A garbage pyrolysis furnace

Abstract

The present invention discloses a garbage pyrolysis furnace, belonging to the field of solid waste harmless disposal technology. Its overall shape is cylindrical or rectangular, with an internal interconnected cavity. A flue gas outlet and feed port are provided at the top, and an ash hopper and slag discharge port are provided at the bottom. A grate and a gas distributor are provided above the ash hopper, with the gas distributor positioned above the grate. The ratio of the furnace cavity's height to its cross-sectional area is 1 to 2. By controlling the ratio of the furnace body's height to its cross-sectional area, a temperature gradient can be achieved from bottom to top within the furnace cavity during operation, achieving the three major functions of combustion, pyrolysis, and drying. By adopting a more rational design of the furnace structure, the present invention can maximize the spontaneous and automatic stratification of each functional zone, ensuring continuous and stable process operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of harmless disposal of solid waste, and more specifically, relates to a garbage pyrolysis furnace. Background Art

[0002] Conventional methods for handling domestic waste include sanitary landfill, composting, and incineration. Sanitary landfill technology has a long history and mature processes, but it occupies a large area and takes a long time to completely treat the waste, resulting in a large amount of land resource consumption. There are also problems such as leachate leakage and contamination of soil and water bodies. Domestic waste composting can recycle waste resources and convert it into fertilizer, but it has high requirements for waste raw materials, and the output fertilizer is not very efficient, and its application scope is limited, among other industry restrictions. Waste incineration can maximize the reduction of domestic waste and convert it into non-polluting components such as carbon dioxide, water, and inorganic ash, but it is also prone to produce pollutants and toxic substances such as sulfides, nitrogen oxides, and dioxins.

[0003] Garbage pyrolysis treatment technology is a heat treatment method that can replace garbage incineration technology and achieve a significant harmless reduction in garbage. In an oxygen-free environment, the pyrolysis reaction converts domestic garbage into pyrolysis gas (oil) and residual carbon composed of hydrogen, carbon monoxide, low-molecular organic matter, etc. The pyrolysis gas (oil) and residual carbon are further burned and completely oxidized into carbon dioxide and water. The pyrolysis reaction avoids the direct incomplete combustion of chlorine-containing high-molecular organic matter and can effectively reduce the production of toxic gases such as dioxins. However, the pyrolysis reaction is an endothermic reaction and requires an oxygen-free or oxygen-limited environment. Most pyrolysis equipment cannot simultaneously achieve complete sealing, an oxygen-free / oxygen-limited environment, and sufficient heat supply, resulting in unsatisfactory pyrolysis treatment results.

[0004] Therefore, it is necessary to develop a new type of continuous and stable garbage pyrolysis furnace to solve the problems existing in the existing technology. Summary of the Invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a garbage pyrolysis furnace, which can ensure the spontaneous and automatic stratification or generation of garbage raw materials and various functional areas to the greatest extent by designing the furnace body to be hollow as a whole, especially in combination with the ratio of the furnace body's height to the cross-sectional area, and combined with the design of the distributor, and the thickness structure of the stratification is very reasonable, ensuring the continuous and stable progress of the process.

[0006] To achieve the above objectives, the present invention provides a garbage pyrolysis furnace, which has an overall cylindrical or rectangular shape, an internal cavity that is interconnected, a smoke outlet and a feed port provided at the top, an ash hopper and a slag discharge port provided at the bottom, a grate and an air distributor provided above the ash hopper, and the air distributor placed above the grate. The ratio of the height to the cross-sectional area of the furnace cavity is 1 to 2. By controlling the ratio of the height to the cross-sectional area of the furnace body, a temperature gradient can be achieved from bottom to top in the furnace cavity during operation for the three major functions of combustion, pyrolysis, and drying.

[0007] At the same time, by controlling the ratio of the furnace body's height to its cross-sectional area, the material distribution uniformity, and the gas distribution uniformity, the material can be controlled to burn fully, while the flue gas outlet temperature is lower than 150°C, thus enabling the pyrolysis process to proceed continuously and stably.

[0008] The height of the furnace body refers to the height of the cylindrical part or the rectangular part of the furnace body, and the cross-sectional area of the furnace body refers to the cross-sectional area of the cylindrical part or the rectangular part of the furnace body.

