Steam Rate Research Articles

Upcycling of medical protective clothing for H2 production through catalytic steam reforming over Ni-impregnated catalysts

Disposing medical protective clothing (MPC) presents a significant challenge due to the potential risk of virus contamination. Catalytic steam reforming using Ni-impregnated catalysts was proposed to upcycle MPC for H2-rich gas production. Parametric studies validated that an optimal steam rate of 42 mL/h and a catalytic reforming temperature of 800 ℃ were ideal for H2-rich gas production. 10 wt% Ni impregnated on diverse supports (HY, ZSM-5, MCM-41, γ-Al2O3, MgO, CaO, and activated carbon) were prepared for steam reforming of MPC to assess the impact of support type on H2 production. Of these Ni-impregnated catalysts, Ni/CaO was found to present the highest gas yield (141.4 mmol/g) with a high H2 proportion of 65.2 vol%, due to its superior catalytic cracking and reforming ability of Ni/CaO, favoring the conversion of MPC intermediates into H2-rich gas. To evaluate the recyclability and reforming activity, the optimized Ni/CaO with and without catalyst regeneration was evaluated throughout the successive tests. It was found that Ni/CaO regenerated throughout the successive tests could more effectively mitigate the decreasing tendency of gas yields, favor H2 production, and reduce tar formation than the catalyst without regeneration. That was due to the removal of carbon deposition by catalyst regeneration, thereby mitigating the catalyst deactivation. In contrast, Ni/CaO without the catalyst regeneration was more responsible for the CO2 reduction, accompanying with a more significant decrease of ƞ (4.8 – 3.5 g CO2 /g H2). Overall, this study demonstrated the feasibility of valorizing medical plastic waste into H2-rich gas using effective Ni-based catalysts.

Energy lost study for the steam and solvent assisted gravity drainage process, using reservoirs with Brazilian northeast characteristics

In Brazil, especially in the Northeast, there are still reservoirs containing heavy oils that are being operated by smaller companies that need to produce the fields, reducing production costs. There are different processes to recover heavy oil, one of which is steam and solvent assisted gravity drainage process, which uses two parallel horizontal wells, where the injector is placed above the producer. In this process, a solvent can be used with the steam, to try to reduce the steam rate injected. Process is carried out by injecting a hydrocarbon additive in low concentration together with steam. Steam contributes with the heat to reduce oil viscosity and solvent helps with miscibility, reducing the interfacial tension. The main force acting in this process is gravitational. The mobility of the displaced fluid is then improved, which may imply at an increase of oil recovery. In this study, a semi-synthetic model was analyzed, with average characteristics of the Brazilian northeast, where there is heavy oil in onshore reservoirs. Several simulations were carried out using a commercial oil reservoir thermal simulation software, where the influence of some operational parameters on oil recovery and energy in the reservoir were verified. The main objective of this study was to find a distance between producer and injector wells that allows reducing heat losses to the overburden and underburden when solvent and steam are injected into the process. It was found an optimal vertical distance to improve oil recovery.

ANALISIS LAJU UAP OLEH BOILER DENGAN KAPASITAS 9 LITER AIR DAN 10KG SAMPAH ORGANIK PADA PLTSa

The island of Bali is geographically surrounded by the ocean, therefore its coastal areas are often visited by garbage coming from the sea. Garbage is one of the most serious problems in the coastal areas of the beaches on the island of Bali, Biaung Beach located in Kesiman Kertalangu Village, East Denpasar is one of the beaches that is often visited by garbage from the sea, where the garbage per day reaches 38 kg / day. The purpose of this study was to determine the steam pressure generated by a boiler with a capacity of 9 liters of water and 10 kg of organic waste in a Waste Power Plant (PLTSa). The descriptive quantitative method used in this study is to determine the steam rate coming out of the boiler with 53.26% organic waste moisture content in the PLTSa Prototype using a 13.6 kilogram freon tube and 3 bar vapor pressure, a power of 209 watts is obtained.

