Low-carbon sintering method, process and system

Abstract

The invention belongs to the technical field of low-carbon sintering, and discloses a low-carbon sintering method aiming at the problem of large sintering carbon emission caused by large fossil energy consumption in an existing sintering process. According to the characteristics of the sintering process, the biomass is purposefully crushed, screened and graded to form biomass particles with different size fractions, and then the biomass particles can fully participate in the sintering process, so that the utilization efficiency of the biomass can be remarkably improved while the sintering quality is ensured, and the consumption of fossil energy is greatly reduced. The method specifically comprises the steps that combustible gas and gasified slag are obtained after medium-particle biomass is gasified, the gasified slag can serve as a sintering raw material to participate in batching, and the combustible gas is blown to the material surface of a sintering mixture to participate in roasting; the large-particle biomass is arranged on the material surface of the sintered material and used for assisting ignition and roasting of the sintered material; and the small-particle biomass is used as ignition fuel. According to the method, the biomass can be fully used in the sintering process after being subjected to special pretreatment, so that the utilization rate of the biomass is effectively increased, the consumption of fossil energy in the sintering process is remarkably reduced, and low-carbon sintering is realized.

Description

Technical Field

[0001] The present invention relates to a sintering method, process and system, and in particular to a low-carbon sintering method, process and system based on biomass fractionation treatment, belonging to the technical field of sintering. Background Art

[0002] The general sintering process is one of the main methods of iron ore agglomeration in the steel process. At present, the annual output of sintered ore in China exceeds 1 billion tons. The fuel used for sintering is mainly coke powder. According to the current energy consumption of 40 to 50 kgce per ton of sintered ore, the annual CO emissions of the sintering industry are 2 More than 100 million tons, accounting for the largest share of CO in the steel industry and even in the country 2 Carbon emission reduction in the sintering process is particularly important in the context of the country's implementation of the dual carbon strategic goals. The current mainstream sintering process is exhaust sintering, and the main equipment includes belt sintering machine, ignition and insulation furnace, distributor, ring cooler, etc. Belt sintering machine has become the absolute mainstream of sintering production in the world due to its high single-machine output and high degree of mechanization and automation.

[0003] Domestic and foreign researchers have conducted many low-carbon research and attempts on the sintering process, such as biomass sintering and gas injection. Due to the inherent defects of biomass fuel, biomass sintering is currently only in laboratory research and cannot be promoted on a large scale in industry; gas injection is a method that has emerged in recent years to reduce the use of coke by injecting gas into the sintering material surface, but the gas used for injection is still mainly coke oven gas and natural gas, which is essentially derived from fossil energy and has little effect on reducing CO 2 The effect of emissions is still limited.

[0004] The existing sintering process production process is as follows Figure 5 As shown in the figure, the sintering raw materials are mainly composed of iron ore, flux and fuel. The sintering fuel is mainly fossil fuel coke powder, which accounts for about 3-5% of the sintering raw materials. After being fully mixed and granulated, the various components of the sintering raw materials are evenly spread on the sintering trolley by the distributor. The trolley moves at a constant speed from left to right. When the trolley moves into the ignition and insulation furnace, gas and air are introduced into the ignition and insulation furnace through the ignition burner for ignition. The coke powder on the surface of the sintering raw materials is ignited. Then, under the negative pressure of the exhaust under the trolley, the air above the trolley is continuously sucked into the material layer, and the combustion zone in the material layer is transmitted from top to bottom, completing the entire sintering process. The high-temperature flue gas is drawn into the large flue under the trolley by the main exhaust fan, and the temperature reaches above 900℃. It is discharged into the atmosphere after waste heat utilization and desulfurization and denitrification.

[0005] The fuel of the traditional sintering process is still mainly fossil fuels. Coke powder is added to the sintering raw materials. The coke oven gas and blast furnace gas used for sintering ignition are essentially derived from coal. The production of sintered ore requires the discharge of a large amount of CO 2 . At present, there are some low-carbon sintering methods on the market that use part of the biomass to replace fossil fuels for sintering. Generally, the biomass fuel is directly mixed with iron ore and then sintered. Under this process, due to the large difference in density between the biomass fuel and other sintering raw materials such as iron ore, the distribution of biomass in the sintering raw materials is prone to segregation when the raw materials are mixed, resulting in uneven heat distribution in the material layer. In addition, a large amount of volatile matter in the biomass is extracted by the large flue before it can be burned, resulting in insufficient heat in the material layer and excessive combustible gas in the flue gas. Directly mixing biomass into the raw materials has limited effect on carbon reduction during sintering and also affects the quality of the sintered ore. Summary of the invention

[0006] In view of the fact that in the prior art low-carbon sintering methods for biomass to replace fossil fuels, there is a problem that biomass is prone to segregation during the mixing process, which leads to uneven heat distribution in the sintering material layer, and a large amount of volatile matter in the biomass does not have time to burn, resulting in insufficient heat in the material layer. The present invention proposes a low-carbon sintering method, process and system, which crushes and screens the biomass and classifies it according to particle size, and then sends biomass fuel particles of different particle sizes to different sintering processes, so as to achieve full utilization of biomass and low-carbon sintering. According to the different basic characteristics of different biomass particle sizes, the inventor studies the characteristics of different biomass properties and the requirements of the sintering process, couples biomass of different properties with different sintering processes, improves the utilization efficiency of biomass in the sintering process, and thus achieves the purpose of reducing the use of fossil energy and reducing carbon emissions, and realizes low-carbon sintering.

[0007] According to a first embodiment of the present invention, a low-carbon sintering method is provided.

[0008] A low carbon sintering method, the method comprising the following steps:

[0009] 1) Biomass pretreatment: crushing and sieving the biomass to obtain large-particle biomass, medium-particle biomass, and small-particle biomass; gasifying the medium-particle biomass to obtain combustible gas and gasification slag;

[0010] 2) Sintering batching and distribution: After the sintering raw materials are batched, the sintering materials are first distributed on the sintering machine trolley, and then optionally dried or not, and finally large biomass particles are laid on the surface of the sintering materials to obtain the sintering materials containing biomass;

[0011] 3) Sintering treatment: The sintering material containing biomass moves forward with the sintering trolley and is sequentially ignited, roasted and cooled to obtain the sintered finished material; in the ignition process: small particles of biomass are sent to the ignition burner as ignition fuel for ignition; in the roasting process, combustible gas is sprayed onto the surface of the sintering mixture to participate in roasting.

[0012] Preferably, in step 1), the particle size of the large biomass particles is [a, b], the particle size of the medium biomass particles is [c, a), and the particle size of the small biomass particles is (0, c);

[0013] Among them, the value of a is 1 to 3 mm; the value of b is 4 to 8 mm, and the value of c is 0.3 to 0.7 mm;

[0014] Preferably, the oversized biomass particles with a particle size greater than b are returned to the crushing process for re-crushing.

[0015] Preferably, the gasified slag obtained in step 1) is used as one of the sintering raw materials to participate in the batching.

[0016] Preferably, in step 1), the gasification treatment is specifically: placing the medium-sized biomass particles in a mixed atmosphere containing water vapor and oxygen for thermal gasification to obtain combustible gas and gasified slag respectively; wherein the temperature of the thermal gasification treatment is not less than 700°C, preferably not less than 800°C.

[0017] Preferably, the gas-solid mass ratio of the total mass of the water vapor and oxygen to the biomass is 0.4-0.8:1, preferably 0.5-0.7:1.

[0018] Preferably, in the mixed atmosphere, the volume ratio of water vapor to oxygen is 1 to 2:1, preferably 1.2 to 1.5:1.

[0019] Preferably, the gasification process is carried out in a suspended bed reactor or a fixed bed reactor.

[0020] Preferably, the heat source in the gasification process is the high-temperature flue gas in the sintering flue. Preferably, the heat exchange between the high-temperature flue gas and the biomass is indirect heat exchange.

[0021] Preferably, the water vapor and oxygen in the gasification process are wholly or partially derived from the high-humidity hot air discharged from the drying section of the sintering process, and new water is used as a supplementary source of water vapor.

[0022] Preferably, the other sintering raw materials in step 2) are iron ore, quicklime, coke powder and optionally gasified slag.

[0023] Preferably, the drying treatment in step 2) is: introducing high-temperature hot air of not less than 300°C into the sintering trolley to contact the sintering material to achieve heat exchange drying; preferably, the high-temperature hot air of not less than 300°C is the hot air generated during the cooling process and / or the flue gas obtained during the gasification process.

[0024] Preferably, the method further comprises: 4) molding the gasified slag obtained in step 1) to obtain molded slag, and using the molded slag as one of the sintering raw materials to participate in the batching.

[0025] Preferably, the forming process is specifically: extruding, exhausting and crushing the obtained gasified slag.

[0026] Preferably, the extrusion pressure during the extrusion exhaust process is 15 to 30 MPa, preferably 20 to 28 MPa.

[0027] Preferably, the particle size of the molded slag obtained after the crushing is 2 to 7 mm, preferably 3 to 5 mm.

