Internal heating type rotary carbonization furnace for forward and reverse flow heating and process control method

Abstract

The invention discloses an internal heating type rotary carbonization furnace for forward and reverse flow heating and a process control method, and relates to a carbonization device. Comprising a feeder, a clockwise and anticlockwise circulation kiln, a high-temperature fuel gas channel, a discharging cabinet, a cooling charcoal discharging device, a low-temperature fuel gas channel, a medium-temperature fuel gas channel, a two-section type combustion furnace, a high-temperature flue and a circulating type regulation and control pipeline system. Raw material carbonization comprises two stages, one stage is a countercurrent carbonization stage which is mainly completed in a countercurrent carbonization furnace stage, raw materials face downwards, flue gas faces upwards, and most of water in the raw materials is gasified in the stage. 2, a down-flow carbonization stage is mainly completed in a down-flow carbonization furnace stage, the raw materials and flue gas move downwards, and most organic matters in the raw materials are cracked in the stage; a process control method comprises the steps of ignition, heating, feeding carbonization, gas ring formation, two-stage combustion, energy self-supply, carbonization temperature regulation and control and gas flow regulation and control. Compared with a conventional carbonization system, an additional drying link is omitted, equipment is simplified, and the stability of the carbonization effect is ensured.

Description

Technical Field

[0001] The invention relates to a carbonization device, in particular to an internal heating rotary carbonization furnace with forward and reverse flow heating and a process control method. Background Art

[0002] Biomass includes plants, animals, microorganisms, and all organic matter that can grow can be called biomass. Biomass pyrolysis carbonization is one of the important ways to utilize biomass energy at this stage, and we should vigorously promote the research and development of biomass pyrolysis carbonization technology and its equipment. As the earliest, most widely used and still widely used energy in human history, biomass energy still has great potential and room for development. It not only has good renewability, but its environmentally friendly characteristics also make it the trend of future energy.

[0003] In recent years, my country has vigorously supported the development and utilization of biomass energy, and pyrolysis processes and equipment have been rapidly developed and optimized. The carbonization device of biomass energy is generally a carbonization furnace, which includes an external heating carbonization furnace and an internal heating carbonization furnace. Among them, the internal heating carbonization furnace adopts a large cavity internal heating type, which has the advantages of simple operation, uniform distribution and heating, high thermal efficiency, low investment, rich industrial operation experience and large production capacity. It is an excellent low-temperature pyrolysis furnace. At the same time, this technology also has problems such as small single furnace production scale, backward automation control, limited raw material sources, and high energy consumption. It has become the primary problem hindering the efficient, environmentally friendly, and clean conversion and utilization of low-metamorphic coal.

[0004] Chinese patent CN111056553A discloses a high-yield rotary carbonization furnace for producing activated carbon. The device includes a furnace body that can rotate, the height of the furnace tail is higher than the height of the furnace head, a central air duct is arranged in the center of the furnace body, and there are several cavities arranged along the central air duct in the furnace body. Several ladder steps are arranged along the cavity wall in the cavity, which can increase the output of activated carbon. However, the carbonization method adopted by the equipment does not fully utilize the cracking gas generated by the material, and the energy consumption is high.

[0005] Chinese patent CN207435036U discloses a high-efficiency rotary steam activation furnace. The inner wall of the activation furnace is provided with a spiral steam pipe connected to the steam layer, and its outer wall is evenly surrounded by a number of steam nozzles. This design can increase the contact area between steam and materials, allowing steam and materials to fully contact, thereby improving efficiency and output. However, this patent has some shortcomings, and is lacking in wear resistance, high temperature resistance and water vapor preheating. During use, the wear of the inner wall of the furnace by coal and the corrosion of the furnace body by high-temperature flue gas and water vapor have not been fully considered.

[0006] Chinese patent CN118745356A discloses an anaerobic countercurrent rotary biomass carbonization furnace. Combining the principle of an externally heated fixed bed carbonization furnace, a rotary furnace body is used, which has the advantages of higher gas-solid heat transfer efficiency, faster biomass heating rate, more uniform temperature distribution, etc. Through the design of the return air pipe and hot air furnace, the uncooled carbonization gas is recovered and burned, combustible gas is effectively recycled, energy is saved and emissions are reduced.

[0007] Most existing biomass carbonization furnaces often only use countercurrent or cocurrent single-direction heating carbonization methods, and the single-direction flue gas flow means that the gaseous products of biomass raw material cracking are inseparable. In order to avoid the influence of moisture contained in biomass raw materials on the calorific value of cracking gas (fuel gas), when pyrolyzing biomass raw materials with high moisture content, it is often necessary to dry the biomass raw materials before entering the furnace. This requires additional drying equipment to ensure smooth carbonization, resulting in complex system structure and large equipment investment. Summary of the invention

[0008] The purpose of the present invention is to provide an internal heating rotary carbonization furnace with forward and reverse flow heating to address the shortcomings of existing carbonization equipment and processes, which has the characteristics of saving resources, good stability of the heat circulation system, high production efficiency, and stable quality of the finished carbonized material.

[0009] Another object of the present invention is to provide a process control method for an internal heating rotary carbonization furnace with forward and reverse flow heating.

[0010] In order to achieve the above-mentioned object of the invention, the present invention adopts the following specific scheme.

[0011] The present invention provides an internal heating rotary carbonization furnace with forward and reverse flow heating, comprising: a feeder, a forward and reverse flow rotary kiln, a high-temperature gas channel, a discharge cabinet, a cooling carbon discharger, a low-temperature gas channel at the kiln tail, a medium-temperature gas channel at the kiln head, a two-stage combustion furnace, a high-temperature flue and a circulating control pipeline system;

[0012] The feeder is arranged at the raw material inlet end of the kiln tail of the forward and reverse two-way flow rotary kiln, and is used to push the raw materials into the interior of the forward and reverse two-way flow rotary kiln;

[0013] The forward and reverse two-way flow rotary kiln adopts the form of a rotary kiln, and the kiln body is divided into a countercurrent carbonization furnace section and a forward carbonization furnace section, wherein the countercurrent carbonization furnace section is near the raw material inlet end of the kiln tail, and the forward carbonization furnace section is near the carbonization material outlet end of the kiln head;

[0014] The inlet of the high-temperature gas channel is connected to the circulating control pipeline system, and the outlet of the high-temperature gas channel is inserted into the interior of the forward and reverse two-way flow kiln and fixed by a support rod and a high-temperature rotary joint;

[0015] The discharge cabinet is arranged at the carbonized material outlet of the kiln head of the forward and reverse flow kiln, and is used to separate the carbonized material from the flue gas after carbonization;

[0016] The cooling carbon discharger is arranged at the bottom of the discharge cabinet, and is used to cool the carbonized material and send it out of the device for packaging;

[0017] The low-temperature gas channel is arranged at the raw material inlet end of the kiln tail of the forward and reverse flow rotary kiln, and collects the low-temperature gas generated by the countercurrent carbonization furnace section through a jacket; a low-temperature gas fan is arranged in the middle of the low-temperature gas channel to provide power for the flow of the low-temperature gas;

[0018] The medium-temperature gas channel is arranged on the discharge cabinet to lead out the medium-temperature gas generated by the downstream carbonization furnace section;

[0019] The two-stage combustion furnace is a device that burns low-temperature fuel gas and sub-high-temperature fuel gas. It can be an independent combustion device or a combustion furnace of a boiler. The generated high-temperature flue gas enters the high-temperature flue, and the excess flue gas is sent to the waste heat utilization device.

