JPH04357101A - Production of hydrogen gas from coke furnace gas - Google Patents

Abstract

PURPOSE:To remarkably enhance the recovery ratio of hydrogen gas when hydrogen gas is recovered from a coke furnace gas by a PSA method. CONSTITUTION:In a method for separating hydrogen gas from a coke furnace gas 1 by a PSA method, off gas 5 adsorbed and separated in an adsorption and separation process 3 of the PSA method is subjected to a reforming treatment in steam reforming process 6, and then mixed with a purified coke furnace gas and the mixed gas is again introduced into the adsorption and separation process 3 to recover hydrogen gas. The method can recover hydrogen gas 1.3 to 3 times the amount from coke furnace gas, compared with a conventional method, and recovery ratio thereof is remarkably improved. Therefore, the objective method is economically advantageous.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for economically producing hydrogen gas from coke oven gas (hereinafter referred to as COG).

0002

BACKGROUND OF THE INVENTION COG contains 50 to 60 vol% hydrogen and 20 to 30 vol% CH4. C
Pressure is a method for recovering hydrogen in OG.
Swing adsorption method (hereinafter referred to as PSA method), cryogenic separation method, etc. have been practiced, but recently the PSA method, which is easy to operate and economically advantageous, has become mainstream. In the production of hydrogen from COG using this PSA method, COG is usually first washed with water and/or oil to remove heavy hydrocarbons such as coal tar and naphthalene, then desulfurized and decyanized, and then desulfurized. After ammonia treatment and the final removal of crude light oil, refined COG
is passed through an adsorbent such as a molecular sieve under pressure to separate it into low-molecular hydrogen, which is not adsorbed by the adsorbent, and macromolecular gases, such as hydrocarbon gases, CO2, and CO, which are adsorbed by the adsorbent. It is carried out by Hydrocarbon gas, CO2, CO, and other polymer gases adsorbed by this adsorbent are desorbed under reduced pressure after the adsorption is completed and are discharged as off-gas. In this case, hydrogen gas can be continuously produced by providing a plurality of adsorption devices and alternately adsorbing and desorbing the polymer gas.

[0003] In hydrogen production from COG using the above-mentioned PSA method, hydrocarbon gas and C
Hydrogen gas is contained in addition to O2 and CO, which causes a decrease in yield. As a method for improving the amount of hydrogen gas recovered from COG using the PSA method, for example, after desulfurizing and deoxidizing COG, S/C=
700~ in the presence of steam in an amount of 3.0~3.5
Steam reforming is carried out at 800℃, and then CO in the reformed gas is converted to C.
Method of converting to O2 and further decarbonizing
94705), after subjecting the COG to pre-treatments such as desulfurization, deoxidation, and water washing, a portion of the COG is subjected to steam reforming treatment and CO conversion treatment, and then hydrogen is recovered by the PSA method, and the remainder of the COG is A method for obtaining synthetic natural gas by methanating and refining natural gas (Japanese Unexamined Patent Publication No. 153102/1982) has been proposed.

0004

[Problems to be Solved by the Invention] JP-A-58-194705 and JP-A-62-153102 disclose the method of steam reforming the COG to convert CH4 in the COG to H2, and then separating and recovering hydrogen gas using the PSA method. The method of the publication is
In both cases, hydrocarbon gas and CO2 are contained in the desorbed off-gas.
In addition to CO, hydrogen gas is contained at a considerable concentration, which causes a decrease in yield.

[0005] The purpose of this invention is to perform steam reforming on the desorbed and discharged off-gas when recovering hydrogen gas in COG by the PSA method, convert CH4 to H2, mix it with COG, and process it again by the PSA method. The object of the present invention is to provide a method that can significantly improve the yield of hydrogen gas.

[0006]

[Means for solving the problem] That is, this invention
In the method of separating hydrogen gas from OG by the PSA method, the off-gas separated by the PSA method is subjected to steam reforming treatment, and then mixed with raw material COG and hydrogen gas is recovered again by the PSA method.

[0007]

[Operation] In this invention, after the off-gas separated by the PSA method is subjected to steam reforming treatment, it is mixed with the raw material COG and hydrogen gas is recovered again by the PSA method.
Prior to hydrogen separation using the SA method, it is possible to recover the hydrogen gas that was discharged into the off-gas when COG is steam reformed, and the recovery rate of hydrogen gas can be significantly increased.

The details of this invention will be explained based on FIG. Figure 1 shows a schematic system diagram of the method of this invention.
In step 1, as in the conventional method, heavy hydrocarbons, hydrogen sulfide, hydrogen cyanide, ammonia, and crude light oil are removed in pretreatment step 2, and then the purified COG is introduced at high pressure into adsorption separation step 3 using the PSA method. , hydrogen 4 not adsorbed by the adsorbent is separated. On the other hand, part of the polymer gases such as CH4, CO, CO2, etc. and unseparated hydrogen adsorbed by the adsorbent in the adsorption separation step 3 are removed as an off-gas by desorption under reduced pressure.
It is discharged as. This off-gas 5 is transferred to a steam reforming process 6.
After converting CH4 in the off-gas 5 to H2, it is mixed with COG1 and introduced into the adsorption separation step 3 of the PSA method to separate hydrogen gas.

