Acid Gas Research Articles

Novel four-in-one intumescent flame retardants for polypropylene: Synthesis, characterization and properties

To address the shortcomings of traditional intumescent flame retardants (IFRs), a novel four-in-one IFR (M [APP/NiCo2O4]) was constructed for the first time. It integrates acid source, gas source, carbon source (crosslinking β-CD), and synergistic agent (NiCo2O4 nanoparticles) into a single entity by a co-encapsulation technology. Under the loading of 20 wt%, its flame retardant performance was significantly better than that of simple mixed flame retardants, and it could increase the limiting oxygen index of polypropylene (PP) from 18 to 30.2 and pass the UL-94 V-0 rating. At the same time, it could reduce the peak of heat release rate, total heat release, and peak of CO production of PP by 77%, 22%, and 80%, respectively, showing excellent flame retardant performance. The excellent flame retardant performance is mainly because the synergist NiCo2O4 nanoparticles in the four-in-one flame retardant can easily combine and efficiently interact with the acid source, carbon source, and gas source in the intumescent flame retardant to form a more stable protective char residue. In addition, the crosslinking β-CD shell enhances both the water resistance and initial thermal decomposition temperature of PP containing the four-in-one IFR compared to PP with simple mixed control samples. After 72 h of water resistance test, it can still maintain the UL-94 V-0 rating. The presence of the crosslinking β-CD shell also improves the compatibility of the four-in-one flame retardant in PP, and its adverse effects on the mechanical properties of PP are also significantly smaller than those of the mixed control sample.

Fabrication of freshness indicators based on methylcellulose-containing color indicator solutions for monitoring the quality of coconut water

This is the first study to apply intelligent packaging to coconut water. The purpose of this study was to determine the best color indicator solution for making freshness indicator labels based on methylcellulose along with the color change profile of coconut water during storage at room temperature. Three color indicator solutions were used, namely phenol red, bromothymol blue, and methyl red, which were then continued with the fabrication of freshness indicator labels based on methylcellulose from each of these color indicator solutions and applied to coconut water at 25 °C room temperature storage for 24 h with observations every 4 h in the form of pH, total dissolved solids, total acid, turbidity, total microbes, CO2 gas, O2 gas, and freshness indicator label color changes. The values of pH, total soluble solids, and O2 gas decreased with storage time, whereas the values of total acid, turbidity, total microbes, and CO2 gas continued to increase. The methylcellulose-based phenol red freshness indicator label provides the best color change profile that matches the freshness condition of coconut water, namely purplish red (fresh), orange (immediately consumed), and yellow (damaged) so that it can be used as intelligent packaging to monitor the quality of coconut water.

Improving the prediction of elemental sulfur solubility in sour gas mixtures by modifying cubic equations of state

So far, several correlations have been developed to forecast the solubility of sulfur in various mixtures of acid gases with different concentrations of hydrogen sulfide. These correlations are correlative methods requiring experimental sulfur solubility data to tune their model parameters. Besides, correlative methods have many restrictions and are useable only for a limited range of operating conditions. Another approach for predicting sulfur solubility is applying equations of state. The predictive ability of equations of state has made them a powerful tool to more accurately perform the equilibrium phase calculations of acid gas mixtures in a vaster operating range. The major problem of the equations of state is the inaccurate characterization of their parameters for elemental sulfur due to its chemical complexity. In this study, the performance of three cubic equations of state is evaluated for forecasting the solubility of elemental sulfur in different acid gas mixtures. The main idea which is supposed to be put forward for rectifying defects of cubic equations of state is to model the trend of errors propagated in predicting the solubility of sulfur. Indeed, the effect of sulfur chemical reactions is ignored, and a generalized correction function is developed to compensate for deviations arising from the simplification assumptions. Subsequently, the results predicted by modified equations of state are compared to experimental sulfur solubility data and previously existing methods. Finally, a case study is performed on a sour gas reservoir sample to predict precipitation P-T curve and to calculate sulfur solubility changes with the pressure and temperature reduction throughout the gas well. Predicted results revealed the proposed correction function could significantly decrease the solubility calculations obtained from the modified equations of state under 5.6%, which is a good achievement compared to their original versions.

