Method for preparing blast furnace injection fuel by using furfural residues

Abstract

The invention relates to a method for preparing blast furnace injection fuel by using furfural residue, which comprises the steps of furfural residue crushing and washing, furfural residue secondary washing, furfural residue tertiary washing, furfural residue drying, washing wastewater treatment and the like, and specifically sets the specific washing mode, washing liquid source, ratio and the like in each washing process. The method realizes the effect of efficiently reducing the contents of alkali metal elements and sulfate radicals for the specific material furfural residue, so that the specific material furfural residue can meet the technical requirements of blast furnace injection fuel after being subjected to specific treatment steps, and the effect of turning harm into benefit is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of waste slag recycling, and particularly relates to a method for preparing blast furnace injection fuel by using furfural slag. Background Art

[0002] Furfural residue is currently mainly used as fuel for steam boilers in furfural plants, accounting for 1 / 2 to 2 / 3 of the furfural residue produced, and the rest is used for biomass power generation or preparation of organic fertilizer. However, furfural residue has a high moisture content, and the efficiency of direct combustion power generation is low. In addition, furfural residue contains a large amount of sulfate, which will aggravate soil compaction when used as fertilizer. Therefore, a more efficient and environmentally friendly treatment process is needed.

[0003] As the industry with the largest CO2 emissions in the manufacturing industry, the steel industry faces severe challenges in green and low-carbon transformation. CO2 emissions from blast furnace ironmaking processes account for more than 70% of the entire steel production process, of which the fuel consumed by blast furnace tuyere injection accounts for about 1 / 3 of the comprehensive energy consumption of the blast furnace. When blast furnace tuyere injection is performed, the injection fuel is required to have high calorific value, good combustibility, low ash content and low harmful element content. The current injection fuel mainly uses anthracite, bituminous coal, heavy oil or natural gas. Compared with traditional fossil fuels, biomass energy (waste wood, straw, etc.) has the characteristics of wide distribution and large output. More importantly, biomass energy is a renewable carbon-neutral energy source. It releases less sulfides and nitrides during use, and has obvious environmental advantages and social benefits. If biomass fuel can be used instead of injection coal to reduce the coal consumption of blast furnace tuyere injection, it will be of great significance to the green transformation of the steel industry. However, due to its high moisture content, low energy density and low crushing efficiency, biomass cannot be directly used for blast furnace tuyere injection. Conventional biomass pyrolysis technology solves the above problems, but biomass pyrolysis technology has the characteristics of high energy consumption and heavy pollution. In addition, the ash and harmful elements such as sodium and potassium in the biomass are enriched in the biomass pyrolysis carbon, which limits the application of biomass pyrolysis carbon in blast furnace injection.

[0004] China's invention patent publication CN116694836A discloses a method for injecting biomass fuel into a blast furnace, in which a mixed fuel obtained by replacing part of fossil fuel with biomass shaped fuel that has not been carbonized at high temperature is injected into the blast furnace, reducing carbon emissions and SO2 pollution. However, the problem of biomass being difficult to crush and having a high alkali metal content is not solved, and the added water glass binder will decompose Na2O at high temperature, which will further increase the alkali load of the blast furnace and affect the normal production of the blast furnace.

[0005] Furfural slag is the residue of most cellulose and lignin components in biomass raw materials, which contains rich biomass energy. However, the inorganic salts in the biomass and the sulfate added in the furfural production process will be enriched in the furfural slag, resulting in high alkali metal and sulfur content in the furfural slag, which cannot be directly used in steel production. But at the same time, in the furfural production process, the original organizational structure of the biomass is destroyed, which is beneficial to the removal of harmful substances. The application of furfural slag as blast furnace injection fuel has both certain unfavorable factors and certain favorable factors. If the furfural slag can be used for blast furnace injection after simple treatment, it can not only reduce the coal consumption and CO2 emissions of the steel industry, but also increase the added value of the furfural production process, achieving a "win-win" situation of economic and social benefits. Summary of the invention

[0006] In view of the current technical problems of high alkali metal content, high sulfur content and difficulty in comprehensive utilization of furfural slag, the present invention uses waste liquid from the bottom of a distillation tower in furfural production to wash and remove impurities from the furfural slag, thereby reducing the content of harmful components in the furfural slag without increasing the generation of waste liquid, so that the content of harmful components in the furfural slag can meet the needs of blast furnace production, and proposes a method for preparing blast furnace injection fuel using furfural slag.

[0007] This is achieved through the following technical means:

[0008] A method for preparing blast furnace injection fuel using furfural slag comprises the following steps:

[0009] (1) Crushing and washing of crude furfural residue: The crude furfural residue is mixed with the first washing liquid (after the third filtrate is obtained after startup, the third filtrate is directly used to replace it) to form a mixed slurry, and then the mixed slurry is added to a crushing grinder for crushing to obtain a small-particle wet furfural residue slurry, and then solid-liquid separation is performed to obtain small-particle furfural residue and the first filtrate.

