JPS58217591A - Preparation of methane-rich gas utilizing byproduct gas - Google Patents

Abstract

PURPOSE:To inexpensively obtain a high-calorie methane-rich gas, in preparing the methane-rich gas by reacting CO and H2 in a coal gas, by adding the byproduct exhaust gas containing high-concn. CO from a metal refining furnace as a carbon source. CONSTITUTION:After a coke oven gas 1 is introduced into a pretreating process 3 to remove the tar component therein, a proper amount of a byproduct exhaust gas 2 containing high-concn. CO from a metal refining furnace is added to said tar-free gas as a carbon source. The mixed stock gas 1 is introduced into a primary desulfurizing vessel 4 to desulfurize inorg. sulfur such as H2S and, after the treated gas is heated by a heater 5, org. sulfur such as COS in the gas is desulfurized in a secondary desulfurizing vessel 6 while finish desulfurization is further carried out in a third desulfurizing vessel 7. The desulfurized gas is pressurized to 1-50atm by a compressor 8 and introduced into a methane converter 9 filled with an Ni-Al2O catalyst, where CO and H2 in the mixed stock gas are reacted to obtain an objective methane-rich gas 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high-calorie methane-rich gas from coal gas.

In recent years, demand for methane-rich gas as city gas or various synthetic raw material gases has been increasing.

In order to meet this demand, research has been progressing on processes for producing alternative natural gas (sNG) from hydrocarbon fuels such as coal and liquefied petroleum gas.

On the other hand, the generation of coke oven gas (COG) has increased due to increased production of coke based on all-coke operation of blast furnaces in steel plants, and the use of this surplus COG is currently being considered.

Therefore, a method of producing methane-rich gas from coal gas such as COG, that is, gas obtained by carbonizing coal gas, has been studied, and in the presence of a nickel-based catalyst, methane-rich gas is produced at a temperature of 250 to 250 ml.
A method of converting 500'C1 into carbon monoxide (Co)f, (methane, (OH)) by carrying out a reaction at a pressure of 1 to 50 atmospheres has been attempted.In general, the H2/CO molar ratio in coal gas is almost is 3 or more, indicating an excess of hydrogen (H2).The H2/CO molar ratio suitable for methane synthesis is ideally 3, as can be seen from equation (1).

CO+3H--→CH4+ H2O (1) Furthermore, CO
In the case of G, when performing methane/yon alone, methane content before calorie amplifier is 28.6%, 4640 kca
l/N m", after increasing the calories, it becomes about 5'700 kcal/N r with 45% methane content.
It was only about n3, and there was a demand for an even higher calorie amplifier.

Therefore, in order to convert this excess H2f into methane, it is necessary to add a carbon source from outside.

Conventionally, naphtha, liquefied petroleum gas, etc. have been added as carbon sources, but in this case, a steam reforming process or partial oxidation process is required to decompose hydrocarbons into carbon monoxide before the methane conversion process. Therefore, it could not necessarily be said to be a preferable method.

As part of the diversification of raw materials, the inventor of the present invention searched for various sources of carbon added from the outside, and discovered that metal smelting, which had traditionally been mixed with other gases and had little use other than as a self-consumption fuel for heating furnaces and boilers, etc. By employing high-concentration carbon oxide-containing exhaust gas that is produced in large amounts as a by-product in furnaces, such as converter exhaust gas for steel manufacturing and electric furnace exhaust gas for ferroalloy production, it is possible to improve steam reforming processes and parts such as naphtha and liquefied petroleum gas. It has been found that the process does not require complicated treatment steps such as oxidation steps, and can be used as a carbon source as is, resulting in an extremely economical process.

Furthermore, for example, when methanation is performed on steelmaking converter exhaust gas (LD()) alone, the methane content before calorie increase is 0%, 2180 kca], /N m3
However, after the calorie increase, the methane content is only 1.4%, about 2376 kcal/Nm.
By using COG and LDG together, the notano content becomes approximately 80%, approximately 500 kcal/Nm",
Compared to the case of methanation alone, dogs 11
discovered that it was possible to obtain a methane-containing cabinet and calorific value,
This has led to the present invention.

