JP4596722B2 - Gas generator and cold gas generation method - Google Patents

Abstract

Gas generator comprising at least one first body, comprising means for the generation of gas, and at least one second body, comprising means for the generation of a neutralisation agent, wherein means are present for contacting the said neutralisation agent with the said first body, to neutraise reaction products from the generation of gas in the said first body, and wherein means are present for operating the generation of a neutralisation agent in the second body at a temporal and/or spatial interval from the generation of gas in the first body.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to applied chemistry, and more particularly to a configuration for generating cold gas and a method for obtaining cold gas.
[0002]
[Prior art]
Gas generation methods based on the decomposition or combustion of chemical propellants and other compositions are often inflated, for example, from automobiles, liferafts, lifeboats and lifejackets (to isolate vents in the event of a fire) It is used for a number of purposes, such as quickly installed bulkheads (used for good drifting), drives and generators of different types of pneumatic systems, and operation of mechanical devices.
[0003]
Several technical methods are known for obtaining relatively cool gases, especially nitrogen. These methods are based on decomposing or burning stationary substances in special units. These materials are typically shaped in the form of monolithic or porous products and are in all types of shapes and dimensions.
[0004]
Hot gases generated from the decomposition of these materials are usually cooled by specially designed ones such as special chemical coolants or heat exchangers.
[0005]
The hot combustion gases are passed through a layer of coolant or a heat exchanger, and the gas temperature is reduced as a result of the endothermic decomposition process of the coolant or heat absorption by the coolant. Such a process is disclosed, for example, in U.S. Pat. No. 1,362,349, British Patent No. 1371506, French Patent No. 136897 and Russian Inventor Certificate No. 801540. The use of heat exchangers is disclosed in British Patent No. 1,500,137 and British Patent No. 1,487,944.
[0006]
The degree of cooling of the generated gas depends on the nature of the coolant, the mass of coolant that can sometimes exceed the mass of the gas generating composition, and in the case of heat exchangers, the design characteristics of the exchanger.
[0007]
One of the disadvantages of the prior art cited above is the relatively complex structure of these units. Another drawback is that known gas generators do not allow or provide the gas to be cooled below 150 ° C. Therefore, the application of these gas generators is limited to systems that can withstand such high temperatures. These are disadvantageous from the viewpoint of cost economy and application.
[0008]
In addition, the gas obtained through the use of the above method can not only have a negative effect in construction, but in the case of an automobile airbag, it is assumed that the person is supposed to be protected by an airbag. Contains a large and undesired amount of ingredients for (driver).
[0009]
Complex designs and complex products that result in increased mass, size and complexity of the products are a negative feature of these gas generation methods. This reduces the reliability and efficiency of the complete system. There is a continuing need for reliable, safe and economical methods for the generation of cold gas, especially in the life-saving airbag industry.
[0010]
French Patent No. 2108282 discloses a method for generating cold gases, in particular nitrogen, as well as hydrogen and oxygen, by using endothermic decomposition of products made from gas permeable solid materials. The gas permeable solid material includes a gas source and a heat absorbing mixture, whereby the gas reaction product passes hot gas through the porous body of the product in the direction of movement of the front point of the reaction. It is cooled by. The hot gas heats the porous body to the temperature necessary to sustain the endothermic chemical reaction. Heating of the porous body is necessary to allow the main reaction. The decomposition of the coolant is also an endothermic chemical reaction. The patent claims to obtain nitrogen gas from a solid propulsion system with a purity better than 97% and a temperature below 150 ° C.
[0011]
In gas generators using this method (as well as in most other gas generators) azide, hydride and chlorate are used as gas sources, which are usually in the form of alkali and alkaline earth compounds. used. In the decomposition of these compounds, usually highly reactive metal slag remains in the gas generator.
[0012]
As an example, NaN ₃ can be used for a gas generator composition that provides nitrogen. The decomposition reaction of NaN ₃ yields Na and N ₂ . Similarly, in other decomposition reactions of sodium compounds, sodium is also formed. The formed gas is blown out and slag remains. This slag contains the remainder of the bonding agent as well as coolant and metallic sodium. Under these conditions of gas evolution, highly chemically reactive sodium is thus generated. This highly reactive material accumulates in the condensed combustion cracking products and thus poses a potential hazard for the person involved. When moisture is present, this can lead to violent and dangerous reactions that occur in conjunction with the generation of highly flammable and explosive hydrogen. The decomposition may cause other undesired effects or even personal damage if humans are involved by explosion.