[0009]

【Example】

Example 1 COG1 having the composition shown in Table 1 was introduced into pretreatment step 2 at 1000 Nm3/Hr to remove heavy hydrocarbons, hydrogen sulfide, hydrogen cyanide, ammonia, and crude light oil, and purified COG
G and none, 35 vol% hydrogen from steam reforming step 6,
Reformed gas containing CH42vol% 3300Nm3/Hr
5 kg/c for adsorption separation step 3 using the PSA method.
The hydrogen gas 4 not adsorbed by the adsorbent was recovered at 1240 Nm3/Hr. A part of the polymer gas and unseparated hydrogen adsorbed in the adsorption/separation step 3 is depressurized to atmospheric pressure and desorbed as off-gas 5.
Separated at 60Nm3/Hr. This off-gas 5 contained 16 vol% hydrogen and 12 vol% CH4. Of this off gas 5, 2660 Nm3/Hr is introduced into the steam reforming step 6, and the remaining 40 Nm3/Hr of the off gas 5 is introduced into the steam reforming step 6.
0Nm3/Hr was discharged through pipe 7.

0010

[Table 1]

Off-gas 5 introduced into the steam reforming step 6
2660Nm3/Hr in the presence of a catalyst at an inlet temperature of 4
Reforming was carried out in the presence of steam under the conditions of 00°C, reactor internal pressure of 10 kg/cm2·G, and outlet temperature of 800°C. As a result, 3300 Nm3/Hr of reformed gas containing 35 vol% hydrogen and 2 vol% CH was obtained. This reformed gas 33
00Nm3/Hr is purified COG1000Nm3/Hr
and then introduced into the adsorption separation step 3 of the PSA method again.

Comparative Example 1 Pretreatment step 12 of the conventional hydrogen gas recovery step shown in FIG.
COG11 shown in Table 1 of Example 1 was added to 1000Nm3/
The heavy hydrocarbons, hydrogen sulfide, hydrogen cyanide, ammonia, and crude light oil are removed to produce purified COG, and 5 kg/cm2・G is added to the adsorption separation step 13 of the PSA method.
400Nm of hydrogen gas that is not adsorbed by the adsorbent.
Collected at 3/Hr. A part of the polymer gas and unseparated hydrogen adsorbed in the adsorption/separation step 3 is depressurized to atmospheric pressure and desorbed to form an off-gas 6 of 600 Nm3/H.
separated by r. This off-gas contains 25 vol of hydrogen.
%, CH450vol% was contained.

Comparative Example 2 COG21 having the composition shown in Table 1 of Example 1 was introduced at 1000 Nm3/Hr into the pretreatment step 22 of the hydrogen gas recovery step of the conventional hydrogen increasing method by steam reforming shown in FIG. Heavy hydrocarbons, hydrogen sulfide, hydrogen cyanide, ammonia, and crude light oil are removed to produce refined COG, which is then introduced into a steam reforming step 27 in the presence of a catalyst at an inlet temperature of 400
°C, reactor internal pressure 10 kg/cm2・G, outlet temperature 80
Reforming was carried out at 0°C in the presence of water vapor. As a result, 1 of the reformed gas contained 74 vol% hydrogen and 3 vol% CH4.
720 Nm3/Hr was obtained. This was introduced into the adsorption separation step 23 of the PSA method at a rate of 5 kg/cm2·G, and hydrogen gas not adsorbed by the adsorbent was recovered at a rate of 930 Nm3/Hr. A portion of the polymer gas and unseparated hydrogen adsorbed in adsorption/separation step 3 was separated at 790 Nm3/Hr as off-gas 25 by being desorbed by reducing the pressure to atmospheric pressure. This off-gas contains 43 vol% hydrogen, CH47 vol%
It contained 1%.

[0014]

[Effects of the Invention] As described above, according to the method of this invention, from the same amount of COG, compared to the conventional PSA method,
In addition, it is possible to recover 1.3 times as much hydrogen gas as with the method of steam reforming COG and then introducing it into the PSA method, and the recovery rate in hydrogen gas production from COG can be greatly improved. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the method of the present invention.

FIG. 2 is a schematic systematic diagram of a conventional method in Comparative Example 1.

FIG. 3 is a schematic systematic diagram of a conventional method in Comparative Example 2.

[Explanation of symbols]

1, 11, 21 COG 2, 12, 22 Pretreatment process 3, 13, 23 Adsorption separation process 4, 14, 24 Hydrogen gas 5, 15, 25 Off gas 6, 26 Steam reforming process 7 Piping

Claims (1)

[Claims] [Claim 1] In a method for separating hydrogen gas from coke oven gas by a pressure swing adsorption method, the off-gas separated by the pressure swing adsorption method is subjected to steam reforming treatment, and then mixed with raw coke oven gas. A method for producing hydrogen gas from coke oven gas, characterized in that hydrogen gas is recovered again by a pressure swing adsorption method.