Showing papers on "Wet oxidation published in 1986"

Oxidation of wastewaters

Abstract: The present invention relates to an improved process for the wet oxidation of water soluble organic pollutants or of an aqueous suspension of organic pollutants. In the contacting of an oxidizing gas and a polluted aqueous phase, the improvement comprises forming a fine mist of the polluted aqueous phase in the presence of the oxidizing gas, thereby increasing the interfacial area between the gas and the polluted aqueous phase. Then the formed mist is introduced into a heated reaction chamber under pressure, thereby enhancing the rate of the destructive oxidation of the organic pollutant by the increase in mass transfer between the gaseous phase and the aqueous mist, the reaction temperature being selected to favor rapid destruction of the pollutant without the formation of stable intermediate reaction products. After destruction of the pollutants, the reaction mixture is allowed to flash off at a pressure lower than the reaction pressure.

Method of removing scale from wet oxidation treatment apparatus

Abstract: A method of removing scale from the surfaces of a fluid treatment apparatus by directing a base solution and an acid solution through the fluid treatment apparatus. The fluid treatment apparatus cleaned by the method of the present invention is a vertical tube wet oxidation treatment apparatus in which an aqueous slurry of organic materials is oxidized in a tube which extends deep into the surface of the earth. Water rinses are performed between the steps of circulating the aqueous base solution, circulating the aqueous acid solution, and operating the fluid treatment apparatus. The water used for separating the sequential steps is preferably buffered water. The aqueous acid solution is preferably a mineral acid and most preferably nitric acid. The aqueous base solution is preferably potassium hydroxide or sodium hydroxide. The method also contemplates a sectional wash of the apparatus by directing a base or acid solution partially into the apparatus.

Heterogeneous Photocatalysis for Water Purification: Prospects and Problems

Abstract: Heterogeneous photocatalysis has demonstrated the complete wet oxidation (mineralization) of a number of common contaminants of water supplies, especially halogenated alkanes, alkenes, and aromatics. We review these recent results, including influence of reactant concentration, product inhibition, intermediate formation and disappearance, synthetic vs. solar illumination, and kinetic rate forms, and discuss prospects and problems for future essays.

Extraction of carbon‐14 from biological samples by wet oxidation

Abstract: An improved method is described for the extraction of 14C from biological samples, based on the wet oxidation techniques of Snyder and Trofymow6. Evolved 14CO2 is trapped in a 2M NaOH solution, and subsequently mixed in a scintillation cocktail for s counting. Recovery of 14C is consistent between batches, with an average recovery of 97.2% over fifteen standards. The technique described does not involve large capital expenditure and is relatively rapid.

Process for the destruction of noxious gases with ozone

Abstract: An improved process for the wet oxidation of malodorous gases obtained from sewage sludge drying operations is provided. Organic-enriched water having an oxygen demand of at least 5 mg per liter is utilized for the process.

Method and device for treating radioactive organic waste

Abstract: PROBLEM TO BE SOLVED: To provide a method which can prevent intermediate products from entering a condensate in an oxidative decomposition reaction made as a result of a process and can reuse or release the condensate without the necessity of a secondary treatment when an organic substance that coexists with radioactive nuclides is treated by wet oxidation using hydrogen peroxide and a device used for the implementation of the method. SOLUTION: In a method for treating radioactive organic wastes whose essential process is that they are oxidatively decomposed by reacting hydrogen peroxide on the radioactive organic wastes under the existence of iron ions and (or) copper ions in an aqueous medium, a mixture of steam and an intermediate product containing at least one of low-molecular-weight organic acid, amines, ammonia, a cyanogen compound and carbon hydride generated as a result of the oxidative decomposition reaction is taken out from an oxidation reaction tank 2 and is heated to raise the temperature and then the mixture is guided to a catalyst combustion device 4 equipped with an oxidative catalyst. In the device 4, oxygen is supplied to oxidatively decompose the intermediate product secondarily and then it is cooled in a condenser 5 to obtain a condensate that does not contain TOC (organic carbon content) materially and a harmless and non-odorous exhaust gas.

