JP3377256B2 - Gas generator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generator, and more particularly to a combination of a cracked gas generation part by a catalytic reaction of a vaporized liquid raw material and a pressure fluctuation type adsorption purification part for separating and refining the generated gas. The present invention relates to an improved gas generator, which improves the purity of the product gas obtained and downsizes the device.

[0002]

2. Description of the Related Art Gases such as hydrogen and carbon monoxide are basic substances used in various industries. And
When using a large amount of these, it is desirable to manufacture them at the place of use in consideration of transportation safety and cost, and these gas generators are becoming popular. For example,
In the semiconductor manufacturing industry, which has made remarkable progress in recent years, a large amount of hydrogen is used as an atmospheric gas in various processes, and there is a strong demand for an improvement in the degree of integration of semiconductors and an increase in their purity. Therefore, impurities such as nitrogen, hydrocarbons, carbon monoxide, carbon dioxide, oxygen and water vapor which are present in the gas in the ppm order are removed to obtain a high purity of the ppb order or less and at a low cost. It is desired to manufacture in large quantities. In addition, a large amount of hydrogen, carbon monoxide, and other gases are also used in the synthetic chemistry industry, polymer chemistry industry, etc., but in response to higher product quality, higher purity raw material gas and low cost There is a rapidly growing demand for a new product. For this reason, impurities such as nitrogen, hydrocarbons, carbon dioxide, oxygen and water vapor, which are present in the raw material gas in the order of ppm, are removed, and mass production is carried out at a high purity level of the order of ppb and at a low cost. Various attempts have been made.

A relatively simple method for producing hydrogen or carbon monoxide gas without using large-scale equipment is to vaporize the raw materials such as methanol and methyl formate, and bring them into contact with the catalyst at high temperature and high pressure. A method is generally known in which chemical decomposition is performed, and the decomposition product gas is separated into components by a pressure fluctuation type adsorption purification method to obtain one or more target product gases. As a practical example of a gas generator by these methods, methanol and water as raw materials are decomposed into a mixed gas of carbon dioxide and hydrogen, and then the decomposed gas is separated into components by a pressure fluctuation type adsorption purification method, and hydrogen gas is produced as a product. After decomposing into a mixed gas of carbon monoxide and hydrogen using methanol as a raw material, the decomposed gas is separated into components by a pressure fluctuation adsorption purification method, and hydrogen gas and carbon monoxide gas as products, or, A gas generator that obtains only hydrogen gas, decomposes into a mixed gas of carbon monoxide and methanol using methyl formate as a raw material, cools this mixed gas to separate and condense methanol, and then purifies by a pressure swing adsorption purification method, Products include gas generators that obtain carbon monoxide gas.

Each of these apparatuses is a combination of a gas decomposition section and a pressure fluctuation type adsorption purification section, and the pressure fluctuation type adsorption purification section is mixed in the liquid raw material in the decomposition gas generated by catalytic decomposition. Since such impurities and impurities generated by decomposition are included, the purpose is to remove these impurities and at the same time separate the target gas into components and take out as a purified product gas. When product gas is obtained using these gas generators, the purity and treatment amount are ultimately the adsorption characteristics for each impurity of the adsorbent, the adsorbent filling amount, etc., that is, the performance of the pressure fluctuation type adsorption purification unit. Therefore, depending on the type of impurities, the content ratio, etc., the type of adsorbent, the combination,
The filling amount and the like are selected.

[0005]

The impurities contained in the decomposed gas usually coexist with those that are easily adsorbed on the adsorbent and those that are difficult to adsorb. Among these impurities, water vapor and carbon dioxide are adsorbed. In addition, carbon monoxide and hydrocarbons are relatively easily adsorbed, and these impurities can be easily adsorbed and removed. However, the adsorbability of oxygen and nitrogen is remarkably small, and if they are to be removed, a large amount of adsorbent must be used, resulting in an enormous amount of equipment and a significant increase in cost. There was a problem that there was no merit. Therefore, give up the removal of oxygen and nitrogen, and use them only for the purposes that will not cause any adverse effects even if they remain, or that will not cause a fatal problem in preparation for the quality and performance deterioration of the target product. There was a drawback that I could not.

[0006]

Means for Solving the Problems As a result of continuing the research from a multifaceted perspective on a gas generator, the inventors of the present invention have obtained a refined gas containing no impurities including oxygen and nitrogen, which have been the subject. In addition to identifying the fact that nitrogen and oxygen, which are particularly problematic, are caused by air dissolved or dissolved in the liquid raw material, and further studying these solutions, including the characteristics of the equipment and the raw material, The present invention has been completed by stacking.

