CN116219101A - Carbonaceous mineral pellet reduction system and method - Google Patents

Carbonaceous mineral pellet reduction system and method Download PDF

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CN116219101A
CN116219101A CN202211717119.1A CN202211717119A CN116219101A CN 116219101 A CN116219101 A CN 116219101A CN 202211717119 A CN202211717119 A CN 202211717119A CN 116219101 A CN116219101 A CN 116219101A
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gas
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pyrolysis
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decarburization
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史雪君
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Beijing Huafu Engineering Co Ltd
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Beijing Huafu Engineering Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0046—Making spongy iron or liquid steel, by direct processes making metallised agglomerates or iron oxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0073—Selection or treatment of the reducing gases
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/50—Carbon oxides
    • B01D2257/504—Carbon dioxide

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  • General Life Sciences & Earth Sciences (AREA)
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  • Geochemistry & Mineralogy (AREA)
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  • Manufacture Of Iron (AREA)

Abstract

The invention provides a system and a method for reducing carbon-containing mineral pellets, and belongs to the technical field of metallurgy. The system comprises: the pyrolysis reduction reaction unit is used for carrying out pyrolysis on the carbon-containing mineral pellets and reducing the mineral pellets to obtain mixed gas and pyrolysis reduction products; the purification unit is used for purifying the mixed gas flowing out of the pyrolysis reduction reaction unit to obtain purified gas; the conversion unit is used for converting the purified gas to obtain converted gas; decarbonization unit for removing CO in the shift gas 2 Obtaining decarburization conversion gas; the heating unit is used for heating the decarburization conversion gas to obtain a furnace-entering reduction gas; the reaction unit comprises an outlet end and an inlet end, the pyrolysis reduction reaction unit is sequentially connected with the purification unit, the conversion unit, the decarburization unit and the heating unit through the outlet end, and the pyrolysis reduction reaction unit is connected with the purification unit through the inlet endIs connected with the outlet of the heating unit. The method is implemented based on the system. The method can fully utilize the carbon source and reduce the investment cost of the system.

Description

Carbonaceous mineral pellet reduction system and method
Technical Field
The invention relates to the technical field of metallurgy, in particular to a system and a method for reducing carbon-containing mineral pellets.
Background
The sponge iron is also called direct reduced iron, high-quality ore is adopted, oxidation-reduction reaction principle is utilized, the sponge iron is removed by a filtering type precipitation removing mode, and the water dissolved oxygen content of the sponge iron after water treatment for pipeline, boiler and circulating water dissolved oxygen corrosion can reach below 0.05 mg/L. Has low backwashing frequency, high compressive strength, no pulverization and hardening, and large specific surface area. High activity, good regeneration effect, etc. At present, most of the direct reduced iron is produced by a gas-based method worldwide, mainly natural gas is used as a gas-making raw material, water vapor or carbon dioxide is used as a conversion agent, and high-quality reducing gas is prepared in a reforming converter filled with a nickel-based catalyst; based on the characteristics of low energy source, rich coal and low oil shortage, the reducing gas is mostly prepared from coal. Coal gas is naturally feasible in principle, but the investment cost is huge. In addition, the coal gasification utilization efficiency is low, so that the pure reducing gas is recycled and used uneconomically.
Disclosure of Invention
In view of the above, the present invention provides a carbonaceous mineral pellet reduction system and method, which can fully utilize carbon sources and reduce investment costs of the system, thereby being more practical.
In order to achieve the first purpose, the technical scheme of the carbonaceous mineral pellet reduction system provided by the invention is as follows:
the invention provides a carbon-containing mineral pellet reduction system, which comprises a carbon source, iron ore powder and a binder, wherein the carbon-containing mineral pellet reduction system comprises:
the pyrolysis reduction reaction unit is used for carrying out pyrolysis on the carbon-containing mineral pellets and reducing the mineral pellets to obtain mixed gas and pyrolysis reduction products;
the purification unit is used for purifying the mixed gas flowing out of the pyrolysis reduction reaction unit to obtain purified gas;
the conversion unit is used for converting the purified gas to obtain converted gas;
a decarbonization unit for removing CO in the shift gas 2 Obtaining decarburization conversion gas;
the heating unit is used for heating the decarburization conversion gas to obtain a furnace-entering reducing gas, so that the temperature of the furnace-entering reducing gas is increased to a set temperature;
the reaction unit comprises an outlet end and an inlet end, the pyrolysis reduction reaction unit is sequentially connected with the purification unit, the conversion unit, the decarburization unit and the heating unit through the outlet end, and the pyrolysis reduction reaction unit is connected with an outlet of the heating unit through the inlet end.
