Process Design Learning Outcomes PDF

Process Design – Learning Outcomes Define chemical process industry (CPI) and its scope. Describe the role of CPI in Singapore. Describe the life cycles of chemical plants and products. Explain the types of process design and their continual need. List th...

Process Design – Learning Outcomes Define chemical process industry (CPI) and its scope. Describe the role of CPI in Singapore. Describe the life cycles of chemical plants and products. Explain the types of process design and their continual need. List the steps and considerations in a design project. Explain the general structure of a chemical process. Describe the overall strategy for process development. List the main sections of a typical chemical plant. Contrast continuous versus batch processes. State a recommended hierarchy for process development decisions. Copyright © IA Karimi 1  History of Chemical Industry Chemistry is at the root of chemical industry. Alchemy (original chemistry) had roots in ancient Egypt, Mesopotamia, and Greece. Alchemists sought to transform metals into gold. Jabir ibn Hayyan (Geber) during the Islamic Golden Age is often considered the father of Chemistry. He introduced experiments, apparatus, and techniques. English “Gibberish” comes from his name! Dyeing, leather tanning, and brewing were known since ages. Modern chemical industry began in UK after industrial revolution. Na2CO3 process by Nicolas Leblanc is commonly considered to be the birth of modern chemical industry. Copyright © IA Karimi 2  Key Historic Events in Chemical Industry 1746: Lead chamber process for H2SO4 by John Roebuck. 1789: Leblanc process for Na2CO3 by Nicolas Leblanc. 1850: The first oil refinery by Samuel Kier in PA, USA. 1905: Haber-Bosch process for ammonia (most important process of all times) by Fritz Haber & Carl Bosch. 1920: Large-scale industrial process for isopropanol from oil by Standard Oil Company – First process from oil. 1923: High-pressure process for methanol by BASF. 1923: Fischer-Tropsch process for synthetic liquid fuels from coal gasification. 1934: First tire from synthetic rubber, neoprene. 1939: Large-scale LDPE at ICI and PVC in Germany & USA. 1955: Large-scale process for PET (PE Terephthalate) Copyright © IA Karimi 3  What is CPI (Chemical Process Industry)? Huge and most diverse industry in the manufacturing sector. Wide variety of inorganics, organics, fuels, feedstocks, gases, pharmaceuticals, agrochemicals, ceramics, polymers, & consumer products. Consumption/production of many of these products is a measure of nation’s industrialization or economic advance. Key contributor to the economy of many advanced nations. Trade is mostly B2B vs B2C (Business-2-Consumer). Most chemicals are used to produce other chemicals. Many chemicals are used in making consumer products. Only some chemicals find direct consumer use. Copyright © IA Karimi 4  Categories of CPI Chemicals/Products Composition-based Performance-based (Commodities) (Specialties) Standard, universal grades Company-specific qualities Fungible (Undifferentiated) Non-fungible (Differentiated) High-volume, Low-margin Low-volume, High-margin Mostly B2B B2B & B2C Pharmaceuticals Fuels Agrochemicals Feedstocks Consumer Products Copyright © IA Karimi 5  Hierarchy of CPI Chemicals/Products Final Products Plastics, Pharmaceuticals, Fibers, Solvents, Detergents, Perfumes, fertilizers, insecticides (~30,000) Intermediates Bulk Chemicals Acetic acid, Formaldehyde, Urea, Ethene oxide, (~300) Acrylonitrile, Acetaldehyde, Terephthalic acid Base Chemicals Ethene, Propene, Butadiene, BTX, SynGas, (~20) ammonia, methanol, sulfur, chlorine, salt Fuels (~10) Raw Materials Air, ??, ??, ??, ?? (~10) 10 basic raw materials: air, water, coal, crude oil, natural gas, ores and Copyright © IA Karimi minerals, seawater, limestone, wood, 6 biomass  Major Industries within CPI Bulk Inorganics Oil & Gas Pharmaceuticals Petrochemicals H2 APIs PAN Acids Acids (H2SO4, HCl, Kerosene Nylon C2H6 Vaccines Alcohols HNO3, HF, …) Petrol PE/PET Diesel NGL Peptides Aldehydes Alkalies PP/PPO HFO Amino Ketones (NaOH, NH4OH, C2H4 