Ammonia Production System Research Articles

Low carbon collaborative planning of integrated hydrogen-ammonia system and power distribution network

The conversion of renewable energy into chemical energy carriers, such as ammonia, enhances the accommodation of renewable energy for power distribution networks (PDN) and supports the decarbonization for ammonia production systems (APS). This paper addresses the integration of PDN with APS through a collaborative planning considering a carbon emission flow (CEF) model. A collaborative planning model with carbon emissions constraints is designed, and a sensitivity analysis is performed to evaluate the impact of varying renewable energy costs on the system. To further reduce carbon emissions from green ammonia production and stabilize renewable energy volatility, a nodal CEF model that incorporates energy storage systems (ESS), wind turbines (WT), and photovoltaics (PV) is proposed. The economic feasibility of the proposed model is verified via comprehensive experiments. Numerical results show that collaborative scheduling reduces both costs and carbon emissions in PDN and APS. Implementing a carbon tax encourages the transition from grey to blue ammonia production, while a decrease in renewable energy costs further promotes the shift from blue to green ammonia. Besides this, the analysis indicates that integrating long-term operation of WT and PV, together with low-cost renewable electricity and ESS, boosts the economic efficiency of the green ammonia production system.

Waste heat recovery from a green ammonia production plant by Kalina and vapour absorption refrigeration cycles: A comparative energy, exergy, environmental and economic analysis

The production of green ammonia involves significant energy penalties due to heat losses. Recovering this heat can enhance the sustainability of ammonia production. However, this area remains largely unexplored, making it unclear which approach to waste heat recovery is best suited. Therefore, this paper investigates two methods of waste heat recovery in a green ammonia production plant: the Kalina Cycle (KC) and the Vapour Absorption Refrigeration Cycle (VARC). The underlying processes are simulated, and an analysis is conducted covering energy, exergy, environmental, and economic aspects. The results show that integrating the system with KC yields a marginal energy efficiency improvement of about 1%. However, when the conventional ammonia production system is integrated with VARC, the improvement in energy efficiency reaches 8%, while exergy efficiency improves by 11%. An environmental assessment estimates the greenhouse gas emissions saved by each heat recovery method, revealing that VARC achieves almost four times the emission savings compared to KC. Economically, integrating KC increases the levelized cost of ammonia (LCOA) by over 18%, whereas adding VARC has almost no impact on the LCOA. Overall, the co-production of refrigeration using VARC is identified as a superior heat recovery technique for green ammonia plants.

Process optimization, exergy analysis, and GHG emissions of ammonia production systems by gasification of high-sulfur petroleum coke with CO2 capture

High-sulfur petroleum coke is commonly used as a fuel because of its high carbon content and calorific value. Direct combustion of high-sulfur petroleum coke has the problem of emitting a lot of CO2 and sulfide. Gasification is an environmentally friendly way to utilize high-sulfur petroleum coke. Therefore, this study first established hydrogen production systems with CO2 capture through high-sulfur petroleum coke gasification. The hydrogen is then reacted with nitrogen from air separation unit for producing ammonia, which is easy to transport and store. After optimizing and analyzing the key parameters of the established models, exergy and life cycle GHG emissions analysis are carried out to evaluate the technical performance and environmental impact. In the system with an 85 % gasification conversion rate of petroleum coke, the ammonia production capacity, exergy efficiency, and GHG emissions are 2300 kmol/h, 45.39 %, and 1468 kg CO2-eq/t NH3. When the conversion rate is elevated by ten percentage points, the ammonia production and exergy efficiency are increased to 2664 kmol/h and 51.95 %, while the GHG emissions are only reduced by 85 kg CO2-eq/t NH3 since most of the CO2 produced by the system is captured. Improving the petroleum coke conversion rate can significantly increase the exergy efficiency of ammonia production system, but has little impact on reducing GHG emissions during the process.

Achieving Decentralized, Electrified, and Decarbonized Ammonia Production.

