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1.
H2S Reactive Absorption from Off‐Gas in a Spray Column: Insights from Experiments and Modeling
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H2S removal from an off‐gas stream was performed in a spray column by H2S reactive absorption into a NaOH solution. The individual and interactive effects of three independent operating variables on the percentage of absorbed H2S were investigated: the initial pH of the scrubbing solution, the initial scrubbing solution temperature, and the volumetric liquid‐to‐gas ratio. The optimum operating variables were determined by response surface methodology (RSM) attaining a percentage of absorbed H2S of 98.7 ± 0.2 %. Additionally, the process performance was modeled by an artificial neural network (ANN) to predict the percentage of absorbed H2S. The results showed that the experimental data agreed better with the ANN model than with the RSM results. 相似文献
2.
Ying‐Chien Chung Yu‐Yen Lin Ching‐Ping Tseng 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2004,79(6):570-577
The removal of high concentrations of H2S from waste gases containing mixtures of H2S and NH3 was studied using the pilot‐scale biofilter. Granular activated carbon (GAC), selected as support material in this study, demonstrated its high adsorption capacity for H2S and good gas distribution. Extensive tests to determine removal characteristics, removal efficiency, and removal capacity of high H2S levels and coexisting NH3 in the system were performed. In seeking the appropriate operating conditions, the response surface methodology (RSM) was employed. H2S removal capacities were evaluated by the inoculated bacteria (biological conversion) and BDST (Bed Depth Service Time) methods (physical adsorption). An average 98% removal efficiency for 0.083–0.167 mg dm?3 of H2S and 0.004–0.021 mg dm?3 of NH3 gases was achieved during the operational period because of rapid physical adsorption by GAC and subsequently an effective biological regeneration of GAC by inoculated Pseudomonas putida CH11 and Arthrobacter oxydans CH8. The results showed that H2S removal efficiency for the system was not affected by inlet NH3 concentrations. In addition, no acidification was observed in the BAC biofilter. High buffer capacity and low moisture demand were also advantages of this system. The maximal inlet loading and critical loading for the system were 18.9 and 7.7 g‐H2S m?3 h?1, respectively. The results of this study could be used as a guide for the further design and operation of industrial‐scale systems. Copyright © 2004 Society of Chemical Industry 相似文献
3.
The absorption of gas pollutants including CO2, CO, NO, NO2, SO2, and H2S from the exhaust of a paint recuperative oxidizer into NaOH solution has been studied using an industrial scale dynamic scrubber. Experimental results show the influence of the absorbent concentration on the pollutant removal efficiency. The best removal efficiencies of CO2, CO, NO, NO2, SO2, and H2S were 79, 80, 80, 100, 75 and 88 %, respectively, with 2 % NaOH as the absorbent. A comparison of these results with previous studies shows that the liquid‐to‐gas flow rate ratio (FL/FG) in this dynamic scrubber is much smaller than for traditional NaOH scrubbers and spray dryers. 相似文献
4.
Pierre‐Franois Biard Annabelle Couvert Christophe Renner Jean‐Pierre Levasseur 《加拿大化工杂志》2010,88(4):682-687
Hydrogen sulphide removal in a waste water treatment plant at semi‐industrial scale in a compact wet scrubber has been investigated. The gas residence time in the scrubber was reduced to 30 ms using a NaOCl caustic scrubbing solution. The contactor is composed of a wire mesh packing structure where liquid and gas flow co‐currently at high velocity (>12 m s−1). H2S removal percentages higher than 95% could be achieved whereas a moderate pressure drop was measured (<4000 Pa). Both the hydrodynamic and chemical conditions can influence the efficiency of the process. Correlations were developed to predict both the pressure drop and the H2S removal efficiency at given operating conditions. 相似文献
5.
For selective removal of H2S from much larger quantities of CO2 under pressure, an industrial prototype spray column has been constructed. Sodium hydroxide solution was atomized by a pressure nozzle of special design and entered the scrubber as fine spray to contact the sour gases.
Several operating variables were examined in order to indicate optimal operating conditions for maximum selectivity of H2S over CO2. Fine mist and short contact time favor this selective absorption process. An optimum inlet reactant concentration was found dependent upon the H2S content relative to CO2 in the inlet sour gas mixture. A special nozzle/shield configuration to avoid contact of sour gas with highly turbulent liquid during droplet formation significantly improved the selectivity. 相似文献
6.
