A device for improving the heat exchange efficiency of a coil dryer

Abstract

The application discloses a device for improving heat exchange efficiency of a coil drying machine, which comprises a material conveying assembly, a drying assembly, a dry material collecting assembly, a tail gas processing assembly and a nitrogen gas heating assembly; the material conveying assembly is connected with the drying assembly; the drying assembly dries the mineral to be dried in a hot nitrogen gas and hot air environment, and dry material and tail gas are generated; the dry material is collected by the dry material collecting assembly, and the tail gas generated in the collecting process is sent into the drying assembly; the tail gas enters the tail gas processing assembly, is processed, and is sent into the nitrogen gas heating assembly; the nitrogen gas heating assembly heats the nitrogen gas source introduced by using the processed tail gas, and outputs the heated hot nitrogen gas to the drying assembly. The device can improve waste heat utilization rate, reduce steam consumption by 15%-25%, ensure that the water content of the concentrate is stably lower than 0.3%, meet the requirements of the flash smelting process, and has remarkable energy-saving and environmental protection benefits.

Description

Technical Field

[0001] This invention relates to the field of copper smelting mineral drying equipment, specifically to a device for improving the heat exchange efficiency of a coil dryer. Background Technology

[0002] In copper smelting, mineral drying is a crucial pretreatment step. Its main purpose is to reduce moisture content and prevent steam expansion caused by rapid vaporization of moisture when wet concentrate is directly fed into the high-temperature smelting furnace, which could threaten equipment safety. This method also improves the physical properties of the minerals, facilitating pneumatic conveying and uniform feeding. Steam dryers utilize steam in the dryer coils to vaporize the moisture in the minerals through indirect contact heating, obtaining solid materials with a specified moisture content. This method is widely used due to its large processing scale and high particle dispersibility after drying. Flash furnaces typically require the concentrate moisture content to be below 0.3%, making drying a mandatory step in copper smelting. However, current steam dryers have the following shortcomings in practical use.

[0003] First, the insulating steam condensate in the baghouse dust collector of the steam dryer is high-temperature hot water (90~100℃), which contains residual heat. Existing equipment does not effectively recover and utilize this residual heat, resulting in heat waste. Second, the dryer's feed end draws in air and protective nitrogen gas. Because the drawn-in air is cold and has a significant temperature difference with the equipment's interior, material tends to adhere around the coils at the dryer head and on the inner wall of the cylinder, affecting drying efficiency and increasing energy consumption. Third, the hot air collected by the elevator system via the induced draft fan is not recovered but directly discharged into the atmosphere, further causing waste heat loss. These three waste heat issues collectively contribute to the high energy consumption of the steam dryer. Effective recovery of this waste heat could significantly reduce the dryer's steam consumption per unit. Therefore, the rational reuse of this waste heat is of great significance. Summary of the Invention

[0004] To overcome the problems of existing technology, the present invention provides a device for improving the heat exchange efficiency of a coil dryer, which is suitable for the pretreatment drying of minerals in flash smelting process. It can realize the recovery and utilization of waste heat, reduce equipment energy consumption, ensure that the moisture content of concentrate meets the standard, and solve the problems of waste heat waste and material adhesion at the feed end of the dryer in the traditional drying process.

[0005] A device for improving the heat exchange efficiency of a coil dryer includes a material conveying assembly, a drying assembly, a dry material collection assembly, a tail gas treatment assembly, and a nitrogen heating assembly. The material conveying component is connected to the drying component and is used to convey the minerals to be dried to the drying component; The drying assembly dries the mineral to be dried in a hot nitrogen and hot air environment, producing dry material and exhaust gas; The dry material is collected by a dry material collection component, and the exhaust gas generated during the collection process is sent into the drying component; The exhaust gas enters the exhaust gas treatment component, and after being treated by it, it is sent to the nitrogen heating component. The nitrogen heating component uses the treated exhaust gas to heat the incoming nitrogen source, and outputs the heated nitrogen to the drying component. The device employs a waste heat recycling method, using the waste heat of the exhaust gas to heat nitrogen, effectively recovering the waste heat resources generated during drying.

[0006] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the material conveying assembly is a movable belt.

