Tarry Substances Research Articles

Experimental study on fixed-bed combustion and agglomeration of sawdust–polyethylene mixtures

ABSTRACT Fixed-bed conversion of polymer-containing waste is one of the most common ways of their disposal. One of the problems with such conversion is the cross-sectional non-uniformity of the bed, the formation of agglomerates, and burnouts. The agglomeration process essentially depends on the weight fraction of melting components (plastic materials). Usually, the non-uniformity of the bed is associated with the random nature of the packing (fluctuations of local concentrations and percolation properties). In the present work, we investigate the agglomeration process caused by non-uniform conditions of heat transfer. To this end, combustion of model waste (mixtures of sawdust and polyethylene with a content of the latter of 20–80) is experimentally studied in a laboratory setup with a bed height of about 10 cm. Due to the heat supply through the wall, airflow, non-uniformities developed, associated with different gas permeability in different areas of the bed. The transition from intense thermal decomposition to smoldering is achieved in 5–15 min (the higher the polyethylene content, the shorter the transition time). When the polyethylene content is high, the permeable area decreases so that the air velocity becomes high enough to entrain sawdust particles. As the polymer decomposes, tarry substances are released and form dense deposits in the gas cooling and cleaning system.

Seasonal variability of leaf water capacity and wettability under the influence of pollution in different city zones

Can dust and tarry substances that are rich in polycyclic aromatic hydrocarbons (PAHs), which are deposited on leaves, cause changes in the water retention of tree crowns? It is hypothesized that the contact angle between droplets and a leaf's surface and water capacity changes because of the content of PAHs. This angle is treated as a bioindicator of environmental pollution. The goal of this study was to analyse the relationship between rainfall water capacity and wettability of small-leaved lime and poplar in different zones in a city centre during the period from April through November. We implemented a series of simulated rainfall and angle measurements under laboratory conditions of tree twigs collected at three locations inside the city centre and one from an area outside the city. The background for the water capacity values were results acquired from selected PAHs contents determined in leaves using high-performance liquid chromatography (HPLC), and images of the leaves' surface were acquired via Scanning Electron Microscope (SEM). Based on the obtained results, we concluded that there were significant differences in water capacity between the areas for each month. In the city centre, water capacity from April to July was lower than that in the forested area. From July to the end of the growing season, the water capacity was lower in the city compared to the forest area. The contact angle was strongly correlated with water capacity. With a decreasing contact angle, the raindrops increasingly adhered to the leaf surface, and water capacity increased.It was found that the effects of pollution on water capacity cannot be ignored in developing forecasts or in models describing ecosystem and hydrological changes in natural and urbanized environments.

On the limitation of the term petroleum products in the determination of the oil pollution of bottom sediments

Problems related to the determination of the oil pollution of bottom sediments are discussed. Tarry substances resistant to degradation, whose content can be as high as 50% on a total oil basis, are accumulated in the bottom sediments. The conventional term petroleum products, which implies only a hydrocarbon fraction, does not adequately describe these substances; because of this, the really evaluated level of the oil pollution of bottom sediments becomes underestimated to a considerable degree. We proposed to determine tarry substances in bottom sediments by fluorescence spectrometry at 490–510 nm in combination with a stage of the chromatographic preconcentration and separation of oils and petroleum products into the following main group components: hydrocarbons, tars, and asphaltenes. The substances coextracted with the petroleum products (pesticides, phenols, pigments, etc.) occurred in a chromatographic zone of tars and asphaltenes, but they fluoresce at other wavelengths and do not interfere with the determination. The typical chromatograms of hydrocarbons from the bottom sediments of different water bodies obtained by gas chromatography are given.

Состав структурных фрагментов, связанных эфирными и сульфидными мостиками в молекулах смолистых веществ природного битума Ашальчинского месторождения (Татарстан)

Состав структурных фрагментов, связанных эфирными и сульфидными мостиками в молекулах смолистых веществ природного битума Ашальчинского месторождения (Татарстан)

Justification of Well Type and Design Depending on Depletion Mechanism of High-Viscosity Oil Production

While choosing an optimal field development strategy it is necessary to take into account the possible effects of oil structural-mechanical qualities. The presented methods allow estimating the effect of structural-mechanical qualities of the production of oil with high levels of asphaltene and tarry substances. After completing all calculations and designing, a parameter set is created for optimal depletion mechanisms of the production of nonlinear high-viscosity non-Newtonian oil.

