Process Operability Class Materials

Process Operability Class Materials
Introduction to Operability Basic flowsheet Design with Operability FC 1 LC Copyright © Thomas Marlin 2013 The copyright holder provides a royalty-free license for use of this material at non-profit educational institutions

PROCESS OPERABILITY Why Operability?
Is design complete when we have a solution for the base case material and energy balances? What could go wrong with a plant design that satisfied the M&E Balances correctly for the base case? No It could be unsafe, unreliable, be unable to satisfy production quantity or quality changes – and many more deficiencies! This is a general introductory slide. The class discussion and perhaps, a new introductory slide should be tailored to the prior learning experiences of the students, which will be different in each university. The instructor could relate these concepts to * An engineering case study or design experience from a prior course * An example from everyday life, e.g., an electric lamp with on/off switch, manual dimmer, method for replacing the bulb, ground fault interruption, and fuse. We have a base case design but is it operable? Will it function for years in many situations?

A CONCISE DEFINITION OF OPERABILITY*
Some engineers prefer the term “Robust Design”. The two terms have the same general meaning. PROCESS OPERABILITY Ensuring that the plant has the capacity and flexibility to achieve a range of operating conditions safely, reliably, profitably and with good dynamic performance and product quality. This is a general, concise statement. The instructor might want to indicate that he/she will ask the students to modify and improve the definition after either this lesson or after all topics have been covered. The instructor could ask the class to discuss what they believe to be the meaning of “robust” as used in this slide. The instructor might want the class to discuss an every-day item like an automobile to consider the importance of the ability to respond to changes from an idea situation, like driving on a test track. * Useful for concise description but not enough detail to guide engineering decisions.

CLASS WORKSHOP We need to regulate the flow, but how complex should the equipment be? Rank designs for simplicity, cost, reliability, flexibility and other factors that you select. F A B C D F This slide presents a very simple chemical engineering system with several possible designs. Students could be asked to give one strength and one weakness for each of the four designs provided. Sample responses for Design A are given in the following. Design A strengths – can measure and influence the flow, simplicity, and low cost weaknesses – must shutdown process to repair or replace faulty (e.g., leaking) control valve, cannot ensure tight shutoff Then, they could be asked to select the best design, which is not possible without a clear definition of the desired performance and the variability anticipated in the process. F

Roadmap for this Lesson
PROCESS OPERABILITY Roadmap for this Lesson What will we learn in this lesson? - Review the basic Process Design Procedure & locate Operability analysis in the design procedure - Identify Causes of Variability in process plants - Introduce the Eight Operability Topics - Present the Learning Goals for the operability topic Workshops - Sources of variability - Typical operability design for each operability topic Used in all future problem solving This lesson provides an overview of the Operability topic. Some key issues are explained that students will apply throughout their study of the topic and in engineering practice thereafter. These issues will provide helpful checklists for identifying operability challenges and introducing modification to achieve desired performance. Workshops are essential to enable students to struggle with issues, propose solutions, and obtain feedback for the instructor. In addition, many of the most common designs for operability will be covered, which will provide a common toolkit for all students in the class. Students will extend their learning when working on group projects that will involve the standard operability issues, but require novel and innovative designs. The novel designs will be similar in concept but different in detail to the workshop examples. For example, the safety analysis method “HAZOP” will the introduced in the operability lessons and a few exercises will be performed; HAZOP is performed to ensure that workers and the local community is not exposed to unacceptable hazards. Students working on projects involving food production will encounter a similar concept with the acronym “HACCP”, which is performed to ensure that the food products will be safe for the consumer. The background in operability issues and specific coverage of HAZOP will enable students to assimilate and apply newly learned safety approaches, including HACCP, where applicable. Start to build your eng. practice toolkit

A PROCESS DESIGN PROCEDURE
Operability in Design Procedure A PROCESS DESIGN PROCEDURE Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment Construct and start up Often performed for one operating point Inconsistency! Operability prevents this inconsistency! The time spend on this slide depends on the prior learning by the students. If they have not seen this sequence of tasks, the instructor may need to spend time explaining the generality and importance of task, as well as the logic in the sequence order. Students should have a general idea of the “inputs” and “products” of each of these major design steps. The students have performed almost all calculations in previous courses for a specific (single) set of conditions, which are termed the “base case” here. The instructor should point this out, without being critical of previous courses, and discuss the limitations involved with this procedure. Clearly, a process so designed will not likely function properly over a range of conditions. Thus, Operability! Operate the plant over a range of conditions, including many operating points and transitions between them

OPERABILITY: WHEN DO WE INTRODUCE IN THE DESIGN PROCEDURE?
Operability in Design Procedure OPERABILITY: WHEN DO WE INTRODUCE IN THE DESIGN PROCEDURE? Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. This slide expands on the latter two steps in the design sequence. Students will have some experience from prior courses in the use of flowsheeting software (Aspen, Pro II, Hysis, etc.) and understand the product of a solved flowsheet. They will recognize that the balances are solved for a single set of “inputs” that define an operating point. Most students will need some guidance on the relationship between the flowsheet and equipment design (covered in transport and reactor courses). The instructor will likely need to explain what information from a flowsheet is used when designing a heat exchanger, pump-pipe-valve fluid flow system, or chemical reactor. These issues could be covered through a short classroom workshop on a SIMPLE problem. The instructor will need to emphasize a point that is missing in previous courses – the equipment so designed will function for the specific conditions used in the calculations, but it may not function properly for variation around the base case conditions. This leads us to the need for a systematic method of defining and quantifying “variation” (five sources will be introduced in this lesson) and “function properly” (eight operability topics will be introduced in this lesson) Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

