1,720,982 research outputs found
Calcination in an electrically heated bubbling fluidized bed applied in calcium looping
No full textSwitching fossil fuels to green electricity as the energy source to decarbonate the raw meal
in the calciner can eliminate the CO2 emissions produced through fuel combustion and
also provide a basis for simple capture of the CO2 generated through calcination, as CO2
is the only gaseous product exiting from the electrified calciner. For this reason, an
electrically-heated fluidized bed reactor was designed as a calciner and its applicability
and cost estimation were carried out.
A mass and energy balance for steady-state conditions was conducted, so that relevant
temperature, flow rates, and duties in the electrically-heated FB reactor and heat
exchanger have been calculated by MATLAB code.
The key parameters of FB reactor such as minimum fluidization velocity, minimum
bubbling velocity, terminal settling velocity, and the reaction time based on the particle
size distribution were calculated. The fluidizability of the fine limestone particles was
tested by a cold-bed BFB unit and it revealed that owing to the fine particle sizes of the
raw meal, there are strong cohesive forces between the particles. Hence, a conventional
bubbling fluidized bed is difficult to fluidize Geldart C particles. The identical system was
simulated by Barracuda® and the results of the simulations had a good consistency with
the experiments.
A binary-particle fluidization system, mixing fine powders with the coarse particles, was
proposed to enhance the flowability of fine particles. The fluidized bed calciner process
was designed as a semi-batch process operating in two modes; the calcination mode (with
a low gas velocity) and the entrainment mode (with a higher velocity). After the raw meal
particles have been calcined, they have to be separated from the coarse, inert particles.
This can be done by increasing the velocity of the CO2 used for fluidization to a value
sufficiently high to entrain the raw meal particles, but still sufficiently low that the coarse,
inert particles are not entrained. The inert particles may provide a homogeneous
distribution of the fine particles and help to fluidize them. The aggregation and clustering
of the fine particles will decrease due to collisions with inert coarse particles. The inert
particles will also provide a thermal energy reservoir through their heat capacity and
thereby contribute to a very stable bed temperature, which is advantageous in the control
of the process.
The operational conditions at 1173 K, such as the particle size distribution of the inert
particles and the fluidization gas velocity were calculated by the Barracuda simulations.
The inert particles with the diameter range of 550-800 µm and the velocities in the
calcination and entrainment modes equal to 0.18 m/s and 3 m/s appeared as suitable for
the calciner operation. The simulations showed that at the velocity of 0.18 m/s, 7.6% of
fine particles may be entrained. However, by comparing the CO2 residence time with the
reaction time of particles, it was concluded that all fine powders were calcined before
leaving the be
Gas-to-gas heat exchanger for heat utilization in hot CO2 from an electrically heated calcination process
No full textThesis was done with the objective of evaluating a gas to gas heat exchanger which will
be used to recover heat from hot calciner exit gas from an electrically heated calcination
process.
Shell and tube heat exchanger (STHE) was selected for design and Inconel 718 was
selected as material of construction to handle high temperature. Gas flow was found to
be highly dilute in terms of dust concentration, so possible problems associated with
dust was assumed to be negligible for design condition.
Study of STHE for 2 different structures (1-2 STHE and 2-4 STHE) along with variation
in internal tube diameter and number of STHE in parallel was done. Thermal study of
STHE was done by utilizing Kern’s method and cost analysis was done using capacity
factor method and detailed factor method. Centrifugal radial fan and turbo blower was
selected as pressure compensation equipment. Cases with inability to use both
equipment was assumed to be technically infeasible. Economic feasibility was studied
by calculating NPV. NPV was calculated based on total installed cost and energy
savings from STHE. Study of weight, size and footprint of STHE was performed.
Sensitivity analysis of NPV with equal percentage variation and more realistic variation
of STHE design parameters was also done.
