A double-shaft throwing system and double-shaft drying equipment for hot air drying of coal chemical fine slag

Abstract

This utility model discloses a biaxial spreading system and biaxial drying equipment for hot air drying of fine coal chemical slag. It solves the technical problems of existing equipment, such as large blade arrangement angles, large spacing, low shaft speed, uneven heat distribution, insufficient material mixing, severe wear, easy water and steam leakage, and low thermal efficiency. The shaft speed is 70~400 rpm, the blade deflection angle perpendicular to the shaft is 5°~30°, the blade cross-sectional thickness is 10~30mm, the blade spacing along the shaft is 30~80mm, the blades are fixed to the shaft by bearing bushes, and the housing is arranged in upper and lower layers. This device can improve thermal efficiency, reduce energy consumption, facilitate blade maintenance, and reduce equipment space occupation.

Description

Technical Field

[0001] This utility model relates to the field of solid waste treatment technology in the coal chemical and thermal power industries, and in particular to an energy-saving drying device for fine slag with high moisture content. It achieves efficient drying of fine slag by mixing it with hot air through high-speed dual-shaft rotation, reducing energy consumption and avoiding secondary pollution of the surrounding environment. Background Technology

[0002] Characteristics of fine slag in the coal chemical industry: High moisture content (45-70%), in the form of cakes or mud paste, with high specific gravity and poor fluidity. The fine slag contains about 30% unburned residual carbon, with a calorific value of 1500-3000 Kcal / kg. Direct disposal results in resource waste. In a high-moisture state, the fine slag easily pollutes the soil and groundwater. The moisture content must be reduced to below 20% before it can be utilized as a resource.

[0003] Existing drying technologies have the following drawbacks: 1. Fluidized bed dryers and vibrating dryers are prone to clogging due to the high viscosity and density of fine residues, making fluidized bed drying impossible. Vibrating dryers also suffer from high energy consumption because the high viscosity of fine residues prevents material from vibrating properly and causes it to accumulate. 2. Pulverized coal combustion dryers have low thermal efficiency (≤50%), require a large floor space, and incur high exhaust gas treatment costs. 3. Centrifugal drum dryers are poorly adapted to high-moisture fine residues and cannot meet drying requirements. 4. Single-shaft or dual-shaft agitated dryers have large blade angles (above 35°), large spacing, and low shaft speeds (below 60 rpm), resulting in uneven heat distribution, insufficient material mixing, severe wear, and easy leakage of water and steam.

[0004] There is an urgent need to develop a high-efficiency and energy-saving drying equipment that fully utilizes the calorific value of residual carbon in fine slag to reduce drying energy consumption. This equipment should solve the problems of high-moisture fine slag agglomeration and uneven distribution, improve the energy exchange efficiency between hot air and materials, and allow for long-term continuous operation. It should also enable exhaust gas purification and water recycling, avoiding secondary pollution of the surrounding environment. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency hot air dual-shaft drying device that reduces drying energy consumption, solves the problems of high-moisture fine residue adhesion and uneven spreading, improves the energy exchange efficiency of hot air contact with materials, and enables convenient maintenance of the blades.

[0006] The technical solution of this utility model is as follows:

[0007] It includes a drying chamber, which is a horizontal design and is arranged in two layers, namely an upper chamber and a lower chamber.

[0008] Preferably, the inner lining material of the drying chamber is a wear-resistant ceramic material, and the chamber also includes a heat insulation layer with a temperature resistance of ≥400°C.

[0009] Preferably, both the upper and lower drying chambers are equipped with a dual-axis spreading system. The dual-axis spreading system specifically includes two parallel shafts, which are horizontally arranged and can rotate in both directions. The two shafts rotate in both directions simultaneously to make the material rise up and collide with each other, so that the material is fully mixed with the hot air and the material is propelled forward.

