JP5567185B2 - Blast furnace gas separation method - Google Patents

Description

  The present invention relates to a method for separating blast furnace gas discharged from the top of a blast furnace furnace into gases each having respective gas components as main components.

At steelworks, coke ovens, blast furnaces, converters, and other facilities generate gas called by-product gas, which contains nitrogen, in addition to components that can be used as fuel, such as hydrogen, carbon monoxide, and methane. Contains carbon dioxide. Most of these by-product gases are used in applications that use heat generated by combustion in power plants, heating furnaces, etc., but as mentioned above, these by-product gases include nitrogen and dioxide. Since an inert component such as carbon is contained, the calorific value per volume is 700 to 4500 kcal / Nm ^3, which is low compared to propane gas and natural gas, which are common fuel gases. In particular, the blast furnace gas is about 700 kcal / Nm ³ and has the lowest amount of heat.

  This is because there are few fuel components such as hydrogen, carbon monoxide, and methane, and the amount of heat generated by combustion of these fuel components is consumed for heating nitrogen and carbon dioxide, which are components other than fuel components. It is. Incidentally, the blast furnace gas contains about 50 to 55% by volume of nitrogen and about 20 to 23% by volume of carbon dioxide.

  For this reason, several proposals have been made regarding methods for removing inert components from these by-product gases, particularly regarding methods for separating and recovering carbon dioxide from blast furnace gas due to recent requests for reduction of carbon dioxide emissions. .

  For example, Patent Document 1 discloses that a small amount of remaining combustible gas is obtained by burning a gas after separating carbon monoxide from a gas containing nitrogen, carbon monoxide, carbon dioxide such as blast furnace gas in the presence of a combustion catalyst. In addition, a method of removing an oxygen and producing an inert gas mainly containing nitrogen and carbon dioxide has been proposed. It has also been proposed to separate carbon dioxide from the inert gas to obtain high purity nitrogen.

  Further, in Patent Document 2, carbon dioxide and nitrogen in blast furnace gas are adsorbed on an alumina basis by a pressure fluctuation type adsorption separation method in which adsorption separation is performed by contacting with an adsorbent under pressure and then desorbing under reduced pressure. There has been proposed a method of producing a rich gas of carbon monoxide and hydrogen by selective adsorption and separation using an agent and porous polystyrene.

  Furthermore, in Patent Document 3, when carbon dioxide is separated and recovered from a by-product gas generated at an ironworks by a chemical absorption method, carbon dioxide is absorbed from the gas by a chemical absorption liquid, and then the chemical absorption liquid is heated to produce carbon dioxide. In the process of separating carbon, it has been proposed to use or utilize low-grade exhaust heat of 500 ° C. or less generated in steelworks.

JP-A 61-28446 Japanese Patent Laid-Open No. 62-193622 JP 2004-292298 A

  As proposed in Patent Documents 1 to 3 above, techniques for separating each component contained in by-product gas generated at an ironworks have been proposed, but none have been put into practical use. Have problems to be solved.

  For example, in Patent Document 1, carbon monoxide in a blast furnace gas is separated by an absorption method, but in this method, about 1% by volume of carbon monoxide remains in the gas after absorbing the carbon monoxide. In addition, hydrogen is not absorbed and remains as it is (see Patent Document 1, page 2, upper left column). These are completely combusted in a combustor provided at the subsequent stage of the separator. The amount of heat generated by the remaining carbon monoxide and hydrogen is a gas diluted with a large amount of nitrogen and carbon dioxide even though the amount of heat generated by the blast furnace gas is as large as 5%. For this reason, it is very difficult to effectively use the amount of heat generated in this combustor. Therefore, in Patent Document 1, it must be said that 5% of the amount of heat of the blast furnace gas is wasted.

  In Patent Document 2, an alumina-based adsorbent for adsorbing carbon dioxide in blast furnace gas and porous polystyrene for adsorbing nitrogen are packed in a single adsorption tower, and this adsorption tower is filled with blast furnace gas. Carbon dioxide and nitrogen are adsorbed to obtain a gas having a relatively increased carbon monoxide concentration and hydrogen concentration, but the recovery rate of carbon monoxide and hydrogen does not exceed 80%, and the remaining 20 % Of carbon monoxide and hydrogen will be exhausted as a low calorific gas mixed with carbon dioxide and nitrogen.