Supercritical waste oxidation of aqueous wastes

Abstract: For aqueous wastes containing 1 to 20 wt% organics, supercritical water oxidation is less costly than controlled incineration or activated carbon treatment and far more efficient than wet oxidation. Above the critical temperature (374 C) and pressure (218 atm) of water, organic materials and gases are completely miscible with water. In supercritical water oxidation, organics, air and water are brought together in a mixture at 250 atm and temperatures above 400 C. Organic oxidation is initiated spontaneously at these conditions. The heat of combustion is released within the fluid and results in a rise in temperature 600 to 650 C. Under these conditions, organics are destroyed rapidly with efficiencies in excess of 99.999%. Heteroatoms are oxidized to acids, which can be precipitated out as salts by adding a base to the feed. Examples are given for process configurations to treat aqueous wastes with 10 and 2 wt% organics.

High thermal flux density wet oxidation steam generator

Abstract: A wet air oxidation process for oxidizing organic matter dispersed in a liquid fuel stream at controlled high temperatures and pressures is capable of treating concentrations of organic matter in the feed stream far in excess of concentrations of organic matter treated in the normal type of wet air oxidation process. The improvement in the process is in the provision of a vapor phase effluent from the reactor system which is considerably greater than normal due to the introduction of high volumes of the oxidizing gas. This provides for increased concentrations of organic matter in the feed stream; however, resulting in the generation of excess energy within the reactor system which cannot be removed in the vapor and liquid phase effluents from the reactor system. The process is adapted to recover this excess energy from the reactor system to permit the reactor system to continue operating within the controlled high temperatures and high pressures, yet well outside of the normal physical-chemical equilibrium operating conditions for the reactor system.

Wet oxidation decomposition of graphite for determination of impurity elements

Abstract: 黒鉛を乾式法で酸化分解した残分(灰分)から不純物元素を定量する従来法は灰化過程で汚染や損失を招くとの見地から,湿式酸化分解法を開発した.黒鉛粉末1gは,200℃に加熱した過塩素酸中の過ヨウ素酸(0.5g)により3時間で分解する.分解後,ヨウ素及び過塩素酸を除き,不純物元素を定量する.この方法は発光分光分析用標準試料の表示値を決める参照法であるが,試作標準試料中の6元素の定量結果を,塩酸-硝酸(1+1)浸出法(回収率95%)の結果と比較して評価した.又, Spex製のG-standardsの9元素を定量した.

The wet oxidation treatment of wastewater from SOx removal facilities

Abstract: The wet oxidation of sodium dithionate was carried out at an elevated temperature between 100 and 300 °C. The decomposition of the dithionate solution proceeded rapidly at 150–170 °C and (approximately) a complete decomposition occurred at temperatures greater than 200 °C within 30 min. The removed percentage of the dithionate under a large excess of air was independent of the concentration. The addition of iron(II) sulfate and hydrogen peroxide accelerated the decomposition. Wet oxidation was effective for the disposal of wastewater containing dithionates.

Redox catalyst for wet oxidation of sulfide and wet oxidation method

Abstract: PURPOSE:To obtain a redox catalyst for wet oxidation of sulfide having extremely stable and high capacity, in a wet oxidative desulfurization method for removing hydrogen sulfide from gas containing hydrogen sulfide, by containing specific naphthohydroquinone sulfonate as a main component. CONSTITUTION:A redox catalyst based on 3-hydroxy-1,4-naphthoquinone-2- sulfonic acid, a salt thereof or a reduced compound thereof or a tautomeric compound of each of these compounds is used in an aqueous alkali solution containing sulfide in a case of a TAKAHAX method in an amount of 10-5,000ppm, pref., 50-2,000ppm to peform desulfurization. At this time, 0.01-2,000ppm, pref., 100-1,200ppm (by wt. of the aqueous solution) of a com plex or chelate compound of a valency variable metal such as iron or vanadium is used as a promotor. When the promotor is used, this redox catalyst is extremely stable and shows high formed sulfur yield and the replenishment of the catalyst on the way of reaction becomes unnecessary.

Oil shale wet oxidation process

Abstract: An aqueous slurry of comminuted oil shale containing pyritic sulfur is contacted with an oxidizing gas under wet oxidation conditions to produce a product mixture containing treated oil shale solids, and a liquid portion. Hydrocarb=onaceous liquid is recovered from the product mixture.

Spectrophotometric determination of traces of sulfur in graphite after wet oxidation decomposition

Abstract: 黒鉛粉末を白煙発生過鹿素酸中過ヨウ素酸で酸化分解し,還元蒸留後,エチレンブルーとして硫黄を吸光光度定量する方法を開発した.黒鉛1gは3時間で分解し,2ppm以上の硫黄が定量できる.この方法を用い,4か国11銘柄の原子炉級黒鉛材を分析した結果,3～90ppmの硫黄が定量された.別に定量した金属不純物の偏析と比べると,硫黄は総じて均一に分布していると言える.本法を基準にして過塩素酸のみによる浸出を試みたところ,90%近い硫黄が回収された.