KOH, Lime, …) LPG Acids PS Phenols NG C3H8 PEG Salts Vitamins EG LSD PTFE (Na2CO3, K2CO3, C3H6 EO NH4SO4, NaNO3, DF NH4NO3, CaSO4, PU …) ATF Naphtha Minerals BTX MGO PEster Naphthenes Feedstocks Industrial MDO PVC Gases Organics (N2, O2, He, Ar, Fuels PVA Cl2, Kr, Xe, …) API = Active Pharmaceutical Ingredient, MDO = Marine Distillate Oil, ATF = Aviation Turbine Polymers Copyright © IA Karimi Fuel or Jet Fuel, LSD = Low-Sulfur Diesel, MGO = Marine Gas Oil, DF = Distillate Fuel 7  Other CPI-Related Industries Lubricants Food & Paints & & Additives Agrochem Beverages Coatings Inhibitors Vegetable oils Fertilizers Paints Enhancers Pesticides Dairy, Sugar Pigments (fuels, flows, Insecticides Beer, Drinks Varnishes paints, polymers) Colors, Flavors Films Fragrances Coatings Preservants Adhesives Paper & Nutraceuticals Sealants Pulp Ink Catalysts Paper Personal Enzymes Notes Care Resins Soaps & Shampoos Cosmetics Electronic Detergents Textiles Soaps Lotions Solvents Inks Detergents Make-ups Photographic Dyes Cleaners Polishes Treatment Coatings Surfactants Perfumes (water) Copyright © IA Karimi 8  CPI in Singapore Manufacturing sector is a key economy driver for Singapore. It accounts for nearly 20% of Singapore’s GDP. Total manufacturing output was 447 Billion S$ in 2022. Electronics 196 Billion S$ (44%), Chemicals & Refinery 120 Billion S$ (27%), and Pharmaceutical & Biological 19 Billion S$ (4.3%). 130 Source: www.statista.com 120 Manufacturing Output (Billion S$) 110 Jurong Island hosts 100 90 >100 chemical 80 companies. 70 60 50 40 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 Year Copyright © IA Karimi 9  Competition in CPI Causes Life Cycles Product substitution (Multiple products for the same market) Polyethylene vs. polypropylene, NaOH vs. Na2CO3, LPG vs NG/TG Gasoline vs ethanol vs electricity vs hydrogen vs ammonia Precursors or reaction pathways Acrylonitrile via acetylene vs. propylene Cyclohexane via naphtha vs. benzene Phenol and methanol via three different processes Processing technologies (T, P, catalyst) Ammonia via high-P, med-P, or low-P processes Raw materials (Coal vs LNG vs petroleum vs biomass) Companies (Dow vs. DuPont, GSK vs Pfizer vs MSD, etc.) Industries: Natural vs. synthetic fibers Net result: Product/plant lifecycles & need for continual design Copyright © IA Karimi 10  S-Curve for Product/Market Life Cycle Start Mature Death Phase Phase Phase Growth Phase Cost/margin decrease over time. Copyright © IA Karimi 11  Plant Life Cycle Conception: R&D, market needs, etc. Engineering: Diagrams and plans for construction workers Construction: From diagrams to complete facility. Commissioning: Full checkup, validation, calibration, startup (zero to full production), testing, training, and handover. Operation: Profitable production over 10 to 20 years. Regular maintenance, repairs, replacements, etc. Periodic shutdowns, cleanups, and overhauls Retrofit or debottlenecking Closure & Scrap/Disposal, or Reuse Copyright © IA Karimi 12  Types of Design Projects Revamp or Retrofit: Modify or upgrade an existing plant. Increase production capacity (debottlenecking) Handle different feeds Make different products Exploit new technology Decrease emissions Improve performance, efficiency, safety, reliability, or consistency. 50% of all projects Capacity Expansion: Build/duplicate plants to increase total production. 45% of all projects Only 5% of all industrial projects build new plants based on new laboratory R&D. Copyright © IA Karimi 13  Greenfield vs Brownfield Projects Greenfield (Grass-roots) projects construct new plants on barren land plots. Plain, totally undeveloped site with no existing infrastructure or development. Brownfield projects construct new plants on sites that produced something else before. Repurpose an abandoned site for a different use. Copyright © IA Karimi 14  Key Steps in a Process Design Project Idea, Need, Design Basis, Specs, Gather Literature, Objective External Constraints Data & Information If chemical is not available on the Process Development simulation databank, use a chemical with similar properties Simulation Models to allow simulation