Flow Rate Of Gas Stream Research Articles

Removal of NOx using ozone injection and subsequent absorption in water

In nuclear reprocessing plant reduction of the nitric acid from the high level radioactive liquid waste is accomplished by the addition of formaldehyde. A significant amount NOx is generated during this conventional acid killing process. In this case NO oxidation followed by NO2 absorption is considered as a suitable option for NOx eradication, which also produces reusable nitric acid. Hence, investigations to explore the NO oxidation in the presence of O3 have been carried out for a relatively large system where the total flow rate of gas stream was 800 SLPM (52.4 m3/ h at 25 °C) and the concentration of NO was 480 ppm. It was observed that the concentration of NO decreases with the increase in the concentration of O3 added. A mathematical model has also been developed to predict the concentration of the gaseous components at the exit of the ozonization chamber. Model calculation shows that the reaction between NO and O3 is completed within fraction of a second. Further investigation on the absorption of NO2 in water was carried out by passing the exhaust gas through a scrubber. The absorption of NO2 in water leads to the formation of NO. An attempt has been made to enhance the performance of the water scrubber by injecting ozone into the gas phase during NO2 absorption. The model prediction reveals that N2O5 is the ultimate fate of the NO2 in the presence of O3. The evolution of N2O5 can be considered as two-step process. Reaction between NO2 and O3 is slow and the rate controlling step. On the contrary NO3 reacts quite rapidly with remaining NO2 and produces N2O5.

The effects of continuous- and stop-flow gas streams on adsorptive removal of benzene vapor using type – II covalent organic polymers

Various materials have been investigated for the adsorptive removal of volatile organic compounds (VOCs, such as benzene). However, most materials proposed for the adsorptive removal of gaseous benzene (and other VOCs) perform relatively poorly (e.g., an impractically low-service 10% breakthrough volume [BTV10] at < 100 ppm). The adsorbent uptake rate (mg g−1 min−1) can also be assessed as a function of the gas-stream flow rate (or space velocity). The main aim of this study is to explore the effect of two different gas-stream supply modes — stopped flow (at a fixed stream flow rate of 330 mL atm min−1) vs. continuous flow (a variable-stream flow rate of 100, 200, or 330 mL atm min−1) on the adsorption metrics of gaseous benzene on 5 mg of two types of – II covalent organic polymers (COPs: CBAP-1 [DETA], CD; or CBAP-1 [EDA], CE). The sorbent tube outlet stream was sampled by two respective sampling methods (i.e., a large-volume injector [LVI] for stopped flow vs. syringe injection [SI] for continuous flow) for sample quantitation by gas chromatography flame-ionization detection (GC-FID). The observed BTV10 values in the two sampling modes were similar when tested using 10 ppm benzene, irrespective of sorbents: 56/60 (CD) vs. 620/624 L atm g−1 (CE). BTV10 values increased systematically with decreasing stream-flow rates to reflect the importance of space velocity in adsorptive removal of benzene. The overall assessment of adsorption performance between stopped flow (LVI) and continuous flow (SI) revealed that the performance of the adsorbent is independent of flow mode (e.g., when performance was compared at flow rate of 330 mL min−1).

DETERMINATION OF THE GAS STREAM FLOW AT CONDUCTING HYDRODYNAMIC INVESTIGATION OF WELLS. PART 3

The paper presents a method for calculating the gas stream flow rate during well tests of gas and gas condensate wells using a diaphragm gauge of critical flow. The above method compensates the disadvantages of the described in the scientific and technical literature gas stream flow rate calculation methods during its flow through the diaphragm in the critical regime. For the proposed method are presented the testing results on gas and gas condensate wells of the north of the Tyumen region.

Ozone Effect on Fungi Proliferation and Genera Susceptibility of Treated Stored Dry Paddy Rice (Oryza sativa L.)

AbstractThis work reports the ozone (O3) gas effects on stored dry paddy rice (Oryza sativa L.) mycoflora (fungi reduction/genera susceptibility/yeast) and humidity microorganism proliferation factors (moisture content [mc]/water activity [aw]. From the three O3 concentrations applied (10, 20 and 40 mg/L – groups I, II and III, respectively) on silos stored rice (n = 10), it was observed a rather high reduction on the total fungi load especially in group III from an initial count of 3.0 × 105 down to 1.4 × 102 cfu/mL. Regarding the samples naturally contaminated fungi genera isolated, they were Aspergillus, Penicillium, Acremonium, Alternaria and Aureobasidium (a yeast‐like fungi), as well as yeast, which were reduced after O3 treatment. Despite this, some strain gas susceptibility differences were observed as follows (decreasing order): Acremonium &gt; Alternaria &gt; Aureobasidium &gt; Aspergillus &gt; Penicillium. As expected, mc and aw reduced after gas treatment, which was proportional to the time of exposure and O3 gas stream flow rate applied on the rice stored samples. O3 treatment showed to be an effective green alternative tool to reduce paddy stored rice contamination and keep safety during storage.Practical ApplicationsThe O3 gas treatment showed to be an effective green alternative tool to avoid paddy stored rice fungi growth, especially toxigenic species responsible for mycotoxin formation in the paddy rice, and to keep safety during storage. Excess ozone is decomposed rapidly to O2, thus no food residue is left.

