Simulation Study of an Oxy-Biomass-Based Boiler for Nearly Zero Emission Using Aspen Plus

Abstract

Bioenergy integrated CO2 capture is considered to be one of the viable options to reduce the carbon footprint in the atmosphere, as well as to lower dependability on the usage of fossil fuels. The present simulation-based study comprises the oxy bio-CCS technique with the objective of bringing about cleaner thermal energy production with nearly zero emissions, CO2 capture and purification, and with the ability to remove NOx and SO2 from the flue gas and to generate valuable byproducts, i.e., HNO3 and H2SO4. In the present work, a simulation on utilization of biomass resources by applying the oxy combustion technique was carried out, and CO2 sequestration through pressurized reactive distillation column (PRDC) was integrated into the boiler. Based on our proposed laboratory scale bio-CCS plant with oxy combustion technique, the designed thermal load was kept at 20 kWth using maize stalk as primary fuel. With the objective of achieving cleaner production with near zero emissions, CO2 rich flue gas and moisture generated during oxy combustion were hauled in PRDC for NOx and SO2 absorption and CO2 purification. The oxy combustion technique is unique due to its characteristic low output of NO sourced by fuel inherent nitrogen. The respective mechanisms of fuel inherent nitrogen conversion to NOx, and later, the conversion of NOx and SO2 to HNO3 and H2SO4 respectively, involve complex chemistry with the involvement of N–S intermediate species. Based on the flue gas composition generated by oxy biomass combustion, the focus was given to the fuel NOx, whereby different rates of NO formation from fuel inherent nitrogen were studied to investigate the optimum rates of conversion of NOx during conversion reactions. The rate of conversion of NOx and SO2 were studied under fixed temperature and pressure. The factors affecting the rate of conversion were optimized through sensitivity analysiês to get the best possible operational parameters. These variable factors include ratios of liquid to gas feed flow, vapor-liquid holdups and bottom recycling. The results obtained through optimizing the various factors of the proposed system have shown great potential in terms of maximizing productivity. Around 88.91% of the 20 kWth boiler’s efficiency was obtained. The rate of conversion of NOx and SO2 were recorded at 98.05% and 87.42% respectively under parameters of 30 °C temperature, 3 MPa pressure, 10% feed stream holdup, liquid/gaseous feed stream ratio of 0.04 and a recycling rate of the bottom product of 20%. During the simulation process, production of around four kilograms per hour of CO2 with 94.13% purity was achieved.

Effects of Temperature and Additives on NOx Emission From Combustion of Fast-Growing Grass

“…The reaction pathway for NO x generation by the oxidation of fuel-N (Vermeulen et al, 2012;Shah et al, 2019) shown in Figure 2 displays that the following two main sources of NO x in the flue gas: the conversion of volatile-N into volatile-NO x ; and the conversion of char-N into char-NO x . The conversion of fuel-N mainly occurs at temperatures below 900 °C; therefore, the NO x emission levels were measured and analyzed in the flue gases from combustion of fast-growing grass at different temperatures below 900 °C.…”

Evaluation of Miscanthus Gasification and Oxy-Combustion Carbon Dioxide Removal Potential with Carbon Capture Towards Implementation of Bioenergy with Carbon Capture and Storage in England

“…Gasification involves the conversion of a solid fuel into a gas through partial oxidation at temperatures between 750 °C and 1,000 °C (Samson et al 2018). According to Mutlu & Zeng (2020) gasification is defined as thermochemical conversion of carbonaceous materials into combustible gases, which is generally performed between 600 °C -1500 °C in the presence of steam, air, O2, CO2 or the mixture of these gases are use case dependend (Motta et al 2018;Shah, Gou & J. Wu 2019). The main product of a typical gasification process, known as syngas, consists of a mixture of H2, CO, CO2, CH4, N2, H2O as well as other light hydrocarbons (Kaushal & Tyagi 2017).…”

Challenges and Opportunities of Modeling Biomass Gasification in Aspen Plus: A Review

“…In the bioenergy sector, concepts such as oxycombustion of biomass for nearly zero‐net emissions , pressurized anaerobic digestion and biogas upgrading , and techno‐economic assessment of biomass‐based chemical production have been investigated using Aspen Plus. Even though each study handles the modeling process from a different technological perspective, the main goal is the development of a realistic process model with high efficiency and product quality.…”