Chemical Plant Design I Basic Concept of Process Design. Dr.Eng. Yulius Deddy Hermawan

Transcription

1 I Basic Concept of Process Design Dr.Eng. Yulius Deddy Hermawan Department of Chemical Engineering UPN Veteran Yogyakarta Outline Formulation of The Design Problem Chemical Process Design and Integration The Hierarchy of Chemical Process Design Onion Model Batch and Continuous Processes Capacity Estimation Pretreatment of Raw Materials Page 1 of 26

2 I FORMULATION OF THE DESIGN PROBLEM How does Chemical Process Plant come into being? 1. An idea: a. Completely new product b. Improvement of an existing product 2. Feasibility Study: reasonable profit? 3. Research and Development: collect data (information) such as the operating condition (P, T, F) 4. Process Design: in this step, a Chemical Engineer: a. decides what kind of equipments will be needed for each operation b. calculates size of each item c. organizes all information in the flowsheet (PFD and/or P&ID) 5. Project Engineering: pilot plant and full scale 6. Construction Engineering 7. Market Research Engineering Page 2 of 26

3 Formulation of The Design Problem Need product specification: Purify spec. Operating and reacting condition Process Design Design Problem for a specialty product (the functional properties rather than chemical properties): require a product design stage Recycle, heat integration Flowsheet Capacity, energy Chemical Product (Smith, R, 2005) essential to modern living standards almost all aspects of everyday life are supported by chemical products in one way or another. 3 broad classes of chemical product: 1. Commodity or bulk chemicals: 2. Fine chemicals: 3. Specialty or effect or functional chemicals Page 3 of 26

4 Commodity or Bulk Chemicals (Smith, R, 2005) These are produced in large volumes and purchased on the basis of chemical composition, purity and price. Examples are: sulfuric acid, nitrogen, oxygen, ethylene and chlorine. Fine Chemicals (Smith, R, 2005) These are produced in small volumes and purchased on the basis of chemical composition, purity and price. Examples: chloropropylene oxide: used for the manufacture of epoxy resins, ion-exchange resins and other products dimethyl formamide: used, for example, as a solvent, reaction medium and intermediate in the manufacture of pharmaceuticals n-butyric acid: used in beverages, flavorings, fragrances and other products) barium titanate powder: used for the manufacture of electronic capacitors Page 4 of 26

5 Specialty or effect or functional chemicals (Smith, R, 2005) These are purchased because of their effect (or function), rather than their chemical composition. Examples: Pharmaceuticals Pesticides Dyestuffs perfumes flavorings. II CHEMICAL PROCESS DESIGN AND INTEGRATION Page 5 of 26

6 Chemical Process Design and Integration (Smith, R, 2005) Transformation of raw material into desired products usually can not be achieve in a single step, but trough some steps as follows: 1. Reaction 2. Separation 3. Mixing 4. Heating 5. Cooling 6. Pressure change 7. Particle size reduction and enlargement 8. etc. Chemical Process Design and Integration (Smith, R., 2005) Synthesis of chemical process involves two broad activities: 1. Selection of individual transformation step 2. Interconnect individual transformation step to form complete structures that achieves the required overall transformation. Flowsheet: diagrammatic representation of the process steps with their interconnection. Once the flowsheet structure has been defined, a simulation of the process can be carried out. A simulation is a mathematical model of the process that attempts to predict how the process would behave if it were constructed. Page 6 of 26

7 III HIERARCHY OF CHEMICAL PROCESS DESIGN AND INTEGRATION Page 7 of 26

8 Hierarchy of Chemical Process Design and Integration (Smith, R, 2005) Process Starts with the reactor. The process requires a reactor to transform the FEED into PRODUCT Unfortunately, not all the FEED reacts. Also, part of the FEED reacts to form BYPRODUCT instead of the desired PRODUCT. Hierarchy of Chemical Process Design and Integration A separation system is needed to isolate the PRODUCT at the required purity. Reactor design dictates the separation and recycle problem this flowsheet is probably too inefficient in its use of energy Need heat integration Page 8 of 26

9 For a given reactor and separator design there are different possibilities for heat integration. For a given reactor and separator design there are different possibilities for heat integration. Page 9 of 26

10 Changing the reactor dictates a different separation and recycle problem A different reactor design not only leads to a different separation system but additional possibilities for heat integration. Page 10 of 26

11 A different reactor design not only leads to a different separation system but additional possibilities for heat integration. IV ONION MODEL Page 11 of 26

