Drying system based on kiln waste gas sensible heat recycling

Abstract

The drying system based on kiln waste gas sensible heat recycling comprises a kiln, a waste gas fan, a hot blast stove and a drying tower, an air inlet is formed in the position, close to the top, of one side of the drying tower, and an air outlet is formed in the position, close to the bottom, of the other side of the drying tower; the waste gas end of the kiln is connected with the air inlet end of the waste gas fan through a waste gas pipeline, the air outlet end of the waste gas fan is communicated with the air inlet through an air inlet pipeline, and the hot blast stove is communicated with the air inlet pipeline. The drying system based on kiln waste gas sensible heat recycling has the advantages of being low in energy consumption, small in damage to materials, high in heat efficiency, safe and reliable.

Description

Technical Field

[0001] The utility model belongs to the technical field of drying, and in particular relates to a drying system based on sensible heat recovery and utilization of kiln waste gas. Background Art

[0002] The drying process of materials is a process in which the surface moisture of materials evaporates through direct heat exchange between materials and hot gas. The unit heat consumption and drying rate of the dried materials are mainly determined by the type and properties of the materials, the amount of water content and the performance of the drying equipment used. The equipment used for drying mainly includes: rotary drying tower, gravity drying kiln, fluidized drying tower, boiling drying tower, traditional vertical drying tower and new automatic vertical drying tower.

[0003] At present, the most widely used drying tower in the metallurgical industry is the rotary drying tower, which is divided into single-drum and three-drum. The drying method of the drying tower is divided into two types: downstream and countercurrent, depending on the flow direction of the material and the flow direction of the flue gas. The advantages of the rotary drying tower are large production capacity, continuous operation, and simple structure; the disadvantages are large equipment, large one-time investment, difficult installation and disassembly, large heat loss, high energy consumption, low thermal efficiency, and excessive breakage rate (because the drum continuously turns the material, the breakage rate of the rotary drying tower is relatively high, the breakage rate of the single-drum rotary drying tower during drying is between 20% and 25%, and the breakage rate of the three-drum drying tower is between 10% and 15%); in addition, when the rotary drying tower is drying materials such as semi-coke, the semi-coke is exposed to high-temperature heat flow for a long time, which is easy to catch fire and cause safety accidents.

[0004] Based on the above characteristics of the rotary drying tower, it is very slow to meet the drying needs of some specific materials (such as the drying of blue charcoal in the calcium carbide industry, which requires a very small breakage rate and also requires that the blue charcoal be prevented from being exposed to hot air for a long time during the drying process). Therefore, it is necessary to develop a new drying system that has the advantages of low energy consumption, little damage to materials, high thermal efficiency, and safety and reliability. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide a drying system based on the recovery and utilization of sensible heat of kiln exhaust gas, which has the advantages of low energy consumption, little damage to materials, high thermal efficiency, safety and reliability.

[0006] The utility model solves the above problems through the following technical means:

[0007] A drying system based on the recovery and utilization of sensible heat of kiln exhaust gas comprises a kiln, an exhaust gas blower, a hot air furnace and a drying tower, wherein an air inlet is arranged near the top of one side of the drying tower, and an air outlet is arranged near the bottom of the other side of the drying tower; the exhaust gas end of the kiln is connected to the air inlet end of the exhaust gas blower through an exhaust gas pipe, the air outlet end of the exhaust gas blower is connected to the air inlet through an air intake pipe, and the hot air furnace is connected to the air intake pipe.

[0008] Furthermore, it also includes a heat exchanger, which is connected to the kiln through a heat exchange pipe. The air inlet end of the heat exchanger is connected to a driving fan through a pipe, and the air outlet end of the heat exchanger is connected to the exhaust gas pipe through a pipe.

[0009] Furthermore, a feed hopper is arranged at the top of the drying tower, and a discharge hopper is arranged at the bottom.

[0010] Furthermore, a material distribution cone is arranged below the feed hopper in the drying tower.

[0011] Furthermore, a guide cone is provided in the drying tower.

[0012] Furthermore, the air outlet is sequentially connected to a cyclone dust collector, a bag dust collector and an induced draft fan through pipelines.

[0013] Beneficial effects of the utility model:

[0014] 1. The drying system of the present application makes full use of the sensible heat of the exhaust gas and effectively saves the drying energy consumption;

[0015] 2. In the drying tower of the present application, the drying hot air flow flows in the same direction as the drying material, and under the action of the material dividing cone and the guide cone, they are fully in contact, which effectively improves the thermal efficiency and reduces the breakage rate of the material.

