Process for graded utilization of high-water-content coal after drying and upgrading

Abstract

The invention discloses a process for graded utilization of high-water-content coal after drying and upgrading. High-water-content coal to be upgraded is dewatered and upgraded by adopting a steam drying and dewatering technology, and is further upgraded and graded through vibration grading drying, and an online detection system is adopted for real-time regulation and control in the process. Due to different dehydration effects of products with different granularities, different products are subjected to differentiation treatment after grading, and quality-improved products with different granularities can be reasonably utilized. According to the invention, the product subjected to steam drying and dewatering is quickly subjected to vibration classification dewatering, the purpose of loosening a material group is achieved in the process, and the contact area of the upgraded coal and air is increased, so that the upgraded coal still having waste heat can continue to perform secondary evaporation on residual moisture through preheating, and the overall dewatering rate of the upgraded coal is improved. According to the invention, the fine fraction product subjected to vibration classification drying is subjected to extrusion compression molding to obtain a briquette product, the unmolded pulverized coal is obtained through secondary screening, and the pulverized coal is continuously and repeatedly extruded, so that the utilization rate of the pulverized coal is improved.

Description

Technical Field

[0001] The invention relates to the field of comprehensive utilization of coal, and in particular to a process for graded utilization of high-water-content coal after drying and upgrading. Background Art

[0002] As the main energy source in my country, clean and efficient utilization of coal has always been the key research direction of the coal industry. Improving the quality of coal is one of the important ways to utilize coal in a clean and efficient manner. Improving the quality of coal is one of the important ways to utilize coal in a clean and efficient manner. Improving the quality of coal is mainly achieved by reducing the moisture and impurities in coal and increasing its calorific value.

[0003] In order to solve the problem of high moisture content of low-rank coal and easy overheating and runaway during the drying process, the method of direct steam drying is used to dehydrate low-rank coal. High-pressure steam drying has been widely used in wood fiber raw material processing, feed processing, and edible grain pretreatment. It has also been initially applied in the domestic coal drying and dehydration quality improvement industry. Since drying and dehydration cause a certain degree of damage to the physical structure of coal, the brittleness of the upgraded product coal increases, the average particle size of the material group decreases, and a certain amount of small-particle pulverized coal is produced. At the same time, there are differences in the dehydration effect of steam drying and dehydration on lump coal and pulverized coal. Due to the different drying principles of traditional hot air and low-temperature steam direct drying, there are also differences in the moisture content of coal of different particle sizes after dehydration. In the traditional drying method, the smaller the particle size, the higher the drying rate, and the moisture content of pulverized coal products is usually lower than that of lump coal products. However, steam drying and dehydration technology uses hot steam as a medium to directly contact coal. The moisture content of pulverized coal after dehydration is higher than that of lump coal. Therefore, it is necessary to further improve the quality of pulverized coal separately to meet user requirements. After steam drying, the material still has a certain temperature. Generally, direct storage is not conducive to further evaporation of water. In addition, the moisture content of fine coal particles after steam drying is often higher than that of coarse particles, because steam heating of fine particles will cause water condensation, and the dehydrated pulverized coal is difficult to use. At the same time, there is a significant difference in the moisture content of coarse and fine particles after drying, resulting in uneven moisture content of the product, so the coal after steam drying needs to be graded and graded. In addition, during the transportation, storage and distribution of the upgraded coal products, the increase in pulverized coal will cause dust pollution, while reducing the overall quality of the product coal and increasing ineffective transportation. Pulverized coal has always been a common problem faced by many coal-related companies due to its low calorific value and the restrictions of environmental protection and resource conservation. Therefore, the technology of grading and grading lump coal and pulverized coal and its clean and efficient utilization needs to be developed urgently.

[0004] At the same time, after the installation of the traditional grading screen, the mesh size and the inclination angle of the screen surface are fixed, and cannot be adjusted autonomously according to the changes in the material properties, resulting in the inability to meet the diverse grading needs. When the moisture content of the material is high during the grading process, the screening effect of the sticky and wet particles is poor, and the agglomeration and adhesion of the sticky and wet particles will reduce the grading effect. Usually, the mesh size is enlarged to ensure the screening effect of fine particles. For example, the 3mm screening of highly sticky and wet materials usually enlarges the mesh to about 6mm. When the moisture content of the material changes, the screen surface needs to be replaced to adjust the mesh size, which cannot be adjusted in real time, reducing production efficiency. Summary of the invention

[0005] In view of the common problems of high cost, poor drying effect, low safety, easy reabsorption after dehydration, poor dehydration effect and difficulty in utilization of fine-particle coal in the above-mentioned background technology, the present invention provides a process for graded utilization of high-water-content coal after drying and upgrading. In view of the difficulty in utilizing the residual heat of materials after steam drying, vibration energy is introduced to enhance the looseness of particles, which not only achieves further drying of the material, but also realizes the graded and quality-based utilization of the material.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A high-water-content coal drying and upgrading and subsequent graded utilization process comprises the following steps:

[0008] The high-water content coal to be upgraded is transported to the steam drying and dehydration system for steam drying and dehydration, and the dehydrated upgraded coal is transported to the vibration grading drying system for vibration grading drying. The steam drying and vibration grading drying parameters are controlled in real time by the online detection system;

[0009] After vibration grading and drying, the material above the sieve is lump coal, and the material below the sieve is pulverized coal. The lump coal is transported to the lump coal bin for direct distribution, and the pulverized coal is extruded and compressed. The compressed product is screened and graded, and the material above the sieve is shaped coal, and the material below the sieve is pulverized coal. The shaped coal is transported to the shaped coal bin for direct distribution, and the pulverized coal is returned for extrusion and compression.

[0010] Furthermore, the steam drying and dehydration system includes a heat source module, a drying and dehydration module, and a waste steam recovery module. The heat source module transports steam as a heat medium to the dehydration device, and then the steam is released to obtain the upgraded coal. The waste steam enters the waste steam recovery device for condensation, and the condensed wastewater enters the wastewater treatment device for purification.

[0011] Furthermore, the total moisture content of the upgraded coal with a diameter of more than 6 mm is ≤20wt%, and the total moisture content of the upgraded coal with a diameter of less than 6 mm is ≤30wt%.

[0012] Furthermore, the vibration grading and drying system includes an excitation module, an intelligent grading module, and a material conveying module. The excitation module enhances the loosening of particles by introducing vibration energy, which not only achieves further drying of the material, but also realizes the grading and quality-based utilization of the material. The system is connected to the steam drying system and the briquette system through the material conveying module.

[0013] Furthermore, the vibration grading drying system adjusts the sieve aperture by overlapping or cross-displacing two 6 mm sieve surfaces placed up and down, with an adjustment range of 3-6 mm, and the inclination angle is adjusted by a hydraulic device, with an adjustment range of 5-15°.

[0014] Furthermore, the steam drying system monitors and transmits product moisture content data in real time through an online moisture detector, and adjusts the temperature and time of the dehydration equipment in real time according to the coal quality characteristics of the input raw coal and user product requirements. The temperature range is 100-200°C and the time range is 0-60min.

[0015] Furthermore, the finished shape of the briquette product is spherical, angular, square, etc.

[0016] Furthermore, the screening particle size of the shaped coal product is 3 mm, and the screened material after classification is unextruded and unformed pulverized coal, and the pulverized coal is returned to the double-roll extrusion molding device through a conveying device for secondary extrusion and compression.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention adopts steam drying and dehydration technology to dehydrate and improve the quality of high-water-content coal. This technology can use steam heating to reduce the risk of coal fire and realize the evaporation of water in the coal to achieve the purpose of dehydration.

[0019] 2. The steam drying and dehydration process of the present invention utilizes the rapidly released steam energy to have a certain deagglomeration and loosening effect on small-particle agglomerated materials with high water content, which is helpful for further evaporation of water and subsequent classification operations.

