Acid Tar Research Articles

Fluidised-bed incineration of acid tar wastes

Problems experienced with the land fill disposal of highly corrosive acid tar wastes mean that alternative, less environmentally damaging methods of disposal must be employed. The incineration of acid tars, although possessing several advantages over landfill disposal, can lead to unacceptably high SO 2-emission concentrations in the flue gases unless precautions are taken. However, such incinerations have been achieved successfully in the present tests with a two-stage fluidised-bed combustor: the attained combustion efficiencies were high (at around 99%). The use of a fluidised-bed combustor for burning acid tar requires that limestone be added to the bed material in order to provide some degree of sulphur capture. The sensitivity of the SO 2 emission to the limestone concentration (as indicated by the Ca: S mole ratio) fell as the Ca: S ratio was increased. At a Ca: S mole ratio of 4:1, 91% sulphur retention was achieved. During this test, 340 kg/h acid tar was pumped into the bed and burnt there successfully with 98 kg/h coal: the bed's temperature and height, and the excess oxygen-in-flue concentration were kept constant. Ultimately, average SO 2 emission-levels (in the flue gas) of around 417 ppm were thereby achieved; i.e., well below the 600 ppm SO 2-emission limit stipulated by the Commission of the European Communities. Nevertheless, the fluctuations in the SO 2 emissions meant that a slightly higher Ca: S ratio of 5:1 was recommended in order to ensure that the emission levels were consistently below the required limit, i.e., such that 97% of all the mean 48-hourly values would not exceed 110% of the stipulated emission limit.

Hydroliquefaction of Raniganj coal

Hydroliquefaction of a high volatile bituminous coal (Raniganj) was carried out in a batch autoclave. The activities of Harshaw CoMo 0402 T, Fe 2O 3 and SnCl 2 catalysts were evaluated on the basis of the amounts of organic tetrahydrofuran and benzene insolubles. The 250°C + product fraction was separated into preasphaltenes, asphaltenes, neutral oil, tar acids and tar bases by Integrated Solvent Recycle Chromatography. The average molecular weight of each fraction was determined by Size Exclusion Chromatography. The neutral oil fraction (250°C +) was further separated by Gradient Elution Chromatography. The effects of catalyst on the distribution of the above fractions are discussed.

Catalytic hydrodealkylation of tar acids

The catalytic vapour phase hydrodealkylation of LT tar acid fractions to low boiling phenols was studied in a flow system in the temperature range 480–650°C, and over a wide range of space velocities on a chromia—alumina catalyst at atmospheric pressure. The feed, as well as the products, was analysed by gas chromatography. Optimum conditions for maximum yield of lower phenols were established. In the hydrodealkylation of tar acid fractions (i) b 170–210°C, (ii) b 210–230°C and (iii) b 230–270°C, the contents of lower phenols in the liquid products were found to be respectively, 98.6% (55.2 % phenol + 43.4% cresols), 85.5.% (27.4% phenol + 58.1% cresols) and 79.9% (26.8% phenol + 53.1% cresols) at 600°C. The catalyst was found to be highly specific in eliminating the dehydroxylation of phenolic substrates. The physico-chemical properties of the catalyst were determined. Based on an examination of the nature of the catalyst and the product pattern, a tentative mechanism for the reaction has been postulated. The results are interpreted as being due to the formation of chemisorbed phenoxy radicals and their subsequent reaction at the surface of the catalyst.

Temperature dependence of limiting shear viscosity of organic binders

Several formulas describing the temperature dependence of organic binder viscosity were compared. Shear flow was studied for more than 100 binders based on petroleum asphalts, asphalts produced in deasphalting operations, and acid tars. Criteria for selecting a formula were simplicity, universality, minimum number of parameters, ease of theoretical interpretation, and a reasonably small theoretical standard deviation. Shear flow was examined in a rotating viscometer. The smallest standard deviation was derived by the Vogel-Fulcher-Tammann formula; however, it was observed that random changes occurred in the parameters when testing similar materials. It was possible to correct this parameter by assigning an identical value for all of the binders. This value corresponds to the Williams-Landel-Ferry equation.

Characterization of coal hydrogenation products by integrated solvent recycle chromatography

A column Chromatographic technique has been developed for the fractionation of coal hydrogenation products, boiling above 250 °C, into asphaltenes, tar acids, tar bases, neutral nitrogen compounds and neutral oils. The method involves extraction of coal hydrogenation products by n-pentane and the extract is passed through successive columns specially developed for selective retention of tar acids, tar bases and neutral nitrogen compounds. Solvent is simultaneously distilled and recycled. The technique provides a convenient means of characterizing coal hydrogenation products within 10–12 h.

Sedimentation of sulfuric acid in acid tars from current production

Acid tars obtained in treating T-750, KhF-12, and I-8A oils were investigated for purposes of recovering sulfuric acid and asphalt binders from the compositions and of determining the effects of storage time on the recovery. The consumption and sedimentation levels of sulfuric acid during storage for different periods and at different temperatures were assessed. The characteristics of an asphalt binder obtained by neutralizing acid tar with a paste consisting of asphalts from deasphalting operations and slaked lime, followed by oxidation of the mixture with atmospheric air, were determined. The sulfuric acid recovered in the settling process could be burned in order to purify it of organic contaminants.

