JPS63317595A - Production of high-btu town gas from methanol - Google Patents

Abstract

PURPOSE:To obtain the titled gas of high methane yield economically in a simple manner, with no carbon separating out, by producing a methane-contg. gas through only one step specific reaction process from a mixture of methanol and water. CONSTITUTION:A mixture of methanol and water is heated to the temperature required, by heat exchange through heating medium followed by reducing the content of the sulfur compounds present, and also, through a catalyst in which a Ni-based matter has been carried on an alumina-based carrier of decreased specific surface area,is made to react at <=ca. 300 deg.C to generate a methane- contg. gas. Water is separated from said gas followed by CO2-removal, dehydration and BTU-enhancement by butane incorporation, thus obtaining the objective high-BTU town gas in a steady manner. The water to be mixed with the methanol and the heat for heating the heat transfer medium are partly supplied externally at the startup, the rest from the water separated from the methane-contg. gas and from the heat of reaction produced at the generation of said gas, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing city gas using methanol as a raw material.

(Technology background) Recently, LNG (g
However, in the case of LNG, it is necessary to transport and store it at an extremely low temperature of -162°C, and city gas companies in small and medium-sized cities have difficulty in transporting and storing it. There are many technical and economic problems regarding such matters. For this reason, it is possible to transport it as a liquid at room temperature.
Progress is being made in developing methods for producing city gas using methanol, which is easy to store, as a raw material.

In addition to the above-mentioned advantages in terms of transportation and storage, methanol can be produced at low cost and from abundant resources such as coal and natural gas produced overseas.
It can be obtained permanently, and also contains sulfur, nitrogen,
It has the advantages of not containing impurities such as metals and requiring no desulfurization work, and is seen as a promising future city gas raw material.

(Prior art and its problems) Conventionally, as a means for producing city gas using methanol as a raw material, the method described in Japanese Patent Publication No. 57-24835, for example, is known.

This conventional method involves catalytically cracking a raw material mixture of methanol and water in the presence of a ruthenium (Ru) catalyst, and
2) A gas containing -carbon oxide (CO) and carbon dioxide (CO2) is produced, and hydrogen and -carbon oxide are methanated. Note that after this methanation, decarboxylation, dehydration, and pA amount adjustment are performed.

According to such conventional means, since the gas produced by catalytic cracking is further subjected to a methanation operation, problems arise in that the manufacturing cost is increased, the manufacturing efficiency is lowered, and the device structure becomes complicated and large.

(Problems to be Solved by the Invention) The problems to be solved by the present invention are to generate a methane-containing gas from a mixed raw material of methanol and water in only one reaction step, and to use methanol only during startup. The purpose is to eliminate the need for supplying fuel for heating raw materials and water to be mixed with methanol.

(Means for Solving the Problems) The technical means taken by the present invention to solve the above problems is to heat a mixture of methanol and water to a required temperature by heat exchange with a heat medium, and then convert the mixture of sulfur compounds into A methane-containing gas is directly generated by reacting under low temperature reaction conditions of about 300°C or less via a nickel-based catalyst supported on an alumina-based carrier with a reduced content and specific surface area. After separating water from the contained gas, high calorific city gas is constantly produced through the steps of carbon dioxide removal, dehydration, and heat increase by adding butane, and the water to be mixed with the methanol and the heat source for heating the heat medium are as follows: In addition to being supplied from the outside at the time of start-up, the entire amount is supplied by water separated from the methane-containing gas during the manufacturing process and reaction heat generated when the methane-containing gas is generated.

(Detailed Description of the Invention) Hereinafter, the method for producing high-calorie city gas as a methanol raw material of the present invention will be described in detail based on the process flow shown in FIG.

The raw material methanol is mixed with water and sent to the reactor (1).

At this time, the mixed raw material of methanol and water is heated and vaporized by recovering the heat of the reaction gas coming out of the reactor (1) and the heat of the methanation reaction caused by the gas phase contact reaction in the reactor (1). K is sent.