[0016] 3. The drying tower of the present application has high heat exchange efficiency, the inlet temperature is controlled between 250 and 280°C, and the outlet temperature is generally between 125 and 135°C. The low temperature does not require high high temperature resistance of steel, and only considers the wear resistance of steel, so the one-time cost is low.

[0017] 4. The drying tower of the present application has good overall sealing, an external insulation layer, and low heat loss. The traditional vertical drying tower is equipped with a boiling furnace at the bottom, and the hot air flow and the material are dried by reverse heat exchange; the hot air flow first flows upward from the lower section, and the wet-based blue charcoal moves from top to bottom. When the hot air flow contacts the uppermost material, the temperature drops, affecting the drying efficiency. When the blue charcoal that has evaporated some of its water runs to the lower part, it is easy to catch fire when it contacts the high-temperature air flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 It is a schematic diagram of a preferred embodiment of the utility model;

[0021] Figure 2 It is a structural diagram of the drying tower. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0024] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] like Figure 1 to Figure 2 As shown, the utility model discloses a drying system based on the recovery of sensible heat of kiln exhaust gas, including a kiln 1, an exhaust gas fan 5, a hot air furnace 6 and a drying tower 8, wherein an air inlet 803 is arranged near the top on one side of the drying tower, and an air outlet 805 is arranged near the bottom on the other side of the drying tower; the exhaust gas end of the kiln is connected to the air inlet end of the exhaust gas fan through the exhaust gas pipe 3, the air outlet end of the exhaust gas fan is connected to the air inlet through the air inlet pipe 7, and the hot air furnace is connected to the air inlet pipe.

[0027] It also includes a heat exchanger 2, which is connected to the kiln through a heat exchange pipe, the air inlet of the heat exchanger is connected to a driving fan 4 through a pipe, and the air outlet of the heat exchanger is connected to the exhaust pipe through a pipe, so that waste heat recovery of the heat exchanger can be achieved.

[0028] The top of the drying tower is provided with a feed hopper 801, and the bottom is provided with a discharge hopper 806.

[0029] A material distribution cone 802 is provided below the feed hopper in the drying tower.

[0030] A guide cone 804 is provided in the drying tower.

[0031] The air outlet is connected to a cyclone dust collector 9, a bag dust collector 10 and an induced draft fan 11 in sequence through pipelines.

[0032] During drying, the material to be dried (such as semi-coke) is first sent to the storage bin in front of the drying tower through a conveyor belt, and then sent to the bucket elevator through the vibrating feeder and conveyor belt under the storage bin, and then sent to the feed hopper at the top of the drying tower by the bucket elevator. An electro-hydraulic gate valve is provided at the bottom of the feed hopper, which is interlocked with the level meter in the drying tower bin; when the bottom material level appears, the electro-hydraulic gate valve is opened, and the semi-coke falls into the drying tower bin due to gravity, and air infiltration is prevented during this process. The material to be dried descends from the drying tower bin to the dividing cone, and the material is evenly distributed to the drying channel of the drying section through the dividing cone. The material slowly descends and exchanges heat with the downward-flowing hot mixed gas for drying. During the heat exchange process, the moisture is taken away with the hot mixed gas.

[0033] During the drying process, the blue carbon with high moisture content just entering the drying section exchanges heat with the mixed gas at 280℃ at the inlet to remove most of the moisture; the hot air then flows to the middle through the guide plate to avoid long-term contact of high temperature with the material and cause fire. At the same time, this process eliminates the infiltration of air, which effectively solves the fire caused by the infiltration of air in the traditional vertical drying tower.

[0034] When the airflow flows to the middle, due to the action of the guide cone and the induced draft fan, the airflow is forced to flow downward, continue to exchange heat with the material, and take away the moisture in the material. The dried material enters the lower discharge hopper, falls onto the conveyor belt through the electromagnetic feeder, and is sent to the silo for storage after screening by the slide screen. The vibrating feeder is frequency-controlled and interlocked with the temperature of the drying section. The temperature and pressure signals collected at point 9 of the drying tower are sent to the main control room. The adjustment of the vibrating feeder is determined by the measured data of the material outlet temperature and humidity sensor. When the humidity is less than 1% and the outlet temperature is high (waste gas temperature 125-135°C, outlet material temperature 80-90°C), the frequency converter of the vibrating feeder is automatically adjusted to achieve control of temperature, humidity and output.