[0010] (2) Furfural slag secondary washing: The small-size furfural slag obtained in step (1) is washed in the first washing tank using the second washing liquid to obtain a washing slurry, and then the washing slurry is subjected to solid-liquid separation to obtain secondary washed furfural slag and a second filtrate. The alkali metal and sulfate content in the furfural slag is reduced to the standard of blast furnace injection fuel.

[0011] (3) Furfural residue washed three times: the furfural residue washed twice obtained in step (2) is placed in a second washing tank with washing water for mixed washing, and then the slurry in the second washing tank is subjected to solid-liquid separation to obtain a third filtrate and the furfural residue washed three times, wherein the third filtrate is returned to step (1) to replace the first washing liquid in step (1) for recycling.

[0012] (4) Drying the furfural slag: Drying the washed furfural slag obtained in step (3) to obtain a refined furfural slag product that can be used as a blast furnace injection fuel.

[0013] (5) Treatment of washing wastewater: The first filtrate obtained in step (1) and the second filtrate obtained in step (2) are treated so that the treated filtrate meets the water inlet standard of the wastewater evaporator.

[0014] Preferably, in step (1), the moisture content of the small-particle-size wet furfural residue slurry is 60-80 wt.%, the average particle size of the small-particle-size furfural residue is 0.5-3 mm, and the maximum particle size is less than 3 mm;

[0015] Preferably, in step (1), the mass ratio of the crude furfural residue to the first washing liquid is (0.8-1.2):(0.9-1.3), and the mass ratio of the furfural residue to the returned third filtrate is (0.8-1.2):(0.9-1.3).

[0016] Preferably, the first washing liquid in step (1) and the second washing liquid in step (2) are one or a mixture of the bottom waste liquid or tap water.

[0017] Preferably, in step (2), the small-particle furfural residue obtained in step (1) is washed with the second washing liquid for 1 to 2 times to ensure the removal effect of harmful components in the furfural residue. A washing slurry is obtained, and then the washing slurry is subjected to solid-liquid separation, and the washing process is carried out in a container with a stirrer, the mass ratio of the small-particle furfural residue to the second washing liquid is (0.9 to 1.1): (1 to 2.2), and the washing time is 20 to 40 minutes.

[0018] Preferably, in step (4), the drying is performed by using a rotary kiln to dry the tertiary washed furfural residue, and the drying medium is boiler flue gas or superheated steam.

[0019] Preferably, in step (5), the first filtrate obtained in step (1) and the second filtrate obtained in step (2) are treated, specifically:

[0020] I. Mix the first filtrate obtained in step (1) and the second filtrate obtained in step (2) to obtain a mixed filtrate.

[0021] II, a water softener is filled with a cation exchange resin (to remove inorganic ions in the filtrate to reduce the adverse effects on the wastewater evaporator), the mixed filtrate obtained in step I is discharged into the water softener, the calcium ions and magnesium ions in the mixed filtrate are removed, and a treated cold filtrate is obtained.

[0022] III, discharging hot bottom waste liquid at 82-98° C. into the heat exchanger through the heat exchange medium inlet, discharging the treated cold filtrate obtained in step II into the heat exchanger, and performing intermittent heat exchange with the bottom waste liquid to obtain a treated hot filtrate with a temperature of 50-60° C., the hot filtrate is used in the dilution link of furfural production of sulfuric acid, and at the same time, the cold bottom waste liquid obtained after cooling is discharged through the heat exchange medium outlet, and the discharged cold bottom waste liquid is discharged into step (1) as the first washing liquid and / or into step (2) as the second washing liquid, wherein the hot bottom waste liquid is the hot bottom waste liquid at the bottom of the distillation tower of the furfural production process.

[0023] Preferably, in step (3), the mass ratio of the secondary washing furfural residue to the washing water is (0.8-1.3):(0.9-1.1); the washing water is tap water or recycled water; and the mixing is specifically stirring in the second washing tank for 15-45 minutes.

[0024] Preferably, the chemical composition of the crude furfural slag includes C: 39.12-55.63wt.%, H: 3.9-6.2wt.%, O: 33.1-41.2wt.%, N: 0.1-0.9wt.%, S: 0.5-1wt.%, and the remainder is inevitable impurities; and the industrial components of the crude furfural slag are moisture: 42.2-49.3wt.%, volatile matter: 32-41wt.%, fixed carbon: 9.98-14.35wt.%, and ash: 2.93-5.89wt.%; and the mass percentage content of K2O in the components of the crude furfural slag is 1.3-1.9wt.%, and the calorific value of the crude furfural slag is 18.21-23.68MJ / kg.

