JP6395493B2 - Apparatus and method for supplying gas to blast furnace - Google Patents

Description

The present invention relates to an apparatus and method for conducting a chemical reaction of a fluid using a catalyst. More specifically, the present invention relates to a gas supply apparatus and method for a blast furnace that enables reduction of carbon dioxide (CO ₂ ) generated in iron making using the blast furnace method.

As a countermeasure against global warming, it is widely demanded to reduce the amount of CO ₂ generated with industrial production. As part of this, in order to reduce the amount of CO ₂ generated in ironmaking using the blast furnace method, hydrogen gas is produced and supplied to the blast furnace shaft part to reduce iron ore with hydrogen to produce pig iron. Non-Patent Documents 1 and 2 disclose techniques for reducing the amount of carbonaceous material such as coke used in a blast furnace as a reducing material and fuel (carbon input: the amount of carbon input when producing pig iron 1t). ing. Here, the reason for supplying hydrogen gas not from the blast furnace tuyere but from the shaft part is that the limit amount of pulverized coal that can already be supplied is usually blown from the blast furnace tuyere. When gas is supplied from the tuyere, efficient blast furnace operation is difficult both in terms of space volume and heat, so hydrogen is supplied from the blast furnace shaft part with little residual oxygen and sufficient heat. It is said that it is advantageous.

  Other prior art documents related to the supply of gas to the blast furnace include Patent Documents 1 to 5 and Non-Patent Document 3.

  Patent Document 1 describes a technique for producing hydrogen by steam reforming a gas containing tar and methane using a catalyst.

Patent Document 2 describes a technique for supplying preheated gas mainly composed of H ₂ and CO from a blast furnace shaft portion.

  Patent Document 3 describes a technique for supplying a gas obtained by partially oxidizing natural gas or coke oven gas from a blast furnace shaft portion.

  Patent Document 4 describes a technique in which coke oven gas, steam, and oxygen are introduced into a reforming furnace to perform partial oxidation and steam reforming reaction without catalyst.

  Patent Document 5 describes a technique for producing a gas rich in methane by supplying coke oven gas, fuel gas, and oxygen to a mixing area, and then introducing the gas into a reaction chamber to cause a reforming reaction (partial oxidation reaction). ing.

  Non-Patent Document 3 describes DAPS (Dry-cleaned and Agglomerated Precompaction System) and SCOPE21 (Super Cooker for forensic enhancement of technology 21) as coal moisture reduction means.

JP 2011-212552 A Japanese Patent Publication No.46-33378 Japanese Patent Publication No.37-8804 JP 2011-11959 A JP 2001-220484 A

CAMPS-ISIJ, vol. 23 (2010), pp. 1025 CAMPS-ISIJ, vol. 25 (2012), pp. 886 Kenji Kato: Journal of the Japan Institute of Energy, vol. 87 (2008), pp. 344-352

By supplying hydrogen gas to the blast furnace shaft, the carbon input of the blast furnace alone is reduced. However, the supplied hydrogen gas needs to be industrially produced, and generally consumes energy when producing the hydrogen gas. The energy that is the consumed unless obtained using fossil fuels, always CO ₂ is produced along with the hydrogen production (unit producing hydrogen gas amount (mol) produced CO ₂ (mol per), hydrogen production when CO ₂ produced I will call it quantity).

In order to reduce the amount of CO ₂ generated by refining using hydrogen in iron making using the blast furnace method, it is necessary to reduce at least the total amount of CO ₂ generated through hydrogen production and blast furnace operation. Therefore, the amount of CO ₂ produced during hydrogen production (mol) must be sufficiently smaller than the carbon input amount (mol) that can be reduced per unit hydrogen gas supply amount (mol) to the blast furnace shaft.

If a gas that originally contains hydrogen, for example, coke oven gas (COG), is supplied to the blast furnace shaft portion as it is, no CO _{2 is} generated due to hydrogen production. However, COG has low boiling point hydrocarbons such as methane gas (methane, ethane, propane, ethylene, etc. that can exist in the gas phase at normal temperature and normal pressure, which can hinder operation at the blast furnace shaft. Therefore, it is simply referred to as “methane”) and cannot be supplied to the blast furnace shaft portion as it is, and it is necessary to remove methane from the COG. Methods for removing methane from COG include methods using membrane separation, physical adsorption, chemical absorption, etc., all of which require a large amount of energy for methane removal (a large amount of CO ₂ is generated) and these methods. Then, since hydrogen is not newly produced, the amount of CO ₂ produced during hydrogen production is also taken into account (not CO ₂ saving). Therefore, there is a need for a methane reforming method in which COG methane is removed by being decomposed and hydrogen is generated at this time.

In the conventional technology for reforming hydrocarbons such as natural gas, heavy oil, and COG to decompose most of the hydrocarbons, gas components for supplying the blast furnace shaft part under low CO ₂ conditions (high purity hydrogen (for example, 70 vol%) As described above, the supply gas satisfying the conditions that hardly contains methane (for example, the methane concentration is 3 vol% or less) and hardly contains CO ₂ (for example, 3 vol% or less)) is CO ₂ -saving conditions (CO ₂ generated during hydrogen production) It was not possible to produce it by making the amount sufficiently smaller than the carbon input reduction amount in the blast furnace. For example, in the case of the techniques of Patent Documents 1 and 5, the methane concentration is excessive, in the case of the techniques of Patent Documents 2, 3, 4, and 5, the hydrogen concentration is excessively low. ₂ becomes excessive. For example, in the case of Patent Document 5, as will be discussed later in Comparative Example 5, in the reforming by partial oxidation of coke oven gas according to Patent Document 5, reducing gas for supplying the blast furnace shaft portion is produced under the condition of CO ₂ saving. I can't do it.

In view of the above circumstances, the reducing gas for a blast furnace shaft supply and to provide an apparatus and method for manufacturing the condition of saving CO _2.

In order to reduce the amount of CO ₂ generated by refining using hydrogen in ironmaking using the blast furnace method, as described above, the amount of carbon input that can be reduced per unit hydrogen gas supply (mol) to the blast furnace shaft ( mol), the amount of CO ₂ produced during hydrogen production (mol) must be sufficiently smaller.

Regarding the prior art, when the relationship between the amount of carbon input and the amount of CO ₂ produced during hydrogen production was examined, for example, in Non-Patent Document 2, 5.22 kmol of hydrogen gas per 1 ton of pig iron was supplied to a simulated blast furnace. , About 10 kg (ie 0.83 kmol) of carbon input per ton of pig iron is described. Therefore, assuming that all of the supplied 5.22 kmol of hydrogen gas is produced, the amount of CO ₂ produced during hydrogen production allowed for producing 1 mol of hydrogen gas is at most 0.16 mol (= 0.83 / 5. 22). Actually, there is no point in producing hydrogen unless the amount of CO ₂ produced during hydrogen production is sufficiently smaller than this value. That is,
[Amount of CO ₂ produced during hydrogen production] << 0.16 mol _{CO 2} / mol _{H 2}
Must.

Starting with this, the present inventor has intensively studied and as a result, has come to the conclusion that the following is effective in order to solve the above-mentioned problems.
(1) a reducing gas hydrogens mainly blown into the blast furnace shaft, hydrogen production during the generation amount of CO ₂ is such less than 0.10 mol _CO2 / mol _H2, to produce a high saving CO ₂ conditions.
(2) By using COG that can be self-supplied by the steelworks as a raw material for the reducing gas, the steelworks purchases compared to the case where hydrocarbons such as oil and natural gas are newly purchased and used as the raw material for the reducing gas. and less carbon, increasing the saving CO ₂ resistance.
(3) In particular, by performing hydrogen production using tar in crude COG, which has not been consumed in the iron making process, as one of the raw materials, the raw materials are effectively used, and CO ₂ saving is enhanced.
(4) Component suitable as reducing gas for blast furnace shaft by producing secondary reformed gas from primary reformed gas obtained by thermal decomposition reaction of crude COG containing tar by partial oxidation at high temperature Is produced under reduced CO ₂ conditions.

The gist of the present invention thus completed is as follows.
(1) 1) It is provided with means for reducing moisture in coke oven gas by drying coal supplied to the coke oven in advance or by spontaneously evaporating the moisture of coal supplied to the coke oven in advance. Coke oven,
2) a carbonization furnace that is maintained at 700 ° C. or higher and pyrolyzes coke oven gas generated from the coke oven;
3) a gas purifier for removing tar and at least a portion of moisture in the gas extracted from the carbonization furnace;
4) a gas transport device for boosting the gas after purification;
5) a gas preheating device;
6) a partial oxidation reformer equipped with means for mixing combustion gas with the gas for partial oxidation of the preheated gas;
7) a gas supply port to the blast furnace shaft,
8) A vent pipe connecting the above 1) to 7) in this order;
A gas supply device for a blast furnace, comprising:
(2) A means for mixing the preheated gas and the combustion gas in the partial oxidation reforming apparatus,
(A) a combustor for receiving supply of oxygen gas and combustible gas and supplying combustion gas generated by combustion of combustible gas to the partial oxidation reformer;
(B) a supply pipe for supplying oxygen gas and combustible gas separately or together into the partial oxidation reformer;
(C) a supply pipe for independently supplying oxygen gas into the partial oxidation reformer;
The gas supply device for a blast furnace according to (1) above, wherein the gas supply device is any one of the above.
(3) The gas supply apparatus for a blast furnace according to (1) or (2), wherein the carbonization furnace includes a catalyst layer filled to reform tar.
(4) The gas supply apparatus for a blast furnace according to (3), wherein the carbonization furnace includes solid carbon separation means for removing solid carbon deposited between the catalysts in the catalyst layer online.
(5) The solid carbon separation mechanism includes a cage that holds the catalyst layer in contact with the inner wall of the carbonization furnace, and a drive mechanism that raises and lowers the catalyst layer by raising and lowering the cage. The gas supply apparatus to a blast furnace as described in said (4) characterized by the above-mentioned.
(6) The gas supply apparatus for a blast furnace according to any one of (1) to (5), wherein the combustible gas is natural gas.
(7) A gas holder for temporarily storing the purified gas between the gas transport device for boosting the gas after purification and the preheating device; and another gas transport means for boosting the gas from the gas holder; The gas supply apparatus for a blast furnace according to any one of (1) to (6), characterized in that
(8) 1) Using the gas supply apparatus for a blast furnace according to any one of (1) to (6) above,
2) When the coke oven gas from the coke oven is vented to the carbonization furnace, the hydrogen concentration is increased by decomposing hydrocarbons in the coke oven gas into coke and hydrogen,
3) Tar and at least a part of moisture in the gas that has passed through the carbonization furnace are removed by the gas purification device to produce a first reformed gas,
4) pressurizing the first reformed gas with the gas transfer device;
5) Preheat the first reformed gas whose pressure has been increased with the preheating device,
6) Supplying the preheated first reformed gas to the partial oxidation reformer and supplying combustion gas to reform hydrocarbons in the first gas to increase hydrogen concentration Producing the second reformed gas,
7) Supplying the second reformed gas into the blast furnace from a gas supply port to the blast furnace shaft portion.
A method of supplying gas to a blast furnace.
(9) The method for supplying gas to a blast furnace according to (8) above, wherein the pressure of the first reformed gas is increased to a pressure of at least 0.2 MPa by the gas transfer device.
(10) The gas supply method to a blast furnace according to (8) or (9) above, wherein the first reformed gas is preheated to 300 to 800 ° C. in the preheating device.
(11) Combustion gas to the partial reformer,
(A) supplying oxygen gas and combustible gas as a combustion gas generated by supplying a combustor;
(B) supplying oxygen gas and combustible gas by supplying the gas into the partial reformer and generating combustion gas in the partial oxidation reformer;
(C) supplying oxygen gas by supplying it into the partial oxidation reforming apparatus and combusting a part of the first reformed gas;
The gas supply method to a blast furnace according to any one of (8) to (10) above,
(12) The gas boosted by the gas transport device is temporarily stored in a gas holder, and the gas from the gas holder is further boosted by another gas transport means and then supplied to the preheating device, (8) The gas supply method to the blast furnace in any one of (11).

