Method and production equipment for preparing hydrogen-rich reducing gas for directly reducing iron

Abstract

The invention relates to a method for preparing hydrogen-rich reducing gas for directly reducing iron, which comprises the following steps in sequence: step 1): from the beginning of coking of a carbonization chamber in a coke oven, closing a second turning plate (201) of a hot gas pipe (20) in a gas collecting unit connected with the carbonization chamber through a pipeline, opening a first turning plate (101) of a gas collecting pipe (10) in the gas collecting unit, the gas from the raw gas in the carbonization chamber is introduced into the gas collecting pipe (10) for gas refining; 2) closing the first turning plate (101) and opening the second turning plate (201) in a time period from more than 60% of the total coking time to the total coking time, and introducing the raw gas from the carbonization chamber into the hot gas pipe (20); 3) introducing the gas in the hot gas pipe (20) into a red coke heating furnace (50) for modification to prepare hydrogen-rich reducing gas; the invention further discloses production equipment for implementing the method.

Description

Technical Field

[0001] This invention relates to the field of non-blast furnace ironmaking technology, and in particular to a method and production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron. Background Technology

[0002] Direct reduced iron (DRI) is a process that directly reduces iron ore to iron in a solid state. It can serve as a pure raw material for smelting high-quality and special steels, and also as an iron-containing raw material for processes such as casting, ferroalloys, and powder metallurgy. Traditional steelmaking processes will gradually be replaced by the shorter direct reduction electric arc furnace (DRI) steelmaking process. This technology can achieve the metallurgical industry's dual-carbon goals, promote industrial upgrading in the steel industry, save energy and reduce emissions, and is an important direction and pathway for sustainable development. Currently, among mature DRI processes, the vertical shaft furnace method is the main production process, with the Midrex process and the HYL / Energiron process being typical examples.

[0003] Most vertical shaft furnaces used natural gas as feedstock for direct reduced iron (DRI) production. However, natural gas is not suitable for use as feedstock in my country. Therefore, developing vertical shaft furnace processes using coke oven gas and pyrolysis gas as feedstocks is the future direction for DRI production technology in my country. However, coke oven gas cannot be directly used as DRI feedstock: First, it contains 20-30% CH4, which needs to be reformed into H2 and CO before it can be effectively used as a reducing gas; second, even after conventional purification, coke oven gas still contains trace amounts of heavy hydrocarbon impurities (tar, naphthalene, BTX (benzene, toluene, xylene)). These impurities will coke and deposit carbon during gas pressurization and heating, affecting equipment operation.

[0004] The HYL-ZR process is a method for producing DRI (Dry Reduction) from coke oven gas. It achieves CH4 conversion through self-reforming in a reduction shaft furnace. Therefore, this process places high demands on the shaft furnace and has relatively low reduction efficiency. For heavy hydrocarbon impurities in the coke oven gas, the process first purifies the gas by passing it through the cooling section of the shaft furnace, then reheating it before re-entering the shaft furnace. However, because the enthalpy of the DRI in the cooling section is insufficient to handle excessive amounts of coke oven gas, only about 30% of the coke oven gas can be utilized using this method. These two drawbacks are related to the compositional characteristics of coke oven gas, namely, high CH4 content and high aromatic hydrocarbon impurity content. Therefore, reducing the CH4 and aromatic hydrocarbon impurity content in coke oven gas for DRI production is crucial.

[0005] Existing invention patents have limited research on reducing CH4 and aromatic impurities in coke oven gas. For example, Chinese patents CN200510012823.7, CN200810226076.0, CN201010195863.0, and CN201210064998.2 relate to methods and equipment for producing DRI from coke oven gas. These patents introduce heated and / or purified coke oven gas into a vertical shaft furnace or converter for reduction, and the reduced top gas is returned to the heating furnace and / or vertical shaft furnace; CN201210064 Patent 993.X discloses a method for producing direct reduced iron (DRI) using coke oven gas. This method uses coke oven gas as both a reducing gas and a cooling gas. The two streams of coke oven gas mix at the bottom of the reduction section of a vertical shaft furnace and participate in the reaction to complete the reduction of iron ore. Patent CN201110112050.5 discloses a method for co-producing DRI using coke oven gas in dry quenching. This method uses coke oven gas as a heat transfer medium to cool red-hot coke and introduces it into the dry quenching coke oven. After heating, it serves as a hydrogen-rich reducing gas. All of these patent applications disclose methods for producing DRI using coke oven gas as a reducing gas. However, they focus more on the reforming of coke oven gas into CH4, rather than on increasing the H2 content of the reducing gas itself and reducing the content of aromatic impurities. Furthermore, the production processes and equipment are complex, requiring a series of purification treatments from the raw coke oven gas, such as tar removal, naphthalene removal, benzene removal, desulfurization, and ammonia removal, before finally obtaining purified coke oven gas (COG) suitable for DRI.