OPERABILITY: WHEN DO WE INTRODUCE IT IN THE DESIGN PROCEDURE?
Operability in Design Procedure OPERABILITY: WHEN DO WE INTRODUCE IT IN THE DESIGN PROCEDURE? Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment We must define the range of operations and goals to achieve before we begin the design! Design limited to the “base case” is not likely to be satisfactory. The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. Most undergraduate experiences are thin on coverage of the importance of defining a problem and on experiences in defining engineering problems. This problem statement must be general, so that it does not imply solutions, but specific enough to enable the subsequent design steps to be performed. Examples of “results” of the first step are * Products with rates and purities/performance specifications (base case and ranges with prices) * Range of feed materials possible (with costs, including transportation) * Geographic location of the plant * Allowed effluents with rates, concentrations, etc. All of the results should include a forecast during the life of the project. For example, the production rates might be anticipated to change over the plant/project life, and the engineer needs to decide the capacity of the initial process, what (if any) pre-investment in extra capacity is warranted during the initial construction, and when the future investment in expansion is planned. Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

We have to known where we are going before we can design!
Operability in Design Procedure We have to known where we are going before we can design! Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment The design must define the range of operations to be achieved. We can accept less than full production rate or top efficiency for extreme situations. We must document specifications and range for operations and review with all stakeholders! The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. Let’s consider one issue that applies to many plant designs. Customers are fickle, so that demand for products will vary. Therefore, engineers must have the ability to modify the production rate or at least the rate of transportation from the plant. Some approaches for this include * Changing the feed rate of raw materials into the process. Typically, process equipment has a limited range over which it functions, such as % of the base case design. If the demand is expected to vary (only) within this range, simply design standard equipment is acceptable. * If the demand is expected to vary over a larger range, alternative approaches are needed, including the following For reductions in demand - adding storage and completely shutting down production for an extended period while shipping products from storage - designing with multiple, parallel units so that one (or more) units can be shut down - operating with a large recycle of material, which will enable equipment to function within acceptable rates - selecting process technology with broader ranges of flow rates over which it will function acceptably For increases in demand - pre-invest in extra process capacity beyond the best estimate of the sales - contracting some production to another company under license Naturally, alternate approaches will have different capital and operating costs, so that students will have the opportunity to apply their learning in engineering economics. Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

Operability in Design Procedure OPERABILITY: WHEN DO WE INTRODUCE IT IN THE DESIGN PROCEDURE? Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment This might influence the range of operations! For example, a fluidized bed reactor could have a smaller range of flow than a packed bed. The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. Certainly, issues of safety and sustainability play a major factor in selecting the basic chemical pathways in some processes. No company wants to use highly toxic materials, like mercury, as catalysts, even if cost savings would accrue. This issue is closely related to “sustainability”. Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

Operability in Design Procedure OPERABILITY: WHEN DO WE INTRODUCE IT IN THE DESIGN PROCEDURE? Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment This might influence the range of operations! For example, the addition of a recycle stream might allow a wider range. The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. In the coverage of operability in the course materials, changes in process structure will address limited modifications, typically by-passing and recycle. These are very important and can be introduced in new plants or plant modifications (retrofits). Student projects could evaluate greater changes in process structure during projects, perhaps with each group designing one alternate. Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

Operability in Design Procedure OPERABILITY: WHEN DO WE INTRODUCE IT IN THE DESIGN PROCEDURE? Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment Some of the flowsheet variables, such a distillation feed location and reactor volume, influence the achievable range of operations. The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. The flowsheet solution provides an important starting point for the plant design. The flowsheet solution using the base case operation will satisfy the most likely production rates. However, many additional steady-state solutions are required to understand the plant operation. Some extra situations include * Some equipment is not functioning (due to faults, maintenance, etc.) * Alternate feed materials are used * Different production rates are required * Significantly different operations are selected (low/high reactor intensity, catalyst regeneration, etc.) * Limitations occur in utilities (steam, cooling, hydrogen, etc.) In addition to ensuring that the steady states are possible, the transient operation must also be achievable. For processes that are inherently dynamic, like batch operation, the analysis is more complex and depends on the allowable changes during a batch. In general, the transient batch behavior of the key units (e.g., chemical reactors) must be possible, and the integrated operation of associated units, such as continuous separation units and intermediate storage, must ensure that production rates and qualities can be achieved for a range of conditions. Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

Operability in Design Procedure OPERABILITY: WHEN DO WE INTRODUCE IT IN THE DESIGN PROCEDURE? Design Procedure Set goals and design specifications Select process technology Define process structure (sequence) Simulate the flowsheet Design equipment The flowsheet typically involves basic M&E balances, equilibrium and rate processes. It does not consider practical issues for achieving the operation. Equipment “sizing” has a very strong impact on operability. Students must understand that equipment has a “sweet spot” where it functions well (efficiently), a wider range over which it can meet process requirements at reduced efficiency, and regions below and above the workable region in which equipment does not function acceptably (safely, reliably, profitably, etc.). For example, a fired boiler exchanges heat from the flame (and hot flue gases) to water that boils to make steam. * There is one steam generation rate at which the efficiency (steam/flue) is maximized. * There is a minimum fuel rate below which the flame unstable (perhaps 15-20% of maximum) * There is a maximum fuel rate above which - water could be carried over with steam - the flame could impinge on and damage the steel tubes - insufficient air can be provided to sustain complete combustion * The region between maximum and minimum are acceptable, but at lower efficiency if deviating from the best value of steam generation Once students understand the importance of mastering equipment behavior, they will be much more inclined to assimilate the details. Equipment design has a very strong influence on the range of plant operation. Again, satisfying the “base case” is not sufficient. Equipment design achieves the base case flowsheet (plus other concerns). This sets the “capacity” of the plant.

