Mobile Pyrolysis Units Research Articles

Continuous In-woods Production of Biochar Using a Trailer-mounted Air Curtain Burner.

Fuel treatments and other forest restoration thinning practices aim to reduce wildfire risk while building forest resilience to drought, insects, and diseases and increasing aboveground carbon (C) sequestration. However, fuel treatments generate large amounts of unmerchantable woody biomass residues that are often burned in open piles, releasing significant quantities of greenhouse gases and particulates, and potentially damaging the soil beneath the pile. Air curtain burners offer a solution to mitigate these issues, helping to reduce smoke and particulates from burning operations, more fully burn biomass residues compared to pile burning, and eliminate the direct and intense fire contact that can harm soil beneath the slash pile. In an air curtain burner, burning takes place in a controlled environment. Smoke is contained and recirculated by the air curtain, and therefore burning can be conducted under a variety of climatic conditions (e.g.,wind, rain, snow), lengthening the burning season for disposal of slash material. The mobile pyrolysis unit that continuously creates biochar was specifically designed to dispose of residual woody biomass at log landings, green wood at landfills, or salvaged logged materials and create biochar in the process. This high-carbon biochar output can be used to enhance soil resilience by improving its chemical, physical, and biological properties and has potential applications in remediating contaminated soils, including those at abandoned mine sites. Here, we describe the general use of this equipment, appropriate siting, loading methods, quenching requirements, and lessons learned about operating this new technology.

Impact of biochar amendments on soil water and plant uptake dynamics under different cropping systems

AbstractApplication of biochar amendments in agricultural systems has received much attention in recent years. In this study, we assess the 5‐year impacts of biochar application on soil water and plant interactions for an irrigated fresh market tomato (Solanum lycopersicum) and a rainfed pasture (Poaceae) cropping system. In particular, we focus on three varieties of locally produced biochar from agricultural waste materials—almond shell, walnut shell, and almond pruning residues that are pyrolyzed using a mobile pyrolysis unit. We used the soil hydrological model HYDRUS‐1D to explicitly track seasonal and annual soil water fluxes through changes in water retention, drainage, evaporation, and plant water uptake under biochar application. Modeling results show that the application of biochar at 5% increased soil water availability within the top 20 cm for a rainfed system, irrespective of biochar amendment type. This is clearly indicative of higher plant water uptake and greater water use efficiency (WUE) under biochar application. In contrast, a similar biochar amendment for the irrigated system did not affect WUE, instead reducing seasonal soil evaporation loss and thereby reducing irrigation demand. In both cropping systems, year‐to‐year variability in precipitation significantly impacted the total amount of water saved under biochar application with certain amendments retaining more water than others. Given that biochar application increased water retention irrespective of cropping systems, we further used a simple approach to determine yield trade‐off, if any, between control and biochar treatments. Our economic balance clearly demonstrates that the water saved by amending soil with biochar does not offset the yield disparity if compensated with carbon credits and therefore, application of biochar should be actively considered for both its direct and indirect benefits to potential greenhouse gas mitigation (e.g., diverting orchard waste from open burning), water savings, and soil health.

Valorization of forest waste biomass by catalyzed pyrolysis

Harvesting of forest residual biomass contributes to regulating wildfires during hot and dry seasons. The collected biomass can be converted into liquid biofuel by pyrolysis. Simple pyrolysis procedures such as slow pyrolysis will allow to dimension and design of mobile pyrolysis units to avoid biomass transportation fees and guarantee efficient management of forest residues. Portuguese forest wastes, particularly biomass from maritime pinus and eucalyptus globulus, were characterized by thermogravimetry and pyrolyzed in a fixed bed reactor, at 698 K, using commercial alkali carbonates and zeolites, bauxite ores, and marble dust as catalysts. Pyrolysis data for mixed biomasses showed the existence of synergy effects. The catalytic pyrolysis experiments led to improved bio-oil quality for all the tested catalysts. The bio-oil produced from pyrolysis with sodium carbonate was the most volatile, since the maximum peak of the volatilization rate is at 390 K, while the bio-oils produced by the remaining catalysts have maximum volatilization at 410 K. Marble dust, a waste from ornamental stones industry, revealed excellent catalytic properties during biomass pyrolysis, allowing an improved bio-oil yield with a decrease in the oxygen-containing functional groups.

