5.2 筛选设备在线视频

同学们好
Hello, everyone

上一节课
In the last class

我们介绍了筛选和净化设备的
we introduced the working principle, function

工作原理、作用
evaluation indicators and application form

评价指标和应用形式
of screening and purifying equipment

本节课我们系统的
In this class, I will systematically

介绍筛选设备
introduce the screening equipment

包括筛选设备的基本结构、分类
including the basic structure, classification

以及常见的产品类型等and common product types of the screening equipment

在概述中我们讲到
In the overview, we have mentioned that

筛选设备是利用阻留原理
the screening equipment uses the retention principle

分离杂质和纤维的
to separate impurities and fibers

这其中起阻留作用的就是筛板
Among them, the screen plate plays a role of retention

也是筛选设备的基本部件
which is also the basic component of the screening equipment

同时也是关键部件
as well as the key component

如图所示
as shown in the figure

根据筛板上面开口的形式
According to the form of the opening on the screen plate

可以将筛浆机分为孔筛或缝筛
the screen can be classified into hole screen or slotted screen

通常，孔筛用来去除较为粗大的杂质
Usually, hole screen is used to remove larger contaminants

缝筛用来去除较为细小的杂质
slotted screen are used to remove smaller contaminants

在实际生产中
In practical production

筛板通常以平面或圆框的形式工作
the screen plates usually work in the form of flat or round frame

下面来看一下几类常见的筛选设备
Let’s have a look at a few common screening devices

首先是高频振框式平筛
First is the high-frequency vibrating screen

该设备是由机械部件
The equipment is a screening equipment that produces vibration

产生振动来净化筛板
from mechanical parts to clean the screen plate

同时利用压力差
and at the same time, uses pressure difference

使良浆通过筛板或者筛鼓的筛选设备
to make the accepted stock through the screen plate or screen drum

这类的筛选设备由
This kind of screening equipment is made up of

筛框、筛板、偏心轮和喷射管组成
screen frame, screen plate, eccentric wheel and injection pipe

用途主要是用于纸浆的粗选
It is mainly used for coarse selection of pulp

筛除较大的杂质
screening out large contaminants

如木节、草节、砂石和铁屑等
such as wood knots, grass, sandstone and iron chips

其次，是离心式筛浆机
Next, the centrifugal screen

离心筛作为粗浆筛选的主要设备
Centrifugal screen has been widely used

已得到广泛应用
as the main equipment for coarse pulp screening

它的结构特点是卧式外流式
Its structure is characterized by horizontal outflow

转子在圆形筛鼓内旋转
and the rotor rotates in a circular screen drum

浆料借助液压差
The pulp enters from one end of the screen drum

从筛鼓的一端进入
by hydraulic pressure difference

良浆靠压力差加上
the accepted stock flows through the screen plate

由转子旋转产生的离心力
by pressure difference and centrifugal force

流过筛板
generated by rotor rotation

尾浆（粗渣）由轴向推力
the tailings (coarse reject) is discharged from the other end

从筛浆机另一端排出
of the screen machine by axial thrust

筛孔的清洁主要靠
The cleaning of the screen hole mainly depends on

转子叶片后方产生的瞬间负压
the instantaneous negative pressure or circulation movement

或环流运动及稀释水的冲刷等作用
behind the rotor blade and the flushing of diluted water

图中所示的是CX型离心筛
The figure shows the CX centrifugal screen

适用于化学浆、机械浆
which is suitable for the screening of chemical pulp

废纸浆的筛选
mechanical pulp and waste pulp

具有生产能力高
It has the advantages of high production capacity

筛选效率高
high screening efficiency

动力消耗低、纤维流失少
low power consumption, less fiber loss

操作维护简单等优点
and simple operation and maintenance, etc.