That is, the present invention produces a methane-rich gas by reacting CO and I(2) in coal gas. This is a method for producing methane-rich gas characterized by the following.

For example, coal gas or CO-containing exhaust gas produced as a by-product in a metal smelting furnace is shown in Table 1 (a preferred example of its composition is shown).

An example of Table 1 (volume O; also, a schematic explanatory diagram of a preferred process) is shown in Fig. 1. In Fig. 1, to explain an example when COG and LDG i are used, COO is initially The material is stored in a raw material gas holder 1, and then led to a pretreatment process 3v, where substances such as BTX, naphthalene, and tar that cause trouble in the subsequent process are removed.

LDG, which is an additive gas, is stored in an additive gas holder 2, and is added in an appropriate amount to the COO that has exited the pretreatment device 3. LDG usually requires no particular pretreatment. The mixed raw material gas enters a desulfurizer, where sulfur compounds that cause poisoning of the methanone iono catalyst are removed to 1 ppm or less. First, in the primary desulfurizer 4, inorganic sulfur such as H2S is desulfurized using an Fe203-based adsorbent. Heater 5 raises the temperature to about 250'C~5i) 0°C, and then the secondary desulfurizer 6
Organic sulfur such as CO8 and C82 is desulfurized using a Fe2O3-based adsorbent.

Next, a second desulfurization is performed in a tertiary desulfurizer 7 using a ZnO-based adsorbent. Then, the pressure is increased to 1 to 50 atmospheres by a pressure booster 8 and the mixed gas is introduced to a methane converter 9. The methane converter 9 is filled with NIA Q203 type catalyst, and 2
50-500'C 11-50 atmospheres - Co., H
2 reacts, and methanation of the mixed gas occurs.

In the methane converter 9, temperature rise due to reaction heat of methane conversion is alleviated as necessary. The gas exiting the methane converter 9 is cooled by a cooler 1o and stored in a product gas holder 11.

The present invention will be further explained below with reference to Examples.

EXAMPLE Using the process shown in Figure 1 and under the conditions described above, LDG was added to COO/Metai 7 was made using the raw material scraps.
Yo: I went to /. The compositions and calorific values i- of COG and LDQ used are shown in Table 2.

coo and LDG were used for JJDG17 cutting on C0G100. This ratio makes the raw material molar ratio of H2/co approximately 3.

Composition and calorific value f of the obtained product gas: Shown in the second column. As a result, significant improvements in methane content and calorific value were achieved. In addition, in the Habodo Operation Note, COG and L
DC) The methane content and calorific value when each i is methane 7 yo/Nrn3 and 23' respectively, as mentioned above, is approximately 5'i'00 kcal/Nrn3 and 23'
Since it was i'6 kcal/N m3, if both gases were mixed and used together with the raw material, a higher force than expected was achieved. In addition, the method of the present invention not only simplifies the equipment compared to the method of adding naphtha or liquefied additive gas, but also eliminates the high concentration of monoxide produced as a by-product in metal smelting furnaces, which has not been effectively utilized in the past. It provides a method for effectively utilizing all carbon-containing exhaust gas, and has extremely high industrial value.

[Brief explanation of drawings]

FIG. 1 is an example of a schematic illustration of a preferred process for carrying out the method of the present invention. ■・ Raw material gas boulder-12-Additional gas holder, 3
Pretreatment device, 4. Primary desulfurizer, 5, heater, 6
Secondary desulfurizer, '/ ・Tertiary desulfurizer, 8... Booster,...
...-Meta 7 converter, 1--Cooler, Jl product gas holder. Agent Patent Attorney Masao Inoue

Claims (1)

[Claims] 1. When producing methane-rich gas by reacting carbon monoxide and hydrogen in coal gas, it is recommended to add high-concentration carbon oxide-containing exhaust gas, which is a by-product of metal smelting furnaces, to coal gas as a carbon source. Characteristic method for producing methane-rich gas.