Techno-economic analysis reveals the untapped potential of wood biochar

The United Nations estimates the rate of deforestation over 10 million hectares per year, with additional infested wood available due to drought, bark beetle calamity and other damage vectors. Processing the hard-to-reach infested wood into biochar via mobile pyrolysis units seems to be a good option for fire prevention. However, since most biochar is currently produced mainly from biological waste, there is not enough experience with wood biochar on a large scale. Review of current knowledge, followed by techno-economic assessment reveals that following the chemical composition of the feedstock, wood biochar outperforms other types of biochar in terms of high porosity. Therefore, wood biochar shows excellent results in increasing the amount of plant-available water content in soil and appears to be an excellent tool for recycling nutrients (especially into plant-available forms of phosphorus and nitrogen). The overall positive effects of biochar application change from abiotic to biotic over time because as it decays, many of its physical properties disappear, but it can boost soil microbial communities on which soil fertility depends. As global climate change creates a wide range of factors that damage forest cover, wood biochar consequently represents untapped potential in the field of soil, nutrient, and energy management.

Influence of biomass type on the composition of bio-oils from ablative fast pyrolysis

One of the easiest ways to minimize the overall costs of bio-oil production is to minimize biomass transportation and, thus, pyrolysis should be performed at or close to the biomass original location. Thus, we applied ablative fast pyrolysis (AFP), as the only potentially mobile pyrolysis unit, to convert residual lignocellulosic biomass into bio-oil. Four different biomass types were converted to bio-oils: beech and poplar wood, straw and miscanthus. To study reliably the influence of biomass type on bio-oil yields, physicochemical properties and composition, pyrolysis was carried out at a constant temperature of 550 °C. Titrations and spectroscopic methods were used for the characterization of the main oxygenate groups. GC–MS was used for the quantification of more than 120 volatile compounds. Such a thorough analytical study of AFP bio-oils, heretoforemissing in scientific literature, allowed us to reliably discuss the differences in bio-oils’ relative to the knowledge of biomass composition. Significant differences between the bio-oils were observed, with the lowest content of carboxylic and carbonyl groups in the straw bio-oil. The amount of carboxylic and phenolic groups in all the bio-oils was in the typical range observed for bio-oils unlike the carbonyls´ and levoglucosan content, which was lower than typical for bio-oils from other pyrolysis units.

The development of a cost model for two supply chain network scenarios for decentralized pyrolysis system scenarios to produce bio-oil

Bio-oil, produced through fast pyrolysis, can act as an intermediate, which can be further upgraded to biofuels. Fast pyrolysis is done in either a centralized or a decentralized (mobile pyrolysis system [MPS]) system. In a centralized system, biomass is transported to a plant to produce bio-oil, which is upgraded in the same unit, while in a decentralized system, the mobile plant is moved to the forest to produce bio-oil, which is transported to an upgrading facility. The objective of this study is to develop supply chain models and conduct a techno-economic assessment of bio-oil production in these two systems using the developed models. For both systems, the bio-oil plant capacity is considered to be 2000 dry t d−1. Because the capacity of an MPS ranges from 10 to 100 dry t d−1, several mobile pyrolysis units are required to achieve the target bio-oil produced in the base case capacity. In this study, models were developed for each supply chain network allocation scenario/configuration for MPS site location (the radial scenario and the truncated scenario) and four relocation time scenarios were assumed (yearly, semi-annually, quarterly, and monthly). Then, bio-oil production costs were evaluated and compared those with a centralized plant. For a 2000 dry t d−1 biomass plant, bio-oil production costs are 0.241$ L−1, 0.349 $ L−1, and 0.407 $ L−1 for the centralized plant, the MPS truncated scenario (100 dry t d−1 MPS unit, yearly relocation), and the MPS radial scenario (100 dry t d−1 MPS unit, yearly relocation), respectively.