  In Patent Document 3, carbon dioxide in the blast furnace gas is separated and recovered by the chemical absorption method. However, the concentration of carbon dioxide in the blast furnace gas is about 20%, and the effect of increasing the amount of heat even by separation of carbon dioxide alone. However, the improvement effect is limited to about 25%, and a gas with a high calorific value cannot be obtained.

  In addition, there is a problem of input power as a problem common to any separation method. In Patent Document 1, heating or depressurization at 100 to 150 ° C. for regeneration of the absorbing solution, and in Patent Document 2, pressurization to 2 ata during adsorption is performed. And pressure reduction to 0.1 at the time of desorption, Patent Document 3 requires heating at 120 ° C. for regeneration of the absorbing solution, and heat source or power treatment for these is necessary even if waste heat is used. .

  As described above, it is important to remove the inactive components in the by-product gas of the steelworks and increase the amount of heat from the viewpoint of reducing carbon dioxide emissions and saving energy. It shows that the improvement of the recovery rate of carbon oxide and hydrogen and the reduction of energy or cost spent for the separation operation are problems.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to produce a reformed blast furnace gas having a high calorific value by separating and removing carbon dioxide and nitrogen from the blast furnace gas. It is an object of the present invention to provide a blast furnace gas separation method capable of efficiently recovering each gas at a high recovery rate in separating the gas into gases mainly composed of the respective components.

  In order to solve the above problems, the present inventors have studied the improvement of the recovery rate in the separation of blast furnace gas and the reduction of energy or cost from various viewpoints. The knowledge that it is feasible by combining the method and the separation method appropriately was obtained.

  The present invention has been made on the basis of the above knowledge, and the method for separating blast furnace gas according to the first invention uses a three-stage gas separation and purification device to separate each component of the blast furnace gas discharged from the blast furnace top. When separating into the main gas, the first stage, gas separation and purification apparatus consisting of a chemical absorption apparatus that separates carbon dioxide by absorption, blast furnace gas, gas composed of carbon dioxide and inevitable impurity gas components, nitrogen Gas separation and purification apparatus comprising an adsorption separation device that separates carbon monoxide by adsorption and carbon monoxide and hydrogen, and an inevitable impurity gas component, and separates the carbon monoxide by adsorption. A gas composed of nitrogen, carbon monoxide and hydrogen, and an unavoidable impurity gas component, separated by a purifier, and a gas composed of nitrogen and an unavoidable impurity gas component Separated into a gas composed of carbon monoxide and unavoidable impurity gas components and a gas composed of hydrogen and nitrogen and unavoidable impurity gas components, and separated into the third stage gas at the outlet side of the second stage adsorption separation apparatus. As a purification device, a hydrogen permeable membrane or an adsorbent that adsorbs components other than hydrogen is arranged, and hydrogen and unavoidable from gas composed of hydrogen and nitrogen and unavoidable impurity gas components separated from the second stage adsorption separation device. It is characterized by separating a gas composed of a typical impurity gas component.

  In the blast furnace gas separation method according to the second invention, in the first invention, an adsorbent that adsorbs components other than hydrogen is disposed as the third-stage gas separation and purification device, and hydrogen and unavoidable by the adsorbent. When separating the gas composed of the impurity gas component, the component adsorbed on the adsorbent is removed by a degassing operation using reduced pressure, a cleaning operation using hydrogen, or a reverse cleaning operation.

  According to the present invention, when separating the blast furnace gas mainly composed of hydrogen, nitrogen, carbon monoxide and carbon dioxide into the respective gas components, carbon dioxide which is most easily separated is first separated. Blast furnace gas can be separated, and since the separation is performed using a two-stage gas separation and purification apparatus, each gas can be separated at a high separation rate. Furthermore, when hydrogen is separated using a third-stage gas separation and purification device, high concentration hydrogen can also be recovered from the blast furnace gas at a high recovery rate. As a result, high concentration hydrogen and high concentration hydrogen can be recovered. A reformed blast furnace gas containing a higher amount of heat and containing carbon monoxide can be obtained, and the input energy and cost spent for separation can be reduced by the effect.

