Biomass fuel pretreatment device capable of efficiently utilizing flue gas waste heat

Abstract

The invention discloses a biomass fuel pretreatment device capable of efficiently utilizing flue gas waste heat. The biomass fuel pretreatment device comprises an efficient air pre-heater, a rotary roller dryer, a cyclone separator and a water film dust remover. The efficient air pre-heater is provided with a flue gas inlet used for introducing flue gas so as to heat air, and the heated air is conveyed to the rotary roller dryer; and after the biomass wet fuel enters the rotary roller dryer, moisture in the biomass fuel is taken away by hot air to form dry fuel, and the dry fuel is discharged from the dry fuel outlet. Air is heated by recovering flue gas waste heat, compared with flue gas, dried air has the advantages of being low in moisture content and large in drying moisture carrying capacity, moisture of biomass fuel can be better taken away, the moisture content of the biomass fuel is reduced, the combustion energy efficiency of the biomass fuel is improved, the combustion efficiency is improved, and the carbon-saving characteristic of biomass energy is fully played.

Description

Technical Field

[0001] The present invention belongs to the technical field related to biomass pretreatment, and in particular relates to a biomass fuel pretreatment device which efficiently utilizes flue gas waste heat. Background Art

[0002] Industrial production is one of the main sources of carbon emissions, and it plays an important role in promoting green and low-carbon development in the industrial sector. As the main source of electricity in my country, thermal power accounts for more than 50% of the country's total installed capacity, and the industry is under tremendous pressure to reduce carbon emissions. my country has the world's largest clean coal power supply system. The coupled combustion of coal and biomass is a powerful response. Existing coal-fired power plants can be used to burn new fuels without large-scale technical transformation or investment. The technical risks and additional investment are small, and the flexibility is high. It is an economically feasible power generation solution at this stage. The moisture content of fuel in biomass power plants varies widely. During the harvest season, the initial moisture content of crop rice straw is usually above 40%. Directly entering the furnace affects the efficiency and stable operation of the boiler. The flue gas composition of the boiler mixed with biomass is unstable and has a high moisture content. The direct use of flue gas to dry biomass is not effective. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a biomass fuel pretreatment device that efficiently utilizes flue gas waste heat, which recovers flue gas waste heat with high efficiency and low resistance to preheat air to dry biomass, thereby achieving low-energy consumption pretreatment of biomass to improve quality and efficiency.

[0004] To achieve the above object, the technical solution of the present invention is:

[0005] A biomass fuel pretreatment device for efficiently utilizing flue gas waste heat comprises a high-efficiency air preheater, a rotary drum dryer, a cyclone separator and a water film dust collector; wherein:

[0006] The high-efficiency air preheater is provided with a flue gas inlet, a flue gas outlet, an air inlet and an air outlet, the flue gas outlet is connected to the water film dust collector, and the air outlet is connected to the rotary drum dryer;

[0007] The rotary drum dryer is provided with a biomass wet fuel inlet, a dry fuel outlet and an exhaust gas outlet, wherein the biomass wet fuel inlet is used to receive the biomass wet fuel, the dry fuel outlet is used to discharge the dry fuel, and the exhaust gas outlet is connected to the cyclone separator;

[0008] The cyclone separator is provided with a gas outlet and a fuel dust outlet, the gas outlet is connected to the water film dust collector, and the fuel dust outlet is connected to the rotary drum dryer.

[0009] Optionally, the high-efficiency air preheater is a pure countercurrent three-dimensional variable space heat exchanger, and the flue gas and air flow in opposite parallel directions.

[0010] Optionally, the biomass fuel pretreatment device for efficiently utilizing flue gas waste heat also includes a screw feeder, the discharge port of the screw feeder is connected to the biomass wet fuel inlet of the rotary drum dryer to deliver the biomass wet fuel into the rotary drum dryer; the screw feeder is also connected to the cyclone separator, and the fuel dust separated by the cyclone separator is sent back to the rotary drum dryer through the screw feeder.

[0011] Optionally, the rotary drum dryer is a reverse parallel friction flow heat exchanger, heated by upstream air, and the wet biomass fuel rolls and turns in the drum to mix with the hot air, and the overall direction of movement is opposite to the air flow direction.

