A solid waste pyrolysis device with low pollutant emissions

Abstract

The present invention relates to the technical field of pyrolysis and gasification of solid waste, and specifically to a solid waste pyrolysis equipment with low pollutant emissions. The present invention includes a furnace body with a grate, a gas supply pipe for supplying gas to the slag cavity, an ignition pipe for igniting the slag cavity, a pyrolysis gas exhaust pipe for exhausting the pyrolysis cavity, and a circulating gas pipe for connecting the slag cavity and the pyrolysis cavity, wherein the air inlet end of the circulating gas pipe is connected to the pyrolysis cavity, and the air outlet end of the circulating gas pipe is connected to the slag cavity; a flow control valve for controlling the gas flow in the cavity is arranged on the circulating gas pipe. The present invention can ensure the stable pyrolysis of low calorific value solid waste in the furnace by the heat generated by spontaneous combustion during stable operation without adding an external heat source, thereby achieving efficient use of heat, and can also increase the residence time of the pyrolysis gas at high temperature, improve the quality and calorific value of the pyrolysis gas, and reduce pollutant emissions.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste pyrolysis and gasification, and in particular to a solid waste pyrolysis device with low pollutant emission. Background Art

[0002] At present, the main methods of solid waste disposal include sanitary landfill, material manufacturing, composting, combustion and pyrolysis. Sanitary landfill, material manufacturing, composting and other methods will cause secondary pollution. Although the use of combustion method solves the impact of secondary pollution, the large amount of flue gas produced by combustion contains NO x 、SO 2 , dioxins, fly ash, VOC, etc., and the cost of monitoring and purifying flue gas is high. The pyrolysis gasification treatment of solid waste not only produces combustible gas for subsequent energy utilization, but also inhibits the generation of nitrogen oxides and sulfur dioxide in a reducing atmosphere. The fly ash carried by the pyrolysis gas through a thicker material layer is greatly reduced compared to the combustion process. Compared with other treatment methods, it has the characteristics of high energy conversion rate, low secondary pollution and low cost. In the existing pyrolysis gasification technology, the pyrolysis gas produced contains more impurities, such as CO 2 , water, N 2 At the same time, the pyrolysis gas will also carry a lot of tar to block the gas pipe, and the calorific value of the pyrolysis gas will be reduced during the tar condensation process, and the heat exchange efficiency of the subsequent pyrolysis gas incineration equipment will be reduced, and the maintenance cost will increase, so it needs to be solved urgently. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a solid waste pyrolysis equipment with low pollutant emissions, which can ensure the stable pyrolysis of low calorific value solid waste in the furnace by the heat generated by spontaneous combustion during stable operation and without adding an external heat source, thereby achieving efficient utilization of heat, and at the same time increasing the residence time of the pyrolysis gas at high temperature, improving the quality and calorific value of the pyrolysis gas, and ultimately reducing pollutant emissions.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A solid waste pyrolysis device with low pollutant emissions, comprising a furnace body with a grate, characterized in that the grate divides the furnace cavity of the furnace body into a pyrolysis chamber located above the grate and a slag chamber located below the grate, solid waste falls into the pyrolysis chamber from above the furnace cavity and is discharged from the slag chamber after pyrolysis; the device also includes an air supply pipe for supplying air to the slag chamber, an ignition pipe for igniting the slag chamber, a pyrolysis gas exhaust pipe for exhausting the pyrolysis chamber, and a circulating gas pipe for connecting the slag chamber and the pyrolysis chamber, the air inlet end of the circulating gas pipe is connected to the pyrolysis chamber, and the air outlet end of the circulating gas pipe is connected to the slag chamber; a flow control valve for controlling the gas flow in the pipe cavity is arranged on the circulating gas pipe.

[0006] An outer sleeve is arranged at the outer wall of the furnace body, and an air layer for accommodating air is formed between the outer sleeve and the outer wall of the furnace body. The air inlet of the air layer is connected to an external air source, and the air outlet of the air layer is connected to the inlet of the air supply pipe.

