• Energy Research

The valorisation of lignin is being increasingly recognised to improve the economics of pulp and paper making mills. In the present study, an integrated lignin–glycerol valorisation strategy is introduced with an overarching aim for enhancing the process value chains. LignoBoost kraft lignin was subjected to base-catalysed depolymerisation using glycerol as a co-solvent. The generated bio-oil was used as a renewable additive to biodiesel for enhancing the oxygen stability. The influence of three independent parameters including temperature, time and glycerol amount on lignin depolymerisation was investigated. Response surface methodology was applied to design the experiments and to optimise the process for maximising the yield and antioxidant impact of bio-oil. The results showed that glycerol has a positive qualitative and quantitative impact on the produced bio-oil, where an enhancement in the yield (up to 23.8%) and antioxidant activity (up to 99 min induction period) were achieved using the PetroOxy method (EN16091). The addition of 1 wt% bio-oil on biodiesel led to an improvement in the oxidation stability over a neat sample of up to ∼340%, making it compliant with European standard (EN14214). The proposed process presents a biorefinery paradigm for the integrated utilisation of waste cooking oil, lignin and glycerol.

Soot formation in a reverse-flow partial-oxidation reactor for reforming of gasifier producer gas has been studied. The process was modeled using a detailed reaction mechanism to describe the kinetics of soot formation. The numerical model was validated against experimental data from the literature and showed good agreement with reported data. Nine cases with different gas compositions were simulated in order to study the effects of water, hydrogen and methane content of the gas. The CO and CO2 contents, as well as the tar content of the gas, were also varied to study their effects on soot formation. The results showed that the steam and hydrogen content of the inlet gas had less impact on the soot formation than expected, while the methane content greatly influenced the soot formation. Increasing the CO2 content of the gas reduced the amount of soot formed and gave a higher energy efficiency and methane conversion. In the case of no tar in the incoming gas the soot formation was significantly reduced. It can be concluded that removing the tar in an energy efficient way, prior to the partial oxidation reactor, will greatly reduce the amount of soot formed. Further investigation of tar reduction is needed and experimental research into this process is ongoing.

Abstract Desulfurization at medium temperature was investigated with focus on impacts of temperature and CO 2 concentration under Oxyfuel firing and Regenerative Calcium Cycle (RCC) conditions. Investigation started with thermodynamic analysis and ThermoGravimetric Analysis (TGA). Tests were then conducted by a bench-scale fixed-bed type reactor, using a synthetic gas mixture. Various parameters were evaluated. The envelope covered temperature variation of 150-450 °C, CO 2 concentrations in the gas stream up to 60% and water concentrations between 0 to 25%. These tests were done having SO 2 concentrations in the gas of 2000 ppm SO 2 . Furthermore different types of lime samples were screened. It was found that CO 2 had strong impact on medium temperature desulfurization. Capture of CO 2 by the lime was enhanced by increasing temperature. CO 2 competed with SO 2 and the relative extent to react with lime varied with temperature. Rate of reaction increased with temperature, the capacity of lime-to-SO 2 and lime-to-CO 2 increased as well. Optimum temperature windows were searched and will be discussed. Based on the tests results, scenarios of desulfurization options at medium temperature range for Oxy and RCC are evaluated, and will be discussed in details. The testing results show issues related to high concentration of CO 2 under the Oxy conditions at temperature over 250 °C. Though capacity of lime for SO 2 increases with temperature, the amount is limited due to reaction with CO 2 at high concentration. Desulfurization at medium temperature range, 250 - 450 °C, should be aiming at moderate SO 2 removal, and the reuse of the spent reagent is considered in the downstream wet desulfurization process. With about 10% CO 2 , in the RCC conditions, it is more optimistic to remove SO 2 in the medium temperature range. Optimum temperature range is discussed for achieving moderate SO 2 removal. Reuse of the spent reagent is considered in the downstream wet desulfurization process.

