NOx reduction behaviour in copper zeolite catalysts for ammonia SCR systems: A review

A review of NOx and SOx emission reduction technologies for marine diesel engines and the potential evaluation of liquefied natural gas fuelled vessels

Extensive research has been conducted on controlling carbon dioxide (CO2), sulfur oxides (SOx), and nitrogen oxides (NOx) emissions in recent years with increasing environmental awareness. The primary contributor to climate change is the exponentially growing anthropogenic CO2, NOx, and SOx in the air from various energy and industrial sectors. Hence, several pre-combustion and post-combustion processes to mitigate these gases have been introduced and implemented. Despite the benefits of CO2, SOx, and NOx abatement technologies, researchers still have major challenges to deal with. While the removal efficiencies, operational costs, and resulting byproducts of conventional removal technologies are being improved, new technologies are also emerging. As it is evident from the current abundant reserves of coal that it will continue to be in a significant position among the principal sources of energy for more than a decade, the research for the reduction of CO2, NOx, and SOx is inevitable to save future generations from the harmful impacts of these pollutants. This review paper summarizes the progress of different emission control technologies at the plant level and introduces emerging technologies that are environment friendly.

Review on the progress in emission control technologies for the abatement of CO2, SOx and NOx from fuel combustion

The demand for V2O5-WO3/TiO2 catalysts is growing as many countries impose increasingly stricter limits on nitrogen oxide emissions. Unfortunately, after service, the spent V2O5-WO3/TiO2 catalyst is continuously and considerably discarded. The cost of the catalyst accounts for approximately 30–50% of the total investment in the denitration system. Additionally, the spent catalyst contains significant amounts of valuable metals and some heavy metals. Thus, the regeneration to form a new catalyst or recovery of valuable metals from the spent V2O5-WO3/TiO2 catalyst has gained widespread attention in recent years, not only for meeting the growing demand for corresponding critical metals/catalysts but also reducing the potential ecological and environmental hazards caused by inappropriate disposal. In this article, a systematic review of the literature was conducted to examine recently developed processes and technologies for recycling the spent V2O5-WO3/TiO2 catalyst to recover either new catalysts or valuable metals. Moreover, the challenges associated with process optimization for the regeneration to form a new catalyst and the recovery of valuable metals were analyzed. The aim of this article is to provide a guideline on how effective processes and techniques for the spent V2O5-WO3/TiO2 catalyst recycling can be developed and to motivate further studies in this theme for industrial-scale realization.

Recycling strategies of spent V2O5-WO3/TiO2 catalyst: A review

Optimisation design of SCR mixer for improving deposit performance at low temperatures

A numerical model of spray and its interaction with the gas exhaust flow and static mixer are developed to investigate the effects of the mixer on the selective catalytic reduction (SCR). The residence time of spray droplets in straight pipes with and without mixers and the interaction between spray droplets and the blades of mixers are investigated. The numerical results show that due to the improvement of evaporation rates of sprays and the ability to break droplets into smaller ones, static mixers can help SCR systems achieve better urea conversion efficiency. Furthermore, the using of mixers significantly improves the uniformity of the reducing agent in a pipe.

CFD studies on effects of SCR mixers on the performance of urea conversion and mixing of the reducing agent

The Selective catalytic reduction (SCR) technology is an effective and economical method for reducing NOx emissions from the heavy duty diesel engine. To ensure a reasonable design of the SCR system, it is critical to understand the effects of space velocity (GHSV), NO2/NOx ratio, NH3/NOx ratio and structural parameters of the SCR reactor on the NOx conversion efficiency. Using the experimental method to conduct all the investigations though the entire development cycle of SCR system is expensive and would cost a long time. Numerical method as a complementary tool to bench tests can help to optimize the design and shorten the development cycle of SCR system. In this paper, a mathematical model is developed to predict the NOx conversion efficiency over a Cu catalyst. The model is calculated in the MATLAB environment. The simulation results agree well with the experimental data, which indicates that the mathematical model is reliable and can effectively predict the performance of the SCR catalytic system. Then the effects of the parameters, such as space velocity, NO2/NOx ratio, NH3/NOx ratio, length, diameter and number of channels per square inch (CPSI) of the SCR reactor on the NOx conversion efficiency were studied.

Ligang Tan

Papers

CFD studies on effects of SCR mixers on the performance of urea conversion and mixing of the reducing agent

An investigation on the catalytic characteristic of NOx reduction in SCR systems

Fatigue life prediction of centrifugal fan blades in the ventilation cooling system of the high-speed-train

An investigation on shielding effectiveness of conductive adhesive

A critical analysis of the bulk current injection immunity test based on common-mode and differential-mode