Mobile demonstration unit for fast- and catalytic pyrolysis: The combustion reduction integrated pyrolysis system (CRIPS)

A mobile pyrolysis unit, designed to process biomass at a rate of 83.3 kg h−1 (two metric tons per day, MTPD) has been developed, constructed and its operation demonstrated for on-farm or in-forest production of pyrolysis oil (bio-oil). The trailer-mounted pyrolysis apparatus is based on the combustion reduction integrated pyrolysis system (CRIPS), a patented, dual fluidized bed, biomass pyrolysis design developed by USDA and the University of Pretoria. The mobile design goal was to demonstrate efficacy of on-farm production and coordinate station-to-station operation to simulate a collective system of several unit operations within a distributed/satellite system of pyrolysis biorefinery. Key design features that provide utility for remote operations including in-situ (on-trailer) generation of heat and electric power required for self-sufficiency were tested at this scale. Extensive trials on three feedstocks important to US agriculture, namely woody biomass, switchgrass and horse litter, were conducted. The results show that a processing rate of up to 40 kg h−1 (approximately 1 MTPD) was successful and easily achievable for the said biomass on the trailer; however, beyond this rate operational problems such as pressure imbalances between the dual-bed reactors were encountered, hampering process control. The operation of the CRIPS under catalytic pyrolysis conditions was also successful with catalyst regeneration readily achievable with the design. Bio-oil yield for neat/traditional and catalytic pyrolysis were in the 45% and 5–10% ranges respectively, similar to lab scale, demonstrating production of large volumes of bio-oil on-farm. Bio-oil quality for catalytic pyrolysis was consistent over several hours on stream due to continuous catalyst regeneration that the design affords yielding high levels of BTEX compounds; however, deactivation due to alkali contamination was noticeable at cumulative biomass to catalyst ratios of > 6/1. Compared with laboratory scale results, non-catalytic pyrolysis product quality for the demonstration scale wavered between that of regular pyrolysis oil produced under nitrogen atmosphere and that of the tail-gas reactive pyrolysis (TGRP) as partial recycle of effluent gas was possible with the mounted CRIPS design. With successful demonstration at 1 MTPD capacity the mobile system meets the technology readiness level for pre-commercial design suggested for blueprints (i.e. development of full-scale prototype), however more testing is underway to remove the bottlenecks impeding operation at the full-scale design.

Design and development of a novel centrifuge ablative pyrolysis approach for biomass conversion to bio-oil and bio-char

Pyrolysis has evolved as a key pre-treatment step to produce renewable fuels and chemicals from agricultural and forestry residues. In the past few years, there have been different directions in the development of pyrolysis reactors. For example, in vortex and cyclone approaches, biomass particles are suspended in a flow of high supersonic velocities to ensure enough centrifugal forces for pressing the particles against the heated reactor surface. Although simple in design, the requirement of large volumes of carrier gases necessitates cumbersome downstream gas separation, resulting in thermodynamic penalties and higher capital equipment costs. In ablative systems, with little or no carrier gases, the key challenge relates to using an appropriate mechanism to continuously apply forces on biomass particles during pyrolysis. In a recent alternative approach, thermo-mechanical rotors at very high rpm have been used to create the required centrifugal forces for pressing the biomass particles against the heated walls of a concentric shell. In the current approach, a modular centrifuge pyrolysis system has been designed using Biot and Thiele numbers as key constraints for characterizing ablative regimes. Unlike other centrifuge pyrolysis reactors, the novel rotor mechanism incorporated in this reactor system facilitates constant centrifugal force as well continuous propagation of biomass feeds. The 10 kg/hr thermo-mechanical pyrolysis system has been successfully commissioned using hardwood sawdust. Properties of bio-oil and bio-char produced in this new reactor have been compared to products from fluid bed pyrolysis system. In addition to its compact and modular design suitable for mobile pyrolysis units, it can be operated in variable regimes of pyrolysis, e.g., slow to fast modes, allowing adjustable product distribution.

