JPS62153102A - Production of hydrogen gas using coke oven gas as raw material - Google Patents

Abstract

PURPOSE:To reduce reproduction cost of hydrogen and synthetic natural gas, by pretreating coke oven gas, subjecting a part of the pretreated gas to steam reforming process and CO conversion process, recovering produced hydrogen and methanating the remaining part of the gas. CONSTITUTION:Coke oven gas COG is sent to a pretreatment stage 5 via a compression stage 3 and subjected to various prescribed treatments. A part of the pretreated gas is successively transferred to a steam reforming stage 11, a CO-conversion stage 13 and a separation stage 15, in which hydrogen is separated and recovered by a pressure swing adsorption method. The produced off gas is used as a fuel for the steam reforming stage 11. Parallel to the above procedure, the remaining part of the gas transferred from the pretreatment stage 5 is sent to a methanation stage 7 and then to a purification stage 9 to obtain a synthetic natural gas SNG, etc. The operation cost for the production of hydrogen gas can be reduced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing hydrogen using coke oven gas (hereinafter referred to as COG) as a raw material.

Techniques and Problems Conventionally, pressure swing atsorption methods (hereinafter referred to as PSA methods), cryogenic separation methods, and the like have been used to obtain hydrogen from COG containing about 150 to 60 vol% hydrogen. For example, in the PSA method, COG is usually first washed with water and/or oil to remove heavy hydrocarbons such as tar, then desulfurized, and then the purified COG is passed through molecular sieves under pressure. Low-molecular hydrogen that is not adsorbed by the adsorbent and high-molecular hydrocarbon gas and CO that are adsorbed to it pass through the adsorbent.
2, CO, etc. are being separated. In this case, hydrogen gas can be continuously produced by providing a plurality of adsorption devices and alternately adsorbing and desorbing the polymer gas.

However, in this method, the function of the adsorbent is easily inhibited by impurities in COG, so it is necessary to remove virtually all of tar, penzole, naphthalene, etc., and it requires large-scale pretreatment. (Desulfurization, heavy hydrocarbon removal, cleaning, etc.) Sei! ! There are drawbacks such as the need for A equipment and the need for a deoxidizing process as a post-treatment. Similar problems exist with cryogenic separation methods. Furthermore, in the PSA method, no method has been found for effectively utilizing off-gas generated in large quantities.

Means for Solving Problem 1 The inventor of the present invention has repeatedly considered various problems in view of the problems of the hydrogen production method using COG as a raw material as described above, and as a result, has produced synthetic natural gas (hereinafter referred to as SNG) from COG. The pretreatment for this process is almost the same as the pretreatment that is performed prior to the PSA method, and the off-gas from the PSA method can be used as a heat source for the high temperature reforming of COG that is performed prior to the PSA method. After further research, we finally completed the present invention. That is, the present invention provides (i) after subjecting coke oven gas to pretreatment such as desulfurization, deoxidation, and water washing;
11) Part of the coke oven gas is subjected to steam reforming treatment and C
The coke oven gas is obtained by subjecting it to O conversion treatment, then recovering hydrogen by a pressure swing atsorption method, and (iii) methanating and refining the remainder of the coke oven gas to obtain synthetic natural gas. The present invention relates to a method for producing hydrogen gas.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

In FIG. 1, COG is sent from a COG tank (1) to a compression step (3) according to a conventional method, and then sent under pressure to a pretreatment step (5).

The pressure of COG used in the pretreatment process is 5 to 50 kcl.
/cffl·G. The pretreatment process includes removal of naphthalene, removal of penzole, removal of cyanogen, removal of ammonia, removal of tar mist, desulfurization, removal of oxygen, removal of dienes, etc., but since these are all well-known means, no detailed explanation will be given. .

A part of the high-temperature COG that has exited the pretreatment step (5) (hereinafter referred to as "a part of COG" or "COG
The remainder '' does not mean quantitatively large or small) is sent to the methanation step (7).Methanation step (7)
For example, in the presence of a catalyst such as a platinum group metal catalyst or a Ni catalyst, S/C (number of oxygen atoms in water vapor per carbon atom 11I in a hydrocarbon) is 0. Adding water vapor in an amount of about 5 to 1.0 to the mixture,
If necessary, a carbon source such as naphtha or LPG may be further added. The reactor inlet temperature for the methanation process is 2
Approximately 50-300'C, pressure inside the reactor is 5-10K (1
/rmG, and the reactor outlet temperature is preferably about 300 to 550'C. The calorific value of the generated gas after the methanation reaction varies depending on the mixing ratio of LPG, etc., methanation reaction conditions, etc., but the initial calorific value of COG is 5000 to 5300.
7000-8000Kcal compared to Kcal/Nm3
/Nm3. After passing through the generation step (9) as necessary, the generated gas may be used as it is or as required.
After being heated by PG, it is used as SNG.

