Drying control method for drum drying section of belt type roasting machine pellet production line

Abstract

The invention relates to the technical field of pellet production, and provides a drying control method for a drum drying section of a belt type roasting machine pellet production line, which comprises the following steps: detecting the temperature of flue gas in a first air bellow of a pumping drying section, taking the temperature as a control parameter and recording the temperature as the temperature of a point A; under the condition that the daily output, the oxidation end-point flue gas temperature and the roasting end-point flue gas temperature are fixed, multiple groups of A-point temperature data are collected, and the broken pellet rate, the compressive strength and the FeO content of finished pellets are correspondingly detected; according to a preset scoring rule, scores corresponding to the broken ball rate, the compressive strength and the FeO content respectively are calculated, comprehensive scores are calculated according to a preset weight, and the temperature of the point A corresponding to the highest comprehensive score serves as a reference value; and at least one of the inlet gas temperature, the total air volume and the proportion of the bypass air volume to the working air volume of the drum drying section is adjusted, so that the temperature of the point A is maintained within the allowable deviation range of the reference value, and closed-loop control over the drying effect of the drum drying section is achieved. According to the scheme, stable quality of finished pellets is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of pellet production, in particular to a drying control method of a drying section of a belt roaster pellet production line. Background Art

[0002] The belt roaster pellet production process utilizes integrated equipment to complete the drying, preheating, roasting, and cooling processes. The pellets maintain a static layered structure from feed to finished product, making them particularly suitable for the high-temperature roasting requirements of hematite and flux-based pellets. The drying section, the first stage of this process, draws hot air through the lower bellows into the middle and lower portion of the material bed, drying the green balls and increasing their strength. This supports the material bed pressure during the transition from air blowing to air extraction, ultimately improving the permeability of the material bed, reducing the crack rate of the pellets, and increasing the strength of the finished pellets.

[0003] The existing belt roaster pellet production process poses the risk of imbalanced system heat distribution. The total heat input to the first five process stages of the belt roaster (including the drying stage) is strictly capped. Excessive heat input to the drying stage will squeeze the heat quota of the subsequent oxidation preheating and roasting stages, impairing their functionality. Insufficient heat in the drying stage directly leads to inadequate drying, resulting in increased pellet fragmentation, deteriorating permeability, and reduced strength. Furthermore, there is the risk of inappropriate control parameter selection. For example, the temperature of the hood above the drying stage's wind box is used as the control parameter, which is easily affected by ambient temperature fluctuations and cannot reliably reflect the actual drying effect. Furthermore, there is a conflict between quality and process stability. Parameter distortion leads to uncontrolled heat input, which not only fails to guarantee drying quality in the drying stage but also disrupts the overall system heat balance. Summary of the Invention

[0004] In the existing belt roaster pellet production process, there are risks of imbalanced system heat distribution, improper control parameter selection, and conflicts between quality and process stability. The present disclosure provides a drying control method for the drum drying section of a belt roaster pellet production line, comprising: Step a: Detect the flue gas temperature in the first wind box of the extraction section and use it as a control parameter and record it as point A temperature; Step b, under the conditions of fixed daily output, oxidation endpoint flue gas temperature and roasting endpoint flue gas temperature, collecting multiple sets of data on the temperature of point A, and correspondingly detecting the ball breakage rate, compressive strength and FeO content of the finished pellets; Step c, calculating scores corresponding to the ball-breaking rate, the compressive strength, and the FeO content according to a preset scoring rule, and calculating a comprehensive score according to preset weights, with the point A temperature corresponding to the highest comprehensive score being used as a reference value; Step d: Adjust at least one of the inlet gas temperature, total air volume, and the ratio of bypass air volume to working air volume of the drying section so that the temperature at point A is maintained within the allowable deviation range of the reference value, thereby achieving closed-loop control of the drying effect of the drying section.