It is process drawing which shows the example of 1st embodiment of this invention. It is process drawing which shows the example of 2nd embodiment of this invention. It is process drawing which shows the example of 3rd embodiment of this invention. In the first embodiment of the present invention, it is a diagram schematically showing a separation operation when a pressure swing adsorption device is used in the first and second gas separation steps. FIG. 5 is a schematic diagram of a separation operation when the hydrogen separator is a membrane separator in the first embodiment of the present invention shown in FIG. 4. FIG. 5 is a schematic diagram of a separation operation when the hydrogen separation device is an adsorption separation device in the first embodiment of the present invention shown in FIG. 4. FIG. 5 is a schematic diagram of a separation operation in a case where a hydrogen separator is deaerated in the first embodiment of the present invention shown in FIG. 4. FIG. 5 is a schematic diagram of a separation operation in the case where the hydrogen separator is washed with hydrogen in the first embodiment of the present invention shown in FIG. 4. FIG. 5 is a schematic diagram of a separation operation when the hydrogen separator is back-washed with hydrogen in the first embodiment of the present invention shown in FIG. 4.

  Hereinafter, the present invention will be specifically described.

  The composition of the blast furnace gas is as follows: carbon monoxide: 21.1 to 26.2% by volume, carbon dioxide: 19.3 to 23.2% by volume, hydrogen: 2.9 to 5.3% by volume, nitrogen: 52.5 ~ 59.2% by volume (4th edition Handbook of Steel (CD-ROM) No.1 Volume 2 Steelmaking and Steelmaking, issued July 30, 2002, see Table 42-5-7 (2000)) For the purpose of producing a reformed blast furnace gas having a higher calorie from this blast furnace gas, when separating the blast furnace gas into respective gas components, in the present invention, a two-stage gas separation and purification apparatus is used. The first stage gas separation and purification apparatus separates the blast furnace gas into a gas composed of carbon dioxide and unavoidable impurity gas components, and a gas composed of nitrogen, carbon monoxide and unavoidable impurity gas components. The nitrogen gas separated by the first-stage gas separation and purification device was separated by the first gas separation and purification device. The gas comprising carbon monoxide and unavoidable impurity gas component, a gas consisting of nitrogen and unavoidable impurity gas component is separated into a gas comprising carbon monoxide and unavoidable impurity gas component.

  Here, inevitable impurity gas components are separated in addition to the trace components contained in the blast furnace gas, other than the target components to be separated among the above four components (carbon monoxide, carbon dioxide, hydrogen, nitrogen). It is a gas component that is incidentally mixed in the efficiency and includes a maximum of 20% by volume. In addition, in the gas which consists of nitrogen, carbon monoxide, and an unavoidable impurity gas component, hydrogen may be included as an unavoidable impurity gas component. That is, among the gases discharged from the adsorption separation device, “gas consisting of hydrogen and nitrogen and inevitable impurity gas components” may be separated, and “gas consisting of nitrogen and carbon monoxide and inevitable impurity gas components”. Is a concept that includes both the case of separating “a gas composed of hydrogen and nitrogen and inevitable impurity gas components” and the case of not separating them.

  Thus, according to the present invention, carbon dioxide is separated from the blast furnace gas in the first stage gas separation step, so the load in the carbon monoxide separation step, which is the second stage gas separation step, is reduced. And efficient separation becomes possible.

As the first-stage gas separation and purification apparatus, an adsorption separation apparatus that separates carbon dioxide (hereinafter also referred to as “CO ₂ ”) by adsorption, or a chemical absorption apparatus that separates carbon dioxide by absorption can be used. As the second stage gas separation and purification apparatus, as in the first stage gas separation and purification apparatus, an adsorption separation apparatus that separates carbon monoxide (hereinafter also referred to as “CO”) by adsorption, or carbon monoxide is used. Chemical absorbers that separate by absorption can be used.

  As the adsorption separation method used as the first-stage and second-stage gas separation and purification apparatus, a pressure swing adsorption apparatus (PSA method), a temperature swing adsorption method (TSA method), etc. can be used. Chemical absorption devices used as gas separation and purification devices for eyes include amine method, chilled ammonia method, etc. for carbon dioxide, and copper chloride / hexamethyl phosphate triamide or chloride for carbon monoxide. A method using aluminum / toluene as an absorbing solution can be used.

