Wildland Fire Laboratory

Thomas H. Fletcher
Chemical Engineering

Steve Smith

Current forest fire Models are based on extensive empirical data for dead vegetation. The models are accurate in predicting the fire spread rate and intensity for conditions similar to the data from which they are based but are less accurate under other conditions. Understanding the combustion characteristics of live vegetation may increase the overall accuracy of forest fire modeling. The lab is designed to burn small samples (single leaf) in an environment similar to a forest fire. The leaf sample is suspended on a cantilever-type mass balance. A thermocouple is placed in a pinhole in the leaf. A flat flame burner and a radiant heating panel can be pulled by a motor to stop under the leaf. The process is captured visually with a camcorder. The images and the temperature and mass are recorded as a function of time through a program written in Labview 6.1. Ignition temperature, time to ignition, flame duration, mass loss, and flame height are determined through the analysis of the data. By changing the moisture content, thickness, and shapes of the leaves different ignition characteristics are observed.

Gas Turbine Combustion Laboratory

Thomas H. Fletcher
Chemical Engineering

This facility was designed to simulate the inlet conditions of gas turbine engines. It matches Mach number and temperatures up to 0.8 and 1200°C respectively. An auxiliary air system allows the experimenter to seed the combustion stream with a cocktail of particles typical of virtually any operating condition of interest to include long-term degradation by ingestion of ambient particulate, biomass burning, coal combustion, or any other particle-laden regime. The express purpose of this facility is to create sample of turbine blade materials with degradation structures typical of actual service life but at a fraction of the cost and time. Details of this facility’s application to the study of GT engine degradation under normal operating conditions were presented by Jared Jensen (thesis title: “The Development of an Accelerated Testing Facility for the Study of Deposits in Land-Based Gas Turbine Engines) in 2004. A condensed version of these findings was presented at the IGTI conference 2004 by Dr. Jeffrey Bons and will later be published in the ASME Journal of Turbomachinery.

Particle Combustion Laboratory

Larry L. Baxter
Chemical Engineering

Black Liquor Combustion

Black liquor is a byproduct from the paper pulping process. It is concentrated and burned in a recovery boiler. Black liquor burns in droplet form. Understanding the combustion process and being able to model the process are significant.
• Single black liquor droplet is burned in a furnace with viewports in three orthogonal directions.
• Imaging from the viewports allows optical surface temperature measurement and 3-D image reconstruction.
• The droplet is suspended on a thermocouple wire that allows for droplet internal temperature profile to be measured.
• The mass loss is also recorded using a high-resolution balance.
• Intermediate-sized particle (ISP) is studied with the addition of the cyclone separators.
• Molecular beam mass spectrometry (MBMS) is used to analyze the off-gas of the droplet combustion.
• Model is being developed for the droplet devolatilization and combustion.

Biomass Particle Combustion

Hong Lu

• Biomass particles commonly have aspect ratios of 3 to 12, which cannot be adequately described using spherical approximations for mass and heat transfer; the combustion process may be controlled by surface area effects.
• An entrained flow reactor is used in this project, which is electrically heated with wall temperature up to 1650 K; the temperature profile along the reactor can be controlled separately by adjusting wall temperatures in each of the four sections;
• This reactor provides about three seconds residence time for biomass particle;
• Optical access is provided, which allows particle images to be obtained in each of three orthogonal directions using imaging pyrometers (high-speed cameras);
• With a 3D particle shape reconstruction code, the particle shape, volume, and surface area data can be generated from particle images;
• The reactor can provide instantaneous particle velocity, surface temperature, size, shape, surface area, volume, and mass loss as functions of particle residence time.

Solids Reactions
Laboratory

Thomas H. Fletcher
Chemical Engineering

Pyrolysis and combustion of solid materials are studied in the Solids Reactions Laboratory in a High Pressure Drop Tube Reactor and in a Flat Flame Burner (FFB). Both facilities can operate with or without oxygen present, and are equipped with sampling probes to separate tars and aerosols from chars. Solid samples are analyzed for elemental composition using a LECO 932 CHNS analyzer. ICP analysis for Ti, Al, and Si provides tracers for verification of mass release. The drop tube experiments can be performed at particle heating rates of ~10⁴ K/s, pressures from 1 to 25 atm, residence times of 100 to 300 ms, and temperatures from 600 to 1300 K. The FFB experiments can be operated at particle heating rates of ~10⁵ K/s, residence times of 20 to 150 ms, and gas temperatures ranging from 1600 to 2500 K, by adjusting the fuel (CO or CH₄), the equivalence ratio, and the flow rates. Particle feed rates in these two reactors are low (1g/hr) to ensure single particle behavior.

Flat Flame Burner Laboratory

Thomas H. Fletcher
Chemical Engineering

Flat Flame Burner

The Flat Flame Burner Laboratory focuses on the formation of soot and char to determine what constitutes these combustion products. Understanding the formation of these undesired by-products may help reduce them in the future. Solid and liquid samples are feed to the center of a Flat Flame Burner (FFB). Soot and char from pyrolysis are pulled into a vacuum collection probe which then separates the soot from the char through the use of a virtual impactor and cyclone apparatus. These two combustion products are collected for further analysis. They may be analyzed to determine elemental compositions of carbon, hydrogen, nitrogen and sulfur using a LECO CHNS-932 analyzer. The combustion gases may also be analyzed during a run through the use of a Fourier Transform Infrared Spectrometer (FTIR). The FTIR allows one to measure the presence and concentration of certain molecules.

The FFB can be operated at various gas temperatures ranging from 900 to 2500 K by changing the gas flow rates and equivalence ratio of fuel (CO) to air. Typical residence times are from 20 to 100 ms with a particle heating rate on the order of ~105 K/s.

Catalysis Combustion Kinetics and Surface Analysis Laboratory

Calvin H. Bartholomew
William C. Hecker
Chemical Engineering

The Catalysis, Combustion Kinetics and Surface Analysis Laboratory focuses research on coal char oxidation, catalysis, and the surface properties of catalysts, coals and chars. The principal objective of this work is to develop models and data which relate oxidation rate parameters for coal chars to their chemical and surface properties. Facilities include:

Combustion and
Reactions Laboratory

Dale R. Tree
Mardson Q. McQuay
Mechanical Engineering

The Combustion and Reactions Laboratory is dedicated to the experimental research and testing of various combustion phenomena. The laboratory includes two pulverized coal reactors, a particle dispersion reactor, and a gas turbine burner. Supporting diagnostic equipment is also maintained and available for numerous combustion and coal-related measurements.

The laminar flow reactor and the CPR can be operated with natural gas or pulverized coal and potentially other experimental fuels. A high pressure particle dispersion chamber is used to study the trajectory of coal particles in high velocity gaseous streams.

Also included in the Combustion and Reactions Laboratory are an optical particle size analyzer and a small chemistry lab where ultimate analysis, coal moisture and gas chromatography can be performed.