[0009] Furthermore, the ratio of the height of the furnace cavity to the cross-sectional area is 1 to 1.5.

[0010] Furthermore, the ratio of the height to the cross-sectional area of the furnace cavity is 1 to 1.2.

[0011] Furthermore, a distributor is arranged in the top cavity of the furnace body. The distributor is set below the feed port, and the feed port is connected to the pusher above the furnace top. The distance between the distributor and the feed port is not less than 50 cm. The distributor has a pointed cone-shaped tip, and the tip is surrounded by a circle of guide rods similar to an umbrella frame. Multiple guide rods are evenly distributed around the tip and tilted downward in a consistent manner. The tip is facing the falling direction of the garbage, and is used to apply force to break up the garbage that is entangled with each other through the tip. The broken garbage flows downward along the guide rods and is evenly dispersed to the surroundings.

[0012] Furthermore, the height of the furnace cavity occupied by the distributor is one-fifth to one-quarter of the total height of the furnace cavity, and the distance between the tip of the distributor and the feed port is one-eighth to one-tenth of the furnace cavity height, and the distance between the tip of the distributor and the drop port of the pusher is 50cm to 100cm, so as to ensure that the height of the free fall of garbage is 50cm to 100cm.

[0013] Furthermore, the top of the furnace body is flat, and the feed port is arranged in the center of the flat furnace top. A two-stage tar removal device is also provided at the furnace top, wherein the first-stage tar removal device is a biomass tar removal device, and the second-stage tar removal device is an electric coke collector. The biomass tar removal device uses biomass adsorption to remove tar, and its cross-sectional area is large enough to reduce the flue gas flow rate, and can also adsorb tar and dust through interception and adsorption.

[0014] Furthermore, the air distributor is composed of a number of L-shaped air inlet pipes evenly distributed at the bottom of the garbage pyrolysis furnace. One end of each L-shaped air inlet pipe is vertically upward and parallel to the furnace body of the garbage pyrolysis furnace, and the top is sealed. A nozzle obliquely downward is provided on the side wall, and the other end passes through the furnace wall of the garbage pyrolysis furnace and is vertically led out and connected to the outside air. When working, the induced draft fan connected to the flue gas outlet on the top of the furnace body is used to extract air, so that the inner cavity of the furnace body is at a negative pressure, so that external air enters from one end of the L-shaped air inlet pipe located outside the furnace body, and air is evenly introduced into the inner cavity of the furnace body through the air inlet holes opened on the side wall at one end inside the furnace body. As the top induced draft fan draws air, the gas inside the furnace body goes upward. The design of the oblique downward nozzle is used to prevent ash produced by combustion from falling and clogging the nozzle.

[0015] Furthermore, a flue gas outlet is arranged on one side of the furnace top and is connected to a two-stage tar removal device.

[0016] In the present invention, the gradient temperature-variable pyrolysis furnace does not have an independent combustion chamber, but the material layer in the bottom area is in the combustion zone. There is no strict pyrolysis chamber or combustion chamber in the gradient temperature-variable pyrolysis furnace. It is a connected cavity. Due to the control of the height and cross-sectional area ratio, and combined with the optimized design of the feeding and distribution space, the drying area, pyrolysis area and combustion area can be reasonably divided automatically and spontaneously in a relatively controllable manner. A grate is provided at the bottom of the low-temperature furnace, and an air distributor is provided above the grate. From top to bottom are the drying layer, pyrolysis layer and combustion layer, and below the grate are the ash layer and slag discharge layer. The material after the combustion layer reacts completely is inorganic ash. The ash passes through the grate and enters the ash layer and slag discharge layer. A slag outlet is provided at the bottom, and the ash in the furnace is discharged from the slag outlet.

