Troubleshooting of Distillation
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The document outlines a comprehensive approach to troubleshooting distillation processes, detailing steps including identifying troubles, determining causes, and recommending remedies. Common issues include flooding, pressure drops, and inefficiencies, often resulting in low capacity, poor product quality, and frequent shutdowns. The document also emphasizes the importance of preventative actions, effective communication, and thorough documentation throughout the troubleshooting process.
Troubleshooting of Distillation
- 1. Troubleshooting of Distillation By Marcep Inc. Pankaj Khandelwal BE (Chemical), M.Tech.(Chemical), DBM
- 2. Troubleshooting of Distillation What is Trouble? Deviation from normal plant operation Why the Trouble occur? Something Wrong happened at some Stage •Selection •Engineering •Purchase •Erection •Operation •Maintenance Trends for Visualization of Trouble Earlier Experience to Advanced Tools NOTES: P-1
- 3. Troubleshooting of Distillation Troubleshooter Tasks a.) Identify the Trouble b.) Determine its Cause c.) Recommend a Remedy Major Distillation Problems arise from: 1. Flooding 2. Excessive Pressure Drop 3. Inefficiency Major Troubles in Distillation i. Low Plant Capacity ii. Poor Quality of Separated Products iii. High Consumption of Utilities iv. Poor Efficiency/ Recovery v. Frequent Shut Downs NOTES: P-2
- 4. Troubleshooting of Distillation Step-1) Identify the Trouble NOTES: P-3 Steps of Troubleshooting
- 5. Troubleshooting of Distillation Step-2) Take Preventive Action If required 2.1) Stop the complete chemical plant depending upon the severity of the trouble. For example, off specs product manufactured in the plant, anyway can not be sold in the market. Or 2.2) Stop a section of the plant For example, if product concentration unit is giving some trouble and plant is having enough storage capacity for the intermediate product to store, it shall be stopped till it is corrected. Or 2.3) Stop a unit of plant section For example, stop running pump which is in trouble and run the plant with standby pump. NOTES: P-4 Steps of Troubleshooting
- 6. Troubleshooting of Distillation Step-3) Determine the Cause Causes of Trouble due to 3 M’s a.) Material Examples: - • Low quality input feed materials • Inadequate utilities available • Poor utility specifications b.) Machine (Plant Hardware) Examples:- • Low capacity pump • Undersized pipe line • Wrong orientation of rotameter c.) Manpower Examples:- • Plant Designer • Plant Fabricator • Plant Operation NOTES: P-5 Steps of Troubleshooting
- 7. Troubleshooting of Distillation Step-4) Correct the Trouble NOTES: P-6 Steps of Troubleshooting Do You Know the Solution? NoYes Go to solution providerDo you find any constraints? No Act to solve the trouble Yes Lack of • Finance • Authority • Permission • Plant Stoppage
- 8. Troubleshooting of Distillation Step-5) Return to Service • Thoroughly check all the modifications done in the plant • Take water trial, if required • Start plant (or section of plant) with lower capacity • Check & record all the process parameters and material analysis • Stabilize all the plant operations and run it at rated capacity • Document all the activities carried out in the troubleshooting exercise • Publish to share the document across the organization. NOTES: P-7 Steps of Troubleshooting
- 9. Troubleshooting of Distillation Levels of Trouble Statements TS-1 (Trouble Statement – Level-1) o By CEO Example: Shortfall in Production – 5 TPA Expected: 100 TPA Actual : 95 TPA TS-2 (Trouble Statement – Level-2) o By Site Head Example: Shortfall in Distillation Capacity – 50 m3/day Expected: 950 m3/day Actual : 900 m3/day TS-3 (Trouble Statement – Level-3) o By Section Head Example: Shortfall in Pump Capacity – 10 m3/hr Expected: 50 m3/hr Actual : 40 m3/hr NOTES: P-8 CEO Sites Heads Section Heads Section Managers (Organization Chart) TS-1 TS-2 TS-3 TS-4
- 10. Troubleshooting of Distillation Classification of Troubles a.) Material Specifications Example Expected Actual a.1) Top Product 95 %v/v ‘A’ 94.5%v/v ‘A’ a.2) Bottom Product 0.05%v/v ‘A’ 0.5%v/v ‘A’ a.3) Feed 10%v/v ‘A’ 9%v/v ‘A’ b.) Process Parameters Example Expected Actual b.1) Column Top Temp. 79 oC 80 oC b.2) Column Bottom Pr. 0.5 kg/cm2 (g) 0.55 kg/cm2 (g) b.3) Reflux Rate 5500 lpm 5000 lpm c.) Utility Consumption Example Expected Actual c.1) Steam 10 TPD 10.5 TPD c.2) Cooling Water 20 TR 21 TR c.3) Electricity 100 KWH 110 KWH d.) Hardware Example Expected Actual d.1) Reflux Pump No Sound Sound like Gravel d.2) Valve Trays No Vibration Vibration in Trays d.3) Pipe Line No Leakage Valve Leakage P-9
- 11. Distillation Concepts Relative Volatility & Equilibrium Stages Vapor – Carrier of Energy & High Volatiles Liquid – Carrier of Low Volatiles P-10 Stage-I Stage-II Stage-III Vapors – Heat Source for Stage-I Vapors – Heat Source for Stage-II Vapors – Heat Source for Stage-III Stage-I Stage-II Stage-III Troubleshooting of Distillation