Yaomin Jin María C Veiga Christian Kennes 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(9):998-1004
The removal of hydrogen sulfide (H2S) from airstreams was studied in a biotrickling filter (BTF) packed with plastic Pall rings operating with counter‐current flows of the air and liquid streams. Experiments were performed at different inlet H2S concentrations, air and/or liquid volumetric flow rates, and sulfate concentrations in the recirculating liquid to check their effect on the performance of the BTF. Conversion of H2S never dropped below 80% at the highest concentration and reached 100% at low concentrations. A maximum removal rate of 22.5 g H2S m?3 reactor h?1 was observed with 100% removal efficiency. The shortest empty bed retention time studied at which complete H2S removal was observed was around 11 s. Conversion of H2S was found to slightly increase as the liquid flow rate decreased and as the air flow rate increased. Copyright © 2005 Society of Chemical Industry 相似文献
7.
J. S. Ahari K. Forsat M. H. Djenab K. Mohammadbigy M. Vahidi Z. Shafiei 《化学工程与技术》2008,31(10):1481-1486
In the present study, a simple model was used to predict the removal efficiency of a venturi scrubber for H2S absorption into a ferric chelate solution. From momentum and mass balances in the scrubber, a set of first‐order, nonlinear ordinary differential equations relating predominantly the liquid velocity with the H2S concentration in the liquid along the axial direction in the scrubber were formulated. These relationships were numerically solved to give performance profiles. The validity of the model was examined by comparing the results of the model with experimental data from the working laboratory scale. The results predicted from the model are in good agreement with the experimental data obtained in different sizes of the venturi scrubber and operating variables. 相似文献
8.
M. J. Azarhoosh H. Ale Ebrahim S. H. Pourtarah 《Chemical Engineering Communications》2016,203(1):53-63
Conventional synthesis gas production plants consist of a natural gas steam reforming to CO + 3H2 on Ni catalysts in a furnace. An alternative method for highly endothermic steam reforming is auto-thermal reforming. In this work, synthesis gas production by auto-thermal reforming was simulated based on a heterogeneous and one-dimensional model in two cases. The first case was the auto-thermal reformer of Dias and Assaf's study. The present work was validated by the reported experimental results. The second case was the fixed-bed catalytic auto-thermal reactor operated at high pressure, which was suitable for methanol production and Fischer–Tropsch reactions (baseline case). Then, the effect of operating variables on the system behavior was studied. Finally, Pareto-optimal solutions were determined by non-dominated sorting genetic algorithm II. The objectives included obtaining a H2/CO ratio of 2 in the produced synthesis gas and the maximum methane conversion. The adjustable parameters were the feed temperature, mass flux, and O2/CH4 and H2O/CH4 ratios in the feed. 相似文献
9.
Deivid Jonathan Souza Barros Emanuel Souza Barros 《Chemical Engineering Communications》2018,205(8):1050-1059
A large set of results of concentration of hydrogen sulfide in the feed and bottom product streams of a sour water stripper found in a typical oil refinery was experimentally obtained. The readings of H2S concentrations were at several different operating conditions in terms of the main process variables that classically have significant effects on the efficiency of H2S removal (E). In particular, the considered factors were the mass flow rate, and temperature of sour water fed into the stripper, the mass flow rate of external steam injected into the reboiler, the difference between the temperature of the product stream leaving and entering the reboiler, and the difference of pressure at the two ends of the tower. Three different soft-sensor models were suggested to describe the observed variation in E from 63 to 97%, namely, an equilibrium, statistical and an artificial neural network model. The best of them was the neural network one with three input variables, four neurons in the one-hidden layer, and a hyperbolic tangent function for both the output and one-hidden layers. The mean absolute relative deviation between measured and calculated E by involving this model was only approximately 2.5% with negligible tendency for the residuals. It confirms the reliability of this approach as a tool to inferential estimation of the efficiency of removal of H2S from the sour water by stripping. 相似文献
10.