Scraper film apparatus for sulfonation of petroleum oil

Apparatus for the sulfonation of petroleum oils must provide a highly developed surface for mass transfer, a high heat transfer coefficient for removal of the heat reaction, the possibility of continuous cleaning of acid tar from the surface of the apparatus, optimal residence time of the reactants in the reaction zone, and high capacity with minimum specific energy consumption. Most closely corresponding to these requirements is a scraper type film apparatus with a cleaned surface known as a sulfurator as illustrated in this paper. As shown by the results obtained through calculations based on the mathematical model developed, the hydrodynamic conditions of sulfonation are quite similar for different sizes of equipment if the wettability of their surfaces is the same. The authors also investigated the thermal regime of operation of the apparatus in the third stage after steady-state conditions has been established. It was found that one of the most effective methods for intensifying the sulfonation process is the creation of disperse-film flow in the sulfurator.

Utilization of acid tars

Freshly produced acid tar (FPAT), obtained as refinery waste in treating petroleum oils with sulfuric acid and oleum, contains 80% or more sulfuric acid. Of such tars, pond acid tars, which contain up to 80% neutral petroleum products and sulfonated resins, are more stable, and have found applications in the production of binders for paving materials. In this article the authors are presenting results obtained in a study of the composition and reactivity of FPAT and its stability in storage in blends with asphalts obtained in deasphalting operations, and the possibility of using the FPAT in road construction has been examined. In this work, wastes were used which were obtained in treating the oils T-750, KhF-12, I-8A, and MS-14. Data on the change in group chemical composition of FPAT are shown, and the acidity, viscosity, needle penetration, and softening point of acid tars obtained from different grades of oils are plotted as functions of the storage time. It is also shown that the fresh and hardened FPATs differ in their solubilities in various solvents.

Sulfonation of petroleum fractions by SO3 solution in dichloroethane

The sulfonation of untreated petroleum fractions with gaseous SO/sub 3/ by a conventional procedure gives a large quantity of acid tar that plugs the laboratory sulfonation reactor. To eliminate this problem, the authors performed sulfonation with a solution of SO/sub 3/ in dichloroethane under milder conditions (at 27-35/sup 0/C), feeding the sulfonating agent gradually into an oil-filled flask equipped with a stirrer, keeping the SO/sub 3/ concentration low in the reaction mixture. The materials taken for sulfonation are listed. Results obtained in sulfonating one particular feed by the two different methods of treatment with a solution of SO/sub 3/ in dichloroethane, and by treatment with gaseous SO/sub 3/, are presented. The selectivity of the sulfonation process with respect to oil-soluble sulfonic acids is shown. The characteristics of the sulfonates that were obtained are listed. It is shown that sulfonation by the use of a solution of SO/sub 3/ in dichloroethane is milder than sulfonation by the use of gaseous SO/sub 3/. Sulfonation with the SO/sub 3/ solution can be used in sulfonating lower-quality raw material, including untreated lube fractions.

Temperature, cyanide and phenolic nitrification inhibition

Laboratory evaluations were conducted of the rate of ammonia biooxidation to nitrite by an autotrophic culture of nitrifiers. Ammonia oxidation biokinetics were found to follow Michaelis-Menten-type relationships. Alterations in Michaelis-Menten kinetics were quantified with elevated temperatures and selected trace organics typical of steel industry type wastewaters. Based on data obtained, the toxic inhibition to biological nitrification decreased in the order of free cyanide, coal tar acid phenolics (derived from a coke plant), phenol, 2,3,6-trimethylphenol, 2-ethylpyridine, 2,4,6-trimethylphenol, complexed cyanides and thiocyanate. All substances except free cyanide appear to follow a “shoulder effect” where low levels of inhibitor had no influence on rates of biological nitrification while higher levels had profound effects. Upper temperature limits for stable optimum nitrification is about 30°C with decreasing rates of nitrification on either side of this optimum. Nitrification rates approach zero as temperatures of wastewater approach 45°C.

Acid Tars: Their Production, Treatment and Disposal in the U.K

Acid tar is a hazardous waste produced by several industries which use concentrated sulphuric acid for the treatment of hydrocarbon materials. It is an acrid, corrosive substance with persistent, hazardous properties. Recent concern about the unsatisfactory treatment and disposal of acid tar has led to research into two main areas of interest: the potential problems which might be created by the legacy of historical disposal sites, and the most effective route for acid tar disposal. This work has found that problems will be created by historical dumps of acid tars, due to the potentially high number of tipping sites and the difficulties encountered in site rehabilitation. Incineration of acid tars in cement kilns is the most promising route for present arisings, because it provides effective and permanent disposal. However, more work is needed to assess its technical feasibility and application.

