钙盐清净剂对生物质燃油碳烟的分散性影响

摘要

Soot dispersity is one of the main functions of the detergent. It was investigated the influence of the three kinds of calcium salt detergents on the dispersity of the biofuel soot (BS) in liquid paraffin (LP, simulant of base stock) by means of viscosity, spot experiment, sedimentation and particle size distribution simulation method. The calcium salt detergent included higher total base number synthesis calcium sulfonate T106, alkyl calcium salicylate T109 and higher total base number sulfuration calcium alkylphenol T115B. The disperse mechanisms of calcium salt detergent to BS were investigated by means of X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The results showed that the dispersed systems with high concentration of BS presented obvious phenomenon of shear thinning, which was similar to that of non-Newtonian fluid. Adding T109 to the LP contaminated with BS, the disperse system showed the minimal dynamic viscosity, the maximum sludge dispersion threshold, the largest drop ratio of supernatant liquid height, the minimum aggregate particle size range and the average particle size in n-heptane. T109 was the excellent additive to disperse BS in LP. The mechanisms analysis showed that the O-containing polar groups (such as carboxyl or hydroxyl) on the surface of BS were liable to adsorb calcium salt detergent through hydrogen bond or acid-base function. At the same time, the lipophilicity of non-polar chain alkane group of calcium salt detergent formed steric hindrance in the oil and impeded BS particle aggregation. Consequently, the calcium salt detergent can disperse the BS particle in the oil.%碳烟分散性是清净剂的主要功能之一，采用黏度法、斑点实验法、沉降法及粒径分布法4种模拟实验考察3种钙盐清净剂（高碱值合成磺酸钙 T106、烷基水杨酸钙 T109、高碱值硫化烷基酚钙 T115B）对生物质燃油碳烟（BS）在液体石蜡（LP，基础油模拟物）中分散性能的影响，并借助 X 射线光电子能谱仪和傅里叶变换红外光谱仪分析钙盐清净剂对 BS 的分散机理。结果表明，BS 浓度高的分散体系剪切稀化明显，有非牛顿型流体特性。相比之下添加 T109时分散体系黏度最小，油泥斑点分散值最大，清液层高度下降率最大，在正庚烷中团聚体的粒径范围和平均粒径最小，T109对 BS 在 LP 中的分散效果最好。机理分析显示 BS 表面含有羧基、羟基等含氧极性基团，可与钙盐清净剂的极性端通过氢键或酸碱作用吸附清净剂；同时，钙盐清净剂中非极性端的烷烃基团的亲油性又使得烷烃基团在 LP 中形成空间位阻，阻碍 BS 颗粒团聚，从而起到分散 BS 的效果。