Gradient heating and high-efficiency heat exchange integrated device of sodium silicate smelting furnace

Abstract

The application provides a gradient heating and high-efficiency heat exchange integrated device of a sodium silicate melting furnace, and relates to the technical field of silicate production. The device comprises a melting furnace body, a flue gas shunting system, a gradient heat exchange and purification system, a heat feedback system and an intelligent control system. The flue gas shunting system separates high-temperature and medium-temperature flue gas; the gradient heat exchange system comprises a high-temperature heat exchanger and a switchable filtering heat exchange module in parallel, and the filtering heat exchange module comprises a composite filtering body, which integrates a tapered anti-blocking mesh, an ash-reducing coating and integrated fins; the heat feedback system precisely supplies recovered high-temperature and low-temperature heat to a high-temperature area and a preheating area of the melting furnace, respectively; and the intelligent control system automatically triggers pulse-rattling ash removal of the module based on pressure difference and temperature signals and dynamically optimizes heat distribution. The application realizes long-term anti-blocking and online self-cleaning of the heat exchange surface, gradient recovery and intelligent utilization of waste heat, and significantly improves the continuity, stability and energy efficiency of system operation.

Description

Technical Field

[0001] This invention relates to the field of silicate production equipment and energy-saving and environmental protection technology, specifically to an integrated device for gradient heating and high-efficiency heat exchange in a sodium silicate melting furnace. Background Technology

[0002] Sodium silicate (water glass) is mainly produced using the melting furnace method. The core of the process is to establish and maintain a gradient temperature field along the length of the furnace, from low temperature to high temperature and then gradually decreasing, forming a preheating zone, melting zone, clarification zone and heat preservation zone in sequence, so as to meet the physical and chemical reaction requirements of the raw materials at different stages, thereby achieving the purpose of energy saving and ensuring product quality.

[0003] During the operation of a melting furnace, especially in the melting and clarification stages, a large amount of high-temperature flue gas is generated, containing significant waste heat resources. Current technology typically involves installing heat exchangers (such as finned tubes and heat pipes) in the flue to recover this heat for heating water, air, or generating steam. However, the flue gas from sodium silicate melting furnaces contains a large amount of alkali metal oxide vapors (such as Na₂O) and dust such as SiO₂. These easily condense and adhere to the surface of the heat exchanger tubes as they flow through the furnace, forming a hard, poorly conductive ash layer. This leads to two serious consequences: first, the heat exchange efficiency decreases sharply in a short period, resulting in unstable and significantly reduced waste heat recovery; second, the flue resistance increases, affecting the pressure balance within the furnace, and in severe cases, requiring shutdown for manual cleaning. This periodic shutdown for cleaning severely disrupts production continuity, increases maintenance costs and labor intensity, and has become a long-standing pain point in the industry.

[0004] To address the ash accumulation problem, several improvement solutions have been proposed. For example, installing removable filter screens or grilles inside the flue can reduce the contact between large dust particles and the heat exchange tubes through physical interception. However, these solutions have fundamental flaws: first, the filter elements themselves become new points of clogging, requiring periodic shutdowns for disassembly and cleaning, failing to achieve "online maintenance"; second, they only provide passive interception, failing to improve the heat transfer efficiency of the heat exchange process and not differentiating the grade (temperature) of the flue gas heat energy; and third, the recovered heat is utilized in a crude manner, failing to match the precise heat requirements of the furnace's temperature zone, leaving significant room for improvement in the overall system energy efficiency.