[0006] In non-blast furnace ironmaking technologies, red coke primarily functions as a reducing agent, helping to reduce oxygen in iron ore to metallic iron and providing thermal energy. However, existing patent applications show limited research on reducing CH4 and aromatic impurities in coke oven gas, and on further heat exchange and upgrading using red coke. Chinese patent CN201110112050.5 relates to a method for co-producing direct reduced iron from coke oven gas during dry quenching. It uses coke oven gas as a heat transfer medium to cool the red coke, which is then introduced into the dry quenching oven and heated to serve as a hydrogen-rich reducing gas. This patent utilizes cooled and purified coke oven gas, or surplus purge gas from methanol production using coke oven gas, to replace nitrogen in the dry quenching process, and does not consider reducing CH4 and aromatic impurities in the coke oven gas. Summary of the Invention

[0007] The gas composition of raw coal gas produced during the coking process in modern coke ovens changes with the coking time. In the later stages of coking, the raw coal gas is mainly composed of H2 with low CH4 content, and only trace amounts of heavy hydrocarbons such as tar, naphthalene, and BTX. The raw coal gas in this coking stage has both good reducing gas components (H2) and high sensible heat, making it very suitable as feed gas for DRI production in vertical shaft furnaces. However, existing technologies do not address how to effectively utilize the raw coal gas in the later stages of coking, and with current coke oven raw coal gas collection equipment, it is difficult to extract and utilize the raw coal gas in the later stages of coking.

[0008] Figure 1 The structure of a conventional coke oven raw gas extraction and collection device in the prior art is shown, wherein the raw gas escapes from the carbonization chamber (not shown) and enters the gas collection pipe (10) via the riser pipe (40) and the bridge pipe (30). The bridge pipe (30) is equipped with an ammonia water nozzle (301), and a flap (101) controls the opening and closing of the gas collection pipe (10). When the flap (101) is open, the carbonization chamber is connected to the gas collection pipe (10) through the riser pipe (40) and the bridge pipe (30). The raw gas from the carbonization chamber enters the bridge pipe (30) via the riser pipe (40), and after being cooled by ammonia water sprayed from the ammonia water nozzle (301), it directly enters the gas collection pipe (10). This conventional coke oven cannot collect the raw gas in the early and late stages of the coking time separately, and cannot directly utilize the sensible heat contained in the raw gas itself.

[0009] Therefore, in order to overcome the problems existing in the prior art, the present invention provides a method and production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron. The hydrogen-rich reducing gas obtained by the present invention has a high H2 content, a low CH4 content, and only trace amounts of heavy hydrocarbon compounds. The raw coal gas, which can maintain a physical sensible heat of 700-800℃, can be further improved by upgrading to increase the H2 content in the generated hydrogen-rich reducing gas, further reduce the CH4 content and heavy hydrocarbon compound content, and increase the physical sensible heat to 900-1000℃. It can be directly used as a reducing gas for DRI production in a vertical shaft furnace or other reduction processes, and has the characteristics of simple process and low energy consumption.

[0010] A first aspect of the present invention provides a production apparatus for preparing hydrogen-rich reducing gas for direct reduction of iron, the production apparatus comprising a coke oven and a red coke heating furnace, wherein the coke oven includes a carbonization chamber and a gas collection unit, the carbonization chamber being connected to the gas collection unit via a pipeline, the gas collection unit comprising:

[0011] A gas collecting pipe (10), the inlet of which is controlled by a first flap (101); and

[0012] Hot air pipe (20), the inlet of which is controlled by a second flap (201);

[0013] From the moment coking begins in the carbonization chamber, the first flap (101) is in the open state, the second flap (201) is in the closed state, and the carbonization chamber is connected to the gas collecting pipe (10);

[0014] During the period from 60% or more, preferably 2 / 3 or more, more preferably 70% or more of the total coking time in the carbonization chamber to the total coking time, the first flap (101) is in the closed state and the second flap (201) is in the open state. The carbonization chamber is connected to the hot gas pipe (20), and the outlet of the hot gas pipe (20) is connected to the red coke heating furnace (50). The red coke heating furnace (50) is used to further refine the gas from the hot gas pipe (20) to obtain hydrogen-rich reducing gas.

[0015] The production equipment described above in this invention can be used to prepare and collect hydrogen-rich reducing gas for direct reduction of iron. In this text, "pipeline" includes any pipe that connects the carbonization chamber to the gas collection unit and allows gas flow, such as an ascending pipe, a bridge pipe, etc. By controlling the first flap (101) and the second flap (201), the gas from the carbonization chamber can be directed into the gas collecting pipe (10) or the hot gas pipe (20), respectively.

[0016] Preferably, the pipeline includes a riser pipe and a bridge pipe, and the bridge pipe is equipped with an ammonia water nozzle (301). At the beginning of coking, since the raw coal gas from the carbonization chamber contains a large amount of gaseous tar, it can be cooled by spraying ammonia water. The ammonia water evaporates rapidly and absorbs a large amount of heat, which lowers the temperature of the raw coal gas to 80-100°C and promotes tar condensation.

[0017] Preferably, the outlet of the gas collecting pipe (10) is connected to a gas refining unit. The raw coal gas collected in the gas collecting pipe (10) contains H2 and CH4. 4、 Tar, naphthalene, BTX, etc. The gas collected in the gas collecting pipe (10) can be further detarted, denaphthalene removed, debenzene removed, desulfurized, deammoniated, etc. in the gas refining unit to finally obtain purified coke oven gas (COG) for further reuse.

