Gasification in Detail – Types of Gasifiers – Entrained Flow Gasifiers
EAGLE, an acronym that stands for Energy Application for Gas, Liquid, and Electricity, is a project funded by the Electric Power Development Company of Japan, in collaboration with Japan’s New Energy and Industrial Technology Development Organization (NEDO). The project goal is to develop a Japanese-built, oxygen-blown, entrained-flow coal gasifier, suitable for multipurpose applications, including the generation of electric power and production of synthetic fuels, chemicals, and hydrogen. The project started in 1995 with feasibility studies and a 150-ton-per-day (tpd) pilot plant was constructed in 2001. Demonstration testing commenced in 2002 and is still in progress. Recent testing includes the evaluation of various coal feedstocks and carbon dioxide (CO2) capture.
The EAGLE gasifier is a two-stage, pressurized, upflow, entrained-flow gasifier with the bottom stage operating in slagging mode, with a second non-slagging stage on top to increase overall gasification efficiency. Figure 1 shows a simplified drawing of the gasifier. Being a two-stage reactor, the EAGLE gasifier is similar to the E-Gas™ gasifier and MHI’s gasifier. Unlike the E-Gas™, the EAGLE gasifier operates with a dry feed and, in contrast to the MHI gasifier, it operates in an oxygen-blown mode. Another unique feature of the EAGLE gasifier is its tangential feed injection and burner system which allows a spiral flow pattern to be developed along the inter-reactor wall between the upper and the lower reactor stage. This flow pattern is claimed to (1) create a longer residence time for the coal particles, and thus increase the overall gasification efficiency, and (2) help facilitate slag removal as the spiral flow pattern creates a pressure differential between the wall and the center of the gasifier which help with drawing the slag toward the bottom of the gasifier for discharge.
The EAGLE gasifier uses a pneumatic system for dry coal fine feeding, using either nitrogen or recycled gas. Its reactor interior is protected by a water-cooled membrane wall; both features are similar to the Shell and Siemens designs.
Figure 2 shows a simplified drawing of the overall EAGLE gasifier vessel, shown with a radiant cooler on top of the gasifier reactor. The gasifier operates the first (bottom) stage at high temperature slagging conditions with only part of the coal feed, but a relatively larger amount of oxygen, while then adding the remaining coal and oxygen to the second (top) stage, where the hot gas drives the endothermic gasification reactions. The relative amount of coal/oxygen feed distribution into each stage depends on the nature of the coal. The distribution is optimized for high gasification efficiency versus stable slag discharge. The second stage is non-slagging. The particulate matter in the syngas contains unreacted char and dry ash. They are removed from the raw syngas downstream of the syngas cooler and recycled to the first stage. In this manner, almost all the ash in the system is removed as slag.
Figure 1: A Simplified Drawing of the EAGLE Gasifier
Figure 2: A Simplified Drawing of the Overall EAGLE Gasifier Vessel
Demonstration and Early Commercialization
The EAGLE technology is currently being demonstrated in a 150-tpd pilot plant facility, built in 2001, at J-Power Wakamatsu Research Institute in Kitakyushu City, Japan. Figure 3 shows a simplified flow diagram of the facility. It is a complete integrated gasification combined cycle (IGCC) pilot facility, equipped with coal feed preparation, a cryogenic air separation unit, an EAGLE gasifier with full heat recovery, a cyclone and char filter system for particulate removal, low-temperature syngas cooling with wet scrubbing, carbonyl sulfide (COS) hydrolysis, an MDEA acid gas removal unit and a power train. Demonstration testing started in March 2002, first with the gasification system shakedown, followed by overall plant performance testing, and recently focusing on testing different feedstocks, and CO2 capture.
Figure 3: A Simplified BFD of the 150 tpd EAGLE Pilot Plant Facility
Figure 4: View of the 150 tpd EAGLE Pilot Plant Facility