Volatile acetic acid selective adsorption by biomass-derived activated carbon with humidity-resistance: Tunable implanting and activation approach of activator

The selective adsorption and capture of polar organic acid gas by activated carbon (AC) absorbent could solve the challenge of irritant volatile organic compound discharge. However, volatile acid gas selective adsorption by traditional activated carbon with humidity resistance remains challenged. In this study, we developed an innovative one-step chemical synthesis method using discarded banana peels as a carbon source to create porous carbon materials. The selection of activators including sodamide and potassium hydroxide along with tunable implanting means of activator under different activated temperatures were modulated to optimize the fabrication of activated carbon. The results reveal that the low dosage of NaNH2 activator (NaNH2/carbon precursor = 1) implanted into carbon precursor through one-step ball-milling could contribute an excellent structural properties, and higher activated temperature makes the mesoporous behavior of activated carbon more obvious. Based on various optimization conditions, the optimal sample, BAC900, displays remarkable structural features (SBET = 2302 m2/g, Vtotal = 1.968 cm3 g−1, V>2nm = 1.474 cm3 g−1), achieving exceptional acetic acid adsorption efficiency (24.105 mmol g−1). Comparative analysis under various synthetic conditions revealed a close linear relationship between the structural characteristics (total pore volume) of adsorbent and acetic acid adsorption efficiency. We further explored the role of mesopores in facilitating acetic acid adsorption at relatively high pressures and their contribution to enhancing the hydrophobicity of the adsorbent. Additionally, we employed the Differential Isothermal Heat (DIH) technique to predict adsorption selectivity at varying relative humidity, revealing the higher adsorption heat (57 kJ mol−1) of acetic acid compared to water vapor (36 kJ mol−1). This comprehensive study emphasizes the outstanding adsorption selectivity of adsorbent for acetic acid, even in humid environments. Furthermore, the low adsorption heat of the BAC900 indicates good reversibility and reusability, paving the way for the practical application of biomass-derived functional biochar adsorbents in the environmental management of threatening acid VOCs pollutants.

Energy-saving exploration of separation for EG/1,2-BDO binary azeotrope based on energy, environmental and economic analysis

In the synthesis of ethylene glycol (EG) from syngas, the inevitable by-product, 1,2-butanediol (1,2-BDO), is generated. Additionally, EG and 1,2-BDO form minimum boiling homoazeotrope, which is a challenge for conventional distillation method. To address this, four processes, extractive distillation process (EDP), extractive distillation with heat integration process (HI-EDP), side-stream extractive distillation process (SSEDP), and extractive dividing wall column process (EDWCP), are used for the separation of EG/1,2-BDO binary system. Firstly, a combination of VLE analysis and COSMO-SAC model analysis was employed to select appropriate entrainers (eugenol). Subsequently, interaction region indicator (IRI) was utilized to reveal the extractive distillation mechanism at the molecular level, demonstrating the feasibility of eugenol as an entrainer for separating EG/1,2-BDO mixture. Next, simulations of the EDP, HI-EDP, SSEDP, and EDWCP processes were conducted through Aspen Plus V11. The optimal process parameters for each flowsheet were determined by the minimum Total Annual Cost (TAC). Furthermore, the process performance was evaluated from economic, energy, and environmental aspects. The EDWCP process demonstrates superior performance compared to the EDP process, with reductions of 16.79% in TAC, 17.6% in TOC, and 14.8% in TCC. Additionally, emissions of acidic gases of decreased by 19.78%, while thermal efficiency improved by 32.91%. EDWCP process represent enormous potential in the field of energy efficiency, economy and environment.

Optimal operation of a natural gas sweetening plant

The most common method of removing acid gases from natural gas is through the use of solvent-based gas sweetening plants, which are energy-intensive. The present study aims to establish a plant-wide structure to operate natural gas sweetening plants optimally. Thus, a steady-state simulation of the Khangiran plant was carried out, and a 17% reduction in energy usage was achieved as a result of the optimization by the application of surrogate models. The self-optimizing method was applied to find the best set of controlled variables (CVs). There was found one unconstrained degree of freedom (DOF). The best CV for the remaining DOF was found to be the top stage temperature of the regenerator. Aspen Plus Dynamics was used to examine the performance of the proposed control structure utilizing simple traditional PIDs and compare it to modern feedback and feedforward MPCs.

Investigation into the Structure and Properties of Biochar Co-Activated by ZnCl2 and NaHCO3 under Low Temperature Conditions.

