焦化厂蒸氨生产装置技术研究

通过对焦化厂蒸氨系统直接蒸氨、间接蒸氨生产工艺装置的技术研究,选择合理工艺,使氨水中的挥发氨由约0．25％（2．5g／L）降至0．01％（0．1g／L）。     

合成氨工艺技术的现状及其发展趋势

对我国的大、中、小型氮肥工业发展现状进行了分析介绍,并对合成氨技术未来的发展趋势进行了展望。     

氨气敏电极法测定废水中的氨氮

研究了氨气敏电极9512HPBNWP测定废水中的氨氮,该方法快速,操作简单,无须对样品进行预处理,省去了絮凝沉淀或过滤等操作,适合实验室大批量废水中氨氮含量的测定,尤其对于高浓度废水更具有优越性。     

Room temperature NH3 gas sensor based on PMMA/RGO/ZnO nanocomposite films fabricated by in-situ solution polymerization

Effective detection of ammonia gas is of great importance due to its detrimental effects on human health, environment, and ecosystem. High-performance composite gas sensors are vital in accomplishing this goal. Herein, we investigate the performance of an ammonia (NH₃) gas sensor fabricated via dip-coating the silver interdigitated electrode for PMMA/RGO/ZnO (PRZ) nanocomposite solution with acetone as a solvent. The PRZ ternary nanocomposite was synthesized using the in-situ solution polymerization method and the resistive properties of the films assembled on the interdigitated electrode were analyzed, with respect to the fixed and varying ammonia gas concentrations, using LCR meter. When the sensor is operated in the controlled chamber containing ammonia gas at room temperature, the sensor responds rapidly to ammonia with a fast recovery of 13.02 s at a gas concentration of 350 ppm. The PRZ sensor exhibits high sensing percentage response (527%), excellent repeatability (four times), high sensitivity at low concentrations (less than 10 ppm), swift response and recovery times (1.94 s/13.02 s), and long-term stability (up to 90 days) with fluctuation of 3.2%, which signifies PRZ composite as a potential material for ammonia gas sensor. Aspects such as simplicity of the synthesis process and fabrication, excellent sensing performance, as well as fast response-recovery time at a particular gas concentration are noteworthy in this study. These features can be utilized for the detection of ammonia gas in chemical and biological fields.     

Utilization of green ammonia as a hydrogen energy carrier for decarbonization in spark ignition engines

Rising concerns about the dependence of modern energy systems on fossil fuels have raised the requirement for green alternate fuels to pave the roadmap for a sustainable energy future with a carbon-free economy. Massive expectations of hydrogen as an enabler for decarbonization of the energy sector are limited by the lack of required infrastructure, whose implementation is affected by the issues related to the storage and distribution of hydrogen energy. Ammonia is an effective hydrogen energy carrier with a well-established and mature infrastructure for long-distance transportation and distribution. The possibility for green ammonia production from renewable energy sources has made it a suitable green alternate fuel for the decarbonization of the automotive and power generation sectors. In this work, engine characteristics for ammonia combustion in spark ignition engines have been reported with a detailed note on engines fuelled with pure ammonia as well as blends of ammonia with gasoline, hydrogen, and methane. Higher auto-ignition temperature, low flammability, and lower flame speed of ammonia have a detrimental effect on engine characteristics, and it could be addressed either by incorporating engine modifications or by enhancing the fuel quality. Literature shows that the increase in compression ratio from 9.4:1 to 11.5:1 improved the maximum power by 59% and the addition of 10% hydrogen in supercharged conditions improved the indicated efficiency by 37%. Challenges and strategies for the utilization of ammonia as combustible fuel in engines are discussed by considering the need for technical advancements as well as social acceptance. Energy efficiency for green ammonia production is also discussed with a due note on techniques for direct synthesis of ammonia from air and water.     

Optimizing thermal performances and NOx emission in a premixed ammonia-hydrogen blended meso-scale combustor for thermophotovoltaic applications

