Abstract: This paper reviews the extraction methods of humic acid from lignite, the structure, chemical composition and characteristics of humic acid, and the production of humic acid fertilizer. Oxidative pretreatment of coal can increase the extractability of humic acid, but needs to improve its economic potential. The apparent molecular masses are determined by gel permeation chromatography and size exclusion chromatography. Mass spectrometry and flow field flow fractionation applied to molecular masses measurement has recently received great attention. Humic acid are supramolecular associations of diverse, relatively low molecular mass. Humic acid is mainly composed of aromatic acids and phenolic compound. Humic acid has been characterized by using tetramethyl-ammonium hydroxide pyrolysis-gas chromatography-mass spectrometry. Electrophoretic patters are often called fingerprints and can potentially be used for the classification. Phosphate-metal-humic (P-M-HA) complexes are the main component of humic acid fertilizer, and are able to decrease phosphate fixation in soils and increase phosphate uptake, which is a research hotspot in the area of humic acid.

Key words: diluted heavy crude, long-distance pipeline, field experiments, centrifugal pump, performance curve

摘要： 原油长输管道上的外输泵能耗巨大,在多年的使用之后,其特性曲线会出现一定程度的偏差,有必要对泵性能曲线进行校核。根据相关规范,本文对某原油管线上的3种外输离心泵展开了现场工业实验,测试了它们输送掺稀稠油(黏度为199.5mm²/s、190.2mm²/s)的性能,绘制了实际的扬程-流量曲线和效率-流量曲线。基于离心泵出厂时的性能曲线和现场实验的油性,利用相关式换算得到离心泵输油时的理论性能曲线。与输水时相比,离心泵输送掺稀稠油时最高效率点效率下降了21.8%~31.2%。比较离心泵的实际性能曲线和理论性能曲线表明:对于同样流量点,使用多年的离心泵的效率降低了1.5%~9.8%;离心泵扬程也有1%~10%不等的损失,并且随着流量增大,扬程下降幅度越大。现场测试得到的泵性能特性曲线为日后输油泵的工艺计算和能耗分析提供了依据。

关键词: 掺稀稠油, 长距离输送, 现场实验, 离心泵, 性能曲线