JPH09202889A - Production of town gas and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both a method for producing a town gas by which the changeover of a gas species of a low to a high calorific values can be carried out at a low cost due to the ability to produce many kinds of town gases ranging from the low to the high calorific values and an apparatus therefor. SOLUTION: This method for producing a town gas 22 comprises hydrogenating and desulfurizing a mixture of a >=3C light hydrocarbon with an enriched hydrogen-containing gas 5 produced by heating and vaporizing methanol 2 and water 3 in a hydrogen gas producer 4 in a hydrogenating desulfurizer 9, then carrying out the steam reforming (a methanizing reaction) with a methane reformer 11 and thereby generating a crude raw material town gas 12. A part of the enriched hydrogen-containing gas 5 produced with the hydrogen gas producer 4 is passed through an enriched hydrogen-containing introduction flow passage 14 and mixed with the crude raw material town gas 12 using a calorific value regulator 15. Thereby, the calorific value of the crude raw material town gas 12 is regulated. As a result, many kinds of the town gases ranging from a low to a high calorific values can be produced. Furthermore, the apparatus for producing the town gases is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing city gas capable of producing various kinds of city gas from low calorific value to high calorific value. More specifically, the method for producing city gas capable of producing many types of city gas from low calorific value to high calorific value, which is used when converting city gas of low calorific value gas type to city gas of high calorific value gas type, and It relates to the device.

[0002]

2. Description of the Related Art At present, there are more than two hundred city gas companies all over Japan, and there are various types of city gas handled by many city gas companies. Currently, there are 13 types, as shown in Table 1 below, from low heat value (low calorie) gas species containing hydrogen as the main component to high heat value (high calorie) gas species of natural gas containing methane as the main component. doing.

[0003]

[Table 1]

Therefore, in the city gas industry, in order to improve the convenience, economy, safety, etc. of city gas, in the future, the present 13 kinds of gas species will be widely used mainly in large cities. Liquefied natural gas (LNG) used as a raw material 1
3A (12,600~13,800kcal / Nm ³⁾
It is being promoted to integrate these gas types into city gas. Under such circumstances, even in small and medium-sized city gas companies in rural areas, where it was difficult to introduce natural gas due to poor geographical conditions compared to city gas companies in large cities, gas species were converted to natural gas I have to do it.
However, such conversion of gas species is once required for replacement of natural gas with an alternative natural gas (SNG: Substitute).
After the production of Natural Gas), it is necessary to convert the gas species to a natural gas system. In such a concrete gas type conversion work, it is necessary to replace parts of each gas consuming equipment of each customer. Since it is not possible to perform such conversion work at the same time because the gas appliances must be adjusted, it is necessary to perform the conversion work of gas species while dividing each region, and such conversion work is required. A period of several months is required to completely complete. Therefore, during the conversion work, the city gas production plant must produce and supply both the current low-calorie gas and high-calorie gas at the same time.

[0005]

However, in the conventional alternative natural gas (SNG) production technology as shown in FIG. 6, in the SNG production equipment, methane gas is produced as a main product, so that hydrogen is the main component. It was impossible to produce such low-calorie city gas. for that reason,
A city gas company that intends to switch from a low-calorie gas type to a high-calorie gas type city gas using such an SNG manufacturing facility will have to maintain the existing low-calorie gas manufacturing facility in maintenance costs and construct a new one. The maintenance cost of the SNG manufacturing equipment that does not become necessary is required, and various problems such as securing a site for the newly installed SNG manufacturing equipment have to be solved. Therefore, it has been desired to develop an alternative natural gas (SNG) production facility capable of producing a wide variety of gas species from low-calorie gas species to high-calorie gas species.

