催化裂化过程中骨架异构化反应的研究 Ⅱ .催化裂化工艺过程中操作参数对骨架异构化反应的影响

SKELETAL ISOMERIZATION REACTIONS IN CATALYTIC CRACKING Ⅱ. Effect of Operating Parameters on Skeletal Isomerization Reaction in Catalytic Cracking Process

在小型固定床反应器、美国Xytel公司ACE(R型)装置和提升管催化裂化装置(Riserunit,RU)上,以Marbon减压馏分油、中间基性质的混合油(85%管输VGO掺混15%管输VR,质量分数)和石蜡基性质的减压蜡油(VGO)掺减压渣油(VR)构成的混合油(70%大庆VGO掺混30%大庆VR,质量分数)为催化进料,考察了主要操作参数对骨架异构化反应的影响。研究表明,反应温度、剂/油质量比(m(Catalyst)/m(Oil))、催化剂上焦炭沉积状况、反应质量空速和蒸汽注入量等操作参数对催化裂化过程中的骨架异构化反应均有影响。催化裂化过程中骨架异构化反应是放热过程,高反应温度会抑制骨架异构化反应。提高m(Catalyst)/m(Oil)可以增强催化裂化过程中的骨架异构化反应。焦炭对催化剂酸中心的覆盖能抑制骨架异构化反应,但其影响幅度小于对裂化反应的影响。骨架异构化反应是一个快速反应,低反应温度下减少反应时间会增强催化过程中的骨架异构化反应。水蒸气注入量的增加(即降低烃分压)会减少催化过程中的骨架异构化反应。

The effects of main operating parameters on skeletal isomerization reaction in catalytic cracking processes were studied on bench-scale fixed bed reactor, Advanced Catalyst Evaluation (ACE) unit (Model R) and Riser unit (RU) pilot plant with Marbon VGO, intermediate base 85% (mass fraction) Shengli VGO mixed with 15% (mass fraction) Shengli VR and paraffinic base 70% (mass fraction) Daqing VGO mixed with 30% (mass fraction) Daqing VR as feedstocks. Operating parameters, such as reaction temperature, catalyst to oil mass ratio, coke deposition, mass hour space velocity (MHSV) and amount of atomizing steam all showed some influence on skeletal isomerization reaction. Skeletal isomerization reaction is an exothermic process, which is suppressed under high reaction temperature conditions and enhanced by increasing catalyst to oil mass ratio. The suppression of skeletal isomerization caused by coke deposition on the active sites of catalyst is in a lesser extent than that of cracking. To react at a shorter contact time can enhance skeletal isomerization reaction under lower reaction temperature, since isomerization is a relatively quick reaction during catalytic cracking process. Using higher amount of atomizing steam resulted in a lower hydrocarbon partial pressure decreased extent of skeletal isomerization reaction in catalytic cracking process.