[0020] The inlet end of the high-temperature flue is connected to a two-stage combustion furnace, and the outlet end is connected to a circulating control pipeline system to lead out the high-temperature flue gas;

[0021] The circulating control pipeline system is a two-inlet and two-outlet pipeline structure, which introduces high-temperature flue gas through the high-temperature flue and medium-temperature gas through the medium-temperature gas channel; the generated sub-high-temperature gas is led out to the two-stage combustion furnace through the sub-high-temperature gas channel; the generated high-temperature gas is led out to the forward and reverse flow kiln through the high-temperature gas channel.

[0022] The forward and reverse two-way flow rotary kiln uses high-temperature combustion gas as the heat source for carbonizing raw materials; the high-temperature combustion gas in the forward and reverse two-way flow rotary kiln is divided into two parts, one part is powered by a low-temperature combustion gas fan, flows upward (at the furnace tail) and enters the countercurrent carbonization furnace section, and the other part is powered by a circulating control pipeline system, flows downward (at the furnace head) and enters the forward carbonization furnace section; in the countercurrent carbonization furnace section, a countercurrent heating method is adopted in which the raw materials are downward and the high-temperature combustion gas is upward; in the forward carbonization furnace section, a forward heating method is adopted in which both the raw materials and the high-temperature combustion gas are downward. In the countercurrent carbonization furnace section, the raw materials are first dehydrated and then carbonized; therefore, the low-temperature combustion gas generated in the countercurrent carbonization furnace section contains a large amount of water vapor, has a low calorific value, and is difficult to maintain combustion autonomously in the air; in the countercurrent carbonization furnace section, the organic components of the raw materials are pyrolyzed in large quantities, and the medium-temperature combustion gas generated has a low water vapor content, a high calorific value, and is easy to burn.

[0023] The present invention adopts a special two-stage combustion furnace design in view of the constraints of medium-temperature gas and low-temperature gas generated by the forward and reverse two-way flow kiln. The two-stage combustion furnace is provided with two zones, one is a high-temperature combustion zone, and the other is a medium-temperature combustion zone; the high-temperature combustion zone is connected to a sub-high-temperature gas channel and a blower for fully burning the sub-high-temperature gas to produce high-temperature flue gas; the medium-temperature combustion zone is connected to a low-temperature gas channel; the high-temperature flue gas enters the medium-temperature combustion zone and is burned with the low-temperature gas; the combustion includes two processes, one is a physical process, namely the "forging" process, which refers to the physical mixing of the high-temperature flue gas with the water vapor contained in the low-temperature gas to increase the temperature; the other is a chemical process, namely the "burning" process, which refers to the combustion and heat release of the combustible part contained in the low-temperature gas combined with the oxygen contained in the high-temperature flue gas. The medium-temperature combustion zone can also be provided with an auxiliary blower to supplement the required air for the chemical process of combustion. In the combustion process of the present invention, high-temperature flue gas is used to physically increase the temperature of water vapor contained in low-temperature fuel gas; and the "high-temperature oxygen" contained in the high-temperature flue gas is used to combust and release heat with the combustible part contained in the low-temperature fuel gas. The two-stage combustion furnace provided by the present invention can ensure the stable combustion of low-temperature fuel gas with high water vapor content and low calorific value.

[0024] At the furnace head of the forward and reverse two-way rotary kiln, there is a circulating control pipeline system. The topological structure of the circulating control pipeline system is a ring pipeline structure, which consists of a medium-temperature semi-ring and a high-temperature semi-ring; the medium-temperature semi-ring and the high-temperature semi-ring are interconnected, with the high-temperature flue gas inlet of the high-temperature flue and the gas inlet of the medium-temperature gas channel as the boundary. The medium-temperature semi-ring includes: a medium-temperature gas pipeline, a gas fan, a medium-temperature semi-ring valve and pipelines connected in sequence; the high-temperature semi-ring includes: a high-temperature flue, a carbonization fan, a high-temperature semi-ring valve and pipelines connected in sequence; the high-temperature semi-ring and the medium-temperature semi-ring are completely symmetrical in structure, and are connected head to tail to form a complete ring topological pipeline structure, in which the gas fan is symmetrical with the carbonization fan; the medium-temperature semi-ring valve is symmetrical with the high-temperature semi-ring valve; the medium-temperature gas channel is symmetrical with the high-temperature flue; the high-temperature gas channel is symmetrical with the sub-high-temperature gas channel.

[0025] In the circulating control pipeline system provided by the present invention, the sub-high temperature fuel gas flows through the gas fan and the medium temperature semi-ring valve in sequence; then it is heated to high temperature fuel gas and flows through the carbonization fan and the high temperature semi-ring valve, and then it is cooled to the sub-high temperature fuel gas and returns to the gas fan, thereby forming a circulating flow of fuel gas, that is, a fuel gas ring; when the medium temperature semi-ring valve and the high temperature semi-ring valve are fully opened, the fuel gas in the entire annular pipeline system forms the largest fuel gas ring. When the opening of the medium-temperature half-ring valve is reduced, the outflow of the sub-high-temperature gas in the gas ring will increase. At the same time, according to the characteristics of the ring, the inflow of the high-temperature flue gas in the gas ring will also increase accordingly, thereby increasing the temperature of the high-temperature gas and raising the carbonization temperature; vice versa; when the opening of the high-temperature half-ring valve is reduced, the inflow of the medium-temperature gas in the gas ring will increase. At the same time, according to the characteristics of the ring, the outflow of the high-temperature gas in the gas ring will also increase accordingly, thereby increasing the gas flow rate; vice versa; therefore, the circulating control pipeline system provided by the present invention can adjust the gas flow rate delivered to the forward and reverse flow kiln and adjust the temperature of the gas in the high-temperature gas channel.

[0026] The temperature of the low-temperature gas is between 100 and 250°C; the temperature of the medium-temperature gas is between 200 and 300°C; the temperature of the sub-high-temperature gas is between 300 and 500°C; the temperature of the high-temperature gas is above 400°C; and the temperature of the high-temperature flue gas is above 700°C.

[0027] In the equipment provided by the present invention, the carbonization of the raw materials in the forward and reverse flow rotary kiln mainly goes through two stages, and the heating methods in the forward and reverse flow rotary kiln are respectively for two directions, so the present invention is called "forward and reverse flow".