[0025] Preferably, the pH value of the hot tower bottom waste liquid is 2.9-3.9, the solid content is 95.11-112.08 mg / L, the COD is 14000-15000 mg / L, the BOD5 is 11000-12000 mg / L, and the K + 0.2~0.3mg / L, Mg 2+ 0.1~0.3mg / L, Ca 2+ 1.25~1.88mg / L, SO4 2- It is 18.85~23.05mg / L.

[0026] Preferably, the chemical composition of the refined furfural slag obtained in step (4) comprises C: 49.38-58.12wt.%, H: 3.98-6.36wt.%, O: 32.8-40.5wt.%, N: 0.1-0.9wt.%, S: 0.1-0.6wt.%, and the remainder is inevitable impurities; and the industrial components of the crude furfural slag are moisture: 45.1-51.9wt.%, volatile matter: 30.08-39.56wt.%, fixed carbon: 13.69-18.02wt.%, and ash: 1.05-3.06wt.%; and the mass percentage content of K2O in the components of the crude furfural slag is 0.1-0.3wt.%, and the calorific value of the crude furfural slag is 20.31-25.32MJ / kg.

[0027] A device for preparing blast furnace injection fuel using furfural slag, the device is used to carry out the above-mentioned method for preparing blast furnace injection fuel using furfural slag, the device comprises a furfural slag crushing and washing component, a furfural slag secondary washing component, a furfural slag tertiary washing component, a furfural slag drying component and a washing wastewater treatment component.

[0028] The furfural residue crushing and washing components include a crushing grinder and a first plate and frame filter press.

[0029] The furfural residue secondary washing components include a first washing tank and a second plate-frame filter press.

[0030] The furfural residue tertiary washing components include a second washing tank and a third plate and frame filter press.

[0031] The furfural residue drying component comprises a dryer.

[0032] The washing wastewater treatment component includes a water softener and a heat exchanger.

[0033] Preferably, the crushing and grinding machine comprises a furfural residue inlet, a wet furfural residue slurry outlet and a first washing liquid inlet; the furfural residue inlet is used to discharge the crude furfural residue produced in the furfural production process into the crushing and grinding machine.

[0034] The first plate-frame filter press comprises a wet furfural residue slurry inlet, a small-size furfural residue outlet and a first filtrate outlet; the wet furfural residue slurry inlet is connected to the wet furfural residue slurry outlet of the crushing and grinding machine.

[0035] The first washing tank comprises an inlet for small-particle furfural residue, an inlet for a second washing liquid and an outlet for washing slurry; the inlet for small-particle furfural residue is connected to the outlet for small-particle furfural residue of the first plate and frame filter press.

[0036] The second plate-frame filter press comprises a washing slurry inlet, a secondary washing furfural residue outlet and a second filtrate outlet; the washing slurry inlet is connected to the washing slurry outlet of the first washing tank.

[0037] The second washing tank includes a secondary washing furfural residue inlet, a washing water inlet and a tertiary washing slurry outlet; the secondary washing furfural residue inlet is connected to the secondary washing furfural residue outlet of the second plate and frame filter press, and the washing water inlet is used to discharge fresh washing water into the second washing tank.

[0038] The third plate and frame filter press includes a tertiary washing slurry inlet, a tertiary washing furfural residue outlet and a third filtrate outlet; the tertiary washing slurry inlet is connected to the tertiary washing slurry outlet of the second washing tank, and the third filtrate outlet is connected to the first washing liquid inlet of the crushing and grinding machine.

[0039] The dryer includes a thrice-washed furfural residue inlet and a refined furfural residue outlet; the thrice-washed furfural residue inlet is connected to the thrice-washed furfural residue outlet of the third plate and frame filter press, and the refined furfural residue outlet is used to discharge the refined furfural residue finished product for blast furnace injection fuel.

[0040] The water softener comprises a filtrate inlet and a softened liquid outlet, and the water softener is filled with a cation exchange resin. The filtrate inlet is respectively connected to the first filtrate outlet of the first plate-frame filter press and the second filtrate outlet of the second plate-frame filter press.

[0041] The heat exchanger includes a heat exchange medium inlet, a softening liquid inlet, a heat exchange medium outlet and a hot filtrate outlet; the heat medium inlet is used to discharge the hot bottom waste liquid at the bottom of the distillation tower of the furfural production process into the heat exchanger, the softening liquid inlet is connected to the softening liquid outlet of the water softener, the heat exchange medium outlet is connected to the second washing liquid inlet of the first washing tank, and the hot filtrate outlet is used to discharge the treated hot filtrate obtained after heat exchange, and is used in the subsequent dilution link of furfural production of sulfuric acid.