[0013]
Methods for neutralizing sodium are known per se and are disclosed, for example, in “Sodium production, its properties and use” State Publishing House, Moscow, 1961, page 142. One of the methods mentioned for removing metallic sodium is decomposition with water. Since this method can be applied to neutralize the gas generator used, the generator after use is sealed and suitable for properly neutralizing the reactive residue of the generator Must be moved to installation. This is dangerous, not cost effective, complicated and therefore undesirable.
[0014]
In the case of a sodium compound as a gas source, elemental sodium (Na) is formed when sodium azide decomposes. Sodium is a very reactive and active chemical. As a result of this reactivity, sodium can react with a wide variety of substances, leading to a number of sufficiently stable compounds. One of these compounds is sulfur. Sodium reacts with sulfur to form sodium sulfide (Na ₂ S).
[0015]
Sodium neutralization by reaction with sulfur or sulfur compounds in the gas generating composition is described, for example, in US Pat. No. 3,775,199, US Pat. No. 5,536,340, EP 394103 and US Pat. No. 3,741,585. It is known from the description. Sulfur is evaporated during the decomposition of the gas generant composition and reacts with sodium slag formed to neutral sodium sulfide.
[0016]
In the conventional gas generator described above, sulfur is vaporized as the gas is generated. It is difficult to vaporize sulfur at the same rate at which sodium slag is formed and reacted with sodium slag. As a result, vaporized sulfur exits the gas generator and / or not all of the metal sodium is neutralized. This is a disadvantage of using a mixture of sulfur and a gas generating composition as described in the prior art.
[0017]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to develop a product that produces an effective generation of low temperature nitrogen gas without the above-mentioned adverse effects and without significant concessions to the output and performance parameters of the gas generator. is there.
[0018]
Another object of the present invention is to provide a method for generating low-temperature nitrogen gas, and to provide a gas generator that generates low-temperature nitrogen gas.
[0019]
The present inventors have now found an arrangement for gas generation that can overcome the above disadvantages of the prior art and that results in the generation of cold gas with effective and sufficient neutralization of the reactive slag. It was.
[0020]
[Means for Solving the Problems]
Accordingly, the present invention provides at least one first body including means for generating a gas and one or more reaction products , and at least one spatially separated first including means for generating a neutralizing agent. in a gas generator including two body, to neutralize with the neutralizing agent is passed through said first body of one or more reaction products, such as slag from the generation of gas in said first body means are present, and at which means for operating the generation of neutralizing agent in the second body at a generation or et empty during intervals and, optionally, the time interval of the gas in the first body are present Includes gas generator.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The principles of the present invention include the separation of gas generating and neutralizing materials, thereby improving the effectiveness and reliability of gas generation and neutralization. According to one embodiment of the present invention, two gas generants are present in one housing and are spatially separated from each other. The first task is to generate a gas, preferably a low temperature gas, and a first gas generator and a neutralizing compound for the slag obtained from the first gas generator; A second gas generator.
[0022]
The first gas generator comprises a composition from which nitrogen, hydrogen and / or oxygen gas, preferably low temperature, can be obtained by decomposition of the gas generating composition in the form of a gas permeable solid material. Here, the generated gaseous product is passed through the porous body in the direction of the front point (front) of the moving decomposition.
[0023]
The second gas generator (neutralizer) is another composition that generates a neutralizing gas, preferably an effective neutralizer compound, such as sulfur, iron oxide, metal sulfide, metal oxide (Fe , Cu, Mg, Ti, Sn, B, etc.), SiO _{2 and the} like, and a gas generating composition. The neutralizing agent composition produces a neutralizing gas separate from the gas generated in the first generator. Neutralizing gas is generated at a time and / or spatial interval from the first gas generator. It is an important aspect of the present invention that the neutralizing agent does not come into contact with the solid porous material to be decomposed during or prior to decomposition. The present invention states that only after the material has been decomposed, the neutralizing agent passes through the decomposed porous solid material, thereby neutralizing (usually harmful) decomposition products (slag). Based on the principle. The neutralizing gas is generated at a rate and in a way that provides effective neutralization of the slag and no gaseous neutralizer is released. A neutralizing agent, such as gaseous sulfur, reacts with the reaction products (slag) from the first gas generator so that these products are effectively neutralized.
[0024]
Accordingly, in one embodiment, the present invention provides a first gas generator comprising a gas permeable solid material comprising a nitrogen source, preferably azide, more preferably sodium azide, a bonding agent and an optional heat absorbing mixture. Here, the solid material relates to a second gas generator having a porosity of 35-60% and comprising a neutralizer composition comprising sulfur and an additional nitrogen source.
[0025]
The gas to be generated can be selected from the group of nitrogen, oxygen and hydrogen, or combinations thereof. In general, azides, hydrates and chlorates are used for this purpose, preferably in the alkali metal form.