  In short, the present invention uses a crude coke oven gas (crude COG) as a raw material for reducing gas to the blast furnace, and tar in the crude COG that has not been consumed in the steelmaking process until now is one of the raw materials. Hydrogen production by thermal decomposition (primary reforming) is performed, and the primary reformed gas obtained thereby is further reformed (secondary reforming) at a high temperature.

In contrast to the present invention that utilizes the two-stage reforming as described above, it is difficult to produce a blast furnace reducing gas with high CO ₂ saving property by only reforming alone, as shown below.

(A) Steam reforming method using crude COG catalyst The crude COG usually contains less than 10% of steam. For the purpose of reforming the total amount (decomposition) of the crude COG tar, in many cases, the tar is reformed (steam reforming) after adding a large amount of steam to the crude COG. For this reason, in the catalytic reforming in the crude COG, the reforming is performed under an excessive water condition, and the production of CO ₂ is excellent by the following aqueous shift reaction.
CO + H ₂ O → CO ₂ + H ₂
That is, the CO ₂ byproduct during hydrogen production by the aqueous shift reaction is 1.0 mol / mol, and the CO ₂ saving property is extremely low. For this reason, since a large amount of CO ₂ is by-produced during reforming, it is difficult to reform the crude COG catalyst under CO ₂ -saving conditions. Further, H ₂ S contained in a large amount (several thousand ppm) in the crude COG remarkably inhibits the catalytic reforming of methane in the crude COG, and a large amount of methane remains in the reformed gas. Cannot be used for reducing gas for shafts.

(B) Partial Oxidation Method of Crude COG As in Patent Document 4, there may be a method of partially oxidizing crude COG. However, when oxygen is supplied to the crude COG, hydrogen having a high combustion rate is first selectively burned and steamed, so that reforming is performed under an excessive steam condition, and there is a problem that CO ₂ saving is low.
Further, when reforming methane in the crude COG, the tar contained in the crude COG is also reformed at the same time, so in order to remove harmful methane by reforming, more oxygen is supplied. There is also a problem that the amount of water vapor generated is greater.
Furthermore, since there is no inexpensive industrial means for raising the normal pressure crude COG at a high temperature, the reformed gas must be cooled once and then supplied to the blast furnace after being pressurized and heated. This further reduces CO ₂ saving.

(C) Steam reforming method using purified COG catalyst There are also means for catalytic reforming of purified COG. However, there is no tar in the purified COG and the water concentration is low. Unlike tar reforming, which is easily pyrolyzed (reforming that does not require moisture), methane, which is the main component in purified COG, can only be reformed by steam reforming. must be modified after having heated the steam each purified COG upon addition of energy to loss greatly saving CO ₂ is unlikely.
In addition, even if the purified COG is heated again to about 800 ° C., which is the heat limit of the COG reforming catalyst, and then the catalyst is reformed, the reformed composition is suitable in equilibrium at such a low temperature. At normal pressure (low temperature, high water vapor concentration, and excessive CO ₂ content under high pressure conditions), the reformed gas is supplied to the blast furnace shaft operated at high pressure. Since it cannot be supplied directly and requires operations such as cooling, pressurization, and re-heating, it is low in energy efficiency and it is difficult to produce gas with reduced CO ₂ .

(D) Partial oxidation method of purified COG If purified COG is partially oxidized, most of the main component methane can be reformed. However, the partial oxidation method has a smaller amount of hydrogen generation per hydrocarbon than the steam reforming method (catalytic reforming method) and has the effect of selectively burning and consuming hydrogen. It is difficult to sufficiently increase the hydrogen concentration inside (only the CO concentration tends to increase in the reformed gas). If partial oxidation is performed after adding steam, steam reforming occurs at a high temperature during combustion, but it is difficult to produce a CO ₂ -saving gas similar to the catalytic reforming method of purified COG.

As is clear from the above, reforming of crude COG containing tar (catalytic method, partial oxidation method) alone or reforming of purified COG without tar (catalytic method, partial oxidation method) alone results in the desired components. Reducing gas cannot be produced under CO ₂ -saving conditions.

(E) Thermal decomposition method of crude COG / refined COG Although it is known that some hydrocarbons in coke oven gas are thermally decomposed in the upper space in the coke oven maintained at 1000 ° C. or higher, The cracking rate is small, and the coke oven gas simply does not function as a carbonization furnace if it is kept at a high temperature.
In addition, when compared with hydrocarbons in coke oven gas, tar is relatively easily pyrolyzed to produce coke, but the decomposition rate of methane is extremely low. For this reason, even if hydrocarbons in the coke oven gas can be decomposed using a carbonization furnace, a large amount of methane remains in the reformed gas (crude COG / refined COG). It cannot be applied to.

Next, a combination of the above reforming methods will be examined.
In the case of performing secondary reforming (catalytic reforming, partial oxidation) with the reformed gas of the purified COG as the primary reforming gas, the temperature is raised during the primary reforming and the subsequent cooling, Since multiple temperature raising processes are required, the reducing gas cannot be produced under CO ₂ -saving conditions.

When the reforming gas of the crude COG is used as the primary reforming gas and further secondary reforming is performed by catalytic reforming, the temperature is raised during the secondary reforming and then cooled, and the temperature is raised again after the pressure is raised before supplying the blast furnace In addition, since a plurality of temperature raising processes are required, the reducing gas cannot be produced under CO ₂ -saving conditions.

When the reformed gas of the crude COG is used as the primary reformed gas and the secondary reforming is further performed by partial oxidation, the CO ₂ saving performance obtained by the crude COG reforming (catalytic reforming / partial oxidation) as described above. As long as the primary reformed gas having a low temperature is used as the raw material, the secondary reforming by partial oxidation, which is originally inferior in the ability to increase the hydrogen concentration compared with the steam reforming method, cannot satisfy the overall CO ₂ saving property.

  Since a large amount of water is contained in the crude COG, in the crude COG reforming using the catalyst, steam reforming is always the main component, and reforming based on thermal decomposition cannot be performed.

Thus, even when the above reforming methods are combined, it can be understood that gas production with reduced CO ₂ is difficult.

In the present invention, crude COG is subjected to thermal decomposition treatment (primary reforming) to produce hydrogen, and the primary reformed gas containing hydrogen obtained thereby is partially oxidized (secondary reforming), thereby providing a blast furnace. The reducing gas for blowing the shaft part is produced under CO ₂ -saving conditions.

Since the crude COG contains tar that is easily pyrolyzed, hydrogen can be produced by pyrolyzing the crude COG. If the crude COG to be pyrolyzed contains a large amount of water, the thermal decomposition reaction is hindered. Therefore, a means for removing moisture from the crude COG is provided in the coke oven. The thermal decomposition of the crude COG is performed in a carbonization furnace containing a catalyst. Since crude COG is generated at a temperature of 700 ° C. or higher, supplying this temperature to the carbonization furnace while maintaining this temperature provides a temperature required for pyrolysis (700 ° C. or higher when using a catalyst) in the carbonization furnace. There is no need to raise the temperature of the COG, and hydrogen production is possible under CO ₂ -saving conditions.

Next, most of the methane remaining in the primary reformed gas is reformed by the partial oxidation method by heating the primary reformed gas containing hydrogen obtained from the carbonization furnace to a temperature exceeding 1000 ° C. Thus, hydrogen can be further produced to produce a reducing gas (secondary reformed gas) for supplying the blast furnace shaft portion. By raising the pressure of the primary reformed gas to 0.2 MPa or more in advance, the secondary reformed gas can be directly supplied to the blast furnace shaft portion, and the number of times of gas temperature increase required for reforming may be one. . Further, since the gas volume is increased by the partial oxidation (in the standard state), the gas flow rate to be compressed may be small. From these effects, it is possible to produce reducing gas under CO ₂ -saving conditions.

To raise the temperature of the primary reformed gas, a large amount of energy is required to raise the temperature by using the mixture with the combustion gas and reforming the primary reformed gas using water vapor contained in the combustion gas. Therefore, it is not necessary to add water or water vapor from the outside, and it is possible to produce a reducing gas under CO ₂ -saving conditions.

  When a gas having a high hydrogen concentration such as the primary reformed gas is burned, hydrogen is selectively burned to generate water vapor. Production of an appropriate amount of steam is necessary for reforming, but excess steam remains in the secondary reformed gas as it is, so that hydrogen consumed during combustion is wasted and the reforming efficiency is lowered. Thus, by using a fuel having a low hydrogen gas concentration such as natural gas as the fuel for the combustion gas, consumption of the hydrogen concentration can be avoided.

(Method for evaluating the amount of CO ₂ produced during hydrogen production)
Regarding the present invention, whether the apparatus and method for evaluating and evaluating the amount of CO ₂ produced during the production of hydrogen contained in the reducing gas supplied to the blast furnace is effective for supplying blast furnace gas under CO ₂ -reducing conditions. Judge whether.

In the prior art, sufficient consideration was not given to the amount of CO ₂ produced during hydrogen production of hydrogen supplied to the blast furnace shaft, so the value of the amount of CO ₂ produced during hydrogen production in the prior art is not accurately known. . The present inventors have devised the following evaluation methods, representative calculate the hydrogen production during the generation amount of CO _2? CO2 ₂ in the prior art, it both difficult high purity hydrogen production for saving CO ₂ I found.

Consider reforming hydrocarbons as a hydrogen production method. Other methods, such as water electrolysis, were excluded from the study because they clearly showed significantly greater ΔCO ₂ than the reforming method.

The target hydrocarbon reforming reaction is as follows (however, the coefficient of the reaction formula is omitted).
Steam reforming reaction: C _n H _m (hydrocarbon) + H ₂ O → H ₂ + CO + CO ₂
Pyrolysis reforming reaction: C _n H _m (hydrocarbon) → C _n H _{m ′} (coke, _n >> _m ′) + H ₂
Partial oxidation reforming reaction: C _n H _m (hydrocarbon) + H ₂ + O ₂ → H ₂ + H ₂ O + CO + CO ₂
The partial oxidation reforming reaction results in a high temperature field and is often accompanied by a steam reforming reaction.

  The composition of the reformed gas was an equilibrium composition at the reforming temperature. In general, the hydrogen generation reaction by reforming has a lower reaction rate, and the closer to the equilibrium composition, the more advantageous is the hydrogen concentration in the reformed gas. Since the reformed gas after reforming is quickly cooled and its reactivity is lowered, the equilibrium composition during reforming can be maintained. However, it is known that even if a gas containing a large amount of tar (such as crude COG) is reformed as a hydrocarbon, an equilibrium composition cannot be easily obtained. The results of the test results are used for the composition.

  The reformed gas supplied to the blast furnace shaft portion is set to a high pressure (1 MPa in this case) that can be supplied to the blast furnace shaft portion, and to a high temperature (800 ° C. or higher) for preventing the inside of the blast furnace from being cooled more than normal operation.

