Total-oxygen blast furnace carbon dioxide removal and utilization system

Abstract

The invention belongs to the technical field of total-oxygen blast furnace carbon dioxide removal, and discloses a total-oxygen blast furnace carbon dioxide removal and utilization system capable of realizing efficient removal and resource utilization of carbon dioxide with low energy consumption. Comprising a purification system used for carrying out dust removal treatment on total-oxygen blast furnace circulating gas; the pretreatment system is used for removing strongly acidic impurities in the circulating gas to obtain circulating gas; the circulating fan is used for boosting the circulating gas, and cooling and dehydrating the boosted circulating gas; the pressure swing adsorption system is used for separating desorbed gas from the circulating gas, the desorbed gas is carbon dioxide mixed gas containing a certain proportion of carbon monoxide, and the circulating gas subjected to adsorption and decarburization by the pressure swing adsorption system is heated and then enters the full-oxygen blast furnace; and the ammonia water absorption system is used for absorbing carbon dioxide in the desorption gas by using ammonia water to produce ammonium bicarbonate and separating out carbon monoxide tail gas, and the carbon monoxide tail gas is returned to the total-oxygen blast furnace or is used as fuel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide removal of oxygen blast furnace, and particularly relates to a carbon dioxide removal and utilization system of oxygen blast furnace. BACKGROUND

[0002] Traditional blast furnace ironmaking accounts for more than 95% of global iron production, but has high carbon emissions. The current main direction of ironmaking development is to carry out oxygen blast furnace top gas circulation and assist with carbon dioxide removal process on the basis of existing blast furnace facilities.

[0003] The existing carbon dioxide removal process mainly includes pressure swing adsorption (PSA) process and wet decarburization process, but both of them have certain defects: for the pressure swing adsorption (PSA) process, although the process energy consumption is low, a multi-stage adsorption tower is needed to separate carbon monoxide and carbon dioxide, which is large in equipment; and the carbon monoxide loss rate is high, the heat value of the desorption gas is low and cannot be utilized, resulting in energy waste and pollution. For the wet decarburization process (such as low-temperature methanol method and amine absorption method), a large amount of steam or electric energy is consumed for the regeneration of the absorption liquid, and the energy consumption accounts for more than 60% of the operating cost, and the system is suitable for high-purity demand, and is poor in economy for the oxygen blast furnace scene.

[0004] Although the oxygen blast furnace can reduce carbon emissions through gas circulation, the existing carbon dioxide removal technology cannot take into account low energy consumption and resource utilization. SUMMARY

[0005] In the oxygen blast furnace gas circulation process, in order to realize low energy consumption and efficient carbon dioxide removal and resource utilization, the present application provides a carbon dioxide removal and utilization system of oxygen blast furnace.

[0006] According to the carbon dioxide removal and utilization system of oxygen blast furnace, the system comprises: a purification system for dust removal treatment of the oxygen blast furnace circulating gas; a pretreatment system for removing strong acid impurities in the circulating gas to obtain circulating gas; a circulating fan for boosting the circulating gas, and the boosted circulating gas is subjected to cooling and dehydration treatment; a pressure swing adsorption system for separating desorption gas from the circulating gas, the desorption gas being carbon dioxide mixed gas containing a certain proportion of carbon monoxide, and the circulating gas after decarburization by the pressure swing adsorption system is heated and then introduced into the oxygen blast furnace; and an ammonia water absorption system for absorbing carbon dioxide in the desorption gas by using ammonia water to produce ammonium bicarbonate, and separating out carbon monoxide tail gas, which is returned to the oxygen blast furnace or used as fuel.

[0007] Further, the pressure swing adsorption system adopts pressure swing adsorption or vacuum pressure swing adsorption.

[0008] Further, the proportion of carbon monoxide loss in the desorption gas during the adsorption process of the pressure swing adsorption system is 5-15%, and the carbon dioxide removal efficiency of the circulating gas is greater than or equal to 90%.