The project was found to be both technically and economically feasible. Heat duty was
7.6 MW for 1-2 STHE and 10 MW for 2-4 STHE. Placing 8 STHE in parallel gave
almost negligible energy loss from pressure drop. NPV varied between -167 MNOK and
25.2 MNOK for different test cases. Internal tube diameter of 0.051m gave highest
NPVs. Highest NPV for 1-2 STHE structure was 25.2 MNOK and was found by placing
2 STHE in parallel. Highest NPV for 2-4 STHE structure was 24.59 MNOK and was
found by placing 3 STHE in parallel. Cost of electricity gave highest sensitivity for real
case scenario while inlet temperature of CO2 gave highest sensitivity for equal
percentage variatio
The impact of waste heat recovery unit installation on the operation and control of the raw meal department at Norcem Brevik
No full textAs a step towards net-zero emissions in the future, a CO2 capture facility is under construction at the cement plant Norcem in Brevik. This will reduce emissions by 400 000t/yr. To utilize waste heat from the cement production a waste heat recovery unit will be installed in the raw meal department, utilizing the available waste heat from the kiln preheater. With altered temperatures and flow rates, this report will seek to find the impact of these changes on the production capacity.
For normal WHRU operation, the production capacity should not be affected since the needed temperatures and flow rates are available. The challenge will be in controlling the pressures to reach the desired flow rates and the corresponding temperatures.
With the reduced water content in the flue gas from the preheater, the saturation temperature will be reduced. This will in turn allow for a reduction in the mill inlet temperature and recovery of an additional 1.92MW of heat. This is dependent on sufficient residence time for the raw materials to reach complete evaporation of water.
Further, the work has investigated the impact of ambient air leaking into the process and how the removal of this would impact the system. Results indicate that complete will cause a hot gas deficit and is therefore not an option. Partially sealing the system will allow for an additional 2.4MW of heat recovered during LA production. For STD the sealing will only cause increased outlet temperatures and no further heat recovery will be possible
Design of Electrified Calciner for Direct Capture of CO2 from Cement Raw Meal
No full textThe main focus in this thesis is on designing an electrified calciner for direct CO2 capture from cement raw meal, investigating various operating conditions using CPFD simulations. The calciner, a binary fluidized bed reactor with several immersed electrically heated cylinders, includes the raw meal (fine powder <200µm) and coarse lime particles (400µm-800µm). The electrically heated cylinders immersed in the bed provide energy both for heating up the raw meal to calcination temperature and for the endothermic calcination reaction. The design has been made using mass and energy balance as well as fluidized bed calculations. The reactor performance is deeply investigated in different operating conditions using CPFD simulations. Key findings show that efficient spreading the raw meal over the heat source (hot cylinders) and preheating the meal can improve the calcination degree in the reactor. Also, the hotter the cylinders (up to 1150℃) the higher the calcination degree. The designed reactor showed a performance of 90% calcination degree for a preheated meal to 720℃ and a hot cylinder temperature of 1150℃. Also, for a 20℃ cold meal, having 1150℃ wall temperature of hot cylinders can lead to almost 70% calcination in the reactor. It should be noted that the more calcination the more gas production and higher particle entrainment. Another investigated factor was the fluidization velocity which has been calculated between 0.2 m/s-0.8 m/s. Simulation results showed that 0.3 m/s works best in terms of mixing and fluidization efficiency and 0.8m/s shall be avoided as it makes even coarse particles escape the bed very quickly. The results of this study also showed that the fluidization velocity has the most effect on the residence time of particles. Having 0.2 m/s fluidization velocity leads to almost 30 s average residence time of fine particles, for the case with 0.3 m/s it is decreased to 24 s while for the case with 0.8 m/s fluidization velocity, the average residence time is only 5 seconds
Dynamic Modelling and Simulation of Raw Meal Calcination for Isothermal Boundary Conditions
Full text linkThis article describes modelling and simulation of heating and calcination of raw meal particles. The purpose is to determine the time required to obtain a certain calcination degree for particles that are exposed to surroundings with a specified temperature. The impact of applying different reactor temperature values and different particle sizes is investigated. The aggregated calcination degree as a function of time is calculated for a typical raw meal with a specified particle size distribution and with different contents of CaCO3 in different size classes. The developed model can be used as a basis for determining the required size of potential new calciner reactor types
Supporting Dataset for “Global evidence map of feedstock portfolios in biomass- and waste-to-X technologies”
No full textThis dataset supports a global evidence map of feedstock portfolios reported across biomass- and waste-to-X conversion technologies. It contains technology-specific labelled feedstock datasets, reference-record datasets with assigned record IDs, summary distributions and shares in Excel and CSV formats, files mapping absolute-hazard feedstocks to List of Waste (LoW) codes, a reference LoW classification file, and supplementary tables associated with the study. Together, these files make feedstock assumptions, label assignments, hazard-related classification, and supporting evidence explicit, auditable, and reusable for comparative sustainability analysis, policy interpretation, and future method development
