Lecture

Flash Drum: Principles and Mass Balance in Separation Processes

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Description

This lecture introduces the concept of a flash drum, a device used for the separation of liquid and vapor phases in chemical engineering. The instructor explains the operational principles of the flash drum, emphasizing the process of partial vaporization. The lecture details the mass and energy balance equations necessary for understanding the relationships between various components, such as feed, liquid, and vapor. The instructor discusses the importance of defining the system and the components involved, including ethanol and water, and how to perform mass balances for each component. The equilibrium relationship is also covered, along with the energy balance that accounts for the heat added during the separation process. The lecture further explores the complexities of multi-component systems and introduces the Rachford-Rice equation, which is essential for solving these systems. The instructor highlights the iterative methods used to find solutions in cases where multiple components are involved, ensuring a comprehensive understanding of the flash drum's role in separation processes.

Official source

Ontological neighbourhood

Physics

Condensed matter physics: Phase transitions

Related concepts (32)

Flash evaporation

Flash evaporation (or partial evaporation) is the partial vapor that occurs when a saturated liquid stream undergoes a reduction in pressure by passing through a throttling valve or other throttling device. This process is one of the simplest unit operations. If the throttling valve or device is located at the entry into a pressure vessel so that the flash evaporation occurs within the vessel, then the vessel is often referred to as a flash drum.

Liquid-mirror telescope

Liquid-mirror telescopes are telescopes with mirrors made with a reflective liquid. The most common liquid used is mercury, but other liquids will work as well (for example, low-melting point alloys of gallium). The liquid and its container are rotated at a constant speed around a vertical axis, which causes the surface of the liquid to assume a paraboloidal shape. This parabolic reflector can serve as the primary mirror of a reflecting telescope.

Phase diagram

A phase diagram in physical chemistry, engineering, mineralogy, and materials science is a type of chart used to show conditions (pressure, temperature, volume, etc.) at which thermodynamically distinct phases (such as solid, liquid or gaseous states) occur and coexist at equilibrium. Common components of a phase diagram are lines of equilibrium or phase boundaries, which refer to lines that mark conditions under which multiple phases can coexist at equilibrium. Phase transitions occur along lines of equilibrium.

Liquid

A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a nearly constant volume independent of pressure. It is one of the four fundamental states of matter (the others being solid, gas, and plasma), and is the only state with a definite volume but no fixed shape. The density of a liquid is usually close to that of a solid, and much higher than that of a gas. Therefore, liquid and solid are both termed condensed matter.

Vapor–liquid equilibrium

In thermodynamics and chemical engineering, the vapor–liquid equilibrium (VLE) describes the distribution of a chemical species between the vapor phase and a liquid phase. The concentration of a vapor in contact with its liquid, especially at equilibrium, is often expressed in terms of vapor pressure, which will be a partial pressure (a part of the total gas pressure) if any other gas(es) are present with the vapor. The equilibrium vapor pressure of a liquid is in general strongly dependent on temperature.

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