plant design piping orignal modified-1.pptx

plant design piping methods

1. Design of Pipes, Fittings,etc 2 First Lecture: B.Sc Chemical (7 th semester) Fall-2014

2. Process Design Types of Process Design Process Flow Diagrams Types of Flow Diagrams Pipes & Fittings Learning Outcomes

3. A principle responsibility of the chemical engineer is to D esign C onstruction O peration of Chemical plants. Process Design Development:

4. Engineer must continuously search for additional information to assist in these functions. Such information is available from numerous sources, including Recent publications Operation of existing process plants Laboratory Pilot-plant data. Cont’d….

5. Design start with Idea or plan. For process Design following factors are considered Technical Factors a. Process flexibility b. continuous, semicontinuous or batch operation c. Special control involved d. Commercial yields e. Technical difficulties involved f. Energy requirements g. Health and safety hazards involved Process Design :

6. 2. Raw Materials a. Present and future availability b. Process required c. Storage requirements d. Materials 3. Waste products & by-products a. Amount produced b. Valve c. Potential markets and uses Cont’d……

7. d. Manner of discard e. Environmental aspects 4. Equipment a. Availability b. Materials of construction c. Initial costs d. Maintenance and installation costs e. Replacement requirements f. Special design Cont’d……

8. 5 . Plant Location a. Amount of land required b. Transportation facilities c. Proximity to markets and raw material sources d. Availability of services and power facilities e. Availability of labor f. Climate g. Legal restrictions and taxes Cont’d……

9. 6. Costs a. Raw materials b. Energy c. Depreciation d. Other fixed charges e. Processing and overhead f. Special labor requirements g. Real estate i. Patent rights Cont’d…..

10. 7. Time Factors a. Project completion deadline b. Process development required c. Market timeliness d. Value of money Cont’d…….

11. 8. Process Consideration a. Technical availability b. Raw materials common with other process c. Consistency of product within company d. General company objectives Cont’d……….

12. The methods for carrying out a design project may be divided into the following classifications , depending on the accuracy and detail required: 1. Order of magnitude designs 2. Study or factored designs 3. Preliminary or quick-estimate designs 4. Detailed-estimate designs 5. Final process designs or detailed designs Types of Process Designs

13. Preliminary designs are ordinarily used as a basis for determining whether further work should be done on the proposed process. The design is based on approximate process methods, and rough cost estimates are prepared. Few details are included, and the time spent on calculations is kept at a minimum . The first step in preparing the preliminary design is to establish the bases for design . Preliminary Design

14. The design can be controlled by such items as the expected annual operating factor (fraction of the year that the plant will be in operation), temperature of the cooling water, available steam pressures, fuel used, value of by-products. The next step is preparing a simplified flow diagram. A preliminary material balance at this point may very quickly eliminate some the alternative cases . Flow rates and stream conditions for the remaining cases are now evaluated by complete material balances. Cont’d….

15. The temperature, pressure, and composition of every process stream is determined . Stream enthalpies, percent vapor, liquid and solid, heat duties are included where pertinent to the process . Unit process principles are used in the design of specific pieces of equipment. Equipment specifications are generally summarized, following equipment's are Cont’d…..

16. In addition to the number of plates and operating conditions it is also necessary to specify the column diameter, materials of construction , plate layout. 2. Vessels: In addition to size, which is often dictated by the holdup time desired , materials of construction and any packing or baffling should be specified . 1. Columns (Distillation)

17. Catalyst type and size, bed diameter and thickness, heat-interchange facilities , cycle and regeneration arrangements, materials of construction must be specified . 4. Heat Exchangers & furnaces Manufacturers are usually supplied with the duty , corrected log mean-temperature difference, percent vaporized, pressure drop desired, and materials of construction. 3. Reactors:

18. Specify type, power requirement, pressure difference, gravities , viscosities, and working pressures . 6. Instruments: Designate the function and any particular requirement . 7. Special equipment . Specifications for mechanical separators, mixers, driers 5. Pumps and Compressors:

19. Finally , it is important that the preliminary design be carried out as soon as sufficient data are available from the feasibility survey or the process-development step . In this way, the preliminary design can serve its main function of eliminating an undesirable project before large amounts of money and time are expended . Cont’d…..

