Method and system for carbon neutralization in lime kiln off-gas

Abstract

The application relates to the technical field of tail gas treatment, in particular to a method and system for carbon neutralization in lime kiln tail gas; the method comprises the following steps: obtaining liquid steel slag after a converter and lime kiln tail gas respectively; performing pressure swing adsorption on the lime kiln tail gas to obtain first CO2 gas; introducing the first CO2 gas into the first treated steel slag to perform an oxidation-reduction reaction, then performing second heat exchange and post-treatment to obtain second CO2 gas and CO gas respectively; returning the second CO2 gas to the blowing to realize carbon cycle; collecting and storing the CO gas to realize carbon neutralization; the system comprises a lime kiln tail gas collecting part, a steel slag reaction part, a gas treatment part and a control part; the utilization of CO2 in the lime kiln tail gas can improve the heat energy utilization rate of the steel slag.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tail gas treatment, in particular to a method and system for carbon neutralization of lime kiln tail gas. BACKGROUND

[0002] Since the steel industry, the calcium carbide industry, the alumina industry, the refractory material industry, etc. are all large consumers of lime, and lime is mostly burned in lime kilns, and during the lime burning stage, the tail gas generated contains a large amount of CO2, and the temperature of the steel slag generated during the steelmaking stage can reach above 1550℃, and the heat content value reaches 2000 MJ / t, which is a high-quality heat energy resource, but during the heat energy utilization stage, the steel slag has low cementitiousness and stability, resulting in low heat energy utilization rate of the steel slag.

[0003] If the CO2 in the lime kiln tail gas is applied to the heat energy recovery of the steel slag, the CO2 recovery rate and utilization rate will be further improved, and therefore, how to improve the utilization rate of the CO2 in the lime kiln tail gas to achieve the purpose of carbon neutralization is a technical problem that needs to be solved at present. SUMMARY

[0004] The present application provides a method and system for carbon neutralization of lime kiln tail gas to solve the technical problem that the CO2 in the lime kiln tail gas is difficult to recover and utilize in the prior art.

[0005] In a first aspect, the present application provides a method for carbon neutralization of lime kiln tail gas, the method comprising:

[0006] obtaining liquid steel slag after converter and lime kiln tail gas respectively;

[0007] performing pressure swing adsorption on the lime kiln tail gas to obtain a first CO2 gas;

[0008] introducing the first CO2 gas into the first treated steel slag to perform an oxidation-reduction reaction, and then performing a second heat exchange and post-treatment to obtain a second CO2 gas and a CO gas respectively;

[0009] returning the second CO2 gas to the blowing to be utilized to achieve carbon cycle;

[0010] collecting and storing the CO gas to achieve carbon neutralization.

[0011] Optionally, the blowing comprises blowing in a side blowing manner.

[0012] Optionally, after obtaining the liquid steel slag after the converter and the lime kiln tail gas respectively, the method further comprises:

[0013] The liquid steel slag is subjected to side blowing, first heat exchange and dust removal, and then gas collection, to obtain exhaust gas and first treated steel slag, respectively;

[0014] According to the oxygen content of the exhaust gas, it is determined whether to inject carbon dioxide.

[0015] If so, the lime kiln exhaust gas is subjected to pressure swing adsorption to obtain first CO2 gas.

[0016] Optionally, according to the oxygen content of the exhaust gas, it is determined whether to inject carbon dioxide, specifically including:

[0017] The oxygen content in the exhaust gas and the standard oxygen content in the exhaust gas are obtained, respectively.

[0018] According to the size of the oxygen content and the standard oxygen content, it is determined whether to inject carbon dioxide.

[0019] If the oxygen content is less than the standard oxygen content, the lime kiln exhaust gas is subjected to pressure swing adsorption to obtain first CO2 gas.

[0020] If the oxygen content is greater than or equal to the standard oxygen content, the side blowing is continued.

[0021] Optionally, the first CO2 gas is introduced into the first treated steel slag for decarburization reaction, and then subjected to second heat exchange and post-treatment, to obtain second treated steel slag.

[0022] According to the temperature of the second treated steel slag, it is determined whether to perform carbon sequestration treatment on the second CO2 gas.

[0023] If so, the second CO2 gas is introduced into the second treated steel slag, and then subjected to third heat exchange and gas collection, to obtain collection gas and third treated steel slag, respectively.

[0024] According to the temperature of the collection gas, it is determined whether to stop aeration.

[0025] If so, the third treated steel slag is poured out to obtain steel slag with excellent performance.

[0026] Optionally, according to the temperature of the second treated steel slag, it is determined whether to perform carbon sequestration treatment on the second separated CO2 gas, specifically including:

[0027] The actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag are obtained.

[0028] According to the size of the actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag, it is determined whether to perform carbon sequestration treatment on the second CO2 gas.

[0029] If the actual temperature of the second treated steel slag is less than the standard temperature of the second treated steel slag, the second CO2 gas is introduced into the second treated steel slag, and then gas collection is performed to obtain collected gas and third treated steel slag, respectively;

[0030] If the actual temperature of the second treated steel slag is greater than or equal to the standard temperature of the second treated steel slag, the second CO2 gas is returned to the CO2 blowing.

