柴油烃组成结构对蒸汽裂解性能的影响

为了拓宽化工原料及实现柴油的优化利用,开展了不同工艺、不同组成柴油的蒸汽裂解性能评价,采用SPYRO模拟软件对6种柴油进行了模拟计算并对其裂解产物收率进行了对比分析。结合全二维气相色谱-飞行时间质谱和核磁共振技术,从柴油裂解产物收率、组成结构及混合裂解性能等方面分析了造成柴油裂解产物分布和收率的差异原因。结果表明:烷烃含量高、馏程窄、碳链短、芳环取代度较高,烷链支化度较低的柴油比较适合作乙烯裂解原料,同时通过与尾油混合裂解,可以进一步优化柴油的裂解性能,为化工行业提供更多元化的原料选择。

依靠科技 从严管理 全面打造一流企业

介绍了乙烯装置开车以来为提高装置技术水平所采取的一系列措施。

Secondary Cracking of Gasoline and Diesel from Heavy Oil Catalytic Pyrolysis

This paper investigated the secondary cracking of gasoline and diesel from the catalytic pyrolysis of Daqing atmospheric residue on catalyst CEP-1 in a fluidized bed reactor.The results show that the secondary cracking reactivity of gasoline and diesel is poor,and the yield of total light olefins is only about 10%(by mass).As reaction temperature increases,ethylene yield increases,butylene yield decreases,and propylene yield shows a maximum.The optimal reaction temperature is about 670℃for the production of light olefins.With the enhance- ment of catalyst-to-oil mass ratio and steam-to-oil mass ratio,the yields of light olefins increase to some extent. About 6.30%of the mass of total aromatic rings is converted by secondary cracking,indicating that aromatic hy- drocarbons are not easy to undergo ring-opening reactions under the present experimental conditions.

Estimating the Operation Status of Steam Cracking Furnace Using Numerical Simulation with Combustion Models

An accurate and complete geometric model was constructed to simulate the combustion, flow and temperature environment in the radiant section of the steam cracking furnace. Simulation of flow and radiation status has utilized the standard k-ε model and P1 model. The finite-rate/eddy-dissipation (finite-rate/ED) combustion model and non-premixed combustion model were both used to simulate accurately the combustion and the operation status of the steam cracking furnace. Three different surfaces of the steam cracking furnace were obtained from the simulation, namely:the flue gas temperature field of the entrance surface in long flame burners, the central surface location of tubes, and the crossover section surface. Detailed information on the flue gas temperature and the mass concentration fraction of these different surfaces in the steam cracking furnace can also be obtained by the simulation. This paper analyzed and compared the simulation results with the two combustion models, estimated the operation status of the steam cracking furnace, and reported that the finite-rate/ED model is appropriate to simulate the steam cracking furnace by comparing key simulation data with actual test data. This work has also provided a theoretical basis for simulating and operating the steam cracking furnace.

Enhancing hydrothermal stability of nano-sized HZSM-5 zeolite by phosphorus modification for olefin catalytic cracking of full-range FCC gasoline

In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano‐sized HZSM‐5 zeolites. A parallel modification was studied by ammonium dihydrogen phosphate impregnation. The modified zeolites were subjected to steam treatment at 800 °C for 4 h (100% steam) and employed as catalysts for olefin catalyticcracking (OCC) of full‐range fluid catalytic cracking (FCC) gasoline. X‐ray diffraction, N2 physicaladsorption and NH3 temperature‐programmed desorption analysis indicated that, although significantimprovements to the hydrothermal stability of nano‐sized HZSM‐5 zeolites can be observedwhen adopting both phosphorus modification strategies, impregnation with trimethyl phosphatedisplays further enhancement of the hydrothermal stability. This is because higher structural crystallinityis retained, larger specific surface areas/micropore volumes form, and there are greaternumbers of surface acid sites. Reaction experiments conducted using a fixed‐bed micro‐reactor(catalyst/oil ratio = 4, time on stream = 4 s) showed OCC of full‐range FCC gasoline-under a fluidized‐bed reaction mode configuration-to be a viable solution for the olefin problem of FCC gasoline.This reaction significantly decreased the olefin content in the full‐range FCC gasoline feed, andspecifically heavy‐end olefins, by converting the olefins into value‐added C2–C4 olefins and aromatics.At the same time, sulfide content of the gasoline decreased via a non‐hydrodesulfurization process.Nano‐sized HZSM‐5 zeolites modified with trimethyl phosphate exhibited enhanced catalytic performance for OCC of full‐range FCC gasoline.