[0020] 3. The present invention rapidly performs vibration classification dehydration on the product after steam drying and dehydration, and in the process achieves the purpose of loosening the material group, increases the contact area between the upgraded coal and the air, increases the heat dissipation space of the material group, and enables the upgraded coal with residual heat to continue to evaporate the residual water for a second time through preheating, thereby improving the overall dehydration rate of the upgraded coal.

[0021] 4. The present invention separates the pulverized coal and the upgraded lump coal generated in the steam drying and dehydration process through vibration classification dehydration, thereby improving the quality of the upgraded lump coal and avoiding ineffective storage and transportation of the product coal.

[0022] 5. The online detection system of the present invention is equipped with sensing devices such as an online particle size detector and an online moisture detector. It can automatically adjust working parameters such as steam dehydration pressure and time by real-time monitoring of the agglomeration, particle size and moisture content of the product in combination with the difference in coal quality of different coal raw materials and user demand for products. It can also adjust working parameters such as the sieve hole size and screen surface inclination of the vibration grading drying system, eliminating the limitations of low screening efficiency and poor adaptability of traditional equipment, and improving the flexibility, intelligence and screening efficiency of operation.

[0023] 6. The present invention extrude and compress the fine-grained product obtained by vibration classification and drying to obtain a shaped coal product, and obtains unshaped pulverized coal through secondary screening, and continues to extrude the pulverized coal repeatedly, thereby improving the utilization rate of the pulverized coal. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the process for graded utilization of high-water content coal after drying and upgrading. DETAILED DESCRIPTION

[0025] like Figure 1 As shown, the present invention provides a high-water content coal drying and upgrading and subsequent graded utilization process, comprising the following steps:

[0026] Steam drying and dehydration technology is used to dehydrate and improve the quality of the coal, and vibration graded drying is used to further improve the quality and grade the coal. An online detection system is used for real-time control during the process.

[0027] The upgraded coal is graded and utilized to obtain two products: low-water lump coal and high-water pulverized coal. The dehydrated lump coal is directly output as a product, and the moisture contained in the pulverized coal helps in subsequent compression molding. The dehydrated lump coal is transported to the lump coal bin by a belt conveyor. The pulverized coal is compressed into shaped coal by a double-roll extrusion molding device, and the shaped coal is screened by a classifier. The shaped coal on the screen is transported to the lump coal bin by a belt conveyor, and the unshaped pulverized coal is recovered and repeatedly compressed until it is formed.

[0028] The online detection system collects and analyzes the information of dehydrated product particle size, agglomeration degree, moisture content, etc. in real time through sensing devices such as online particle size detector and online moisture detector. It can also adjust the working parameters of the vibration grading drying system such as screen surface inclination and screen hole size in real time according to process needs and product requirements, and can also adjust the working parameters of the steam drying system such as pressure and time.

[0029] The system determines the sieve hole diameter through real-time monitoring and transmission of a large amount of data. The input variables are the moisture content M of the particles, the particle size d, and the screening process parameters (such as screening time t, sieve vibration frequency f, sieve hole shape φ, etc.). In the case of particle agglomeration, the effective particle size D' of the particles usually increases with the increase of moisture content, and the sieve hole size needs to be enlarged. The moisture content is positively correlated with the effective diameter. The preliminary empirical formula can be expressed as D'=D 0 (1+kM),

[0030] in:

[0031] D 0 : sieve size under dry conditions;

[0032] k: empirical coefficient, related to the agglomeration characteristics of the particles and the screening conditions;

[0033] M: Particle moisture content.