Using sodium lignosulfonate as feedstock, ZnCl2 and NaHCO3 co-activated the hierarchical porous carbons (HPCs) were prepared by one-pot pyrolysis with different NaHCO3 dosages (0-4 g) and carbonization temperatures (400-600 °C). Subsequently, phosphotungstate (HPW) was supported with the resulting biochar for the α-pinene hydration reaction to produce α-terpineol. The optimum preparation conditions were determined according to the yield of α-terpineol. The formation mechanism and physicochemical properties of HPCs were analyzed through TG, SEM, XPS, XRD, FT-IR, and N2 adsorption-desorption isotherms. The results demonstrated that NaHCO3 underwent a two-step reaction which liberated a substantial quantity of CO2, thereby enhancing activated carbon's macroporous and mesoporous structures. Simultaneously, NaHCO3 mitigated strong acid gas (HCl) emissions during ZnCl2 activation. Compared with AC450-4:8:0 prepared by ZnCl2 activation alone, the total pore volume of AC450-4:8:2 prepared by co-activation is increased from 0.595 mL/g to 0.754 mL/g and the mesopore rate from 47.7% to 77.8%, which is conducive to reducing the steric hindrance of the hydration reaction and improving the selectivity. Hydration experiments show that the selectivity of α-terpineol is 55.7% under HPW/AC450-4:8:2 catalysis, higher than 31.0% for HPW and 47.4% for HPW/AC450-4:8:0.

Investigation of decomposition and partial oxidation of mixed acid gas and methane for syngas production

Reaction processes of decomposition and partial oxidation of a mixture of acid gas (H2S and CO2) and methane (CH4) could enable the efficient production of valuable syngas resource (H2 and CO). In this work, the decomposition and partial oxidation of H2S–CH4–CO2 system was experimentally studied in a tube furnace. Effects of temperature, CH4 and CO2 addition, equivalence ratio and residence time were studied for syngas production and H2/CO variation. Extended temperature and pressure were then studied by equilibrium calculation for thermodynamic analysis in Aspen Plus software. The results showed the increasing temperature favored reactant conversion and syngas production. H2S decomposition was the dominant reaction at temperature below 1050 °C while threshold temperature for CH4 conversion over H2S was about 1100 °C. H2 was formed mainly via H2S decomposition at low temperatures. CH4 addition promoted H2 formation and conversely restrained H2S conversion. The introduction of O2 brought partial oxidation, favored the reaction rate, balanced H2/CO but reduced syngas production. H2/CO ratio also remained at an appropriate level at high CO2 addition since CO2 evidently adjusted the ratio via CO2+H2↔CO + H2O. However, this CO2 reactivity was only adequately expressed under high temperature and extended residence time. Equilibrium calculation confirmed experimental variation trends and revealed reducing pressure favored the syngas production. It could be inferred that extended residence time, higher temperature, suitable equivalence ratio, CH4 and CO2 addition and low pressure could enable improvement in both syngas production and H2/CO. This study revealed high syngas production and adjustment of H2/CO could be realized in H2S–CH4–CO2 system and this might be of great practical in industry.

Acidic Gas Determination Using Indium Tin Oxide-Based Gas Sensors.

This work has presented gas sensors based on indium tin oxide (ITO) for the detection of SO2 and NO2. The ITO gas-sensing material was deposited by radio frequency (RF) magnetron sputtering. The properties of gas sensing could be improved by increasing the ratio of SnO2. The response characteristics of the gas sensor for detecting different concentrations of NO2 and SO2 were investigated. In the detection of NO2, the sensitivity was significantly improved by increasing the SnO2 ratio in ITO by 5%, and the response and recovery time were reduced significantly. However, the sensitivity of the sensor decreased with increasing SO2 concentration. From X-ray photoelectron spectroscopy (XPS) analysis, the gas-sensitive response mechanisms were different in the atmosphere of NO2 and SO2. The NO2 was adsorbed by ITO via physisorption but the SO2 had a chemical reaction with the ITO surface. The gas selectivity, temperature dependence, and environmental humidity of ITO-based gas sensors were systematically analyzed. The high detection sensitivity for acidic gas of the prepared sensor presented great potential for acid rain monitoring.