The carbonaceous mineral pellet reduction system provided by the invention can be further realized by adopting the following technical measures.
Preferably, the pyrolysis reduction reaction unit is selected from a vertical type, a horizontal type, a rollaway type, a chain type, a mesh bag type, a rotary bottom type, a tunnel type and a rotary type pyrolysis reduction reaction unit.
Preferably, the carbonaceous mineral pellet reduction system further comprises:
and the heat recovery unit is used for recovering heat from the mixed gas flowing out of the pyrolysis reduction reaction unit.
Preferably, the carbonaceous mineral pellet reduction system further comprises:
and the oxygen supplementing unit is used for blowing oxygen into the furnace-entering reducing gas so that the temperature of the furnace-entering reducing gas is increased to a set temperature.
Preferably, the purification and heat recovery unit comprises a dust remover, a waste heat boiler, a compressor, a water washing tower and a desulfurization and decarbonization tower which are connected in sequence, and an outlet of the desulfurization and decarbonization tower is connected with the conversion unit.
Preferably, the conversion unit comprises a heat exchanger, a mixer, a conversion furnace, a heat exchanger, a water cooler and a gas-liquid separator which are sequentially connected, wherein a gas outlet of the conversion furnace is connected with a heating medium inlet of the heat exchanger through a pipeline, and a heating medium outlet of the heat exchanger is connected with the water cooler.
Preferably, the decarbonization unit comprises a decarbonization tower, a tower top cooler, a gas-liquid separator, a solution heat exchanger, a solution cooler, a reboiler and a regeneration tower which are sequentially connected with each other through pipelines, wherein a steam outlet of the waste heat boiler and a steam drum is connected with an inlet of the reboiler of the regeneration tower and an inlet of the shift reactor through a steam pipeline.
In order to achieve the second purpose, the technical scheme of the method for reducing the carbon-containing mineral pellets provided by the invention is as follows:
the carbon-containing mineral pellet reduction method provided by the invention is realized based on the carbon-containing mineral pellet reduction system provided by the invention, and comprises the following steps of:
obtaining the original material composition of the carbon-containing mineral pellets, wherein the original material composition comprises a carbon source, iron ore powder and a binder;
forming the original composition of the carbon-containing mineral pellets into carbon-containing mineral pellets;
the carbon-containing mineral pellets are subjected to pyrolysis reduction in the pyrolysis reduction reaction unit to obtain a reduction product and a mixed gas;
the mixed gas is purified by the purification unit to obtain purified gas, and CO in the purified gas 2 The mass percentage of the sulfur is less than or equal to 1 percent, and the total sulfur is less than or equal to 10mg/m 3 ；
The purified gas is converted by the conversion unit to obtain a converted gas in which H 2 The ratio of the mass percent of the catalyst to the mass percent of the CO is in the range of 4.6 to 1.5;
removal of CO from the shift gas 2 Obtaining decarburization shift gas in which H 2 The sum of the mass of the catalyst and the mass of CO accounts for more than 90 percent of the total mass of the total decarburization conversion gas, H 2 The ratio of the mass percent of (C) to the mass percent of CO is 4.6-1.5, the oxidation degree is less than 5%, and the CO is 2 The mass percentage of the total decarburization conversion gas is less than or equal to 1 percent of the total mass of the total decarburization conversion gas;
after the decarburization conversion gas is heated, obtaining a furnace-entering reducing gas, so that the temperature of the furnace-entering reducing gas is 700-850 ℃ when entering the pyrolysis reduction unit;
and the furnace-entering reducing gas is sent to the pyrolysis reduction reaction unit, so that the carbon-containing mineral pellets are finally reduced into sponge iron.
The reduction method of the carbon-containing mineral pellets provided by the invention can be further realized by adopting the following technical measures.
Preferably, after the decarburization conversion gas is heated, a reducing gas entering the furnace is obtained, so that the reducing gas entering the furnace has a temperature ranging from 700 ℃ to 850 ℃ when entering the pyrolysis reduction unit, and if the temperature of the decarburization conversion gas after being heated is lower than 700 ℃, the method further comprises the following steps:
and introducing oxygen into the heated decarburization and transformation gas, so that the temperature of the decarburization and transformation gas reaches 700-850 ℃.
Preferably, the step of recovering heat of the mixed gas is further included in the step of purifying the mixed gas by the purification unit.