[0007] That is, the present invention is a pressure fluctuation type adsorption for producing a decomposition gas for vaporizing a liquid raw material and catalytically decomposing it, and separating the gas generated by the catalytic decomposition into one or a plurality of product gases. A gas generator comprising a refining section in combination, a liquid raw material supply tank having a seal gas introduction pipe at one or more locations, and a vaporizer connected to the supply tank. A decomposing device connected to the outlet of the vaporizer and having a catalyst filled therein, and a pressure fluctuation type adsorption refining device constituted by a plurality of adsorption tubes connected to the decomposing device and having an adsorbent filled therein The liquid raw material supply tank is chemically inert to the liquid raw material,
And a gas generator, characterized in that that will be sealed by a gas having a strong adsorption against the adsorbent. The present invention is constituted by a gas decomposing section for vaporizing and decomposing a liquid raw material and a pressure fluctuation adsorption refining section for separating and purifying the gas generated by decomposition, and nitrogen, hydrocarbon, carbon monoxide,
Impurities such as carbon dioxide, oxygen, and water vapor, particularly impurities such as nitrogen and oxygen, which are difficult to remove by a normal pressure swing adsorption refiner, can be reliably removed, and a high-purity product gas can be generated.

The gas decomposing section is composed of a liquid raw material storage and supply tank (hereinafter referred to as a supply tank), a supply pump, a vaporizer, a decomposer, and the like. In the present invention, the supply tank is sealed by a gas that is chemically inert to the contained liquid raw material and that has a strong adsorptive property to the adsorbent filled in the pressure fluctuation type adsorption refiner described later. It The adsorption tank is provided with a gas introduction pipe for sealing at one or a plurality of locations. The introduction pipe may be provided so that the sealing gas can be fed into the upper space of the supply tank, or it may be opened in the lower liquid so that the liquid raw material can be aerated, but at least one of them is in the lower liquid. It is preferable to open it. Further, the seal gas is well dispersed in the case of opening in the liquid, effectively曝or a structure having a large number of small holes the openings of balloon angles different to be air, or the like stirrer in the supply vessel May be attached.

The sealing gas is chemically inert to the liquid raw material and is easily adsorbed to the adsorbent, such as carbon dioxide, carbon monoxide and hydrogen, which are liquids. It is selected according to the type of raw material, the type of decomposed gas generated, the type of adsorbent in the pressure fluctuation type adsorption / purification section, and the like. Among these, the chemical stability to various liquid raw materials and the adsorptivity to adsorbents are high, and
Carbon dioxide is particularly preferable because it can be easily replaced with nitrogen, oxygen, etc. dissolved in the liquid raw material.

A gas phase catalytic cracking catalyst is packed in the cracker. For example, in the case where hydrogen, carbon monoxide or the like is generated as a cracking gas from methanol, methyl formate or water as a raw material as described later. Is generally a catalyst containing copper oxide or copper oxide as a main component, and containing zinc oxide, chromium oxide, etc., usually from a variety of commercially available catalysts depending on the raw material liquid and the type of target gas to be generated. To be selected.

The pressure fluctuation type adsorption purification unit combined with the gas decomposition unit is basically used for separation and purification of ordinary gas, and is constituted by a plurality of adsorption columns filled with an adsorbent. For example, in the case of the most general four-cylinder type device, each process is sequentially switched such as an adsorption process, a pressure reduction process, a blow, a regeneration process, a pressurization process, and a finishing process. The adsorbent filled in the adsorption column is activated carbon, alumina, synthetic zeolite, natural zeolite, activated carbon having molecular sieves, etc., and one kind or two or more kinds may be combined depending on the kind and content ratio of the generated gas and impurities. Is filled. With these adsorbents, it is possible to efficiently remove carbon monoxide, hydrocarbons, hydrogen, steam and the like as impurities, including carbon dioxide. On the other hand, the removal ability of both adsorbents for nitrogen and oxygen is small, but in the present invention, the gas supplied to the pressure fluctuation type adsorption purification unit is aerated by the aeration and sealing of the supply tank as described above. It is removed in advance and basically not included, so no special measures such as increasing the amount of adsorbent are required.

