Fuel-Flexible Gasification-Combustion Technology for Production of H2 and Sequestration-Ready Co2

Abstract

It is expected that in the 21 st century the Nation will continue to rely on fossil fuels for electricity, transportation, and chemicals. It will be necessary to improve both the thermodynamic efficiency and environmental impact performance of fossil fuel utilization. General Electric Energy and Environmental Research Corporation (GE EER) has developed an innovative fuel-flexible Advanced Gasification-Combustion (AGC) concept to produce H 2 and sequestration-ready CO 2 from solid fuels. The AGC module offers potential for reduced cost and increased energy efficiency relative to conventional gasification and combustion systems. GE EER was awarded a Vision-21 program from U.S. DOE NETL to develop the AGC technology. Work on this three-year program started on October 1, 2000. The project team includes GE EER, California Energy Commission, Southern Illinois University at Carbondale, and T. R. Miles, Technical Consultants, Inc.In the AGC technology, coal/opportunity fuels and air are simultaneously converted into separate streams of (1) pure hydrogen that can be utilized in fuel cells, (2) sequestration-ready CO 2 , and (3) high temperature/pressure oxygen-depleted air to produce electricity in a gas turbine. The process produces near-zero emissions and, based on preliminary modeling work in the first quarter of this program, has an estimated process efficiency of approximately 67% based on electrical and H 2 energy outputs relative to the higher heating value of coal. The three-year R&D program will determine the operating conditions that maximize separation of CO 2 and pollutants from the vent gas, while simultaneously maximizing coal conversion efficiency and hydrogen production. The program integrates lab-, bench-and pilot-scale studies to demonstrate the AGC concept.

Chemical Looping Gasification Using Solid Fuels

“…Experiments conducted in the labatory -scale reactor further suggested that a high calcium sorbent to coal ratio ( ∼ 16:1 by weight) was required to avoid CO 2 emission from the reactor. 32 The experimental results also suggest that a 4:1 ratio by weight of calcium sorbent to Fe 2 O 3 enhances H 2 production. 32 A further increase in Fe 2 O 3 , however, will lead to a reduction in H 2 yield.…”

“…As shown in Figure 5.10 , which previously was shown as Figure 1.27 , the Fuel -Flexible AGC Process consists of three interconnected fl uidized -bed reactors. 30 In the fi rst reactor, or the gasifi er, coal partially is gasifi ed with steam to form a mixture of H 2 , CO and CO 2 . The CO 2 generated during the coal gasifi cation is captured in situ by CaO under operating conditions of 750 ° C -850 ° C and 17 -20 atm.…”

“…The rest of the heat carried by the hot exhaust gas stream is recovered and used to drive the gas turbine for electricity generation. 31 The reaction in the oxidizer is as follows:…”

Chemical Looping Gasification Using Gaseous Fuels

“…The GE Process obtains a hydrogen concentration of only 80%. 61 The calcium -based chemical looping process mentioned is discussed in detail in Chapter 5 .…”

“…61.1% CO,35.1% H 2 , and 3.8% CO 2 (mol%) is sent to the bottom of the reactor at a rate of 1,686 mL/min (STP, Standard Temperature and Pressure). The gas composition is chosen to be similar to the syngas generated from a Shell SCGP gasifi er.…”