That is, the methanol/water mixed raw material is passed through a preheater (2) in which the reaction gas flows through a heat converter, and an evaporator (in which a heating medium heated by the heat of methanation reaction in the reactor (1) circulates and flows).
3), passes through the superheater (4) sequentially, so that it is preheated in the preheater (2), vaporized in the evaporator (3), further heated in the superheater (4), and then heated in the reactor (1). ) will be sent to.

The reactor (1) is equipped with a preheater (2) and an evaporator (
3) A mixture of methanol and water that has been heated and vaporized in the heater (4) is subjected to a vapor phase contact reaction in the presence of a catalyst to produce a methane-containing mixed gas as a reaction gas. Become.

The catalyst filled in the tube of this reactor (1) consists of a nickel-based carrier supported on an alumina-based carrier with a reduced content of sulfur compounds and a reduced specific surface area.
For example, sulfur compound content (as 504-2) 1.2
Up to % by weight of finely divided r-alumina or finely divided alumina hydrate on a carrier of Ni' and/or
It is made by supporting a nickel substance or its reduced product, or it is made by supporting a reduced product of nickel on a silica-alumina carrier having a specific surface area of 350 m27 g or less. This catalyst has the characteristics of high activity at low temperatures and a methanation rate of 9 Atm.

6,900Kcal/N under reaction conditions of about 300℃ or less
Methane-containing mixed gas (CH472%) with a calorific value of about m3
, about 25% of CO2, and about 3% of H) can be produced in only one stage of reaction.

After water is separated from the generated methane-containing mixed gas, it is decarbonized and dehumidified, and further heated by mixing with butane to produce high calorific value city gas.

Separation of water from methane-containing mixed gas is done in the reaction gas separation tank (5)
The methane-containing mixed gas leaves the reactor (1) and is sent to the reaction gas separation tank (5), where heat is recovered to the methanol/water mixed raw material in the preheater (2). At the same time, the heat is recovered to potassium carbonate vapor in the reboiler (6) of the decarbonation process, and then the Q-cooler (7)
The reactant gas is cooled in the reactor gas separation flff (5) K and then sent to the reaction gas separation flff (5) K.

On the other hand, the methanation reaction by gas phase catalytic reaction in the reactor (1) is an exothermic reaction, and the reaction heat generated here is transferred to the evaporator (3) via the superheater (4) via a heating medium. sent,
In the superheater (4), heat is recovered to the methanol/water mixed raw material that has been evaporated in the evaporator (3), and in the evaporator (3), the methanol/water that has been preheated in the preheater (2) is fed into the evaporator (3).
Heat is recovered to water mixed raw material.

In the above, a molten salt that melts at 142°C is used as the heat medium, and the heat medium circulation path (A) passes through the heat medium storage tank (8), reactor (1), superheater (4), and evaporator (3). The pump (9) operates to circulate and flow, absorbing the reaction heat of the methanation reaction when passing through the reactor (1), and recovering the heat to the methanol/water mixed raw material when passing through the superheater (4) and evaporator (3). , this methanol
The water mixed raw material and the reactor are heated together with the methane-containing mixed gas exiting (1) to the required temperature, that is, the activation temperature.

That is, the heat of the methanation reaction and the heat of the methane-containing mixed gas generated by the reaction cover all of the amount of heat required to generate the methane-containing mixed gas.

Incidentally, since the reaction heat is generated in an amount larger than necessary, the temperature is adjusted by cooling with a heating medium temperature controller (10).

This heat medium temperature regulator (10) is provided between the hot storage tank (8) and the reactor (1).

Also, the reaction gas content is t1%, l! The separated water separated from the methane-containing mixed gas in (5) is mixed with the raw material methanol supplied by the methanol feed pump (11) from an external methanol supply source to be recycled and used as water to create the methanol ψ water mixed raw material. However, the covalent part is discarded.

That is, the entire amount of water required for producing the methanol-containing mixed gas is covered by this separated water.

