JPH09309703A - Apparatus for producing hydrogen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing hydrogen, having an extremely simple equipment constitution for preheating a raw material gas and generating and superheating, etc., of process steam at a low equipment cost and apply a slight load thereto in aspects of maintenance and control over the equipment and suitable for a small capacity. SOLUTION: This apparatus for producing hydrogen is capable of reforming a desulfurized raw material hydrocarbon at a high temperature with steam in a reforming furnace 2, converting carbon monoxide in the reformed gas comprising hydrogen, the carbon monoxide, gaseous carbon dioxide, methane, etc., into hydrogen in a CO conversion column 7, then treating the prepared conversion product with a hydrogen pressure swing adsorption(PSA) device 8 and producing the high-purity hydrogen. The raw material hydrocarbon is mixed with pure water for the steam and the resultant mixture is introduced into a raw material/steam heater 1 and heated by the heat exchange with a high-temperature combustion gas emerging from the reforming furnace 2 to provide a high-temperature mixture substance of the hydrocarbon with the steam. The obtained mixture is subsequently introduced into reactional tubes 3 of the reforming furnace 2 to carry out the high-temperature steam reforming reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen producing apparatus, and more particularly to a heating and vaporizing apparatus for a raw material hydrocarbon and process steam in a hydrogen producing apparatus by a steam reforming method.

[0002]

2. Description of the Related Art A hydrogen producing apparatus is very important because the hydrogen gas produced by the hydrogen producing apparatus is used as a reducing gas or a hydrogenated gas in many industrial fields such as the metal industry, the oil and fat industry, and the semiconductor industry. It is a device.

In particular, as natural gas has become widespread as a city gas in recent years, an on-site type small-capacity hydrogen production apparatus for producing hydrogen by a steam reforming method using the city gas composed of the natural gas as a raw material has been attracting attention. There is. This is because the city gas, which is a raw material, is supplied to the required place via a conduit, so it is extremely stable and safe in terms of supply and security, and it also saves raw material transportation costs and does not require a raw material storage facility. This is because it has many economic advantages.
In the future, it is expected that the on-site small-capacity hydrogen production equipment that uses city gas, which is natural gas, as a raw material will be popularized by taking advantage of this advantage.

The structure of a conventional hydrogen production apparatus using the steam reforming method will be described with reference to the drawings. FIG. 3 is a system diagram showing the configuration of a conventional hydrogen generator. In the figure,
Natural gas, which is an example of a raw material, is heated to a predetermined pressure by a compressor after a sulfur compound contained in a desulfurization device (not shown) is removed, and then a direct-fired raw material heating furnace 21 is used.
It is preheated to around 350 ℃.

On the other hand, steam necessary for the steam reforming reaction (hereinafter referred to as process steam) is prepared by the following method. That is, the deionized water supplied from the deionized water device outside the system is preheated using the waste heat in the device by a feed water preheater (not shown), and then the multi-tube process steam boiler 2
5 and heat exchange with the high temperature reformed gas that exits the reaction tube 23 of the reforming furnace 22 to supply heat of vaporization to form process steam.

As described above, the generated process steam is superheated up to about 400 ° C. by the high temperature combustion gas leaving the reforming furnace 22 in the process steam superheater 24 so that it is not condensed even if mixed with the raw material gas. To be done. Then, after being mixed with the raw material gas that exits the raw material heating furnace 21, it enters the reaction tube 23 of the reforming furnace 22 filled with the reforming catalyst, and the reaction heat is supplied by the combustion of the fuel gas to change the steam. As a result of the quality reaction, the raw material hydrocarbon becomes a reformed gas composed of hydrogen, carbon monoxide, carbon dioxide and methane.

In the reaction tube 23, the reforming reaction is generally carried out at around 800 ° C. from the viewpoint of reaction equilibrium so that the residual methane in the reformed gas is minimized. Therefore, the reforming furnace 22
The temperature of the combustion gas that exits is also considerably high. Generally, as described above, this combustion gas is supplied to the reforming furnace 22 after the combustion air preheater 26 is provided in the flue in order to measure the heat recovery after the combustion gas is used for overheating the process steam. Used for preheating combustion air.

[0008]

SUMMARY OF THE INVENTION In the conventional hydrogen production apparatus described above, hydrogen is used for facilities such as preheating of raw material gas, generation and overheating of process steam, and heat recovery from combustion gas of a reforming furnace. It can be seen that the structure of the manufacturing apparatus is complicated. This is because the hydrogen production device is operated at a high temperature, so that heat recovery is necessary from the viewpoint of heat economy.

