plant design 401

FST 401: Food Plant Design and Pilot Demonstration

MODULE 1: Experimentation in Pilot Layout

Size and Structure of the Pilot Plant
Pilot Plant Definition

The pilot plant serves as a physical model that is a scaled-down version of a corresponding industrial unit. The equipment in this setup is typically smaller in size, ranging from approximately 1/100 to 1/10 of the industrial unit. Pilot plants facilitate experiments that yield extensive data and information across several areas:

  1. Market Survey: Allows the production of a specific amount of a new product to gauge market acceptance and assess economic viability.
  2. Design Data: Provides insights on the behavior of operations or unit processes under conditions that cannot be replicated in a laboratory environment.
  3. Products and Raw Materials: Helps in characterizing food products and evaluating the conversion of specific raw materials into desired products.
  4. Optimization Data: Assists in improving the performance of an operational plant.
Basic Principles of Scaling

The determination of the size and configuration of the pilot plant relies heavily on the principle of similarity, initially introduced by Newton. When fluids are processed, three key types of similarities in fluid dynamics must be achieved:

  1. Geometric Similarity: The pilot plant and the full-scale food processing plant should exhibit identical physical forms or, at the very least, comparable geometric dimension relationships.
  2. Kinematic Similarity: Velocity relationships should remain consistent between the pilot and full-scale plants.
  3. Dynamic Similarity: Force relationships should remain comparable, ensuring that turbulence regimes are similar across scales.

In cases where chemical processes are involved, additional similarities to consider include:

  1. Thermal Similarity.
  2. Chemical and Biochemical Similarity.
Minimum and Maximum Size

The size constraints of a pilot plant are influenced by various factors:

  • Minimum Size: Determined by the least amount of product necessary for quality analytical control.
  • Maximum Size: Defined by the quantity of processed product essential for market acceptance testing.
Types and Applications

A pilot plant is termed a semi-commercial plant when it produces sufficient quantities for market acceptance tests. Common applications of pilot plants include:

  1. Product Studies: Quality characterization, analysis of process conditions on product quality, new product development, and market acceptance studies.
  2. Raw Material Studies: Characterization of raw materials and assessment of their feasibility for industrialization.
  3. Process Technology and Engineering Studies: Optimization of process conditions for economic viability and product quality, analysis of equipment alternatives for food processing, and development of new technologies and equipment.
  4. Auxiliary System Requirement Studies: Evaluation of mass and energy balances, analysis of energy recovery opportunities, and enhancement of alternative control systems.

MODULE 2: Engineering Economy

Introduction

Engineering Economy pertains to the quantitative techniques used to evaluate engineering alternatives based on financial metrics. Economic decisions are crucial in production systems engineering, particularly when:

  • Introducing new products or services or phasing out existing ones.
  • Choosing between various production technologies.
  • Selecting plant location and design.
  • Making equipment replacement decisions.
Important Terms of Engineering Economy
  1. Time Value of Money: Defined as the value of money changing over time due to inflation and potential returns from alternate investments.
    • Reasons why N1000 today is more valuable than N1000 a year later include:
      • Inflation
      • Risk
      • Cost of money.
  2. Inflation: The gradual decrease in purchasing power due to economic factors.
  3. Interest: The cost incurred for borrowing money, typically paid back to lenders.
  4. Interest Rate: The ratio of interest paid over a specified period to the principal amount borrowed, commonly expressed as a percentage.
  5. Compound Interest: Interest calculated on the total balance (principal plus interest) at the beginning of each time period for a loan longer than one period.
  6. Rate of Return: The ratio of net profits to the investment made, indicating the profitability of the investment.
  7. Attractive Rate of Return: The benchmark rate used by a company to evaluate investment proposals.
  8. Payment: Any amount of money spent by a production entity, which includes costs for materials, wages, etc.
  9. Receipt: Money received from sales or services; total income.
  10. Cash Flow: The detailed account of incoming and outgoing cash over a specific period.
  11. Sunk Costs: Historical costs that are no longer relevant to future decision-making.
  12. Opportunity Costs: The potential returns lost when investing resources in one alternative over another.
  13. Asset: Valuable resources owned by a company, such as land, buildings, and machinery.
  14. Life of an Asset: Can be categorized into three types:
    • Actual/Technological Life: Duration for which an asset functions effectively.
    • Accounting Life: Duration for which the asset’s cost must be amortized through profits.
    • Economic Life: The period during which the asset generates economic benefits.
  15. Depreciation: The process of allocating the cost of an asset over its useful life, affecting annual tax and profits calculations.
  16. Book Value of an Asset: The cost less accumulated depreciation.
  17. Salvage Value: The value an asset is expected to realize upon sale at the end of its useful life.
  18. Replacement: The acquisition of a new asset to replace an old one, maintaining similar functionality.
  19. Defender and Challenger: The existing asset (Defender) compared to the new asset proposed for replacement (Challenger).
  20. Retirement: This refers to the disposal of an asset through sale or abandonment.

