是一種機器,在這種機器中,帶有葉片的軸在氣缸或槽中旋轉,將各種材料混合成一種混合物或適當的稠度。今天我們將介紹攪拌機的工作原理
A machine in which a shaft with blades rotates in a cylinder or groove to mix various materials into a mixture or appropriate consistency. Today we will introduce the working principle of the mixer
混頻器是由多個(gè)參數決定的,用任意一個(gè)參數來(lái)描述混頻器是不可能的。軸功率(P)、葉片流量(Q)、壓頭(H)、葉片直徑(D)和攪拌速度(N)是描述水泥攪拌車(chē)的五個(gè)基本參數。葉片的流量與葉片本身的流量、葉片速度的一次方和葉片直徑的三次方成正比。攪拌消耗的軸功率與流體比重、葉片本身的功率判據、轉速的三次方、葉片直徑的五次方成正比
The mixer is determined by multiple parameters. It is impossible to describe the mixer with any one parameter. Shaft power (P), blade flow (q), head (H), blade diameter (d) and mixing speed (n) are the five basic parameters to describe the cement mixer. The flow of the blade is directly proportional to the flow of the blade itself, the first power of the blade speed and the third power of the blade diameter. The shaft power consumed by stirring is directly proportional to the specific gravity of fluid, the power criterion of blade itself, the third power of rotating speed and the fifth power of blade diameter
在某些和形式的葉片,葉片排水數量(Q)和壓頭(H)通過(guò)改變葉片的直徑(D)和速度(N)匹配調整,大直徑葉片與低速(軸功率恒定)水泥攪拌車(chē)高流量和低壓力水頭的影響,和小直徑葉片高速度生產(chǎn)低的壓頭和流量的影響。在攪拌槽中,使顆粒相互碰撞的方法是提供足夠的剪切速率。
In some and forms of blades, the blade drainage quantity (q) and head (H) are adjusted by changing the matching of blade diameter (d) and speed (n), the influence of high flow and low pressure head of large-diameter blades and low-speed (constant shaft power) cement mixer, and the influence of low head and flow of high-speed production of small-diameter blades. In the stirred tank, the only way to make the particles collide with each other is to provide sufficient shear rate.
從攪拌機理來(lái)看,正是由于流體速度的不同,使得流體層之間相互混合。因此,混合過(guò)程總是涉及到流體剪切速率。剪切應力是攪拌過(guò)程中引起氣泡分散和液滴破裂的一種力。必須指出的是,攪拌槽內流體各點(diǎn)的剪切速率是不均勻的。根據剪切速率分布的研究,攪拌槽中少有4個(gè)剪切速率值。它們是:在葉片區域,無(wú)論何種紙漿類(lèi)型,當葉片直徑固定時(shí),剪切速率和平均剪切速率都隨著(zhù)轉速的增加而增加。
From the stirring mechanism, it is the difference of fluid velocity that makes the fluid layers mix with each other. Therefore, the mixing process always involves the fluid shear rate. Shear stress is a kind of force that causes bubble dispersion and droplet rupture in the process of stirring. It must be pointed out that the shear rate at each point of the fluid in the stirred tank is uneven. According to the study of shear rate distribution, there are at least four shear rate values in the mixing tank. They are: in the blade area, regardless of the pulp type, when the blade diameter is fixed, the maximum shear rate and average shear rate increase with the increase of rotating speed.
而當轉速一定時(shí),平均剪切速率與葉片直徑的關(guān)系與紙漿形狀有關(guān)。當轉速一定時(shí),徑向葉片的剪切速率隨葉片直徑的增大而增大,而平均剪切速率與葉片直徑無(wú)關(guān)。這些葉片剪切速率的概念在攪拌器的放大和縮小設計中需要特別注意。與大缸相比,小缸水泥攪拌車(chē)通常具有高速(N)、小葉徑(D)和低葉尖速度(ND)的特點(diǎn),而大缸水泥攪拌車(chē)通常具有低速(N)、大葉徑(D)和高葉尖速度(ND)的特點(diǎn)。
When the rotating speed is constant, the relationship between the maximum average shear rate and blade diameter is related to the shape of pulp. When the rotating speed is constant, the maximum shear rate of radial blade increases with the increase of blade diameter, while the average shear rate is independent of blade diameter. These blade shear rate concepts require special attention in the enlarged and reduced design of agitators. Compared with the large cylinder, the small cylinder cement mixer usually has the characteristics of high speed (n), small blade diameter (d) and low tip speed (nd), while the large cylinder cement mixer usually has the characteristics of low speed (n), large blade diameter (d) and high tip speed (nd).
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