[0018] Preferably, the production equipment further includes a dust collector (60) and a heating furnace (70), wherein the outlet of the red coke heating furnace (50) is connected to the dust collector (60) to introduce hydrogen-rich reducing gas into the dust collector (60) and remove dust from the hydrogen-rich reducing gas in the dust collector (60), and the outlet of the dust collector (60) is connected to the heating furnace (70) to heat and collect the hydrogen-rich reducing gas. Gas discharged from the top of the red coke heating furnace (50) is introduced into the inlet of the dust collector (60), and the dust-removed gas is discharged from the outlet of the high-temperature dust collector (60) and introduced into the inlet of the heating furnace (70). The dust collector (60) is used to separate dust from the gas discharged from the red coke heating furnace (50). The heating furnace (70) is used to further heat the gas discharged from the red coke heating furnace (50), and its outlet can be connected to a DRI unit.

[0019] Preferably, the coke oven includes multiple carbonization chambers and multiple gas collection units, with each carbonization chamber corresponding to one of the gas collection units. Typically, a coke oven contains more than one carbonization chamber, each with an independent coking time; therefore, each carbonization chamber can correspond to one gas collection unit.

[0020] Preferably, the coke heating furnace (50) includes a first coke heating furnace (501) and a second coke heating furnace (502), one of which is used for heating and upgrading raw coal gas, and the other is used for oxygen storage; the outlet of the hot gas pipe (20) is connected to the first coke heating furnace (501) and the second coke heating furnace (502) respectively, wherein the hot gas pipe (20) is alternately connected to one of the first coke heating furnace (501) and the second coke heating furnace (502).

[0021] The red coke heater (50) is a vertical furnace containing red coke, used to upgrade gas (i.e., raw coal gas) from the hot gas pipe (20). During the heating of the gas from the hot gas pipe (20), the temperature in the red coke heater (50) decreases. Therefore, the red coke heater (50) can be divided into two sets: one for heating raw coal gas and the other for heat storage as a backup. Red coke that has not undergone quenching is added from the top of the two vertical furnaces to form the first red coke heater (501) and the second red coke heater (502). The first red coke heater (501) and the second red coke heater (502) are used interchangeably, one in operation and one on standby. For example, when the temperature in the first red coke heater (501) is below 900°C, gas from the hot gas pipe (20) is introduced into the second red coke heater (502) for reforming, while the first red coke heater (501) is heated to 900-1000°C. This cycle is repeated to improve the reforming efficiency. The temperature of the gas in the hot gas pipe (20) is 700-800°C, and it is alternately introduced into the first red coke heater (501) and the second red coke heater (502) to reform the red coke. The temperature of the raw coal gas discharged from the red coke heater can be raised to 900-950°C.

[0022] A second aspect of the present invention provides a method for preparing a hydrogen-rich reducing gas for the direct reduction of iron, comprising the following steps performed sequentially:

[0023] Step 1): Starting from the coking chamber in the coke oven, close the second flap (201) of the hot gas pipe (20) in the gas collection unit connected to the coking chamber through the pipe, open the first flap (101) of the gas collection pipe (10) in the gas collection unit, and introduce the gas from the raw coal gas in the coking chamber into the gas collection pipe (10) for coal gas refining.

[0024] Step 2): During the period from 60% or more, preferably 2 / 3 or more, more preferably 70% or more of the total coking time in the carbonization chamber to the total coking time, close the first flap (101) of the gas collecting pipe (10) and open the second flap (201) of the hot gas pipe (20) to introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20).

[0025] Step 3): The gas in the hot gas pipe (20) is passed to the red coke heating furnace (50) for modification. The gas temperature coming out of the red coke heating furnace (50) is 900-950℃.

[0026] Typically, when the coking time is more than 60% of the total coking time (preferably more than 2 / 3, more preferably more than 70%), the raw coal gas in the carbonization chamber has a low content of CH4 and heavy hydrocarbons and a high content of H2, which can be further modified for direct reduction of iron.

[0027] Preferably, the method further includes step 2.1): the gas collected in the gas collecting pipe (10) is introduced into the gas refining unit, and the gas is further detarted, denaphthalene removed, debenzene removed, desulfurized, deammoniated, etc. in the gas refining unit to finally obtain purified coke oven gas (COG) for further reuse.

[0028] Preferably, in step 1), ammonia water is sprayed when the first flap (101) of the gas collecting pipe (10) is opened, and in step 2), ammonia water spraying is stopped when the first flap (101) of the gas collecting pipe (10) is closed. In step 1), the raw coal gas from the carbonization chamber has a high content of tar and heavy hydrocarbons, so spraying ammonia water can cause the tar and heavy hydrocarbons to condense; while in step 2), the raw coal gas from the carbonization chamber in the later stage of coking time has a lower content of tar and heavy hydrocarbons, so there is no need to spray ammonia water for condensation, and the sensible heat of the gas during coking can be retained while ensuring the H2 content.

[0029] Preferably, in step 1), the gas collected in the gas collecting pipe (10) includes the following components: H2 ≤ 55% by volume, CH4 ≥ 25% by volume, CO: 2-6% by volume, CO2: 3-8% by volume, tar: ≥ 200 mg / Nm, naphthalene: ≥ 300 mg / Nm, BTX: ≥ 2000 mg / Nm.

[0030] Preferably, in step 2), the gas collected in the hot gas pipe (20) includes the following components: H2 ≥ 70% by volume, CH4 ≤ 15% by volume, CO: 2-10% by volume, CO2: 1-6% by volume, tar: ≤ 10 mg / Nm, naphthalene: ≤ 30 mg / Nm, BTX: ≤ 300 mg / Nm.

[0031] Preferably, in step 2), the temperature of the gas collected in the hot gas pipe (20) is 700-800°C.

[0032] Preferably, the total coking time in the carbonization chamber is 19 to 25 hours.