  In addition, as a combination of the first stage and the second stage separation apparatus, an adsorption method + adsorption method (first embodiment) or an absorption method + adsorption method (second embodiment), and further an adsorption method + absorption There is a method (third embodiment), but in the case of the absorption method in both the first stage and the second stage, hydrogen cannot be separated and is lost, which is not preferable.

  Hydrogen having an adsorbent that adsorbs a component other than hydrogen permeable membrane or hydrogen as a third-stage gas separation / purification device on the outlet side of the adsorption / separation device (which may be either the first stage or the second stage) It is also possible to separate high-purity hydrogen by arranging a separation device.

  Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 is a process diagram showing a first embodiment of the present invention, in which a CO ₂ adsorption separation device is arranged as a first-stage gas separation step (S1), and blast furnace gas is produced by this CO ₂ adsorption separation device. Hydrogen (hereinafter also referred to as “H ₂ ”) and nitrogen (hereinafter also referred to as “N ₂ ”), a gas composed of inevitable impurity gas components (discharged from the separation device at the initial stage of discharge), nitrogen and carbon monoxide In addition, it is separated into a gas composed of inevitable impurity gas components (discharged in the middle of the discharge) and a gas composed of carbon dioxide and inevitable impurity gas components (discharged last), and the second stage A CO adsorption / separation device is arranged as the gas separation step (S2), and is composed of nitrogen and carbon monoxide and inevitable impurity gas components separated by the CO adsorption separation device in the first-stage gas separation step (S1). Gas is separated into a gas composed of nitrogen and inevitable impurity gas components (exhausted from the separation device at the initial stage of discharge) and a gas composed of carbon monoxide and inevitable impurity gas components (exhausted most recently). To do.

  Here, what is expressed as “discharge” is a general term for the steps exhausted from the adsorption tower in each step of the pressure (temperature) swing adsorption method (adsorption, decompression, washing, degassing, etc.) “Initial”, “medium term”, and “latest” indicate the temporal context within one cycle that summarizes each process.

  Here, the reason for separating carbon dioxide in the first stage gas separation step is as follows. That is, when separating with an adsorption separation device, the adsorption power of each component to the adsorbent is generally strong in the order of “hydrogen << nitrogen <carbon monoxide << carbon dioxide”. The difference in adsorption force is generally smaller than the difference in adsorption force between these and other components. This is because when carbon dioxide is adsorbed at a lower pressure or at a higher temperature when the components are separated from a mixed gas containing hydrogen, nitrogen, carbon monoxide, and carbon dioxide, it is most easily separated. That is, the power consumed for separation can be minimized. In addition, since the separation power by the adsorption method is necessary for components that are not separated, the separation of low-concentration components requires a large amount of power because there are a large amount of other components that are not subject to separation. .

  Furthermore, a hydrogen separation device is arranged as the third-stage gas separation step (S3), and hydrogen and nitrogen and inevitable impurity gas components separated by the hydrogen separation device in the first-stage gas separation step (S1). A gas comprising hydrogen and inevitable impurity gas components is separated from the gas comprising As described above, in the present invention, the third-stage gas separation step (S3) is not essential, and an attempt is made to obtain a reformed blast furnace gas having a heat quantity per volume of three times or more compared to the blast furnace gas. In this case, the gas composed of hydrogen and nitrogen and inevitable impurity gas components separated by the first-stage gas separation step (S1) and the first oxidation separated by the second-stage gas separation step (S2). By mixing carbon and a gas composed of inevitable impurity gas components, the object can be sufficiently satisfied.

FIG. 2 is a process diagram showing a second embodiment of the present invention, in which a CO ₂ absorption separation device is arranged as a first-stage gas separation step (S1), and blast furnace gas is converted by this CO ₂ absorption separation device. Separated into a gas composed of nitrogen and carbon monoxide and hydrogen and inevitable impurity gas components (exhausted from the absorption tower) and a gas composed of carbon dioxide and inevitable impurity gas components (exhausted from the regeneration tower), Further, a CO adsorption / separation device is arranged as the second stage gas separation step (S2), and by this CO adsorption / separation device, nitrogen, carbon monoxide and hydrogen separated by the first stage gas separation step (S1), and Gas composed of inevitable impurity gas components, hydrogen and nitrogen, and gas composed of inevitable impurity gas components (discharged from the separation device at the initial stage of discharge), nitrogen and inevitable impurity gas The gas is separated into a component gas (discharged in the middle of the discharge) and a gas composed of carbon monoxide and inevitable impurity gas components (discharged last).