[0007] The outer wall of the outer sheath is wrapped with refractory material and heat-insulating material.

[0008] A steam discharge pipe is arranged beside the gas supply pipe, one end of the steam discharge pipe is connected to an external steam generator, and the other end is connected to the slag chamber.

[0009] The equipment also includes a desulfurization spray pipe for spraying a desulfurization solution and a denitration spray pipe for spraying a denitration solution. The spray ports of the desulfurization spray pipe and the denitration spray pipe are both installed on the top of the pyrolysis chamber.

[0010] The equipment includes a spiral feeding assembly for feeding materials into a feeding port at the top of a furnace body; the spiral feeding assembly includes an upper spiral feeding section, a lower spiral feeding section, and a sealed storage bin located between the two groups of feeding sections and serving as a connection and transition function; sealed doors that can be opened and closed are arranged between the inlet of the sealed storage bin and the outlet of the upper spiral feeding section, and between the outlet of the sealed storage bin and the inlet of the lower spiral feeding section.

[0011] The equipment comprises a spiral slag discharge assembly connected to a discharge port at the bottom of the furnace body. The slag enters the slag discharge bin below from the slag cavity and is finally discharged from the spiral slag discharge assembly.

[0012] The grate is a reciprocating spiral grate, comprising an inner spiral section and an outer spiral section in the same direction, wherein the outer spiral section is fixed on the furnace body, and the inner spiral section is connected to the working end of the cam machine.

[0013] The ignition tube constitutes the ignition outlet pipe of the diesel ignition assembly. The axis of the ignition tube is coaxial with the axis of the furnace body. The ignition tube includes an inner sleeve and an outer sleeve that are sleeved together. The inner sleeve is a diesel pipe with an atomizing nozzle arranged at the outlet. An annular airway for air flow is formed between the outer sleeve and the inner sleeve.

[0014] The furnace body is provided with a thermocouple for detecting the temperature in the furnace, and an observation window for observing the condition in the furnace is also provided on the furnace body; the thermocouple and the observation window are arranged in sequence from top to bottom along the axis of the furnace body, and the installation areas of the thermocouple and the observation window avoid each other in space.

[0015] The beneficial effects of the present invention are:

[0016] 1) Through the above scheme, the present invention adopts a grate-type pyrolysis furnace structure, so that solid waste is fed from the top and pyrolyzed in the pyrolysis chamber, and the slag after combustion is discharged from the slag chamber, thereby achieving a process-based pyrolysis treatment effect. More importantly: the present invention also uses the method of lower air supply to make the solid waste particles in the lower part of the furnace body burn and consume most of the oxidant, causing the solid waste particles in the upper part of the furnace body to be in an oxygen-deficient state; at the same time, the heat generated during the combustion process in the lower part is also transmitted to the upper part, and the circulating air pipe with a controllable flow rate that continuously extracts oxygen from the upper part of the furnace body forms a high-temperature and low-oxygen atmosphere in the upper part of the furnace body, thereby effectively ensuring the rapid generation of material layer partitions from top to bottom, that is, forming a drying layer, a reduction layer, an oxidation layer, and an ash layer from top to bottom in the furnace chamber. The present invention rapidly forms the above-mentioned material layer partitions through the circulation of pyrolysis gas, thereby ensuring stable pyrolysis of low calorific value solid waste in the furnace without adding an external heat source, and at the same time increasing the residence time of the pyrolysis gas at high temperature, reducing the tar content in the pyrolysis gas, thereby improving the quality and calorific value of the pyrolysis gas, and reducing the emission of pollutants such as sulfur dioxide, nitrogen oxides, dioxins, and fly ash.

[0017] 2) When the present invention is actually used, the pyrolysis object can be solid waste particles with certain mechanical strength and thermal stability, so that they are not easy to break during the combustion process, reducing the generation of fly ash; and the pyrolysis gas is partitioned by a thicker material layer and then output from the furnace body along the top of the furnace body, and the pyrolysis gas is not easy to carry fly ash out of the furnace.

