:))

Question 1

What are the two general categories of thermal energy?

Answer 1

The two general categories of thermal energy are:

Heat

Stored Internal Energy of a Substance

Question 2

What is the difference between heat and stored internal energy?

Answer 2

Heat is the transfer of energy caused by a temperature difference, while stored internal energy is a state of the material. When heat is passed from one body to another, the internal energy of the bodies changes.

Question 3

What are the three heat transfer mechanisms?

Answer 3

The three heat transfer mechanisms are:
■
Conduction: The transfer of heat by the interactions of atoms or molecules of a material through which the heat is being transferred.
■
Convection: The transfer of heat by the mixing and motion of macroscopic portions of a fluid (liquid or gas). Convection occurs in two parts: heat transfer into or out of a fluid by conduction, and the movement of the fluid transporting the heated fluid, as well as its thermal energy, to another location.
■
Radiation: The transfer of heat by electromagnetic radiation.

Question 4

What is the difference between heat transfer and mass transfer? Give an example of each.

Answer 4

Heat transfer is the transfer of thermal energy from one system to another, while mass transfer is the net movement of mass from one location, usually meaning stream, phase, fraction or component, to another. Mass transfer is driven by a concentration difference, meaning a difference in the chemical potential of the species.
○
An example of mass transfer is a distillation column.
○
An example of heat transfer is a heater.

Question 5

What is the difference between intensive and extensive properties?

Answer 5

Intensive properties are independent of the size of the system, while extensive properties are dependent on the size of the system.
○
Examples of intensive properties include temperature, pressure, and density.
○
Examples of extensive properties include mass, volume, and energy.

Question 6

What are the two main approaches to thermodynamics?

Answer 6

The two main approaches to thermodynamics are:
■
Statistical thermodynamics (microscopic or molecular approach): This approach considers the behavior of individual molecules and uses statistical methods to derive macroscopic properties.
■
Classical thermodynamics (macroscopic approach): This approach deals with systems as a whole and does not consider the behavior of individual molecules.

Question 7

What are the two types of fluid flow in pipelines?

Answer 7

The two types of fluid flow in pipelines are:
■
Single-phase flow: The flow of either a gas or a liquid.
■
Multiphase flow: A mixture of gas and liquid.

Question 8

What are the main functions of a separator?

Answer 8

The main functions of a separator are:
■
To separate well fluids into their constituent components (gas, oil and water).
■
To condition the separated fluids to meet the requirements for downstream processing or transportation.

Question 9

What are the two main types of storage tanks?

Answer 9

○
The two main types of storage tanks are:
■
Fixed roof tanks: These tanks have a fixed roof that is permanently attached to the tank shell.
■
Floating roof tanks: These tanks have a roof that floats on the surface of the liquid, which helps to reduce evaporation losses.

Question 10

What is the difference between a reciprocating compressor and a centrifugal compressor?

Answer 10

Reciprocating compressors: These compressors use pistons to “push” gas to a higher pressure. They are positive displacement machines, meaning they trap a volume of gas and then displace it into a smaller volume, increasing the pressure.
○
Centrifugal compressors: These compressors use rotating blades to add velocity and pressure to a fluid stream. They are dynamic machines, meaning they rely on the transfer of kinetic energy to potential energy to compress the gas.

Question 11

What are the three main types of distillation towers?

Answer 11

The three main types of distillation towers are:
■
Batch process: The feed to the column is introduced in batches, and the distillation process is carried out. When the desired outcome is achieved, the next batch is introduced.
■
Continuous column: The column processes a continuous feed stream without interruptions unless there is a problem with the column or the surrounding process units. Continuous columns are the most common type of distillation tower.
■
Stripping column: Volatile components are stripped from a solution by the action of stripping gas or steam.

Question 12

What are the different types of distillation trays?

Answer 12

There are three main types of distillation trays:
■
Sieve tray: A metal plate with holes punched into it. It’s the cheapest and simplest tray type, but it’s not as efficient as other types.
■
Valve tray: Similar to a sieve tray, but with valves that open and close to regulate the flow of vapor and liquid. Valve trays are more efficient than sieve trays and can handle a wider range of flow rates.
■
Bubble cap tray: The most complex and expensive type of tray. Bubble cap trays use caps to force the vapor to bubble through the liquid, which improves contact between the two phases and increases separation efficiency.

Question 13

What are the different types of packings used in distillation columns?

Answer 13

There are three main types of packings used in distillation columns:
■
Random packings: Random packing is made up of small, irregularly shaped pieces of material (e.g. Raschig rings, Lessing rings, Pall rings, Berl saddles) that are randomly dumped into the column. They are the cheapest type of packing but can cause high-pressure drops.
■
Structured packings: Structured packing is made up of carefully arranged layers of corrugated sheets or mesh. This type of packing provides a high surface area for contact between vapor and liquid and has a low-pressure drop.

