CN203513711U - System for producing gas-base direct reduction iron from coke-oven gas - Google Patents

Abstract

The utility model relates to a system for producing gas-based direct reduced iron by using coke oven gas. The system for producing gas-based direct reduced iron using coke oven gas includes a purifier, a first fine desulfurization tower, a catalytic converter, a gas mixer, a shaft furnace, a cooler, a scrubber, a second fine desulfurization tower, a decarburizer, heater. The system for producing gas-based direct reduced iron using coke oven gas provided by the utility model is to use coke oven gas to produce synthesis gas through catalytic conversion method, and then to produce direct reduced iron system, and to achieve the follow-up Conversion catalyst requirements, and then burn with oxygen to provide heat for subsequent conversion reactions, and control various process indicators to make the synthesis gas meet the requirements of shaft furnace gas-based direct reduced iron. This system has the characteristics of easy control, simple structure, and low energy consumption. , especially suitable for enterprises with air separation and pure oxygen.

Description

A system for producing gas-based direct reduced iron using coke oven gas

technical field

The utility model relates to a system for producing gas-based direct reduced iron by using coke oven gas, which belongs to the technical field of direct reduced iron production.

Background technique

Direct reduced iron (DRI), also known as sponge iron, is a kind of metallic iron obtained without blast furnace smelting. The process of producing DRI is called non-blast furnace ironmaking process. The production process of DRI is divided into two types: coal-based and gas-based. Among them, the gas-based method currently accounts for 90% of the output of DRI. The typical processes are the tank method (HYL method) and the shaft furnace method (Midrex method). The shaft furnace method uses a vertical moving bed reduction reactor, which is mainly divided into two parts: Reduction zone, where reducing gas circulates at high temperature, hydrogen and carbon monoxide above 800°C reduce iron oxide to generate DRI, hydrogen and carbon monoxide generate water and carbon dioxide; and a cold zone located at the lower part of the reduction zone, before DRI is discharged, The DRI in the cooling zone is cooled to ambient temperature by a cooling gas containing hydrogen and carbon monoxide circulating in a cooling circuit.

The reducing agent used in the gas-based method is mainly natural gas, which is produced by steam reforming or partial oxidation to produce syngas CO+H ₂ , but the price of natural gas in China is expensive, and the price of natural gas in some eastern coastal areas has reached 5 yuan/m ³ , while large-scale coal gasification The price of the refined synthesis gas produced is also more than 0.8 yuan/m ³ , so finding a cheap reducing gas raw material channel is a problem that must be faced when vigorously developing DRI production in China.

China has a large amount of coke oven gas (COG) resources, except for a part used for power generation, pure hydrogen production, heating fuel and methanol production, about one-third of the resources are put into the torch and burned. And there is a large amount of surplus gas with low calorific value in iron and steel enterprises, such as blast furnace gas and converter gas that have been vented. With the advancement of energy-saving technology, double preheating technology of hot blast stoves and regenerative heating furnace technology are constantly emerging, and a large amount of low calorific value gas is used, and the surplus of coke oven gas is beyond doubt. Taking Angang Steel as an example, it is predicted that in 2006, the surplus of blast furnace gas will be 460,000 m ³ /h, and the surplus of coke oven gas will be 40,000-60,000 m ³ /h.

The main components of coke oven gas are H ₂ (55-66%), CH ₄ (18-26%), CO (6-8%), and the rest are carbon dioxide, nitrogen, hydrocarbons above C ₂ and a small amount of oxygen and sulfur impurities. Premium DRI reducing gas.

Chinese patent application CN100523228C discloses a method for producing sponge iron by using coke oven gas to produce reducing gas, which is to add a certain amount of CO ₂ after desulfurization of coke oven gas, and use the conversion of CH ₄ and CO ₂ in coke oven gas To produce high-quality reduced iron synthesis gas, a part of the reduction tail gas is used as fuel. Due to the addition of CO ₂ and the endothermic reaction with CH ₄ , a large amount of coke oven gas needs to be burned to supply reaction heat outside, and the heating efficiency is low. The flue gas energy loss is large. Compared with the direct heat generation by adding O ₂ oxidation, the equipment investment is large, the heat loss is large, and the energy consumption is high. The additional CO ₂ also increases energy consumption and separation costs.