The rapid reduction in the cost of renewable energy has motivated the transition from carbon-intensive chemical manufacturing to renewable, electrified, and decarbonized technologies. Although electrified chemical manufacturing technologies differ greatly, the feasibility of each electrified approach is largely related to the energy efficiency and capital cost of the system. Here, we examine the feasibility of ammonia production systems driven by wind and photovoltaic energy. We identify the optimal regions where wind and photovoltaic electricity production may be able to meet the local demand for ammonia-based fertilizers and set technology targets for electrified ammonia production. To compete with the methane-fed Haber-Bosch process, electrified ammonia production must reach energy efficiencies of above 20% for high natural gas prices and 70% for low natural gas prices. To account for growing concerns regarding access to water, geospatial optimization considers water stress caused by new ammonia facilities, and recommendations ensure that the identified regions do not experience an increase in water stress. Reducing water stress by 99% increases costs by only 1.4%. Furthermore, a movement toward a more decentralized ammonia supply chain driven by wind and photovoltaic electricity can reduce the transportation distance for ammonia by up to 76% while increasing production costs by 18%.

Research on design and multi-frequency scheduling optimization method for flexible green ammonia system

As an important chemical product and energy carrier, green ammonia is a way to consume large quantities of green hydrogen produced from renewable electricity. For the optimization of the green ammonia production systems, a primary problem is to solve the electricity-hydrogen-ammonia matching problem under multi-frequency and multi-amplitude load fluctuations. In this work, a method for capacity designing and scheduling optimization of a hybrid multi-frequency flexible green ammonia system is constructed. The method can be applied to design the whole green ammonia system in grid-connected and isolated scenarios. The established model can accurately describe the electricity-hydrogen-ammonia matching characteristics of each module. Furthermore, many important practical engineering constraints are taken into account, such as the operating time of the chemical device, and the flexibility of the ammonia device. This work verifies the effectiveness of the proposed method based on a real case, and the impact of load range, adjustment speed, and adjustment frequency of the ammonia synthesis process on the product cost and module capacity.

Techno-economic comparison of ammonia production processes under various carbon tax scenarios for the economic transition from grey to blue ammonia

Ammonia synthesis is a carbon-intensive process, with significant volumes of carbon dioxide produced during the preliminary production of hydrogen from a fossil fuel feedstock. Since carbon emissions vary significantly depending on the hydrogen production method, the impact of carbon capture and storage (CCS) implementation on the overall economic performance of the ammonia synthesis process differs. Therefore, it is crucial to (1) integrate cost-effective CCS into various ammonia synthesis processes and (2) conduct a comprehensive comparison of grey and blue ammonia systems together, considering the economic costs of the carbon emissions. This study aims to investigate the economic feasibility of large-scale ammonia processes under various carbon tax scenarios and suggest carbon-efficient options for the ammonia industry. Three ammonia synthesis processes are designed that differ in their hydrogen production method – steam methane reforming (SMR), autothermal reforming (ATR), and hybrid SMR-ATR – and these three options also have grey ammonia and blue ammonia production versions. The grey ammonia production systems do not include a carbon capture procedure, while the blue ammonia systems ensure that the CO2 emissions are below 0.065 t CO2/t NH3. In the present study, both the grey and blue versions of the three ammonia production processes are subjected to techno-economic evaluation under various carbon tax scenarios. For the grey ammonia systems, economic feasibility varies depending on the carbon tax scenario under consideration. Grey ATR becomes the most cost-effective option within a carbon tax of 95 $/ton to 115 $/ton. In contrast, the economic viability of the blue ammonia systems is unaffected by the carbon tax policy environment. In particular, blue ATR exhibits 6% and 14% lower levelized cost of ammonia (LCOA) compared to the blue SMR and blue Hybrid SMR-ATR, respectively. Overall, the results indicate that, below a carbon tax threshold of 62 $/ton, the SMR process without carbon capture is economically favorable. However, for carbon tax above 62 $/ton, the ATR process with carbon capture has greater economic feasibility than other options. A minimum carbon tax of 62 $/ton is required to promote the transition to blue ammonia. These findings thus provide valuable insight into the establishment of effective carbon regulations in response to the global demand to tackle the climate crisis.

