(Daily Question) Coal-to-oil and olefins forum, April 19, 2018
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3.jpg Participation: Prize of 5 Wealth； Correct answer: Reward of 10 wealth points ； Note: This post is valid for 48 hours. Question: (DMTO) Olefin separation unit: Why does the exhaust temperature rise when the vacuum level decreases? When the vacuum level drops, the back pressure increases accordingly. At a certain back pressure, there is a specific saturation temperature; therefore, as the exhaust pressure increases, the exhaust temperature also rises. Note: The answer will be announced automatically in two days!
Because all materials have a outgassing rate in a vacuum, and this rate increases as the temperature rises. This is because when we evacuate the vacuum system to a certain level of vacuum at room temperature and then heat the system, the vacuum level decreases. As the temperature rises, the outgassing rate of the material in a vacuum environment increases, resulting in a lower vacuum level
As the vacuum decreases, the back pressure of the condenser increases accordingly. A certain back pressure corresponds to a specific saturation temperature, and the exhaust steam temperature is essentially equal to the saturation temperature of the steam inside the condenser; therefore, as the vacuum decreases or the back pressure rises, the temperature of the exhaust cylinder also increases
This is because when we evacuate the vacuum system to a certain level of vacuum at room temperature and then heat the system, the vacuum level decreases. As the temperature rises, the outgassing rate of the material in a vacuum environment increases, resulting in a lower vacuum level
As the vacuum level decreases, the back pressure increases accordingly. At a certain back pressure, there is a specific saturation temperature; as the exhaust pressure rises, the exhaust temperature also rises correspondingly.
As the vacuum level decreases, the exhaust pressure increases accordingly. At a certain exhaust pressure, there is a certain saturation temperature. As the exhaust pressure increases, the exhaust temperature rises accordingly.
A drop in the vacuum of the condenser means an increase in the back pressure; consequently, the saturated temperature corresponding to this pressure also rises. Structurally, the condenser is connected to the exhaust port of the low-pressure cylinder through an exhaust pipe equipped with a stainless steel expansion joint; therefore, changes in the condenser vacuum and the exhaust temperature of the low-pressure cylinder are interrelated. The lower the condenser vacuum, the higher the exhaust pressure of the turbine, and the smaller the ideal specific enthalpy drop of the turbine. This also causes the exhaust temperature to rise, and as a result, the temperature of the exhaust cylinder increases as well. An increase in the exhaust cylinder temperature can cause thermal deformation of the cylinder, a change in the rotor’s centerline, and may also lead to vibration in the unit or even accidents.
As the vacuum level decreases, the back pressure increases accordingly. At a certain back pressure, there is a specific saturation temperature; as the exhaust pressure rises, the exhaust temperature also rises correspondingly.
As the vacuum level decreases, the back pressure increases accordingly. At a certain back pressure, there is a specific saturation temperature; therefore, as the exhaust pressure increases, the exhaust temperature also rises.
As the vacuum decreases, the back pressure of the condenser increases accordingly. A certain back pressure corresponds to a specific saturation temperature, and the exhaust steam temperature is essentially equal to the saturation temperature of the steam inside the condenser; therefore, as the vacuum decreases or the back pressure rises, the temperature of the exhaust cylinder also increases
Why does the exhaust temperature rise when the vacuum level decreases? A decrease in vacuum leads to an increase in exhaust pressure; with constant initial parameters, this results in a reduced effective enthalpy drop of the steam within the turbine, thereby lowering its internal efficiency. In particular, less work is done in the low-pressure cylinder, and some of the steam with certain energy levels is discharged directly, causing the exhaust temperature to rise.