[0033] In summary, the coking time is determined by the specifications of the coke oven. In this invention, a top-loading regenerative coke oven (with a carbonization chamber height of more than 6m) is generally used.

[0034] Preferably, in step 3), the red coke heating furnace (50) includes a first red coke heating furnace (501) and a second red coke heating furnace (502);

[0035] The first red coke heater (501) and the second red coke heater (502) are used alternately to heat the gas collected in the reforming hot gas pipe (20). The gas in the hot gas pipe (20) is passed into the first red coke heater (501) for reforming. When the temperature of the red coke in the first red coke heater (501) is lower than 900°C, the gas passing into the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is passed into the second red coke heater (502). At the same time, oxygen is introduced into the first red coke heater (501) to make the first red coke... The temperature in the coke heating furnace (501) is raised to 900℃-1000℃; when the temperature of the second red coke heating furnace (502) is lower than 900℃, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the first red coke heating furnace (501), while oxygen is introduced into the second red coke heating furnace (502) to raise the temperature in the second red coke heating furnace (502) to 900℃-1000℃; the above heating process is repeated to modify the gas in the hot gas pipe (20).

[0036] By controlling the oxygen supply, the temperature of the red coke in the first red coke heater (501) and the second red coke heater (502) is alternately maintained at 900-1000℃. Gas from the hot gas pipe (20) is introduced into the first red coke heater (501) or the second red coke heater (502) to reform the red coke. As described above, alternating use of the first red coke heater (501) and the second red coke heater (502) can improve the efficiency of heating and reforming raw coal gas.

[0037] Preferably, the gas collected in the red coke heating furnace (50) comprises the following components: CH4: 0-10 vol%, H2: 75-90 vol%, CO: 4-12 vol%, CO2: 0-1 vol%, N2: 0-4 vol%, C n H m 0-0.5% by volume; tar: 0-5 mg / Nm, naphthalene: 0-10 mg / Nm, BTX: 0-100 mg / Nm.

[0038] Preferably, the method further includes step 4): introducing the gas in the red coke heating furnace (50) into the dust collector (60) for dust removal.

[0039] Preferably, the method further includes step 5): introducing the gas in the dust collector (60) into the heating furnace (70), heating and collecting the gas in the heating furnace (70); preferably, the temperature of the gas collected in the heating furnace (70) is 1050-1100℃.

[0040] Preferably, in step 5), the heating furnace (70) is a tubular heating furnace.

[0041] A tubular heater is preferred for further heating the gas after dust removal to produce hydrogen-rich reducing gas. The tubular heater uses blast furnace gas, coke oven gas, or DRI process tail gas for combustion outside the tubes to heat the inside of the tubes. The tubular heater further increases the temperature of the gas exiting the dust collector (60) to 1050-1100°C; this further increased sensible heat can be used in subsequent direct reduction iron processes.

[0042] Beneficial effects of this invention:

[0043] 1) This invention collects the portion of raw coal gas with high H2 content, and after being modified with red coke, it can be used as a high-quality hydrogen-rich reducing gas for direct reduction of iron. The reduction of iron by this hydrogen-rich reducing gas can achieve low carbon emissions, effectively solving the shortcomings of high CH4 content and high aromatic impurity content in the coke oven gas currently used for direct reduction of iron.

[0044] 2) This invention can effectively utilize the sensible heat of raw coal gas, which can be retained in the subsequent direct reduction iron process, thus saving energy. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of a conventional coke oven;

[0046] Figure 2 This is a schematic diagram of a production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron according to an embodiment of the present invention.

[0047] Reference numerals: 10-Gas collecting pipe; 20-Hot gas pipe; 101-First flap; 201-Second flap; 30-Bridge pipe; 301-Ammonia water nozzle; 40-Rising pipe; 50-Red coke heating furnace; 501-First red coke heating furnace; 502-Second red coke heating furnace; 60-Dust collector; 70-Heating furnace. Detailed Implementation

[0048] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the invention is not limited to the embodiments mentioned herein. Furthermore, unless otherwise stated, features of the various embodiments can be suitably combined with each other.

[0049] In the description of this embodiment, it should be noted that the terms "upper," "front," "inner," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of the invention is usually placed in during use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0050] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly, for example, it can be a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above term in this embodiment based on the specific circumstances.

[0051] Gas composition detection methods

[0052] The collected gas was sampled and then analyzed by gas chromatography to determine the content of the main components in the coke oven gas, such as GB / T28901-2012 Gas Chromatographic Analysis Method for Coke Oven Gas Components.

[0053] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0054] As mentioned above, Figure 1 The diagram shows the structure of a conventional coke oven. The carbonization chamber is connected to the gas collecting pipe (10) through the riser pipe (40) and the bridge pipe (30). During the coking time, the gas from the carbonization chamber is introduced into the gas collecting pipe (10).

[0055] Figure 2 A schematic diagram of the production equipment for preparing hydrogen-rich reducing gas for direct reduced iron according to the present invention is shown. The carbonization chamber is connected to a gas collection unit via a pipe. The gas collection unit includes: a gas collecting pipe (10), the inlet of which is controlled by a first flap (101); and a hot gas pipe (20), the inlet of which is controlled by a second flap (201).