Hydrogen production during the generation amount of CO _2? CO2 ₂ is, ΔCO ₂ = ΔCO ₂ next be calculated by the _{formula, comp + ΔCO 2, heat +} ΔCO 2, cmp + ΔCO 2, ph + ΔCO 2, O2

In this equation,? CO2 2, _comp is feedstock hydrocarbon + additive compositions (such as water), represents the amount of CO ₂ corresponding to the CO ₂ concentration in the equilibrium composition at the temperature during modification. CO ₂ concentration in the crude COG and purification COG usually is close to zero, blast furnace feed gas CO ₂ concentration corresponds to CO ₂ flow rate generated in the substantially modified, i.e.,
[Blast furnace feed gas CO ₂ concentration] × [blast furnace feed gas flow rate]
Corresponding to

ΔCO _{2, heat} represents the amount of CO ₂ generated when the amount of heat directly supplied from the outside is generated among the various amounts of heat necessary for the reforming reaction (reaction exotherm, raw material preheating, etc.). Assuming that the required amount of heat is given by the combustion of natural gas, the amount of CO ₂ produced by the complete combustion of natural gas is given by the following equation.
ΔCO _{2, heat} = [Mole flow rate of natural gas consumed] × 1 mol _CO2 / mol _CH4
= [Required heat value] / ([Thermal efficiency η _heat ] × [Natural gas calorific value])
In the subsequent calculation, the calculation was performed with η _heat = 70%.

ΔCO _{2, cmp} is power for boosting the supply gas to the blast furnace, which must be supplied at a pressure (at least 0.2 MPa) that is sufficiently higher than the pressure in the blast furnace to be blown into the deep part of the blast furnace. Represents the amount of CO ₂ generated when it is generated. For example, in the case of using electric power generated by natural gas thermal power generation, the following CO ₂ generation amount discharged from a thermal power plant corresponding to power consumption is Give it as an expression.
ΔCO _{2, cmp} = [Mole flow rate of natural gas consumed] × 1 mol _CO2 / mol _CH4
= [Compressor power consumption for boosting] / ([shipping power efficiency η _el ] × [natural gas calorific value])
In the subsequent calculations, the compressor power consumption for boosting was calculated from the adiabatic compression power from normal pressure to 0.3 MPa, and calculated with η _el = 50%.

ΔCO _{2, ph} represents the amount of CO ₂ generated when generating the amount of heat necessary for preheating the supply gas to the blast furnace shaft. The gas supplied to the blast furnace shaft is usually preheated in many cases.
In subsequent calculations, ΔCO _{2, ph} was calculated in the same manner as ΔCO _{2, heat} .

ΔCO _{2, O 2} represents the amount of CO ₂ generated when the partial oxidation method is used for reforming the crude COG and oxygen is supplied in the form of pure oxygen to generate energy necessary for oxygen production. .
In the subsequent calculations, the electric power consumption at the time of oxygen production was set to 0.3 kWh / Nm ³ _{O 2,} and the calculation was performed in the same manner as ΔCO _{2, heat} .

According to the gas supply apparatus and method for a blast furnace of the present invention, carbon dioxide (CO ₂ ) generated in connection with the production of reducing gas for supplying a blast furnace shaft portion can be reduced. There is a great contribution to global warming countermeasures.

It is a schematic diagram of the 1st Embodiment of this invention. It is a schematic diagram of a carbonization furnace. It is a schematic diagram of an embodiment of a solid carbon separation mechanism. It is a schematic diagram of other embodiment of a solid carbon separation mechanism. It is a schematic diagram of other embodiment of a solid carbon separation mechanism. It is a schematic diagram of other embodiment of a solid carbon separation mechanism. It is a schematic diagram of embodiment of a partial oxidation reforming apparatus. It is a schematic diagram of other embodiment of a partial oxidation reforming apparatus. It is a schematic diagram of other embodiment of a partial oxidation reforming apparatus. It is a schematic diagram of the 2nd Embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  First, a basic overall configuration of a gas supply apparatus for a blast furnace according to the present invention will be described with reference to FIG. 1 schematically showing the first embodiment.

(overall structure)
The apparatus of the present invention is configured by connecting a coke oven 1, a carbonization furnace 2, a gas purification apparatus 3, a gas transfer apparatus 4, a preheating apparatus 5, a partial oxidation reforming apparatus 6, and a blast furnace 7 in this order from the upstream. . These devices can be connected using means such as a vent pipe. The coke oven 1 is accompanied by a moisture reducing means 1A for the generated coke oven gas (COG). For example, DAPS or SCOPE 21 for reducing the moisture of coal is used as the moisture reducing means 1A, and the coal dehydrated by the moisture reducing means 1A can be transported to the coke oven 1 by the coal conveying means 1B such as a belt conveyor. . The partial oxidation reformer is connected to a combustor 8 that supplies oxygen gas and combustible gas to burn.

(Coke oven)
As the coke oven 1, a general coke oven used in the steel industry or the like can be applied. Alternatively, if the system is smaller, coal may be continuously supplied to a heating furnace such as a kiln and heated to continuously generate COG.

(coal)
As the coal for generating COG, bituminous coal having a water concentration of 6 mass% or more and 15% or less, which is a coal as a raw material for coke suitable for steel refining by the blast furnace method, can be used. Alternatively, subbituminous coal or lignite may be used with emphasis on the amount of COG generated and quality. In order to prevent fire and scattering during mining, trading, transportation, storage, etc., these coals are generally held so as to maintain a predetermined moisture concentration or more until immediately before being supplied to the coke oven. Such a lower limit value of the predetermined moisture concentration should be 6% by mass. Moreover, since excessive moisture concentration in coal has a problem in terms of workability and work cost, the bituminous coal for iron making should be approximately 15% by mass or less.

(Coke oven gas (COG))
The COG generated during coal dry distillation contains aliphatic organic gas such as methane and ethane, aromatic hydrocarbon light oil gas such as benzene and toluene, tar gas mainly composed of aromatic heavy hydrocarbon, and the like. Further, water adhering to or contained in the coal to be used evaporates in the coke oven, so that COG generally contains water vapor.

  In the present invention, tar is suitable as the main substance thermally decomposed by the hydrogen generation reaction in the carbonization furnace 2. This is because when aromatic hydrocarbons, which are the main components of tar, are pyrolyzed, the remaining hydrocarbons that have released hydrogen easily grow as macromolecules composed of a two-dimensional aromatic polycyclic structure and have a diameter of several μm. This is because solid carbon particles of ˜several mm can be easily obtained, so that it is easy to hold the solid carbon in the carbonization furnace. By maintaining the generated solid carbon in the carbonization furnace for a certain period of time, hydrogen remaining in the solid carbon is gradually released as hydrogen gas, so that thermal decomposition is further promoted. On the other hand, aliphatic organic matter can also be thermally decomposed, but the solid carbon produced at that time generally has an amorphous structure in which diamond-like crystal structures are randomly arranged, and has a diameter of nanometer to submicron. Since solid carbon is generated as fine particles, it tends to be difficult to hold the generated solid carbon in the carbonization furnace or to separate and discharge the carbon from the carbonization furnace collectively. In addition, in the case of COG that unavoidably contains hydrogen sulfide gas at a high concentration, in the hydrogen generation reaction using a catalyst, the reaction rate of tar is generally higher than the reaction of aliphatic hydrocarbons. It is advantageous to pyrolyze tar. This is a feature of the process which is the subject of the present invention, in which the reaction rate is very high in the reforming reaction of aliphatic hydrocarbons in an ethylene plant using a raw gas having a low hydrogen sulfide concentration.

(COG moisture reduction means)
As the COG moisture reducing means 1A, the coal supplied to the coke oven can be dried in advance using a conventional DAPS or SCOPE21 furnace. If the dried coal is carbonized, the moisture in the generated COG can be reduced. Alternatively, in the case of a smaller system, coal may be stored in a coal warehouse for a long period of time such as several months or more, and moisture may be naturally evaporated during that time.

In the hydrogen generation reaction in the carbonization furnace 2 of the COG, in order to make thermal decomposition reaction such as tar excellent, it is preferable that the moisture (total moisture) concentration of coal is less than 4% by mass using moisture reducing means. The reason is due to the following findings. The inventors of the present invention supplied bituminous coal for a coke oven to a continuous coke oven and investigated the hydrogen generation reaction characteristics of the catalyst used in the thermal decomposition. The bituminous coal used at that time had a water content of 6 to 10% by mass at the same level as the actual machine. From these test results, under any test condition, generation of CO ₂ of about 20 mol% or more of the hydrogen generation amount was unavoidable with hydrogen generation, which was a problem from the viewpoint of CO ₂ saving. At one time, when bituminous coal was collected from a place that was easily exposed to the sun in the coal storage, and subjected to a similar test, the amount of generated CO _{2 was} reduced without significantly affecting the amount of hydrogen or CO generated. Of about 8 mol%. As a result of analyzing the remaining material of the supplied coal, it was found that the moisture content of this coal was 3 to 4% by mass, and the coal that had been naturally dried by the sun was applied to the test. In this way, the amount of CO ₂ produced during the hydrogen production reaction, which was generated in large quantities under the condition of 6% by mass, which is the lower limit value of coal moisture commonly used in actual machines, is reduced to less than 4% by mass of coal. The present inventors have found that this can be dramatically reduced.

Since the amount of CO ₂ generation can be reduced as the moisture in the coal is reduced, it is preferable to reduce the coal moisture as much as possible within the industrially possible range. For example, if DAPS is used, the moisture content of coal can be reduced to less than 1% by mass. Moreover, if it is a laboratory-level drying apparatus, the moisture content of coal can also be made almost zero. Accordingly, in the present invention, the water (total water) content is less than 4% by mass, for example, more than 0% by mass and less than 4% by mass, or 1% by mass to less than 4% by mass, or 2% by mass to less than 4% by mass. Alternatively, it is preferable to use coal adjusted to 1% by mass to 3% by mass, or 1% by mass to 2% by mass, particularly bituminous coal. However, more energy is generally consumed in order to reduce the moisture content of coal. In particular, (in the case of bituminous coal, about 2%) inherent moisture of coal in order to obtain a water concentration of less than, because must be heated coal above 105 ° C., the CO ₂ emissions in the coal drying process It is easy to increase. Therefore, the target moisture level of the coal, the CO ₂ generated with the energy consumption in the coal drying process, taking into account the advantages and disadvantages of the sum of the CO ₂ generated in the hydrogen production process, and should be decided.

  In some cases, COG is supplied to a coke oven without reducing the moisture of the coal, COG containing high-concentration water vapor generated in the coke oven is extracted, and an adsorbent such as high-temperature zeolite is passed through to pass through the COG. Moisture may be reduced.

  Next, the carbonization furnace 2 and the apparatus associated therewith in the present invention will be specifically described with reference to the embodiment illustrated in FIG.