[0028] The first stage is the countercurrent carbonization stage, which is mainly completed in the countercurrent carbonization furnace section. In this stage, the raw material is heated downward and the gas is heated upward (reverse). Most of the water in the raw material is evaporated and carried away by the countercurrent gas, and the low calorific value cracking gas is sent to the medium temperature combustion zone of the two-stage combustion furnace. The second stage is the downstream carbonization stage, which is mainly completed in the downstream carbonization furnace section. In this stage, the raw material and the gas are heated downward (in the same direction). The raw material is carbonized and cracked under the action of the gas, and the high calorific value cracking gas is sent to the high temperature combustion zone of the two-stage combustion furnace.

[0029] In the first stage, the countercurrent carbonization stage, the raw materials are fed into the kiln in both forward and reverse directions through the feeder, and enter the countercurrent carbonization furnace section from the raw material inlet end of the kiln; after passing through the countercurrent carbonization furnace section, the raw materials enter the forward carbonization furnace section. The fuel gas enters the countercurrent carbonization furnace section from the middle section of the forward and reverse flow kiln through the high-temperature fuel gas channel. In the countercurrent carbonization furnace section, the fuel gas flows upward and the raw materials flow downward (in reverse direction), and the fuel gas gradually decreases from high temperature to low temperature; and the raw materials are heated to near medium temperature by the fuel gas. In this process, a large amount of water in the raw materials is gasified into water vapor, and at the same time, part of the organic matter in the raw materials is cracked into cracking gas, and then this part of the mixed gas is taken out of the forward and reverse flow kiln by the countercurrent fuel gas, and enters the medium temperature combustion zone of the two-stage combustion furnace through the low-temperature fuel gas channel.

[0030] In the second stage, i.e. the downstream carbonization stage, the raw materials pass through the countercurrent carbonization furnace section in the two-way rotary kiln and enter the downstream carbonization furnace section. The raw materials undergo high-temperature cracking in the downstream carbonization furnace section and finally enter the discharge cabinet and the cooling carbon discharger to realize the discharge. The fuel gas enters the downstream carbonization furnace section from the middle section of the two-way rotary kiln through the high-temperature fuel gas channel. In the downstream carbonization furnace section, the fuel gas and the raw materials are both downward (in the same direction), and the fuel gas gradually decreases from high temperature to medium temperature. In this process, the organic matter in the raw materials is further cracked, and most of the water in the raw materials has been decomposed. Therefore, the cracking gas produced in the downstream carbonization furnace section has a high calorific value. Then this part of the mixed gas is taken out of the two-way rotary kiln by the downstream fuel gas, and enters the high-temperature combustion zone of the two-stage combustion furnace through the medium-temperature fuel gas channel, the circulating control pipeline system and the sub-high-temperature fuel gas channel.

[0031] The device provided by the present invention can achieve the expected beneficial effect by operating according to the following process control method. A process control method for an internal heating rotary carbonization furnace with forward and reverse flow heating comprises the following steps:

[0032] Step 1, ignition: using an auxiliary burner to heat the high temperature combustion zone of the two-stage combustion furnace; the auxiliary burner can be a biomass pellet burner, a natural gas burner, a wood stove, an electric stove or other heating equipment;

[0033] Step 2, heating: The carbonization fan of the circulating control pipeline system is used to lead the high-temperature flue gas into the high-temperature gas channel to heat the forward and reverse flow kiln; the cooled high-temperature flue gas is led to the medium-temperature calcination area through the low-temperature gas fan, and then sent to the waste heat utilization equipment through the outlet of the two-stage combustion furnace for discharge;

[0034] Step 3, feeding and carbonization: using a feeder to push the raw materials into the forward and reverse flow kiln; using a low-temperature gas channel to draw out low-temperature gas; using a medium-temperature gas channel to draw out medium-temperature gas;

[0035] Step 4, gas ring formation: in the circulating control pipeline system, the sub-high temperature gas flows through the gas fan and the medium temperature half-ring valve in sequence; then it is heated to high temperature gas and flows through the carbonization fan and the high temperature half-ring valve, and then it is cooled to sub-high temperature gas and returns to the gas fan, thereby forming a circulating flow of gas, i.e., a gas ring;

[0036] Step 5, two-stage combustion: the sub-high temperature gas drawn from the circulating control pipeline system provides fuel for the high temperature combustion zone of the two-stage combustion furnace (8), forming high temperature flue gas to ensure the stability of the combustion furnace; the low temperature gas enters the medium temperature combustion zone from the low temperature gas channel to realize the combustion of the low calorific value cracking gas;

[0037] Step 6, energy self-supply: After the high-temperature flue gas generated by the two-stage combustion furnace provides carbonization energy for the forward and reverse flow rotary kiln, the auxiliary burner is turned off to achieve energy self-supply; the excess flue gas is sent to the waste heat utilization equipment to achieve efficient energy utilization;

[0038] Step 7, carbonization temperature regulation: In the circulating control pipeline system, reducing the opening of the medium-temperature half-ring valve will increase the outflow of the medium-temperature gas in the gas ring; at the same time, according to the characteristics of the ring, the inflow of high-temperature flue gas in the gas ring will also increase accordingly, thereby increasing the high-temperature gas temperature and the carbonization temperature; vice versa;

[0039] Step 8, regulation of gas flow: In the circulating control pipeline system, reducing the opening of the high-temperature half-ring valve will increase the inflow of medium-temperature gas in the gas ring; at the same time, according to the characteristics of the ring, the outflow of high-temperature gas in the gas ring will also increase accordingly, thereby achieving the effect of increasing the gas flow; and vice versa.

[0040] It can be seen from the above steps that the key point of the device provided by the present invention to realize the preset process is to control two stages: the ignition stage and the energy self-supply stage.

[0041] During the ignition stage, the auxiliary burner (such as biomass pellet burner, natural gas burner, wood stove, electric stove, etc.) heats the high-temperature combustion zone of the two-stage combustion furnace to provide a heat source, so that the two-stage combustion furnace is heated until it can provide high-temperature flue gas, heats the entire carbonization system, and then realizes the carbonization of the feed.

[0042] In the energy self-supply stage, the two-stage combustion furnace delivers high-temperature flue gas to the carbonization system through the high-temperature flue. The high-temperature flue gas is mixed with the sub-high-temperature fuel gas to form high-temperature fuel gas, which is then delivered to the forward and reverse flow kiln to provide energy for the carbonization of the raw materials. At the same time, the medium-temperature fuel gas and low-temperature fuel gas generated by the cracking of the raw materials are returned to the two-stage combustion furnace as fuel. The auxiliary burner can be further turned off to achieve cyclic operation under the condition of energy self-supply.