Modeling and simulation of dynamic characteristics of a green ammonia synthesis system

Green ammonia production system driven by renewable electricity will be under frequent dynamic operation due to the fluctuation of renewable energy. The nonlinear dynamic model of a green ammonia synthesis system is developed and the dynamic responses of PEM (proton exchange membrane) electrolysis subsystem, PSA (Pressure swing adsorption) subsystem and ammonia synthesis subsystem during the start-up process and under the fluctuation of renewable electrical current are analyzed. The start-up dynamic results show that the hydrogen production rate of PEM electrolysis system is positively correlated to the current. The nitrogen output of PSA system is affected by the adsorption time, adsorption pressure, bed length, and air velocity. A start-up period of 300 min from the warmed-up state to the design state can maintain the temperature rise rate of the ammonia synthesis reactor at approximately 40 K/h. The dynamic results under step fluctuations of electrical current show that the PEM electrolysis subsystem and the PSA subsystem response fast compared to the ammonia synthesis reactor and buffer tanks. Using large buffer tanks to smooth the fluctuation allows the system to slide with the variation of renewable current to some extent, resulting in a higher outlet ammonia fraction when the current increases. Different volume ratios of the hydrogen tank to the nitrogen tank volume can lead to different variations of the hydrogen/nitrogen ratio. PID controllers can effectively maintain the bed temperatures, hydrogen/nitrogen ratio, and pressure of the ammonia synthesis reactor at their set points despite fluctuations in renewable electrical current. Buffer tanks are necessary to compensate for the imbalance between the flow rate fluctuation caused by current change and the flow rate regulation caused by PID controllers.

Correlating the influence of the purity of hydrogen produced by a surplus power on the production of green ammonia

Abstract Carbon dioxide is the primary greenhouse gas contributing to climate change. Furthermore, due to the surplus power generated by renewable energy resources, various approaches have been developed to handle this overproduction. This study verifies via a correlation analysis the influence of the purity of hydrogen produced by a continuous surplus power on the sustainable ammonia production. The influence of the temperature and pressure of the hydrogen treatment system on the purity of the hydrogen gas produced in the alkaline water electrolysis system was investigated, where the purity increased with a decrease in temperature and an increase in pressure. The purity of the produced ammonia was positively correlated with the purity of hydrogen. Furthermore, the energy consumption of the ammonia production process increased when the purity of hydrogen was low. In the case of storing the surplus power as ammonia, the effect of hydrogen purity was less affected by the hydrogen production system than by the ammonia production system, and it was thus concluded that it is more desirable to determine the hydrogen purity in the hydrogen production system prior to employing it in the ammonia production system.

(Invited) Insights on Decentralized Electrochemical Reduction of Nitrate

Ammonia is a chemical commodity with demonstrated global importance given its clear food-energy-water nexus. Ammonia large-scale production relies on the Haber-Bosch process which employs hydrogen and nitrogen as reagents under high pressure (10 MPa) and high temperature (500 °C). This process is responsible for more than ~180 million tons of ammonia production per year to satisfy industrial and agricultural needs. Sustaining the ammonia production through the Haber-Bosch process has a huge carbon footprint as sustainability toll. The Haber-Bosch process generates over 450 million tons of CO2 annually, which represents almost 1.5 % of global emissions per year. The fossil fuel reliance of this high energy demand process of ammonia synthesis defines the world economy in many ways. For instance, recent cost increase on ammonia production has had a direct impact on food price inflation worldwide. Ammonia shortage has different causes such as geopolitical conflicts around the world, and increased natural gas price, among others. Thus, a fossil fuel-free green chemical synthesis alternative is required to alleviate the ammonia demand while diminishing the carbon footprint.Agriculture is strongly dependent on ammonia-based fertilizers generating a nitrogen-imbalance in the environment due to N-species (e.g., NO3 -, NO2 -, NH4 +) runoff to ground and surface water. Among these N-species, high concentrations of nitrate and nitrite are highlighted as frequent water quality violations in the US. Concentrations way above the regulated maximum contaminant levels (MCL) of 10 mg L-1 for NO3 --N and 1 mg L-1 for NO2 --N are commonly found in many water resources. Implementation of electrochemical reduction of nitrate (ERN) to produce ammonia can address environmental pollution while producing ammonia under mild conditions with less carbon footprint. The ERN process can become a decentralized ammonia production system alleviating needs at small and even medium scale production. Selectively reducing nitrate towards ammonia has gained attention due to several advantages respect to direct N2 gas reduction such as higher solubility and lower energy barrier. This electrochemically driven process can be coupled with renewable energy systems and therefore holds the promise to enable fossil-free ammonia production off-grid.The mechanisms for electrochemical conversion of nitrate to nitrogen gas are highly complex, involving numerous reactions, products and stable intermediates (e.g., ammonia, nitrite, hydrazine, hydroxylamine, nitric oxide, nitrous oxide) spanning the many nitrogen oxidation states (from -III up to +V). Controlling the reaction selectivity of a complex mechanisms that involve different charge transfer and chemical reactions (e.g., hydrogenation) is challenging. This invited presentation aims to showcase some of the advances in terms of electrode engineering design to steer selectivity towards ammonia production as well as some of the challenges that will be faced when translating lessons learnt towards application under real environmental samples.

Energy-Efficient and Self-Powered Green Ammonia Synthesis by Electrochemical Nitrate Reduction Combined with Hydrazine Oxidation.

To achieve the global goal of carbon neutrality, recently, emphasis has been placed on developing green ammonia production method to replace the Haber-Bosch process. Nitrate reduction reaction (NO3 RR) has received considerable attention, especially for electrochemically producing ammonia from nitrate and simultaneously purifying wastewater. This study first demonstrates that the combination of NO3 RR with hydrazine oxidation reaction (HzOR) is an energy efficient green ammonia production method, which overcomes the sluggish water oxidation limitation. Tungsten phosphide (WP) nanowires (NWs) are prepared as cathode NO3 RR electrocatalysts, which exhibit a high Faradaic efficiency in both neutral (≈93%) and alkaline (≈85%) media. Furthermore, they show a high bifunctional activity in anodic reactions and exhibit a low potential 0.024V for generating a current density of 10mAcm-2 in HzOR. The overall NO3 RR-HzOR required an impressively low potential of 0.24V for generating a current density of 10mAcm-2 ; this potential is much lower than those required for NO3 RR-OER (1.53V) and NO3 RR-UOR (1.31V). A self-powered ammonia production system, prepared by assembling an NO3 RR-HzOR with a perovskite solar cell, displays a high ammonia production rate of 1.44mgcm-2 h-1 . A single PV cell provides enough driving voltage in the PV-EC due to low required potential. This system facilitates unassisted green ammonia synthesis with a low energy consumption and also allows upcycling of wastewater to produce useful fuel.

Transient modeling of a green ammonia production system to support sustainable development

Wind power intermittency makes it imperative to conduct transient modeling to highlight and address the challenges related to longer-term dynamics prior to demonstration projects. This paper presents the transient modeling and simulation of offshore wind energy integrated with a “green hydrogen” and “green ammonia” synthesis system. Since the transmission of electricity produced from far offshore sites to onshore points is challenging and submarine power cables are a significant cost, a fully off-grid offshore location is proposed for green ammonia production (power-to-ammonia) in contrast to previous studies that have examined grid-tied approaches. This approach can utilize the massive unexploited potential of remote offshore locations where wind velocities and capacity factors are comparatively higher, with produced green ammonia transported to onshore demand points via pipelines or ships. The offshore wind energy can directly be converted into ammonia using water and air as input materials, starting with the generated wind power used in the water electrolysis system to split water into hydrogen and oxygen. Nitrogen is separated by an air separation unit and mixed with the hydrogen to produce ammonia through an all-electric ammonia synthesis system. The transient analysis results include ammonia production at each hour of the year and an integrated hydrogen storage system to buffer production for nominally steady ammonia ouput throughout the year. An economic analysis is also conducted that reveals offshore wind and electrolysis as the leading cost drivers.