20. The preliminary design and the process-development work gives the results necessary for a detailed-estimate design . The following factors should be established before a detail- estimate design is developed 1.Manufacturing process 2 . Material and energy balances 3 . Temperature and pressure ranges 4 . Raw-material and product specifications Detailed-estimate designs

21. 5 . Yields, reaction rates, and time cycles 6 . Materials of construction 7 . Utilities requirements 8 . Plant site When the preceding information is included in the design, the result permits accurate estimation of required capital investment, manufacturing costs, and potential profits. Cont’d……

22. The chemical engineer uses flow diagrams to show the sequence of equipment and unit operations in the overall process, to simplify visualization of the manufacturing procedures, and to indicate the quantities of materials and energy transfer. These diagrams may be divided into three general types: (1). qualitative ( 2 ). quantitative ( 3 ). combined-detail . Process Flow Diagrams

23. A qualitative flow diagram indicates the flow of materials, unit operations involved, equipment necessary, and special information on operating temperatures and pressures. A quantitative flow diagram shows the quantities of materials required for the process operation. Preliminary flow diagrams are made during the early stages of a design project. As the design proceeds toward completion, detailed information on flow quantities and equipment specifications becomes available, and combined- detail flow diagrams can be prepared. Cont’d……

24. Block flow diagram Process flow diagram PIFD (Process and instrumentation flow diagram) Isometric Flow Diagram Types of flow diagrams

25. The block or rectangles used represent a unit operation. The blocks are connected by straight lines which represent the process flow streams which flow between the units. These process flow streams may be mixtures of liquids, gases and solids flowing in pipes or ducts, or solids being carried on a conveyor belt . In order to prepare clear, easy to understand and unambiguous block flow diagrams a number of rules should be followed: unit operations such as mixers, separators, reactors, distillation columns and heat exchangers are usually denoted by a simple block or rectangle. Block Flow Diagram

26. groups of unit operations may be noted by a single block or rectangle. process flow streams flowing into and out of the blocks are represented by neatly drawn straight lines. These lines should either be horizontal or vertical. the direction of flow of each of the process flow streams must be clearly indicated by arrows. flow streams should be numbered sequentially in a logical order. unit operations (i.e., blocks) should be labeled. where possible the diagram should be arranged so that the process material flows from left to right, with upstream units on the left and downstream units on the right. Cont’d……..

27. A  process flow diagram  ( PFD ) is a diagram commonly used in chemical and process engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between  major  equipment of a plant facility and does not show minor details such as piping details and designations. Another commonly used term for a PFD is a  flowsheet . Process flow diagram

28. Typically, process flow diagrams of a single unit process will include the following: Process piping Major equipment items Control valves and other major valves Connections with other systems Major bypass and recirculation streams Operational data (temperature, pressure, mass flow rate, density, etc.), often by stream references to a mass balance. Process stream names Typical content of a process flow diagram

29. Process flow diagrams generally do not include: Pipe classes or piping line numbers Process control instrumentation (sensors and final elements) Minor bypass lines Isolation and shutoff valves Maintenance vents and drains Relief and safety valves Flanges Cont’d…

30. Flow Diagram of Single Unit Operation

31. Multiple process units within an industrial plant

32. A  piping and instrumentation diagram/drawing  ( P&ID ) is a diagram in the process industry which shows the piping of the process flow together with the installed equipment and instrumentation. A Process and Instrument Drawing (P&ID) includes more details than a PFD. It includes major and minor flows, control loops and instrumentation. P&ID is sometimes referred to as a Piping and Instrumentation Drawing. These diagrams are also called flowsheets. P&IDs are used by process technicians and instrument and electrical, mechanical, safety, and engineering personnel . Process and instrumentation flow diagram

33. A piping and instrumentation diagram/drawing (P&ID) is defined by the Institute of Instrumentation and Control as follows: A diagram which shows the interconnection of process equipment and the instrumentation used to control the process. In the process industry, a standard set of symbols is used to prepare drawings of processes. The instrument symbols used in these drawings are generally based on International Society of Automation (ISA) Standard S5. 1. The primary schematic drawing used for laying out a process control installation. Contents and Function

34. P&IDs play a significant role in the maintenance and modification of the process that it describes. It is critical to demonstrate the physical sequence of equipment and systems, as well as how these systems connect. During the design stage, the diagram also provides the basis for the development of system control schemes, allowing for further safety and operational investigations, such as a Hazard and operability study commonly pronounced as HAZOP. Cont’d……

35. For processing facilities, it is a pictorial representation of: Key piping and instrument details Control and shutdown schemes Safety and regulatory requirements Basic start up and operational information Cont’d…….