A direct H2S fueled SOFC model is developed based on Ni‐YSZ/YSZ/YSZ‐LSM button cell test stand. The model considers the detailed reforming chemical processes of H2S and multi‐physics transport processes in the fuel cell and fuel supply tubes. The model is validated using experimental data. Extensive simulations are performed to study the complicated interactions between multi‐physics transport processes and chemical/electrochemical reactions. The results elucidate the fundamental mechanisms of direct H2S fueled SOFCs. It is found that suitably increasing the H2O content in the supplied H2S fuel can improve SOFC electrochemical performance; high operating temperature may facilitate the reforming of H2S and improve the electrochemical performance. The sulfur poisoning effect may be mitigated by increasing the H2O content in the fuel, increasing the operating temperature, decreasing the flow rate, and/or making the cell work at low voltage (or high current) conditions. 相似文献
11.
Removal of H2S from a steam-hydrogasifier product gas was studied at 636 K and 1 atm using a commercially available zinc oxide sorbent in a packed-bed reactor. A mixture gas containing 22% CH4, 18.7% H2, 8.8% CO and 5.5% CO2 (non-steam components subtotaling to 55%) balanced with steam was used to simulate the steam-hydrogasifier product gas. Sorbent particles of 150–250 μm size were used to eliminate the effect of intraparticle mass transfer limitation. Experiments were conducted to monitor H2S breakthrough of reactor effluent stream for operation parameters such as space velocity and inlet H2S concentration. With space velocity varied from 6000 to 8000 to 12,000 h?1 for inlet H2S concentration in the range of 100–800 ppmv, sulfur capture capacity of the sorbent (Scap) for 2 ppmv H2S breakthrough did not change notably, indicating that, for each inlet H2S concentration tested, sorbent utilization for sulfur removal was not affected by the space velocity. Meanwhile, for each space velocity tested, Scap increased monotonically as the inlet H2S concentration increased from 100 to 500 to 800 ppmv, which is opposite to the result observed for the mixture gas devoid of CH4, H2, CO and CO2. As the overall content of these non-steam components of the simulation gas was halved for each inlet H2S concentration tested at 8000 h?1 space velocity, Scap for non-steam gas components of 27.5% content corresponded approximately to the median value of those for the non-steam gas components of 55% and 0% content, suggestive of linear dependency of Scap upon the content of the non-steam components for the inlet H2S concentration tested. 相似文献
12.
Experimental Study and Mathematical Modeling of NO Removal Using the UV/H2O2 Advanced Oxidation Process
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An experimental study on NO removal via UV/H2O2 process was conducted in a semi‐continuous bubble‐column reactor and the effect of some operation parameters including NO initial concentration and gas flow rates on removal efficiency was investigated. Applying UV light increased the efficiency significantly. The steady‐state removal efficiency was found to be higher at the lower gas flow rates. The bubble size as an important factor in mass transfer calculations and modeling procedure was determined at different gas flow rates using bubble photographs and image processing technique. In the ranges of flow rates studied here, the gas flow rate had no significant effect on the bubble diameter. A mathematical model was developed to describe the NO removal process. The model predictions were compared with existing experimental data, confirming a good agreement of the data. 相似文献
13.
Wet scrubbers are gaining importance over other devices for particulate collection with the increasing stringency of pollution regulations. The scrubbing of particulates (soot and fly‐ash) in a spray tower with a two‐phase critical flow atomizer using water is reported in this article. The atomizer is capable of generating droplets with a high degree of spray uniformity. Preliminary studies reveal that the atomizer deployed in the present investigation is energetically more favorable than existing atomizers. With this atomizer, the scrubbing performances of a model spray tower are determined experimentally in terms of different operating variables. Various physical interactions with the exception of electrostatic effects are found to significantly influence the removal efficiency. The removal efficiency is found to increase with the inlet particle loading, gas flow rate and liquid to gas flow rate ratio. Experiments reveal that the present system collects finer (soot) particles (with a Sauter Mean Diameter (SMD) of 1.43 μm) more efficiently than the relatively coarse (fly‐ash) particles (SMD of 6.38 μm) under similar experimental conditions. Further investigation reveals that almost 100 % removal efficiency (zero penetration) of both soot and fly‐ash particles can be attained at a much lower QL/QG ratio of 3 m3/1000 actual cubic meters (ACM) than for the existing systems. A unique correlation is developed for predicting the performance of the spray tower in terms of various pertinent variables of the system. The predicted values agree very well with the experimental values (± 10 % deviation). A comparison of the performance of the present system with the existing systems indicates that the spray tower developed is techno‐enviro‐economically more favorable than existing systems. 相似文献
14.