Thermo-economic optimization of a novel hybrid structure for power generation and portable hydrogen and ammonia storage based on magnesium–chloride thermochemical process and liquefied natural gas cryogenic energy

Storage and transfer of hydrogen (H2) from production sites/plants to large-scale demanding industries are one of the most challenging obstacles to hydrogen adoption. Hydrogen liquefaction and its chemical storage in the form of ammonia (NH3) can be used for safe and economic transportation. High energy consumption and carbon dioxide (CO2) emissions to supply the utility of these systems can limit the production of liquid H2 and liquid NH3. Therefore, efficient design and practical strategies to store hydrogen at a large scale with minimal energy consumption and CO2 emissions are necessary. In this research, an innovative hybrid system for portable hydrogen storage and power generation with zero CO2 emission through liquefied natural gas (LNG) regasification is developed. The proposed structure includes a cryogenic air separation unit, magnesium–chloride hydrogen production process, ammonia production system, hydrogen liquefaction cycle, and Rankine/oxy-fuel power plants. The heat loss of the proposed structure is utilized to supply the required heat load for the thermo-electrochemical unit. The LNG regasification operation is utilized for pre-cooling the hydrogen liquefaction system and the necessary refrigeration of the air separation process and the final products. The developed structure is fed by 1883 kmol/h LNG, which is converted to 120 kmol/h liquid NH3, 180 kmol/h liquid H2, 924.5 liquid CO2, and 16.09 MW power. The thermal and exergy efficiencies for the designed system are 20.33% and 22.76%, respectively. The results of the exergy investigation reveal that the largest contribution of exergy destruction occurs in heat exchangers (31.27%), combustion chamber (34.65%), and turbines (8.12%). The economic evaluation indicates that the net annual profit, added value, and payback period are 15.93 US$/yr, 0.0779 US$/kWh, and 5.646 yr, respectively, based on the energy potential of Newfoundland and Labrador in Canada. Three-objective optimization approach using the combination of genetic algorithm and neural network exhibits that the energy efficiency and net annual profit based on the Bellman-Zadeh approach increase up to 27.04% and 45.20 US$/MMBTU, respectively, and the irreversibility reduces to 99.4 MW.

Optimising renewable generation configurations of off-grid green ammonia production systems considering Haber-Bosch flexibility

Green ammonia has received increasing interest for its potential as an energy carrier in the international trade of renewable power. This paper considers the factors that contribute to producing cost-competitive green ammonia from an exporter’s perspective. These factors include renewable resource quality across potential sites, operating modes for off-grid plants, and seasonal complementarity with trade buyers. The study applies a mixed-integer programming model and uses Australia as a case study because of its excellent solar and wind resources, and the potential for synergy between Southern Hemisphere supply and Northern Hemisphere demand. Although renewable resources are unevenly distributed across Australia and present distinct diurnal and seasonal variability, modelling shows that most of the pre-identified hydrogen hubs in each state and territory of Australia can produce cost-competitive green ammonia providing the electrolysis and Haber-Bosch processes are partially flexible to cope with the variability of renewables. Flexible operation reduces energy curtailment and leads to lower storage capacity requirements using batteries or hydrogen storage, which would otherwise increase system costs. In addition, an optimised combination of wind and solar can reduce the magnitude of storage required. Providing that a partially flexible Haber Bosch plant is commercially available, the modelling shows a levelised cost of ammonia (LCOA) of AU$756/tonne and AU$659/tonne in 2025 and 2030, respectively. Based on these results, green ammonia would be cost-competitive with grey ammonia in 2030, given a feedstock natural gas price higher than AU$14/MBtu. For green ammonia to be cost-competitive with grey ammonia, assuming a lower gas price of AU$6/MBtu, a carbon price would need to be in place of at least AU$123/tonne. Given that there is a greater demand for energy in winter concurrent with lower solar power production, there may be opportunities for solar-based Southern Hemisphere suppliers to supply the major industrial regions, most of which are located in the Northern Hemisphere.