[0043] The forward and reverse two-way flow rotary kiln provided by the present invention will produce two streams of fuel gas: low-temperature fuel gas and medium-temperature fuel gas. Among them, the low-temperature fuel gas contains a large amount of water vapor and has the characteristics of low calorific value, and it is difficult to maintain stable combustion in the air. Therefore, in the equipment of the present invention, a circulating control pipeline system is used to first send the high-calorific value fuel gas into the high-temperature combustion zone; the high-temperature flue gas generated in the high-temperature combustion zone can ensure the stability of the combustion furnace and the normal operation of the carbonization system. Then, the low-calorific value low-temperature fuel gas enters the medium-temperature calcination zone of the two-stage combustion furnace. The water vapor contained in the low-temperature fuel gas will only affect the temperature of the medium-temperature calcination zone and the outlet of the combustion furnace, but will not affect the temperature of the high-temperature combustion zone. The excess flue gas in the two-stage combustion furnace is sent to the waste heat utilization equipment through the outlet of the combustion furnace. In this way, the stable operation of the combustion furnace and the carbonization rotary kiln is guaranteed, and efficient energy utilization is achieved.

[0044] The circulating control pipeline system provided by the present invention can realize the dual control of carbonization temperature and gas flow. In the circulating control pipeline system, the sub-high temperature gas in the sub-high temperature gas channel is mixed with the high temperature flue gas to form high temperature gas, and then enters the medium temperature half ring through the high temperature half ring valve, thereby forming a circulating flow of gas, that is, a gas ring; in the gas ring, the function of the medium temperature half ring valve is to adjust the inflow of high temperature flue gas, thereby controlling the temperature of high temperature gas, that is, controlling the carbonization temperature; in the gas ring, the function of the high temperature half ring valve is to adjust the inflow of medium temperature gas, thereby controlling the outflow of high temperature gas, that is, controlling the gas flow; therefore, the circulating control pipeline system designed by the present invention can effectively realize the dual control of carbonization temperature and gas flow by utilizing the characteristic principle of the ring.

[0045] In the present invention, the temperature of the low-temperature fuel gas is between 100 and 250°C; the temperature of the medium-temperature fuel gas is between 200 and 300°C; the temperature of the sub-high-temperature fuel gas is between 300 and 500°C; the temperature of the high-temperature fuel gas is above 400°C; and the temperature of the high-temperature flue gas is above 700°C.

[0046] The present invention has the following beneficial effects:

[0047] ① In the process of carbonizing raw materials in the forward and reverse flow rotary kiln of the present invention, since the temperature of water vaporization in the raw materials is much lower than the temperature of cracking of organic matter in the raw materials, most of the water in the raw materials is vaporized in the countercurrent carbonization stage, while most of the organic matter in the raw materials is cracked in the forward and reverse flow carbonization stage. Therefore, the water in the raw materials is mainly concentrated in the low-temperature fuel gas, while the calorific value of the medium-temperature fuel gas is almost unaffected by the moisture content of the raw materials. Compared with the previous carbonization rotary kiln, the forward and reverse flow rotary kiln omits the additional drying step, simplifies the system, and reduces costs.

[0048] ② The two-stage combustion furnace of the present invention adopts a two-stage combustion technology, which is divided into a high-temperature combustion zone and a medium-temperature combustion and calcination zone, which respectively deal with high calorific value and low calorific value gases. The high-temperature combustion zone uses sub-high temperature fuel gas as fuel, which is completely burned with the help of a blower to generate stable high-temperature flue gas. At the same time, the medium-temperature combustion and calcination zone receives the low-temperature fuel gas and raises its temperature through the "combustion-calcination" process - the high-temperature flue gas physically heats the water vapor in the low-temperature fuel gas, and at the same time, a combustion reaction occurs between the combustible components in the fuel gas and the oxygen contained in the high-temperature flue gas, further releasing heat. This two-stage combustion design ensures that low-temperature fuel gas with a higher water content can also burn stably in the medium-temperature combustion and calcination zone, without affecting the temperature of the high-temperature combustion zone, thereby ensuring the continuous and stable operation of the system.

[0049] ③ The circulating control pipeline system of the present invention adopts a ring topology structure, which is composed of a high-temperature half ring and a medium-temperature half ring, and can control the flow rate and temperature of the gas in each area. Utilizing the design concept of the gas ring, by adjusting the opening of the high-temperature half ring valve and the medium-temperature half ring valve, the temperature and flow of the high-temperature gas entering the forward and reverse flow kiln can be adjusted. For example, reducing the opening of the medium-temperature half ring valve can increase the inflow of high-temperature flue gas. According to the characteristics of the gas ring, the inflow of high-temperature flue gas in the gas ring also increases accordingly, thereby increasing the temperature of the high-temperature gas; similarly, according to the characteristics of the gas ring, reducing the opening of the high-temperature half ring valve can increase the flow of high-temperature gas. This design not only simplifies process control, but also improves the controllability and flexibility of the production process, facilitates the dual regulation of carbonization temperature and gas flow, and enables the system to adapt to different process requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0051] Figure 2 It is a schematic diagram of the circulating control pipeline system of the present invention.

[0052] The markings of the components in the figure are as follows: feeder (1), forward and reverse flow kiln (2), high temperature gas channel (3), discharge cabinet (4), cooling carbon discharger (5), low temperature gas channel (6), medium temperature gas channel (7), two-stage combustion furnace (8), high temperature flue (9) and circulating control pipeline system (10), low temperature gas fan (11), gas fan (12), medium temperature semi-ring valve (13), carbonization fan (14), high temperature semi-ring valve (15), blower (16), auxiliary blower (17), waste heat utilization equipment (18), feed screw (19), sub-high temperature gas channel (20). DETAILED DESCRIPTION

[0053] The present invention is described in detail below in conjunction with the embodiments and drawings. The protection scope of the present invention is not limited to the embodiments, and any changes made by those skilled in the art within the scope defined by the claims also fall within the protection scope of the present invention.

[0054] See also Figure 1 An embodiment of an internal heating rotary carbonization furnace with forward and reverse flow heating includes a feeder 1, a forward and reverse flow rotary kiln 2, a high-temperature gas channel 3, a discharge cabinet 4, a cooling carbon discharger 5, a low-temperature gas channel 6, a medium-temperature gas channel 7, a two-stage combustion furnace 8, a high-temperature flue 9, and a circulating control pipeline system 10.

[0055] The feeder 1 is arranged at the raw material inlet end of the kiln tail of the forward and reverse two-way flow kiln 2, and is used to push the raw materials into the forward and reverse two-way flow kiln 2 through the feed screw 19. The feeder 1 is a funnel-shaped container with an open size of 1.5m×1.5m. The feeder 1 is connected to a feed conveyor belt above, and the feeder 1 is connected to a feed screw 19 with a diameter of Φ0.5×3m at the bottom.