The invention provides a reduction system and a method for carbon-containing mineral pellets, wherein a reducing gas production system is not required to be additionally arranged, the reduction of the mineral pellets is carried out by adjusting the hydrogen-carbon ratio after the circulation and conversion of top gas of CO gas generated in the process of reducing the mineral pellets by means of pyrolysis gas of the carbon-containing mineral pellets, so that the metallization rate of the mineral pellets exceeds 90%, the reduction of the mineral pellets without a reducing gas production system is realized, the carbon source is fully utilized, and the investment cost of the system is reduced.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a schematic diagram showing the connection relationship between units and the material change between the units in the carbonaceous mineral pellet reduction system according to embodiment 1 of the invention;
FIG. 2 is a schematic diagram showing the connection relationship between units and the material variation between units in the carbonaceous mineral pellet reduction system according to embodiment 2 of the invention;
fig. 3 is a flow chart of steps of a method for reducing carbonaceous mineral pellets according to an embodiment of the invention.
Detailed Description
In view of the above, the present invention provides a carbonaceous mineral pellet reduction system and method, which can fully utilize carbon sources and reduce investment costs of the system, thereby being more practical.
The inventor has made hard efforts, and found that,
the steel industry is the basis of national economy, and although the development is slow in recent years, the status of the steel industry is still free from movable shaking. In the steel yield of China, the iron-steel ratio is high, the electric furnace steel ratio is low, wherein 90% of the steel is produced by adopting the traditional blast furnace-converter flow, and ton of coarse steel CO 2 The discharge amount exceeds 2.15t. Coking, sintering and ironmaking processes in the iron and steel combined enterprises account for about 70% of total energy consumption, and sintering flue gas dioxin and NO in the sintering process x 、CO 2 、SO 2 And water pollutants and dust emission in dust emission and coking processes account for more than 50% of the total emission.
Compared with blast furnace ironmaking, the non-blast furnace process does not depend on coke, has wide energy selection range, and gets rid of the problem of the development of the iron and steel industry caused by the shortage of coking coal resources; meanwhile, the links of sintering and coking processes are omitted, the comprehensive energy consumption of the steel flow products is reduced, the environmental load is low, the flow is short, and the comprehensive utilization of resources can be realized. The non-blast furnace process has been developed in a long term abroad, and a modern non-blast furnace ironmaking industrial system mainly comprising direct reduction and melt reduction is gradually formed. The direct reduction method has two types, namely a gas-based method and a coal-based method, and the gas-based direct reduction method becomes a mainstream technology of a non-coking coal metallurgical process due to the advantages of high volume utilization rate, high thermal efficiency, high productivity and the like.
In the prior art, a pyrolysis furnace and a gas-based shaft furnace combined system and a method are provided, wherein the system consists of the pyrolysis furnace, a separation and purification system, a reforming and conversion system and the gas-based shaft furnace. The method is that pyrolysis oil gas (700 ℃ -900 ℃) generated by pyrolysis of raw material coal is treated by a separation and purification system and a reforming and conversion system to obtain reducing gas, and the reducing gas is introduced into a shaft furnace to reduce iron ore. The pyrolysis raw gas separation and purification system consists of a complex set of cooling, decoking and debenzolizing devices such as a primary cooling tower, a blower, an electrical tar precipitator, a debenzolizing tower and the like, and a small amount of coal tar is recovered after the pyrolysis raw gas is treated by the separation and purification system. Wherein the pyrolysis raw gas contains 5 to 15 percent of CH 4 And a certain amount of organic matters such as tar, etc., which are directly introduced into the shaft furnace as reducing gas, may have adverse effects on the normal operation of the shaft furnace; tar per se orPart of decomposition products of the furnace body can be adsorbed in the furnace body, so that the normal operation of the shaft furnace is affected; for CH with higher volume content 4 The carbon monoxide and the hydrogen are not fully converted into carbon monoxide and the hydrogen in the furnace, so that the reducibility of the gas is weakened, and the reduction of raw materials is not facilitated; the pyrolysis raw gas contains about 10 to 20 percent of H 2 O (g) and 5-10% CO 2 So that the oxidizing atmosphere (H) 2 O(g)+CO 2 ) The volume molar content of the (2) is higher than 5%, and the too high oxidation degree in the reducing gas is unfavorable for the reduction of the iron ore, and the reducing gas can be changed into high-quality reducing gas for reducing the iron ore after the content of the two is further reduced; the pyrolysis raw gas separation and purification system has complex procedures, large investment and high coal tar capturing and further utilization cost.