[0026]
In a further embodiment of the invention, the gas to be produced is nitrogen and the nitrogen source in both the first and second gas generators is selected from the group of alkali metal azide or alkaline earth metal azide, Preferably potassium azide or sodium azide, more preferably sodium azide.
[0027]
The first and second gas generators need not be physically separated from each other. In embodiments of the invention, the vaporizer neutralizing agent of the second generator can be placed in any position relative to each other as long as it can contact the slag from the first generator.
[0028]
In the present invention, neutralization occurs behind the reaction front point of the decomposition reaction of the first gas generator. The spatial spacing between the reaction front point of the first gas generator and the production of the neutralizing agent in the second gas generator is such that the hot reaction product from the first gas generator remains behind, while the nitrogen The intervals are such that the gas is released. The front point of neutralization is delayed from the front point of decomposition and neutralizes the reaction product remaining behind.
[0029]
In another embodiment of the present invention, the rate at which the gas generant composition decomposes is different from the rate of decomposition of the neutralizer charge. That is, the decomposition of the gas generating composition and the neutralizing agent is started simultaneously. Metal slag is formed, and then generation of gaseous neutralizing agent occurs in the second generator to neutralize the slag.
[0030]
In another embodiment of the invention, the time when the neutralizing agent is activated is later than the time of activation of the gas generator.
[0031]
Activation or ignition of the two bodies can be performed by any suitable means known in the art.
[0032]
Exemplary embodiments of the present invention are as follows.
[0033]
The body consists essentially of two parts. That is, a gas generator and a neutralizing agent. The gas generator includes a porous solid material that includes a gas generating component, such as sodium azide, together with a binder (eg, a phenolic resin) and an optional coolant or other heat absorbing mixture. The other part of the main body is a neutralizer part. The neutralizing agent includes a neutralizing agent (sulfur, iron, metal sulfide, metal oxide) and a gas generating component. The gas generant component may be the same as the gas generant component in the first part, for example sodium azide. When the gas generator is activated, gas is generated and released, leaving behind a highly reactive metallic sodium slag. When the neutralizing agent is activated, the neutralizing reagent is vaporized. In the case of a solid neutralizer, it can be in the form of an aerosol. The neutralizing agent reacts with the slag, resulting in a non-hazardous or less harmful material and neutral sodium sulfide when neutralizing the sodium with sulfur.
[0034]
The amount of neutralizing agent is sufficient to effectively neutralize the slag formed by both the neutralizing agent and the gas generator and such that minimal or little gaseous neutralizing agent is released. Amount.
[0035]
In the present invention, in order to promote the interaction between sodium and a neutralizer compound (for example, sulfur), the neutralizing material is preferably in a form in which the reaction with sodium slag is enhanced. To this extent, the neutralizing agent can be mixed with gas generating compounds in the form of powders, granules and the like.
[0036]
In a gas generator according to a preferred embodiment of the present invention, the gas generator is based on the use of sodium azide and sulfur and the total amount of nitrogen source in the first and second bodies is 50 relative to the total weight of the gas generator. -80% by weight and the amount of neutralizing agent in the second body is 47-90% by weight with respect to the weight of the second body. Each weight of the gas generator is measured in the absence of a housing, external cooling aids, and the like.
[0037]
The second body (gas generator) comprises from 17 to 35% by weight of the gas generator according to the invention, based on the total weight of the gas generator. The second body (gas generator) contains 10 to 53 wt% nitrogen source and 47 to 90 wt% neutralizer. In a preferred embodiment, the second body (gas generator) comprises 15-25% by weight, more preferably 17-23% by weight nitrogen source and 75-85% by weight, more preferably 77-83% by weight sulfur. .
[0038]
In a preferred embodiment, the sulfur is in the form of particles, preferably in the form of small particles, more preferably in the form of sulfur powder.
[0039]
The relative amount of sodium azide and sulfur is included between the lower sulfur limits, which is the amount of sulfur required to neutralize the elemental sodium formed. The upper limit of sulfur is determined by the amount at which little vaporized sulfur is released, or the amount that is considered acceptable for output gas purity.
[0040]
The rate at which gas was generated was measured to provide an optimal formulation with any heat absorbing product and neutralizer product. The ratio of the various components (nitrogen source, heat-absorbing material and sulfur) was chosen to obtain the desired maximum emission of evaporated sulfur and stable combustion of the material. It has been found that stable ignition and combustion of a substance is not possible if the sulfur concentration in the substance is greater than 90% by weight of additional nitrogen source and sulfur combined weight (neutralizer mass). . If the concentration of sulfur was less than 47% by weight of the total amount, the evaporated sulfur emissions were reduced below the desired level and the total (neutralizer mass) / (nitrogen source) ratio was In order to obtain elemental sodium binding at a sufficiently high level, it had to be increased. The preferred mass ratio of nitrogen source and neutralizing agent is determined by the total neutralization of sodium to sodium sulfide in the slag.