[0028] According to a second embodiment of the present invention, a biomass fractionation process for a low-carbon sintering method is provided.

[0029] A biomass fractionation process for a low-carbon sintering method, the biomass fractionation process comprising: a) controlling gasification reaction parameters according to the properties of the biomass so that the volatile content in the gasified slag is not higher than a set value, and preferably also making the carbon content in the gasified slag not lower than a set value.

[0030] Preferably, the volatile matter content in the gasified slag is not higher than the set value: the volatile matter content in the gasified slag is not higher than 8%, preferably not higher than 5%; the carbon content in the gasified slag is higher than the set value: the carbon content in the gasified slag is not lower than 20%, preferably not lower than 25%.

[0031] Preferably, the gasification process is carried out in a fixed bed reactor, and the control gasification reaction parameters are:

[0032] At a given gasification temperature, the theoretical gasification time required for the carbon content in the gasified slag to be equal to the set value is calculated as:

[0033]

[0034] In the formula, C 0 is the initial carbon content in the medium-grained biomass, %; C 1 is the set value of carbon content in gasification slag, %; L is the particle size of medium-sized biomass, mm; M is the moisture content in biomass, %; T 1 is the vaporization temperature, °C; t ′ 1It is the time required for the temperature to rise to the carbon reaction in the biomass; α and η are adjustment coefficients, where the value range of α is 0.20-0.30, and the value range of η is 0.10-0.20.

[0035] At the same gasification temperature, the theoretical gasification time required for the volatile matter content in the gasified slag to be equal to the set value is:

[0036]

[0037] Where V 0 is the initial volatile content in the medium-grained biomass, %; V 1 is the set value of the volatile matter content in the gasification slag, %; L is the particle size of the medium-sized biomass, mm; M is the moisture content in the biomass, %; T 1 is the vaporization temperature, °C; t ′ 2 It is the time required for the temperature to rise to the time required for the volatile matter in the biomass to react; γ and μ are adjustment coefficients, among which the value range of γ is 0.08-0.15; the value range of μ is 0.10-0.20.

[0038] Then the actual gasification time is controlled as:

[0039] When t 2 ≤t 1 When the temperature meets the gasification conditions, according to (Formula 1) and (Formula 2), the actual gasification time t at this temperature is controlled as follows: t 2 ≤t≤t 1 When t 2 >t 1 When the actual vaporization time t at this temperature is controlled to be: t≥t 2 .

[0040] Preferably, the process further comprises: b) detecting the volatile matter content and carbon content in the gasified slag, and returning the gasified slag with too high volatile matter content and carbon content to the gasification process of the medium-particle biomass for re-gasification.

[0041] Preferably, the process further comprises: c) during the biomass crushing and screening and grading process, controlling the mass distribution ratio of the obtained large-particle biomass, medium-particle biomass and small-particle biomass, thereby reducing carbon emissions while meeting the normal operation requirements of the sintering process; which specifically includes:

[0042] ci) To reduce carbon emissions while meeting the normal operation requirements of the sintering process, a dynamic mathematical model of the mass distribution ratio of large-particle biomass, medium-particle biomass and small-particle biomass is established:

[0043]

[0044] In (Formula 3), A is the proportion of the mass of small-particle biomass to the total mass of biomass, %; B is the proportion of the mass of medium-particle biomass to the total mass of biomass, %; C is the proportion of the mass of large-particle biomass to the total mass of biomass, %; where A+B+C<1; δ is a dimensionless correction coefficient, ranging from 1 to 3; Q is the proportion of the mass of gasified slag after gasification to the mass of medium-particle biomass, %; P is the proportion of the mass of gasified biomass to the mass of medium-particle biomass during gasification, %; T 2 is the ignition temperature, ℃; F is the iron ore grade, %. Y is the carbon saving ratio after biomass classification and quality treatment coupled with sintering process.

[0045] cii) Based on the relationship curve between the mass change of large-particle biomass laid on the sintering material surface and the ignition temperature, the relationship between the laying amount of large-particle biomass and the ignition temperature is established:

[0046] T 2 =1050-β*(0.5+5*D) 0.1 *In(1+5*D)……(Formula 4)

[0047] In (Formula 4), β is a coefficient related to the type of ore raw material, and its value range is 50-600, preferably 200-600, and more preferably 300-600; D is the mass of large-particle biomass laid on the sintering material surface as a percentage of the total mass of the sintering material, and its value range is 1%-15%, preferably 2%-10%, and more preferably 3%-8%; the minimum ignition temperature under the target working condition is calculated according to (Formula 4); combining (Formula 3) and (Formula 4), first calculate the mass of small-particle biomass required for the optimal energy consumption conditions for sintering ignition at the ignition temperature, and then obtain the mass distribution ratio of large-particle biomass and the mass distribution ratio of small-particle biomass, and finally calculate the mass distribution ratio of medium-particle biomass on the premise of satisfying the mass distribution ratio of large-particle biomass and the mass distribution ratio of small-particle biomass. Preferably, there is an optimal range for the percentage of the mass of the large-particle biomass laid on the sintering material surface to the total mass of the sintering material, that is, the optimal value range of D is 1% to 15%, preferably 2% to 10%, and more preferably 3% to 8%.

[0048] Preferably, the total mass of biomass is 1% to 2.6% of the mass of sintered ore, the value range of A is 5% to 12%, the value range of B is 55% to 75%, the value range of C is 18% to 28%, A+B+C≤1; the value range of P is 60% to 75%, the value range of Q is 25% to 40%, and P+Q=1.

[0049] According to a third embodiment of the present invention, a low-carbon sintering system is provided.

[0050] A low-carbon sintering system, the sintering system includes a sintering machine, a batching device, a distribution device, an ignition burner, a crushing device, a screening device, a gasification device, a ring cooler, and a blowing device. According to the running direction of the sintering machine, the sintering machine is divided into a drying section, a preheating section, and a roasting section. The ignition burner is arranged in an ignition furnace located above the downstream side of the preheating section. The material outlet of the batching device is connected to the material inlet of the distribution device. The material outlet of the distribution device is arranged at the feed end of the sintering machine. The blowing device is arranged above the roasting section. The discharge end of the sintering machine is connected to the feed end of the ring cooler.

[0051] The material outlet of the crushing device is connected to the material inlet of the screening device. The large particle material outlet of the screening device is connected to the material inlet of the material distribution device, the medium particle material outlet of the screening device is connected to the material inlet of the gasification device, and the small particle material outlet of the screening device is connected to the material inlet of the ignition burner. The gas outlet of the gasification device is connected to the fuel inlet of the injection device. The length of the sintering machine is 1 to 2000m, preferably 2 to 1500m, and more preferably 3 to 1000m. The length of the ring cooler is 1 to 800m.

[0052] Preferably, the screening device is further provided with an outlet for material on the screen, and the outlet for material on the screen is communicated with the material inlet of the crushing device.

[0053] Preferably, the system further comprises a forming device, the solid outlet of the gasification device is connected to the material inlet of the forming device, and the material outlet of the forming device is connected to the material inlet of the batching device.

[0054] Preferably, the gas inlet of the drying section is connected to the high-temperature gas outlet of the ring cooler or to the low-temperature medium outlet of the gasification device through a pipeline.

[0055] Preferably, the ignition burner includes a combustion-supporting air duct and a biomass duct. The air inlet end of the combustion-supporting air duct is connected to the oxygen-containing gas source, and the air outlet end of the combustion-supporting air duct is connected to the furnace of the ignition furnace. The feed end of the biomass duct is simultaneously connected to the fine particle material outlet of the screening device and the carrier gas source, and the discharge end of the biomass duct is connected to the furnace of the ignition furnace. The bottom of the ignition furnace is connected to the upper part of the downstream side of the preheating section.

[0056] Preferably, the discharge section of the biomass pipeline includes a gas discharge channel and a solid discharge channel sleeved outside the gas discharge channel.

[0057] Preferably, the combustion-supporting air duct includes a central air duct and a secondary air duct that are not connected to each other. The air inlet ends of the central air duct and the secondary air duct are both connected to the oxygen-containing gas source. The central air duct is sleeved in the tube cavity of the gas discharge channel along the axis of the gas discharge channel, and the secondary air duct is sleeved on the outside of the solid discharge channel. The air outlet ends of the central air duct and the secondary air duct are both connected to the furnace of the ignition furnace.

[0058] Preferably, the ignition burner further comprises a swirl mechanism, and the swirl mechanism is arranged at the gas outlet end of the secondary air duct and / or the gas outlet channel. Preferably, the swirl mechanism is a swirl blade.

[0059] Preferably, the carrier gas source is a gas outlet of the drying section.