Analysis of Combustion Characteristics in Boilers Using Comparison of Coal Fuel Mixtures and Bark Biomass To Determine Optimal Combustion Conditions in a Steam Power Plant

Currently, several material production industries have used self-sustaining power generation systems. Where the most common steam power plant system is found as an option to be used as a source of electricity. The use of biomass as an additional material for fuel in power plant has been widely carried out. This method is more commonly known as cofiring. Analysis of the cofiring combustion system of biomass in the boiler needs to be carried out in order to determine the characteristics of the combustion system that occurs. By varying the composition of the fuel, an analysis of the energy produced from the combustion reaction will be calculated. In this study, the comparison of the use of coal and wood bark was varied at conditions 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80. Assuming that the steam rate and temperature conditions to be achieved from the combustion products are constant. From the results of the analysis it was found that an increase in the amount of cofiring bark resulted in a decrease in the heating value of the combustion reaction and an increase in fuel capacity. Thus, it can be concluded that the use of bark cofiring in boilers with a coal design is less effective because it will require additional energy to increase the fuel consumption rate and reduce combustion efficiency due to not achieving optimal combustion energy because the initial design combustion chamber capacity is fixed.

Performance analysis of a single-cylinder type steam turbine with a capacity of 3.5 mw using enthalpy drop method

The performance capability of the steam turbine under factory conditions will experience changes that can be caused by operating or environmental factors. Therefore, it is necessary to analyze the performance of the steam turbine during the actual condition so that it can be compared with the performance of the steam turbine from the manufacturer using mass and energy balance equations on HP heater #1 and deaerators and iteration methods. The research was conducted by looking at the phenomena that occur in the steam turbine using mathematical models and theories when the unit operates according to the heat balance design parameters. Feedwater flow from the calculation of the iteration method based on the equation of the water heater obtained a value of 17,961.58 kg/h. The performance steam turbine experienced a decrease in efficiency with a value for isentropic efficiency of 72.73% down 6.54% from the design value of 79.27% and thermal efficiency of 26.88% down 1.75% from the design value of 28.64%. Meanwhile, the steam rate value of 5.03 kg/kWh increased by 0.44 kg/kWh from the design value of 4.59 kg/kWh, and the turbine heat rate of 3198.83 kcal/kWh, an increase of 196.08 kcal/kWh from the design value of 3002.75 kcal/kWh.

Actor-critic reinforcement learning leads decision-making in energy systems optimization—steam injection optimization

Steam injection is a popular technique to enhance oil recovery in mature oil fields. However, the conventional approach of using a constant steam rate over an extended period can lead to sub-optimal performance due to the complex nature of the problem and reservoir heterogeneity. To address this issue, the Markov decision process can be employed to formulate the problem for reinforcement learning (RL) applications. The RL agent is trained to optimize the steam injection rate by interacting with a reservoir simulation model and receives rewards for each action. The agent’s policy and value functions are updated through continuous interaction with the environment until convergence is achieved, leading to a more efficient steam injection strategy for enhancing oil recovery. In this study, an actor-critic RL architecture was employed to train the agent to find the optimal strategy (i.e., policy). The environment was represented by a reservoir simulation model, and the agent’s actions were based on the observed state. The policy function gave a probability distribution of the actions that the agent could take, while the value function determined the expected yield for an agent starting from a given state. The agent interacted with the environment for several episodes until convergence was achieved. The improvement in net present value (NPV) achieved by the agent was a significant indication of the effectiveness of the RL-based approach. The NPV reflects the economic benefits of the optimized steam injection strategy. The agent was able to achieve this improvement by finding the optimal policies. One of the key advantages of the optimal policy was the decrease in total field heat losses. This is a critical factor in the efficiency of the steam injection process. Heat loss can reduce the efficiency of the process and lead to lower oil recovery rates. By minimizing heat loss, the agent was able to optimize the steam injection process and increase oil recovery rates. The optimal policy had four regions characterized by slight changes in a stable injection rate to increase the average reservoir pressure, increasing the injection rate to a maximum value, steeply decreasing the injection rate, and slightly changing the injection rate to maintain the average reservoir temperature. These regions reflect the different phases of the steam injection process and demonstrate the complexity of the problem. Overall, the results of this study demonstrate the effectiveness of RL in optimizing steam injection in mature oil fields. The use of RL can help address the complexity of the problem and improve the efficiency of the oil recovery process. This study provides a framework for future research in this area and highlights the potential of RL for addressing other complex problems in the energy industry.