[0005] In some embodiments, the step c of calculating the scores corresponding to the broken ball rate, the compressive strength, and the FeO content according to a preset scoring rule includes: The score for the fragmented ball rate was calculated based on 10 points for a fragmented ball rate less than 10%, 7 points for a rate in the range of 10-15%, 4 points for a rate in the range of 15-20%, and 1 point for a rate greater than or equal to 20%; The compressive strength score is calculated based on a score of 1 for a compressive strength less than 1800N, 3 for a compressive strength between 1800-2000N, 6 for a compressive strength between 2000-2500N, and 10 for a compressive strength greater than or equal to 2500N. The FeO content score was calculated based on 5 points for FeO content less than 1.0%, 3 points for FeO content within the range of 1.0-2.0%, and 1 point for FeO content greater than or equal to 2.0%.

[0006] In some embodiments, the step c of calculating the comprehensive score according to the preset weights includes: The scores of the ball-breaking rate, the compressive strength, and the FeO content were weighted and calculated according to a weight ratio of 2:7:1 to obtain a comprehensive score.

[0007] In some embodiments, step d comprises: The inlet air temperature of the drying section is adjusted by adjusting the opening of the inlet cold air valve of the drying blower.

[0008] In some embodiments, step d further comprises: The total air volume of the drying section is adjusted by locking the opening of the bypass valve of the drying blower and adjusting the rotation speed of the drying blower.

[0009] In some embodiments, step d further comprises: The ratio of the bypass air volume to the working air volume of the drying section is adjusted by locking the rotation speed of the drying blower and adjusting the opening of the bypass valve.

[0010] In some embodiments, the step b of collecting multiple sets of data on the temperature of point A includes: According to the gradient change rule, the inlet gas temperature of the drum-dry section, the ratio of the total air volume and the bypass air volume to the working air volume are adjusted to collect multiple sets of data on the temperature of point A.

[0011] In some embodiments, the gradient change rule includes: Only adjust a single operating parameter at a time; In response to the stable operation time of the single operating parameter being adjusted for ≥30 minutes, the temperature at point A and the crushing rate, compressive strength and FeO content of the finished pellets are collected again; The temperature change of point A between two consecutive adjustments is ≥5°C.

[0012] In some embodiments, adjusting the inlet gas temperature, the total air volume, the ratio of the bypass air volume to the working air volume of the blower-dryer section includes: Adjusting the inlet gas temperature of the drying section to vary within the range of 200-350°C; Adjust the total air volume of the drying section to within ±15% of the standard air volume; Adjust the ratio of bypass air volume to working air volume within the range of 0.2-0.8.

[0013] In some embodiments, step d further comprises: In response to the temperature at point A continuously deviating from the allowable deviation range for more than 10 minutes, performing a gradient adjustment operation, including: In response to the first deviation, adjusting the inlet gas temperature of the drum-dry section; In response to the secondary deviation, the total air volume of the drying section is additionally adjusted; In response to the three deviations, synchronously adjusting the ratio of the bypass air volume to the working air volume; If the temperature at point A has not recovered to the allowable deviation range within 30 minutes, the parameter alarm program of the drum-drying section is triggered.

[0014] The aforementioned drying control method for the drying section of a belt roaster pellet production line achieves closed-loop control of the drying effect in the drying section, simultaneously ensuring stable quality of finished pellets and overall system heat balance. By establishing a complete control chain consisting of precise parameter selection, scientific benchmark calibration, and dynamic adjustment, it effectively addresses three major technical issues: imbalanced heat distribution, control parameter distortion, and quality-process conflicts. This significantly improves process stability and product quality in belt roaster pellet production. Specifically, selecting the temperature at point A of the first blower in the drying section as the control parameter effectively mitigates the problem of flue gas hood temperature fluctuations influenced by ambient temperature, ensuring that the parameter accurately reflects the heat input in the drying section and providing a stable basis for drying effect evaluation. Data collection under fixed daily production output, oxidation endpoint, and roasting endpoint flue gas temperatures effectively prevents the drying section from displacing heat from subsequent processes, thus mitigating process anomalies caused by heat distribution imbalance at the source. A comprehensive scoring mechanism based on the ball breakage rate, compressive strength, and FeO content quantifies the drying effect in the drying section, achieving synergistic optimization of drying effect and finished product quality. By adjusting the three parameters of inlet gas temperature, total air volume and bypass ratio, a multi-dimensional dynamic adjustment mechanism is constructed to ensure that the temperature of point A is stable in the optimal range, thereby achieving simultaneous improvement in drying quality and heat balance of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A flow chart of a drying control method for a drum drying section of a belt roaster pellet production line provided by one embodiment of the present invention; Figure 2 A schematic diagram of a belt roaster pellet production line provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following embodiments of the present disclosure are further described in detail with reference to the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present disclosure, but are not intended to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but rather includes all technical solutions within the scope of the claims.

