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  • 1. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 251 MASTER ➁ Process Diagrams OBJECTIVES After studying this chapter, the student will be able to: • • • • • Review process diagram symbols. Describe the use of process diagrams and the information they contain. Draw a process flow diagram. Draw a process and instrument drawing. Describe the various process equipment relationships. 251
  • 2. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 252 MASTER ➁ Chapter 12 ● Process Diagrams Key Terms Electrical drawings—symbols and diagrams that depict an electrical process. Elevation drawings—a graphical representation that shows the location of process equipment in relation to existing structures and ground level. Equipment location drawings—show the exact floor plan for location of equipment in relation to the plan’s physical boundaries. Flow diagram—a simplified sketch that uses symbols to identify instruments and vessels and to describe the primary flow path through a unit. Foundation drawings—concrete, wire mesh, and steel specifications that identify width, depth, and thickness of footings, support beams, and foundation. Legends—a document used to define symbols, abbreviations, prefixes, and specialized equipment. Process and instrument drawing (P&ID)—a complex diagram that uses process symbols to describe a process unit; also called piping and instrumentation drawing. Types of Process Diagrams Process diagrams can be broken down into two major categories: process flow diagrams (PFDs) and process and instrument drawings (P&IDs), sometimes called piping and instrumentation drawings. A flow diagram is a simple illustration that uses process symbols to describe the primary flow path through a unit. A process flow diagram provides a quick snapshot of the operating unit. Flow diagrams include all primary equipment and flows. A technician can use this document to trace the primary flow of chemicals through the unit. Secondary or minor flows are not included. Complex control loops and instrumentation are not included. The flow diagram is used for visitor information and new employee training. A process and instrument drawing is more complex. The P&ID includes a graphic representation of the equipment, piping, and instrumentation. Modern process control can be clearly inserted into the drawing to provide a process technician with a complete picture of electronic and instrument systems. Process operators can look at their process and see how the engineering department has automated the unit. Pressure, temperature, flow, and level control loops are all included on the unit P&ID. Basic Instrument Symbols Process technicians use P&IDs to identify all of the equipment, instruments, and piping found in their units. New technicians use these drawings 252
  • 3. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 253 MASTER ➁ Basic Instrument Symbols VALVES S Gate Valve Needle Globe Valve Four-Way Diaphragm Angle Manual Operated Gauge Valve H Solenoid Valve CLOSED Hydraulic Back Pressure Regulator Back Pressure Regulator Pneumatic Operated Three-Way Valve Butterfly M Ball Bleeder Valves Plug Check Valve Orifice COMPRESSORS Reciprocating Compressor Pneumatic Operated Butterfly Valve Motor Rotameter Relief PRV Safety PSV PUMPS & TURBINE Vacuum Pump Centrifugal Pumps Centrifugal Compressor Compressor & Silencers Vertical T Liquid Ring Compressor Rotary Compressor Screw Pump Centrifugal Compressor (Turbine Driven) Turbine Gear Pump HEAT EXCHANGERS LINE SYMBOLS Future Equipment Major Process Hairpin Exchanger U-Tube Heat Exchanger Shell & Tube Heat Exchanger Minor Process Pneumatic Hydraulic Capillary Tubing Single Pass Heat Exchanger Reboiler L L L X X XXX X Electromagnetic Signal Heater Condenser Electric VESSELS TI Temp Transmitter TR Mixer Temp Indicator TT Drum or Condenser Temp Recorder LI Level Transmitter LC Level Controller FI Tank Level Indicator LT Flow Indicator Mixing Reactor Forced-Draft Cooling Tower FT Tower Furnace Figure 12.1a Induced-Draft Cooling Tower Tower with Packing Flow Recorder PI Bin Flow Transmitter FR Pressure Indicator PT Pressure Transmitter PRC Pressure Recording Controller Process and Instrument Symbols 253
