The success, cost-effectiveness, and sustainability of turnkey food factory projects largely depend on the rigorous application of process engineering discipline. This article examines the process engineering activities that form the backbone of the installation process. Within its scope, the importance of fundamental process calculations (capacity, mass balance, energy), Process Flow Diagrams (PFD), and Piping & Instrumentation Diagrams (P&ID) is detailed, and equipment selection criteria are optimized based on process, hygiene, cost, and flexibility parameters. In conclusion, it is emphasized that process engineering is not a cost item but a vital investment for efficiency and profitability.

The “turnkey” concept encompasses all processes from the physical structure of a food factory to the delivery of a fully operational production line. At the center of these processes lies process engineering, which defines, scales, and optimizes the transformation of raw materials into final products. An investment made without process engineering is like an unplanned journey; unexpected bottlenecks, hygiene risks, high energy costs, and poor quality production are inevitable. This article will examine the cornerstones of this critical process.

Process Engineering Calculations: The Foundation of the System

All design is built on accurate and consistent calculations. These calculations can be grouped under three main headings.

Mass Balance Calculations
Mass balance is based on the principle of “input = output”. It must be performed for each process unit and the entire system.

• Purpose: To determine raw material requirements, intermediate product quantities, final product yield, and waste (pomace, steam, etc.) amounts.

• Calculation Example (Fruit Juice Concentrate):

  • Input: 1000 kg/hour of apple (20% solids, 80% water)

  • Desired output: Concentrate containing 70% solids.

  • The amount of water vapor (W) exiting the evaporator is calculated.

  • Total Mass Balance: 1000 = W + Concentrate

  • Solids Balance: (1000 * 0.20) = (W * 0) + (Concentrate * 0.70)

  • Equation solved: 200 = 0.70 * Concentrate → Concentrate = 285.7 kg/hour

  • W = 1000 – 285.7 = 714.3 kg/hour of water must be evaporated.

  • This data is the basis for evaporator capacity, condenser, and cooling tower selection.

Energy Balance Calculations
Determines how much energy processes require for operations such as heating, cooling, and evaporation.

• Purpose: To optimize equipment capacities (heat exchangers, boilers, chillers) and energy costs.

• Calculation Example (Milk Pasteurization):

  • Process: Heat milk from 5°C to 72°C, hold for 15 seconds, cool to 5°C.

  • Capacity: 5000 kg/hour.

  • Energy required for heating (Q_heat): Q = m * Cp * ΔT

    • m: mass flow rate (5000 kg/hour)

    • Cp: specific heat of milk (~3.9 kJ/kg°C)

    • ΔT: temperature difference (72-5=67°C)

  • Q_heat = 5000 * 3.9 * 67 = ~1,306,500 kJ/hour

  • This energy requirement is used for sizing the plate heat exchanger and determining hot water needs. This cost can be significantly reduced with energy recovery (regeneration).

Equipment and Capacity Calculations
Equipment is sized using the data from mass and energy balances.

• Example: In the fruit juice example above, the required evaporator surface area to evaporate 714.3 kg/hour of water is calculated using heat transfer coefficients and temperature differences. Storage tanks are sized considering processing times (holding time) (e.g., to accommodate 2 hours of production).

Flow Diagrams: The Visual Roadmap of the Process

Calculations are meaningless unless visualized with diagrams.

Process Flow Diagram (PFD)

• Purpose: To show the main components and flow direction of the process. Includes equipment, main flow lines, and basic control points. Does not contain detailed piping and instrumentation information.

• Contents:

  • Major equipment (tanks, pumps, heat exchangers, fillers, etc.)

  • Main flow lines and flow directions.

  • Key process parameters (temperature, pressure, flow rate).

  • Basic control points.

• Importance: Creates a common language among all stakeholders (investor, engineer, production team). It is the first step in understanding the process.

Piping and Instrumentation Diagram (P&ID)

• Purpose: To create the final working document for engineering, procurement, installation, and automation teams. It is where every component on the PFD is detailed—it contains the “DNA of the process”.

• Contents:

  • All pipes, their diameters, fluids, and insulation information.

  • All valves (manual, automatic, shut-off, control, check) and their types.

  • All instruments (temperature, pressure, level, flow transducers/transmitters).

  • Tank, pump, and equipment nozzle details.

  • Control system (PLC/SCADA) input/output (I/O) points and control logic.

• Importance: Hygienic design (drainage, cleanability, prevention of dead legs), automation strategy, maintenance planning, and operating procedures are all managed through the P&ID. Correcting an error at the P&ID stage is hundreds of times cheaper than correcting it on site.

Optimization of Equipment Selection Criteria

Correct equipment selection directly impacts process efficiency, product quality, and total cost of ownership (TCO).

Optimization Scenario: Selecting a Homogenizer

• Capacity: 5,000 kg/hour.

• Option 1: Low-priced model with standard surface finish (Ra > 1.0 µm) and difficult-to-source spare parts.

• Option 2: 20% more expensive model with a Ra ≤ 0.8 µm surface finish, CIP compatible, energy efficient, with a local service network, and EHEDG certified.

• Optimization Decision: Option 2 should be chosen. Justification: Lower energy costs, shorter cleaning time (more production hours), less CIP chemical consumption, longer lifespan, and lower product quality risk will amortize the initial price difference in the medium term and accelerate profitability.

In a turnkey food factory setup, process engineering is not just an “engineering discipline” but also a “risk management and optimization” process. Well-defined mass and energy balances, a clear PFD, and an extremely detailed P&ID are essential for the project. Equipment selection is not just a purchasing decision but a strategic choice that directly influences the future efficiency and profitability of the operation.

The advice to investors and project managers is not to skip the process engineering stages or to allocate the necessary budget and time to these stages. Every unit of investment made in process engineering will return multifold during the operational phase. This is the most scientific and economical way of “doing the right thing, the right way.”