[0056] The forward and reverse two-way flow rotary kiln 2 adopts the form of a rotary kiln, and the kiln body is divided into a countercurrent carbonization furnace section and a downstream carbonization furnace section. Among them, the countercurrent carbonization furnace section is close to the raw material inlet end of the kiln tail, and the downstream carbonization furnace section is close to the carbonization material outlet end of the kiln head. In the countercurrent carbonization furnace section, the raw material is heated in a countercurrent manner with the high-temperature combustion gas upward; in the downstream carbonization furnace section, the raw material and the high-temperature combustion gas are both heated in a downstream manner with the raw material downward. In this embodiment, the dimensions of the forward and reverse two-way flow rotary kiln 2 are Φ1.9×12m in diameter, and the high-temperature combustion gas channel 3 extends from the kiln head into the rotary kiln. The 6m length near the raw material inlet end of the kiln is used as the countercurrent carbonization furnace section, and the 6m length near the raw material outlet end of the kiln head is used as the countercurrent carbonization furnace section. The length is used as the downstream carbonization furnace section. The kiln body of the forward and reverse two-way flow rotary kiln 2 forms an angle of 2° with the ground, and the rotation speed is 2 r / min. The raw materials move downward under the action of gravity during rotation, ensuring that the direction of movement of the gas and the raw materials in the countercurrent carbonization furnace section is opposite, that is, the countercurrent carbonization method. The forward and reverse two-way flow rotary kiln 2 uses high-temperature gas as the heat source for carbonization of raw materials; the high-temperature gas in the forward and reverse two-way flow rotary kiln 2 is divided into two parts, one part is powered by the low-temperature gas fan 11, flows upward (furnace tail) into the countercurrent carbonization furnace section, and the other part is powered by the circulating control pipeline system 10, flows downward (furnace head) into the downstream carbonization furnace section; in the countercurrent carbonization furnace section, a countercurrent heating method with the raw materials downward and the high-temperature gas upward is adopted; in the downstream carbonization furnace section, a downstream heating method with both the raw materials and the high-temperature gas downward is adopted.

[0057] The inlet of the high-temperature gas channel 3 is connected to the circulating control pipeline system 10, and the outlet of the high-temperature gas channel 3 is inserted into the interior of the forward and reverse flow rotary kiln 2 and fixed in the kiln by a support rod. The high-temperature gas channel 3 serves as a heat source, and the outlet of the high-temperature gas channel 3 is used as a boundary to formally divide the kiln body of the forward and reverse flow rotary kiln 2 into a countercurrent carbonization furnace section and a downstream carbonization furnace section. The high-temperature gas coming out of the outlet of the high-temperature gas channel 3 is divided into two flow directions: one part is powered by the low-temperature gas fan 11 and flows upward into the countercurrent carbonization furnace section; the other part is powered by the circulating control pipeline system 10 and flows downward into the downstream carbonization furnace section. The high-temperature gas channel 3 uses a 304 stainless steel seamless steel pipe with a diameter of Φ0.6m.

[0058] The discharge cabinet 4 is arranged at the kiln head carbonized material outlet end of the forward and reverse two-way flow kiln 2, and is used to separate the carbonized material from the medium-temperature fuel gas. In this embodiment, the discharge cabinet 4 is a square cabinet made of 304 stainless steel with a width of 2.5m, a height of 3m, and a thickness of 1m.

[0059] The cooling carbon discharger 5 is arranged at the bottom of the discharge cabinet 4. The cooling carbon discharger 5 uses a water-cooling spiral with a diameter of Φ0.5×3m to cool the carbonized material to room temperature and send it out of the device for packaging to achieve discharge.

[0060] The low-temperature gas channel 6 is arranged at the raw material inlet end of the kiln tail of the forward and reverse two-way rotary kiln 2, and collects the low-temperature gas generated by the countercurrent carbonization furnace section through a jacket; the low-temperature gas channel 6 uses a 304 stainless steel seamless steel pipe with a diameter of Φ0.5m; in the middle of the low-temperature gas channel 6, a low-temperature gas fan 11 is arranged, and the low-temperature gas fan 11 uses a stainless steel centrifugal fan with a full pressure of 2000Pa, a flow rate of 20000m³ / h, and a temperature resistance of 300℃, which is used to provide power for the flow of low-temperature gas. The low-temperature gas fan 11 ensures that the gas in the countercurrent carbonization furnace section is directed upward, and sends the low-calorific value low-temperature gas into the two-stage combustion furnace 8.

[0061] The medium temperature gas channel 7 is provided on the discharge cabinet 4, and is used to lead out the medium temperature gas generated by the downstream carbonization furnace section. The medium temperature gas channel 7 uses a 304 stainless steel seamless steel pipe with a diameter of Φ0.5m. The medium temperature gas channel 7 uses a 304 stainless steel seamless steel pipe with a diameter of Φ0.5m. Similarly, the raw material moves downward under the action of gravity and wind force, and the movement direction of the gas and the raw material is the same, that is, the downstream carbonization method.

[0062] The two-stage combustion furnace 8 is a device for burning low-temperature gas and sub-high-temperature gas. It can be an independent combustion device or a combustion furnace of a boiler. The high-temperature flue gas generated by the combustion of the two-stage combustion furnace 8 enters the high-temperature flue 9, and the excess flue gas is sent to the waste heat utilization device 18. The two-stage combustion furnace 8 adopts a circular furnace body with a size of Φ2.2×8m in diameter. The waste heat utilization device 18 uses a waste heat boiler with a capacity of 6t / h and a pressure of 1Mpa to recover energy from the excess flue gas of the two-stage combustion furnace 8.

[0063] The two-stage combustion furnace 8 includes two zones, one is a high-temperature combustion zone, and the other is a medium-temperature combustion zone; the high-temperature combustion zone of the two-stage combustion furnace 8 is connected to a sub-high-temperature gas channel 20 and a blower 16, which is used to fully burn the sub-high-temperature gas and generate high-temperature flue gas; the blower 16 uses a conventional centrifugal fan with a total pressure of 500Pa and a flow rate of 10,000 m³ / h; the sub-high-temperature gas channel 20 is connected to the circulating control pipeline system 10 and the two-stage combustion furnace 8, which is used to lead out the sub-high-temperature gas.

[0064] The high-temperature flue gas generated in the high-temperature combustion zone of the two-stage combustion furnace 8 enters the medium-temperature combustion zone and is combusted with the low-temperature fuel gas. The combustion process includes physical and chemical processes: the physical process refers to the physical mixing of the high-temperature flue gas with the water vapor contained in the low-temperature fuel gas to increase the temperature; the chemical process refers to the combustion heat release of the combustible part contained in the low-temperature fuel gas combined with the oxygen contained in the high-temperature flue gas.

[0065] The medium temperature combustion zone of the two-stage combustion furnace 8 is connected to the kiln tail low temperature gas channel 6. The medium temperature combustion zone can also be provided with an auxiliary blower 17, and the auxiliary blower 17 uses a conventional centrifugal fan with a total pressure of 500Pa and a flow rate of 5000m³ / h.

[0066] The auxiliary burner provided at the furnace head of the two-stage combustion furnace 8 is a 900,000 kcal biomass pellet burner, which provides a heat source during the ignition phase and is turned off during the energy self-supply phase. The waste heat utilization device 18 provided at the furnace tail outlet of the two-stage combustion furnace 8 is a waste heat boiler with a capacity of 6 t / h and a pressure of 1 MPa, which recovers the excess flue gas of the two-stage combustion furnace 8.

