powder concentrator for the steel slag micropowder, the gas traction force F between the rotor blades_rAnd centrifugal force F_tThe calculation formulas of (A) and (B) are respectively as follows:

F_r＝600π×(d_i/2)×μ×U_r；

F_t＝(4π/3)×(d_i/2)³×ρ×(100V_r1)²/R；

in the formula: d_iIs the particle size of the material particles, cm; mu is the viscosity of the powder selecting gas, Pa.s; u shape_rIs the radial air velocity between the rotor blades, m/s; rho is the mass density of the material, g/cm³(ii) a R is the radius of the rotor, cm; v_r1The tangential circumferential working speed of the rotor is m/s;

in the separation method of the combined high-efficiency powder separator for the steel slag micro powder, when F is used, the steel slag micro powder is separated into a first fraction and a second fraction_r＝F_tAt this time, the particle diameter d₀Referred to as cut particle size or graded particle size;

when F of the material_r＞F_tWhen the material particles pass through the rotor blades, they enter the next step of refiningSelecting process step, when F of material_r＜F_tDuring the process, the material particles fall into the collecting cone under the action of centrifugal force, gravity, traction force and other resultant forces to realize classification.

In the separation method of the combined high-efficiency powder separator for steel slag micro-powder, the calculation formula of the radial air velocity (m/s) between the rotor blades is as follows:

U_rQ/S/3600; in the formula: q is the air quantity (m) of the powder concentrator³H); s is the passing area (m) between the rotors²)；

Area of passage between rotors (m)²) The calculation formula of (2) is as follows:

s ═ pi (2R/10) × L- (nxlxlxh); in the formula: n is the number of blades; l is the length (m) of the blade; h is the thickness (m) of the blade; r is the rotor radius, cm.

Compared with the prior art, the inner rotor and the outer rotor are arranged in the same separator, two separation chambers (namely the roughing chamber and the fine separation chamber) are formed to finish the primary separation and the secondary accurate classification of the steel slag materials, the load of the inner rotor can be reduced, the powder selection efficiency of the powder concentrator is improved, the accurate classification can be realized, and the integral powder selection efficiency can reach more than 98%. The invention controls the particle size of the material which is required by the finished product by controlling the number of blades of the inner rotor and the outer rotor, different linear velocities and air flow velocities, thereby realizing accurate classification, improving the sorting precision and the quality of the product, realizing the three grades of the material which is divided into coarse powder to be reprocessed, low-quality finished products and high-quality fine products, and leading a user to randomly adjust the quality of the product according to the requirements of different customers, thereby achieving the purpose of reasonably utilizing resources; has good social benefit and economic benefit. Through the mutual cooperation of the structures, the grading precision of the combined powder concentrator can be effectively improved, the particle size distribution of the finished steel slag powder can be controlled randomly, and the activity of the steel slag powder is fully excited. In conclusion, the invention has the characteristics of effectively improving the powder selection efficiency and accurately controlling the particle size of the selected material particles.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is an external view of the present invention;

fig. 3 is a top view of the present invention.

The labels in the figures are: 1-shell, 2-feed inlet, 3-air inlet, 4-guide vane, 5-outer rotor, 6-inner rotor, 7-material scattering device, 8-roughing chamber, 9-fine selection, 10-coarse powder discharge outlet, 11-fine powder discharge outlet, 12-middle coarse powder discharge outlet, 13-outer rotor transmission device and 14-inner rotor transmission device.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

Examples are given. The combined high-efficiency powder concentrator for the steel slag micro powder is shown in figures 1 to 3 and comprises a shell 1, wherein a feed inlet 2 is arranged at the upper end of the shell 1, an air inlet 3 is arranged at the side end of the shell 1, guide blades 4 are arranged in the shell 1, an outer rotor 5 and an inner rotor 6 are sequentially arranged on the inner sides of the guide blades 4, and a material scattering device 7 is arranged at the upper end of the outer rotor 5; a roughing chamber 8 is arranged between the guide vane 4 and the outer rotor 5, and a fine-selecting chamber 9 is arranged between the outer rotor 5 and the inner rotor 6; a coarse powder discharge port 10 and a fine powder discharge port 11 which respectively correspond to the coarse separation chamber 8 and the fine separation chamber 9 are arranged below the shell 1.