The present invention is applied, for example, when the following gases are generated and a high-purity product gas is obtained.
CuO-Z using methanol and water as raw materials
After contacting with an nO catalyst or the like to decompose it into a mixed gas of carbon dioxide and hydrogen, the decomposed gas is separated into components by a pressure swing adsorption purification method to obtain hydrogen gas as a product. After methanol is used as a raw material, it is heated and vaporized and brought into contact with a CuO catalyst or the like to decompose it into a mixed gas of carbon monoxide and hydrogen,
The decomposed gas is separated into its components by a pressure swing adsorption purification method to obtain hydrogen gas and carbon monoxide gas or only hydrogen gas as a product. Using methyl formate as a raw material, it is heated and vaporized and brought into contact with a CuO catalyst, etc. to decompose it into a mixed gas of carbon monoxide and methanol, and after cooling this mixed gas to condense and separate methanol, a pressure fluctuation adsorption purification method To obtain carbon monoxide gas as a product.
For example, methanol is used as a raw material, which is vaporized by heating and brought into contact with a catalyst to form methyl formate, and then carbon monoxide gas is obtained by a further step. As the sealing gas in these gas generators, for example, hydrogen, carbon dioxide, etc. in the device, carbon monoxide in the device,
For devices such as hydrogen and carbon dioxide, carbon monoxide, carbon dioxide and the like can be used. Of these, carbon dioxide is preferable because it can be commonly used in any case and is safe in addition to the reasons already described.

Next, the present invention will be illustrated in more detail with reference to the drawings. FIG. 1 is a flow sheet of the gas generator of the present invention. In FIG. 1, two liquid raw material supply tanks 1 and 2 each having a vent on the top of which a check valve is interposed are connected to a cylinder 3 of a sealing gas at the bottoms thereof, and a plurality of outlets are provided at the tip. The sealing gas introduction pipes 4 and 4'provided are inserted and fixed airtightly. Liquid source supply pipes 5 and 5'are connected to the supply tanks 1 and 2, and the supply pipes 5 and 5'join each other on the outlet side of the pressurizing pumps 6 and 6 ', and a vaporizer provided with a heater. 7
It is connected to the. The outlet of the vaporizer 7 has a heating mechanism,
Further, it is connected to an inlet of a cracker 8 in which a catalyst for catalytic cracking is filled, and an outlet of the cracker 8 is sequentially connected to a cooler 9 and a gas-liquid separator 10, which together generate the cracked gas. It is defined as part 11.

The outlet of the decomposition gas generating section 11 is connected to a pressure fluctuation type adsorption / purification section 12. The pressure fluctuation type adsorption purification unit 12 has four adsorption cylinders A, B, C and D each filled with an adsorbent, and the adsorption process, the pressure reduction process, the regeneration process, and the pressurization process are sequentially switched. And is connected to the product gas outlet pipe 13. Further, the outlet 14 for the regenerated exhaust gas is connected to the introducing pipes 4 and 4'for the sealing gas. In this manner, the decomposition gas generation section 11 and the pressure fluctuation type adsorption purification section 12 are combined to form the gas generation apparatus of the present invention as a whole.

In the above-mentioned gas generator, a case where hydrogen gas is manufactured as a product gas mainly using methanol and water as raw materials will be described as an example. Methanol is stored in the supply tank 1 for the raw material liquid and water is stored in the supply tank 2, and carbon dioxide is introduced from the seal gas cylinder 3 into the supply tanks 1 and 2 through the introduction pipes 4 and 4 ′ to enter the liquid raw material. By blowing out and aerating methanol and water with highly soluble carbon dioxide, impurities such as dissolved nitrogen and oxygen are replaced with carbon dioxide, and the air is retained and left in the space together with the supply tank 1 And 2 completely vented from the top vent. In this way, the supply tanks 1 and 2
Will be sealed by carbon dioxide.

Methanol and water in the supply tanks 1 and 2 are pressurized by pressurizing pumps 6 and 6 ', respectively, and when methanol and water are supplied to the vaporizer 7 at a mixing ratio of 1: 2 in molar ratio, the methanol and water are heated to generate methanol. And a mixed gas of water.
The mixed gas enters the decomposer 8 which has been heated and contacts the decomposition catalyst to generate a decomposed gas in a ratio of 1 mol of carbon dioxide to 3 mol of hydrogen. The decomposed gas is cooled to room temperature by the cooler 9 to condense excess water, the water is separated and removed by the gas-liquid separator 10, and then sent to the pressure swing adsorption purification section 11.