[0009] Further, the pressure swing adsorption system is located behind the circulating fan, and the operating pressure is 0.3-0.6 MPa.

[0010] Further, the pressure swing adsorption system is located in front of the circulating fan, and the operating pressure is 0.15-0.3 MPa.

[0011] Further, the gas flow of the resolving gas is about 1 / 3 of the total amount of the circulating gas, the proportion of carbon dioxide in the resolving gas is about 4 / 5, and the proportion of carbon monoxide is about 1 / 5.

[0012] Further, the oxygen blast furnace is an oxygen top gas circulating blast furnace, and the oxygen concentration of the oxygen top gas circulating blast furnace is greater than or equal to 80%.

[0013] Further, the pressure swing adsorption system is connected with a resolving gas energy recovery device for recovering the pressure relief energy of the pressure swing adsorption system.

[0014] Further, the carbon monoxide tail gas is returned to the oxygen blast furnace after being pressurized by a compressor.

[0015] Further, the pressure of the circulating gas after being discharged from the oxygen blast furnace is 0.15-0.3 MPa, and the pressure after being pressurized by the circulating fan is 0.3-0.6 MPa.

[0016] Compared with the existing pressure swing adsorption (PSA) process (two-stage PSA for purifying CO), the oxygen blast furnace carbon dioxide removal and utilization system of the present application realizes ≥90% CO2 removal in a single-stage PSA / VPSA, allows the CO loss rate to be controlled at 5-15%, and eliminates the need for a second-stage PSA and its large equipment; compared with the existing wet decarburization, the oxygen blast furnace carbon dioxide removal and utilization system of the present application uses ammonia water absorption to generate ammonium bicarbonate, thereby realizing separation from unreacted carbon monoxide, eliminating the need for wet process heating or gas stripping to regenerate the absorption liquid, and reducing energy consumption by more than 40%, and eliminating waste liquid discharge. The gas operating pressure of the oxygen blast furnace carbon dioxide removal and utilization system of the present application is the normal production operating condition of the blast furnace, and no additional pressurization energy is required. By flexibly arranging the position of the pressure swing adsorption, recovering the pressure relief energy, and re-compressing the tail gas, the main energy consumption of the process is only about 0.25 MPa or 0.5 MPa of the pressure relief loss of the resolving gas, the overall power consumption of the system can be reduced by 10-20%, CO2 is theoretically zero-emission, the byproduct ammonium bicarbonate creates additional economic benefits, and the use of CO tail gas reduces external fuel procurement, so that the oxygen blast furnace is significantly superior to the prior art in terms of emission reduction, cost reduction, and efficiency improvement. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a structural schematic diagram of an oxygen blast furnace carbon dioxide removal and utilization system according to a first embodiment of the present application;

[0018] Figure 2 Structure diagram of a full-oxygen blast furnace carbon dioxide removal and utilization system according to a second embodiment of the present application. DETAILED DESCRIPTION

[0019] For better understanding of the purpose, structure and function of the present application, the present application is further described in detail below in combination with the drawings.

[0020] Figure 1 And Figure 2 A structure of a full-oxygen blast furnace carbon dioxide removal and utilization system 100 according to an embodiment of the present application is shown. As shown in Figure 1 And Figure 2 The full-oxygen blast furnace carbon dioxide removal and utilization system 100 can include a purification system 2 for dust removal treatment of circulating gas of the full-oxygen blast furnace 1, a pretreatment system 3 for removing strong acid impurities in the circulating gas to obtain circulating gas, a circulating fan 5 for boosting the circulating gas, and the boosted circulating gas is cooled and dehydrated, a pressure swing adsorption system 4 for separating desorption gas from the circulating gas, the desorption gas being carbon dioxide mixed gas containing a certain proportion of carbon monoxide, the circulating gas after decarburization by the pressure swing adsorption system 4 is heated and then enters the full-oxygen blast furnace 1, and an ammonia water absorption system 6 for absorbing carbon dioxide in the desorption gas by using ammonia water to produce ammonium bicarbonate and separate carbon monoxide tail gas, the carbon monoxide tail gas returns to the full-oxygen blast furnace 1 or is used as fuel.

