H2S Removal Efficiency Research Articles

Study of aluminum corrosion in contact with biogas before and after purification on different carbons

The study of aluminium corrosion in contact with biogas before and after purification on different types of carbon aims to understand the impact of impurities present in biogas, in particular hydrogen sulphide (H₂S), on aluminium degradation. The study highlights the importance of biogas purification in minimising aluminium corrosion. Depending on the level of purification and the types of carbon used for filtering, it is possible to improve the durability of infrastructures in contact with biogas. This has direct implications for the maintenance and operating costs of facilities using biogas as an energy source. Hydrogen sulfide (H₂S) is a colorless, flammable and highly toxic gas characterized by an unpleasant odor. It is often present in industrial and natural environments, particularly in biogas. This gas is involved in the degradation of metals used in anaerobic digestion equipment, in the petrochemical industry, etc. The aim of this work is to study the performance of biochar and activated carbon prepared from corn cobs in removing H2S from biogas, and to evaluate the reduction of the corrosive effect of filtered biogas on metallic aluminum. The impregnation and carbonization method was used to prepare activated carbon from corn cobs, and the gravimetric method to study the corrosion rate of metal in biogas. The results indicate that the activated carbon prepared is microporous, has a good specific surface and a better adsorption capacity. Furthermore, the prepared activated carbon samples also showed good H2S removal efficiency in the biogas. The aluminum-induced protective power values in filtered biogas for biochar and activated carbon are 58 % and 82.22 % respectively. We plan to increase the contact time and experiment with other metals and carbons.

Enhanced H2S removal efficiency using CuO/Al2O3 catalyst impregnated with Ca(NO3)2: Influence of calcination temperature and mechanistic insights

A series of Ca(NO3)2-CuxO/Al2O3 catalysts with different calcination temperatures were designed to remove H2S effectively. Experimental and characterization results indicate that the calcination temperature can influence the catalyst's specific surface area, basic sites, and oxygen vacancies (VOs) concentration, thereby promoting its desulfurization performance. The Ca(NO3)2-CuxO/Al2O3 catalyst, calcined at 230 °C, exhibits an optimal surface structure. It demonstrates optimal H2S desulfurization performance at a temperature of 60 °C and relative humidity of 60 %, achieving a removal capacity of 486.67 mg/g. The VOs in CuxO (CuO and Cu2O) induce a unique catalytic of H2O, which generates hydroxy radicals (·OH) to oxidize the H2S anion to S. The introduction of Ca2+ provides basic sites to buffer pH, and NO3- with H+ removes H2S through cyclic oxidation, significantly enhancing the desulfurization performance of the Cu-based catalyst. The CaO-CuxO/Al2O3 catalyst, calcined at 700 °C, suffers from a deteriorated catalyst structure, leading to the rapid formation of desulfurization by-products due to the presence of CaO covering the catalyst surface. This diminishes the effectiveness of Cu, significantly impairing the catalyst's desulfurization performance (150.47 mg/g). Consequently, desulfurization mechanisms of Ca(NO3)2-CuxO/Al2O3 and CaO-CuxO/Al2O3 are proposed, offering effective strategies for the design and optimization of subsequent high-efficiency catalysts.

Reconfiguration of acid gas removal process matching the integration of coal chemical industry with green hydrogen