to run (Performance & profitability) Design R&D Best Process/Design (Physical properties, Alternatives Pilot studies, …) Optimize Detailed Design Designs & Equipment Specs Procurement Commissioning Operation & Construction Copyright © IA Karimi 15  Design Basis – Project Statement Raw materials, products/byproducts, & specifications Grades, purities, impurities, storage conditions (P, T), … Plant capacity: xxx – xxx ktpa (kilo tonne per annum) Onstream time: 8000 h/y to 8256 h/y (downtime, overhauls) Potential location/s, if not fixed already. Company, local, and national design codes and standards Codes recommend various design procedures and safety margins. Safety factors (margins) allow for uncertainties in material properties, procedures, fabrication, and operation. Standards stipulate common equipment sizes, dimensions,... NIST, ANSI, API, ASTM, ASME, NFPA, TEMA, ISA, ISO, … System of units: Imperial, SI, CGS, MKS, … Copyright © IA Karimi 16  External Constraints – Beyond Designer Physical laws Mass & energy conservations, thermodynamics, kinetics, heat transfer coefficients,... Government regulations NEA controls Effluent discharges & emission limits regulations for waste discharge in Tax code, corporate taxes or incentives Singapore Depreciation rules Safety: Exposure limits, safe distances, … Codes and standards: Previous slide Resources Time, construction equipment, manpower, land, sourcing, … Copyright © IA Karimi 17  Company Policies or Guidelines Raw materials, products, specs, plant site, contractors, vendors, design factors (margins), … Design factors overdesign to embed operational flexibility. Typical: Max (design) flow = 1.1 x desired flow, 10% for pumps, 20% for exchangers, … Danger of gross overdesign, if repeated by people. Cost increases and efficiency decreases drastically. Mr S Singh (Amec-Foster-Wheeler) opined that this is not done anymore, as computer simulations are quite accurate and reliable. Project economics Budget, RORI, Payback period, discount rate, inflation, interest, equity, … Copyright © IA Karimi 18  Literature, Data, & Information The mother of all sources, ChatGPT, Online databases (e.g. Science Direct), patent databases,... Company reports, people, and plants Licensors (ABB Lummus, UOP, etc.) Books, handbooks, encyclopedias, … Codes and standards Research/Trade journals and publications AIChE J, Ind Eng Chem Res, Chem Eng Sci, Comp Chem Eng, Chem Eng J, … ChE Progress, Hydrocarbon Processing, Chem Eng, Chem Marketing Reporter, … SRI (Stanford Res Inst) International for detailed design reports HTRI (Heat Transfer Res Inst, US) & HTFS (Heat Transfer & Fluid Flow Service, UK) for heat exchangers FRI (Fractionation Research Institute) for distillation Copyright © IA Karimi 19  Reports & Documents Market or technoeconomic analysis Preliminary design or feasibility study Basic engineering design or FEED (Front End Eng Design) BFD, PFD, P&ID, and isometric drawings Firm process design Plant-wide controllability analysis HAZOP study: Hazard identification & risk assessment Environmental impact analysis Life cycle and sustainability analysis General correspondence Copyright © IA Karimi 20  Market or Technoeconomic Analysis Market potential (demand) of target product/s? Price projections? Projected local and global profiles over10-20 years. would only use the Main competitors? technology if it has a TRL of at least 7/8 Technologies? Technology readiness levels (TRL)? TRL levels range Technology licensors? Any political embargos? from 1 to 10 Raw materials? suppliers? Any significant safety, environmental, societal, or geopolitical risks? Carbon footprints and harmful emissions? Sustainability? Estimated rates of returns? Copyright © IA Karimi 21  Block Flow Diagram (BFD) Broad and multiple definitions exist. Simple diagram with blocks showing major sections or operations in a process. Benzene + Hydrogen Cyclohexane Cyclohexane Water Dehydrogenation Hydrogen Benzene Benzene Cyclohexene Cyclohexene Cyclohexanol Hydrogenation Recovery Recovery Hydration Recovery Benzene Benzene Cyclohexanol Production of cyclohexanol from benzene via hydration