On the other hand, the applicant of the present patent application has previously proposed that the alternative natural gas which facilitates starting / stopping / changing the load of the plant, has high gasification efficiency and stable quality, and is excellent in operability and economy. As a gas production method, a method has been proposed in which a production process as shown in FIG. 6 is performed (see Japanese Patent Laid-Open No. 4-366200). However, in the method for producing the alternative natural gas,
Since the high calorie city gas is produced through the production process as shown in FIG. 6, various excellent effects as described above can be exhibited, but the hydrogen generator in the production process is used. The produced hydrogen-rich gas is mixed with light hydrocarbons and used as a hydrogen source for hydrodesulfurization, and the rest is spent for producing methane gas in a methane reformer. Therefore, it has been difficult to produce a low-calorie city gas containing hydrogen as a main component. In addition, even if the hydrogen gas production in the hydrogen generator is produced in excess of the theoretical amount for producing methane gas from light hydrocarbons in the methane reformer, the total amount is converted to methane gas in the methane reformer. Therefore, there is a large time lag in the heat quantity adjustment, and it was practically impossible to adjust the heat quantity of the city gas to a low heat quantity.

[0007]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventor has found that a portion of a hydrogen-rich gas obtained by steam reforming methanol and water in a hydrogen generator is used as a raw material. The present invention has been completed based on the finding that low-calorie city gas containing hydrogen as a main component can be produced by using it as a part of city gas. That is, the method for producing city gas of the present invention capable of producing various types of city gas from low calorific value to high calorific value is carried out by steam reforming light hydrocarbon having 3 or more carbon atoms, methanol and water with a hydrogen generator. In the method for producing a city gas, in which a raw material city gas is generated by hydrodesulfurizing a mixture with a hydrogen-rich gas, the raw material city gas is hydrogenated. It is characterized in that the calorific value of the raw material city gas is adjusted by mixing a part of the hydrogen-rich gas containing gas generated by the generator. In addition, another embodiment of the present invention is a city gas production apparatus capable of producing various types of city gas from low calorific value to high calorific value, using light hydrocarbons having 3 or more carbon atoms and methanol as raw materials, In a city gas production apparatus for producing city gas, a hydrogen gas generator for generating a hydrogen-rich gas from methanol and water, and a mixture of the hydrogen-rich gas and the light hydrocarbon having 3 or more carbon atoms are hydrodesulfurized. To produce a raw material city gas by steam reforming (methanation reaction) of a mixture of a hydrodesulfurizer for removing sulfur content and the hydrodesulfurized hydrogen-rich gas and light hydrocarbons. A methane reformer and a heat quantity adjusting tank for adjusting a heat quantity by mixing a part of the hydrogen-rich gas generated by the hydrogen generator with the raw material city gas. Ah .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

[I] Raw materials (1) Light hydrocarbons Light hydrocarbons used as raw materials in the method for producing city gas of the present invention capable of producing various types of city gas from low heat amount to high heat amount include propane, butane, and LP.
It is a hydrocarbon having 3 or more carbon atoms such as G and naphtha, and is generally a lower hydrocarbon having 3 to 10 carbon atoms, preferably 3 to 7 carbon atoms, particularly preferably 3 to 5 carbon atoms. (2) Methanol As methanol used as a raw material for generating a hydrogen-rich gas in a hydrogen gas generator in a method for producing a city gas capable of producing various types of city gas from low heat quantity to high heat quantity of the present invention, Methyl alcohol, industrial methyl alcohol, which is generally produced by carbonization of wood, or is a high-pressure contact with synthetic raw material gas consisting of carbon monoxide and hydrogen obtained from coke, coal, natural gas, etc. It was synthesized by the reaction. (3) Other raw materials In addition to the above raw materials, water is indispensable to generate a hydrogen-rich gas from methanol in a hydrogen gas generator. Furthermore, in order to adjust this low calorific city gas to a low calorific city gas with a higher gas specific gravity, the Wobbe index (WI) and the combustion rate (CPI) are deviated, so that air and light hydrocarbons are mixed. Is required.