  The reason why carbon dioxide is separated first in the second embodiment is the same as the reason described in the first embodiment, and is for reducing the load of the second-stage gas adsorption separation process.

  Furthermore, a hydrogen separation device is arranged as the third-stage gas separation step (S3), and hydrogen and nitrogen and inevitable impurity gas separated by the hydrogen separation device in the second-stage gas separation step (S2). A gas composed of hydrogen and inevitable impurity gas components is separated from the gas composed of components. Here, it is the same as in the first embodiment that the third-stage gas separation step (S3) is not essential.

FIG. 3 is a process diagram showing a third embodiment of the present invention, in which a CO ₂ adsorption separation device is arranged as the first stage gas separation step (S1), and the blast furnace gas is converted by this CO ₂ adsorption separation device. Gas consisting of hydrogen and nitrogen and unavoidable impurity gas components (discharged from the separation device at the beginning of discharge), and gas consisting of nitrogen and carbon monoxide and unavoidable impurity gas components (discharged in the middle of the discharge) ) And a gas composed of carbon dioxide and unavoidable impurity gas components (most recently discharged), and a CO absorption / separation device is disposed as the second stage gas separation step (S2). The gas composed of nitrogen and carbon monoxide and unavoidable impurity gas components separated by the separation device in the first stage gas separation step (S1) is converted into a gas composed of nitrogen and unavoidable impurity gas components. And the gas composed of carbon monoxide and inevitable impurity gas components (discharged from the regeneration tower).

  Furthermore, a hydrogen separation device is arranged as the third-stage gas separation step (S3), and hydrogen and nitrogen and inevitable impurity gas components separated by the hydrogen separation device in the first-stage gas separation step (S1). A gas composed of hydrogen and inevitable impurity gas components is separated from the gas composed of Here, it is the same as in the first embodiment that the third-stage gas separation step (S3) is not essential.

  The first embodiment of the present invention will be described in more detail with reference to actual examples.

FIG. 4 shows a CO ₂ adsorption separation device in the first stage gas separation step (S1) and a CO adsorption separation device in the second stage gas separation step (S2) in the first embodiment of the present invention. Both schematically show separation operations when using a pressure swing adsorption device (PSA). Reference numeral 1 in FIG. 4 denotes a pressure swing adsorption device for CO ₂ adsorption (hereinafter referred to as “CO ₂ -PSA device”). )), Gas source 2 is an adsorption tower of a CO ₂ -PSA apparatus (hereinafter referred to as “CO ₂ -PSA adsorption tower”), and numeral 3 is a pressure swing adsorption apparatus for CO adsorption (hereinafter referred to as “CO ₂ -PSA adsorption tower”). The raw material gas holder of “CO-PSA apparatus”, reference numeral 4 is an adsorption tower of the CO-PSA apparatus (hereinafter referred to as “CO-PSA adsorption tower”), and reference numeral 5 is the hydrogen separator described above. . The distribution state of each gas component in the CO ₂ -PSA adsorption tower 2 and the CO-PSA adsorption tower 4 is a schematic expression for explanation, and the actual gas distribution in the tower is as shown in the figure. I don't mean.

The blast furnace gas discharged from the blast furnace is introduced into the raw material gas holder 1 of the CO ₂ -PSA apparatus, and the raw material gas holder 1 returns from a CO ₂ -PSA adsorption tower 2 described later, nitrogen, carbon monoxide, and carbon dioxide. After being mixed with carbon d and a gas d composed of unavoidable impurity gas components, it is introduced into the CO ₂ -PSA adsorption tower 2 from the raw material gas holder 1. In this case, it is preferable to remove dust (solid particles), mist (liquid fine particles), moisture and sulfur in the blast furnace gas in advance before introducing the blast furnace gas into the raw material gas holder 1. This is because dust causes a reduction in capacity due to the clogging of the pores of the adsorbent installed in the CO ₂ -PSA adsorption tower 2, and mist and moisture have higher adsorbability with the adsorbent than carbon dioxide. In addition to relatively lowering the carbon dioxide adsorption capacity, the deterioration of the adsorbent is promoted, and the sulfur content causes a decrease in capacity due to poisoning of the adsorption point of the adsorbent.