[0018] 3) The maximum temperature of the solid waste particles in the lower part of the furnace of the present invention is above 1000°C. At the same time, the circulating gas pipe draws gas from the top of the furnace body and sends it to the bottom of the furnace body, which increases the gas travel in the furnace and ensures that the gas has sufficient residence time at a relatively high temperature, thereby further effectively reducing the generation of dioxins.

[0019] 4) Based on the above structure, the present invention is also arranged with a spray assembly, that is, including a denitration spray pipe and a desulfurization spray pipe. The denitration spray pipe and the desulfurization spray pipe spray desulfurization and denitration solutions respectively to remove sulfur dioxide and nitrogen oxides in the combustible gas. In addition, the arrangement of the steam discharge pipe can be matched with a steam generator to introduce steam into the furnace. On the one hand, the steam can be used as a catalyst to improve the reactivity of the combustible gas of the coke; on the other hand, the addition of steam causes the reaction in the furnace to proceed in the direction of generating small molecular weight alkanes, thereby improving the quality of the combustible gas, achieving multiple goals at one stroke.

[0020] 5) The setting of the air interlayer is another key part of the present invention. During operation, the air is first preheated through the air interlayer and then introduced into the furnace. Specifically, the air supplied into the furnace is first input from an external air source and then output from the air outlet of the air interlayer. Then the preheated air directly enters the air supply pipe, and the preheated air in the air interlayer is introduced into the furnace through the air supply pipe. The purpose is to improve the combustion efficiency by preheating the air, and the preheated air can also take away the heat of the original outer wall of the furnace body during preheating, so as to achieve the function of protecting the furnace body at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Figure 2 It is a structural schematic diagram of the spiral feeding component;

[0023] Figure 3 It is the structural diagram of the grate.

[0024] The actual correspondence between the reference numerals and component names of the present invention is as follows:

[0025] 10-grate 11-inner spiral section 12-outer spiral section

[0026] 20-furnace body 21-outer jacket 22-air interlayer 23-thermocouple 24-observation window

[0027] 30-air supply pipe 40-ignition pipe 50-pyrolysis gas exhaust pipe

[0028] 60-circulation air pipe 61-flow control valve

[0029] 70-steam discharge pipe 81-desulfurization spray pipe 82-denitrification spray pipe

[0030] 90-screw feeding assembly 91-upper screw feeding section 92-lower screw feeding section

[0031] 93-Sealed storage bin 94-Sealed door

[0032] 100-slag discharge bin 110-slag discharge spiral assembly DETAILED DESCRIPTION

[0033] For ease of understanding, the specific structure and working mode of the present invention are further described below:

[0034] The specific implementation structure of the present invention can refer to Figure 1-3 As shown, the furnace body 20 is provided with an outer jacket 21 outside the furnace body 20 so that an air layer 22 is formed between the two. The furnace body 20 is provided with a spiral feeding assembly 90, a spray assembly, a circulating gas pipe 60, a pyrolysis gas exhaust pipe 50, a grate 10, an air supply pipe 30, an ignition pipe 40, a steam discharge pipe 70, a slag discharge bin 100 and a spiral slag discharge assembly 110 in order from top to bottom. Among them:

[0035] like Figure 1 As shown, the grate 10 is installed at the bottom of the furnace body 20. At the same time, the spiral feed assembly 90 is installed on the upper part of the furnace body 20, and the central axis of the outlet of the spiral feed assembly 90 coincides with the central axis of the furnace body 20. The circulating gas pipe 60 connects the left side of the top and the left side of the bottom of the furnace body 20, and transports the gas in the pyrolysis chamber at the top of the furnace body 20 to the slag chamber at the bottom of the furnace body 20. The pyrolysis gas in the circulating gas pipe 60 can be transported by a high temperature resistant fan and controlled by a flow control valve 61.