- 12. Distillation Concepts Contact of Vapor & Liquid for Heat & Mass Transfer Packed Column Tray Column P-11 Outlet Weir Down comer Inlet WeirTray Spacing Troubleshooting of Distillation
- 13. Basic Issues of Distillation Affecting its Performance Fluid Flow Related Externally – Gravity versus Pump Flow Internally – Liquid Distributor/ Redistributor Streams Involved : Feed from Tank to Preheater, Reflux to Column, Reboiler Return, Product Draws, etc. Heat Transfer Related Heat Transfer Coefficient – Low considered or reduced Heat Transfer Area – Less tubes or plugged tubes Differential Temperature – High Cooling water temperature Units Involved : Feed Preheater, Reboiler, Condensor, etc. Mass Transfer Related Simultaneous Heat & Mass Transfer Packed Column – Dry Packing, Flooding, etc. Tray Column – Less or More Liquid Level Other Issues : Flooding, Entrainment, Weeping, Dumping, Channeling, Coning, Priming P-12 Troubleshooting of Distillation
- 14. Troubleshooting of Distillation • Liquid with suspended/ dissolved solids • Choking of Trays/ Downcomer • Liquid having trapped gases • Blocking flows • Liquid having material decomposing at high temperatures • Material properties changes • Foaming type liquids • High entrainments • Corrosive Liquids • Material failures • Flammable Liquids • Fire safety concern • Hazardous Liquids • Human safety NOTES: P-13 Fluid Specific Troubles of Distillation
- 15. Troubleshooting of Distillation • Column Components •Packed Column •Packing Types – Random, Structure •Liquid Distributor/ Redistributors •Support Plate •Inlet/ Outlet Nozzles •Tray Column •Tray Types – Sieve, Bubble Cap, Valve Trays •Downcomer, Outlet/ Inlet Weir •Feed/ Draw nozzles • Condensor •Size of Condensor, its piping, etc. • Reboiler •Location, Piping • Pumps •Feed, Reflux, Product (Top/Bottom) Draws NOTES: P-14 Hardware Specific Troubles of Distillation
- 16. Troubleshooting of Distillation • Process Design •Oversized Distillation column, Higher number of sieves • Mechanical Design •Wrong location of vapor nozzles • Procurement •Purchase of Small sized packing • Fabrication •Gap between Tray & Column shell. • Erection •Locating condensor at lower elevation • Maintenance •Downcomer not placed after column cleaning NOTES: P-15 Manpower Specific Troubles of Distillation
- 17. Troubleshooting Exercise Trouble : Product Quality in the distillation system is not achieved NOTES: P-16 Troubleshooting of Distillation
- 18. Troubleshooter Skills 1. Safety first. Assess the SHE (safety, health and environment) issues and implement a temporary solution to give time for troubleshooting. Rushing can lead to safety hazards. 2. Good trouble shooters understand the basics well. Use calculations, models, experiments and so on to check your theories. Know what is important and what is not. 3. Know what to expect before you start. What temperature, pressure profile should you expect? What quality of separation should you expect? Have a feel for what is reasonable based on a variety of experiences. And, last, but not least, “Don’t ever be afraid to do a simple material and energy balance. It will tell you a million things.” 4. Do not overlook the obvious. However, correcting obvious problems does not necessarily solve the whole issue. Be patient. 5. The so-called mental model both helps and hurts the troubleshooting process. “Good trouble shooters have a willingness to accept the data rather than their own theories.” But, “Don’t let the data get in the way of a good theory.” 6. Think of ways to challenge the mental model. Is the process at steady state? Visualize what is happening. Imagine yourself as a pocket of liquid or vapour looking for the easiest path. Think of everyday analogies. Processes are the same that occur in the kitchen, bathroom or yard. “A lot of trouble shooters look for the smoking gun, but it can be a cluster problem.” 7. Testing strategy advice varies considerably, and depends on your situation. Testing should begin with the easiest to prove or disprove and not be based on how likely the theory is. Do all practical tests before making a permanent change. 8. Believe your instruments, unless you have a good reason not to. Don’t start by questioning your instruments. What scenario could cause these data to be true? Instruments report information as they see it. 9. Use people as sources of information. Operators can be powerful resources. They know how to make their own equipment work. What do you see? What do you do in response? What do you do to fix it? Listen to all sources. See value from different viewpoints (level, experience, function personalities). Seek out unsolicited opinions and contrary views. Listen more than talk. Use a learning attitude. Implying that someone screwed up is a sure way to get no cooperation. NOTES: P-17 Troubleshooting of Distillation