Coke powder pre-screening grading process and grading system for sintering production

Abstract

The invention relates to the field of sintering production fuel treatment, and discloses a coke powder pre-screening grading process and grading system for sintering production, and the process comprises the following steps: feeding coke powder is conveyed to a vibrating screen through a feeding conveying belt; the feeding coke powder is pre-screened and graded through the vibrating screen, undersize products and oversize products are obtained, the undersize products are coke powder with the particle size smaller than 4 mm, and the oversize products are coke powder with the particle size larger than or equal to 4 mm; the screen underflow bypasses a four-roller crusher through a screen underflow bypass conveying branch and is conveyed to a fuel finished product belt; the oversize product is conveyed to the four-roller crusher through an oversize conveying branch to be crushed, and a crushed product is obtained; and the crushed products are conveyed to an upstream blanking point of the fuel finished product belt, and the crushed products and the screen underflow converge at the upstream blanking point and then are output.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sinter production fuel treatment, in particular to a coke powder pre-screening classification process and classification system for sinter production. BACKGROUND

[0002] In the sinter production process, solid fuel usually participates in mixing, distribution and combustion heat supply in the form of coke powder. The combustion speed, combustion uniformity and carrying characteristics of coke powder in the material layer will affect the temperature field distribution, permeability and sintering process stability of the material layer. The particle size composition of coke powder is one of the important factors affecting the above processes. When the particle size structure is unreasonable or fluctuates greatly, it is easy to cause uneven combustion, material layer resistance changes, dust and dust removal load fluctuations and other phenomena.

[0003] In the existing production line, coke powder or returned coke material usually enters the crushing and screening link after conveying to meet the subsequent batching requirements. One common scheme is to crush the whole material, for example, using a pair of roller crushers or four-roll crushers to crush large-size material to the target particle size range, and then conveying to the fuel finished product belt or batching system. Another scheme is to combine screening and crushing, that is, to set a vibrating screen or other screening equipment before or after crushing to classify the material, and the screened material returns or enters the crusher for processing, and the screened material directly enters the subsequent conveying and batching link. In the above scheme, the screen angle, amplitude, processing capacity and other parameters are usually configured according to the particle size distribution, moisture content, adhesion and conveying capacity of the material to realize continuous operation.

[0004] In the working condition where the proportion of fine particles of coke powder is high and fluctuates, the whole crushing or screening and crushing process often cannot stably control the particle size structure of the final fuel, which easily increases the fine particles while reducing the large particles, resulting in fluctuations in combustion and permeability and increasing the risk of dust carrying and escaping; at the same time, the screening link is prone to hole blockage and efficiency reduction when the moisture content changes or the material adheres, thereby causing classification boundary drift and crushing load fluctuation, increasing the system operation stability and maintenance workload.

[0005] Therefore, there is an urgent need for a technical scheme that can stably control the particle size structure of coke powder under continuous conveying conditions and also consider the screening reliability and equipment operation stability. SUMMARY

[0006] The purpose of the present application is to provide a coke powder pre-screening classification process and classification system for sinter production to solve the problem that the existing process easily causes further increase in fine particles while reducing large particles, resulting in fluctuations in particle size structure.

[0007] In order to achieve the above application purpose, the present application adopts the following technical scheme: a coke powder pre-screening classification process for sinter production, comprising the following steps:

[0008] S1: feeding the sintering charge coke powder into a vibrating screen through a feeding conveyor belt;

[0009] S2: pre-screening and grading the feeding coke powder by using the vibrating screen to obtain undersize and oversize, wherein the undersize is coke powder with a particle size less than 4 mm, and the oversize is coke powder with a particle size greater than or equal to 4 mm;

[0010] S3: bypassing the undersize around a four-roll crusher through an undersize bypass conveying branch and conveying the undersize to a fuel product belt;

[0011] S4: conveying the oversize to the four-roll crusher through an oversize conveying branch to obtain a crushing product;

[0012] S5: conveying the crushing product to an upstream dropping point of the fuel product belt, and the crushing product and the undersize are combined at the upstream dropping point.

[0013] Preferably, the screen surface installation angle of the vibrating screen is 20° to 30°.

[0014] Preferably, the amplitude of the vibrating screen is 4 mm to 6 mm.

[0015] Preferably, the processing capacity of the vibrating screen is 40 t / h to 60 t / h.

[0016] Preferably, the vibrating screen adopts a relaxation elastic screen mesh, which alternately is in a tension state and a relaxation state during vibration.

[0017] Preferably, the relaxation elastic screen mesh is a multi-layer screen mesh structure, and the screen hole diameters from top to bottom are 4.1 mm, 3.9 mm and 3.8 mm.

