Ammonia Pressure Research Articles

Light triggers green recovery: Boosted biomethane production from ammonia-stressed anaerobic digestion through optimized illuminated bioreactor

Excess ammonia generated during anaerobic digestion (AD) often poses a great challenge on efficient waste-to-energy bioconversion, which requires feasible strategies to improve the performance. Herein, by response surface methodology (RSM), an innovative light-assisted bioreactor was designed for boosting ammonia-stressed AD. The proposed optimal light condition (225 W/m2 with 63 min/day) with incandescent lighting boosted CH4 yield (198 ± 15 mL CH4/g-DOCremoval), which was twofold of the dark reactor under ammonia stress. This light-induced enhancement was further found to be reliable and adaptive at different ammonia levels (2500–8000 mg/L), revealing its effectiveness for treating various ammonia-rich wastes. Additionally, the practical feasibility of sunlight utilization was confirmed by the similar performance obtained under simulated solar lighting (ultraviolet cut). Furthermore, the developed bioreactor exhibited a stable and superior conversion efficiency for 2 months, suggesting its sustainability for long-term operation. The mechanism insights revealed that light acted as stimulus on ammonia-stressed anaerobes, effectively regulated the enzyme activities, the functional microbiome, and the sludge properties to alleviate the ammonia inhibition. The critical coenzymes involved in methanogenic pathways (hydrogenotrophic and acetotrophic) were upregulated by light. Meanwhile, proper light stimulation diversified the ammonia-tolerant fermentative taxa (hydrolytic and acetogenic genera), which jointly collaborated with the enriched Methanosarcina. Under ammonia pressure, those enriched anaerobes aggregated in compact clusters which thermodynamically favored the sludge electroactivity and hydrophobicity, and assisted the syntrophic bioconversion. Therefore, the proposed bioreactor would be a promising technique to solve ammonia inhibition and achieve the sustainable waste-to-energy bioconversion with solar integration.

Synergistic Effect of MIL-101/Reduced Graphene Oxide Nanocomposites on High-Pressure Ammonia Uptake.

Ammonia has emerged as a potential working fluid in adsorption heat pumps (AHPs) for clean energy conversion. It would be necessary to develop an efficient adsorbent with high-density ammonia uptake under high gas pressures in the low-temperature range for waste heat. Herein, a porous nanocomposite with MIL-101(Cr)-NH2 (MIL-A) and reduced graphene oxide (rGO) was developed to enhance the ammonia adsorption capacity over high ammonia pressures (3–5 bar) and low working temperatures (20–40 °C). A one-pot hydrothermal reaction could form a two-dimensional sheet-like nanocomposite where MIL-A nanoparticles were well deposited on the surface of rGO. The MIL-A nanoparticles were shown to grow on the rGO surface through chemical bonding between chromium metal centers in MIL-A and oxygen species in rGO. We demonstrated that the nanocomposite with 2% GO showed higher ammonia uptake capacity at 5 bar compared with pure MIL-A and rGO. Our strategy to incorporate rGO with MIL-A nanoparticles would further be generalizable to other metal–organic frameworks for improving the ammonia adsorption capacity in AHPs.

Improved anaerobic digestion under ammonia stress by regulating microbiome and enzyme to enhance VFAs bioconversion: The new role of glutathione

Several methods, such as dilution, ion exchange, and bioaugmentation, have been tried to improve anaerobic digestion (AD) process performance under ammonia stress. Herein, a new strategy for improving AD under ammonia pressure by regulating microbiome and enzyme to enhance volatile fatty acids (VFAs) bioconversion was reported. Under ammonia stress, the methane yield was raised by 41.7% with glutathione addition (5 mg/g VS) during long-term AD of food waste. This glutathione-induced improvement was found not due to the mitigation of proton imbalance and potassium depletion or the elimination of excessive reactive oxygen species. Interestingly, the ammonia-stressed bioconversions of propionate and butyrate → acetate → methane and the cell viability were remarkably enhanced in the presence of glutathione. Further integrated metagenomic and metaproteomic analyses revealed that the key microbiota (i.e., syntrophic acetogenic taxa and their assistant bacteria and acetotrophic methanogens) related to the above biotransformations were enriched. Meanwhile, the expressions of vital proteins (such as RNA polymerase subunit α, ribosomal protein L25, and iron adenosine triphosphate binding cassette transporter substrate-binding protein) involved in enzyme synthesis and catalyzing the bioconversions above were significantly upregulated. The reported new role of glutathione on regulating functional microbiome and enzyme offered an alternative strategy for improving AD performance under high ammonia condition.

