Life cycle assessment of acetylene production from calcium carbide and methane in China
Graphical abstract
Introduction
Acetylene plays an important role in organic synthesis because of its triple bond (Teong and Zhang, 2020), and can be used to produce vinyl chloride, 1,4-butanediol, acetaldehyde, esters, ethers, and other products. Acetylene has a high calorific value, so it is often used as a welding heat source, as well as an alternative fuel, and as an additive for internal combustion engines to reduce NOx emissions (Khader Basha et al., 2020; Lakshmanan and Nagarajan, 2011).
Acetylene production processes include the calcium carbide, hydrocarbon cracking, and methane partial oxidation methods, etc. (Kang et al., 2016). The calcium carbide method is a traditional and universally used acetylene production process; it is relatively simple, but is a large energy consumer and results in CO2 emissions, which have a negative environmental effect (Zhang et al., 2017). For these reasons, it is basically no longer used to produce acetylene outside of China; thus, the total annual non-Chinese acetylene production capacity of approximately 3 million tons is achieved mainly using hydrocarbons and methane (mainly from natural gas) as raw materials (Orsula et al., 2015).
In China, the calcium carbide and methane partial oxidation methods are used to produce acetylene, with the former being predominantly used. China is the largest producer and consumer of calcium carbide worldwide, with 2018 output reaching 26.08 million tons, 90% of which was used to produce polyvinyl chloride, 1,4-butanediol, and vinyl acetate through acetylene (LZI, 2018). The average calcium carbide purity has been calculated to be 80% (Orsula et al., 2015), and the Chinese acetylene output using the calcium carbide method was approximately 7.62 million tons in 2018— which was much higher than the total acetylene output from the rest of the world combined.
Acetylene production using the partial oxidation method was introduced in the 1970s for the production of vinylon (also known as vinalon), polyvinyl alcohol, and vinyl acetate, and the annual acetylene production capacity using this method is 658.6 thousand tons (An, 2013). The methane plasma method used to produce acetylene is a local Chinese high-tech process, and has been in the pilot stage of development. It uses only approximately one-third of the methane required by the partial oxidation method, and, according to a report in March 2020 (Wang, 2020), a plant for acetylene production using the methane plasma method will soon be built in Xinjiang (Xinjiang Uygur Autonomous Region in NW China), to provide raw materials for biodegradable plastics production. This means that acetylene production using the methane plasma method is expected to be industrialized in China, in due course. Methane has a wide range of sources, including conventional natural gas, unconventional natural gas (shale gas, coalbed methane, tight sandstone gas, and so on), and biogas. China's total unconventional natural gas resources rank second in the world, with recoverable resources accounting for 14% of the global total (Lu, 2019). In the future, it will be necessary to accelerate development of unconventional natural gas (NEA National Energy Administration, 2020), which could have a profound impact on the natural gas market pattern.
It was necessary to adopt a scientific approach so as to understand the environmental impacts of producing acetylene by the calcium carbide, partial oxidation, and plasma methods. This would allow the systematic analysis and comparison of the respective environmental performances of the three production methods, and its results could be very significant for developing China's acetylene industry, with the possibility of providing a clear future development roadmap.
Life cycle assessment (LCA) is the compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life cycle. It is a recognized environmental analysis tool (Zhang et al., 2020), which can be used to identify environmental problems and optimize improvement plans (Li et al., 2020), and has been widely used to evaluate the lifetime environmental performance of products and processes (Luo et al., 2020; Mao et al., 2021; Souliotis et al., 2018; Vidergar et al., 2020; Visentin et al., 2021).
To date, there have been few studies on the environmental performance of the calcium carbide- or methane-based acetylene production processes. Huang and Qian (2007) used the life cycle cost analysis method to study acetylene production from natural gas, with their results showing that the external cost of the partial oxidation method was lower than that of the plasma method—and that its environmental performance was better than that of the plasma method. However, their method could not be applied to comprehensively evaluate all environmental impacts of production processes, being unable to account for aspects such as effects of global warming, fossil resource consumption, acidification effects, and so on. Mi et al. (2016) also considered acetylene production LCA, but only conducted carbon footprint analysis on a low-rank, coal-based acetylene manufacturing process.
In this study, the LCA method was used to evaluate the environmental performance of acetylene production using the calcium carbide, partial oxidation, and plasma methods. The authors first established the LCA models, then quantified the environmental burdens using the CML 2001 method, and discussed the environmental impact of the three acetylene production methods from the perspective of technical improvement, energy substitution, and policy planning. The aim of this work was to explore ways to reduce the environmental burdens of acetylene production, and to provide a reference for the future sustainable development of China's acetylene industry.
Section snippets
Methodology
The LCA study was conducted in accordance with International Standard ISO 14040, which divides the process into four main steps: goal and scope definition, life cycle inventory (LCI) analysis, life cycle impact assessment (LCIA), and life cycle interpretation (ISO International Organization for Standardization, 2006a).