36. Instrumentation and designations Mechanical equipment with names and numbers All valves and their identifications Process piping, sizes and identification Miscellanea - vents, drains, special fittings, sampling lines, reducers, increasers and swaggers Permanent start-up and flush lines Flow directions List of P&ID items

37. Interconnections references Control inputs and outputs, interlocks Interfaces for class changes Computer control system input Identification of components Cont’d….

38. Fluids are transported in pipes and tubes which are circular in cross section and available in various sizes, wall thicknesses and material of construction. There is no clear-cut difference between pipes and tubes. Pipes and Tubes

39. Pipes are heavy walled, large in diameter. Length relatively 20-40 ft. Rough surface and pipes can be threatened Length of pipe are joined by screwed, flanged or weld fittings. It can be made from metals, alloys, ceramics, wood, glass and various types of plastics. PVC pipes are extensively used for water lines. Black iron pipes are also used in process plants. Pipes

40. Tubes are thin walled and used for several hundred feets . Tubes can not be threatened Tubes are connected by compression fittings, flare fittings or soldered fittings. It also can be made from metals, alloys, ceramics, wood, glass and various types of plastics. Tubes

41. Pipes and tubing are specified in terms of their diameter and their wall thickness. With steel pipe the standard nominal diameters, in American practice, range from 1/8 to 30 inch. Diameter of large pipe is 12 inch. The nominal diameters are outside diameter of pipe. Inside diameter of the pipe is 3 to 12 inch. Standard sizes for steel pipes are known as IPS (iron pipe size) or NPS (normal pipe size). Sizes

42. The wall thickness of pipe are indicated by schedule number, which increases with thickness. Ten schedule numbers, 10, 20, 30, 40, 60, 80, 100, 120, 140 and 160 are in use. Size of tubing is indicated by outside diameter. The normal value is actual outer diameter within very close tolerances. Wall thickness is given by BWG (Birmingham wire gauge) which ranges from 24 to 7. Cont’d…..

43. Size of pipe depends upon the relative costs of investment, power, maintenance, and stocking pipe & fittings. In small installation, rule of thumb are sufficient. Representative ranges of velocities in pipes are given: Selection of pipe sizes

44. The method used to join pipe and tubes depends in part on the properties of materials and on thickness of the wall. Thick walled are connected by screwed fittings, by flanges or by welding. Thin walled are connected by soldering or compression flare fittings. Joints and fittings

45. Allowance for expansion All pipes will be installed at ambient temperature. Pipes carrying hot fluids such as water or steam operate at higher temperatures. It follows that they expand, especially in length, with an increase from ambient to working temperatures. This will create stress upon certain areas within the distribution system, such as pipe joints, which, in the extreme, could fracture. The amount of the expansion is readily calculated using Equation 

46. The expansion fitting is one method of accommodating expansion. These fittings are placed within a line, and are designed to accommodate the expansion, without the total length of the line changing. They are commonly called expansion bellows, due to the bellows construction of the expansion sleeve.  Other expansion fittings can be made from the pipework itself. This can be a cheaper way to solve the problem, but more space is needed to accommodate the pipe. Expansion fittings

47. In processing equipment one part is moving in relation with others without excessive leakage of fluids around the moving part. This is true in packed expansion joints. Devices which are used to minimize the leakage. Stuffing Boxes Mechanical Seals Prevention of leakage

48. A  stuffing box  is an assembly which is used to house a gland seal .   It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements. An enclosure containing packing to prevent leakage around a moving machine part . The stuffing box is located on the inboard end of the stern tube in the vessel machinery space.  The job of the stuffing box is to allow the propeller to rotate freely inside the stuffing box and at the same time, keep any water from entering the vessel from inside the stern tube. Stuffing Boxes

49. The sealing surface in a stuffing box is between the stuffing box packing rings and the propeller shaft liner or for smaller shafts the propeller shaft itself.     The rotation of the propeller shaft against the stuffing box packing creates friction and heat and over time grooves are worn into the propeller shaft.  Because of this friction your stuffing box must be lubricated with grease or water or both. Stuffing boxes, generally above approximately 5 inch shaft size, can also have an emergency inflatable tube that can be inflated in case of shaft damage preventing water from flowing into the machinery spaces. Cont’d…….

50. A  mechanical seal  is a device that helps join systems or mechanisms together by preventing leakage (e.g. in a plumbing system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent on adhesion in the case of sealants and compression in the case of  gaskets. A stationary seal may also be referred to as 'packing '. In mechanical seals the sliding contact is between a ring of graphite and a polished metal face. Rotary seals require less maintenance than stuffing boxes and have come into wide use in equipment handling highly corrosive fluids. Mechanical Seals