[II] City Gas Manufacturing Apparatus A city gas manufacturing apparatus 1 according to the present invention, which is capable of manufacturing various kinds of city gas from low calorific value to high calorific value, is as shown in FIG.
A hydrogen gas generating step 6 for generating a hydrogen-rich gas 5 in a hydrogen gas generator 4 using methanol 2 and water 3 as raw materials;
A hydrodesulfurization step 9 of removing a sulfur content by hydrodesulfurization of a mixture of the hydrogen-rich gas 5 and a light hydrocarbon having 3 or more carbon atoms (for example, LPG) 7 by a desulfurizer 8, and the hydrodesulfurization Methane reforming in which water 10 is added to a mixture of a hydrogen-rich gas 5 and a light hydrocarbon 7 having a carbon number of 3 or more, and a raw material city gas 12 is generated by steam reforming (methanation reaction) in a methane reformer 11. Step 13 and a heat quantity for adjusting the heat quantity by mixing a part of the hydrogen-rich gas 5 generated by the hydrogen generator 4 with the raw material city gas 12 by the heat quantity controller 15 through the hydrogen-rich gas introducing passage 14. The adjustment process 16 and, if necessary, an air introduction flow path 18 for mixing the air 17 and a light hydrocarbon introduction flow path 19 for mixing the light hydrocarbons, or, if necessary, a decarbonation device (CO ₂ removal device) 20 Gas 12
It comprises a decarbonation step 21 for removing CO ₂ and water therein to improve the concentration of methane gas and hydrogen.

(1) Hydrogen Gas Generating Step In the hydrogen gas generating step 6 of the present invention, although not shown, methanol 2 as a raw material is pressurized to a reaction pressure by a methanol pump and mixed with water 3. , Heating the mixture of methanol 2 and water 3 with a methanol evaporator.
After being vaporized, the temperature is raised to a reaction temperature of about 300 to 360 ° C. with a methanol superheater and sent to the hydrogen gas generator 4.
A mixture of this methanol 2 and water 3 is used as a hydrogen gas generator 4
The hydrogen-rich gas 5 is produced by causing the following chemical reaction by passing through the reaction tube filled with the hydrogenation catalyst therein and adjusted to a temperature of about 300 to 360 ° C. CH ₃ OH + H ₂ O → 3H ₂ + CO ₂ Due to such a chemical reaction, the above-mentioned hydrogen-rich gas 5 containing a small amount of CO and CH ₄ and a large amount of H _{2 in} the product is obtained. Will be converted. Production of low calorific city gas In order to produce a low calorific city gas, which is a feature of the present invention, it is necessary to perform hydrodesulfurization of light hydrocarbons (eg, butane) 7 in a hydrodesulfurization step 9 described later. It is necessary to produce the hydrogen gas (hydrogen-rich gas) 5 by using an excess amount of methanol 2 in excess of the theoretical amount of hydrogen gas. The hydrogen gas generating step 6 can be combined with a reaction tower of a steam reforming step 13 in which steam reforming (methanation reaction) is performed in a methane reformer 11 described later. That is, a part of the tubes in the reaction tower was filled with a hydrogenation catalyst and used as a reaction tube in a separate channel, and methanol was
If the mixture of water and water 3 is carried out under the same temperature conditions as the steam reforming step 13, the hydrogen gas generating step 6 and the steam reforming step 13 can be carried out in one reaction tower.

(2) Desulfurization Step As the desulfurizer 8 used in the desulfurization step 9 of the present invention, a desulfurizer generally used for desulfurization of city gas can be used. For example, the structure of the heat exchange system described in JP-A-4-366200 can be mentioned. The structure of the heat exchange system is not shown, but the upper channel is divided into two parts, a gas inlet and an outlet, by a partition plate, and U
Forming a letter flow path, and a nimox catalyst on the inlet side pipe of the partition,
The outlet side tube (return path) is filled with zinc oxide. From the shell-side lower heating medium inlet, which is the outside of the tube, a heating medium previously adjusted to a temperature of about 300 to 400 ° C. in a heating medium heating furnace is caused to flow upward between the baffle plates to activate the catalyst at its activation temperature. Hold on. In this case, the hydrogen-mixed raw material gas (hydrogen-rich gas) 5 sent to the desulfurization tower 8 and the catalyst filled in the desulfurization tower 8 together have a large heat capacity flowing in series with the heating medium heating furnace → the raw material superheater → the desulfurization tower. A constant temperature is always maintained due to the temperature control of the heating medium.