In the prior art, a device and a method for producing the gas-based shaft furnace reducing gas by adopting the fast pyrolysis are also provided. The device comprises a pyrolysis furnace and a gas-based shaft furnace; the pyrolysis furnace comprises a first cavity and a second cavity, pyrolysis raw gas is treated by the second cavity of the pyrolysis furnace and then is heated by the heating furnace, so that the pyrolysis raw gas can be introduced into the shaft furnace to reduce iron ore, a reforming furnace filled with a large amount of expensive catalyst is not required to be constructed, the system is simplified, and the maintenance cost is low. The full sensible heat of the pyrolysis raw gas at 700-900 ℃ is directly and fully utilized, and the energy utilization efficiency is obviously improved; the radiant tube is arranged in the second cavity to ensure proper oxidation pellet reduction, sponge iron reforming temperature and tapping clean pyrolysis gas temperature, so that the metallization rate of the sponge iron is high, the reforming conversion efficiency is greatly improved, and high-quality reducing gas meeting the requirements of the temperature and components of a downstream gas-based shaft furnace is also produced; the pyrolysis-free raw gas separation and purification system does not need to build a heating furnace or a reforming furnace, and the whole system is simple, small in investment and low in production cost. Although the full sensible heat of the pyrolysis raw gas at 700-900 ℃ is directly and fully utilized, the energy utilization efficiency is obviously improved, the raw gas generated in the rapid pyrolysis process of coal contains a large amount of dust and tar, and the whole system is not provided with a separation and purification system of the raw gas, so that the dust and the tar can block a pipeline and a nozzle at the inlet of the shaft furnace, and the normal operation of the shaft furnace is adversely affected.
In order to further describe the technical means and effects adopted by the invention to achieve the preset aim, the following description refers to the specific implementation, structure, characteristics and effects of a carbonaceous mineral pellet reduction system and method according to the invention in combination with the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.
The term "and/or" is herein merely an association relation describing an associated object, meaning that three relations may exist, e.g. a and/or B, specifically understood as: the composition may contain both a and B, and may contain a alone or B alone, and any of the above three cases may be provided.
Carbonaceous mineral pellet reduction system
Example 1
Referring to fig. 1, in the carbonaceous mineral pellet reduction system provided in embodiment 1 of the invention, the material composition of the carbonaceous mineral pellets includes a carbon source, iron ore powder and a binder, and the carbonaceous mineral pellet reduction system includes:
the pyrolysis reduction reaction unit is used for carrying out pyrolysis on the carbon-containing mineral pellets and reducing the mineral pellets to obtain mixed gas and pyrolysis reduction products;
the purification unit is used for purifying the mixed gas flowing out of the pyrolysis reduction reaction unit to obtain purified gas;
the conversion unit is used for converting the purified gas to obtain converted gas;
decarbonization unit for removing CO in the shift gas 2 Obtaining decarburization conversion gas;
the heating unit is used for heating the decarburization conversion gas to obtain a furnace-entering reducing gas, so that the temperature of the furnace-entering reducing gas is increased to a set temperature;
the reaction unit comprises an outlet end and an inlet end, the pyrolysis reduction reaction unit is sequentially connected with the purification unit, the transformation unit, the decarburization unit and the heating unit through the outlet end, and the pyrolysis reduction reaction unit is connected with the outlet of the heating unit through the inlet end.
According to the reduction system for the carbon-containing mineral pellets, provided by the invention, an additional reducing gas preparation system is not needed, the reduction of the mineral pellets is performed by adjusting the hydrogen-carbon ratio after the cycle and conversion of the top gas of the CO gas generated in the process of pyrolysis gas and reduction of the mineral pellets of the carbon-containing mineral pellets, so that the metallization rate of the mineral pellets exceeds 90%, the reduction of the mineral pellets without the reducing gas preparation system is realized, the carbon source is fully utilized, and the investment cost of the system is reduced. Wherein, the liquid crystal display device comprises a liquid crystal display device,
1) The reduction method of the carbon-containing mineral pellets does not need hydrogen production system, does not depend on coke, has wide energy selection range, low environmental load and short flow, effectively reduces the comprehensive energy consumption of the products of the steel flow, has the metallization rate of the produced sponge iron of more than or equal to 90 percent and the carbon content of 3.6 to 4.0 percent, and can output clean CO 2 A byproduct;
2) The steam generated by the heat recovered by the pyrolysis gas and the reducing gas is used for supplying heat for the solution regeneration and conversion reaction of the absorption tower, and the reduction of the carbon-containing mineral pellets without a gas making system is realized by combining the pyrolysis technology, the conversion technology and the heat recovery technology, so that the heat can be recovered, and the comprehensive utilization of heat energy resources is realized.
