Chapter 4 Gas Systems PDF

Process Tech 2 Chapter 4 Gas Systems Reading objective: 1. Describe the purpose and fundamental concepts of gas systems. 2. Describe the equipment and components and the operating principles of gas systems. 3. Explain the instrumentation and control of gas systems. 4. Describe factors...

Process Tech 2 Chapter 4 Gas Systems Reading objective: 1. Describe the purpose and fundamental concepts of gas systems. 2. Describe the equipment and components and the operating principles of gas systems. 3. Explain the instrumentation and control of gas systems. 4. Describe factors that affect normal gas systems operations. 5. Explain the process technician's responsibilities in operating gas systems. 6. List specific safety, health, and environmental concerns associated with gas systems. Reading Objective: I. Introduction i. Fuel gas used as fuel in boiler and other types of furnaces ii. Nitrogen inert gas that is used to purge, or remove explosive gases and air from process systems and equipment also used as a backup to the instrument air iii. Blanketing process of putting nitrogen into the vapor space above the liquid in a tank to prevent air leakage into the tank iv. Air will be used for: 1. Operative valves, drive equipment, pneumatic systems 2. Drying and cleaning equipment 3. Transport (pneumatic conveyor) 4. System purging 5. Blanketing 6. Breathing air supply 7. Combustion with fuel gas II. System Components and Operating Principles a. Overview Gas Systems v. Defined gas and highly compressible vi. Behave according to gas laws 8. Boyles pressure-volume 9. Charles temperature-volume 10. Dalton partial pressure vii. Compressors move gases around the plant and type used is dependent on flow rate and the pressure required b. Air Systems viii. Consist of three subsystems supply, dryers and distribution ix. Difference between systems are: 11. Ultimate use, which determines the quality needed 12. Pressures of individual systems a. Plant air provides compressed atmospheric air needed for the motive force for equipment and tools b. Instrument air derived from same source as utility or plant air but must meet additional requirements such as removal of moisture contaminants c. Breathing air is ambient air that has been purified and tested to meet reequipments for human use x. Knockout pot small vessel used to remove liquid droplets or impurities from a gas system, sometimes called a knockout drum xi. Dewpoint temperature at which a vapor or gas begins to condense to a liquid c. Nitrogen Systems xii. Inert gas system introduces an inert gas, often nitrogen into the top of a vessel to prevent combustion, a positive pressure is normally maintained in the vessel xiii. Letdown station is a valve or series of valves that reduce pressure in a gas stream, may sometimes be referred to as a pressure reducing regulator xiv. Regulators devices used to control the pressure of a fluid or gas upstream or downstream of the device location d. Fuel Gas Systems xv. Uses natural gas or gas derived from a combination of commercial natural gas and light end gases produced by other operations e. Composition of Natural Gas xvi. Heating value, its physical characteristics, water content, and percentage of specific hydrocarbons contained in the gas f. Composition of Fuel Gas xvii. Consists of lighter hydrocarbons and can come from a variety of sources xviii. Fuel considered lean or rich 13. If lean if the BTU value is less than 900 14. Typically, due to higher amounts of nitrogen and or hydrogen 15. Fuel gas is rich if the BTU value is greater than 1100 III. Instrumentation and Controls g. Reference figure 4.7 IV. Abnormal Conditions h. Primary concern related to proper pressures maintenance i. Troubleshooting reasons for any pressure drops V. Process Technician Responsibilities j. Compressors monitor: xix. Lubrication systems xx. Seals, flanges xxi. Observe vibrations monitors xxii. Verify that liquid levels are within control limits xxiii. Monitoring gas flow rates, pressure levels and temperature k. Filters and dryers monitor: xxiv. Instrumentation xxv. Time intervals between filter changes, desiccant changes and or regeneration xxvi. Parameters that indicate the filter or desiccant needs to be changed or regenerated xxvii. Verifying that proper filters are being used upon replacement xxviii. Motorized equipment for vibrations and temperature xxix. Checking strainer baskets and cleaning as necessary l. Compressed gas systems xxx. Must be kept separate and will have special connections to avoid cross connection. VI. Safety, Health and Environmental Concerns m. Compressor and compressor system: high noise levels, extreme temperatures, electrical hazards and high pressures n. Natural gas and fuel system pose fire and explosive hazard xxxi. Mercaptan needs to be added if not already present to detect leaks with smell o. Process tech should; xxxii. Know the content of the gas system xxxiii. Understand the surrounding of the system xxxiv. Understand what is connected to the system and watch for potential cross connection to prevent a variety of consequences xxxv. Be aware of the specific hazards associated with the gas in the system xxxvi. Understand that these systems are under pressure and that pressure is a potential hazard. Quiz **Question 1** What term refers to the process of putting nitrogen into the vapor space above the liquid in a tank to prevent air leakage? Isolating Layering Smothering Blanketing **Feedback** Good work **Question 2** What is a desiccant? A special dryer that uses hot air to remove water vapor from a gas A disposable material used to absorb water vapor from a gas A substance that can adsorb water vapor as