[0010] Preferably, the shaft rotation speed is 70~400 rpm. Below 70 rpm, the material cannot be thrown up and dispersed. When the rotation speed is too high, exceeding 400 rpm, the material moves too quickly, resulting in short contact time between the material and the hot air, reducing the drying effect. The ideal and preferred rotation speed is in the range of 150~300 rpm. The paddles, mounted on the shaft, are arranged in a staggered design on two parallel shafts. The vertical deflection angle between the paddles and the shaft is in the range of 5°~30°. When the vertical deflection angle is less than 5°, the paddles are almost parallel to the vertical direction of the shaft, resulting in slow material movement and insufficient output. When the angle is greater than 30°, the material moves too quickly, resulting in short contact time between the material and the hot air, reducing the drying effect, and simultaneously increasing resistance and energy consumption.

[0011] Preferably, the shaft is a hollow shaft.

[0012] Preferably, the blades are spaced 30-80mm apart along the shaft. This spacing refers to the distance from the right end of the left blade to the left end of the right blade between two adjacent blades. Longitudinally, multiple blades are welded to the bearing shell or shaft at regular intervals. Preferably, two bearing shells are joined and fixed to the shaft using connecting flanges. It is not recommended to directly fix the blades to a hollow shaft, as the long shaft spacing leads to uneven heating and deformation during welding, resulting in low concentricity and unstable operation. This blade arrangement serves to cut, break up, and scatter the material clumps, ensuring thorough mixing and contact between the material and hot air, thus improving thermal efficiency and achieving a drying effect.

[0013] Preferably, multiple rows of blades are arranged along the horizontal direction of the axis, with adjacent blades arranged side by side parallel to each other.

[0014] The design of the paddles is related to the output of the drying equipment and the material travel speed. Preferably, the paddle cross-section thickness is 10~30mm. If the paddle cross-section is small, the amount of material thrown is small and the output is insufficient. If the paddle cross-section is too large, the resistance is high, the material travel speed is high, and the drying effect is reduced.

[0015] Preferably, the blades are made of high wear-resistant alloy steel, and each blade is fan-shaped. Specifically, 360 degrees is divided into eight equal parts, which are the central angles of a single fan-shaped blade. Then, according to the actual required deflection angle, four blades are evenly spiraled around the outer circumference of the shaft. Here, "evenly spiraled around" means that the connection positions of the four blades and the shaft form a spiral line.

[0016] Preferably, the bearing shells are fixed on the shaft in several equal length sections. At the same time, for two adjacent bearing shells in the lateral direction, the line connecting the flange connecting plates on both sides of one bearing shell is perpendicular to the line connecting the flange connecting plates on both sides of the adjacent bearing shell. This helps to ensure the shaft rotation balance, stable operation, and facilitates blade maintenance and replacement.

[0017] Preferably, the drying equipment is arranged in a layered configuration. The chamber consists of an upper and lower section, both connected by flanges. The chamber is constructed of inner and outer layers, with sealing plates at both ends. Both the upper and lower chambers are bolted to the crossbeams of the side frames. The discharge port of the upper chamber connects to the inlet of the lower chamber. This design is chosen because: the shaft cannot be too long, as an excessively long shaft is prone to bending and unstable operation; it increases the material travel distance and the contact time between hot air and material, improving heat exchange efficiency and drying effect; and it reduces the horizontal space occupied by the equipment. Currently, the fine slag production workshops of coal chemical plants have limited space, making it impossible to install rotary drum dryers. Furthermore, the site is an explosion-proof area where open flames are prohibited.

[0018] Preferably, the reducer assembly drives the dual shafts to rotate via a coupling.

[0019] Preferably, the hot air system uses high-temperature hot air (250°C~400°C) (waste heat from boiler flue gas or electric heater) which enters from the air inlets on both sides or bottom of the housing via an induced draft fan, is evenly distributed by the air distribution plate, and the exhaust gas is treated by a cyclone dust collector and a condenser to recover moisture.

[0020] The beneficial effects of this utility model are as follows:

[0021] (1) The blades of the dual-shaft throwing system are arranged in an alternating pattern. The deflection angle, spacing, thickness, and rotation speed of the blades take into account the material walking speed, material viscosity, and contact time with hot air. This can cut and break up the material clumps and throw them, so that the material can be fully mixed and contacted with hot air, improve thermal efficiency to achieve the drying effect, and reduce energy consumption.

