Recessed plate and membrane plate 压滤机es 是由一个坚固的框架组成的，这个框架容纳了一系列衬有过滤介质的板.
The plates are held tightly together using hydraulic pressure, and a high pressure slurry feed pump is used to force slurry material into the void spaces between the plates.
浆液固体在板之间被捕获，而滤液水通过板表面的滤布.
When no additional slurry can be pumped into the 压滤机, the slurry feed pump is stopped and the plates are separated, allowing the cakes to fall by gravity out of the press.
What is a 压滤机 cycle?
通过设计, 凹板式和膜板式压滤机的脱水工艺为间歇式工艺. A series of process steps occur to complete the batch process, and all of the steps combined are referred to as a 压滤机’s dewatering cycle.
A typical plate 压滤机 cycle is made up of the following steps:
- Filter plate closing/clamping
- 填充
- Ramp/Filtration
- Core blow (optional)
- Cake dry (optional)
- Membrane squeeze (optional)
- Filter plate unclamping and opening
Filter plate closing/clamping step
The filter plates are closed together using a hydraulic cylinder and mobile plate. Lower pressure is required to first close the plate stack, then very high hydraulic pressure clamps the plates tightly together.
夹紧液压需要足够高，以承受浆液进料泵将浆液推入滤板之间空隙所产生的压力.
填充步骤
启动进料泵，以便它可以开始填充夹紧滤板之间的空隙.
在这个填充步骤中，浆料进料速率可以很高，进料压力很低.
To help reduce cloth wear around the filter plate feed hole areas, the fill flow rate is limited by controlling the pump speed. 这个有限的流量保持恒定，直到达到最小的给水泵压力.
Ramp/Filtration step
Once the minimum feed pressure is reached in the fill stage, 在一段时间内，进料泵的转速提高以增加进料压力.
增加给水泵转速，直到达到目标过滤级压力. The pressure is held constant for the balance of the filtration stage.
As the filtration step continues, 由于滤板之间的空隙被脱水的浆液固体填满，浆液流速下降.
当浆液流量达到预设的最小水平，并停止给料泵时，过滤阶段结束.
Core blow step (optional)
After the feed pump is stopped, some amount of slurry remains in the core hole areas of the filter plates. 吹芯步骤使用冲洗水和/或压缩空气去除剩余的泥浆.
Flush water is first forced through the core to push the slurry out, 然后，压缩空气被强行通过核心孔推出冲洗水和任何剩余的泥浆.
The slurry and water are typically forced back to the slurry surge tank, where they can be fed back to the press in subsequent cycles.
Cake dry step (optional)
To remove additional water in the cakes, 压缩空气被强制通过滤饼，而饼仍然被保持在滤板.
这通常用于蛋糕材料非常多孔和蛋糕水分要求非常低的情况.
Membrane squeeze step (optional)
Similar to the cake dry step, 膜挤压步骤用于在滤饼形成后从滤饼中除去额外的水.
膜板具有可弯曲的表面，可以用水或压缩空气膨胀. 膨胀的盘子表面压缩蛋糕，迫使多余的水被除去.
Filter plate unclamping and opening step
一旦所有脱水步骤完成，高液压夹紧压力解除.
气缸和活动板继续打开，为所有滤板分离腾出空间.
A plate opening system indexes each plate to open, 使脱水的饼料在重力作用下从滤板之间落下.
Once all of the cakes have been discharged, a new filter press cycle can begin.
Factors that affect cycle time
压滤机循环的每一步都需要一定的时间，这取决于被脱水的浆料的特性以及压滤机的设计.
Design factors
Key filter press design factors that can influence the cycle time include:
- Chamber thickness
- Slurry Pump feed pressure
- Filter plate opening and closing speed
- Filter cloth design
Chamber thickness
由于滤板之间脱水的浆液体积较大，因此腔室厚度较大的滤板需要更长的填充和过滤时间.
Slurry Pump feed pressure
Filtration time typically can be reduced with higher slurry feed pump pressures.
只有在不同进料压力下测试具有代表性的样品材料，才能确定在较高进料压力下实现的时间减少. 大多数现代压滤机设计在100 psi和225 psi的最大压力之间运行.
For special dewatering applications, higher feed pressures are possible.
Filter plate opening and closing speed
液压动力单元和液压缸尺寸将决定压滤机打开和关闭的速度. Typical hydraulic cylinder opening and closing speeds are one to 10 minutes.
The plate opening speed is also dependent on the 压滤机 plate shifting design, but it is typically one to five seconds per plate.
Filter cloth design
压滤机 cloths are typically woven synthetic fabrics made from fine nylon, polypropylene or polyester filaments. Many different types of cloth weaves and styles can be used for dewatering.
滤布的设计是为了捕获固体颗粒，并允许滤水通过. 当需要更紧密的编织布来捕获由更细粒度组成的材料时, the flow of filtrate through the cloth can be negatively impacted, extending filtration time.
根据织物的脱水特性和织物的最佳耐磨脱饼性能，选择最优的织物设计.
Key dewatering process factors that can influence the cycle time include:
- Slurry feed density (percent solids of the slurry)
- Composition of the slurry (clay, ash, coal, etc.)
- Slurry particle size distribution
- 脱水 aids
Slurry feed density
高密度的浆料通常会减少填充和过滤时间. At higher percent slurry solids, 被泵入压滤室的固体量发生得更快, resulting in reduced cycle times.
Composition of the slurry
被脱水料浆的成分会影响除水速度.
Materials that tend to absorb water — or water-loving, 亲水材料-可能很难脱水，可能需要延长过滤时间或辅助过滤.
自然排斥水的材料——或疏水材料——将更容易脱水, reducing the filtration time.
Slurry particle size distribution
Slurries with larger, 圆形颗粒比颗粒更细的浆料更容易脱水，颗粒更细的浆料更容易堆积在一起.
Fine clay materials can be very flat particles that pack tightly together, making the removal of water between them nearly impossible.
脱水 aids
When slurry materials are very difficult to dewater, dewatering aids or chemicals can be added to decrease the filtration time.
最常见的辅助材料包括珍珠岩、硅藻土(DE)和高钙水合石灰. 珍珠岩和DE是天然存在的矿物，在泥浆中提供较大的颗粒, allowing the water to be more easily removed.
加入水合石灰可以化学地使浆料更容易释放水分.
在设计压滤机时，所有这些因素都被考虑在内，以确保每个应用的最佳脱水效率.