[0021] The full-oxygen blast furnace carbon dioxide removal and utilization system 100 according to the embodiment of the present application works as follows. Figure 1In the preferred embodiment shown, the circulating gas discharged from the oxygen blast furnace first enters a purification system 2 (such as a bag filter, a cyclone dust collector, etc.), to remove dust particles (such as ore powder, coke powder) in the gas, to prevent subsequent equipment from being blocked or adsorbent from being poisoned; the dust-removed circulating gas enters a pretreatment system 3 (such as an acid washing tower, an alkali washing tower, or a dry adsorption tower), to remove strong acidic impurities (such as H2S, HCl, SO2, etc.), to avoid corroding the pipeline and the adsorbent, and to protect the adsorbent activity of the subsequent pressure swing adsorption system 4; the pretreated circulating gas enters a circulating fan 5 for pressure boosting, to overcome the system resistance and to provide sufficient operating pressure for the pressure swing adsorption; the pressure-boosted circulating gas enters a cooling and dehydration system (not shown in the figure, such as an indirect cooler, a freeze dryer), to reduce the temperature of the circulating gas so that the pressure swing adsorption system 4 can work at a suitable temperature, and to remove saturated water vapor to prevent water from condensing and blocking the adsorbent channels in the pressure swing adsorption stage; the dehydrated circulating gas enters the pressure swing adsorption system 4, in which the adsorbent selectively adsorbs carbon dioxide, and a small amount of carbon monoxide is also adsorbed, including the circulating gas for adsorbent regeneration and backwashing, to form desorption gas containing high-concentration carbon dioxide and a small amount of carbon monoxide; the decarbonated circulating gas enters a heating system (not shown in the figure, such as a hot blast stove or a heat exchanger), is heated, and then enters the oxygen blast furnace 1 as a reducing agent, to continue to participate in the reduction reaction of iron oxides, and to form a closed loop; the desorption gas enters an ammonia water absorption system 6, reacts with concentrated ammonia water to generate ammonium bicarbonate, and carbon monoxide does not participate in the reaction, but is separated in the form of tail gas; the separated carbon monoxide tail gas has two destinations: one is injected into the oxygen blast furnace 1 as a supplementary reducing agent after pressure boosting, and the other is directly used as fuel, for example, can be used in a hot blast stove or a boiler, thereby improving energy utilization, and of course can also be used for other purposes.

[0022] The oxygen blast furnace carbon dioxide removal and utilization system 100 of the embodiment of the present application separates the desorption gas containing carbon monoxide and carbon dioxide through the pressure swing adsorption system 4, directly utilizes the ammonia water absorption reaction to realize efficient separation of carbon monoxide and carbon dioxide, and avoids the energy consumption of wet regeneration; at the same time, the process is driven by reaction heat, realizing energy self-consistency. The oxygen blast furnace carbon dioxide removal and utilization system 100 of the embodiment of the present application realizes efficient removal of carbon dioxide, resource utilization of carbon monoxide, and production of ammonium bicarbonate product in a single system through the coupling process of “purification-pretreatment-pressure boosting-pressure swing adsorption-ammonia water absorption”, significantly reduces the carbon emissions of the oxygen blast furnace, creates byproduct value, and at the same time, the carbon monoxide tail gas can be fully recovered, realizing carbon resource closed loop. Experiments show that 0.55 tons of carbon dioxide can be fixed per ton of ammonium bicarbonate, and the total energy consumption of the system can be reduced by more than 80% compared with the wet method.

[0023] In a preferred embodiment, the pressure swing adsorption system 4 can employ pressure swing adsorption (PSA) or vacuum pressure swing adsorption (VPSA). This process is mature, compact, and can be operated stably in a wide pressure range of 0.15-0.6 MPa, thereby reducing the initial investment, and the vacuum pressure swing adsorption (VPSA) can deeply resolve and improve the carbon dioxide recovery rate (>95%). Preferably, activated carbon or silica gel can be used as the adsorbent for pressure swing adsorption, which is low in cost and strong in acid resistance.