[0005] Therefore, there is an urgent need in this field for an innovative and comprehensive solution that can not only solve the problem of ash blockage in heat exchange areas in a long-term and online manner, but also achieve efficient and tiered recovery of waste heat from flue gas, and accurately and intelligently feed the recovered heat back to the gradient heating process of the melting furnace, thereby maximizing energy utilization efficiency while ensuring production continuity. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an integrated gradient heating and high-efficiency heat exchange device for sodium silicate melting furnace, so as to solve the problems of easy blockage, inconvenient ash removal, low heat recovery efficiency and poor coupling with the process in the flue gas heat exchange system.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] An integrated gradient heating and high-efficiency heat exchange device for a sodium silicate melting furnace includes a sodium silicate melting furnace body, wherein the melting furnace body is sequentially provided with a preheating zone, a melting zone, a clarification zone and a heat preservation zone along the material flow direction, and further includes:

[0009] A flue gas diversion and collection system includes a high-temperature flue and a medium-temperature flue that are respectively connected to the melting zone and the clarification zone, and the high-temperature flue and the medium-temperature flue merge into a main flue downstream;

[0010] A cascade heat exchange and purification system includes a high-temperature section heat exchanger installed in the high-temperature flue and at least two parallel switchable filter heat exchange modules installed in the medium-temperature flue.

[0011] The switchable filter heat exchange module includes a module valve, a module housing, and a composite functional filter body disposed within the housing.

[0012] The composite functional filter body includes a main filter plate with tapered streamlined mesh, a dust-repellent and lubricating coating applied to the surface of the filter plate, and an auxiliary heat exchange fin assembly disposed on the downstream side of the filter plate.

[0013] The self-cleaning actuator, which is configured corresponding to each of the switchable filter heat exchange modules, includes a high-frequency mechanical vibrator acting on the module housing and a pulse air wave cleaning nozzle pointing to the composite functional filter.

[0014] The intelligent heat feedback system includes a high-temperature heat medium circuit connected to the outlet of the high-temperature section heat exchanger, and a medium-temperature hot air circuit connected to the outlet of the medium-temperature flue after purification.

[0015] The online monitoring and control system includes a central controller, a differential pressure sensor for monitoring the resistance of each filter heat exchange module, and temperature sensors located in each temperature zone of the melting furnace; the central controller is signal-connected to the module valves, the self-cleaning actuator, and the regulating valves located in the flue gas diversion and collection system and the heat intelligent feedback system.

[0016] Optionally, the cross-sectional shape of the tapered streamlined mesh is circular, square, or hexagonal, and its flow cross-section continuously decreases from the flue gas inlet side to the outlet side, with a contraction angle of 15-30 degrees.

[0017] Optionally, the dust-repellent and slip-enhancing coating is a polytetrafluoroethylene, fluorocarbon resin-based, or silicone resin-based coating with a thickness of 10-50 μm.

[0018] Optionally, the auxiliary heat exchange fin assembly is connected to the main filter plate by thermocompression welding, brazing, or by a high thermal conductivity interface material.

[0019] Optionally, the blowing medium of the pulse air wave cleaning nozzle is dry compressed air, nitrogen or superheated steam, and the pulse pressure is 0.5-0.8 MPa.

[0020] Optionally, the high-temperature section heat exchanger is a finned tube heat exchanger or a heat pipe heat exchanger; the heat medium in the high-temperature heat medium circuit is heat transfer oil or high-pressure water / steam.

[0021] Optionally, the high-temperature heat transfer medium circuit is connected to the auxiliary heaters of the melting zone and the clarifying zone; the medium-temperature hot air circuit is connected to the air distribution device of the preheating zone.

[0022] Optionally, the online monitoring and control system further includes a flue gas composition analyzer installed on the main flue; the central controller is configured to trigger the self-cleaning program of the corresponding module according to the differential pressure sensor signal, and dynamically adjust the inlet opening and heat distribution ratio of the high-temperature flue and / or medium-temperature flue according to the temperature sensor signal and / or flue gas composition signal.

[0023] Optionally, the intelligent control method of the device includes the following steps:

[0024] S1: Real-time monitoring of the pressure difference between the inlet and outlet of each switchable filter heat exchange module;

[0025] S2: When the differential pressure of any module exceeds the preset threshold, control its module valve to close and take it offline; S3: Sequentially trigger the high-frequency mechanical vibration and pulse air wave cleaning operation of the offline module;

[0026] S4: After the dust removal is completed, control the valve of this module to open, so that it can start running online again;

[0027] S5: Real-time monitoring of the temperature in the preheating zone, melting zone, and refining zone of the melting furnace;

[0028] S6: Based on the deviation between the target temperature and the actual temperature in each temperature zone, dynamically adjust the inlet opening of the high-temperature flue and the medium-temperature flue, and adjust the flow distribution valves of the high-temperature heat medium circuit and the medium-temperature hot air circuit in conjunction.