  • 4. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 254 MASTER ➁ Chapter 12 ● Process Diagrams TI I Flow Indicator Temp Indicator FI TT Temp Transmitter FT Flow Transmitter PIC 105 Pressure Indicating Controller TR Temp Recorder FR Flow Recorder PRC 40 Pressure Recording Controller TC Temp Controller FC Flow Controller LA 25 Level Alarm LI Level Indicator PI Pressure Indicator FE Flow Element LT 65 Level Transmitter PT 55 Pressure Transmitter TE Temperature Element LR 65 Level Recorder PR 55 Pressure Recorder LG Level Gauge LC 65 Level Controller PC 55 Pressure Controller AT Analyzer Transmitter P Variable Being Measured What It Does Transducer Instrument FIC 55 Control Loop Figure 12.1b Field Mounted Remote Location (board mounted) Remote Location (behind control panel) Process and Instrument Symbols (continued) during their initial training period. Knowing and recognizing these symbols is important for a new technician. The chemical processing industry has assigned a symbol for each type of valve, pump, compressor, steam turbine, heat exchanger, cooling tower, basic instrumentation, reactor, distillation column, furnace, and boiler (Figure 12.1). There are symbols to represent major and minor process lines and pneumatic, hydraulic, or electric lines, and there is a wide variety of electrical symbols. Flow Diagrams New technicians are required to study a simple flow diagram of their assigned operating system. Process flow diagrams typically include the major equipment and piping path the process takes through the unit. As operators learn more about symbols and diagrams, they graduate to the much more complex P&IDs. 254
  • 5. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 255 MASTER ➁ Flow Diagrams Cooling Tower Vacuum Pump Product Tank 1 Drum Furnace Feed Tank Column Reactors Product Tank 2 Bottoms Tank Boiler Figure 12.2 Process Flow Diagram (PFD) Some symbols are common among plants; others differ from plant to plant. Some standardization of process symbols and diagrams is taking place. The symbols used in this chapter reflect a wide variety of petrochemical and refinery operations. Figure 12.2 is a PFD that shows the basic relationships and flow paths found in a process unit. It is easier to understand a simple flow diagram if it is broken down into sections: feed, preheating, the process, and the final products. This simple left-to-right approach allows a technician to identify where the process starts and where it will eventually end. The feed section includes the feed tanks, mixers, piping, and valves. In the second step, the process flow is gradually heated for processing. This section includes heat exchangers and furnaces. In the third section, the process is included. Typical examples found in the process section could include distillation columns or reactors. The process area is a complex collection of equipment that works together to produce products that will be sent to the final section. 255
  • 6. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 256 MASTER ➁ Chapter 12 ● Process Diagrams Process and Instrument Drawings A P&ID is a complex representation of the various units found in a plant (Figure 12.3). It is used by people in a variety of crafts. The primary users of the document after plant startup are process technicians and instrument and electrical, mechanical, safety, and engineering personnel. In order to read a P&ID, the technician needs an understanding of the equipment, instrumentation, and technology. The next step in using a P&ID is to memorize your plant’s process symbol list. This information can be found on the process legend. Process and instrument drawings have a variety of elements, including flow diagrams, equipment locations, elevation plans, electrical layouts, loop diagrams, title blocks and legends, and foundation drawings. The entire P&ID provides a three-dimensional look at the various operating units in a plant. Process Legend The process legend (Figure 12.4) provides the information needed to interpret and read the P&ID. Process legends are found at the front of the P&ID. The legend includes information about piping, instrument and equipment P-12 CT-105 V-2 V-3 PC P-13 I/P PCV PT D-105 LT Tk-10 Tk-12 V-4 C-105 Rx-105 V-5 I/P TT FT V-1 I/P P-14 F-105 FC LC FCV P-10 V-6 Tk-14 TC LT TE TT TC I/P Rx-106 I/P P-15 LC I/P EX-105 Tk-16 P-11 Figure 12.3 256 V-7 Process and Instrument Diagram (P&ID) B-105