Question 14

What are the main factors that need to be considered when selecting random packing?

Answer 14

The type, size, and material of the random packing need to be considered.

Question 15

What are the advantages and disadvantages of using packed columns versus trayed columns?

Answer 15

Packed columns provide extra interfacial area for liquid-vapor contact, which can de-bottleneck trayed columns facing throughput problems.
○
Packed columns are shorter than trayed columns and have a continuous-contact process, while trayed columns have a staged-contact process.
○
Plate towers can be designed to handle a wider range of liquid and gas flow-rates than packed towers.
○
The efficiency of a tray can be predicted more accurately than the efficiency of packing.

Question 16

What are the main types of reboilers used in distillation columns?

Answer 16

There are a number of reboiler designs, but the main types are:
■
Thermal Syphon Reboiler: Uses natural circulation to move the liquid to be heated.
■
Fired Heater Reboiler: Uses a furnace to heat the liquid.
■
Kettle Type Reboiler: The bottom product from the tower flows to the bottom of the reboiler and comes in contact with hot coils heated by steam or another heating medium. Part of the liquid is vaporized, and the remaining heated liquid expands, causing a thermal syphon flow.

Question 17

What are the main types of condensers used in distillation columns?

Answer 17

The main types of condensers used in distillation columns include:
■
Fin Fan Cooler: A heat exchanger containing finned tubes to increase the heating surface. Air is forced across the tubes by fans.
■
Water-Cooled Condensers: Use water to cool the vapor, which is then condensed. This method can be used to condense all or part of the overhead product.
■
Partial Condensers: Best used when there is a large difference in overhead vapor compositions. They are commonly used in condensing LPG and heavier products.
■
Hot Vapor By Pass Condenser: Best utilized when there is a potential for large changes in overhead vapor composition.

Question 18

What are the two main classifications of compressors?

Answer 18

Compressors can be broadly categorized as:
■
Positive displacement compressors: Trap a volume of gas and then displace it into a smaller volume, which increases the pressure. They are typically used for low to medium flow rates and high-pressure ratios. Reciprocating compressors are a type of positive displacement compressor.
■
Dynamic compressors: Rely on the transfer of kinetic energy to potential energy to compress the gas. They are typically used for high flow rates and low-pressure ratios. Centrifugal and axial compressors are types of dynamic compressors.

Question 19

What are the advantages and disadvantages of using a reciprocating compressor versus a centrifugal compressor?

Answer 19

Reciprocating compressors:
■
Advantages: Higher efficiency at low flow rates and high-pressure ratios.
■
Disadvantages: Larger and heavier than centrifugal compressors, more expensive, require more maintenance.
○
Centrifugal compressors:
■
Advantages: Smaller and lighter than reciprocating compressors, less expensive, require less maintenance.
■
Disadvantages: Lower efficiency at low flow rates and high-pressure ratios.

Question 20

What is surge in a centrifugal compressor?

Answer 20

Surge is an unstable operating condition that can occur in a centrifugal compressor when the flow rate is reduced below a certain point. This causes the flow to reverse direction in the compressor, leading to vibrations, noise, and potential damage to the compressor. Surge can be prevented by using a surge control system, which typically involves recirculating a portion of the discharge flow back to the suction side of the compressor.

Question 21

Separators are essential for separating well fluids into their primary phases: oil, gas, and water. This separation is crucial for several reasons:

Answer 21

○
Simplified Processing: Separating the phases makes it easier and more cost-effective to process the oil, gas, and water.
○
Corrosion Mitigation: Separating produced water, which is often corrosive, helps to reduce corrosion damage.
○
Energy Savings: Moving separated single phases requires less energy, allowing for lower back pressure and increased well production.

Question 22

What is “retention time” in a separator, and why is it important?

Answer 22

Retention time refers to the amount of time the liquid stays in a separator vessel. It ensures sufficient time for the liquid and gas to reach equilibrium at the separator pressure. This equilibrium is vital for effective separation. Retention time is calculated by dividing the vessel’s liquid volume by the liquid flow rate and typically ranges from 30 seconds to 3 minutes. However, for foaming crude oil, the retention time may need to be increased up to four times the normal values.