Chinese patent application CN101392192B discloses a coke oven gas carbon dioxide conversion and gas-based shaft furnace direct reduction iron production method. In this application, the coke oven gas is deeply purified and desulfurized, and oxygen, carbon dioxide and water vapor are added as gas conversion agents. Too much water vapor is added to the gas, and after conversion, it needs to be cooled to 40°C for dehydration treatment, and then the temperature is raised to feed into the shaft furnace. The process of cooling and heating the high-temperature syngas results in high energy consumption.

Utility model content

In order to solve the above-mentioned technical problems, the purpose of this utility model is to provide a system for producing gas-based direct reduced iron, which uses coke oven gas to produce synthesis gas through catalytic conversion, and then produces direct reduced iron. It is easy to control, Features such as simple structure.

In order to achieve the above purpose, the utility model provides a system for producing gas-based direct reduced iron by using coke oven gas, which is a system for producing gas-based direct reduced iron by using coke oven gas catalytic conversion. The direct reduction iron system includes a purifier, the first fine desulfurization tower, a catalytic converter, a gas mixer, a shaft furnace, a cooler, a scrubber, a second fine desulfurization tower, a decarbonization tower, and a heater, among which:

The purifier is provided with a coke oven gas input port, and its outlet is connected to the first fine desulfurization tower;

The first fine desulfurization tower is provided with a CO ₂ /H ₂ O inlet, its outlet is connected to the catalytic converter, and other gas input pipes are provided on the connecting pipe between the first fine desulfurization tower and the catalytic converter;

The gas mixer is respectively provided with an oxygen-containing gas inlet and a CO ₂ /H ₂ O inlet, and its outlet is connected to the catalytic converter;

The outlet of the catalytic converter is connected with the shaft furnace;

The shaft furnace is provided with a pellet inlet, a top gas outlet and a reduced iron outlet, which are connected to the cooler through a top gas outlet;

The cooler is connected to the scrubber;

The scrubber is connected to the second fine desulfurization tower;

The second fine desulfurization tower is connected with the decarburization tower;

The decarbonization tower is provided with a reducing gas outlet and _{a CO} outlet, and is connected to the heater through the reducing gas outlet;

The heater is connected to the shaft furnace.

According to a specific embodiment of the present utility model, preferably, the shaft furnace is a Midrex high-temperature gas-based reduced iron shaft furnace or a HyL high-temperature gas-based reduced iron shaft furnace.

In the system for producing gas-based direct reduced iron by catalytic conversion of coke oven gas, the purifier is used to purify coke oven gas as raw material gas;

The first fine desulfurization tower is used to carry out fine desulfurization treatment and deunsaturated hydrocarbon treatment on the purified coke oven gas, and the CO ₂ /H ₂ O inlet is used to input CO ₂ and/or H ₂ O to control the reformer nozzle other gas input pipes are used to input "converter gas, blast furnace gas, and a mixture of two or more of the purified tail gas";

Gas mixer for mixing oxygen-containing gas and "CO ₂ and/or H ₂ O" for controlling the flame temperature at the reformer nozzle;

The catalytic converter is used for catalytic conversion and the obtained synthesis gas containing _H2 and CO is fed to the shaft furnace as reducing gas;

The shaft furnace is provided with a pellet inlet, a top gas outlet and a reduced iron outlet, which are connected to the scrubber through the top gas outlet; wherein the pellet inlet is used to input iron ore into the shaft furnace, and the furnace The top gas outlet is used to input the top gas (reduced tail gas) produced by the shaft furnace into the scrubber, and the reduced iron outlet is used to output the produced direct reduced iron;

The scrubber is used for scrubbing the reduction tail gas produced by the shaft furnace;

The second fine desulfurization tower is used to perform fine desulfurization treatment on the washed reduced tail gas to obtain purified tail gas;

The decarbonization tower is used to remove CO ₂ from the purified tail gas, and the CO ₂ outlet is used to output the removed CO ₂ . This part of CO ₂ can be added to the raw material mixture or oxygen-containing gas, or used for other purposes; The reducing gas outlet is used to input the decarburized and purified tail gas into the heater, so that it can be sent to the shaft furnace as reducing gas to participate in the reduction reaction after heating;

The heater is used for heat treatment of the purified tail gas to be fed into the shaft furnace.

In the above system, the equipment used by each component can be existing equipment, as long as the corresponding functions can be realized.