A PROCESS DESIGN PROCEDURE WITH OPERABILITY
Operability in Design Procedure A PROCESS DESIGN PROCEDURE WITH OPERABILITY • Set goals and design specifications • Select process technology • Define process structure (sequence) Iterate as needed • Simulate the flowsheet • Design equipment Operability analysis This slide indicates that operability analysis will check preliminary design decisions and force re-design when operability has not been provided. The majority of this topic addresses how we define and assess operability and designs to provide it. This slide is simplified. Our goal is to integrate operability with other stages of design. The skilled engineer (i.e., graduate of this course) will be able to “look ahead” and build in operability during prior stages of the design procedure; this look ahead ability will reduce time-consuming iterations. However, we perform specific reviews for critical operability topics, like safety, so that we ensure that the design is satisfactory. (This is discussed at the end of the chapter text.) This concludes the overview of the design procedure and the role of operability analysis. Now, we move on to two key themes in operability analysis, (1) Why is it necessary, that is, why do plant operating conditions change? (2) What are the major operability topics? We will introduce these briefly and apply them numerous times during the subsequent lessons. Construct and start up Operate the plant over a range of conditions, including many operating points and transitions between them

PROCESS DESIGN WITH OPERABILITY
Causes of Variability PROCESS DESIGN WITH OPERABILITY The design procedure should ensure that the plant is operable, that it functions “well”. This requires a specification that addresses a range of conditions. What are causes of deviation from base case conditions? 1. Changes to operations introduced by plant personnel deliberately - We need to match production rate to sales We often produce multiple products and some products are made at different qualities (grades) We often process various feed materials Students have not been introduced to a complex manufacturing environment in which “the abnormal is normal”. Often, the design and construction of a plant will take years, so that the market demands, raw material availabilities, and prices of purchases and sales can be very different from a planning base case. (This is why economic sensitivity analysis is so important in project evaluation!) In addition, the situation continues to change during the many years of operation after startup. Engineers continually evaluate the economic environment and take actions to improve the profitability of the operation. Naturally, the production rate must match the demands. Depending on the process type, operating conditions should be modified. Can this be achieved? Only if operability has been considered during the design!

Causes of Variability PROCESS DESIGN WITH OPERABILITY The design procedure should ensure that the plant is operable, that it functions “well”. This requires a specification that addresses a range of conditions. What are causes of deviation from base case conditions? 2. Disturbances - Many “external” variables change from their assumed base case values. We refer to these as disturbances - really normal variation in the plant. Examples are feed composition, ambient temperature, cooling water temperature, catalyst deactivation, heat exchanger fouling, etc. We seldom discuss disturbances and their influences on process behavior. In the typical course, problems are posed with exactly known, unchanging “inputs” and students are asked to calculate results, such as heat exchanger area or reactor volume. How often have they been asked to extend the problem, “Now, calculate the result for a 20K increase in the feed temperature; the equipment must achieve the same desired exit temperature (exchanger) or conversion (reactor).” Well, now that the students know the basics, we WILL extend the problem in this course. In addition, we will go much further; we will develop designs with flexibility so that the desired result can be obtained for many different input conditions, i.e., for many feed temperature in the example above. Naturally, not all values of feed temperature are likely; therefore, a definition of the variability, here disturbances, must be included during the initial design definition.

Causes of Variability PROCESS DESIGN WITH OPERABILITY The design procedure should ensure that the plant is operable, that it functions “well”. This requires a specification that addresses a range of conditions. What are causes of deviation from base case conditions? 3. Mismatch in design models – Our predictions are imperfect - not useless, just contain some errors. Examples include equilibrium, rate processes, and efficiencies. We compensate for these errors through flexibility. If we rely on perfect models, the plant will not likely operate as expected. Mathematical modelling of chemical processes has progressed to an amazing level; however, we must always acknowledge the limitations in model structure and parameter values that lead to mismatch between actual process behavior and model-based predictions. In the design process, we will use models extensively, and we should understand the range of likely mismatch. In cases where the models are known to have significant uncertainty (and likely, significant mismatch), we will not design to achieve the desired result. We will include a “safety margin” to provide greater capacity for the equipment. An example would be a chemical reactor design using rate information with significant uncertainty. The design should include a manner for achieving the desired conversion for any rate within the estimated range by, for example, changing the reactor temperature.

Causes of Variability PROCESS DESIGN WITH OPERABILITY The design procedure should ensure that the plant is operable, that it functions “well”. This requires a specification that addresses a range of conditions. What are causes of deviation from base case conditions? 4. Equipment Malfunction – Plants operate for months (or years) without stopping, but process equipment sometimes requires immediate maintenance. control valves heat exchangers motors and pumps We need to perform some maintenance without stopping the (entire) plant, and respond safely to all faults. Process equipment is designed to be reliable and robust to mal-operation. However, equipment (infrequently) fails to fully perform its function. For example, * Valves can experience small leaks * Heat exchangers can foul and fail to transfer heat at the desired rate For these “minor” faults, we seek to maintain plant operation by quickly repairing or replacing faulty equipment. Special designs are required to enable people to perform the repair/replacement without shutting down the process. In addition, some equipment faults can cause conditions that could damage equipment and be hazardous for plant personnel. Special designs are required to quickly return process conditions to safe values. A common example is pressure in a closed vessel, which if it were too high (low) could cause explosion (implosion). Methods for preventing extreme pressures will be covered in operability topics.

Causes of Variability PROCESS DESIGN WITH OPERABILITY The design procedure should ensure that the plant is operable, that it functions “well”. This requires a specification that addresses a range of conditions. What are causes of deviation from base case conditions? 5. Human error – People make many important decisions in the plant, and inevitably, errors occur. A single human error should not - cause an unsafe condition cause environmental damage remain undetected (to enable fast correction) Humans make hundreds of decisions and implement actions every workday. Occasionally, a plant operator will make a mistake – this is inevitable regardless of the training and care taken by the person. These mistakes could be due to improper analysis and decision making or to a failure to correctly implement an action, for example, pushing the wrong pushbutton. Process designs should prevent common mistakes from creating hazardous conditions or large economic losses due to equipment damage. Generally, the designs will involve sensing approach to an undesired condition and actions to prevent the process from proceeding further, which could vent fluids to reduce pressure or stop a heating fluid to prevent excessive temperatures.