Any adsorbent filled in the CO ₂ -PSA adsorption tower 2 can be used as long as it can separate hydrogen, nitrogen, carbon monoxide, and carbon dioxide to some extent, and is not particularly specified. Commercially available activated carbon and zeolite can be used. Moreover, although the pressure at the time of adsorption | suction and the pressure at the time of desorption are not specified in particular, 100-500 kPa and a desorption pressure are 5-100 kPa from the ease of operation.

As shown in FIG. 4, the gas a introduced into the CO ₂ -PSA adsorption tower 2 from the source gas holder 1 (a gas composed of blast furnace gas and circulating N ₂ , CO, CO ₂ and inevitable impurity gas components) is as shown in FIG. A gas b composed of hydrogen and nitrogen and inevitable impurity gas components; a gas c composed of nitrogen and carbon monoxide and inevitable impurity gas components; a gas d composed of nitrogen, carbon monoxide and carbon dioxide and inevitable impurity gas components; It is separated into a gas e composed of carbon dioxide and inevitable impurity gas components.

Although the gas b composed of hydrogen, nitrogen and inevitable impurity gas components can be used as a fuel gas in the ironworks as it is, the gas j composed of hydrogen and inevitable impurity gas components is further provided by providing the hydrogen separator 5. In other words, it can be separated into high-concentration hydrogen. The gas k consisting of nitrogen and carbon monoxide and the inevitable impurity gas component separated from the gas b consisting of hydrogen and nitrogen and the inevitable impurity gas component is recovered in the CO ₂ -PSA raw material gas holder 1 or Although it can be recovered in the raw material gas holder 3 of the CO-PSA apparatus, if the separation power is increased when the carbon monoxide concentration is low and recovered, it is mixed with air with a catalyst or the like and burned. Dissipated into the atmosphere. The hydrogen separation device 5 may be a PSA device that strongly adsorbs gas components other than hydrogen (that is, nitrogen), and an adsorbent for CO _{2 is} disposed on the upper portion of the CO ₂ -PSA adsorption tower 2 as an adsorbent. It may be filled separately. Alternatively, a hydrogen separation membrane using molecular size may be used.

A gas c composed of nitrogen and carbon monoxide and inevitable impurity gas components is sent to the raw material gas holder 3 of the subsequent CO-PSA apparatus, and a gas d composed of nitrogen, carbon monoxide and carbon dioxide and inevitable impurity gas components. Is sent to the raw material gas holder 1 of the CO ₂ -PSA apparatus as described above and mixed with the blast furnace gas. The separated gas e composed of carbon dioxide and inevitable impurity gas components is high-purity CO ₂ having a purity of 99% or more, and can be used for inert gas or dry ice.

In the CO ₂ -PSA apparatus, operations of gas introduction from the raw material gas holder 1 to the CO ₂ -PSA adsorption tower 2 and gas discharge from the CO ₂ -PSA adsorption tower 2 are repeatedly performed.

The gas c composed of nitrogen and carbon monoxide and inevitable impurity gas components separated by the CO ₂ -PSA adsorption tower 2 is sent to the raw material gas holder 3 of the subsequent CO-PSA apparatus. After being mixed with nitrogen and carbon monoxide and a gas h composed of unavoidable impurity gas components returning from the CO-PSA adsorption tower 4 described later, it is introduced into the CO-PSA adsorption tower 4 as a gas f from the raw material gas holder 3. Is done.

  Any adsorbent filled in the CO-PSA adsorption tower 4 can be used as long as carbon monoxide can be separated to some extent, and is not particularly specified. A zeolite in which monovalent copper is supported or ion-exchanged is preferable because of its excellent ability to adsorb carbon monoxide. Moreover, although the pressure at the time of adsorption | suction and the pressure at the time of desorption are not specified in particular, 100-500 kPa and the desorption pressure are 5-100 kPa from the ease of operation.