Supplying renewable energy for Canadian cement production: Life cycle assessment of bioenergy from forest harvest residues using mobile fast pyrolysis units

Cement production contributes over 5% of global greenhouse gas (GHG) emissions. Heavy manufacturing industries like cement production continue to rely primarily on fossil fuels for primary energy production and have limited renewable energy options. This study used life cycle assessment (LCA) to quantify the potential environmental benefits of substituting bio oil and biochar from mobile fast pyrolysis of forest harvest residues for fossil fuels in an average cement plant in Québec, Canada. Bioenergy Pathways for cement production showed reductions in non-biogenic GHG emissions as high as 50% relative to the Reference Pathway for energy provision in the plant. The use of bio oil and biochar from mobile pyrolysis units increased the share of renewable energy in the cement plant energy mix from just under 15% in the Reference Pathway up to 47% and 73% in the Bioenergy Pathways, depending on the scale of fuel substitution. Bioenergy Pathways also led to decreases in potential acidification, ozone depletion, respiratory effects, and eutrophication impacts, with slightly higher contributions to smog-forming emissions. The environmental and socioeconomic sustainability of fast pyrolysis units are strongly linked to the availability of, and proximity to, sufficient forest harvest residues, such that regional-level analysis of feedstock availability is needed prior to wide-scale deployment of these systems.

Ablative Pyrolysis of Wood Chips: Effect of Operating Conditions

AbstractWe pyrolyzed entire wood chips (5×15 mm) in a new ablative reactor with the goal to evaluate the possibility to minimize grinding costs before pyrolysis. The effects of the operating parameters on the product yields and composition were investigated. Our results revealed that the bio‐oil yield in the ablative reactor was favored at a moderate pyrolysis temperature of 500 °C, low initial thickness of the wood chips layer (≤5 mm), low applied pressure on the wood chips (≤0.5 bar), and with the rotation of the bowl (≥100 rpm). The temperature profile of the wood chips indicated that the ablative pyrolysis of thick layers is limited strongly by heat transfer rates. The maximum bio‐oil yield obtained was approximately 60 wt %. The bio‐oil elemental composition was determined mostly by its water content and that of char was affected primarily by the temperature. The knowledge of how operating conditions affect the ablative process can be used in the design of continuous mobile pyrolysis units in the future.

Pyrolysis of whole wood chips and rods in a novel ablative reactor

The ability to carry out pyrolysis of entire wood chips and rods instead of small particles would be of great value for mobile pyrolysis units, because of the large possible savings in grinding costs (7–9% of total process costs). With this goal in mind, we designed and constructed a novel lab-scale ablative reactor for fast pyrolysis of entire wood chips and even wood rods, converting those directly into a high yield of bio-oil for the first time. The bio-oil yield from fast pyrolysis of wood chips (10×20mm) was as high as 60wt.%, similar to that from wood crumbles (2×2mm). Additionally, the yield and composition of bio-oil from ablative pyrolysis were in the same range as those obtained from a fluidized bed reactor using <1mm particles, with the small differences (slightly lower yield and HHV, and higher water content) attributed to the longer vapor residence times in the ablative reactor, which promote secondary reactions. We modeled the heat transfer characteristics of this semi-batch system, and comparison with experimental measurements confirmed that radiation from the hot components does not significantly decompose the wood prior to direct contact with the hot metallic surface in ablative pyrolysis. The findings of this work have the potential to lead to new developments for small-scale, mobile pyrolysis units for the disposal of forest residues.

RESEARCH OF STRAIN-STRESS STATE OF A PYROLYSIS MODULE DESIGN CONSIDERING THE EXCESS PRESSURE IN THE REACTOR

Oil sludge treatment is an important environmental challenge. It should be noted, that oil sludge is a valuable raw material, which should be refined to the extraction of useful products, as it yields environmental and economic effect. Among the variety of methods and techniques, burning is the most common one. But the most effective, including an environmental point of view is the pyrolysis, especially low temperature as hydrocarbons, included in the oil slurry from the combustion emit a large amount of toxic combustion products.. It makes more economical sense that the relatively small amounts of oil sludge, which are distant from the stationary treatment units, are to be treated at the locations. It calls for modular build mobile units that are placed on off-road vehicles. The main problems at mobile pyrolysis units origination are performance and reliability assurance at high temperatures, that are necessary for the treatment process, high capacity. Therefore, in mobile applications, as well as in stationary, it is necessary to provide the technical and technological methods of uniform heating throughout the volume of the sludge as existing installations have a long process due to the preferential heating only the surface layers of sludge and location of critical nodes in the areas of minimum temperatures to reduce the stress-strain state. This article introduces a model, fully describing the construction, and all the components of the oil sludge treatment unit. Strain-stress state analysis of unit’s bottom individually and of the pyrolysis module integrally considering the excess pressure in the reactor for different configurations of the pyrolysis module design.