[0056] In the production equipment of the present invention, from the start of coking in the carbonization chamber, the first flap (101) is in the open state and the second flap (201) is in the closed state, and the carbonization chamber is connected to the gas collecting pipe (10); during the period from 60% or more, preferably 2 / 3 or more, more preferably 70% or more of the coking time to the coking time, preferably to 80% of the coking time, more preferably to 75% of the coking time, the first flap (101) is in the closed state and the second flap (201) is in the open state, and the carbonization chamber is connected to the hot gas pipe (20), and the outlet of the hot gas pipe (20) is connected to the red coke heating furnace (50), which is used to further refine the gas from the hot gas pipe (20) to obtain hydrogen-rich reducing gas.

[0057] The pipeline includes an ascending pipe (40) and a bridge pipe (30). The carbonization chamber is connected to the gas collecting pipe (10) and the hot gas pipe (20) via the ascending pipe (40) and the bridge pipe (30), respectively. An ammonia water nozzle (301) is provided on the bridge pipe (30). By controlling the first flap (101) of the gas collecting pipe (10) and the second flap (201) of the hot gas pipe (20), the present invention allows gas from the carbonization chamber to enter the gas collecting pipe (10) or the hot gas pipe (20).

[0058] The coke heating furnace (50) includes a first coke heating furnace (501) and a second coke heating furnace (502). The outlet of the hot gas pipe (20) is connected to the first coke heating furnace (501) and the second coke heating furnace (502) respectively. The hot gas pipe (20) is alternately connected to one of the first coke heating furnace (501) and the second coke heating furnace (502).

[0059] In the production equipment of the present invention, the outlet of the gas collecting pipe (10) can be connected to the gas refining unit.

[0060] The production equipment of the present invention also includes a dust collector (60) and a heating furnace (70). The outlet of the red coke heating furnace (50) is connected to the dust collector (60) to introduce hydrogen-rich reducing gas into the dust collector (60) and remove dust from the hydrogen-rich reducing gas in the dust collector (60), and the outlet of the dust collector (60) is connected to the heating furnace (70) to heat and collect the hydrogen-rich reducing gas.

[0061] Example 1

[0062] A steel plant needs to produce pre-reduced Fe pellets with a metallization rate of over 85%, requiring an annual output of 300,000 tons. This invention collects raw coal gas from the latter part of the coking time in a 200-hole, 6-meter coke oven as feed gas for direct reduction of iron. In this embodiment, the final coking time in the carbonization chamber is 21 hours. Specifically, the method includes the following steps performed sequentially:

[0063] Step 1): When coking begins in the carbonization chamber, close the second flap (201) of the hot gas pipe (20) and open the first flap (101) of the gas collecting pipe (10) to introduce the gas from the raw coal gas in the carbonization chamber into the gas collecting pipe (10).

[0064] Before the coking time in the coke oven reaches 12.6 hours (i.e., 60% of the total coking time), ammonia water is sprayed by the ammonia water nozzle (301) on the bridge pipe (30). The first flap (101) located before the inlet of the gas collecting pipe (10) is in the open state, and the second flap (201) located before the inlet of the hot gas pipe (20) is in the closed state. The raw coal gas from the carbonization chamber is cooled and condensed into tar after being sprayed with ammonia water. Then, the mixture of gas and tar is introduced into the gas collecting pipe (10). The gas collected in the gas collecting pipe (10) contains the following components: H2: 54.5 vol%, CH4: 20.9 vol%, CO: 4.4 vol%, CO2: 7.1 vol%, tar: 385 mg / Nm, naphthalene: 260 mg / Nm, BTX: 3100 mg / Nm.

[0065] Step 2): When the coking time is 60% of the total coking time, close the first flap (101), open the second flap (201), and introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20).

[0066] When the coking time of the carbonization chamber reaches 12.6 hours, close the ammonia water nozzle (301) on the bridge pipe (30), stop spraying ammonia water, close the first flap (101) located at the inlet of the gas collecting pipe (10), open the second flap (201) located at the inlet of the hot gas pipe (20), and introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20) until the coking time reaches 21 hours (final coking time);

[0067] Then, the gas collected in the gas collecting pipe (10) is introduced into the gas refining unit, and the gas collected in the hot gas pipe (20) is directly introduced into the red coke heating furnace (50).

[0068] This method allows for the collection of approximately 25,000 Nm³ / h of raw gas from raw coal gas. The raw gas collected in the hot gas pipe (20) has a temperature of 800 °C and contains the following components: H₂: 70.8 vol%, CH₄: 14.5 vol%, CO: 9.2 vol%, CO₂: 2.7 vol%, tar: 10 mg / Nm³, naphthalene: 30 mg / Nm³, and BTX: 300 mg / Nm³.

[0069] Example 2

[0070] A steel plant needs to produce pre-reduced Fe pellets with a metallization rate of over 85%, requiring an annual output of 300,000 tons. This invention collects raw coal gas from the later stages of coking time in a 200-hole, 6-meter coke oven as feed gas for direct reduction of iron. In this embodiment, the final coking time in the carbonization chamber is 21 hours. Specifically, the method includes the following steps performed sequentially:

[0071] Step 1): Starting from the coking of the carbonization chamber, close the second flap (201) of the hot gas pipe (20) and open the first flap (101) of the gas collecting pipe (10) to introduce the gas from the raw coal gas in the carbonization chamber into the gas collecting pipe (10).

