Blast furnace mixed injection pulverized coal and coal blending method

Abstract

The invention discloses blast furnace mixed injection pulverized coal and a coal blending method, and belongs to the technical field of blast furnace injection pulverized coal. Brown coal, long flame coal and anthracite are creatively mixed, the novel blast furnace mixed injection pulverized coal is provided, the high volatile component of the brown coal and the high calorific value of the long flame coal are fully utilized through the accurate coal type proportion, meanwhile, the low volatile component characteristic of the anthracite is combined, and sufficient combustion of the mixed pulverized coal in the blast furnace injection process is achieved; meanwhile, the combustion process of the pulverized coal is stabilized due to the low volatile component characteristic of the anthracite, so that the safety of the ironmaking process is ensured; in addition, the invention further provides a coal blending method of the mixed pulverized coal, by means of the method, the combustion efficiency of the pulverized coal is remarkably improved, the safety and economical efficiency of the ironmaking process are improved, and a new solution is provided for efficient, safe, economical and environment-friendly pulverized coal injection of a blast furnace.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace pulverized coal injection, and in particular to a blast furnace mixed pulverized coal injection and a coal blending method. Background Art

[0002] At present, blast furnace injection is generally divided into three categories: bituminous coal injection, anthracite injection, and mixed injection of anthracite and bituminous coal. Bituminous coal is highly volatile and has a high risk of explosion, so it is rarely injected alone. For a long time, domestic blast furnace injection has been mainly based on the injection of anthracite. However, the combustion performance of anthracite is poor. Injecting a large amount of coal will lead to a decrease in the combustion rate of coal powder at the tuyere, and it is difficult to reduce the blast furnace fuel ratio. In order to improve the efficiency of coal injection, high-volatile bituminous coal is gradually used as injection coal, and mixed with anthracite in a certain proportion for injection to achieve better injection effect. Among my country's coal resources, lignite and low-metamorphic bituminous coal (long flame coal belongs to this category) occupy an important position. Among them, lignite accounts for about 13% of my country's coal reserves, and low-metamorphic bituminous coal accounts for about 42% of my country's coal reserves. However, due to its high volatility and high water content, it is easy to cause safety problems such as explosion and incomplete combustion during the injection process.

[0003] In order to make more effective use of various types of coal, some utilization schemes have been proposed in the prior art. Chinese patent CN201610640833.3 discloses "a blending component of coal for blast furnace injection", which innovatively proposes a mixed injection technology of anthracite and bituminous coal, aiming to achieve high calorific value while reducing costs and improving economic benefits. The scheme recommends using bituminous coal with a volatile content of 20%-26% and anthracite in a ratio of 30:70 to ensure high calorific value and reduced production costs. However, it only studies the ratio of bituminous coal at 22% and 30%, and does not analyze and discuss the mixing effect of more detailed ratios. In addition, the scheme ignores the potential explosion risk that may be caused by the mixing of anthracite and bituminous coal, which may bring safety difficulties to the operation of the blast furnace. Chinese patent CN201510137576.7 discloses "a blending method for blast furnace injection coal", which relaxes the particle size requirements of coal powder to solve the problem of strong explosiveness associated with its high volatile content. By increasing the content of coal powder with a particle size less than or equal to 100 mesh in low-rank coal to 38.05% to 93.74% by weight of coal powder, the patent successfully reduced the explosiveness of coal powder. However, this adjustment leads to an increase in coarser coal powder in the charge, affecting the injection effect and the stability of the temperature field in the vortex zone of the blast furnace tuyere, thereby affecting the stable and smooth production of the blast furnace. Chinese patent CN201611173433.2 discloses "a mixed pulverized coal injection", which includes coke oven dust, anthracite and bituminous coal, aiming to reduce explosiveness and increase combustion rate through this mixture. The weight ratio of coke oven dust, anthracite and bituminous coal in the patent is (5-20): (35-50): (38-45), and the return flame length of the mixed pulverized coal is less than 400mm, showing lower explosiveness, and the combustion rate is 2-3 percentage points higher than that of a single coal type. However, it only considers reducing the explosiveness, and does not study the impact of high ash content of coke oven dust on blast furnace operation. The addition of such high ash content material may increase the ash content in the blast furnace, adversely affecting the air permeability and operational stability of the blast furnace, and become a key limiting factor in the injection process.