[0042] Preferably, the crushing and grinding machine is a ball mill.

[0043] Preferably, the first washing tank and the second washing tank are both tank containers with agitators.

[0044] Preferably, the dryer is a rotary kiln.

[0045] The technical effects of the present invention are:

[0046] (1) The present invention uses specific steps and parameters to transform the specific material furfural slag for preparing blast furnace injection fuel. First, the crude furfural slag is crushed by washing, and the crude furfural slag is crushed into small particles of a specific range in the presence of liquid, thereby increasing the contact area between the furfural slag material and the washing liquid, thereby accelerating the transfer rate of inorganic salts from the furfural slag to the washing liquid, thereby improving the washing efficiency, greatly enhancing the washing effect, and there is no dust pollution during the crushing process. The specific method of washing the specific material after washing and crushing effectively reduces the content of alkali metal elements and sulfate in the furfural slag, so that it can meet the standards of blast furnace injection fuel.

[0047] (2) The present invention returns the third filtrate to the washing and crushing process, returns the cold tower bottom waste liquid to the first washing tank, and only adds fresh washing water inside and outside the second washing tank. The other processes all use specific and recycled waste liquids, and are applied to specific processes according to the characteristics of the specific waste liquids, thereby reducing the amount of washing water used. Moreover, the waste liquids (the first filtrate and the second filtrate) after washing are returned to the furfural production process after treatment, thereby achieving that no additional wastewater discharge is basically added during the refining process. Since the direct use of the hot tower bottom waste liquid will cause the washing temperature to be too high, the heat of the hot tower bottom waste liquid is transferred back to the softened waste liquid of the furfural production process through reasonable settings, thereby making reasonable use of the heat and also turning harm into benefit. The filtrate after washing is treated with a cation exchange resin to avoid the adverse effects of the washing process on the wastewater evaporator. Through the overall setting of the waste liquid, both the waste liquid and the heat are reasonably utilized, without causing any subsequent environmental burden, and at the same time, the washing effect is enhanced.

[0048] (3) Different washing liquids and washing waters are added and reused in each process. By setting the ratio of furfural residue material to washing liquid or washing water, and combining the specific particle size of furfural residue, the effect of the specific washing liquid and washing water on the washing of furfural residue is enhanced through the coordinated relationship between the material ratio and the material particle size. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The process flow diagram of the method of the present invention is shown in FIG.

[0050] In the figure: 1-crushing grinder; 2-1st plate and frame filter press; 3-1st washing tank; 4-2nd plate and frame filter press; 5-2nd washing tank; 6-3rd plate and frame filter press; 7-dryer; 8-water softener; 9-heat exchanger; A-crude furfural residue; B-refined furfural residue; C-3rd filtrate; D-cold bottom waste liquid; E-washing water; F-1st filtrate; G-2nd filtrate; H-treated cold filtrate, I-treated hot filtrate, J-hot bottom waste liquid. DETAILED DESCRIPTION

[0051] The process technology scheme of the present invention is further illustrated below by combining embodiments and drawings. The orientations involved in this specification are based on the orientations of the present invention during normal operation, and do not limit the orientations during storage and transportation. They only represent relative positional relationships, not absolute positional relationships. Specific implementation methods Unless otherwise described, each feature is only an example of a series of equivalent or similar features. Just to help understand the present invention, those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] Example 1

[0053] like Figure 1 As shown, Figure 1 It is both a schematic diagram of the connection of the device of the present invention and a schematic diagram of the process flow of the method. Figure 1 The connection mode of the device in the embodiment is carried out in a furfural plant in Hebei. The average particle size of the crude furfural slag is about 3 mm, and the physical and chemical properties are shown in Table 1, which shows the physical and chemical properties of the furfural slag raw material (crude furfural slag).

[0054] Table 1

[0055]

[0056] As shown in Table 1, the furfural slag raw material has a high calorific value, but the K and S elements are high in content, and is not suitable for blast furnace injection. At the same time, the temperature of the bottom waste liquid of the distillation tower is about 90°C, and it can be used for furfural slag washing only after cooling. The physical and chemical properties of the bottom waste liquid are shown in Table 2. Table 2 shows the physical and chemical properties of the bottom waste liquid.

