Pyrolysis of residues from well-established biochemical processes for biomass conversion into liquid fuel

This project focuses on the pyrolysis of residues from well-established biochemical processes into liquid fuel. The residues examined come from two major conversion processes; wastewater treatment facilities, and biogas digesters. These processes produce low value, unconverted residues that are refractory to further biochemical conversion. Pyrolysis is an aggressive thermochemical conversion process that is ideally suited to such residues. Currently, these residues are viewed as a low-value or waste products that must be disposed of. The environmentally friendly disposal of wastewater sludge is a common problem for many municipalities, where the sludge is often incinerated or disposed of in landfills. Anaerobic digestate can be used as a soil amendment but is often landfilled as waste. The key goal of this project is to find a solution to the disposal issues associated with these residues, while improving the overall process economics, through the production of high quality bio-oil and bio-char streams. Please click Additional Files below to see the full abstract

A NOVEL FAST GAS-SOLID SEPARATOR FOR PYROLYSIS REACTORS

From escalating global concern over the exhaustion of non-renewable energy sources comes an imperative need for the use of renewable resources. Among possible renewable sources and subsequent conversion processes, biomass pyrolysis is a very promising alternative for fuel and chemical production. Previous work has shown that the most effective biomass pyrolysis processes employ downer reactors. Ongoing research at the Institute for Chemicals and Fuels from Alternative Resources (ICFAR) has led to the development of a new downer reactor design for the pyrolysis of biomass feedstock. However, this process requires a gas-solid separator that achieves a minimum spread of the gas residence time distribution – i.e. as near to plug flow as possible. A novel integrated gas-solid inertial separator has been designed for implementation in the downer reactor. This new separator combines both primary separation and solids stripping within the same device. This is intended to decrease the product vapor residence time as well as to reduce the severity of vapor overcracking as compared to other separation methods proposed in the literature. The gas-solid separation section of the new device features a uniflow configuration and a vertical, axial entry with swirl vanes. In the current study, various geometry configurations and operating conditions were tested for their effect on separation efficiency and pressure drop. A 5 cm-diameter separator was tested under cold flow modeling conditions using air, silica sand and glass beads. The sand and glass beads had Sauter mean diameters of 200 µm and 63 µm, respectively. The gas inlet velocity was varied from 1 to 21 m/s and the solid load ranged from 1.1 to 21 wt./wt. The separation length was adjusted from 0 to 2.5 separator diameters. Initial cold flow experiments using silica sand revealed that the separator performance was influenced greatly by separator geometry. Flow deflector blades (i.e. swirl vanes) induced only a very weak swirl to the incoming flow. Hence the primary means of particle collection at the wall was by particle deflection as opposed to imparted centrifugal forces. The optimum separation length was determined to be zero (i.e. deflector blades positioned very near the gas outlet). Solids recovery in excess of 99.99% was achieved at zero separation length. The solids recovery decreased steadily as the separation length increased, to a minimum of 99.78% at 2.5 separator diameters. At long separation lengths, visual observation confirmed that particles were re-entrained in the exiting gas flow above the gas outlet after colliding with the separator wall. Several blade geometries were tested, where the most effective separation was obtained using 30° deflector blades (as measured from the separator vertical axis). Solid recovery was in general not strongly affected by gas inlet velocity or solid loading. Finally, the separator grade efficiency curve was measured from experiments using glass beads

Jiggle bed reactor for testing catalytic activity of olivine in bio-oil gasification

The Jiggle Bed Reactor (JBR) is a batch-wise operating micro fluidized bed reactor that was designed for screening the endothermic catalytic reactions. A vertical actuator attached to the bottom of reactor provides fluidization of the catalytic bed. Induction heating generates the required heat for endothermic reactions inside the catalytic bed so that heat transfer coefficient is similar to that in large-scale fluidized bed reactors. Olivine is a natural magnesium iron silicate mineral that can have catalytic effect in a gasification reaction due to its iron content. However, iron has a redox property; i.e. it can absorb oxygen to convert Fe+2 to Fe+3 and then release the oxygen depending on the oxidative and reductive environment. Therefore, it is important to have a true understanding of iron activity and thus let it undergo an appropriate pretreatment step before injecting the gasification feed. The JBR was utilized to conduct bio-oil gasification tests for syngas production, without added steam or oxygen, at the presence of different prepared olivine particles (calcined with air at 850°C and 1000°C and reduced with hydrogen at 800°C) as well as silica sand. Experiments were conducted at temperature 800°C and at different reaction times. Yield data were compared with equilibrium data obtained from a developed thermodynamic model. Results showed that olivine was an active catalyst for bio-oil gasification when it was initially reduced with hydrogen, providing complete bio-oil conversion as well as maximum syngas yield. However, calcined olivine was inappropriate, as it released oxygen that reacted with the combustible products

Production of biochar and development of predictive methods for determining performance in value-added composite materials