Cold Hard Cache: The Arctic Drilling Controversy

On 27 May 2010, with crude oil gushing into the Gulf of Mexico after the explosion of BP’s Deepwater Horizon oil rig, the Obama administration announced it would pause offshore drilling plans in the Arctic Ocean, one of the planet’s most pristine ecosystems.1 Hailed by environmental groups, the decision was a major setback to the oil industry, which was gearing up to tap what’s expected to be vast amounts of oil and gas lying under the Arctic’s treacherous waters, wher e sustained winds blow at 30 to 50 miles per hour, and menacing chunks of floating “pack ice,” some hundreds of feet wide and dozens of feet thick, threaten marine traffic. With shallow-water, near-shore reserves increasingly tapped out in the Gulf of Mexico, oil companies are being forced into more challenging terrain to sustain domestic energy production. That means pushing into much deeper geology in the Gulf of Mexico—much of it more than a mile underwater—and also into ecologically fragile locations off the coast of Alaska. In decades past, oil companies didn’t prioritize the offshore Arctic for development because drilling there was too expensive. Oil prices simply weren’t high enough to sustain production windows limited to just a few months in summer, when thawing seas make drilling possible, explains Layla Hughes, an attorney and senior program officer for Arctic oil, gas, and shipping policy at the WWF in Juneau. But as economies in China, India, and Brazil have grown, global fuel demands have risen accordingly,2 driving prices higher and making offshore Arctic development economically viable. “Prices started going up in the late nineties, and they’re projected to stay high,” Hughes says. Oil companies now have to prove they can extract those resources safely, without compromising an ecosystem that might never recover from the effects of a large blowout. Dana Wetzel, an ecotoxicologist at Mote Marine Laboratory with 10 years’ research experience in the Arctic, says oil degradation depends largely on temperature. When exposed to frigid water, oil turns quickly into a thick, tarry substance that microbes can’t easily degrade. The 1989 Exxon Valdez spill, which occurred roughly 400 miles south of the Arctic Circle, likely underestimates the full environmental impact of a blowout even farther to the north. “The Valdez was a horrible spill in a rich marine ecosystem, but you didn’t have the oiling of the sea ice,” Wetzel says. “If you taint sea ice with oil, you’re never going to get rid of it. And those ice floes are home to walruses, seals, and polar bears. Many people survive up there by subsistence hunting, and to contaminate their food is one of the worst moral blows you can deliver to those communities.”3

Influence of different chemical reagents on the preparation of activated carbons from bituminous coal

Activated carbons were prepared by chemical activation from bituminous coal with three chemical reagents, ZnCl 2, H 3PO 4 and KOH. The activation consisted of impregnation of a reagent followed by carbonization in nitrogen at various temperatures. A thermogravimetric study showed that these reagents were capable of suppressing the evolution of tarry substances during carbonization. Because of carbon oxidation and gasification mechanisms, activation with KOH resulted in a lower carbon yield than those with ZnCl 2 and H 3PO 4. For each activation process the porosity of the resulting carbons increased with the carbonization temperature to a maximum and then began to decrease with further increase of the temperature. The maximum surface areas obtained from the activation with ZnCl 2, H 3PO 4 and KOH are 960, 770 and 3300 m 2/g, respectively. The results of the present work suggest that ZnCl 2 and H 3PO 4, which are acidic, are not suitable for preparing high-porosity carbons from bituminous coal, while carbons with very high porosity can be produced with bases such as KOH. An increase in particle size of the coal precursor was found to cause a reduction in both yield and porosity of the resulting carbons.

Solvent cleansing of the surface of carbon filaments and its benefit to the electrochemical behavior

The surface of vapor-grown carbon filaments (types H79 and ADNH of Applied Sciences Inc.) was found to be covered with a layer of tarry substance (comprising primarily polyaromatic hydrocarbons and originating from the filament growth process), which degraded the electrochemical performance (as shown by cyclic voltammetry using the Fe(CN) 6 −3 −4 redox couple), increased the filament-to-filament electrical contact resistivity in a binderless filament compact and decreased the filaments' compactability. Solvent cleansing removed the tarry coating, thereby exposing oxygen-containing functional groups. The coating was more tenacious on H79 than ADNH filaments. For ADNH, either acetone or methylene chloride cleansing removed the coating; for H79, methylene chloride cleansing removed the coating, but acetone cleansing did not. Chopping the cleansed filaments in a liquid medium using a blender helped maintain ADNH filament compaction after pressure release, thereby further improving the electrochemical performance, though it was not necessary for H79. Cleansing and chopping raised the electron transfer rate constant (k s) of ADNH by up to 500%, so that k s up to 0.02 cm/s was attained, and decreased capacitance and electrochemical area. For H79, cleansing removed the high residual current density, but degraded the rate constant by up to 70%. Graphitization decreased the electrical resistivity and increased the compactability of ADNH, but degraded the electrochemical performance because of a change in surface functional groups. In contrast to conventional carbon paste electrodes, carbon filament compacts, if not graphitized, did not require any binder.