CO2 absorption into aqueous ammonia using membrane contactors: Role of solvent chemistry and pore size on solids formation for low energy solvent regeneration

Solids formation can substanitally reduce the energy penalty for ammonia solvent regeneration in carbon capture and storage (CCS), but has been demonstrated in the literature to be difficult to control. This study examines the use of hollow fibre membrane contactors, as this indirect contact mediated between liquid and gas phases in this geometry could improve the regulation of solids formation. Under conditions comparable to existing literature, NH4HCO3 was evidenced to primarily crystallise in the gas-phase (lumen-side of the membrane) due to the high vapour pressure of ammonia, which promotes gaseous transmission from the solvent. Investigation of solvent reactivity demonstrated how equilibria dependent reactions controlled the onset of NH4HCO3 nucleation in the solvent, and limited ‘slip’ through transfomation of ammonia into its protonated form which occurs prior to the phase change. Crystallisation in the solvent was also dependent upon ammonia concentration, where sufficient supersaturation must develop to overcome the activation energy for nucleation. However, this has to be complemented with a reduction in solvent temperature to offset vapour pressure and limit the risk of gas-phase crystallisation. While changes to the solvent chemistry were sufficient to shift from gas-phase to liquid phase crystallisation, wetting was observed immediately after nucleation in the solvent. This was explained by a local region of supersaturation within the coarse membrane pores that promoted a high nucleation rate, altering the material contact angle of the membrane sufficient for solvent to breakthrough into the gas phase. Adoption of a narrower pore size membrane was shown to dissipate wetting after crystallisation in the solvent, illustrating membrane contactors as a stable platform for the sustained separation of CO2 coupled with its simultaneous transformation into a solid. Through resolving previous challenges experienced with solids formation in multiple reactor configurations, the cost benefit of using ammonia as a solvent can be realised, which is critical to enabling economically viable CCS for the transition to net zero, and can be exploited within hollow fibre membrane contactors, eliciting considerable process intensification over existing reactor designs for CCS.

Анализ влияния факторов неопределенности на математическое моделирование процесса обратного расширения аммиака в тихоходной поршневой компрессорной ступени. Часть 1

The paper presents an analysis of the influence on the mathematical modeling of the process of reverse expansion of ammonia in the area of wet steam, implemented in the working chamber of the reciprocating compressor stage, of such uncertainty factors as the method for calculating the heat transfer coefficient, the surface temperature of the wall of the working chamber and the degree of dryness at the beginning of the process of reverse expansion. The mathematical model is based on the equations of the first law of thermodynamics for a body of variable mass, the equation of state of a real gas, the Clausius– Clausius and Newton–Richmann equations. The results of the calculation showed that the instantaneous values of the pressure and temperature of ammonia, as well as its degree of dryness during reverse expansion in the wet steam region, significantly depend on the chosen method for calculating the heat transfer coefficient. The process under consideration is also significantly influenced by the temperature of the walls of the compressor working chamber, in which the compression process is implemented, and the degree of dryness of ammonia at the beginning of the expansion process.

Efficient and reversible absorption of low pressure NH3by functional type V deep eutectic solvents based on phenol and hydroxypyridine

Highly efficient and reversible absorption of low pressure ammonia by phenol-hydroxypyridine deep eutectic solvents.