[0018] Further, the present application also provides a coke powder pre-screening and grading system for implementing the coke powder pre-screening and grading process, and the coke powder pre-screening and grading system comprises:

[0019] a feeding conveyor belt for conveying the feeding coke powder;

[0020] a vibrating screen, the feeding end of the vibrating screen is connected with the discharging end of the feeding conveyor belt, the vibrating screen has undersize and oversize outlets for grading the feeding coke powder into undersize and oversize according to 4 mm, wherein the undersize is coke powder with a particle size less than 4 mm, and the oversize is coke powder with a particle size greater than or equal to 4 mm;

[0021] an undersize bypass conveying branch, the feeding end of the undersize bypass conveying branch is connected with the undersize outlet of the vibrating screen, and the undersize bypass conveying branch is used for conveying the undersize to a fuel product belt;

[0022] an oversize conveying branch, a feed end of which is interfaced with the oversize outlet of the vibrating screen;

[0023] a four-roller crusher, a feed end of which is interfaced with the discharge end of the oversize conveying branch, for crushing the oversize to obtain a crushed product;

[0024] a fuel product belt, an upstream drop point of which is respectively interfaced with the discharge end of the undersize bypass conveying branch and the discharge end of the four-roller crusher, for receiving the undersize and the crushed product and forming a combined output.

[0025] Preferably, the undersize bypass conveying branch does not pass through the feed end of the four-roller crusher, and the undersize does not enter the four-roller crusher.

[0026] Preferably, the system further comprises a dust removal pipeline, which is in communication with the receiving area and the screening area of the vibrating screen, for extracting dust-containing gas generated in the screening process.

[0027] Preferably, the system further comprises an interlock control unit, which receives the operating state signal of the vibrating screen and outputs an interlock control signal when the vibrating screen is stopped, the interlock control signal being used for implementing stop control and start prohibition control of the four-roller crusher respectively.

[0028] Compared with the prior art, the technical scheme has the following beneficial effects:

[0029] I. By arranging the vibrating screen in the feeding conveying path and pre-screening and classifying the feeding coke powder at a predetermined classification particle size, the undersize bypasses the four-roller crusher and directly enters the fuel product belt through the undersize bypass conveying branch, and the oversize enters the four-roller crusher through the oversize conveying branch after being crushed, and then combines with the undersize at the upstream drop point of the fuel product belt to form a combined output, thereby reducing the probability of fine particle material entering the crushing link and reducing the risk of further refinement of fine particle material, and making the formation process of fuel particle size structure more controllable.

[0030] II. By only crushing the oversize, the processing object of the four-roller crusher is concentrated on larger particle material, the overall crushing amount is reduced, and the crushing load is more stable, thereby being conducive to reducing the disturbance of the crushing link to the downstream conveying and batching, improving the continuous operation stability of the system, and reducing the dust generated due to excessive crushing.

[0031] In addition, by configuring the installation angle and amplitude of the screen surface of the vibrating screen and the processing capacity in a range suitable for the screening of coke breeze, the screening capacity is matched with the conveying capacity and the crushing capacity, thereby improving the stability of the pre-screening classification process, reducing the screening fluctuation caused by material accumulation and classification limit drift, and facilitating the continuous and consistent flow of the oversize and undersize materials.

[0032] III. By adopting the relaxation elastic screen mesh and setting multiple layers of screen mesh aperture combinations, the screen mesh alternately enters the tension and relaxation state during vibration, thereby reducing the probability of screen hole clogging and improving the stability of the screen passing near the critical particle size, making the classification limit more stable and enhancing the adaptability to the fluctuation of the moisture content or adhesion of the material.

[0033] In addition, by setting the dust removal pipeline in the receiving area and the screening area of the vibrating screen to extract and remove the dust-containing gas, the dust emission during the screening process is reduced, and the site dust emission is reduced; and by setting the interlocking control unit, the four-roller crusher is controlled to stop and the start prohibition control is maintained when an abnormal state such as the stop of the vibrating screen is detected, thereby reducing the risk of the crusher being in an empty load or blocked under abnormal conditions, and improving the safety and reliability of the system operation. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The figure is a process flow diagram of the coke breeze pre-screening classification process of the embodiment.

[0035] Figure 2 The figure is a comparison schematic diagram of the embodiment before and after the process transformation, wherein Figure 2 The left side is a process schematic diagram before the transformation, Figure 2 and the right side is a process schematic diagram after the transformation.

[0036] Figure 3 The figure is a site layout diagram of the embodiment.

[0037] In the figure: 1, an inlet conveying belt; 2, a vibrating screen; 3, an undersize bypass conveying branch; 4, an oversize conveying branch; 5, a four-roller crusher; and 6, a fuel product belt. DETAILED DESCRIPTION

[0038] The preferred embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0039] As Figures 1-3 shown, a coke breeze pre-screening classification process for sintering production includes the following steps: feeding the coke breeze used for sintering into the vibrating screen 2 through the inlet conveying belt 1; pre-screening and classifying the coke breeze by using the vibrating screen 2 to obtain undersize and oversize, wherein the undersize is coke breeze with a particle size less than 4 mm, and the oversize is coke breeze with a particle size greater than or equal to 4 mm; and conveying the undersize to the fuel product belt 6 by bypassing the four-roller crusher 5 through the undersize bypass conveying branch 3.