[0034] A neural network model is used to predict the relationship between moisture content and sieve size. The input data is normalized and divided into training, validation, and test sets. The input layer contains features such as moisture content, the hidden layer uses the ReLU activation function, and the output layer uses a linear activation function to predict the sieve size. The mean square error is selected as the loss function, and the Adam optimizer is used for training. The mean square error (MSE) and mean absolute error (MAE) are calculated to evaluate the prediction accuracy of the model. The final model is:

[0035] k = f(M, d, t, f, φ);

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] In this embodiment, the raw coal has a moisture content of 28wt% (total moisture), and the raw coal is dehydrated and upgraded by steam drying and dehydration technology to obtain upgraded coal, and the upgraded coal is subjected to vibration graded drying. During the process, an online detection system is used to adjust the steam drying and vibration graded drying parameters in real time to ensure product quality and process stability. During the steam drying stage, the online moisture detector collects the moisture content of the upgraded coal in real time, and the control system automatically adjusts the steam drying temperature and time according to the real-time monitoring data, the physical and chemical properties of the raw coal and the set product coal moisture requirements. The control system sets the temperature range to 100-200℃ and the drying time range to 0-60 minutes. After dehydration, the upgraded coal enters the vibration graded drying system, and the particle size and agglomeration are monitored in real time by the online particle size detector, and the moisture content is monitored by the online moisture detector. According to the real-time detection data, the screen surface inclination of the screening system is adjusted between 5-15°, and the screen hole size range is 3-6mm. The model k=f(M, d, t, f, φ) is used to dynamically adjust the screen hole size. The model calculates the parameters such as moisture content (M), particle size (d), vibration classification time (t), screening frequency (f) and mesh shape (φ) in the real-time detection data to optimize the screening conditions. When the moisture content of the target pulverized coal product is 22wt%, the particle size is about 3mm, the mesh shape is square, the screening time is set to 5 minutes, and the screening frequency is 50Hz, the model calculates the empirical parameter to be 2.48. By the formula D'=D 0 (1+kM) calculates the effective sieve hole size to be 4.64mm, that is, the sieve hole size should be adjusted to about 4.64mm to ensure the best screening effect. During the vibration classification process, the excitation system dynamically adjusts the vibration frequency according to the detection data to ensure that the moisture content of the fine coal particles is reduced to the process requirements. Finally, two products, lump coal and pulverized coal, are obtained. The moisture content of the lump coal product after dehydration is 10wt%, and the moisture content of the pulverized coal product is 22wt%. The moisture contained in the pulverized coal helps the subsequent compression molding. The dehydrated lump coal is transported to the lump coal bin by a belt conveyor. The pulverized coal is compressed into spherical coal by a double-roll extrusion molding device, and the coal is screened twice by a classifier. The above-screen coal is transported to the lump coal bin by a belt conveyor to recover the unformed pulverized coal and compress it repeatedly until it is formed.

[0039] Example 2

[0040] In this embodiment, the raw coal has a moisture content of 36wt% (total moisture), and the raw coal is dehydrated and upgraded by steam drying and dehydration technology to obtain upgraded coal, and the upgraded coal is subjected to vibration grade drying. During the process, an online detection system is used to adjust the steam drying and vibration grade drying parameters in real time to ensure product quality and process stability. During the steam drying stage, the online moisture detector collects the moisture content of the upgraded coal in real time, and the control system automatically adjusts the steam drying temperature and time according to the real-time monitoring data, the physical and chemical properties of the raw coal and the set product coal moisture requirements. The control system sets the temperature range to 100-200℃ and the drying time range to 0-60 minutes. After dehydration, the upgraded coal enters the vibration grade drying system, and the particle size and agglomeration are monitored in real time by the online particle size detector, and the moisture content is monitored by the online moisture detector. According to the real-time detection data, the screen surface inclination of the screening system is adjusted between 5-15°, and the screen hole size range is 3-6mm. The model k=f(M, d, t, f, φ) is used to dynamically adjust the screen hole size. The model calculates the parameters such as moisture content (M), particle size (d), vibration classification time (t), screening frequency (f) and mesh shape (φ) in the real-time detection data to optimize the screening conditions. When the moisture content of the target pulverized coal product is 25wt%, the particle size is about 4mm, the mesh shape is square, the screening time is set to 6 minutes, and the screening frequency is 60Hz, the model calculates the empirical parameter to be 1.56. By the formula D'=D 0 (1+kM) calculates the effective sieve size to be 5.56mm, that is, the sieve size should be adjusted to about 5.56mm to ensure the best screening effect. During the vibration classification process, the excitation system dynamically adjusts the vibration frequency according to the detection data to ensure that the moisture content of the fine coal particles is reduced to the process requirements. Finally, two products, lump coal and pulverized coal, are obtained. The moisture content of the lump coal product after dehydration is 13wt%, and the moisture content of the pulverized coal product is 25wt%. The moisture contained in the pulverized coal helps the subsequent compression molding. The dehydrated lump coal is transported to the lump coal bin by a belt conveyor. The pulverized coal is compressed into ridged coal by a double-roll extrusion molding device, and the coal is screened twice by a classifier. The sieve-surface coal is transported to the lump coal bin by a belt conveyor to recover the unformed pulverized coal and compress it repeatedly until it is formed.