[0067] The inlet end of the high-temperature flue 9 is connected to the two-stage combustion furnace 8, and the outlet end of the high-temperature flue 9 is connected to the circulating control pipeline system 10 to lead out the high-temperature flue gas. The high-temperature flue 9 is made of high-temperature refractory bricks, and the inner cross-sectional area is 0.6×0.6m. The high-temperature flue 9 sends the 900°C high-temperature flue gas generated by the combustion of the two-stage combustion furnace 8 into the forward and reverse two-way flow kiln 2. A circulating control pipeline system 10 is set between the high-temperature flue 9 and the medium-temperature gas channel 7 to control the flow of gas, and produce 600°C high-temperature gas, and send the high-temperature gas into the forward and reverse two-way flow kiln 2 through the carbonization fan 14. The air supply port of the carbonization fan 14 is connected to the high-temperature gas channel 3 to send the high-temperature gas into the forward and reverse two-way flow kiln 2. The carbonization fan 14 uses a stainless steel centrifugal fan with a total pressure of 2000Pa, a flow rate of 25000m3 / h, and a temperature resistance of 700°C.

[0068] like Figure 1 and 2The circulating control pipeline system 10 is a two-inlet and two-outlet pipeline structure. The circulating control pipeline system 10 is arranged between the high-temperature flue 9 and the medium-temperature gas channel 7. The two inlets introduce high-temperature flue gas through the high-temperature flue 9 and the medium-temperature gas through the medium-temperature gas channel 7. One outlet leads the generated sub-high-temperature gas to the two-stage combustion furnace 8 through the sub-high-temperature gas channel 20; the other outlet leads the generated high-temperature gas to the forward and reverse two-way flow kiln 2 through the high-temperature gas channel 3. The topological structure of the circulating control pipeline system 10 is a ring pipeline structure, which is composed of a medium-temperature semi-ring and a high-temperature semi-ring. The medium-temperature semi-ring of the circulating control pipeline system 10 includes a medium-temperature gas channel 7, a gas blower 12, a medium-temperature semi-ring valve 13 and pipelines connected in sequence; the high-temperature semi-ring includes a high-temperature flue 9, a carbonization blower 14, a high-temperature semi-ring valve 15 and pipelines connected in sequence. The high-temperature semi-ring valve 15 connects the high-temperature gas channel 3 with the medium-temperature gas channel 7. The structures of the high-temperature half ring and the medium-temperature half ring are completely symmetrical, and the heads and tails are connected to each other to form a complete ring topology pipeline structure, wherein the gas blower 12 is symmetrical to the carbonization blower 14; the medium-temperature half ring valve 13 is symmetrical to the high-temperature half ring valve 15; the medium-temperature gas channel 7 is symmetrical to the high-temperature flue 9; the high-temperature gas channel 3 is symmetrical to the sub-high-temperature gas channel 20. In the medium-temperature half ring of the circulating control pipeline system 10, the high-temperature gas is mixed with the low-temperature gas to generate sub-high-temperature gas; in the high-temperature half ring of the circulating control pipeline system 10, the high-temperature flue gas is mixed with the sub-high-temperature gas; further, the oxygen content in the high-temperature flue gas is consumed, and the temperature of the sub-high-temperature gas is increased, thereby forming the oxygen-free high-temperature gas. The gas blower 12 is a stainless steel centrifugal blower with a total pressure of 2000Pa, a flow rate of 30000m³ / h, and a temperature resistance of 500℃; the gas blower 12 is used to ensure that the gas in the downstream carbonization furnace section is directed downward, and to send the high calorific value cracking gas into the circulating control pipeline system 10 through the kiln head medium temperature gas channel 7. The carbonization blower 14 is a stainless steel centrifugal blower with a total pressure of 2000Pa, a flow rate of 25000m³ / h, and a temperature resistance of 700℃. The medium temperature half ring valve 13 and the high temperature half ring valve 15 are both high temperature butterfly valves with a diameter of Φ0.6 and a temperature resistance of 800℃, which are used to send excess gas back to the pipeline system into circulation to realize the gas ring.

[0069] The working principle of the internal heating rotary carbonization furnace with forward and reverse flow heating of the present invention is as follows:

[0070] Raw material feeding: The raw material is pushed into the interior of the forward and reverse two-way flow kiln 2 through the feeder 1 and the feed screw 19. The feeder 1 is a funnel-shaped container, with a feed conveyor belt connected to the top and a feed screw 19 connected to the bottom.

[0071] Carbonization process: The raw materials are divided into a countercurrent carbonization furnace section and a downstream carbonization furnace section for carbonization in the countercurrent two-way rotary kiln 2. In the countercurrent carbonization furnace section, the raw materials move downward, and the high-temperature gas flows upward through the power provided by the low-temperature gas fan 11, forming a countercurrent heating method. In the downstream carbonization furnace section, both the raw materials and the high-temperature gas move downward, forming a downstream heating method. The high-temperature gas channel 3 serves as a heat source, and its outlet divides the kiln body into a countercurrent carbonization furnace section and a downstream carbonization furnace section.

[0072] Gas circulation and regulation: The high-temperature gas comes out from the high-temperature gas channel 3 and is divided into two parts: one part enters the countercurrent carbonization furnace section through the low-temperature gas fan 11, and the other part enters the downstream carbonization furnace section through the circulating regulation pipeline system 10. The circulating regulation pipeline system 10 is a two-inlet and two-outlet pipeline structure, which is arranged between the medium-temperature gas channel 7 and the high-temperature flue 9, and is used to control the gas flow and produce 600°C high-temperature gas. The medium-temperature gas channel 7 leads out the medium-temperature gas generated in the downstream carbonization furnace section, and the sub-high-temperature gas channel 20 leads out the sub-high-temperature gas generated by the circulating regulation pipeline system 10 to the two-stage combustion furnace 8.

[0073] Two-stage combustion and waste heat utilization: The two-stage combustion furnace 8 includes a high-temperature combustion zone and a medium-temperature combustion zone, which are used to burn low-temperature fuel gas and sub-high-temperature fuel gas to produce high-temperature flue gas. The high-temperature flue gas enters the high-temperature flue 9, part of which is sent to the forward and reverse two-way flow kiln 2, and the excess is sent to the waste heat utilization device 18 for energy recovery. The waste heat utilization device 18 uses a waste heat boiler to recover energy from the excess flue gas of the two-stage combustion furnace 8.

[0074] Discharging and cooling: The carbonized material after carbonization is separated from the medium-temperature fuel gas in the discharging cabinet 4, then cooled to room temperature by the cooling carbon discharging device 5, and sent out of the device for packaging.

[0075] System control and auxiliary equipment: The carbonization fan 14 is used to deliver high-temperature fuel gas to the forward and reverse two-way flow kiln 2, and regulates the gas flow through the high-temperature half-ring valve 15. The gas fan 12 is used to ensure that the fuel gas in the forward carbonization furnace section is directed downward, and regulates the gas flow through the medium-temperature half-ring valve 13. The auxiliary blower 17 provides additional air volume in the medium-temperature combustion zone of the two-stage combustion furnace 8. The auxiliary burner set at the furnace head of the two-stage combustion furnace 8 provides a heat source during the ignition stage and is turned off during the energy self-supply stage.