3) Instead of the existing shaft furnace process, the process does not depend on natural gas, and large coal gasification investment and cost are avoided;
4) The method is suitable for using lignite, long flame coal, weak-viscosity bituminous coal and non-viscosity bituminous coal with the largest reserve in China and low price, and raw coal sources are wide and the price is low;
5) The desulfurization can obtain solid products, which meet the requirements of criticism;
6) The waste heat recovery utilization rate is high, the steam yield is large, and the waste heat recovery device is self-provided.
7) The process is short, the unit investment/energy consumption/cost is low, the prepared sponge iron has stable chemical components and low impurity content, especially the harmful impurity S, P, has uniform granularity, can be used for producing a plurality of special steels which cannot be produced by scrap steel, is a high-quality source for smelting special steels, and can be used for powder metallurgy after secondary reduction.
Wherein the pyrolysis reduction reaction unit is selected from the group consisting of vertical, horizontal, rollaway nest type, chain type, mesh bag type, rotary bottom type, tunnel type and rotary type pyrolysis reduction reaction unit.
The purifying and heat recovering unit comprises a dust remover, a waste heat boiler, a compressor, a water washing tower, a desulfurizing and decarbonizing tower which are sequentially connected, and an outlet of the desulfurizing and decarbonizing tower is connected with the converting unit.
The conversion unit comprises a heat exchanger, a mixer, a conversion furnace, a heat exchanger, a water cooler and a gas-liquid separator which are sequentially connected, wherein a gas outlet of the conversion furnace is connected with a heating medium inlet of the heat exchanger through a pipeline, and a heating medium outlet of the heat exchanger is connected with the water cooler.
The decarbonization unit comprises a decarbonization tower, a tower top cooler, a gas-liquid separator, a solution heat exchanger, a solution cooler, a reboiler and a regeneration tower which are sequentially connected with each other through pipelines, wherein a steam outlet of the waste heat boiler and a steam drum is connected with an inlet of the reboiler of the regeneration tower and an inlet of the shift reactor through a steam pipeline.
Example 2
Referring to fig. 2, the difference between the carbonaceous mineral pellet reduction system provided in embodiment 1 of the invention and the carbonaceous mineral pellet reduction system provided in embodiment 2 of the invention is that the carbonaceous mineral pellet reduction system further comprises:
a heat recovery unit for recovering heat from the mixed gas flowing out of the pyrolysis reduction reaction unit;
and the oxygen supplementing unit is used for blowing oxygen into the furnace-entering reducing gas so that the temperature of the furnace-entering reducing gas is increased to a set temperature. In this case, the reduction temperature of the reducing gas can be increased, the reduction time of the mineral pellets can be shortened, and the metallization rate can be increased.
Reduction method for carbon-containing mineral pellets
Referring to fig. 3, the carbonaceous mineral pellet reduction method provided by the invention is realized based on the carbonaceous mineral pellet reduction system provided by the invention, and comprises the following steps:
step S1: obtaining the original material composition of the carbon-containing mineral pellets, wherein the original material composition comprises a carbon source, iron ore powder and a binder;
step S2: forming the original composition of the carbon-containing mineral pellets into carbon-containing mineral pellets;
step S3: carrying out pyrolysis reduction on the carbon-containing mineral pellets in a pyrolysis reduction reaction unit to obtain a reduction product and a mixed gas;
step S4: purifying the mixed gas in a purifying unit to obtain purified gas, wherein CO in the purified gas 2 The mass percentage of the sulfur is less than or equal to 1 percent, and the total sulfur is less than or equal to 10mg/m 3 ；
Step S5: after the purified gas is converted by the conversion unit, a conversion gas is obtained, wherein H is 2 The ratio of the mass percent of the catalyst to the mass percent of the CO is in the range of 4.6 to 1.5;
step S6: removal of CO from shift gas 2 Obtaining decarburization shift gas, H in the decarburization shift gas 2 The sum of the mass of the catalyst and the mass of CO accounts for more than 90 percent of the total mass of the total decarburization conversion gas, H 2 The ratio of the mass percent of (C) to the mass percent of CO is 4.6-1.5, the oxidation degree is less than 5%, and the CO is 2 The mass percentage of the total decarburization conversion gas is less than or equal to 1 percent of the total mass of the total decarburization conversion gas;
step S7: after the decarburization conversion gas is heated, obtaining a reduction gas entering the furnace, so that the temperature of the reduction gas entering the pyrolysis reduction unit is 700-850 ℃;
step S8: and feeding the reducing gas into a pyrolysis reduction reaction unit to reduce the carbon-containing mineral pellets into sponge iron.
