Method of and apparatus for gas generation

A method of generating clean nitrogen gas in which most of the combustion residue product has been removed comprising:

• (a) providing a combustible composition essentially about 65 weight percent to about 70 weight percent alkali metal azide, up to about 4 weight percent sulfur and from about 27 weight percent to about 33 weight percent polybdenum disulfide;
• (b) placing said combustible composition in a combustion chamber having gas discharge orifices;
• (c) raising the temperature of said combustible composition sufficiently to ignite it;
• and
• (d) providing filtering means and cooling means between said combustible composition and said gas discharge orifices, said filtering means being selected for its compatibility with the combustion process and for its characteristic property at the combustion temperature of said composition of becoming less porous for a short interval during an early stage of the combustion function time thereby, during such interval, to increase the restrictive effect thereof and to retard the flow of combustion products out of said gas discharge orifices to allow such combustion products to be cooled by and condensed on said cooling means.

A gas generator comprising:

• housing means defining a combustion chamber having first gas discharge orifice means;
• combustible gas generating means disposed in said combustion chamber, said generating means being operable upon ignition to produce gas and combustion products;
• and
• primary filter means disposed in said combustion chamber adjacent said orifice means to cool said gas and to trap said combustion products, said filter means including a substance proximate to said gas generating means, in close surrounding relation thereto, said substance being selected for its compatibility with the combustion process and having a surface which at the temperature and environment of the combustion process, begins to melt and becomes tacky at an early stage of the combustion process whereby the porosity of said filter means is reduced for a short interval of the combustion process function time while the acceleration and velocity of the generated gas are at a relatively low level, thereby preventing combustion products from being blown out of the combustion chamber through said orifice means and allowing such products to condense and become entrapped in said filter means, wherein said substance of said primary filter means is a woven fabric the fibers of which swell as they become tacky to increase the restrictive effect of said filter means to the flow of combustion products therethrough, such increased flow restrictive effect existing for a short interval only during the combustion process function period to retard the flow out of said combustion chamber of combustion products to increase the period for cooling thereof and thereby condensation and trapping of molten solid products of combustion by said filter means to minimize the quantity of such solid products of combustion that are blown out of said combustion chamber through said orifice means, and
• wherein said combustible gas generating means includes a plurality of pellets that are uniformly disposed in said combustion chamber and that are comprised of a compacted mixture of 66% sodium azide, 30% ferric oxide, 2% sulfur and 2% molybdenum disulfide.

A gas generator comprising:

• housing means defining a combustion chamber having first gas discharge orifice means;
• combustible gas generating means disposed in said combustion chamber, said generating means being operable upon ignition to produce gas and combustion products;
• and
• primary filter means disposed in said combustion chamber adjacent said orifice means to cool said gas and to trap said combustion products, said filter means including a substance proximate to said gas generating means, in close surrounding relation thereto, said substance being selected for its compatibility with the combustion process and having a surface which at the temperature and environment of the combustion process, begins to melt and becomes tacky at an early stage of the combustion process whereby the porosity of said filter means is reduced for a short interval of the combustion process function time while the acceleration and velocity of the generated gases are at a relatively low level, thereby preventing combustion products from being blown out of the combustion chamber through said orifice means and allowing such products to condense and become entrapped in said filter means, wherein said substance of said primary filter means comprises a plurality of layers of a fiberglass woven fabric, wherein said primary filter means includes a plurality of filter portions of which said fiberglass woven fabric layers comprise an interior portion, wherein the portion of said primary filter means adjacent to said gas discharge orifice means comprises at least one layer of a coarse screen and the portion of said primary filter means adjacent the gas generating means comprises a plurality of layers of fine mesh screen, wherein the composition of said gas generating means is such that one of the products of combustion is an alkali metal oxide, said fiberglass woven fabric reacting chemically with said alkali metal oxide to produce an alkali metal silicate and to cause the fibers of said fiberglass woven fabric to swell and to be effective, as the pressure in said combustion chamber rises to a predetermined level, to restrict the flow of gas through said filter means thereby allowing molten products of combustion to cool and condense on said fine mesh screen, wherein said one of the products of combustion is caustic soda and the product of the reaction of said caustic soda with said fiberglass woven fabric is sodium silicate, wherein said generating means and said primary filter means are contained in a hermetically sealed cartridge, wherein said cartridge and said combustion chamber are both cylindrical in shape, said cartridge being concentrically arranged with respect to and substantially completely filling said combustion chamber, and wherein said housing means further includes wall means defining an annular space external of said combustion chamber, said wall means having second gas discharge orifice means, and further including secondary filter means in said annular space between said first and second orifice means further to cool said gas and trap combustion products, wherein said secondary filter means includes a plurality of filter portions, an intermediate portion of said secondary filter means comprising a blanket of aluminum silicate which reacts chemically with caustic soda to form sodium silicate, wherein said secondary filter means includes a standoff screen and a coarse screen between said first gas discharge orifice means and said blanket of aluminum silicate, and a fine screen between said blanket of aluminum silicate and said second gas discharge orifice means, and wherein said combustible gas generating means includes ignition means, said ignition means being disposed along the common cylindrical axis of said cartridge and combustion chamber, and wherein said gas generating means includes a plurality of pellets that are uniformly distributed in said cartridge in surrounding relation to said ignition means and that are comprised of a compacted mixture of about 65 weight percent to about 70 weight percent alkali metal azide, up to about 4 weight percent sulfur and from about 27 weight percent to about 33 weight percent molybdenum disulfide.