Each of the adsorption columns A to B is filled with, as an adsorbent, for example, alumina, activated carbon, and zeolite in order from the gas inlet side (lower part). The pressurized gas emitted from the gas generating portion is supplied to the adsorption cylinder in the adsorption process, for example, the A cylinder in the operation process diagram shown in FIG. Carbon dioxide (including sealing gas) that is a mixed component and impurities such as carbon monoxide, hydrocarbons, and water vapor are adsorbed and removed, and purified hydrogen is extracted from the product gas outlet pipe 13.

As shown in FIG. 2, the steps of each suction cylinder are sequentially switched and operated. When the adsorption in the A cylinder is completed, the gas from the gas generating portion is regenerated by adsorbent material, repressurized, and switched to the standby C cylinder to be supplied, where the adsorption purification is continued. On the other hand, after the adsorption, the A cylinder that is in a high pressure state is regenerated and equalized with the B cylinder that is in a low pressure equalization stage (high pressure equalization).
Further, the pressure is equalized (low pressure equalization) with the D cylinder that has completed the regeneration. Subsequently, blow open the valve of the discharge pipe 16, by passing in the opposite direction to the time of purifying a portion of the terminated C tube of the gas of the adsorption step together when to落圧the inner cylinder to near atmospheric pressure Carbon dioxide desorbed from the adsorbent and other impurities are discharged from the regeneration exhaust gas discharge pipe 14 to regenerate the adsorbent. Cylinder A, which has been regenerated, is pressure-equalized (low pressure equalization) with C-cylinder in a high pressure equalization state, and then adsorption is completed,
The pressure is equalized (high pressure equalization) between the B cylinder in a high pressure state,
Further, the pressure is increased with purified hydrogen gas for finishing, and the product is prepared for the next adsorption step.

Since most of the blow gas during regeneration of the adsorption column is carbon dioxide, part or all of it is used as a gas for sealing the liquid raw material, if desired. In this case, the regeneration exhaust gas is supplied to the supply tanks 1 and 2 by opening the valve of the pipe that connects the exhaust pipe 14 for the regeneration exhaust gas and the introduction pipe 4 for the sealing gas.

[0020]

Example 1 A hydrogen gas production experiment was conducted using methanol and water as raw materials using a gas generator having the same configuration as shown in FIG. A liquid raw material supply tank made of a stainless steel tube having a diameter of 20 cm and a height of 1 m, an introduction pipe having an inner diameter of 4 mm for blowing a sealing gas into the bottom, an introduction pipe having a large number of small holes at the tip, and an inner diameter of 10 mm at the top. Using a ventilation port, a feed port for raw materials, a feed port for raw materials, and a methanol feed tank and a water feed tank equipped with a level gauge, carbon dioxide was blown into each as a sealing gas at 0.2 L / min to obtain a liquid raw material. was kept in a state the nitrogen to which they are dissolved by aeration, oxygen supply tank while continuing flow of sealing gas together when drive off impurities such as sealed with carbon dioxide.

40c of methanol from each supply tank
c / min, water at a flow rate of 36 cc / min up to 10 kg / cm ² by a pressure pump, and while mixing, supply to a vaporizer made of stainless tube with a diameter of 10 cm and a length of 100 cm to heat and vaporize A mixed gas of methanol and water was used. While controlling the temperature of this mixed gas at 280 ° C., a copper oxide-zinc oxide catalyst (N2, manufactured by JGC Chemical Co., Ltd.) was used.
11) 25kg filled with 20cm diameter, filling height 50
After being supplied to a cm 2 stainless steel tube decomposer to decompose it into hydrogen and carbon dioxide, it was cooled to around room temperature by a cooler, and condensed excess water was separated and removed by a gas-liquid separator.

The components of this gas were separated in a pressure swing adsorption purification section to obtain purified hydrogen gas. That is, four stainless steel tubes having a diameter of 8.3 cm and a height of 3 m are provided as the adsorption cylinders of the pressure fluctuation type adsorption purification unit, and alumina balls (made by Mizusawa Chemical Co., Ltd. , Neobead SA) 100 mm, granulated coconut shell activated carbon (Takeda Pharmaceutical Co., Ltd., Shirasagi G2X-7 / 12) 2
400 mm, and 200 mm of molecular sieve 5A (manufactured by Union Carbide Co., 1/16 inch pellet) were filled. Each adsorption column was operated based on the adsorption / regeneration pattern shown in FIG. The flow rate of the gas during purification in the pressure fluctuation type adsorption purification unit was 88 NL / min, and the flow rate of the regeneration gas during regeneration was 35 NL / min. The purity of the product hydrogen gas being purified is measured by a FID gas chromatograph with a small reactor (manufactured by Shimadzu Corporation) to measure methane, carbon monoxide, and carbon dioxide using a Hersche trace oxygen analyzer (manufactured by Osaka Oxygen Industrial Co., Ltd.,
MK3) was used to analyze oxygen, TCD gas chromatograph (manufactured by Shimadzu Corporation) was used to analyze nitrogen, and dew point meter (manufactured by Panametric) was used to analyze water. The results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was carried out except that aeration and sealing were not performed by blowing carbon dioxide into the methanol and water supply tanks, and the purity of the product hydrogen gas during purification was analyzed. The results are shown in Table 1.

