An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree R.sub.Blaine/R.sub.BET of 3.0 to 5.5 wherein R.sub.Blaine is the particle size calculated from the Blaine specific surface area and R.sub.BET is the particle size calculated from the BET specific surface area.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator having a sulfur content of 0.1 to 0.5 mass % and an aggregation degree R.sub.Blaine/R.sub.BET of 3.0 to 5.5 wherein R.sub.Blaine is the particle size calculated from the Blaine specific surface area and R.sub.BET is the particle size calculated from the BET specific surface area.

PROBLEM TO BE SOLVED:

In an apparatus for synthesizing methane from carbon dioxide and hydrogen, a device which is capable to remove the reaction heat and lower the reaction temperature as the reaction progresses in order to increase the conversion ratio to methane has been desired.

SOLUTION:

In the present invention, powders of magnesium hydroxide and magnesium carbonate, which are chemical heat storage agents, are used as part of the fluidizing medium of the multi-stage fluidized bed in the temperature range where the methanation reaction proceeds. The heat generated during the methanation reaction can be absorbed and stored in the powder. At this time, carbon dioxide generated from magnesium carbonate can be used as a raw material gas for the methanation reaction. Furthermore, after discharging the magnesium oxide generated by endotherm, the powder can be regenerated with an external regenerating facility and then the storage heat can be released and recovered. The regenerated powder can be fed to the uppermost stage of the multi-stage fluidized bed at a temperature lower than the internal temperature of the reactor to lower inside temperature. This made it possible to lower the reaction temperature of ascending reaction gas in the reactor along with the reaction progress, and to increase the conversion ratio to the produced methane by this lowered temperature.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×10.sup.3 to 25.0×10.sup.3 m.sup.2.Math.kg.sup.−1 and a Blaine specific surface area of 2.0×10.sup.3 to 7.0×10.sup.3 m.sup.2.Math.kg.sup.−1.

An object of the present invention is to provide magnesium oxide for an annealing separator which is useful for obtaining grain-oriented electromagnetic steel sheets with excellent magnetic properties and insulating properties. To resolve the above object, an aspect of the present invention resides in magnesium oxide for an annealing separator which has a BET specific surface area of 12.0×10.sup.3 to 25.0×10.sup.3 m.sup.2.Math.kg.sup.−1 and a Blaine specific surface area of 2.0×10.sup.3 to 7.0×10.sup.3 m.sup.2.Math.kg.sup.−1.

One object of the present invention is to provide an apparatus for producing inorganic spheroidized particles which can significantly reduce the amount of warming gas generated and suppress the generation of soot during combustion. The present invention provides an apparatus (10) for producing inorganic spheroidized particles, including a burner (11) for producing inorganic spheroidized particles, a vertical spheroidizing furnace (15), an ammonia supply source (12), an oxygen supply source (13), an ammonia supply line (L1) located between the ammonia supply source (12) and the burner (11) for producing inorganic spheroidized particles, and an oxygen supply line (L2) located between the oxygen supply source (13) and the burner (11) for producing inorganic spheroidized particles.

One object of the present invention is to provide an apparatus for producing inorganic spheroidized particles which can significantly reduce the amount of warming gas generated and suppress the generation of soot during combustion. The present invention provides an apparatus (10) for producing inorganic spheroidized particles, including a burner (11) for producing inorganic spheroidized particles, a vertical spheroidizing furnace (15), an ammonia supply source (12), an oxygen supply source (13), an ammonia supply line (L1) located between the ammonia supply source (12) and the burner (11) for producing inorganic spheroidized particles, and an oxygen supply line (L2) located between the oxygen supply source (13) and the burner (11) for producing inorganic spheroidized particles.

One object of the present invention is to provide a burner for producing inorganic spheroidized particles which can efficiently melt and spheroidize even organic powder with a large particle size distribution. The present invention provides a burner for producing inorganic spheroidized particles, including; a raw material powder supply path configured to supply inorganic powder as raw material powder; a first fuel gas supply path (3A) configured to supply a first fuel gas; and a first combustion-supporting gas supply path (4A) configured to supply a first combustion-supporting gas; wherein the raw material powder supply path includes: a first supply path (2A) configured to extend in an axial direction of the burner (1); a first collision wall (2D) configured to be located at the top of the first supply path (2A); a plurality of second supply paths (2B) configured to be branched from the top of the first supply path (2A), and extend radially from the center of the burner (1); one or more dispersion chambers (2C) configured to be located at the top of the second supply path (2B), and have a space in which the cross-sectional area is larger than the cross-sectional area in the second supply path (2B); and one or more raw material ejection holes (2a) configured to communicate with the dispersion chamber (2C).

One object of the present invention is to provide a burner for producing inorganic spheroidized particles which can efficiently melt and spheroidize even organic powder with a large particle size distribution. The present invention provides a burner for producing inorganic spheroidized particles, including; a raw material powder supply path configured to supply inorganic powder as raw material powder; a first fuel gas supply path (3A) configured to supply a first fuel gas; and a first combustion-supporting gas supply path (4A) configured to supply a first combustion-supporting gas; wherein the raw material powder supply path includes: a first supply path (2A) configured to extend in an axial direction of the burner (1); a first collision wall (2D) configured to be located at the top of the first supply path (2A); a plurality of second supply paths (2B) configured to be branched from the top of the first supply path (2A), and extend radially from the center of the burner (1); one or more dispersion chambers (2C) configured to be located at the top of the second supply path (2B), and have a space in which the cross-sectional area is larger than the cross-sectional area in the second supply path (2B); and one or more raw material ejection holes (2a) configured to communicate with the dispersion chamber (2C).

Provided are a method of preparing a metal oxide-silica composite aerogel, and a metal oxide-silica composite aerogel having an excellent weight reduction property prepared by the method. The method includes a step of adding an acid catalyst to a first water glass solution to prepare an acidic water glass solution (step 1); a step of adding a metal ion solution to the acidic water glass solution to prepare a precursor solution (step 2); and a step of adding a second water glass solution to the precursor solution and performing a gelation reaction (step 3) to yield a metal oxide-silica composite wet gel, wherein, in steps 2 and 3, bubbling of an inert gas is performed during the adding of the metal ion solution or the second water glass solution, respectively.