Catalytic cracking of 1-butene to propylene by Ag modified HZSM-5

Silver modified HZSM-5 （AgHZ） zeolite catalysts were prepared by ion exchange method and their catalytic properties in the l-butene cracking reaction were measured. The catalysts were characterized by infrared spec- troscopy with pyridine adsorption （Py-IR）, N2 adsorption and X-ray diffraction （XRD）. The effects of Ag loading and steaming treatment on catalytic performances were studied. It is found that the activity ofHT_SM-5 （HZ） catalyst significantly decreases with the steaming time, whereas AgHZ catalysts show stable activity in the steaming time of 24-48 h and their activities increase with the Ag loading. When the steaming time is 24-48 h, the yield of propylene over HZ catalyst significantly decreases, whereas it is stable over AgHZ catalysts. The AgHZ catalysts with Ag loadings of 0.28%-0.43% （by mass） show similar propylene yields （-30%）, which are higher than that over the AgHZ catalyst with a Ag loading of 0.55% （by mass）. These results indicate that the steam-treated AgHZ catalysts with optimum Ag loadings have higher yield of propylene and are more stable than the steam- treated HZ catalyst. The regeneration stability measurement in butene cracking also shows that the AgHZ catalyst steam-treated under a suitable condition has better stability than the HZ catalyst.

Commercial Test on Technology for High-Temperature Cracking of C5 Fraction to Decrease Olefin Content of Gasoline in DCCU

During June and July 2003, Jingmen Petrochemical Company carried out thecommercial test on technology for high-temperature cracking of C_5 fraction to decrease olefincontent of gasoline in DCCU. The test results showed that the olefin content of DCC gasoline haddecreased from 68.32m% to 42.5m%, meanwhile the propylene yield increased by 0.90m%.

Study on the Catalyst for Catalytic Cracking of Light Gasoline to Produce Propylene

The catalytic cracking of a FCC gasoline fraction （IBP--75℃） provided by the refinery No. 2 of Fushun Petrochemical Company was carried out in a continuous fixed fluidized bed reaction apparatus in the laboratory, using the modified HZSM-5 as the catalyst. The effects of the reaction temperature and loading of lanthanum on the modified HZSM-5 catalyst on the FCC product distribution were investigated. The results showed that the yield of propylene was as high as 39.28% and the yield of aromatics reached 23.57% when the loading of La in the HZSM-5 catalyst was about 8%, when the reaction was carried under atmospheric pressure and at a reaction temperature of 500~550℃and a spatial velocity of 4.5 h^-1. The yield of aromatics dropped by 6.29% during catalytic cracking of gasoline in the presence of the zeolitic catalyst modified with 8% La.

A Mathematical Model Based on Supply Chain Optimization for International Petrochemical Engineering Projects

Based on the study of supply chain(SC) and SC optimization in engineering projects, a mixed integer nonlinear programming(MINLP) optimization model is developed to minimize the total SC cost for international petrochemical engineering projects. A steam cracking project is selected and analyzed, from which typical SC characteristics in international engineering projects in the area of petrochemical industry are summarized. The MINLP model is therefore developed and applied to projects with detailed data. The optimization results are analyzed and compared by the MINLP model, indicating that they are appropriate to SC management practice in engineering projects, and are consistent with the optimal priceeffective strategy in procurement. As a result, the model could provide useful guidance to SC optimization of international engineering projects in petrochemical industry, and improve SC management by selecting more reliable and qualified partner enterprises in SC for the project.

Outlet Temperature Correlation and Prediction of Transfer Line Exchanger in an Industrial Steam Ethylene Cracking Process

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.

Effect of Operating Parameters on Composition of Dry Gas Obtained During Gasoline Cracking Process

The influence of operating parameters on ethylene content in dry gas obtained during catalytic cracking of gasoline was investigated in a pilot fixed fluidized bed reactor in the presence of the MMC-2 catalyst. The results have shown that the majority of dry gas was formed during the catalytic cracking reaction of gasoline, with a small proportion of dry gas being formed through the thermal cracking reaction of gasoline. The ethylene content in dry gas formed during the catalytic cracking reaction was higher than that in dry gas formed during the thermal cracking reaction. The ethylene content in dry gas formed during catalytic cracking of gasoline with a higher olefin content was higher than that in dry gas formed during catalytic cracking of gasoline with a lower olefin content, which meant that the higher the amount of carbonium ions was produced during the reaction, the higher the ethylene content in the dry gas would be. An increasing reaction temperature could increase the percentage of dry gas formed during thermal cracking reaction in total dry gas products, leading to decreased ethylene content in the dry gas. An increasing catalyst/oil ratio could be conducive to the catalytic cracking reactions taking place inside the zeolite Y, leading to a decreased ethylene content in the dry gas. A decreasing space velocity could be conducive to the catalytic cracking reactions taking place inside the shape-selective zeolite, leading to increased ethylene content in the dry gas.