The focus of the acid gas removal process has shifted from decarbonization and desulfurization to desulfurization in the context of integrating coal chemical technology with green H2 without a water gas shift unit. The conventional Rectisol process, Selexol process, organic amine process, and sulfone-amine process have been reconfigured to form the R-Rectisol process, R-Selexol process, R-MDEA process, and R-Sulfolane-MDEA process to adapt to the shift of acid gas removal target. The removal efficiency of H2S and CO2, process energy consumption, and process cost are investigated to evaluate the technical and economic performance of the above four reconfigured acid gas removal processes. The results indicate that for the R-Recitsol process and R-Selexol process, both high pressure and low temperature increase the relative selectivity of H2S to CO2, thereby enhancing the selective removal of H2S. In contrast, for the R-MDEA process and R-Sulfolane-MDEA process, low pressure and low temperature improve the relative selectivity of H2S to CO2, thereby facilitating the selective removal of H2S. Under optimal operating conditions, the value of relative selectivity of H2S to CO2 of the R-Sulfolane-MDEA process is the largest, and the relative selectivity of H2S to CO2 of the R-Rectisol process, R-Selexol process and R-MDEA process are only 7.64 %, 12.85 %, and 68.40 % of the relative selectivity of H2S to CO2 of the R-Sulfolane-MDEA process, respectively. Compared to the other three reconfigured acid gas removal processes, the R-Sulfolane-MDEA process demonstrates superior advantages in both energy consumption and economic feasibility, provided that the H2S levels remain below 0.1 ppm in purified syngas. This study aims to enhance the decision-making process for gas purification methods in the coal chemical industry by considering integrated green H2 as an alternative to the water gas shift unit.

Modeling selective absorption of H2S from a gas mixture containing CO2 within rotating packed bed based on surface renewal theory

Compared to conventional packed beds (PBs), the rotating packed beds (RPBs) demonstrate superior selectivity for H2S. RPBs can selectively absorbing more than 99 % of H2S in CO2-rich gas mixtures, while the co-absorption rate of CO2 in RPBs is only 1/9 of that in PB columns. Therefore, RPBs have been well applied in the gas purification for natural gas, blast furnace gas, and refinery gas. While, modeling the selective reaction process in RPBs under conditions of rapid liquid film renewal remains challenging. Here, a diffusion–reaction mass transfer model based on surface renewal theory is established. The model elucidates the mechanism behind the selective absorption of H2S, and also demonstrate how RPBs enhance liquid film absorption. Experimental data collected from an RPB operating under actual conditions were used to validate the model. The model demonstrates high precision in predicting the removal efficiency of H2S and CO2.

Novel multineedle-to-cylinder plasma coupled with bimetallic catalysts for efficient removal of sulfides and ammonia in odor gases

Dielectric barrier discharge (DBD) plasma is a promising technology for treating odor gases. This study developed an innovative multineedle-to-cylinder (MC) configuration DBD plasma reactor and investigated its synergistic effect with bimetallic catalysts. The results demonstrated that MC-DBD plasma achieved complete elimination of ammonia and organic sulfides, while the removal efficiencies of inorganic H2S and CS2 reached 44.0 % and 53.0 % respectively. Compared with conventional plasma, the specific energy input (SEI) of MC-DBD was significantly reduced to 4.44 J/L. Furthermore, with the incorporation of Mn-Ce/ZSM-5 catalyst, optimal removal efficiencies of H2S and CS2 were significantly improved to 82.6 % and 90.7 %, and the SEI was reduced by 18 %. The electrical performance revealed that the low energy consumption was mainly attributed to stable fast-pulse micro-discharge channels and significantly enhanced inhomogeneous electric fields achieved by the filament discharge mode. Catalyst characterization (X-ray photoelectron spectroscopy and O2-temperature programming desorption) confirmed that surface catalytic reaction mainly follows the Mars-van Krevelen mechanism, where increased lattice oxygen content and the electron transfer between Mn and Ce play crucial roles in enhancing malodor degradation performance. This work proposes an efficient solution for degrading mixed malodors and provides an experimental and theoretical basis for optimizing plasma structure as well as researching treatment of mixed pollutants.