The gas f introduced into the CO-PSA adsorption tower 4 from the raw material gas holder 3 is a gas g composed of nitrogen and inevitable impurity gas components, a gas composed of nitrogen and carbon monoxide, and inevitable impurity gas components as shown in FIG. h, separated into a gas i comprising carbon monoxide and inevitable impurity gas components. The gas g composed of nitrogen and inevitable impurity gas components is high-purity N ₂ having a purity of about 99% and can be used as an inert gas in a converter or the like. The gas h composed of nitrogen and carbon monoxide and inevitable impurity gas components is sent to the raw material gas holder 3 as described above. The gas i composed of carbon monoxide and inevitable impurity gas components is high-purity CO having a purity of 99% or more, can be used as a fuel gas having a calorific value of 3000 kcal / Nm ³ or more, and is also useful as a chemical raw material.

  In the CO-PSA apparatus, the operation of gas introduction from the raw material gas holder 3 to the CO-PSA adsorption tower 4 and gas discharge from the CO-PSA adsorption tower 4 are repeatedly performed.

In this way, high-purity H ₂ , CO ₂ , N ₂ , and CO are separated from the blast furnace gas with high efficiency and high separation rate.

  When the hydrogen separation device 5 is installed, the hydrogen separation device 5 may be a PSA device that strongly adsorbs gas components other than hydrogen as described above, or may be a hydrogen separation membrane. However, when a PSA device that strongly adsorbs gas components other than hydrogen is used, when the adsorbent is broken by components other than hydrogen, a degassing operation by decompression, or a cleaning operation or reverse cleaning operation by hydrogen is performed. It is preferable. It is possible to minimize the loss of carbon monoxide and nitrogen by performing a degassing operation under reduced pressure, or a cleaning operation or reverse cleaning operation with hydrogen.

  FIG. 5 shows a case where the hydrogen separator 5 is a membrane separator in the first embodiment. The gas k consisting of carbon monoxide and nitrogen and inevitable impurity gas components separated and discharged simultaneously with the separation of the gas j (high purity hydrogen gas) consisting of hydrogen and inevitable impurity gas components by the hydrogen separator 5 is: When the concentration of hydrogen contained in the separated exhaust gas is high, it is introduced into the raw material gas holder 1, and when the concentration of hydrogen contained in the separated exhaust gas is low, it is introduced into the raw material gas holder 3.

  FIG. 6 shows a case where the hydrogen separation device 5 is an adsorption device in the first embodiment. A gas b composed of hydrogen and nitrogen and inevitable impurity gas components is introduced into the hydrogen separator 5 to separate a gas j (high-purity hydrogen gas) composed of hydrogen and inevitable impurity gas components.

  When the hydrogen separation device 5 is an adsorption device, a schematic diagram of the separation operation when performing degassing operation of the adsorption device by decompression after separation of the gas j composed of hydrogen and inevitable impurity gas components is shown in FIG. Further, FIG. 8 shows a schematic diagram of a separation operation when performing a cleaning operation of the adsorption device with hydrogen, and FIG. 9 shows a schematic diagram of a separation operation when performing a reverse cleaning operation of the adsorption device with hydrogen. Here, the cleaning operation with hydrogen means a cleaning operation in the forward direction, and means that cleaning hydrogen gas is introduced in the same direction as the gas is introduced during adsorption. Similarly, the reverse cleaning operation with hydrogen gas means a reverse cleaning operation, which means that cleaning hydrogen gas is introduced in a direction opposite to the direction in which gas is introduced during adsorption.

When the hydrogen separator 5 is an adsorber and the deaeration operation of the adsorber is performed, as shown in FIG. 7, the CO and N ₂ remaining in the hydrogen separator 5 are exhausted by a vacuum pump or the like. 6 to discharge. The separated exhaust gas 1 mainly composed of CO and N ₂ is introduced into the raw material gas holder 1 when the concentration of hydrogen contained in the separated exhaust gas is high, and is contained in the separated exhaust gas. When the concentration of hydrogen to be produced is low, it is introduced into the raw material gas holder 3.