of cyclohexene Copyright © IA Karimi 22  BFD for Process Simulation BFD with blocks that represent various modules in a commercial process simulation model (e.g. Aspen Hysys). Compress N2 + H2 + CH4 Purge 340 psia 320 psia Heat H2 Heat React Cool Condense Flash V-Mix Expand 340 psia 335 psia 335-320 psia 320 psia 320 psia 320 psia 120 F 340 psia 15 psia 570 F 570-430 F DPT DPT-120 F 120 F Vaporize L-Mix Pump Split Purge 340 psia 340 psia 340 psia 320 psia Light Ends C6 H 6 C6H12+C6H6 Cool Expand Pump 15 psia Distil 15 psia 100 F 340 psia 100 F 100 F 20 psia 20 psia Copyright © IA Karimi 23  Process Flow Diagram (PFD) Key reference for most design tasks with two main parts Directional network diagram & Steam table Diagram shows complete process and flow structures. Sequenced process units with standard icons, names, labels, legend, and nominal operating conditions (P, T, …) ISO 10628 is the international standard, but companies have own symbols. MS Visio is often used by FYDP students. Directional streams/flows (pipelines) of materials and utilities with systematic labels Control valve locations and equipment for storage and transport Stream table shows key data for all streams. Mass flows of each stream and its components P, T, and phase at reasonable precisions Critical trace species and amounts versus zero or blank. indicate important contaminants Copyright © IA Karimi 24  PFD for Benzene Manufacture Production of Benzene via Hydrodealkylation of Toluene stream flow Stream 1 2 3 4 5 6 7 8 9 10 using standard symbols information Pressure (kPa) and icons to indicate the table Temperature (K) type of equipment with Enthalpy (MJ/s) each individual Phase Fraction (wt) equipment tag name Total Flow (kg/s) Benzene (kg/s) Toluene (kg/s) Hydrogen (kg/s) Source: https://www.informit.com/articles/article.aspx?p=1915161&seqNum=2 Copyright © IA Karimi 25  Piping & Instrumentation Diagram (P&ID) A = Alarm C = Controller E = Element F = Flow H = High I = Indicator L = Level L = Low P = Pressure T = Temperature T = Transmitter V = Valve X = Composition Y = Y-type valve P, T, F, and L dominate Source: https://www.linkedin.com/pulse/how-develop-piping-instrumentation-diagram-pid-sadeghi-azizkhani of Javad Sadeghi Copyright © IA Karimi 26  Isometric Piping Diagram - Example Source: https://whatispiping.com/basic-piping-isometric-drawings/?expand_article=1 by Nur Hidayah Haron Copyright © IA Karimi 27  3D Model of Chemical Plant - Example Source: https://www.cgtrader.com/3d-models/industrial/other/chemical-plant-3 Copyright © IA Karimi 28  Preliminary Design or Feasibility Study Quick-estimate design with ±30% cost accuracy to assess project potential tells us whether design is profitable or not BFD, PFD, and stream table with all major sections, units, and operating conditions Critical dimensions of all major units for estimating costs from correlations laws, regulations, licenses, equipment, operational cost, salaries Cash flow analysis (revenue vs cost) to estimate profitability This is partially the scope of your FYDP. Copyright © IA Karimi 29  FEED (Front End Eng Design) Also called basic engineering design Detailed optimized design with ±10% cost accuracy Basis for a Go/No-Go budgeting decision by the corporate board Minimal drafting work (engineering drawings) Copyright © IA Karimi 30  Firm Process Design Final, ready-to-purchase/fabricate designs Firm vendor quotes with 2-5% cost accuracy Detailed equipment specifications & drawings PFD and P&ID Complete Isometric Piping Diagrams (3D drawings) 3D visualization (e.g. PDS) Copyright © IA Karimi 31  HAZOP Study Identify all process (material, equipment, & operational) hazards. Material safety data sheets or MSDS Explosion limits, flammability limits, toxicity, etc. Can tank overflow? Can pressure exceed design level? What is valve fails? What if a seal (e.g. gasket corrodes or degrades/dissolves due to chemical reaction) leaks? Quantitative risk assessment What is the frequency of occurrence? What is the extent of damage? How mechanisms are in place to reduce damage? Alarms, relief devices, pressure switches, etc. Prof Sin will go into