According to the reduction method of the carbon-containing mineral pellets, provided by the invention, an additional reducing gas preparation system is not needed, the carbon source is fully utilized and the investment cost of the system is reduced by adjusting the hydrogen-carbon ratio to enter the reduction furnace for carrying out the reduction of the mineral pellets after the cycle and conversion of the top gas of the CO gas generated in the process of the pyrolysis gas of the carbon-containing mineral pellets and the reduction of the mineral pellets, so that the metallization rate of the mineral pellets exceeds 90 percent, and the reduction of the mineral pellets without the reducing gas preparation system is realized. Wherein, the liquid crystal display device comprises a liquid crystal display device,
1) The reduction method of the carbon-containing mineral pellets does not have hydrogen production system, does not depend on coke, has wide energy selection range, low environmental load and short flow, and effectively reducesThe comprehensive energy consumption of the products of the steel process is high, the metallization rate of the produced sponge iron is more than or equal to 90%, the carbon content is 3.6% -4.0%, and clean CO can be output 2 A byproduct;
2) The steam generated by the heat recovered by the pyrolysis gas and the reducing gas is used for supplying heat for the solution regeneration and conversion reaction of the absorption tower, and the reduction of the carbon-containing mineral pellets without a gas making system is realized by combining the pyrolysis technology, the conversion technology and the heat recovery technology, so that the heat can be recovered, and the comprehensive utilization of heat energy resources is realized.
3) Instead of the existing shaft furnace process, the process does not depend on natural gas, and large coal gasification investment and cost are avoided;
4) The method is suitable for using lignite, long flame coal, weak-viscosity bituminous coal and non-viscosity bituminous coal with the largest reserve in China and low price, and raw coal sources are wide and the price is low;
5) The desulfurization can obtain solid products, which meet the requirements of criticism;
6) The waste heat recovery utilization rate is high, the steam yield is large, and the waste heat recovery device is self-provided.
7) The process is short, the unit investment/energy consumption/cost is low, the prepared sponge iron has stable chemical components and low impurity content, especially the harmful impurity S, P, has uniform granularity, can be used for producing a plurality of special steels which cannot be produced by scrap steel, is a high-quality source for smelting special steels, and can be used for powder metallurgy after secondary reduction.
Wherein, after the decarburization conversion gas is heated, the reducing gas is obtained, so that in the step of leading the temperature of the reducing gas entering the pyrolysis reduction unit to be 700 ℃ to 850 ℃, if the temperature of the decarburization conversion gas is lower than 700 ℃ after being heated, the method further comprises the following steps:
oxygen is introduced into the heated decarburization and transformation gas, so that the temperature of the decarburization and transformation gas reaches 700-850 ℃.
Wherein, the step of purifying the mixed gas by the purifying unit further comprises the step of recovering the heat of the mixed gas.
Example 1
Referring to fig. 1 and 3, the carbonaceous mineral pellet reduction method provided in embodiment 1 of the invention includes the following steps:
step S1: and (3) forming: carbon source powder (high volatile matters (biomass, garbage, coal and the like)), iron ore powder (black ore, colored ore and the like) and a binder are mixed and molded to prepare carbon-containing mineral pellets, wherein the mass ratio of ore to carbon is as follows: 1.6.
step S2: pyrolysis/reduction: the carbon-containing mineral pellets enter a reaction furnace, the carbon-containing mineral pellets are pyrolyzed and reduced in the furnace, the pyrolysis and reduction temperature is 700 ℃ -1300 ℃ (a heating system of the reaction furnace can be gas heating or electric heating), and the reduction time is 20 min-240 min; the pyrolysis gas generated by pyrolysis of the reaction furnace and the gas generated by reduction of iron ore are mixed and then enter a purification and heat recovery unit.
Step S3: purifying and heat recovery: after dust removal, the pyrolysis gas and the reducing gas which are discharged from the reducing furnace enter a waste heat boiler to recover heat energy of the pyrolysis gas to generate medium-pressure steam for regeneration of a solution of a regeneration tower, the pyrolysis gas which is cooled to below 50 ℃ by the waste heat boiler is pressurized to 0.2-0.8 MPa by a compressor, and then enters a mixed gas purifying unit; purified mixed gas H 2 S content of 0.03ppm, total sulfur content of less than 0.05ppm, CO 2 The content of (2) was 20ppm.
