WO2014071800A1

WO2014071800A1 - Method and apparatus for drying biomass raw material using biomass boiler flue gas

Info

Publication number: WO2014071800A1
Application number: PCT/CN2013/085685
Authority: WO
Inventors: 陈义龙; 张岩丰; 李宏
Original assignee: 阳光凯迪新能源集团有限公司
Priority date: 2012-11-07
Filing date: 2013-10-22
Publication date: 2014-05-15
Also published as: CN102954678A; CN102954678B

Abstract

A method and an apparatus for drying a biomass raw material using biomass boiler flue gas. The method guides a biomass raw material onto a belt conveyor (7) inside a drying chamber (8), performs dynamic transmission, and introducing biomass boiler flue gas that has undergone dedusting processing to contact and exchange heat with the biomass raw material, so as to remove a part of water inside the biomass raw material; performing dedusting processing again on the flue gas that has undergone heat exchange, and directly using the dried biomass raw material as a fuel for a biomass boiler (1) or saving the same for future use. The apparatus is mainly formed of a flue gas circulation system and the belt conveyer (7), the flue gas circulation system being formed by a deduster (3), the drying chamber (8), a booster fan (10), an induced draft fan (6), and the like, and the belt conveyer (7) being disposed inside the drying chamber (8) and used for conveying a biomass raw material. The method can reduce the size of a biomass boiler system and significantly enhance the thermal efficiency of the biomass boiler system.

Description

Method and device for drying biomass raw material by using biomass boiler flue gas

The invention relates to boiler waste heat utilization and energy saving and emission reduction technology, and specifically relates to a method and a device for drying biomass raw materials by using biomass boiler flue gas. Background technique

With the declining reserves of traditional fossil energy coal, oil and natural gas, and the environmental pollution caused by the use of fossil energy directly threatening the survival and development of human beings, the importance and development of renewable environmentally friendly energy has become the government of all countries. Common goal. Biomass is an organic substance produced by plants through photosynthesis. It is widely distributed, widely available, cleaned with fossil energy, and has zero carbon dioxide emissions. It is an important renewable energy source. Biomass feedstock generally contains a large amount of water. If it is not subjected to drying treatment before entering the boiler as a fuel, the calorific value per unit mass of biomass feedstock is low, resulting in a decrease in the overall efficiency of the biomass boiler and an increase in the biomass boiler feed pipe. The size of the road and the furnace leads to an increase in the cost of the boiler. Therefore, biomass feedstocks typically require pre-drying prior to entering the biomass boiler.

The traditional method of drying biomass feedstock requires the introduction of an external high-temperature drying medium, which is cumbersome in process, complicated in equipment, high in energy consumption, and high in investment cost. In order to solve the above problem, the Chinese Patent Application Publication No. CN101693248A proposes a method for drying biomass raw materials using high-temperature flue gas, which is dried by high-temperature flue gas and then heated. Pressurized to form a fluidized slurry. However, this method requires the introduction of an external high-temperature drying medium, which has a great energy consumption and is currently unable to meet the increasingly high energy-saving and emission-reduction requirements of the national economy. The Chinese utility model patent specification with the announcement number CN202032602U discloses an integrated system for pre-drying power generation of flue gas, which uses the preheating of flue gas to dry the lignite raw material of the boiler, but the drum device used for drying still needs to consume a large amount of electric energy, thereby Increased system operation difficulty and operating costs. Summary of the invention

The object of the present invention is to overcome the existing structure of the existing biomass raw material drying technology, A drawback of high energy consumption, providing a method and apparatus for drying biomass feedstock using biomass boiler flue gas. The utility model has the advantages of simple structure, economical process and good drying effect, and can effectively reduce the size of the biomass boiler system and greatly improve the thermal efficiency of the biomass boiler system.

In order to achieve the above object, the method for drying biomass raw materials using biomass boiler flue gas designed by the present invention comprises the following steps:

1) introducing the biomass raw material to be burned into the working surface of the crawler conveyor provided in the drying chamber for uninterrupted dynamic transmission;

2) Introduce the high-temperature flue gas discharged from the biomass boiler into the dust collector to remove most of the dust impurities and obtain a relatively clean flue gas;

3) A part of the relatively clean flue gas is sent to the drying chamber to pass through the gap of the working surface of the crawler conveyor from bottom to top, and exchange heat with the dynamically transported biomass material to remove the biomass material. Part of the water;

4) Exporting the flue gas used for heat exchange to the drying chamber, and re-delivering it to the dust collector for further processing;

5) Export the dehydrated and dried biomass material to the drying chamber and use it directly as a fuel or storage for the biomass boiler.

