JPS5815006A - Enhancing method for hydrogen recovering rate in production of hydrogen from converter waste gas - Google Patents

Abstract

PURPOSE:To enhance the recovering rate of gaseous H2 by removing gaseous O2 from waste gas before or during separating hydrogen. CONSTITUTION:Waste gas from a converter 1 is fed to a CO converting apparatus 5 through a dust collector 3 and a gas holder 4 and reacted with steam from a steam generator 6 to generate a gaseous mixture by CO conversion. The gaseous mixture is introduced into a CO2 separator 7 and an H2 separator 9 to separate CO2 and H2, respectively. At this time, prior to the introduction the gaseous mixture is passed through an O2 removing apparatus 12 provided with a palladium catalyst bed for removing O2. O2 in the gaseous mixture is thoroughly removed, and the recovering rate of gaseous H2 is enhanced.

Description

[Detailed Description of the Invention] The present invention is an improvement of a method for producing hydrogen from converter exhaust gas.
In detail, this is a method for improving hydrogen recovery efficiency in a hydrogen production method, which involves adding water and S gas to converter exhaust gas to perform CO conversion (water gas reaction), and separating and recovering water volume from the generated gas using an adsorbent. Regarding.

Converter exhaust gas discharged from steelmaking converters such as pure** top-blown converters generally contains carbon monoxide (CO) and carbon dioxide (c
o, ), nitrogen (N, ) and hydrogen (H3) in proportions of approximately 70%, 10%, 17% and 8% by volume, respectively. Therefore, instead of adding water vapor to this exhaust gas to perform CO conversion, it is better to generate carbon dioxide and hydrogen, separate and recover the carbon dioxide and hydrogen separately from this generated gas, and use each as appropriate. 1 Normally, the product gas after CO conversion is first sent to a carbon dioxide separator 1 to recover carbon dioxide, then sent to a hydrogen separator and treated with an adsorbent such as zeolite by suitable means. Collect hydrogen.

For a while after the start of blowing, the composition of converter exhaust gas fluctuates dramatically due to unreacted oxygen being discharged, but after that the composition becomes relatively stable. When converter exhaust gas is used as raw material gas for hydrogen production as described above, conventionally, in order to avoid fluctuations in the composition of the raw material gas, recovery of the converter exhaust gas was not performed while the composition of the converter exhaust gas was unstable after the start of blowing. Instead, only the converter exhaust gas was used after the composition reached a stable state.

However, with the background of the era of energy crisis, the recovery rate of converter exhaust gas has inevitably increased, and it has become necessary to use converter exhaust gas whose composition is unstable after blowing. It is becoming. To prevent this, the converter exhaust gas is temporarily [i' on average α16 to α8vo1%1i! The temperature has become so high that more oxygen is mixed in.

By the way, when separating and recovering hydrogen from the produced gas after CO conversion using an adsorbent, the efficiency of hydrogen recovery by the adsorbent (i.e., the ratio of the separated and recovered hydrogen to the hydrogen supplied to the adsorption column) (in other words, the ratio of the amount of hydrogen at the outlet to the amount of hydrogen at the inlet of the adsorption tower) h is inhibited by the presence of oxygen in the gas supplied to the adsorption tower, and the oxygen concentration increases. If the hydrogen recovery efficiency is found to decrease rapidly, it is necessary to take a longer time to separate the hydrogen in the adsorption column, use a larger amount of adsorbent, or increase the amount of adsorbent. It is necessary to take measures such as shortening the usage time until regeneration and relatively increasing the purge time of the adsorption tower, which will lead to deterioration of the productivity of the hydrogen production method in any case.

Therefore, an object of the present invention is to overcome the deterioration in performance of an adsorption tower due to the presence of oxygen in the adsorption tower feed gas in hydrogen production from converter exhaust gas as described above.

Herein, 1. The present invention increases the hydrogen concentration by adding steam to the converter exhaust gas to cause a water gas reaction, and the hydrogen in the generated gas is separated and recovered by using an adsorbent. In a method for producing hydrogen from converter exhaust gas, the hydrogen recovery efficiency during hydrogen separation and recovery is improved by removing oxygen from the gas prior to hydrogen separation or during hydrogen separation. The gist of this paper is a method for improving hydrogen recovery rate in hydrogen production from converter exhaust gas, which is characterized by:

Conventionally, when producing carbon dioxide and hydrogen from converter exhaust gas by CO conversion, no consideration was given to the presence of oxygen at all. The present invention was achieved by focusing on the presence of a very small amount of oxygen in converter exhaust gas and discovering that this oxygen has a significant effect on the recovery efficiency in hydrogen separation and recovery using an adsorbent. By removing substantially K (i.e., to the order of a few ppm) of oxygen from the adsorption tower feed gas (by the invention), the hydrogen recovery efficiency is 6.5% compared to the conventional method.
It improves by about 16%, greatly contributing to improving productivity.

Oxygen can be removed from the gas supplied to the adsorption tower by, for example, installing a catalyst tank made of cypress wood or the like at any suitable position in the gas path between the gas outlet of the converter and the inlet of the adsorption tower. It is possible to react with K. Any suitable oxygen removal method known in the art can also be employed.

As mentioned above, instead of removing oxygen from the gas supplied to the adsorption tower before it is introduced into the adsorption tower, an adsorbent with a good ability to separate hydrogen and oxygen ( For example, by using a synthetic zeolite with good H*Os separation (K), it is also possible to trap oxygen in the adsorbent and remove it.