The system for producing gas-based direct reduced iron using coke oven gas provided by the utility model can carry out direct reduction production according to the following steps:

The coke oven gas enters the purifier for purification (dust removal, deoiling, compression), and then enters the first fine desulfurization tower to contact with the catalyst for fine desulfurization and deunsaturated hydrocarbon treatment to reduce the content of olefins and aromatics, and then with the external Other gases (converter gas, blast furnace gas, purified tail gas, one or more than two kinds of mixed gas) are mixed to obtain the raw material mixed gas and enter the catalytic converter after preheating, and the oxygen-containing gas enters the catalytic converter after preheating ;

In the catalytic converter, the oxygen-containing gas and the raw gas mixture are mixed and partially combusted (partial oxidation) at the nozzle of the catalytic converter to perform dry reforming and/or steam reforming of methane to obtain high _H2 and CO concentration Syngas, in order to control the flame temperature during partial combustion, a certain amount of carbon dioxide and/or water vapor can be mixed into the oxygen-containing gas or raw material mixture before entering the catalytic converter;

Let the synthesis gas enter the shaft furnace, reduce the pellets, etc. to obtain direct reduced iron, and output it through the outlet of the reduced iron, and the reduction tail gas (top gas) generated at the top of the shaft furnace enters the cooler for cooling, and then enters the scrubber for further processing. Washing, the dry gas after washing enters the second fine desulfurization tower and contacts with zinc oxide catalyst for fine desulfurization treatment to obtain purified tail gas, and the purified tail gas enters the decarbonization tower to remove CO ₂ (CO ₂ is discharged through the CO ₂ outlet), and then It enters the heater for heating, and then enters the shaft furnace to participate in the reduction reaction. The purified tail gas can also be discharged directly after passing through the second fine desulfurization tower for other purposes.

The system for producing gas-based direct reduced iron using coke oven gas provided by the utility model is to use coke oven gas to produce synthesis gas through catalytic conversion method, and then to produce direct reduced iron system, and to achieve the follow-up Conversion catalyst requirements, and then burn with oxygen to provide heat for subsequent conversion reactions, and control various process indicators to make the synthesis gas meet the requirements of shaft furnace gas-based direct reduced iron. This system has the characteristics of easy control, simple structure, and low energy consumption. , especially suitable for enterprises with air separation and pure oxygen.

Description of drawings

The following drawings are only intended to illustrate and explain the utility model schematically, and do not limit the scope of the utility model. in:

Fig. 1 is a schematic structural diagram of a system for producing gas-based direct reduced iron using coke oven gas provided in Example 1.

Explanation of reference numbers:

Purifier 1 First Fine Desulfurization Tower 2 Catalytic Converter 3 Gas Mixer 4 Shaft Furnace 5 Cooler 6 Scrubber 7 Second Fine Desulfurization Tower 8 Decarbonization Tower 9 Heater 10

Detailed ways

In order to have a clearer understanding of the technical features, purpose and beneficial effects of the present utility model, the technical solution of the present utility model is described in detail below with reference to the accompanying drawings, but it should not be construed as limiting the scope of implementation of the present utility model.

Example 1

This embodiment provides a system for producing gas-based direct reduced iron by utilizing coke oven gas, the structure of which is shown in FIG. 1 . The system includes purifier 1, first fine desulfurization tower 2, catalytic converter 3, gas mixer 4, shaft furnace 5, cooler 6, scrubber 7, second fine desulfurization tower 8, decarbonization tower 9, heater 10, of which:

The purifier 1 is provided with a coke oven gas input port, and its outlet is connected to the first fine desulfurization tower 2;

The first fine desulfurization tower 2 is provided with a CO ₂ /H ₂ O inlet, and its outlet is connected to the catalytic converter 3, and the connecting pipe between the first fine desulfurization tower 2 and the catalytic converter 3 is provided with other Gas input pipeline;

The gas mixer 4 is respectively provided with an oxygen-containing gas inlet and a CO ₂ /H ₂ O inlet, and its outlet is connected to the catalytic converter 3;

The outlet of the catalytic converter 3 is connected with the shaft furnace 5;

The shaft furnace 5 is provided with a pellet inlet, a top gas outlet and a reduced iron outlet, which are connected to the cooler 6 through a top gas outlet;

The cooler 6 is connected with the scrubber 7;

The scrubber 7 is connected with the second fine desulfurization tower 8;

The second fine desulfurization tower 8 is connected with the decarburization tower 9;

The decarburization tower 9 is provided with a reducing gas outlet and _a CO outlet, and is connected with the heater 10 through the reducing gas outlet;

The heater 10 is connected to the shaft furnace 5 .