Microparticle-aggregation effect of intumescent flame retardants on flame retardancy and toughening property of polypropylene

It is a widespread problem that loading intumescent flame retardant (IFR) into polypropylene (PP) always sacrificed the mechanical properties significantly. To develop PP composites with high flame retardancy and toughness, a new intumescent flame retardant (TAIC-IFR) with microparticle-aggregation structure was synthesized by a straightforward in-situ cemented method. Through its microparticle-aggregation effect, the TAIC-IFR enhanced the toughness and charring flame retardancy of PP composites, compared with the traditional intumescent flame retardant mixtures. The 3TAIC-24IFR/PP sample exhibited an increase in impact strength and elongation at the break by 71.8 % and 233.5 % respectively compared with 27IFR/PP. The cemented TAIC-IFR particles with rough surfaces and triallyl triazine triketone component enhanced the interface performance between the fillers and PP matrix. In addition, the TAIC-IFR with particulate microparticle-aggregation characteristics promoted charring reactions among different flame retardant components, thereby enhancing its char-forming flame retardant effect in PP. Specifically, 1TAIC-24IFR/PP with cemented aggregated flame retardant particles exhibited a UL 94 V-0 rating and 28.5 % of limiting oxygen index (LOI), while PP with IFR mixture performed no UL 94 rating and a lower LOI. Moreover, the residue rate of 1TAIC-24IFR/PP increased to 15.9 % from 0 % of PP in cone calorimeter test. These results were attributed to the microparticle-aggregation effect of the acid source, carbon source, and gas source in TAIC-IFR particles, which exhibited better charring effect and barrier effect. This work provides a new idea for designing construction way of flame retardants to develop polymer materials with high flame retardancy and good toughness.

Wet H2S corrosion and degradation of pipeline in amine regeneration system

AbstractThe paper presents the results of non‐destructive testing examinations, metallographic tests and risk assessment of degradation related to corrosion of amine regeneration unit in a desulphurisation system. Intensive corrosion resulting from acid gases environment upon water condensation causes perforation of the pipeline. Detailed analysis reveals cracking related to the mechanism of wet H2S. Hydrogen penetration, resulting from the wet H2S process, causes a decrease in mechanical properties of steel and an increase in hydrogen content inside steel. Corrosion results mostly from high stream velocity, the presence of acid gases (with high ammonia content), the presence of amine and low stream temperature.

A comparison between Claus and THIOPAQ sulfur recovery techniques in natural gas plants

A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data.

Understanding the performance of amine-based DESs for acidic gases capture from biogas

The current work presents comprehensive data derived from the thermophysical assessment of monoethanolamine (MEA)-based Deep Eutectic Solvents (DESs) for H2S extraction from biogas. The MEA-based DES demonstrated the capability to absorb H2S and CO2 from biogas at various pressures, as evidenced by density profile analysis. Analyses were made to determine the solubility of acidic gases and the solubility selectivity of H2S over CO2, H2S over CH4, and CO2 over CH4. According to the findings, MEA-based DES absorbed 40 %, 60 %, and 80 % of H2S concentration from biogas at pressures of 10 atm, 15 atm, and 20 atm, respectively. Structural analyses, including radial and spatial distribution functions, quantification of hydrogen bonds between DES species and acidic gases, and evaluation of non-bonded interaction energies, were explored to gain a more in-depth understanding of the absorption mechanism. Moreover, the diffusion coefficient of species after the absorption process reveals that CO2, with a diffusion coefficient of 556.5 Å2/ns, moves more quickly than H2S, which exhibited a value of 348.2 Å2/ns. According to our findings, the MEA-based DES is a highly effective choice for removing H2S from biogas.

Dissolution behavior and kinetic investigation of 〖Ca〗^(2+) in the dissolution of colemanite in propionic acid presence saturated with synthetic flue gas

Colemanite (〖2CaO.3B〗_2 O_3.5H_2 O) is a calcium borate mineral and can be expressed as the primary material of industrial production of boric acid. Boric acid is one of the most essential raw materials obtained by solving colemanite ore in acidic solutions and gases. The dissolution behavior and kinetics of 〖Ca〗^(2+) in a solution of colemanite in a propionic acid solution saturated with synthetic flue gas were examined. In this context; the effects of particle size, reaction temperature, acid concentration, solid-liquid ratio and synthetic flue gas flow rate parameters were investigated. According to the experimental data, it was observed that the amount of 〖Ca〗^(2+) passing to the solution increased with the increase of the reaction temperature, acid concentration and gas flow rate, and with the decrease in solid-liquid ratio and grain size. Experimental results were analyzed by homogeneous and heterogeneous models using the Statistica package program, and it was determined that the dissolution of 〖Ca〗^(2+) in solution complies with the “Avrami” model. The activation energy (E) was found as 〖26.83 kJ.mol〗^(-1) and the Arrhenius constant (A) was found as 〖8.9*10〗^3.