  • 7. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 257 MASTER ➁ Process and Instrument Drawings VALVE SYMBOLS Ball Gate Valve Bleeder Valves Minor Process Pneumatic Pneumatic Angle Globe Valve Future Equipment Major Process Manual Operated Valve Pneumatic Plug Knife Valve SAFETY (Gases) Diaphragm Four-Way Check Valve X Mechanical Link • • • • X X X Electromagnetic, Sonic Optical, Nuclear Electric Stop Check Three-Way Valve EQUIPMENT SYMBOLS L L L Capillary Tubing Pinch Valve Relief Valve Solenoid Valve CLOSED Hydraulic INDUCED DRAFT Crossflow Butterfly S LINE SYMBOLS EQUIPMENT CONT. Connecting Line NATURAL DRAFT Counterflow Non-Connecting Line Non-Connecting Line Jacketed or Double Containment Vacuum Pump Horizontal Software or Data Link Vertical INSTRUMENT SYMBOLS Sump Pump BOILER Orifice TI Temp. Indicator FI Flow Indicator TT Temp. Transmitter FT Flow Transmitter TR Temp. Recorder FR Flow Recorder TC Temp. Controller FC Flow Controller LI Level Indicator PI Pressure Indicator LT 65 Level Transmitter PT 55 Pressure Transmitter LR 65 Level Recorder PR 55 Pressure Recorder LC 65 Level Controller PC 55 Pressure Controller FE Flow Element I Transducer Centrifugal Rotameter Gear Pump Positive Displacement FURNACE Rotary Screw Compressor Gauge Reciprocating Pump Single Pass Demister Screw Pump Chimney Progressive Cavity Two Pass Spray Nozzle Packed Section P Draw Off C C Double-Pipe Spiral Heat Heat Exchanger Exchanger TE Temperature Element PIC 105 Pressure Indicating Controller LG Generic Tray Level Gauge PRC 40 Pressure Recording Controller AT Analyzer Transmitter Manway Plate and Frame Heat Exchanger Vortex Breaker LA 25 Level Alarm P Air Cooled Exchanger (Louvers Optional) C E Drum APPROVED Dome Roof Tank Sphere 10-6-99 DATE GENERAL LEGEND Condenser DISTILLATION UNIT Cone Roof Tank Internal Floating Roof Tank DRAWING NUMBER OO6543 REVISION 1 PAGE 1 OF 30 Heater ABBREVIATIONS PREFIXES CW- cooling water MU- makeup FW- feed water SE- sewer Figure 12.4 RX- reactor UT- utilities CA- chemical addition IA- instrument air D- drum C- column CT- cooling tower TK-tank F- furnace EX- exchanger P- pump V- valve Process Legend 257
  • 8. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 258 MASTER ➁ Chapter 12 ● Process Diagrams S 4" 18" W E Remesh 12" N 2' x 64' x 18" Load-Bearing Beam Rebar in All Beams 32' 0" Remesh Over Plastic Remesh 6-8-10 Method 6' 0" 10' 0" 28' 0" 90 8' 0" 28' 0" 64' 0" Estimating Materials: Figure 12.5 cu. yds. = width x length x thickness 27 Foundation symbols, abbreviations, unit name, drawing number, revision number, approvals, and company prefixes. Because symbol and diagram standardization is not complete, many companies use their own symbols in unit drawings. Unique and unusual equipment will also require a modified symbols file. Foundation Drawing The construction crew pouring the footers, beams, and foundation uses foundation drawings (Figure 12.5). Concrete and steel specifications are designed to support equipment, integrate underground piping, and provide support for exterior and interior walls. Process technicians do not typically use foundation drawings, but these drawings are useful when questions arise about piping that disappears under the ground and when new equipment is being added. Elevation Drawing Elevation drawings (Figure 12.6) show the location of process equipment in relation to existing structures and ground level. In a multistory structure, the elevation drawing provides the technician with information about 258
  • 9. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 259 MASTER ➁ Process and Instrument Drawings RX-300 TK-300 Figure 12.6 Elevation Drawing C-300 EL-40' 0" D-56 EL28' 0" RX-105 EL 16' 0" TK-105 TK-200 RX-106 equipment location. This information is important for making rounds, checking equipment, developing checklists, catching samples, and performing startups and shutdowns. Electrical Drawing Electrical drawings (Figure 12.7) include symbols and diagrams that depict an electrical system. Electrical drawings show unit electricians where power transmission lines run and places where power is stepped down or up for operational purposes. A process technician typically traces power to the unit from a motor control center (MCC). The primary components of an electrical system are the MCC, motors, transformers, breakers, fuses, switchgears, starters, and switches. Specific safety rules are attached to the operation of electrical systems. The primary safety system is the isolation of hazardous energy “lock-out, tag-out.” Process technicians are required to have training in this area. Figure 12.7 shows the basic symbols and flow path associated with an electrical drawing. Electrical lines are typically run in cable trays to switches, motors, ammeters, substations, and control rooms. A transformer is a device used by industry to convert high voltage to low voltage. The electric department always handles problems with transformers. Electric breakers are designed to interrupt current flow if design conditions are exceeded. Breakers are not switches and should not be turned on 259
