JPH04338102A - Method for enriching combustible gas with hydrogen - Google Patents

Abstract

PURPOSE:To enrich the combustible gas generated in melting iron with hydrogen to obtain a gas appropriate for methanol synthesis without hindering the operation of melting iron. CONSTITUTION:An org. fuel and reduced iron are supplied to a melting and gasifying furnace to produce molten iron and a combustible gas. In this case, the content of the fixed carbon in coal as the fuel to be added to the furnace is controlled to 0.3ton per ton of the product pig iron. The amt. of an oxygen- contg. gas to be blown into the furnace is adjusted so that the molten iron in the furnace is controlled to a specified temp. The amt. of hydrogen to be blown into the furnace is adjusted so that the ratio of the number of mols of the total carbon in the combustible gas generated from the furnace to that of the total oxygen is specified.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hydrogen enriching combustible gas generated in a melting gasifier.

0002

[Prior Art] Most of the production of pig iron relies on the blast furnace method, but as is well known, the blast furnace method requires high-quality coking coal and iron ore, so it is possible to replace it in preparation for future deterioration of the raw material situation. As a method, the molten ironmaking method is attracting attention. The molten ironmaking method is an innovative ironmaking method that allows the use of low-grade coal and low-quality iron ore, and does not require coke production or iron ore sintering, which are required in the blast furnace method. A huge amount of flammable gas is generated during iron making, and its effective use determines the economic efficiency of iron making. For this reason, there are inconveniences such as not only restrictions on the use of steam coal with a high volatile content but also restrictions on the setting of operating conditions such as coal supply amount.

On the other hand, from the viewpoint of suppressing the generation of carbon dioxide gas, which is considered to be the cause of global warming, the removal of carbon dioxide gas and the emergence of clean energy with low carbon content have become social needs. Against this background, the present invention aims to meet the social demands for solving the problem of iron making and carbon dioxide gas by efficiently producing methanol, which is a clean energy source, from flammable gas generated during iron making using the molten iron making method. This was done with the aim of meeting the needs of the public.

As is well known, the raw material gas components for methanol synthesis are hydrogen (H2) and carbon monoxide (CO).
, carbon dioxide gas (CO2), whose composition is H2/
It is necessary to satisfy the condition of (3CO2 +2CO)=1. That is, although it is necessary to increase the hydrogen content in the raw material gas, the gas generated during iron making has a low hydrogen content because its source is coal.

[0005] In order to use a gas with a low hydrogen content as a raw material gas for methanol, it is necessary to convert CO into H2.
O-shift reaction operation is necessary, and the lower the hydrogen content, the greater the amount of conversion must be, and the less methanol can be obtained. Therefore,
It is advisable to generate hydrogen-enriched combustible gas during the melt ironmaking process, within a range that does not interfere with the ironmaking operation.

[0006] As a means of hydrogen enrichment, it is known to inject steam in coal gasification operations, and also in molten pig iron making operations, Japanese Patent Laid-Open No. 171510/1983 discloses the method of injecting steam into the produced gas. It is introduced that water vapor can be injected for the purpose of temperature control, and hydrogen enrichment can be achieved as a result.

[0007]

[Problems to be Solved by the Invention] In molten iron making operations, the flammable gas generated in the melting and gasifying furnace that performs the operation is used as reducing gas for iron ore, so it is difficult to reduce the reduction potential (flammable gas) to the gas. It is necessary to have a certain amount of carbon (CO + H2 concentration in the combustible gas), and it is also necessary to have a certain amount of carbon necessary for molten pig iron production in the melting and gasifying furnace. Steam cannot be blown solely for the purpose of achieving temperature control or for the purpose of temperature control.

[0008] As is well known, in the melting ironmaking operation, fuel such as coal is added to a melting and gasifying furnace, and this is partially combusted with oxygen to produce carbon monoxide (CO) and hydrogen (H2) as the main components. This is an operation in which flammable gas is generated and reduced iron is introduced into a gasifier to produce molten pig iron, and iron ore is reduced with the flammable gas generated in the gasifier to produce reduced iron. .

That is, carbon in the fuel is also consumed by oxygen, and the temperature inside the melting and gasifying furnace increases accordingly. If water vapor is injected to control this temperature rise, H2 and CO will be generated through a hydrochemical reaction with carbon, but carbon will also be consumed. Therefore, if there is excessive injection of steam, carbon content will be consumed more than necessary, which will not only make it impossible to retain the carbon content necessary for molten iron making, but also make it difficult to maintain the temperature in the melting and gasifying furnace. Moreover, this results in an increase in the amount of fuel burned, and also leads to a waste of oxygen.