[0072] Before the coking time in the coking chamber of the coke oven reaches 14 hours (i.e., 2 / 3 of the total coking time), ammonia water is sprayed by the ammonia water nozzle (301) on the bridge pipe (30). The first flap (101) located in front of the gas inlet of the gas collecting pipe (10) is in the open state, and the second flap (201) located in front of the hot gas pipe (20) is in the closed state. The raw coal gas from the coking chamber is cooled and condensed into tar after being sprayed with ammonia water. Then the mixture of gas and tar is introduced into the gas collecting pipe (10). The gas collected in the gas collecting pipe (10) contains the following components: H2: 55.5 vol%, CH4: 21.8 vol%, CO: 4.9 vol%, CO2: 6.6 vol%, tar: 408 mg / Nm, naphthalene: 366 mg / Nm, BTX: 3900 mg / Nm.

[0073] Step 2): When the coking time is 2 / 3 of the total coking time, close the first flap (101) and open the second flap (201) to introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20).

[0074] When the coking time of the carbonization chamber reaches 14 hours, close the ammonia water nozzle (301) on the bridge pipe (30) to stop spraying ammonia water, close the first flap (101) located at the inlet of the gas collecting pipe (10), open the second flap (201) located at the inlet of the hot gas pipe (20), and the raw coal gas from the carbonization chamber enters the hot gas pipe (20) until the coking time reaches 21 hours (final coking time);

[0075] Then, the gas collected in the gas collecting pipe (10) is introduced into the gas refining unit, and the gas collected in the hot gas pipe (20) is directly introduced into the red coke heating furnace (50).

[0076] This method allows for the collection of approximately 18,000 Nm³ / h of raw gas from raw coal gas. The raw gas collected in the hot gas pipe (20) has a temperature of 800 °C and contains the following components: H₂: 74.5 vol%, CH₄: 11.9 vol%, CO: 7.2 vol%, CO₂: 2.2 vol%, tar: 5 mg / Nm³, naphthalene: 10 mg / Nm³, and BTX: 150 mg / Nm³.

[0077] Example 3

[0078] A steel plant needs to produce DRI with a metallization rate of over 90%, requiring an annual output of 500,000 tons. This invention collects raw coal gas from the later stages of coking time in a 200-hole, 7-meter coke oven as feed gas using the following method. In this embodiment, the final coking time in the carbonization chamber is 24 hours.

[0079] Specifically, the method includes the following steps performed sequentially:

[0080] Step 1): Starting from the coking of the carbonization chamber, close the second flap (201) of the hot gas pipe (20) and open the first flap (101) of the gas collecting pipe (10) to introduce the gas from the raw coal gas in the carbonization chamber into the gas collecting pipe (10).

[0081] Before the coking time in the coking chamber of the coke oven reaches 16.8 hours (i.e., 70% of the total coking time), ammonia water is sprayed by the ammonia water nozzle (301) on the bridge pipe (30). The first flap (101) at the inlet of the gas collecting pipe (10) is in the open state, and the second flap (201) at the inlet of the hot gas pipe (20) is in the closed state. The raw coal gas from the coking chamber is cooled and condensed into tar after being sprayed with ammonia water. The mixture of gas and tar enters the gas collecting pipe (10). The gas collected in the gas collecting pipe (10) contains the following components: H2: 57.5 vol%, CH4: 20.3 vol%, CO: 6.5 vol%, CO2: 3.6 vol%, tar: 212 mg / Nm, naphthalene: 305 mg / Nm, BTX: 2800 mg / Nm.

[0082] Step 2): When the coking time is 70% of the total coking time, close the first flap (101), open the second flap (201), and introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20).

[0083] When the coking time of the carbonization chamber reaches 16.8 hours, close the ammonia water nozzle (301) on the bridge pipe (30), stop spraying ammonia water, close the first flap (101) located at the inlet of the gas collecting pipe (10), open the second flap (201) located at the inlet of the hot gas pipe (20), and introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20).

[0084] Then, the gas collected in the gas collecting pipe (10) is introduced into the gas refining unit, and the gas collected in the hot gas pipe (20) is directly introduced into the red coke heating furnace (50).

[0085] This method allows for the collection of approximately 24,000 Nm³ / h of raw gas from raw coal gas. The raw gas collected in the hot gas pipe (20) has a temperature of 700 °C and contains the following components: H₂: 73.8 vol%, CH₄: 10.7 vol%, CO: 8.3 vol%, CO₂: 2.0 vol%, tar: 8 mg / Nm³, naphthalene: 12 mg / Nm³, and BTX: 180 mg / Nm³.

[0086] Example 4

[0087] The raw material gas in the hot gas pipe (20) of Example 2 is introduced into the first red coke heating furnace (501) for modification; when the temperature of the red coke in the first red coke heating furnace (501) is lower than 900°C, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the second red coke heating furnace (502). At the same time, oxygen is introduced into the first red coke heating furnace (501) to raise the temperature in the first red coke heating furnace (501) to 900°C-1000°C; after a period of time, when the temperature of the red coke in the second red coke heating furnace (502) is lower than 900°C, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the first red coke heating furnace (501). At the same time, oxygen is introduced into the second red coke heating furnace (502) to raise its temperature to 900°C-1000°C; the above heating process is repeated to obtain hydrogen-rich reducing gas. The gas leaving the first red coke heater (501) reaches a temperature of 900°C. Optionally, the gas after heat exchange and conditioning in the first red coke heater (501) passes through a dust collector (60) to remove dust. Optionally, the gas in the dust collector (60) is passed to the heater (70) for further heating to 1050°C.