Preferably, in the above step 3), the flue gas is first concentratedly transported to the hot air chamber disposed under the working surface of the crawler conveyor, and then escapes from the top of the hot air chamber, crossing the gap of the working surface of the crawler conveyor, and The dynamically transported biomass feedstock undergoes contact heat exchange. In this way, the flue gas entering the drying chamber can be buffered and evenly distributed to the dynamically transported biomass feedstock for drying.

Further, the temperature of the flue gas at the inlet of the drying chamber is controlled at 110~150 °C, preferably controlled at 120~130 °C; the temperature of the flue gas at the outlet of the drying chamber is controlled at 45~55 °C, preferably controlled At 48~50 °C. In this way, the temperature of the flue gas entering the drying chamber is lower than the lowest precipitation temperature of the effective volatile component in the biomass material, which ensures that the biomass material has no effective component loss during the drying process; and the flue gas temperature output from the drying chamber is only high. At tens of degrees Celsius at room temperature, it ensures that the biomass raw materials make full use of the residual heat of the flue gas.

Further, the transfer rate of the biomass material on the crawler conveyor is 0.2 to 0.8 m/s, and the residence time is 300 to 480 s; the average flow rate of the flue gas in the drying chamber is 8 to 15 m/s. In this way, by properly controlling the contact parameters of the dynamically transported biomass feedstock and the flue gas stream, it is ensured that the heat exchange between the two is always stable, thereby meeting the needs of continuous uninterrupted production in the industry. A device specially designed for realizing the above method for drying biomass raw materials by using biomass boiler flue gas, comprising a dust remover and a drying chamber, wherein the drying chamber is provided with a crawler conveyor, the top of the drying chamber a biomass feed port and a flue gas outlet pipe are respectively disposed, wherein the bottom of the drying chamber is respectively provided with a biomass discharge port and a flue gas inlet pipe; the biomass feed port is located above the input end of the crawler conveyor, The biomass outlet is located below the output of the crawler conveyor, and the flue gas outlet pipe is connected to the input end of the precipitator through a booster fan, and the flue gas inlet pipe is connected to the output end of the precipitator through an induced draft fan.

Preferably, a plurality of independent hot air chambers are arranged in parallel below the working surface of the crawler conveyor, and an air inlet branch is disposed at the bottom of the hot air chamber, and the air inlet branch is connected to the flue gas inlet tube, The top of the hot air chamber is uniformly provided with a smoke diffusion hole. In this way, the flue gas entering the drying chamber can be buffered evenly across the working surface of the crawler conveyor to evenly dry the dynamically transported biomass feedstock.

Further, a regulating valve is disposed on the intake branch pipe. In this way, the flue gas flow rate of each intake manifold can be conveniently adjusted to ensure uniform distribution of flue gas into each hot air chamber.

Further, a hot air uniform device is disposed in the hot air chamber. In this way, the flow direction of the flue gas inside each hot air chamber can be adjusted to match the flue gas flow field to an optimum state.

The invention has the advantages that: the designed drying method directly uses the high-temperature flue gas discharged from the biomass boiler as a heat source, and dehydrates and dries the biomass raw material, thereby reducing the total mass of the biomass raw material.

More than 15% can remove about half of the water in the biomass material, so that the calorific value per unit mass of biomass material is greatly increased. In this way, the thermal efficiency of the biomass boiler system can be greatly improved, with considerable economic benefits; and the size of the feed line of the biomass boiler system can be reduced accordingly. Moreover, the flow of flue gas generated by the combustion of the dried biomass feedstock is relatively low, and the size of the entire biomass boiler system can be reduced, thereby effectively reducing the cost of the boiler. At the same time, after the biomass material is dried, the humidity and flow rate of the flue gas generated during the combustion process are also significantly reduced. Therefore, when the flue gas discharged from the boiler is dedusted by the dust collector, the humidity and flow rate of the flue gas treated by the precipitator It also decreases correspondingly, which is conducive to improving dust removal efficiency.

In addition, the device designed by the invention has the advantages of simple structure, small investment, convenient adjustment of dry air volume and uniform distribution, and can well meet the requirements of drying of biomass raw materials. Although it has increased the energy consumption of adding some pipes and fans to overcome the system resistance, it has a low boiler cost and high thermal efficiency. Compared with the increased energy consumption ratio, the energy saving and emission reduction benefits of the whole system are obvious. DRAWINGS

1 is a schematic structural view of an apparatus for drying biomass feedstock using biomass boiler flue gas. Figure 2 is a schematic enlarged view of the portion of the drying chamber of Figure 1.