[0007] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the drying assembly includes a steam dryer body and a dryer discharge hopper, wherein the steam dryer body dries the minerals to be dried and then sends the resulting dry material and exhaust gas into the dryer discharge hopper.

[0008] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the dryer discharge hopper is provided with a dry material outlet, a tail gas outlet, a steam inlet, and a condensate outlet.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the dry material collection assembly includes a dryer rotary screen, an air elevator, a gravity dust collector, a cyclone dust collector, and an elevator bag dust collector connected in sequence, wherein the dryer rotary screen is connected to the dryer discharge hopper via a dry material outlet.

[0010] In addition to the aspects described above and any possible implementations, a further implementation is provided, which further includes a Roots blower connected to and used to power the air lift.

[0011] In addition to the aspects described above and any possible implementations, a further implementation is provided, which further includes a dry ore bin connected to the baghouse dust collector of the elevator.

[0012] In addition to the aspects and any possible implementations described above, a further implementation is provided in which a hot exhaust gas pipe is provided between the baghouse dust collector of the elevator and the feed end of the dryer body, and an air elevator induced draft fan is provided on the pipe.

[0013] In addition to the aspects and any possible implementations described above, a further implementation is provided in which a nitrogen heating assembly is provided with a nitrogen coil, the diameter of the coil being 40 mm, the spacing between pipes being 400~500 mm, the nitrogen coil being used to introduce nitrogen, the nitrogen flow rate in the pipes being 200 m / s~400 m / s, and the pressure being 0.2~0.6 MPa.

[0014] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the hot exhaust gas pipe is configured as an annular pipe with a circular gap at the outlet end, and the gap direction is towards the dryer body.

[0015] Furthermore, the pipes for conveying hot nitrogen, the hot exhaust gas pipes, the dryer body, and the dryer bag dust collector are all wrapped with thermal insulation cotton.

[0016] Beneficial effects of the present invention Compared with existing technologies that use free air and ambient temperature nitrogen at the feed end of the drying system, the steam rotary dryer provided by this invention has the following significant advantages: First, the present invention adopts the waste heat recycling method, which uses the waste heat of the insulation steam condensate of the dryer bag dust collector to heat nitrogen. There is no need to consume additional steam to heat nitrogen, which is economical, highly operable, and the process is simple and easy to implement, effectively recovering the waste heat resources of the insulation steam condensate. Secondly, this invention makes reasonable use of the air heated when the dried high-temperature minerals are transported by the air elevator. After the hot air is collected by the bag dust collector of the elevator, it is returned to the head feed end by the induced draft fan, so as to fully recover and utilize the residual heat in the hot air, reduce the heat loss of the system, and have a good heat recovery effect. Third, this invention fully recovers the hot air from the conveying process of the dried ore and the waste heat from the steam condensate drain of the bag filter dust collector in the dryer. On the one hand, it reduces the amount of cold air drawn into the head of the dryer, increases the temperature of the concentrate at the head of the dryer, and ensures smooth feeding, thereby reducing steam energy consumption by 2~2.5t / h, achieving the goal of economy and energy saving. On the other hand, it uses the waste heat from the steam condensate drain to preheat the nitrogen inlet air of the dryer, effectively avoiding the material adhesion problem caused by the large temperature difference between the room temperature nitrogen and the inside of the equipment, and improving the heat transfer efficiency.

[0017] In summary, this invention can increase the waste heat utilization rate to over 85%, reduce steam consumption by 15% to 25%, and ensure that the concentrate moisture content is consistently below 0.3%, fully meeting the requirements of flash smelting process. It has significant energy-saving and environmental protection benefits and high industrial application value. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the device structure of the present invention. Detailed Implementation

[0019] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0020] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0021] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0022] like Figure 1 As shown, the device of the present invention includes a material conveying assembly, a drying assembly, a dry material collection assembly, an exhaust gas treatment assembly, and a nitrogen heating assembly; The material conveying component is connected to the drying component and is used to convey the minerals to be dried to the drying component; The drying assembly dries the mineral to be dried in a hot nitrogen and hot air environment, producing dry material and exhaust gas; The dry material is collected by a dry material collection component, and the hot air generated during the collection process is sent into the drying component; The exhaust gas enters the exhaust gas treatment component, and after being treated by it, it is sent to the nitrogen heating component. The nitrogen heating component uses the treated exhaust gas to heat the incoming nitrogen source, and outputs the heated nitrogen to the drying component.