[0022] (2) The blades are mounted on the shaft through bearing bushes, which can prevent shaft deformation. At the same time, the bearing bushes are divided into several sections, and the connecting lines of the flange connecting plates on both sides of two adjacent bearing bushes are perpendicular to each other, which can ensure the shaft rotation balance, stable operation, and facilitate blade maintenance and replacement.

[0023] (3) The drying chamber is divided into upper and lower layers, which can avoid the shaft being too long and easy to bend when a single layer is set. It can also increase the material walking distance and the contact time between hot air and material, improve heat exchange efficiency and drying effect, and at the same time reduce the horizontal space occupied by the equipment.

[0024] (4) The thermal efficiency of this invention can be increased to over 85%, and energy consumption can be reduced by over 30%. The exhaust gas is treated by a cyclone dust collector and a condenser, and the emissions meet the standards (particulate matter ≤20mg / m3, NOx ≤100mg / m3). After drying, the moisture content of the fine residue is ≤20%, which meets the requirements for resource utilization. The equipment footprint is reduced by 50%, and the operating cost is reduced by about 35%. Attached Figure Description

[0025] Figure 1 This is a top view of a hot air twin-shaft drying equipment;

[0026] Figure 2 This is a front view of a hot air twin-shaft dryer;

[0027] Figure 3 A 3D diagram of a hot air twin-shaft dryer;

[0028] Figure 4 This is a schematic diagram of the installation of the propeller blade and bearing.

[0029] Figure 5 A schematic diagram showing the deflection angle between the blade and the shaft;

[0030] 101 Housing; 102, 103 Shafts; 104 Blade; 105 Connecting Flange Plate; 106 Bearing Shell; 107 Reducer Assembly; 108 Discharge Port; 109 Inlet / Outlet Port; 110 Inlet Port; 111 Steam Outlet; 112 Bearing Housing; 201 Air Inlet; 202 Hot Air Duct; 203 Dust Collector; 204 Condenser; 301 Frame. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0032] In this invention, the horizontal direction or transverse direction is along the axis 102, 103, and the vertical direction or longitudinal direction is perpendicular to the axis 102, 103.

[0033] Figure 1-3 This is a schematic diagram of a hot air dual-axis drying equipment, specifically including a housing 101, which is a horizontal design.

[0034] Preferably, two boxes 101 are provided, arranged in upper and lower layers. The discharge port of the upper box and the inlet of the lower box are connected to form an inlet / outlet 109. The upper box has an inlet 110 at the top, and the lower box has an outlet 108 at the bottom. The box also has a steam outlet 111.

[0035] Preferably, the inner lining material of the box 101 is a wear-resistant ceramic material, and the box 101 also includes a heat insulation layer with a temperature resistance of ≥400°C.

[0036] Preferably, both the upper and lower drying chambers 101 are equipped with a dual-axis spreading system. The dual-axis spreading system specifically includes two parallel shafts 102 and 103, which are horizontally arranged and can rotate in both directions. The two shafts 102 and 103 rotate in both directions simultaneously. The purpose of rotating in both directions is to make the material rise up and collide with each other, so that the material is fully mixed with the hot air and the material is propelled forward.

[0037] Preferably, the rotational speed of shafts 102 and 103 is 70~400 rpm. Below 70 rpm, the material cannot be thrown up and dispersed. When the speed is too high, exceeding 400 rpm, the material moves quickly, resulting in short contact time between the material and hot air, reducing the drying effect. An ideal and preferred rotational speed is within the range of 150~300 rpm. Paddles 104 are mounted on shafts 102 and 103. The paddles 104 on the two parallel shafts 102 and 103 are arranged in a staggered pattern. The deflection angle of the paddles 104 relative to the vertical direction of shafts 102 and 103 is within the range of 5°~30°. When the deflection angle of the paddles 104 relative to the vertical direction of shafts 102 and 103 is less than 5°, the paddles 104 are almost parallel to the vertical direction of shafts 102 and 103, resulting in slow material movement and insufficient output. When the angle is greater than 30°, the material moves too quickly, resulting in short contact time between the material and hot air, reducing the drying effect, and simultaneously increasing resistance and energy consumption.