[0036] The pyrolysis gas exhaust pipe 50 is installed on the right side of the top of the furnace body 20; the gas supply pipe 30 is symmetrically installed at the bottom of the furnace body 20; the spiral slag removal assembly is installed at the lower part of the furnace body 20, and the slag removal bin 100 is installed at the bottom of the furnace body 20 and connects the furnace body 20 and the spiral slag removal assembly. The central axis of the slag removal bin 100 coincides with the central axis of the furnace body 20. The vertical section of the ignition tube 40 is perpendicular to the ground, and the vertical section is installed at the central axis of the slag removal bin 100. The nozzle height of the ignition tube 40 is slightly lower than the grate 10, ensuring that the width of the flame when it reaches the grate 10 can cover the entire grate 10.

[0037] During the operation of the solid waste pyrolysis equipment, the fuel is accumulated on the grate 10, and the material layer fills between two-thirds and three-quarters of the volume of the entire furnace body 20. The solid waste accumulated in the furnace body 20 can be Figure 1 The structure shown in the figure is continuously pyrolyzed, and a stable material layer partition is quickly formed, that is, a drying layer, a reduction layer, an oxidation layer, and an ash layer are layered from top to bottom. The bottom material layer burns to form ash, and the temperature is kept above 1000℃. The heat generated by the combustion is provided to the upper material layer, and a large amount of oxygen is consumed at the same time, so that the upper material layer is in an oxygen-deficient atmosphere; the temperature of the oxidation layer, the reduction layer, and the drying layer decreases in turn, the lowest temperature at the top of the material layer is about 300℃, and the highest temperature at the bottom is above 1000℃.

[0038] If necessary, refractory materials and heat-insulating materials can be wrapped on the outside of the furnace body 20; when the outer sheath 21 is arranged, the refractory materials and heat-insulating materials should be wrapped on the outer wall of the outer sheath 21. Thermocouples 23 can be arranged in order from top to bottom along the axis of the furnace body 20 at equal intervals, and a number of observation windows 24 can also be arranged at equal intervals. The temperature detected by each thermocouple 23 and the pyrolysis situation in the furnace observed by the observation window 24 are used to adjust the air intake, feed amount, and start and stop of the diesel ignition device, thereby improving the pyrolysis efficiency.

[0039] The screw feed assembly 90 is as follows Figure 2 As shown, it is set to be an upper spiral feeding section 91 and a lower spiral feeding section 92 arranged in series, and connected in the middle by a sealed storage bin 93 with a sealed door 94. The upper spiral feeding section 91 feeds the solid waste particles after granulation into the sealed storage bin 93, at which time the upper sealed door 94 is in an open state, and the lower sealed door 94 is in a closed state. Afterwards, the upper sealed door 94 is closed, and the lower sealed door 94 is opened, and the solid waste in the sealed storage bin 93 is stably transported into the furnace body 20 through the lower spiral feeding section 92 in a sealed state. The volume of the sealed storage bin 93 can at least store the amount of fuel consumed by the present invention in one hour of operation. The lower ash is discharged from the furnace body 20 from the gap of the grate 10 under the action of gravity. In actual design, the speed at which the fuel is dropped into the furnace body 20 from the top of the furnace body 20 by the spiral feeding assembly 90 is the same as the speed at which the ash is discharged from the furnace body 20 through the gaps in the grate 10, so as to ensure that a stable material layer partition, namely a drying layer, a reducing layer, an oxidizing layer, and an ash layer are formed during the operation of the equipment, while the material layer height in the furnace body 20 remains unchanged.

[0040] Furthermore, when the present invention is working, the circulating gas pipe 60 will continuously extract pyrolysis gas from the top of the furnace body 20 and send it to the bottom of the furnace body 20. The exhaust port of the circulating gas pipe 60 is arranged on the left side of the top of the furnace in parallel with the central axis of the furnace body 20, and the outlet of the circulating gas pipe 60 is parallel to the gas supply pipe 30 and is arranged together at the bottom of the furnace body 20. The circulating gas pipe 60 is made of high-temperature resistant material, which can withstand 800°C, and is wrapped with insulation material on the outside. The combustible gas in the circulating gas pipe 60 is transported by a high-temperature resistant fan, and the flow rate is controlled by a flow control valve 61. The extracted combustible gas will be introduced into the slag cavity to assist in igniting the bottom fuel, while increasing the residence time of the flue gas and reducing the exhaust loss. The high-temperature water vapor contained in the combustible gas can act as a combustion catalyst to promote fuel combustion.

