FECHA DE PUBLICACIÓN DEL ESTÁNDAR ORIGINAL VÁLIDO: 24.01.1996

Outline of technology

1.Background and process outline

Efforts of reduction in CO2 emissions have been promoted over the world responding to the issues of global warming in recent years. Specifically, coal is known as a source of heavy emissions of environmental loading substances (SOx, NOx, CO2, etc.), though the coal is expected as a sustainable energy resource also in the future. Since coal generates large quantity of CO2 per unit calorific value, research and development of the CO2 recovery and CO2 separation technologies are in progress on various points of views. With the background, the study team focused on the development of technology to recover CO2 from coal-fired power plants utilizing oxygen (O2/CO2) combustion, and has promoted the research of CO2 recovery technology. The CO2 recovery in the oxygen combustion stage is a hopeful technology of direct CO2 recovery

from large scale coal-fired power plants.

Ordinary coal-fired power plants combust coal by air. Since air contains N2 by 79%, all of the N2 is emitted to atmosphere during the combustion process, thus the CO2 concentration in the combustion flue gas is only 13-15% level. The oxygen combustion technology is a process to separate oxygen from the combustion air and to directly combust the coal with thus separated oxygen to increase the CO2 concentration in the flue gas to 90% or more, then to recover the flue gas in that state (refer to Fig. 1.)

Furthermore, the study team investigated a CO2 recovery system applying oxygen-blow IGCC aiming to further increase the efficiency.

In charge of research and development: Center for Coal Utilization, Japan; Electric Power Development Co., Ltd.;

Ishikawajima-Harima Heavy Industries, Co., Ltd.; Nippon Sanso Corp.; and Institute of Research and Innovation

Project type: Coal Production and Utilization Technology Promotion Grant

Period: 1992-2000 (8 years)

Ordinary recovery process

Recovered CO2 Recovered CO2 Compressor Compressor

2.Result of the development

Efforts of reduction in CO2 emissions have been promoted over the world responding to the issues of global warming in recent years. Specifically, coal is known as a source of heavy emissions of environmental loading substances (SOx, NOx, CO2, etc.), though the coal is expected as a sustainable energy resource also in the future. Since coal generates large quantity of CO2 per unit calorific value, research and development of the CO2 recovery and CO2 separation technologies are in progress on various points of views. With the background, the study team focused on the development

of technology to recover CO2 from coal-fired power plants utilizing oxygen (O2/CO2) combustion, and has promoted the research of CO2 recovery technology. The CO2 recovery in the oxygen combustion stage is a hopeful technology of direct CO2 recovery from large scale coal-fired power plants.

Ordinary coal-fired power plants combust coal by air. Since air contains N2 by 79%, all of the N2 is emitted to atmosphere during the combustion process, thus the CO2 concentration in the combustion flue gas is only 13-15% level. The oxygen combustion

1) Hiromi Shimoda: Proceeding of the 10th Coal Utilization Technology Conference, p.211 (2000)

2) S. Amaike: Proceeding of the 5th ASME/JSME Joint Thermal Engineering Conference, "AJTE99-6410" (1999)

Fig. 2 Image-drawing of CO2 recovery type power plant applying oxygen combust H2O N2 H2 CO2 N2 Recovered CO2 Bleed

Gasification Gas purification CO-shift _reaction CO2 removal HRSG CO2 compression Coal Air Air Steam CO CO2 H2 H2O CO2 H2 Air separation

Air combustion gas turbine

3.Issues and feasibility to practical application

Regarding the CO2 recovery type oxygen combustion power generation system and the CO2 recovery type IGCC, the study team conducted research and development and has proposed a power generation system which has superiority in terms of performance and economy as a CO2 recovery technology. In addition, in the basic combustion test, the study team has acquired academically valuable results (including the effect of reduction in NOx emissions).

It should be emphasized to further promote the study for controlling

the global warming and for reducing the CO2 emissions, though there are technologically validating issues such as the safety of power generation system with the oxygen combustion and the operability of CO2 recovery type IGCC. As for the practical application of the system, positive study should be conducted on the basis of the obtained results, while studying the application of the CO2 recovery type oxygen pulverized coal combustion system and of the CO2 recovery type IGCC, respectively, for the cases of application of CO2 recovery to an existing plant and of new plant.

References

CO2 recovery type oxygen pulverized coal combustion power plant

CO2 underground disposal

CO2 ocean disposal

CO2 tank

Oxygen production facility Boiler

Fig. 3 CO2 recovery type IGCC system technology is a process to separate oxygen from the combustion

air and to directly combust the coal with thus separated oxygen to increase the CO2 concentration in the flue gas to 90% or more, then to recover the flue gas in that state (refer to Fig. 1.)

Furthermore, the study team investigated a CO2 recovery system applying oxygen-blow IGCC aiming to further increase the efficiency.

The consumption of fossil fuel compacts on the environment in a variety of manners. Coal also influences the nature in each of its production, transportation, and utilization processes. In the process of its utilization in particular, coal dust, ash dust, acid gas (NOx, SOx), and carbon dioxide are discharged, suggesting that unregulated guzzling of coal may possibly have a great impact on the environment. On the other hand, technologies to limit the impacts derived from coal utilization on the environment to the minimum, as measures to cope with the above-mentioned situations, were collectively called Clean Coal Technology (CCT), for which advanced R&D is in wide practice in major advanced countries including Japan.

With such circumstances , the "Basic Technology Development Program for Advanced Coal Utilization (BRAIN-C)," mainly targeting at the coal gasification technology and to realize early commercialization of new high-efficiency and clean coal utilization technologies such as coal gasification and pressurized fluidized-bed processes, has sought and accumulated basic data

on coal from different angles. In the meantime, numerical simulation is a very effective tool to predict characteristics of a pilot or actual production unit from the above-mentioned basic data or, in reverse, to evaluate and select useful basic data. With this taken into consideration as well, technology development under the BRAIN-C is proceeded with from both aspects of useful basic data retrieval/storage and high-precision numerical simulation.

Fig.1 shows "BRAIN-C Technology Map." Products from this project are roughly grouped into the following three categories:

(1) Entrained flow gasification simulator

(2) Predicted model/parameter correlative equation (3) Coal database

Each category is explained below. Every categories, as integral part of products from this project, is indispensable for their actual use in a variety of situations, and ingenious utilization of each in accordance with the situation where it is used allows such products to be given full play.

Fig. 1 BRAIN-C Technology Map