In the above, water is mixed with methanol to prevent carbon precipitation during the gas phase contact reaction in reactor (1), and the water/methanol molar ratio is adjusted to 0.5 gl. suitable.

When the water/methanol molar ratio is set to 0.7 or more, the amount of heat required to heat the methanol/water mixed raw material to the required temperature increases, and all of that heat is transferred to the methane-containing mixed gas coming out of the reactor (1). In order to cover the heat and reaction heat from the methanation reaction, it is difficult to provide sufficient heat insulation and heat retention, and the burden on the circulation system increases, which is disadvantageous in terms of manufacturing costs.

Further, if the water/methanol molar ratio is set to 0.3X or less, there is a fear that carbon precipitation may occur during long-term steady operation.

Of course, at startup, there is no water separated from the methane-containing mixed gas, and no reaction heat is generated to heat the heating medium, so water must be supplied from outside and the heating medium must be supplied from an external heat source. Although heating is required, after shifting to normal operation, there is no need for this at all, and only methanol needs to be fed.

The startup will be discussed later.

Next, the decarbonation gas step, dehumidification step, and butane heating step are performed by conventional methods.

That is, the methane-containing mixed gas from which water has been separated at a reaction gas content of [411 (5) 1/C] absorbs carbon dioxide (12).
After the potassium carbonate gas is absorbed and removed, the refined gas is led to a water separation tank (16) through coolers (13), (14), and (15), where water is separated.

By removing carbon dioxide gas in the above decarbonation step, the calorific value of the methane-containing mixed gas was reduced to 9,200 Kca〆N m3
It can be increased to a certain extent. Incidentally, this decarbonation gas removal can of course be carried out by other methods such as a dry method (PSA method).

Finally, a required amount of pyIH is mixed with the decarbonated gas and dehumidified purified gas through a mixer (17), and the heat 1 is increased to about 11,000 Kcal/Nm3.

At this time, butane is evaporated by recovering heat from the decarbonated methane-containing mixed gas that has left the carbon dioxide gas absorption tower (12) and before passing through the first cooler (13).

In this way, city gas with high calorific value can be constantly obtained at room temperature.

If the manufacturing process of city gas is shown in a flowchart, the second
It will look like the figure.

Next, although not directly related to the gist of the present invention, some explanation will be given regarding the start-up when carrying out the method for producing high-calorific city gas as a raw material for methanol according to the present invention.

At startup, water for mixing with methanol is externally supplied with pure water by a water feed pump (18).

In addition, the temperature of the heating medium is increased by the heating medium heating furnace (19) installed between the reactor (1) and the superheater (in the heating medium circulation path (A)) and the heater (20) installed in the heating medium storage tank (8). ) Start from K.

The means and process of heating the heating medium described above will be explained based on FIGS. 3 to 7. As shown in FIG. 3, the heating medium circulation path (A
), an appropriate bypass is provided in the first circulation system (a
), heat medium storage +1 (8) to heat medium temperature regulator (10),
The second circulation system (b) returns from the heat medium storage 4 (8) through the heat medium heating furnace (19), and from the heat medium storage 4 (8) to the heat medium temperature regulator (
10), the third circulation system (C
), and the path (B) from the supply of raw materials to the outflow of city gas includes an ethanol/water mixture in the middle of the pipe leading from the reaction gas separation tank (5) to the carbon dioxide absorption tower (12). A bypass (22) equipped with a startup blower (21) is provided to connect the upstream side of the preheater (2) in the pipeline for supplying raw materials, and connect the startup blower (21) to the preheater (2) and the evaporator (3). ), superheater (4), reactor (
1), preheater (2), reboiler (6), reaction gas separation [(
5) to form a fourth circulation system (d) returning to the startup blower (21)K.

First, the heating medium in the heating medium storage (8) is heated by the heater (20), and the pump (9) is operated to circulate and flow the heating medium into the first circulation system (a). Heat medium temperature to 170°C
(Figure 4).