[0041] Two or four air supply pipes 30 are symmetrically arranged at the bottom of the furnace body 20, with a tilted structure that is higher on the side close to the central axis of the furnace body 20 and lower on the side away from the central axis of the furnace body 20. The angle between the air supply pipe 30 and the central axis of the furnace body 20 is 45° to ensure that the intake air is evenly distributed at the bottom of the furnace, thereby making the bottom fuel temperature evenly distributed.

[0042] like Figure 3 As shown, the grate 10 is composed of an inner spiral section 11 and an outer spiral section 12. The outer spiral section 12 is fixed on the furnace wall, and the inner spiral section 11 is connected to the working end of the cam machine. The inner spiral section 11 is driven by the cam machine to reciprocate horizontally. There is always a large gap between the inner spiral section 11 and the outer spiral section 12, so that the solid fuel particles that have formed ash fall into the slag discharge bin 100. Finally, the spiral slag discharge assembly 110 discharges the ash out of the furnace body 20 to achieve continuous slag discharge.

[0043] The ignition tube 40 is arranged along the central axis of the slag discharge bin 100, and adopts a coaxial sleeve structure of an inner sleeve and an outer sleeve. The inner sleeve cavity transports diesel, and a nozzle is used to atomize diesel at the end of the inner sleeve; the annular airway formed by the outer sleeve and the inner sleeve is used to transport air. When the furnace is started or the operating load in the furnace is reduced, the ignition tube 40 can be opened to increase the combustion speed of the fuel and the temperature in the furnace, so that the temperature distribution of the material layer remains in a stable operating state.

[0044] Figure 1 It can be seen that the present invention is also provided with a spray assembly, an air interlayer 22 and a steam discharge pipe 70. Among them: the spray assembly includes a desulfurization spray pipe 81 and a denitration spray pipe 82, and both are obliquely inserted into the slag cavity, the taper angle of the nozzle spraying the solution is 120°, and the two nozzles spray desulfurization and denitration solutions respectively, in order to remove sulfur dioxide and nitrogen oxides in the combustible gas. When the air interlayer 22 is working, the air is first preheated through the air interlayer 22 and then introduced into the furnace. Specifically, the air supplied into the furnace is first input from an external air source and then output from the air outlet of the air interlayer 22. Subsequently, the preheated air directly enters the air supply pipe 30, and the preheated air in the air interlayer 22 is introduced into the furnace through the air supply pipe 30. The purpose is to improve the combustion efficiency by preheating the air, and the preheated air can also take away the heat of the outer wall of the original furnace body 20 during preheating, so as to achieve the function of protecting the furnace body 20 at the same time. The steam discharge pipe 70 is used to connect to an external steam generator, thereby playing the function of introducing steam into the furnace, allowing the steam to act as a catalyst to improve the reactivity of the combustible gas of the coke; in addition, the addition of steam causes the reaction in the furnace to proceed in the direction of generating small molecular weight alkanes, thereby improving the quality of the combustible gas.