[0023] Furthermore, the material conveying assembly is a movable belt.

[0024] Furthermore, the drying assembly includes a steam dryer body and a dryer discharge hopper. The steam dryer body dries the minerals to be dried and then sends the resulting dry material and exhaust gas into the dryer discharge hopper.

[0025] Furthermore, the dryer discharge hopper is equipped with a dry material outlet, a tail gas outlet, a steam inlet, and a condensate outlet.

[0026] Furthermore, the dry material collection assembly includes a dryer rotary screen, an air elevator, a gravity dust collector, a cyclone dust collector, and an elevator bag dust collector connected in sequence.

[0027] Furthermore, it also includes a Roots blower connected to and used to power the air lift.

[0028] Furthermore, it also includes a dry ore bin connected to the bag filter of the elevator.

[0029] Specifically, the device of the present invention includes a steam dryer body 1, a dryer discharge hopper 2, a dryer bag dust collector 3, a rotary screen 4, an air lift 5, a Roots blower 6, a gravity dust collector 7, a cyclone dust collector 8, an elevator bag dust collector 9, a movable belt 10, a nitrogen chamber 11, a nitrogen coil 12, a dry ore bin 13, an air lift induced draft fan 14, and a dryer bag dust collector exhaust fan 15.

[0030] The movable belt 10 is connected to the feed end of the steam dryer body 1. The mineral to be dried is conveyed to the feed end by the movable belt 10 and then fed into the dryer body 1. The feed end is provided with an air inlet hole, and a trumpet-shaped nitrogen pipe is fixedly installed inside the air inlet hole. It is used to connect the hot nitrogen gas heated by the heat-insulating steam discharged from the dryer bag dust collector 3. The dryer body 1 dries the mineral to be dried under the action of hot nitrogen gas and hot exhaust gas to obtain a mixture of dry material and gas, which is directly fed into the discharge hopper 2. The sources of hot nitrogen gas and hot exhaust gas are described below.

[0031] The discharge hopper 2 serves a storage function and is equipped with a dry material outlet, a tail gas outlet, a steam inlet, and a condensate outlet. It is connected to the rotary screen 4 via the dry material outlet and to the dryer baghouse dust collector 3 via the tail gas outlet. The steam inlet is used to receive external steam for further treatment of the tail gas. The condensate outlet discharges the condensate generated during treatment. The discharge hopper 2 conveys the stored dry material to the rotary screen 4 for screening to remove agglomerated materials, while the tail gas enters the dryer baghouse dust collector 3. The discharge end of the rotary screen 4 is connected to the air lift 5, and a Roots blower 6 is connected to the air lift 5 to provide power. The discharge end of the air lift 5 is sequentially connected to a gravity dust collector 7 and a cyclone dust collector 8. The air lift 5 conveys the dry material, which is then processed sequentially by the gravity dust collector 7 and the cyclone dust collector 8. The fed dry material is processed; the discharge end of the cyclone dust collector 8 is connected to the elevator bag dust collector 9, which transports the processed dry material to the dry ore bin 13 for storage. Simultaneously, the elevator bag dust collector 9 directs the exhaust gas generated during the processing through a hot exhaust gas pipe, and the air induced draft fan 14 installed on the pipe draws the exhaust gas back to the feed end of the air dryer body 1. Excess hot exhaust gas is vented through a valve installed on another branch of the hot exhaust gas pipe. The outlet end of the hot exhaust gas pipe is a ring-shaped pipe with circular gaps, the gaps facing the dryer body 1, ensuring that the hot exhaust gas is evenly blown onto the minerals to be dried in the air dryer body 1.