However, an on-site type hydrogen production apparatus (generally 1000 Nm ³ /
In the case of (H or less), if such a complicated device configuration is adopted, not only the equipment cost increases and the production cost of the product hydrogen increases, but also the burden of maintenance of the device is large, The advantages of the on-site hydrogen generator will be lost.

The present invention has been made in view of the above-mentioned problems of the prior art, and the equipment structure for preheating the raw material gas, generation of process steam and overheating is very simple, and the equipment is very simple. It is an object of the present invention to provide a hydrogen production apparatus which is inexpensive and has a small burden in terms of facility maintenance, and which is suitable for a small capacity.

[0011]

The hydrogen producing apparatus according to claim 1 for solving the above-mentioned problems is hydrogen, carbon monoxide and carbonic acid obtained by high-temperature steam reforming of a desulfurized raw material hydrocarbon in a reforming furnace. In a hydrogen production apparatus for producing high-purity hydrogen by converting a carbon monoxide into hydrogen in a CO shift tower, a reformed gas composed of gas, methane, etc., is used as a raw material hydrocarbon. And pure water for water vapor are mixed
It is introduced into the steam heater and heated by heat exchange with the high temperature combustion gas leaving the reforming furnace to form a mixture of high temperature hydrocarbons and steam, which is then introduced into the reaction tube of the reforming furnace for high temperature steam reforming. Provided is a hydrogen production device characterized by carrying out a reaction.

Further, in the hydrogen producing apparatus according to the second aspect, the raw material / steam heater is a shell and tube type heat exchanger, and the raw material hydrocarbons and pure water are fed into the mixing pipe mounted in the inlet channel portion. After uniformly mixing, flow into the heat transfer tube,
The hydrogen production apparatus according to claim 1, wherein a high temperature combustion gas that exits the reforming furnace is caused to flow on the shell side for heat exchange.

The high-temperature steam reforming reaction referred to in the present invention is that a mixture of a raw material hydrocarbon and process steam is passed through a reactor filled with a reforming catalyst to be externally heated by the heat of combustion of fuel, and then exits the reforming catalyst layer. The temperature of the reformed gas after the reaction is 600 to 900.
It means that it is in the range of ° C, and is not particularly limited depending on the structure of the reforming furnace and the like.

Also, the structure of the raw material / steam heater used in the present invention is such that the mixture of the raw material hydrocarbon and the pure water is heated by the high temperature combustion gas leaving the reforming furnace to evaporate and superheat the liquid pure water. Any heat exchanger capable of forming a mixture of high-temperature raw material hydrocarbon gas and steam may be used, and the structure is not particularly limited, but it is preferable that the applicant of the present invention first devises it for adjusting the heat quantity of city gas. The shell-and-tube type heat exchanger proposed in Japanese Utility Model Publication No. 6-47003 is. The structure of this heat exchanger is characterized in that a liquid having a small volume is uniformly dispersed in a gas body having a large volume, and then a heat source fluid is indirectly heated through a heat transfer tube to evaporate the liquid having a small volume. That is, the raw material / steam heater of the present invention is provided with the necessary structure.

The feature of the operation of the present invention is that in the conventional hydrogen production apparatus, the raw material hydrocarbon and the process steam for the steam reforming reaction are separately heated and vaporized / superheated, and then mixed to form a reaction tube. The mixture of the raw material hydrocarbon and pure water was heated by the high-temperature combustion gas leaving the reforming furnace in one heat exchanger to obtain a high-temperature homogeneous mixture in the same state. The point is that it can be obtained and supplied to the reaction tube.

Another feature of the operation of the present invention is that since the conventional process steam boiler for recovering heat from the reformed gas is eliminated, the excess high temperature waste heat of the reformed gas is effectively used. That is, a combustion air preheater is installed at the same position and is used for preheating combustion air.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of the present invention, and FIG. 2 is a vertical sectional view of an embodiment of a raw material / steam heater used in the present invention. In the figure, the raw material gas consisting of natural gas (city gas), which is an example of the raw material, is
After desulfurization by a desulfurization device (not shown), the pressure is raised to a required pressure and the upper channel part of the raw material / steam heater 1 which is a vertical shell-and-tube type heat exchanger having the same structure as the above-mentioned No. 6-47003 13 and is mixed uniformly with pure water which is also supplied to the channel portion by the mixing tube 11 mounted inside the channel, enters the upper end of the heat transfer tube 12 in the vertical direction, and flows down in the tube.