A gas generator comprising:

• housing means defining a combustion chamber having first gas discharge orifice means;
• combustible gas generating means disposed in said combustion chamber, said generating means being operable upon ignition to produce gas and combustion products;
• and
• primary filter means disposed in said combustion chamber adjacent said orifice means to cool said gas and to trap said combustion products, said filter means including a substance proximate to said gas generating means, in close surrounding relation thereto, said substance being selected for its compatibility with the combustion process and having a surface which at the temperature and environment of the combustion process, begins to melt and becomes tacky at an early stage of the combustion process whereby the porosity of said filter means is reduced for a short interval of the combustion process function time while the acceleration and velocity of the generated gases are at a relatively low level, thereby preventing combustion products from being blown out of the combustion chamber through said orifice means and allowing such products to condense and become entrapped in said filter means, wherein said substance of said primary filter means is a woven fabric the fibers of which swell as they become tacky to increase the restrictive effect of said filter means to the flow of combustion products therethrough, such increased flow restrictive effect existing for a short interval only during the combustion process function period to retard the flow out of said combustion chamber of combustion products to increase the period for cooling thereof and thereby condensation and trapping of molten solid products of combustion by said filter means to minimize the quantity of such solid products of combustion that are blown out of said combustion chamber through said orifice means, and wherein said combustible gas generating means includes a plurality of pellets that are uniformly disposed in said combustion chamber and that are comprised of a compacted mixture of about 65 weight percent to about 70 weight percent alkali metal azide, up to about 4 weight percent sulfur, and from about 27 weight percent to about 33 weight percent molybdenum disulfide.

A gas generator comprising:

• housing means defining a combustion chamber having first gas discharge orifice means;
• combustible gas generating means disposed in said combustion chamber, said generating means being operable upon ignition to produce gas and combustion products;
• and
• primary filter means disposed in said combustion chamber adjacent said orifice means to cool said gas and to trap said combustion products, said filter means including a substance proximate to said gas generating means, in close surrounding relation thereto, said substance being selected for its compatibility with the combustion process and having a surface which at the temperature and environment of the combustion process, begins to melt and becomes tacky at an early stage of the combustion process whereby the porosity of said filter means is reduced for a short interval of the combustion process function time while the acceleration and velocity of the generated gases are at a relatively low level, thereby preventing combustion products from being blown out of the combustion chamber through said orifice means and allowing such products to condense and become entrapped in said filter means, wherein said substance of said primary filter means comprises a plurality of layers of a fiberglass woven fabric, wherein said primary filter means includes a plurality of filter portions of which said fiberglass woven fabric layers comprise an interior portion, wherein the portion of said primary filter means adjacent to said gas discharge orifice means comprises at least one layer of a coarse screen and the portion of said primary filter means adjacent the gas generating means comprises a plurality of layers of fine mesh screen, wherein the composition of said gas generating means is such that one of the products of combustion is an alkali metal oxide, said fiberglass woven fabric reacting chemically with said alkali metal oxide to produce an alkali metal silicate and to cause the fibers of said fiberglass woven fabric to swell and to be effective, as the pressure in said combustion chamber rises to a predetermined level, to restrict the flow of gas through said filter means thereby allowing molten products of combustion to cool and condense on said fine mesh screen, wherein said one of the products of combustion is caustic soda and the product of the reaction of said caustic soda with said fiberglass woven fabric is sodium silicate, wherein said generating means and said primary filter means are contained in a hermetically sealed cartridge, wherein said cartridge and said combustion chamber are both cylindrical in shape, said cartridge being concentrically arranged with respect to and substantially completely filling said combustion chamber, and wherein said housing means further includes wall means defining an annular space external of said combustion chamber, said wall means having second gas discharge orifice means, and further including secondary filter means in said annular space between said first and second orifice means further to cool said gas and trap combustion products, wherein said secondary filter means includes a plurality of filter portions, an intermediate portion of said secondary filter means comprising a blanket of aluminum silicate which reacts chemically with caustic soda to form sodium silicate, wherein said secondary filter means includes a standoff screen and a coarse screen between said first gas discharge orifice means and said blanket of aluminum silicate, and a fine screen between said blanket of aluminum silicate and said second gas discharge orifice means, and wherein said combustible gas generating means includes ignition means, said ignition means being disposed along the common cylindrical axis of said cartridge and combustion chamber, and wherein said gas generating means includes a plurality of pellets that are uniformly distributed in said cartridge in surrounding relation to said ignition means and that are comprised of a compacted mixture of 66% sodium azide, 30% ferric oxide, 2% sulfur and 2% molybdenum disulfide.