(Carbonization furnace)
The carbonization furnace 2 reforms hydrocarbons (mainly tar gas) in the COG 14 continuously supplied from the coke oven 1 by pyrolysis, separates them into hydrogen gas and solid carbon, and brings the reformed gas 15 downstream. A furnace for discharging and storing the generated solid carbon. In order to maintain the furnace temperature at a temperature suitable for the pyrolysis reaction and supply reaction heat required for the hydrogen generation reaction mainly composed of pyrolysis, the carbonization furnace is supplied from the outside of the furnace body (or inside the furnace). A heat supply means 32 is provided for supplying heat from the furnace by providing a heating element or the like. As the heat supply means 32, general electric heater heating or direct fire heating can be used. The carbonization furnace 2 has a structure that avoids inflow of oxygen, air, water vapor, and the like, which are oxidation sources, into the carbonization furnace as much as possible in order to avoid combustion of the generated solid carbon there. Specifically, there is no provision of oxygen supply means for COG during the hydrogen generation reaction as in the partial oxidation method. Water vapor is not added to the COG other than that originally contained in the COG. The reaction temperature suitable for the thermal decomposition reaction of tar is generally in the range of 650 ° C. to 900 ° C. when a thermal decomposition catalyst is used. When COG is passed through the carbonization furnace below this temperature range, tar condensation occurs, and this condensate closes the space between the solid carbon fine particles. Therefore, in the present invention in which the solid carbon is held in the carbonization furnace, carbonization is easily performed. There are problems that cause furnace blockage. However, in the present invention, by keeping the inside of the carbonization furnace in a temperature range suitable for this thermal decomposition reaction, the solid carbon produced as a by-product by thermal decomposition is kept dry without condensing the tar contained in the COG. Can be maintained, and the decrease in air permeability due to the solid carbon can be minimized. Moreover, it is preferable that the pressure in a carbonization furnace is lower than the pressure in a coke oven. For example, since the coke oven internal pressure is usually higher than 10 Pa (gauge pressure), the COG ventilation can be maintained by setting the carbonization furnace internal pressure to 10 Pa (gauge pressure) or less. The lower limit of the pressure in the carbonization furnace does not exist in particular, but from the viewpoint of the pressure resistance of the carbonization furnace, the gas density in the carbonization furnace, the required vacuum apparatus capacity (this may be necessary in some cases), etc., −20000 Pa ( (Gauge pressure) or more.

  In the carbonization furnace 2, a solid carbon holding mechanism 30 configured by the granular material layer 13 held by the cage 12 is provided. The granular layer 13 is heated and kept at a temperature at which the thermal decomposition reaction suitably proceeds, and fresh COG directly sent from the coke oven 1 is always aerated, so that the COG thermal decomposition reaction promotion region (reaction region) ).

  The carbonization furnace inner wall 11 may have any shape as long as it has openings 16 and 17 in the vicinity of both upper and lower ends and the solid carbon holding mechanism 30 can be accommodated between these openings. The opening 16 is an inlet of the COG 14 to the carbonization furnace 2 and is connected to a vent pipe 33 connected to the coke oven 1 (FIG. 1). The opening 17 is an outlet of the reformed gas 15 from the carbonization furnace 2 and is connected to a vent pipe 34 connected to the gas purification device 3 (FIG. 1). The COG introduced into the carbonization furnace 2 flows from the lower part to the upper part in the direction of the arrow 18 in the direction of the arrow 18, undergoes a hydrogen generation reaction, and flows out as a reformed gas (primary reformed gas). The carbonization furnace inner wall 11 can have a shape such as a cylindrical shape or a rectangular duct shape, for example. Below, the square-shaped duct-shaped carbonization furnace inner wall 11 is demonstrated to an example.

  In the following description, “carbonization furnace thickness” corresponds to the minimum length of the representative length of the carbonization furnace inner wall 11 in the horizontal section, and “carbonization furnace width” is the representative of the carbonization furnace inner wall 11 in the horizontal section. It corresponds to the maximum length among the lengths. When the carbonization furnace inner wall 11 is a cylinder, the “width” and “thickness” of the carbonization furnace inner wall 11 may be replaced with “diameter”. The “carbonization furnace height” corresponds to the maximum height of the representative height of the space surrounded by the carbonization furnace inner wall 11.

  The material of the inner wall 11 of the carbonization furnace may be any material as long as it has a strength for holding a granular material such as a catalyst, heat resistance / corrosion resistance to a fluid involved in a catalytic reaction, and contamination resistance to a reaction product. Can be used. For example, carbon steel, stainless steel, nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium, titanium alloy and other metal materials, silica, alumina, silicon nitride, silicon carbide and other ceramic materials (those processed into bricks) Glass materials such as soda glass and fused silica can be used.

  The thickness of the carbonization furnace must be larger than the representative thickness of the built-in solid carbon holding mechanism 30, and the endothermic reaction heat generally generated in the hydrogen production reaction of hydrocarbons can be supplied by heat transfer from the outside. Must be thin enough. From these viewpoints, the thickness of the carbonization furnace can be 10 mm or more and 500 mm or less, and more preferably 50 mm or more and 200 mm or less. There is no particular restriction on the width of the carbonization furnace in terms of function. Based on the volume of the solid carbon holding mechanism to be held and the thickness of the carbonization furnace, it may be determined in terms of engineering in consideration of structural and strength constraints (for example, 5000 mm).

  The carbonization furnace height must be greater than the height of the solid carbon holding mechanism. On the other hand, the upper limit of the inner wall height of the carbonization furnace is not limited in terms of function, and may be determined in terms of engineering in consideration of structural and strength limitations (for example, 5000 mm).

(Solid carbon retention mechanism)
The solid carbon holding mechanism 30 is a mechanism that is provided in a reaction region (gas flow path) constituted by the carbonization furnace inner wall 11 and holds solid carbon so as to come into contact with the COG.

  As shown in FIG. 2, the solid carbon holding mechanism 30 is provided with a granular material layer 13 composed of a plurality of laminated granular materials in the flow path of the carbonization furnace 2, and in a space between adjacent granular materials. It can be a mechanism for holding solid carbon such as granular, powdery, or porous bodies. A single porous body can be used instead of the granular body. In order to hold the granular material layer 13 and the porous material at a fixed position in the flow path of the inner wall 11 of the carbonization furnace without swelling the opening 16 of the inlet and the opening 17 of the outlet, A cage 12 that prevents falling and has air permeability is provided.

  The cage 12 that supports the granular material layer 13 includes a net, punching metal, and a plurality of bars, in which the bars are arranged in parallel to each other so as to create a space between the bars, and both ends of the bars are fixed. Etc. can be used. Such a cage can also be used when a single porous body is used for the solid carbon holding mechanism. The material of the cage 12 is preferably a metal material having heat resistance, corrosion resistance, and strength. Examples of such metal materials include stainless steel, Ni alloys such as Hastelloy (registered trademark) and Inconel (registered trademark), titanium, titanium alloys, and the like.

  The property of the solid carbon is preferably a fine powder having a diameter of 0.1 mm or less, for example, from the viewpoint of ensuring the ease of dropping of particles and securing a large number of solid carbon nucleation sites during the pyrolysis reaction. Therefore, it may be a larger granular or porous body. As the material of the solid carbon, for example, commercially available carbon black powder or solid carbon produced as a by-product in the thermal decomposition reaction of hydrocarbons can be used.

  As the granular material, any material can be used as long as it has heat resistance, corrosion resistance, gas contamination resistance, and strength capable of retaining solid carbon under thermal decomposition reaction conditions. For example, ceramic particles such as silica glass and alumina, and copper and nickel particles can be used. The size of each granular material is not preferably extremely small so as not to impede gas permeability, and extremely coarse so that solid carbon can be retained. The thing with a typical dimension (for example, diameter) of 0.1-50 mm can be used.

  The thickness of the particulate layer in the ventilation direction can be in the range of 10 to 3000 mm from the viewpoint of ensuring air permeability and retaining solid carbon.

  When a single porous body is used for the solid carbon holding mechanism, a commercially available ceramic porous material having a porosity of about 20 to 80%, such as an alumina porous material, is used for the porous body. Can do.

(catalyst)
A pyrolysis catalyst can be disposed in the flow path formed by the carbonization furnace inner wall 11. The pyrolysis catalyst can be processed into a granular form and used as a granular body constituting the granular layer 13.

The pyrolysis catalyst is a composite oxide containing nickel, magnesium, cerium, and aluminum, and is a composite oxide not containing alumina. The composite oxide is NiMgO, MgAl ₂ O ₄ , CeO _2. A catalyst composed of the following crystalline phase can be used.

Specific examples of the catalyst that can be suitably used in the carbonization furnace of the present invention include, for example, an oxide containing nickel, magnesium, cerium, and aluminum, including at least one composite oxide, and alumina as a single compound. And a catalyst for reforming a tar-containing gas that does not contain hydrogen (WO 2010/134326 pamphlet). A suitable example of this composite oxide is composed of a crystal phase of NiMgO, MgAl ₂ O ₄ , and CeO ₂ , and among the crystal phases, the (200) plane of the NiMgO crystal phase determined by X-ray diffraction measurement is used. The crystallite size is 1 nm to 50 nm, the crystallite size of the (311) plane of the MgAl ₂ O ₄ crystal phase is 1 nm to 50 nm, and the crystallite size of the (111) plane of the CeO ₂ crystal phase is 1 nm to 50 nm. This catalyst contains a large amount of hydrogen sulfide generated when a carbonaceous raw material is thermally decomposed, and even if it is a condensed polycyclic aromatic-based tar-containing gas that easily causes carbon deposition, the accompanying heavy hydrocarbon such as tar Is converted to light hydrocarbons mainly composed of hydrogen, carbon monoxide, and methane, and when the catalyst performance deteriorates, at least one of water vapor and air is converted to the catalyst at a high temperature. By contacting, the carbon is removed from the catalyst and adsorbed sulfur, and the catalyst performance is restored to enable stable operation over a long period of time. Note that even a cheaper catalyst (Ni—MgO-based catalyst) manufactured under the same conditions as the above catalyst except that it does not contain CeO ₂ can achieve performance close to that of the above catalyst.

Although it has been known that this catalyst is suitably applied to steam reforming of tar, there has been no knowledge regarding the thermal decomposition reaction characteristics. When the present catalyst is brought into contact with a tar gas at about 800 ° C. under conditions where the supplied water is reduced as much as possible, the tar decomposes into hydrogen gas and solid carbon with almost no generation of CO or CO _2. I found. That is, the present catalyst can be suitably applied to promote the thermal decomposition reaction of tar, and the amount of CO and CO ₂ generated in hydrogen production can be reduced by adjusting the supply water concentration.

(Solid carbon separation mechanism)
The carbonization furnace 2 used in the present invention is for separating and removing a part or all of the solid carbon generated in the carbonization furnace 2 at a temperature corresponding to the furnace temperature from at least the reaction region in the carbonization furnace 2 and recovering it as solid carbon. It can have a solid carbon separation mechanism.

  For example, as shown in FIG. 3, a cage 12 for holding the granular material layer 13 in contact with the inner wall of the carbonization furnace 2, and a cage driving mechanism 20 for raising and lowering the granular material layer 13 by raising and lowering the cage 12. And a solid carbon separation mechanism 31 including the non-reacting part 35 for storing the separated solid carbon 25 can be used.

  In the carbonization furnace 2, a solid carbon holding mechanism 30 configured by the granular material layer 13 held by the cage 12 is provided. In addition, the carbonization furnace 2 includes a cage driving mechanism 20 for raising and lowering the cage 12 and a non-reacting portion 35 for storing the solid carbon 25 dropped from the holding mechanism 30 at the lower portion of the carbonization furnace 2. A mechanism 31 is provided. The granular layer 13 is heated and kept at a temperature at which the thermal decomposition reaction suitably proceeds, and fresh COG directly sent from the coke oven 1 is always aerated, so that the COG thermal decomposition reaction promotion region (reaction region) ). On the other hand, in the region where the solid carbon that has fallen is stored, the temperature is kept lower than the reaction temperature range, and the hydrogen generation reaction or oxidation is not performed by a means such as not supplying fresh COG by keeping air vented or keeping away from the catalyst. This is a non-reactive part 35 for preventing the reaction from proceeding.

