【Daily Question】Chemical Engineering Principles 415: Boilers (August 26)
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This post was last edited by “Back to Cambridge” on September 6, 2016, at 16:58. Starting today, the Chemical Engineering Theory section is launching the “Question of the Day” activity, aimed at helping everyone reinforce their fundamental knowledge in chemical engineering. Subsequently, series such as “Principles of Chemical Engineering”, “Mass Transfer and Separation”, “Chemical Thermodynamics”, and “Chemical Process Technology” will also be introduced. We hope for your active participation! Wishing you all a Merry Christmas~~ For replies to the “Question of the Day” activity, answers can be viewed directly; however, the thread will be closed after one day! ! To encourage continued participation from everyone this year! Participation earns 3 wealth points, with an additional 4 wealth points for correct answers~~~ Short answer question: Why is it easier for steam to contain water at higher boiler pressures? Answer: The higher the boiler pressure, the higher the temperature of the boiler water. This increases the movement of water molecules, weakening the forces between them. At the same time, the density of steam increases, which enhances the attraction exerted by the steam in contact with the water on these molecules. As a result, the surface tension of the boiler water decreases, making it easier for small water droplets to form ； As the boiler pressure increases, the density of the steam rises, and the steam flow’s ability to carry water droplets improves, making it harder to separate these droplets from the steam. Therefore, the higher the pressure, the more likely the steam is to contain water.
The greater the pressure, the higher the boiling point, and the more difficult it is to separate water vapor
As the pressure in the boiler increases, the boiling point of the boiler water rises; simultaneously, the surface tension of the boiler water decreases. This makes it easier for small droplets to form as the water evaporates, and these droplets can be carried away. At the same time, as pressure increases, the difference in specific gravity between steam and water decreases, making it difficult to separate them, and steam tends to carry water droplets. The higher the pressure, the greater the density of the steam, and the kinetic energy of the steam flow increases, making it easier for water to be carried along. So when the steam flow velocity is constant, the higher the pressure, the easier it is for the steam to carry water.
1. As the pressure in the boiler increases, the boiling point of the water rises; the surface tension of the water decreases, and it becomes easier for small droplets to form as the water evaporates, allowing them to be carried away. 2. As pressure increases, the difference in specific gravity between steam and water decreases, making it difficult to separate them; as a result, steam tends to carry water droplets along with it. 3. The higher the pressure, the greater the density of the steam, and the kinetic energy of the steam flow increases, making it easier for water to be carried along.
When the pressure is high, the flow rate increases, and it becomes easier for the steam to contain water
As the operating pressure of the boiler increases, not only does the saturation temperature of the boiler water rise, but the molecular thermal motion of the water also intensifies and the forces between molecules weaken. Additionally, due to the increased density of steam, the magnesium oxide composite air ducts cause the steam in contact with the water surface to exert a greater attraction on the water molecules, resulting in a decrease in the surface tension of the boiler water. The result is an increase in the number of small water droplets in the steam space of the drum. As the operating pressure of the boiler increases, the density of steam rises, while the density of the boiler water decreases due to the rise in saturation temperature. As the density difference between steam and boiler water decreases, the ability of steam to carry water droplets increases, while the gravitational separation effect that relies on this density difference weakens. For these two reasons, the higher the operating pressure of the boiler, the more difficult it becomes to separate steam from the boiler water, and the easier it is for the steam to contain water.
As pressure increases, the saturation temperature of the boiler water rises; the molecular thermal motion of the water intensifies, and the forces between molecules weaken. Additionally, as the density of steam increases, the attraction exerted by the steam in contact with the water surface on the water molecules grows, resulting in a decrease in the surface tension of the boiler water. As a result, the number of small water droplets in the steam space of the drum increases. As pressure increases, the density of steam rises, while the density of boiler water decreases due to the rise in saturation temperature. As the density difference between steam and boiler water decreases, the ability of steam to carry water droplets increases, while the gravitational separation effect that relies on this density difference weakens.
As the operating pressure of the boiler increases, not only does the saturation temperature of the boiler water rise, but the molecular thermal motion of the water also intensifies, resulting in weaker forces between the molecules. Additionally, as the density of the steam increases, the attraction exerted by the steam in contact with the water surface on the water molecules grows, which leads to a decrease in the surface tension of the boiler water. The result is an increase in the number of small water droplets in the steam space of the drum. As the operating pressure of the boiler increases, the density of steam rises, while the density of the boiler water decreases due to the rise in saturation temperature. As the density difference between steam and boiler water decreases, the ability of steam to carry water droplets increases, while the gravitational separation effect that relies on this density difference weakens. For these two reasons, the higher the operating pressure of the boiler, the more difficult it becomes to separate steam from the boiler water, and the easier it is for the steam to contain water.
As the pressure in the boiler increases, the boiling point of the boiler water rises; simultaneously, the surface tension of the boiler water decreases. This makes it easier for small droplets to form as the water evaporates, and these droplets can be carried away. At the same time, as pressure increases, the difference in specific gravity between steam and water decreases, making it difficult to separate them, and steam tends to carry water droplets. The higher the pressure, the greater the density of the steam, and the kinetic energy of the steam flow increases, making it easier for water to be carried along. So when the steam flow velocity is constant, the higher the pressure, the easier it is for the steam to carry water.
As the pressure in the boiler increases, the boiling point of the boiler water rises; simultaneously, the surface tension of the boiler water decreases. This makes it easier for small droplets to form as the water evaporates, and these droplets can be carried away. At the same time, as pressure increases, the difference in specific gravity between steam and water decreases, making it difficult to separate them, and steam tends to carry water droplets. The higher the pressure, the greater the density of the steam, and the kinetic energy of the steam flow increases, making it easier for water to be carried along. So when the steam flow velocity remains constant, the higher the pressure, the easier it is for the steam to carry water
The higher the boiler pressure, the higher the temperature of the boiler water, which increases the movement of water molecules and weakens the forces acting between them. At the same time, the density of steam increases, making it more difficult to separate it from the water.