Hydrogen Sulfide Oxidizing Microbiome in Biogas-Stream Fed Biofilter in Palm Oil Factory

Hydrogen sulfide (H2S) is highly corrosive to electric generators, which is the main problem of biogas utilization. The industrial scale of the biofilter system relies on the performance of sulfide-oxidizing bacteria (SOB) via the activity of sulfur oxidation (soxABXYZ) and flavocytochrome sulfide dehydrogenase (fccAB) enzymes to reduce to a concentration below 100 ppm before using in industrial machinery. The main purpose of this research is to investigate the SOB community in full-scale H2S removal and their gene expression (fccAB and soxABXYZ) associated with H2S elimination efficiency. In this study, SOB communities were obtained from 2 sampling sites of the full-scale biofilter of palm oil factory (PPG), comprising starting sludge (PPG1) and recirculating sludge (PPG2). The abundance of SOB strains was examined by next-generation sequencing analysis (NGS) based on the 16S rRNA gene. The changes in the expression of genes involved in sulfur oxidation, namely soxABXYZ, and fccAB, between the 2 sampling sites were evaluated by using a comparative genomic hybridization (CGH) microarray. The results indicate that the high abundance of SOB genera that could play a vital role in biofilters belonged mainly to Sulfurovum, Paracoccus, Acidihalobacter, Acidithiobacillus, Thioalkalispira, Thiofaba, Caldisericum, Bacillus, were rapidly increased in the biofilter tank. Interestingly, expressions of soxAXYZ gene cluster at PPG2 were increased in Paracoccus pantotrophus J40 and Paracoccus alkenifer DSM 11593 for 1.1188 and 1.0518-fold, respectively, while in Acidihalobacter prosperus F5, the expression of fccAB genes was up to 1.3704 fold in comparison with PPG1. Increasing both relative abundance and gene expressions at PPG2 were correlated with 95% H2S removal efficiency. Hence, stabilization of the SOB microbiome is vital to H2S removal in industrial-scale biogas applications.

Diversity of Hydrogen Sulfide Oxidizers in Biogas-Stream Fed Bioscrubber in Seafood Factory

Corrosive and harmful hydrogen sulfide (H2S) are major obstacles to biogas utilization. Bioscrubber system is the one of the most popular tecnologies for removing H2S from biogas. Sulfur oxidizing bacteria (SOB) play an important role in controlling the efficiency and stability of bioscrubber systems through sulfur oxidation (soxABXYZ) and flavocytochrome sulfide dehydrogenase (fccAB) enzyme catalyses. The main purpose of this research is to analyse microbial diversity and gene expression pattern of SOBs related to H2S oxidation. In this study, SOB population were collected from the full-scale bioscrubber system of the seafood factory (TKF). The richness and diversity of SOB strains were analyzed using next-generation sequencing analysis (NGS) based on 16S rRNA gene. DNA microarray was used to examine the expression of soxABXYZ and fccAB genes involved in the H2S oxidation. A number of readable sequences indicate SOB diversity and richness that cover the entire population of bacteria in the TKF factory. The phylum proteobacteria was found covered up to 60% of total bacteria. Interestingly, the highest abundance genus of SOB coexisting in biocrubber to oxidize H2S in biogas was Pseudomonas, MWH-UniP1_aquatic, Smithella, Thioalkalimicrobium, Hydrogenophaga and Acinetobacter. Paracoccus sediminis, Pseudomonas stutzeri and Paracoccus denitrificans were found having the soxAXYZ and soxB gene expression level up to 0.2754-fold, 0.0808-fold and 0.3819-fold respectively. On the other hand, the expression of fccAB genes of P. denitrificans was increased up to 0.3819-fold. Altogether, the predominance of these species-strains was associated with the excellent H2S removal efficiency of 99.3% in the TKF factory.

Application of a generalized hybrid machine learning model for the prediction of H2S and VOCs removal in a compact trickle bed bioreactor (CTBB)

This study presents a generalized hybrid model for predicting H2S and VOCs removal efficiency using a machine learning model: K–NN (K - nearest neighbors) and RF (random forest). The approach adopted in this study enabled the (i) identification of odor removal efficiency (K) using a classification model, and (ii) prediction of K <100%, based on inlet concentration, time of day, pH and retention time. Global sensitivity analysis (GSA) was used to test the relationships between the inputs and outputs of the K-NN model. The results from classification model simulation showed high goodness of fit for the classification models to predict the removal of H2S and VOCs (SPEC = 0.94–0.99, SENS = 0.96–0.99). It was shown that the hybrid K-NN model applied for the “Klimzowiec” WWTP, including the pilot plant, can also be applied to the “Urbanowice” WWTP. The hybrid machine learning model enables the development of a universal system for monitoring the removal of H2S and VOCs from WWTP facilities.