Gasification processes convert carbon-containing material into syngas through chemical reactions in the presence of gasifying agents such as air, oxygen, and steam. Syngas mixtures produced from such processes consist mainly of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), and methane (CH4); this gas can be directly utilised as a fuel to produce electricity or steam. Besides, it is regarded as a basic feedstock within the petrochemical and conventional refining industries, producing various useful products like methanol, hydrogen, ammonia, and acetic acid. In this work, a rigorous process model is developed to simulate the co-gasification of coal-biomass blends through an entrained flow gasifier. The proposed model is tested originally for American coal. The model validation is made against literature data and results show good agreement with these practical data, providing a robust basis for integration and retrofitting applications. Effects of critical parameters, comprising gasification temperature, steam/O2 ratio, and feedstock variability on the syngas composition and gasifier efficiency are studied. The developed model is further applied in a project to revamp an existing Egyptian natural gas-based power plant, replacing its standard fuel with coal-rice straw blends. The revamping project integrates the existing plant with a gasification unit burning a blend of coal and rice straw to replace the conventional fuel used. The feedstock used constitutes a dry Egyptian coal and a coal-rice straw blend (10 wt% rice straw), gathered locally. Different blending scenarios are investigated and the best performance is achieved with coal to rice straw ratio of 90:10 on weight basis, attaining 85.7% cold gas efficiency and significant economic savings. Results showed that the total annualised cost of the revamped process decreased by 52.7% compared with a newly built integrated gasification combined cycle (IGCC) unit. (Less)

Abstract Production of synthetic vehicle fuels from biomass is a hot topic. There are several alternative fuels to consider when evaluating properties such as cost of production and energy efficiency to both product and final use in a road vehicle. Thermochemical conversion via gasification and downstream synthesis of fuels as well as biochemical conversion of woody biomass to ethanol is considered in this paper. The vehicle fuels considered in this paper include methanol, ethanol, synthetic natural gas, Fischer–Tropsch diesel, dimethyl ether and synthetic gasoline from the methanol-to-gasoline process. The aim of the study is to evaluate all the different fuels on the same basis. The production cost of the various fuels is estimated as well as the overall investment cost. Well-to-wheel energy efficiency calculations were performed to evaluate how far a vehicle can travel on the fuel produced from a specific amount of feedstock. The production cost of the fuel as a function of distance travelled is also presented. Of the fuels considered in this study, dimethyl ether manages the highest efficiency from feedstock to travelled distance and manages to do so at the lowest cost. Ethanol produced from woody biomass is the most inefficient and expensive fuel, when considering biomass harvesting and transport, the production and road use (ignoring fuel distribution), in this study due to low yields in fuel production. Total investment cost for ethanol is considerably lower at MM$ 281 compared to the thermochemical fuels that ranges from MM$ 580 to MM$ 760. The production costs of the various fuels range from $79.9/MW h for synthetic natural gas to 139.6 $/MW h for Fischer–Tropsch diesel. The production cost translates to a travel cost ranging from $4.98/100 km for dimethyl ether to $8.51/100 km for ethanol.

AbstractThis paper presents the major outcome of the IEA Hydrogen Implementing Agreement (IEA-HIA) Task 23 “Small-scale reforming for on-site hydrogen supply”. The task is briefly described, including the three sub-tasks: harmonized industrialization, sustainability and renewables and market information.An exclusive network of worldwide suppliers of reformers as well as gas companies has contributed to the discussion, evaluation and harmonization of on-site production technologies and optimal use of feedstock. The ambition has been to contribute to harmonization of capacities and improved system performance to facilitate both reduced system and production costs.

Solutions of the amines N-methyldiethanolamine (MDEA) and piperazine (PZ) are commonly used for CO2 removal in industrial applications. This is mainly due to the low heat of reaction of MDEA, reducing the heat required for regeneration, and the high reaction rate of PZ, which reduces the size of the absorption tower. However, the effect of PZ on the heat of absorption in a mixture of these two solutions has not previously been investigated. This paper presents experimental data on the heat developed during the absorption of CO2 in aqueous solutions of MDEA and PZ, and mixtures thereof, at low loading and temperatures from 35 °C to 65 °C. The results indicate that PZ affects the amount of heat developed to a higher degree than previously thought, resulting in a significant increase compared to pure MDEA solutions. This effect is more pronounced at low carbon dioxide loadings. The impact of the temperature on the heat of absorption is weak for MDEA, as has been found in previous studies. The present study also demonstrated a weak temperature dependence for PZ.

AbstractKraft lignin, a by‐product from the production of pulp, is currently incinerated in the recovery boiler during the chemical recovery cycle, generating valuable bioenergy and recycling inorganic chemicals to the pulping process operation. Removing lignin from the black liquor or its gasification lowers the recovery boiler load enabling increased pulp production. During the past ten years, lignin separation technologies have emerged and the interest of the research community to valorize this underutilized resource has been invigorated. The aim of this Review is to give (1) a dedicated overview of the kraft process with a focus on the lignin, (2) an overview of applications that are being developed, and (3) a techno‐economic and life cycle asseeements of value chains from black liquor to different products. Overall, it is anticipated that this effort will inspire further work for developing and using kraft lignin as a commodity raw material for new applications undeniably promoting pivotal global sustainability concerns.