【Q&A Question No. 083】2018.03.24
Thread Content
【Q&A Question 083】March 24, 2018: Briefly explain what the significance of the space velocity in hydrogenation reactions is, and what impact it has on the reaction. Space velocity refers to the amount of feed oil processed per unit volume of catalyst. A high space velocity means that the oil has less contact time with the catalyst, resulting in a lower degree of reaction; conversely, a lower space velocity leads to a higher degree of reaction. There is a certain complementarity between space velocity and reaction temperature – reducing the space velocity can also be achieved by increasing the temperature. Generally, the space velocity is determined by the production requirements. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) Due to the limits on the number of posts in the “One Question per Day” section, “One Image per Day” has been moved to the registered devices section; you can access it through the directory I posted. For management purposes, if you need to access content from a few days ago, please go to the summary post below to enter the “My Registration Season” event – (Note: This event is currently ongoing in the Chemical Engineering section) https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=18978. Summary post of daily questions for the 2018 Chemical Engineering Technology Training section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888971. Summary post of daily images for the 2018 Registered Equipment section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888970. Summary post of Q&A questions for the 2018 Hydrogen Production and Hydrogenation Technology section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888968. Summary post of daily questions for the 2018 LNG Technology Discussion section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1888973. Summary post of Q&A questions for 2017 (updates have started): https://bbs.hcbbs.com/thread-1657793-1-1.html. Summary post of daily questions for 2017 (updates have started): https://bbs.hcbbs.com/thread-1657794-1-1.html. Summary post of daily images for 2017: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1875160. List of daily questions for the 2017 LNG section: https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1804162. Summary post of Q&A questions for 2016 (updates completed): https://bbs.hcbbs.com/thread-1597792-1-1.html
Answer: Space velocity refers to the amount of feed oil processed per unit volume of catalyst. A high space velocity means that the oil has less contact time with the catalyst, resulting in a lower degree of reaction; conversely, a higher degree of reaction is achieved. There is a certain complementarity between space velocity and reaction temperature, and reducing the space velocity can also be accomplished by increasing the temperature. Generally, the space velocity is determined by the production requirements.
Reaction space velocity refers to the amount of gas processed per unit volume of catalyst per unit time under specified conditions. Reducing the space velocity prolongs the reaction time for the reactants, increases the degree of reaction, and raises the conversion rate. However, if the space velocity is too low, the secondary cracking reactions intensify; although the conversion rate can increase, the amount of gaseous hydrocarbons produced also increases accordingly, resulting in a decrease in the liquid yield. The choice of air velocity varies depending on the properties of the feedstock and the activity of the catalyst. An increased air velocity means an increased processing capacity. Therefore, without compromising the degree of raw material conversion, the space velocity should be increased as much as possible.
Reaction space velocity refers to the amount of gas processed per unit volume of catalyst per unit time under specified conditions. Reducing the space velocity prolongs the reaction time for the reactants, increases the degree of reaction, and raises the conversion rate. However, if the space velocity is too low, the secondary cracking reactions intensify; although the conversion rate can increase, the amount of gaseous hydrocarbons produced also increases accordingly, resulting in a decrease in the liquid yield. The choice of air velocity varies depending on the properties of the feedstock and the activity of the catalyst. An increased air velocity means an increased processing capacity. Therefore, without compromising the degree of raw material conversion, the space velocity should be increased as much as possible.
Reaction space velocity refers to the amount of gas processed per unit volume of catalyst per unit time under specified conditions. Reducing the space velocity prolongs the reaction time for the reactants, increases the degree of reaction, and raises the conversion rate. However, if the space velocity is too low, the secondary cracking reactions intensify; although the conversion rate can increase, the amount of gaseous hydrocarbons produced also increases accordingly, resulting in a decrease in the liquid yield. The choice of air velocity varies depending on the properties of the feedstock and the activity of the catalyst. An increased air velocity means an increased processing capacity. Therefore, without compromising the degree of raw material conversion, the space velocity should be increased as much as possible.
Space velocity refers to the amount of feed oil processed per unit volume of catalyst. A high space velocity means that the oil has less contact time with the catalyst, resulting in a lower degree of reaction; conversely, a higher degree of reaction is achieved at lower space velocities. There is a certain complementarity between space velocity and reaction temperature, as reducing the space velocity can also be accomplished by increasing the temperature. Generally, the space velocity is determined by the production requirements.
Reaction space velocity refers to the amount of gas processed per unit volume of catalyst per unit time under specified conditions. Reducing the space velocity prolongs the reaction time for the reactants, increases the degree of reaction, and raises the conversion rate. However, if the space velocity is too low, the secondary cracking reactions intensify; although the conversion rate can increase, the amount of gaseous hydrocarbons produced also increases accordingly, resulting in a decrease in the liquid yield. The choice of air velocity varies depending on the properties of the feedstock and the activity of the catalyst. An increased air velocity means an increased processing capacity. Therefore, without compromising the degree of raw material conversion, the space velocity should be increased as much as possible.
Space velocity refers to the amount of feed oil processed per unit volume of catalyst. A high space velocity means that the oil has less contact time with the catalyst, resulting in a lower degree of reaction; conversely, a higher degree of reaction is achieved at lower space velocities. There is a certain complementarity between space velocity and reaction temperature, as reducing the space velocity can also be accomplished by increasing the temperature. Generally, the space velocity is determined by the production requirements.
Reducing the space velocity prolongs the reaction time of the feedstock, increases the reaction depth, and raises the conversion rate. However, if the space velocity is too low, the secondary cracking reactions intensify; although the conversion rate can increase, the amount of gaseous hydrocarbons produced also increases accordingly, resulting in a decrease in the liquid yield. The choice of air velocity varies depending on the properties of the feedstock and the activity of the catalyst. An increased air velocity means an increased processing capacity. Therefore, without compromising the degree of raw material conversion, the space velocity should be increased as much as possible.
Air velocity (h-1) = Feed rate per hour (t/h) × Raw material density (g/cm3) ÷ Catalyst volume (m3). Reducing the air velocity prolongs the time for the raw materials to react, increases the degree of reaction, and raises the conversion rate. However, if the space velocity is too low, the secondary cracking reactions intensify; although the conversion rate can increase, the amount of gaseous hydrocarbons produced also increases accordingly, resulting in a decrease in the liquid yield. The choice of air velocity varies depending on the properties of the feedstock and the activity of the catalyst. An increased air velocity means an increased processing capacity. Therefore, without compromising the degree of raw material conversion, the space velocity should be increased as much as possible.
Space velocity refers to the amount of feed oil processed per unit volume of catalyst. A high space velocity means that the contact time with the catalyst is short, resulting in a low degree of reaction; conversely, a high degree of reaction occurs at lower space velocities. There is a certain complementarity between space velocity and reaction temperature, and reducing the space velocity can also be achieved by increasing the temperature. Generally, the space velocity is determined by the production requirements.