Question 23

What are the primary types of separators used in oil and gas processing?
●
The sources describe several types of separators, each designed for specific applications:

Answer 23

Vertical Separator: Favored for well fluids with low GOR (gas-oil ratio), fluctuating flow rates, and a tendency for liquid surging or slugging.
○
Horizontal Separator: Suited for efficient liquid/liquid separation in three-phase systems, handling foaming crude oil, situations with height limitations, well fluids with high GOR, and relatively constant flow rates.
○
Spherical Separator: Utilized for well fluids with high GORs, constant flow rates, and no liquid slugging or heading, especially when space is limited. They are also often placed downstream of process units to scrub valuable process fluids.

Question 24

What are the key factors to consider when troubleshooting a separator with mist in the gas outlet line?
●
If mist is detected in the gas outlet line, it may indicate several issues:

Answer 24

Inadequate Vessel Size: The separator may be too small to handle the flow rate effectively.
○
Low Operating Pressure: The pressure may be too low to achieve proper separation.
○
High Liquid Level: A high liquid level could be hindering gas separation.
○
Damaged Mist Extractor: The mist extractor, responsible for removing liquid droplets from the gas stream, might be damaged or malfunctioning.

Question 25

What are some common components found in most separators? ● Separators generally incorporate several components or features to enhance their functionality:

Answer 25

Primary Separation Section: Collects and removes the bulk of the liquid from the incoming stream, often utilizing inlet baffling to harness the momentum of the stream. ○ Secondary Separation Section: Employs gravity settling to further separate liquid from the gas. ○ Liquid Collection Section: Stores the separated liquid before it is discharged. ○ Gas Outlet Section: Directs the separated gas out of the vessel. ○ Mist Extractor: Removes fine liquid droplets from the gas stream before it exits the vessel. ○ Level Control Devices: Maintain the liquid level within the separator at the desired operating range.

Question 26

What are the different types of separators based on their specific purpose? ● Besides their structural classification, separators can be categorized by their purpose:

Answer 26

Production Separator: Used to separate the well fluids produced from a single well or a group of wells. ○ Test Separator: Used for separating and metering the well fluids to assess individual well performance. ○ Expansion Vessel: Designed to handle and melt gas hydrates formed by expansion cooling in cold separation applications. ○ Scrubber: Primarily used as a secondary separation device to remove carryover fluids from process equipment like absorbers or flare systems. ○ Slug Catcher: Designed to separate bulk liquid-gas flow streams that are surging or slugging, sometimes also functioning as a production separator.

Question 27

What are some key factors that influence separator design? ● Several factors are critical in separator design:

Answer 27

GOR (Gas-Oil Ratio): A high GOR requires a separator with greater gas handling capacity. ○ Pressure and Temperature (P&T): Operating pressure and temperature affect the separator's size and design. ○ Surging, Slugging, and Foaming: These flow characteristics influence the separator's design and the need for specific internal components. ○ Corrosive Tendencies: The presence of corrosive fluids may require the use of corrosion-resistant materials in the separator's construction. ○ Gas Physical Properties: The properties of the gas, such as density and viscosity, impact separator sizing. ○ Impurity Types: The nature and concentration of impurities in the well fluids influence the need for additional separation stages or treatment processes.

Question 28

What are the main types of storage tanks used in the oil and gas industry, and what are their key characteristics? ● The sources highlight three primary types of storage tanks:

Answer 28

Open Top Tanks: Used for storing water (city water, fire water, cooling water) and are characterized by the absence of a roof. ○ Floating Roof Tanks: Designed to minimize evaporation loss and fire hazard by using a floating roof that rests on the stored liquid surface. These tanks operate at slightly above atmospheric pressure (around 3 psi). The floating roof helps to eliminate the vapor space above the liquid, reducing emissions. There are two main types of floating roofs: Single deck pontoon roof and Double deck roof. ○ Fixed Roof Tanks: Designed for operating pressures ranging from atmospheric to 15 psi and feature a fixed roof.

Question 29

What are the primary causes of vapor emissions from storage tanks? ● The sources identify three main causes of vapor emissions:

Answer 29

Breathing Losses: Occur due to temperature changes, causing vapor to expand and contract, leading to vapor movement in and out of the tank. ○ Filling Losses: Result from vapor displacement by liquid during tank filling. ○ Boiling Losses: Happen when the liquid temperature reaches its boiling point, generating vapor.

Question 30

What are some typical equipment associated with most types of storage tanks? ● Tanks often have associated equipment for various purposes:

Answer 30

Product Mixers and Mixing Pumps: Ensure product homogeneity and prevent settling. ○ Product Heaters: Maintain the desired temperature of the stored product. ○ Drains: Allow for tank emptying and cleaning. ○ Vacuum and Pressure Relief Valves: Protect the tank from overpressure or vacuum conditions. ○ Level Measuring and Sampling Devices: Monitor tank level and facilitate product sampling.