Experimental study on removal of hydrogen sulfide gas by spray and bubble blowing: A comparative study

H2S (hydrogen sulfide) is widely concerned because of its strong odor and toxicity, which seriously affects the physical and mental health of surrounding residents. In this paper, bubble blowing and spray deodorization experimental systems for H2S gas generation were constructed, with plant-derived deodorant were employed as a deodorizing liquid. The influence factors of spray and bubble blowing deodorization experimental system for deodorization performance were explored. And the effects of spray deodorization method and bubble blowing deodorization method on H2S removal rate were compared. The results show a positive correlation between the removal rate of H2S and the inlet pressure in the spray deodorization system. As the inlet pressure increases, the removal efficiency of H2S exhibits a gain ranging from 22.36% to 23.56%. Within the bubble blowing deodorization system, H2S concentration decreases as the deodorization solution dosage increases. As the deodorizing solution dosage increases from 920 mL to 1800 mL, H2S concentration decreases from 0.46 mg·m−3 to 0 mg·m−3. Furthermore, the bubble blowing deodorization method outperforms the spray, resulting in a 14.60–29.09% increase in H2S removal rate. The bubble blowing deodorization method proposed in this study exhibits promising potential for application in the field of malodorous gas treatment.

Modeling and improving the scrubbing efficiency of an intensified ammonia process for coke oven gas purification

Coke oven gas (COG) is a valuable byproduct of coke production in the steel industry. Conventionally, undesired H2S and NH3 in COG are removed in separate columns in an ammonia process. In this work, an intensified ammonia process which removes both H2S and NH3 in a single column with multiple sections is studied. The intensified process occupies less space and is less expensive. A process model is built and validated using plant operating data. The underlying principal of scrubber operation is explained through the simulated concentration profile. The influences of important operating variables such as inlet COG flowrate, strong ammonia liquid flowrate, low ammonia liquid flowrate and concentrated NaOH solution flowrate are studied. It is shown that the H2S removal efficiency is sensitive to inlet COG flowrate, and that the flowrate of low ammonia liquid should be used as manipulate variable to control the outlet COG composition. Furthermore, it is found that to improve the H2S removal efficiency, the flowrate of concentrated NaOH solution should exceed a certain threshold. Otherwise the scrubbing liquid will be neutralized by CO2 in the COG, which will decrease the pH and alkalinity of the scrubbing liquid significantly.

Biodesulfurization of landfill biogas by a pilot-scale bioscrubber: Operational limits and microbial analysis.

Biogas serves as a crucial renewable energy vector to ensure a more sustainable energy future. However, the presence of hydrogen sulfide (H2S) limits its application in various sectors, emphasizing the importance of effective H2S removal techniques for maximizing its potential. In the present study, the limits of a pilot-scale bioscrubber for biogas desulfurization was study in a real scenario. An increase in the superficial liquid velocity resulted in significant improvements in the H2S removal efficiency, increasing from 76 ± 8% (elimination capacity of 6.2 ± 0.5 gS-H2S m−3 h−1) to 97.7 ± 0.5% (elimination capacity of 8 ± 1 gS-H2S m−3 h−1) as the superficial liquid velocity increased from 50 ± 3 m h−1 to 200 ± 8 m h−1. A USL of 161.4 ± 0.5 m h−1 was able to achieve outlet H2S concentrations as low as 3 ± 1 ppmv (H2S removal efficiency of 97 ± 1%) for 7 days. High superficial liquid velocity favoured the aerobic H2S oxidation reducing the nitrate demand. The maximum EC reached throughout the operation was 50.8 ± 0.6 gS-H2S m−3 h−1 (H2S removal efficiency of 96 ± 1%) and a sulfur production of 60%. Studies in batch flocculation experiments showed sulfur removal rates up to 97.6 ± 0.9% with a cationic flocculant dose of 75 mg L−1. Microbial analysis revealed that the predominant genus with sulfo-oxidant capacity during periods of low H2S inlet load was Thioalkalispira-sulfurivermis (61–69%), while in periods of higher H2S inlet load, family Arcobacteraceae was the most prevalent (11%).