Operability Class Workshop
Causes of Variability Operability Class Workshop Identify key design specifications that could change and whose magnitudes and frequencies must be defined in a Design Basis Memorandum. reactors compression refrigeration separation products feeds CLASS WORKSHOP! THE PROCESS: This is a common chemical process that converts hydrocarbon feed materials to a range of products, with the most valuable being ethylene and propylene for use in polymerization reactors. The feed goes to reactors, which are fired heaters where thermal pyrolysis occurs. Heavier components are removed in the fractionator; then, the gases are compressed to about 30 bar. The remaining units separate the light hydrocarbons using refrigeration and distillation. THE EXERCISE: We have introduced five categories of variation that result in deviations from the “base case” conditions in a plant. Identify a few specific causes in each of the five categories. A worksheet is available on the next slide.

Causes of Variability Operability Class Workshop Identify key design specifications that could change and whose magnitudes and frequencies must be defined in a Design Basis Memorandum. Identify a few sources of variability for each of the five categories

These are just some examples. There are many other correct answers.
Causes of Variability These are just some examples. There are many other correct answers. WORKSHOP SOLUTIONS Here, some of the many sources of variation that will affect the design are stated. These are certainly not the only correct answers and may not in all cases be the most important. Students will certainty find other correct answers and may propose some answers that are incorrect. That is a good start for further classroom discussions! For students: We do not expect you to prepare perfect solutions for this exercise. You were not given enough information or time to assimilate the information. Also, you do not have sufficient experience in engineering practice. So, do the very best that you can and PAY ATTENTION TO CLASS SOLUTIONS. There is no shortcut to experience, and course workshops are the fastest (and least painful) way to gain some experience. Gaining experience on real plants is great, but it can lead to costly “learning experiences” when something goes wrong.

Operability Topics PROCESS OPERABILITY Ensuring that the plant has the capacity and flexibility to achieve a range of operating conditions safely, reliably, profitably and with good dynamic performance and product quality. By learning about process operability, we will be able to design processes that respond well to variability, just the way a well-designed automobile responds well to curves, bumps, and demands to accelerate and brake quickly. OK, so how will we organize the study of operability?

OPERABILITY TOPICS WILL BE GROUPED INTO EIGHT CATEGORIES
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics OPERABILITY TOPICS WILL BE GROUPED INTO EIGHT CATEGORIES These are the eight categories of operability topics that you will learn and apply to many process examples. We will Learn eight of the most common operability issues Understand typical designs through many class workshops OPERABILITY CATEGORIES Operability is an amorphous goal that we seek to tailor for each application and achieve through analysis and design modifications. How can we do this? Certainly, professional skills, creativity and problem solving are applied, and knowledge of engineering principles is essential. Here, we introduce the eight Operability Topics that we will use to decompose the problem into smaller issues that we can address sequentially. Each topic is a subset of Operability, and we will address them in an order that makes basic structural and capacity decisions before more localized sensor and operations decisions. However, we must recognize that a purely sequential analysis is not adequate; decisions made a lower topic could influence our decisions are a prior topic. Therefore, engineers must build the ability to look ahead and include an iteration in their analysis. The eight topics are listed in the blue boarder. Each will be covered by one or more lessons. Each lesson will define the topic more fully, show several major examples for process plants, and present some of the most commonly applied designs. The coverage will not be – and could never be – comprehensive. The coverage will enable you to understand the issues and some common designs. You will also learn how to extend these concepts and practices in a major course project in which you will encounter different challenges in these operability topics. To learn, we must see many examples!

OPERABILITY TOPICS WILL BE GROUPED INTO EIGHT CATEGORIES
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics OPERABILITY TOPICS WILL BE GROUPED INTO EIGHT CATEGORIES The design procedure involves balancing many objectives, including the eight operability issues. Sometimes, we call this multi-objective design or multi-disciplinary design. One way to combine disparate objectives is through economics, but objectives like safety and contracted product delivery and quality must be satisfied, regardless of cost. (If they cannot in a profitable manner, we do not proceed with the project.) Here we encounter the realistic situation that involves many objectives, which cannot be achieved simultaneously. Therefore, we will ensure that some are rigorously achieved, e.g., safety, and others are partially achieved so that we have the best tradeoff of operability and profitability.

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Operability Class Workshop For the plant sketched below, identify one operability issue in each of the eight categories, and for each, propose a design to attenuate its effect.* reactors compression refrigeration separation feeds products CLASS WORKSHOP We revisit the ethylene plant to identify some challenges to good operability in each of the eight categories along with designs for each of the challenges. TO THE INSTRUCTOR: These are difficult exercises for students at their level of experience. Their class notes give them some hints by highlighting a part of the process. The students should work on the area of the plant highlighted in the sketch. This could be a very long workshop if all students performed all eight exercises. It might be better for the class to be divided into eight groups, with each group working on one of the operability topics and sharing their results with the class during debriefing. TO STUDENTS: Again, this is a difficult exercise, and you will likely not prepare a perfect solution (this early in the course). The goal is to introduce the topics with real examples from engineering practice. In practice (and during your projects) you will have time to investigate issues and search for designs. In a sense, this is LEARN THROUGH STRUGGLE; the more you struggle (apply yourself in the exercises), the more you will learn! * You have not been given much detail about the process or at this point, specific designs for operability. Therefore, don’t expect to get a perfect answer now; just do the best you can with the knowledge that you have. You will learn about solutions in many lessons on operability.