A middle coarse powder discharge port 12 is also arranged below the fine separation chamber 9.

The outer rotor 5 is connected with an outer rotor transmission device 13.

An inner rotor transmission 14 is connected to the inner rotor 6.

A sorting method of a combined high-efficiency powder concentrator for steel slag micro-powder comprises the steps of finishing primary rough sorting of the powder through a rough sorting chamber formed between a guide blade and an outer rotor, and finishing secondary fine sorting of the powder through a fine sorting chamber formed between the outer rotor and an inner rotor which rotate in the same direction; thereby completing the grading screening of the powder.

The particle size of the material to be screened is controlled by controlling the number of blades of the outer rotor and the inner rotor, the linear speed of rotation and the air flow rate, so that accurate classification is realized.

The maximum feeding amount (kg/h) of the powder concentrator is calculated by the following formula:

w ═ K × (1+ L) × T; in the formula: k is a reserve coefficient, and K is 1.2; l is a cyclic load rate, and is 200-250%; t is the design yield (T/h) of the finished product;

powder selecting air quantity (m) of powder selecting machine³The formula for the calculation of/h) is:

Q＝W/C_s(ii) a In the formula: c_sGas ratio (C) of powder concentrator_s＝2～2.5kg/m³)；

The formula for calculating the fractional particle size (cm) is:

d_o＝(18μ×R×U_r/ρ)^(1/2)/10V_r1。

gas drag force F between rotor blades_rAnd centrifugal force F_tThe calculation formulas of (A) and (B) are respectively as follows:

F_r＝600π×(d_i/2)×μ×U_r；

F_t＝(4π/3)×(d_i/2)³×ρ×(100V_r1)²/R；

in the formula: d_iIs the particle size of the material particles, cm; mu is the viscosity of the powder selecting gas, Pa.s; u shape_rIs the radial air velocity between the rotor blades, m/s; rho is the mass density of the material, g/cm³(ii) a R is the radius of the rotor, cm; v_r1The tangential circumferential working speed of the rotor is m/s;

when F is present_r＝F_tAt this time, the particle diameter d₀Referred to as cut particle size or graded particle size;

when F of the material_r＞F_tWhen the material particles pass through the rotor blades, the next fine separation process is carried out, and when the material F is obtained_r＜F_tDuring the process, the material particles fall into the collecting cone under the action of centrifugal force, gravity, traction force and other resultant forces to realize classification.

The radial airflow velocity (m/s) between the rotor blades is calculated as:

U_rQ/S/3600; in the formula: q is the air quantity (m) of the powder concentrator³H); s is the passing area (m) between the rotors²)；

Area of passage between rotors (m)²) The calculation formula of (2) is as follows:

s ═ pi (2R/10) × L- (nxlxlxh); in the formula: n is the number of blades; l is the length of the blade, m; h is the thickness of the blade, m; r is the rotor radius, cm.

The working principle is as follows: the materials enter a material scattering device in the powder concentrator through a feed inlet arranged on a shell, an outer rotor drives the material scattering device to rotate under the drive of an outer rotor transmission device, the materials are uniformly scattered to the periphery, the materials enter a vortex powder selecting area (namely a roughing chamber) between a guide blade and the outer rotor, the materials are fully mixed with gas again in the powder selecting area of the roughing chamber, a part of large-particle materials begin to freely settle under the action of self gravity and enter a lower cone, the materials are discharged from a coarse powder discharge port, the first primary separation of the materials is completed in the roughing chamber, and the primarily selected coarse materials can return to a mill or grinding equipment thereof for secondary processing; the fine material after the primary selection enters a vortex channel (namely a fine selection chamber) between the outer rotor and the inner rotor, the outer rotor and the inner rotor move in the same direction under the action of an outer rotor transmission device and an inner rotor transmission device, different rotating speed conditions are set for the outer rotor and the inner rotor respectively, the material is refined for the second time in a fine selection chamber area, and the refined finished product material enters a fine powder discharge port along with the air flow through the inner rotor and enters a dust collector to be collected into a finished product. The materials left after refining in the refining area can be used as low-quality finished products to be settled and collected through a middle coarse powder discharge hole.