Modelling and Simulation of CO2 Capture through Aqueous Indirect Mineralization using CaO-containing By-products
Full text linkThe amount of CO2 in the atmosphere is continuously increasing, resulting in climate change and global warming. Industrial processes contribute a substantial share in the amount of CO2 released to the atmosphere. On the other hand, different types of wastes and by-products are being produced by different industries which are deemed pollutants and require energy and capital to be safely managed through a circular economy perspective. A solution to simultaneously tackle both the CO2 emission and waste pollution problems would be of high value. CO2 sequestration by mineralization of CaO-rich industrial wastes is one potential solution. In such a process, CO2 reacts with the CaO in the waste and CaCO3 is produced. This product is thermodynamically stable and has multiple uses. Many studies in the literature have reported use of various CaO-rich wastes to capture CO2, but they are mostly based on labscale experiments, and mostly the focus is on the chemistry of the suggested processes. Hence, there is a need to study the technical and economic feasibility of up-scaled industrial versions of such processes. In this study, four different aqueous indirect mineralization processes applying different chemicals, all with a relatively high performance documented from laboratory experiments, are scaled up to industrial size with a CO2 capturing capacity of 400 t/y using an in-house-made process simulation tool. Furthermore, an economic analysis and environmental assessment are conducted for all processes, and the results are compared. Finally, parameters impacting the techno-economic feasibility of each process are evaluated through a sensitivity study. The results indicate that the potential of capturing CO2 and producing CaCO3 can be as high as 530 kg and 1200 kg per ton of the waste while the yearly energy consumption can be as low as 0.7 kWh per kilogram of captured CO2. The aqueous indirect mineralization of CO2 can be profitable and the emitted CO2 by the process can be so low as 6% of the captured amount.publishedVersio
Supplementary data and code for: Replacing natural gas in Norwegian methanol production: A national-scale MILP optimization of a waste-to-methanol supply chain
No full textThis dataset accompanies the paper "Replacing natural gas in Norwegian methanol production: A national-scale MILP optimization of a waste-to-methanol supply chain". It contains all input data, processing code, optimization results, and supporting documentation needed to reproduce the study in full.
The study develops a deterministic mixed-integer linear programming (MILP) model to evaluate whether domestic Norwegian waste and biomass resources can support a national upstream supply chain for methanol production, as a long-term substitute for natural gas. The model covers 356 mainland Norwegian municipalities and five industrial hub nodes as potential conversion sites, 110 approved coastal ports as aggregation and export points, and six feedstock-specific thermochemical conversion modules: hydrothermal liquefaction of food waste and sewage sludge, fast pyrolysis of woody waste and forest harvest residues, and thermal cracking of household and industrial plastic waste. For each module, bio-oil yield, capital cost, operating cost, electricity demand, external heat demand, and emission intensity parameters are derived from the peer-reviewed techno-economic literature using triangular fuzzy numbers and defuzzified into single planning values before optimisation.
The model determines which conversion plants should be activated, how much feedstock should be processed at each site, and how the resulting waste- and biogenic-derived oil (WBD-oil) should be routed to coastal ports, under four cost- and emission-constrained scenarios. Each scenario is solved using a lexicographic two-pass procedure: the first pass maximises annual WBD-oil delivered to port, and the second pass minimises total annual system cost while preserving the maximum output achieved in the first pass. Transport distances between supply nodes and ports are computed using the Open Source Routing Machine (OSRM) with real Norwegian road-network data, capturing the routing constraints imposed by fjord and mountain geography.
The deposit is organised into four folders. The input data folder contains all raw feedstock statistics from Statistics Norway (SSB), municipality boundary and port registry geospatial files, and four parameter workbooks documenting the techno-economic, yield, emission, and minimum capacity assumptions with full literature traceability. The pipeline folder contains six sequentially numbered Python scripts covering node construction, port table assembly, distance matrix computation, cost and emission parameter generation, MILP optimisation, and results analysis, each accompanied by a detailed code manual. The results folder contains 31 publication-quality figures and 10 statistics tables generated by the analysis script, consolidated into a single Excel workbook. The data descriptor folder contains a variable dictionary covering every column in every deposit file, provided in both Word narrative and Excel lookup table formats. An interactive Leaflet.js map visualising the optimised supply chain across all four scenarios is included at the deposit root
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