[0038] See Figure 5 'a' is the deflection angle of the blade 104 in the vertical direction relative to the shafts 102 and 103, which is in the range of 5° to 30°.

[0039] Preferably, the shafts 102 and 103 are hollow shafts.

[0040] Preferably, the blades 104 are spaced 30-80mm apart along the shafts 102 and 103. This spacing refers to the distance from the right end of the left blade to the left end of the right blade between two adjacent blades. Longitudinally, multiple blades 104 are welded to the bearing shell 106 or the shaft at certain intervals. Preferably, two bearing shells are joined and fixed to the shafts 102 and 103 by connecting flange plates 105. It is not recommended to directly fix the blades 104 to the hollow shaft, as the long shaft spacing leads to uneven heating and deformation during welding, resulting in low concentricity and unstable operation. This arrangement of blades serves to cut, break up, and scatter the material clumps, ensuring thorough mixing and contact between the material and hot air, thereby improving thermal efficiency and achieving a drying effect.

[0041] The configuration of the paddle 104 is related to the output and material travel speed of the drying equipment. Preferably, the cross-sectional thickness of the paddle 104 is 10~30mm. If the paddle cross-section is small, the amount of material thrown is small and the output is insufficient. If the paddle cross-section is too large, the resistance is high and the material travel speed is high, which reduces the drying effect.

[0042] Preferably, the blade 104 is made of high wear-resistant alloy steel, and each blade is fan-shaped. Specifically, the 360 ​​degrees are divided into eight equal parts, which are the central angles of a single fan-shaped blade. Then, according to the actual required deflection angle, four blades are evenly spiraled around the outer circumference of the shaft. Here, "evenly spiraled around" means that the connection positions of the four blades and the shaft form a spiral line.

[0043] Preferably, the bearing shell 106 is divided into several equal-length sections and fixed on the shaft, that is, a shaft has multiple bearing shells. At the same time, for two adjacent bearing shells along the horizontal direction of the shaft, the line connecting the flange connecting plates on both sides of one bearing shell is perpendicular to the line connecting the flange connecting plates on both sides of the adjacent bearing shell. This helps to ensure the shaft rotation balance, stable operation, and facilitates blade maintenance and replacement.

[0044] Preferably, the drying equipment housing 101 is arranged in layers. That is, there are two housings 101: an upper housing and a lower housing, both connected by flanges. The housing is made of inner and outer layers, with sealing plates at both ends. Both the upper and lower housings are bolted to the crossbeams of the side frames. The discharge port of the upper housing connects to the inlet of the lower housing. This design is chosen because: the shaft cannot be too long, as an excessively long shaft is prone to bending and unstable operation; it increases the material travel distance and the contact time between hot air and material, improving heat exchange efficiency and drying effect; and it reduces the horizontal space occupied by the equipment. Currently, the fine slag production workshops of coal chemical enterprises have limited space, making it impossible to install a rotary drum dryer. Furthermore, the site is an explosion-proof area where open flames are not permitted.

[0045] Preferably, the reducer assembly 107 drives the dual shafts 102 and 103 to rotate via a coupling, and is also provided with a bearing housing 112.

[0046] Preferably, both the upper and lower housings 101 are provided with air inlets 201 and hot air ducts 202.

[0047] Preferably, the hot air system is a high-temperature hot air (250°C~400°C) (waste heat from boiler flue gas or electric heater) that enters from the air inlets 201 on both sides or bottom of the housing via an induced draft fan. The hot air duct 202 is equipped with an air distribution plate. The hot air enters the hot air duct 202 through the air inlet 201 and is evenly distributed through the air distribution plate. The exhaust gas is treated by a cyclone dust collector 203 and a condenser 204 to recover moisture.

[0048] The following sections detail the design of the blade parameters and the shaft rotation speed, providing several specific implementation examples.