[0004] Although the above patents have all made innovative combined applications of various types of coal to a certain extent, they all have certain limitations. In view of this, the present invention proposes a blast furnace mixed pulverized coal injection and coal blending method. Summary of the invention

[0005] The purpose of the present invention is to propose a blast furnace mixed pulverized coal injection and coal blending method to solve the problems raised in the background technology. The present invention prepares a new type of blast furnace mixed pulverized coal injection by rationally blending three types of coal: lignite, long flame coal and anthracite; through the complementary advantages of the above three types of coal, the combustion efficiency and safety of the mixed pulverized coal are effectively improved, while the ironmaking cost is reduced.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A blast furnace mixed pulverized coal injection, comprising anthracite, long flame coal and lignite, wherein the mass ratio of the anthracite, long flame coal and lignite is 15% to 88%: 2% to 85%: lignite 0 to 40%; the total mass of the anthracite, long flame coal and lignite is 100%.

[0008] Preferably, the mixed coal powder composed of anthracite, long flame coal and lignite has a total moisture content of ≤12%, an ash content of ≤12%, a sulfur content of ≤1%, and a calorific value of >23.5 MJ / kg.

[0009] Preferably, the mass ratio of lignite is controlled to be 23%, and the mass ratio of anthracite and long flame coal is 37%-60%:17%-40%; the total mass of the anthracite, long flame coal and lignite is 100%; the calorific value of the mixed coal powder composed of the anthracite, long flame coal and lignite is 26MJ / kg-28MJ / kg, and the volatile matter content is 17%-28%.

[0010] Preferably, the mass ratio of long flame coal is controlled to be 27%, and the mass ratio of anthracite and lignite is 37%-60%:13%-36%; the total mass of the anthracite, long flame coal and lignite is 100%; the calorific value of the mixed coal powder composed of the anthracite, long flame coal and lignite is 25MJ / kg-29MJ / kg, and the volatile matter content is 17%-26%.

[0011] A method for blending coal for mixed pulverized coal injection in a blast furnace comprises the following steps:

[0012] Crushing and grinding of anthracite, long flame coal and lignite samples, and conducting industrial analysis and calorific value determination on the processed coal samples;

[0013] The coal samples are dried to remove moisture from the coal samples, and then the coal samples of anthracite, long flame coal and lignite are fully mixed according to a predetermined ratio;

[0014] The mixed coal samples were measured using an explosiveness measuring device, and the return flame length values ​​were recorded. According to the difference in return flame lengths, the mixed coal samples were divided into three categories: non-explosive, weakly explosive, and moderately explosive.

[0015] According to the results of the explosiveness test, a ternary diagram of the relationship between the proportion of the mixed coal and the return flame length and a trend diagram of the mixed coal volatile matter and the return flame length are drawn. The obtained trend diagram is analyzed to determine that the mixed coal sample with a volatile matter below 25% is non-explosive;

[0016] Carry out combustion performance experiments on mixed coal samples to evaluate the combustion efficiency of mixed coal samples at different coal type ratios, and draw a ternary diagram of different coal type ratios and combustion performance of mixed coal samples based on the combustion performance experimental results;

[0017] Comprehensively analyze the ternary diagram and combustion performance test results to determine the ratio with good combustion performance and meeting the non-explosive conditions;

[0018] Coal samples were prepared according to the determined ratio, and explosion tests and combustion performance experiments were carried out again to verify the progressiveness of the obtained ratio.

[0019] Compared with the prior art, the present invention provides a blast furnace mixed pulverized coal injection and coal blending method, which has the following beneficial effects:

[0020] The present invention proposes a novel blast furnace mixed pulverized coal injection method by innovatively mixing lignite, long flame coal and anthracite, and further proposes a coal blending method for the mixed pulverized coal. The method not only significantly improves the combustion efficiency of the pulverized coal, but also enhances the safety and economy of the ironmaking process. The beneficial effects thereof specifically include the following contents:

[0021] (1) Significant improvement in combustion efficiency: The present invention makes full use of the high volatile matter of lignite and the high calorific value of long flame coal through precise coal ratio, and combines the low volatile matter characteristics of anthracite to achieve full combustion of mixed coal powder during blast furnace injection. This optimized combustion process releases more heat energy and effectively improves ironmaking efficiency.

