Steps
Step 1
Property Data Acquisition
The core task of this step is to obtain and regress thermodynamic property parameters of pure substances and mixtures, providing basic data for subsequent phase equilibrium calculations and energy balances. Accurate property data is the cornerstone of chemical engineering design calculations, directly affecting process design reliability and economics. Obtained through multiple approaches: database query, experimental measurement or theoretical estimation.
• Obtain basic property data such as critical parameters, acentric factors, and saturation vapor pressures from NIST Chemistry WebBook, DIPPR database or Aspen Properties
• Select Peng-Robinson or SRK equation of state, regress binary interaction parameters kij using least squares method
• Validate regression results against experimental data, ensuring average relative error is less than 5%
Deliverable: Property parameter table (including pure substance critical parameters, EOS parameters, binary interaction parameters, validation data) | Quality standard: Deviation from experimental data <5%, complete parameters
Step 2
Phase Equilibrium Calculation
This step performs detailed calculations of chemical engineering processes, obtaining quantitative design parameters and performance indicators. Calculation is the core means of chemical engineering design, providing quantitative basis for process design through material balance, energy balance and equipment calculation. Must strictly follow chemical engineering design specifications and standards, ensuring accurate and reliable calculation results.
• Determine calculation methods and formulas, clarify theoretical basis and assumptions, draw calculation flow chart
• Perform process simulation calculations using Aspen Plus or PROII, obtain material stream data and equipment parameters
• Manually verify key calculation results, cross-validate through empirical formulas or simplified models, ensuring calculation accuracy
Deliverable: Calculation document (including calculation formulas, calculation process, result data table, simulation files, validation comparison) | Quality standard: Correct calculation method, clear process, accurate results, sufficient verification
Step 3
Energy Balance
This step performs detailed calculations of chemical engineering processes, obtaining quantitative design parameters and performance indicators. Calculation is the core means of chemical engineering design, providing quantitative basis for process design through material balance, energy balance and equipment calculation. Must strictly follow chemical engineering design specifications and standards, ensuring accurate and reliable calculation results.
• Determine calculation methods and formulas, clarify theoretical basis and assumptions, draw calculation flow chart
• Perform process simulation calculations using Aspen Plus or PROII, obtain material stream data and equipment parameters
• Manually verify key calculation results, cross-validate through empirical formulas or simplified models, ensuring calculation accuracy
Deliverable: Calculation document (including calculation formulas, calculation process, result data table, simulation files, validation comparison) | Quality standard: Correct calculation method, clear process, accurate results, sufficient verification
Step 4
Exergy Analysis
This step performs thermodynamic analysis and exergy analysis of chemical processes, revealing process energy utilization efficiency and irreversible losses. Exergy analysis is an advanced method for evaluating process energy quality, quantifying exergy losses of each unit based on the second law of thermodynamics, identifying weak links in energy utilization. Provides directional guidance for energy-saving retrofitting and process optimization.
• Determine environmental state parameters (T0, P0), calculate enthalpy, entropy and exergy values of each stream, establish exergy balance equations
• Calculate exergy loss and exergy efficiency of each unit equipment, identify key equipment with maximum irreversible loss
• Plot heat integration temperature-enthalpy diagram (T-H diagram) and pinch analysis, determine minimum utility consumption and energy saving potential
Deliverable: Exergy analysis report (including exergy balance table, unit exergy loss distribution diagram, pinch analysis diagram, energy saving potential assessment) | Quality standard: Exergy balance closed, clear loss distribution, reasonable energy saving potential analysis
Step 5
Optimization Scheme and Report
This step performs optimization design of chemical processes, seeking the optimal techno-economic solution under constraint conditions. Chemical engineering optimization involves multi-objective decision-making, requiring balance among investment, energy consumption, operating cost and product quality. Systematically search the optimal solution space using a combination of process simulation and mathematical programming methods.
• Determine optimization objective function (e.g., minimum annualized total cost, maximum NPV) and constraint conditions (production, purity, safety and environmental protection, etc.)
• Perform single-parameter and multi-parameter optimization using Aspen Plus sensitivity analysis or Aspen Optimization
• Conduct techno-economic evaluation, calculate payback period, IRR and other indicators, compare performance before and after optimization
Deliverable: Optimization design report (including optimization model, parameter optimization process, techno-economic analysis, before-after comparison, recommended scheme) | Quality standard: Clear optimization objectives, scientific method, significant effects, feasible solution