[0018] The present disclosure provides these embodiments in order to make this disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values ​​set forth in these embodiments should be interpreted as merely exemplary, and not as limiting.

[0019] In addition, the terms "first," "second," and similar terms used in this disclosure do not denote any order, quantity, or importance, but are simply used to distinguish different parts. The terms "include," "comprise," and similar terms mean that the elements preceding the term include the elements listed after the term, and do not exclude the possibility of also including other elements.

[0020] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0021] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0022] It should be understood that the embodiments of the present invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in the present invention, it is readily apparent to those skilled in the art that various modifications are feasible without departing substantially from the teachings of the subject matter of the present invention. Accordingly, all such modifications should be included within the scope of the present invention. Without departing from the gist of the present invention, other replacements, modifications, variations, and deletions may be made to the design, operating conditions, and parameters of the following exemplary embodiments.

[0023] Please refer to Figure 1 , Figure 1 The flowchart of the drying control method of the drying section of the belt roaster pellet production line provided by one embodiment of the present invention is shown. The drying control method of the drying section of the belt roaster pellet production line shown in this embodiment includes: Step a: Detect the flue gas temperature in the first wind box of the extraction section and use it as a control parameter and record it as point A temperature; Step b, under the conditions of fixed daily output, oxidation endpoint flue gas temperature, and roasting endpoint flue gas temperature, collecting multiple sets of point A temperature data, and correspondingly testing the ball breakage rate, compressive strength, and FeO content of the finished pellets; Step c, calculating the scores corresponding to the broken ball rate, compressive strength, and FeO content according to the preset scoring rules, and calculating the comprehensive score according to the preset weights, with the point A temperature corresponding to the highest comprehensive score as the reference value; Step d: Adjust at least one of the inlet gas temperature, total air volume, and the ratio of bypass air volume to working air volume of the drying section to maintain the temperature at point A within the allowable deviation range of the reference value, thereby achieving closed-loop control of the drying effect of the drying section.

[0024] In a specific embodiment, in step a, Figure 2 As shown, the first bellows in the drying section is tested ( Figure 2 The flue gas temperature in the 3# windbox (in the middle) is used as the control parameter, recorded as the temperature at point A. This parameter can stably reflect the heat input effect of the drying section and avoid environmental interference.

[0025] In the above step a, the temperature of point A of the first air box in the extraction section is selected as the control parameter, which can effectively avoid the defect of "the hood temperature fluctuating due to interference from the ambient temperature", ensure that the parameter truly reflects the heat input effect of the drying section, and provide a stable basis for the evaluation of the drying effect.

[0026] In a specific embodiment, in step b, under the conditions of fixed daily output, oxidation endpoint flue gas temperature, and roasting endpoint flue gas temperature, the operating parameters of the drying and drying stage are adjusted to obtain multiple sets of point A temperature data; corresponding batches of finished pellets are collected, and their broken ball rate, compressive strength, and FeO content are tested; wherein the broken ball rate is calculated based on (number of broken balls ÷ total number of balls) × 100%; the compressive strength is tested based on the national standard GB / T14201; and the FeO content is tested based on the national standard GB / T6730.5.