[0076] The internal heating rotary carbonization furnace with forward and reverse flow heating described in the present invention realizes an efficient and energy-saving carbonization process through the forward and reverse flow heating method combined with the precise control of the gas by the circulating control pipeline system 10, and recovers the energy of excess flue gas through the waste heat utilization equipment 18, thereby improving the overall energy utilization efficiency.

[0077] In conjunction with the embodiments of the present invention, the process control method is further described in detail, including the following steps:

[0078] Step 1, ignition: using a 900,000 kcal biomass pellet burner to heat the high temperature combustion zone of the two-stage combustion furnace 8, raising the temperature of the high temperature combustion zone to 900°C;

[0079] Step 2, heating: the carbonization fan 14 of the circulating control pipeline system 10 is used to lead the 900°C high-temperature flue gas into the high-temperature fuel gas channel 3 to heat the forward and reverse flow kiln 2; the temperature of the high-temperature flue gas after cooling is 250°C, and it is led to the medium-temperature calcination zone through the low-temperature fuel gas fan 11, and then sent to the waste heat utilization device 18 through the outlet of the combustion furnace for discharge;

[0080] Step 3, carbonization: When the average temperature inside the heated forward and reverse two-way rotary kiln 2 reaches 400°C, feed the raw materials. Use the feeder 1 to push the raw materials into the forward and reverse two-way rotary kiln 2; the raw materials undergo cracking reaction in the kiln body, and after generating fuel gas, the low-temperature fuel gas of 150°C is drawn out through the low-temperature fuel gas channel 6; the medium-temperature fuel gas of 300°C is drawn out through the medium-temperature fuel gas channel 7;

[0081] Step 4, gas ring formation: In the circulating control pipeline system 10, the sub-high temperature gas of 400°C flows through the gas fan 12 and the medium temperature half-ring valve 13 in sequence; then the high temperature gas heated to 600°C flows through the carbonization fan 14 and the high temperature half-ring valve 15, and then the sub-high temperature gas cooled to 400°C returns to the gas fan 12, forming a circulating flow of gas, i.e., a gas ring;

[0082] Step 5, two-stage combustion: 400°C sub-high temperature gas is drawn from the circulating control pipeline system 10 to provide fuel for the high temperature combustion zone of the two-stage combustion furnace 8, forming 900°C high temperature flue gas; 150°C low temperature gas enters the medium temperature combustion zone from the low temperature gas channel 6 to realize the combustion of low calorific value cracking gas, and the combustion flue gas temperature is 750°C;

[0083] Step 6, energy self-supply: the high-temperature flue gas generated by the two-stage combustion furnace 8 provides carbonization energy for the forward and reverse two-way rotary kiln 2; at this time, the biomass pellet burner is turned off, and the energy self-supply is completely achieved by gas; the excess flue gas is sent to the waste heat utilization equipment 18, which can generate 3t / s, 1Mpa high-pressure steam to achieve efficient energy utilization;

[0084] Step 7, carbonization temperature regulation: In the circulating control pipeline system 10, if the actual temperature of the high-temperature gas is lower than 600°C, the carbonization degree will be insufficient. At this time, the opening of the medium-temperature half-ring valve 13 is reduced, the outflow of the sub-high-temperature gas in the gas ring is increased, and the inflow of the sub-high-temperature flue gas in the gas ring is also increased accordingly; this regulation will slowly increase the temperature of the high-temperature gas to increase the carbonization temperature; vice versa;

[0085] Step 8, gas flow control: In the circulating control pipeline system 10, if the temperature of the high-temperature flue gas is lower than 700°C, it means that the gas flow is insufficient, which will cause the risk of flameout of the combustion furnace. At this time, the opening of the high-temperature semi-ring valve 15 is reduced, the inflow of the medium-temperature gas in the gas ring is increased, and the outflow of the sub-high-temperature gas in the gas ring is also increased accordingly, thereby achieving the effect of increasing the gas flow; this control will further effectively improve the state of the high-temperature combustion zone and increase the temperature of the combustion furnace; vice versa.

[0086] The above embodiments are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An internal heating rotary carbonization furnace with forward and reverse flow heating, characterized in that: It comprises a feeder (1), a forward and reverse two-way rotary kiln (2), a high-temperature gas channel (3), a discharge cabinet (4), a cooling charcoal discharger (5), a low-temperature gas channel (6), a medium-temperature gas channel (7), a two-stage combustion furnace (8), a high-temperature flue (9) and a circulating control pipeline system (10); The feeder (1) is arranged at the raw material inlet end of the kiln tail of the forward and reverse two-way flow rotary kiln (2) and is used to push the raw materials into the forward and reverse two-way flow rotary kiln (2); The forward and reverse two-way flow rotary kiln (2) is in the form of a rotary kiln, and the kiln body is divided into a countercurrent carbonization furnace section and a forward carbonization furnace section, wherein the countercurrent carbonization furnace section is near the raw material inlet end of the kiln tail, and the forward carbonization furnace section is near the carbonized material outlet end of the kiln head; The inlet of the high-temperature gas channel (3) is connected to a circulating control pipeline system (10), and the outlet of the high-temperature gas channel (3) is inserted into the interior of the forward and reverse two-way flow rotary kiln (2); The discharge cabinet (4) is arranged at the kiln head carbonized material outlet end of the forward and reverse flow kiln (2) and is used to separate the carbonized material from the medium-temperature fuel gas after carbonization; The cooling carbon discharger (5) is arranged at the bottom of the discharge cabinet (4) and is used to cool the carbonized material and send it out of the device for packaging; The low-temperature gas channel (6) is arranged at the raw material inlet end of the kiln tail of the forward and reverse flow rotary kiln (2), and collects the low-temperature gas generated by the countercurrent carbonization furnace section through a jacket; a low-temperature gas fan (11) is arranged in the middle of the low-temperature gas channel (6) to provide power for the flow of the low-temperature gas; The medium-temperature fuel gas channel (7) is provided on the discharge cabinet to lead out the medium-temperature fuel gas generated by the downstream carbonization furnace section; The two-stage combustion furnace (8) is a device for burning low-temperature fuel gas and sub-high-temperature fuel gas, and uses an independent combustion device or a combustion furnace of a boiler; the high-temperature flue gas generated by the combustion enters the high-temperature flue (9), and the excess flue gas is sent to the waste heat utilization device (18); The inlet end of the high-temperature flue (9) is connected to the two-stage combustion furnace (8), and the outlet end is connected to the circulating control pipeline system (10) to lead out the high-temperature flue gas; The circulating control pipeline system (10) is a two-inlet and two-outlet pipeline structure, wherein high-temperature flue gas is introduced through a high-temperature flue (9) and medium-temperature fuel gas is introduced through a medium-temperature fuel gas channel (7); the generated sub-high-temperature fuel gas is led out to a two-stage combustion furnace (8) through a sub-high-temperature fuel gas channel (20); and the generated high-temperature fuel gas is led out to a forward and reverse two-way rotary kiln (2) through a high-temperature fuel gas channel (3).