[0040] To illustrate the particle size composition of the undersize of the vibrating screen 2, particle size statistics are performed on the undersize, and the results are shown in Table 1.

[0041] Table 1 Particle size composition of undersize (%)

[0042] Number <1 mm 1-3 mm 3-5 mm >5 mm 1 63.86 28.03 7.73 0.38 2 56.10 31.30 12.00 0.60 3 66.07 25.01 8.12 0.79 4 62.60 27.50 9.20 0.70 5 62.15 25.76 11.69 0.40 6 63.53 27.72 7.56 1.19 7 59.85 27.99 9.99 2.17 8 53.27 33.57 11.33 1.84 Average 60.93 28.36 9.70 1.01

[0043] To obtain the data in Table 1, in this embodiment, the undersize discharged from the undersize outlet of the vibrating screen 2 is taken as the statistical object, and the undersize is sampled in a stable running state during the conveying process in the undersize bypass conveying branch 3; the sampled material is subjected to a screening test, the particle size is divided into four particle size intervals of less than 1 mm, 1 mm to 3 mm, 3 mm to 5 mm and greater than 5 mm, and the percentage of the mass of each particle size interval to the total mass of the sample is taken as the particle size composition. Numbers 1 to 8 in Table 1 are the sampling results of different batches, and the average is the arithmetic mean of the results of each batch, which is used to represent the overall distribution characteristics of the particle size of the undersize.

[0044] As can be seen from Table 1, the proportion of the particle size less than 1 mm in the undersize is 60.93% on average, the proportion of the particle size of 1 mm to 3 mm is 28.36% on average, and the total proportion of the two is 89.29%, indicating that the undersize is mainly composed of fine particle sizes; at the same time, the proportion of the particle size greater than 5 mm is 1.01% on average, indicating that the proportion of large particle sizes entrained in the undersize is low. Based on the above particle size composition characteristics, in this embodiment, the undersize is bypassed through the undersize bypass conveying branch 3 to output the four-roll crusher 5, so as to reduce the probability of further refining of fine particle materials after entering the four-roll crusher 5, and to converge with the crushing products of the oversize at the upstream material dropping point of the fuel finished product belt 6, so as to ensure the continuity of classification and conveying while improving the controllability of the fuel particle size structure.

[0045] The oversize is conveyed through the oversize conveying branch 4 to the four-roll crusher 5 for crushing to obtain the crushing products.

[0046] To illustrate the influence of the four-roll crusher 5 on the particle size of the material, the particle size composition statistics before and after crushing are shown in Table 2.

[0047] In this embodiment, the material to be crushed entering the four-roll crusher 5 is the oversize, which can also be referred to as the coke return material.

[0048] Table 2 Particle size composition before and after coke return crushing (%)

[0049] Time / Stage <1 mm 1-3 mm 3-5 mm >5 mm Before crushing 40.01 29.60 10.43 19.96 After crushing 49.23 26.86 14.30 9.61 Comparison 9.22 −2.74 3.87 −10.35

[0050] To obtain the data in Table 2, in this embodiment, the material to be crushed entering the four-roll crusher 5 is taken as the statistical object, and samples are taken at the inlet and outlet of the four-roll crusher 5 respectively; the sampled material is subjected to a screening test, the particle size is divided into four particle size intervals of less than 1 mm, 1 mm to 3 mm, 3 mm to 5 mm and greater than 5 mm, and the percentage of the mass of each particle size interval to the total mass of the sample is taken as the particle size composition. The comparison in Table 2 is the percentage of each particle size after crushing minus the percentage of each particle size before crushing, which is used to represent the influence range of the crushing process on the particle size composition.

[0051] As can be seen from Table 2, after crushing by the four-roll crusher 5, the percentage of the particle size greater than 5 mm is reduced from 19.96% to 9.61%, with a reduction of 10.35 percentage points, indicating that the four-roll crusher 5 has a significant crushing effect on large particle size material; at the same time, the percentage of the particle size less than 1 mm is increased from 40.01% to 49.23%, with an increase of 9.22 percentage points, indicating that the crushing process will cause the percentage of fine particle size to increase. Based on this particle size change characteristic, in this embodiment, the feed coke powder is pre-screened and classified by the vibrating screen 2 in the process flow, and the undersize material with a particle size less than 4 mm is output through the undersize bypass conveying branch 3, so as to reduce the probability of further refinement of fine particle size material after entering the four-roll crusher 5, and the undersize material is combined with the oversize material after crushing at the material dropping point upstream of the fuel finished product belt 6.

[0052] Further, to illustrate the particle size composition of the crushed product output by the four-roll crusher 5, the particle size of the crushed product is counted, and the results are shown in Table 3.