Fig. 3 is a schematic enlarged view of the A-A section of Fig. 2;

In the figure: Biomass boiler 1, biomass feed port 2, dust collector 3, biomass outlet 4, chimney 5, induced draft fan 6, crawler conveyor 7, drying chamber 8, silo 9, booster fan 10 The flue gas inlet pipe 11, the intake manifold 12, the regulating valve 13, the hot air distributing device 14, the hot air chamber 15, the flue gas diffusing hole 16, and the flue gas outlet pipe 17.

detailed description

The invention will be further described in detail below with reference to the drawings and specific embodiments.

The apparatus for drying biomass feedstock using biomass boiler flue gas, including a precipitator 3 and a drying chamber 8 disposed between the biomass boiler 1 and the chimney 5, is shown. The input of the precipitator 3 is connected to the flue gas outlet of the biomass boiler 1, and the output of the precipitator 3 is connected to the chimney 5. A crawler conveyor 7 is disposed in the drying chamber 8. The top of the drying chamber 8 is respectively provided with a biomass feeding port 2 and a flue gas outlet pipe 17, and the bottom of the drying chamber 8 is respectively provided with a biomass discharging port 4 and a flue gas inlet pipe 11 respectively. . The biomass feed port 2 is located above the input of the track conveyor 7 and is connected to the silo 9. The biomass discharge port 4 is located below the output of the track conveyor 7 and the dry biomass feedstock from the biomass discharge port 4 can be transported to the fuel inlet of the biomass boiler 1 via a transfer device. The flue gas outlet pipe 17 is connected to the input end of the precipitator 3 via a booster fan 10, and the flue gas inlet pipe 11 is connected to the output end of the precipitator 3 via an induced draft fan 6.

A plurality of independent hot air chambers 15 are arranged in parallel below the working surface of the crawler conveyor 7. The bottom portions of the hot air chambers 15 are provided with intake manifolds 12, and each of the intake manifolds 12 is simultaneously connected to the flue gas inlet pipe 11 and each An adjustment valve 13 is provided on the intake manifold 12. A hot air distribution device 14 is also disposed in each of the hot air chambers 15 above the outlet of the intake manifold 12. In the present embodiment, the hot air distribution device 14 is a horizontally fixed baffle, and a gap is left between the periphery and the hot air chamber 15 for dispersing the flue gas entering the hot air chamber 15. The top of each hot air chamber 15 is uniformly provided with a flue gas diffusion hole 16, and the flue gas can uniformly pass through the flue gas diffusion hole 16 The working surface with the conveyor 7.

Taking fresh biomass feedstock with a water content of about 30% of the total mass as an example, the above device uses the biomass boiler flue gas to dry the biomass raw material:

The biomass raw material to be burned stored in the silo 9 enters the working surface of the crawler conveyor 7 in the drying chamber 8 through the biomass feed port 2, and performs uninterrupted dynamic transmission, and finally outputs from the biomass discharge port 4. . The transport speed of the biomass material on the crawler conveyor 7 is preferably 0.2 to 0.8 m/s, the optimum range is 0.4 to 0.6 m/s, the residence time is preferably 300 to 480 s, and the optimum range is 400 to 450 s; The average flow rate in the drying chamber 8 is preferably 8 to 15 m/s, and the optimum range is 10 to 12 m/s.

At the same time, the high-temperature flue gas emitted by the biomass boiler 1 enters the precipitator 3, and most of the dust impurities are removed to obtain a relatively clean flue gas. A part of the relatively clean flue gas is discharged into the atmosphere through the bacon 5, and the other portion is pressurized by the draft fan 6, and enters the hot air chamber 15 in the drying chamber 8 through the flue gas inlet pipe 11 and the intake branch pipe 12. The flue gas in each hot air chamber 15 is uniformly flowed by the hot air distributing device 14, and then escapes through the flue gas diffusion hole 16 at the top of the hot air chamber 15, so that the flue gas passes through the working surface of the crawler conveyor 7 from bottom to top. The voids exchange heat with the dynamically transported biomass feedstock to remove some of the moisture from the biomass feedstock.

The temperature of the flue gas at the inlet of the drying chamber 8 is controlled to be 110 to 150 ° C, and the temperature at the outlet of the drying chamber 8 is 45 to 55 ° C. The residual heat and temperature difference of the flue gas can be fully utilized to obtain a good drying effect. In this embodiment, the temperature of the flue gas at the inlet of the drying chamber 8 is 120 to 130 ° C, and the temperature of the flue gas at the outlet of the drying chamber 8 is 48 to 50 °C.

Finally, the flue gas used for heat exchange is led out of the drying chamber 8 through the flue gas outlet pipe 17, and is re-delivered to the dust collector 3 to continue the dust removal process; meanwhile, the dehydrated and dried biomass material is exported through the biomass discharge port 4. The drying chamber 8 is used directly as a fuel or storage reserve for the biomass boiler 1.