Workshop Solution – Operating Window
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Operating Window The production rate will be changed frequently (daily) to match sales demands. Therefore, the flow rates through the plant will vary and the equipment must be able to accommodate these changes. b. The set of series compressors increase the pressure from slightly above atmospheric to about 30 atmospheres. The work required depends on the flow rate a. The reactors process sufficient feed to produce the desired products. This rate can vary significantly. reactors compression refrigeration separation feeds products The process must have the correct capacity, which enables the process to achieve the maximum and minimum production values, and typically any value in between. Two issues are addressed in the solution: (a) The process must be able to achieve the desired feed rate (b) The compressor must be able to provide enough work to compress that gases resulting from the feed rate

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Operating Window a. The reactors process sufficient feed to produce the desired products. This rate can vary significantly. A flow sensor and controller is required to maintain the feed rate at its desired value. The allowable flow rate for a reactor is about 70%-110% of the base case design value. Therefore, multiple reactors are provided. To reduce the flow below 70% of design, one (or more) reactors can be shutdown. FC reactors compression refrigeration separation feeds products Feed rate The source of the feed (e.g., pipeline or outlet of a pump) must be at a higher pressure that the reactor. In addition, the piping and valves must provide sufficiently low resistance to flow. The valve can be adjusted to regulate the flow rate to the desired value. A typical guideline is that the valve is about 70% open at the base case flow, which allows flows higher than the base case and accounts for some error in the prediction of flow through the valve. Since this is a very important variable, we want to be sure that we achieve the desired flow rate. Therefore, we include a flow sensor. Which type or sensor, i.e., upon what physical principle does the flow sensor rely? For information on sensor principles and selection, refer to

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Operating Window b. The set of series compressors increase the pressure from slightly above atmospheric to about 30 atmospheres. The work required depends on the flow rate We provide the compressor with a source of power that has the required maximum capacity and can variable flow rate, including a much lower flow rate than the base case design. One way to achieve this is to provide a power source that is large enough and a recycle so that all gas passing through the compressor does not have to flow to the distillation section. Here, the power source is a steam turbine, which is like a “reverse compressor”. The turbine rotates and since is connected by a axel, the compressor is rotated. An electric motor could also be used. We can calculate the work required to compress the gas using principles and equations available from our thermodynamics course. Similarly, we can calculate the flow of steam required to provide the work as it flows through a turbine. Notes: 1. The compressor has 5 stages with interstage cooling (why have multiple stages and interstage cooling?) 2. What is the best distribution of pressures for the 5 stages? 3. Is the compression isothermal, isenthalpic, isentropic, or other? What does the typical design equation assume? 4. If we calculate the work using the typical textbook equation, do we need to make any adjustments? (think efficiency) 5. We can calculate the steam flow given the high and low steam pressures. Each plant has steam at a few pressure levels, so these are not variables for designing this system. The other typical source of power would be an electric motor.

Workshop Solution – Flexibility
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Flexibility We must provide equipment to ensure that the desired production rate can be achieved and to make the operation as easy as possible for the plant personnel. a. The required work must be provided and should be provided without frequent intervention by plant personnel. b. The recycle flow should be used when needed. Note that centrifugal compressors have a minimum flow; if flows below this limit occur, the compressors experience “surge” or flow reversal and potentially severe damage. reactors compression refrigeration separation feeds products For flexibility, we concentrate on the compressor. As explained in the workshop on variation, the flow rate will change often; in this plant, the suction and outlet pressures should remain (nearly) constant. Therefore, the work must be adjusted to match the flow rapidly. In addition, a rotary compressor has a minimum flow rate that should flow through it. If the flow is below the minimum value, the flow becomes unstable, flow oscillations occur, the compressor can be seriously damaged, and if people are near, they could be injured. This flow instability is called “surge” and can occur in seconds!

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Flexibility a. The required work must be provided and should be achieved without frequent intervention by plant personnel. This is achieved by adjusting the steam flow to the turbine. The amount of steam is determined by a controller that maintains the compressor suction pressure at the desired value. For example, if the pressure increases, the flow through the compressor is too low, and the controller increases the flow rate of steam to the turbine. ACHIEVING THE DESIRED WORK In theory, we could measure the process flow rate and calculate the required work and steam. However, this approach would be subject to many errors in measurement and in modelling. Therefore, we apply a simpler approach using the FEEDBACK PRINCIPLE. FEEDBACK PRINCIPLE: In feedback control, we measure an output (effect) and adjust an input (cause) to achieve the desired value of the output variable. We select the output (effect) variable that will be controlled as the compressor suction pressure. As the process flow increases (decreases), the suction pressure would increase (decrease), if no change were made to the steam flow (work). Also, the suction pressure is important to the operation of the fractionator. Therefore, this is an appropriate choice. A single-loop controller is applied that uses a pressure measurement as it controlled variable, with the set point (desired value) being input by plant personnel. The controller output signal adjusts the control valve affecting the steam flow rate.

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Flexibility b. The recycle flow should be used only when needed. Note that centrifugal compressors have a minimum flow; if flows below this limit occur, the compressors experience “surge” or flow reversal and potentially severe damage. The flow rate through the compressor is measured. If this measured value is below the minimum, the controller adjusts the recycle valve to maintain the inlet flow rate at the minimum. Note, when the process flow rate without recycle is greater than the minimum, the controller closes the recycle valve, which is desired to prevent wasting energy. ACHIEVING AT LEAST A MINIMUM FLOW RATE The flow through the compressor must be equal to or above a minimum value to prevent surge. Again, we will apply the feedback principle. A single-loop controller uses a measurement of the flow rate as the controlled variable, and the set point value input by plant personnel is the MINIMUM flow requirement. The controller output signal adjusts the recycle control valve. If the flow from the fractionator overhead to the compressor is above the minimum without recycle, the controller keeps the recycle closed. If the flow from the fractionator is below the minimum, the controller will quickly open the recycle value enough to achieve the minimum flow rate through the compressor.