Current pyrolysis technologies are used for the production of liquid bio-oil, solid biochar, and gases, at temperatures in the range of 400-600 °C in the presence of little or no oxygen. Typically, pyrolysis processes have been investigated with the aim of producing the oil and char for their potential value as sustainable sources of energy and chemicals. Biochar, or biocarbon, the carbonaceous residue remaining after the volatile components have exited the biomass material, has typically been used in low value applications such as soil amendment. However, for pyrolysis technology to become fully established, it remains necessary to extract as much value as possible from all product streams. Please click on the file below for full content of the abstract

Life cycle analysis of different biochar production processes for simultaneous waste management and carbon capture credits

Biomass pyrolysis has been extensively investigated to produce biooils, gaseous products and biochar and a number of successful commercial production facilities have been implemented. Gaseous products are mainly utilized for process energy recovery, whereas biooils have found broad applications that vary from food additives to fuels. On the other hand, biochar has attracted a growing interest in recent years as a valuable soil amendment, a precursor for high quality adsorbent materials, as a catalyst, as well as an efficient medium for carbon sequestration. Therefore, biomass pyrolysis can convert waste materials that decompose and generate greenhouse gases into a stable carbon that can offer intrinsic soil amendment properties while sequestering carbon in the soil for hundreds of years, thus representing a net carbon sink. Large scale biomass pyrolysis processes are traditionally based on fluidized bed technologies, rotary kilns, cyclonic contactors, auger or other mechanically mixed reactors. However, all these technologies require addition of external energy and feedstock pre-processing steps. An emerging alternative to produce large quantities of biochar is based on air-curtain carbonators. This technology consists of a combustion process which can handle very large quantities of raw unprocessed biomass materials. The feedstock is partially combusted to generate the process energy while generating quantities of unconverted carbon in the form of biochar and controlling the gaseous emissions by secondary combustion through an air curtain. All the biochar technologies have different impacts on the carbon balance between feedstock, emissions, and products. In addition, depending on the operating conditions and, particularly, the process temperature, the stability of the carbon in the products varies considerably. Consequently, Life Cycle Analysis (LCA) is the essential tool to evaluate the carbon management balance between the waste feedstock and the products, and, consequently, to evaluate the potential net carbon sequestration potential of the biochar. Carbon removal markets and corporate decarbonization have been popular topics in recent months. A growing number of companies are qualifying to sell biochar CO2 Removal Certificates (CORCs). Carbon Future and Puro Earth are the two current markets for biochar carbon removal credits and LCA is required for validation and certification. In this work, LCA was conducted according to ISO 14044:2006, ISO 14067:2018 and Puro Earth Annex A: Biochar Methodology to determine and compare the carbon footprint associated with the production of biochar derived from woody feedstocks, from cradle-to-grave, utilizing large scale biochar production facilities employing different technologies. The functional unit is one metric tonne of biochar, and the primary function is soil conditioning and carbon sequestration. The system boundaries for the cradle-to-grave LCA include transporting waste biomass to conversion facility, processing the biomass into biochar using the conversion technology, drying and packaging the final biochar product, transportation to end-user, and product utilization. The system boundaries are defined by a specific methodology, as waste biomass is transported to the conversion facility for processing. GaBi LCA software was used to conduct the life cycle analysis with information gathered from specific industry and regional databases. The carbon footprint is expressed in tonne CO2-eq. and includes all greenhouse gases, directly and indirectly, related to the process. The end result of the net carbon sequestration is in the form of net carbon dioxide removal certificates (CORCs) resulting from biochar production activity as provided by Puro Earth which can then be monetized and marketed to be purchased by CO2 emitters for offset purposes. The CORCs for the different case-studies investigated were determined to be between 1.2 and 2.5 tonne CO2-eq. per tonne biochar. The LCA methodology developed in this work can easily be implemented to evaluate and validate the net CO2 removal equivalent credits offered by any biochar production technology

Effect of interactions between spray jets on liquid distribution in a fluidized bed

In Fluid CokersTM, banks of spray nozzles are used to inject oil in a bed of hot coke particles. The purpose of this study is to determine whether interactions between spray jets could enhance liquid distribution on hot coke particles, which is crucial to improve the operability and performance of Fluid Cokers. A low temperature experimental model of Fluid Coking was used to measure the liquid distribution. Preliminary screening of nozzle positions employed conductance measurements. A binder solution was utilized to further investigate the most interesting nozzle interactions, by simulating at low temperature the formation of agglomerates during high temperature coking. Adding different dyes to the binder solutions injected by the different nozzles helped determine how nozzles interacted. Three types of spray nozzle interactions were investigated to determine their effect on the liquid distribution. With opposing horizontal spray nozzles, the liquid distribution can be greatly improved when their jets merge slightly, but only when the sprays are synchronized. For vertically separated spray nozzle configurations, interactions can have a detrimental or beneficial impact on liquid distribution depending on the horizontal and vertical distances between jet tips. Interactions between inclined nozzles in the same vertical plane always degrade the liquid distribution when the nozzles are spraying in the same direction, while, when they are spraying from opposite directions, the performance can be improved when the bottom jet is close enough to the top jet. A physical interpretation is provided for all the observations