Науково-практичні основи поліпшення ефективності зневоднення кам'яновугільної смоли коксохімічного виробництва

Abstract

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.17.07 − хімічна технологія палива та паливно-мастильних матеріалів. – Національний технічний університет «Харківський політехнічний інститут», Харків, 2023 р. Дисертацію присвячено створенню науково–практичних засад зневоднення кам’яновугільної смоли шляхом визначення закономірностей формування сукупності чинників, що визначають стійкість системи «кам'яновугільна смола-надсмольна вода», а також розробки методів реагентного впливу і спрямованого зниження в'язкості системи, що обумовлюють підвищення якості товарної кам’яновугільної смоли у умовах діючого коксохімічного підприємства. Досліджено особливості формування емульсій на основі кам’яновугільних смол, що пов’язані зі ступенем піролізованості смоли і розділенням смоло–водяної суміші. Розроблено теоретичні основи впливу на реологічні характеристики кам’яновугільної смоли при підвищенні температури, при змішувані смол, добавок нафталіну, антрацену та антраценової фракції, впливу компонентного складу та полярних речовин. Досліджено в'язкість високопіролізованих смол у залежності від вмісту та характеру агрегації дисперсних частинок, надано приклад руйнування агрегатів нерозчинних у хіноліні під час змішування смол з різним гранулометричним складом речовин нерозчинних у хіноліні. Вибрано деемульгатор та визначено його характеристики поверхневої активності, обґрунтовано вибір добавки до основного деемульгатора з метою поліпшення реагентного зневоднення важкої кам'яновугільної смоли, досліджено реагентне зневоднення кам'яновугільної смоли за допомогою композиційних реагентів–зневоднювачів важких нафт. Наведено практичні приклади і особливості застосування деемульгаторів на різних технологічних процесах відділень конденсації коксохімічних виробництв України і результати дослідно–промислових випробувань з реагентного зневоднення з подачею антраценової фракції та комплексного реагенту з добавками «Діссолван».Dissertation for the degree of Doctor of Technical Sciences in specialty 05.17.07 – chemical technology of fuel and fuels and lubricants – National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2023. The manuscript is devoted to a critical analysis of current concepts regarding the peculiarities of the formation and thermochemical destruction of emulsions based on coal tar, discusses the difficulties, peculiarities and development of the processes of coal tar settling in production conditions. The peculiarities of the formation of emulsions based on coal tar are considered, which are related to the degree of pyrolysis of the tar and the condensation and separation of the tar–water mixture in the condensation department of coke production. The influence of the organic and mineral composition of coal particles on the stabilization of emulsions, the influence of the salt content of collecting main flush water on the stabilization of the emulsion, and the reasons for the undesirable formation of direct emulsions of the "tar in flush water" type are also considered.The scientific foundations have been developed concerning of the influence on the rheological characteristics of coal tar at increasing temperature, miscibility of tars, additives of naphthalene, anthracene and anthracene fraction, the influence of component composition and polar substances. Influence on the viscosity of the dispersion medium can reduce the obstruction of droplet coalescence and improve the process of demulsifier diffusion to the interface. The viscosity of highly pyrolyzed tars depending on the content and nature of aggregation of dispersed particles is considered, and an example of the destruction of quinoline–insoluble aggregates during the mixing of tars with different particle size distribution of quinoline–insoluble substances is given. The scientific and practical bases for the thermochemical destruction of emulsions of the "water in coal tar" type were developed. The demulsifier was selected and its surface activity characteristics were determined. The decrease in the demulsification efficiency with a significant increase in the degree of pyrolysis of the tar is due to the strengthening of the armor shell around the dispersed water droplets in heavy tar. Probably, there was an increase in the hydrophobicity of quinoline–insoluble dispersed particles, which is associated with an increase in their content in coal tar by 3–4 times. Such an increase in hydrophobicity could be due to their self–aggregation, with intermolecular interactions occurring between functional groups that reduced the polarity of the formed aggregates. Such aggregates, locked in on themselves by functional groups, lost their ability to wetting due to a decrease in polarity.Therefore, when changing the degree of pyrolysis of coal tar and the nature of dust removal from the coking chamber, it is advisable to modify the base reagent by increasing the wetting and detergent characteristics. To increase the efficiency of the demulsifying effect of the reagent, it is desirable that the surfactant complex has a wetting and detergent effect to destroy aggregates that block the coalescence of water droplets. The choice of an additive to the main demulsifier was substantiated in order to improve the thermochemical dehydration of heavy coal tar, and the thermochemical dehydration of coal tar using composite reagents–dewatering agents for heavy oils was investigated. It was found that a deeper reduction in tar viscosity with the addition of a demulsifier corresponds to a higher dehydration efficiency, and for more viscous media, the influence of the reagent's RSN index should be taken into account. A line of demulsifying compositions was compiled in accordance with the manufacturers' recommendations for the separation of heavy oils, which contained two conditional groups: with an estimated relative solubility index of mixtures of 8.2–9.5 and 10.5–11.2. Dehydration showed that the highest destructive ability of emulsions against the heaviest tar samples was demonstrated by the composite reagent with the highest relative solubility index. At the same time, the compositions of demulsifiers with RSN 8.2–9.5 and the demulsifier PM showed practically no dehydration effect when dehydrating the superheavy resin. With a slight decrease in the degree of pyrolysis of the tar, the dependence of the efficiency of tar dehydration on the relative solubility index decreases. This confirms the assumption that in order to destroy emulsions based on superheavy tars, the demulsifier reagent must be given some hydrophilicity to wet the emulsion stabilizers. Based on the existing experience of using the demulsifier PM (oil–soluble and water–soluble) in the condensation department of coke plants, it can be stated that when PM is dosed into the tar path behind the mechanized clarifier (with the return of settled water to the gas collector cycle at maximum dilution), there is no secondary emulsification and foaming of liquids. To prevent possible disruptions in the operation of the condensation unit during sharp fluctuations in tar quality or during the resumption of demulsifier supply, it is necessary to adjust the demulsifier dose in the laboratory with an assessment of the quality of settled water using the "bottle test". Practical examples and peculiarities of demulsifiers application in different technological processes of condensation departments of coke production in Ukraine were shown. The results of pilot tests on thermochemical dehydration with the supply of anthracene fraction and complex reagent with «Dissolvan» additives in the condensation department of the recovery shop No. 2 of PJSC "AKKhZ" were presented. A scheme of safe and effective dosing of the tar solvent–anthracene fraction was introduced, which allowed to ensure the fluidity of the tar in the critical state of increased pyrolysis of the tar on an underloaded coke oven battery and to facilitate the dehydration of the tar. Comparison of the degree of dehydration of the developed method with existing similar reagents shows that the efficiency of previously used demulsifiers for tar settling in industrial conditions was 40–80 % for the AZNII reagent and 73–75 % for the PM reagent, but for tar with a density of 1200 kg/cm3. For dehydration of tar with a density of 1245–1280 kg/m3 and an initial moisture content of 16–19%, the efficiency of the composition of the demulsifier "PM" under industrial conditions was at least 50%.