[0031] In a second aspect, the present application provides a system for carbon neutralization of lime kiln tail gas, which is suitable for the method of the first aspect, and comprises:

[0032] a lime kiln tail gas collection part, which comprises a lime kiln collection unit, a first pressure swing adsorption unit, and a carbon dioxide storage unit, the carbon dioxide storage unit is provided with a first feed port and a second feed port, the discharge port of the lime kiln collection unit is connected to the feed port of the first pressure swing adsorption unit to separate CO2 in the lime kiln tail gas, and the discharge port of the first pressure swing adsorption unit is communicated with the feed port of the carbon dioxide storage unit;

[0033] a steel slag reaction part, which comprises a gas pipeline, a gas collection hood, and a reaction unit, the reaction unit is provided with a first feed port and a second feed port, the top of the reaction unit is provided with the gas collection hood, the bottom of the gas collection hood abuts against the top of the reaction unit, the gas collection hood is communicated with the top of the reaction unit, the top of the gas collection hood is communicated with one end of the gas pipeline, and the first feed port of the reaction unit is communicated with the discharge port of the carbon dioxide storage unit;

[0034] a side blowing part, which comprises a side blowing gas storage unit and a side blowing pipeline, the discharge port of the side blowing gas storage unit is communicated with the feed port of the side blowing pipeline, and the discharge port of the side blowing pipeline is communicated with the second feed port of the reaction unit;

[0035] a gas treatment part, which comprises a heat exchange unit, a dust removal unit, and a second pressure swing adsorption unit, the other end of the gas pipeline is communicated with the heat exchange unit, the discharge port of the heat exchange unit is communicated with the feed port of the dust removal unit, the discharge port of the dust removal unit is communicated with the feed port of the second pressure swing adsorption unit, and the discharge port of the second pressure swing adsorption unit is communicated with the second feed port of the carbon dioxide storage unit;

[0036] The control unit includes a gas temperature sensor group, an oxygen content sensor, a first control valve, and a controller. The oxygen content sensor is located inside the top of the gas collection hood. The first control valve is located at the connection between the gas collection hood and the gas pipeline. The gas temperature sensor group is located inside the gas collection hood. The controller is connected to the gas temperature sensor group, the oxygen content sensor, the first control valve, the side-blowing pipeline, the side-blowing gas storage unit, the carbon dioxide storage unit, and the first pressure swing adsorption unit via electrical signals.

[0037] Optionally, the gas temperature sensor group includes a first gas temperature sensor and a second gas temperature sensor, which are disposed opposite to each other on the inner wall of the gas collection hood, and are disposed at the end of the oxygen content sensor away from the first control valve.

[0038] Optionally, the second pressure swing adsorption unit is provided with a first outlet and a second outlet, and the first outlet of the second pressure swing adsorption unit is connected to the second inlet of the carbon dioxide storage unit;

[0039] The system also includes:

[0040] The carbon monoxide collection section is connected to the second outlet of the second pressure swing adsorption unit.

[0041] Optionally, the reaction unit includes a reaction vessel and a running trolley. The running trolley is located at the bottom of the reaction vessel. A first feed inlet of the reaction unit is provided at the junction of the running trolley and the side of the reaction vessel. A second feed inlet of the reaction unit is provided on the bottom surface of the reaction vessel.

[0042] The technical solutions provided in this application have the following advantages compared with the prior art:

[0043] This application provides a method for carbon neutralization in lime kiln tail gas. CO2 gas obtained through pressure swing adsorption (PSA) of the lime kiln tail gas is introduced into liquid steel slag. This allows the CO2 gas to react with Fe-containing substances such as FeO, Fe, and Fe3O4 in the steel slag, ensuring complete conversion of the CO2 gas and FeO, Fe, and Fe3O4 in the molten steel to form iron oxides. Ultimately, Fe2O3, CO gas, and residual CO2 gas are obtained. The residual CO2 gas is returned to the blowing stage to achieve carbon recycling. The generated CO gas is then collected and utilized, thus completing the recovery and utilization of CO2 gas from the lime kiln tail gas, achieving carbon neutralization, and fully utilizing the CO2 in the lime kiln tail gas. Attached Figure Description

[0044] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings required to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the field, other drawings can also be obtained based on these drawings without any creative effort.

[0046] Figure 1 The flowchart provided for the embodiments of the present application;

[0047] Figure 2 The detailed flowchart provided for the embodiments of the present application;

[0048] Figure 3 The continuation of Figure 2 ;

[0049] Figure 4 The structure diagram of the system provided for the embodiments of the present application;

[0050] Figure 5 The detailed structure diagram of the system provided for the embodiments of the present application;

[0051] Figure 6 The schematic diagram of the steel slag reaction part provided for the embodiments of the present application;

[0052] Figure 7 The schematic diagram of the reaction tank body provided for the embodiments of the present application;

[0053] Figure 8 The experimental device schematic diagram for detecting CO2 gas provided for the embodiments of the present application;

[0054] Among them, 1-lime kiln tail gas collection part, 11-lime kiln collection unit, 12-first pressure swing adsorption unit, 13-carbon dioxide storage unit, 2-steel slag reaction part, 21-gas pipeline, 22-gas collection cover, 23-reaction unit, 231-reaction tank, 232-operation trolley, 3-side blowing part, 31-gas storage unit, 32-side blowing pipeline, 4-gas treatment part, 41-heat exchange unit, 42-dust removal unit, 43-second pressure swing adsorption unit, 5-control part, 51-gas temperature sensor group, 511-first gas temperature sensor, 512-second gas temperature sensor, 52-oxygen content sensor, 53-first control valve, 54-controller, 6-carbon monoxide collection part. DETAILED DESCRIPTION