(3) Methane Reforming Step The desulfurized light hydrocarbon (eg, butane) 7 and the raw material of the hydrogen-rich gas 5 are mixed with the steam 10 in the raw material / steam mixer, and then the raw material / steam superheater. 320 to 40
It is sent to a reaction tower whose reaction temperature is adjusted to about 0 ° C., and steam reforming (methanation reaction) is performed in the methane reformer 11. In this reaction tower, both nickel reforming (decomposition) reaction and methanation reaction are performed simultaneously under a specific reaction condition, especially at the same temperature, using a nickel-alumina catalyst in which nickel is supported on an alumina carrier. Go in one step,
Convert to high calorie gas with low CO content and high CH ₄ content.

Methane reforming reaction This methane reforming reaction will be explained using butane as an example.
First, a part of butane (hydrocarbon) is heated by steam on the catalyst and decomposed, and the following chemical reaction occurs, whereby CO and H ₂ are generated. C ₄ H ₁₀ + 4H ₂ O → 4CO + 9H ₂ Then, as such gasification progresses, the following chemical reaction further occurs, whereby a methanation reaction and a shift reaction by CO and H ₂ occur. CO + H ₂ O → CO ₂ + H ₂ CO + H ₂ O ← CO ₂ + H ₂ CO + 3H ₂ → CH ₄ + H ₂ O CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O Such a synthetic reaction is performed in one tower reactor. It can also be done in one step. As the reaction tower in which such methane reforming is carried out, the same type as the above heat exchange system shell tube type fixed tube plate structure can be used, and the methanation of nickel / alumina type catalyst etc. is carried out in the reaction tube. The catalyst is charged, and the heat medium having a temperature of preferably 320 to 400 ° C., which is divided by the heat medium distribution control valve from the shell side lower heat medium inlet which is the outside of the tube, is flowed in the upper direction to bring the catalyst to the activation temperature. Hold.

As described above, when butane is used as the light hydrocarbon 7 and hydrogen-containing gas (3H ₂ + CO ₂ ) 5 produced by using methanol 2 as a raw material is used for methanation by a methane reforming reaction. As a result, the following reaction proceeds. C ₄ H ₁₀ + 3H ₂ + CO ₂ → 4CH ₄ + CO ₂ Then, if decarbonation and water are removed from the product gas thus obtained, the methane gas containing a high concentration (rich methane mixture gas 22) The heat of the city gas 23 can be obtained.

(4) Decarbonation Step 12 The raw material city gas 12 which is a mixed gas of the above methane / hydrogen
The CO ₂ removal device can also be used to remove the carbon dioxide gas and moisture therein to increase the concentration of methane gas and hydrogen gas to form the methane-rich mixed gas 22. The CO ₂ removal device is
An apparatus by a pressure swing (PSA) method in which carbon dioxide, zeolite, silica gel, or other adsorbent is filled to perform decarbonation under pressure / decompression, and the like. Decarbonation gas can be performed by the method described in JP-A-2-281096.

(5) Mixing adjustment step The above-mentioned methane-rich mixed gas 22 and methane / hydrogen mixed gas 1
The raw material city gas consisting of 2 is used as the city gas with an appropriate amount of heat 23
In order to achieve the above, the amount of heat is adjusted by adjusting the concentrations of methane gas and hydrogen gas in the raw material city gas 12. To adjust the heat quantity of the raw material city gas 12,
It is important to use the hydrogen-rich gas introduction flow path 14 and the calorie controller 15 equipped with a gas analyzer. Further, the heat quantity controller 15 may be provided with an introduction flow passage 18 for mixing air and an introduction flow passage 19 for mixing light hydrocarbons, if necessary.