MODULE 3: Methods of Economic Evaluation of Engineering Alternatives

Types of Economic Evaluation Methods

There are primarily two categories of methods for evaluating engineering alternatives:

  1. Undiscounted Cash Flow Methods: Future cash flows are not discounted.
    • Pay Back Period Method: Determines the time frame required for profits to equal the original investment.
  2. Discounted Cash Flow Methods: These methods account for the time value of money, comprising three specific methodologies:
    A. Net Present Value Method: Calculates the present worth of future cash receipts and payments, using a discount rate that meets the company's acceptable rate of return. A positive NPV indicates that the investment exceeds the attractive rate of return.
    B. Equivalent Annual Cost Method: Converts a series of cash flows into an equivalent annual amount, allowing for the comparison of alternatives based on cost.
    C. Rate of Return Method: Estimates the expected rates of return for different options, choosing the one with the highest expected return by iteratively adjusting the discount rate until an acceptable net present value is achieved.
Cost-Benefit Analysis

This analysis is vital for assessing the feasibility of substantial government engineering projects. The choice of alternatives is based on either maximizing net social benefits or yielding the highest rate of return based on all associated social costs and benefits:

  • Social Costs: Encompasses both government investments and social costs borne by affected community members.
  • Social Benefits: Encompasses revenues and positive impacts on the community resulting from the project.
Procedure
  1. Identify project alternatives and enumerate all potential social costs and benefits associated with each.
  2. Evaluate costs and benefits in monetary terms for the lifecycle of the project.
  3. Construct a cash flow diagram to depict costs and benefits over time and determine net social benefit using an appropriate social rate of return.
  4. Select the alternative that maximizes social benefit or return.

MODULE 4: Materials of Construction of Food Equipment

Characteristics of Suitable Construction Material

Materials used in food processing equipment must exhibit the following:

  1. Corrosion Resistance: They must withstand harmful actions from food and cleaning agents.
  2. Surface Finish: Should prevent dirt accumulation; smoother surfaces encourage cleanliness.
  3. Mechanical Behavior: Must possess strength, resist abrasion, and tolerate physical or thermal shocks.
Types of Materials and Applications
  1. Stainless Steel: The primary choice for food equipment. AISI 304 is the most prevalent form used. AISI 316 is recommended for highly corrosive environments.
    • Corrosion Resistance Mechanism: Stainless steel develops a chromium oxide layer when exposed to air, enhancing resistance to corrosion. This layer can be intensified by treatment with nitric acid.
  2. Aluminum: Known for excellent thermal conductivity, yet less corrosion resistant than stainless steel; effective under specific conditions but vulnerable to alkalis.
  3. Nickel and Monel: High resistance to corrosion in certain applications, Monel is preferable for salt processing systems.
  4. Plastic Materials: Used across various applications such as food packaging and process equipment.

MODULE 5: Maintenance of Food Plant Building

Maintenance Practices
  • Painting: Essential for equipment and structures to enhance operational life and improve aesthetics. Special paints for concrete surfaces must be selected to prevent deterioration from exposure to elements.
  • Safety Color Code: A standardized system to identify hazards and safety equipment using designated colors, improving operational safety.
  • Roof Inspection: Biannual inspections are crucial to prevent roof deterioration due to environmental exposures.
  • Concrete Floor Care: Methods to clean, repair, and maintain concrete surfaces to ensure longevity and safety in plant operations.

MODULE 6: Cleaning and Sanitization

Importance of Cleaning

Integral to food process design and operation, equipment must be designed for easy cleaning and sanitation to remove waste products and prevent contamination.

Cleaning Techniques

CIP (Cleaning In Place): A systematic cleaning approach that includes several stages, from pre-rinsing to using chemical solutions, ensuring all equipment surfaces are thoroughly sanitized.

Sanitation Definition

Sanitation in the food industry involves creating healthful conditions to reduce the risk of foodborne illnesses and contamination, which goes beyond mere cleanliness.

MODULE 7: Process Scheduling

Significance of Scheduling

Effective scheduling is critical for optimizing productivity in manufacturing, focusing on resource allocation, cost reduction, and meeting delivery timelines.

Algorithms for Scheduling

Involves using heuristic algorithms to streamline production scheduling and improve overall manufacturing efficiency by addressing complex scheduling scenarios.

MODULE 9: Illumination and Ventilation

Illumination
  • High-quality lighting promotes safety and productivity, with specific lighting standards to maintain efficiency in work areas. Radiation levels and color reflectivity significantly affect worker comfort and efficiency.
Ventilation
  • Necessary for ensuring air quality in processing areas, removing unwanted air while conditioning the environment to enhance comfort and safety. Specific filtration and positive pressure conditions may apply in sensitive areas.