Design and Analysis of an Offshore Wind Power to Ammonia Production System in Nova Scotia

Green ammonia has potential as a zero-emissions energy vector in applications such as energy storage, transmission and distribution, and zero-emissions transportation. Renewable energy such as offshore wind energy has been proposed to power its production. This paper designed and analyzed an on-land small-scale power-to-ammonia (P2A) production system with a target nominal output of 15 tonnes of ammonia per day, which will use an 8 MW offshore turbine system off the coast of Nova Scotia, Canada as the main power source. The P2A system consists of a reverse osmosis system, a proton exchange membrane (PEM) electrolyser, a hydrogen storage tank, a nitrogen generator, a set of compressors and heat exchangers, an autothermal Haber-Bosch reactor, and an ammonia storage tank. The system uses an electrical grid as a back-up for when the wind energy is insufficient as the process assumes a steady state. Two scenarios were analyzed with Scenario 1 producing a steady state of 15 tonnes of ammonia per day, and Scenario 2 being one that switched production rates whenever wind speeds were low to 55% the nominal capacity. The results show that the grid connected P2A system has significant emissions for both scenarios, which is larger than the traditional fossil-fuel based ammonia production, when using the grid in provinces like Nova Scotia, even if it is just a back-up during low wind power generation. The levelized cost of ammonia (LCOA) was calculated to be at least 2323 CAD tonne−1 for both scenarios which is not cost competitive in this small production scale. Scaling up the whole system, reducing the reliance on the electricity grid, increasing service life, and decreasing windfarm costs could reduce the LCOA and make this P2A process more cost competitive.

Stability Assessment of Small-Scale Distributed Ammonia Production Systems

Stability Assessment of Small-Scale Distributed Ammonia Production Systems

Design and modeling of an integrated combined plant with SOFC for hydrogen and ammonia generation

Because of the requirement of the utilization of energy resources in a way that is both effective and efficient, solid oxide fuel cells have become a notable preference due to their advantages such as high efficiency and use with different fuels. In addition, the integration of these systems in the production of alternative fuels such as hydrogen and ammonia are important for a sustainable future to combat environmental problems. For this reason, the main intention of this paper is to introduce a new plant combining the different systems that use the solid oxide fuel cell for a cleaner and sustainable future. In the modeled work, a solid oxide fuel cell, a gas turbine, an organic Rankine cycle, a Kalina cycle with ejector, a hydrogen generation and storage process, a wood steaming plant, and an ammonia production system is integrated, to generate useful products. Detailed thermodynamic modeling is performed through energy and exergy methods, to determine the performance of the advised system and subsystem. Moreover, energy efficiency, exergy efficiency, and exergy destruction analyses methods are applied to each sub-plant and the whole system separately. In addition, parametric research is carried out to examine the effects of modifying key parameters on the plant's and subsystems' performance. Looking at the analysis results, the amount of the hydrogen and ammonia generation capacities of this work are 0.0085 kgs−1and 0.2023 kgs−1, respectively. In addition, the modeled power plant produces a power rate of about 20,180 kW. As a result, this proposed study is calculated to have 61.04% energy efficiency, and 57.13% exergy efficiency.