[0041]
In a preferred embodiment of the invention, the nitrogen source and neutralizing agent, preferably sulfur, are mixed uniformly as part of the second body.
[0042]
In another preferred embodiment of the present invention, the neutralizer product is an amount of 10 to 53 wt% additional nitrogen source and 47 to 90 wt% sulfur based on the total weight of the additional nitrogen source and sulfur. Including sulfur and additional nitrogen sources.
[0043]
In this embodiment of the invention, the total amount of nitrogen source and sulfur is 17-35% by weight, based on the total weight of the product.
[0044]
When the total amount of additional nitrogen source and sulfur is less than 17% by weight, the total neutralization of sodium is insufficient due to the lack of sulfur. If the amount exceeds 35% by weight, the evaporated sulfur is blown out with the generated gas and therefore the purity of the generated nitrogen gas is reduced.
[0045]
It should be noted that in some cases the generated gas may contain some entrained contaminants. If these are not desired in the intended use of the generator, it may be advantageous to include additional filtering means downstream. This can be any type of filter, such as sand, chemical filters, metal wire filters, and the like. In some instances, it may also be advantageous to include some additional neutralizing agent in the filter, thereby providing additional protection against contaminants being blown out with the gas.
[0046]
As described above, when generating a cold gas by passing the generated gas through a porous solid material, the condition is that when the material is almost completely decomposed, the remaining porous material is cooled. Because the capacity is too small, it can result in failure to maintain the gas temperature at a constant level. If in certain applications this is unacceptable, it may be advantageous to include cooling means downstream in the gas generator. In particular, since both the cooling means and the filtering means can be easily constructed from the same material (sand, steel wire, steel wool, metal mesh, etc.), it is possible to combine these cooling means with the filtering means described above. It is.
[0047]
The present invention also provides
Decomposing the gas permeable porous solid material in the first body, thereby generating gas and other reaction products at the front of the decomposition;
Allowing the gas to pass through the porous solid material;
Generating a neutralizing agent in the second body, wherein the second body is spatially separated from the first body ;
Passing the porous solid material through the neutralizing agent;
Neutralizing the other reaction product in the first body by reaction with a neutralizing agent;
Maintaining a temporal and / or spatial spacing between a forward point of disassembly of the first body and a forward point of neutralization obtained by passing a neutralizing agent from the second body through the first body. And relates to a method for generating a gas, preferably nitrogen.
[0048]
When the nitrogen source containing the gas generating substance and the neutralizing substance are ignited, the substance starts to decompose. The gaseous decomposition products of the nitrogen source are cooled by passing through the porous body branched in the direction of movement of the forward point of the reaction and transferring heat to the porous body. In the combustion of the neutralizer, evaporated sulfur is generated and passed through the slag of the nitrogen source. In an embodiment of the present invention, a spatial and temporal interval is provided between a point ahead of the nitrogen source reaction and a point forward of the neutralizer reaction. The reaction between evaporated sulfur and metallic sodium is exothermic. However, this will not affect the temperature of the generated gas because there is a spatial and temporal interval between gas generation and neutralization. This interval can be achieved by a lower reaction rate of the neutralizing agent when compared to the reaction rate of the nitrogen source, or by an appropriate time delay. With this interval, the evaporated sulfur is mainly generated after sodium is formed, thus allowing more optimal reaction conditions for both gas evolution and sodium neutralization.
[0049]
The spacing may also be controlled by design related features such as flow rate adjustment by different forms of the combustion surface or by non-simultaneous ignition of the nitrogen source and neutralizer. Accordingly, the present invention includes a generator for cold gas.
[0050]
In a preferred embodiment, the generated gas is cooled by passing the gas through the porous body in the direction of movement of the forward point of the reaction.
[0051]
In a preferred embodiment, the heat formed in the exothermic reaction by the heat absorbing material contained in the porous body is absorbed.
[0052]
In a preferred embodiment of the invention, the amount of heat generated with respect to the amount of heat absorbed is such that the generated gas is cooled to a temperature below 150 ° C, preferably below 100 ° C.
[0053]
The present invention will now be described with reference to the accompanying drawings. In the figure, a gas generator having a housing 1 and provided with an opening 2 for the generated gas is shown. There are two gas generating bodies 3, 4 in the housing 1. The first solid porous body 3 provides the majority of the gas and the body 4 provides the neutralizing gas. In addition, there is a sand filter body 5 which optionally contains cooling and / or filter material, for example dispersed additional neutralizing agent.