Hyun-Hee Park Chun-Won Lim Hang-Dai Jo Won-Kil Choi Hyung-Keun Lee 《Korean Journal of Chemical Engineering》2007,24(4):693-697
In this study, removal of SO2 from gas stream was carried out by using microporous polyvinylidene fluoride (PVDF) asymmetric hollow fiber membrane modules
as gas-liquid contactor. The asymmetric hollow fiber membranes used in this study were prepared polyvinylidene fluoride by
a wet phase inversion method. Water was used as an internal coagulant and external coagulation bath for all spinning runs.
An aqueous solution containing 0.02 M NaOH was used as the absorbent. This study attempts to assess the influence of PEG additive,
absorbent flow rate, SO2 concentration, gas flow rate and gas flow direction on the SO2 removal efficiency and overall mass transfer coefficient. The effect of liquid flow rate on SO2 removal efficiency shows that at very low liquid flow rate, the NaOH available at the membrane surface for reacting with
SO2 is limited due to the liquid phase resistance. As liquid flow rate is above the minimum flow rate which overcomes the liquid
phase resistance, the SO2 absorption rate is controlled by resistance in the gas phase and the membrane. The SO2 absorption rate with inlet SO2 concentration was sharply increased by using hollow fiber membranes compared to a conventional wetted wall column because
the former has higher gas liquid contacting area than the latter. The mass transfer coefficient is independent of pressure.
When the gas mixture was fed in the shell side, the removal efficiency of SO2 declined because of channeling problems on the shell side. Also, the addition of PEG in polymer dopes increased SO2 removal efficiency.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
15.
Dali Kong Shuai Wang Kun Luo Jianren Fan 《American Institute of Chemical Engineers》2023,69(8):e18096
Biomass gasification combined with CO2 absorption-enhanced reforming (AER) in a bubbling fluidized bed (BFB) reactor is numerically studied via the multiphase particle-in-cell (MP-PIC) method featuring thermochemical and polydispersity sub-models. A novel bubble detection algorithm is proposed for efficiently characterizing bubble morphology. The effects of several crucial operating parameters on the microscale particle behaviors, mesoscale bubble dynamics, and macroscale reactor performance of the AER gasification process are analyzed. Compared with conventional gasification, AER gasification reduces the CO2 concentration by 33.58% but elevates the H2 concentration by 32.13%. Higher operating temperature and steam-to-biomass (S/B) ratio promote H2 generation but deteriorate gasification performance. A lower operating pressure improves gas–solid contact efficiency and gasification performance as the increased operating pressure inhibits bubble dynamics and particle kinematics. Compared with pure sand as bed material, the mixed bed material (CaO:sand = 1:1) significantly improves gasification performance by enhancing H2 generation and CO2 removal. 相似文献
16.
Fabric filters are involved in most semi-dry flue gas desulfurization process and represent ability of SO2 removal. SO2 removal efficiency in fabric filter after a semi-dry scrubber is investigated. Experimental results showed that SO2 inlet concentration has little effect on SO2 removal efficiency, SO2 removal efficiency increases as flue gas inlet temperature increases and relative humidity affects SO2 removal efficiency significantly. The kinetic model based on shrinking core theory has been presented. It is found that, in the beginning, when calcium hydroxide conversion ratio is less than 0.3, SO2 removal process is mainly controlled by chemical reaction (Model-2); and when calcium hydroxide conversion ratio is greater than 0.3, SO2 diffusion through product layer is rate limiting (Model-3). The experimental results in fabric filter are successfully correlated by Model-3. 相似文献
17.
Tailor‐made polyvinylidene fluoride (PVDF) asymmetric hollow fibre membranes are employed for the removal of soluble gases, such as H2S or SO2, from waste gas streams. This study focuses on techniques of fabricating and characterizing the PVDF asymmetric hollow fibre membrane used as a stable interface for absorption of H2S or SO2 using an alkaline solution. The effects of operating conditions and the morphological structures of the membranes on the membrane's coefficient, k̄AM are examined. Capabilities of the hollow fibre membranes developed for the removal of H2S and SO2 from waste gas streams are evaluated. 相似文献
18.