Peculiarities of development and metabolism of <i>Streptococcus thermophilus</i> strains under different conditions of deep liquid phase cultivation

The microflora of most fermented dairy products, including cheeses, consists entirely of lactic acid bacteria, i. e., bacterial starter cultures with different species and strain composition that are specially introduced into the mixture. The species composition of the starter must ensure the intensity and direction of the microbiological and biochemical processes of the produced product and guarantee its safety, quality and storability. In particular, lactic acid bacteria transform the main components of milk (protein, milk fat, lactose) into taste, aromatic, and biologically active substances involved in the formation of identification and organoleptic characteristics of fermented dairy products. The number of starter microorganisms in fermented dairy products, including cheeses, significantly exceeds the content of any foreign microflora and can cause the appearance of organoleptic defects such as acid, bitterness, non-specific off-taste or excessive gas formation. The ability of microorganisms to form certain metabolic products is determined both by their species and strain properties, and by cultivation conditions. These include, first of all, the composition of the development environment and temperature conditions of cultivation. By combining the composition of the starter and selecting favorable modes for cultivating microorganisms, it is possible to achieve optimal development of the starter microflora, obtaining products with the desired quality characteristics. This article presents the results of a comparative assessment of the properties of production strains of Streptococcus thermophilus during their development in dairy environments at optimal temperatures (41 ± 1) °C, simulating conditions for the production of fermented milk products, as well as in modes simulating cheese ripening conditions (11 ± 1) °C and 4% table salt concentration. The nature of the enzymatic processes of glycolysis, proteolysis, lipolysis, and flavor formation as a result of the metabolism of these cultures was also assessed.

A bifunctional 3D porous MOF with potential for fluorescence sensing of picric acid and natural gas purification

A pillared-layer fluorescence metal-organic framework [Zn2(TCPP)(BPE), GXZ-1] has been synthesized by using the AIE ligand 2,3,5,6-tetrakis(4-carboxyphenyl) pyrazine (TCPP) and 1,2-Bis(4-pyridyl) ethylene (BPE). The GXZ-1 exhibited remarkable stability in both air and various solvents. Furthermore, fluorescence experiments demonstrated its potential as a fluorescence probe for the sensitive detection of picric acid (PA). Additionally, the activated GXZ-1 exhibited permanent porosity with a high BET surface area of 210.59 m2 g−1 and a narrow pore size distribution of 0.6 nm. These properties enable GXZ-1 ideally suitable for gas separation applications. Gas adsorption experiments revealed promising CO2/CH4 separation properties, with an IAST adsorption selectivity of 8.37 and 5.39 for equimolar CO2/CH4 gas mixtures at 273/298 K and 1 atm, respectively. In addition, GXZ-1 displayed outstanding chemical and thermal stability, further enhancing its potential for practical applications.

Optical fiber gas sensor with multi-parameter sensing and environmental anti-interference performance

Formic acid finds widespread applications in numerous fields, including the petrochemicals production, rubber industry, and leather tanning process, in which the operational environments are complex and diverse. The corresponding industrial systems are often intricate and highly integrated. Indeed, formic acid gas is insidious and poses a hazard to both operating personnel and industrial equipment. The existing detection technologies for formic acid gas suffer from inherent technical limitations, making it challenging to effectively shield against industrial interference in complex environments while accurately conveying information. Furthermore, the simultaneous transmission of essential environmental data alongside formic acid gas concentration remains a formidable challenge, which is crucial for facilitating the integration and simplification of industrial system. In response to the aforementioned challenges, this research firstly employs an optical fiber structure (SNS: single mode fiber-no-core fiber-single mode fiber) with natural resistance to electromagnetic interference as the substrate. Subsequently, considering the characteristics of spectral variations and the response mechanism of formic acid gas, and addressing the issue of humidity interference of the current-stage sensors based on sensitive material, the chitosan and chitosan@PDMS are chosen as sensitive membranes. Finally, a correction formula was introduced to address the temperature and humidity coupling issue of the sensor, resulting in the successful development of two formic acid gas sensors. The chitosan-based sensor has a detection sensitivity of up to 7.7 pm/ppm, whose dual parameter detection performance for temperature and formic acid gas has been experimentally demonstrated. It can also correct the humidity-induced detection error in real-time by the correction formula. The chitosan@PDMS-based sensor was fabricated by plating a hydrophobic and breathable PDMS membrane on the surface of the chitosan-based sensor. In addition to maintaining the performance compared to the original sensor (response and recovery time was increased), the latter sensor can effectively resist the humidity interference from the environment. Furthermore, the new capability has been complemented for the simultaneous detection of temperature and humidity. That is, it realizes the dual parametric detection for formic acid gas and humidity, meanwhile providing the compensation ability for temperature change. The proposed sensors have the outstanding sensitivity, selectivity, immunity, and safety. This research not only effectively resolves the interference problem in formic acid gas detection, but also provides a new idea for equipment simplification and information integration in complex industrial systems.