Further, in the case of performing the cleaning operation of the adsorption device with hydrogen after the separation of the gas j composed of hydrogen and inevitable impurity gas components, as shown in FIG. 8, the separated gas j composed of hydrogen and inevitable impurity gas components. Is introduced into the hydrogen separator 5 by a blower 7 such as a blower, and the gas composed of CO and N ₂ and inevitable impurity gas components remaining in the hydrogen separator 5 is discharged. Gas consisting discharged CO and N ₂ and H ₂ as well as unavoidable impurity gas component m, when the concentration of hydrogen contained in the separation exhaust gas is high is introduced into the feed gas holder 1, the separation discharge When the concentration of hydrogen contained in the gas is low, it is introduced into the raw material gas holder 3.

Similarly, when performing a reverse cleaning operation of the adsorption device with hydrogen, as shown in FIG. 9, the separated gas j consisting of hydrogen and unavoidable impurity gas components is introduced into the hydrogen separation device 5 by the blower 7. The gas composed of CO and N ₂ remaining in the hydrogen separator 5 and unavoidable impurity gas components is discharged. Discharged CO and N ₂ and H ₂ as well as gas n the unavoidable impurity gas component, when the concentration of hydrogen contained in the separation exhaust gas is high is introduced into the feed gas holder 1, the separation discharge When the concentration of hydrogen contained in the gas is low, it is introduced into the raw material gas holder 3.

  In this case, since it is not necessary to install extra piping or the like, a reverse cleaning operation with hydrogen is more preferable. 5 to 9, the configuration other than the above is the same as that of FIG. 4, and the same portions are denoted by the same reference numerals and the description thereof is omitted.

  Next, the blast furnace gas separation method according to the present invention, that is, the case where the first gas separation step is the carbon dioxide separation step and the second gas separation step is the carbon monoxide separation step (“the present invention”). On the contrary, when the first gas separation step is a carbon monoxide separation step and the second gas separation step is a carbon dioxide separation step (referred to as “Comparative Example”). Table 1 shows the difference in input power required for gas separation.

  As shown in Table 1, it can be seen that when the first gas separation step is the carbon dioxide separation step, the input power can be reduced as compared to the case where the gas separation step is not. That is, in the blast furnace gas separation method according to the present invention, the blast furnace gas is separated with a small input energy.

1 raw material gas holder 2 CO _2-PSA adsorption tower 3 source gas holder 4 CO-PSA adsorption tower 5 hydrogen separator 6 exhaust device 7 blower S1 first stage gas separation process S2 second stage gas separation process S3 third stage Gas separation process

Claims (2)

  When separating the blast furnace gas discharged from the top of the blast furnace into gas mainly composed of each component using a three-stage gas separation and purification device, a gas composed of a chemical absorption device that separates carbon dioxide by absorption in the first stage Separation and purification equipment separates the blast furnace gas into a gas composed of carbon dioxide and unavoidable impurity gas components, and a gas composed of nitrogen, carbon monoxide and hydrogen, and unavoidable impurity gas components. A gas consisting of nitrogen and carbon monoxide and hydrogen and an unavoidable impurity gas component separated by the gas separation and purification device of the first stage by a gas separation and purification device comprising an adsorption separation device for separating carbon by adsorption, Gas consisting of inevitable impurity gas components, gas consisting of carbon monoxide and inevitable impurity gas components, hydrogen and nitrogen, and inevitable impurities Gas adsorbing agent that adsorbs a component other than hydrogen permeable membrane or hydrogen as a third-stage gas separation and purification device is arranged on the outlet side of the second-stage adsorption separation device. A method for separating blast furnace gas, characterized in that hydrogen and nitrogen separated from the second stage adsorption separation apparatus and gas composed of unavoidable impurity gas components are separated from gas composed of hydrogen and unavoidable impurity gas components. .   Components adsorbed on the adsorbent when an adsorbent that adsorbs components other than hydrogen is arranged as the third-stage gas separation and purification device, and the gas composed of hydrogen and inevitable impurity gas components is separated by the adsorbent. The blast furnace gas separation method according to claim 1, wherein the gas is removed by a degassing operation under reduced pressure, a cleaning operation with hydrogen, or a reverse cleaning operation.

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