[0022] (2) Significantly enhanced safety: The safety of pulverized coal is crucial during the blast furnace injection process. The present invention effectively reduces the risk of explosion of mixed pulverized coal during the injection process by precisely controlling the ratio of three types of coal: lignite, long flame coal and anthracite. The low volatility of anthracite helps stabilize the combustion process of pulverized coal, thereby ensuring the safety of the ironmaking process.

[0023] (3) Significant reduction in costs: The present invention significantly reduces the cost of ironmaking by optimizing the coal ratio. Lignite and long flame coal, due to their relatively low prices, combined with the stability provided by anthracite, form an economical and efficient coal blending solution, which helps to reduce the overall ironmaking cost and improve the economic benefits of the enterprise.

[0024] (4) Environmental friendliness: While pursuing economic benefits, the present invention also pays attention to environmental protection. By rationally matching the types of coal, the emission of harmful gases is reduced, and the impact on the environment is reduced. Lignite and long flame coal produce less pollutants during the combustion process, while the low volatile matter of anthracite helps to reduce the generation of smoke and dust. Together, they reduce environmental pollution during the ironmaking process.

[0025] (5) Simplicity of operation: The coal blending method proposed in the present invention is easy to implement and simple to operate. The coal ratio is intuitively displayed through the ternary diagram, so that operators can quickly understand and master the coal blending skills, reducing the complexity of operation and improving work efficiency.

[0026] (6) High flexibility: The coal blending method of the present invention is highly flexible and can adjust the coal ratio according to the specific needs of different ironmaking plants and the coal supply situation to meet the requirements of different ironmaking processes, thereby enhancing the applicability and flexibility of the method.

[0027] In summary, the mixed pulverized coal injection and coal blending method for blast furnaces proposed in the present invention are not only technically innovative, but also show significant effects and advantages in practical applications, providing a new solution for the high efficiency, safety, economy and environmental protection of pulverized coal injection in blast furnaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an overall flow chart of a coal blending method for mixed pulverized coal injection in a blast furnace proposed in Example 1 of the present invention;

[0029] Figure 2 The ternary diagram of the mixed coal ratio and the return flame length mentioned in Example 1 of the present invention;

[0030] Figure 3 This is a trend diagram of the mixed coal volatile matter and the return flame length mentioned in Example 1 of the present invention;

[0031] Figure 4 This is a ternary diagram of the mixed coal ratio and combustion performance mentioned in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] The present invention proposes a blast furnace mixed pulverized coal injection and coal blending method, which aims to overcome the disadvantages of a single coal type by rationally blending three types of coal, namely, lignite, long flame coal and anthracite, comprehensively utilizing their respective advantages, improving the combustion performance and safety of pulverized coal injection, and reducing ironmaking costs.

[0034] Lignite has the advantages of high volatile matter and low cost, but its high moisture content and easy weathering affect its combustion performance. By mixing lignite with long flame coal and anthracite, the flammability of lignite can be utilized, while the high calorific value of other coal types can make up for its low calorific value.

[0035] Long flame coal has high volatile matter and good combustion performance, but its cohesiveness and storage stability are poor. By mixing long flame coal with anthracite, the high cohesiveness of anthracite can be used to make up for the shortcomings of long flame coal, while improving storage conditions and reducing weathering and fragmentation.

[0036] Anthracite has the advantages of high calorific value and low pollution, but it has a high ignition point and high cost. By mixing anthracite with lignite and long flame coal, the flammability of lignite and long flame coal can be used to ignite anthracite, while taking advantage of the high calorific value and low pollution characteristics of anthracite. By pre-treating anthracite, such as crushing and preheating, its ignition point can be lowered and combustion efficiency can be improved.

[0037] The blast furnace mixed pulverized coal injection and coal blending method proposed by the present invention are described below in conjunction with specific drawings and example data, specifically including the following contents.

[0038] Embodiment 1:

[0039] The present invention provides a blast furnace mixed pulverized coal for injection, more specifically, a pulverized coal for injection that is a mixture of lignite, long flame coal and anthracite, wherein lignite with a volatile matter content of 40.35%, long flame coal with a volatile matter content of 35.94% and anthracite are uniformly mixed to form a mixed coal, and the mass ratio of the three types of coal is: 15% to 88% of anthracite, 2% to 85% of long flame coal, and 0 to 40% of lignite; the total mass of the three types of coal, the long flame coal and the lignite, is 100%.