[0017] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0018] On the whole, the pyrolysis furnace of the present invention is a closed integrated cavity. By controlling the height-to-diameter ratio of the furnace body, the material can spontaneously maintain a stable upper and lower layer structure without using components or structures to forcibly separate the furnace cavity. There will be no problem of garbage accumulation in the furnace due to slow pyrolysis and oxygen-controlled combustion speeds, nor will there be the problem of rapid falling into the pyrolysis and oxygen-controlled combustion range due to insufficient drying. Due to its reasonable height-to-diameter ratio, the position and structure of the distributor and feed port are further optimized to ensure the stable segmentation and stratification of the material in the vertical direction to the greatest extent, while ensuring the airtightness of the furnace body. Such a design realizes stable and continuous anaerobic or oxygen-limited pyrolysis and combustion. Continuous and stable anaerobic or oxygen-limited pyrolysis and combustion are the basis for the furnace body to be truly put into actual engineering and truly applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the furnace structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] Most existing garbage pyrolysis processes are often unable to operate continuously and stably for a long time. This is because: the pyrolysis process usually requires that the material be divided into multiple parts such as drying, pyrolysis, and combustion for step-by-step reactions. In order to make the material in the furnace more stably divided into multiple sections and react in sequence, most pyrolysis furnaces use batches, compartments or other methods to feed or operate non-continuously in stages.

[0022] The present invention is designed and created after a scientific and effective analysis of the existing problems and finding out the real causes of the problems.

[0023] Figure 1It is a schematic diagram of the furnace structure in an embodiment of the present invention. As can be seen from the figure, the overall shape of the garbage pyrolysis furnace of the present invention is cylindrical, and the interior is a connected cavity. The top is provided with a flue gas outlet 1 and a feed port 7, and the bottom is provided with an ash hopper 5 and a slag discharge port 6. A grate 9 and an air distribution cavity 10 are provided above the ash hopper. The air distribution cavity 10 is below the grate 9. The ratio of the height of the furnace body cavity to the cross-sectional area is 1 to 2. The preferred ratio of the height of the furnace body cavity to the cross-sectional area is 1 to 1.5, and the optimal ratio of the height of the furnace body cavity to the cross-sectional area is 1 to 1.2. A distributor is arranged in the top cavity of the furnace body. The distributor is set below the feed port, which is connected to the pusher above the furnace top. The distance between the distributor and the feed port is not less than 50 cm. The distributor has a pointed cone-shaped tip, surrounded by a circle of guide rods similar to the skeleton of an umbrella. Multiple guide rods are evenly distributed around the tip and tilted downward. The tip is facing the direction of garbage falling. It is used to apply force to break up tangled garbage balls through the tip. After breaking, the garbage flows downward along the guide rods and is evenly dispersed to the surrounding areas. The height of the furnace cavity occupied by the distributor is one-fifth to one-quarter of the total height of the furnace cavity, and the distance between the distributor tip and the feed port is one-eighth to one-tenth of the furnace cavity height. The distance between the distributor tip and the pusher drop port is 50 cm to 100 cm, to ensure that the height of the free fall of garbage is 50 cm to 100 cm. The top of the furnace is flat, with the feed port located in its center. A two-stage detarring system is also installed at the top. The first stage is a biomass detarring system, and the second stage is an electric capture system. The biomass detarring system removes tar by biomass adsorption. Its cross-sectional area is large enough to reduce the flue gas flow rate and absorb tar and dust through interception and adsorption. The air distributor consists of several L-shaped air inlet pipes evenly distributed at the bottom of the waste pyrolysis furnace. Each L-shaped air inlet pipe has one end extending vertically upward and parallel to the furnace body, and is sealed at the top. A nozzle is provided on its sidewall, facing downward. The other end extends vertically through the furnace wall and is connected to the outside air. During operation, the furnace's internal cavity is negatively pressurized by an induced draft fan connected to the flue gas outlet at the top of the furnace. This allows air to enter through the L-shaped inlet pipe, located outside the furnace, and evenly flow into the furnace cavity through the air inlet holes on the sidewall at one end inside the furnace. As the top induced draft fan draws air, the internal gas flows upward. The downward-angled nozzle is designed to prevent ash from falling and clogging the nozzle. The flue gas outlet is located on one side of the furnace roof and connects to a two-stage detarring device.

[0024] In the present invention, by controlling the height-to-diameter ratio of the furnace body, during operation, the internally interconnected furnace cavity can be naturally divided into a drying layer 2, a pyrolysis layer 3 and a combustion layer 4, and the drying layer occupies one-fifth to one-quarter of the entire furnace cavity height, the pyrolysis layer occupies one-fifth to one-quarter of the entire furnace cavity height, and the combustion layer occupies one-tenth to one-eighth of the entire furnace cavity height, thereby enabling the pyrolysis process to be carried out continuously and stably. The height of the furnace body refers to the height of the cylindrical part of the furnace body, and the diameter of the furnace body refers to the inner diameter of the cylindrical part of the furnace body.