接下来，让我们来看一下压力筛
Next, let's take a look at the pressure screen

压力筛最初是从
The pressure screen was originally

A型离心筛发展而来的
developed from Type-A centrifugal screen

主要特征是密封条件下
The main characteristic is that under the condition of sealing

向压力切向进浆
the pulp is fed in the tangential direction of the pressure

良浆在压力差作用下
Under the action of pressure difference

通过筛板
the accepted stock passes through the screen plate

粗渣留在筛板表面
the reject remains on the surface of the screen plate

由水力推向下方排除
and is discharged to the bottom by hydraulic pressure

筛板的清洁净化靠
The cleaning of the screen plate is realized

转子叶片旋转产生的
by the instantaneous pressure pulse

瞬间压力脉冲来实现
generated by the rotation of rotor blades

主要结构由筛框、转子
The main structure is composed of

机壳三部分组成
screen frame, rotor and housing

这就是压力筛常见的筛框
This is the common screen frame of pressure screen

开口可以是孔，也可以是缝
The opening can be holes or slots

这是压力筛的常见的转子
This is a common rotor of the pressure screen

有阶梯型转子、罗茨转子
which has stepped rotor, Roots rotor

缓冲块转子和叶片转子
buffer block rotor and blade rotor

这是压力筛的机壳
This is the housing of the pressure screen

构建了一个密闭的空间\ N which builds an airtight space

以旋翼压力筛为例
Take the selectifier as an example

说明其工作过程
to illustrate its working process

如图所示
As shown in the figure

当浆料以一定的压力
when the pulp enters the inside of the screen drum

沿着切线进入筛鼓内部
at a constant pressure along the tangent

将会自上而下的移动
it will move from top to bottom

良浆在筛鼓内外
and the accepted stock will pass through the screen holes

压力差作用下
under the action of pressure difference

通过筛孔
between the inside and outside of the screen drum

立式旋翼筛转子上
There are generally 2-3 blades

一般有2-3块叶片
on the rotor of the selectifier screen

转子叶片旋翼面
and the gap between the selectifier surface of the rotor blades

与筛鼓之间的间隙很小
and the screen drum is very small

当旋翼沿筛鼓表面运动时
When the selectifier move along the surface of the screen drum

旋翼的头部附近浆料
the pressure difference of the pulp

所受的压力差增大
near the selectifier head increases

随着尾部与筛鼓的间隙渐增
and as the gap between the tail and the screen drum increases

在这一区域内出现局部负压
local negative pressure appears in this area

当产生的负压使筛鼓内外
When the generated negative pressure makes the absolute value

浆料压力的绝对值相等时
of the pulp pressure inside and outside the screen drum equal

浆料停止通过筛孔
the pulp stops passing through the screen holes

当负压继续增加
and when the negative pressure continues to increase

筛鼓外的良浆
the accepted stock outside the screen drum

即通过筛孔返回筛鼓内
returns to the screen drum through the screen holes

起反冲黏附在筛孔上的浆团
playing the role of recoiling of the pulp lump

和粗大纤维的作用
and the coarse fiber attached to the screen hole

这样就保证了筛浆机工作的正常进行
This ensures the normal operation of the screen

旋翼后缘处
At the tail edge of the selectifier

造成的负压最大
the generated negative pressure is the greatest

旋翼经过后
After the selectifier passes

负压减小
the negative pressure decreases

浆料又依靠压力差
the pulp depends on the pressure difference

及另一个旋翼的推动
and another selectifier’s push

再次向外流动，开始下一个循环
flows outward again to start the next cycle

在此过程中
In this process

旋翼运动引起的负压大小
the negative pressure caused by the motion of selectifier

决定于旋翼断面形状
is determined by the shape of the selectifier section

和它与筛鼓内壁的距离
and the distance between it and the inner wall of the screen drum

而筛孔畅通程度则与
And the unobstructed degree of screen holes

负压大小
is proportional to the value of the negative pressure

旋翼运动速度的平方
the square of the selectifier speed

和旋翼通过的次数成正比
and the number of times the selectifier passes through

以上是压力筛的工作原理
Above is the working principle of pressure screen

接下来来看一下压力筛的分类
Next, let’s have a look at the classification of pressure screens

按照良浆流向、转子形状
According to the characteristics of accepted stock flow direction

与安装位置及运动部件等特征
rotor shape, installation position and moving parts, etc.

压力筛可以分为
the pressure screens can be classified into

单鼓内流式、单鼓外流式
single-drum inward-flow type, single-drum outward-flow type

和内外双鼓式等形式
and inner and outer double-drum type, etc.

如图所示
as shown in the picture

对于压力筛
In terms of pressure screen

我们这里还要介绍一种较为典型的产品
I will introduce a more typical product here

其纸浆筛选浓度比较高
Its pulp screening consistency is relatively high

可以达到2%~5%
which can reach 2%~5%

我们称之为高浓压力筛
and we call it high consistency pressure screen

它具有两个特点
It has two characteristics

一是纸浆浓度高
one is high pulp consistency

二是产量高
and the other is high yield

那么这种高浓筛选的
So what is the energy consumption

能耗又是怎样的呢
of this high consistency screening

我们来分析一下
Let's analyze it

筛选浆料浓度
For the low consistency screening

低于2%的低浓筛选
with the screening consistency lower than 2%

每吨绝干浆的纸浆通过量约为70~140m3
the pulp throughput per ton of bone dry pulp is about 70~140m3

而筛选浆料浓度为
while the screening consistency is

2~5%的高浓筛选时
the high consistency screening of 2~5%

每吨绝干浆的纸浆通过量仅为30~50m3
the pulp throughput per ton of bone dry pulp is only 30~50m3

也就是说，高浓筛选
That is to say, the energy consumption of high consistency

每筛选一吨绝干浆的能耗
screening per ton of bone dry pulp

与低浓筛选相比
is significantly reduced compared with that

是显著减少的
of the low consistency screening

另外，由于筛选浓度高
In addition, because of the high screening consistency

高浓筛选系统不像
the high consistency screening system is not

低浓筛选系统那样
the same as the low consistency screening system

需要循环输送大量的水
which needs to circulate a large volume of water

因此，从整个筛选系统来看
Therefore, from the whole screening system

高浓筛选系统所消耗的能量更低一些
the energy consumption of high consistency screening system is lower