[0012] Optionally, the high-efficiency air preheater includes an outer shell, in which an upper tube plate and a lower tube plate are arranged, the area between the outer shell and the upper tube plate serves as a flue gas inlet, the area between the lower tube plate and the outer shell serves as a flue gas outlet, and the flue gas outlet is connected to a cyclone separator; an air inlet and an air outlet are respectively arranged on both sides of the outer shell, the air inlet is connected to the lower tube plate, the air outlet is connected to the upper tube plate, and air corridors are evenly distributed on the opposite side of the lower tube plate and the upper tube plate; the air corridors are provided with group partitions; the upper tube plate and the lower tube plate are provided with tube holes, and a plurality of spirally deformed tube bundle modules are connected and sealed with the upper and lower tube plates through the tube holes; each spirally deformed tube bundle module is provided with an enclosure.

[0013] Optionally, the biomass fuel pretreatment device for efficiently utilizing waste heat of flue gas further comprises a first induced draft fan, which is disposed in a first pipeline connecting the high-efficiency air preheater and the rotary drum dryer.

[0014] Optionally, the biomass fuel pretreatment device for efficiently utilizing waste heat of flue gas may further include a second induced draft fan, which is disposed in a second pipeline connecting the cyclone separator and the water film dust collector.

[0015] Optionally, the biomass fuel pretreatment device for efficiently utilizing flue gas waste heat further comprises a third induced draft fan, and the third induced draft fan is arranged in a third pipeline connecting the flue gas outlet and the water film dust collector.

[0016] Optionally, the spirally deformed tube bundle module is composed of a plurality of spirally deformed tubes and is bundled with a fixing belt; the flow space ratio of the cold and hot media in the high-efficiency air preheater is adjusted according to the deformation coefficient of the spirally deformed tubes.

[0017] Optionally, a discharge collection trough is provided below the dry fuel outlet.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat provided in this embodiment recycles the high-temperature flue gas after the combustion of biomass fuel, and heats the air by recycling the flue gas waste heat. The dry air has the advantages of low moisture content and large dry moisture carrying capacity relative to the flue gas, and can better remove the moisture of the biomass fuel, reduce the moisture content of the biomass fuel, increase the combustion efficiency of the biomass fuel, improve the combustion efficiency, and give full play to the carbon-saving characteristics of biomass energy. At the same time, by processing the tail gas, the fuel dust in the tail gas can be reused and the pollution to the environment can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a biomass fuel pretreatment device for efficiently utilizing flue gas waste heat provided in an embodiment of the present application;

[0021] Figure 2 This is the front view of the high-efficiency air preheater;

[0022] Figure 3 This is a top view of the high-efficiency air preheater;

[0023] Figure 4 This is a schematic diagram of the installation of the spiral deformation tube bundle module;

[0024] In the figure: 1. High-efficiency air preheater; 2. Rotary drum dryer; 3. Cyclone separator; 4. Water film dust collector; 5. Screw feeder; 6. Discharge collection tank; 7. First induced draft fan; 8. Second induced draft fan; 9. Third induced draft fan. I. First pipeline; II. Second pipeline; III. Third pipeline; 1-1. Smoke inlet; 1-2. Upper tube sheet; 1-3. Air outlet; 1-4. Spiral deformation tube bundle module; 1-5. Fixing belt; 1-6. Shell; 1-7. Lower tube sheet; 1-8. Air inlet; 1-9. Smoke outlet; 1-10. Baffle plate; 1-11. Envelope. DETAILED DESCRIPTION

[0025] Example:

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0027] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does 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 cannot be understood as a limitation on the present application.

[0028] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0029] In this application, unless otherwise clearly specified and limited, if the terms "install", "connect", "connect", "fix" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the above terms can be understood in their specific meanings in this application according to the specific circumstances.

[0030] In this application, unless otherwise clearly specified and limited, if there is a description such as "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, "above", "above" and "above" a first feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "below" and "below" a first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0032] See also Figure 1-4 As shown, the biomass fuel pretreatment device for efficiently utilizing flue gas waste heat provided in this embodiment mainly includes a high-efficiency air preheater 1, a rotary drum dryer 2, a cyclone separator 3 and a water film dust collector 4.