  In the embodiment shown in FIG. 3, the solid carbon separation mechanism 31 includes a solid carbon holding mechanism 30, a cage driving mechanism 20, and a non-reaction unit 35, and the cage 12 is moved up and down by the cage driving mechanism 20. Thus, the granular material layer 13 on the cage 12 is moved up and down in the carbonization furnace inner wall 11. When the granular material layer 13 moves up and down, relative movement occurs between the granular materials, and the solid carbon deposited between the granular materials falls and is removed from the granular material layer and stored in the non-reacting portion 35. . The non-reacting part 35 may be arranged at the lower part in the carbonization furnace 2 or may be arranged below the carbonization furnace 2 as shown in FIG. In any case, as described above, the non-reacting portion 35 is a space that is separated from the reaction region in the carbonization furnace 4 and in which contact with the COG flow is suppressed. The cage drive mechanism 20 is equipped with a drive device 21, which is connected to the cage 12 via the conduction shaft 22, and the cage 12 and the entire granular material layer 13 are moved up and down by the raising and lowering operation of the drive device 21. . The drive device 21 can be a general drive device such as a mechanism using gears such as an air cylinder and a rack and pinion.

  At least a part of the conduction shaft 22 on the cage 12 side needs to be installed in the reaction region in the carbonization furnace 2. However, the drive device 21 can be provided outside the carbonization furnace 4. In this case, while a commercially available lifting device can be used, it is necessary to seal the portion where the conductive shaft 22 penetrates the wall of the carbonization furnace 2 with high-temperature packing or the like.

  When the cage 12 is raised, a part of the cage 12 may bite into the granular material layer 13 and solid carbon may not fall freely. Therefore, the cage 12 is only raised when the cage 12 is raised. It is preferable to drive even when the vehicle is lowered.

  In order to sufficiently perform the relative motion between the granular materials, and from the viewpoint of avoiding an increase in the size of the apparatus, the lifting / lowering stroke of the cage 12 is not less than 0.1 times the representative dimension (eg, diameter) of the outer surface of the granular material, and It can be 10 times or less, more preferably 1 time or more and 5 times or less.

  Since the required ascending force required to raise the granular material layer 13 together with the cage 12 is smaller as the ascending speed is smaller, a lower speed is preferable. As a result of the investigation by the present inventors, it has been found that the required ascending force when raising the granular material layer 13 together with the cage 12 at 10 mm / s needs to be twice that when raising at 1 mm / s. In addition, at a high ascending speed, the granular material tends to break. However, the difference in required ascending force between the case of raising at 1 mm / s and the case of raising at 0.5 mm / s is small, so it is not always necessary to make it slower than 1 mm / s. Further, even if the rising speed is 10 mm / s, it may be applied as long as the granular material does not break.

  The descending speed of the cage 12 is preferably large. In particular, if the cage 12 is lowered at a speed larger than the free fall rate of the catalyst at the lowermost end (eg, 100 mm / s), the granules are separated from the cage 12 and the constraint between the granules is reduced. This is preferable because the relative motion between the granular materials can be increased. However, there is no difference in the effect obtained even when the cage 12 is lowered at a speed extremely higher than the free fall speed of the granular material.

  When the granular material layer 13 rises, the reaction force acting between the granular materials becomes more isotropic in the granular material layer 13, and the same force as the vertical force for pushing up the granular material layer 13 is in the other direction. And a frictional force proportional to this force is generated between the catalysts. The downward component of this frictional force acts as a resistance force for pushing up the granular material layer. For example, when the aspect ratio (granular layer height / carbonization furnace thickness ratio) of the granular material layer 13 exceeds 2, the present inventors have shown that the push-up load increases rapidly and the granular material can be destroyed at the lowest stage. Found. Therefore, the lower the height of the granular material layer, the better, and the aspect ratio of the granular material layer (the granular material layer height / carbonization furnace thickness ratio) is preferably 2 or less. On the other hand, since there is a minimum necessary height in the granular material layer 13 in order to cause a relative motion between the granular materials by raising and lowering, the granular material layer height is an average length of three or more layers of the granular material. It is preferable that

The solid carbon 25 separated from the granular material layer 13 and stored in the non-reacting part 35 can be individually collected off-line. The recovered solid carbon can be used for industrial raw materials without being incinerated, thereby avoiding CO conversion or CO ₂ conversion. Compared with conventional methods, the amount of CO and CO ₂ generated during hydrogen production is reduced. It can be greatly reduced.

  The solid carbon separation mechanism is not limited to the above system, and any type of solid carbon separation mechanism can be applied as long as the solid carbon deposited in the granular layer can be removed during the modification of COG.

  For example, a fluidized bed type granular material layer 13 ′ shown in FIG. 4 can be applied to a solid carbon separation mechanism. The COG 14 introduced from the COG inlet 16 is vented upward into the granular material layer 13 ′ held by the cage 12 in the carbonization furnace 2. The COG 14 is thermally decomposed when passing through the granular material layer 13 ′ to generate the reformed gas 15 and solid carbon. At this time, if the flow rate of the gas flow 18 is set so as to exceed the fluidization flow rate of the granular material layer 13 ′, the granular material layer 13 ′ is fluidized to form a fluidized bed. If it sets so that the flow velocity of the gas flow 18 may not be excessive, a granular material can form a fluidized bed stably within a carbonization furnace, without scattering downstream. Solid carbon moves relatively freely in the fluidized bed. In general, the generated solid carbon particles having a smaller density and smaller diameter than the granular material are more easily moved downstream, and finally leave the fluidized bed to form a solid carbon flow 47, and the reformed gas outlet 17 flows out of the carbonization furnace 2. By providing the dust removing device 46 in the non-reaction zone downstream of the carbonization furnace, the solid carbon 25 can be recovered, and the solid carbon 25 can be separated and recovered online from the granular material layer 13 ′. The reformed gas 15 that has passed through the dust removal device 46 is supplied to the gas purification device 3 (FIG. 1).

  In order to fluidize the granules, there is an appropriate range for the diameter of the granules. For example, what is necessary is just to set to 50-300 micrometers. The diameter of the solid carbon produced in the carbonization furnace 2 is 50 μm at least at the initial stage of production, and is smaller than the diameter of the granular material. Therefore, the gas flow 18 that does not scatter the granular material and can scatter the solid carbon. There is a flow rate range of. This flow velocity range may be appropriately determined as a design condition of the apparatus, and may be, for example, 0.1 to 1 m / s.

  The cage 12 can be made of a porous material having a pore diameter smaller than the particle diameter. For example, a sintered body of fine alumina powder can be used.

  As the dust remover 46, for example, a bag filter, a scrubber, an electric dust collector or the like can be used.

  In this embodiment, some solid carbon, for example, grown and large particle size, is not scattered and retained in the fluidized bed, so the solid carbon retention mechanism 30 matches the granular layer. To do.

  An example of another solid carbon separation mechanism using a fluidized bed type granular material layer is shown in FIG. In the carbonization furnace 2 before the start of operation (before fluidization of the granular material layer), the granular material layer 13, the granular material recovery unit 55, and the granular material reflux path 56 having the same configuration as in FIG. 3 are arranged. Keep warm. When COG 14 is supplied to the granular material layer 13 in the carbonization furnace 2 and the flow rate of the gas flow 18 in the granular material layer 13 is set to a predetermined value or more, the granular material layer 13 is fluidized and the granular material is only fluidized. Rather, some of the particulates scatter downstream to produce a particulate flow 48. At the same time, part of the solid carbon produced in the fluidized bed is also scattered downstream to form a solid carbon stream 47. The particulate stream 48 and the solid carbon stream 47 enter the particulate collector 55 along with the gas stream 18. Since the granular material collector 55 has a large flow passage cross-sectional area downstream, and the flow velocity here is not so large as to raise the granular material, the granular material cannot pass through the granular material collector 55, Fall down. On the other hand, the solid carbon particles having a relatively small particle size and a small density can rise even if the gas flow has a low flow rate, and can flow out from the carbonization furnace 2 downstream. The solid carbon flowing out from the carbonization furnace 2 is collected by the dust remover 46 in the non-reaction region, and the solid carbon 25 can be separated and collected online from the granular material layer. For example, the dust remover 46 may be of the type described above with reference to FIG.

  The granular material dropped from the granular material collector 55 is deposited in the granular material reflux path 56 and falls in the granular material circulation path 56 by gravity, and returns to the fluidized granular material layer 13. That is, the granular material flows through the carbonization furnace.

  What is necessary is just to determine suitably the flow velocity range of the gas flow 18 for scattering a granular material and circulating in a carbonization furnace as a design condition of an apparatus, for example, can be 2-10 m / s.

  Alternatively, the mechanism shown in FIG. 6 can be applied to the solid carbon separation mechanism. The carbonization furnace 2 is provided with a granular material supply port 50 at the top and a granular material discharge port 51 at the bottom, and the granular material supplied from the granular material supply port 50 is laterally permeable in the carbonization furnace 2. The granular material layer 13 is formed. The inside of the carbonization furnace 2 is separated by the granular material layer 13 into the inlet side space 57 and the outlet side space 58. COG 14 flows into the inlet side space 57 and heat is generated when it passes through the granular material layer 13 as the gas flow 18. It is decomposed and flows into the outlet space 58 and flows out from the carbonization furnace 2 as the reformed gas 15.

  Since the solid carbon is deposited in the granular material layer 13 by pyrolysis, the granular material outlet 48 becomes a granular material flow 48 and a solid carbon flow 47 together with the solid carbon on which the granular material staying in the carbonization furnace 2 is accumulated for a predetermined time. 51 is discharged out of the carbonization furnace 2. The granular material discharge timing and the discharge speed are controlled by using the granular material discharging means 52. The discharge of the granular material may be intermittent or may be performed continuously. During the reforming operation, the same amount of granules as the amount of discharged granules is quickly filled from the granule supply port.

  Only solid carbon is separated and recovered from the mixture of the granular material and solid carbon discharged from the carbonization furnace 2. As a means for this, for example, a mixture of a granular material and solid carbon can be sieved using a sieve 53 to recover the small-diameter solid carbon 25. The solid carbon 25 recovered in this way naturally exists in the non-reacting part 35. The granular material 54 remaining on the sieve 53 after separating the solid carbon 25 is appropriately removed from the sieve.

  There are no particular restrictions on the granular material used in such a technique. As the particle size, for example, a particle size of 1 mm to 30 mm can be used. There are few restrictions on the flow velocity of the gas flow. For example, it can be set to 0.01 to 10 m / s.

  For supplying the granular material to the carbonization furnace 2, for example, a commercially available device (not shown) such as a belt conveyor or a screw feeder can be used.

  As the granular material discharging means 52, a commercially available device such as a rotary valve or a screw feeder can be used. The granular material discharging means 52 also has a function of preventing the granular material from falling more than necessary. Therefore, in the carbonization furnace 2 of FIG. 6, the region of the granular material surrounded by the cage 12 and the granular material discharging means 52 is the solid carbon holding mechanism 30.

(Gas purification equipment)
The gas purification device 3 is a device that removes at least high-boiling hydrocarbons such as tar, light oil, and benzene, and condensable gases such as moisture in the primary reformed gas discharged from the carbonization furnace 2. The removal of the condensable gas can be performed using a gas water-cooling device such as a scrubber or a distillation tower. If necessary, desulfurization treatment or deammonification treatment may be added. The high-temperature primary reformed gas from the carbonization furnace 2 is cooled to at least a temperature lower than the heat-resistant temperature of the gas transfer device 4, usually near normal temperature, by the treatment in the gas purification device.