The test shows that: when the flue gas inlet temperature of the drying chamber 8 is about 130 °C, the flue gas outlet temperature is about 50 °C, and the average flue gas flow rate is about 12 m/s, the biomass raw material passing through the drying chamber 8 can be Remove about 15% of the total mass of water. Since the flue gas temperature is lower than the lowest precipitation temperature of the volatiles in the biomass feedstock, there is no problem with the volatilization analysis.

Claims

claims

1. A method of drying biomass raw materials using biomass boiler flue gas, including the following steps:

1) Introduce the biomass raw materials to be burned into the working surface of the crawler conveyor (7) installed in the drying chamber (8) for uninterrupted dynamic transmission;

2) Introduce the high-temperature flue gas emitted by the combustion of the biomass boiler (1) into the dust collector (3) to remove most of the dust impurities and obtain relatively clean flue gas;

3) Take a part of the relatively clean flue gas and transport it to the drying chamber (8), so that it passes through the working surface gap of the crawler conveyor (7) from bottom to top, and contacts and exchanges heat with the dynamically transported biomass raw materials. , thereby removing part of the water in the biomass raw materials;

4) Export the heat-exchanged flue gas out of the drying chamber (8), and re-transmit it to the dust collector (3) for continued processing;

5) Export the dehydrated and dried biomass raw materials out of the drying chamber (8), and directly use them as fuel for the biomass boiler (1) or store them for later use.

2. The method of using biomass boiler flue gas to dry biomass raw materials according to claim 1, characterized in that: in step 3), the flue gas is first concentrated and transported to the bottom of the working surface provided on the crawler conveyor (7) in the hot air chamber (15), and then escape from the top of the hot air chamber (15) and pass through the crawler conveyor

(7) The working surface gap is in contact with the dynamically transported biomass raw materials for heat exchange.

3. The method of using biomass boiler flue gas to dry biomass raw materials according to claim 1 or 2, characterized in that: the temperature of the flue gas at the entrance of the drying chamber (8) is 110~150°C, The temperature of the flue gas at the outlet of the drying chamber (8) is 45~55°C.

4. The method of using biomass boiler flue gas to dry biomass raw materials according to claim 1 or 2, characterized in that: the temperature of the flue gas at the entrance of the drying chamber (8) is 120~130°C, The temperature of the flue gas at the outlet of the drying chamber (8) is 48~50°C.

5. The method of drying biomass raw materials using biomass boiler flue gas according to claim 1 or 2, characterized in that: the transmission speed of the biomass raw materials on the crawler conveyor (7) is 0.2~0.8m/s , the residence time is 300~480s; the average flow velocity of the flue gas in the drying chamber (8) is 8~15m/s.

6. A device for drying biomass raw materials using biomass boiler flue gas designed to implement the method of claim 1, including a dust collector (3) and a drying chamber (8), characterized in that: the drying chamber

(8) The inner cavity is provided with a crawler conveyor (7). The top of the drying chamber (8) is provided with a biomass feed port (2) and a flue gas outlet pipe (17). The bottom of the drying chamber (8) A biomass outlet (19) and a flue gas inlet pipe (11) are respectively provided; the biomass inlet (2) is located above the input end of the crawler conveyor (7), and the biomass outlet (4) ) is located below the output end of the crawler conveyor (7), the flue gas outlet pipe (17) is connected to the input end of the dust collector (3) through the booster fan (10), and the flue gas inlet pipe (11) passes through the guide The fan (6) is connected to the output end of the dust collector (3).

7. The device for drying biomass raw materials using biomass boiler flue gas according to claim 6, characterized in that: a plurality of independent hot air chambers (15) are arranged side by side below the working surface of the crawler conveyor (7). , the hot air chamber (15) is provided with an air inlet branch pipe (12) at the bottom, the air inlet branch pipe (12) is connected to the smoke inlet pipe (Π), and the top of the hot air air chamber (15) is evenly distributed with smoke Gas diffusion hole (16).

8. The device for drying biomass raw materials using biomass boiler flue gas according to claim 7, characterized in that: the air inlet branch pipe (12) is provided with a regulating valve (13).

9. The device for drying biomass raw materials using biomass boiler flue gas according to claim 7 or 8, characterized in that: a hot air uniform distribution device (14) is provided in the hot air chamber (15).

10. The device for drying biomass raw materials using biomass boiler flue gas according to claim 9, characterized in that: the hot air uniform distribution device (14) is a horizontal barrier located above the outlet of the air inlet branch pipe (12)