(A) Hydrogen-rich gas-introducing flow path between hydrogen generator and heat quantity controller Heat quantity adjustment in the city gas production apparatus 1 of the present invention capable of producing various kinds of city gas from low heat quantity to high heat quantity Bowl 15
In addition, since the raw material city gas 12 composed of the methane-rich mixed gas obtained by the methanation reaction of the mixture of the hydrogen-rich gas 5 and the light hydrocarbons 7 in the methane reformer 11 has too much heat, By increasing the concentration of hydrogen gas in the raw material city gas 12 by mixing a part of the hydrogen-rich gas 5 generated by the hydrogen generator with the raw material city gas 12 composed of this methane-rich mixed gas. Hydrogen-rich gas 5 generated by the hydrogen generator 4 for controlling the heat quantity of the raw material city gas 12 by reducing the concentration of methane gas
Is provided with a hydrogen-rich gas introducing passage 14 for guiding a part of the gas to the heat quantity controller 15. In this way, the raw material city gas 12 diluted with the hydrogen-rich gas 5 becomes a methane-containing gas diluted with a large amount of hydrogen because the hydrogen concentration is further increased by increasing the mixing amount of the hydrogen-rich gas. Such a methane-containing gas becomes city gas of the same quality as the low calorific gas produced by the conventional low calorific city gas production apparatus.

(B) Introductory flow path for mixing air with the raw material city gas Even if the raw material city gas 12 is diluted with the hydrogen-rich gas 5 as described above to obtain a predetermined amount of heat, the specific gravity of the gas is If too small, Wobbe index (WI) and burning rate (C
Since PI) is deviated, as shown in FIG. 3, an air introduction passage 18 and a light hydrocarbon introduction passage 19 for mixing the air 17 and the light hydrocarbons 7 with the raw material city gas 12 are provided. By mixing such air 17 and light hydrocarbons 7, a wide variety of low calorific city gas 23 can be obtained.

(C) Introductory flow path for mixing light hydrocarbons with raw material city gas Different from the above-mentioned low calorie city gas, when a higher calorie city gas is required, the amount of methanol 2 used is limited. However, the hydrogen gas concentration is reduced as much as possible to increase the concentration of methane gas in the city gas, and as shown in FIG. 4, a light hydrocarbon having a carbon number of 3 or more such as butane, propane, and naphtha, which are raw materials, is separately provided. Hydrocarbon introduction passage 19 for mixing
By providing, the city gas 23 having a high calorific value can be obtained.

(D) Gas Analyzer Heat quantity controller 15 in the city gas producing apparatus 1 of the present invention capable of producing a wide variety of city gas from low heat quantity to high heat quantity
Is equipped with a gas calorimeter to measure the amount of heat of city gas.

[III] City Gas (1) Control of Heat Quantity of City Gas The hydrogen-rich gas introduction channel 14, the introduction channel 18 for mixing air, and the light hydrocarbon introduction channel 19 for mixing light hydrocarbons. Hydrogen-containing gas 5 introduced, air 1
By adjusting the mixing ratio of 7 and light hydrocarbons 7, the concentrations of hydrogen gas, air and light hydrocarbons in the city gas 23 can be adjusted. Therefore, as a result, the heat quantity and combustibility (specific gravity, combustion speed, Wobbe index) of city gas can be freely adjusted. (2) Integration of city gas Therefore, if a method and an apparatus for producing city gas capable of producing such various types of city gas from low heat quantity to high heat quantity are used, the city gas with low heat quantity and the city with high heat quantity can be used. There is no need to install and operate an excessive city gas production facility at the time of gas switching, and it is possible to integrate it into city gas of 13A gas type.