LCIA results for acetylene production using the calcium carbide method
Contributions from each process in the investigated impact categories can be seen Fig. 4. Electricity had a significant impact on every category, especially the FAETP, HTP, and TETP, accounting for >90%. On the one hand, due to high energy consumption in the calcium carbide production stage (Zhang et al., 2020), 10,299.7 kWh of electrical energy was consumed for each ton of acetylene produced, accounting for 95.3% of total electricity consumption (Table 1). On the other hand, coal-based
Discussion
The findings in Section 3 make it clear that special attention should be paid to decreasing the environmental impact of electricity and steam generation on acetylene production. To reduce the environmental impact of steam, it is necessary to recover as much of the heat used in the production process as possible, by technical means, or to use clean energy to replace coal in the steam production process—with both options discussed here. To reduce the environmental impact of electricity
Conclusions
In the study reported here, the authors compared the environmental impacts caused by producing acetylene using the calcium carbide, partial oxidation, and plasma methods, and discussed the effects of technical improvements, energy substitution, and policy development on environmental performance. The findings were as follows:
Steam had a relatively large impact on the environment when the partial oxidation and plasma methods were used. Using oil quenching to recover heat was beneficial for
CRediT authorship contribution statement
Suisui Zhang: Conceptualization, Methodology, Writing – original draft. Jingying Li: Data curation, Writing – review & editing, Supervision. Gang Li: Investigation, Data collection. Yan Nie: Data collection. Luyao Qiang: Validation. Boyang Bai: Validation. Xiaoxun Ma: Supervision.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (NO. 22078266) and (NO. 22008198), Science and Technology Plan Projects of Shaanxi Province, China (2017ZDCXL-GY-10-03), and Special Scientific Research Plan Project of Education Ministry of Shaanxi province, China (No. 19JK0854).
References (45)
- et al.
Simulation of industrial-scale gas quenching process for partial oxidation of nature gas to acetylene
Chem. Eng. J.
(2017) - et al.
The viability of generating electricity by harnessing household garbage solid waste using life cycle assessment
Procedia Technol.
(2013) - et al.
A multi-criteria sustainability assessment for biodiesel alternatives in Spain: life cycle assessment normalization and weighting
Renew. Energy
(2021) - et al.
Particulate matter emission control from small residential boilers after biomass combustion. A review
Renew. Sustain. Energy Rev.
(2021) - et al.
Methane to acetylene conversion by employing cost-effective low-temperature arc
Fuel Process. Technol.
(2016) - et al.
Performance analysis and control of NOx emissions in diesel engine using on-board acetylene gas from calcium carbide
Mater. Today Proc.
(2020) - et al.
Study on using acetylene in dual fuel mode with exhaust gas recirculation
Energy
(2011) - et al.
Life cycle assessment and economic analysis of methanol production from coke oven gas compared with coal and natural gas routes
J. Clean. Prod.
(2018) - et al.
A holistic life cycle evaluation of coking production covering coke oven gas purification process based on the subdivision method
J. Clean. Prod.
(2020) - et al.
CO2 emissions in calcium carbide industry: an analysis of China's mitigation potential
Int. J. Greenh. Gas Contr.
(2011)
China's black carbon emission from fossil resource consumption in 2015, 2020, and 2030
Atmos. Environ.
Life cycle assessment approach for renewable multi-energy system: a comprehensive analysis
Energy Convers. Manag.
How can bicycle-sharing have a sustainable future? A research based on life cycle assessment
J. Clean. Prod.
Multi-product carbon footprint assessment for low-rank coal-based acetylene manufacturing process
J. Clean. Prod.
Experimental study and life cycle assessment (LCA) of hybrid photovoltaic/thermal (PV/T) solar systems for domestic applications
Renew. Energy
Calcium carbide and its recent advances in biomass conversion
J. Bioresourc. Bioprod.
Life cycle sustainability assessment of the nanoscale zero-valent iron synthesis process for application in contaminated site remediation
Environ. Pollut.
A comparative life-cycle assessment of hydro-, nuclear and wind power: a China study
Appl. Energy
Life cycle human health and ecotoxicological impacts assessment of electricity production from wood biomass compared to coal fuel
Appl. Energy
Life cycle assessment of grid-connected power generation from metallurgical route multi-crystalline silicon photovoltaic system in China
Appl. Energy
Life cycle assessment of electrolytic manganese metal production
J. Clean. Prod.
Actuality and thoughts of natural gas to acetylene technology
Mod. Chem. Ind.
Cited by (23)
Sustainable utilisation of calcium-rich industrial wastes in soil stabilisation: Potential use of calcium carbide residue
2024, Journal of Environmental ManagementNitrogen-doped carbon particles with distinctive ethylene adsorption selectivity for efficient ethylene/acetylene separation
2023, Chemical Engineering JournalCarbon dioxide capture with aqueous calcium carbide residual solution for calcium carbonate synthesis and its use as an epoxy resin filler
2023, Journal of Environmental ManagementA novel gas removal method for the removal of C<inf>2</inf>H<inf>2</inf> in calcium carbide slag slurry by fine bubbles combined with air purging: performance, mechanism, and in situ bubble imaging analysis
2023, Separation and Purification TechnologyCitation Excerpt :Therefore, it is urgent to find low-carbon calcareous materials that can replace limestone to reduce carbon emissions [2,6]. Calcium carbide slag (CCS) is a solid waste generated in the acetylene (C2H2) production process through a reaction of calcium carbide with water [7,8], with an annual emission of over 40 million tons in China [7,9]. It mainly contains 80%–90% Ca(OH)2, with fine particle size and high reactivity, and can replace limestone to prepare cement, desulfurizer, active calcium oxide, and other products [10–13].
- 1
These authors contributed equally to this manuscript.