(Gas transfer device)
The gas transfer device 4 is a device for sucking the primary reformed gas from the carbonization furnace 2 and increasing the pressure to send it to the partial oxidation reforming device 6. For this purpose, the gas transport device 4 needs a head that can maintain an inlet pressure of about −10 kPa and an outlet pressure of at least 0.2 MPa, generally about 0.2 to 1 MPa. A commercially available multistage axial flow compressor or the like can be used for the gas transfer device 4.

(Preheating device)
In 1 reformation gas reforming apparatus for the partial oxidation of 6, although performing heating vent gas by using a gas combustion using oxygen gas, the CO ₂ generation amount of reduction and the pure water MotoHara units viewpoint Therefore, the amount of oxygen supplied should be set as the minimum required source. For this reason, when the temperature of the primary reformed gas at room temperature is raised by gas combustion, the temperature of the aerated gas after the temperature rise often does not rise so as to promote methane decomposition by steam reforming. For this reason, the primary reformed gas is preheated by the preheating device 5 and then the temperature of the aerated gas is raised by gas combustion, whereby the aerated gas temperature after the temperature rise can be set to a suitable range. The preheating temperature of the primary gas is preferably about 300 to 800 ° C.

  Preheating of the primary reformed gas in the preheating device 5 can be performed, for example, by using a commercially available heat exchanger or by exchanging heat with a combustion gas generated in a separately provided combustion furnace.

(Partial oxidation reformer)
The partial oxidation reformer 6 increases the reaction rate by mixing the combustion gas with the primary reformed gas and raising the temperature of the primary reformed gas to a temperature significantly exceeding 1000 ° C. (eg, 1500 ° C.). This is an apparatus for generating hydrogen gas and CO gas by decomposing hydrocarbons such as methane in the primary reformed gas without using a catalyst based on chemical equilibrium. Any partial oxidation reforming apparatus 6 may be used as long as these requirements are satisfied.

  One embodiment of the partial oxidation reforming apparatus 6 that can be used in the present invention will be described with reference to FIG.

  The main body of the reformer 6 is a steel pressure-resistant reaction vessel whose inner surface is covered with a refractory material such as an alumina molding material or silica brick, and the primary reformed gas is introduced from a vent pipe 68 connected to one end. Then, the secondary reformed gas generated by the partial oxidation reforming reaction is exhausted through the vent pipe 69 from the other end.

  A combustor 61 is connected to the reformer 6. Oxygen gas and combustible gas are supplied to the combustor 61 from the supply pipes 62 and 63, and mixed and ignited in the combustor to generate combustion gas. Exhaust into the reformer 6. A commercially available axial flow burner or the like can be used as the combustor 61.

  Oxygen gas is preferably supplied in the form of pure oxygen in terms of the quality of the secondary reformed gas, but oxygen-containing gas such as air or oxygen-enriched air can also be supplied as oxygen gas.

The supply flow rate (mol flow rate) of the oxygen gas is 0.4 to 1.0 times the total value of the mol flow rates of carbon atoms contained in the hydrocarbons in the primary reformed gas and the hydrocarbons in the combustible gas (that is, O _{2 /} C = 0.4 to 1.0) is preferable in terms of secondary reformed gas quality, and O ₂ /C=0.4 to 0.7 is more preferable.

  As the combustible gas, natural gas, liquefied petroleum gas, refined COG, reformed COG, blast furnace gas (BFG), converter gas (LDG), or the like can be used. Also, liquid fuels such as naphtha, light oil, heavy oil, etc. can be used because they are not substantially different from combustible gas if they are made into mist and supplied into the combustor.

Of these combustible gases, it is particularly advantageous to use natural gas mainly composed of methane. Natural gas consumes hydrogen during combustion because the price per calorific value is low, the amount of CO ₂ generated per calorific value is relatively small, and the gas does not contain hydrogen gas (like COG). The advantage is that there is nothing to do.

  When supplying oxygen gas and combustible gas simultaneously, it is preferable that the supply flow rate (mol flow rate) of the combustible gas is 0.2 to 2 times the oxygen gas supply flow rate (mol flow rate). However, when oxygen gas is directly supplied to the primary reformed gas, it is difficult to separate the amount of primary reformed gas as combustion gas from the entire primary reformed gas. The supply flow rate may be less than 0.2 times the oxygen gas supply flow rate.

  Oxygen gas and combustible gas may be supplied to the combustor 61 at room temperature, or may be supplied after preheating. When supplying below the ignition temperature of combustible gas, it is necessary to provide an ignition means (not shown) in the combustor 61. By providing a pilot burner in the combustor 61 or preheating the reformer 6 and the combustor 61 to the ignition point or higher, a mixed gas of combustible gas and oxygen gas can be ignited.

  The gas temperature in the reformer 6 must be maintained at least 1000 ° C. or higher. The maximum temperature is preferably in the range of 1200 to 1800 ° C. If the temperature is less than this temperature range, the chemical reaction rate is too low, which causes a problem that the size of the reformer 6 as a reactor becomes enormous. If the temperature range is exceeded, the reformer inner wall temperature in contact with the gas is high. This is because there is a problem that the life of the inner surface constituting material is remarkably shortened.

  A thermometer 64 is provided in the partial oxidation reforming apparatus 6 to measure the temperature of the gas in the apparatus, and the temperature management of the gas in the apparatus can be performed based on the measured value. As the thermometer, an R-type or B-type thermocouple that is covered and protected with a heat-resistant material such as ceramic can be used.

  The capacity of the reformer 6 as a reactor is the apparent average residence time of gas ([reaction vessel volume] / ([processed primary reformed gas flow rate (standard state)] + [externally supplied combustion gas flow rate (normally Pressure, 100 ° C. conversion)])) is preferably from 30 seconds to 100 seconds. If it is less than this range, the reformer residence time of the processing gas is too short, causing a problem that the reaction does not proceed sufficiently. On the other hand, if this range is exceeded, the reformer residence time is excessive and a problem of requiring excessive equipment costs arises.

  A plurality of supply points of the combustion gas to the reformer 6 may be provided. For example, 4 to 8 supply ports can be provided at equal intervals in the circumferential direction of the apparatus. By doing in this way, mixing and reaction of combustion gas and primary reformed gas can be made more uniform.

  Another embodiment of the partial oxidation reforming apparatus 6 that can be used in the present invention will be described with reference to FIG.

  In the reformer 6 of this embodiment, an independent combustor is omitted, and oxygen gas and combustible gas are brought close to each other and supplied directly into the reformer. In this case, since the supplied oxygen gas and the combustible gas are close to each other, a combustion region 65 is formed in the vicinity of these gas supply ports. Here, the oxygen gas and the combustible gas are mainly combusted. The combustion region 6 plays the same role as the combustor. In some cases, oxygen gas and combustible gas may be supplied together into the reformer in advance.

  Also in this embodiment, the natural gas combustion gas can be supplied into the reformer by supplying the natural gas as the combustible gas, as in the embodiment described above with reference to FIG. It is also possible to use fuels other than the natural gas mentioned above. Moreover, you may provide multiple supply locations to the reformer 6 of oxygen gas and combustible gas, for example, can provide 4-8 places by the equal interval in the circumferential direction of an apparatus.

  Another embodiment of the partial oxidation reforming apparatus 6 that can be used in the present invention will be described with reference to FIG.

  Since the primary reformed gas is a kind of combustible gas, the primary reformed gas may be used as the combustible gas. In this case, the primary reformed gas is not necessarily separated from the combustor 61 ( 7) or the combustion region 65 (FIG. 8) does not need to be supplied, and only the oxygen gas may be supplied directly into the reformer 6. The space near the oxygen supply port in the reformer 6 becomes the combustion region 65, and this combustion region 65 plays substantially the same role as the combustor, as in the embodiment described above with reference to FIG. Fulfill.

  The primary reformed gas contains a large amount of hydrogen gas together with methane, and the combustion speed of hydrogen gas is generally faster than that of methane gas. Therefore, when oxygen is supplied into the reformer 6, The hydrogen in the next reformed gas is consumed to produce steam. When this gas is kept at a high temperature in the reformer 6, the generated steam steam reforms the methane to generate hydrogen, so that a primary reformed gas can be formed if a sufficient high temperature holding time can be set in the reformer 6. There is no problem in the decomposition of methane. However, if this holding time is insufficient, the secondary reformed gas is exhausted before the steam reforming of methane sufficiently proceeds, so that the hydrogen gas consumed by combustion cannot be recovered. Become. Therefore, when this embodiment is adopted, it is necessary to set the dimensions of the reformer 6 as a reaction vessel sufficiently large. On the other hand, as in the embodiment described with reference to FIGS. 7 and 8, when other than hydrogen gas (for example, natural gas) in the primary reformed gas is used as the combustible gas, the dimensions of the reformer 6 are assumed. However, since the hydrogen gas in the primary reformed gas remains in the secondary reformed gas, there are few such problems.

  Also in this embodiment, a plurality of supply points of the oxygen gas to the reformer 6 may be provided. For example, 4 to 8 supply ports can be provided at equal intervals in the circumferential direction of the apparatus.

  In any of the embodiments, the secondary reformed gas discharged from the partial oxidation reforming device 6 through the vent pipe 69 can be supplied to the blast furnace 7 from its shaft portion. The technology for supplying the secondary reformed gas (reducing gas) to the blast furnace is well known, and it is not necessary to explain in detail here.

  Next, a second embodiment of the present invention will be described with reference to the schematic diagram of FIG.

(overall structure)
The gas supply device to the blast furnace of the second embodiment includes a coke oven 1, a carbonization furnace 2, a gas purification device 3, a first gas transfer device 4 ′, a gas holder 9, a second gas transfer device 4 ″, and a preheating device. 5. The partial oxidation reforming device 6 and the blast furnace 7 are connected in this order from the upstream.

  Most of the second embodiment is common to the first embodiment, and only the difference from the first embodiment will be described.

  In the second embodiment, the primary reformed gas can be temporarily stored using the gas holder 9 as a buffer, and it is necessary to completely synchronize the production of the primary reformed gas and the production of the secondary reformed gas. There is no point in improving operability. The capacity of the gas holder 9 can be appropriately determined based on the operating conditions of the coke oven 1 and the blast furnace 7. Since the gas transfer devices 4 ′ and 4 ″ are provided on the inlet side and the outlet side of the gas holder 9, respectively, the optimum is obtained according to the characteristics of the operating conditions on the primary reformed gas production side and the secondary reformed gas production side. For example, since the first gas transfer device 4 ′ does not need to be boosted, an inexpensive device such as a Roots blower can be applied. The second transfer device 4 ″ includes a commercially available multi-stage. An axial compressor or the like can be used.

  The partial oxidation reforming apparatus 6 in the second embodiment shown in FIG. 10 is configured such that the combustor 8 in FIG. 1 is omitted (the type described with reference to FIG. 8). However, the gas supplied from the outside for supplying heat to the partial oxidation reforming apparatus 6 may supply oxygen and a combustible gas as combustion gas via a combustor (see FIG. 7). Alternatively, only oxygen gas may be supplied to the reformer 6 (see FIG. 9).

  The following examples further illustrate the present invention. However, the present invention is not limited to these examples.

  In the following example, crude COG obtained from a coke oven without using moisture reducing means, and reduced water crude COG obtained from a coke oven operating with reduced coal moisture using DAPS as moisture reducing means are used as raw material gas. Using. Table 1 shows the composition of the crude COG and reduced water crude COG.