2. According to claim 1, the internal heating rotary carbonization furnace with forward and reverse flow heating is characterized in that: The forward and reverse two-way flow rotary kiln (2) uses high-temperature combustion gas as a heat source for carbonizing raw materials; the high-temperature combustion gas in the forward and reverse two-way flow rotary kiln (2) is divided into two parts, one part is powered by a low-temperature combustion gas fan (11) and flows upward (to the furnace tail) into the countercurrent carbonization furnace section, and the other part is powered by a circulating control pipeline system (10) and flows downward (to the furnace head) into the forward carbonization furnace section; in the countercurrent carbonization furnace section, a countercurrent heating method is adopted in which the raw materials flow downward and the high-temperature combustion gas flows upward; in the forward carbonization furnace section, a forward heating method is adopted in which both the raw materials and the high-temperature combustion gas flow downward.

3. The internal heating rotary carbonization furnace with forward and reverse flow heating according to claim 1, characterized in that: The two-stage combustion furnace (8) is provided with two zones, one is a high-temperature combustion zone, and the other is a medium-temperature combustion zone; the high-temperature combustion zone is connected to a sub-high-temperature fuel gas channel (20) and a blower (16) for fully burning the sub-high-temperature fuel gas to generate high-temperature flue gas; the medium-temperature combustion zone is connected to a kiln tail low-temperature fuel gas channel (6); the high-temperature fuel gas enters the medium-temperature combustion zone and is burned with the low-temperature fuel gas; the combustion includes two processes, one is a physical process, which refers to the physical mixing of the high-temperature fuel gas with the water vapor contained in the low-temperature fuel gas to increase the temperature; the other is a chemical process, which refers to the combustion and heat release of the combustible part contained in the low-temperature fuel gas combined with the oxygen contained in the high-temperature fuel gas.

4. The internal heating rotary carbonization furnace with forward and reverse flow heating according to claim 1, characterized in that: The topological structure of the circulating control pipeline system (10) is a ring pipeline structure, which is composed of a medium-temperature semi-ring and a high-temperature semi-ring; the medium-temperature semi-ring includes: a medium-temperature gas pipeline (7), a gas fan (12), a medium-temperature semi-ring valve (13) and pipelines connected in sequence; the high-temperature semi-ring includes: a high-temperature flue (9), a carbonization fan (14), a high-temperature semi-ring valve (15) and pipelines connected in sequence; the high-temperature semi-ring and the medium-temperature semi-ring are completely symmetrical in structure, and are connected end to end to form a complete ring topological pipeline structure, wherein the gas fan (12) is symmetrical to the carbonization fan (14); the medium-temperature semi-ring valve (13) is symmetrical to the high-temperature semi-ring valve (15); the medium-temperature gas duct (7) is symmetrical to the high-temperature flue (9); and the high-temperature gas duct (3) is symmetrical to the sub-high-temperature gas duct (20).

5. The internal heating rotary carbonization furnace with forward and reverse flow heating according to claim 4, characterized in that: In the medium-temperature half-ring of the circulating control pipeline system (10), the high-temperature fuel gas is mixed with the low-temperature fuel gas to generate a sub-high-temperature fuel gas; in the high-temperature half-ring of the circulating control pipeline system (10), the high-temperature flue gas is mixed with the sub-high-temperature fuel gas; the oxygen content in the high-temperature flue gas is consumed, and the temperature of the sub-high-temperature fuel gas is increased, thereby forming oxygen-free high-temperature fuel gas.

6. The internal heating rotary carbonization furnace with forward and reverse flow heating according to claim 1, characterized in that: The temperature of the low-temperature gas is between 100 and 250°C; the temperature of the medium-temperature gas is between 200 and 300°C; the temperature of the sub-high-temperature gas is between 300 and 500°C; the temperature of the high-temperature gas is above 400°C; and the temperature of the high-temperature flue gas is above 700°C.

7. A process control method for an internal heating rotary carbonization furnace with forward and reverse flow heating, characterized in that The steps include: Step 1, ignition: using an auxiliary burner to heat the high temperature combustion zone of the two-stage combustion furnace (8); the auxiliary burner is a biomass pellet burner, a natural gas burner, a wood stove or an electric stove; Step 2, heating: using the carbonization fan (14) of the circulating control pipeline system (10) to lead the high-temperature flue gas into the high-temperature fuel gas channel (3), heating the forward and reverse flow kiln (2); the high-temperature flue gas after cooling is led out to the medium-temperature calcination zone through the low-temperature fuel gas fan (11), and then sent to the waste heat utilization device (18) through the outlet of the two-stage combustion furnace for discharge; Step 3, feeding and carbonization: using the feeder (1) to push the raw materials into the interior of the forward and reverse two-way flow kiln (2); using the low-temperature gas channel (6) to draw out the low-temperature gas; using the medium-temperature gas channel (7) to draw out the medium-temperature gas; Step 4, gas ring formation: in the circulating control pipeline system (10), the sub-high temperature gas flows through the gas fan (12) and the medium temperature half ring valve (13) in sequence; then it is heated to high temperature gas and flows through the carbonization fan (14) and the high temperature half ring valve (15); then it is cooled to sub-high temperature gas and returns to the gas fan (12), thereby forming a circulating flow of gas, i.e., a gas ring; Step 5, two-stage combustion: the sub-high temperature fuel gas drawn from the circulating control pipeline system (10) provides fuel for the high temperature combustion zone of the two-stage combustion furnace (8), forming high temperature flue gas to ensure the stability of the combustion furnace; the low temperature fuel gas enters the medium temperature combustion zone from the low temperature fuel gas channel (6) to realize the combustion of the low calorific value cracking gas; Step 6, energy self-supply: After the high-temperature flue gas generated by the two-stage combustion furnace (8) provides carbonization energy for the forward and reverse flow kiln (2), the auxiliary burner is turned off to achieve energy self-supply; the excess flue gas is sent to the waste heat utilization device (18) to achieve efficient energy utilization; Step 7, regulating the carbonization temperature: in the circulating regulating pipeline system (10), reducing the opening of the medium temperature half ring valve (13) will increase the outflow of the medium temperature gas in the gas ring. At the same time, according to the characteristics of the ring, the inflow of the high temperature flue gas in the gas ring will also increase accordingly, thereby increasing the temperature of the high temperature gas and the carbonization temperature; and vice versa; Step 8, gas flow control: In the circulating control pipeline system (10), reducing the opening of the high-temperature half-ring valve (15) will increase the inflow of medium-temperature gas in the gas ring. At the same time, according to the characteristics of the ring, the outflow of high-temperature gas in the gas ring will also increase accordingly, thereby achieving the effect of increasing the gas flow; and vice versa.

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