Energy-saving and environmentally-benign integrated ammonia production system

In this work, an integrated conversion system of coal to ammonia (NH3) is developed with the objectives of total energy efficiency maximization and process simplification. The system integrates drying, chemical looping hydrogen production, cryogenic nitrogen separation, NH3 synthesis, and power generation. Due to this integration, the total exergy destruction from each individual process, as well as the whole system, can be reduced significantly, leading to high energy efficiency. Several operating parameters, including mass fraction of oxygen carrier, reduction temperature, oxidation temperature, operating pressure, and conversion per pass during NH3 synthesis are evaluated. Low-rank coal with a flowrate of 100 t h−1 (moisture content of 65.5 wt% wb) is used as the feedstock, while Fe2O3 is adopted as an oxygen carrier. From the results, the system shows high total energy efficiency (NH3 production and total energy efficiencies of 58% and 60%, respectively) and significant system simplification. Higher Fe2O3 mass fraction lowers the total flowrate of circulated material in the chemical looping module. Moreover, lower reduction temperature and higher combustion temperature are preferred due to lower amount of circulated material in the chemical looping module. Conversion per pass of 40% during NH3 synthesis leads to largest NH3 production amount, which is 40 t h−1.

Dynamic modelling of a solar hydrogen system for power and ammonia production

A new configuration of solar energy-driven integrated system for ammonia synthesis and power generation is proposed in this study. A detailed dynamic analysis is conducted on the designed system to investigate its performance under different radiation intensities. The solar heliostat field is integrated to generate steam that is provided to the steam Rankine cycle for power generation. The significant amount of power produced is fed to the PEM electrolyser for hydrogen production after covering the system requirements. A pressure swing adsorption system is integrated with the system that separates nitrogen from the air. The produced hydrogen and nitrogen are employed to the cascaded ammonia production system to establish increased fractional conversions. Numerous parametric studies are conducted to investigate the significant parameters namely; incoming beam irradiance, power production using steam Rankine cycle, hydrogen and ammonia production and power production using TEGs and ORC. The maximum hydrogen and ammonia production flowrates are revealed in June for 17th hour as 5.85 mol/s and 1.38 mol/s and the maximum energetic and exergetic efficiencies are depicted by the month of November as 25.4% and 28.6% respectively. Moreover, the key findings using the comprehensive dynamic analysis are presented and discussed.

Prevention and Countermeasures of Urea Crystallization in SCR Urea Pyrolysis System

The reasons for urea crystallization in the SCR urea pyrolysis system are analyzed, and system design, flow field control, equipment selection, process water and compressed air quality requirements and other aspects are optimized and selected, in order to improve the urea crystallization of pyrolysis furnace Phenomenon to effectively prevent and provide targeted countermeasures. In the process of pyrolysis of urea to produce ammonia, a slight deviation will easily form crystals. In severe cases, pipeline blockage and insufficient ammonia supply in the system will occur. However, based on the feedback of multiple application projects in the past ten years, there has not been a situation that has affected the operation of the pyrolysis system due to serious urea crystallization, and as long as the system design, flow field control, equipment selection, process water and compression Optimization and selection of air quality requirements and other aspects can effectively prevent and control the phenomenon of urea crystallization. The urea pyrolysis ammonia production system is a safe and effective source of ammonia, which can ensure the long-term safe and stable operation of the SCR system, so it will be more and more widely used.

Sustainability prioritization of energy systems by developing an integrated decision support framework with hybrid-data consideration

Rapid development in energy systems results in a choice question for decision-makers. Since many conflicting criteria are involved in the decision process, multi-criteria decision-making (MCDM) could be used. To make the decision process more suitable and reliable in reality, this paper introduces a sustainability prioritization framework with hybrid-data consideration via the integration of fuzzy group Delphi (FGD), fuzzy best-worst method (FBWM), and fuzzy best-worst projection (FBWP). In which, the triangular fuzzy number is incorporated into the framework to address the hybrid-data issues under uncertainty; the FGD rationally identifies the key criteria by implementing group consensus decisions, the FBWM accurately assigns the weights to the criteria by preserving the consistency in cognitive processes under uncertainty, and the FBWP rigorously ranks the alternatives by incorporating the absolute and relative performances regarding the multi-criteria. An illustrative case regarding ammonia production systems was studied, while the effectiveness and advantages of the framework were validated by results comparisons. In summary, this work makes methodological contributions to the sustainability prioritization of energy systems, including properly considering the uncertain hybrid data in decision-making, rationally selecting the key criteria and accurately determining their weights, and reliably ranking the alternative systems in the context of sustainability.