[0010] Furthermore, when the flammable gas generated in the molten pig iron making operation is used as a raw material for methanol synthesis, it is important that the composition is stable in addition to hydrogen enrichment. If there is a change in composition, it will not only change the load on the raw material adjustment process such as CO shift operation, but also change the composition conditions of the raw material gas for methanol synthesis as mentioned above, which is not preferable, but it can be used for temperature control. When steam is blown into the
It is easy to understand that the gas composition varies.

In addition, when methanol synthesis is performed in parallel with ironmaking operations, it is necessary to confirm the flexibility of the plant, and in accordance with the requirements of the methanol synthesis side, dissolved gas can be synthesized without interfering with the molten ironmaking operation. It is necessary to be able to adjust the amount of gas generated in the chemical furnace. That is, it is necessary to increase or decrease the amount of fuel supplied to the melting and gasifying furnace, but it is completely impossible to deal with such a situation using conventional methods.

[0012] The present invention produces methanol from the flammable gas generated in molten pig iron making, thereby improving the economic efficiency of pig iron making and suppressing carbon dioxide emissions. It is an object of the present invention to provide a method for enriching hydrogen suitable for methanol synthesis and stably producing it without hindrance to molten pig iron making operations. That is, the present invention maintains the reduction potential of combustible gas necessary for stable operation of molten pig iron, maintains a predetermined amount of carbon (coke) in the melting gasifier, and maintains an appropriate temperature inside the melting gasifier. (a) Enrich the flammable gas with hydrogen by inhaling water vapor and minimize compositional fluctuations in the flammable gas. (2) Minimize the amount of oxygen blown into the melting and gasifying furnace. (3) The amount of combustible gas generated can be increased or decreased by increasing or decreasing the amount of fuel supplied to the melting gasifier.

[0013] It is an object of the present invention to provide a method for enriching combustible gas with hydrogen generated in a melting gasifier.

[0014]

[Means for solving the problem] Coal (including coke) or coal and other organic fuels (hereinafter collectively referred to as fuel) is added to a melting gasifier, and the fuel is partially combusted and gasified with oxygen. In addition to generating flammable gas mainly composed of carbon oxide and hydrogen, reduced iron (
(including a partially reduced state) to produce molten pig iron, and reduce iron ore with part or all of the flammable gas generated in the melting and gasifying furnace to produce the reduced iron. In the method, (1) Fuel is added so that the fixed carbon content of coal in the fuel added to the melting-gasifier becomes 0.3 ton or more per 1 ton of product pig iron. (2) Adjust the amount of oxygen-containing gas blown into the melting and gasifying furnace so that the temperature of the hot metal in the melting and gasifying furnace becomes a predetermined temperature. (3) The total oxygen component (C
The ratio of the number of moles of O, CO2, H2 O) (hereinafter referred to as O2 /
The amount of steam blown into the melting and gasifying furnace is adjusted so that the C ratio) becomes a predetermined value.

[0015]

[Function] In order to stabilize the molten pig iron making operation, as mentioned above, (1) maintaining the temperature in the melting and gasifying furnace at an appropriate level, (2) maintaining carbon content in the melting and gasifying furnace, (3) It is necessary that the combustible gas generated in the melting gasification furnace maintains the reduction potential necessary for iron ore reduction.

First, to properly maintain the temperature inside the melting and gasifying furnace, the hot metal temperature, which is linked to the temperature inside the melting and gasifying furnace, is detected while fuel is being supplied to the gasifying furnace. When the amount of oxygen-containing gas blown is adjusted so that the temperature becomes a predetermined value, the amount of blown oxygen-containing gas becomes the minimum amount necessary to maintain the temperature of the melting and gasifying furnace. In addition, the composition of the fuel supplied to the melting gasifier is substantially constant, and if the temperature inside the melting gasifier is kept constant, the reduction potential of the combustible gas generated in the gasifier is is determined by the O2 /C ratio of the gas, and the amount of carbon gasified in the melting-gasifier also depends on this O2 /C ratio.
Determined by ratio. Therefore, by selecting an O2/C ratio that does not impair the reduction potential of combustible gas and retaining carbon content in the melting gasifier, and injecting steam so that the value remains constant, the This amount is the maximum amount of steam that can be blown in without causing any trouble to the molten pig iron making operation, and the hydrogen content in the combustible gas is maximized. Also, O in the gas
It is easy to understand that by keeping the 2 /C ratio constant, fluctuations in gas composition are reduced.

Next, regarding the response to changes in fuel supply amount,
When the melting gasifier is operated in a steady state, if the amount of fuel supplied to the melting gasifier is increased for the purpose of increasing the amount of combustible gas generated, the melted gas will increase due to the heat of thermal decomposition of the fuel. The temperature inside the heat treatment furnace decreases, and the temperature of the hot metal decreases. As the hot metal temperature decreases, the amount of oxygen-containing gas blown increases to maintain the set temperature, and the amount of steam blown is adjusted in response to changes in conditions, resulting in an increase in the amount of fuel supplied. The optimal amount of oxygen-containing gas and water vapor to be blown is set according to the time.