more details. Copyright © IA Karimi 32  SHE, Controllability, & Others Environmental impact analysis Disposal of waste streams (toxic or nontoxic) Toxic releases and dispersion models Facilities for reducing emissions Water treatment plants Life cycle and sustainability analysis Cradle-to-grave impact on carbon emissions and renewable penetration Energy efficiency, energy penalty, material intensity, footprints (land, carbon, water, energy, materials, …) Plant-wide controllability analysis Control system design (control schemes, controllers, variables) General correspondence Internal and external (client, vendors, regulators, …) Licenses, permits, agreements, and approvals Copyright © IA Karimi 33  Example Design Project in Singapore Investment = $700 million to $1 billion Duration = 18-30 months Feasibility to go/no-go: 6-12 months, 4-5% of investment Authority submissions: 3-5 months URA (Urban Redevelopment Authority) & JTC (Jurong Town Corporation) for planning approvals BCA (Building & Construction Authority) for building plans FSB (Fire & Safety Board) for safety issues NEA (National Environmental Agency) for pollution control & drainage MoM (Ministry of Manpower) for permits & inspection MPA (Maritime & Port Authority) for waterfront issues EPCC steps (% of project value) Engineering: 10-12% (250K man-hours, 120 people, S$100 million) Procurement: 50-60%, Construction: 30-35%, Commissioning: 10-15% Copyright © IA Karimi 34  Process Development – Learning Outcomes Explain the general structure of a chemical process. List the main sections of a typical chemical plant. Describe the overall strategy for process development. Copyright © IA Karimi 35  Industrial Strategy of Process Development Most business leaders avoid risking huge money Design Objective on unproven process technologies, unless returns are high, and no good alternatives exist. No Is there a Does a process Is it for an No No Develop a commercial exist for a similar existing plant? new process process? objective? Yes Yes Revamp Explore & assess Very few processes existing process Yes get developed from current plant scratch in practice. alternatives 50% of all projects are revamp projects Rule of Thumb Yes Modify Plagiarize* much, Need for existing reinvent nothing. improvement? process Source: Towler & Sinnot (2013) Use existing Developing a PFD from scratch is good process for learning the basics of process development. Copyright © IA Karimi 36  Typical Chemical Process Structure Recycle of Valuable Byproduct Unreacted Reactants Storage This section gets repeated in a multi-step process. Raw Feed Product Product Product Material Reaction Preparation Separation Purification Storage Storage Wastes Wastes Effluents & Waste Emissions Treatment Adapted from Towler & Sinnot (2013) Shared Utility System (Compressed air, N2, power, steam, cooling water, …) e.g. Boiler, Heater, Combined Heat & Power (CHP) System, … Benzene (C6H6) + 3H2  Cyclohexane (C6H12) has 1 step. Benzene + 2H2  Cyclohexene (C6H10) + H2O  Cyclohexanol (C6H11OH) has 2 steps. Several additional recycles may exist for mass separating agents (e.g. solvents). Copyright © IA Karimi 37  Feed / Product Storage Several huge, insulated / jacketed, often refrigerated / heated, tank won’t be solely atmospheric pressure near-atmospheric cylindrical tanks. (slightly above) but not too high to save costs (tank has to be made of material and of a Why atmospheric? Heated? Refrigerated? thickness to maintain the pressure) and for safety reasons Normally for liquid or solid materials. Why not gaseous? for the same amount of Buffer between plant and outside world. Why? liquid and gas, volume for gas will be huge Normally hold a few days of supply/demand. For what?convenience of Often inerted or blanketed with nitrogen. Why? storage and trasnportation Preserve quality and integrity of perishable (e.g. food) or sensitive (e.g. drugs) materials due to degradation, discoloration (Vitamin C), contamination, or humidification.  