The invention aims to improve the quality of the steel slag powder, and separates coarse materials with unqualified particle size from fine materials through primary selection, so that the materials with qualified particle size enter a second sorting chamber for secondary sorting, and the purpose of sorting is to enable the particle size distribution of finished products to be wider, thereby improving the adaptability of the finished products and enabling the finished products to fully exert various properties.

Natural wind enters the interior of a powder concentrator shell through 2 uniformly distributed air inlets arranged on the powder concentrator shell, the wind entering the interior passes through wind guide blades uniformly distributed on the periphery and then enters a vortex separation area I between the guide blades and an outer rotor, the airflow speed in the vortex area along the circumferential direction is realized by adjusting the rotating speed of the outer rotor (the circumferential motion speed of the rotor is called as the rotor rotating linear speed, and the airflow speed is also related to the air draft of a finished product connected with a main exhaust fan of an external dust collector), and the accurate classification of materials is realized by adjusting the airflow speed and the linear speed.

The design and calculation method of the relevant parameters of the powder concentrator comprises the following steps:

when the concentration of the selected materials in the powder selecting machine reaches a certain value, interference settlement and centrifugal settlement exist. The design uses the theory of free settling of monomer particles to search for the relationship between the separation particle size and the relevant process parameters. And determining relevant sizes and parameters by combining practical experience.

1. Maximum feeding amount (kg/h) of powder concentrator

W＝K×(1+L)×T

In the formula: k is a reserve coefficient, and K is 1.2;

l is a cyclic load rate, and is 200-250%;

t is the design yield (T/h) of the finished product.

2. Powder selecting air quantity (m) of powder selecting machine³/h)

Q＝W/C_s

In the formula: c_sGas ratio (C) of powder concentrator_s＝2～2.5kg/m³)。

3. Fractional particle size (cm)

d_o＝(18μ×R×U_r/ρ)^(1/2)/10V_r1

After the material fed into the powder concentrator passes through the material spreading disk and is uniformly dispersed, most of the powder material is passed through the guide blade and introduced into the powder-selecting zone to make primary coarse selection, and the gas traction force F between rotor blades_rAnd centrifugal force F_tThe function of (1).

F_r＝600π×(d_i/2)×μ×U_r(N)

F_t＝(4π/3)×(d_i/2)³×ρ×(100V_r1)²/R(N)

In the formula: d_iIs the particle size of the material particles, cm;

mu is the viscosity of the powder selecting gas, Pa.s;

U_ris the radial air velocity between the rotor blades, m/s;

rho is the mass density of the material, g/cm³；

R is the radius cm of the rotor;

V_r1is the tangential circumferential operating speed of the rotor, m/s.

When F is present_r＝F_tAt this time, the particle diameter d₀Referred to as cut particle size or graded particle size.

d_o＝(18μ×R×U_r/ρ)^(1/2)/10V_r1(cm)

The radial speed U between the blades under a specific working environment can be known by a calculation formula_rThe greater the traction force F produced_rThe larger; while centrifugal force F of the rotor_tVaries in direct proportion to the tangential speed of the rotor. When the material F_r＞F_tThe material particles pass through the rotating cage blades and enter the next working procedure, and when the material F is_r＜F_tThe material particles fall into the collecting cone under the action of centrifugal force, gravity, traction force and other resultant forces after deviating from the blades, so that classification is realized.

4. Radial air velocity (m/s) between rotor blades

U_r＝Q/S/3600

In the formula: q is the air quantity (m) of the powder concentrator³/h)；

S is the passing area (m) between the rotors²)。

5. Area of passage between rotors (m)²)

S＝π(2R/10)×L-(n×L×H)

In the formula: n is the number of blades;

l is the length (m) of the blade;

h is the thickness (m) of the blade;

r is the rotor radius, cm.