这是这种高浓压力筛的优势之一
This is one of the advantages of this high consistency pressure screen

但是，作为一种压力筛
However, as a kind of pressure screen

它在运行中同样也会遇到
it will also encounter the typical

典型的筛板增浓现象
screen plate thickening phenomenon in operation

什么是筛板增浓
What is screen plate thickening

先来解释一下
Let's explain it first

在筛选过程中
In the screening process

由于水比良浆更容易
because the water is easier to pass through the screen holes

通过筛孔或者筛缝
or the screen slots than the accepted stock

因此，从进浆口到排渣口
therefore, there is a thickening phenomenon of pulp

存在浆料的增浓现象
from the inlet to the reject discharge port

这就是筛板增浓
which is the thickening of the screen plate

筛选浆料浓度增高时
When the consistency of screening pulp increases

这种增浓现象会更明显
the phenomenon of thickening will be more obvious

从这张示意图中我们也可以看出
From this diagram, it can also be seen

由于筛板表面的增浓现象
due to the thickening phenomenon on the screen plate surface

实际上是只有大约三分之一到二分之一的筛板表面
only about one-third to one-half of the screen plate surface

起到了有效的筛选作用
actually plays an effective screening role

这个从进浆到排渣的筛选表面
According to the consistency of pulp

按照浆料浓度的不同
the screening surface between pump feeding to reject discharging

可以分为上区、中区
can be classified into three areas

和下区三个筛选区域
upper area, middle area and lower area

在上区，因为浆料浓度较低
In the upper area, because the pulp consistency is lower

切线速度高
and the tangential velocity is high

大部分水和纤维通过筛板
most of the water and fiber pass through the screen plate

保持了一定的筛选效率
maintaining a certain of screening efficiency

同时也由于浓度低
At the same time, due to the low consistency

转子输入了过量的能量
the rotor input excessive energy

部分动能被浪费
and part of the kinetic energy is wasted

在中区，浆料浓度和
In the middle area, the pulp consistency

切线速度适中
and tangential velocity are moderate

纸浆流所具有能量
and the energy of the pulp flow

恰好达到流体化的要求
is just up to the requirement of fluidization

从而这一区域筛选效率高
so that the screening efficiency of this area is high

但生产能力比上区要低
but the production capacity is lower than that of the upper area

而在下区
While in the lower area

由于浆料浓度增高
due to the increase of pulp consistency

切线速度过低
and too low tangential velocity

转子旋转所补充的能量
the energy supplemented by the rotor rotation

也不能使纸浆流体化
can’t fluidized the pulp

能量被大量消耗
the energy is consumed in large quantities

容易形成纤维网络塞体
which is easy to form the fiber network plug

并导致筛孔（或筛缝）的堵塞
and lead to the blockage of the screen holes (or screen slots)

由此可见，筛板表面的
It can be seen that this thickening phenomenon

这种增浓现象
on the surface o f the screen plate

会造成高浓筛选过程的
will make it more difficult to optimize

优化更为困难
the high consistency screening process

那么如何消除高浓筛选时的
So how to eliminate the thickening phenomenon

增浓现象呢
in high consistency screening

目前主要是从两个方面去加强
At present, it is mainly strengthened from two aspects

一是优化筛板的结构
First, to optimize the structure of the screen plate

采用波形筛板和齿形筛板
adopt the corrugated screen plate and toothed screen plate

提升筛板的筛选能力
and enhance the screening capacity of the screen plate

二是改变旋翼的结构
second, to change the structure of the selectifier

采用鼓泡型或多叶片型旋翼等
and adopt the bubbling type or multi-blade selectifier, etc.

增宽旋翼作用面
widen the selectifier action surface

增加真空抽吸长度
and increase the vacuum suction length

使在正压时
making a large amount of water

通过筛孔的大量水
passing through the screen holes in positive pressure

处于负压脉冲时又重新返回进浆侧
return to the pulp side in the negative pressure pulse

这样良浆沿筛板的
so that the consistency of the accepted stock

浓度保持一致
along the screen plate maintains consistent

避免了筛板表面的增浓现象
and the phenomenon of thickening on the surface of screen plate is avoided

达到如图所示的进浆
achieving the same consistency of the feeding pulp

良浆和渣浆浓度一样
accepted stock and reject as shown in the figure

保证了筛浆机在高浓下正常运行
which ensures the normal operation of the screen under high consistency

由于高浓筛浆机节约用水
Because of saving water

节省动力消耗
saving power consumption

杂质去除效率高
and high impurity removal efficiency

所以具有很好的发展前景
the high consistency screen has a good development prospect

现已广泛地应用于废纸浆
It has been widely used in the screening of waste pulp

化学浆及机械浆的筛选
chemical pulp and mechanical pulp

此外，还可以作为纤维分级设备
In addition, it can also be adopted as fiber grading equipment

分离长纤和短纤
to separate long fiber and short fiber

以上就是本节筛选设备所要介绍的内容
That's content for the screening equipment of this section

谢谢大家
Thank you