[0022]

The present invention will be described more specifically with reference to the following experimental examples. Examples 1 to 9 Hydrogen as a raw material for a hydrogen gas generator was pumped to 6.5 kg / h.
12 kg / cm ² G which is the reaction pressure at a speed of r (appropriate amount)
2. Increase the pressure to about the same level and add degassed water to this 3.
It is supplied at a rate of 6 kg / hr, the methanol is vaporized in a methanol evaporator, and after mixing with steam, the temperature is raised to a reaction temperature of about 320 to 360 ° C. in a methanol / steam superheater to be a hydrogen gas generator. Transferred. This methanol /
10 kg of hydrogenation catalyst in the hydrogen gas generator
The gas containing hydrogen-rich gas having a gas component as shown in the outlet gas of the hydrogen generator shown in Table 2 was passed through a reaction tube having a temperature of about 320 to 360 ° C.
It was produced at a rate of hr.

Desulfurizer Next, 10.2 kg / hr of this hydrogen-rich gas is used as a raw material for light hydrocarbons (LPG, i-C ₄ H ₁₀ / n-C ₄ H _10).
= 27.0 / 71.0) and the ratio of 1: 12.6 (capacity)
600 kg of Nimox catalyst.
Then, the mixture was introduced into a desulfurization tower of a heat exchange system filled with 600 kg of zinc oxide, the nimox catalyst adjusted to a temperature of 320 to 360 ° C. with a heating medium was maintained at its activation temperature, and the raw material mixture was adjusted to 0.2 ppm by weight or less. Desulfurized to concentration.

Steam reformer (methane reforming) The raw material mixture desulfurized as described above is mixed with steam supplied at a rate of 867 kg / hr in the raw material / steam mixer, and then the raw material / steam superheat 320-
It was sent to a steam reformer (reaction tower) adjusted to a reaction temperature of 360 ° C. to carry out a methane reforming reaction. In the methane reforming reaction tower, 800 kg of a highly active catalyst (nickel / alumina catalyst) in which nickel was supported on an alumina carrier was packed under specific reaction conditions in which the reaction rate in one step was increased. , The isothermal reforming (decomposition) reaction and the methanation reaction are performed at a reaction temperature of about 320 to 360 ° C., and the gas components as shown in the methane reformer outlet gas in Table 2 are converted into high calorific city gas. Let

[0025]

[Table 2]

Decarbonation Device By removing decarbonation and water from the product gas thus obtained, a high calorific city gas containing methane in a high concentration was obtained.

Heat quantity controller CO ₂ content obtained by methane reforming reaction in the steam reformer (reaction tower) is 10.7% by volume, and CH ₄ content is 43.2% by volume. Hydrogen-rich gas (reformed hydrogen) produced by the hydrogen gas generator for high calorific city gas (methane rich) generated at a rate of 523 kg / hr
Of the raw material liquefied natural gas (heated LPG) having the composition shown in Table 2 and air at a ratio shown in Table 3,
9 kinds of gases having different heat amounts of 4C / 3,600 to 6B / 5,000 shown in Fig. 3 were produced, and their specific gravity, Wobbe index, and burning rate were measured. Table 3 shows the results.

[0028]

[Table 3]

[0029]

INDUSTRIAL APPLICABILITY The method and apparatus for producing city gas capable of producing various kinds of city gas from low heat quantity to high heat quantity according to the present invention can produce many kinds of city gas from low heat quantity to high heat quantity. Since it is possible, there is no need to build a new alternative natural gas (SNG) production facility when converting from low calorific gas type city gas to high calorific gas type city gas. It is easy to convert city gas to high-calorie gas species, and to unify city gas throughout the country without the need to secure the necessary cost and maintenance costs for existing low-calorie gas production equipment and costs for new equipment. Therefore, the convenience, economy, safety and the like of city gas can be improved.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a city gas production apparatus according to the present invention in which the amount of heat can be adjusted.