A green vapor suppressing agent for aqueous ammonia carbon dioxide capture solvent: Microcontactor mass transfer study

Aqueous ammonia is a promising carbon dioxide capture solvent and has recently attracted significant attention, but its main problem is high evaporation rate of ammonia in the absorber. Glycerol, which is a by-product of biodiesel, has hydroxyl groups that bind to ammonia molecules. Hence, it can reduce the vaporization of ammonia as an additive and improve the CO2 absorption properties. In this work, the mass transfer performance of glycerol, as an ammonia vaporization reduction additive, was investigated. Carbon dioxide absorption experiments using ammonia-glycerol hybrid solvent have been done in a T-shaped microchannel. The impact of process condition, including ammonia concentration (4–10 wt%), glycerol concentration (1–3 wt%), liquid flow rate (3–9 ml/min) and temperature (20–40 °C) was investigated on the volumetric overall mass transfer coefficient (KGaV), absorption percentage (AP) and volumetric molar flux (NAaV). According to the results, rising the glycerol concentration in the range of 2–3 wt% leads to an increase in KGaV by 4.8%. Hence, the addition of glycerol to aqueous ammonia not only increases the mass transfer coefficient but also reduces the vapor pressure of ammonia as a green vapor suppressing agent and diminishes the ammonia loss in the absorption tower.

Establishment of a murine model of acute-on-chronic liver failure with multi-organ dysfunction

Acute-on-chronic liver failure (ACLF) is a distinct clinical entity with high probability of organ failure and mortality. Since patients generally present late, experimental models are needed to understand the pathophysiology and natural course of the disease. To reproduce the syndrome of ACLF, chronic liver disease was induced in C57BL6 mice (6-8weeks; approximately 20-24g weight) by intraperitoneal administration of carbon tetrachloride (CCl4) for 10weeks followed by an acute injury with acetaminophen (APAP) and lipopolysaccharide (LPS). Blood, ascitic fluid, and organs were collected to study cell death, regeneration, and fibrosis. At 24h post-APAP/LPS infusion, the liver tissue showed increased hepatocyte ballooning and endothelial cell TUNEL positivity. This was followed by progressive hepatocyte necrosis from perivascular region at day 7 to lobular region by day 11. ACLF (day 7 and day 11) animals showed increase in bilirubin (p < 0.05), prothrombin time (p < 0.0001), blood ammonia (p < 0.001), and portal pressure post-acute hepatocellular injury similar to human ACLF. Ascites was noticed by day 11 with median serum-ascites albumin gradient of 1.2 (1.1-1.3)g/dL. In comparison to cirrhosis, ACLF group (day 7 and day 11) showed significant decrease in Sirius red (p ≤ 0.0001), collagen1 (p < 0.0001), and a-SMA proportionate area (p < 0.0001) with loss of hepatocytes regeneration (p < 0.005). At day 11, ACLF animals also showed significant increase in serum creatinine (p < 0.05) and acute tubular necrosis suggestive of organ failure, compared to cirrhotic animals. The CCL4/APAP/LPS (CALPS) model of ACLF mimics the clinical, biochemical, and histological features of ACLF with demonstrable progressive hepatocellular necrosis, liver failure, impaired regeneration, development of portal hypertension, and organ dysfunction in an animal with chronic liver disease.

EFFECT OF COMPRESSOR CARGO SUCTION PRESSURE AND TANK PRESSURE ON THE LENGTH OF THE RELIQUEFACTION PROCESS ON LPG/C GRIYA BORNEO

LPG / C Griya Borneo is a gas vessel with a semi-pressurized type, where the supporting components in the form of cargo handling equipment have a very big influence on the success and safety of ship operations. This is important to note because when the ship will carry out the loading process, the load temperature must be in accordance with the boiling point. High temperatures on ammonia loads can increase the pressure in the tank so that it exceeds the specified pressure limits and ammonia loads that have high temperatures need to be reliquefaction. In addition, the compressor compressor suction pressure that does not work in accordance with what is expected to affect the reliability process. This resulted in the reliquefaction process being longer than usual. The long reliquefaction process results in more fuel being used so that it costs a lot. Therefore the writer makes a thesis related to the problems experienced by the ship owned by PT Humpuss Transportasi Kimia aims to find out how much influence the compressor compressor suction pressure and tank pressure on the process of reliquefaction on the LPG / C Griya Borneo ship, the place where the authors practice.