[Comparative Example 1]
COG extracted from a coke oven using coal reduced in water by DAPS is treated in a carbonization furnace (no solid carbon separation mechanism) shown in FIG. 3 (temperature 700 ° C. or higher, using Ni—MgO-based catalyst). The next reformed gas was produced, purified through a scrubber, then pressurized (0.3 MPa), heated by indirect heating (800 ° C.) without partial oxidation, and supplied to the blast furnace shaft.

  In the water reduction treatment with DAPS, the coal moisture was reduced from 7% to 4%. The reduced water-treated coal was conveyed by a belt conveyor to a coal storage tank on the coke oven, and then transferred from the coal storage tank to the coke oven using a commercial charging vehicle. From the branch pipe provided in the coke riser pipe of the coke oven, about 800 ° C. water-reduced crude COG was sucked and extracted. The extracted water-reduced crude COG was supplied to the carbonization furnace through a vent pipe that kept the surroundings warm to suppress the temperature drop.

  The carbonization furnace had a ventilation cross section (horizontal plane) size of 120 mm × 900 mm and a ventilation direction height of 1200 mm. The granular material layer (catalyst layer) in the carbonization furnace was formed by holding the catalyst (diameter 15 mm) filled in the carbonization furnace with a saw-like cage at the bottom, and the height was 600 mm. During operation, the carbonization furnace maintained a temperature of 800 ° C. by external heating and produced 4 kg of coke in 2 hours of operation. Unless otherwise noted, the coke (solid carbon) deposited on the catalyst layer of the carbonization furnace was not separated or recovered from the catalyst layer during operation. When the coke (solid carbon) deposited on the catalyst layer was periodically separated and collected by moving the cage up and down, the operation time was 24 hours. The cage was moved up and down by attaching an air cylinder to the outer end of the conduction shaft passing through the carbonization furnace wall and reciprocating it (stroke 30 mm).

  A scrubber was used as a refining device, and most of tar and water in the reduced water crude COG were removed to produce a primary reformed gas. The gas temperature after passing through the scrubber was about 50 ° C. A branch for sampling was provided in the vent pipe on the outlet side from the scrubber, the primary reformed gas was extracted, and this was supplied to a commercially available gas chromatography apparatus for online component analysis. The analysis results are shown in Table 2 (“thermal decomposition composition of reduced water crude COG”).

When the amount of CO ₂ produced during hydrogen production is obtained by the complete combustion of natural gas, the amount of CO ₂ in the primary reformed gas, the theoretical reaction heat in the above pyrolysis reaction, and the energy required to raise and raise the pressure of the primary reformed gas Was calculated from the theoretical amount of CO _{2 in} the combustion exhaust gas. The calculation results are shown in Table 2 as ΔCO ₂ values. The obtained value (0.13%) is within the range of the allowable value (0.16 mol _{CO 2} / mol _{H 2} ) of the amount of CO ₂ produced during the production of hydrogen allowed when producing 1 mol of the hydrogen gas described above. The methane concentration is excessive, and this cannot be applied to the blast furnace shaft supply reducing gas as it is.

[Comparative Example 2]
A secondary reformed gas was produced by catalytic steam reforming using the primary reformed gas obtained by thermal decomposition of the reduced-water crude COG of Comparative Example 1 in which the amount of CO ₂ produced during hydrogen production was within the above-mentioned allowable range. In this case, the amount of CO ₂ produced at the time of hydrogen production in which the secondary reformed gas component composition and the primary and secondary reforming were combined was calculated by thermodynamic calculation assuming equilibrium conditions at the reaction temperature of the secondary reforming. For secondary reforming, the amount of each component produced during the 100% methane decomposition obtained by equilibrium calculation and the amount of each component produced are 70% of the values obtained during about 100% methane decomposition, respectively. The value obtained on the assumption that 30% methane in the reformed gas remains in the reformed gas was used (the methane decomposition (equilibrium) of about 100% is not always obtained in reforming, so methane Was also considered incompletely decomposed). Table 3 shows the amount of each component generated during 100% methane decomposition and the amount of each component generated during 70% decomposition.

  The gas component obtained by the steam reforming reaction or partial oxidation reaction (non-catalyzed) of hydrocarbons under conditions greatly exceeding 1000 ° C. is sufficient if the gas residence time in the reactor is sufficiently provided. It is known that the composition is substantially close to the equilibrium composition at the outlet temperature of the reactor), so by calculating the equilibrium component, the steam reforming reaction or partial oxidation reaction under conditions greatly exceeding 1000 ° C The reforming performance of (non-catalyst) can be evaluated.

The secondary reformed gas by catalytic steam reforming is heated (800 ° C.) and processed in a catalytic reactor (steam addition (S / C (number of H ₂ O molecules / C atom in hydrocarbon) Number) = 2, reaction temperature of 700 ° C. or higher, using Ni—MgO-based catalyst), the secondary reformed gas thus produced is once cooled, and after increasing the pressure (0.3 MPa), the temperature is increased by indirect heating ( 800 ° C.) and supplied to the blast furnace shaft.

The hydrogen production during CO ₂ generation amount, CO ₂ due to the energy supplied during 1 Tsugiaratame quality, CO ₂ in the above components, to increase the temperature-boosting theoretical reaction heat +2 reformation gas in the steam reforming reaction The required energy was calculated from the theoretical amount of CO _{2 in} the combustion exhaust gas when the required energy was obtained by complete combustion of natural gas. The results are shown in Table 3.

Equilibrium composition at 100% methane decomposition, with 70% modifier composition of the non-equilibrium, exceeds an allowable value when the hydrogen production CO ₂ generation amount the (0.16mol _CO2 / mol _H2), becomes excessive. Therefore, the secondary reformed gas in this case is not suitable as a reducing gas for supplying the blast furnace shaft. Furthermore, the moisture in the secondary reformed gas is excessive (allowable value: 10%), and as it is, it cannot be supplied to the blast furnace shaft portion, and a moisture removal step by cooling is essential. Therefore, even if catalytic steam reforming is performed after the primary reformed gas has been boosted and heated in advance, it is still necessary to cool the reformed gas once.

[Example 1]
Comparing secondary reformed gas component composition and primary / secondary reforming when secondary reformed gas is produced by partial oxidation using primary reformed gas by thermal decomposition of reduced water crude COG of Comparative Example 1 The amount of CO ₂ produced during hydrogen production was determined as described in Comparative Example 2. Table 4 shows the amount of each component generated during 100% methane decomposition and the amount of each component generated during 70% decomposition, together with the thermal decomposition composition of the reduced water COG (same as that shown in Table 2).

  The secondary reformed gas by partial oxidation is pressurized (0.3 MPa) and heated (500 ° C.), and processed by a partial oxidation reformer (addition of pure oxygen gas (in the primary reformed gas) The secondary reformed gas thus produced was supplied directly to the blast furnace shaft portion. As the combustible gas at the time of partial oxidation, primary reformed gas is used, and oxygen gas is supplied directly into the primary reformed gas (the oxygen gas supply molar flow rate is the primary reformed gas flow rate). 0.12 times greater).

The hydrogen production during CO ₂ generation amount, 1 CO ₂ due to the energy supplied to Tsugiaratame quality during the combustion exhaust gas theory when the energy required for manufacturing the CO _2, O ₂ in the component obtained by natural gas fired power CO ₂ amount was calculated the energy required for heating-boost 1 reformation gas from combustion exhaust gas stoichiometric amount of CO ₂ in the case of obtaining the complete combustion of natural gas. The results are shown in Table 4.

The efficiency of hydrogen production can be evaluated using the following hydrogen amplification factor.
[Hydrogen amplification factor] = [Hydrogen flow rate in product gas] / [Hydrogen flow rate in feed gas]
Table 4 also shows the hydrogen amplification factor obtained from this equation. The hydrogen amplification rate in this example is a value that greatly exceeds 2, and it can be said that the efficiency of hydrogen production is relatively high.

Both the equilibrium composition at the time of 100% methane decomposition and the non-equilibrium 70% reforming composition have a problem that the amount of CO ₂ produced during hydrogen production is sufficiently smaller than the allowable value (0.16 mol _{CO 2} / mol _{H 2} ). Further, the methane component is a trace amount compared to the crude COG, the hydrogen concentration is high, and the ratio of CO having reducibility is high among the remaining gas components. The H ₂ O concentration is also acceptable. Therefore, the secondary reformed gas produced in this example is suitable as a reducing gas for supplying the blast furnace shaft.

  Thermal calculation was performed, and it was also confirmed that the processing gas (secondary reformed gas) reached a maximum of 1500 ° C. by the partial oxidation reaction with the supplied oxygen amount.

Partial oxidation reforming apparatus as a reactor, for example, it was confirmed to be able to ensure a sufficient gas residence time by the capacity of 1 reformation gas 1 m ³ per 0.15 m ^3.

[Example 2]
The primary reformed gas was partially oxidized in the same manner as in Example 1 except that the solid carbon separation mechanism shown in FIG. 3 was added to the carbonization furnace and the operation time was 24 hours, thereby producing a secondary reformed gas. . Thermal decomposition composition of reduced-water crude COG obtained by on-line analysis of primary reformed gas after purification by scrubber, calculated amount of each component during 100% methane decomposition, and calculated value of each component generated during 70% decomposition Table 5 shows calculated values of the amount of CO ₂ produced during hydrogen production.

In a 24-hour operation, 40 kg of coke was produced in the carbonization furnace, 37 kg of which was removed from the catalyst layer online. By applying the solid carbon (coke) separation means, it was possible to prevent the carbonization furnace from being clogged and to carry out hydrogen production with reduced CO ₂ for a long time.

Both the equilibrium composition at the time of 100% methane decomposition and the non-equilibrium 70% reforming composition have a problem that the amount of CO ₂ produced during hydrogen production is sufficiently smaller than the allowable value (0.16 mol _{CO 2} / mol _{H 2} ). Further, the methane component is a trace amount compared to the crude COG, the hydrogen concentration is high, and the ratio of CO having reducibility is high among the remaining gas components. The H ₂ O concentration is also acceptable. Therefore, the secondary reformed gas produced in this example is also suitable as the reducing gas for supplying the blast furnace shaft.

[Comparative Example 3]
Refined COG (refined COG (aromatic compounds such as benzene, aromatic compounds), moisture, sulfides, and nitrides in the crude COG) is used to produce fuel gas, which is widely used as fuel in steelworks. The catalytic steam reforming) is described.

  Purified COG (primary reformed gas) from the gas holder is heated (800 ° C) and treated in a catalytic reactor (steam addition (S / C = 2), reaction temperature 700 ° C or higher, using Ni-MgO-based catalyst) Then, the secondary reformed gas is produced, cooled, and after pressure increase (0.3 MPa), the temperature is raised by indirect heating (800 ° C.) and supplied to the blast furnace shaft portion. Thus, the amount of each component generated during 100% methane decomposition of the secondary reformed gas and the amount of each component generated during 70% decomposition were determined by calculation.

Flue gas when the hydrogen production during CO ₂ generation amount, CO ₂ in the above components, the energy required for raising the temperature-boosting theoretical reaction heat +2 reformation gas in the steam reforming reaction is obtained by complete combustion of natural gas It was calculated from the medium theoretical CO ₂ amount.

  The results obtained are shown in Table 6.

Equilibrium composition at 100% methane decomposition, with 70% modifier composition of the non-equilibrium, exceeds an allowable value when the hydrogen production CO ₂ generation amount the (0.16mol _CO2 / mol _H2), becomes excessive. Therefore, the secondary reformed gas in this example is not suitable as a reducing gas for supplying a blast furnace shaft. Furthermore, the moisture in the secondary reformed gas is excessive (allowable value: 10%), and as it is, it cannot be supplied to the blast furnace shaft portion, and a moisture removal step by cooling is essential. Accordingly, even if the catalytic steam reforming is performed after the purified COG has been pressurized and heated in advance, it is necessary to once cool the reformed gas.