Localization of CsI Radioaerosols from the gas phase using various filtration elements

The behavior of 137Cs131I radioaerosols, yielded by CsI evaporation from a Pt healer into argon or air, during their localization with aqueous solutions and various filtration materials [filters based on Petryanov fabric (from here on, Petryanov filter), “while band” paper filter, and TRUMEM metallic membrane filter] was studied. The degree of localization of 137Cs131I radioaerosols was examined in relation to the amount of sublimed 137Cs131I, the number of bubblers in the system, the size of the nozzle in the bubbling system, and the gas stream flow rate. The efficiency of localization of 137Cs131I radioaerosols with a 10-layer stack of Petryanov filters from the gas stream with and without bubbling system was estimated. It was found that, at the stream velocity of 2–3 cm s−1, a 10-layer stack of Petryanov filters with the total thickness of 3 cm takes up ca. 97% of total 137Cs131I sublimed from the Pt heater. It was shown that the bubbling system does not affect the efficiency of localization of 137Cs131I radioaerosols by Petryanov filters but only favors decrease of the aerosol load on these filters. Electron-microscopic examination of the particle-size distribution of the CsI aerosols penetrating through aqueous solutions was carried out, and various filtration materials (Petryanov filter and “white band” paper filter) were tested.

Study of adsorption deposition of xenon in an industrial unit for processing ASU tail streams

Results are presented for studying the deposition stage in an industrial unit of the adsorption type intended for extracting xenon from “dirty oxygen” taken from air separation units (ASU). Calculation relationships are proved under industrial conditions that were obtained as a result of studies in a laboratory unit. The following parameters of low-temperature deposition of xenon from a stream of so-called dirty oxygen are varied: adsorption temperature, linear gas stream flow rate in an adsorber and xenon content in the gas mixture.

Capturing Volatile Nitrosamines in Gas Stream by Zeolites: Why and How

For potential application of zeolite in environmental protection, the instantaneous adsorption of volatile nitrosamines in gas stream by zeolites was studied by a gas chromatography technique. Three volatile nitrosamines, N-nitrosodimethylamine, N-nitrosopyrrolidine, and N-nitrosohexamethyleneimine, were chosen as adsorbates. The influence of adsorption temperature, flow rate of gas stream, and the mixed nitrosamines on the adsorption of zeolites was examined. Furthermore, the adsorption isotherms of nitrosamines were fitted with the Freundlich equation for the first time. Zeolite NaY showed the highest capacity to capture the nitrosamines in the gas stream containing sidestream smoke from cigarettes at ambient temperature, providing an efficient candidate for protection of environment and public health.

Aqueous Absorption and Oxidation of Nitric Oxide with Oxone for the Treatment of Tail Gases: Process Feasibility, Stoichiometry, Reaction Pathways, and Absorption Rate

The absorption−oxidation of nitrogen oxides (NOx) induced by aqueous solutions of potassium hydrogen peroxymonosulfate or oxone (2KHSO5·KHSO4·K2SO4) in the absence and presence of SO2 has been studied in a bubble column reactor operated in semicontinuous and continuous countercurrent flow modes. The influence of different process variables, such as temperature (22−55 °C), gas stream flow rate (or residence time), concentration of oxone, solution pH, feed concentrations of NO and SO2, and the presence of O2 and CO2 in the feed stream on the absorption−oxidation of NO were evaluated in the semibatch flow mode. The individual and simultaneous chemistry of NOx and SO2 removal by peroxomonosulfate (KHSO5) is discussed. The effects of simultaneous mass transfer and chemical reactions in the liquid phase were also investigated with a bubble column reactor operated in the continuous countercurrent flow mode using the theory of absorption accompanied by fast pseudo-mth-order reaction. The rate of reaction of NO wi...

Dynamic Adsorption of Organic Solvent Vapors onto a Packed Bed of Activated Carbon Cloth

The adsorption behavior of organic compound vapors onto a packed bed of activated carbon cloth (ACC) has been investigated. Three types of ACCs have been employed: KF1500, FT200-20, and E-ACC. The volatile organic compounds (VOCs) used in this study are acetone, dichloromethane, acrylonitrile, and n-hexane. The operating parameters studied are temperature of adsorber, weight of ACC, relative humidity of fluid, inlet concentration of VOCs, and total volumetric flow rate of gas stream. A simple theoretical model, originally introduced by Yoon and Nelson, has been utilized to simulate the breakthrough curve of VOC vapor on an adsorption column packed with activated carbon cloth. A modified model is proposed to predict the adsorption behavior of an adsorber at different temperatures.

Absorption of nitric oxide promoted by strong oxidizing agents: organic tertiary hydroperoxides in n-hexadecane

The selective removal of nitric oxide from gas streams was investigated using 3,6-dimethyl-3-octyl hydroperoxide, p-menthanyl hydroperoxide, pinanyl hydroperoxide, and cumenyl hydroperoxide in solutions of n-hexadecane (cetane). The influence of different variables such as temperature, gas stream flow rate (or residence time), and concentration of hydroperoxide compounds on rate of NO removal was evaluated. The NO reacted with the hydroperoxides to produce allyl nitrates. These are easily hydrolyzed with ammonium hydroxide to ammonium nitrate and the alcohol

Behavior of Small Particles from Process Gas Streams in Diffusion Furnaces

The deposition of small particles in the diffusion furnace environment was examined. A 6-ft-long and 6 1/4-in diameter quartz tube furnace was used. Particles ranging from 0.5 to 10 μm in diameter were generated and the deposition rate onto 5-in wafers in the furnace was measured as a function of gas stream flow rate, furnace temperature, and pressure. The measured deposition velocity ranged from 5×10−5 to 5×10−3 cm/s. The results of this study indicate that the deposition of particles decreases with increasing furnace tern perature. In addition, deposition increases as the wafer spacing increases and decreases as the wafers are placed further away from the entrance. Particles are found to deposit preferentially on the outer portion of the wafers. Owing to the flow pattern in the diffusion furnace, deposition of particulates is higher at the top of the wafer. The electrostatic charge effects were found to be insignificant.