  • 10. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 260 MASTER ➁ Chapter 12 Process Diagrams ● 69,000 Volts 69 KV MAIN TRANSFORMER V As A 51 Vs 27 Steam Turbine MCC #1 2.3 KV or 480 Volts Motor Starter ELECTRIC POWER PLANT Motor Starter M M Motor Fuse M Motor V Voltmeter: measures voltage 27 Under Voltage Relay A Ammeter: measures electric current Vs On Off MCC Motor Control Center Voltmeter Switch Current Transformer: reduces high voltage to instrumentation. As Ammeter switch 50 Transformer Overcurrent Relay (Instantaneous) Potential Transforming Symbol 51 Transformer Overcurrent Relay (Time delay) Power Transformer: reduces high voltage Circuit Breaker: a protective device that interrupts current flow through an electric circuit Switch Figure 12.7 260 13.2 KV 13.8 KV 2.3 KV 480V BUS MAIN POWER DISTRIBUTION Generator BOILER 13,200 V 13, 800 V 2,300 V Electrical Drawing Motor Circuit Contacts
  • 11. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 261 MASTER ➁ Process and Instrument Drawings or off. If a tripping problem occurs, the technician should call for an electrician. Fuses are devices designed to protect equipment from excess current. A thin strip of metal will melt if design specifications are exceeded. During operational rounds, technicians check the ammeters inside the MCC for current flow to their electrical systems. Voltmeters, electrical devices used to monitor voltage in an electrical system, are also checked during routine rounds. Equipment Location Drawing Equipment location drawings (plot plans) show the exact location of equipment in relation to the plant’s physical boundaries (Figure 12.8). One of the most difficult concepts to explain to a new process technician is the scope and size of modern chemical processing. Most chemical plants and refineries closely resemble small cities; they have well-defined blocks and areas connected by a highway of piping and equipment. Equipment location drawings provide information about the neighborhood. Loop Diagrams A loop diagram traces all instrument connections between the field instrument and the control room panel. This includes instrument air lines, wiring connections at field junction boxes, and control room panels and front connections. Electrical One-Line Diagrams Like the piping in process systems, the wiring in a unit follows a path. Electrical diagrams show a flow path for distributing power throughout the unit and TK-3 Figure 12.8 Equipment Location TK-2 TK-4 8' 0" TK-1 P-200 D-200 TK-100 18' 0" TK-200 8' 0" 20' 0" 18' 0" 20' 0" 20' 0" 6' 0" P-100 EX-200 P-500A C-200 8' 0" P-201 TK-300 EX-202 10' 0" P-300 TK-400 P-400 20' 0" 16' 0" 261
  • 12. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 262 MASTER ➁ Chapter 12 ● Process Diagrams to all electrical equipment. These diagrams show the different voltage levels in the unit, electrical equipment such as transformers, circuit breakers, fuses, and motors and horsepower required. It also includes start/stop switches, emergency circuits, and motor control centers. Process technicians can use these diagrams to trace a system from the power source to the load. Review of Basic and Specialized Symbols Piping and Valves Each plant will have a standardized file for their piping symbols. Process technicians should carefully review the piping symbols for major and minor flows; electric, pneumatic, capillary, and hydraulic elements; and future equipment (Figure 12.9). The major flow path through a unit illustrates the Figure 12.9 Piping Symbols Y-type Strainer RS Removable Spool Flexible Hose Duplex Strainer Expansion Joint Basket Strainer D Flame Arrestor S In-Line Silencer T Steam Trap Breather Vent Cover Detonation Arrestor F XXX In-Line Mixer Desuperheater DS Ejector / Eductor S Vent Silencer Diverter Valve Rotary Valve Pulsation Dampener Exhaust Head Flange Future Equipment Major Process Minor Process Electromagnetic, Sonic Optical, Nuclear Electric Connecting Line Pneumatic Non-Connecting Line Hydraulic LLL Non-Connecting Line X X Capillary Tubing Jacketed or Double Containment • 262 X X • Mechanical Link Software or Data Link • •