Pilot test of water-lean solvent of 2-(ethylamino) ethanol, 1-methyl-2-pyrrolidinone, and water for post-combustion CO2 capture

Water-lean solvent for post-combustion CO2 capture is promising to significantly reduce regeneration energy. It hasn’t been put into commercial application due to unsolved challenges including water balance issue, increased viscosity, and high volatility. Even though numerous water-lean solvents were developed in laboratory, rare of them were tested in pilot scale. Water-lean solvent of 2-(ethylamino) ethanol (EMEA) dissolving into 1-methyl-2-pyrrolidinone (NMP) and water was tested in a CO2 capture pilot with flue gas rate of 280 m3/h. Effects of liquid/gas ratio and reboiler steam rate on CO2 removal efficiency, regeneration energy, lean/rich heat exchanger performance, and volatile amine emission were investigated. Water-lean EMEA achieved CO2 removal efficiency greater than 90 % and the lowest regeneration energy of 2.3 GJ/tCO2, which is 43 % lower than that of 5 M MEA. Water-lean EMEA showed significantly reduced latent heat, greater CO2 capacity, and lower reaction heat (secondary amino) than aqueous MEA and amine blends. It was found that water-lean EMEA regeneration in stripper had extremely lower lean loading (0.1–0.5 mol CO2/L) than aqueous MEA and amine blends, which enables a faster CO2 absorption rate in absorber and a greater CO2 capacity, but also causes larger volatile amine emission. Volatile amine emission after water wash was 110–380 mg/m3. 13C NMR spectrum suggested amine carbamate dominated CO2 absorption products. Due to that increased viscosity decreases heat transfer coefficient (h), lean/rich heat exchanger temperature difference (ΔT) for water-lean EMEA (6.5–7.5℃) was greater than MEA (3.5-5℃) and amine blends (5-6℃), yet smaller than biphasic solvent (8-9℃). A negative power (-0.614) function relation between h and viscosity was fitted and can be further used to normalize sensible heat.

Experimental investigation of heat transfer characteristics of steam generator with circular-ring turbulators

Heat transfer has been improved by creating turbulence in the fluid flow of heat exchangers through introducing various techniques. The present study investigated the heat transfer characteristics of steam generator with circular-ring tabulators with an inclination angle of 45° and a blocked ratio (BR) of 0.20 mm. The length ratios (LR) of 25%, 50%, 75% and 100%, pitch ratios (PR) of 1.0, 2.0, 3.0 and 4.0 and water flow rates of 12, 24 and 36 l/h were studied. The heat source used waste lubricating oil as fuel to produce steam. The results showed that the heat exchanger with circular-ring inserts provided a higher steam rate than that of a smooth tube by 6.88–10.35%, vapor quality (x) by 0.21–0.92, heat transfer by 1.27–1.55 times and the thermal efficiency by 0.46–0.68 depending on the PR, LR and FR. The optimum insert ratio was LR = 50% while 75% and 100% were not significantly different. The circular-ring inserts changed the flow behavior to turbulent flow. This increased the surface area, causing boundary layer interruptions leading to more heat exchange on the tube surface.

Reaction characteristics and lattice oxygen transformation mechanism of semi-coke chemical looping gasification with Fe2O3/CaSO4–Al2O3 oxygen carrier