[0040] The total moisture content of the above mixed coal is controlled not to exceed 12%, the ash content is controlled not to exceed 12%, the sulfur content is controlled not to exceed 1%, and the calorific value is controlled to be higher than 23.5MJ / kg.

[0041] Furthermore, the proportion of lignite is controlled to 23%, and the proportions of anthracite and long flame coal are 60%:17%, 55%:22%, 50%:27%, 45%:32%, and 37%:40% respectively, so that the calorific value of the mixed coal is 26MJ / Kg~28MJ / Kg, and the volatile matter content is 17%~28%.

[0042] Furthermore, the proportion of long flame coal is controlled to 27%, anthracite and lignite to 60%:13%, 55%:18%, 45%:28% and 37%:36% respectively, so that the calorific value of the mixed coal is 25MJ / Kg~29MJ / Kg and the volatile matter content is 17%~26%.

[0043] Based on the above content, the coal blending method of the mixed coal powder is described below, which specifically includes the following contents:

[0044] Step 1. Preparation and analysis of coal samples:

[0045] First, the three coal samples of anthracite, long flame coal and lignite were crushed and ground to ensure that the coal samples with a particle size of less than 200 mesh accounted for more than 70% of the total mass. Then, the coal samples were subjected to industrial analysis and calorific value determination. The specific analysis results are as follows:

[0046] Table 1: Industrial analysis and calorific value of coal samples

[0047]

[0048] In Table 1, A d V represents the ash content of coal powder on an air-dried basis; daf M represents the volatile matter content of coal powder on an air-dried basis; t represents the ash moisture content of coal powder on an air-dried basis; Q net,ar Represents the high heating value on an air dry basis.

[0049] According to Table 1, we can know that:

[0050] Long flame coal has a volatile content of about 36% and a calorific value of 25.6 MJ / kg;

[0051] The volatile matter of lignite is about 40% and the calorific value is 18.2MJ / kg;

[0052] Anthracite has low volatile matter and a calorific value of 31.5MJ / kg.

[0053] Step 2: Drying and mixing of coal samples:

[0054] The coal samples were dried at 105°C to 110°C for 2 hours to remove moisture from the coal samples. Subsequently, the coal samples were fully mixed according to the predetermined ratio and prepared for the next step of explosiveness determination.

[0055] Step 3: Determination of coal powder explosion:

[0056] The mixed coal samples were measured using a long-tube coal powder explosion test device, and the return flame length was recorded. According to the difference in return flame length, the coal samples were divided into three categories: non-explosive, weakly explosive, and medium-strongly explosive.

[0057] Step 4: Draw a ternary diagram:

[0058] According to the measurement results, a ternary diagram of the relationship between the coal type ratio and the return flame length is drawn (such as Figure 2 As shown in the figure, the unit of return flame length is mm), and the trend diagram of the change of mixed coal volatile matter and return flame length (as shown in the figure Figure 3 By analyzing the trend chart, it is determined that mixed coal with a volatile content below 25% is non-explosive.

[0059] Step 5: Combustion performance test:

[0060] The ratio range with a return flame length below 200 mm was selected from the ternary diagram, and a combustion performance experiment was carried out to evaluate the combustion efficiency under different ratios.

[0061] Step 6: Drawing of the combustion performance ternary diagram:

[0062] According to the combustion performance test results, a ternary diagram of the ratio of mixed coal and combustion performance is drawn (such as Figure 4 As shown in the figure, the higher the combustion characteristic index, the better the combustion performance), to intuitively show the combustion performance under different ratios.

[0063] Step 7: Determination of optimal ratio:

[0064] Through comprehensive analysis of the ternary diagram and combustion performance experimental results, it was determined that the ratio of 45% anthracite, 27% long flame coal and 28% lignite has better combustion performance and meets the non-explosive conditions.

[0065] Step 8: Explosiveness determination of final coal sample:

[0066] The coal samples were prepared according to the optimized ratio and tested again using the long-tube coal powder explosion testing device to confirm that they were non-explosive.