Optimized Feedstock Logistics for Mobile Pyrolysis Units in the North Central Region of the U.S.

<abstract><title><italic>Abstract.</italic></title> Mobile pyrolysis units have the potential to greatly simplify feedstock logistics by moving pyrolysis equipment to the feedstock production fields to produce bio-oil. The concept is to use mobile pyrolysis units to convert low-density biomass to high-density bio-oil to minimize feedstock transportation costs. A recently published GIS program was used to assess feedstock availability for mobile pyrolysis units in the North Central (NC) region using GIS databases. The feedstocks chosen for this study were corn stover, energy sorghum, and switchgrass. The GIS program identified optimum locations for mobile pyrolysis stations based on feedstock availability and calculated the routes and distances between the optimum pyrolysis stations. The GIS program utilized a harvest grid concept with the mobile pyrolysis unit located in the center of a square grid cell. It was assumed that the mobile pyrolysis units would move on discrete time steps of 1, 2, 4, 6, 8, 10, and 12 months (stationary). The harvest grid sizes ranged from 2.4 to 9.6 km for corn stover, from 5.0 to 23.0 km for energy sorghum, and from 3.3 to 12.0 km for switchgrass, depending on move times. In the NC region, the distances required to move the mobile pyrolysis unit from one location to the next varied from 2.1 to 138.7 km for corn stover, from 4.4 to 81.0 km for energy sorghum, and from 3.0 to 60.7 km for switchgrass. The distances required to transport bio-oil to the closest oil refineries ranged from 81.0 to 195.0 km for corn stover, from 365.0 to 522.0 km for energy sorghum, and from 192 to 265 km for switchgrass. Using these optimized feedstock logistics, a total of 14,825,993 barrels (2,357,144,597 L) of bio-oil could be produced by 853 mobile pyrolysis units using 25% of the corn stover in Illinois. In Nebraska, 469,287 barrels (74,610,673 L) of bio-oil could be produced by 27 mobile units using energy sorghum, and 903,812 barrels (143,694,630 L) of bio-oil could be produced by 52 mobile units using switchgrass.

A Geographic Information Systems Program to Optimize Feedstock Logistics for Bioenergy Production for Mobile Pyrolysis Units

<abstract><title><italic>Abstract.</italic></title> A comprehensive decision-making tool was developed to optimize the use of a fleet of mobile pyrolysis units in the North Central region of the U.S. to produce bio-oil from agricultural feedstocks. The concept is to use mobile pyrolysis units to convert low-density biomass to high-density bio-oil to minimize the cost of feedstock logistics. The feedstocks evaluated in this project included corn stover, energy sorghum, and switchgrass. It was assumed that (1) energy sorghum would replace grain sorghum and (2) switchgrass would be grown on Conservation Reserve Program (CRP) land. A Geographic Information System (GIS) program was developed to optimize the movement of mobile pyrolysis units based on an analysis of transportation networks, cropping patterns, feedstock production rates, and oil refinery locations in the North Central region. The locations of existing corn, sorghum, and CRP fields in the North Central region were obtained from the USDA National Agricultural Statistics Service (NASS). Model Builder, a utility in ArcGIS, was used to automate the GIS procedures. Network Analysis, an extension of ArcGIS, was used to find the best route to move the mobile pyrolysis units to new locations and to identify the nearest refinery to receive the bio-crude oil. The feedstock input rate for each mobile pyrolysis unit was assumed to be 40 tons/day.

