Metal oxide particles having: (1) a volume ratio (a) in 0.7 μm band of 5 to 40 vol %, (2) a volume ratio (b) in 13 μm band of 20 to 45 vol %, (3) a volume ratio (c) in 1.3 μm band of 20 to 50 vol %, and (4) a sum of the volume ratios (a), (b), and (c) of 60 to 100 vol %. The 0.7 μm, 13 μm, and 1.3 μm bands are particle size distributions having peaks at 0.3 to 1.2 μm, 0.3 to 20 μm, and 0.7 to 3 μm, respectively. The volume ratios (a), (b), and (c) of each band have peaks near 0.7 μm, 1.3 μm, and 13 μm in a particle size distribution curve, and being obtained by calculating an abundance ratio of particles in each band from a numerical integration of distribution curves obtained by further dividing the particle size distribution curve into three bands.

Metal oxide particles having: (1) a volume ratio (a) in 0.7 μm band of 5 to 40 vol %, (2) a volume ratio (b) in 13 μm band of 20 to 45 vol %, (3) a volume ratio (c) in 1.3 μm band of 20 to 50 vol %, and (4) a sum of the volume ratios (a), (b), and (c) of 60 to 100 vol %. The 0.7 μm, 13 μm, and 1.3 μm bands are particle size distributions having peaks at 0.3 to 1.2 μm, 0.3 to 20 μm, and 0.7 to 3 μm, respectively. The volume ratios (a), (b), and (c) of each band have peaks near 0.7 μm, 1.3 μm, and 13 μm in a particle size distribution curve, and being obtained by calculating an abundance ratio of particles in each band from a numerical integration of distribution curves obtained by further dividing the particle size distribution curve into three bands.

The invention relates to a material for storing and releasing oxygen, consisting of a reactive ceramic made of copper, manganese and iron oxides, wherein, subject to the oxygen partial pressure of a surrounding atmosphere and/or an ambient temperature, the reactive ceramic has a transition region that can be passed through any number of times, said transition region being between a discharge threshold state of a three-phase crednerite/cuprite/hausmannite mixed ceramic and a charge threshold state of a two-phase spinel/tenorite mixed ceramic. A passing through of the transition region from the discharge threshold state towards the charging threshold state is associated with oxygen uptake and a passing through of the transition region from the charge threshold state towards the discharge threshold state is associated with oxygen release.

The invention relates to a material for storing and releasing oxygen, consisting of a reactive ceramic made of copper, manganese and iron oxides, wherein, subject to the oxygen partial pressure of a surrounding atmosphere and/or an ambient temperature, the reactive ceramic has a transition region that can be passed through any number of times, said transition region being between a discharge threshold state of a three-phase crednerite/cuprite/hausmannite mixed ceramic and a charge threshold state of a two-phase spinel/tenorite mixed ceramic. A passing through of the transition region from the discharge threshold state towards the charging threshold state is associated with oxygen uptake and a passing through of the transition region from the charge threshold state towards the discharge threshold state is associated with oxygen release.

A raw material composition for producing oxygen carriers includes a first component which is one or more of nickel oxide and nickel hydroxide and a second component which is one or more of boehmite, cerium oxide, cerium hydroxide, magnesium oxide, magnesium hydroxide, and titanium oxide, wherein, when the first component is nickel oxide, the second component includes cerium hydroxide. Such a raw material composition for producing oxygen carriers of the present invention is formed into oxygen carriers according to an oxygen carrier producing method, which will be described below, by adjusting the composition, formulation of raw materials, and degree of homogenization. Then, it is possible to produce oxygen carriers having physical properties such as a shape, a particle size, and a particle distribution suitable for a fluidized bed process or a high speed fluidized bed process and having improved wear-resistance, long-term durability, and oxygen transfer performance.

A raw material composition for producing oxygen carriers includes a first component which is one or more of nickel oxide and nickel hydroxide and a second component which is one or more of boehmite, cerium oxide, cerium hydroxide, magnesium oxide, magnesium hydroxide, and titanium oxide, wherein, when the first component is nickel oxide, the second component includes cerium hydroxide. Such a raw material composition for producing oxygen carriers of the present invention is formed into oxygen carriers according to an oxygen carrier producing method, which will be described below, by adjusting the composition, formulation of raw materials, and degree of homogenization. Then, it is possible to produce oxygen carriers having physical properties such as a shape, a particle size, and a particle distribution suitable for a fluidized bed process or a high speed fluidized bed process and having improved wear-resistance, long-term durability, and oxygen transfer performance.

A device for holding a target gas comprises a compartment configured to hold the target gas. The device further comprises a gas generator configured and arranged to release the target gas in the compartment in response to a control signal. The device further comprises a reference sensor sensitive to the target gas and arranged to supply a sensor signal representing a concentration of the target gas in the compartment. A control unit is provided and configured to control the release of the target gas from the gas generator by way of the control signal, dependent on the sensor signal. The gas generator and the reference sensor are arranged in the compartment.

A device for holding a target gas comprises a compartment configured to hold the target gas. The device further comprises a gas generator configured and arranged to release the target gas in the compartment in response to a control signal. The device further comprises a reference sensor sensitive to the target gas and arranged to supply a sensor signal representing a concentration of the target gas in the compartment. A control unit is provided and configured to control the release of the target gas from the gas generator by way of the control signal, dependent on the sensor signal. The gas generator and the reference sensor are arranged in the compartment.

An integrated chemical looping air separation unit (5) in a large-scale oxy-fuel power generating plant takes a portion of recycled flue gas (6) via a recycling conduit (7) through a heat exchanger (8) to a reduction reactor (9). The reduction reactor (9) exchanges oxidized metal oxide with an oxidation reactor (11) via transfer means (10) which return reduced metal oxide from the reduction reactor (9) to the oxidation reactor (11). This enables the reduction reactor (9) to feed a mixture of oxygen and recycled flue gas into the boiler (13) of the power generating plant in a more energy efficient manner than conventional oxy-fuel power plants using air separation units.

An integrated chemical looping air separation unit (5) in a large-scale oxy-fuel power generating plant takes a portion of recycled flue gas (6) via a recycling conduit (7) through a heat exchanger (8) to a reduction reactor (9). The reduction reactor (9) exchanges oxidized metal oxide with an oxidation reactor (11) via transfer means (10) which return reduced metal oxide from the reduction reactor (9) to the oxidation reactor (11). This enables the reduction reactor (9) to feed a mixture of oxygen and recycled flue gas into the boiler (13) of the power generating plant in a more energy efficient manner than conventional oxy-fuel power plants using air separation units.