Multi-stage coking for more tar and formed coke of higher strength: 4. Formed coking of residues extracted from heat-treated single coals with a mixed solvent of N-methylpyrrolidinone and carbon disulphide

A mixed solvent of N-methylpyrrolidinone and carbon disulphide (MP-CS 2) was found to extract very large amounts of tarry substance from bituminous coals of C% above 80% and the residue provided a high mechanical strength of its formed coke. However, coals of C% below 80% exhibited rather low solubility and the formed cokes from their residues were not strong enough. The preheat-treatment at 450 °C under 1 MPa nitrogen pressure increased significantly the extract yield and tensile strength of the formed cokes from the residues especially with coals of C% below 80%. The origins of coking properties of the coal are briefly discussed based on the present particular results obtained by MP-CS 2 extraction.

Observation of volatile cloud formation during the early stages of pulverized coal combustion

During the early stages of combustion when bituminous coal particles are in a nearly single particle combustion environment, a surrounding mantle of volatile products is observed. Initially, the cloud is of spherical shape and almost concentric with the particle. As the reaction progresses, more material is ejected in the shape of jet-like tails. This rapid mass release was observed through in-situ high speed photographs of particles in combustion environment, and was also confirmed by examining cross sections of the quenched samples of coal particles. The inner structure became porous, while base material softened and some portion of it was ejected due to high pressure build up inside. Direct sampling of the partly burned coal particles revealed that the material in the volatile cloud contained tarry substances and small sized particle fragments in addition to gaseous volatiles. These solid and condensible substances were seen as a luminous envelope which implied that they participated in the radiative transfer process.

Removal of tarry substances from industrial waste gases

Removal of tarry substances from industrial waste gases

Glycosylamines

This chapter discusses the glycosylamines. The name “glycosylamine” is considered as the general name of the compounds resulting from the condensation of aldoses and ketoses with ammonia and amines. Nearly all glycosylamines are colorless, although the compounds made from nitroarylamines are yellow or orange. Some are bitter to the taste. Their stabilities differ considerably. The N -arylaldosylamines of aniline and of the toluidines turn brown on normal storage at room temperature for a month or so and eventually decompose completely in black, tarry substances. The acetates are the best known derivatives of the glycosylamines. Direct acetylation by methods involving hot acetic anhydride is often unsuccessful, leading only to discolored oils. The most generally useful method consists in treating the glycosylamine with excess acetic anhydride in pyridine solution at 0° for periods varying from several hours to two days. Indirect methods for preparing such acetates include the condensation of O -acetyl-aldosyl bromides or aldohexose 2, 3, 4, 6-tetraacetates with the appropriate amine, usually in chloroform or ether solution.

Application of the Robinson dehydrogenation reaction. I. A synthesis of 2, 3-dimethoxy-6H-indolo [2, 1-a] isoindole.

For the purpose of examining the scope of the Robinson dehydrogenation reaction as a tool for building up polynuclear condensed nitrogen-ring compounds, in which the nitrogen atom is common to two rings, 1-(3', 4'-dihydroxybenzyl) isoindoline and its N-methyl derivative were treated with chloranil in ethanolic solution. The former gave the expected 2, 3-dihydroxy-6H-indolo[2, 1-a] isoindole, characterized as its dimethyl derivative, but the latter failed to give any definite oxidation product under a variety of working conditions, yielding only intractable, dark blue tarry substance.

Observations on the Action of Sulfur Monochloride on Bituminous and Tarry Substances and Hydrocarbon Oils

Observations on the Action of Sulfur Monochloride on Bituminous and Tarry Substances and Hydrocarbon Oils

2. Note on the Action of Ammonia on Dicloracetone

For some time I have been engaged in an attempt to replace the chlorine in monochloracetone and dichloracetone by other radicals, and with this object have acted upon them by means of cyanide of potassium, acetate of soda, and aqueous and alcoholic ammonia. In all of these cases the chlorine was removed as chloride of the alkaline metal or ammonium, and brown, tarry substances were produced, which resisted all attempts at purification. By the action of dry ammonia gas, however, I have obtained somewhat better results.