the vapor passes through a fixed bed A chemical additive that reacts with water vapor, causing it to turn into a fine powder **Feedback** Good work **Question 3** Water under atmospheric pressure boils at 212 degrees Fahrenheit. What happens if the pressure is increased? The boiling point stays the same. The boiling point increases. The boiling point sometimes increases and sometimes decreases. The boiling point decreases. **Feedback** That\'s not correct **Question 4** Which of the following is a process technician\'s responsibility associated with working with compressor systems? Monitoring supply/storage levels Monitoring humidity Monitoring outlet temperatures Looking for leaks around filter enclosures **Feedback** Good work **Question 5** High noise levels are one of the common hazards associated with \_\_\_\_\_\_\_\_. wastewater systems compressors and compressor systems filter systems dryer systems **Feedback** Good work **Question 6** Where does the fuel gas in a fuel system feeding a furnace come from? Refinery off-gas only A mix of natural gas and refinery off-gas Propane tanks Natural gas source only **Feedback** Good work **Question 7** Which of the following is a process technician\'s responsibility associated with working with compressed air systems? Switching dryers and filters Ensuring proper grounding Lubricating equipment Looking for leaks around filter enclosures **Feedback** Good work **Question 8** Which air system normally has the least-strict quality requirements? Breathing air Utility air Oxygen tanks for first aid stations Instrument air **Feedback** Good work **Question 9** Which of the following fuel gas components has the lowest number of carbon atoms per molecule? Ethane Pentane Butane Methane **Feedback** That\'s not correct **Question 10** Which type of air is used for catalyst regeneration? Instrument air Breathing air Compressed air Plant air **Feedback** Good work **Question 11** How is natural gas used to maintain constant pressure for the fuel gas system? By using a control loop and manually adjusting set points By using an alarm system that alerts the plant of over-pressure situations By constantly monitoring the pressure gauges By cascading the pressure controller to the flow controller **Feedback** Good work **Question 12** Electrical hazards are among the common hazards associated with \_\_\_\_\_\_\_\_. dryer systems filter systems compressors and compressor systems wastewater systems **Feedback** Good work **Question 13** Which of the following is a process technician\'s responsibility associated with working with filters and dryers? Ensuring proper grounding Monitoring outlet temperatures Looking for leaks around enclosures Purging liquids **Feedback** That\'s not correct **Question 14** Which of the following is a process technician\'s responsibility associated with working with nitrogen systems? Lubricating equipment Verifying lubrication levels Monitor pressure levels Monitoring outlet temperatures **Question 15** What is an example of a gas that comes from an off-site distribution system? Instrument air Breathing air Natural gas Liquid hydrogen **Feedback** Good work **Question 16** What ensures the safe and effective isolation of the fuel gas line during normal or emergency shutdown? Constant technician monitoring of the system Double block and bleed trip valves A sophisticated alarm system Break-away feed valves **Feedback** Good work **Question 17** What are the primary concerns when working with any gas system? Keeping pressures always at the same level and eliminating inefficient quality controls Keeping all pressures high to speed up throughput and producing materials as cheaply as possible Keeping all pressures as low as possible and producing materials as cheaply as possible Maintaining proper pressures and ensuring that composition of materials meets appropriate standards **Feedback** Good work **Question 18** What is a potential cause of dirt, rust, and scale in the air lines of a gas system? Lubrication leaks Fouled dryers Failure of oil traps Failure of screens and/or filters **Feedback** Good work **Question 19** What gas system component is used to remove liquids from gases? A special piping system An aerator A knockout drum or knockout pot A filter **Feedback** Good work **Question 20** In addition to double block and bleed trip valves, what are used on the fuel and pilot gas lines during startup and shutdown of the furnace? Break-away feed valves Nitrogen gas lines Manual operation procedures Flare lines **Feedback** That\'s not correct **Question 21** What is likely to be the most common issue to affect the operation of gas systems? A change in fuel costs A change in customer expectations A change in pressure A change in humidity **Feedback** Good work **Question 22** What is the most important consideration in choosing the location of a portable compressor? Ensuring that it will not cause noise complaints from nearby residents Ensuring that adequate power is available Ensuring that it is not too close to meeting rooms Ensuring that it does not introduce hazardous fumes into the system **Feedback** Good work **Question 23** What is one of the hazards associated with nitrogen systems? Explosions Asphyxiation Fires Overheating **Feedback** Good work **Question 24** The phase transition of a fluid such as water from liquid to vapor is known as \_\_\_\_\_\_\_\_. condensation boiling alchemy ionization **Feedback** Good work **Question 25** For what purpose is breathing air often used? To assist in a turnaround or maintenance activities in a confined space To put out small fires To clear fog from parking lots To provide fresh air in offices **Feedback** Good work