Effects of temperature on the physicochemical characteristics of fast pyrolysis bio-chars derived from Canadian waste biomass

Bio-chars are produced by means of a mobile pyrolysis unit from fast pyrolysis of different types of Canadian waste biomass including agricultural waste (wheat straw and flax straw), forest residue (sawdust) and animal manure (poultry litter). They were analyzed for their physicochemical changes with pyrolysis temperature (400–550°C). To study the chemical nature of bio-char samples, analyses such as XRD, FTIR, Raman spectroscopy, XPS, SEM, ICP, TGA and electrical conductivity measurements were performed. ICP-MS analysis showed that poultry litter-derived bio-char had the largest concentration of inorganic elements (∼200,000ppm) followed by wheat straw, flax straw and sawdust derived bio-chars. In addition, the alkaline elements were 4–14times that of essential elements (Fe and P) and 18–57times that of heavy elements. Electrical conductivity of bio-chars, a measure of their salinity, was maximum for all samples prepared at 400°C. SEM showed that sawdust derived bio-chars retained relatively less dissociated surfaces compared with other bio-chars. XRD confirmed the presence of sylvite, dolomite and quartz in the bio-chars. The deconvoluted XPS spectra indicated that for all precursors except poultry litter, aromatic/aliphatic carbon portion increased in the corresponding bio-char with the pyrolysis temperature. For all precursors, O/C mass ratio decreased with an increase in the pyrolysis temperature due to the development of compact aromatic structure in bio-char. This result was confirmed by a drastic increase in ID/IG (defect to graphitic carbon) ratio of bio-char samples produced at 550°C from the deconvolution results of Raman spectroscopy. Thermogravimetric analysis showed that biomass decomposition started at lower temperatures for the following order: poultry litter, wheat straw, flax straw and sawdust.

Evaluation of properties of fast pyrolysis products obtained, from Canadian waste biomass

Pyrolysis is known as the most common method for the conversion of waste biomass such as agricultural wastes, forest residues and animal manure to value-added products such as bio-oil and bio-char. Four types of Canadian waste biomass including wheat straw, saw dust, flax straw and poultry litter, collected in Saskatchewan (Canada), were used for fast pyrolysis process using a mobile pyrolysis unit. For each biomass, pyrolysis was performed at three different temperatures (400, 475 and 550°C) to investigate their effects on the properties of products. A comprehensive physical and chemical characterization was conducted for all biomass and pyrolysis products including bio-char, bio-oil and gas phase. Saw dust and wheat straw showed the largest cellulose and lignin contents (37.7 and 20.8wt%, respectively). Poultry litter had the highest ash content (12.3wt%). Amount of bio-oil collected from liquid product increased by an increase in the pyrolysis temperature for wheat straw and poultry litter. Total acid number of bio-oil product decreased by an increase in the pyrolysis temperature. Carbon content of bio-char was in the range of 70–81wt% which was much larger than that for original biomass. The pH for bio-chars derived from the wheat straw and poultry litter was in the range of bases. For all samples, the concentrations of CH4 and H2 in the gas phase increased with an increase in the pyrolysis temperature.

Carbon abatement via treating the solid waste from the Australian olive industry in mobile pyrolysis units: LCA with uncertainty analysis

The olive oil industry in Australia has been growing at a rapid rate over the past decade. It is forecast to continue growing due to the steady increase in demand for olive oil and olive products in the local and regional market. However, the olive oil extraction process generates large amounts of solid waste called olive husk which is currently underutilized. This paper uses life-cycle methodology to analyse the carbon emission reduction potential of utilizing olive husk as a feedstock in a mobile pyrolysis unit. Four scenarios, based on different combinations of pyrolysis technologies (slow versus fast) and end-use of products (land application versus energy utilization), are constructed. The performance of each scenario under conditions of uncertainty was also investigated. The results show that all scenarios result in significant carbon emission abatement. Processing olive husk in mobile fast pyrolysis units and the utilization of bio-oil and biochar as substitutes for heavy fuel oil and coal is likely to realize a carbon offset greater than 32.3 Gg CO2-eq annually in 90% of the time. Likewise, more than 3.2 Gg-C (11.8 Gg CO2-eq) per year could be sequestered in the soil in the form of fixed carbon if slow mobile pyrolysis units were used to produce biochar.