6. For example, the following steps are carried out:

if the required finished product amount is known to be 80t/h

6.1 maximum feeding amount (kg/h) of powder concentrator

W＝1.2×3.5×80×1000＝336000(kg/h)

6.2 air flow (m) of powder concentrator³/h)

Q＝60W/C_s

Material gas ratio C of powder concentrator_sAt 2.5kg/m³The powder selecting machine is in the best working state, the energy consumption is low, and the powder selecting efficiency is high. Calculation of air volume of selected powder C_s＝2.5kg/m³As a reference.

Q＝336000/2.5＝134400(m³/h)

6.3, every 1.0m in the powder concentrator under normal conditions³The product amount under the condition of operation gas amount is 450-500 m as the product surface area³In/kg), C_s1The reasonable concentration range of the finished product is 0.4-0.6 (kg/m)³)；

C_s1＝80×1000/134400＝0.59(kg/m³) Meet the requirements

6.4, outer rotor diameter (m):

D＝2R/10

S＝π(2R/10)×L-(n×L×H)

S＝Q/3600/U_r

l-f × D (f is the proportionality coefficient of blade length to rotor diameter)

S_{Inner part}＝Q/3600/U_r＝134400/3600/3.35＝11.14m²

D_{Inner part}＝2.05m；

S_{Outer cover}＝Q/3600/U_r＝134400/3600/3.8＝9.82m²

D_{Outer cover}＝2.4m；

According to the practical production experience data of the powder concentrator:

U_r＝3.0～4(m/s)，f＝0.5～0.8，H＝0.06m

get U_{r is inside}＝3.35m/s，U_{r outer}＝3.8m/s，n_{Inner part}＝96，n_{Outer cover}＝48，L＝1.6m，f_{Outer cover}＝0.66，f_{Inner part}＝0.78；

6.5, fractional particle size (cm):

it is known that: rotor speed N_{Outer cover}＝130r/min，N_{Inner part}＝250r/min，

Gas viscosity μ 0.0000198pa.s, particle density ρ 3.1g/cm³

V_r1＝(N×π×2R/10)/3600

d_o＝(18μ×R×U_r/ρ)^(1/2)/10V_r1

d_{Outer cover}＝(18×0.0000198×120×3.8/3.1)^(1/2)/(10×130×π×24/3600)

＝8.41×10^-3(cm)

d_{Inner part}＝(18×0.0000198×120×3.35/3.1)^(1/2)/(10×250×π×24/3600)＝3.79×10^-3(cm)

7. It is known that: w is 336t/h, V_{r outer}＝16m/s，S_{Outer cover}＝11.14m²，C_S＝2.5kg/m²，

γ_kqx＝0.994kg/m³，η₁＝0.85，η₂＝0.9，V_{r is inside}＝26.8m/s，S_{Outer cover}＝9.82m²，

t_xf＝80℃

γ_kqx＝＝1.293×273/(273+t_xf)

In the formula: w is the maximum feeding amount t/h

V_rIs the linear speed m/s of the rotor

S is the rotor passing area m²

C_sThe dust concentration is kg/m³

γ_kqxIs the air concentration kg/m³

η₁Is the efficiency of a speed reducer

η₂Is the motor efficiency%

P_fFor the power consumed kW

P_dFor spreading material power kW

P_{Outer cover}For outer rotor motor power kW

P_{Inner part}For inner rotor motor power kW

Solving: p_{Outer cover}＝P_f+P_d/(η₁×η₂)

P_{Outer cover}＝(0.18/2000)×(C_S+γ_kqx)×Vr³×S+【(W×C_S×V_r ²)/(7200

×η₁×η₂)】

P_{Outer cover}＝(0.18/2000)×(2.5+1.0)×16³×11.14+【(336×2.5

×16²)/(7200×0.85×0.9)】＝53.4(kW)

Therefore, the power of the selected motor is 55kW

Solving: p_{Inner part}＝P_f/(η₁×η₂)

P_{Inner part}＝(0.18/2000)×(C_S+γ_kqx)×V_r ³×S/(η₁×η₂)

P_{Inner part}＝(0.18/2000)×(2.5+1.0)×26.8³×9.821/(0.85×0.9)

＝77.84(kW)

Therefore, the power of the selected motor is 90 kW;

from the above calculations: the installed power of the outer rotor and the installed power of the inner rotor are respectively as follows: 55kW and 90 kW.