That is, the amount of oxygen-containing gas blown into the melting and gasifying furnace is adjusted so that the temperature of the hot metal reaches a predetermined value, and the O2 /
By using the method of the present invention in which steam is injected so that the C ratio becomes a predetermined value, the composition of the combustible gas can be adjusted to the minimum necessary amount of oxygen-containing gas without interfering with the molten pig iron making operation. The hydrogen content in the combustible gas can be maximized while minimizing fluctuations, and the amount of fuel supplied, that is, the amount of combustible gas generated, can be easily increased or decreased.

[0019]

EXAMPLES Next, the present invention will be explained in detail based on examples. FIG. 1 is a system diagram showing an embodiment of the present invention. In the diagram, 1 indicates a melting and gasifying furnace, and 2 indicates a preliminary reduction furnace for producing reduced iron to be supplied to the melting and gasifying furnace. Reduced iron (including partial reduction) produced in the preliminary reduction furnace is supplied to the melting and gasifying furnace through conduit 3, fuel is supplied to the melting and gasifying furnace through conduit 4, and oxygen-containing gas is blown into the melting and gasifying furnace. The filling is carried out through conduit 5, and the injection of water vapor is carried out through conduit 6. In addition, a sludge-forming agent such as limestone is charged into the melting and gasifying furnace as necessary together with fuel through a conduit 4 or a charging port (not shown) provided separately, to improve the basicity, fluidity, desulfurization effect, etc. of the slag. adjusted.

Hot metal produced in the melting and gasifying furnace is taken out from the conduit 7 together with slag. The combustible gas generated in the melting gasification furnace is introduced into the solid-gas separator 9 through a conduit 8, and after separating the solid content, it is blown into the preliminary reduction furnace through the conduit 10, and the separated solid content is dissolved through the conduit 12. It is reduced to the gasifier. The amount of combustible gas blown into the pre-reduction furnace can be appropriately selected depending on the operating conditions of the pre-reduction furnace.
If there is surplus gas, it is taken out from the conduit 11 as crude raw material gas for methanol synthesis.

The combustible gas blown into the preliminary reduction furnace reduces the iron ore supplied from near the top of the furnace, and then passes through the conduit 13.
It is extracted as raw material gas for methanol synthesis. The temperature of the hot metal is detected by a temperature detector (a), and the opening degree of the oxygen-containing gas injection amount control valve (d) is adjusted by a controller (c) so that the temperature becomes a predetermined value. In addition, (b) shows a control microprocessor, which outputs information on the amount of oxygen-containing gas injected, which is calculated from the operating conditions of the melting and gasifier, such as the composition and supply amount of fuel, iron ore, and slag-forming agent. Temperature detector (
b) is adopted when the information is used as supporting information,
This is useful when the operating conditions of the melting gasifier are frequently changed.

[0022] The hot metal temperature, that is, the setting value for temperature control is 1
400°C to 1700°C (preferably 1450°C to 160°C
0°C). As the hot metal temperature detector, a contact type tungsten thermocouple is suitable, and an infrared thermometer is suitable as a non-contact type. The oxygen-containing gas preferably has as high an oxygen purity as possible, and suitably has a purity of 95% by volume or more. High content of impurities such as nitrogen causes problems during methanol synthesis.

The composition analysis of the combustible gas generated in the melting gasification furnace is carried out using an on-line analyzer (a), and the analysis is performed while a small amount of combustible gas is extracted from the conduit 10 at a substantially constant rate. As long as the analyzer has a certain degree of accuracy, it is best to have a short analysis time; for example, an analyzer that uses mass spectrometry and high-speed gas chromatography in combination can be used. The analysis value is processed by the control microprocessor (b), and the O2 /C ratio of the combustible gas (in practice, using the volume ratio of the components in the combustible gas, it is calculated as [CO2 + 1/2 ( H2O
+CO)]/(CO+CO2+CH4) is a predetermined value, the controller (c) adjusts the opening degree of the water vapor injection amount control valve (d).

[0024] The O2/C ratio is selected from the range of 0.2 to 0.7, but when selecting the set value, the (H2 O + C
The control processor (b) processes this information, and the controller (c) controls the O2/ It is also possible to automatically adjust the set value of the C ratio.