[0027] More specifically, in step b, collecting multiple sets of point A temperature data includes: adjusting the inlet gas temperature of the blower section, the total air volume, and the ratio of the bypass air volume to the working air volume according to the gradient change rule to collect multiple sets of point A temperature data.

[0028] Among them, the gradient change rules include: only adjusting a single operating parameter each time; in response to the stable operation time of ≥30 minutes after the single operating parameter is adjusted, the temperature of point A and the crushing ball rate, compressive strength and FeO content of the finished pellets are collected again; the change in the temperature of point A between two adjacent adjustments is ≥5°C.

[0029] Among them, adjusting the inlet gas temperature, total air volume and the ratio of bypass air volume to the working air volume of the drying section include: adjusting the inlet gas temperature of the drying section to vary within the range of 200-350℃; adjusting the total air volume of the drying section to vary within ±15% of the standard air volume; and adjusting the ratio of bypass air volume to the working air volume to vary within the range of 0.2-0.8.

[0030] In step b above, data is collected under the conditions of fixed daily output, oxidation endpoint, and roasting endpoint flue gas temperature. This can effectively prevent the heat in the drying stage from crowding out the quota of subsequent processes, thus avoiding process anomalies caused by heat distribution imbalance from the source.

[0031] In a specific embodiment, in step c, the grading rules are set as follows: Fragmented ball rate: <10% is 10 points, 10-15% is 7 points, 15-20% is 4 points, ≥20% is 1 point; Compressive strength: <1800N gets 1 point, 1800-2000N gets 3 points, 2000-2500N gets 6 points, ≥2500N gets 10 points; FeO content: <1.0% gets 5 points, 1.0~2.0% gets 3 points, ≥2.0% gets 1 point.

[0032] Based on the above scoring rules, the scores corresponding to the broken ball rate, compressive strength and FeO content were calculated respectively.

[0033] The composite score is calculated using the following weightings: Comprehensive score Σ=(broken ball rate score × 2) + (compressive strength score × 7) + (FeO score × 1).

[0034] The temperature at point A corresponding to the highest comprehensive score is taken as the reference value M.

[0035] In a specific embodiment, the reference value M is determined based on the weighted sum of the scores corresponding to the actual values ​​of the ball crushing rate, compressive strength, and FeO content, and the drying reference temperature. The details are shown in Table 1: Table 1

[0036] As can be seen from Table 1, the highest comprehensive score is 87, which corresponds to a temperature of 190°C. Therefore, the reference value M of the temperature at point A is 190°C.

[0037] In the above step c, the drying effect of the drum drying stage is quantified through a comprehensive scoring mechanism of the broken ball rate, compressive strength and FeO content, thereby achieving synergistic optimization of the drying effect and the quality of the finished product.

[0038] In a specific embodiment, in step d, the temperature at point A is maintained within an allowable deviation range of the reference value M, for example, ±10° C., by adjusting at least one of the following parameters: As a specific embodiment, the inlet air temperature of the drying section is adjusted by controlling the opening of the cold air valve at the drying blower inlet. Increasing the opening increases the proportion of cold air mixed in, lowering the inlet air temperature and reducing heat input. Decreasing the opening decreases the proportion of cold air mixed in, raising the inlet air temperature and increasing heat input.

[0039] As a specific embodiment, the total air volume in the drying section is adjusted by fixing the bypass valve opening and adjusting the drying blower speed. Increasing the speed increases the total air volume, and the amount of hot air entering the belt roaster through the 1# and 2# bellows increases simultaneously. Decreasing the speed decreases the total air volume, and the amount of hot air passing through the 1# and 2# bellows decreases accordingly.

[0040] As a specific embodiment, the ratio of bypass airflow to working airflow in the blower section is adjusted by fixing the blower blower speed and adjusting the bypass valve opening. Increasing the bypass valve opening increases the bypass airflow ratio, reducing the working airflow ratio entering the 1# and 2# blowers. Decreasing the bypass valve opening decreases the bypass airflow ratio, increasing the working airflow ratio entering the 1# and 2# blowers.