[0060] Preferably, the gasification device includes a kiln body and a heat exchange device extending into the interior of the kiln body and not connected to the kiln body. Wherein, the kiln body includes a kiln head, a kiln body and a kiln tail connected in series. The kiln head and the kiln tail are fixedly arranged, and the kiln body can rotate along its axis. A gas-solid inlet is provided at the upper part of the kiln head, and the gas-solid inlet is connected to the medium-particle material outlet of the screening device and the high-humidity oxygen-containing gas source through a pipeline. A gas outlet is provided at the upper part of the kiln tail, and the gas outlet is connected to the fuel inlet of the blowing device through a pipeline. A solid outlet is provided at the lower part of the kiln tail, and the solid outlet is connected to the material inlet of the molding device or the material inlet of the batching device through a conveyor belt. Preferably, the high-humidity oxygen-containing gas source is the gas outlet of the drying section.

[0061] Preferably, the heat exchange device comprises an outer cylinder and an inner cylinder, the outer cylinder axially passes through the kiln head, the kiln body and the kiln tail in sequence, an inner cylinder is inserted at each end of the outer cylinder, and the inserted end of the inner cylinder extends along the axis of the outer cylinder to the middle of the inner cylinder cavity. High-temperature medium inlets are provided at both ends of the outer cylinder located outside the kiln body, and medium reflux ports are provided at the ends of the inner cylinder located inside the outer cylinder, and the inner cylinder is connected to the outer cylinder through the medium reflux ports. Low-temperature medium outlets are provided on the inner cylinder located outside the outer cylinder. Preferably, the high-temperature medium inlet is connected to the sintering flue. Preferably, a blind plate is also provided in the middle of the outer cylinder cavity, and the outer cylinder cavity is divided into two sections of tube cavities that are not connected to each other by the blind plate, and the two inner cylinders are respectively located in the two sections of tube cavities that are not connected to each other.

[0062] Preferably, 1 to 8 evenly distributed heat exchange devices are provided inside the kiln body.

[0063] Preferably, the gasification device also includes a water supply pipe, the water inlet end of the water supply pipe is connected to the new water source, the water outlet end of the water supply pipe passes through the kiln head and extends to the inside of the kiln body, and a plurality of atomizing nozzles are arranged on the water outlet pipe section of the water supply pipe.

[0064] Preferably, the kiln body is arranged in an inclined manner with the kiln head being high and the kiln tail being low. Preferably, the inclination angle of the kiln body is 2 to 8°, preferably 3 to 6°.

[0065] In the prior art, the biomass added to sintering is preferably woody plants in urban garden solid waste, such as pine, camphor, etc., and agricultural straw solid waste can be used secondarily. Their common feature is that the volatile matter is relatively high, and the volatile matter content can generally reach about 70%. At the same time, the biomass raw materials are irregular in shape, and the requirements for sintering fuel are low volatile matter (<5%) and strong heat release capacity, so biomass cannot be directly added to the sintering process. If the biomass is directly mixed into the sintering raw materials, it does not meet the low volatile matter requirements of sintering fuel, and it is easy to cause uneven heat distribution or insufficient heat in the sintering material layer.

[0066] In the present invention, the biomass is crushed and screened and divided into three grades, and large-particle biomass fuel is arranged on the surface of the sintering material layer to replace part of the coke powder. The medium-particle biomass fuel has a moderate particle size and a high reactivity, and is used for gasification to produce combustible gas. The small-particle biomass fuel has a high specific surface area, a light specific gravity, and a fast combustion speed, and is fed into the ignition burner as the ignition fuel of the ignition burner. The present invention divides the biomass into multiple grades according to the particle size, and adds biomass fuels of different particle sizes into the sintering process using different process methods, which can effectively improve the utilization rate of the biomass and achieve low-carbon sintering. In addition, the biomass with too large a particle size (i.e., super-large particle biomass fuel) can be returned to the crushing step for re-crushing to improve the utilization rate of the biomass.

[0067] In the present invention, based on a large number of experiments, the approximate range of the biomass fuel particle size classification is obtained, as follows. Since the particle size of coke powder in the sintering raw material is about 2 to 5 mm, the particle size of the large-particle biomass fuel is set to be closer to [a, b]. After the biomass fuel in this particle size range is laid on the surface of the sintering material layer, it is more reactive than coke powder and easier to ignite. After entering the preheating section, it can be quickly ignited, thereby improving the ignition efficiency and reducing the ignition energy consumption. In addition, since the biomass particle size in the [c, a) particle size range is moderate and has good reactivity, it is used for gasification to produce combustible gas. The remaining biomass fuel with a particle size of (0, c) is used as the ignition fuel of the ignition burner. Among them, the value of a is 1 to 3 mm; the value of b is 4 to 8 mm, and the value of c is 0.3 to 0.7 mm. In actual application, the specific values ​​of a, b, and c are determined according to the specific properties of the biomass.

[0068] The inventors have found through experimental research that medium-particle biomass (e.g., biomass with a particle size in the range of [c, a)) has a moderate particle size and good reactivity, and is most suitable for gasification to produce combustible gas (controlling the volatile matter and carbon content in the treated material). In the present invention, the gasification temperature of the medium-particle biomass fuel is above 700°C (preferably 800°C). In theory, the higher the gasification temperature, the higher the gasification reaction rate and the higher the carbon conversion rate. The gasification reaction uses water vapor and oxygen as gasifying agents, and the main reactions are as follows:

[0069] C+H 2 O=CO+H 2

[0070] C+O 2 =2CO

[0071] The main component of the combustible gas obtained by gasification is H 2 , CO and other combustible gases are sprayed into the sintering material layer to supplement the heat of the sintering material surface, which can effectively reduce the consumption of solid carbon in the sintering material layer and achieve low-carbon sintering. Preferably, the heat required for the gasification reaction comes from the high-temperature flue gas in the sintering flue, the flue gas temperature is >700°C, and indirect heat exchange (such as partition heat exchange) is adopted. In addition, the source of water vapor and oxygen can be the high-humidity hot air after drying in other processes (such as the high-humidity hot air generated in the drying section), which contains rich water vapor and air and has a higher temperature. The use of ready-made high-humidity hot air can reduce the consumption of new water and improve the waste heat utilization rate of high-humidity hot air. If the moisture content in the high-humidity hot air is insufficient, additional new water needs to be added.

[0072] In the present invention, in order to ensure that the combustible gas has sufficient H 2 , while making the medium-grained biomass fuel in H 2 In the CO atmosphere, the total mass of water vapor and oxygen is limited to the gas-to-solid mass ratio of the residual biomass to 0.4-0.8:1. The water vapor content in the high-humidity hot air and the amount of new water added are adjusted to make the volume ratio of water vapor to oxygen in the gasification reaction range from 1 to 2:1. 2 The content can improve the cleanliness of the combustion products. At the same time, the combustion of hydrogen releases more heat, which improves the energy utilization efficiency of the combustible gas.

[0073] In the present invention, the reaction vessel of the gasification process may be optionally a suspended bed reactor or a fixed bed reactor.

[0074] In the present invention, the medium-particle biomass fuel obtains combustible gas and gasification slag after gasification. The main component of the gasification slag is the carbon that has not been completely reacted in the biomass, and the carbon content is generally 20-30%, and the volatile matter is <5%. Compared with the biomass raw material, the volatile matter and carbon content of the gasification slag are greatly reduced, so its reactivity is relatively low and can participate in the sintering process. Preferably, since the pore structure of the gasification slag is still developed, in order to further reduce its reactivity and improve the utilization rate of biomass, the present invention adopts an extrusion molding method, and further defines the time, pressure and other parameters in the extrusion molding process, eliminates the pores of the gasification slag, forms a dense gasification slag molded fuel carbon, and then obtains carbon fuel after crushing. The obtained carbon fuel has low volatile matter, slow heat release, and high density, which meets the requirements of sintering for fuel, and can be directly mixed with the sintering raw material to replace part of the coke powder and reduce the use of fossil fuels.

[0075] In the present invention, in order to achieve a carbon content of not less than 20% and a volatile matter of not more than 5% in the gasified slag, the present invention calculates the gasification time t at which the carbon content in the gasified slag reaches the critical point based on the particle size, moisture content, carbon content and other parameters of the medium-sized biomass. 1 and the vaporization time t at which the volatile content is at the critical point 2 If t 2 ≤t 1 , indicating that there is a gasification time that satisfies both the carbon content and volatile content requirements at this temperature, and the actual gasification time t is set to satisfy t 2 ≤t≤t 1 When t 2 >t 1 When the volatile content is lower than the set value, it is a hard requirement, and the carbon content is higher than the set value, so t must be greater than or equal to t 2 , the actual vaporization time t at this temperature should be: t ≥ t 2 .

[0076] In the present invention, a dynamic mathematical model of the mass distribution ratio of large-particle biomass, medium-particle biomass and small-particle biomass is further proposed. At the same time, according to the relationship curve between the mass of large-particle biomass laid on the sintering material surface and the ignition temperature, a relationship between the laying amount of large-particle biomass and the ignition temperature is established. According to (Formula 4), the minimum ignition temperature under the target working condition can be calculated. Combining (Formula 3) and (Formula 4), the mass of small-particle biomass required for the optimal energy consumption condition of sintering ignition at the ignition temperature is first calculated, and then the mass distribution ratio of large-particle biomass and the mass distribution ratio of small-particle biomass are obtained. Finally, the mass distribution ratio of medium-particle biomass is calculated on the premise of satisfying the mass distribution ratio of large-particle biomass and the mass distribution ratio of small-particle biomass. In addition, regarding the values ​​of P and Q: According to (Formula 3), the larger the value of P, the larger the carbon saving ratio. The means to increase P include increasing the gasification temperature and residence time, but P cannot be increased indefinitely. When the temperature and residence time reach a certain level, P will not increase again, and P takes the maximum value at this time. Preferably, the total mass of biomass is 1% to 2.6% of the mass of sintered ore, the value range of A is 5% to 12%, the value range of B is 55% to 75%, the value range of C is 18% to 28%, A+B+C<1; the value range of P is 60% to 75%, the value range of Q is 25% to 40%, and P+Q=1.

[0077] In the present invention, under the premise of meeting the requirements of the ignition process, the maximum carbon saving of the technical solution is achieved by controlling the mass distribution ratio of large-particle biomass, medium-particle biomass and small-particle biomass. Through iterative calculation, the mass distribution ratio of large-particle biomass, medium-particle biomass and small-particle biomass that can achieve the maximum carbon saving is obtained; then the crushing, screening and grading processes are controlled to obtain the mass distribution amount of large-particle biomass, medium-particle biomass and small-particle biomass that require a specific ratio.

[0078] In the present invention, according to the running direction of the sintering trolley, a drying section is set upstream of the preheating section, and ambient air (preferably hot air discharged from the ring cooler or low-temperature flue gas discharged from the sintering flue and used for gasification and hydrogen production) is introduced to dry the sintering raw materials, take away the moisture added to the sintering raw materials during the mixing and granulation process, reduce the subsequent energy consumption, and avoid the formation of an over-wet zone in the sintering material layer, which affects the air permeability of the sintering material layer.

[0079] In the present invention, an ignition burner structure is also proposed, which transports gas to the sintering material surface through the combustion-supporting air duct and the biomass duct and ignites and heats. Preferably, since the biomass will be pyrolyzed when it exceeds 300°C, the burner is under the high temperature (850°C to 1050°C) of the sintering furnace, and the internal temperature of the burner is likely to exceed 300°C, so that the biomass is pyrolyzed. The present invention sets the biomass duct as an inner solid discharge channel and a gas discharge channel sleeved on the outside of the solid discharge channel. After the biomass powder is pyrolyzed, it enters the burner from the tangential direction to generate a vortex. Due to the density difference between the gas and the solid, the solid biomass powder moves to the outside of the center and enters the solid discharge channel, while the gas is close to the center, thereby generating a certain cyclone separation, and the gas enters the gas discharge channel, enters the ignition furnace hearth, mixes with the combustion-supporting gas, and burns, and is connected to the upper part of the downstream side of the preheating section through the bottom of the ignition furnace hearth, completing the sintering ignition. Preferably, the combustion-supporting air duct is divided into a central air duct and a secondary air duct, the outlet end of the central air duct is arranged inside the gas discharge channel, and the outlet end of the secondary air duct is sleeved outside the solid discharge channel. Under the joint action of the central air and the secondary air, the combustion-supporting air can be fully mixed with the biomass powder and the pyrolysis gas. Furthermore, a swirl mechanism is provided in the gas discharge channel and / or the secondary air duct, and the swirling combustion-supporting gas entrains the biomass powder, the pyrolysis gas and the internal combustion-supporting air to make them strongly mixed, thereby achieving efficient combustion.

[0080] In the present invention, a gasification device structure is also proposed, in which a kiln body and a heat exchange device are provided, and indirect heat exchange is used to provide heat for biomass gasification to increase the gasification temperature. Biomass and high-humidity oxygen-containing gas enter from the gas-solid inlet. After the reaction in the kiln body is completed, the generated gasification gas (i.e., combustible gas) is discharged from the gas outlet, and the gasified slag moves to the kiln tail under the rotation of the kiln body, and is finally discharged from the solid outlet. In addition, the kiln body can also be set to an inclined setting with a high kiln head and a low kiln tail, and combined with a rotatable kiln body, it is conducive to the discharge of gasified slag. Preferably, the heat exchange device is set to a sleeve structure, and the hot flue gas enters from the outer cylinder and indirectly contacts the biomass. After heat exchange, it is discharged from the inner cylinder, which reduces the contact between the biomass and the low-temperature flue gas. Further preferably, in addition to the high-humidity oxygen-containing gas carrying a large amount of water vapor, a water supply pipeline is also provided. After the water enters the kiln body, it reacts secondary with the biomass, which is convenient for controlling the ratio of water vapor to oxygen, increasing the gasification intensity, and increasing the H in the gasification gas. 2 of production.

[0081] In the present invention, the formulas in the present invention are obtained by fitting by the inventor based on experiments and engineering applications, and all calculations are numerical values ​​converted according to prescribed units, and the numerical values ​​after conversion are substituted into the formulas for calculation (after the units of each parameter are converted, only the numerical values ​​are substituted into the formulas for calculation, without substituting the units, and the units are only used to adjust the size of the numerical values).

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] 1. The present invention provides a low-carbon sintering method, which crushes and screens biomass into multiple grades, and adds them to different processes for utilization according to different particle sizes, thereby effectively improving the utilization rate of biomass and achieving low-carbon sintering.

[0084] 2. The present invention provides a biomass fractionation process for a low-carbon sintering method. According to the properties of the biomass, the gasification time is calculated to make the carbon content and volatile matter content in the gasified slag meet the requirements. In addition, by controlling the mass distribution ratio of large, medium and small particle biomass, the normal operation requirements of sintering supply and demand are met while achieving refined control, thereby reducing carbon emissions and fossil fuel usage.

[0085] 3. The low-carbon sintering system provided by the present invention has a simple structure and can realize the utilization of biomass according to different particle sizes after crushing. At the same time, the structure of the ignition burner can quickly mix the combustion-supporting gas and the fuel to achieve efficient combustion, and the gasification intensity and H in the gasified gas can be increased by the gasification device. 2 The output is high and has high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 A schematic structural diagram of a low-carbon sintering system provided by the present invention.

[0087] Figure 2 Another structural schematic diagram of a low-carbon sintering system provided by the present invention.

[0088] Figure 3 A schematic structural diagram of an ignition burner in a low-carbon sintering system provided by the present invention.

[0089] Figure 4 A schematic structural diagram of a gasification device in a low-carbon sintering system provided by the present invention.

[0090] Figure 5 Produce a flow chart for the existing sintering process.

[0091] Reference numerals: 1: sintering machine; 101: drying section; 102: preheating section; 103: roasting section; 2: batching device; 3: material distribution device; 4: ignition burner; 401: combustion air duct; 4011: central air duct; 4012: secondary air duct; 402: biomass duct; 4021: gas discharge channel; 4022: solid discharge channel; 403: cyclone mechanism; 5: crushing device; 6: screening device; 7: gasification device; 701: kiln body; 70 11: kiln head; 7012: kiln body; 7013: kiln tail; 7014: gas-solid inlet; 7015: gas outlet; 7016: solid outlet; 702: heat exchange device; 7021: high-temperature medium inlet; 7022: low-temperature medium outlet; 7023: outer cylinder; 7024: inner cylinder; 7025: medium return port; 7026: blind plate; 7027: water supply pipeline; 7028: atomizing nozzle; 8: ring cooler; 9: blowing device; 10: forming device. DETAILED DESCRIPTION

[0092] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0093] A low-carbon sintering system, the sintering system comprises a sintering machine 1, a batching device 2, a distribution device 3, an ignition burner 4, a crushing device 5, a screening device 6, a gasification device 7, a ring cooler 8, and a blowing device 9. According to the running direction of the sintering machine 1, the sintering machine 1 is divided into a drying section 101, a preheating section 102, and a roasting section 103. The ignition burner 4 is arranged in an ignition furnace located above the downstream side of the preheating section 102. The material outlet of the batching device 2 is connected to the material inlet of the distribution device 3. The material outlet of the distribution device 3 is arranged at the feed end of the sintering machine 1. The blowing device 9 is arranged above the roasting section 103. The discharge end of the sintering machine 1 is connected to the feed end of the ring cooler 8.

[0094] The material outlet of the crushing device 5 is connected to the material inlet of the screening device 6. The large particle material outlet of the screening device 6 is connected to the material inlet of the material distribution device 3, the medium particle material outlet of the screening device 6 is connected to the material inlet of the gasification device 7, and the small particle material outlet of the screening device 6 is connected to the material inlet of the ignition burner 4. The gas outlet of the gasification device 7 is connected to the fuel inlet of the injection device 9.

[0095] Preferably, the screening device 6 is further provided with an outlet for material on the screen, and the outlet for material on the screen is communicated with the material inlet of the crushing device 5 .