Chemical looping gasification (CLG) provides a potential way for clean utilization of solid fuels with the innate CO2 separation and capture. Selection of suitable oxygen carrier and operating conditions in reactor are the key for fuels conversion. In this work, Fe2O3–Al2O3, CaSO4–Al2O3 and Fe2O3/CaSO4–Al2O3 oxygen carriers (OCs) were synthesized by impregnation method and innovatively applied in semi-coke chemical looping gasification (SCCLG) for syngas production. The reaction conditions (oxygen carrier types, temperature, steam addition amount) of oxygen carrier for syngas production were tested in a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The experimental results showed that syngas yield of SCCLG with Fe2O3/CaSO4–Al2O3 is more than that with Fe2O3–Al2O3 or CaSO4–Al2O3 OC at 1000 °C when O/C ratio is 1:1. Furthermore, the maximum syngas yield (CO + H2) reached 129.20 mL/g of Fe2O3/CaSO4–Al2O3 at the gasification temperature of 950 °C. Results showed that the optimum operating conditions are steam rate of 0.06 mL/min at 950 °C with O/C of 1:1. Finally, the reaction mechanism of SCCLG was proposed based on experimental methods combing with advanced analytical testing and density functional theory (DFT) calculations results, and it reveals that OC in SCCLG underwent the reduction processes of Fe2O3/CaSO4–Al2O3 to CaFeSO/CaO–Al2O3 and then to Fe/CaS–Al2O3, which can efficiently improve the sulfur escape of CaSO4 OC. The present study provides an efficient way for conversion and utilization of fossil fuels in energy and chemical industry fields.

Response surface modelling of biomass-rich municipal solid waste pyrolysis: towards optimum hydrogen production

In this study, two-step pyrolysis of biomass-rich municipal solid waste was studied on nickel supported ZSM-5 catalyst. In the first stage of the reactor, constant temperature (T = 550 °C) was applied, and in the second stage, the reactions took place at 500, 700 and 850 °C. Effects of operating parameters (temperature = 500, 700, 850 °C, steam rate = 1, 5 g/h) and catalyst load (0.5, 1.0, 2.0) were studied on yields and compositions, particularly on the hydrogen contents. In order to determine the significance of the operating parameters, response surface methodology was used. Considering the experimental data, the values of hydrogen/carbon monoxide molar ratio, lower heating value and the simulation, it was found that the favourable operating parameters of two-step pyrolysis of biomass-rich municipal solid waste were 850 °C temperature and 1 g/h steam rate (gas yield: 27.1%, hydrogen yield: 9.96 mmol g−1 waste, hydrogen/carbon monoxide molar ratio: 1.8). From the data of response surface methodology, it was also concluded that temperature has a more critical effect on gas yields and composition than steam rate. However, in some cases, the synergistic effect of the two factors can also be significant.Graphical abstract

Activated carbon from hydrolysis lignin: Effect of activation method on carbon properties

This study presents the effects of different activation methods to produce activated carbon from the hydrolysis lignin. Pretreatment of the feedstock with common mineral acids (HCL, HNO3, and H3PO4), different steam rates for physical activation, and different chemical activating agents (ZnCl2, Na2CO3, and KOH) for chemical activation were investigated. The pretreated biomass was carbonized and activated in one-stage process and the surface characteristics, such as total pore volume, pore size distribution and specific surface area, were investigated. The results showed that the activated carbon surface properties were not greatly affected by acid pretreatment. Brunauer-Emmett-Teller (BET) surface areas as high as 616 m2/g could be achieved with physical activation and 2054 m2/g with chemical activation. Different steam rates in the selected interval (0.5–2 cm3/min) did not change the pore size distribution but had small positive effect on the specific surface area, while chemical activation with ZnCl2 increased the mesoporosity, and activation with KOH increased the microporosity and oxygen groups in the form of ether and alcohol bonds.

Cyclic In-Situ Combustion Process for Improved Heavy Oil Recovery after Cyclic Steam Stimulation

