Recirculating combustion system MERIT combines oxidation, reduction
Source: UFTO
Date: 5/15/97    Record No.: 10452
Contact: National Institute for Resources and Environment
16-3 Onogawa, Tsukuba, Ibaraki, 305 Japan
TEL +81-209-58-8100 FAX +81-298-58-8118

Recirculating combustion system MERIT combines oxidation, reduction
NIRE is investigating a new combustion system to solve global environmental problems resulting from current technologies. Single-stage combustion is divided into oxidation and reduction processes. Both are connected by the recalculation of mediator particles which transport oxygen. In this way, it is possible to minimize energy loss during combustion. The system can also reduce pollutant emissions and increase combustion efficiency. In addition, pure C02 is easily recovered by cooling the exhaust gas. To develop this system, NIRE conducted basic research on the reactivity of particles and gases, system hydrodynamics, and process system synthesis.

The National Institute for Resources and Environment (NIRE) is concerned with a wide range of research fields such as environmental protection, the development of natural resources and new forms of energy, and industrial safety, all of which are critical areas for our highly-industrialized society.

(this is a news item, off the web.)
New combustion system MERIT has smooth burn

Nikkei English News via Individual Inc. : (Nikkei Industrial Daily, May 6, 1997)

The Agency of Industrial Science and Technology's National Institute for Resources and Environment reports progress in the design of a next-generation combustion system dubbed MERIT, for Mediator Recirculation Integrating Technology.

MERIT combines oxidation and reduction steps to minimize energy loss and the release of polluting emissions during fuel combustion. Fuel is not burned directly, but exposed to a circulating metallic mediator.

The method is said to be as much as 10% more energy efficient than conventional combustion systems which directly burn fuel. Moreover, no nitrogen oxides are released and pure carbon dioxide is easily recovered.

In the latest development, the institute succeeded in running smooth continuous combustion reactions in a small prototype system. The next step is to design larger facilities, with the aim of eventually introducing the technology to power-generating turbines and boilers.

The prototype system comprises a pair of reaction columns connected at the top and bottom. Metal particles are exposed to air in the first column and undergo a sudden oxidation reaction, generating heat of 1,000 C.

The now-oxidized metal particles are then moved to the second column, where they mix with fuel and undergo a reduction reaction. Once reduced, they can be transferred back to the first column and oxidized again. In this way, the circulating metal particles act as a mediator for an overall combustion reaction.

In the tests, nickel was used as the metal mediator, and both the oxidation and reduction reactions were completed in less than one-tenth of a second. By circulating the nickel particles at a high enough speed it was possible to run a continuous oxidation-reduction reaction.

The challenge now is to find metals with higher durability and to develop a way to control the oxidation reaction. With these research topics in mind, the institute said it plans to work with other research institutes and private concerns to develop a practical technology.