On the other hand, the remainder of the high temperature COG from the pretreatment step (5) is
In the steam reforming step (11), reforming is performed at high temperature in the presence of steam. Conditions during modification are not particularly limited, but
For example, it is carried out in the presence of a catalyst such as a normal Ni-based reforming catalyst or a noble metal-based catalyst, with water vapor added to the COG in an amount such that S/C is about 3.0 to 3.5. The reactor inlet temperature in the steam reforming step (11) is 400 to 450'
C, the pressure inside the reactor is 5 to 50'K (J/cm・G
The reactor outlet temperature is preferably about 700 to 800°C. Through this steam reforming, carbon hydrogen having two or more carbon atoms is decomposed into H2, CO1CO2 and CHt.

Next, in the CO transformation step (13), the CO in the reformed gas obtained above is converted to Fe, for example, in accordance with a conventional method.
It is converted into CO2 using a system catalyst.

The gas from the CO conversion step (13) is then sent to a separation step (15) using the PSA method, where it is separated into hydrogen that is not adsorbed by the adsorbent and Co, CO2, CHa, etc. that are adsorbed by the adsorbent. will be collected.

The off-gas released by desorption from the separation step (15), which is equipped with a plurality of adsorption devices and alternately performs adsorption and desorption, is sent to the steam reforming step (11) via a line (17), where it is used as heating fuel. It is effectively used as Note that if the heating energy in the steam reforming step (11) is insufficient due to only the combustion of off-gas, for example, COG may be sent from the COG tank (1) and used as part of the fuel.

Effect of the invention According to the present invention, the following effects are achieved.

(i>C during H2 production and SNI production using common equipment)
Since OG pretreatment can be performed, equipment costs are reduced and the manufacturing costs of H2 and SNG are reduced.

(ii> Since a large amount of off-gas generated in the separation process using the PSA method is effectively used as fuel for the COG steam reforming process, operating costs are significantly reduced.

<iii) The COG from the pre-treatment step is heated to a high temperature (25
(about 300° C.), it is possible to reduce heating fuel in the steam reforming process.

X-Dust-1 Examples and comparative examples will be shown below to further clarify the characteristics of the present invention.

Example 1 The present invention was carried out according to the flow shown in FIG.

The COG 185 ONm3/h pressurized to 10 kg/CIt-G in the compression step (3) is subjected to the pretreatment step (5)
De-tar mist, desulfurization, deoxidation,
Remove dienes, remove ammonia, remove cyanogen, remove penzole,
Various treatments for removing naphthalene were performed.

6 of the COGs at a temperature of 380°C from pretreatment step (5)
158 m3/h was sent to the steam reforming step (11), and steam reforming was performed in the presence of a noble metal catalyst and while supplying steam such that S/C=3.0 to 3.5. The inlet temperature of the reactor is about 400℃, the outlet temperature is about 800℃, the pressure inside the reactor is about 10kg/cd-G, and the C0G2158m3/
Heating was performed using h and an off-gas described below.

CO transformation process (13) of gas obtained by steam reforming
in the presence of a Fe-based catalyst to maintain a reactor outlet temperature of approximately 400°C.
Processed at °C.

The gas that has undergone CO conversion is separated by the PSA method (15
) to obtain 10,100 ON/h of hydrogen.

Off gas (1000Kca) generated in the separation process (15)
l/h) is the steam reforming process (
11) and used as fuel.

On the other hand, in parallel with the above hydrogen production, the CO00100ONm3/h from the pretreatment step (5) is sent to the methanation step (7), and in the presence of a platinum-based catalyst, the steam is converted to S/C=0.9. Methanation treatment was performed during the supply.Thus, 6808 m3/h of gas with a calorific value of 7300 KCal/Nm3
was gotten.

Comparative Example 1 COG pretreated in the same manner as in Example 1 was directly subjected to a separation process using the PSA method.

In this case, to obtain 10008 m3/h of hydrogen, C0G
Requires 28,608m3/h and off-gas 19,608m
3/h was generated. Since this off-gas does not contain hydrogen, it has poor combustibility and is of little use value, so it was released into the atmosphere after combustion.

[Brief explanation of drawings]

FIG. 1 is a flowchart outlining the invention. (1)...COG tank, (3)...compression step, (5)...pretreatment step, (7)...Methanation step, (9)...Refining process, (11)...steam reforming step, (13)...CO metamorphosis process, (15) Separation step by PSA method. (that's all)

Claims (1)

[Claims] [1] (i) After subjecting the coke oven gas to pretreatment such as desulfurization, deoxidation, and water washing, (ii) subjecting a portion of the coke oven gas to steam reforming treatment and CO conversion treatment. and then recovering hydrogen by a pressure swing adsorption method, and (iii) methanating and refining the remainder of the coke oven gas to obtain synthetic natural gas. A method for producing hydrogen gas. [2] The method according to claim 1, wherein the off-gas separated by the pressure swing adsorption method is used as a heat source material in steam reforming.