Identification of diffusing species during metal silicide oxidation by Rutherford backscattering spectrometry

Abstract: Rutherford backscattering spectra of wet oxidized WSi2 thin films on single crystal Si substrate may provide valuable information to identify the diffusing species during the WSi2 thin film oxidation. After wet oxidation, spikes were observed at the low energy side of the ion signals backscattered from the W atoms in the WSi2 layer, indicating that a rough WSi2/Si interface is obtained after oxidation. It is proposed that the oxidation proceeds partially by the transport of W atoms through the WSi2 layer into the Si substrate where they react with the Si atoms in the Si substrate to form WSi2. With the grain growth, the grown WSi2 protrude into the Si substrate and therefore a rough interface is observed. This is discussed by comparing the results obtained from a radioactive Si∗ tracer technique and results obtained from investigations on the TaSi2 thin film oxidation.

Catalytic processes for space station waste conversion

Abstract: Catalytic techniques for processing waste products onboard space vehicles were evaluated. The goal of the study was the conversion of waste to carbon, wash water, oxygen and nitrogen. However, the ultimate goal is conversion to plant nutrients and other materials useful in closure of an ecological life support system for extended planetary missions. The resulting process studied involves hydrolysis at 250 C and 600 psia to break down and compact cellulose material, distillation at 100 C to remove water, coking at 450 C and atmospheric pressure, and catalytic oxidation at 450 to 600 C and atmospheric pressure. Tests were conducted with a model waste to characterize the hydrolysis and coking processes. An oxidizer reactor was sized based on automotive catalytic conversion experience. Products obtained from the hydrolysis and coking steps included a solid residue, gases, water condensate streams, and a volatile coker oil. Based on the data obtained, sufficient component sizing was performed to make a preliminary comparison of the catalytic technique with oxidation for processing waste for a six-man spacecraft. Wet oxidation seems to be the preferred technique from the standpoint of both component simplicity and power consumption.

Wet carbonization of lump-size low-rank coals by a novel non-slurry approach: Progress report for the period February-April 1986

Abstract: Construction of the process research unit (PRU) was completed with the successful modification and shakedown testing of the high-pressure steam boiler. Following an initial shakedown test of the PRU, four wet carbonization tests were conducted: a test (86-PRU-1) to determine the wet carbonization characteristics of (-1+1/2 inch) North Dakota Indianhead lignite, a replicate test (86PRU-2) to determine reproducibility of data, a test (86PRU-3) to determine the effect of residence time, and a test (86PRU-4) to determine the effect of partial wet oxidation using air feed to the reactor. The PRU and ancillary equipment operated smoothly, and system temperature and pressure controls operated well. The operating conditions for the four tests were a residence time of 0.3 to 1.1 hours and a temperature of about 550F. Air was used in the fourth test as a means of providing a portion of the required process heat. Product solid, liquid, and gas samples were taken for analyses. Two successful tests were conducted in the free-fall devolatilization reactor with raw Texas lignite and Montana subbituminous coals. These tests were conducted at a temperature of 1300F and a pressure of 500 psig with a steam-hydrogen mixture (50 mole percent hydrogen). About 150 grams of coalmore » were fed during the 60-minute duration of the tests. The product solid, liquid, and gas samples from the tests are being analyzed. Anaerobic digestion tests continued with filtered product water from the batch wet carbonization unit and the PRU. The objective of these tests is to determine the preferred reactor configuration and operating conditions for producing methane from and reducing the chemical oxygen demand of the wet carbonization product water.« less

Method for preventing oxidization of product such as magnetite in wet-oxidization process

Abstract: PURPOSE:To produce a high-quality magnetite preventing the oxidation of the product, by cooling the reaction liquid to a temperature below a specific level after the detection of the comletion of the reaction. CONSTITUTION:In the continuous production of magnetite and ferrite by wet oxidation process, the oxidation reaction is carried out at 80-90 deg.C and 9-10pH. When the reaction product is maintained at the reaction temperature after the completion of the reaction, the gradual oxidation of the Fe(II) in the spinel takes place. Therefore, the reaction liquid is cooled to <=70 deg.C, preferably to 40-70 deg.C after the detection of the completion of the reaction.