[0053] Table 3 Particle size composition of oversize material after crushing (%)

[0054] Number Less than 1 mm 1 mm to 3 mm 3 mm to 5 mm More than 5 mm 1 20.32 20.26 24.12 35.30 2 20.50 24.50 36.80 18.20 3 18.63 14.52 24.26 42.60 4 21.60 21.40 30.70 26.30 5 14.52 25.30 33.57 26.61 6 21.34 14.12 20.24 44.30 7 20.90 24.58 19.62 34.90 8 15.40 19.62 17.51 47.48 Average 19.15 20.54 25.85 34.46

[0055] To obtain the data in Table 3, in this embodiment, the crushed product discharged from the outlet of the four-roll crusher 5 is taken as the statistical object, and multiple batches of samples are taken under the stable running state of the system; each batch of samples is subjected to a screening test, the particle size is divided into four particle size intervals of less than 1 mm, 1 mm to 3 mm, 3 mm to 5 mm and greater than 5 mm, and the percentage of the mass of each particle size interval to the total mass of the sample is taken as the particle size composition. Numbers 1 to 8 in Table 3 are the results of different batches of sampling, and the average is the arithmetic mean of the results of each batch, which is used to represent the overall characteristics of the particle size distribution of the crushed product.

[0056] Table 3 shows that the average proportion of particles larger than 5mm in the crushed product is 34.46%, and the average proportion of particles between 3mm and 5mm is 25.85%, indicating that a certain proportion of large and medium-sized particles still exist in the oversize material after processing by the four-roll crusher 5. Combined with the bypass output of the undersize material via the undersize bypass conveyor branch 3 in this embodiment, the undersize material, being predominantly fine-grained, can reduce the probability of entering the four-roll crusher 5, thereby reducing the risk of further fine particle refinement. Simultaneously, the crushed product and undersize material merge at the upstream discharge point of the fuel finished product belt 6, allowing the particle size structure of the final output material to be adjusted jointly by the grading of the vibrating screen 2 and the crushing treatment of the four-roll crusher 5.

[0057] The crushed products are transported to the upstream discharge point of the fuel finished product belt 6, so that the crushed products and the screened materials merge at the upstream discharge point to form a combined output.

[0058] To ensure the above steps are feasible, the discharge end of the feed conveyor belt 1 is connected to the feed end of the vibrating screen 2 via a discharge chute; the undersize outlet of the vibrating screen 2 is connected to the feed end of the undersize bypass conveyor branch 3, and the oversize outlet of the vibrating screen 2 is connected to the feed end of the oversize conveyor branch 4; the discharge end of the oversize conveyor branch 4 is connected to the feed end of the four-roll crusher 5, and the discharge end of the four-roll crusher 5 is connected to the upstream discharge point of the fuel finished product belt 6 via a crushing discharge chute; the discharge end of the undersize bypass conveyor branch 3 is connected to the upstream discharge point of the fuel finished product belt 6, so that the undersize material and the crushed product merge at the same upstream discharge point and are then output. A particle size of 4mm is used as the grading boundary; the undersize material is the material that passes the grading boundary, and the oversize material is the material that does not pass the grading boundary. During operation, the screening and crushing status can be monitored by combining the thickness of the material layer on the vibrating screen 2, the load of the oversize conveyor branch 4, and the operating current of the four-roll crusher 5 to maintain grading stability and merging continuity.

[0059] like Figures 1-3 As shown, in this embodiment, the screen surface installation angle of the vibrating screen 2 is set to 20° to 30°, and the amplitude of the vibrating screen 2 is set to 4mm to 6mm.

[0060] To illustrate the screening effect of vibrating screen 2 under different amplitude conditions, the oversize and undersize materials were weighed and statistically analyzed, and the results are shown in Table 4.

[0061] Table 4. Coke powder screening efficiency

[0062] Note: The "Percentage of Undersize Material" in the table is the percentage of the mass of undersize material to the total weight.

[0063] Number Amplitude (mm) Total weight (kg) Screen oversize (kg) Screen undersize (kg) Screen undersize ratio (%) 1 4±1 9.1 3.0 6.1 67.03 2 4±1 10.2 3.5 6.7 65.69 3 4±1 11.3 4.2 7.1 62.83 4 4±1 11.8 4.5 7.3 61.86 5 4±1 9.9 3.5 6.4 64.65 6 4±1 10.6 4.0 6.6 62.26 7 4±1 10.4 3.8 6.6 63.46 8 4±1 9.8 3.7 6.1 62.24 Average 4±1 10.39 3.78 6.61 63.75 1 5±1 9.9 3.1 6.8 68.71 2 5±1 11.4 4.21 7.19 63.07 3 5±1 9.9 3.72 6.18 62.4 4 5±1 10.6 4.02 6.58 62.08 5 5±1 10.9 4.22 6.68 61.28 6 5±1 10.44 1.26 9.18 87.89 7 5±1 10.58 2.3 8.28 78.22 8 5±1 8.67 1.62 7.05 81.3 Average 5±1 10.30 3.06 7.24 70.62 1 6±1 11.5 3.5 8.0 69.57 2 6±1 10.8 3.1 7.7 71.30 3 6±1 9.8 2.5 7.3 74.49 4 6±1 8.6 2.1 6.5 75.58 5 6±1 10.9 3.5 7.4 67.89 6 6±1 10.7 3.6 7.1 66.36 7 6±1 9.9 2.5 7.4 74.75 8 6±1 11.6 2.8 8.8 75.86 Average 6±1 10.48 2.95 7.53 71.97

