Conceptual carbon-reduction process design and quantitative sustainable assessment for concentrating high purity ethylene from wasted refinery gas

The direct emission of waste refinery gas after combustion will cause a severe greenhouse effect.Recovering high-value-added ethylene from wasted refinery gas has fundamental economic and environmental significance. Due to the complexity of the composition of refinery waste gas, designing and optimizing the whole recovery process is still a challenging task. Herein, a novel process(SCOAS) was proposed to obtain polymer-grade ethylene from wasted refinery gas through a direct separation process,and heat pump-assisted thermal integration optimization(HPSCOAS) was carried out. The unique feature of the novel approach is that a new stripper and ethylene reabsorber follow the dry gas absorber to ensure ethylene recovery and methane content. An industrial model, shallow cooling oil absorption(SCOA), and concentration combined cold separation system of ethylene unit using wasted refinery gas was established to analyze the technology and environment. Based on the detailed process modeling and simulation results, the quantitative sustainability assessment of economy and environment based on product life cycle process is carried out. The results show that compared with the traditional process when the same product is obtained, the total annual cost of the HPSCOAS process is the lowest, which is 15.4% lower than that of the SCOA process and 6.1% lower than that of the SCOAS process. In addition,compared with the SCOA process and the HPSCOAS process, the SCOAS process has more environmental advantages. The non-renewable energy consumed by SCOAS is reduced by about 24.8% and 6.1%, respectively. The CO_(2) equivalent is reduced by about 38.6% and 23.7%.

Decomposition analysis of CO_(2) emissions of electricity and carbon-reduction policy implication: a study of a province in China based on the logarithmic mean Divisia index method

As the proportion of electricity in final energy consumption gradually increases,CO_(2) emissions reduction actions in the power system will become the key to achieving China’s carbon-peak and carbon-neutrality goals.It is essential to analyse and quantify the driving forces of CO_(2) emissions from electricity generation in the fossil-rich area in China.This paper aims to identify the characteristics of CO_(2) emissions generated by electricity and provide a basis for formulating CO_(2)-reduction policies in power systems.First,we analyse the current state of CO_(2) emissions from electricity generation in Anhui Province that was dominated by fossil energy during the period 2010-19.Then,we apply the logarithmic mean Divisia index method to find the nature of the factors influencing the changes in CO_(2) emissions.Finally,we analyse the CO_(2)-reduction measures of each side of the source-network-load-storage of the power system in Anhui through a power-system carbon-reduction path analysis model proposed in this study and provide policy suggestions.The results showed the following.(i)CO_(2) emissions in Anhui Province continued to increase from 2010 to 2019 and the trend in the growth rate of CO_(2) emissions presented approximately a u-shaped curve.(ii)Economic activity has always been the dominant factor driving the growth of electricity CO_(2) emis-sions.The increase in the proportion of renewable energy in power generation,the improvement in thermal power-conversion efficiency and the decrease in the intensity of power consumption are the three major driving factors for the reduction in CO_(2) emissions from power generation in Anhui.(iii)The CO_(2)-reduction measures of the power system are provided in each link of the source-network-load-storage,such as developing the photovoltaic industry and building energy storage,upgrading and transforming coal-fired power stations,redu-cing the loss rate of transmission lines on the grid side and improving the efficiency of the utilization of electricity on the user side.