Workshop Solution – Reliability
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Reliability We must provide equipment to ensure that the desired production rate can be achieved and to make the operation as easy as possible for the plant personnel. Equipment malfunction should have the least effect on the overall plant behavior possible, without requiring very expensive additional equipment. The liquid product from the bottom of the fractionator is pumped to storage, and pumps and drivers can fail to perform properly. reactors compression refrigeration separation feeds products Equipment can fail, and engineers must plan for failures and in some cases, provide additional backup equipment. The proper design depends on safety (which will be discussed later) and economics. Based on economics, ADD EQUIPMENT for process designs with equipment whose failures that could lead to large economic losses, which could be prevented by modest extra investment We evaluate the reliability of the flow system at the bottoms of the fractionator.

Workshop Solution – Reliability
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Reliability Equipment malfunction should have the least effect on the overall plant behavior possible, without requiring very expensive additional equipment. The design includes two pumps, with valves so that either can be in operation while the other is isolated from the process and under repair. The level is measured and controlled to withdraw the correct amount of product. Level alarms are included to warn the operator of unusual situations. Here, we have decided to install two pumps and motors (motors not shown in the drawing). In addition, we have provided extra valves so that either pump can be taken out of service and replaced or repaired while the other pump is in service providing work for the bottoms flow. The level controller adjusts a valve to influence the flow rate from the fractionator. The valve is located in the pipe connection after both pumps, so that the level control will function regardless of which pump is in service.

Workshop Solution – Safety
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Safety Equipment is designed to operate within specific limits of pressure and temperature. The compressor suction pressure has upper and lower limits. The upper limit is to protect the equipment from overpressure and failure, releasing hazardous gases to the environment. The lower limit is to prevent the process pressure from being below atmospheric, which might lead to a leak introducing oxygen into the process hydrocarbon stream. reactors compression refrigeration separation feeds products Our first task in safety analysis is identifying all possible sources of hazards; we will address this in a lesson on Hazards and Operability Analysis (HAZOPS). For the moment, we will concentrate on one issue that is always worth analysis – pressure in a closed vessel. This pressure could increase rapidly because of An increase in vapor flow from the fractionator - increase in feed rate - increase in reactor temperature, increasing the yield of lighter products - decrease in cooling in the fractionator over condenser A reduction in the flow rate through the compressor - steam valve stuck too far open, - controller poorly tuned - compressor fails completely

Workshop Solution – Safety
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Safety The compressor suction has upper and lower limits. The upper limit is to protect the equipment from overpressure and failure, releasing hazardous gases to the environment. A safety valve is located in the suction; it will open and provide a path to a safe location for storage or disposal. The lower limit is to prevent the process pressure from being below atmospheric, which might lead to a leak introducing oxygen into the process hydrocarbon stream. An additional pressure controller, PC-2, is added to open the recycle valve to prevent low pressures. (Note, that this must function in conjunction with the low flow recycle; the details are not shown here.) We first note that we cannot rely entirely on the pressure controller for safety, because it could be the root cause of the failure creating the potential hazard. As we will see in the detailed material on safety, we will design many layers of safety protection. PREVENTING HIGH PRESSURE Here, we will add a commonly used feature to prevent high pressure, a safety valve. This is like a heavy weight on the lid of a pot containing liquid that could boil. If we boiled the liquid, the pressure would build and at some point, the force on the lid would be strong enough to lift the weight and release the vapor. The safety valve operates on a similar principle, but it has many advantages, such as in will re-close when the pressure returns to a lower value. (We will cover safety relief devices in detail later.) Naturally, we must design additional process equipment for any effluent that will neutralize, store, or otherwise handle the material safely in a sustainable manner.

Workshop Solution – Product Quality
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Product Quality The ethylene product is used on polyethylene reactors, which require very pure feed. The operation of a high purity distillation column is challenging. Simply setting the conditions (reflux, reboil, etc.) and expecting to achieve the desired purities is not an acceptable strategy. reactors compression refrigeration separation feeds products Consistent product quality is an important goal for all manufacturers. The principle methods for achieving this are automatic process control and statistical process control. Here, we will emphasize automatic control. For process design, we will concentrate on the selection of variables to be measured and controlled (including sensor principles) and equipment to be adjusted, primary control valves (including valve body and actuator selection).

Workshop Solution – Product Quality
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Product Quality The operation of a high purity distillation column is challenging. Simply setting the conditions (reflux, reboil, etc.) and expecting to achieve the desired purities is not an acceptable strategy. We install an on-stream analyzer to measure the concentration (ppm) of methane and ethane in the ethylene product. The measured value of ethane is controlled by a feedback controller adjusting the distillate flow rate. The methane cannot be influenced by this distillation unit. If methane is too high, the product must be sent to waste OK, there is a lot here. One key message – most processes involve a lot or measurement and control. If we fail to provide this equipment, the process will be unsafe, unreliable, and unprofitable. That’s not good! Second key message – Engineers must understand unit operations (exchangers, separation units, combustion units, chemical reactors, etc.) to be able to control them. This will require students to review principles and think in new ways about each unit operation. We have decided to control the impurities in the distillation tower with an overhead product consisting of mainly ethylene and a bottoms product consisting mainly of ethane. What do we measure? (For this problem, we must measure the impurities in the overhead product) What do we adjust? (We have many – reboiler duty, reflux flow, overhead product flow. We will select overhead product flow rate.) What principle do we use? (FEEDBACK!) The control design is too complex to review for this overview.