[0029] Compared with the prior art, the present invention has the following significant technical effects:

[0030] Effectively solves clogging and achieves online self-cleaning: By adopting a composite filter body with integrated tapered pore structure, dust-repellent coating and heat exchange fins, and combined with intelligent dust removal technology based on differential pressure feedback, the tendency of filter elements to clog is significantly reduced, realizing automatic dust removal and continuous operation without stopping the machine, and extending the maintenance cycle.

[0031] Achieving efficient utilization of waste heat from flue gas in stages: By separating high- and medium-temperature flue gas and performing targeted heat exchange, the recovered high- and low-grade heat is precisely supplied to the high-temperature process zone and material preheating zone of the melting furnace, respectively, thereby improving the grade matching of heat energy recovery and the overall energy efficiency of the system.

[0032] Enhance system automation and operational stability: By integrating sensing and control systems, real-time monitoring of filter blockage status, automatic dust removal triggering, and dynamic distribution of recovered heat are achieved, enabling the waste heat recovery system to operate in coordination with the main process, thereby improving the level of automation and process stability.

[0033] The structure is reasonable and economical: the unit adopts a modular design, which facilitates maintenance. Its long-term stable operation reduces the frequency and cost of downtime for cleaning, while the recovered heat is directly reused in the production process, reducing external energy consumption. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure and process connection of the integrated device of the present invention.

[0035] Figure 2 This is a cross-sectional view of the switchable filter heat exchange module in this invention.

[0036] Figure 3 for Figure 2 A partially enlarged schematic diagram of the composite functional filter.

[0037] Figure 4 This is a block diagram illustrating the logic control principle of the online monitoring and control system of the present invention.

[0038] Explanation of the labels in the diagram:

[0039] 1-Sodium silicate melting furnace body; 101-Preheating zone; 102-Melting zone; 103-Refining zone; 104-Insulation zone; 201-High-temperature flue; 202-Medium-temperature flue; 203-First electric regulating valve; 204-Second electric regulating valve; 205-Main flue; 206-Induced draft fan; 301-High-temperature section heat exchanger; 302-Switchable filter heat exchange module; 3021-Module valve; 3022-Module shell; 3023-Composite functional filter body; 302 3a-Main filter screen (with tapered holes), 3023b-Dust-reducing and lubrication-enhancing coating, 3023c-Auxiliary heat exchange fin assembly, 3023d-Tapered streamlined mesh, 3031-High-frequency mechanical vibrator, 3032-Pulse air wave cleaning nozzle; 401-High-temperature heat medium circulation pump and pipeline, 402-Medium-temperature hot air fan and pipeline, 403-Auxiliary heater, 404-Air distribution device; 501-Central controller, 502-Differential pressure sensor, 503-Temperature sensor. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] Example 1:

[0042] Reference Figures 1 to 4 This embodiment provides an integrated device for a large gas-fired sodium silicate melting furnace.

[0043] The sodium silicate melting furnace body 1 is a tunnel kiln structure. In the flue gas diversion and collection system, the high-temperature flue gas (about 1350°C) at the top of the melting zone 102 enters the high-temperature flue duct 201 through the first electric regulating valve 203; the medium-temperature flue gas (about 1150°C) at the top of the clarification zone 103 enters the medium-temperature flue duct 202 through the second electric regulating valve 204.