Composition of acid tars from sulfuric acid treatment of petroleum oils

This paper examines the composition of freshly produced acid tars and pond tars, gives an analysis of the acid part of the tars, and obtains data on the change in composition of the acid tar in the course of storage--data that are needed in developing methods for utilizing the tar. The acid-pond tars consist of a mixture of hydrocarbons with a very low content of acids, whereas the freshly produced acid tars consist mainly of sulfuric acid, sulfonic acids, and carboxylic acids. In the course of storage, hardening of acid tars in the volume proceeds through reactions of polymerization, condensation, and oxidation of the surface layer that is in contact with air.

Shakedown operations in commercial production of sulfuric acid from acid tar

The authors describe process technology for processing acid tars to obtain sulfuric acid by means of high temperature splitting to regenerate spent sulfuric acid contaminated with organic impurities. An illustration presents a simplified flow plan for acid tar processing. The authors conclude, from experience with this unit, that process indexes meet design requirements, in particular with respect to the degree of decomposition of the acid tar, the temperature conditions the SO/sub 2/ conversion, the SO/sub 3/ adsorption, and the quality and quantity of the oleum and commercial sulfuric acid obtained.

Composition and properties of acid tar and asphalt produced from acid tar

Composition and properties of acid tar and asphalt produced from acid tar

Production of paving asphalt from acid tar

Production of paving asphalt from acid tar

Coal Liquefaction and Deashing Studies. 2. Solvent Refined Coal Process

In a laboratory-scale study performed under Fort Lewis Solvent Refined Coal (SRC) Pilot-Plant conditions with Kentucky coal, integrated gravity settling produced an SRC with 0.1% ash content if Soltrol 130 paraffinic naphtha was added as antisolvent in 0.3:1 to 0.5:1 antisolvent/liquefaction solvent ratio. Higher ratios produced clogging deposits. SRC pilot-plant filter feed containing 10% solids was used in the tests, and 86% was recovered as deashed product. The separation was sensitive to upflow velocity, and a low velocity of 0.4 in./min was required in an 8 in. settler. A commercial plant processing 25,000 tons/day of coal would require thirty-two 40 ft dia settlers. Recycled Soltrol 130, contaminated with 6% tar acids and approx. 12% nonparaffinic materials, had a much lower efficiency than fresh solvent; the Kauri-Butanol value correlated linearly with the efficiency. Various other aspects of the process are also discussed.

Coexistent psoriasis and bullous pemphigoid: a report of six cases

• Vesicles and bullae developed in six patients with psoriasis while they were undergoing therapy for their psoriasis. Skin biopsy specimens were taken from their lesions and studied for regular histopathologic findings and direct immunofluorescence. These studies confirmed that they had coexistent psoriasis and bullous pemphigoid. A review of the therapy that the patients were given incriminates anthralin, crude coal tar, ultraviolet light, and salicylic acid in the possible cause of the development of their bullous pemphigoid lesions. (<i>Arch Dermatol</i>114:1643-1646, 1978).

Coexistent Psoriasis and Bullous Pemphigoid

Vesicles and bullae developed in six patients with psoriasis while they were undergoing therapy for their psoriasis. Skin biopsy specimens were taken from their lesions and studied for regular histopathologic findings and direct immunofluorescence. These studies confirmed that they had coexistent psoriasis and bullous pemphigoid. A review of the therapy that the patients were given incriminates anthralin, crude coal tar, ultraviolet light, and salicylic acid in the possible cause of the development of their bullous pemphigoid lesions.

Effectiveness of Low and High Tar Acid Creosotes as Determined by Stake Tests

ABSTRACT The 1977 results of stake tests with low and high tar acid content creosotes (high temperature and low temperature creosotes) placed since 1952 are given. It was found that the amount of the residue with boiling temperatures higher than 355°C is correlated with the performance of the pure creosotes, irrespective of the processes used in producing the creosotes. The addition of PCP, copper naphthanate as well as 30% Synthol waxy oil increases performance when compared with pure creosotes.

Characterization of Nitrogen Compounds in Tar Produced from Underground Coal Gasification

Although the major product of underground gasification of coal is a low-Btu gas, approximately 5 percent of the total energy produced is in the form of relatively low-boiling coal tars. These liquid organic compounds, which are produced along with water and the product gas, have been characterized for their potential use as a synthetic liquid fuel. The liquids may also be suitable as a petrochemical feedstock and useful in determining the chemical reactions that are occurring underground. The coal tar material, which was sampled regularly during an underground coal-gasification test, showed variations in boiling ranges of from ambient to 600/sup 0/F and ambient to 950/sup 0/F with little or no residue as determined by simulated distillation. The coal tars were separated into tar acid, tar base, and neutral oil fractions. Of particular interest was the tar base fraction, which was examined in detail and showed the major constituents to be nitrogen-containing alkyl pyridines. The specific identification of several pyridines and the relative concentrations of these compounds produced under varying gasification conditions are discussed. Virtually all the nitrogen-containing compounds are weak bases as shown by potentiometric titration. The sulfur content of the acidic, basic, and neutral fractions is 0.2 to 0.3more » percent.« less