Plate-and-frame filter press construction: the slurry is introduced through a port in each frame. What surface geometry does the mating plate typically have to provide drainage channels?

Introduction / Context:
In plate-and-frame presses, frames form cavities to hold cake, while plates support the cloth and provide filtrate drainage paths. Surface geometry of plates is crucial to reduce cloth blinding and allow filtrate to exit uniformly.

Given Data / Assumptions:

• Classical plate-and-frame construction.
• Slurry introduced via frame ports; filtrate flows along the plate.

Concept / Approach:
Plates are cast or machined with ribs or grooves. The ribbed pattern keeps the cloth off the solid surface locally, creating channels that collect filtrate and route it to corner ports. A plane plate would flatten the cloth and restrict flow; curving alone does not create uniform channels.

Step-by-Step Solution:
Identify design function: provide drainage under the cloth.Design feature: ribbed/grooved plate face.Answer: ribbed.

Verification / Alternative check:
Press manuals illustrate diamond or herringbone rib patterns to support cloth and promote drainage.

Why Other Options Are Wrong:
Plane/curved plates without ribs cannot maintain continuous drainage channels everywhere across the face.

Common Pitfalls:
Confusing recessed-chamber presses with true plate-and-frame; both use ribbed faces for drainage.

Final Answer:
ribbed