Workshop Solution – Operation During
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Operation During Transitions Equipment must be taken out of service periodically for maintenance without stopping the entire plant.. Each furnace/reactor has coke build up in the pipes (coils). When the coke thickness is too great, the reactor must be removed from production. Air and steam is used to react and remove the coke. During this time, the reactor effluent contains air and cannot be mixed with the hydrocarbons from the other reactors. reactors compression refrigeration separation feeds products Operation during transitions includes * Startup * Shut down * Batch operations * Periodic maintenance (regeneration, filter cleaning, etc.) * Major disturbances and failures Here, we consider the maintenance of each reactor, which must be periodically (periods of days) taken out of service and operated in a manner that coke is removed from the inner wall of the pipes (tubes).

Workshop Solution – Operation During
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Operation During Transitions Each furnace/reactor has coke build up in the pipes (coils). When the coke thickness is too great, the reactor must be removed from production. Air and steam is used to react and remove the coke. During this time, the reactor effluent contains air and cannot be mixed with the hydrocarbons from the other reactors. Many isolation valves are required to change operation and keep streams separated. To ensure safety, these may be “double block and bleed” to provide greater assurance of isolation. Under normal operation, each reactor has two feed materials, steam and a hydrocarbon (ethane, propane, naphtha or gas oil). This must NOT flow to the reactor during decoking. During decoking, air is fed to the reactors and the effluent steam must NOT flow to the fractionator. Therefore, the design must include piping and valves to enable people to switch feed materials. Safety is a concern because allowing hydrocarbon into the air or air into the hydrocarbon could lead to an explosive mixture. Therefore, we should design to provide “tight shutoff” with essentially no chance of leakage. One design that reduces the possibility of leaks is a “double block and bleed”. This places two block valves in series; these are manual valves that are designed to be fully open or closed, not to regulate flow. A connection between the two valves is connected to a “bleed” valve that allows fluid between the two block valves to escape. The bleed valve is opened when the two block valves are closed. As a result, a small leak in the block valves would not result in fluid entering a restricted volume; the (small amount of) leaking fluid would follow the path of least resistance out the bleed valve. Very simplified drawing of the furnace/reactor

Workshop Solution – Efficiency and
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Efficiency and Profitability The heart of the plant is the reactors. We desire the best conversion and yields. The temperature, pressure and dilution steam all have strong affects on the reactor performance. reactors compression refrigeration separation feeds products In many chemical processes, the desired amount of production at the desired quality can be achieved safely through many combinations of plant operating conditions (flow rates, temperatures, pressures, etc.). These various operating conditions have different efficiencies, product yields, effluent rates, and so forth. Therefore, the engineer would like the opportunity to adjust the operating conditions to satisfy all requirements and in addition, optimize plant operation, which is typically maximizing the profit.

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Efficiency and Profitability The temperature, pressure and dilution steam all have strong affects on the reactor performance. To maintain the preferred low pressure, which improves ethylene yields, all equipment between the reactors and the suction to the compressor should be designed for low pressure drop. reactors compression refrigeration separation feeds products Here, we select the reactor operation as the location where we will change operating conditions to improve profitability. In general, we must perform simulation tests using a model of the process plant to determine which variables will have the strongest effect on profit.

Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Efficiency and Profitability The temperature, pressure and dilution steam all have strong affects on the reactor performance. The ratio of steam to hydrocarbon is controlled. The yields of key components can be measured periodically with an onstream analyzer using samples from the process. The yields can be controlled by adjusting the reactor outlet temperature. Two variables that have a strong influence on profit are Steam-to-hydrocarbon ratio “Intensity” in the reactor, which is influenced by temperature. For example, intensity can be measured by conversion of the feed material feed for ethane feed. The steam-to-hydrocarbon ratio is easily implemented by measuring the feed flow rate, multiplying by the desired ratio value, and using the result as the set point to steam flow controller. This approach is using the “FEEDFORWARD CONTROL PRINCIPLE”. The conversion in the reactor can be determined using an on-stream analyzer that measures the compositions in the reactor effluent. The analyzer controller could adjust the fuel valve directly; however, this approach would be subject to many fast disturbances. Therefore, the analyzer controller adjusts the temperature controller set point, and the temperature controller adjusts the fuel vale. (Oops, its time to review the advantages of cascade control.)

Workshop Solution – Monitoring and
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Monitoring and Diagnosis Plant personnel must continually monitor the plant operation and intervene when undesired events occur. Many extra sensors are required, and the people must have extensive training and experience. Distillation towers, like all equipment, can exceed their operating window. Potential causes can be failures, such as tray corrosion or loss of cooling water, or human error, such as increasing the reboiler heating flow to too high a value. reactors compression refrigeration separation feeds products In any complex endeavor, and especially in the operation complex and potentially hazardous process plants, many events occur that are challenging to diagnosis. Therefore, trouble shooting is a critical issue in plant operation. Many professions are must have good trouble shooting skills. Perhaps, the most obvious profession is medicine; a doctor must be able to determine the root cause of a patient’s symptoms before deciding on a treatment program. In the diagnosis activity, the doctor needs to * Measure many aspects of the patient’s body, such as blood tests, temperature, blood pressure, x-ray, etc. * Interact with the patient, asking him/her questions and to perform special tests, like moving a knee * Consult other medical professionals and references Plant personnel need to perform these functions as well. During the Lesson on Trouble Shooting, we will learn a tailored method of trouble shooting process plants. This method will be helpful when performing trouble shooting and when DESIGNING PLANTS, because engineers must design plants so that they can be monitored and diagnosed! What equipment is most crucial for monitoring?