[0033] The high-efficiency air preheater 1 is provided with a flue gas inlet 1-1, a flue gas outlet 1-9, an air inlet 1-8 and an air outlet 1-3; the air inlet 1-8 is used to connect the ambient air, and the flue gas inlet 1-1 is used to connect the flue gas, so that the high-temperature flue gas and the normal-temperature air exchange heat in the high-efficiency air preheater, and the flue gas and tail gas after cooling are directly returned to the water film dust collector or the boiler environmental protection device, and the heated air is transported to the rotary drum dryer 2; the rotary drum dryer 2 is provided with a biomass wet fuel inlet, a dry fuel outlet, and a tail gas outlet. It is used to connect biomass wet fuel. After the biomass wet fuel enters the rotary drum dryer 2, the moisture in the biomass fuel is taken away by hot air to form dry fuel and discharged from the dry fuel outlet, and collected by the discharge collecting tank 6; the dry fuel generates tail gas in the process of discharge, and the tail gas contains part of the carried-out fuel dust and odor. The tail gas enters the cyclone separator 3 through the tail gas outlet to separate the fuel dust in the tail gas, and the separated fuel dust is sent back to the rotary drum dryer 2; the separated tail gas enters the water film dust collector 4, and is filtered by the water film dust collector 4 before being discharged into the atmosphere.

[0034] It can be seen that the biomass fuel pretreatment device for efficiently utilizing flue gas waste heat provided in this embodiment recycles the high-temperature flue gas after the combustion of biomass fuel, and heats the air by recycling the flue gas waste heat. The dry air has the advantages of low moisture content and large dry moisture carrying capacity relative to the flue gas, and can better remove the moisture of the biomass fuel, reduce the moisture content of the biomass fuel, increase the combustion efficiency of the biomass fuel, improve the combustion efficiency, and give full play to the carbon-saving characteristics of biomass energy. At the same time, by processing the tail gas, the fuel dust in the tail gas can be reused and the pollution to the environment can be reduced.

[0035] In a preferred embodiment, the biomass fuel pretreatment device for efficiently utilizing flue gas waste heat also includes a screw feeder 5, the discharge port of the screw feeder 5 is connected to the biomass wet fuel inlet of the rotary drum dryer 2, so as to feed the biomass wet fuel into the rotary drum dryer 2; the screw feeder 5 is also connected to the cyclone separator 3, and the fuel dust separated by the cyclone separator 3 is sent back to the rotary drum dryer 2 through the screw feeder 5. In this way, under the action of the screw feeder 5, the biomass wet fuel / fuel dust can be fed into the rotary drum dryer, while reducing the fuel that is blown back to the feed port by air in a countercurrent state.

[0036] In a specific embodiment, the rotary drum dryer 2 is a reverse parallel friction flow heat exchanger, heated by upstream air, and the wet biomass fuel rolls and turns in the drum to mix with the hot air. The overall direction of movement is opposite to the air flow, so that the air heat can be fully utilized for drying.