12 Simplify Onion Model (Smith, R, 2005) III Raw materials II I Products I. Process/Reaction II. Operation III. Utility Reflect!! 1. What does it mean? Process circle < operation circle < utility circle 2. in case, if Industries do not involve the process/reaction? How about the onion model? 3. Does it possible if industries with un-concentred the onion model? Give its examples Page 12 of 26

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16 V BATCH & CONTINUOUS PROCESSES Page 16 of 26

17 Batch and Continuous Processes (Smith, R, 2005) However, not all processes operate continuously. In a batch process, the main steps operate discontinuously. In contrast with a continuous process, a batch process does not deliver its product continuously but in discrete amounts. This means that heat, mass, temperature, concentration and other properties vary with time. In practice, most batch processes are made up of a series of batch and semicontinuous steps. A semicontinuous step runs continuously with periodic startups and shutdowns. A Simple Batch Process (Smith, R, 2005) Unfortunately, even if the reactor effluent is at a high enough temperature to heat the feeding, the reactor feeding and emptying take place at different times, Requires cooling Requires heating Page 17 of 26

18 Batch Processes: (R. Smith) are economical for small volumes; are flexible in accommodating changes in product formulation; are flexible in changing production rate by changing the number of batches made in any period of time; allow the use of standardized multipurpose equipment for the production of a variety of products from the same plant; are best if equipment needs regular cleaning because of fouling or needs regular sterilization; are amenable to direct scale-up from the laboratory and allow product identification. Batch Processes: (R. Smith) One of the major problems with batch processing is batch tobatch conformity. Minor changes to the operation can mean slight changes in the product from batch to batch. Fine and specialty chemicals are usually manufactured in batch processes. Yet, these products often have very tight tolerances for impurities in the final product and demand batch-to-batch variation being minimized. Page 18 of 26

19 Batch Processes: (James M. Dauglas) Select batch, if: 1. Production rate a. Sometimes batch if less than 10million lb/year b. Usually batch if 1million lb/year c. Multiproduct plant 2. Market forces: a. Seasonal production b. Short product lifetime 3. Scale up problems: a. Very long reaction times b. Handling slurries at low flowrates c. Rapidly fouling materials VI PLANT CAPACITY ESTIMATION Page 19 of 26

20 Production Capacity (Smith, R, 2005) Production capacity is an important factor that needs to be calculated to: determine equipment size satisfy contractual requirements aid supply chain management benchmark against competitors obtain operating permits from regulator. Production capacity is a central concept in: production planning and scheduling operations management Production capacity depends on: market raw material availability Production System Performance (Smith, R, 2005) The production capacity of a chemical plant is a fundamental measure of its economic potential. A simple definition of capacity is the maximum through-put for a single processing step For chemical manufacturing operations, the production system usually takes the form of a series of processing steps (called a serial production system) Page 20 of 26

21 The important things to Determine Production Rates (James M. Dauglas) 1. If we want to design a new plant to meet an expanding market condition, first guess of the production rate based on the largest plant that has ever been built. The greatest economy of scale Normally things are cheaper per unit if we buy them in large quantitiies 2. The maximum size of a plant is usually fixed by the maximum size of one or more pieces of equipment to the plant site. 3. The production rate specified for the plant might change during a design because of the market conditions are constantly changing we must be responsive to these changes 4. Product purity normally is also fixed by marketing consideration. Capacity deppends on the Bottleneck Source: Russell A. Ogle, P.E., and Andrew R. Carpenter, P.E. 2014, AICHE Journal, p Page 21 of 26

22 VII PRETREATMENT OF RAW MATERIALS Raw Material Handling (James M. Dauglas) 1. Phase: a. solid b. liquid c. gas d. slurry e. solution f. etc. 2. Impurity a. inert b. will affect to the reactions? c. Its separation and recycle 3. Its Properties: a. Density/viscosity b. volatility c. corrosive d. etc. 4. Operating/Storing condition: P, T, V. Page 22 of 26

23 Solid Feeder Vertical Silo Page 23 of 26

24 Belt Conveyor Bucket Elevator Page 24 of 26

25 Liquid Tank Mixing Process Page 25 of 26

26 Preparing of Vapor/Gas Feed Control strategies would be discussed next Preparing of High Pressure Gas Feed Control strategies would be discussed next flare (Fflare) dry gas (FG) SPLITTER comp. suction CONDENSOR gas feed (FF) coolant (FC) high pressure gas (Fsuct) T, P SEPARATOR COMPRESSOR condensate (FL) to oil pit Page 26 of 26