Achieving industrial ammonia synthesis rates at near-ambient conditions through modified scaling relations on a confined dual site

The production of ammonia through the Haber-Bosch process is regarded as one of the most important inventions of the 20th century. Despite significant efforts in optimizing the process, it still consumes 1 to 2% of the worldwide annual energy for the high working temperatures and pressures. The design of a catalyst with a high activity at milder conditions represents another challenge for this reaction. Herein, we combine density functional theory and microkinetic modeling to illustrate a strategy to facilitate low-temperature and -pressure ammonia synthesis through modified energy-scaling relationships using a confined dual site. Our results suggest that an ammonia synthesis rate two to three orders of magnitude higher than the commercial Ru catalyst can be achieved under the same reaction conditions with the introduction of confinement. Such strategies will open pathways for the development of catalysts for the Haber-Bosch process that can operate at milder conditions and present more economically viable alternatives to current industrial solutions.

Kinetics and thermodynamics of ammonia solvation on Z2Cu, ZCuOH and ZCu sites in Cu-SSZ-13 – Implications for hydrothermal aging

Temperature and ammonia (NH3) pressure dependent surface coverage of Cu-amine complexes formed on Z2Cu, ZCuOH and ZCu sites in Cu-SSZ-13 are described using a kinetic model. Consistent with results from in-situ electron paramagnetic resonance (EPR) spectra upon NH3 solvation [47] and quantification from NH3 temperature programmed desorption (TPD) experiments [33], the model considers a maximum NH3/Cu ratio of 2 for Z2Cu sites, 1 for ZCuOH sites and 2 for ZCu sites. Experimentally determined Z2Cu and ZCuOH number densities are provided as initial inputs for the kinetic model, along with density functional theory (DFT) estimated NH3 binding energies [3]. These parameters are further modified to predict the rate of NH3 adsorption and desorption during TPD experiments on oxidized and reduced catalysts. Relative adsorption free energies of surface species based on equilibrium constants are consistent with the expected nature of NH3 solvated Cu sites. Relative mobility estimates based on the entropy of Cu-amine complexes are consistent with electrostatic considerations, first-principles calculations and observations from impedance spectroscopy [3,68,69]. Desorption pre-exponentials on CuII sites are validated via in-situ diffuse reflectance infrared fourier transform spectroscopic (DRIFTS) experiments during NH3 adsorption. The resulting kinetic model is incorporated into a formalism that combines all framework aluminum sites and treats mild hydrothermal aging as a reaction involving the transformation of ZCuOH sites to Z2Cu sites. NH3 storage at 200 °C on Cu sites increases upon reduction. Modifications to the NH3 coordination on Brønsted acid (ZH) sites in the reduced catalyst upon hydrothermal aging are predicted by the model and confirmed experimentally. Accurate predictions of the distribution of Z2Cu, ZCuOH and ZH sites as a function of catalyst aging, along with predictions of the extent of NH3 solvation of these sites is an important foundation to enable quantitative descriptions of the changes in the oxidation state and SCR redox reaction rates during real-world aging.

Inelastic Neutron Scattering Observation of Plasma-Promoted Nitrogen Reduction Intermediates on Ni/γ-Al2O3

Plasma-assisted catalysis is an emerging technology for the atmospheric pressure and low bulk gas temperature synthesis of ammonia from molecular nitrogen and hydrogen. Direct evidence for plasma-i...