Comparative Example 2 Alumina balls (Mizusawa Chemical Co., Ltd.) were sequentially placed inside the adsorption cylinder having a diameter of 8.3 cm and a height of 4.5 m from the raw material gas inlet side.
Made, Neo-Bead SA) 100 mm, Granulated coconut shell activated carbon (Takeda Yakuhin Kogyo, Shirasagi G2X-7 / 12) 3000
mm, molecular sieve 5A (manufactured by Union Carbide Co., 1/16 inch pellet) was filled in 900 mm, the same operation as in Comparative Example 1 was carried out, and the results of analyzing the purity of the product hydrogen gas during purification are shown in Table 1. .

[0025]

[Table 1] Table 1 Product Impurity Concentration in Hydrogen Gas (ppb) Nitrogen Oxygen Oxygen CO ₂ CO Methane Water Example 1 <1000 <2 15 20 <1 50 Comparative Example 1 7300 520 20 120 <1 55 Comparative Example 2 2500 140 15 70 <1 59

[0026]

INDUSTRIAL APPLICABILITY The present invention is one in which a liquid raw material supply tank is aerated and sealed with a gas that is chemically stable with respect to the liquid raw material and strongly adsorbable to the adsorbent.
The removal of nitrogen, oxygen, etc., which was difficult to remove with the material , was prevented in advance. By combining the pressure fluctuation type adsorption purification section with the decomposition gas generation section, it became possible to generate purified gas with high purity. And, it becomes unnecessary to adsorb and remove the impurity gas having small adsorptivity such as nitrogen and oxygen in the pressure fluctuation type adsorption purification section, and it is possible to drastically reduce the adsorbent required in a large amount by the conventional method. In addition to improving the purity of the product gas, it has become possible to downsize the device.

[0027]

[Brief description of drawings]

FIG. 1 is a flow sheet of a gas generator of the present invention.

FIG. 2 is an adsorption / regeneration pattern process diagram of a pressure fluctuation type adsorption / purification unit.

[Explanation of symbols]

1, 2 supply tank 4, 4'introduction tube 5, 5'supply pipe 6, 6'pressurizing pump 7 vaporizer 8 decomposer 11 Generator 12 Adsorption Purification Department 13 Product gas outlet pipe 14 Recycled exhaust gas outlet pipe A, B, C, D adsorption cylinder

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI C01B 31/20 C01B 31/20 A (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 7/00 C01B 3 / 00-3/58 C01B 31/00-31/36 F17C 13/00-13/12 B01D 53/04

Claims (5)

(57) [Claims] 1. A generation part of a decomposition gas for vaporizing a liquid raw material to catalytically decompose it, and a pressure fluctuation type adsorption purification part for obtaining a product gas of one or more kinds by separating the gas generated by the catalytic decomposition into its components. In a gas generator comprising a combination of the above, a liquid raw material supply tank in which a sealing gas introduction pipe is provided at one or more locations, a vaporizer connected to the supply tank, and an outlet of the vaporizer. The liquid raw material is provided with a decomposer connected to the inside and filled with a catalyst, and a pressure fluctuation type adsorption refiner composed of a plurality of adsorption cylinders connected to the decomposer and filled with an adsorbent inside. The supply tank of
Be chemically inert to the liquid material, and the gas generator, characterized in that that will be sealed by a gas having a strong adsorption against the adsorbent. 2. The gas generator according to claim 1, wherein at least one of the introducing pipes for the sealing gas is opened in the lower liquid raw material of the supply tank so that the liquid raw material can be aerated by the sealing gas. 3. The gas generator according to claim 1, wherein an outlet pipe for the regenerated exhaust gas discharged from the pressure fluctuation type adsorption / purification unit is connected to the sealing gas inlet pipe. 4. The sealing gas is carbon dioxide.
The gas generator according to. 5. The gas generator according to claim 4, wherein the liquid raw material is at least one of methanol, methyl formate and water, and the product gas is hydrogen and / or carbon monoxide.