[0049] Example 1: A biaxial spreading system for hot air drying of fine coal chemical slag, comprising two parallel shafts 102 and 103, with blades 104 arranged in an alternating pattern on the two parallel shafts, each blade 104 being fan-shaped; longitudinally, four blades are evenly spiraled around the outer circumference of the shaft in four equal parts; horizontally along the shaft, multiple rows of blades are arranged, with adjacent blades arranged parallel to each other; the shaft rotation speed is 200 rpm; the blade deflection angle in the vertical direction relative to the shaft is 10 degrees; the blade cross-sectional thickness is 16 mm; and the blade spacing along the shaft is 50 mm. For ease of implementation, the blades are obtained by dividing a circular piece with a radius of 250mm into eight equal parts, that is, dividing 360 degrees into eight equal parts, which is the central angle of a single fan-shaped blade. Four blades are taken, and the length of the straight segment of a single fan-shaped blade (i.e., the straight segment adjacent to the outermost arc edge of the blade) is 170.5mm. Here, it refers to the 170.5mm section of the fan-shaped blade away from the center after dividing it into eight equal parts. It should be noted that the radius of 250mm and the length of the straight segment of the blade of 170.5mm are only examples of this embodiment and are not the main content protected by this utility model.

[0050] Example 2: The difference from Example 1 is that the shaft speed is 70 rpm.

[0051] Example 3: The difference from Example 1 is that the shaft speed is 150 rpm.

[0052] Example 4: The difference from Example 1 is that the shaft speed is 300 rpm.

[0053] Example 5: The difference from Example 1 is that the shaft speed is 400 rpm.

[0054] Example 6: The difference from Example 1 is that the vertical deflection angle between the blade and the shaft is 5 degrees.

[0055] Example 7: The difference from Example 1 is that the vertical deflection angle between the blade and the shaft is 30 degrees.

[0056] Example 8: The difference from Example 1 is that the blade cross-section thickness is 10mm.

[0057] Example 9: The difference from Example 1 is that the blade cross-section thickness is 30mm.

[0058] Example 10: The difference from Example 1 is that the blades are spaced 30mm apart along the axis.

[0059] Example 11: The difference from Example 1 is that the blades are spaced 80mm apart along the axis.

[0060] Comparative Example 1: A biaxial spreading system for hot air drying of fine coal chemical slag, comprising two parallel shafts with staggered blades arranged on them. Each blade is fan-shaped. The blades are arranged in four equal spirals around the outer circumference of the shafts. Multiple rows of blades are arranged along the horizontal direction of the shafts, with adjacent blades parallel to each other. The shaft rotation speed is 50 rpm, the blade deflection angle perpendicular to the shaft is 55 degrees, the blade cross-sectional thickness is 14 mm, and the blade spacing along the shaft is 100 mm. A circular component with a radius of 250 mm is divided into eight equal parts, representing the central angle of a single fan-shaped blade. Four blades are selected, and the length of the straight segment of each fan-shaped blade (i.e., the straight segment adjacent to the outermost arc edge of the blade) is 170.5 mm.

[0061] The thermal efficiencies of Examples 1-11 and Comparative Example 1 are shown in Table 1 below.

[0062] Table 1

[0063] Shaft rotation speed Vertical deflection angle of the blades relative to the shaft Blade cross-sectional thickness The blades are spaced apart along the axis. Thermal efficiency Example 1 200rpm 10 degrees 16mm 50mm 90.89% Example 2 70 rpm 10 degrees 16mm 50mm 83.31% Example 3 150rpm 10 degrees 16mm 50mm 87.02% Example 4 300 rpm 10 degrees 16mm 50mm 86.71% Example 5 400 rpm 10 degrees 16mm 50mm 82.04% Example 6 200rpm 5 degrees 16mm 50mm 87.32% Example 7 200rpm 30 degrees 16mm 50mm 89.91% Example 8 200rpm 10 degrees 10mm 50mm 90.23% Example 9 200rpm 10 degrees 30mm 50mm 90.67% Example 10 200rpm 10 degrees 16mm 30mm 91.01% Example 11 200rpm 10 degrees 16mm 80mm 88.32% Comparative Example 1 50rpm 55 degrees 14mm 100mm 48.67%

[0064] Through the above embodiments and comparative examples (i.e., the prior art), it can be seen that the parameter settings of this application significantly improve the thermal efficiency, which can reach 82%-91%. The preferred rotation speed is 150~300 rpm, and the thermal efficiency can reach over 85%.