[0096] Preferably, the system further comprises a forming device 10 , the solid outlet of the gasification device 7 is communicated with the material inlet of the forming device 10 , and the material outlet of the forming device 10 is communicated with the material inlet of the batching device 2 .

[0097] Preferably, the gas inlet of the drying section 101 is connected to the high-temperature gas outlet of the ring cooler 8 or to the low-temperature medium outlet of the gasification device 7 through a pipeline.

[0098] Preferably, the ignition burner 4 includes a combustion-supporting air duct 401 and a biomass duct 402. The air inlet end of the combustion-supporting air duct 401 is connected to the oxygen-containing gas source, and the air outlet end of the combustion-supporting air duct 401 is connected to the furnace of the ignition furnace. The feed end of the biomass duct 402 is simultaneously connected to the fine particle material outlet of the screening device 6 and the carrier gas source, and the discharge end of the biomass duct 402 is connected to the furnace of the ignition furnace.

[0099] Preferably, the discharge section of the biomass pipeline 402 includes a gas discharge channel 4021 and a solid discharge channel 4022 sleeved outside the gas discharge channel 4021 .

[0100] Preferably, the combustion-supporting air duct 401 includes a central air duct 4011 and a secondary air duct 4012 which are not connected to each other. The air inlet ends of the central air duct 4011 and the secondary air duct 4012 are both connected to the oxygen-containing gas source. The central air duct 4011 is sleeved in the tube cavity of the gas discharge channel 4021 along the axis of the gas discharge channel 4021, and the secondary air duct 4012 is sleeved on the outside of the solid discharge channel 4022. The air outlet ends of the central air duct 4011 and the secondary air duct 4012 are both connected to the furnace of the ignition furnace.

[0101] Preferably, the ignition burner 4 further comprises a swirl mechanism 403, and the swirl mechanism 403 is arranged at the gas outlet end of the secondary air duct 4012 and / or the gas outlet channel 4021. Preferably, the swirl mechanism 403 is a swirl blade.

[0102] Preferably, the carrier gas source is the gas outlet of the drying section 101 .

[0103] Preferably, the gasification device 7 includes a kiln body 701 and a heat exchange device 702 extending into the kiln body 701 and not connected to the kiln body 701. The kiln body 701 includes a kiln head 7011, a kiln body 7012 and a kiln tail 7013 connected in series. The kiln head 7011 and the kiln tail 7013 are fixedly arranged, and the kiln body 7012 can rotate along its axis. A gas-solid inlet 7014 is provided at the upper part of the kiln head 7011, and the gas-solid inlet 7014 is connected to the medium particle material outlet and the high-humidity oxygen-containing gas source of the screening device 6 through a pipeline. A gas outlet 7015 is provided at the upper part of the kiln tail 7013, and the gas outlet 7015 is connected to the fuel inlet of the blowing device 9 through a pipeline. A solid outlet 7016 is provided at the lower part of the kiln tail 7013, and the solid outlet 7016 is connected to the material inlet of the forming device 10 or the material inlet of the batching device 2 through a conveyor belt. Preferably, the high-humidity oxygen-containing gas source is the gas outlet of the drying section 101 .

[0104] Preferably, the heat exchange device 702 includes an outer cylinder 7023 and an inner cylinder 7024, the outer cylinder 7023 sequentially penetrates the kiln head 7011, the kiln body 7012 and the kiln tail 7013 in the axial direction, an inner cylinder 7024 is inserted at each end of the outer cylinder 7023, and the insertion end of the inner cylinder 7024 extends along the axis of the outer cylinder 7023 to the middle of the cylinder cavity of the inner cylinder 7024. High-temperature medium inlets 7021 are provided at both ends of the outer cylinder 7023 located outside the kiln body 701, and medium return ports 7025 are provided at the ends of the inner cylinder 7024 located inside the outer cylinder 7023, and the inner cylinder 7024 is connected to the outer cylinder 7023 through the medium return ports 7025. Low-temperature medium outlets 7022 are provided on the inner cylinder 7024 located outside the outer cylinder 7023. Preferably, the high-temperature medium inlet 7021 is connected to the sintering flue. Preferably, a blind plate 7026 is further provided in the middle of the outer tube 7023 cavity, and the blind plate 7026 divides the outer tube 7023 cavity into two mutually unconnected cavities, and the two inner tubes 7024 are respectively located in the two mutually unconnected cavities.

[0105] Preferably, 1 to 8 evenly distributed heat exchange devices 702 are provided inside the kiln body 701 .

[0106] Preferably, the gasification device 7 also includes a water supply pipe 7027, the water inlet end of the water supply pipe 7027 is connected to the new water source, the water outlet end of the water supply pipe 7027 passes through the kiln head 7011 and extends to the inside of the kiln body 7012, and a plurality of atomizing nozzles 7028 are arranged on the water outlet pipe section of the water supply pipe 7027.

[0107] Preferably, the kiln body 701 is tilted with a kiln head 7011 being high and a kiln tail 7013 being low. Preferably, the inclination angle of the kiln body 701 is 2 to 8°, preferably 3 to 6°.

[0108] Example 1

[0109] A low carbon sintering system, such as Figure 1-4 As shown, the sintering system includes a sintering machine 1, a batching device 2, a distribution device 3, an ignition burner 4, a crushing device 5, a screening device 6, a gasification device 7, a ring cooler 8, and a blowing device 9. According to the running direction of the sintering machine 1, the sintering machine 1 is divided into a drying section 101, a preheating section 102, and a roasting section 103. The ignition burner 4 is arranged in the ignition furnace above the downstream side of the preheating section 102. The material outlet of the batching device 2 is connected to the material inlet of the distribution device 3. The material outlet of the distribution device 3 is arranged at the feed end of the sintering machine 1. The blowing device 9 is arranged above the roasting section 103. The discharge end of the sintering machine 1 is connected to the feed end of the ring cooler 8.

[0110] The material outlet of the crushing device 5 is connected to the material inlet of the screening device 6. The large particle material outlet of the screening device 6 is connected to the material inlet of the material distribution device 3, the medium particle material outlet of the screening device 6 is connected to the material inlet of the gasification device 7, and the small particle material outlet of the screening device 6 is connected to the material inlet of the ignition burner 4. The gas outlet of the gasification device 7 is connected to the fuel inlet of the injection device 9.

[0111] Example 2

[0112] Example 1 is repeated, except that the screening device 6 is further provided with an outlet for materials on the screen, and the outlet for materials on the screen is connected to the material inlet of the crushing device 5 .

[0113] The system further comprises a forming device 10 , the solid outlet of the gasification device 7 is communicated with the material inlet of the forming device 10 , and the material outlet of the forming device 10 is communicated with the material inlet of the batching device 2 .

[0114] The gas inlet of the drying section 101 is connected to the high-temperature gas outlet of the ring cooler 8 through a pipeline.

[0115] Example 3

[0116] Example 2 is repeated, except that the ignition burner 4 includes a combustion-supporting air duct 401 and a biomass duct 402. The air inlet end of the combustion-supporting air duct 401 is connected to the oxygen-containing gas source, and the air outlet end of the combustion-supporting air duct 401 is connected to the furnace of the ignition furnace. The feed end of the biomass duct 402 is simultaneously connected to the fine particle material outlet of the screening device 6 and the carrier gas source, and the discharge end of the biomass duct 402 is connected to the furnace of the ignition furnace.

[0117] The discharge section of the biomass pipeline 402 includes a gas discharge channel 4021 and a solid discharge channel 4022 sleeved outside the gas discharge channel 4021 .

[0118] Example 4

[0119] Example 3 is repeated, except that the combustion-supporting air duct 401 includes a central air duct 4011 and a secondary air duct 4012 that are not connected to each other. The air inlet ends of the central air duct 4011 and the secondary air duct 4012 are both connected to the oxygen-containing gas source. The central air duct 4011 is sleeved in the tube cavity of the gas discharge channel 4021 along the axis of the gas discharge channel 4021, and the secondary air duct 4012 is sleeved on the outside of the solid discharge channel 4022. The air outlet ends of the central air duct 4011 and the secondary air duct 4012 are both connected to the furnace of the ignition furnace.

[0120] Example 5

[0121] The embodiment 4 is repeated, except that the ignition burner 4 further includes a swirl mechanism 403, which is arranged at the outlet ends of the secondary air duct 4012 and the gas outlet channel 4021. The swirl mechanism 403 is a swirl blade.

[0122] The carrier gas source is the gas outlet of the drying section 101 .

