Hua Jiang Huang

Process modeling and analysis of pulp mill-based integrated biorefinery with hemicellulose pre-extraction for ethanol production: a comparative study.

Pulp and paper mills represent a major platform to use more effectively an abundant, renewable bio-resource - wood. Modification of the modern day pulp mills into integrated forest biorefineries (IFBR) presents an excellent opportunity to produce, in addition to valuable cellulose fiber, co-products including fuel grade ethanol and additional energy, thus resulting in increased revenue streams and profitability and potentially lower the greenhouse gas emissions. A process model to simulate the integrate forest biorefinery manufacturing pulp and other co-products has been developed. This model has been used to compare three integrated biorefinery scenarios: the conventional Kraft pulping process, the pulp mill-based IFBR with hemicelluloses extraction prior to pulping for ethanol production, and the pulp mill-based IFBR with both pre-extracted hemicelluloses and the short fiber for ethanol production. Based on a fixed feedstock throughput of 2000 dry Mg wood/day, results show that the pulp mill-based IFBR with both pre-extracted hemicelluloses and the short fiber cellulose converted to ethanol can produce 0.038 MM m(3) (10.04 MM gal) ethanol per year at a minimum ethanol selling price (MESP) of

Reaction Kinetics of the Hydrothermal Treatment of Lignin

491/m(3) (

Separation and Purification Technologies in Biorefineries

1.86/gal). The economic feasibility of IFBR can be further improved by using further improvements in the pre-extraction process, other biomass such as corn stover for producing ethanol, and taking advantage of the economies of scale.

Modeling Biomass Gasification Using Thermodynamic Equilibrium Approach

Lignins derived from abundant and renewable resources are nontoxic and extremely versatile in performance, qualities that have made them increasingly important in many industrial applications. We have shown recently that liquefaction of lignin extracted from aspen wood resulted in a 90% yield of liquid. In this paper, the hydrothermal treatment of five types of lignin and biomass residues was studied: Kraft pine lignin provided by MeadWestvaco, Kraft pine lignin from Sigma-Aldrich, organosolv lignin extracted from oat hull, the residues of mixed southern hardwoods, and switchgrass after hydrolysis. The yields were found dependent on the composition or structure of the raw materials, which may result from different pretreatment processes. We propose a kinetic model to describe the hydrothermal treatment of Kraft pine lignin and compare it with another model from the literature. The kinetic parameters of the presented model were estimated, including the reaction constants, the pre-exponential factor, and the activation energy of the Arrhenius equations. Results show that the presented model is well in agreement with the experiments.

Modeling of gas–solid chemisorption in chemical heat pumps

Separation and purification processes play a critical role in biorefineries and their optimal selection, design and operation to maximise product yields and improve overall process efficiency. Separations and purifications are necessary for upstream processes as well as in maximising and improving product recovery in downstream processes. These processes account for a significant fraction of the total capital and operating costs and also are highly energy intensive. Consequently, a better understanding of separation and purification processes, current and possible alternative and novel advanced methods is essential for achieving the overall technoeconomic feasibility and commercial success of sustainable biorefineries.

Process Modeling of Comprehensive Integrated Forest Biorefinery—An Integrated Approach

In this paper, the thermodynamic equilibrium models for biomass gasification applicable to various gasifier types have been developed, with and without considering char. The equilibrium models were then modified closely matching the CH4 only or both CH4 and CO compositions from experimental data. It is shown that the modified model presented here based on thermodynamic equilibrium and taking into account local heat and mass considerations can be used to simulate the performance of a downdraft gasifier. The model can also be used to estimate the equilibrium composition of the syngas. Depending on the gasifier type and internal fluid flow, heat and mass transfer characteristics, with proper modification of the equilibrium model, a simple tool to simulate the operation and performance of varying types of biomass gasifier can be developed.