Highly efficient capture and removal of H2S by multi-amine functionalized ionic liquids

With the increasing awareness of environmental protection, H2S removal in natural gas has attracted more attention. In this study, three multi-amino functionalized ionic liquids (MFILs) were prepared with a one-step reaction. The solubility of H2S was measured at temperatures of 298.2 K to 328.2 K. Among them, diethylenetriamine imidazole ([DETAH][Im]) presented the unprecedented H2S solubility of 7.82 mol/kg (1.34 mol/mol) at 298.2 K and 0.1 bar H2S partial pressure, surpassing all the reported absorbent under the experimental condition. The H2S removal ability was determined with the interference of CO2, and the highest H2S removal efficiency reached 99.32% during four-hour absorption. The mechanism was elucidated by NMR, FT-IR, and DFT calculation. Moreover, five consecutive absorption–desorption cycles were performed to evaluate the regeneration efficiency. These MFILs represent apparent viscosity and absorption performance superiority over previously reported absorbents. These MFILs are a class of promising absorbents for sweetening natural gas.

Simulation study of hydrogen sulfide removal in underground gas storage converted from the multilayered sour gas field

A simulation study was carried out to investigate the temporal evolution of H2S in the Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing gas field. Based on the rock and fluid properties of the Huangcaoxia gas field, a multilayered model was built. The upper layer Jia-2 contains a high concentration of H2S (27.2 g/m3), and the lower layer Jia-1 contains a low concentration of H2S (14.0 mg/m3). There is also a low-permeability interlayer between Jia-1 and Jia-2. The multi-component fluid characterizations for Jia-1 and Jia-2 were implemented separately using the Peng-Robinson equation of state in order to perform the compositional simulation. The H2S concentration gradually increased in a single cycle and peaked at the end of the production season. The peak H2S concentration in each cycle showed a decreasing trend when the recovery factor (RF) of the gas field was lower than 70%. When the RF was above 70%, the peak H2S concentration increased first and then decreased. A higher reservoir RF, a higher maximum working pressure, and a higher working gas ratio will lead to a higher H2S removal efficiency. Similar to developing multi-layered petroleum fields, the operation of multilayered gas storage can also be divided into multi-layer commingled operation and independent operation for different layers. When the two layers are combined to build the storage, the sweet gas produced from Jia-1 can spontaneously mix with the sour gas produced from Jia-2 within the wellbore, which can significantly reduce the overall H2S concentration in the wellstream. When the working gas volume is set constant, the allocation ratio between the two layers has little effect on the H2S removal. After nine cycles, the produced gas’s H2S concentration can be lowered to 20 mg/m3. Our study recommends combining the Jia-2 and Jia-1 layers to build the Huangcaoxia underground gas storage. This plan can quickly reduce the H2S concentration of the produced gas to 20 mg/m3, thus meeting the gas export standards as well as the HSE (Health, Safety, and Environment) requirements in the field. This study helps the engineers understand the H2S removal for sulfur-containing UGS as well as provides technical guidelines for converting other multilayered sour gas fields into underground storage sites.

Optimization of effecting parameters for flue gas desulfurization in a self‐priming venturi scrubber using response surface methodology

AbstractHydrogen sulfide (H2S), a highly poisonous and corrosive gas, is regarded as a hazardous air pollutant with significant effects on human health. Hence, reduction of hydrogen sulfide (H2S) gas from the atmosphere is very essential. In the present work, self‐priming venturi scrubber is employed to extract H2S gas from the air. Response surface methodology (RSM) with a central composite design (CCD) has been selected to investigate maximizing the H2S removal efficiency by optimizing the process variables. Experiments were carried out by altering the throat gas velocity, outer cylinder liquid level and inlet concentration of H2S. The analysis of variance (ANOVA) test showed that the parameters had a significant effect on the efficiency of H2S removal. A quadratic equation has been developed that accurately predicts the percentage of removal efficiency. The appropriateness of the generated model has been verified by the value of higher R2 resulting from the regression analysis. According to the observations, the velocity of throat gas has the highest effect on the H2S removal efficiency, whereas inlet H2S concentration has the least effect.