[0055] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0056] The creative thinking of the present application is that CO2 gas is introduced into steel slag, and when the temperature of the liquid steel slag is above 700 DEG C, the following reactions 1-3 will occur:

[0057] 3FeO + CO2 = Fe3O4 + CO reaction 1

[0058] 3Fe + CO2 = Fe3O4 + CO reaction 2

[0059] 2Fe3O4 + CO2 = 3Fe2O3 + CO reaction 3

[0060] Among them, reaction 1 is the main reaction, and a large amount of CO is generated;

[0061] When the liquid steel slag is below 700 DEG C (not including 700 DEG C), the following reaction 4 will occur:

[0062] CaO + CO2 = CaCO3 reaction 4

[0063] Therefore, through the above different reaction stages, CO2 gas can be introduced to obtain different products, and the effective recovery of the heat of the liquid steel slag can be ensured.

[0064] In an embodiment of the present application, as shown in Figure 1 A method for carbon neutralization in lime kiln tail gas is provided, and the method comprises the following steps:

[0065] S1. Liquid steel slag after converter and lime kiln tail gas are obtained respectively;

[0066] S2. Pressure swing adsorption is performed on the lime kiln tail gas to obtain first CO2 gas;

[0067] S3. The first CO2 gas is introduced into the first treated steel slag to perform redox reaction, and then second heat exchange and post-treatment are performed to obtain second CO2 gas and CO gas respectively;

[0068] S4. The second CO2 gas is returned to the blowing for utilization to realize carbon cycle;

[0069] S5. The CO gas is collected and stored to realize carbon neutralization.

[0070] In some optional embodiments, the blowing includes blowing in a side blowing manner.

[0071] In the embodiments of the present application, by controlling the blowing manner, the side blowing manner is used, which not only has a faster gas diffusion speed than the side blowing, but also can prevent the condensation of the steel slag on the inner wall of the container, so as to better complete the reaction of the CO2 gas and the steel slag, and further realize carbon neutralization.

[0072] In some optional embodiments, as shown in Figure 2 and Figure 3 After the liquid steel slag and the lime kiln tail gas after the converter are obtained respectively, the method further includes:

[0073] S6. The liquid steel slag is side blown with nitrogen, first heat exchanged and dedusted, and then gas is collected to obtain a discharge tail gas and a first treated steel slag respectively;

[0074] S7. According to the oxygen content of the discharge tail gas, it is determined whether to blow in carbon dioxide.

[0075] If yes, the lime kiln tail gas is pressure swing adsorbed to obtain a first CO2 gas.

[0076] In the embodiments of the present application, the liquid steel slag is first side blown with nitrogen, and then the side blowing gas is first heat exchanged and dedusted, because CO gas is generated in the reaction process of the CO2 gas and the steel slag, so the oxygen element in the steel slag needs to be removed by using inert gas, so as to avoid the reaction of the CO gas and the O2 gas to produce explosion.

[0077] In some optional embodiments, according to the oxygen content of the discharge tail gas, it is determined whether to blow in carbon dioxide, specifically including:

[0078] S71. The oxygen content in the discharge tail gas and the standard oxygen content in the discharge tail gas are obtained respectively;

[0079] S72. According to the size of the oxygen content and the standard oxygen content, it is determined whether to blow in carbon dioxide.

[0080] If the oxygen content < the standard oxygen content, the lime kiln tail gas is pressure swing adsorbed to obtain a first CO2 gas.

[0081] If the oxygen content ≥ the standard oxygen content, the side blowing is continued, wherein the standard oxygen content ≤ 0.5%.

[0082] In the embodiments of the present application, by controlling the oxygen content in the discharge tail gas, the reaction of the CO gas and the O2 gas to produce explosion is avoided, and the safety of the overall system is ensured.

[0083] In some optional embodiments, the first CO2 gas is introduced into the first treated steel slag for redox reaction, followed by second heat exchange and post-treatment, to obtain a second treated steel slag;

[0084] S31. According to the temperature of the second treated steel slag, it is determined whether the second CO2 gas is subjected to carbon sequestration treatment;

[0085] If yes, the second CO2 gas is introduced into the second treated steel slag, followed by third heat exchange and gas collection, to obtain a collection gas and a third treated steel slag, respectively;

[0086] S32. According to the temperature of the collection gas, it is determined whether the aeration needs to be stopped;

[0087] If yes, the third treated steel slag is poured out to obtain a steel slag with excellent performance.

[0088] In some optional embodiments, the determination of whether the second separated CO2 gas is subjected to carbon sequestration treatment according to the temperature of the second treated steel slag specifically comprises:

[0089] S311. The actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag are obtained;

[0090] S312. According to the actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag, it is determined whether the second CO2 gas needs to be subjected to carbon sequestration treatment;

[0091] If the actual temperature of the second treated steel slag is less than the standard temperature of the second treated steel slag, the second CO2 gas is introduced into the second treated steel slag, followed by gas collection, to obtain a collection gas and a third treated steel slag, respectively;

[0092] If the actual temperature of the second treated steel slag is greater than or equal to the standard temperature of the second treated steel slag, the second CO2 gas is returned to the CO2 aeration, wherein the standard temperature of the second treated steel slag is 700-800°C.