[0041] In one specific embodiment, for example, when the temperature at point A falls below M-10°C, the following actions can be performed simultaneously: reducing the cold air valve opening to increase the inlet air temperature; increasing the blower speed to increase the total air volume; and reducing the bypass valve opening to increase the proportion of working air volume entering the 1# and 2# air boxes. These actions synergistically increase the effective heat input to the blower section, allowing the temperature at point A to quickly return to the target range.

[0042] According to several embodiments of the present invention, step d also includes: in response to the temperature at point A continuously deviating from the allowable deviation range for more than 10 minutes, performing a gradient adjustment operation, including: for the first deviation, adjusting the inlet gas temperature of the drum-dry section; for the second deviation, additionally adjusting the total air volume of the drum-dry section; for the third deviation, synchronously adjusting the ratio of the bypass air volume to the working air volume; if the temperature at point A has not returned to the allowable deviation range for more than 30 minutes, triggering a parameter alarm program for the drum-dry section.

[0043] In step d above, by adjusting the three parameters of inlet gas temperature, total air volume and bypass ratio, a multi-dimensional dynamic adjustment mechanism is constructed to ensure that the temperature of point A is stable in the optimal range, thereby achieving simultaneous improvement in drying quality and heat balance of the entire system.

[0044] The aforementioned drying control method for the drying section of a belt roaster pellet production line achieves closed-loop control of the drying effect in the drying section, simultaneously ensuring stable quality of finished pellets and thermal balance across the entire system. By establishing a complete control chain consisting of precise parameter selection, scientific benchmark calibration, and dynamic adjustment, it effectively addresses three major technical issues: unbalanced system heat distribution, distorted control parameters, and quality-process conflicts. This significantly improves the process stability and product quality of belt roaster pellet production.

[0045] In some embodiments, the above-mentioned dynamic control step (step d) can be executed in conjunction with the process status: when the flue gas temperature in the oxidation section is lower than the set value, the ratio of the bypass air volume to the working air volume is adjusted first; when the flue gas temperature in the roasting section is lower than the set value, the total air volume in the drying section is adjusted first; when the temperature fluctuation of the smoke hood in the drying section exceeds the limit, the inlet gas temperature is adjusted first.

[0046] As a feasible implementation, companies can adjust technical details based on raw material conditions and quality requirements. Specifically, scoring thresholds can be adjusted, and the scoring ranges for ball crushing rate, compressive strength, or FeO content can be fine-tuned based on raw material composition. Weighting ratios can also be adjusted: the weight ratios of ball crushing rate, compressive strength, and FeO can be optimized within the range of (1-3): (6-8): (0.5-1.5). The allowable deviation range can be determined based on the production line's thermal balance characteristics, within a range of ±5-15°C of the baseline value M.

[0047] This solution, by selecting the anti-interference point A temperature parameter, determining the scientific benchmark value under the system thermal boundary constraint, and building a multi-dimensional adjustment mechanism, simultaneously achieves: optimization of the drying effect in the drying stage, namely, reduction of the broken ball rate and improvement of the compressive strength; guarantee of the heat balance of the entire system to avoid crowding out the heat quota of the oxidation / roasting stage; and improvement of process stability and improvement of the parameter control accuracy under environmental fluctuations.

[0048] Thus far, various embodiments of the present disclosure have been described in detail. To avoid obscuring the concept of the present disclosure, some details known in the art have not been described. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

[0049] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. In particular, as long as there are no structural conflicts, the various technical features mentioned in the various embodiments may be combined in any manner.