[0123] Example 6

[0124] Repeat Example 5, except that the gasification device 7 includes a kiln body 701 and a heat exchange device 702 extending into the kiln body 701 and not connected to the kiln body 701. Wherein, the kiln body 701 includes a kiln head 7011, a kiln body 7012 and a kiln tail 7013 connected in series. The kiln head 7011 and the kiln tail 7013 are fixedly arranged, and the kiln body 7012 can rotate along its axis. A gas-solid inlet 7014 is provided at the upper part of the kiln head 7011, and the gas-solid inlet 7014 is connected to the medium particle material outlet and the high-humidity oxygen-containing gas source of the screening device 6 through a pipeline. A gas outlet 7015 is provided at the upper part of the kiln tail 7013, and the gas outlet 7015 is connected to the fuel inlet of the blowing device 9 through a pipeline. A solid outlet 7016 is provided at the lower part of the kiln tail 7013, and the solid outlet 7016 is connected to the material inlet of the forming device 10 through a conveyor belt. The high-humidity oxygen-containing gas source is the gas outlet of the drying section 101 .

[0125] Example 7

[0126] Example 6 is repeated, except that the heat exchange device 702 includes an outer cylinder 7023 and an inner cylinder 7024. The outer cylinder 7023 sequentially penetrates the kiln head 7011, the kiln body 7012 and the kiln tail 7013 in the axial direction. An inner cylinder 7024 is inserted at each end of the outer cylinder 7023, and the inserted ends of the inner cylinder 7024 extend along the axis of the outer cylinder 7023 to the middle of the cylinder cavity of the inner cylinder 7024. High-temperature medium inlets 7021 are provided at both ends of the outer cylinder 7023 located outside the kiln body 701, and medium return ports 7025 are provided at the ends of the inner cylinder 7024 located inside the outer cylinder 7023. The inner cylinder 7024 is connected to the outer cylinder 7023 through the medium return ports 7025. Low-temperature medium outlets 7022 are provided on the inner cylinder 7024 located outside the outer cylinder 7023. The high-temperature medium inlet 7021 is connected to the sintering flue. A blind plate 7026 is also provided in the middle of the outer tube 7023 cavity, and the outer tube 7023 cavity is divided into two mutually unconnected cavities by the blind plate 7026. The two inner tubes 7024 are respectively located in the two mutually unconnected cavities.

[0127] Example 8

[0128] Example 7 is repeated, except that two evenly distributed heat exchange devices 702 are provided inside the kiln body 701 .

[0129] The gasification device 7 also includes a water supply pipe 7027, the water inlet end of the water supply pipe 7027 is connected to the new water source, the water outlet end of the water supply pipe 7027 passes through the kiln head 7011 and extends to the inside of the kiln body 7012, and 5 atomizing nozzles 7028 are arranged on the water outlet pipe section of the water supply pipe 7027.

[0130] The kiln body 701 is tilted with a kiln head 7011 being high and a kiln tail 7013 being low. The inclination angle of the kiln body 701 is 5°.

[0131] Application Example 1

[0132] A low-carbon sintering method, using the system described in Example 8, performs the following steps:

[0133] 1) Biomass pretreatment: 1000kg of biomass was crushed and sieved to obtain 270.1kg of large-particle biomass with a particle size of [2mm-5mm], 529kg of medium-particle biomass with a particle size of [0.5mm-2mm), and 149.7kg of small-particle biomass with a particle size of less than 0.5mm. The medium-particle biomass was gasified at 900°C for 5.5 minutes and then converted into about 111.1kg of gasified slag and combustible gas. In addition, 51.2kg of super-large-particle biomass with a particle size greater than 5mm was obtained by screening and grading, and the super-large-particle biomass was returned to the crushing process for re-crushing.

[0134] 2) Sintering batching and distribution: 9200kg of iron ore powder, 250kg of flux and 210kg of coke powder are batched to obtain 9850kg of sintering material. The sintering material is firstly distributed on the sintering trolley, and then introduced with 400°C high temperature hot air for drying. Finally, 270.1kg of large-particle biomass is arranged on the surface of the sintering material to obtain a mixed sintering material.

[0135] 3) Sintering treatment: the mixed sintering material moves forward at a uniform speed along with the sintering trolley and is sequentially ignited, roasted and cooled to obtain the sintered finished material; during the sintering process: the 149.7 kg small-particle biomass is fed into the ignition burner as an ignition fuel, and the combustible gas is sprayed onto the surface of the sintering mixture to participate in the roasting treatment.

[0136] 4) 111.1 kg of gasified slag is extruded and degassed at 25 MPa, and after passing through a mold, 111.1 kg of molded slag with a particle size of 3 to 5 mm is prepared; and then the 111.1 kg of molded slag is added to the batching process of step 2).

[0137] Application Example 2

[0138] A biomass fractionation treatment process for applying the sintering method described in Example 1 is provided:

[0139] a) According to the properties of biomass, the reaction process is controlled so that the volatile matter content in the gasified slag is not higher than 8%, and the carbon content in the gasified slag is not lower than 20%; the gasification process is carried out in a fixed bed reactor, and at a given gasification temperature, the time for the carbon content in the gasified slag to be equal to the set value is:

[0140]

[0141] In the formula, C 0 is the initial carbon content in the medium-grained biomass, which is 50%; C 1 is the set value of carbon content in medium-sized biomass particles, which is 20%; L is the particle size of medium-sized biomass particles, which is 1.2 mm; M is the moisture content in biomass, which is 8%; T 1 is the vaporization temperature, which is 900℃; t ′ 1 The time required for the temperature to rise to the carbon reaction in the biomass is 0.5min; α and η are adjustment coefficients, where α is 0.45 and η is 0.1;

[0142] At the same gasification temperature, the time for the volatile matter content in the gasified slag to be no higher than the set value is:

[0143]

[0144] Where V0 is the initial volatile content in the medium-grained biomass, which is 70%; V 1 is the set value of the volatile content in the medium-sized biomass particles, which is 6%; L is the particle size of the medium-sized biomass particles, which is 1.2 mm; M is the moisture content in the biomass, which is 8%; T 1 is the vaporization temperature, which is 900℃; t ′ 2 The time required for the temperature to rise to the time required for the volatile matter in the biomass to react is 0.5 min; γ and μ are adjustment coefficients, where γ is 0.20 and μ is 0.10;

[0145] According to equations 1 and 2, the vaporization time t at this temperature should be: t 2 ≤t≤t 1 , that is, 4.61min≤t≤5.45min, so t can be controlled to be 5min.

[0146] The gasification treatment described in step 1) is changed to: placing 529 kg of medium-sized biomass particles in a mixed atmosphere containing water vapor and oxygen, and performing thermal gasification treatment at 900° C. for 5 minutes to obtain about 132.3 kg of gasified slag and combustible gas.

[0147] b) The volatile matter content in the gasified slag was detected to be 5.98%, and the carbon content was 21.13%, and there was no need to return to the gasification process.

[0148] c) In the process of biomass crushing and screening and grading, the mass distribution ratio of the obtained large-particle biomass, medium-particle biomass and small-particle biomass is controlled, thereby reducing carbon emissions while meeting the normal operation requirements of the sintering process, specifically including: ci) While meeting the normal operation requirements of the sintering process, carbon emissions are reduced and a dynamic mathematical model of the mass distribution ratio of large-particle biomass, medium-particle biomass and small-particle biomass is established:

[0149]

[0150] Among them, A is the proportion of the mass of small-particle biomass to the total mass of biomass, %; B is the proportion of the mass of medium-particle biomass to the total mass of biomass, %; C is the proportion of the mass of large-particle biomass to the total mass of biomass, %; δ is the dimensionless correction coefficient, which is 2.3; Q is the proportion of the mass of gasified slag after gasification to the mass of medium-particle biomass, which is 25%; P is the proportion of the mass of gasified biomass to the mass of medium-particle biomass during gasification, which is 75%; T 2 is the ignition temperature, °C; F is the iron ore grade, which is 60%;

[0151] cii) Based on the relationship curve between the mass change of large-particle biomass laid on the sintering material surface and the ignition temperature, the relationship between the laying amount of large-particle biomass and the ignition temperature is established:

[0152] T 2 =1050-β*(0.5+5*D) 0.1 *In(1+5*D)……(Formula 4)

[0153] Among them, β is a coefficient related to the type of ore raw materials, and its value is 550; D is the percentage of the mass of large-particle biomass laid on the sintering surface material to the total mass of the sintering surface material, and its value is 5.6%. The ignition temperature T is calculated according to (Formula 4): 2 The temperature is 917.5° C. According to D and the total mass of the sintered surface ore, the proportion of large-particle biomass to the total mass of biomass is further calculated to be 28%.

[0154] The mass A of small biomass particles required under the optimal energy consumption conditions for sintering ignition is 5%. Finally, the mass distribution ratio of medium biomass particles B∈[55%, 62%] is calculated under the premise of satisfying the minimum mass distribution ratio of large biomass particles (i.e., C≥28%) and the minimum mass distribution ratio of small biomass particles (i.e., A≥5%). According to (Formula 3), the larger the B and C, the smaller the A, and the larger the value of Y. Since the mass of super-large biomass particles accounts for 5.1%, the mass distribution ratios of large, medium, and small biomass particles are modified as follows: A is 5%, B is 61.9%, and C is 28%. And further, according to (Formula 3), the value of Y is 11.82%.