[0093] In the embodiments, the temperature of the second CO2 gas is determined, the heat of the steel slag carried out by the second CO2 gas is used to determine the temperature of the steel slag, so that the turning point of the steel slag under the condition of 700-800°C can be distinguished, and it is determined whether the second CO2 gas continues to treat the liquid steel slag or is subjected to carbon sequestration treatment, so that the temperature turning point can be accurately distinguished, the CO2 gas in the lime kiln tail gas can be fully absorbed and utilized, and the utilization rate of the lime kiln tail gas is improved.

[0094] In some optional embodiments, the judging whether the aeration needs to be stopped according to the temperature of the collection gas specifically comprises:

[0095] S321. obtaining the actual temperature of the collection gas and the standard temperature of the collection gas;

[0096] S322. judging whether the aeration needs to be stopped according to the magnitude of the actual temperature of the collection gas and the standard temperature of the collection gas;

[0097] If the actual temperature of the collection gas is less than the standard temperature of the collection gas, the aeration is stopped, the third treated steel slag is poured out, and the steel slag with excellent performance is obtained.

[0098] If the actual temperature of the collection gas is greater than or equal to the standard temperature of the collection gas, the aeration needs to be continued.

[0099] In the embodiments of the present application, the temperature of the collection gas is judged, and the heat of the steel slag carried out by the collection gas is indirectly judged, so as to ensure that the residual heat in the steel slag is sufficient for subsequent operations, and then the heat of the steel slag is accurately recovered and utilized.

[0100] In some optional embodiments, the standard temperature is less than or equal to 200°C.

[0101] In the embodiments of the present application, the positive effect of the standard temperature being less than or equal to 200°C is that under the temperature condition, the residual heat in the steel slag can support the subsequent operations, so as to ensure the heat recovery of the steel slag.

[0102] In one embodiment of the present application, as shown in Figure 4 a system for carbon neutralization in lime kiln tail gas is provided, the system is adapted to the method of the first aspect, and the system comprises:

[0103] a lime kiln tail gas collection part 1, the lime kiln tail gas collection part 1 comprises a lime kiln collection unit 11, a first pressure swing adsorption unit 12 and a carbon dioxide storage unit 13, the carbon dioxide storage unit 13 is provided with a first feed inlet and a second feed inlet, the discharge port of the lime kiln collection unit is connected to the feed port of the first pressure swing adsorption unit 12, so as to realize the separation of CO2 in the lime kiln tail gas, and the discharge port of the first pressure swing adsorption unit 12 is communicated with the feed port of the carbon dioxide storage unit 13;

[0104] a steel slag reaction part 2, as Figure 6The steel slag reaction part 2 includes a gas pipeline 21, a gas collection cover 22, and a reaction unit 23 provided with a first feeding port and a second feeding port. The top of the reaction unit 23 is provided with the gas collection cover 22, the bottom of the gas collection cover 22 abuts against the top of the reaction unit 23, the gas collection cover 22 communicates with the top of the reaction unit 23, the top of the gas collection cover 22 communicates with one end of the gas pipeline 21, and the first feeding port of the reaction unit 23 communicates with the discharge port of the carbon dioxide storage unit 13.

[0105] The side blowing part 3 includes a side blowing gas storage unit 31 and a side blowing pipeline 32. The discharge port of the side blowing gas storage unit 31 communicates with the feeding port of the side blowing pipeline 32, and the discharge port of the side blowing pipeline 32 communicates with the second feeding port of the reaction unit 23.

[0106] The gas treatment part 4 includes a heat exchange unit 41, a dust removal unit 42, and a second pressure swing adsorption unit 43. The other end of the gas pipeline 21 communicates with the heat exchange unit 41, the discharge port of the heat exchange unit 41 communicates with the feeding port of the dust removal unit 42, the discharge port of the dust removal unit 42 communicates with the feeding port of the second pressure swing adsorption unit 43, and the discharge port of the second pressure swing adsorption unit 43 communicates with the second feeding port of the carbon dioxide storage unit 13.

[0107] The control part 5 includes a gas temperature sensor group 51, an oxygen content sensor 52, a first control valve 53, and a controller 54. The oxygen content sensor 52 is arranged inside the top of the gas collection cover 22, the first control valve 53 is arranged at the connection between the gas collection cover 22 and the gas pipeline 21, the gas temperature sensor group 51 is arranged in the gas collection cover 22, and the controller 54 communicates with the gas temperature sensor group 51, the oxygen content sensor 52, the first control valve 53, the side blowing pipeline 32, the side blowing gas storage unit 31, the carbon dioxide storage unit 13, and the first pressure swing adsorption unit 12 through electrical signals, respectively.