Step S4: and (3) transformation: after the heat exchange of the purified mixed gas by the shift gas generated by the shift furnace, the mixed gas is heated to 180 ℃ to 260 ℃ from 40 ℃ below zero and then mixed with steam from a steam boiler to enter a shift process, the shift temperature is 300 ℃ to 400 ℃, and H in the shifted reducing gas 2 The ratio of the CO to the water is 4.6-1.5; the temperature of the conversion gas is reduced from 400 ℃ to 300 ℃ to 260 ℃ to 180 ℃, then the temperature is reduced to about 40 ℃ by a water cooler, and the conversion gas enters a gas-liquid separator to separate liquid and then enters a decarburization unit;
step S5: decarbonization: the transformed gas enters a decarbonization unit to remove CO in the mixed gas 2 CO after being treated by a decarbonization tower 2 Is 20ppm;
step S6: heating: the decarbonizing gas is heated to 700-850 ℃ by a heating system and then enters a reaction furnace to reduce mineral pellets.
Example 2
Referring to fig. 2 and 3, the method for reducing carbon-containing mineral pellets provided in embodiment 2 of the present invention includes the following steps:
step S1: and (3) forming: carbon source powder (high volatile matters (biomass, garbage, coal and the like)), iron ore powder (black ore, colored ore and the like) and a binder are mixed and molded to prepare carbon-containing mineral pellets, wherein the mass ratio of ore to carbon is as follows: 1.6;
step S2: pyrolytic reduction reaction: the carbon-containing mineral pellets enter a reaction furnace, the carbon-containing mineral pellets are pyrolyzed and reduced in the furnace, the pyrolysis and reduction temperature is 700 ℃ -1300 ℃ (a heating system of the reaction furnace can be gas heating or electric heating), and the reduction time is 20 min-240 min; the pyrolysis gas generated by pyrolysis of the reaction furnace and the gas generated by reduction of the iron ore are mixed and then enter a purification and heat recovery unit;
step S3: purifying and heat recovery: after dust removal, the pyrolysis gas and the reducing gas which are discharged from the reducing furnace enter a waste heat boiler to recover heat energy of the pyrolysis gas to generate medium-pressure steam for regeneration of a solution of a regeneration tower, the pyrolysis gas which is cooled to below 50 ℃ by the waste heat boiler is pressurized to 0.2-0.8 MPa by a compressor, and then enters a mixed gas purifying unit; purified mixed gas H 2 S content of 0.03ppm, total sulfur content of less than 0.05ppm, CO 2 Is 20ppm;
step s4: and (3) transformation: after the heat exchange of the purified mixed gas by the shift gas generated by the shift furnace, the mixed gas is heated to 180 ℃ to 260 ℃ from 40 ℃ below zero and then mixed with steam from a steam boiler to enter a shift process, the shift temperature is 300 ℃ to 400 ℃, and H in the shifted reducing gas 2 The ratio of the CO to the water is 4.6-1.5; the temperature of the conversion gas is reduced from 400 ℃ to 300 ℃ to 260 ℃ to 180 ℃, then the temperature is reduced to about 40 ℃ by a water cooler, and the conversion gas enters a gas-liquid separator to separate liquid and then enters a decarburization unit;
step S5: decarbonization: the transformed gas enters a decarbonization unit to remove CO in the mixed gas 2 CO after being treated by a decarbonization tower 2 Is 20ppm;
step S6: heating: heating the decarbonizing gas to 700-850 ℃ through a heating system, and then entering a reaction furnace to reduce mineral pellets;
step S7: oxygen supplement: if the temperature of the converted gas after being heated by the heating system is lower than 700 ℃ after entering the reaction furnace, a small amount of oxygen (20 Nm) needs to be blown into the reducing gas 3 /tDRI～50Nm 3 Dri) to increase the reduction temperature of the shift gas, accelerate the reduction of mineral pellets, and increase the metallization rate.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (10)

1. A carbonaceous mineral pellet reduction system, wherein the composition of matter of the carbonaceous mineral pellets comprises a carbon source, iron ore fines, and a binder, the carbonaceous mineral pellet reduction system comprising:
the pyrolysis reduction reaction unit is used for carrying out pyrolysis on the carbon-containing mineral pellets and reducing the mineral pellets to obtain mixed gas and pyrolysis reduction products;
the purification unit is used for purifying the mixed gas flowing out of the pyrolysis reduction reaction unit to obtain purified gas;
the conversion unit is used for converting the purified gas to obtain converted gas;
a decarbonization unit for removing CO in the shift gas 2 Obtaining decarburization conversion gas;
the heating unit is used for heating the decarburization conversion gas to obtain a furnace-entering reducing gas, so that the temperature of the furnace-entering reducing gas is increased to a set temperature;
the reaction unit comprises an outlet end and an inlet end, the pyrolysis reduction reaction unit is sequentially connected with the purification unit, the conversion unit, the decarburization unit and the heating unit through the outlet end, and the pyrolysis reduction reaction unit is connected with an outlet of the heating unit through the inlet end.