[0032] The dryer bag filter dust collector 3 further processes the exhaust gas transported from the discharge hopper 2, separating the mineral particles in it. The separated minerals re-enter the discharge hopper 2, while the exhaust gas obtained after separation enters the nitrogen chamber 11 through a pipeline. The temperature inside the nitrogen chamber 11 is controlled between 90 and 110°C, and the pressure is 0.2 to 0.6 MPa. A 0.6 MPa pressure relief valve is installed at the outlet of the nitrogen chamber 11 to recover the generated condensate. To achieve the insulation effect, the outside of the nitrogen chamber 11 is wrapped with insulation cotton, and the thickness of the insulation cotton is selected according to actual needs.

[0033] Meanwhile, the dryer exhaust fan 15, which is connected to the dryer bag dust collector 3, is used to assist in the discharge of tail gas and the airflow regulation in the dryer bag dust collector 3. The dryer bag dust collector 3 is also equipped with a steam inlet for inputting bag insulation steam. The steam is heated by the tail gas from the dry material hopper 2 in the dryer bag dust collector 3 and then enters the nitrogen chamber 11 to heat the nitrogen entering the nitrogen chamber 11. The heated nitrogen is connected to the trumpet-shaped nitrogen pipe at the feed end through a pipeline and then sent to the feed end of the dryer body 1.

[0034] A nitrogen coil 12 is fixedly installed in the nitrogen chamber 11. The diameter of the nitrogen coil 12 is 40 mm, and the spacing between the pipes is 400~500 mm, preferably 450 mm. The nitrogen coil 12 is used to introduce nitrogen. The flow rate of nitrogen in the pipe is controlled at 200 m / s~400 m / s, and the pressure is 0.2~0.6 MPa. It is heated by heating steam from the bag dust collector 3 of the dryer.

[0035] In addition, the pipes for conveying hot nitrogen, the hot exhaust gas pipes, the dryer body, and the dryer bag dust collector are all wrapped with thermal insulation cotton to keep these components warm. The thickness is selected according to the needs.

[0036] The dryer of the present invention adopts the waste heat recycling method, which uses the waste heat in the gas discharged from the bag dust collector 3 of the dryer to heat nitrogen, providing a fresh air heat source for the nitrogen that needs to be heated, thereby reducing economic costs, making it highly operable, and with a simple and easy process flow. Secondly, the present invention utilizes the hot exhaust gas discharged from the bag dust collector 9 of the elevator as a drying heat source, thereby reducing the heat loss of the system and having a good heat return effect. In summary, this invention improves the drying efficiency of the dryer body 1 by rationally utilizing the hot gas generated during the drying process, ensuring smooth material feeding and reducing steam energy consumption by 2-2.5 t / h, thus achieving economic and energy-saving goals and maximizing resource utilization. The entire process generates no waste gas, wastewater, or solid waste, and all resources are utilized with maximum efficiency. Therefore, this invention has the advantages of being economical, energy-saving, and having high resource utilization.

[0037] The following specific examples and comparative examples will be used for illustration: The mineral drying in the following comparative examples and embodiments was carried out in a coil-type steam dryer. The raw material to be dried was copper concentrate with a moisture content of 8.3% (mass fraction) at a temperature of 28°C. The copper concentrate feed rate was 180 t / h. Thermocouple testing was used for gas temperature measurement, and mineral temperature testing was performed using a mineral thermometer. The temperature of the ore at the discharge end was set to 115°C, and the main steam flow rate was adjusted based on the temperature of the ore at the discharge end. The mineral moisture content was analyzed using the loss on drying method. 5-6g of mineral was placed in the loss on drying chamber, heated to constant weight, and the sample was repeated three times, with the average value taken. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] Comparative Example 1 A traditional steam dryer was used, without recovering any waste heat. The dryer head draws in ambient temperature air (28℃), with no hot air recirculation or nitrogen preheating. After 12 hours of operation, the following tests were conducted: main steam consumption was 25.8 t / h, concentrate moisture content was 0.4% (slightly exceeding the standard), material adhesion occurred at the dryer head, hot air was directly discharged, resulting in significant waste heat and high energy consumption.

[0039] Comparative Example 2 The only difference from Comparative Example 1 is that the hot air accompanying the baghouse dust collection of the elevator is recovered and returned to the head feed end through a hot air pipeline; the rest of the structure remains unchanged. After 12 hours of operation, the following tests were conducted: main steam consumption was 22.1 t / h, a decrease of 14.3% compared to Example 1; concentrate moisture content was 0.25% (meeting the standard), with no material adhesion; waste heat recovery utilization rate increased by 35%, proving that hot air recovery can effectively reduce energy consumption.