The system for producing gas-based direct reduced iron using coke oven gas provided in this embodiment can carry out the production of direct reduced iron according to the following steps:

The coke oven gas enters the purifier 1 for purification (dust removal, deoiling, compression), and then enters the first fine desulfurization tower 2 to contact with the catalyst for fine desulfurization and deunsaturated hydrocarbon treatment. It will also saturate the olefins and aromatics in the coke oven gas, and then mix other gases (converter gas, blast furnace gas, purified tail gas or a mixture of two or more) input through other gas input pipelines to obtain the raw material mixture gas and Enter the catalytic converter 3 after preheating, and the oxygen-containing gas enters the catalytic converter 3 after preheating;

In the catalytic converter 3, the oxygen-containing gas and the raw material mixture are mixed and partially combusted (partial oxidation) at the nozzle of the catalytic converter 3 to perform dry reforming and/or steam reforming of methane to obtain high _H2 and CO content of synthesis gas, in order to control the flame temperature during partial combustion, a certain amount of carbon dioxide and/or water vapor can be mixed into the oxygen-containing gas or raw material mixture before entering the catalytic converter 3, for example, through the gas mixer 4 to the Oxygen mixed with carbon dioxide and/or water vapor;

The synthesis gas with high _H2 and CO content produced in the catalytic converter 3 enters the shaft furnace 5, and the pellets etc. are reduced to obtain direct reduced iron, which is exported through the outlet of the reduced iron, and the reduced tail gas generated at the top of the shaft furnace 5 ( Furnace top gas) enters the cooler 6 for cooling, and then enters the scrubber 7 for washing. The dry gas after washing enters the second fine desulfurization tower 6 and contacts with the zinc oxide catalyst for fine desulfurization treatment to obtain purified tail gas, which then enters the desulfurization The carbon tower 9 removes the CO ₂ therein (the CO ₂ is discharged through the CO ₂ outlet), and then enters the heater 10 for heating, and then enters the shaft furnace 5 to participate in the reduction reaction.

Example 2

This embodiment provides a method for producing gas-based direct reduced iron by catalytic conversion of coke oven gas, which includes the following steps, carried out using the system shown in Figure 1:

The flow rate of raw coke oven gas is 20000Nm ³ /h, in which, in terms of volume ratio, the content of methane is about 22%, the content of hydrogen is about 59%, and it also contains a small amount of CO ₂ , CO, N ₂ and C ₂ ⁺ group points, the total sulfur content is less than 350ppm;

Raw coke oven gas enters purifier 1 for dust removal, deep deoiling, and pressurization, then heats up to 220°C, and enters the fine desulfurization reactor (the first fine desulfurization tower 2) for adsorption desulfurization under a pressure of 1.1MPa. Two reactors, one open and one regenerated, each equipped with 25m ³ of hydrogen adsorption fine desulfurizer, hydrogen adsorption fine desulfurizer contains 15wt% nickel and 5wt% tungsten, and the rest components are zinc oxide, aluminum oxide and magnesium oxide, the content 70wt%, 5wt% and 5wt% respectively (the hydroadsorption fine desulfurizer is CUPB-XTS series hydroadsorption desulfurizer, produced by Dongying Kerte New Material Co., Ltd.), and the hydroadsorption desulfurization is also saturated The olefins and aromatics in the coke oven gas are removed, the total sulfur content of the purified gas from the refined desulfurization reactor is less than 0.5ppm, and the concentration of olefins and aromatics is less than 100ppm, and then preheated to 600°C;

Use air separation oxygen (98% oxygen) as the oxidant for hydrocarbon conversion (that is, oxygen-containing gas), its flow rate is about 3168Nm ³ /h, preheated to 600°C, and if necessary, an appropriate amount of carbon dioxide and carbon dioxide can be input through the gas mixer 4 / or water vapor to control the temperature of the flame during combustion;