2. The carbonaceous mineral pellet reduction system of claim 1, wherein the pyrolytic reduction reaction unit is selected from the group consisting of vertical, horizontal, race, chain, mesh bag, rotary bottom, tunnel, rotary pyrolytic reduction reaction units.
3. The carbonaceous mineral pellet reduction system according to claim 1, further comprising:
and the heat recovery unit is used for recovering heat from the mixed gas flowing out of the pyrolysis reduction reaction unit.
4. The carbonaceous mineral pellet reduction system according to claim 1, further comprising:
and the oxygen supplementing unit is used for blowing oxygen into the furnace-entering reducing gas so that the temperature of the furnace-entering reducing gas is increased to a set temperature.
5. The carbonaceous mineral pellet reduction system according to claim 3, wherein the purification and heat recovery unit comprises a dust remover, a waste heat boiler, a compressor, a water washing tower, a desulfurization and decarbonization tower, which are sequentially connected, and an outlet of the desulfurization and decarbonization tower is connected to the conversion unit.
6. The carbonaceous mineral pellet reduction system according to claim 1, wherein the shift unit comprises a heat exchanger, a mixer, a shift converter, a heat exchanger, a water cooler, and a gas-liquid separator which are sequentially connected, a gas outlet of the shift converter is connected to a heating medium inlet of the heat exchanger through a pipe, and a heating medium outlet of the heat exchanger is connected to the water cooler.
7. The carbonaceous mineral pellet reduction system according to claim 5, wherein the decarbonization unit comprises a decarbonization tower, a tower top cooler, a gas-liquid separator, and a solution heat exchanger, a solution cooler, a reboiler and a regeneration tower connected in sequence by pipelines, wherein steam outlets of the waste heat boiler and the steam drum are connected with an inlet of the reboiler of the regeneration tower and an inlet of the shift reactor by steam pipelines.
8. A method for reducing carbonaceous mineral pellets, characterized in that it is realized based on the carbonaceous mineral pellet reduction system according to any one of claims 1 to 7, comprising the steps of:
obtaining the original material composition of the carbon-containing mineral pellets, wherein the original material composition comprises a carbon source, iron ore powder and a binder;
forming the original composition of the carbon-containing mineral pellets into carbon-containing mineral pellets;
the carbon-containing mineral pellets are subjected to pyrolysis reduction in the pyrolysis reduction reaction unit to obtain a pyrolysis reduction product and a mixed gas;
the mixed gas is purified by the purification unit to obtain purified gas, and CO in the purified gas 2 The mass percentage of the sulfur is less than or equal to 1 percent, and the total sulfur is less than or equal to 10mg/m 3 ；
The purified gas is converted by the conversion unit to obtain a converted gas in which H 2 The ratio of the mass percent of the catalyst to the mass percent of the CO is in the range of 4.6 to 1.5;
removal of CO from the shift gas 2 Obtaining decarburization shift gas in which H 2 The sum of the mass of the catalyst and the mass of CO accounts for more than 90 percent of the total mass of the total decarburization conversion gas, H 2 The ratio of the mass percent of (C) to the mass percent of CO is 4.6-1.5, the oxidation degree is less than 5%, and the CO is 2 The mass percentage of the total decarburization conversion gas is less than or equal to 1 percent of the total mass of the total decarburization conversion gas;
after the decarburization conversion gas is heated, obtaining a furnace-entering reducing gas, so that the temperature of the furnace-entering reducing gas is 700-850 ℃ when entering the pyrolysis reduction unit;
and the furnace-entering reducing gas is sent to the pyrolysis reduction reaction unit, so that the carbon-containing mineral pellets are finally reduced into sponge iron.
9. The method for reducing carbon-containing mineral pellets according to claim 8, wherein after the decarburization shift gas is heated, a furnace-entering reducing gas is obtained, so that the furnace-entering reducing gas has a temperature ranging from 700 ℃ to 850 ℃ when entering the pyrolysis reduction unit, and if the temperature of the decarburization shift gas after being heated is lower than 700 ℃, the method further comprises the following steps:
and introducing oxygen into the heated decarburization and transformation gas, so that the temperature of the decarburization and transformation gas reaches 700-850 ℃.
10. The method for reducing carbon-containing mineral pellets according to claim 8, further comprising a step of recovering heat of the mixed gas during the step of obtaining the purified gas after the purification unit purifies the mixed gas.
CN202211717119.1A 2022-12-29 2022-12-29 Carbonaceous mineral pellet reduction system and method Pending CN116219101A (en)

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