[0025] In the present invention, the furnace body of the pyrolysis furnace is cylindrical as a whole, and its essence is a hollow cavity with a large aspect ratio. The top feed port of the pyrolysis furnace adopts a compression continuous feeding device, such as a pusher, to continuously convey the garbage raw materials into the furnace body. The garbage moves downward along the furnace body and accumulates layer by layer in the furnace cavity. Since the cross-section of the furnace cavity is smaller than the height of the furnace body, the material can easily be evenly accumulated in one layer and is not prone to local collapse. According to the temperature change, it is divided into a drying layer and a pyrolysis reaction layer in height. The material is dried first and then pyrolyzed. The temperature of the garbage raw materials changes gradiently from top to bottom. The temperature of the top drying layer is the lowest, the temperature of the pyrolysis reaction layer in the middle and lower part gradually increases, and the temperature of the bottom combustion layer is the highest. Along the height direction of the pyrolysis furnace, from top to bottom, the temperature in the furnace shows a gradient change according to the different functional layers. It is a gradient temperature-variable pyrolysis furnace. In the low-temperature furnace, the solid-phase material moves from top to bottom, and the gaseous material moves from bottom to top. The combustion layer primarily burns residual carbon and some unreacted waste. The gaseous products from pyrolysis are discharged from the upper outlet, where they undergo tar removal before entering the secondary combustion chamber, where they undergo complete combustion and reaction. During this process, the waste is converted through pyrolysis into a gaseous phase (including water, pyrolysis gas, tar, and other inert components) and a solid phase (residual carbon from pyrolysis and unreacted inorganic components). The gaseous phase is further completely burned in the secondary combustion chamber, while the solid phase is completely burned in the combustion zone. The slag is discharged from the pyrolysis furnace through the outlet below the combustion chamber.

[0026] One of the improvements of this invention is that it combines drying, pyrolysis, and combustion in a single furnace. By designing a high aspect ratio, this ensures that the three processes are well-matched and run smoothly. This prevents inadequate drying from hindering pyrolysis and combustion, nor does it prevent insufficient processing capacity from slowing down the pyrolysis and combustion processes, leading to slow processing and combustion. This design saves furnace space and maximizes the use of heat from waste pyrolysis.

[0027] One of the key improvements of the present invention is the furnace body height-to-diameter ratio and the placement of the distributor. Furthermore, the furnace body entrance is relatively small, and the material is pushed into the furnace through compression and density, sealing the furnace body entrance to prevent oxygen or air from entering the furnace. The ratio of the furnace body cavity height to the cross-sectional area is set at 1-2, ensuring that the furnace body height is a set multiple of the furnace body diameter. Combined with the design of the distribution and feed design and other process parameters, the garbage can be dried, pyrolyzed, and burned in layers. If the furnace body diameter is too small relative to the furnace body height, the process processing capacity of the combustion link will be insufficient, combustion will be incomplete, and emissions will not meet standards. If the furnace body diameter is too large relative to the furnace body height, it may result in incomplete drying and pyrolysis, and the combustion will produce more polluting emissions.

[0028] In fact, although some furnaces on the market also combine drying, pyrolysis and combustion in one furnace, in actual engineering practice, it is found that the continuous stability of the process is insufficient, and there are often problems such as unqualified slag or tail gas, or large fluctuations in furnace parameters. In fact, these are all caused by unreasonable layer heights of the drying layer, pyrolysis layer and combustion layer. A too small height-to-diameter ratio will make it difficult for the material to form horizontal stratification, and the reaction will be uneven in the horizontal direction, resulting in the material not being able to be distributed in layers; a too large height-to-diameter ratio will cause gas flow and solid material movement to be obstructed, the material residence time is too long, and the space utilization efficiency in the furnace is low. At the same time, this type of furnace has poor practicality (it is like a chimney, with practical problems such as high construction difficulty, difficulty in feeding, and difficulty in processing). The present invention has found the crux of the problem and solved it.