[0108] In the embodiment of the present application, by adopting the lime kiln tail gas collecting part 1 comprising the lime kiln collecting unit 11, the first pressure swing adsorption unit 12 and the carbon dioxide storage unit 13, the steel slag reaction part 2 comprising the gas pipeline 21, the gas collecting cover 22 and the reaction unit 23, the side blowing part 3 comprising the side blowing gas storage unit 31 and the side blowing pipeline 32, the gas treatment part 4 comprising the heat exchange unit 41, the dust removal unit 42 and the second pressure swing adsorption unit 43, and the control part 5 comprising the gas temperature sensor group 51, the oxygen content sensor 52, the first control valve 53 and the controller 54, the oxygen content in the gas after side blowing is controlled by the gas temperature sensor group 51 and the oxygen content sensor 52 in the control part 5 respectively, the safety of the device is ensured, the temperature of the second separated CO2 gas and the temperature of the collected gas are judged by the gas temperature sensor group 51, so that the sufficient recovery of the heat in the liquid steel slag can be ensured, and the controller 54 can also ensure that the reaction of the CO2 gas in the lime kiln tail gas into the liquid steel slag is switched after the side blowing is completed, so that the switching in different stages is effectively realized, and the utilization rate of the CO2 gas in the lime kiln tail gas to the heat energy of the liquid steel slag is improved.

[0109] In some optional embodiments, as shown in Figure 5 The gas temperature sensor group 51 comprises a first gas temperature sensor 511 and a second gas temperature sensor 512, the first gas temperature sensor 511 and the second gas temperature sensor 512 are oppositely arranged on the inner wall of the gas collecting cover 22, and the first gas temperature sensor 511 and the second gas temperature sensor 512 are arranged at the end of the oxygen content sensor 52 away from the first control valve 53.

[0110] In the present application, by adopting the gas temperature sensor group comprising the first gas temperature sensor 511 and the second gas temperature sensor 512, the temperature in different stages can be effectively ensured, for example, the first gas temperature sensor 511 measures the second separated CO2 gas, so that whether the temperature of the liquid steel slag is 700℃ or not can be determined, and the accurate conversion of the processing mode of the CO2 gas to the liquid steel slag is ensured, and the second gas temperature sensor 512 measures the temperature of the collected gas, so that the end time of the CO2 gas to the liquid steel slag can be accurately judged, and the effective utilization of the heat of the liquid steel slag is ensured to the maximum extent.

[0111] In some optional embodiments, the second pressure swing adsorption unit 43 is provided with a first discharge port and a second discharge port, and the first discharge port of the second pressure swing adsorption unit 43 is communicated with the second feed port of the carbon dioxide storage unit 13.

[0112] The system further comprises:

[0113] A carbon monoxide collection part 6, a second discharge port of the second pressure swing adsorption unit 43 is communicated with the carbon monoxide collection part 6.

[0114] In the embodiment, the second discharge port of the second pressure swing adsorption unit 43 is communicated with the carbon monoxide collection part 6, so that the carbon monoxide in the mixed gas can be separated, and the mixed gas can be effectively utilized.

[0115] In some optional embodiments, as shown in Figure 7 The reaction unit 23 includes a reaction tank 231 and a running trolley 232, the running trolley 232 is arranged at the bottom end of the reaction tank 231, the first discharge port of the reaction unit 23 is arranged at the joint of the side surface of the running trolley 232 and the reaction tank 231, and the second discharge port of the reaction unit 23 is arranged on the bottom surface of the reaction tank 231.

[0116] In the embodiment, the reaction tank 231 is additionally designed, so that the material can be smoothly transferred before and after the reaction in the reaction tank 231.

[0117] Example 1

[0118] As shown in Figure 2 and Figure 3 A method for carbon neutralization in lime kiln tail gas, comprising:

[0119] S1. obtaining liquid steel slag after converter and lime kiln tail gas respectively;

[0120] S2. performing pressure swing adsorption on the lime kiln tail gas to obtain first CO2 gas;

[0121] S3. introducing the first CO2 gas into the first treated steel slag to perform redox reaction, then performing second heat exchange and post-treatment, to obtain second CO2 gas, CO gas and second treated steel slag respectively;

[0122] S311. obtaining the actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag;

[0123] S312. judging whether the second CO2 gas needs to be treated for carbon sequestration according to the actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag;

[0124] If the actual temperature of the second treated steel slag < the standard temperature of the second treated steel slag, the second CO2 gas is introduced into the second treated steel slag, and then gas collection is performed, to obtain collected gas and third treated steel slag respectively;

[0125] If the actual temperature of the second treated steel slag is greater than or equal to the standard temperature of the second treated steel slag, the second CO2 gas is returned to the injection of carbon dioxide;

[0126] S321. Obtain the actual temperature of the collected gas and the standard temperature of the collected gas;

[0127] S322. Determine whether ventilation needs to be stopped according to the magnitude of the actual temperature of the collected gas and the standard temperature of the collected gas;

[0128] If the actual temperature of the collected gas is less than the standard temperature of the collected gas, ventilation is stopped, the third treated steel slag is discharged, and the steel slag with excellent performance is obtained;

[0129] If the actual temperature of the collected gas is greater than or equal to the standard temperature of the collected gas, ventilation needs to be continued;

[0130] S4. The second CO2 gas returned to the injection is utilized to realize carbon cycle;

[0131] S5. The CO gas is collected and stored to realize carbon neutralization;

[0132] S6. The liquid steel slag is side blown, subjected to first heat exchange and dust removal, and then subjected to gas collection, to obtain exhaust gas and first treated steel slag, respectively;

[0133] S71. Obtain the oxygen content in the exhaust gas and the standard oxygen content in the exhaust gas, respectively;

[0134] S72. Determine whether carbon dioxide injection is performed according to the magnitude of the oxygen content and the standard oxygen content;

[0135] If the oxygen content is less than the standard oxygen content, the lime kiln exhaust gas is subjected to pressure swing adsorption to obtain first CO2 gas;

[0136] If the oxygen content is greater than or equal to the standard oxygen content, side blowing is continued.

