Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined b...Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.展开更多
Regenerative cooling is considered one of the most effective cooling methods used in liquid rocket engines and has been widely studied in recent years.But the effect of the non-uniform flow in cooling channels caused ...Regenerative cooling is considered one of the most effective cooling methods used in liquid rocket engines and has been widely studied in recent years.But the effect of the non-uniform flow in cooling channels caused by inlet and outlet manifolds did not attract much attention.In this paper,we carried out the coupled flow and heat transfer of combustion and regenerative cooling in a LOX/Methane (LOX means liquid oxygen) engine and compared the results with and without manifolds.Then,three different configurations of the inlet and outlet manifolds were also discussed.The results show that the parameters averaged in the circumferential direction are less affected by the manifolds.However,the existence of the manifolds will make the distribution of mass flow rate as well as wall temperature non-uniform along the circumferential direction.In addition,when the angles between inlet and outlet are 0°,90° and 180°,the maximum temperature difference along the circumference of throat increases by 90.1%,151.2% and 229.5%,respectively,compared with that without manifolds.This indicates that the larger the angle between inlet and outlet,the greater the non-uniformity of mass flow rate and wall temperature along the circumferential direction.As a result,extra thermal stress will be generated which could cause some negative effects on the rocket engines.展开更多
基金Supported by the Major State Basic Research Development Program of China (2012CB720500)the National Natural Science Foundation of China (U1162202, 21276078)+2 种基金the National Science Fund for Outstanding Young Scholars (61222303)the Shanghai Key Technologies R&D Program (12dz1125100)the Shanghai Leading Academic Discipline Project (B504)
文摘Predicting the best shutdown time of a steam ethylene cracking furnace in industrial practice remains a challenge due to the complex coking process. As well known, the shutdown time of a furnace is mainly determined by coking condition of the transfer line exchangers （TLE） when naphtha or other heavy hydrocarbon feedstocks are cracked. In practice, it is difficult to measure the coke thickness in TLE through experimental method in the complex industrial situation. However, the outlet temperature of TLE （TLEOT） can indirectly characterize the coking situation in TLE since the coke accumulation in TLE has great influence on TLEOT. Thus, the TLEOT could be a critical factor in deciding when to shut down the furnace to decoke. To predict the TLEOT, a paramewic model was proposed in this work, based on theoretical analysis, mathematic reduction, and parameters estimation. The feasibility of the proposed model was further checked through industrial data and good agreements between model prediction and industrial data with maximum deviation 2% were observed.
文摘Regenerative cooling is considered one of the most effective cooling methods used in liquid rocket engines and has been widely studied in recent years.But the effect of the non-uniform flow in cooling channels caused by inlet and outlet manifolds did not attract much attention.In this paper,we carried out the coupled flow and heat transfer of combustion and regenerative cooling in a LOX/Methane (LOX means liquid oxygen) engine and compared the results with and without manifolds.Then,three different configurations of the inlet and outlet manifolds were also discussed.The results show that the parameters averaged in the circumferential direction are less affected by the manifolds.However,the existence of the manifolds will make the distribution of mass flow rate as well as wall temperature non-uniform along the circumferential direction.In addition,when the angles between inlet and outlet are 0°,90° and 180°,the maximum temperature difference along the circumference of throat increases by 90.1%,151.2% and 229.5%,respectively,compared with that without manifolds.This indicates that the larger the angle between inlet and outlet,the greater the non-uniformity of mass flow rate and wall temperature along the circumferential direction.As a result,extra thermal stress will be generated which could cause some negative effects on the rocket engines.