Under the pressure of 0.8MPa, the two streams of coke oven gas and oxygen-containing gas enter the nozzle of the catalytic converter 3 to mix and partially burn. The flame temperature is controlled at 1500-1700°C. The catalyst bed layer of the catalytic converter 3, under the action of the catalyst, the dry reforming conversion of methane and carbon dioxide and the steam reforming of methane occur to obtain synthesis gas. The catalyst loading in the catalytic converter 3 is 20m ³ , and the conversion catalyst of the coke oven gas is CUPB -DR series (manufactured by Dongying Keerte New Material Co., Ltd., containing about 10wt% nickel, and the balance being high-temperature-resistant aluminum-silicon-magnesium-lanthanum composite oxide heterogeneous carrier), the temperature of the synthesis gas at the outlet of catalytic converter 4 is about 1020°C, decompressed to 0.3MPa, the flow rate of synthesis gas is about 30460Nm ³ /h, in which, H ₂ :H ₂ O=14.9:1 and CO:CO ₂ =21.3:1, both are molar ratios, the entrance of the shaft furnace In the composition of syngas, the molar ratio of (H ₂ +CO)/(H ₂ +CO+H ₂ O+CO ₂ ) is 0.95, which meets the requirements of gas-based direct reduced iron, and can be directly used in the production of reduced iron;

The temperature of the synthesis gas produced by the above steps is as high as 1020°C, the degree of oxidation is 5.6%, and the molar ratio of H ₂ :CO is relatively high, about 2.92:1. It is input into the Midrex high-temperature gas-based reduced iron shaft furnace 5 for production.

The synthesis gas with a flow rate of 30460Nm ³ /h is used to produce direct reduced iron, and the output is about 20 _t /h. After reducing the iron, the tail gas is cooled by the cooler 6, washed by the scrubber 7, compressed and then enters the second fine desulfurization tower 8 Desulfurization is carried out by fine desulfurization process to obtain purified tail gas. The flow rate of the dry basis reduction tail gas after washing is about 21320Nm ³ /h, and the total sulfur content of the purified tail gas is lower than 0.5ppm, and then pressure swing adsorption is used in the decarbonization tower 9 method to decarbonize the exhaust gas. The flow rate of the purified tail gas after desulfurization and decarbonization purification is about 17660Nm ³ /h, the content of water and carbon dioxide is very low, and the oxidation degree is about 3.5%. It is a high-quality gas-based direct reduction iron reducing gas, of which 1960Nm ³ /h can be used Part of it is used as fuel to heat another 15700Nm ³ /h gas to about 900°C (can be done by heater 10), and then this part of gas is mixed with synthesis gas (product gas of catalytic conversion) or directly used as shaft furnace reduction gas , so that the production of reduced iron can be increased by about 10t/h, and the rational utilization of the tail gas of reduced iron can be realized.

Claims (2)

1. a system of utilizing coke(oven)gas to produce gas base directly reducing iron, it is characterized in that, this system of utilizing coke(oven)gas to produce gas base directly reducing iron comprises cleaner, the first smart thionizer, catalyzed conversion stove, gas mixer, shaft furnace, water cooler, washer, the second smart thionizer, decarbonizing tower, well heater, wherein:

Described cleaner is provided with coke(oven)gas input aperture, and its outlet is connected with described the first smart thionizer;

Described the first smart thionizer is provided with CO ₂/ H ₂o entrance, its outlet is connected with described catalyzed conversion stove, and, on the connecting tube of the first smart thionizer and catalyzed conversion stove, be provided with other gas inlet pipe roads;

Described gas mixer is respectively equipped with oxygen-containing gas entrance and CO ₂/ H ₂o entrance, its outlet is connected with described catalyzed conversion stove;

The outlet of described catalyzed conversion stove is connected with described shaft furnace;

Described shaft furnace is provided with pellet entrance, top gas outlet and reduced iron outlet, and it is exported with described water cooler and be connected by top gas;

Described water cooler is connected with described washer;

Described washer is connected with described the second smart thionizer;

Described the second smart thionizer is connected with described decarbonizing tower;

Described decarbonizing tower is provided with reducing gas outlet and CO ₂outlet, and export with described well heater and be connected by reducing gas;

Described well heater is connected with described shaft furnace.

2. the system of utilizing coke(oven)gas to produce gas base directly reducing iron according to claim 1, is characterized in that, described shaft furnace is Midrex High Temperature Gas base Shaft furnace for riducing iron or HyL High Temperature Gas base Shaft furnace for riducing iron.

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