[0024] According to the present application, the proportion of carbon monoxide loss into the desorption gas during the adsorption process of the pressure swing adsorption system 4 is preferably 5-15%, and the carbon dioxide removal efficiency in the circulating gas is ≥90%. The 5-15% of carbon monoxide loss is converted into a useful resource (non-emission) or recovered; the ≥90% of carbon dioxide removal rate ensures that the circulating gas meets the blast furnace recycling standard.

[0025] In a preferred embodiment as shown in Figure 1 , the pressure swing adsorption system 4 can be located after the circulating fan 5, and the operating pressure can be preferably 0.3-0.6 MPa. High-pressure operation (0.3-0.6 MPa) can improve the adsorption efficiency and reduce the amount of adsorbent; the desorption gas carries high-grade pressure energy (more than 60% can be recovered), which can reduce the equipment size and improve the single-tower processing capacity.

[0026] In a preferred embodiment as shown in Figure 2 , the pressure swing adsorption system 4 is located before the circulating fan 5, and the operating pressure is preferably 0.15-0.3 MPa. Low-pressure operation (0.15-0.3 MPa) can reduce the pressure relief energy loss, reduce the compressor load, and prolong the service life of the equipment, which is suitable for situations where the furnace top pressure is low or further energy saving is desired. In this embodiment, the pretreatment system 3 can have the functions of removing strong acidic impurities in the circulating coal gas to obtain the circulating gas and cooling and dehydrating the circulating gas. The separated carbon monoxide tail gas has two destinations: one is sent into the oxygen blast furnace 1 as a supplementary reducing agent after being boosted by the circulating fan 5, and the other is directly used as fuel, for example, can be used in a hot blast stove or a boiler, thereby improving the energy utilization rate, and of course can be used for other purposes as required.

[0027] According to the application, in a preferred embodiment, the gas flow of the resolving gas is preferably about 1 / 3 of the total circulating gas, and the proportion of carbon dioxide in the resolving gas is preferably about 4 / 5, and the proportion of carbon monoxide is preferably about 1 / 5. The gas flow of the resolving gas is set to about 1 / 3 of the total circulating gas, which can optimize the system balance and is conducive to maintaining the reaction and heat balance in the blast furnace; the proportion of carbon monoxide is preferably about 1 / 5, which is the result of balancing the gas required for the reverse blowing of the adsorbent regeneration, optimizing investment and operating costs under the condition that the carbon dioxide content of the circulating gas is not higher than the bearing capacity of the blast furnace. The settings of this embodiment can make the subsequent ammonia water absorption system 6 smaller in size, lower in adsorbent consumption, and the equipment investment and operating costs decrease simultaneously.

[0028] According to the application, the full-oxygen blast furnace 1 can be preferably a full-oxygen top coal gas circulating blast furnace, and the oxygen enrichment concentration of the full-oxygen top coal gas circulating blast furnace is ≥80%. By using the full-oxygen top coal gas circulating blast furnace with an oxygen enrichment concentration of ≥80%, the circulating gas amount is significantly reduced, and the power consumption of the circulating fan 5 and the scale of the pressure swing adsorption system 4 can be further reduced.

[0029] According to the application, the pressure swing adsorption system 4 can be connected with a resolving gas energy recovery device (not shown in the figure) for recovering the pressure relief energy of the pressure swing adsorption system. By setting the energy recovery device (such as a turboexpander) in the resolving stage, 30-60% of the pressure relief energy can be recovered for driving a generator or other sections, and the overall power consumption can be reduced by another 5-8%.

[0030] In the preferred embodiment shown in FIGS. Figure 1 and Figure 2 , the carbon monoxide tail gas can be returned to the full-oxygen blast furnace 1 after being pressurized by a compressor. This setting is used to solve the pressure matching problem of the carbon monoxide tail gas. The compressor can pressurize the carbon monoxide tail gas close to normal pressure to 0.3-0.6 MPa and return it to the full-oxygen blast furnace 1 for supplementing the reducing agent in the furnace; at the same time, it also avoids the additional cost of fuel pressurization and avoids energy waste and environmental pollution caused by external discharge.