FIG. 2 is a process explanatory view in the case of producing low calorific value city gas (No. 1) by the city gas manufacturing apparatus of the present invention.

FIG. 3 is a process explanatory diagram in the case of producing a low calorific value city gas by another method in the city gas manufacturing apparatus of the present invention.

FIG. 4 is a process explanatory view in the case of producing a low calorific value city gas by another method in the city gas production apparatus of the present invention.

FIG. 5 is a process explanatory view in the case of producing high calorific value city gas by the city gas production apparatus of the present invention.

FIG. 6 is a schematic explanatory view of a conventional high calorific value city gas production apparatus.

[Explanation of symbols]

1 City gas production equipment capable of producing many types of city gas 2 Methanol 3 Water 4 Hydrogen gas generator 5 Hydrogen-rich gas 6 Hydrogen gas generation process 7 Light hydrocarbons with 3 or more carbon atoms (eg LPG) 8 Desulfurizer 9 Hydrodesulfurization process 10 Water 11 Methane reformer 12 Raw material city gas 13 Methane reforming process 14 Hydrogen-rich gas introduction flow path 15 Heat quantity regulator 16 Heat quantity adjustment step 17 Air 18 Air introduction flow path 19 Light hydrocarbon introduction Flow path 20 Decarbonation device (CO ₂ removal device) 22 City gas 21 Decarbonation process

Claims (7)

[Claims] 1. A mixture of a light hydrocarbon having 3 or more carbon atoms and a hydrogen-rich gas generated by steam reforming methanol and water in a hydrogen generator is hydrodesulfurized and then steam reformed ( In the method for producing a city gas in which a raw material city gas is generated by performing a methanation reaction), the raw material city gas is mixed with a part of the hydrogen-rich gas generated by the hydrogen generator. A method for producing city gas capable of producing various types of city gas from low calorific value to high calorific value, which is characterized by adjusting the calorific value of the city gas. 2. The calorific value of the raw material city gas is adjusted by mixing light hydrocarbons and / or air with the raw material city gas, wherein the calorific value of the raw material city gas is low to high. A method for producing city gas capable of producing various types of city gas. 3. The low calorific value to high calorific value according to claim 1 or 2, wherein the raw material city gas produced by performing steam reforming (methanation reaction) is purified by decarboxylation and dehydration. A method for producing city gas capable of producing various types of city gas. 4. A city gas production apparatus for producing city gas using a light hydrocarbon having 3 or more carbon atoms and methanol as raw materials, and a hydrogen gas generator for producing a hydrogen-rich gas from methanol and water, A hydrodesulfurizer for removing a sulfur content by hydrodesulfurizing a mixture of a hydrogen-rich gas and a light hydrocarbon having 3 or more carbon atoms, and the hydrodesulfurized hydrogen-rich gas and a light hydrocarbon. Methane reformer for generating a raw material city gas by steam reforming (methanation reaction) of the mixture and a part of the hydrogen-rich gas generated by the hydrogen generator is mixed with the raw material city gas. An apparatus for producing city gas, which is capable of producing various types of city gas from low calorific value to high calorific value, characterized in that it is configured with a calorie controller that regulates the calorific value. 5. A large amount of heat from a low amount of heat to a high amount of heat according to claim 4, wherein a heat quantity adjusting tank for adjusting heat quantity by mixing light hydrocarbons and / or air with the raw material city gas is provided. City gas production equipment capable of producing various types of city gas. 6. The reactor according to claim 4, wherein the hydrogen gas generator and the methane reformer are combined into an integrated structure to produce various kinds of city gas from low heat quantity to high heat quantity. Manufacturable city gas production equipment. 7. A low calorific value to a high calorific value according to claim 4, wherein a decarbonation device for decarbonating and dehydrating the raw material city gas produced by the methane reformer is provided. City gas production equipment capable of producing various types of city gas.