[0064] Note: The "average" in the table is the arithmetic mean of 8 test data, and the under-screen material ratio is the arithmetic mean of the corresponding under-screen material ratio of 8 tests.

[0065] To obtain the data in Table 4, in this embodiment, the screening process of the vibrating screen 2 is taken as the statistical object. When the vibrating screen 2 is in a stable operating state, the coke powder entering the vibrating screen 2 is weighed in batches, the total weight of each test is recorded, and the oversize and undersize are collected and weighed respectively; the under-screen material ratio is calculated as the ratio of the under-screen material mass to the total weight, expressed in percentage. The amplitude is obtained by setting the exciter of the vibrating screen 2, and multiple repeated tests are carried out under the conditions of three amplitudes of 4±1, 5±1 and 6±1, respectively, to reduce the influence of single material fluctuation.

[0066] As can be seen from Table 4, the average under-screen material ratio is 63.75% under the condition of amplitude of 4±1, and the average under-screen material ratio is 71.97% under the condition of amplitude of 6±1, which indicates that under the structure and material conditions of this embodiment, increasing the amplitude is beneficial to improve the under-screen material ratio, thereby improving the screening ability of the vibrating screen 2 to the material with particle size less than the classification limit. Based on the screening effect, the amplitude of the vibrating screen 2 in this embodiment is set to be in the range of 4mm to 6mm, so as to take into account the screening efficiency and the processing matching relationship of the downstream oversize conveying branch 4 and the four-roll crusher 5.

[0067] The processing capacity of the vibrating screen 2 is set to be 40t / h to 60t / h to meet the working condition requirements of pre-screening classification of the incoming coke powder and matching the processing capacity of the four-roll crusher 5.

[0068] The above-mentioned screen surface installation angle is achieved by adjusting the mounting seat between the frame and the foundation of the vibrating screen 2, and after adjustment, the mounting seat is locked and fixed to avoid angle drift during operation; the amplitude is achieved by setting the eccentric block parameters of the exciter of the vibrating screen 2, and after setting, the amplitude is positioned by fasteners and reviewed in the trial operation whether it is in the range of 4mm to 6mm; the processing capacity can be adjusted by the belt speed of the incoming conveying belt 1 and the opening degree of the feeder gate, and matched and checked in combination with the effective length and width of the screen surface of the vibrating screen 2, so as to form a stable material layer thickness on the screen surface and avoid local material accumulation leading to classification limit drift. In order to facilitate the reproduction of the working condition, it is recommended to record the screen surface installation angle of the vibrating screen 2, the amplitude setting value, the belt speed of the incoming conveying belt 1 and the hourly processing capacity under stable working condition when put into operation, as the control parameters for subsequent operation.

[0069] As Figures 1-3As shown, in the present embodiment, the vibrating screen 2 adopts a relaxation elastic screen mesh, which alternately assumes a tensioned state and a relaxed state during vibration, so as to improve the screening efficiency and reduce the probability of screen hole blockage; the relaxation elastic screen mesh is a multi-layer screen mesh structure, and the screen hole diameters from top to bottom are 4.1 mm, 3.9 mm and 3.8 mm, so as to realize multi-stage screening around the 4 mm classification limit and stabilize the particle size of the undersize.

[0070] The relaxation elastic screen mesh can adopt an elastic screen surface mounting mode, that is, the screen mesh is fixed through a tensioning beam at both ends and is limited through a supporting beam at the middle part, so that the screen mesh alternately deforms controllably in tension and relaxation in the vibration direction; the multi-layer screen mesh is sequentially laid from top to bottom and is respectively fixed at the corresponding screen frame layer position of the vibrating screen 2, and a spacing support strip is arranged between the screen meshes to ensure that the screen surfaces do not interfere with each other. The screen hole diameters of 4.1 mm, 3.9 mm and 3.8 mm are arranged around the 4 mm classification limit, the upper layer screen mesh is used to preferentially release the screenable particles close to the classification limit, and the middle and lower layer screen meshes are used to improve the screen passing probability of the critical particle size particles and stabilize the particle size distribution of the undersize; during maintenance, the single-layer screen mesh can be quickly replaced through the detachable pressing strip, and the consistency of the tensioning force is checked after replacement, so as to avoid the classification limit drift of the vibrating screen 2 due to the relaxation of the screen mesh.