[0057] Table 2

[0058]

[0059] In furfural production, corncobs, etc. are mixed with concentrated sulfuric acid and then steam is passed to increase the temperature and pressurize. The furfural and byproduct acetic acid produced can be discharged with steam in a gaseous form, and crude aldehyde is obtained by cooling. Then, the distillation tower is distilled, and furfural becomes steam and discharged. After cooling and refining, furfural products are obtained. The components that the distillation tower does not evaporate, mainly acetic acid and water, will be left at the bottom of the tower to form a waste liquid at the bottom of the tower (i.e., the main components of the waste liquid at the bottom of the tower are water and acetic acid). After hydrolysis is completed, the unreacted corncobs, etc. remaining in the hydrolysis tank, and sulfate (sulfuric acid will not evaporate under the hydrolysis condition) have become furfural slag. Therefore, the essence of the waste liquid at the bottom of the tower is condensate, and there is basically no inorganic salt ion (extremely low content) therein. It can be seen from Table 2 and actual conditions that the inorganic salt ion content is extremely low in the waste liquid at the bottom of the tower (for example, sulfate ion only has 20.53mg / L), indicating that it can be used as the furfural washing of the present embodiment.

[0060] After the raw materials are determined, proceed as follows:

[0061] (1) The crude furfural residue (wet basis) is first mixed with the third filtrate of the same mass (the bottom waste liquid is used as the first washing liquid at the start-up) to form a slurry, and then added to the ball mill to crush the furfural residue into small particles of ≤2 mm (maximum particle size is less than or equal to 2 mm), and fully mixed with the third filtrate to complete the first washing. The crushed slurry enters the first plate and frame filter press for solid-liquid separation to obtain the first filtrate and the first washed furfural residue (i.e., small-particle furfural residue).

[0062] (2) The first washed furfural residue enters the first washing tank, is mixed with twice the mass of the cold tower bottom waste liquid produced in step (5) and stirred for 30 minutes, and then enters the second plate and frame filter press for solid-liquid separation to obtain the second filtrate and the second washed furfural residue.

[0063] (3) The second washed furfural residue then enters the second washing tank, is mixed with tap water of equal mass and stirred for 30 min, and then enters the third plate and frame filter press for solid-liquid separation to obtain the third filtrate and the thrice washed furfural residue.

[0064] (4) After the furfural residue is washed three times, it is dried in a rotary kiln to obtain a refined furfural residue product. The physical and chemical analysis is shown in Table 3.

[0065] (5) The third filtrate obtained by solid-liquid separation is recycled to the furfural residue crushing unit. The first filtrate and the second filtrate are mixed and first enter the water softener for ion exchange. The water softener is equipped with cation exchange resin, which can remove Ca in the filtrate. 2+ and Mg 2 + The filtrate after ion exchange treatment is then heat exchanged with the bottom waste liquid at about 90°C through a heat exchanger, and after heating to about 50-60°C, it enters the wastewater evaporator of the furfural production process. The cold bottom waste liquid cooled after heat exchange is discharged into step (2) for use as the second washing liquid. The cationic resin in the water softener is regenerated using NaCl solution, and the regenerated wastewater is used in the sulfuric acid dilution link of furfural production.

[0066] Table 3 shows the physical and chemical properties of the refined furfural slag product obtained in Example 1.

[0067] Table 3

[0068]

[0069] It can be seen from Table 3 that the refined furfural slag product reaches the level of low-basicity coal (alkali metal content ≤ 0.3%), which can meet the needs of blast furnace injection.

[0070] In other embodiments, the average particle size of the small-particle furfural residue in step (1) is, for example, 0.8, 1.0, 1.5, 2.1, 2.5 mm, etc., and the maximum particle size is less than 1.0, 1.2, 1.8, 2.2, 2.8 mm, etc., respectively, and the mass ratio of the crude furfural residue to the first washing liquid (including the replaced third filtrate) is, for example, (0.9:1.1), (1:0.95), (1:1.2), (1:1.3), (1.1:1.3), etc.

[0071] In other embodiments, in step (2), the mass ratio of the first washing liquid to the second washing liquid is, for example, (0.9:1.5), (1:1.95), (1:2.1), (1.05:2.15), (1.1:2), etc., and the washing time is, for example, 22, 25, 28, 31, 33, 35, 39 min, etc.

[0072] In other embodiments, in step (3), the mass ratio of the secondary washed furfural residue to the washing water is, for example, (0.985:1.1), (0.9:0.95), (1:1.05), (1.1:1), (1.2:1.05), etc.; the mixing in the second washing tank is specifically stirring, and the stirring time is, for example, 18, 23, 29, 33, 38, 42 minutes, etc.

[0073] Comparative Example 1

[0074] This comparative example is a comparative test with an increased washing liquid ratio, except that the mass of the bottom waste liquid added to the first washing tank is 4 times the mass of the furfural residue, and the other settings are the same as those in Example 1. The physicochemical analysis of the refined furfural residue obtained under this working condition is shown in Table 4. Table 4 shows the physicochemical properties of the refined furfural residue of Comparative Example 1.