Inactivation Kinetics of Yeast Cells during Infrared Drying

Abstract A model coupled the chemical kinetics with heat transfer was applied for simulation of the dynamic behavior of the gas–solid fixed-bed reactors used in chemical heat pumps (CHP). The kinetic parameters and the thermal parameters were identified, respectively. Good agreement was found between the simulation and the experimental data. Moreover, the sensitivity of the global advancements and the radial temperature profiles to the thermal parameters was analyzed. The thermal capacity of the reactive medium has little influence on the global advancement, while the effective thermal conductivity of the medium has an apparent effect on the global advancement. The influence of the effective thermal conductivity on the global advancement is significant until its value is larger than 15 W m −1 K −1 . The contact heat transfer coefficient between reactive salt and reactor wall has less influence on the global advancements and the radial temperature profiles when its value is higher than 800 W m −2 K −1 . This model can be used for optimal design of CHPs, optimization of the operation conditions, and determination of the influence of various parameters on the reactor performances, including the kinetic and thermal parameters, the operational parameters (imposed pressure and temperature), and the configuration parameters of the medium or reactor (geometry and dimensions).

A Kinetics Study on Hydrothermal Liquefaction of High-diversity Grassland Perennials

The key to expanding the energy supply, increasing energy security, and reducing the dependency on foreign oil is to develop advanced technologies to efficiently transform our renewable bioresources into domestically produced bioenergy and bioproducts. Conventional biorefineries, i.e., forest products industry’s pulp and paper mills with long history of sustainable utilization of lignocellulose (wood), offer a suitable platform for being expanded into future integrated forest biorefineries. Due to the pre-existing infrastructure in current forest products operations, this could present a very cost-effective approach to future biorefineries. In order to better understand the overall process, technical, economic, and environmental impacts, a detailed process modeling of the whole integrated forest biorefinery is presented here. This approach uses a combination of Aspen Plus®, WinGEMS®, and Microsoft Excel® to simulate the entire biorefinery in detail with sophisticated communication interface between the three simulations. Preliminary results for a simple case study of an integrated biorefinery show the feasibility of this approach. Further investigations, including additional details, more process options, and complete integration, are currently underway.

Separation and purification processes for lignocellulose-to-bioalcohol production

In this study, aqueous yeast suspensions were used to investigate the effects of drying (in an infrared heating environment) on the survival of yeast. The processes were modeled mathematically using a range of kinetics rate equations. The model parameters for each kinetic rate expression were obtained using a Matlab optimization procedure and the more suitable models describing the inactivation processes were identified. In order to provide the data for model validation, experiments were conducted using freshly prepared yeast suspensions. Additional experiments were also performed that further demonstrate the protective effects of sucrose and skim milk solids on yeast survival during drying. The simple Arrhenius equation was found to be a good model for predicting yeast survival during the control experiments, when heat was applied without dehydration occurring. Models incorporating both temperature and moisture content were more effective in describing yeast inactivation during drying. The model that gave the best predictions included the drying rate and the rate of temperature change as variables; the predicted activation energy for yeast deactivation was closest to that obtained from heating-only experiments in comparison with the other models examined. The results from this work are discussed and future prospects are suggested.

Simulation of an industrial trickle bed hydrogenation reactor in the pulsing flow regime

Abstract Modeling of the liquefaction reaction kinetics for the low-input high-diversity mixtures of native grassland perennials was studied. The highest liquid yield of 82% was achieved within a short residence time of 1 minute at 374°C and 22.1 MPa. Seven possible reaction schemes and kinetic models were developed and compared. The unknown kinetic parameters of each model were estimated by nonlinear least square method. Model 3, assuming that biomass first decomposes to condensable hydrocarbons or tars (liquid products), gaseous products, and solid chars via three competitive reactions and then tars are subjected to a second cracking reaction producing gases, is found to be the best one closely matching the experimental yield data obtained from liquefaction of prairie grasses. The effects of temperature on reaction rate constants for all the reactions except the biomass conversion to char were best described by Arrhenius-type equations. The model developed here in addition to helping better understand the fundamentals of reaction kinetics of biomass liquefaction is also helpful for prediction of three lumped products—liquid products, gaseous products, and solid chars, and rough design of biomass liquefaction reactors and subsequent techno-economic analysis of the process.