[0155] The same method as in Application Example 1 was adopted to adjust the gasification temperature in step 1) and the volume ratio of water vapor to oxygen during the gasification process, and parallel experiments were carried out. The specific experimental parameters are shown in Table 1.

[0156] Table 1 Comparison of gasification reaction parameters

[0157]

[0158]

[0159] The same method as in Application Example 2 was adopted to adjust the mass distribution ratio among large biomass particles, medium biomass particles, and small biomass particles in step 1), the mass ratio of medium biomass particles that become gasified slag and combustible gas during gasification, and the ignition temperature, and parallel experiments were conducted. The specific experimental parameters are shown in Table 2. The carbon saving ratio is: the difference between the fossil fuel consumption after adding biomass and the fossil fuel consumption before adding biomass under the process conditions, accounting for the ratio of the fossil fuel consumption before adding biomass.

[0160] Table 2 Comparison of mass distribution parameters and corresponding energy consumption of biomass pellets

[0161]

[0162]

[0163] Comparative Example 1

[0164] 9200kg of iron ore powder, 250kg of flux and 210kg of coke powder were mixed to obtain 9850kg of sintering material. The sintering material was first placed on the sintering trolley, and then dried by passing 400℃ hot air. Finally, 1000kg of crushed biomass was placed on the surface of the sintering material to obtain mixed sintering material. The mixed sintering material moved at a uniform speed along the sintering trolley and was ignited, roasted and cooled in sequence to obtain the sintered finished material.

[0165] Comparative Example 2

[0166] 9200kg iron ore powder, 250kg flux, 210kg coke powder and 1000kg crushed biomass are mixed to obtain 10850kg sintering material. The sintering material is first placed on the sintering trolley, then 400℃ hot air is introduced for drying, and finally 1000kg crushed biomass is placed on the surface of the sintering material to obtain mixed sintering material. The mixed sintering material moves at a uniform speed along the sintering trolley and is ignited, roasted and cooled in sequence to obtain the sintered finished material.

[0167] The sintered finished materials obtained by using Examples 1, 3 to 18 and Comparative Examples 1 and 2 were tested to obtain the sintering coke consumption and the CO and CO in the flue gas. 2 The concentration test results are shown in Table 3.

[0168] Table 3 Comparison of energy consumption and carbon emissions

[0169]

[0170]

[0171] According to the above experimental results, the present invention provides a low-carbon sintering method, process and system, which crushes and screens the biomass into multiple grades, and adds them to different processes for utilization according to the different particle sizes. The gasification time is limited according to the properties of the biomass, and fine control is performed, which effectively improves the utilization rate of the biomass and realizes low-carbon sintering.

Claims

1. A low carbon sintering method, characterized in that: The method comprises the following steps: 1) Biomass pretreatment: crushing and sieving the biomass to obtain large-particle biomass, medium-particle biomass, and small-particle biomass; gasifying the medium-particle biomass to obtain combustible gas and gasification slag; 2) Sintering batching and distribution: After the sintering raw materials are batched, the sintering materials are first distributed on the sintering machine trolley, and then optionally dried or not, and finally large biomass particles are laid on the surface of the sintering materials to obtain the sintering materials containing biomass; 3) Sintering treatment: The sintering material containing biomass moves forward with the sintering trolley and undergoes ignition, roasting and cooling treatments in sequence to obtain the sintered finished material; in the ignition process: small particles of biomass are sent to the ignition burner as ignition fuel for ignition; in the roasting process: combustible gas is sprayed onto the surface of the sintering mixture to participate in roasting.

2. The sintering method according to claim 1, characterized in that: In step 1), the particle size of the large biomass particles is [a, b], the particle size of the medium biomass particles is [c, a), and the particle size of the small biomass particles is (0, c); Among them, the value of a is 1 to 3 mm; the value of b is 4 to 8 mm, and the value of c is 0.3 to 0.7 mm; Preferably, the oversized biomass particles with a particle size greater than b are returned to the crushing process for re-crushing.

3. The sintering method according to claim 1 or 2, characterized in that: The gasified slag obtained in step 1) is used as one of the sintering raw materials to participate in the batching.

4. The low-carbon sintering method according to any one of claims 1 to 3, characterized in that: In step 1), the gasification treatment is specifically as follows: placing the medium-sized biomass particles in a mixed atmosphere containing water vapor and oxygen for thermal gasification treatment to obtain combustible gas and gasified slag respectively; wherein the temperature of the thermal gasification treatment is not less than 700° C., preferably not less than 800° C.; Preferably, the gas-solid mass ratio of the total mass of the water vapor and oxygen to the biomass is 0.4 to 0.8:1, preferably 0.5 to 0.7:1; Preferably, in the mixed atmosphere, the volume ratio of water vapor to oxygen is 1 to 2:1, preferably 1.2 to 1.5:

1.

5. The low carbon sintering method according to claim 4, characterized in that: The gasification process is carried out in a suspended bed reactor or a fixed bed reactor; Preferably, the heat source in the gasification process is the high-temperature flue gas in the sintering flue; preferably, the heat exchange method between the high-temperature flue gas and the biomass is indirect heat exchange; Preferably, the water vapor and oxygen in the gasification process are entirely or partially derived from the high-humidity hot air discharged from the drying section of the sintering process, and new water is used as a supplementary source of water vapor.

6. The low carbon sintering method according to claim 4 or 5, characterized in that: The sintering raw materials in step 2) are iron ore, quicklime, coke powder and optionally gasified slag; and / or The drying treatment described in step 2) is: introducing high-temperature hot air of not less than 300°C into the sintering trolley to contact the sintering material to achieve heat exchange drying; preferably, the high-temperature hot air of not less than 300°C is the hot air generated during the cooling process and / or the flue gas obtained during the gasification process.

7. The low-carbon sintering method according to any one of claims 1 to 6, characterized in that: The method further comprises: 4) forming the gasified slag obtained in step 1) to obtain formed slag, and using the formed slag as one of the sintering raw materials to participate in the batching; Preferably, the forming process is specifically: extruding, exhausting and crushing the obtained gasified slag.

8. The low-carbon sintering method according to claim 7, characterized in that: The extrusion pressure during the extrusion exhaust process is 15 to 30 MPa, preferably 20 to 28 MPa; and / or The particle size of the molded slag obtained after crushing is 2 to 7 mm, preferably 3 to 5 mm.

9. A biomass fractionation process for the low-carbon sintering method according to any one of claims 1 to 8, characterized in that: The biomass fractionation treatment process comprises: a) controlling gasification reaction parameters according to the properties of the biomass so that the volatile content in the gasified slag is not higher than a set value; and further preferably, the carbon content in the gasified slag is not lower than a set value; Preferably, the volatile matter content in the gasified slag is not higher than the set value: the volatile matter content in the gasified slag is not higher than 8%, preferably not higher than 5%; the carbon content in the gasified slag is higher than the set value: the carbon content in the gasified slag is not lower than 20%, preferably not lower than 25%.

10. The biomass fractionation treatment process according to claim 9, characterized in that: The gasification process is carried out in a fixed bed reactor, and the control gasification reaction parameters are: At a given gasification temperature, the theoretical gasification time required to calculate the carbon content in the gasified slag to be equal to the set value is: Wherein, C0 is the initial carbon content in the medium-sized biomass particles, %; C1 is the set value of the carbon content in the gasified slag, %; L is the particle size of the medium-sized biomass particles, mm; M is the moisture content in the biomass, %; T1 is the vaporization temperature, °C; t ′ 1 is the time required for the temperature to rise to the carbon reaction in the biomass; α and η are adjustment coefficients, where the value range of α is 0.20-0.30, and the value range of η is 0.10-0.20; At the same gasification temperature, the theoretical gasification time required for the volatile matter content in the gasified slag to be equal to the set value is: Wherein, V0 is the initial volatile content in the medium-sized biomass particles, %; V1 is the set value of the volatile content in the gasified slag, %; L is the particle size of the medium-sized biomass particles, mm; M is the moisture content in the biomass, %; T1 is the vaporization temperature, °C; t ′ 2 is the time required for the temperature to rise to the time required for the volatile matter in the biomass to react; γ and μ are adjustment coefficients, where the value range of γ is 0.08-0.15; the value range of μ is 0.10-0.20; Then the actual gasification time is controlled as: When t2≤t1, the temperature meets the vaporization condition. According to (Formula 1) and (Formula 2), the actual vaporization time t at this temperature is controlled to be: t2≤t≤t1; When t2>t1, the actual vaporization time t at the temperature is controlled to be: t≥t2.

11. The biomass fractionation treatment process according to claim 10, characterized in that: The process also includes: b) detecting the volatile matter content and carbon content in the gasified slag, and returning the gasified slag with too high volatile matter content and carbon content to the gasification process of the medium-particle biomass for re-gasification.