[0031] According to the application, the pressure of the circulating coal gas after exiting the full-oxygen blast furnace 1 can be preferably 0.15-0.3 MPa, and the pressure after being pressurized by the circulating fan 5 is 0.3-0.6 MPa. The full-oxygen blast furnace carbon dioxide removal and utilization system 100 of the embodiment of the application fully utilizes the existing 0.15-0.3 MPa furnace top pressure of the full-oxygen blast furnace 1, pressurizes it to 0.3-0.6 MPa by the circulating fan 5, and then enters the subsequent sections, without the need for an additional high-pressure compressor, thereby reducing the power consumption and equipment cost.

[0032] According to the present application, instead of separately purifying and recycling carbon monoxide and carbon dioxide in the process, only carbon dioxide is roughly separated and concentrated, and then the raw material or intermediate product (ammonia) is directly reacted with carbon dioxide to produce products, and carbon monoxide and carbon dioxide are completely separated through product formation reaction, thereby saving the energy consumption required for the regeneration of the absorbent in the wet decarbonization process.

[0033] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A carbon dioxide removal and utilization system for an all-oxygen blast furnace, characterized in that, The application relates to a system for purifying circulating gas of a full-oxygen blast furnace, which comprises the following components: a purification system for dust removal of circulating gas of a full-oxygen blast furnace; a pretreatment system for removing strong acidic impurities in the circulating gas to obtain circulating gas; a circulating fan for boosting the pressure of the circulating gas, and the boosted circulating gas is cooled and dehydrated; a pressure swing adsorption system for separating desorption gas from the circulating gas, wherein the desorption gas is carbon dioxide mixed gas containing a certain proportion of carbon monoxide, and the circulating gas after decarburization by the pressure swing adsorption system is heated and then enters the full-oxygen blast furnace; an ammonia water absorption system for absorbing carbon dioxide in the desorption gas by using ammonia water to produce ammonium bicarbonate, and simultaneously separating carbon monoxide tail gas, which is returned to the full-oxygen blast furnace or used as fuel.

2. The full oxygen blast CO2 removal and utilization system according to claim 1, wherein, The pressure swing adsorption system adopts pressure swing adsorption or vacuum pressure swing adsorption.

3. The CO2 removal and utilization system for an oxygen blown blast furnace according to claim 2, wherein The proportion of carbon monoxide loss into the desorption gas during the adsorption process of the pressure swing adsorption system is 5-15%, and the carbon dioxide removal efficiency of the circulating gas is greater than or equal to 90%.

4. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The pressure swing adsorption system is located behind the circulating fan, and the operating pressure is 0.3-0.6 MPa.

5. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The pressure swing adsorption system is located in front of the circulating fan, and the operating pressure is 0.15-0.3 MPa.

6. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The gas flow of the desorption gas is 1 / 3 of the total amount of the circulating gas, the proportion of carbon dioxide in the desorption gas is 4 / 5, and the proportion of carbon monoxide is 1 / 5.

7. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The full-oxygen blast furnace is a full-oxygen top gas circulating blast furnace, and the oxygen enrichment concentration of the full-oxygen top gas circulating blast furnace is greater than or equal to 80%.

8. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The pressure swing adsorption system is connected with a desorption gas energy recovery device for recovering the pressure relief energy of the pressure swing adsorption system.

9. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The carbon monoxide tail gas is boosted by a compressor and then returned to the full-oxygen blast furnace.

10. The CO2 removal and utilization system for an oxygen blown blast furnace according to any one of claims 1 to 3, characterized in that, The pressure of the circulating gas after the full-oxygen blast furnace is 0.15-0.3 MPa, and the pressure of the circulating gas after the circulating fan is boosted is 0.3-0.6 MPa.

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