[0045] Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0046] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0047] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A solid waste pyrolysis device with low pollutant emission, comprising a furnace body (20) with a grate (10), characterized in that: The grate (10) divides the furnace chamber of the furnace body (20) into a pyrolysis chamber located above the grate (10) and a slag chamber located below the grate (10); solid waste falls from the top of the furnace chamber into the pyrolysis chamber and is discharged from the slag chamber after pyrolysis; the device further comprises a gas supply pipe (30) for supplying gas to the slag chamber, an ignition pipe (40) for igniting the slag chamber, a pyrolysis gas exhaust pipe (50) for exhausting gas from the pyrolysis chamber, and a circulating gas pipe (60) for connecting the slag chamber and the pyrolysis chamber; the gas inlet end of the circulating gas pipe (60) is connected to the pyrolysis chamber, and the gas outlet end of the circulating gas pipe (60) is connected to the slag chamber; a flow control valve (61) for controlling the gas flow in the pipe chamber is arranged on the circulating gas pipe (60); The grate (10) is a reciprocating spiral grate, comprising an inner spiral section (11) and an outer spiral section (12) in the same direction, wherein the outer spiral section (12) is fixed on the furnace body (20), and the inner spiral section (11) is connected to the working end of the cam machine; The inner spiral section (11) is driven by a cam to move horizontally back and forth, and a gap is always formed in a part of the area between the inner spiral section (11) and the outer spiral section (12), so that the solid fuel particles that have formed ash fall into the slag discharge bin (100).

2. The low-pollutant-emission solid waste pyrolysis equipment according to claim 1, characterized in that: An outer sleeve (21) is arranged on the outer wall of the furnace body (20), and an air layer (22) for accommodating air is formed between the outer sleeve (21) and the outer wall of the furnace body (20). The air inlet of the air layer (22) is connected to an external air source, and the air outlet of the air layer (22) is connected to the inlet of the air supply pipe (30).

3. The low-pollutant-emission solid waste pyrolysis equipment according to claim 2, characterized in that: The outer wall of the outer sheath (21) is wrapped with refractory material and thermal insulation material.

4. A solid waste pyrolysis device with low pollutant emissions according to claim 1, 2 or 3, characterized in that: A steam discharge pipe (70) is arranged beside the gas supply pipe (30); one end of the steam discharge pipe (70) is connected to an external steam generator, and the other end is connected to the slag chamber.

5. A solid waste pyrolysis device with low pollutant emission according to claim 1, 2 or 3, characterized in that: The device further comprises a desulfurization spray pipe (81) for spraying a desulfurization solution and a denitrification spray pipe (82) for spraying a denitrification solution, wherein the spray ports of the desulfurization spray pipe (81) and the denitrification spray pipe (82) are both installed at the top of the pyrolysis chamber.

6. A solid waste pyrolysis device with low pollutant emissions according to claim 1, 2 or 3, characterized in that: The device comprises a spiral feeding assembly (90) for feeding materials into a feeding port at the top end of a furnace body (20); the spiral feeding assembly (90) comprises an upper spiral feeding section (91), a lower spiral feeding section (92), and a sealed material storage bin (93) located between the two groups of feeding sections and having a connection and transition function; and an openable and closable sealed door (94) is arranged between the inlet of the sealed material storage bin (93) and the outlet of the upper spiral feeding section (91), and between the outlet of the sealed material storage bin (93) and the inlet of the lower spiral feeding section (92).

7. A solid waste pyrolysis device with low pollutant emissions according to claim 1, 2 or 3, characterized in that: The device comprises a spiral slag discharge assembly (110) connected to a discharge port at the bottom of a furnace body (20); slag flows from a slag cavity into a slag discharge bin (100) below and is finally discharged from the spiral slag discharge assembly (110).

8. A solid waste pyrolysis device with low pollutant emission according to claim 1, 2 or 3, characterized in that: The ignition tube (40) constitutes an ignition outlet tube of a diesel ignition assembly. The axis of the ignition tube (40) is coaxial with the axis of the furnace body (20). The ignition tube (40) comprises an inner sleeve and an outer sleeve which are sleeved together. The inner sleeve is a diesel pipe with an atomizing nozzle arranged at the outlet. An annular air passage is formed between the outer sleeve and the inner sleeve for air flow.

9. A solid waste pyrolysis device with low pollutant emission according to claim 1, 2 or 3, characterized in that: A thermocouple (23) for detecting the temperature in the furnace is arranged on the furnace body (20), and an observation window (24) for observing the condition in the furnace is also provided on the furnace body (20); the thermocouple (23) and the observation window (24) are arranged in sequence from top to bottom along the axis of the furnace body (20), and the installation areas of the thermocouple (23) and the observation window (24) are spaced away from each other.

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