Digital twin-based optimization and demo-scale validation of absorption columns using sodium hydroxide/water mixtures for the purification of biogas streams subject to impurity fluctuations

This paper aims to validate a demo scale plant scrubber technology through experimental campaign and development of a digital twin. Thus, it is useful to evaluate the H2S absorption process in a biogas production plant for analysis and optimization purposes. The absorber unit removes H2S through the chemical absorption via sodium hydroxide (NaOH) as wet agent (30% w/w). The column treats 300 Nm3/h of biogas, whose inlet H2S concentration ranges from 1000 to 3000 ppm. Field measurements are conducted to investigate the H2S removal efficiency. An experimental dataset is collected, processed and used as input on Aspen PLUS suite to develop the digital twin.This model is helpful to generate a large dataset and simulate operating conditions different from the demo-scale plant. The process simulation is then exploited to perform a sensitivity analysis to figure out main variables influencing the H2S removal efficiency. Operating conditions such as H2S concentration, soda concentration and flowrate, temperature, and freshwater flowrate are perturbed in the sensitivity analysis. NaOH flowrate and its concentration are the variables with the biggest impact on the process. In detail, the highest efficiency performance was obtained using 50% NaOH solution with a flowrate higher than 8 kg/h.

Simultaneous removal of H2S and particulate matter by a multistage dual-flow sieve plate scrubber

In this work, an experimental study has been conducted in a newly designed and developed dual-flow scrubber with three sieve plates for simultaneous removal of hydrogen sulphide and particulate matter (fly-ash) from syngas produced in a gasifier as these impurities of syngas destroy and decrease the efficiency of the downstream processing equipment. The performance of the scrubber at different gas and liquid flow rates in the range of 16.59 × 10−4- 27.65 × 10−4 Nm3/s 20.649 × 10−6-48.183 × 10−6 m3/s has been observed for both the particulate matter and hydrogen sulphide removal along with the effect of inlet particulate loading (15 × 10−3- 25 × 10−3 kg/Nm3) and 100–300 ppm inlet H2S loading. The H2S removal efficiency in the dual-flow wet scrubber increased from 78.88% to 87.45% when the particulate matter loading was increased from zero to 25 × 10−3 kg/Nm3 at 300 ppm inlet H2S concentration for 48.183 × 10−6 m3/s liquid flow rate and 27.65 × 10−4 Nm3/s gas flow rate. The efficiency of the particulate matter is similar to that of the particulate scrubbing in absence of the H2S.

Simultaneously remove Phosphine, hydrogen sulfide and hydrogen Cyanide: Synergistic effect of micro-electrolysis and liquid-phase catalytic electrolysis

In this study, phosphine, hydrogen sulfide and hydrogen cyanide were efficiently removed in the three-dimensional electrochemical catalysis system. The effect of electrolysis conditions, micro-electrolysis & electrolysis system, and micro-electrolysis & liquid-phase catalytic electrolysis system on PH3, H2S and HCN removal was investigated. The mechanism of synergistic effect of electrolysis, micro-electrolysis and liquid-phase catalysis, as well as the catalytic oxidation pathway of PH3, H2S and HCN, were thoroughly analyzed. The results showed that the addition of Fe/C particle electrodes improved the removal efficiency and stability of PH3, H2S and HCN in both liquid-phase catalytic and electrolytic systems. The removal efficiency was increased as the external field voltage increased. The reaction products and free radicals of the PH3, H2S and HCN removal process were analyzed by XRD, GC, ion chromatography and ESR, etc., and PH3, H2S and HCN was eventually oxidized to PO43-, S, H2, CO2, N2 and NO3– by free radicals. By incorporating the micro-electrolysis effect into liquid-phase catalytic electrolysis system, the removal efficiencies of PH3, H2S and HCN removal rate can be maintained above 90% for nearly 800 min, eventually reaching 90%, 98%, 93.68% at 800 min. The system is regenerative and the removal efficiency of PH3, H2S and HCN after regeneration is about 80% of the original.