Subsequently, the flow of the heating medium is switched to the second circulation system (b), and fuel is supplied to the heating medium heating furnace (19) and heated by combustion.
The heating medium temperature is raised to about 250°C (Fig. 5).

Next, the flow of the heat medium is switched to the third circulation system (c) (sixth
figure).

After that, the startup blower (21) K Yoshi No. 4
Nitrogen (N2) is fed into the circulation system (d) and circulated.

Then, nitrogen (N2) flowing through the fourth circulation system (d)
The evaporator (3) and superheater (4) recover the heat from the heat medium and raise the heat medium temperature to about 250°C, and then heat the reactor (1) to create the activation temperature. Figure 7).

``And when the above reaction conditions are set, the flow of the heating medium is switched to the regular heating medium circulation path (A), and the raw material, which is methanol and feed water, is fed into the reactor (1).

Once reaction heat is generated from this K, water is separated from the reaction gas (methane-containing mixed gas). From then on, this reaction heat and separated water are used to supply feed water and heat the heating furnace (1
Steady rotation is performed by stopping the supply of fuel to 9).

(Example) Regarding the method for producing high-calorie city gas as a raw material for methanol according to the present invention, high-calorie city gas is produced in the process 70- shown in FIG.
An example of actual production based on the following is shown below.

Example 1 Water and methanol as raw materials, molar ratio 05, reaction temperature 305°C, reaction pressure 9.0kg/c in the reactor 16
When operated under rIIG conditions, a manufactured gas having the following properties was obtained.

Calorific value 11.000 Kcal/NmJ Specific gravity 0
．． 68 WI (Wotsube Index) 13340 CP (Burning Rate) 41.9 crn/S Table 1 shows various numerical values for each stream number in the flowchart shown in FIG. 2 in this example.

Example 2 The raw materials water and methanol were mixed in a molar ratio of 0, s, and the reaction temperature was 299°C and the reaction pressure was 8.9% in the reactor 16.
When operated under the condition of /c+dG, a manufactured gas having the following properties was obtained.

Heat generation 1 11,000 Kcal/NJ specific gravity 0.68 WI (Wotsube Index) 13340cp (burning rate) 41.6 @/s Note that the various numerical values for each stream number in the flowchart shown in Figure 2 in this experimental example are It is shown in Table 2.

(effect) The present invention has the above configuration and has the following advantages.

(1) Methanol is dimethane-formed by a gas phase catalytic reaction in the presence of a catalyst in a reactor,
A methane-containing mixed gas with a high methane yield can be obtained in this step.

(2) The entire amount of water separated from the methane-containing gas mixture can be used to mix methanol with water.

(3) The entire amount can be used for heating the methanol/water mixed raw material by recovering the reaction heat in the reactor and the heat of the methane-containing mixed gas coming out of the reactor.

(4) Therefore, according to (2) and (3) above, with only continuous supply of methanol, the heating energy, V! A methane-containing mixed gas can be constantly obtained without any supply of L feed water, and the economic effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a process flow schematically showing an example of the process of implementing the present invention, and FIG. 2 is a flowchart showing an embodiment of the present invention. Indicates the measurement position of the specifications. FIGS. 3 to 7 are explanatory diagrams illustrating the process of starting the door. Patent applicant: Seibu Gas Corporation Patent applicant: Mitsubishi Yuka Engineering Co., Ltd. f
Go to 1

Claims (1)

[Claims] After a mixture of methanol and water is heated to the required temperature by heat exchange with a heat medium, it is heated to about 300°C via a catalyst made of a nickel-based carrier supported on an alumina-based carrier with a reduced content of sulfur compounds and a reduced specific surface area. A methane-containing gas is directly generated by the reaction under the following low-temperature reaction conditions, and after water is separated from the methane-containing gas, high calorific city gas is produced through the steps of carbon dioxide removal, dehydration, and heating by adding butane. The water that is constantly produced and mixed with the methanol and the heat for heating the heating medium are supplied from outside at the time of start-up. A method for producing high calorific city gas as a methanol raw material, characterized in that the heat of reaction generated during gas generation is used.