Oxidation? Corrosion? Combustion / Explosion? Evaporation? inerting storage with nitrogen reduces the effects of these Copyright © IA Karimi processes on the raw materials/ 38 products  Feed Preparation Natural raw materials and synthetic feeds are always impure: They contain species (impurities) other than reactants. What about air? noble gases, dust, SO2, NOx, nitrogen, water vapour What about crude oil? sulfur, heavy metals, salt What about natural gas? sulfur, mercury, Three types of impurities: Inert, reactive, and harmful Catalyst, equipment, health, or environment, … Most impurities are undesirable. They can make a process impractical (e.g. waste heat recovery from power plants). Why not always use high-purity feeds? Copyright © IA Karimi expensive 39  Inert Impurities Species that remain intact through a process. Ar present in air Example 1: C3H8 in C3H6 feed for polypropylene Example 2: Ar in N2 feed for NH3 (How did Ar get there?) Example 3: N2, CO2 in natural gas How can an inert affect a process? Reaction rate? reduce reaction rate because concentration of reactants is lower as inert impurity takes up space Reactor size? larger reactor size to compensate for the reduced reactor size purge required Recycle of unreacted reactants? What becomes necessary? because recycling will keep the inerts Product quality? What becomes necessary? Always remove inerts from feeds? How to decide? What about the examples above? unless harmful, no point spending money to remove the inert Copyright © IA Karimi 40  e.g. sulfur as it reacts to Reactive Impurities form SOx, which is harmful Many impurities react with reactants or other impurities to form side products. Side products may or may not be desirable. Some may be pollutants or harmful emissions. Example 1: Air cannot be used for ammonia. Example 2: Reactive impurity in petrol, diesel, and fuels? Example 3: Reactive impurity combustion air? Diesel? How do they impact process? Product quality? Product yield? Product cost? Process after reactor? Some impurities may decompose or polymerize. Always remove reactive impurities? How to decide? Example 2? Example 3? Copyright © IA Karimi 41  always remove sulfur as sulfur poisons catalysts Harmful Impurities Catalyst/Adsorbent: S, moisture, … can poison or deactivate. Health: Hg in NG is highly toxic and carcinogen. Environment: NH3 in emissions Process efficiency: Moisture in MSW for incineration plant Operations: Water, CO2, C3+ in NG liquefaction. Equipment: Moisture in flue gas can corrode Always remove above impurities? have to remove the ones above as they Copyright © IA Karimi are harmful to health and the process 42  Product Recovery (Separate & Purify) Reactor effluents are almost always mixtures versus single pure products. Why? Most reactions are slow or equilibrium controlled. Few reach 100% conversions. Ammonia and methanol syntheses have only 20-30% conversions. Side reactions (hence side products) are generally inevitable. Many organics in Fischer-Tropsch synthesis (coal gasification) Excess reactants are common and strategic. Fully consume a reactant: Excess H2 in benzene hydrogenation remove a carcinogen and simplifies downstream separation. Suppress side reactions: Facilitate temperature control in highly exothermic reactions. Copyright © IA Karimi 43  Why Separate & Purify Effluent? Reactor effluent has inerts, unreacted reactants, and side products (useful or not) Example 1: Ammonia reactor effluent has N2, H2, NH3 with Ar and CH4 as inerts. Example 2: Benzene hydrogenation gives cyclohexane (useful side product), cyclohexene, benzene, and hydrogen. Example 3: SMR (Steam Methane Reforming) process for H2 gives CH4, CO, H2, and CO2 (useless) Why must we separate and purify? Products must meet market specs (99.9% hydrogen for FCEV). Valuable excess reactants cannot be wasted. Byproducts can be valuable and improve process economics. Harmful and polluting species must be removed before discharge or venting. Copyright © IA Karimi 44  Plant Utility System Chemical plants use two types of utilities: Energy & Mass Energy utilities supply energy of various forms to process. Steam, power (electricity), cooling water, chilled water, air for cooling, … Which three common energy forms in a plant? heat (internal