[0067] Step 9: Analysis of combustion characteristic parameters:

[0068] The combustibility of the mixed coal powder was analyzed in depth, including ignition temperature, burnout temperature, combustibility index and comprehensive combustion characteristic index, as shown in Table 2.

[0069] Table 2 Mixed coal combustion characteristic parameters

[0070]

[0071]

[0072] In Table 2, WY represents anthracite; CY represents long flame coal; HM represents lignite; T i Represents the ignition temperature of coal powder; T h represents the combustion temperature of pulverized coal; T k represents the temperature at which the weight loss rate is the largest during the combustion of coal powder; S represents the comprehensive combustion characteristic index of coal powder; and C represents the combustibility index. According to the content of Table 2, in the present invention, the addition of lignite has a good effect on improving the combustion performance of anthracite.

[0073] Through the above steps, the present invention realizes an efficient, safe and economical method for blending pulverized coal for blast furnace injection, and provides a new technical solution for the ironmaking industry.

[0074] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles described in the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A blast furnace mixed pulverized coal injection method, characterized in that: It comprises anthracite, long flame coal and lignite, wherein the mass ratio of anthracite, long flame coal and lignite is 15%-88%: 2%-85%: lignite 0-40%; the total mass of anthracite, long flame coal and lignite is 100%.

2. The blast furnace mixed pulverized coal injection method according to claim 1, characterized in that: The mixed coal powder composed of anthracite, long flame coal and lignite has a total moisture content of ≤12%, an ash content of ≤12%, a sulfur content of ≤1%, and a calorific value of >23.5 MJ / kg.

3. The blast furnace mixed pulverized coal injection method according to claim 1, characterized in that: The mass ratio of lignite is controlled to be 23%, and the mass ratio of anthracite and long flame coal is 37%-60%:17%-40%; the total mass of the anthracite, long flame coal and lignite is 100%; the calorific value of the mixed coal powder composed of the anthracite, long flame coal and lignite is 26MJ / kg-28MJ / kg, and the volatile matter content is 17%-28%.

4. The blast furnace mixed pulverized coal injection according to claim 1, characterized in that: The mass ratio of long flame coal is controlled to be 27%, and the mass ratio of anthracite and lignite is controlled to be 37%-60%:13%-36%; the total mass of the anthracite, long flame coal and lignite is 100%; the calorific value of the mixed coal powder composed of the anthracite, long flame coal and lignite is 25MJ / kg-29MJ / kg, and the volatile matter content is 17%-26%.

5. The method for blending coal for mixed pulverized coal injection in a blast furnace according to any one of claims 1 to 4, characterized in that: The following steps are involved: Crushing and grinding of anthracite, long flame coal and lignite samples, and conducting industrial analysis and calorific value determination on the processed coal samples; The coal samples are dried to remove moisture from the coal samples, and then the coal samples of anthracite, long flame coal and lignite are fully mixed according to a predetermined ratio; The mixed coal samples were measured using an explosiveness measuring device, and the return flame length values ​​were recorded. According to the difference in return flame lengths, the mixed coal samples were divided into three categories: non-explosive, weakly explosive, and moderately explosive. According to the results of the explosiveness test, a ternary diagram of the relationship between the proportion of the mixed coal and the return flame length and a trend diagram of the mixed coal volatile matter and the return flame length are drawn. The obtained trend diagram is analyzed to determine that the mixed coal sample with a volatile matter below 25% is non-explosive; Carry out combustion performance experiments on mixed coal samples to evaluate the combustion efficiency of mixed coal samples at different coal type ratios, and draw a ternary diagram of different coal type ratios and combustion performance of mixed coal samples based on the combustion performance experimental results; Comprehensively analyze the ternary diagram and combustion performance test results to determine the ratio with good combustion performance and meeting the non-explosive conditions; Coal samples were prepared according to the determined ratio, and explosion tests and combustion performance experiments were carried out again to verify the progressiveness of the obtained ratio.

6. A method for blending coal for mixed pulverized coal injection in a blast furnace according to claim 5, characterized in that: Among the coal samples after crushing and grinding, particles with a size less than 200 mesh account for more than 70% of the total mass.

7. A method for blending coal for mixed pulverized coal injection in a blast furnace according to claim 5, characterized in that: The drying temperature of the coal sample drying operation is 105℃~110℃, and the drying time is 2~3h.

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