As a carbon-free energy carrier, ammonia has attracted significant interest in the combustion field as a potential substitute for fossil fuels. However, the focus has been given to the application at meso-scale conditions, particularly with regard to thermal performance and NO_x emissions. Therefore, the present study numerically investigates a 3-dimensional time-domain premixed ammonia/oxygen meso-scale combustor to optimize its' thermal performance and NO_x emission for power generation applications. The numerical model is firstly validated by using experimental data available in the literature. Then, the effects of 1) the inlet pressure (P_in), 2) the equivalence ratio, and 3) the hydrogen blended ratio on the temperature uniformity, the combustor outer wall mean temperature (OWMT), NO emission, and exergy efficiency are examined. The results indicate that increasing P_in intensifies the mixing process of the mixture gases, thus reducing the residence time for the high-temperature flame in the combustion chamber. The optimized OWMT and NO emissions are up to 26% and 40.3% respectively, with only 9% compensation of the standard deviation achieved, when the inlet velocity is set to 0.5 m/s and P_in is 3.0 bar. Furthermore, varying the equivalence ratio in the range of 0.95–1.1 has a minor influence on improving thermal performances, but a significant impact on mitigating the NO_x emission performance. Additionally, blending less than 15% hydrogen has a significant reduction in the maximum NO_x emission (up to 53%); however, the influence on the OWMT can be neglected. Further exergy analysis reveals that elevating P_in results in a decrease in the exergy efficiency due to the increased inlet exergy. In general, this work provides a preliminary method for improving the thermal performance and NO_x emission of an ammonia/hydrogen-oxygen-fueled meso-scale combustor for power generation purpose.     

Large-scale long-distance land-based hydrogen transportation systems: A comparative techno-economic and greenhouse gas emission assessment

Interest in hydrogen as an energy carrier is growing as countries look to reduce greenhouse gas (GHG) emissions in hard-to-abate sectors. Previous works have focused on hydrogen production, well-to-wheel analysis of fuel cell vehicles, and vehicle refuelling costs and emissions. These studies use high-level estimates for the hydrogen transportation systems that lack sufficient granularity for techno-economic and GHG emissions analysis. In this work, we assess and compare the unit costs and emission footprints (direct and indirect) of 32 systems for hydrogen transportation. Process-based models were used to examine the transportation of pure hydrogen (hydrogen pipeline and truck transport of gaseous and liquified hydrogen), hydrogen-natural gas blends (pipeline), ammonia (pipeline), and liquid organic hydrogen carriers (pipeline and rail). We used sensitivity and uncertainty analyses to determine the parameters impacting the cost and emission estimates. At 1000 km, the pure hydrogen pipelines have a levelized cost of $0.66/kg H₂ and a GHG footprint of 595 gCO₂eq/kg H₂. At 1000 km, ammonia, liquid organic hydrogen carrier, and truck transport scenarios are more than twice as expensive as pure hydrogen pipeline and hythane, and more than 1.5 times as expensive at 3000 km. The GHG emission footprints of pure hydrogen pipeline transport and ammonia transport are comparable, whereas all other transport systems are more than twice as high. These results may be informative for government agencies developing policies around clean hydrogen internationally.     

Pulsating one-dimensional detonation in ammonia-hydrogen–air mixtures

In this study, one-dimensional detonations in ammonia/hydrogen-air mixtures are numerically investigated by solving the fully compressible Navier-Stokes equations with detailed chemistry. Pulsating instabilities with single-mode are observed during the detonation wave propagation, accompanied by periodic coupling and decoupling of the lead shock wave and the reactive front. The ratio between driver pressure and initial pressure determines the overdrive degree and thus the oscillatory mode of detonation for a premixture with certain composition. The effects of hydrogen dilution and mixture equivalence ratio on pulsating detonations are also examined under a constant driver pressure. The growing hydrogen fraction in fuel blends significantly increases the oscillation frequency. In addition, the pulsating detonation frequency rises with increasing equivalence ratio under fuel-lean conditions, peaks under stoichiometric conditions, and falls under fuel-rich conditions as the equivalence ratio increases further. Evolutions of reactants, main intermediate radicals, and products are analysed in both fuel-lean and fuel-rich conditions. A chemical explosive mode analysis further confirms the highly-autoignitive nature of the mixture in the induction zone between reaction front and shock front where thermal diffusion plays a negligible role.     

一种新型环保低温制冷系统

提出了一种采用氨做制冷剂、可用于获得低至．60℃低温的新型制冷系统,为我国低温冷库的建设提供了一条新型环保技术路线。该制冷系统具有两个蒸发温度回路,高温回路的蒸发温度在-35- -28℃之间可调,低温回路的蒸发温度在．50- -65℃之间可调。两个回路在低压循环桶处汇合。在对该系统进行热力计算的基础上,分析了系统的特点及应用中需要解决的问题。该制冷系统可在新建、改建或扩建．50- -60℃的低温库中采用。     

高浓度氨氮渗滤液脱氦方式的比较及选择

氨氮浓度高是垃圾渗滤液的水质特征之一,目前对于高浓度氨氮废水的处理方法主要有硝化—反硝化、氨吹脱法、化学沉淀法以及新型生物脱氮技术。基于工程实例,对国内外已有的去除垃圾渗滤液高浓度氨氮的方法进行了阐述和对比,并对渗滤液处理厂脱氮方式的选择提出了建议。