Even if oxygen is removed during the separation and recovery of hydrogen by adsorption in this manner, the hydrogen recovery efficiency can be improved almost in the same way as when oxygen is removed from the gas supplied to the adsorption tower in advance.

Therefore, the present invention makes it possible to circulate and reuse the recovered CO1 by combining it with a converter steelmaking method that also uses CO1 bottom blowing as shown in the specific example described later. 4.Excellent effects that greatly contribute to improving the efficiency and reducing costs of the steelmaking process umbrella are exhibited.

The method of the invention will be further explained in detail in conjunction with the accompanying drawings.

Figure 1 is an example of a flow sheet when the method of the present invention is incorporated into the exhaust gas treatment of a carbon dioxide gas bottom-blown converter. The converter exhaust gas discharged from the converter l in which carbon dioxide gas (carbon dioxide 'a) is bottom-blown from the nozzle 1-b passes through the hood 2, the dust collector 8, and the converter exhaust gas holder 4. It is temporarily stored and sent to the CO conversion device 5 after death.

Steam is supplied to the CO converter 5 from a steam generator 166, and carbon monoxide in the converter exhaust gas reacts with steam in the presence of an appropriate catalyst according to the reaction formula: CO+H*0-+COt+quickly. and produces carbon dioxide and hydrogen.

The resulting gas containing carbon dioxide and hydrogen is then sent to a removal device 12, which in the illustrated embodiment consists of a catalyst tank equipped with, for example, a palladium catalyst, located near the outlet of the CO conversion device 6. Oxygen is removed by reaction with hydrogen. The oxygen-free gas is then sent to a separation unit 7, where the Cow is separated, possibly by suitable means such as absorption by the MKA (monoethanolamine) method or the potassium carbonate method. The separated COl passes through the CO gas holder 8 and is reused as bottom-blown gas to the converter l. The hydrogen-rich gas leaving the separator 7 is sent to the H2 separator (for example, an adsorption tower equipped with synthetic zeolite) 9, where a 999% high purity water volume, for example, is separated and recovered. This hydrogen Fi H* gas holder 10 KjF is used for home use or sold externally as appropriate. The off-gas from the H1 separator 9 is immediately or temporarily transferred to the off-gas holder 11Cl? It is used as fuel after being charged.

In the illustrated process, the snow removal device 18 is preferably located near the downstream outlet of the KCOR converter as shown. That is, since the temperature change of sR, which is made up of the catalyst tank such as a palladium paddle that is the O8 removal device 12, is required to function, it is preferable to place it on the downstream side of the CO2 separation device 7 by absorption. Further, since components such as Has, which act as catalyst poison for the oxygen removal catalyst, are removed by the CO converter 6, the lower R91 is better than the CO2 converter 6.

Next, the present invention will be further explained with reference to Examples.

Example Converter exhaust gas was treated as a raw material gas by the process shown in FIG. 1 to produce hydrogen. The gas flowing out from the CO conversion device 6 at a temperature of approximately 280°C is passed through the gas removal device 12G'C, which consists of a palladium catalyst tank for bag removal, installed near the outlet of this device, and is heated to substantially remove oxygen. After completely removing CO1, it passes through CO1 separator 7 to 1 synthetic zeolite 5All
The flow rate of the raw material gas discharged from the converter was 650 NWI/hr, and the CO,
The feed gas leaving the separator and being fed to the adsorption tower is approximately 461
It contained hydrogen in an amount of 11&l//hrO, and its oxygen content was several P P ''e, or essentially 0%.

For rounding the comparison, the above feed gas pressure α1 supplied to the adsorption tower in %
It was mixed with 6% and 08% oxygen and passed through the adsorption column under the same conditions. This experiment reproduced the operating conditions of a conventional method without oxygen removal.

The experimental conditions and results are summarized in the following table K. Six experimental results were obtained, i.e., O ml in the adsorption tower feed gas.
The relationship between f:, H, and recovery efficiency is shown in a graph in FIG.

(Gas amount O unit: tNdAr) From the above results and FIG. 2, it will be clear that the present invention has a significant effect on Ha recovery efficiency.In both of the above experiments, the product H discharged from the adsorption tower.

The purity of the gas was over 911999%.

[Brief explanation of the drawing]

Fig. 1 is a flow sheet showing one embodiment of the method of the present invention, and Fig. 2 shows the O1 concentration in the adsorption tower feed gas and the H2 concentration in the adsorption tower.
It is a graph showing the relationship with collection efficiency. 1...Transfer F%1-1...Lance, 1-b...Nozzle, ~...7-de, 8...Dust collector, 4...Gas holder,... CO conversion device, 6...Steam generator, 7...001 minute M device, 2...COl gas holder, 9...Shi separation device, 10...H, gas holder, 11...Off gas Holder, 12-0. removal device. Patent Applicant: Sumitomo Metal Industries, Ltd. Kyodo Sanso Co., Ltd., Patent Attorney Akira Hirose - Figure 1, 2 No. 114 Loss #Cass 02 Ji Ji (%)

Claims (1)

[Claims] From the converter exhaust gas, the hydrogen concentration is increased (by adding water vapor to the converter exhaust gas to cause a water gas reaction), and the hydrogen in the generated gas is separated and recovered (by using an adsorbent). In the hydrogen production method, the important thing is to remove oxygen from the gas during hydrogen separation (prior to the hydrogen content), and to improve the hydrogen recovery efficiency during hydrogen separation and recovery. A method for improving hydrogen recovery rate in hydrogen production from converter exhaust gas, characterized by: