JPS63225510A - Production of co-rich gas - Google Patents

Abstract

PURPOSE:To improve the durability of a combustion furnace and to increase the amount of CO in the product gas, by blowing CO2 into the combustion furnace along the inner wall side, when a hydrocarbon type fuel is imperfectly burnt in the combustion furnace to produce a reductive gas containing H2 and CO. CONSTITUTION:The hydrocarbon type fuel (for example, natural gas) is introduced in the combustion furnace 1 through the fuel introducing pipe 2 of a main burner 8 and an auxiliary burning material (for example, air) is introduced through an auxiliary burning material introducing pipe 3 to carry out imperfect combustion, and the reductive gas containing at least H2 and CO. In this case, CO2 is blown into the combustion furnace 1 through the CO2 introducing pipes 4 disposed near the inner wall surface of the combustion furnace 1 so as to ascend along the inner wall surface so that the inner wall is cooled and prevented from bringing into direct contact with the flame produced by the burner 8, and is prevented from melting. Moreover, as this method eliminates the need of introduction of steam for adjusting the temp. in the furnace, the production amount of H2 is reduced and a CO-rich gas is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention produces gas containing H2 and CO (hereinafter referred to as Co-rich gas) by incompletely burning hydrocarbon fuel in a combustion furnace.
In particular, the present invention relates to a method for producing a CO-rich gas that can improve the durability of a combustion furnace and adjust the amount of Co.

[Prior art] A hydrocarbon fuel such as fuel oil, naphtha, or natural gas is incompletely combusted alone or mixed with steam and/or CO2 to produce a mixed gas containing H2+Co, Cow, H20, etc. The manufacturing method for spears has already been put into practical use. The gas produced here contains H2 derived from hydrocarbons and H2 derived from steam, and therefore H2
Because it is rich, it is widely used as a raw material gas for ammonia production. Since a part of the raw material is used as the heat source for the above reaction to proceed, there is no need to apply heat from the outside like in reforming to maintain the reaction temperature, and the combustion furnace is lined with refractory material. An extremely simple structure with a stretched cylindrical shape may be sufficient.

[Problem to be solved by the invention] The steam added in the above method is H.

Not only is it effective in producing rich gas, but it also serves as a cooling protector for large furnace wall components. However, if too much steam is added, the combustion temperature will drop too much and the combustibility will drop, resulting in a large amount of carbon being generated, and therefore a carbon removal device must be installed at a later stage.

For example, the amount of carbon generated increases when ca Ha → 6
C+31(z (decomposition reaction)-(1)C+ 02 →
COz ”' (2a) C+Co2→
This is because when the combustion temperature decreases in the reaction of 2CO.-(2b), the reactions of (2a) and (2b) become slower than the reaction of (1).

The addition of steam lowers the temperature inside the furnace, but since the high-temperature reaction of combustion is already occurring inside the furnace, the temperature is quite high, and damage to the furnace walls due to contact with the flames can be avoided. There are no such problems, so some measures are being taken to deal with this problem, such as making the furnace larger.

On the other hand, in recent years, C1 using a compound with one carbon number as a starting material
Chemistry is gaining attention and the need to produce CO-rich gas is increasing. Therefore, in the present invention, consideration has been given to providing a method for producing CO-rich gas that can protect the furnace wall and also make it possible to adjust the amount of CO in the generated gas.

[Means for Solving the Problems] The present invention has solved the above-mentioned problems by at least partially burning a hydrocarbon fuel in a combustion furnace with the addition of steam and/or CO2 as necessary. A method for producing a reducing gas containing H, and CO, the gist of which is to inject CO2 into the inner wall surface of the combustion furnace.

[Operation] FIG. 1 is a cross-sectional view showing an example of a furnace body structure suitable for carrying out the present invention, and the gist of the present invention will be explained below based on FIG. 1. Note that FIG. 1(a) is a longitudinal cross-sectional view, and FIG. 1(b) is a vertical cross-sectional view.
) is a sectional view taken along line AA' in FIG. 1(a).

The main burner 8 in the combustion furnace 1 is formed by a double pipe consisting of a fuel introduction pipe 2 and a combustion improver introduction pipe 3.
For example, hydrocarbon fuel (hereinafter also simply referred to as fuel) containing steam is preheated and then introduced into the combustion furnace 1 through the fuel introduction pipe 2.
(or air) is introduced through the combustion improver introduction pipe 3 to combust a part of the fuel, and the combustion heat generated at that time is used to separate and gasify the remainder of the fuel to generate incomplete combustion gas.

On the other hand, CO2 is blown into the combustion furnace 1 from the COI introduction pipe 4 arranged near the inner wall surface of the combustion furnace 1.
rises along the inner wall of the combustion furnace 1, cools the inner wall, prevents the flame from the burner from coming into direct contact with the inner wall, and blocks radiant heat. Therefore, it is possible to prevent melting damage such as hot spots from occurring on the furnace wall and to extend the life of the furnace wall. Furthermore, this CO2 is mixed with the combustion gas and discharged from the exhaust gas pipe 5. In FIG. 1, 6 is a temperature measuring flange, and 7 is a pilot burner.

The reactions taking place in this combustion furnace are as follows. Of these reaction equations, reactions in equations (4) and (5) show the case where steam is blown together.

2 ICmHn+m
H20-4mC0+ (m+-)H.

CO+ H20-C02+ H2"" (S) Here, hydrocarbon fuels include natural gas, off-gas from refineries, aromatic hydrocarbons such as benzene, light oil such as naphtha, heavy oil, or mixtures thereof, etc. These fuels can be used alone or in combination with steam and/or CO. In the above reaction formula, the hydrocarbon fuel is expressed as CmHn, but there are no restrictions on their component composition. The role of C02 and steam is to suppress the generation of C (soot), as will be described later.

The CO2 injected from the CO2 introduction pipe 4 may be obtained through any route, but as shown in Fig. 2, the gas discharged from the exhaust gas pipe 5 is collected by exhaust heat recovery, carbon removal, moisture removal, and gas separation. It is recommended to recycle the CO7 collected through various devices such as . In this way, in the present invention, since steam is not introduced to adjust the temperature inside the furnace, H2
Since the production amount of CO is reduced, the CO gas ratio is relatively improved, and the C conversion rate is also improved, it has become possible to obtain a certain Co-rich gas for the purpose of the present invention. Further, it is possible to prevent a decrease in combustion temperature and the accompanying decrease in combustibility, and as a result, it is possible to suppress the amount of carbon generated. The generated C reacts with CO2 and H2O to generate CO or H2 as the temperature inside the furnace increases.

C+CO2→2CO C+H20→H,+CO In this case, adding only steam will not make the mixture rich in CO, and blowing in a large amount of steam will lower the combustion temperature more than blowing in CO3. As described above, according to the present invention, it is possible to improve the heat utilization efficiency and reduce fuel consumption, and these aspects also contribute to an increase in the amount of CO produced.

[Example] Fuel, combustion improver, and CO2 for injection into the inner wall side were introduced into the combustion furnace 1 shown in FIG.
Produced rich gas. The resulting produced gas amount, outlet gas temperature, gas component composition, 82/Co and C conversion rates are as shown in the lower column of the same table. Furthermore, the influence of the injection of 002 on the inner wall surface side on the temperature distribution in the furnace at this time is shown in FIG.

Table 1 Comparison of combustion conditions and results (S CF M: 5 standard Cubic
feet/@1 nut@) As is clear from Table 1, when the amount of 002 blown into the inner wall side is increased, the amount of C in the generated gas increases.
The amount of O can be increased, H2/Co can be reduced, and C
The conversion rate can be increased. Furthermore, as is clear from FIG. 3, by introducing CO3, the temperature of the inner wall of the furnace can be lowered as a whole. In other words, the maximum temperature inside the furnace can be lowered by about 13°C at the outlet and by about 20°C.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to eliminate the adverse effects associated with the introduction of H2O for temperature adjustment in the furnace, and to inject CO7 into the inner wall side of the combustion furnace. It is possible to improve the durability and increase the amount of Co in the generated gas without increasing the size.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of a combustion furnace for carrying out the present invention, Fig. 2 is a schematic diagram showing an example of the process flow of the present invention, and Fig. 3 is a schematic diagram showing an example of the process flow of the present invention. It is a figure showing the influence on temperature distribution. 1... Combustion furnace 2... Fuel introduction pipe 3...
Combustion aid introduction pipe 4-CO, introduction pipe 5...exhaust gas pipe
6...Temperature measurement flange 7...Pilot burner 8...Main burner 9...Exhaust heat boiler 10-
...Scrubber 11.13.18...Drum 1
2...Dust collector 14-...Compressor 1
5...H20 removal device 16.-CO2 adsorption device 17
...Con detachment device

Claims (1)

[Claims] A method for producing a reducing gas containing at least H_2 and CO by incompletely burning a hydrocarbon fuel in a combustion furnace, characterized in that CO_2 is injected into the inner wall side of the combustion furnace. Method.