[0137] Example 2

[0138] Example 2 and Example 1 are compared, and the difference between Example 2 and Example 1 is that:

[0139] As shown in Figure 5 A system for carbon neutralization in a lime kiln exhaust gas, the system is adapted to the method of the first aspect, and the system comprises:

[0140] The lime kiln tail gas collecting part 1 comprises a lime kiln collecting unit 11, a first pressure swing adsorption unit 12 and a carbon dioxide storage unit 13, the carbon dioxide storage unit 13 is provided with a first feed inlet and a second feed inlet, the discharge outlet of the lime kiln collecting unit is connected to the feed inlet of the first pressure swing adsorption unit 12, so as to separate CO2 in the lime kiln tail gas, and the discharge outlet of the first pressure swing adsorption unit 12 is communicated with the feed inlet of the carbon dioxide storage unit 13;

[0141] The steel slag reaction part 2 comprises a gas pipeline 21, a gas collecting cover 22 and a reaction unit 23, the reaction unit 23 is provided with a first feed inlet and a second feed inlet, the top of the reaction unit 23 is provided with the gas collecting cover 22, the bottom of the gas collecting cover 22 abuts against the top of the reaction unit 23, the gas collecting cover 22 is communicated with the top of the reaction unit 23, the top of the gas collecting cover 22 is communicated with one end of the gas pipeline 21, and the first feed inlet of the reaction unit 23 is communicated with the discharge outlet of the carbon dioxide storage unit 13;

[0142] The side blowing part 3 comprises a side blowing gas storage unit 31 and a side blowing pipeline 32, the discharge outlet of the side blowing gas storage unit 31 is communicated with the feed inlet of the side blowing pipeline 32, and the discharge outlet of the side blowing pipeline 32 is communicated with the second feed inlet of the reaction unit 23;

[0143] The gas treatment part 4 comprises a heat exchange unit 41, a dust removal unit 42 and a second pressure swing adsorption unit 43, the other end of the gas pipeline 21 is communicated with the heat exchange unit 41, the discharge outlet of the heat exchange unit 41 is communicated with the feed inlet of the dust removal unit 42, the discharge outlet of the dust removal unit 42 is communicated with the feed inlet of the second pressure swing adsorption unit 43, and the discharge outlet of the second pressure swing adsorption unit 43 is communicated with the second feed inlet of the carbon dioxide storage unit 13;

[0144] The control part 5 comprises a gas temperature sensor group 51, an oxygen content sensor 52, a first control valve 53 and a controller 54, the oxygen content sensor 52 is arranged inside the top of the gas collecting cover 22, the first control valve 53 is arranged at the connection between the gas collecting cover 22 and the gas pipeline 21, the gas temperature sensor group 51 is arranged in the gas collecting cover 22, and the controller 54 is communicated with the gas temperature sensor group 51, the oxygen content sensor 52, the first control valve 53, the side blowing pipeline 32, the side blowing gas storage unit 31, the lime kiln collecting unit 11 and the first pressure swing adsorption unit 12 through electric signals respectively.

[0145] The gas temperature sensor group 51 comprises a first gas temperature sensor 511 and a second gas temperature sensor 512, which are oppositely arranged on the inner wall of the gas collecting cover 22, and are arranged at the end of the oxygen content sensor 52 away from the first control valve 53.

[0146] The second pressure swing adsorption unit 43 is provided with a first discharge port and a second discharge port, and the first discharge port of the second pressure swing adsorption unit 43 is communicated with the second feed port of the carbon dioxide storage unit 13.

[0147] The system further comprises:

[0148] The carbon monoxide collecting part 6 is communicated with the second discharge port of the second pressure swing adsorption unit 43.

[0149] The reaction unit 23 comprises a reaction tank 231 and a running trolley 232, the running trolley 232 is arranged at the bottom end of the reaction tank 231, the first feed port of the reaction unit 23 is arranged at the joint of the side surface of the running trolley 232 and the reaction tank 231, and the second feed port of the reaction unit 23 is arranged on the bottom surface of the reaction tank 231.

[0150] Example 3

[0151] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is that:

[0152] The system of the present application is simplified into an experimental device as shown in Figure 8 The specific process includes:

[0153] 1. Weigh 100.0g of steel slag into a crucible, weigh the crucible 458.9g, and put the crucible into a muffle furnace and heat to 1400℃;

[0154] 2. Take the crucible out of the muffle furnace and put it into the test device and introduce nitrogen;

[0155] 3. When gas comes out of the gas collecting pipe, switch to CO2 and start the drainage gas collection method;

[0156] 4. The gas collection is divided into early and late stages with 700℃ as the node.

[0157] 5. When the temperature of the crucible is lower than 200℃, stop collecting gas;

[0158] 6. Cool the crucible to room temperature and weigh 460.5g;

[0159] 7. Analyze the composition of the collected gas.

[0160] Related experiments:

[0161] The small-scale experiment is carried out according to the simplified device of embodiment 3, and the results are as follows:

[0162] 1. The test crucible is increased by 460.5-458.9=1.6g,

[0163] 2. The early collected gas is mainly composed of carbon monoxide through qualitative analysis.