[0075] Table 4

[0076]

[0077] By comparing Table 3 and Table 4, it can be concluded that increasing the mass of the washing liquid does not have a significant effect on the physical and chemical properties of the refined furfural slag. In the usual furfural production, 16-17t of furfural slag (wet basis) and about 20t of bottom waste liquid are produced for every 1t of furfural produced, and 7-8t of tap water are consumed. Since the boiler needs to consume 50% to 60% of the furfural slag in the production of furfural, the ratio of the mass of the furfural slag that can be used for refining to the bottom waste liquid and tap water is basically 1:2:1, that is, the ratio in Example 1 can basically ensure the material balance of the entire system. If a higher proportion of bottom waste liquid is used for furfural slag refining, the quality of the product will not be greatly improved, and the processing amount of furfural slag will be less, which is not conducive to the full utilization of furfural slag. That is, the material ratio relationship set by the present invention is the optimal setting. Too little can not meet the requirements of complete treatment. Too much will not only not improve the effect, but also bring adverse effects.

[0078] Comparative Example 2

[0079] This comparative example is a comparative test without crushing the furfural residue, except that the furfural residue is not crushed, but directly mixed with the third filtrate in the washing tank and stirred for 30 minutes (i.e., no ball mill is used for crushing and grinding), and the other settings are the same as those in Example 1. The physical and chemical analysis of the refined furfural residue obtained under this working condition is shown in Table 5. Table 5 shows the physical and chemical properties of the refined furfural residue of Comparative Example 2.

[0080] Table 5

[0081]

[0082] It can be concluded from Table 5 that the moisture content in the finished furfural slag is high and the K2O content is too high. This is because the furfural slag itself has large particles (about 30 mm), the plate and frame filter press has poor dehydration effect, and the refined furfural slag obtained has a high moisture content, which will increase the energy consumption of the drying unit. At the same time, the larger particles affect the diffusion of harmful substances into the water phase, making the removal effect of harmful substances poor under the same working conditions. That is, the crushing link and the crushing particle size setting set by the present invention are not just a simple enhanced process, but are closely coordinated with the subsequent washing and filter press solid-liquid separation. The crushing and grinding particle size range set by the present invention can ensure the appropriate amount of moisture in the product while ensuring the effect of harmful substances diffusing into the water phase, that is, the crushing and particle size limitation are not routinely performed with the specific settings of the subsequent steps but are closely coordinated.

[0083] Comparative Example 3

[0084] This comparative example is a comparative test in which only one washing and dehydration is performed. The difference is that before crushing, the crude furfural residue (wet basis) is mixed with 2 times the mass of the tower bottom waste liquid and the same mass of tap water into a slurry and then enters the ball mill for crushing and solid-liquid separation (i.e., no subsequent secondary or tertiary washing is performed), the solid product is directly dried, and the filtrate enters the water softener for treatment. The other settings are the same as those in Example 1. The physical and chemical analysis of the refined furfural residue obtained under this working condition is shown in Table 6. Table 6 shows the physical and chemical properties of the refined furfural residue of Comparative Example 3.

[0085] Table 6

[0086]

[0087] It can be concluded from Table 6 that, although the quality of the waste liquid at the bottom of the tower and the tap water used for washing is the same as that of Example 1, the harmful substance removal effect of a single washing is far inferior to that of multiple washings, and the K2O content in the product is relatively high, which limits its use in steel production. Since the amount of the washing liquid (or washing water) in this comparative example is the same as that of Example 1 as a whole, the difference in the washing effect is very large, that is, the multiple washings set in the present invention are not simply for strengthening the effect, but are achieved by setting multiple specific washing methods to reduce the K2O content to a content that meets the requirements.

[0088] Comparative Example 4

[0089] This comparative example is a comparative test in which the filtrate after washing is not treated. The difference is that the first filtrate and the second filtrate are mixed without using a water softener for treatment, and directly enter the wastewater evaporator after heat exchange. The other settings are the same as those in Example 1. The untreated washing filtrate (tower bottom waste liquid) was tested, and its physical and chemical properties are shown in Table 7. Table 7 shows the physical and chemical properties of the tower bottom waste liquid of Comparative Example 4.