If it is necessary to adjust the temperature of the flammable gas supplied to the pre-reduction furnace, known means such as cooling the combustible gas extracted from the conduit 11 and then circulating a part of it may be adopted. can. CO and H2 in the combustible gas supplied to the pre-reduction furnace reduce iron ore and convert into carbon, respectively.
The gas becomes O2 and H2O, and the concentration of CO2 and H2O in the gas extracted from the conduit 13 increases, but by removing these CO2 and H2O, it can be used as a raw material for methanol synthesis. Furthermore, the consumption rates of CO and H2 in the reduction of iron ore are approximately the same, and the hydrogen-enriched combustible gas does not impair its quality as a raw material for methanol synthesis in the preliminary reduction furnace.

Various methods have been proposed for the molten pig iron making process, such as using a fluidized bed method in the preliminary reduction furnace, as is well known, but the function of the melting and gasifying furnace is the same in all methods. The method of the present invention is useful in any hot melt ironmaking process. Next, specific experimental results of the present invention will be explained. Iron ore used: Total iron concentration 68% by weight, supply amount 1.47t/
hr Fuel used: Steam coal, composition: C71.19% by weight, H2
4.69% by weight, O2 7.62% by weight, N2 1.4
0% by weight, S 0.29% by weight, ash 12.4% by weight
, inherent moisture 2.41% by weight, supply rate 1.36t/hrOxygen-containing gas used: Purity 98% by volume or more Pre-reduction furnace type: Moving bed shaft furnace Comparison of the conventional method and the method of the present invention under the above conditions An experiment was conducted.

In experiments using the conventional method, the amount of oxygen-containing gas blown was kept approximately constant, and water vapor was blown in so that the temperature of the flammable gas at the outlet of the melting gasifier reached 1000°C. In addition, the oxygen-containing gas was blown in so that the hot metal temperature was 1500°C, and the steam was blown in so that the O2/C ratio in the combustible gas was 0.55. .

The experimental results are shown in Table 1.

[0029]

[Table 1]

As is clear from the above experimental results, compared to the conventional method, the method of the present invention can reduce the amount of oxygen-containing gas blown into the gas, and can also obtain a combustible gas that is significantly enriched in hydrogen. The flammable gas obtained from conduits 11 and 13 is
Assuming that methanol synthesis is performed by adjusting the O shift reaction operation, purification operation, etc., the amount of methanol obtained by the conventional method is about 0.7 t/t pig iron, and the amount of methanol obtained by the method of the present invention is about 0.9 t/t pig iron and methanol. The quantity will be greatly improved.

[0031]

Effects of the Invention The method for enriching hydrogen in combustible gas according to the present invention involves adding coal or coal and other organic fuel to a melting gasifier, and partially combustion gasifying the fuel with oxygen to produce carbon monoxide and hydrogen. At the same time, molten pig iron is produced by producing flammable gas mainly composed of In a method for producing reduced iron by reducing iron ore with part or all of the gas, the amount of fixed carbon in the coal in the fuel added to the melting and gasifier is 0.3 tons or more per 1 ton of pig iron product. The amount of oxygen-containing gas injected into the melting and gasifying furnace is adjusted so that the temperature of the hot metal in the melting and gasifying furnace reaches a predetermined value. By adjusting the amount of water vapor blown into the melting and gasifying furnace so that the ratio of the number of moles of all oxygen components to the number of moles of all carbon components becomes a predetermined value, the following effects can be obtained.

[0032] The flammable gas generated in molten pig iron making can be enriched with hydrogen to make it suitable for methanol synthesis without causing any hindrance to the molten pig iron making operation, improving the economic efficiency of pig iron making, It becomes possible to suppress carbon dioxide emissions.

[Brief explanation of drawings]

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

[Explanation of symbols]

1 Melting and gasification furnace 2 Preliminary reduction furnace 9 Solid-gas separator B Temperature detector a Online analyzer B Control microprocessor b Control microprocessor C Controller c Controller D Controller d Controller

Claims (1)

[Claims] Claim 1: Coal and other organic fuels are added to a melting gasification furnace, and the fuel is partially combustion gasified with oxygen to generate a combustible gas containing carbon monoxide and hydrogen as main components, and the melting In the method of producing molten pig iron by adding reduced iron to a gasification furnace, and reducing iron ore with a part or all of the combustible gas generated in the melting and gasification furnace, the method includes: The amount of fixed carbon in the coal added to the melting and gasifying furnace is
The amount of oxygen-containing gas injected into the melting and gasifying furnace is adjusted so that the temperature of the hot metal in the melting and gasifying furnace reaches a predetermined value. It is characterized by adjusting the amount of steam blown into the melting gasifier so that the ratio of the number of moles of all oxygen components to the number of moles of all carbon components in the combustible gas generated from the combustible gas is adjusted to a predetermined value. A method for enriching combustible gas with hydrogen.