[0164] 3. The later collected gas is mainly composed of carbon dioxide through qualitative analysis.

[0165] One or more technical solutions in the embodiments of the application have at least the following technical effects or advantages:

[0166] (1) The method provided by the embodiments of the application first exchanges and dedusts the side-blown gas, and then analyzes it to ensure that the oxygen content in the side-blown gas is at a minimum, and then the CO2 gas obtained by pressure swing adsorption of the lime kiln tail gas is introduced into the liquid steel slag, to ensure that the CO2 gas and FeO, Fe and Fe3O4 in the steel liquid are fully converted, and then the second separated CO2 gas is continuously subjected to carbon sequestration treatment to obtain CaCO3, thereby realizing the collection of CO2 in the lime kiln tail gas and achieving the goal of carbon neutrality. In all processes, the heat carried out by the side-blown gas, the heat in the gas generated by the reaction of the CO2 gas and the steel liquid, and the gas heat in the carbon sequestration treatment process are collected respectively, thereby improving the heat energy utilization rate of the steel slag.

[0167] (2) The method provided by the embodiments of the application effectively controls the temperature at the reaction endpoint and controls the temperature of the second treated steel slag, thereby accurately ensuring that the heat carried out by the gas from the liquid steel slag is fully recovered, and realizing the use of CO2 in the lime kiln tail gas to improve the heat energy utilization rate of the steel slag.

[0168] (3) The method provided by the embodiments of the application uses the lime kiln tail gas to purify CO2 and blow it into the liquid steel slag to produce carbon monoxide gas and exchange heat energy. When the steel slag temperature drops below 700℃, continue to introduce CO2 gas into the active CaO in the steel slag to generate CaCO3, thereby effectively carbonizing the steel slag and optimizing the performance of the steel slag, which is easy to crush and recycle metal materials.

[0169] (4) The system provided by the embodiment of the present application, by adopting the lime kiln tail gas collecting unit 1 comprising a lime kiln collecting unit 11, a first pressure swing adsorption unit 12 and a carbon dioxide storage unit 13, the steel slag reaction unit 2 comprising a gas pipeline 21, a gas collecting hood 22 and a reaction unit 23, the side blowing unit 3 comprising a side blowing gas storage unit 31 and a side blowing pipeline 32, the gas treatment unit 4 comprising a heat exchange unit 41, a dust removal unit 42 and a second pressure swing adsorption unit 43, and the control unit 5 comprising a gas temperature sensor group 51, an oxygen content sensor 52, a first control valve 53 and a controller 54, the oxygen content in the gas after side blowing is controlled by the gas temperature sensor group 51 and the oxygen content sensor 52 in the control unit 5 respectively, the safety of the device is ensured, the temperature of the second separated CO2 gas and the temperature of the collected gas are judged by the gas temperature sensor group 51, so that the sufficient recovery of the heat in the liquid steel slag can be ensured, and the controller 54 can also ensure that, after the side blowing is completed, the reaction of the CO2 gas in the lime kiln tail gas into the liquid steel slag is switched, so that the switching in different stages is effectively realized, the sufficient reaction of the CO2 gas in the lime kiln tail gas and the liquid steel slag is ensured, the collection of the reaction tail gas is realized, and the heat energy utilization rate of the liquid steel slag is improved by using multiple heat exchange devices.

[0170] (5) The system provided by the embodiment of the present application can effectively simplify the overall method, and the overall device is simple to operate.

[0171] It should be noted that, in the present text, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0172] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges and values should be construed to be approximations that allow for significant variation. Various ranges of values that resolve from the disclosure herein are considered to be within the scope of the disclosure, as construing each range between the endpoints, each range between an endpoint and a single point value, and each single point value between ranges as new ranges.

[0173] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and it is intended to embrace all such modifications and changes that fall within the scope of the application. Accordingly, the application is not to be restricted in scope to the specific embodiments disclosed herein but is to be accorded the full scope that the principles and novel features request appropriately granted.