[0088] The hydrogen-rich reducing gas collected by this method can be used for the direct reduction of iron. The temperature of the hydrogen-rich reducing gas collected in the heating furnace (70) is 1050℃, and it contains the following components: H2: 82% by volume, CH4: 10% by volume, CO: 5% by volume, CO2: 1% by volume, N2: 3% by volume, C n H m 0.5%; Tar: 2 mg / Nm, Naphthalene: 10 mg / Nm, BTX: 60 mg / Nm.

[0089] Example 5

[0090] The raw material gas in the hot gas pipe (20) of Example 2 is introduced into the first red coke heating furnace (501) for modification; when the temperature of the red coke in the first red coke heating furnace (501) is lower than 900°C, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the second red coke heating furnace (502). At the same time, oxygen is introduced into the first red coke heating furnace (501) to raise the temperature in the first red coke heating furnace (501) to 900°C-1000°C; after a period of time, when the temperature of the red coke in the second red coke heating furnace (502) is lower than 900°C, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the first red coke heating furnace (501). At the same time, oxygen is introduced into the second red coke heating furnace (502) to raise its temperature to 900°C-1000°C; the above heating process is repeated to obtain hydrogen-rich reducing gas. The gas leaving the first red coke heater (501) reaches a temperature of 910°C. Optionally, the gas after heat exchange and conditioning in the first red coke heater (501) passes through a dust collector (60) to remove dust. Optionally, the gas in the dust collector (60) is passed to the heater (70) for further heating to 1070°C.

[0091] The hydrogen-rich reducing gas collected by this method can be used for the direct reduction of iron. The temperature of the hydrogen-rich reducing gas collected in the heating furnace (70) is 1070℃, and it contains the following components: H2: 87 vol%, CH4: 3 vol%, CO: 7.5 vol%, CO2: 0.5 vol%, N2: 1.8 vol%, C n H m : 0% by volume; tar: 1 mg / Nm, naphthalene: 2 mg / Nm, BTX: 40 mg / Nm.

[0092] Example 6

[0093] The raw material gas in the hot gas pipe (20) of Example 2 is introduced into the first red coke heating furnace (501) for modification; when the temperature of the red coke in the first red coke heating furnace (501) is lower than 900°C, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the second red coke heating furnace (502). At the same time, oxygen is introduced into the first red coke heating furnace (501) to raise the temperature in the first red coke heating furnace (501) to 900°C-1000°C; after a period of time, when the temperature of the red coke in the second red coke heating furnace (502) is lower than 900°C, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the first red coke heating furnace (501). At the same time, oxygen is introduced into the second red coke heating furnace (502) to raise its temperature to 900°C-1000°C; the above heating process is repeated to obtain hydrogen-rich reducing gas. The gas leaving the first red coke heater (501) reaches a temperature of 950°C. Optionally, the gas after heat exchange and conditioning in the first red coke heater (501) passes through a dust collector (60) to remove dust. Optionally, the gas in the dust collector (60) is passed to the heater (70) for further heating. The temperature of the gas in the heater (70) can be further increased to 1100°C.

[0094] The hydrogen-rich reducing gas collected by this method can be used for the direct reduction of iron. The temperature of the hydrogen-rich reducing gas collected in the heating furnace (70) is 1100℃, and it contains the following components: H2: 85 vol%, CH4: 5 vol%, CO: 6 vol%, CO2: 0.5 vol%, N2: 2.5 vol%, C n H m : 0% by volume; tar: 1 mg / Nm, naphthalene: 4 mg / Nm, BTX: 50 mg / Nm.

[0095] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. A production apparatus for preparing hydrogen-rich reducing gas for direct reduction of iron, comprising a coke oven and a red-hot coke heating furnace, characterized in that, The coke oven includes a carbonization chamber and a gas collection unit. The carbonization chamber is connected to the gas collection unit via a pipeline. The gas collection unit includes: A gas collecting pipe (10), the inlet of which is controlled by a first flap (101); and Hot air pipe (20), the inlet of which is controlled by a second flap (201); From the moment coking begins in the carbonization chamber, the first flap (101) is in the open state, the second flap (201) is in the closed state, and the carbonization chamber is connected to the gas collecting pipe (10); During the period from 60% or more, preferably 2 / 3 or more, more preferably 70% or more of the total coking time in the carbonization chamber to the total coking time, the first flap (101) is in the closed state and the second flap (201) is in the open state. The carbonization chamber is connected to the hot gas pipe (20), and the outlet of the hot gas pipe (20) is connected to the red coke heating furnace (50). The red coke heating furnace (50) is used to further refine the gas from the hot gas pipe (20) to obtain hydrogen-rich reducing gas.

2. The production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron according to claim 1, characterized in that, The pipeline includes an ascender pipe (40) and a bridge pipe (30), and the bridge pipe (30) is provided with an ammonia nozzle (301).

3. The production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron according to claim 1, characterized in that, The outlet of the gas collecting pipe (10) is connected to the gas refining unit.

4. The production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron according to claim 1, characterized in that, The production equipment also includes a dust collector (60) and a heating furnace (70), wherein the outlet of the red coke heating furnace (50) is connected to the dust collector (60) to introduce hydrogen-rich reducing gas into the dust collector (60) and remove dust from the hydrogen-rich reducing gas in the dust collector (60), and the outlet of the dust collector (60) is connected to the heating furnace (70) to heat and collect the hydrogen-rich reducing gas.