[0035] The drying heat source mainly comes from the exhaust gas of the kiln, with an exhaust gas volume of 46000Nm3 / h, the temperature is generally between 150 and 200℃. A hot air furnace is set in front of the drying tower (select burner model: YDZM-150), and the heat load specification is 150×104kcal. The furnace temperature of the hot air furnace is between 900 and 1200℃, and the temperature drops to between 250 and 300℃ (generally controlled at around 280℃) after the blast and the kiln tail gas are mixed. The mixed hot gas enters the drying tower through the air inlet on one side of the top of the drying tower. Before the mixed hot gas enters the drying tower, the automatic regulating valve controls the air volume, and temperature and pressure measuring points are set for real-time monitoring. The pressure is detected by the negative pressure of the drying tower, and the induced draft fan inverter is automatically adjusted to achieve the flow rate adjustment of the exhaust gas. After the exhaust gas enters the drying tower, the guide plate in the material distribution cone evenly distributes the exhaust gas to the drying section of the drying tower. Since there are three guide cones in the drying section, the airflow first passes through the first guide cone and enters the slowly descending material layer to contact with the material downstream, heat exchange and dry to remove moisture. The exhaust gas descends to the guide plate. Due to the action of the guide plate, the hot air flow is forced to flow to the center of the drying tower (longitudinal heat exchange is performed in this process, but the time is short). When the airflow is in the center of the drying tower, under the action of the second guide cone, the airflow continues to flow to both sides and downward, and heat exchange is performed downstream again. When the airflow flows through the third guide cone, it is drawn to the flue by the suction of the induced draft fan, and after passing through the cyclone dust collector and bag dust collector, it is discharged from the chimney of the induced draft fan. In this way, the exhaust gas reciprocates in the drying tower for 4 cycles to exchange heat and remove moisture. The outlet temperature of the exhaust gas is generally between 125 and 135°C, with high heat exchange efficiency and low tail gas temperature, which reduces the difficulty of dust removal.

[0036] The drying system of this application has the following characteristics:

[0037] Power saving: The materials are sent to the feed hopper by the bucket elevator, and the gate is automatically opened to discharge the materials through the material level meter. The materials are dried by their own gravity. The adjustable damping coefficient is adopted, which not only effectively controls dust and avoids wind tunnels, but also saves a lot of power for the rotary and environmental protection systems. Compared with the φ2.4×18m rotary drying tower with the same output, the new drying tower can save 5-10KW of electricity per ton of dry material and more than 3000KW.h of electricity per day.

[0038] Energy saving: The use of sensible heat recovery technology for industrial exhaust gas reduces energy consumption and equipment investment, reduces production costs and is environmentally friendly. The heat generating area is surrounded by materials, and any heat must pass through the materials to be dried to dissipate. This has changed the history of using a large amount of hot air to filter materials and low thermal energy utilization. The drying process uses a large amount of materials to filter hot air, and its thermal energy utilization rate can be as high as 96%. Compared with a φ2.4×18m rotary drying tower, it saves 1200Nm of semi-coal gas with a calorific value of 1900kcal per hour. 3 / h (single drum 15 / h rotary drying tower burner requires 2000Nm gas3 / h, the three-drum 15 / h rotary drying tower burner requires 3000Nm of gas 3 / h, while the burner equipped with the Xinxing vertical drying tower hot air furnace requires a gas volume of 799Nm 3 / h).

[0039] Drying quality: The material stepless speed unloading system is controlled according to the material drying detection system to achieve the coordination between quality control and output, and the drying requirements can be changed at any time and the drying quality can be effectively controlled. This has rewritten the history of drying quality being affected by unstable initial moisture. No matter how much the initial moisture of the material is, it will be the desired amount after drying, and it can be adjusted and controlled at any time.

[0040] Adaptability: The automatic control of the temperature and humidity switching system not only effectively controls the drying quality and prevents material jamming and blocking, but also significantly improves the adaptability of the equipment to materials with different moisture contents.

[0041] Environmentally friendly emissions: The kiln exhaust is used as a heat source for drying. A large amount of materials are filtered in the hot air. The drying tower is well sealed and dust-removed. Wind tunnels and dust are completely avoided. The system comes with dust collection equipment, and dust emissions meet the standards. This has changed the situation of large investment in environmental protection equipment and high operating costs in traditional drying systems.

[0042] Equipment maintenance: The whole set of automatic systems for heating, detection and control is adopted to coordinate the production capacity and maintenance of the equipment. Under normal use, the equipment hardly needs maintenance within 3 to 5 years. This not only improves the operation rate of the equipment, but also greatly reduces the maintenance cost of the equipment, which is about one tenth of that of the rotary drying tower.