[0041] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A process for graded utilization of high-water-content coal after drying and upgrading, characterized in that: The following steps are involved: The high-water content coal to be upgraded is transported to the steam drying and dehydration system for steam drying and dehydration, and the dehydrated upgraded coal is transported to the vibration grading drying system for vibration grading drying. The steam drying and vibration grading drying parameters are controlled in real time by the online detection system; After vibration grading and drying, the material above the sieve is lump coal, and the material below the sieve is pulverized coal. The lump coal is transported to the lump coal bin for direct distribution, and the pulverized coal is extruded and compressed. The compressed product is screened and graded, and the material above the sieve is shaped coal, and the material below the sieve is pulverized coal. The shaped coal is transported to the shaped coal bin for direct distribution, and the pulverized coal is returned for extrusion and compression.

2. A high-water-content coal drying and upgrading and classification utilization process according to claim 1, characterized in that: The steam drying and dehydration system includes a heat source module, a drying and dehydration module, and a waste steam recovery module. The heat source module transports steam as a heat medium to a dehydration device, and then releases the steam to obtain the upgraded coal. The waste steam enters the waste steam recovery device for condensation, and the condensed wastewater enters the wastewater treatment device for purification.

3. A high-water-content coal drying and upgrading and classification utilization process according to claim 1, characterized in that: The total moisture content of the upgraded coal with a thickness of more than 6 mm is ≤20wt%, and the total moisture content of the upgraded coal with a thickness of less than 6 mm is ≤30wt%.

4. The process for classifying and utilizing high-water-content coal after drying and upgrading according to claim 1, characterized in that: The vibration grading and drying system includes an excitation module, an intelligent grading module, and a material conveying module. The excitation module strengthens the loosening of particles by introducing vibration energy, which not only achieves further drying of the material, but also realizes the grading and quality-based utilization of the material. The system is connected to the steam drying system and the briquette system through the material conveying module.

5. The process for classifying and utilizing high-water-content coal after drying and upgrading according to claim 1, characterized in that: The vibration grading drying system adjusts the sieve holes by overlapping or cross-displacing two 6mm sieve surfaces placed up and down, with an adjustment range of 3-6mm, and the inclination angle is adjusted by a hydraulic device, with an adjustment range of 5-15°.

6. The process for classifying and utilizing high-water-content coal after drying and upgrading according to claim 1, characterized in that: The steam drying system monitors and transmits product moisture content data in real time through an online moisture detector, and adjusts the temperature and time of the dehydration equipment in real time according to the coal quality characteristics of the raw coal and user product requirements. The temperature range is 100-200°C and the time range is 0-60min.

7. The process for classifying and utilizing high-water-content coal after drying and upgrading according to claim 1, characterized in that: The finished shape of the shaped coal product is one of spherical, prismatic and square.

8. The process for classifying and utilizing high-water-content coal after drying and upgrading according to claim 1, characterized in that: The screening particle size of the shaped coal product is 3 mm, and the screened material after classification is unextruded and unformed pulverized coal. The pulverized coal is returned to the double-roll extrusion molding device through a conveying device for secondary extrusion and compression.

Images