Intermediate Refrigeration Systems for Operators

Transcription

1 Intermediate Refrigeration Systems for Operators A web-based course conducted by the

2 Intermediate Refrigeration Systems for Operators This class is designed to build upon and extend the skills developed in the introductory class. This class furthers an operator's understanding of ammonia refrigeration and reinforces many of the duties required of an operator. It is not intended to replace plant-specific operation training. Rather, this course strengthens the operator s understanding of ammonia refrigeration theory making them better equipped to receive plant-specific training. The course material is suitable for anyone who has successfully completed the introductory course. A typical course outline is provided below, but can be modified to meet your plant's/company's specific training needs. The course is taught in ten sessions that are 2 hours in length. If desired, an examination can be administered to participants upon completion to validate their comprehension of the material. Advantages of E-Learning In its quest to provide companies with affordable and unified training for operators, the IRC has refined its development of web-based training. Some of the advantages include: Training is delivered live by qualified instructors. A uniform training program can be delivered to all operators across multiple plants. Eliminates travel costs for both students and instructors. Can be tailored to your company s training needs. Session can be recorded and played back at a later date. Students have multiple ways to interact with instructor both during and after class. Homework and exams are to verify their level of comprehension. All web-based courses offered by the IRC feature 1 or 2 instructors providing live audio feed over phone lines while participants view slides, documents, images and animations over their internet connection. Participants can interact with the instructors both on-line and by telephone during the course or can contact the instructors after the session has ended. Most courses are taught in 2 to 4 hour segments over several days. This allows participants stay productive within their plants since there is no off-site travel. These courses are intended to build operator s understanding of refrigeration theory and fundamentals. Our experience has shown that operators with this sounds knowledge make better decisions in their plants-particularly during upset conditions. This foundation of knowledge also makes operators better equipped to receive plant-specific procedure training as required by PSM.

3 Course Outline Refrigeration Systems Review Single stage systems: direct expansion, flooded, liquid overfeed Multi-stage Systems: direct, indirect Loads Temperature requirements Envelope loads Product loads Internal loads Evaporator fan heat gains Psychrometrics overview Sensible & latent loads Infiltration loads - theory vs. real-world Rules-of-thumb Assessing System Performance Basic vapor compression cycle Performance measures Benchmarking Pressure-enthalpy diagrams Influence of head pressure, suction pressure, subcooling & superheat System balance Refrigeration Components: Condensers Types: water-cooled, evaporative Performance characteristics Wet/dry operation Piping considerations (traps, vent line sizing, drainers) Fan alternatives - single speed, two speed, and variable speed Refrigeration Components: Evaporators Evaporator types - Plate-fin, o Plate-fin o Sprayed glycol o Shell-and-tube o Plate-and-frame o Ice builders Refrigerant feed o Top-fed o Bottom-fed o DX, Flooded, Overfeed Defrosting o Methods o Influence on head pressure o Influence on compressor loading o Do I need high head pressure for defrosting? Refrigeration Components: Valves/Metering Devices Solenoid valves Check valves Stop valves Expansion valves: hand-expansion, thermostatic Modulating valves Regulators Actuating methods (direct-acting, pilotoperated) Installation considerations Service considerations: packings, stem lubrication, valve exercising Refrigeration Components: Compressors Reciprocating Screw (single/twin) Rotary Duty: high-stage, booster Compressor ratings: capacity, power, efficiency Capacity control/unloading Variable volume control Methods of oil cooling o Thermosiphon o Liquid injection o Water-cooled Refrigeration Components: Vessels & Accumulators Types: high-pressure receiver, thermosiphon, low-pressure accumulator, flash intercooler Configurations: horizontal or vertical Proper practices for system integration Refrigerant level control (floats, capacitance probes) Influence of oil on level controls & floats Refrigerant Management Issues Transfer systems - what are they and why are they needed? Gas pumping Mechanical pumping Advantages/Disadvantages Purgers and Purge Systems Non-condensables Determining presence of non-condensables Consequences of non-condensables Purge locations and techniques Importance of muli-point purging Purger operation Installation considerations

4 Insulation Systems Insulation system types and alternatives Thickness requirements Vapor and vapor barrier considerations Sheathing and jacketing PM & Inspection guidelines Pumps Refrigerant Pumps o Pump types and performance curves o Net positive suction head required o Net positive suction head available o Refrigerant pump cavitation (causes, diagnostics, and cures) Secondary Fluid Pumps o Types & performance o Influence of fluid selection o Influence of operating temperature Maintenance Overview Oil draining o Techniques for safe draining o Attire (personal protection) Cleaning strainers o Techniques for safe pump-out o Attire Testing ammonia for water o Sample collection Process Safety Management Process safety information Mechanical integrity o Visible inspection techniques o Inspection intervals Management of change Safety Systems & Equipment Ammonia detectors o Types o Proper locations o Testing & calibration requirements PRVs & relief piping o Types o Code requirements o Inspection intervals Operational Issues Methods for adjusting valves o What, where, why? o Hand expansion valves o Thermostatic expansion valves o Back-pressure regulators Estimating quantity of refrigerant released during an incident Estimating residual refrigerant inventory after pump-out Techniques for safely charging systems Incidents Why do they occur? How can they be minimized? Overview of incident investigation o When is it required? o What is required? o Relationship to PHAs Troubleshooting What are the causes of high head pressure? What are the cures? Why can't I get my evaporators defrosted? How often should I defrost? What causes high-level alarms and shutdowns? Hydraulic shock - what is it? How and why do you want to prevent it?

5 Web-based courses currently offered by the IRC Advanced Refrigeration Systems for Operators Ammonia Awareness Training for Employees Intermediate Refrigeration Systems for Operators Introduction to Refrigeration Systems for Operators Overview of Ammonia Refrigeration Systems For more information, contact the IRC at 1415 Engineering Drive Suite 2342 Madison, WI Toll-free: (866) Local: (608) Fax: (608)