[0090] Table 7

[0091]

[0092] In normal furfural production, the scaling of the wastewater evaporator is caused by the high-temperature polycondensation of organic matter (mainly acetic acid), which can be removed by soaking in an alkaline solution, and the cleaning cycle is about 7 to 10 days. In Example 1, the scaling of the wastewater evaporator is not much different from that of conventional production, but in Comparative Example 4, the heat exchange efficiency of the wastewater evaporator drops rapidly, the scaling rate accelerates, and the effect of soaking in an alkaline solution to change the tubes is still poor. By analyzing the scale on the heat exchange tubes, it is found that in addition to the soft scale formed by common organic matter, there is also yellow-white hard scale generated. After analysis, its main component is CaSO4. It can be concluded from Table 7 that during the washing process, a large amount of Ca 2+ and SO4 2-Entered the liquid phase. The solubility of CaSO4 at 100°C is only 169mg / L. If the filtrate is not treated and directly enters the wastewater evaporator, as the temperature rises and the filtrate is concentrated, CaSO4 crystals will precipitate quickly, causing scaling of the wastewater evaporator and affecting the normal production of furfural. That is, the overall setting of each step of the present invention not only achieves excellent standards for the use of the refined furfural slag as blast furnace injection fuel, but also has no adverse consequences on the overall process of furfural production. Changing a part of the setting method will cause adverse consequences to the overall process of furfural production.

[0093] The technical principles and examples of the present invention are described above in conjunction with specific embodiments. The above embodiments and comparative examples of the present invention are all examples and do not have a limiting effect on the protection scope of the technical solution. The technical effects that are not compared can be clearly described through the textual description of the technical effects, and do not mean that the invention is low in height. These descriptions are only for explaining the principles and examples of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can think of other specific implementations of the present invention without creative labor, and these methods will fall within the protection scope of the present invention.

Claims

1. A method for preparing blast furnace injection fuel using furfural slag, characterized in that: The steps include: (1) crushing and washing the crude furfural residue: mixing the crude furfural residue with a first washing liquid to form a mixed slurry, then adding the mixed slurry into a crushing and grinding machine for crushing to obtain a wet furfural residue slurry with a small particle size, and then performing solid-liquid separation to obtain a small particle size furfural residue and a first filtrate; (2) secondary washing of furfural residue: washing the small-particle furfural residue obtained in step (1) in a first washing tank with a second washing liquid to obtain a washing slurry, and then performing solid-liquid separation on the washing slurry to obtain secondary washed furfural residue and a second filtrate; (3) washing the furfural residue three times: placing the twice washed furfural residue obtained in step (2) and washing water into a second washing tank for mixed washing, then subjecting the slurry in the second washing tank to solid-liquid separation to obtain a third filtrate and the three-washed furfural residue, wherein the third filtrate is returned to step (1) to replace the first washing liquid in step (1) for recycling; (4) drying the furfural slag: drying the washed three-times-washed furfural slag obtained in step (3) to obtain a refined furfural slag product that can be used for blast furnace injection fuel; (5) Treatment of washing wastewater: The first filtrate obtained in step (1) and the second filtrate obtained in step (2) are treated so that the treated filtrate meets the water inlet standard of the wastewater evaporator.

2. The method for preparing blast furnace injection fuel using furfural slag according to claim 1, characterized in that: In step (1), the moisture content of the small-particle-size wet furfural residue slurry is 60-80wt.%, the average particle size of the small-particle-size furfural residue is 0.5-3mm, and the maximum particle size is less than 3mm; In step (1), the mass ratio of the crude furfural residue to the first washing liquid is (0.8-1.2):(0.9-1.3), and the mass ratio of the furfural residue to the returned third filtrate is (0.8-1.2):(0.9-1.3).

3. The method for preparing blast furnace injection fuel using furfural slag according to claim 1, characterized in that: The first washing liquid in step (1) and the second washing liquid in step (2) are either the bottom waste liquid or tap water or a mixture of the two.

4. The method for preparing blast furnace injection fuel using furfural slag according to claim 1, characterized in that: In step (2), the small-particle furfural residue obtained in step (1) is washed with the second washing liquid for 1 to 2 times to obtain a washing slurry, and then the washing slurry is subjected to solid-liquid separation. The washing process is carried out in a container with a stirrer, and the mass ratio of the small-particle furfural residue to the second washing liquid is (0.9 to 1.1): (1 to 2.2), and the washing time is 20 to 40 minutes.

5. The method for preparing blast furnace injection fuel using furfural slag according to claim 1, characterized in that: In step (4), the drying is performed by using a rotary kiln to dry the tertiary washed furfural residue, and the drying medium is boiler flue gas or superheated steam.