Efficient purification of n-butanol by thermally coupled extractive distillation with mixed entrainer

To solve the problems of difficult separation of azeotropes and high energy consumption in the preparation of n-butanol from the fermented mother liquor, this study focused on the separation process integration of water/acetone/ethanol/n-butanol mixture based on the combination of mixed entrainer and thermally coupled distillation technology. Based on quantum chemical calculations, the molecular polarity and weak interaction between the entrainer and the mixture to be separated were studied at the molecular scale, and the separation mechanism of extractive distillation was revealed. Based on the simulation results, the three different configurations' process performance was evaluated and compared to the benchmark conventional extractive distillation process with ethylene glycol as the entrainer. The thermally coupled extractive distillation process with mixed entrainers can reduce the total annual cost by about 39.87%, reduce energy consumption and acid gas emissions by 46.53%, and improve the thermodynamic efficiency by 47.57%. The thermally coupled extractive distillation process with mixed entrainers is an economical, energy-saving, and environmentally friendly production scheme superior to the conventional extractive distillation process. The thermally coupled extractive distillation process, as an essential energy-saving technology for producing n-butanol from fermentation mother liquor, has broad development prospects.

Parametric study and optimization of an acid gas enrichment plant with outlet streams and energy usage consideration

Acid gas enrichment (AGE) is a new method to increase the H2S conversion in conventional Clause process. In this paper effect of methyl diethanolamine (MDEA) flow rate, MDEA temperature, acid gas flow rate, and AGE tower pressure on the outlet H2S and CO2 concentration and energy consumption have been studied. A novel procedure based on enthalpy of combustion in the reaction furnace and incinerator is conducted for energy consumption calculations. By changing MDEA and inlet acid gas flow rates, a maximum H2S concentration in the enriched stream could be attainable. Increasing MDEA temperature will decrease maximum H2S concentration and enriched acid flow rate; also, CO2 concentration in off-gas will be decreased. By increasing AGE pressure, maximum H2S concentration in the enriched stream will be diminished. At higher MDEA flow rates, lower AGE pressures will bring higher H2S concentration in enriched acid gas stream. According to flame temperature simulation in the reaction furnace, energy consumption is directly related to H2S concentration in the sulfur recovery unit (SRU) feed stream. Results show that maximum H2S concentration in the enriched acid gas stream has the best conditions from energy point of view. At optimum conditions, H2S concentration in enriched acid gas is 62.45 mol%, which has been increased by 24.8%, compared with existing plant conditions, and energy consumption has been decreased by 25.05 GJ/h, and CO2 concentration in off-gas is 94.94 mol%.

Thermodynamic Simulation of the Interaction Reaction between Copper-Based Oxygen Carrier and Acid Gases from Municipal Solid Waste Pyrolysis

To reveal the interaction reaction of copper-based oxygen carriers with acid gases during chemical looping with oxygen uncoupling of MSW pyrolysis and gasification syngas, the thermodynamic analysis is employed by HSC Chemistry. The thermodynamic simulation results show that the products of the copper-chloride interactions are solid CuCl, gaseous Cu3Cl3 (g), and CuCl (g), and no solid CuCl2 is formed. In addition, it’s found that CuCl (g) originates from the high-temperature decomposition of the complex Cu3Cl3 (g). At a sufficient amount of OC, the interaction products of copper-based OC with H2S are CuSO4, SO2, and Cu2SO4, while Cu2S and CuS disappear. Compared to HCl, H2S dominates during the competitive reaction or adsorption with copper-based oxygen carrier or CaO. Due to the capture of Cl and S in the gaseous state of Ca2+, the lattice oxygen of chlorinated or sulfated oxygen carriers can be restored, suggesting that CaO can be used as an in situ dechlorinator for CLOU. The results of this work will provide theoretical guidance for the inhibition of copper-based oxygen carriers chlorination loss and active design of multifunctional oxygen carriers.