Summary Cyclic in-situ combustion (ISC) is a novel process with great potential for thermal enhanced oil recovery (EOR). In this study, a 3D physical simulation experiment of cyclic ISC after cyclic steam stimulation (CSS) was carried out for the first time. The mass loss during heavy oil oxidation was studied by thermogravimetry (TG) and the preheating temperature of sandpack was determined by differential scanning calorimeter (DSC). The oxidation process of heavy oil in a porous medium was investigated by a heavy oil static oxidation experiment. The development characteristics and EOR mechanism of cyclic ISC after CSS were studied through 3D physical simulation experiments and the characteristics of the coking zone was studied by scanning electron microscope (SEM) and computed tomography (CT). The results of the thermal analysis indicate that three different regions were observed with increasing temperature: low-temperature oxidation zone (LTO), fuel deposition zone (FD), and high-temperature oxidation zone (HTO). When the temperature reaches 480°C, the mixed oil sand has the most exothermic effect and the high-temperature oxidation reaction is the most vigorous. The results of the 3D physical simulation show that steam channeling and steam overlay in CSS reduced the swept volume of steam and heat usage rate. During the cyclic ISC, the oil bank can overcome the heterogeneity of the oil reservoir caused by steam channeling and steam overlay, which makes the combustion front move forward smoothly. Cyclic ISC can greatly increase the temperature of the zone near the well, and upgrade the crude oil through cracking to reduce the viscosity of heavy oil. The foaming oil formed by the dissolution of flue gas improves the fluidity of the crude oil. The oil recovery of CSS is 19.3%, and the oil recovery of cyclic ISC increased by 13.2%. SEM and CT show that flake black solid coke was attached to the surface of the sand at the coking zone. The coking zone is a porous medium structure with a porosity of 35.14%, which has little effect on the oil recovery in the process of cyclic ISC.

Development of a waste‐to‐energy gasification system for sustainable communities

In this study, a geothermal energy-based integrated gasification combined cycle is incorporated with an anaerobic digestion unit to produce multiple useful commodities to create a circular economy for a sustainable community. This proposed system aims to utilize non-recyclable and unfavorable plastics, which leave material recovery facilities as a feedstock in the gasification unit to produce hydrogen, hydrogen sulfur, and electricity. Further energy is recovered in the heat recovery heat exchanger to meet the optimum temperature in the digesters where wastewater sludge is utilized to generate biogas and lower-grade compost for agricultural applications. The Durham Region in the Province of Ontario is selected to be the case location to meet the increased energy demand as a result of the growing population. Two software packages, namely Aspen Plus and Engineering Equation Solver, are used to completing the thermodynamic simulations and analyses for this system. Some parametric studies are also carried out to investigate its feasibility under different conditions and find the optimum working conditions for the integrated gasification combined cycle. Accordingly, gasification operating temperature, steam feed rate, oxygen feed rate, and carbon content in biomass are varied in both the integrated gasification combined cycle and anaerobic digestion facilities. In the proposed system, hydrogen-to-fuel and biogas-to-biomass ratios are observed to be 0.192 and 0.57, respectively, while the daily total energy delivered to the community from this integrated system is calculated to be 2.7 GWh. The overall energy and exergy efficiencies of the proposed waste management system at the chosen operating conditions are determined to be 28.1% and 30.2%, respectively. As a result of the dynamic simulations where the steam rate is varied in the gasification reactor, the energy and exergy efficiencies are determined to be 33.7% and 36.2% at the steam rate of 10 kg/s.

Long-term coal chemical looping gasification using a bimetallic oxygen carrier of natural hematite and copper ore

Coal chemical looping gasification (CCLG) is a promising gasification technology for coal utilization with high resource utilization rate, energy saving and environmental protection properties. Development of suitable oxygen carriers and optimization of operating conditions for CCLG are the key for the coal conversion and H2&CO production (H2, CO). In this study, Cu-Fe bi-ore oxygen carrier prepared by spray drying granulation method using hematite and copper ore as raw materials was tested for CCLG. The effects of the reaction temperature, oxygen carrier to coal (O/L) ratio and steam addition amounts were systematically evaluated by reaction tests combing with various analytical methods. Most importantly, over 100 redox chemical looping cycles were performed to demonstrate the excellent stability of Cu-Fe bi-ore oxygen carrier during the redox reactions. Results showed that the optimal gasification condition is 950 °C with oxygen carrier-to-coal mass ratio of 3:1 and steam rate of 0.08 ml/min. Syngas yield of 58 mmol/g, as well as 75.2% syngas selectivity and 85.3% carbon conversion were achieved. After 100 redox cycles, the synthesis gas yield can still reach 46 mmol/g despite a decline, and the carbon conversion kept above 72%, without obvious sintering in the long-term test. The characterization results showed that the synergistic effect between Cu and Fe metals contributed to its good oxygen release ability and reducibility. The Cu-Fe bi-ore oxygen carrier undergoes a gradual reduction Fe3+→Fe8/3+→Fe2+→Fe and Cu2+→Cu process during the gasification reaction, accompanying with the lattice oxygen migration from bulk to the particle surface. This work demonstrated the economical method for the industrial application of CCLG process using spray-drying-derived oxygen carriers.