[0071] On the basis of the above-mentioned coke powder pre-screening classification process, in order to enable each step to be continuously and stably executed on the production line, the present embodiment gives a coke powder pre-screening classification system for implementing the process. The system realizes the material flow direction corresponding to the process steps and equipment cooperation through pre-screening and shunting of the incoming coke powder, crushing treatment of the oversize, and confluence conveying of the undersize and the crushing product. The structure, connection relationship and material conveying path of the coke powder pre-screening classification system will be described below with reference to the accompanying drawings.

[0072] As shown in the figure, Figures 1-3 The coke powder pre-screening classification system includes an incoming material conveying belt 1, a vibrating screen 2, an undersize bypass conveying branch 3, an oversize conveying branch 4, a four-roller crusher 5 and a fuel product belt 6. The incoming material conveying belt 1 is used to convey the incoming coke powder; the incoming end of the vibrating screen 2 is butted against the outgoing end of the incoming material conveying belt 1, the vibrating screen 2 has an undersize outlet and an oversize outlet, and is used to classify the incoming coke powder into undersize and oversize according to the 4 mm classification limit; the incoming end of the undersize bypass conveying branch 3 is butted against the undersize outlet of the vibrating screen 2, and is used to convey the undersize to the fuel product belt 6; the incoming end of the oversize conveying branch 4 is butted against the oversize outlet of the vibrating screen 2; the incoming end of the four-roller crusher 5 is butted against the outgoing end of the oversize conveying branch 4, and is used to crush the oversize to obtain a crushing product; the upstream dropping points of the fuel product belt 6 are respectively butted against the outgoing end of the undersize bypass conveying branch 3 and the outgoing end of the four-roller crusher 5, and are used to receive the undersize and the crushing product and form a confluence output.

[0073] To ensure the system structure can be implemented, the upstream material dropping point of the fuel product belt 6 can be provided as a confluence material dropping box, the confluence material dropping box has a screen under material inlet which is connected with the screen under bypass conveying branch 3 and a crushing material inlet which is connected with the discharge end of the four-roll crusher 5, and the two materials are guided to the same dropping area of the fuel product belt 6, so that the confluence output is realized; the confluence material dropping box can be provided with a flow guide plate inside to reduce the segregation of the two materials in the dropping process. The screen under bypass conveying branch 3 and the screen over conveying branch 4 can be provided in the form of a belt conveyor respectively, and a fly ash prevention baffle and a maintenance door are arranged at the discharge end of each to meet the operation and maintenance; a buffer chute or a flexible connection can be arranged between the discharge end of the four-roll crusher 5 and the confluence material dropping box to reduce the impact and reduce the vibration transmission.

[0074] In the embodiment, the material flow path of the screen under bypass conveying branch 3 does not pass through the inlet of the four-roll crusher 5, so that the screen under material does not enter the four-roll crusher 5; the system further comprises a dust removal pipeline which is in communication with the material receiving area and the screening area of the vibrating screen 2, and is used for extracting and discharging the dust-containing gas generated in the screening process; the system further comprises an interlocking control unit which receives the running state signal of the vibrating screen 2, and outputs an interlocking control signal when the vibrating screen 2 is stopped, the interlocking control signal is used for implementing the stop control and the start prohibition control of the four-roll crusher 5.

[0075] The bypass of the screen under bypass conveying branch 3 around the four-roll crusher 5 can be realized by physical isolation, that is, the screen under bypass conveying branch 3 and the inlet chute of the four-roll crusher 5 do not form a butt joint relationship, and a material blocking plate and a closure cover are arranged at the necessary place to avoid the screen under material falling into the four-roll crusher 5. The dust removal pipeline can be provided with a material receiving cover at the material receiving area of the vibrating screen 2 and a screen surface cover at the screening area of the vibrating screen 2, the material receiving cover and the screen surface cover are connected with the negative pressure fan and the dust removal equipment through the branch pipe and the main pipe, so that the stable negative pressure extraction is formed at the material receiving position and the screening position, and the dust escape is reduced.

[0076] To illustrate the change of the dust removal ash residual carbon before and after the transformation, the dust removal ash residual carbon of each electric field of the electric dust removal is counted, and the results are shown in Table 5.

[0077] Table 5 Change of residual carbon in electric field (%)

[0078] Stage 1, 2 carbon residue in electric field dust removal ash 3, 4 carbon residue in electric field dust removal ash Before transformation 1 3.13 2.93 Before transformation 2 2.29 3.35 After transformation 1 1.73 2.34 After transformation 2 1.84 2.40 Before and after comparison −0.93 −0.77

[0079] To obtain the data in Table 5, the dust collected by the electric field of the electric precipitator 1 and 2 before and after the modification and the dust collected by the electric field of the electric precipitator 3 and 4 before and after the modification were sampled, and the mass fraction of residual carbon in the dust was measured; wherein, the before modification 1 and the before modification 2 are the recorded results of different statistical batches before the modification, and the after modification 1 and the after modification 2 are the recorded results of different statistical batches after the modification. The difference between the average value of the two records before the modification and the average value of the two records after the modification in Table 5 is used to represent the change range of the residual carbon level before and after the modification.