Design and Analysis of Novel Co2 Conditioning Processes in the 3d Project

In this work, CO2 conditioning processes for ship-based CCS chain are modelled using simulation software APSEN HYSYS. The case study uses the captured CO2 gas from the 3D project as the feed. The feed gas is saturated with water and contains H2S and CO as impurities. The purification processes for dehydration, desulfurization and CO removal are reviewed. Two liquefaction approaches, open cycle liquefaction and closed cycle liquefaction, are modelled and compared for transport pressure 7 bar and 15 bar. It is found that the energy requirement of the open cycle liquefaction process is higher than that of the closed cycle liquefaction process. For the closed cycle liquefaction, two refrigerants: ammonia and propane are considered. Results show that the energy requirement of the process using ammonia is lower than the process using propane. When comparing the two transport pressures it is found that liquefaction at 15 bar requires less energy than 7 bar. On top of that, both refrigerants are unsuited for the liquefaction of CO2 at 7 bar as their operating pressures are below 1 atm. Several optimization methods are tested on the closed cycle liquefaction design. The net power consumption of the closes cycle liquefaction is reduced after utilizing intermediate pressure ammonia cold from CO stripper for pre-cooling.

Анализ влияния факторов неопределенности на математическое моделирование процесса сжатия аммиака в области влажного пара

The paper presents the influence analysis of such uncertainty factors as the heat transfer coefficient calculation method and the working chamber wall temperature on the mathematical modeling of the ammonia compression in a reciprocating compressor stage during the condensation of ammonia vapors. The mathematical model is based on the equation of the first law of thermodynamics for bodies with variable mass, the equation of state for real gases, the Clausius–Clapeyron and Newton–Richman equations. When determining the heat transfer coefficient value, several well-known dependencies for calculating these coefficients for dropwise and filmwise condensation have been considered. The calculation data shows that the instantaneous values of the ammonia pressure and temperature, as well as of the dryness fraction during compression in the wet steam region, significantly depends on the chosen method for calculating the heat transfer coefficient. Moreover, the walls temperature value of the compressor working chamber, where the compression occurs, has a considerable impact on the process under discussion. They are the determining factors and require special attention when the ammonia compression process is mathematically modelled in a reciprocating compressor stage, taking into account its vapors condensation.

Finite Element Analysis of Liquefied Ammonia Tank for Mobility Vehicles Employing Polymers and Composites

Hydrogen has attracted global attention as a clean secondary energy source and has numerous possible applications, including fuel for vehicles. To store the hydrogen effectively, ammonia is considered promising due to high hydrogen density, stability, and total energy efficiency. Adopting ammonia as a fuel in vehicles requires a proper fuel tank design to fulfill the required volumetric content and safety standards, without neglecting the economic objectives. In general, a type-IV pressure vessel is utilized as a fuel tank because it is the lightest one, compared to other types of pressure vessel. This paper focuses on the effort to develop a lightweight type-IV ammonia pressure vessel designed for mobility vehicles. The material combination (liner and composite) and composite stacking sequence are analyzed for both burst and impact tests by using a finite element method. Two polymer materials of polyethylene terephthalate (PET) and polypropylene (PP) are evaluated as the liner considering their ultimate tensile strength, density, cost, and compatibility with ammonia, while carbon-fiber-reinforced polymer (CFRP) and glass-fiber-reinforced polymer (GFRP) are adopted as composite skins. In addition, five composite stacking sequences are analyzed in this study. Von Mises stress and Hashin’s damage initiation criteria are used to evaluate the performance of liner and composite, respectively. As the results, PP-based pressure vessels generate lower stress in the liner compared to PET-based vessels. In addition, CFRP-based pressure vessels have a higher safety margin and are able to generate lower stress in the liner and lower damage initiation criteria in the composite skin. The material combination of PP-CFRP with a stacking sequence of [90/±30/90]3s gives the lowest maximum stress in the liner during the burst test, while, for the impact test, the stacking sequence of [90/±θ/90]3s is considered the most appropriate option to realize a lower stress at the liner, although this tendency is relatively small for vessels with PP liner.

Demonstrating the Direct Relationship between Hydrogen Evolution Reaction and Catalyst Deactivation in Synthetic Fe Nitrogenases

Synthetic Fe nitrogenases are promising catalysts for atmospheric pressure ammonia synthesis. However, their catalytic efficiency is severely limited by the accompanying hydrogen evolution reaction...