12. The biomass fractionation treatment process according to any one of claims 9 to 11, characterized in that: The process also includes: c) during the biomass crushing and screening and grading process, controlling the mass distribution ratio of the obtained large-particle biomass, medium-particle biomass and small-particle biomass, thereby reducing carbon emissions while meeting the normal operation requirements of the sintering process; which specifically includes: ci) To reduce carbon emissions while meeting the normal operation requirements of the sintering process, a dynamic mathematical model of the mass distribution ratio of large-particle biomass, medium-particle biomass and small-particle biomass is established: In (Formula 3), A is the proportion of the mass of small-particle biomass to the total mass of biomass, %; B is the proportion of the mass of medium-particle biomass to the total mass of biomass, %; C is the proportion of the mass of large-particle biomass to the total mass of biomass, %; wherein, A+B+C<1; δ is a dimensionless correction coefficient, which takes a value of 1 to 3; Q is the proportion of the mass of gasified slag after gasification to the mass of medium-particle biomass, %; P is the proportion of the mass of gasified biomass to the mass of medium-particle biomass during gasification, %; T2 is the ignition temperature, °C; F is the grade of iron ore, %; Y is the carbon saving ratio after the biomass classification and quality treatment coupled with the sintering process; cii) Based on the relationship curve between the mass change of large-particle biomass laid on the sintering material surface and the ignition temperature, the relationship between the laying amount of large-particle biomass and the ignition temperature is established: T2 = 1050 - β * (0.5 + 5 * D) 0.1 *In(1 + 5 * D)……(Equation 4) In (Formula 4), β is a coefficient related to the type of ore raw material, and its value range is 50-600, preferably 200-600, and more preferably 300-600; D is the mass of large-particle biomass laid on the sintering material surface as a percentage of the total mass of the sintering material, and its value range is 1%-15%, preferably 2%-10%, and more preferably 3%-8%; the minimum ignition temperature under the target working condition is calculated according to (Formula 4); combining (Formula 3) and (Formula 4), first calculate the mass of small-particle biomass required for the optimal energy consumption conditions for sintering ignition at the ignition temperature, and then obtain the mass distribution ratio of large-particle biomass and the mass distribution ratio of small-particle biomass, and finally calculate the mass distribution ratio of medium-particle biomass on the premise of satisfying the mass distribution ratio of large-particle biomass and the mass distribution ratio of small-particle biomass.

13. A low carbon sintering system or a sintering system used for the low carbon sintering method according to any one of claims 1 to 8, characterized in that: The sintering system comprises a sintering machine (1), a batching device (2), a material distribution device (3), an ignition burner (4), a crushing device (5), a screening device (6), a gasification device (7), a ring cooler (8), and a blowing device (9); wherein, according to the running direction of the sintering machine (1), the sintering machine (1) is divided into a drying section (101), a preheating section (102), and a roasting section (103) in sequence; the ignition burner (4) is arranged in an ignition furnace located above the downstream side of the preheating section (102); the material outlet of the batching device (2) is connected to the material inlet of the material distribution device (3); the material outlet of the material distribution device (3) is arranged at the feed end of the sintering machine (1); the blowing device (9) is arranged above the roasting section (103); the discharge end of the sintering machine (1) is connected to the feed end of the ring cooler (8); The material outlet of the crushing device (5) is connected to the material inlet of the screening device (6); the large particle material outlet of the screening device (6) is connected to the material inlet of the distribution device (3); the medium particle material outlet of the screening device (6) is connected to the material inlet of the gasification device (7); the small particle material outlet of the screening device (6) is connected to the material inlet of the ignition burner (4); the gas outlet of the gasification device (7) is connected to the fuel inlet of the injection device (9).

14. The system according to claim 13, characterized in that: The screening device (6) is also provided with an outlet for materials on the screen, and the outlet for materials on the screen is connected to the material inlet of the crushing device (5); Preferably, the system further comprises a forming device (10), the solid outlet of the gasification device (7) is connected to the material inlet of the forming device (10), and the material outlet of the forming device (10) is connected to the material inlet of the batching device (2); Preferably, the gas inlet of the drying section (101) is connected to the high-temperature gas outlet of the ring cooler (8) or to the low-temperature medium outlet of the gasification device (7) through a pipeline.

15. The system according to claim 13 or 14, characterized in that: The ignition burner (4) comprises a combustion-supporting air duct (401) and a biomass duct (402); the air inlet end of the combustion-supporting air duct (401) is connected to an oxygen-containing gas source, and the air outlet end of the combustion-supporting air duct (401) is connected to the furnace of the ignition furnace; the feed end of the biomass duct (402) is simultaneously connected to the fine particle material outlet of the screening device (6) and the carrier gas source, and the discharge end of the biomass duct (402) is connected to the furnace of the ignition furnace; Preferably, the discharge section of the biomass pipeline (402) includes a gas discharge channel (4021) and a solid discharge channel (4022) sleeved outside the gas discharge channel (4021).

16. The system according to claim 15, characterized in that: The combustion-supporting air duct (401) comprises a central air duct (4011) and a secondary air duct (4012) which are not connected to each other; the air inlet ends of the central air duct (4011) and the secondary air duct (4012) are both connected to an oxygen-containing gas source; the central air duct (4011) is sleeved in the tube cavity of the gas discharge channel (4021) along the axis of the gas discharge channel (4021), and the secondary air duct (4012) is sleeved on the outside of the solid discharge channel (4022); the air outlet ends of the central air duct (4011) and the secondary air duct (4012) are both connected to the furnace of the ignition furnace; Preferably, the ignition burner (4) further comprises a swirl mechanism (403), and the swirl mechanism (403) is arranged at the gas outlet end of the secondary air duct (4012) and / or the gas outlet channel (4021); preferably, the swirl mechanism (403) is a swirl blade; Preferably, the carrier gas source is the gas outlet of the drying section (101).

17. The system according to any one of claims 13 to 16, characterized in that: The gasification device (7) comprises a kiln body (701) and a heat exchange device (702) extending into the kiln body (701) and not connected to the kiln body (701); wherein the kiln body (701) comprises a kiln head (7011), a kiln body (7012) and a kiln tail (7013) connected in series in sequence; the kiln head (7011) and the kiln tail (7013) are fixedly arranged, and the kiln body (7012) can rotate along its axis; a gas-solid inlet (7014) is provided at the upper part of the kiln head (7011), and the gas-solid inlet (7014) is simultaneously connected to the kiln head (7011) and the kiln tail (7013) through a pipeline. The medium particle material outlet of the screening device (6) is connected to a high-humidity oxygen-containing gas source; a gas outlet (7015) is provided at the upper part of the kiln tail (7013), and the gas outlet (7015) is connected to the fuel inlet of the blowing device (9) through a pipeline; a solid outlet (7016) is provided at the lower part of the kiln tail (7013), and the solid outlet (7016) is connected to the material inlet of the forming device (10) or the material inlet of the batching device (2) through a conveyor belt; preferably, the high-humidity oxygen-containing gas source is the gas outlet of the drying section (101).

18. The system according to any one of claims 13 to 17, characterized in that: The heat exchange device (702) comprises an outer cylinder (7023) and an inner cylinder (7024); the outer cylinder (7023) passes through the kiln head (7011), the kiln body (7012) and the kiln tail (7013) in sequence along the axial direction; an inner cylinder (7024) is inserted into each of the two ends of the outer cylinder (7023); and the insertion ends of the inner cylinder (7024) extend along the axis of the outer cylinder (7023) to the middle of the cylinder cavity of the inner cylinder (7024); high-temperature medium inlets (7021) are provided at both ends of the outer cylinder (7023) located outside the kiln body (701); and a high-temperature medium inlet (7021) is provided at the end of the inner cylinder (7024) located inside the outer cylinder (7023). A medium return port (7025) is provided on each of the inner cylinders (7024), and the inner cylinder (7024) is connected to the outer cylinder (7023) via the medium return port (7025); a low-temperature medium outlet (7022) is provided on the inner cylinder (7024) located outside the outer cylinder (7023); preferably, the high-temperature medium inlet (7021) is connected to the sintering flue; preferably, a blind plate (7026) is further provided in the middle of the cylinder cavity of the outer cylinder (7023), and the cylinder cavity of the outer cylinder (7023) is divided into two sections of the tube cavity that are not connected to each other by the blind plate (7026), and the two inner cylinders (7024) are respectively located in the two sections of the tube cavity that are not connected to each other.

19. The system according to any one of claims 13 to 18, characterized in that: According to the arrangement of 1 to 8 evenly distributed heat exchange devices (702) inside the kiln body (701), preferably, the gasification device (7) further comprises a water supply pipe (7027), the water inlet end of the water supply pipe (7027) is connected to a new water source, the water outlet end of the water supply pipe (7027) passes through the kiln head (7011) and then extends to the inside of the kiln body (7012), and a plurality of atomizing nozzles (7028) are arranged on the water outlet pipe section of the water supply pipe (7027).

20. The system according to any one of claims 13 to 19, characterized in that: The kiln body (701) is tilted with the kiln head (7011) being higher and the kiln tail (7013) being lower; preferably, the inclination angle of the kiln body (701) is 2 to 8°, preferably 3 to 6°.

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