[0080] As can be seen from Table 5, the residual carbon of the dust in the 1st and 2nd electric field after the modification is reduced from an average of 2.71% before the modification to an average of 1.79% after the modification, a decrease of about 0.93 percentage points; the residual carbon of the dust in the 3rd and 4th electric field is reduced from an average of 3.14% before the modification to an average of 2.37% after the modification, a decrease of about 0.77 percentage points. The above results can be used as a reference for the improvement of the related indicators in the production process under the condition that the pre-screening classification of the vibrating screen 2, the bypass output of the undersize material through the bypass conveying branch 3, and the cooperation of the dust removal pipeline are combined.

[0081] The opening of the receiving cover and the screen cover can be provided with a flexible sealing curtain to balance the sealing and maintenance. The interlocking control unit can be composed of a controller and a relay output module, and the running state signal can be obtained from the running feedback signal of the vibrating screen 2 motor loop; when the vibrating screen 2 is detected to be stopped, the controller outputs a stop control signal to make the four-roller crusher 5 stop, and at the same time outputs a start prohibition control signal to make the start loop of the four-roller crusher 5 remain open, until the vibrating screen 2 resumes operation and meets the preset allowed conditions to release the start prohibition control, so as to reduce the abnormal impact risk of the four-roller crusher 5 caused by the failure of the oversize material to be effectively diverted.

[0082] To further illustrate the influence of pre-screening diversion on the increase of fine particle size after crushing, the particle size composition change before and after crushing under different pre-screening stages was counted, and the results are shown in Table 6.

[0083] Table 6 Change of particle size composition of coke powder (%)

[0084] Stage Less than 1 mm before crushing Less than 1 mm after crushing More than 5 mm after crushing Less than 1 mm increase Without pre-screening 40.17 49.44 9.85 9.27 Pre-screening stage 1 41.93 46.36 9.84 4.43 Pre-screening stage 2 41.69 44.99 9.92 3.30

[0085] To obtain the data in Table 6, in this embodiment, three operating stages of no pre-screening, pre-screening stage 1 and pre-screening stage 2 are selected respectively, and under the condition that the system is in a stable operating state, the material at the inlet end of the four-roll crusher 5 is taken as the pre-crushing sample, and the material at the outlet end of the four-roll crusher 5 is taken as the post-crushing sample. The sample is subjected to screening test and the particle size composition is counted; wherein, the less than 1mm before crushing and the less than 1mm after crushing are the mass percentage of the particle size less than 1mm in the corresponding sample, the more than 5mm after crushing is the mass percentage of the particle size greater than 5mm in the post-crushing sample, and the less than 1mm increase is the less than 1mm after crushing minus the less than 1mm before crushing, which is used to represent the increase of the fine particle size fraction caused by the crushing process.

[0086] As can be seen from Table 6, in the no pre-screening stage, the less than 1mm increase is 9.27; in the pre-screening stage 1 and the pre-screening stage 2, the less than 1mm increase is reduced to 4.43 and 3.30 respectively, which indicates that after setting the vibrating screen 2 for pre-screening and making the undersize bypassing the four-roll crusher 5 through the undersize bypass conveying branch 3, the particle size structure of the material entering the four-roll crusher 5 changes, and the increase of the fine particle size fraction caused by the crushing process is reduced, thereby being conducive to reducing the over-crushing trend. At the same time, the more than 5mm particle size fraction after crushing is maintained in the range of 9.84 to 9.92 under the three stages, which indicates that under the condition of the combination of the shunting and crushing in this embodiment, the large particle size control effect remains stable.

[0087] On the basis of the above particle size structure change, the production indexes under the conditions of no pre-screening and different pre-screening stages are statistically compared, and the results are shown in Table 7.

[0088] Table 7 Production index change

[0089] Stage Utilization coefficient (t / m²·h) Drum intensity (%) 5-10 mm particle size (%) Solid fuel consumption (kg / t) Without pre-screening 1.30 75.29 23.72 51.69 Pre-screening stage 1 1.41 74.69 23.85 50.88 Pre-screening stage 2 1.44 74.89 22.52 50.81 Average comparison 0.12 −0.50 −0.53 −0.84

[0090] To obtain the data in Table 7, in this embodiment, three operating stages of no pre-screening, pre-screening stage 1 and pre-screening stage 2 are selected respectively, and under the condition that the system is in a stable operating state, the system utilization coefficient, the drum strength, the 5mm to 10mm particle size fraction and the solid fuel consumption in the sintering production process are recorded, and the recorded results are summarized to form Table 7; wherein, the average comparison is the comprehensive comparison result of the pre-screening stage relative to the no pre-screening stage, which is used to represent the change trend of the production index under the pre-screening shunting condition.