6. The method for preparing blast furnace injection fuel using furfural slag according to claim 1, characterized in that: In step (5), the first filtrate obtained in step (1) and the second filtrate obtained in step (2) are treated, specifically: I, mixing the first filtrate obtained in step (1) and the second filtrate obtained in step (2) to obtain a mixed filtrate; II, a water softener is filled with a cation exchange resin, the mixed filtrate obtained in step I is discharged into the water softener, the calcium ions and magnesium ions in the mixed filtrate are removed, and a treated cold filtrate is obtained; III, discharging hot bottom waste liquid at 82-98° C. into the heat exchanger through the heat exchange medium inlet, discharging the treated cold filtrate obtained in step II into the heat exchanger, exchanging heat with the bottom waste liquid at intervals, and obtaining treated hot filtrate at a temperature of 50-60° C., the hot filtrate is used in the furfural production to generate secondary steam, and at the same time, the cold bottom waste liquid obtained after cooling is discharged through the heat exchange medium outlet, and the discharged cold bottom waste liquid is discharged into step (1) as the first washing liquid and / or into step (2) as the second washing liquid, wherein the hot bottom waste liquid is the hot bottom waste liquid at the bottom of the distillation tower of the furfural production process.

7. The method for preparing blast furnace injection fuel using furfural slag according to claim 1, characterized in that: In step (3), the mass ratio of the secondary washing furfural residue to the washing water is (0.8-1.3):(0.9-1.1); the washing water is tap water or recycled water; the mixing is specifically stirring in the second washing tank, and the stirring time is 15-45 minutes.

8. A device for preparing blast furnace injection fuel using furfural slag, characterized in that: The device is used for carrying out the method for preparing blast furnace injection fuel using furfural slag as claimed in any one of claims 1 to 7, and the device comprises a furfural slag crushing and washing component, a furfural slag secondary washing component, a furfural slag tertiary washing component, a furfural slag drying component and a washing wastewater treatment component; The furfural residue crushing and washing components include a crushing grinder and a first plate and frame filter press; The furfural residue secondary washing components include a first washing tank and a second plate-frame filter press; The furfural residue tertiary washing components include a second washing tank and a third plate-frame filter press; The furfural residue drying component comprises a dryer; The washing wastewater treatment component includes a water softener and a heat exchanger.

9. The device for preparing blast furnace injection fuel using furfural slag according to claim 8, characterized in that: The crushing and grinding machine comprises a furfural residue inlet, a wet furfural residue slurry outlet and a first washing liquid inlet; the furfural residue inlet is used to discharge the crude furfural residue generated in the furfural production process into the crushing and grinding machine; The first plate-frame filter press comprises a wet furfural residue slurry inlet, a small-size furfural residue outlet and a first filtrate outlet; the wet furfural residue slurry inlet is connected to the wet furfural residue slurry outlet of the crushing and grinding machine; The first washing tank comprises a small-particle-size furfural residue inlet, a second washing liquid inlet and a washing slurry outlet; the small-particle-size furfural residue inlet is connected to the small-particle-size furfural residue outlet of the first plate-frame filter press; The second plate-frame filter press comprises a washing slurry inlet, a secondary washing furfural residue outlet and a second filtrate outlet; the washing slurry inlet is connected to the washing slurry outlet of the first washing tank; The second washing tank includes a secondary washing furfural residue inlet, a washing water inlet and a tertiary washing slurry outlet; The secondary washing furfural residue inlet is connected to the secondary washing furfural residue outlet of the second plate and frame filter press, and the washing water inlet is used to discharge fresh washing water into the second washing tank; The third plate-frame filter press comprises a tertiary washing slurry inlet, a tertiary washing furfural residue outlet and a third filtrate outlet; the tertiary washing slurry inlet is connected to the tertiary washing slurry outlet of the second washing tank, and the third filtrate outlet is connected to the first washing liquid inlet of the crushing and grinding machine; The dryer comprises a tertiary washed furfural residue inlet and a refined furfural residue outlet; the tertiary washed furfural residue inlet is connected to the tertiary washed furfural residue outlet of the third plate and frame filter press, and the refined furfural residue outlet is used to discharge the refined furfural residue finished product for blast furnace injection fuel; The water softener comprises a filtrate inlet and a softened liquid outlet, the water softener is filled with a cation exchange resin, and the filtrate inlet is respectively connected to the first filtrate outlet of the first plate-frame filter press and the second filtrate outlet of the second plate-frame filter press; The heat exchanger includes a heat exchange medium inlet, a softening liquid inlet, a heat exchange medium outlet and a hot filtrate outlet; the heat medium inlet is used to discharge the hot bottom waste liquid at the bottom of the distillation tower of the furfural production process into the heat exchanger, the softening liquid inlet is connected to the softening liquid outlet of the water softener, the heat exchange medium outlet is connected to the second washing liquid inlet of the first washing tank, and the hot filtrate outlet is used to discharge the treated hot filtrate obtained after heat exchange, and is used in the subsequent dilution link of furfural production of sulfuric acid.

10. The device for preparing blast furnace injection fuel using furfural slag according to claim 8 or 9, characterized in that: The crushing and grinding machine is a ball mill; the first washing tank and the second washing tank are both tank containers with agitators; and the dryer is a rotary kiln.

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