Claims

1. A method for carbon neutralization in lime kiln off-gas, characterized by, The method comprises: respectively obtaining liquid steel slag after the converter and lime kiln tail gas; after respectively obtaining the liquid steel slag after the converter and the lime kiln tail gas, it further comprises: side blowing, first heat exchange and dust removal are carried out on the liquid steel slag, then gas collection is carried out, respectively obtaining the exhaust gas and the first treated steel slag; determining whether to carry out carbon dioxide blowing according to the oxygen content of the exhaust gas; the determination whether to carry out carbon dioxide blowing according to the oxygen content of the exhaust gas specifically comprises: respectively obtaining the oxygen content in the exhaust gas and the standard oxygen content in the exhaust gas; according to the size of the oxygen content and the standard oxygen content, it is judged whether to carry out carbon dioxide blowing; if the oxygen content < the standard oxygen content, the lime kiln tail gas is carried out pressure swing adsorption to obtain the first CO2 gas; if the oxygen content ≥ the standard oxygen content, the side blowing is continued; if yes, the lime kiln tail gas is carried out pressure swing adsorption to obtain the first CO2 gas; the first CO2 gas is introduced into the first treated steel slag to carry out redox reaction, then second heat exchange and post-treatment are carried out, respectively obtaining the second CO2 gas and CO gas; the second CO2 gas is returned to the blowing for use to realize carbon cycle; the CO gas is collected and stored to realize carbon neutralization; the blowing comprises blowing in the form of side blowing; the first CO2 gas is introduced into the first treated steel slag to carry out redox reaction, then second heat exchange and post-treatment are carried out, and the second treated steel slag is also obtained; according to the temperature of the second treated steel slag, it is judged whether the second CO2 gas needs to be treated for carbon sequestration; if yes, the second CO2 gas is introduced into the second treated steel slag, then third heat exchange and gas collection are carried out, respectively obtaining the collection gas and the third treated steel slag; according to the temperature of the collection gas, it is judged whether the aeration needs to be stopped; if yes, the third treated steel slag is poured out to obtain steel slag with excellent performance; the judgment whether the second separated CO2 gas needs to be treated for carbon sequestration according to the temperature of the second treated steel slag specifically comprises: the actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag are obtained; according to the size of the actual temperature of the second treated steel slag and the standard temperature of the second treated steel slag, it is judged whether the second CO2 gas needs to be treated for carbon sequestration; if the actual temperature of the second treated steel slag < the standard temperature of the second treated steel slag, the second CO2 gas is introduced into the second treated steel slag, then gas collection is carried out, respectively obtaining the collection gas and the third treated steel slag; if the actual temperature of the second treated steel slag ≥ the standard temperature of the second treated steel slag, the second CO2 gas is returned to the carbon dioxide blowing.

2. A system for carbon neutralization in lime kiln off-gas, characterized by, The system is adapted to the method of claim 1, and the system comprises: The lime kiln tail gas collecting part (1) comprises a lime kiln collecting unit (11), a first pressure swing adsorption unit (12) and a carbon dioxide storage unit (13), the carbon dioxide storage unit (13) is provided with a first feed port and a second feed port, the discharge port of the lime kiln tail gas collecting unit is connected with the feed port of the first pressure swing adsorption unit (12), so as to realize the separation of CO2 in the lime kiln tail gas, and the discharge port of the first pressure swing adsorption unit (12) is communicated with the feed port of the carbon dioxide storage unit (13); The steel slag reaction part (2) comprises a gas pipeline (21), a gas collecting cover (22) and a reaction unit (23), the reaction unit (23) is provided with a first feed port and a second feed port, the top of the reaction unit (23) is provided with the gas collecting cover (22), the bottom of the gas collecting cover (22) abuts against the top of the reaction unit (23), the gas collecting cover (22) is communicated with the top of the reaction unit (23), the top of the gas collecting cover (22) is communicated with one end of the gas pipeline (21), and the first feed port of the reaction unit (23) is communicated with the discharge port of the carbon dioxide storage unit (13); The side blowing part (3) comprises a side blowing gas storage unit (31) and a side blowing pipeline (32), the discharge port of the side blowing gas storage unit (31) is communicated with the feed port of the side blowing pipeline (32), and the discharge port of the side blowing pipeline (32) is communicated with the second feed port of the reaction unit (23); The gas treatment part (4) comprises a heat exchange unit (41), a dust removal unit (42) and a second pressure swing adsorption unit (43), the other end of the gas pipeline (21) is communicated with the heat exchange unit (41), the discharge port of the heat exchange unit (41) is communicated with the feed port of the dust removal unit (42), the discharge port of the dust removal unit (42) is communicated with the feed port of the second pressure swing adsorption unit (43), and the discharge port of the second pressure swing adsorption unit (43) is communicated with the second feed port of the carbon dioxide storage unit (13); The control part (5) comprises a gas temperature sensor group (51), an oxygen content sensor (52), a first control valve (53) and a controller (54), the oxygen content sensor (52) is arranged in the top of the gas collecting cover (22), the first control valve (53) is arranged at the connection between the gas collecting cover (22) and the gas pipeline (21), the gas temperature sensor group (51) is arranged in the gas collecting cover (22), and the controller (54) is communicated with the gas temperature sensor group (51), the oxygen content sensor (52), the first control valve (53), the side blowing pipeline (32), the side blowing gas storage unit (31), the carbon dioxide storage unit (13) and the first pressure swing adsorption unit (12) through electric signals respectively.

3. The system of claim 2, wherein, The gas temperature sensor group (51) comprises a first gas temperature sensor (511) and a second gas temperature sensor (512), the first gas temperature sensor (511) and the second gas temperature sensor (512) are oppositely arranged on the inner wall of the gas collecting cover (22), and the first gas temperature sensor (511) and the second gas temperature sensor (512) are arranged at one end of the oxygen content sensor (52) away from the first control valve (53).

4. The system of claim 2, wherein, The second pressure swing adsorption unit (43) is provided with a first discharge port and a second discharge port, and the first discharge port of the second pressure swing adsorption unit (43) communicates with the second feed port of the carbon dioxide storage unit (13). The system further comprises: A carbon monoxide collecting part (6), and the second discharge port of the second pressure swing adsorption unit (43) communicates with the carbon monoxide collecting part (6).

5. The system of claim 2, wherein, The reaction unit (23) comprises a reaction tank (231) and a running trolley (232), the running trolley (232) is arranged at the bottom end of the reaction tank (231), the side surface joint of the running trolley (232) and the reaction tank (231) is provided with a first feed port of the reaction unit (23), and the bottom surface of the reaction tank (231) is provided with a second feed port of the reaction unit (23).

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