Justin M. Weber

The Effect of Thermal Treatment of Hematite Ore for Chemical Looping Combustion of Methane

For chemical looping processes to become an economically viable technology, an inexpensive carrier that can endure repeated reduction and oxidation cycles needs to be identified or developed. Unfortunately, the reduction of hematite ore with methane in both batch and fluidized beds has revealed that the performance (methane conversion) decreases with time. Previous analysis had shown that the grains within the particle grew with the net effect of reducing the surface area of the particles and thereby reducing the rate and net conversion for a fixed reduction time. To improve the lifespan of hematite ore, it is hypothesized that if the grain size could be stabilized, then the conversion could be stabilized. In this work, series of tests were conducted in an electrically heated fluidized bed. The hematite ore was first pretreated at a temperature higher than the subsequent reduction temperatures. After pretreatment, the hematite ore was subjected to a series of cyclic reduction/oxidation experiments. The results show that the ore can be stabilized for cycles at different conditions up to the pretreatment temperature without any degradation. Details of the pretreatment process and the test results will be presented.

Experimental Investigation of Gas-Solid Disengagement in Bubbling Fluidized Bed Cold Model

The aim of this experimental study is to investigate the separation performances of a new gas-solid disengagment (GSD) device in a 10 cm bubbling fluidized bed cold model. An impactor separator is designed to be fitted internally onto the loop seal and install in the bubbling fluidized bed based on the impingement separation concept. The effects of operating parameters, such as static bed height, the length of the GSD device’s dip leg, and effect of dip leg porting were examined. The results indicated that a higher static bed height increases the mass of elutriated particles from the bed column. The length of the GSD device’s dip leg has a small effect on its separation ability. A longer dip leg can reduce the amount of particles elutriated due to the reduced pressure it experiences on the solids exit as compared to a shorter dip leg. The addition of fluidization ports to the dip leg has a negative effect on preventing particles from escaping through the gas outlet. The fluidizing gas will bypass the gas inlet of the GSD device through the dip leg and no particles will impact the baffle to be separated from the gas flow. Increasing the diameter of the solid exit for the dip leg increases the efficiency of the GSD device. The higher rate of particles passing through the dip leg reduces the chance of gas flow blockage by particles accumulating in the GSD device. The research concludes that with an effective design for a gas-solid disengagement device will reduce up to 75% of the particles that enter the filtration system that elutriate from the bubbling fluidized bed.

Inverted Brayton Cycle for use with Chemical Looping Combustion

Carbon management is a two-step process in which carbon dioxide is first captured and then permanently stored. This approach can be used to reduce carbon dioxide emissions from power generation point sources. In 2007, a National Energy Technology Laboratory (NETL) report on the performance of fossil energy power plants described the performance impact of carbon dioxide recovery for various plant designs. The electric power sector is also one of the largest producers of carbon dioxide. Therefore, if CO2 emissions must be controlled, then it is reasonable to expect significant changes in the electric power sector of the U.S. economy.