  • 13. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 263 MASTER ➁ Review of Basic and Specialized Symbols critical areas a new technician should concentrate on. A variety of other symbols are included on the piping. These include valves (Figure 12.10), strainers, filters, flanges, spool pieces, insulation, piping size, pressure rating, material codes, and steam traps. Pumps and Tanks Pumps and tanks come in a variety of designs and shapes. Common pump and tank symbols are shown on Figure 12.11. Compressors, Steam Turbines, and Motors Because compressors and pumps share a common set of operating principles and are classified as dynamic or positive displacement, the symbols for compressors may closely resemble those for pumps (compare GATE VALVES Manual Operated Valve Gate Valve Hydraulic M Pneumatic H Motor Bleeder Valves Hydraulic M Angle Needle Pneumatic BALL VALVES Ball M Plug Motor or Hydraulic BUTTERFLY VALVES Butterfly Motor PLUG VALVES H Ball Butterfly H Motor Pneumatic GLOBE VALVES Globe Valve Figure 12.10 Valves M Motor or Hydraulic Plug M Butterfly S DIAPHRAGM VALVES Solenoid Valve CLOSED Pneumatic Operated Motor or Hydraulic CHECK VALVES M Diaphragm SAFETY (Gases) Motor Check Valve RELIEF (Liquids) Four-Way Check Valve Stop Check Three-Way Valve Relief Valve Knife Valve Pinch Valve Gauge Rotameter Orifice 263
  • 14. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 264 MASTER ➁ Chapter 12 ● Process Diagrams CENTRIFUGAL PUMPS POSITIVE DISPLACEMENT PUMPS Positive Displacement Positive Displacement Vertical Progressive Cavity Horizontal Gear Pump Screw Pump Vertical Screw Pump Sump Pump Vertical Vertical Can Pump Vacuum Pump Reciprocating Pump STORAGE SYMBOLS Dome Roof Tank Bin Open Top Tank Tank Tank Double Wall Tank Cone Roof Tank Drum Sphere Figure 12.11 Internal Floating Roof Tank Onion Tank External Floating Roof Pumps and Tanks Figures 12.11 and 12.12). In most cases, the compressor symbol is slightly larger than the pump symbol. In the multistage, centrifugal compressors, the narrowing of the symbol from left to right denotes compression of the gas before it is released. This is in sharp contrast to the steam turbine symbol, which illustrates the opposite effect as the steam expands while passing over the rotor. Modern P&IDs show the motor symbol connected to the driven equipment. This equipment may be a pump, compressor, mixer, or generator. Figure 12.12 illustrates the standardized symbols for compressors, steam turbines, and motors. Heat Exchangers and Cooling Towers Heat exchangers and cooling towers are two types of industrial equipment that share a unique relationship. A heat exchanger is a device used to 264
  • 15. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 265 MASTER ➁ Review of Basic and Specialized Symbols CENTRIFUGAL COMPRESSORS PD COMPRESSORS T Centrifugal Compressor Centrifugal Compressor (Turbine Driven) Centrifugal Compressor Centrifugal Blower Reciprocating Compressor Rotary Compressor Rotory Compressor & Silencers Rotary Screw Compressor Liquid Ring Vacuum Positive Displacement Blower Reciprocating Compressor Axial Compressor STEAM TURBINE MOTORS Agitator or Mixer Turbine Driver Doubleflow Turbine Motor Diesel Motor Figure 12.12 Compressors, Steam Turbines, and Motors transfer heat energy between two process flows. The cooling tower performs a similar function, but cooling towers and heat exchangers use different scientific principles to operate. Heat exchangers transfer heat energy through conductive and convective heat transfer, whereas cooling towers transfer heat energy to the outside air through the principle of evaporation. Figures 12.13 and 12.14 illustrate the standard symbols used for heat exchangers and cooling towers. The symbol for a heat exchanger clearly illustrates the flows through the device. It is important for a process technician to be able to recognize the shell inlet and outlet and the tube inlet and outlet flow paths. A heat exchanger with an arrow drawn through the body illustrates whether the tubeside flow is being used to heat or cool the shellside fluid. The downward direction indicates heating; the upward direction illustrates cooling. 265
  • 16. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 266 MASTER ➁ Chapter 12 ● Process Diagrams Figure 12.13 Heat Exchangers Plate and Frame Heat Exchanger Hairpin Exchanger Air Cooled Exchanger (Louvers Optional) Double-Pipe Heat Exchanger U-Tube Heat Exchanger Single Pass Heat Exchanger C C Spiral Heat Exchanger Heater Condenser Shell and Tube Heat Exchanger Figure 12.14 Cooling Towers INDUCED DRAFT Crossflow HYPERBOLIC Chimney Tower 266 Reboiler FORCED DRAFT Counterflow NATURAL DRAFT Counterflow