[Comparative Example 4]
The catalytic steam reforming of crude COG (COG obtained from a coke oven without using moisture reducing means, see Table 1 for composition) will be described.

The crude COG extracted from the coke oven (running for 24 hours) was treated with a catalytic reactor (800 ° C steam addition (S / C = 2), reaction temperature 700 ° C or higher, using Ni-MgO-based catalyst). The secondary reformed gas is produced, refined through a scrubber, boosted (0.3 MPa), heated by indirect heating (800 ° C.), and supplied to the blast furnace shaft. Secondary as described in Comparative Example 2 The amount of each component generated during 100% methane decomposition of the reformed gas and the amount of each component generated during 70% decomposition were calculated. Also, the hydrogen production during CO ₂ generation amount, CO ₂ in the above components, the combustion exhaust gas in the case of obtaining the energy required for raising the temperature-boosting theoretical reaction heat + reformed gas in the catalyst vapor reaction by complete combustion of natural gas It was calculated from the medium theoretical CO ₂ amount. The results obtained are shown in Table 7.

１００％メタン分解時の平衡組成、非平衡の７０％改質組成とも、水素製造時ＣＯ₂生成量が前記の許容値（０．１６ｍｏｌ_CO2／ｍｏｌ_H2）を超え、過大となった。よって、この例の２次改質ガスは高炉シャフト部供給用還元ガスとして好適でない。

Equilibrium composition at 100% methane decomposition, with 70% modifier composition of the non-equilibrium, exceeds an allowable value when the hydrogen production CO ₂ generation amount the (0.16mol _CO2 / mol _H2), becomes excessive. Therefore, the secondary reformed gas in this example is not suitable as a reducing gas for supplying a blast furnace shaft.

[Comparative Example 5]
The production of the reducing gas for supplying the blast furnace shaft by the partial oxidation reforming described in Patent Document 5 will be described.

In Patent Document 5, crude COG extracted from a coke oven is reformed by partial oxidation by using pure oxygen addition (crude COG itself is used as a combustible gas), and then purified by a scrubber to obtain a reducing gas for supplying a blast furnace shaft. Manufacture. As the composition of the reformed gas according to the indicated partial oxidation in Example of Patent Document 5, the CO ₂ generation amount and hydrogen production during CO ₂ generation amount calculated from the amount of hydrogen generated are shown in Table 8.

It can be seen that the amount of CO ₂ produced during hydrogen production exceeds the allowable value (0.16 mol _{CO 2} / mol _{H 2} ), which is extremely excessive.

[Comparative Example 6]
An example of the production of the primary reformed gas by thermal decomposition in the carbonized furnace of the reduced water crude COG and the production of the secondary reformed gas by catalytic steam reforming will be described.

  The production of the primary reformed gas was performed as described in Example 2. Next, the temperature of the primary reformed gas is raised (800 ° C.) and treated in a catalytic reactor (steam addition (S / C = 2, reaction temperature of 700 ° C. or higher, using Ni—MgO-based catalyst) to perform secondary reforming. The gas was manufactured, cooled once to room temperature, then pressurized (0.3 MPa), heated (800 ° C.), and supplied to the blast furnace shaft portion, as described in Comparative Example 2. The amount of each component produced during the 100% methane decomposition of the gas and the amount of each component produced during the 70% decomposition were calculated.

The amount of CO ₂ produced during hydrogen production is increased by the CO ₂ resulting from the energy supplied during the primary reforming, the CO _{2 in} the components, the theoretical reaction heat in the catalytic steam reforming reaction, and the temperature of the secondary reformed gas Was calculated from the theoretical amount of CO _{2 in} the combustion exhaust gas when the energy required for the combustion was obtained by complete combustion of natural gas.
Table 9 shows the obtained results.

Equilibrium composition at 100% methane decomposition, with 70% modifier composition of the non-equilibrium, exceeds an allowable value when the hydrogen production CO ₂ generation amount the (0.16mol _CO2 / mol _H2), becomes excessive. Therefore, the secondary reformed gas in this example is not suitable as a reducing gas for supplying a blast furnace shaft. Furthermore, the moisture in the secondary reformed gas is excessive, and as it is, it cannot be supplied to the blast furnace shaft portion, and a moisture removing step by cooling is essential. Therefore, even if catalytic steam reforming is performed after the primary reformed gas has been boosted and heated in advance, it is still necessary to cool the reformed gas once.

[Comparative Example 7]
The modification of the purified COG by partial oxidation will be described.

The purified COG (primary reformed gas) from the gas holder is increased in pressure (0.3 MPa) and heated (500 ° C.) and treated with a partial oxidation reformer as described in Example 1 (partial oxidation by addition of pure oxygen) ) To produce the secondary reformed gas, and the secondary reformed gas thus produced was directly supplied to the blast furnace shaft portion. As described in Comparative Example 2, the amount of each component generated during 100% methane decomposition of the secondary reformed gas and the amount of each component generated during 70% decomposition were determined by calculation. The hydrogen production during CO ₂ generation amount, secondary reformation amount of CO ₂ gas component, the combustion exhaust gas stoichiometric amount of CO ₂ in the case of the energy required for manufacturing the O ₂ obtained by natural gas fired power + purification COG heating Calculated from the theoretical amount of CO _{2 in the} flue gas when energy required for boosting is obtained by complete combustion of natural gas. Table 10 shows the obtained results.

Example 1 Although the equilibrium composition at the time of 100% methane decomposition and the non-equilibrium 70% reforming composition are within the allowable range (0.16 mol _CO2 / mol _H2 ), the amount of CO ₂ produced during hydrogen production The hydrogen amplification rate is significantly lower than 2, and the efficiency of hydrogen production is inferior to that of Examples 1 and 2 of the present invention. Further, regarding the product gas component, the hydrogen concentration is only slightly increased from the raw material gas (refined COG: hydrogen concentration 53%), which is inferior to the product gas in the present invention from the viewpoint of hydrogen purity.

From the above results, the typical conventional method cannot produce reducing gas under CO ₂ -saving conditions, and the superiority of the present invention is clear.

DESCRIPTION OF SYMBOLS 1 Coke oven 1A Water | moisture content reduction means 1B Coal conveyance means 2 Carbonization furnace 3 Gas purification apparatus 4, 4 ', 4 "Gas conveyance means 5 Preheating apparatus 6 Partial oxidation reforming apparatus 7 Blast furnace 8 Combustor 11 Carbonization furnace inner wall 12 Cage 13 , 13 'granular material layer 14 COG
DESCRIPTION OF SYMBOLS 15 Reformed gas 16, 17 Opening of carbonization furnace 18 Gas flow 20 Cage drive mechanism 21 Drive device 22 Conduction shaft 25 Solid carbon 30 Solid carbon retention mechanism 31 Solid carbon separation mechanism 32 Heat supply means 33, 34 Vent pipe 35 Non-reaction Part 46 Dust remover 47 Solid carbon flow 48 Granular flow 50 Granular supply port 51 Granular discharge port 52 Granular discharge means 53 Sieve 54 Granular material 55 Granular material collector 56 Granular material return path 57 Inlet side space 58 Outer side space 61 Burner 62 Oxygen gas supply pipe 63 Combustible gas supply pipe 64 Thermometer 65 Combustion area 68, 69 Ventilation pipe

Claims (12)

1) Coke oven provided with means for reducing moisture in coke oven gas by drying coal supplied to the coke oven in advance or by spontaneously evaporating the moisture of coal supplied to the coke oven in advance When,
2) a carbonization furnace that is maintained at 700 ° C. or higher and pyrolyzes coke oven gas generated from the coke oven;
3) a gas purifier for removing tar and at least a portion of moisture in the gas extracted from the carbonization furnace;
4) a gas transport device for boosting the gas after purification;
5) a gas preheating device;
6) a partial oxidation reformer equipped with means for mixing combustion gas with the gas for partial oxidation of the preheated gas;
7) a gas supply port to the blast furnace shaft,
8) A vent pipe connecting the above 1) to 7) in this order;
A gas supply device for a blast furnace, comprising: Means for mixing the preheated gas and the combustion gas in the partial oxidation reformer,
(A) a combustor for receiving supply of oxygen gas and combustible gas and supplying combustion gas generated by combustion of combustible gas to the partial oxidation reformer;
(B) a supply pipe for supplying oxygen gas and combustible gas separately or together into the partial oxidation reformer;
(C) a supply pipe for independently supplying oxygen gas into the partial oxidation reformer;
The gas supply device for a blast furnace according to claim 1, wherein the gas supply device is any one of the above.   The gas supply apparatus for a blast furnace according to claim 1 or 2, wherein the carbonizing furnace includes a catalyst layer filled to reform tar.   4. The gas supply apparatus for a blast furnace according to claim 3, wherein the carbonization furnace includes a solid carbon separation unit that removes solid carbon deposited between the catalysts in the catalyst layer online. 5.   The solid carbon separation mechanism is composed of a cage for holding the catalyst layer in contact with the inner wall of the carbonization furnace, and a drive mechanism for raising and lowering the catalyst layer by raising and lowering the cage. The gas supply apparatus for a blast furnace according to claim 4. The gas supply device for a blast furnace according to any one of claims 1 to 5, wherein the combustible gas is natural gas. A gas holder for temporarily storing the purified gas, and another gas conveying means for increasing the pressure of the gas from the gas holder, between the gas conveying device for boosting the gas after purification and the preheating device; The gas supply apparatus for a blast furnace according to any one of claims 1 to 6, characterized by: 1) Using the gas supply apparatus for a blast furnace according to any one of claims 1 to 6,
2) When the coke oven gas from the coke oven is vented to the carbonization furnace, the hydrogen concentration is increased by decomposing hydrocarbons in the coke oven gas into coke and hydrogen,
3) Tar and at least a part of moisture in the gas that has passed through the carbonization furnace are removed by the gas purification device to produce a first reformed gas,
4) pressurizing the first reformed gas with the gas transfer device;
5) Preheat the first reformed gas whose pressure has been increased with the preheating device,
6) Supplying the preheated first reformed gas to the partial oxidation reformer and supplying combustion gas to reform hydrocarbons in the first gas to increase hydrogen concentration Producing the second reformed gas,
7) Supplying the second reformed gas into the blast furnace from a gas supply port to the blast furnace shaft portion.
A method of supplying gas to a blast furnace.   The gas supply method to a blast furnace according to claim 8, wherein the first reformed gas is boosted to a pressure of at least 0.2 MPa by the gas transfer device.   10. The gas supply method to a blast furnace according to claim 8, wherein the first reformed gas is preheated to 300 to 800 ° C. in the preheating device. Combustion gas to the partial reformer,
(A) supplying oxygen gas and combustible gas as a combustion gas generated by supplying a combustor;
(B) supplying oxygen gas and combustible gas by supplying the gas into the partial reformer and generating combustion gas in the partial oxidation reformer;
(C) supplying oxygen gas by supplying it into the partial oxidation reforming apparatus and combusting a part of the first reformed gas;
The gas supply method to a blast furnace according to any one of claims 8 to 10, wherein The gas boosted by the gas transport device is temporarily stored in a gas holder, and the gas from the gas holder is further boosted by another gas transport means and then supplied to the preheating device. The gas supply method to the blast furnace as described in any one of 11.

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