Economic life comparison — large vs. small chemical process plants The economic life of a large chemical process plant, compared with that of a small plant, is typically:

Introduction / Context:
Economic life is the optimal operating period that minimizes the equivalent annual cost or maximizes economic return before replacement. It is influenced by obsolescence, maintenance growth, and performance decline rather than purely by physical durability.

Given Data / Assumptions:

• Compare large vs. small chemical plants under typical market and technology conditions.
• Economic life is defined by cost optimum, not the last day equipment can physically run.
• All else equal (maintenance practices, product market), scale primarily affects capital intensity.

Concept / Approach:
Larger plants enjoy economies of scale in capital and operating costs but face similar technological obsolescence and market shifts as smaller units. Because economic life is dominated by obsolescence and maintenance escalation, scaling up size does not proportionally extend the optimum replacement time. Textbook rules of thumb therefore state that large plants have an economic life only slightly longer than small plants, not dramatically longer.

Step-by-Step Solution:
Identify dominant factors: obsolescence, maintenance cost growth, regulatory changes.Recognize that these are largely independent of absolute size.Infer that any extension in economic life with size is modest, not “much more.”Select the option reflecting a small increase.

Verification / Alternative check:
Practice examples show economic life often clustering in comparable ranges (e.g., 6–12 years) across sizes for similar technologies.

Why Other Options Are Wrong:

• Much more: overstates the effect of scale on obsolescence.
• Slightly less / Almost equal: do not reflect the small but positive tendency for larger units to remain competitive slightly longer.

Common Pitfalls:

• Equating physical life or design life with economic life.
• Assuming economies of scale automatically extend useful economic life greatly.

Final Answer:
Only slightly more