Highly Dispersed FeAg-MCM41 Catalyst for Medium-Temperature Hydrogen Sulfide Oxidation in Coke Oven Gas.

The traditional hydrolysis-cooling-adsorption process for coke oven gas (COG) desulfurization urgently needs to be improved because of its complex nature and high energy consumption. One promising alternative for replacing the last two steps is selective catalytic oxidation. However, most catalysts used in selective catalytic oxidation require a high temperature to achieve effective desulfurization. Herein, a robust 30Fe-MCM41 catalyst is developed for direct desulfurization at medium temperatures after hydrolysis. This catalyst exhibits excellent stability for over 300 h and a high breakthrough sulfur capacity (2327.6 mgS gcat-1). Introducing Ag into the 30Fe-MCM41 (30Fe5Ag-MCM41) catalyst further enhances the H2S removal efficiency and sulfur selectivity at 120 °C. Its outstanding performance can be attributed to the synergistic effect of Fe-Ag clusters. During H2S selective oxidation, Fe serves as the active site for H2S adsorption and dissociation, while Ag functions as the catalyst promoter, increasing Fe dispersion, reducing the oxidation capacity of the catalyst, improving the desorption capacity of sulfur, and facilitating the reaction between active oxygen species and [HS]. This process provides a potential route for enhancing COG desulfurization.

Mathematical modelling of water-based biogas scrubber operating at digester pressure

Abstract The socio-economic feasibility of biogas as a renewable source of energy has been analyzed for the energy security of India. The impact of Indian government schemes such as the National Biogas and Manure Management Programme (NBMMP) for the implementation of Bioenergy has been discussed in detail. The feasibility of a water-based scrubber (high as well as low pressure) for Bio-methane production in the Indian scenario was analyzed. Theoretical modeling for Steady-State Digester Pressure Water-based Biogas Scrubber (DP-WBS) was performed using the Sum Rate Method. Design parameters for a DP-WBS-based scrubber having a capacity of 60 Nm3/h were optimized at the digester pressure of 110 mm of the Water Column (WC). Modeling for raw biogas (CH4 64 %, CO2 30 %, H2S 1000 ppm) scrubbing was done with and without water recirculation. Sensitivity analysis shows that a 90 m3/h water flow rate and a total of 7 theoretical stages are required to reduce the CO2 concentration in biogas from 30 % to &lt;2.58 % and H2S concentration from 1000 ppm to &lt;20 ppm. H2S removal efficiency in the scrubber was found to be highly dependent on operating conditions at the regeneration section.

ANALYSIS AND EVALUATION OF THE BIOGAS PURIFICATION TECHNOLOGIES FROM H2S

H2S concentrations in biogas are limited by environmental regulations. Because these gases are toxic to human health, cause corrosion, and damage the combined heat and power (CHP) engines and other metallic parts after burning. Hence, the following requirements must be met by a biogas purification method: 1 – high H2S removal efficiency (RE), 2 – stability over a long period of time, 3 – low cost, 4 – minimal biogas dilution, and 5 – straightforward structure. There are various physical, chemical, and biological technologies, which can be undertaken to meet earlier mentioned criteria and efficiently remove H2S from biogas. In this study, electrochemical oxidation, adsorption by zeolite, pressure swing adsorption, adsorption on activated carbon, adsorption on metal oxides, adsorption on nano-particles, metal sulfide precipitation, water scrubbing, membrane separation, organic solvents (amine), microaeration, and purification by sulfur-oxidizing bacteria (anoxic, aerobic, anaerobic), will be introduced, while their pros and cons are compared and discussed in detail.