[0029] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A garbage pyrolysis furnace, characterized in that: Its overall shape is rectangular or cylindrical, and it is a hollow cavity with a large aspect ratio. The interior is a connected cavity. A flue gas outlet and a feed port are provided on the top, an ash hopper and a slag discharge port are provided on the bottom, a grate and an air distributor are provided above the ash hopper, and the air distributor is placed above the grate. The ratio of the height to the cross-sectional area of the furnace body inner cavity is 1 to 1.

2. By controlling the ratio of the height to the cross-sectional area of the furnace body, the internally connected furnace cavity can be naturally divided into a drying layer, a pyrolysis layer and a combustion layer during operation. Moreover, the drying layer occupies one-fifth to one-quarter of the entire furnace cavity height, the pyrolysis layer occupies one-fifth to one-quarter of the entire furnace cavity height, and the combustion layer occupies one-tenth to one-eighth of the entire furnace cavity height, so that the temperature gradient of the three major functions of combustion, pyrolysis and drying can be realized from bottom to top in the furnace cavity during operation, thereby realizing continuous and stable pyrolysis process. At the same time, by controlling the ratio of the furnace body's height to its cross-sectional area, the material distribution uniformity, and the gas distribution uniformity, the material can be controlled to burn fully, while the flue gas outlet temperature is lower than 150°C, thus enabling the pyrolysis process to proceed continuously and stably. The height of the furnace body refers to the height of the cylindrical part or the rectangular part of the furnace body, and the cross-sectional area of the furnace body refers to the cross-sectional area of the cylindrical part or the rectangular part of the furnace body.

2. A garbage pyrolysis furnace according to claim 1, characterized in that: A distributor is arranged in the top cavity of the furnace body. The distributor is set below the feed port, which is connected to the pusher above the furnace top. The distance between the distributor and the feed port is not less than 50 cm. The distributor has a pointed cone-shaped tip, and the tip is surrounded by a circle of guide rods similar to an umbrella frame. Multiple guide rods are evenly distributed around the tip and tilted downward in a consistent manner. The tip is facing the direction of garbage falling, and is used to use the tip to apply force to break up the garbage that is entangled in clusters. The broken garbage flows downward along the guide rods and is evenly dispersed to the surroundings.

3. A garbage pyrolysis furnace as claimed in claim 2, characterized in that: The height of the furnace cavity occupied by the distributor is one-fifth to one-quarter of the total height of the furnace cavity, and the distance between the tip of the distributor and the feed port is one-eighth to one-tenth of the furnace cavity height. The distance between the tip of the distributor and the drop port of the pusher is 50cm~100cm to ensure that the height of the free fall of garbage is 50cm~100cm.

4. A garbage pyrolysis furnace as claimed in claim 3, characterized in that: The top of the furnace body is flat, and the feed port is set in the center of the flat furnace top. A two-stage tar removal device is also installed on the furnace top. The first-stage tar removal device is a biomass tar removal device, and the second-stage tar removal device is an electric coke collector. The biomass tar removal device uses biomass adsorption to remove tar. Its cross-sectional area is large enough to reduce the flue gas flow rate, and it can also adsorb tar and dust through interception and adsorption.

5. A garbage pyrolysis furnace as claimed in claim 4, characterized in that: The air distributor is composed of a number of L-shaped air inlet pipes evenly distributed at the bottom of the waste pyrolysis furnace. One end of each L-shaped air inlet pipe is vertically upward and parallel to the furnace body of the waste pyrolysis furnace, and its top is sealed. A nozzle is opened on its side wall and obliquely downward. The other end passes through the furnace wall of the waste pyrolysis furnace and is vertically led out and connected to the outside air. During operation, the induced draft fan connected to the smoke outlet on the top of the furnace body is used to extract air, so that the inner cavity of the furnace body is at a negative pressure, so that external air enters from the end of the L-shaped air inlet pipe located outside the furnace body, and is evenly introduced into the inner cavity of the furnace body through the air inlet holes opened on the side wall at one end inside the furnace body. As the top induced draft fan draws air, the gas inside the furnace body goes upward; the design of the downward-slanting nozzle is used to prevent ash produced by combustion from falling and clogging the nozzle.

6. A garbage pyrolysis furnace as claimed in claim 5, characterized in that: The flue gas outlet is set on one side of the furnace top and connected to the two-stage tar removal device.

Images