energy), electricity, mechanical Mass utilities are all auxiliary materials that are not process materials (feeds, products, internal streams). material added to make the process easier and Compressed air, fire water, inert/buffer/drying gases, …simpler Solvents, catalysts, additives, inhibitors, and flow enhancers are known as auxiliary materials, but could be called mass utilities. Most large plants have an auxiliary section for utilities. Some/small plants may also use external suppliers (e.g. SUT). Two reasons to have a separate utility system? economies of scale (to reduce cost), space efficiency, reliability of supply Energy utilities impact carbon footprint or intensity. Mass utilities impact mass/resource/sustainability footprint. Copyright © IA Karimi better to minimise use of energy utilities so 45 that carbon footprint is minimised  Why do we Need Utilities? Most chemical plants operate at non-ambient and non-normal process conditions. Point-to-point, unit-to-unit condition (stream variable) changes are inevitable & pervasive. Velocity, elevation, P, T, phase, size/shape, composition, species,... ALL changes need energy in various forms. electrical energy P-change: What energy form does it need? What heat utility? energy T-change: What energy form does it need? What utility? electrical energy Size/shape: What energy form? What utility? heat and Which forms of energy does enthalpy include? mechanical What is the current source of our energy? How about future? solar, wind, hydrogen fossil fuels Copyright © IA Karimi 46  Batch vs Continuous Plants Most ChEs view chemical plants as continuous. in pharma, typically reactors are batch Traditional training emphasizes them heavily. reactors Most well-known chemical plants are continuous. Batch plants are more common than expected. Examples? reasons Feature/Aspect Batch Continuous for choosing Mode of Operation Intermittent, shared 24/7 continuous, dedicated batch: Role of Time Planning & scheduling is critical. Limited - long Scale and nature of production Low-volume, high-margin High-volume, low-margin residence time Number & Nature of Products Multiple, multi-step syntheses Single, 1-step synthesis required Nature of operation Largely manual, labor intensive Highly automated - Flexibility High Low & limited synthesis process is Cleaning/maintenance Much easier Expensive, yearly very complex Product identity Tagged batches Loss of identity Process utilization Low High Residence times Long Short Copyright © IA Karimi typical residence time for 47 continuous reactors is in milliseconds  process synthesis means determining the structure of a process Continuous Process Synthesis Generate and evaluate several plausible process alternatives to achieve the desired objective in the best possible manner. Processes that differ in technology, structures, units, sequence, … How to define best? (Prof Suraj will discuss this & process optimization) ??? ??? ??? ??? ??? ??? Final deliverable: PFD for the best process design Copyright © IA Karimi 48  Process Synthesis is Iterative & Complex Highly creative and multi-disciplinary No universal or systematic procedure exists. Computer-aided commercial tools for process modeling, simulation, optimization, integration, and visualization have made a huge impact. Today’s designs use them fully and cleverly. Few designs without them! University research on systematic & automated methods or algorithms for optimally synthesizing processes from scratch or revamping them. Industry relies heavily on best practices, experience, rules of thumb, heuristics, etc. Copyright © IA Karimi 49  Onion Diagram for Process Synthesis Smith (2005) recommends a core of Robin Smith (2005) hierarchy of major decisions for the chemical continuous process. process Premise: Reactors, their Reactors conversions, yields, and selectivity largely dictate separations and Separations & recycles. Recycles Separations, recycles, and energy Energy Integration integration determine structure. Utility System They offer most complexity and network alternatives. Water & Effluent Treatment Our first focus will be separations. Copyright © IA Karimi 50