[0091] From Table 7, it can be seen that, relative to the stage without pre-screening, the utilization coefficient of the stage with pre-screening is increased from 1.30 to 1.41 and 1.44, indicating that, in the embodiment, the pre-screening classification of the coke powder feedstock by the vibrating screen 2 and the bypassing of the undersize material through the undersize bypass conveying branch 3 after bypassing the four-roller crusher 5, the comprehensive utilization level of the production process is improved; at the same time, the solid fuel consumption is reduced from 51.69 to 50.88 and 50.81, with an average comparative reduction of 0.84, indicating that, under the condition of the particle size structure being adjusted, the solid fuel consumption per unit output is reduced. The drum strength and the proportion of the particle size fraction of 5mm to 10mm have a small change range in the statistical stage, indicating that, under the process and system configuration of the embodiment, the pre-screening diversion does not significantly reduce the drum strength at the expense of the improvement of the output and fuel consumption, thereby being more conducive to stable promotion and application on the sintering production line.

[0092] The above merely describes a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, within the technical range disclosed by the present application, according to the technical scheme and inventive concept of the present application, makes equivalent replacement or change, should be covered within the protection scope of the present application.

Claims

1. A pre-screening and grading process for coke powder in sintering production, characterized in that, Includes the following steps: S1: The coke powder used for sintering is conveyed to the vibrating screen via the feed conveyor belt; S2: The feeding coke powder is pre-screened and graded using the vibrating screen to obtain undersize material and oversize material, wherein the undersize material is coke powder with a particle size of less than 4 mm, and the oversize material is coke powder with a particle size of greater than or equal to 4 mm. S3: The undersize material is conveyed to the fuel finished product belt via the undersize bypass conveyor branch, bypassing the four-roll crusher; S4: The material over the screen is conveyed to the four-roll crusher through the screen conveyor branch for crushing to obtain the crushed product; S5: The crushed product is conveyed to the upstream discharge point of the fuel finished product conveyor belt, where the crushed product and the undersize material are merged.

2. The pre-screening and grading process for coke powder in sintering production according to claim 1, characterized in that: The screen surface of the vibrating screen is installed at an angle of 20° to 30°.

3. The pre-screening and grading process for coke powder in sintering production according to claim 1, characterized in that: The amplitude of the vibrating screen is 4mm to 6mm.

4. The pre-screening and grading process for coke powder in sintering production according to claim 1, characterized in that: The processing capacity of the vibrating screen is 40t / h to 60t / h.

5. The pre-screening and grading process for coke powder in sintering production according to claim 1, characterized in that: The vibrating screen uses a tensioned elastic screen mesh, which alternates between a tensioned state and a relaxed state during vibration.

6. The coke powder pre-screening and grading process for sintering production according to claim 5, characterized in that: The tension elastic screen has a multi-layer screen structure, with the screen aperture diameters from top to bottom being 4.1mm, 3.9mm, and 3.8mm respectively.

7. A coke powder pre-screening and grading system for a coke powder pre-screening and grading process in sintering production according to any one of claims 1-6, characterized in that: include: Feed conveyor belt is used to transport the feed coke powder; A vibrating screen, wherein the feed end of the vibrating screen is connected to the discharge end of the feed conveyor belt, the vibrating screen has an undersize outlet and an oversize outlet, used to classify the feed coke powder into undersize and oversize materials according to 4mm, wherein the undersize material is coke powder with a particle size of less than 4mm, and the oversize material is coke powder with a particle size of greater than or equal to 4mm. The undersize bypass conveying branch is connected at its inlet to the undersize outlet of the vibrating screen, and is used to convey the undersize material to the fuel finished product belt. The feed end of the feed conveyor branch is connected to the feed outlet of the vibrating screen; A four-roll crusher, wherein the feed end of the four-roll crusher is connected to the discharge end of the screen conveyor branch, is used to crush the screen material to obtain crushed products; The fuel finished product conveyor belt has its upstream discharge point connected to the discharge end of the undersize bypass conveyor branch and the discharge end of the four-roll crusher, respectively, for receiving the undersize material and the crushed product and forming a combined output.

8. The coke powder pre-screening and grading system according to claim 7, characterized in that: The material flow path of the undersize bypass conveyor branch does not pass through the feed end of the four-roll crusher, and the undersize material does not enter the four-roll crusher.

9. The coke powder pre-screening and grading system according to claim 7, characterized in that: The system also includes a dust removal pipeline, which is connected to the receiving area and the screening area of ​​the vibrating screen, and is used to extract dust-laden gas generated during the screening process.

10. The coke powder pre-screening and grading system according to claim 7, characterized in that: The system also includes an interlock control unit, which receives the operating status signal of the vibrating screen and outputs an interlock control signal when the vibrating screen stops. The interlock control signal is used to implement shutdown control and start prohibition control for the four-roll crusher respectively.

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