Study of Desorption Agent for LADS Process

This article refers to the procedure for selection, evaluation and development of the LADS-D desorption agent associated with the LADS-A adsorbent used in the non-hydroprocessing adsorptive desulfurization (LADS) process for FCC naphtha developed by LPEC Refining Research Institute. The LADS-D desorption agent can effectively remove the sulfides adsorbed on the LADS-A adsorbent. The saturated LADS-A adsorbent can be instantly regenerated by the LADS-D desorption agent to recover its adsorption activity. The LADS-D desorption agent can not only effectively remove all impurities adsorbed on the adsorbent, but also has strong ability to dissolve the impurities to keep a stable desorption efficiency of adsorbent to be basically commensurate with fresh adsorbent after extended use.

Effects of Reservoir Minerals and Chemical Agents on Aquathermolysis of Heavy Oil during Steam Injection

In order to effectively reduce the viscosity of heavy oil during steam injection, a catalyst system, consisting of reservoir minerals, nickel sulfate, and formic acid, was used to exert catalytic effect on aquathermolysis of heavy crude oil extracted from the Liaohe oilfield. Experimental results indicated that all the reservoir minerals used in the experiment had catalytic effect on aquathermolysis and the oil viscosity reduction rate ranged from 24% to 36% after the aquathermolysis reaction. If nickel sulfate was used as the catalyst and added to the reaction system, the oil viscosity reduction rate could reach 50%. If formic acid was used as the hydrogen donor, the oil viscosity reduction rate could increase further, and could reach up to 71.8%. The aquathermolysis reaction of heavy oil under steam injection condition was affected by the reaction temperature, the reaction time, the dosage of minerals, the catalyst concentration, and the hydrogen donor. The experimental results showed that minerals, catalyst and hydrogen donor could work together to enhance aquathermolysis reaction of heavy oil in the presence of the high-temperature water vapor.

LTAG Technology Passed Appraisal

Recently the LTAG technology combining selective hydro-saturation of LCO with selective catalytic cracking technology for producing high-octane gasoline or light aromatic hydrocarbons has passed technical appraisal.

Effect of Operating Conditions on Olefin Distribution in FCC Gasoline as Part of an Olefin Reduction Process

The effects of operating conditions on the distribution of olefins in the FCC gasoline, obtained during catalytic cracking reaction in the presence of the GOR-Q catalyst and conventional MLC-500 catalyst, have been studied in detail. The test results showed that the GOR-Q catalyst could obviously reduce the content of several kinds of olefins in FCC gasoline. Olefins in the FCC gasoline consist mainly of C5- C7 compounds, that are composed of C=C bond with normal or mono- branched chains. The reduction of gasoline olefin content could be achieved by decreasing the content of above-mentioned olefins. Lower reaction temperature, lower weight hourly space velocity （WHSV） and higher catalyst to oil ratio would help to reduce the content of olefins with a C = C double bond, normal olefins, mono-branched-chain olefins and diolefins. To decrease the loss of gasoline octane number, the operation for olefin reduction should be firstly focused on increasing the catalyst to oil ratio.

Mode splitting of a cavity with a high-density birefringence rubidium vapor in the superstrong coupling regime

The mode splitting in a system with Doppler-broadened high-density two-level atoms in the presence of magnetic field inside a relatively long optical cavity is studied in the superstrong coupling regime(atoms-cavity coupling strength g√N is near or larger than the cavity free-spectral range?FSR).The effect of a magnetic field applied along the quantization axis is used to break the polarization degeneracy of the cavity and thereby introduce birefringence(or Faraday rotation)into the medium.The cavity modes are further split in the presence of the magnetic field compared with the normal case of the multi-normal-mode splitting of the two-level system near the D2 line of87Rb.The dependence of the mode splitting on the magnetic field and the temperature is studied.The theoretical analysis according to the linear dispersion theory can provide a good explanation.