[0054]
If the main body 3 is ignited by ignition means (not shown), decomposition starts and gas generation occurs, the gas mainly flowing in the direction of arrow B, i.e. through the main body 3, and thereby being porous. The material is heated and at the same time cooled to a relatively low temperature. Finally, the cooled gas exits the housing 1 through the opening 2 in the direction of arrow C.
[0055]
The decomposition of the porous solid material proceeds with time, and the front point of the decomposition moves in the direction of arrow A.
[0056]
From the main body 4, neutralizing gas is provided after ignition of the main body (not shown) by the ignition means. The gas flows in the direction of arrow D and forms a forward neutralization point (not shown) in the body 3. The front point exists behind the front point of disassembly, but moves in the same direction (arrow A).
[0057]
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a gas generator of the present invention.

Claims (21)

Gas generation comprising at least one first body comprising means for generating a gas and one or more reaction products , and at least one spatially separated second body comprising means for generating a neutralizing agent in vessels, there are means for by the said neutralizing agent is passed through the said first body neutralize one or more reaction products, such as slag from the generation of gas in said first body, and gas generator where there are means for operating the generation of neutralizing agent in the second body at a generation or et empty during intervals and, optionally, the time interval of the gas in the first body. The gas generator of claim 1, wherein the means for generating a gas and one or more reaction products includes components that produce nitrogen, oxygen, hydrogen, or combinations thereof. The means for generating gas and one or more reaction products comprises a gas permeable solid material comprising a gas source, a binder and an optional heat absorbing mixture, wherein the solid material is 35-60 wt% The gas generator according to claim 2, which has porosity. It said first body comprises means for generating nitrogen gas generator of any one of claims 1 to 3.   The gas generator according to any one of claims 1 to 4, wherein the reaction product contains slag containing sodium.   The gas generator according to claim 1, wherein the second body includes a gas source and a neutralizing agent.   The gas generator according to any one of claims 1 to 6, wherein the neutralizing agent is sulfur. The total amount of gas sources in the first and second bodies constitutes 50-80% by weight relative to the total weight of the gas generator, and the amount of neutralizing agent in the second body is based on the weight of the second body. The gas generator according to any one of claims 1 to 7, comprising 47 to 90% by weight.   The gas generator according to any one of claims 1 to 8, wherein the second main body is 17 to 35% by weight with respect to the total weight of the gas generator.   The gas generator according to any one of claims 1 to 9, wherein the second body comprises 10 to 53 wt% nitrogen source and 47 to 90 wt% neutralizer.   The gas generator according to claim 1, wherein the generated gas is cooled by a heat-absorbing substance.   The gas generator according to any one of claims 1 to 11, wherein a heat-absorbing substance is contained in the first main body.   13. A gas generator according to any one of the preceding claims, wherein there are means for cooling and / or filtering the gas downstream of the first body. 14. A gas generator according to claim 13 , wherein the means for cooling and / or filtering the gas also includes a neutralizing agent for contaminants entrained by the gas.   15. A gas generator according to any one of the preceding claims, wherein the first and second bodies are contained in a container, the container having at least one outlet for the generated gas. . Decomposing the gas permeable porous solid material in the first body, thereby generating gas and other reaction products at the front of the decomposition;
Allowing the gas to pass through the porous solid material;
Generating a neutralizing agent in the second body, wherein the second body is spatially separated from the first body;
Passing the porous solid material through the neutralizing agent;
Neutralizing the other reaction product in the first body by reaction with a neutralizing agent;
Maintaining a temporal and / or spatial spacing between a forward point of disassembly of the first body and a forward point of neutralization obtained by passing a neutralizing agent from the second body through the first body. including, method of generating gas.   17. The method of claim 16, wherein the generated gas is cooled by passing the gas through the porous solid material in the same direction as the movement of the forward point of the reaction.   18. A method according to claim 16 or 17, wherein heat is absorbed by the porous body and the heat is generated in the decomposition of the gas permeable porous solid material. The amount of heat generated and absorbed, generated gas is in an amount such as to be cooled to a temperature below Ri by 0.99 ° C., any one method according to claim 16-18. 20. A method according to any one of claims 17 to 19, wherein the heat absorbed by the porous solid material maintains the temperature necessary for the decomposition of the gas permeable porous solid material. The generated gas is passed through a filter and / or cooling means downstream of gas generation, the filter and / or cooling means optionally further comprising neutralizing means. Way .

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