Workshop Solution – Monitoring and
Key Operability issues 1. Operating window 2. Flexibility/ controllability 3. Reliability 4. Safety & equipment protection 5. Dynamic operation & product quality 6. Operation during transitions 7. Efficiency & profitability 8. Monitoring & diagnosis Operability Topics Workshop Solution – Monitoring and Diagnosis Distillation towers, like all equipment, can exceed their operating window. Many extra sensors not used for control! Tray temperatures Pressure drops across tray sections Redundant sensors for pressure and level Pressures around pumps ….. How do we know which sensors to add? We must identify likely root causes and give the people the information needed to diagnose them. The systematic method for preparing a process for monitoring and diagnosis is to 1. Identify all faults and other root causes of mal-operation that need to be diagnosed (are likely to occur have a significant impact on process performance 2. For each item in (1), prepare a cause-effect (or fishbone) diagram 3. Ensure that every root cause can be uniquely identified from information available (sensors, laboratory analysis, process tests, historical data, etc.) 4. Cross check to be sure that time-critical causes, i.e., those that could lead quickly to hazards or large economic loss, can be diagnosed fast enough to prevent severe consequences Here, we see a typical industrial design. * We note that it contains many more sensors for diagnosis than for control. * For some critical variables, redundant sensors are provided to enable plant personnel to diagnose faults in individual sensors. * Many sensors have local displays to reduce cost. A person must be present near the equipment to observe the displayed value of the measurement * Some equipment have sensors to enable personnel to evaluate it performance, e.g., pressures at the suction and output of a pump * Most (all) sensors which are available for display will have historical data stored to review upon request The capital and maintenance costs for additional sensors is high, but the cost for slow diagnosis of faults can be higher. The proper balance can be gained from experience in operating plants.

Reflections on Operability Workshop
Learning Goals Reflections on Operability Workshop This looks very difficult. I would never have gotten those answers! Don’t worry, you were not expected to answer these questions perfectly. The purpose of this exercise is to introduce the topics, show the critical importance of operability, and demonstrate the types of learning that will be required in the remainder of this topic. Without such examples, you would likely doubt the need to learn details about equipment performance. These examples motivate your learning. OK, that was a difficult set of workshop exercises for the beginning of the course. Students should not expect (or be expected to) solve these exercises perfectly. However, students must see many examples of engineering practice to understand the principles, apply similar methods, and innovate to design novel approaches to new challenges. We have a shared responsibility in the course. The instructor will provide fundamental information, methods of analysis, and compelling practical examples. The students will strive to learn and ask questions when topics are not clear.

OPERABILITY INVOLVES MANY ISSUES; What are the Learning Goals?
Table 1.3 Learning Objectives for Operability Attitudes Knowledge Skills Process operating conditions and goals change freque ntly Process behavior never matches theoretical predictions* Operability is essential and cannot be “added on” after equipment design has been completed Defining sources of variability in plant operation Standard designs to attenuate the effects on plant b ehavior of variability in eight major categories Applying principles to develop non - standard designs in response to variability Problem solving process operations Achieving a good solution to a problem with multiple criteria (e.g., economic and safety) Ma naging a team project (e.g., HAZOP) * Except fundamentals like material and energy balances What else would you like to learn? Talk with your instructor. The categories are likely more important than the entries in each category. ATTITUDES are critical in motivating learning: no one will learn how to design for safety if the person does not value safety. SKILLS are crucial to be able to define problems, gather and evaluate information, collaborate with colleagues, draw conclusions, and communicate results. KNOWLEDGE in technology is what differentiates engineers and makes us able to bring unique benefits to society

OPERABILITY IS A CENTRAL DESIGN ISSUE What will you be able to do?
Learning Goals OPERABILITY IS A CENTRAL DESIGN ISSUE What will you be able to do? Identify the key operability issues in a process and design the process structure and equipment to achieve good process operability. You will be able to apply knowledge to many processes, not limited to class examples. You will be able integrate this analysis with sustainability, engineering economics, and so forth when selecting the best designs. You will be prepared for life-long learning Perhaps, the major emphasis in this area should be placed on the preparation for life-long learning. In operability, we encounter a complex, poorly defined set of criteria that must be satisfied for process designs. The course should be equally useful to students who encounter typical processes covered during the course and those who encounter novel processes never discussed during the course. Let’s move on to detailed study of the first topic: Operating Window

Workshop #1- Waste Water Treatment Plant
PROCESS OPERABILITY Why Operability? Workshop #1- Waste Water Treatment Plant Waste water treatment is essential for municipal sewage and industrial waste water. For a typical plant shown in the sketch, a. Identify sources of variability in each of the five categories. b. Identify an operability issue and propose a design to reduce the effect in each of the eight categories. Leonard G., Creative Commons,

Workshop #2- Drinking Water Treatment Plant
PROCESS OPERABILITY Why Operability? Workshop #2- Drinking Water Treatment Plant People need potable water for drinking and cooking. For a typical plant shown in the sketch, a. Identify sources of variability in each of the five categories. b. Identify an operability issue and propose a design to reduce the effect in each of the eight categories. LabSpace, creative commons,

Workshop #3- Ethanol from Corn Plant
PROCESS OPERABILITY Why Operability? Workshop #3- Ethanol from Corn Plant Ethanol is an alternative fuel made from renewable materials. For a typical ethanol from corn plant shown in the sketch, a. Identify sources of variability in each of the five categories. b. Identify an operability issue and propose a design to reduce the effect in each of the eight categories. Copyright © - Reproduced with Permission

Workshop #4 – Steam generator
PROCESS OPERABILITY Why Operability? Workshop #4 – Steam generator Steam is used for power generation and heating. For a typical boiler shown in the sketch page, a. Identify sources of variability in each of the five categories. b. Identify an operability issue and propose a design to reduce the effect in each of the eight categories. Mbeychok, Creative commons,

Process Operability Class Materials

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