[0044] The high-temperature section heat exchanger 301 of the cascade heat exchange and purification system uses a heat pipe heat exchanger with potassium as the working fluid. The medium-temperature section is equipped with three parallel switchable filter heat exchange modules 302. The composite functional filter 3023 within the module has a main filter plate 3023a made of 310S stainless steel with a tapered streamlined mesh (inlet φ2mm, outlet φ1.5mm) formed by photochemical etching, and the surface is coated with a 30μm thick PTFE-based dust-repellent coating 3023b. A copper auxiliary fin assembly 3023c is welded downstream. Each module is equipped with an integrated dust collector 303, which includes an electromagnetic vibrator 3031 and a 0.7MPa pulsed air nozzle 3032.

[0045] The intelligent heat feedback system delivers heat transfer oil at approximately 400°C in the high-temperature heat transfer medium circuit 401 to the natural gas auxiliary heater 403 in the melting and clarifying zones, replacing approximately 20% of natural gas consumption. The medium-temperature hot air circuit 402 delivers clean hot air at approximately 500°C to the perforated plate air distribution device 404 at the bottom of the preheating zone 101.

[0046] The online monitoring and control system uses a PLC as the central controller 501. When the differential pressure sensor 502 detects that the resistance of module 1 302 exceeds 600Pa, the PLC automatically executes the following: closing its module valve 3021, starting the vibrator 3031 (vibrating for 5 seconds) and the pulse nozzle 3032 (blowing 3 times), and then opening the module valve. The entire process takes about 30 seconds, during which the other modules maintain system operation. Simultaneously, based on feedback from the temperature sensors 503 of each temperature zone, the PLC fine-tunes the opening of regulating valves 203 and 204 in real time to achieve dynamic balance.

[0047] Operational Results: After commissioning, the filtration and heat exchange module operated continuously for over 180 days without manual intervention, and the system resistance remained stable. The average inlet temperature of the preheating zone increased by more than 180°C, the overall natural gas consumption of the melting furnace decreased by approximately 17%, saving more than 1,500 tons of standard coal annually, and the investment payback period was less than 2 years.

[0048] Example 2:

[0049] Based on Example 1, optimizations were made for melting furnaces that use heavy oil as fuel and have a higher dust load.

[0050] The main filter plate 3023a of the composite functional filter body 3023 is made of porous silicon carbide ceramic to improve wear resistance and thermal shock resistance.

[0051] The pulse air wave cleaning nozzle 3032 was replaced with superheated steam (300℃) to prevent the low-temperature gas from causing the heavy oil ash to stick together.

[0052] An air preheater is added to the medium-temperature hot air circuit 402 of the heat intelligent feedback system. By utilizing part of the high-temperature heat medium (through a three-way valve), the temperature of the hot air sent to the preheating zone is further increased to 600°C to cope with raw materials with higher moisture content.

[0053] In intelligent control systems, the risk of corrosion or special scaling can be predicted in advance by analyzing the pressure difference growth trend and fuel sulfur content data.

[0054] Example 3:

[0055] An economical and simplified solution for retrofitting existing melting furnaces is provided. The independent high-temperature flue 201 and its heat exchanger 301 are eliminated, and all recovered heat is concentrated through the medium-temperature section.

[0056] The switchable filter heat exchange module 302 is simplified to two, and the composite function filter body 3023 retains only the tapered hole main mesh plate 3023a and the basic rapping dust removal function.

[0057] The intelligent heat feedback system is simplified, and the recovered hot air is directly used for centralized heating in the factory area during winter, rather than being reused in the melting furnace.

[0058] The online monitoring and control system is simplified to a basic differential pressure over-limit alarm and timed dust removal program.