Reduced graphene oxide/silver/wood as a salt-resistant photoabsorber in solar steam generation and a strong antibacterial agent

Interfacial solar steam generation (SSG) of seawater opens a novel scene to address water shortage and stress. In this work, reduced graphene oxide (RGO) and silver nanoparticles (NPs) were prepared, coated on poplar wood, and used as a single and double-layer photoabsorbers in SSG of seawater. The maximum evaporation rate per unit area of 5.99 kg m−2 s−1 and four orders of magnitude reduction in salinity were achieved under 3 sun (1 sun = kW m−2) for the optimum double-layer photoabsorber due to the synergistic effect of surface plasmon resonance phenomenon of Ag NPs and black color and the conjugated aromatic rings of RGO. The evaporation efficiency of the optimum photoabsorber did not change even after 11 cycles. The cost per produced steam rate was calculated as 0.011 $ cm−3 h. The antibacterial activity of the bare wood and the optimum double-layer photoabsorber against methicillin-resistant Staphylococcus aureus (MRSA) was also investigated in dark. The optimized photoabsorber had strong antibacterial activity so that the bacterial growth was totally inhibited during 24 h whereas it increased with time for bare wood.

Preparation of Ni-based steel slag catalyst by impregnation method for sludge steam gasification

In this study, a nickel (Ni)-based catalyst was loaded onto steel slag that was rich in metal oxides using impregnation method. The effects of the catalyst on hydrogen-rich gas produced using sludge steam gasification were discussed. Under the conditions of 900 ℃, steam flowrate of 1.5 g min−1 and 20% Ni-based loading rate, the gas and H2 yield reached 0.78 Nm3 kg−1 and 15.72 mol kg−1. At this time, the volume fraction of H2 was as high as 45.096%. Compared with the raw sludge gasification without Ni-based catalyst, the gas and H2 yield were increased by 39.22% and 60.15% respectively. However, excessive flowrate of steam (≥1.5 g min−1) and excessive rate of loading of Ni-based (≥25%) catalyst would lead to a decrease in the production of gas. In addition, the impregnation method could effectively disperse NiO particles on the surface of the support, increasing the ratio of active sites on the surface of catalyst and improving the catalytic activity. These characteristics indicated that the Ni-based steel slag catalysts prepared by the impregnation method had high application potential in the process of sludge steam gasification, and provided a novel idea for solid wastes recycling.

Analisis Pengaruh Turbine Washing Terhadap Efisiensi dan Daya Pembangkit Turbin Uap

The steam turbine is one of the main components in the Geothermal Power Plant which acts as the prime mover is used to convert heat energy in steam into rotation energy. At PLTP X, steam is used to drive the turbine is in saturation conditions. The principle of the steam turbine is dry steam plant cycle. From July to August, it was known that there have been several decreases in generating power at Unit 2 at PLTP X. The efforts that can be done to overcome this problem is by turbine washing. This study aims to compare the performance of steam turbines based on thermal efficiency, isentropic efficiency and steam turbine generator power before and after turbine washing from the calculation results based on CEI/IEC 953-1, CEI/IEC 60953-3 and ASME PTC 6-2004 standards using the actual steam system operating parameter data collection, interviews and analysis. So that it gets an average increase in isentropic efficiency of 0,0564 %, thermal efficiency of 0,0082 %, the actual power generation of steam turbine is 162,72 kW and the largest power generation reaches 54.500 kW after the turbine washing steam rate of 7,5963 kg/kWh and the turbine heat rate of 3.607,3453 kJ/kWh.