[0037] In a specific embodiment, the high-efficiency air preheater 1 is divided into two processes. The media inside and outside the tube are parallel pure countercurrent heat exchange. The high-efficiency air preheater recovers the waste heat in the high-temperature flue gas in depth, thereby preheating the air for drying and heating. The minimum difference between the hot end of the cold and hot media can reach 10℃-20℃. The flue gas exhaust is sent to the water film dust collector through the induced draft fan to absorb odor and then discharged. Specifically, Figure 2-3As shown, the high-efficiency air preheater 1 is a pure countercurrent three-dimensional variable space heat exchanger, including a shell 1-6, on both sides of which are respectively provided with an air outlet 1-3 and an air inlet 1-8; an upper tube sheet 1-2 and a lower tube sheet 1-7 are provided in the shell 1-6, the area between the shell 1-6 and the upper tube sheet 1-2 serves as a flue gas inlet 1-1, the area between the lower tube sheet 1-7 and the shell 1-6 serves as a flue gas outlet 1-9, the air inlet 1-8 is connected to the lower tube sheet 1-7, the air outlet is connected to the upper tube sheet 1-2, air corridors are distributed between the lower tube sheet 1-7 and the upper tube sheet 1-2, and the air corridors are provided with baffles 1-10; tube holes are provided in the upper tube sheet 1-7 and the lower tube sheet 1-2, and a plurality of spirally deformed tube bundle modules 1-4 are connected and sealed with the upper and lower tube sheets through the tube holes, and each spirally deformed tube bundle module 1-4 is provided with an enclosure 1-11 on the outside. In this way, ambient air can enter from the lower tube plate 1-7, enter the outside of the spirally deformed tube bundle module after passing through the baffle plate 1-10 and the inclusion body 1-11, and then be discharged from the upper tube plate 1-2; one end of the spirally deformed tube bundle module 1-4 is connected to the flue gas inlet 1-1, and the other end is connected to the flue gas outlet 1-9, and the flue gas outlet 1-9 is also connected to the water film dust collector 4. In specific applications, the high-temperature flue gas drawn out from the boiler enters the spirally deformed tube bundle module 1-4 from the flue gas inlet 1-1, is discharged from the flue gas outlet 1-9 after releasing heat, and then returns to the water film dust collector 4 or the boiler environmental protection device. The ambient air enters the external space of the spirally deformed tube bundle module 1-4 from the air inlet 1-8, is discharged from the air outlet 1-3 after absorbing heat, and then enters the rotary drum dryer 2 to dry the biomass fuel; in this way, the flue gas and air perform pure countercurrent high-efficiency heat exchange in the high-efficiency air preheater 1, achieving ultra-high quality heating and ultra-low temperature waste heat recovery, the overall heat transfer coefficient is increased by 50%-70%, the hot end difference between the cold and hot media can reach 10℃-20℃, the dry air temperature is greatly increased, the manufacturing is simple and the medium pressure drop can be reduced by 30%-40%, and the volume can be reduced by more than 30% compared with traditional air preheaters on the market. Specifically, the spiral deformation tube bundle module 4 is composed of a number of spiral deformation tubes, and is bundled with fixing belts 1-5 to avoid vibration. The spiral deformation tubes are made of stainless steel, ND steel or carbon steel, etc. The flow space ratio of the cold and hot media in the air preheater can be adjusted according to the deformation coefficient of the spiral deformation tube.

[0038] In a preferred embodiment, the biomass fuel pretreatment device for efficiently utilizing flue gas waste heat also includes a first induced draft fan 7, a second induced draft fan 8 and a third induced draft fan 9. The first induced draft fan 7 is arranged in the first pipeline I connecting the high-efficiency air preheater 1 and the rotary drum dryer 2, so that the heated air can be sent to the rotary drum dryer 2 as a heat source to dry the biomass fuel; the second induced draft fan 8 is arranged in the second pipeline II connecting the cyclone separator 3 and the water film dust collector 4, so that the dried air tail gas can be extracted and the tail gas can be sent to the water film dust collector 4 for tail gas treatment; the third induced draft fan is arranged in the third pipeline III connecting the flue gas outlet 1-9 and the water film dust collector 4, so that the flue gas can be extracted and power can be provided for the flow of the flue gas. That is to say, the high-efficiency air preheater 1, the first induced draft fan 7, the rotary drum dryer 2, the cyclone separator 3, the second induced draft fan 8, and the water film dust collector 4 are connected end to end through the first pipeline I and the second pipeline II to form a hot air flow channel, and the high-efficiency air preheater 1, the third induced draft fan 9, and the water film dust collector 4 are connected in sequence through the third pipeline to form a flue gas exhaust flow channel, and the dried exhaust gas passes through the cyclone separator and the water film dust collector for environmental protection treatment. The low-temperature air enters the first pipeline through the heat exchanger, and the high-temperature flue gas passes through the heat exchanger in the opposite direction and then enters the third pipeline. The two fluids realize sufficient energy exchange in the heat exchanger, thereby efficiently recovering the flue gas energy and reducing energy consumption.

[0039] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention recycles the high-temperature flue gas after the combustion of biomass fuel, heats the air with the waste heat of the flue gas, and then uses the air as a heat transfer medium to dry the biomass fuel for pretreatment, thereby reducing the moisture content of the biomass fuel and increasing the combustion energy efficiency of the biomass fuel. This saves energy waste and improves energy release efficiency, thus significantly improving energy utilization.