5. The production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron according to claim 1, characterized in that, The coke oven includes multiple carbonization chambers and multiple gas collection units, with each carbonization chamber corresponding to one of the gas collection units.

6. The production equipment for preparing hydrogen-rich reducing gas for direct reduction of iron according to claim 1, characterized in that, The red coke heating furnace (50) includes a first red coke heating furnace (501) and a second red coke heating furnace (502). One of the first red coke heating furnace (501) and the second red coke heating furnace (502) is used for heating and upgrading raw coal gas, and the other is used for oxygen storage. The outlet of the hot gas pipe (20) is connected to the first red coke heating furnace (501) and the second red coke heating furnace (502) respectively, wherein the hot gas pipe (20) is alternately connected to one of the first red coke heating furnace (501) and the second red coke heating furnace (502).

7. A method for preparing a hydrogen-rich reducing gas for the direct reduction of iron, characterized in that, The method includes the following steps performed sequentially: Step 1): Starting from the coking chamber in the coke oven, close the second flap (201) of the hot gas pipe (20) in the gas collection unit connected to the coking chamber through the pipe, open the first flap (101) of the gas collection pipe (10) in the gas collection unit, and introduce the gas from the raw coal gas in the coking chamber into the gas collection pipe (10) for coal gas refining. Step 2): During the period from 60% or more, preferably 2 / 3 or more, more preferably 70% or more of the total coking time to the total coking time, close the first flap (101) of the gas collecting pipe (10) and open the second flap (201) of the hot gas pipe (20) to introduce the raw coal gas from the carbonization chamber into the hot gas pipe (20). Step 3): The gas in the hot gas pipe (20) is passed to the red coke heating furnace (50) for modification; the temperature of the raw coal gas leaving the red coke heating furnace (50) is 900-950℃.

8. The method according to claim 7, characterized in that, The method further includes step 2.1): introducing the gas collected in the gas collecting pipe (10) into the gas refining unit.

9. The method according to claim 7, characterized in that, In step 1), ammonia water is sprayed when the first flap (101) of the gas collecting pipe (10) is opened, and in step 2), ammonia water spraying is stopped when the first flap (101) of the gas collecting pipe (10) is closed.

10. The method according to claim 7, characterized in that, In step 1), the gas collected in the gas collecting tube (10) includes the following components: H2 ≤ 55% by volume, CH4 ≥ 25% by volume, CO: 2-6% by volume, CO2: 3-8% by volume, tar: ≥ 200 mg / Nm, naphthalene: ≥ 300 mg / Nm, BTX: ≥ 2000 mg / Nm.

11. The method according to claim 7, characterized in that, In step 2), the gas collected in the hot gas pipe (20) includes the following components: H2 ≥ 70% by volume, CH4 ≤ 15% by volume, CO: 2-10% by volume, CO2: 1-6% by volume, tar: ≤ 10 mg / Nm, naphthalene: ≤ 30 mg / Nm, BTX: ≤ 300 mg / Nm.

12. The method according to claim 7, characterized in that, In step 2), the temperature of the gas collected in the hot gas pipe (20) is 700-800℃.

13. The method according to claim 7, characterized in that, The total coking time in the carbonization chamber is 19-25 hours.

14. The method according to claim 7, characterized in that, In step 3), the red coke heating furnace (50) includes a first red coke heating furnace (501) and a second red coke heating furnace (502). One of the first red coke heating furnace (501) and the second red coke heating furnace (502) is used for heating and upgrading raw coal gas, and the other is used for oxygen storage. The first red coke heater (501) and the second red coke heater (502) are used alternately to heat the gas collected in the hot gas pipe (20). The gas in the hot gas pipe (20) is passed into the first red coke heater (501) for modification. When the temperature of the red coke in the first red coke heater (501) is lower than 900°C, the gas passing into the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is passed into the second red coke heater (502). At the same time, oxygen is introduced into the first red coke heater (501) to make the first red coke... The temperature in the heating furnace (501) is raised to 900℃-1000℃; when the temperature of the second red coke heating furnace (502) is lower than 900℃, the gas in the hot gas pipe (20) is stopped, and the gas in the hot gas pipe (20) is introduced into the first red coke heating furnace (501), while oxygen is introduced into the second red coke heating furnace (502) to raise the temperature in the second red coke heating furnace (502) to 900℃-1000℃; the above heating process is repeated to modify the gas in the hot gas pipe (20).

15. The method according to claim 7, characterized in that, The gas collected in the red coke heating furnace (50) includes the following components: CH4: 0-10 vol%, H2: 75-90 vol%, CO: 4-12 vol%, CO2: 0-1 vol%, N2: 0-4 vol%, C n H m 0-0.5% by volume; tar: 0-5 mg / Nm, naphthalene: 0-10 mg / Nm, BTX: 0-100 mg / Nm.

16. The method according to claim 7, characterized in that, The method further includes step 4): introducing the gas in the red coke heating furnace (50) into a dust collector (60) to remove dust from the gas in the red coke heating furnace (50).

17. The method according to claim 16, characterized in that, The method further includes step 5): introducing the gas in the dust collector (60) into the heating furnace (70), heating and collecting the gas in the dust collector (60) in the heating furnace (70); preferably, the temperature of the gas collected in the heating furnace (70) is 1050-1100℃.

18. The method according to claim 17, characterized in that, The heating furnace (70) is a tubular heating furnace.

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