Clean water production by non-noble metal/reduced graphene oxide nanocomposite coated on wood: Scalable interfacial solar steam generation and heavy metal sorption

Herein, a cost-effective, bifunctional, scalable, and highly efficient water-treatment material was prepared by coating iron/nickle (Fe/Ni)-reduced graphene oxide (RGO) nanocomposite on poplar wood which was used both as non-noble metal based photoabsorber in interfacial solar steam generation of seawater and as highly efficient heavy metal sorbent. The solar evaporation fluxes of 1.43 and 4.19 kg m−2h−1 under 1 and 3 sun (1 sun = 1 kW m−2), respectively were achieved by the most efficient photoabsorber (RGO200/FeNi-wood). The evaporation efficiency of the photoabsorber did not change significantly even after 20 cycles. After desalination by RGO200/FeNi-wood, a remarkable reduction in the salinity (4 order of magnitude), pH (8.1 to 6.2), and electrical conductivity (6000 to 2.25 µScm−1) was achieved. The cost per produced steam rate was calculated as 0.03 $ cm−3h under 3 sun which is comparable to the best double-layer devices reported in the literature. RGO200/FeNi-wood could act as a novel sorbent to remove Pb (II) completely from aqueous solutions.

Highly efficient solar desalination and wastewater treatment by economical wood-based double-layer photoabsorbers

Design of rational photoabsorbers is a promising approach to produce drinking water. Herein, a highly efficient and scalable wood-based photoabsorber device composed of poplar wood as a substrate coated with FeNi with mole ratio of Fe/Ni = 85% and reduced graphene oxide (RGO) as top and bottom layers, respectively was designed for the interfacial solar desalination of seawater and heavy metal removal as a sorbent. Benefiting from high sunlight utilization and rapid water transport, high photothermal conversion fluxes of 1.50 and 4.77 kg m−2h−1 were achieved by the most efficient double-layer photoabsorber of W/FeNi4∙5RGO4∙5 (wood coated with 4.5 g L−1 of FeNi as a top layer and 4.5 g L−1 of RGO as a bottom layer) under 1 and 3 sun, respectively (1 sun = 1 kW m−2). Also, a significant reduction in the salinity (four orders of magnitude), the electrical conductivity (3000 times) and the pH (1.35 times) of the seawater was achieved after 40 min solar desalination. The ratio of produced steam rate per cost was calculated as 9 cm3 h−1 $−1 which is compared with other double-layer devices reported in the literature. In addition, W/FeNi4∙5RGO4∙5 acted as an excellent sorbent for Pb (II).

Development of a sustainable community with an integrated renewable and waste to energy system for multiple useful outputs

In this study, a solar energy-based integrated gasification system is designed to produce multiple useful commodities, such as hydrogen, biogas, freshwater, domestic hot water, and power, for a sustainable community. The COVID-19 pandemic has clearly shown society the importance of renewable energy systems and proper waste management systems. In this developed system, shredded waste tires are used to produce energy in the form of hydrogen and the syngas produced at the gasification unit is further utilized for the steam Rankine cycle, and this will be replaced with forward multi-effect desalination unit to produce useful outputs. This hybrid system is also incorporated with integrated anaerobic digestion and composting units to create a circular economy unlike traditional systems. This proposed system is thermodynamically analyzed and dynamically simulated by investigating the effect of dynamic solar intensities throughout the months in a year. Furthermore, the gasification products are analyzed by altering the steam and oxygen feed rate within the system. This system utilizes closed landfills with a renewable energy system, solar tower cycle, to produce energy and steam. This steam is then further utilized at the gasification unit as a gasification agent to increase hydrogen production. The total electricity and freshwater produced within this integrated system is calculated to be 163 MW/h and 2.16 tonnes during its operation in a day. In addition, the hydrogen to fuel ratio at the gasifier and the hourly methane production at the anaerobic digestion unit are found to be 0.175 and 309 m3/h, respectively. The overall energy and exergy efficiencies of this proposed system are observed to be 74% and 73%, respectively.