[0065] This utility model's dual-shaft spreading system features staggered blade arrangements. The blade deflection angle, spacing, thickness, and rotation speed are carefully controlled to balance material travel speed, material viscosity, and contact time with hot air. This allows for the cutting, breaking up, and spreading of material clumps, ensuring thorough mixing and contact between the material and hot air, improving thermal efficiency for drying, and reducing energy consumption. The blades are mounted on the shaft via bearing bushes, preventing shaft deformation. Furthermore, the bearing bushes are divided into several segments, and the flange connecting plates on the sides of two laterally adjacent bearing bushes are perpendicular, ensuring shaft rotational balance, stable operation, and easy blade maintenance and replacement. The drying chamber is divided into upper and lower layers, avoiding the excessive shaft length and bending issues associated with single-layer installations. This design also increases the material travel distance and the contact time between hot air and material, improving heat exchange efficiency and drying effect, while reducing the horizontal space occupied by the equipment.

[0066] This invention achieves a thermal efficiency of over 85% and reduces energy consumption by over 30%. The exhaust gas is treated by a cyclone dust collector and condenser, ensuring emissions meet standards (particulate matter ≤20mg / m³, NOx ≤100mg / m³). After drying, the fine residue has a moisture content of ≤20%, meeting resource utilization requirements. The equipment's footprint is reduced by 50%, and operating costs are reduced by approximately 35%.

Claims

1. A double-shaft throwing system for hot air drying of coal chemical fine slag, comprising two parallel shafts, and paddles arranged in staggered rows on the two parallel shafts, characterized in that: Each blade is fan-shaped; multiple rows of blades are arranged horizontally along the shaft, with adjacent blades arranged in parallel. In the longitudinal direction, four blades are evenly spiraled around the outer circumference of the shaft. The shaft speed is 70~400 rpm, the blade deflection angle with the shaft in the vertical direction is 5°~30°, the blade cross-sectional thickness is 10~30 mm, and the blade spacing along the shaft is 30~80 mm.

2. The dual-axis flinging system of claim 1, wherein: The shaft speed is 150~300 rpm.

3. The dual-axis spraying system according to claim 1, characterized in that: The shaft is a hollow shaft.

4. The biaxial spraying system according to any one of claims 1-3, characterized in that: The blades are welded onto the bearing shells, and the two bearing shells are joined and fixed onto the shaft by connecting flange plates.

5. The dual-axis spraying system according to claim 4, characterized in that: The bearing shells are fixed to the shaft in several sections. For two adjacent bearing shells in the lateral direction, the line connecting the flange connecting plates on both sides of one bearing shell is perpendicular to the line connecting the flange connecting plates on both sides of the adjacent bearing shell, so that the shaft can rotate in a balanced manner.

6. A twin-shaft drying device for hot air drying of fine coal chemical slag, comprising the twin-shaft spreading system as described in any one of claims 1-5, characterized in that: It includes a drying chamber, which is horizontally designed and arranged in two layers, with the upper chamber's outlet connected to the lower chamber's inlet. The dual-axis scattering system is installed inside the chamber.

7. The dual-shaft drying equipment according to claim 6, characterized in that: The inner lining of the enclosure is made of wear-resistant ceramic material.

8. The dual-shaft drying equipment according to claim 6 or 7, characterized in that: The reducer assembly drives the dual shafts to rotate via a coupling.

9. The dual-shaft drying equipment according to any one of claims 6-8, characterized in that: It includes a hot air system, in which high-temperature hot air enters from the air inlets on both sides or bottom of the box and is evenly distributed through the air distribution plates in the hot air duct. The hot air temperature is 150~400°C.

10. The dual-shaft drying equipment according to claim 9, characterized in that: The exhaust gas is treated by a cyclone dust collector and a condenser.

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