[0040] Comparative Example 3 The only difference from Comparative Example 1 is that the residual heat from the steam condensation in the dryer's baghouse dust collector is used to heat nitrogen before it is fed into the head feed end; the rest of the structure remains unchanged. After 12 hours of operation, the following tests were conducted: main steam consumption was 21.9 t / h, a 15.1% reduction compared to Example 1; concentrate moisture content was 0.2% (meeting the standard); there was no material adhesion at the dryer head; and the residual heat recovery effect was significant.

[0041] Example 1

[0042] The complete technical solution of this invention involves: recovering hot air from the elevator and using the residual heat from the steam condensate drain at the tail end of the dryer to heat nitrogen. The hot air pipe outlet is annular, and the hot nitrogen is introduced through a funnel-shaped pipe. All related pipes / equipment are wrapped with insulation cotton. After 12 hours of operation, the main steam consumption was 19.3 t / h, a 25.2% reduction compared to Example 1 (existing technology); the waste heat utilization rate reached 88%, and the concentrate moisture content was 0.2% (fully compliant). This solves the problems of high energy consumption, material adhesion, and waste heat in traditional dryers, fully demonstrating the practicality and superiority of this invention.

[0043] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A device for improving the heat exchange efficiency of a coil dryer, characterized in that, Includes material conveying components, drying components, dry material collection components, exhaust gas treatment components, and nitrogen heating components; The material conveying component is connected to the drying component and is used to convey the minerals to be dried to the drying component; The drying assembly dries the mineral to be dried in a hot nitrogen and hot air environment, producing dry material and exhaust gas; The dry material is collected by a dry material collection component, and the exhaust gas generated during the collection process is sent into the drying component; The exhaust gas enters the exhaust gas treatment component, and after being treated by it, it is sent to the nitrogen heating component. The nitrogen heating component uses the treated exhaust gas to heat the incoming nitrogen source, and outputs the heated nitrogen to the drying component. The device employs a waste heat recycling method, using the waste heat of the exhaust gas to heat nitrogen, effectively recovering the waste heat resources generated during drying.

2. The apparatus according to claim 1, characterized in that, The material conveying assembly is a movable belt.

3. The apparatus according to claim 2, characterized in that, The drying assembly includes a steam dryer body and a dryer discharge hopper. The steam dryer body dries the minerals to be dried and then sends the resulting dry material and exhaust gas into the dryer discharge hopper.

4. The apparatus according to claim 3, characterized in that, The dryer discharge hopper is equipped with a dry material outlet, a tail gas outlet, a steam inlet, and a condensate outlet.

5. The apparatus according to claim 4, characterized in that, The dry material collection assembly includes a dryer rotary screen, an air elevator, a gravity dust collector, a cyclone dust collector, and an elevator bag dust collector connected in sequence. The dryer rotary screen is connected to the dryer discharge hopper via the dry material outlet.

6. The apparatus according to claim 5, characterized in that, It also includes a Roots blower connected to and used to power the air lift.

7. The apparatus according to claim 5, characterized in that, It also includes a dry ore bin connected to the bag dust collector of the elevator, wherein the dry material is processed by the dry material collection component and then sent into the dry ore bin.

8. The apparatus according to claim 6, characterized in that, A hot exhaust gas pipe is provided between the bag dust collector of the elevator and the feed end of the dryer body, and an air elevator fan is installed on the pipe.

9. The apparatus according to claim 1, characterized in that, The nitrogen heating assembly is equipped with a nitrogen coil with a diameter of 40 mm and a spacing of 400-500 mm between pipes. The nitrogen coil is used to introduce nitrogen gas, and the nitrogen gas flow rate in the pipe is 200 m / s-400 m / s, with a pressure of 0.2-0.6 MPa.

10. The apparatus according to claim 8, characterized in that, The hot exhaust gas pipe is configured as an annular pipe with a circular gap at the outlet end, and the gap direction is oriented towards the dryer body.

Images