A plurality of horizontal ejection holes are bored in the upper part of the mixing tube 11, and the pure water supplied to the upper channel portion 13 is ejected from the perforations to be uniformly mixed in the raw material gas. To be done. The supply amount of pure water is set so as to satisfy the required mole ratio of process steam to the carbon mole of the raw material hydrocarbon (steam / carbon ratio). In the liquid state of pure water, the volume ratio to the raw material gas is very small, so a structure such as the mixing tube 11 shown in FIG. 2 or a corresponding structure is required.

The mixture of the raw material gas and the pure water is flown through the heat transfer tube 12 of the raw material / steam heater 1 and is heated by the high temperature combustion gas leaving the reforming furnace 2 which rises outside the tube (shell side). Then, it becomes a mixture of city gas and superheated steam at a temperature of around 450 ° C., and exits the lower channel 14 of the raw material / steam heater 1 and enters the reaction tube 3 of the reforming furnace 2 to form a mixture on the reforming catalyst. By steam reforming reaction, hydrogen, carbon monoxide,
It becomes a reformed gas composed of carbon dioxide gas and methane, and exits the reaction tube 3 at a high temperature and flows into the inside of the multi-tube combustion air preheater 4.

In the combustion air preheater 4, the blower 5
The combustion air blown by the gas flows outside the pipe (shell side), exchanges heat with the high-temperature reformed gas to be preheated, is supplied to the reforming furnace 2, and is used for combustion of the fuel gas. In the present embodiment, city gas is used as the fuel because it is safe from the aspect of supply and security because city gas is supplied through the conduit as described above.

After the combustion heat of the fuel gas is supplied to the reaction tube 3 by combustion, the fuel gas exits the reforming furnace 2 and enters the shell side of the raw material / steam heater 1 as described above. After exchanging heat with the mixture of the raw material gas and pure water via 12, the stack 6 is released into the atmosphere.

After the heat is exchanged in the combustion air preheater 4, the temperature becomes 35
The reformed gas, which has fallen to around 0 ° C, is then fed to the CO shift tower 7
The carbon monoxide in the gas is converted into hydrogen by a known conversion reaction on the conversion catalyst to be charged. In this way, hydrogen: 77%, carbon dioxide: 4%, carbon monoxide:
17%, methane: around 2% of the metamorphic gas then enters the PSA (Pressure Swing Adsorption) device 8,
Components other than hydrogen are adsorbed and removed by the adsorbent, and the purity is
It becomes high purity product hydrogen of 99.9% or more.

[0023]

EFFECTS OF THE INVENTION According to the hydrogen producing apparatus having the above-mentioned structure, the heating of the raw material and the generation and overheating of the process steam can be carried out by one heat exchanger, so that the facility cost can be reduced and the maintenance of the apparatus can be performed. Labor saving is possible, and product hydrogen can be economically produced as an on-site type device.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an example of a raw material / steam heater.

FIG. 3 is a system diagram showing a configuration of a conventional hydrogen production device.

[Explanation of symbols]

 1; Raw material / steam heater 2; Reforming furnace 3; Reaction tube 4; Combustion air preheater 5; Blower 6; Stack 7; CO shift tower 8; PSA device 11; Mixing tube 12; Heat transfer tube 13; Upper channel 14 ; Lower channel 15; spout hole

Claims (2)

[Claims] 1. A reformed gas comprising hydrogen, carbon monoxide, carbon dioxide, methane, etc. obtained by high-temperature steam reforming of a desulfurized raw material hydrocarbon in a reforming furnace, and carbon monoxide in a CO shift tower. In a hydrogen production device that produces high-purity hydrogen by processing with a hydrogen PSA device after conversion to hydrogen, a raw material hydrocarbon and pure water for steam are mixed and introduced into a raw material / steam heater, Characterized by heating by heat exchange with the high temperature combustion gas leaving the reforming furnace to form a mixture of high temperature hydrocarbon and steam, which is introduced into the reaction tube of the reforming furnace to carry out high temperature steam reforming reaction. Hydrogen production equipment. 2. The raw material / steam heater is a shell-and-tube type heat exchanger, and the raw material hydrocarbons and pure water are uniformly mixed in a mixing pipe mounted in the inlet channel portion, and then the heat transfer pipe is introduced. 2. The hydrogen production apparatus according to claim 1, wherein a high temperature combustion gas leaving the reforming furnace is caused to flow to the shell side for heat exchange.