[0043] Floor space and investment: vertical and built-in heating equipment is used, and the floor space is 20% of the rotary drying tower. The scientific design is not only reasonable in structure, but also reduces the system investment by more than 50% for the manufacturer.

[0044] Production operation: The entire drying process fully adopts an automated detection and control system, which can realize both centralized control and independent operation of a single machine. It not only reduces the labor intensity of workers, but also makes the quality, output and energy consumption of the equipment in the production process more coordinated, more reasonable and more scientific.

[0045] The process comparison between the drying tower of this application and other drying towers is shown in Table 1:

[0046]

[0047] Table 1

[0048] The investment and production costs of the drying tower of this application are compared with those of other drying towers, as shown in Table 2:

[0049]

[0050] Table 2

[0051] The cost saving comparison between the drying tower of the present application and other drying towers is shown in Table 3:

[0052]

[0053] Table 3

[0054] Note: Taking 500,000 tons of semi-coke dried annually as an example, the market price of wet semi-coke is 900 yuan / ton, and the market price of semi-coke foam is 500 yuan / ton. The total cost of all drying towers minus the total cost of the new drying tower is the "comparison difference".

[0055] From the comparison table 2 of investment and production cost, it can be seen that the power consumption per ton of single-drum rotary drying tower is 14.4KW.h, the power consumption per ton of three-drum rotary drying tower is 20KW.h, the traditional vertical drying tower is 15KW.h, and the new vertical drying tower is 10KW.h. The new vertical drying tower saves electricity per year compared with the three-drum rotary drying tower: 180*24*300*=1.296 million KW.h, and saves gas 2201*24*300=15.8472 million Nm 3 (Gas calorific value is 1900Kcal, annual operation days are calculated as 300 days). According to the statistics of Table 3 on the cost saving of the new automatic vertical drying tower and other drying towers, the amount of wet-based semi-coal is increased due to the damage rate, and this part of the increased amount is turned into cheap semi-coal foam, while the damaged semi-coal foam cannot be used as carbon material and can only be used as fuel for heating. Therefore, the cost generated by the damage rate of the single-cylinder drying tower is 60.8 million more per year than that of the new vertical drying tower. Therefore, the new vertical drying tower has great advantages in energy saving.

[0056] Through the comparison of drying towers and the summary of actual production experience, the rotary drying tower has a wide range of adaptability as the production capacity increases, but due to the high heat loss, high equipment investment and high breakage rate, it is not conducive to the drying production of semi-coke. The new automatic vertical drying uses the tail gas of the kiln for drying, and the comprehensive utilization of the tail gas of the kiln turns waste into treasure, greatly reducing production costs and benefiting the environment. In addition, the new vertical drying tower has the advantages of low one-time investment, small footprint, energy saving, low production cost, wide application range, simple maintenance and operation, and low failure rate. It has gradually developed and matured as a new technology and new process in the carbon drying industry. It will eventually become a leader in the carbon drying industry and be widely used.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A drying system based on sensible heat recovery of kiln exhaust gas, characterized in that: It includes a kiln, an exhaust gas fan, a hot air furnace and a drying tower. An air inlet is arranged near the top of one side of the drying tower, and an air outlet is arranged near the bottom of the other side of the drying tower. The exhaust gas end of the kiln is connected to the air inlet end of the exhaust gas fan through an exhaust gas pipe, and the air outlet end of the exhaust gas fan is connected to the air inlet through an air intake pipe, and the hot air furnace is connected to the air intake pipe.

2. The drying system based on sensible heat recovery of kiln exhaust gas according to claim 1 is characterized in that: It also includes a heat exchanger, which is connected to the kiln through a heat exchange pipe. The air inlet end of the heat exchanger is connected to a driving fan through a pipe, and the air outlet end of the heat exchanger is connected to an exhaust gas pipe through a pipe.

3. The drying system based on sensible heat recovery of kiln exhaust gas according to claim 2 is characterized in that: The top of the drying tower is provided with a feed hopper, and the bottom is provided with a discharge hopper.

4. The drying system based on sensible heat recovery of kiln exhaust gas according to claim 3 is characterized in that: A material distribution cone is arranged below the feed hopper in the drying tower.

5. The drying system based on sensible heat recovery of kiln exhaust gas according to claim 4 is characterized in that: A guide cone is arranged in the drying tower.

6. The drying system based on sensible heat recovery of kiln exhaust gas according to any one of claims 1 to 5, characterized in that: The air outlet is sequentially connected to a cyclone dust collector, a bag dust collector and an induced draft fan through pipelines.

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