Claims

1. A drying control method for the drying section of a belt roaster pellet production line, characterized in that: include: Step a: Detect the flue gas temperature in the first wind box of the extraction section and use it as a control parameter and record it as point A temperature; Step b, under the conditions of fixed daily output, oxidation endpoint flue gas temperature and roasting endpoint flue gas temperature, collecting multiple sets of data on the temperature of point A, and correspondingly detecting the ball breakage rate, compressive strength and FeO content of the finished pellets; Step c, calculating scores corresponding to the ball-breaking rate, the compressive strength, and the FeO content according to a preset scoring rule, and calculating a comprehensive score according to preset weights, with the point A temperature corresponding to the highest comprehensive score being used as a reference value; Step d: Adjust at least one of the inlet gas temperature, total air volume, and the ratio of bypass air volume to working air volume of the drying section so that the temperature at point A is maintained within the allowable deviation range of the reference value, thereby achieving closed-loop control of the drying effect of the drying section.

2. The drying control method according to claim 1, characterized in that: The step c of calculating scores corresponding to the broken ball rate, the compressive strength, and the FeO content according to a preset scoring rule includes: The score for the fragmented ball rate was calculated based on 10 points for a fragmented ball rate less than 10%, 7 points for a rate in the range of 10-15%, 4 points for a rate in the range of 15-20%, and 1 point for a rate greater than or equal to 20%; The compressive strength score is calculated based on a score of 1 for a compressive strength less than 1800N, 3 for a compressive strength between 1800-2000N, 6 for a compressive strength between 2000-2500N, and 10 for a compressive strength greater than or equal to 2500N. The FeO content score was calculated based on 5 points for FeO content less than 1.0%, 3 points for FeO content within the range of 1.0-2.0%, and 1 point for FeO content greater than or equal to 2.0%.

3. The drying control method according to claim 2, characterized in that: Calculating the comprehensive score according to the preset weights in step c includes: The scores of the ball-breaking rate, the compressive strength, and the FeO content were weighted and calculated according to a weight ratio of 2:7:1 to obtain a comprehensive score.

4. The drying control method according to claim 1, characterized in that: The step d comprises: The inlet air temperature of the drying section is adjusted by adjusting the opening of the inlet cold air valve of the drying blower.

5. The drying control method according to claim 4, characterized in that: The step d further comprises: The total air volume of the drying section is adjusted by locking the opening of the bypass valve of the drying blower and adjusting the rotation speed of the drying blower.

6. The drying control method according to claim 5, characterized in that: The step d further comprises: The ratio of the bypass air volume to the working air volume of the drying section is adjusted by locking the rotation speed of the drying blower and adjusting the opening of the bypass valve.

7. The drying control method according to claim 6, characterized in that: The step b of collecting multiple sets of data on the temperature of point A includes: According to the gradient change rule, the inlet gas temperature of the drum-dry section, the ratio of the total air volume and the bypass air volume to the working air volume are adjusted to collect multiple sets of data on the temperature of point A.

8. The drying control method according to claim 7, characterized in that: The gradient change rules include: Only adjust a single operating parameter at a time; In response to the stable operation time of the single operating parameter being adjusted for ≥30 minutes, the temperature at point A and the crushing rate, compressive strength and FeO content of the finished pellets are collected again; The temperature change of point A between two consecutive adjustments is ≥5°C.

9. The control method according to claim 8, characterized in that: The step of adjusting the inlet gas temperature, the total air volume, the ratio of the bypass air volume to the working air volume of the blower-dryer section includes: Adjusting the inlet gas temperature of the drying section to vary within the range of 200-350°C; Adjust the total air volume of the drying section to within ±15% of the standard air volume; Adjust the ratio of bypass air volume to working air volume within the range of 0.2-0.

8.

10. The drying control method according to claim 1, characterized in that: The step d further comprises: In response to the temperature at point A continuously deviating from the allowable deviation range for more than 10 minutes, performing a gradient adjustment operation, including: In response to the first deviation, adjusting the inlet gas temperature of the drum-dry section; In response to the secondary deviation, the total air volume of the drying section is additionally adjusted; In response to the three deviations, synchronously adjusting the ratio of the bypass air volume to the working air volume; If the temperature at point A has not recovered to the allowable deviation range within 30 minutes, the parameter alarm program of the drum-drying section is triggered.

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