K. Chandrasekara Pillai T. Raju Sang Joon Chung Il‐Shik Moon 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(3):447-453
BACKGROUND: Hydrogen sulfide (H2S) from industrial activities and anaerobic manure decomposition in commercial livestock animal operations is an offensive malodorous and toxic gas even in small concentrations, causing serious discomfort and health and social problems. The objective of this study was to employ for the first time a novel, attractive, low cost, environmentally benign mediated electrochemical oxidation (MEO) process with Ce(IV) as the redox catalyst for H2S gas removal from an H2S–air feed mixture. RESULTS: The influence of liquid flow rate (QL) from 2–4 L min?1, gas flow rate (QG) from 30–70 L min?1, H2S concentration in the H2S–air feed mixture from 5–15 ppm, and Ce(III) pre‐mediator concentration in the electrochemical cell from 0.1–1 mol L?1 on H2S removal efficiency were investigated. Both liquid and gas flow rates influenced the removal efficiencies, but in opposite directions. Nearly 98% H2S removal was achieved when the concentration of Ce(IV) mediator ion in the flowing scrubbing liquid reached 0.08 mol L?1. CONCLUSIONS: The new MEO method proved promising for H2S removal, achieving high removal efficiency. Integration of the electrochemical cell with the scrubber set‐up ensured continuous regeneration of the mediator and its repeated reuse for H2S removal, avoiding use of additional chemicals. Since the process works at room temperature and atmospheric pressure utilizing conventional transition metal oxide electrodes more commonly used in industrial applications, it is also safe and economical. Copyright © 2008 Society of Chemical Industry 相似文献
19.
Amir RahimiMohammad Sadegh Hatamipour Mohsen GholamiMohammad Reza Haghnegahdar 《Chemical Engineering Research and Design》2011,89(6):777-784
A mathematical model is developed for investigation of SO2 removal in a powder particle spouted bed (PPSB) for non-isothermal operating condition. For this aim, the stream-tube model which was already validated for such systems is applied for hydrodynamics of solid and gas phases, and then by using the conservation laws of mass and energy, the governing equations for gas and solid phases are derived and solved numerically. The published experimental data in the literature are used to validate the accuracy of the proposed model. The results show that the model is capable of predicting the behaviour of this system properly. Also the optimum performance of this system is investigated by studying the effects of different parameters such as bed height, molar ratio of sorbent to acid gas (Ca/S) and inlet concentration of SO2. 相似文献
20.
Hyun-Min Shim Su-Yong Jung Hong Yue Wang Hyung-Taek Kim 《Korean Journal of Chemical Engineering》2009,26(2):324-331
Gasification technology, which converts fossil fuels into either combustible gas or synthesis gas (syngas) for subsequent
utilization, offers the potential of both clean power and chemicals. Especially, IGCC is recognized as next power generation
technology which can replace conventional coal power plants in the near future. It produces not only power but also chemical
energy sources such as H2, DME and other chemicals with simultaneous reduction of CO2. This study is focused on the determination of operating conditions for a 300 MW scale IGCC plant with various feedstocks
through ASPEN plus simulator. The input materials of gasification are chosen as 4 representative cases of pulverized dry coal
(Illinois#6), coal water slurry, bunker-C and naphtha. The gasifier model reflects on the reactivity among the components
of syngas in the gasification process through the comparison of syngas composition from a real gasifier. For evaluating the
performance of a gasification plant from developed models, simulation results were compared with a real commercial plant through
approximation of relative error between real operating data and simulation results. The results were then checked for operating
characteristics of each unit process such as gasification, ash removal, acid gas (CO2, H2S) removal and power islands. To evaluate the performance of the developed model, evaluated parameters are chosen as cold
gas efficiency and carbon conversion for the gasifier, power output and efficiency of combined cycle. According to simulation
results, pulverized dry coal which has 40.93% of plant net efficiency has relatively superiority over the other cases such
as 33.45% of coal water slurry, 35.43% of bunker-C and 30.81% of naphtha for generating power in the range of equivalent 300
MW. 相似文献