  • 17. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 267 MASTER ➁ Review of Basic and Specialized Symbols Figure 12.15 Furnace and Boiler Furnace Boiler The symbol for a cooling tower is designed to resemble the actual device in the process unit. Cooled product flows out of the bottom of the tower and to the processing units. Hot water returns to a point located above the fill. The symbol will not show all of the various components of the cooling tower system, but it will provide a technician with a good foundation in cooling tower operation and enough information to clearly see the process. Furnaces and Boilers The standard symbols file for furnaces and boilers is shown in Figure 12.15. If a proprietary process includes several types of equipment not typically found on a standard symbol file, the designer will draw the device as it visually appears in the unit. Distillation Columns Distillation columns come in two basic designs, plate and packed (Figure 12.16). Flow arrangements vary from process to process. The symbols allow the technician to identify primary and secondary flow paths. Distillation is a process designed to separate the various components in a mixture by their boiling points. (See Chapter 15.) A distillation column is the central component of a much larger system. This system typically includes all of the equipment symbols found in this chapter. Plate distillation columns include sieve trays, valve trays, and bubble-cap trays. Packed columns are filled with packing material, rings, saddles, sulzer, and rosette. Reactors Reactors (Figure 12.17) are stationary vessels and can be classified as batch, semibatch, or continuous. A reactor is designed to allow chemicals to mix together under specific conditions to make chemical bonds, break chemical bonds, or make and break chemical bonds to form new products. 267
  • 18. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 268 MASTER ➁ Chapter 12 ● Process Diagrams Figure 12.16 Distillation Symbols PLATE TOWER Bubble-cap, Sieve, Valve PACKED TOWER Saddle, Ring, Sulzer, Rosette Single Pass Demister Spray Nozzle Chimney Two Pass Packed Section Draw Off Generic Tray Manway Vortex Breaker Sources of Information for Process Technicians Information used by process technicians comes from a variety of sources. Some of these sources are: • Operating training manuals • Process descriptions • Process control manuals • Equipment summaries • Safety, health, and environment regulations • Operating procedures • Startup and shutdown procedures 268
  • 19. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 269 MASTER ➁ Summary Figure 12.17 Reactor Symbols Hydrocracking Fluid Catalytic Cracking Hydrodesulfurization Fluid Coking Mixing Reactor • • • • Tubular Reactor Reformer Fluidized Reactor Alkylation Emergency procedures Process diagrams Technical data books Detailed equipment vendor information Summary Process flow diagrams (PFDs) and process and instrument drawings (P&IDs) are used to outline or explain the complex flows, equipment, instrumentation, electronics, elevations, and foundations that exist in a process unit. A PFD is a simple flow diagram that describes the primary flow path through a unit. A P&ID is a complex representation of the various units found in a plant. Standardized symbols and diagrams have been developed for most pieces of industrial equipment, process flows, and instrumentation. 269
  • 20. 30678_12_ch12_p251-270.qxd 06/09/2006 11:14 Page 270 MASTER ➁ Chapter 12 ● Process Diagrams Review Questions 1. Describe a process flow diagram and a process and instrument drawing. 2. Draw the symbols for a gate, globe, and automatic valve. 3. Draw the symbols for a centrifugal pump and positive displacement pump. 4. Draw the symbols for a blower and a reciprocating compressor. 5. Draw the symbols for a steam turbine and centrifugal compressor. 6. Draw the symbols for a heat exchanger and a cooling tower. 7. Draw the symbols for a packed distillation column and plate distillation column. 8. Draw the symbols for a furnace and a boiler. 9. Draw a simple process flow diagram using the symbols from questions 2–8. 10. What information is obtained from a loop diagram? 11. What information is available on electrical one-line diagrams? 12. What information is contained on a plot plan drawing? 270