A study effects of injection pressure and wall temperature on the mixing process of NOx and NH3 in Selective Catalytic Reduction system

Diesel engines are commonly used for public transportation on-road and off-road applications. Growth production of the diesel engine is very significant from year to year. Nitride Oxide (NOx) from diesel engine was one of the major sources of air pollution. Selective Catalytic Reduction (SCR) has been successfully used to reduce NOx from a diesel engine with a chemical reaction from ammonia (NH3). The mixing reaction between NOx and NH3 reaction can produce steam (H2O) and Nitrogen (N2). However, ammonia uniformity pattern usually not homogenization and the ammonia was difficult to mix with NOx. The constant air flows incomplete to assist the spray injector to spread NH3 to all corners of SCR. The impact study of turbulent phenomena and standard k-epsilon Low-Reynolds Number model to the mixing process in the SCR system using STARCCM+. The simulation studies are conducted under different pressure (4 to 6 bars), the injection rate (0.04 g/s) and temperature (338 K – 553 K) and the high pressure and high velocity magnitude creating turbulent swirl flow. The ammonia decomposition process and mixing process with NOx were investigated using a box with optical access. The simulation and numerical study results validated using back pressure value and the distribution of NOx concentration value from the catalyst outlet. The wall temperature will increase the urea evaporation to generate ammonia and gas pressure will increase the mixing process and chemical process in the SCR system. These reactions enable to optimize the SCR system technology which eventually able to reduce the NOx quantity from a diesel engine.

Effect of Preliminary Alkali Desilication on Ammonia Pressure Leaching of Low-Grade Copper–Silver Concentrate

Ammonia leaching is a promising method for processing low-grade copper ores, especially those containing large amounts of oxidized copper. In this paper, we study the effect of Si-containing minerals on the kinetics of Cu and Ag leaching from low-grade copper concentrates. The results of experiments on the pressure leaching of the initial copper concentrate in an ammonium/ammonium-carbonate solution with oxygen as an oxidizing agent are in good agreement with the shrinking core model in the intra-diffusion mode: in this case, the activation energies were 53.50 kJ/mol for Cu and 90.35 kJ/mol for Ag. Energy-dispersive X-ray spectroscopy analysis (EDX) analysis showed that reagent diffusion to Cu-bearing minerals can be limited by aluminosilicate minerals of the gangue. The recovery rate for copper and silver increases significantly after a preliminary alkaline desilication of the concentrate, and the new shrinking core model is the most adequate, showing that the process is limited by diffusion through the product layer and interfacial diffusion. The activation energy of the process increases to 86.76 kJ/mol for Cu and 92.15 kJ/mol for Ag. Using the time-to-a-given-fraction method, it has been shown that a high activation energy is required in the later stages of the process, when the most resistant sulfide minerals of copper and silver apparently remain.

Thermodynamic assessment of chemical looping combustion and solar thermal methane cracking-based integrated system for green ammonia production

To attain sustainability, effective use of resources became a basic need for new energy systems. The present study considers a novel integrated system for greener ammonia synthesis using hydrogen produced from solar thermal cracking of methane. The system utilizes chemical looping combustion for the production of electricity with the advantage of carbon capture. The first law and second law analysis of the subsystems and overall system provide deep insights into the performance of the proposed system. The effects of various parameters such as reference temperature, air reactor temperature, ammonia reaction temperature and pressure on energy and exergy efficiencies of component and overall system are analyzed. Overall system energy and exergy efficiencies of 28.8% and 25.8%, respectively are obtained, whereas the subsystems are also found to have energy efficiencies ranging between 18.8 and 42.9%. The highest exergy destruction rate of 20.9 MW is observed for solar thermal cracking. The proposed system can help in the mitigation of carbon emissions accounted for the production of ammonia.

Removal of Hydrogen Poisoning by Electrostatically Polar MgO Support for Low-Pressure NH3 Synthesis at a High Rate over the Ru Catalyst

The increasing availability of low-cost and low pressure, renewable H2 from wind and solar means has triggered tremendous interest in developing low pressure ammonia synthesis with N2 as energy car...