[0059] Although this solution reduces the energy efficiency integration, the core functions of "intelligent anti-clogging and online ash removal" are retained, which can solve the problem of ash accumulation and production stoppage at the lowest cost. It is particularly suitable for the transformation of small and medium-sized or intermittently operating furnaces.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An integrated gradient heating and high-efficiency heat exchange device for a sodium silicate melting furnace, comprising a sodium silicate melting furnace body, wherein the melting furnace body is sequentially provided with a preheating zone, a melting zone, a clarification zone, and a heat preservation zone along the material flow direction, characterized in that, Also includes: A flue gas diversion and collection system includes a high-temperature flue and a medium-temperature flue that are respectively connected to the melting zone and the clarification zone, and the high-temperature flue and the medium-temperature flue merge into a main flue downstream; A cascade heat exchange and purification system includes a high-temperature section heat exchanger installed in the high-temperature flue and at least two parallel switchable filter heat exchange modules installed in the medium-temperature flue. The switchable filter heat exchange module includes a module valve, a module housing, and a composite functional filter body disposed within the housing. The composite functional filter body includes a main filter plate with tapered streamlined mesh, a dust-repellent and lubricating coating applied to the surface of the filter plate, and an auxiliary heat exchange fin assembly disposed on the downstream side of the filter plate. The self-cleaning actuator, which is configured corresponding to each of the switchable filter heat exchange modules, includes a high-frequency mechanical vibrator acting on the module housing and a pulse air wave cleaning nozzle pointing to the composite functional filter. The intelligent heat feedback system includes a high-temperature heat medium circuit connected to the outlet of the high-temperature section heat exchanger, and a medium-temperature hot air circuit connected to the outlet of the medium-temperature flue after purification. The online monitoring and control system includes a central controller, a differential pressure sensor for monitoring the resistance of each filter heat exchange module, and temperature sensors located in each temperature zone of the melting furnace; the central controller is signal-connected to the module valves, the self-cleaning actuator, and the regulating valves located in the flue gas diversion and collection system and the heat intelligent feedback system.

2. The apparatus according to claim 1, characterized in that, The cross-sectional shape of the tapered streamlined mesh is circular, square, or hexagonal, and its flow cross-section continuously decreases from the flue gas inlet side to the outlet side, with a contraction angle of 15-30 degrees.

3. The apparatus according to claim 1, characterized in that, The dust-repellent and slip-enhancing coating is a polytetrafluoroethylene, fluorocarbon resin-based, or silicone resin-based coating with a thickness of 10-50 μm.

4. The apparatus according to claim 1, characterized in that, The auxiliary heat exchange fin assembly is connected to the main filter plate by hot-press welding, brazing, or through a high thermal conductivity interface material.

5. The apparatus according to claim 1, characterized in that, The blowing medium of the pulse air wave cleaning nozzle is dry compressed air, nitrogen or superheated steam, and the pulse pressure is 0.5-0.8MPa.

6. The apparatus according to claim 1, characterized in that, The high-temperature section heat exchanger is a finned tube heat exchanger or a heat pipe heat exchanger; the heat medium in the high-temperature heat medium circuit is heat transfer oil or high-pressure water / steam.

7. The apparatus according to claim 1, characterized in that, The high-temperature heat transfer medium circuit is connected to the auxiliary heaters of the melting zone and the clarifying zone; the medium-temperature hot air circuit is connected to the air distribution device of the preheating zone.

8. The apparatus according to claim 1, characterized in that, The online monitoring and control system also includes a flue gas composition analyzer installed on the main flue; the central controller is configured to trigger the self-cleaning program of the corresponding module according to the differential pressure sensor signal, and dynamically adjust the inlet opening and heat distribution ratio of the high-temperature flue and / or medium-temperature flue according to the temperature sensor signal and / or flue gas composition signal.

9. A smart control method for the device as described in any one of claims 1-8, characterized in that, Includes the following steps: S1: Real-time monitoring of the pressure difference between the inlet and outlet of each switchable filter heat exchange module; S2: When the differential pressure of any module exceeds the preset threshold, control its module valve to close and take it offline; S3: Sequentially trigger the high-frequency mechanical vibration and pulse air wave cleaning operation of the offline module; S4: After the dust removal is completed, control the valve of this module to open, so that it can start running online again; S5: Real-time monitoring of the temperature in the preheating zone, melting zone, and refining zone of the melting furnace; S6: Based on the deviation between the target temperature and the actual temperature in each temperature zone, dynamically adjust the inlet opening of the high-temperature flue and the medium-temperature flue, and adjust the flow distribution valves of the high-temperature heat medium circuit and the medium-temperature hot air circuit in conjunction.

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