[0041] (2) The present invention has an ultra-efficient air preheater and adopts a pure countercurrent design, that is, the cold fluid and the hot fluid flow in opposite parallel directions. The low-temperature air enters the first pipeline through the heat exchanger, and the high-temperature flue gas passes through the heat exchanger in the opposite direction and then enters the third pipeline. The two fluids realize sufficient energy exchange in the heat exchanger, thereby efficiently recovering the flue gas energy and reducing energy consumption. The temperature efficiency is high, the medium resistance is low, and the active energy consumption of the fan is low, so that a large amount of heat in the high-temperature flue gas can be recovered to raise the air temperature close to the flue gas inlet temperature.

[0042] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A biomass fuel pretreatment device for efficiently utilizing flue gas waste heat, characterized in that: It includes high-efficiency air preheater, rotary drum dryer, cyclone separator and water film dust collector; among them, The high-efficiency air preheater is provided with a smoke inlet, a smoke outlet, an air inlet and an air outlet; the air outlet is connected to the rotary drum dryer; the smoke inlet is used to receive smoke, and the air inlet is used to receive air, so that the smoke and air exchange heat in the high-efficiency air preheater, and the heated air enters the rotary drum dryer from the air outlet; The rotary drum dryer is provided with a biomass wet fuel inlet, a dry fuel outlet and an exhaust gas outlet, wherein the biomass wet fuel inlet is used to receive the biomass wet fuel, the dry fuel outlet is used to discharge the dry fuel, and the exhaust gas outlet is connected to the cyclone separator; The cyclone separator is provided with a gas outlet and a fuel dust outlet, the gas outlet is connected to the water film dust collector, and the fuel dust outlet is connected to the rotary drum dryer.

2. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 1, characterized in that: The high-efficiency air preheater is a pure countercurrent three-dimensional variable space heat exchanger, and the flue gas and air flow in opposite parallel directions.

3. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 1, characterized in that: It also includes a screw feeder, the discharge port of which is connected to the biomass wet fuel inlet of the rotary drum dryer to feed the biomass wet fuel into the rotary drum dryer; the screw feeder is also connected to the cyclone separator, and the fuel dust separated by the cyclone separator is sent back to the rotary drum dryer through the screw feeder.

4. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 1, characterized in that: The rotary drum dryer adopts reverse parallel friction flow heat exchange and is heated by upstream air. The wet biomass fuel rolls and turns in the drum to mix with the hot air, and the overall direction of movement is opposite to the air flow direction.

5. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 2, characterized in that: The high-efficiency air preheater includes an outer shell, in which an upper tube plate and a lower tube plate are arranged, the area between the outer shell and the upper tube plate serves as a flue gas inlet, the area between the lower tube plate and the outer shell serves as a flue gas outlet, and the flue gas outlet is connected to a cyclone separator; an air inlet and an air outlet are respectively arranged on both sides of the outer shell, the air inlet is connected to the lower tube plate, and the air outlet is connected to the upper tube plate, and air corridors are evenly distributed on the side opposite to the lower tube plate and the upper tube plate, and the air corridors are provided with a group of partitions; the upper tube plate and the lower tube plate are provided with tube holes, and a plurality of spirally deformed tube bundle modules are connected and sealed with the upper and lower tube plates through the tube holes; each spirally deformed tube bundle module is provided with an enclosure on the outside.

6. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to any one of claims 1 to 5, characterized in that: It also includes a first induced draft fan, which is arranged in a first pipeline connecting the high-efficiency air preheater and the rotary drum dryer.

7. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 6, characterized in that: It also includes a second induced draft fan, which is arranged in a second pipeline connecting the cyclone separator and the water film dust collector.

8. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 7, characterized in that: It also includes a third induced draft fan, which is arranged in a third pipeline connecting the smoke outlet and the water film dust collector.

9. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 5, characterized in that: The spirally deformed tube bundle module is composed of a plurality of spirally deformed tubes and is bundled with a fixing belt; the flow space ratio of the cold and hot media in the high-efficiency air preheater is adjusted according to the deformation coefficient of the spirally deformed tubes.

10. The biomass fuel pretreatment device for efficiently utilizing flue gas waste heat according to claim 1, characterized in that: A discharge collecting trough is arranged below the dry fuel outlet.

Images