催化裂化装置闷床与喷燃烧油技术的应用

一、前言随着社会主义经济开放改革的发展以及石油化工工业的扩大,国内催化裂化装置相续建成投产.装置型式越来越多,工艺技术已经达到国际先进水平.但是,各型催化裂化装置的生产开工与事故停工或检修步骤都是相同的.

船用柴油机颗粒捕集器主动再生技术研究

柴油颗粒捕集器(DPF)是船用柴油机颗粒物排放治理的重要技术手段之一,而喷油燃烧再生是实现DPF高效再生的一种有效方式;本文通过CFD仿真和实验相结合的方式,研究采用壁流式DPF过滤体与燃油助燃主动再生技术组合方法对颗粒捕集器的捕集和再生特性的影响;结果表明:正常运行工况下,DPF过滤器对颗粒物捕集效率高达94%以上;采用喷油燃烧主动再生方式,过滤器再生性能和耐久性能均较好;但喷油燃烧过程不易控制,需对燃烧器结构进行优化,如增加稳焰盘;利用CFD仿真能对DPF过滤器内燃烧和温度分布进行有效预测,对颗粒物捕集器产品的设计和应用具有向导作用。

INVESTIGATION IN REDUCING EXHAUST EMISSIONS FROM TWO STROKE MOTORCYCLES

Test results of reducing two stroke motorcycle emissions with new type carburettors and electronic fuel injection systems are presented. Analyses and comparison between different systems are discussed. The adoption of electronically controlled injection and corresponding electronic control technique is an effective measure of prolonged vitality to improve emissions from two stroke motorcycles. Suggestions about the strategic steps of China′s motorcycle emission control are proposed.

Effect of equivalence ratio on diesel direct injection spark ignition combustion

Aviation heavy-fuel spark ignition(SI)piston engines have been paid more and more attention in the area of small aviation.Aviation heavy-fuel refers to aviation kerosene or light diesel fuel,which is safer to use and store compared to gasoline fuel.And diesel fuel is more suitable for small aviation application on land.In this study,numerical simulation was performed to evaluate the possibility of switching from gasoline direct injection spark ignition(DISI)to diesel DISI combustion.Diesel was injected into the cylinder by original DI system and ignited by spark.In the simulation,computational models were calibrated by test data from a DI engine.Based on the calibrated models,furthermore,the behavior of diesel DISI combustion was investigated.The results indicate that diesel DISI combustion is slower compared to gasoline,and the knock tendency of diesel in SI combustion is higher.For a diesel/air mixture with an equivalence ratio of 0.6 to 1.4,higher combustion pressure and faster burning rate occur when the equivalence ratios are 1.2 and 1.0,but the latter has a higher possibility of knock.In summary,the SI combustion of diesel fuel with a rich mixture can achieve better combustion performance in the engine.

Multidimensional modeling of Dimethyl Ether(DME) spray combustion in DI diesel engine

In the present study a modified CFD code KIVA3V was used to simulate the spray combustion in a small DI diesel engine fueled with DME. The improved spray models consider more spray phenomena such as cavitation flow in nozzle hole, jet atomization, droplet second breakup and spray wall interaction. Otherwise, a reduced DME reaction mechanism is implemented in the combustion model, and a new turbulent combustion model?Partial Stirred Reactor (PaSR) model is selected to simulate the spray combustion process, the effects of turbulent mixing on the reaction rate are considered. The results of engine modeling based on those models agreed well with the experimental measurements. Study of temperature fields variation and particle traces in the combustion chamber revealed that the engine combustion system originally used for diesel fuel must be optimized for DME.

Improvement of Emissions and Burning Limits in Burner Combustion using an Injector on the Concept of Fuel-Water Internally Rapid Mixing

This study tried to apply biomass fuel to clean burner combustion under high load conditions by water addition. A newly developed injector mixes fuel rapidly with water inside of the injector with support of atomizing air. The mixture composed of three-fluid is injected as spray into a flame stabilizer of burner. Investigation of emission performance of this injector shows that the internally rapid mixing type of injector is hopeful technique to introduce water into burner combustion. Combustion by this injector emits exceedingly less particulate matters at high load. NOx emission is strongly dependent on water flow rate.

Numerical study of high-pressure GO_2/GH_2 combustion of a single-element injector

A single-element shear-coaxial combustor using gaseous hydrogen(GH2) and oxygen(GO2) was designed and hot-tested.The wall temperature was measured.The combustion flowfield of this GH2 /GO2 single-element combustor was modeled by RANS(Reynolds Averaged Navier-Stokes) and LES(Large Eddy Simulation) methods respectively.The impact of using various turbulence and turbulent combustion models was investigated to obtain the model combination which best represented the experimental data in the RANS modeling.The flamelet model was used in the LES modeling and the validity of its application to the GH2 /GO2 combustion in the combustor was carefully examined.The combustor wall heat flux distributions of both RANS and LES results show good agreement with the experimental data.The experimental wall temperature distribution can be clearly explained through analyzing the inner flowfield structure.The results indicate that both RANS and LES used in this paper can give good predictions of the development of the whole flowfield and the combustion completion length.LES can resolve large-scale flow motions in the combustor and accurately predict the influence of the wall heat loss on the combustion efficiency.

Investigation of the Effect of Pilot Burner on Lean Blow Out Performance of A Staged Injector

The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real engine.In this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test section.The experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.