Distillation hardware and practice: pick the correct statement about condensers, tray details, packing, and riser attachment.

Introduction / Context:
Column internals—trays, downcomers, risers, and packings—must be designed for hydraulic performance and maintainability. Ancillary equipment like condensers also follows best practices depending on whether total or partial condensation and subcooling are required. This question asks for the correct statement among several commonly misunderstood points.

Given Data / Assumptions:

• Conventional trayed distillation column.
• Standard random and structured packings.
• Normal operating ranges, not special cases.

Concept / Approach:
Weep holes are small openings that allow draining of residual liquid from trays during shutdown to prevent pooling and corrosion. Random packing generally has higher pressure drop than structured (regular/stacked) packing at similar capacity; structured packings excel in low pressure drop and high capacity factors. Preferences for condenser orientation depend on duty: horizontal condensers are often selected for condensing with significant non-condensables or where no subcooling is needed; vertical units are common too but not universally preferred in the stated way. Riser attachments are normally secure and positive; saying they are “generally not connected” is misleading.

Step-by-Step Solution:

Verification / Alternative check:
Vendor manuals and TEMA/standards for columns corroborate weep-hole use and structured packing advantages in low ∆P service.

Why Other Options Are Wrong:

• (a) Overgeneralizes condenser orientation without context.
• (c) Reverses the established pressure-drop comparison.
• (d) Misstates mechanical practice; secure attachment is standard.

Common Pitfalls:
Assuming one condenser orientation is always best; in reality, subcooling target, condensate drainage, and non-condensables govern selection.

Final Answer:
Weep holes on trays facilitate draining of residual liquid during column shutdown