Coal gasification plant and process with bottom ash recycling
By designing a coal gasification unit that reuses bottom ash, a carbon dioxide blower is used to blow airflow to transport the gasified bottom ash back to the gasifier, solving the problem of recycling coal gasification bottom ash, improving the efficiency of coal gasification reaction and the utilization rate of solid waste resources, and reducing environmental pollution and the use of fresh additives.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XINJIANG YIHUA CHEM CO LTD
- Filing Date
- 2023-09-19
- Publication Date
- 2026-06-12
AI Technical Summary
Traditional methods of treating coal gasification bottom ash lead to resource waste and environmental pollution, and the issue of recycling it back to the gasifier has not yet been effectively resolved.
A coal gasification device for bottom ash recycling was designed, including a gasifier, a screw conveyor mechanism, and a backflushing section. A carbon dioxide blower is used to blow airflow to transport the gasified bottom ash back to the gasifier for re-reaction. The design of the screw conveyor mechanism and ash box ensures the recycling of the gasified bottom ash.
It enables the recycling of coal gasification bottom ash, improves the yield of coal gasification reaction, reduces environmental pollution and resource waste, reduces the amount of fresh additives used, and improves the effective utilization of solid waste resources.
Smart Images
Figure CN117229815B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal gasification technology, and in particular to a coal gasification device and process for bottom ash recycling. Background Technology
[0002] The traditional way to deal with coal gasification bottom ash is to send it to thermal power plants for co-firing or to bury it directly, which not only wastes resources and pollutes the environment, but also occupies a lot of land.
[0003] The bottom ash from coal gasification mainly consists of ash from coal and contains various metal and non-metal oxides. Mixing the bottom ash with raw coal can promote the coal gasification reaction and improve the effective utilization of solid waste resources.
[0004] However, how to recycle the coal gasification bottom ash back into the gasifier requires further research. Summary of the Invention
[0005] In view of this, embodiments of the present invention provide a coal gasification device and process for bottom ash recycling, the main purpose of which is to recycle the bottom ash of coal gasification back to the gasifier.
[0006] To achieve the above objectives, the present invention mainly provides the following technical solutions:
[0007] On one hand, one embodiment of the present invention provides a coal gasification device for bottom ash recycling, the device comprising: a gasifier, a screw conveyor mechanism, and a backflushing section;
[0008] The gasifier is equipped with a feeding mechanism;
[0009] The inlet end of the screw conveyor is connected to the slag discharge port of the gasifier;
[0010] The backflushing unit includes a carbon dioxide blower, a slag bin, a first slag box, and a second slag box. The inlet of the slag bin is connected to the outlet of the screw conveyor mechanism. The lower end of the slag bin is connected to the first slag box through a slag discharge pipe. The upper end of the first slag box is connected to the second slag box through an exhaust pipe. The carbon dioxide blower is connected to the lower end of the second slag box. The upper end of the second slag box is connected to the feeding mechanism through a diversion pipe.
[0011] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.
[0012] Optionally, the backflushing section further includes a distribution plate disposed inside the second slag box to divide the second slag box into an upper space and a lower space. The distribution plate is evenly distributed with multiple air vents, and the exhaust pipe is connected to the side wall of the upper space.
[0013] Optionally, the distribution plate is inclined, with the upper end of the inclined surface of the distribution plate close to the exhaust pipe.
[0014] Optionally, the outlet end of the screw conveyor is higher than the inlet end of the screw conveyor.
[0015] Optionally, it also includes a balancing pipe, one end of which is connected to the upper end of the second slag box and the other end of which is connected to the upper end of the slag bin.
[0016] Optionally, the feeding mechanism includes a mixing bin and an auger conveyor, the lower end of the mixing bin is connected to the inlet of the auger conveyor, the outlet of the auger conveyor is connected to the feed inlet of the gasifier, and the guide pipe is connected to the upper end of the mixing bin.
[0017] Optionally, the tilt angle of the distribution plate is 5°.
[0018] Optionally, it also includes a cyclone separator, the tangential inlet and the lower discharge port of which are respectively connected to the gasifier.
[0019] On the other hand, another embodiment of the present invention provides a coal gasification process for bottom ash recycling, comprising the following steps:
[0020] (1) Additives and coal gasification bottom ash are added to raw coal to form a mixture;
[0021] (2) The mixture is transported to the gasifier for coal gasification reaction.
[0022] Optionally, in step (1), the additive is one of kaolin, coal gangue, bentonite or quartz sand.
[0023] By employing the above technical solution, the present invention has at least the following advantages:
[0024] The bottom ash discharged from the ash discharge port of the gasifier enters the screw conveyor and is transported to the ash bin. The bottom ash in the ash bin enters the first ash box through the ash discharge pipe. The gasified bottom ash in the first ash box rises through the exhaust pipe and enters the second ash box. In the second ash box, the carbon dioxide gas flow blown into the second ash box by the carbon dioxide blower mixes with the gasified bottom ash and carries the gasified bottom ash along the guide pipe to the feeding mechanism. After the metal and non-metal oxides in the gasified bottom ash are mixed with the coal, they re-enter the gasifier for another coal gasification reaction.
[0025] Through the above process, the bottom ash from coal gasification is recycled, the yield of coal gasification reaction is increased, and the effective utilization of solid waste resources is improved. Attached Figure Description
[0026] Figure 1 A diagram of a coal gasification device for bottom ash recycling provided in an embodiment of the present invention;
[0027] Figure 2 for Figure 1 Enlarged view of section A;
[0028] Figure 3 for Figure 2 Enlarged view of section B.
[0029] The reference numerals in the accompanying drawings include: gasifier 1, screw conveyor 2, carbon dioxide blower 3, slag bin 4, first slag box 5, second slag box 6, slag discharge pipe 7, exhaust pipe 8, diversion pipe 9, distribution plate 10, vent hole 11, balance pipe 13, mixing bin 14, screw conveyor 15, cyclone separator 16, crusher 17, and discharge valve 18. Detailed Implementation
[0030] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.
[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0032] like Figure 1 As shown, in one aspect, an embodiment of the present invention provides a coal gasification device for bottom ash recycling, which includes:
[0033] Gasifier 1, screw conveyor 2, and backflushing section;
[0034] Gasifier 1 is equipped with a feeding mechanism;
[0035] The inlet end of the screw conveyor 2 is connected to the slag discharge port of the gasifier 1;
[0036] The backflushing unit includes a carbon dioxide blower 3, a slag bin 4, a first slag box 5, and a second slag box 6. The inlet of the slag bin 4 is connected to the outlet end of the screw conveyor 2. The lower end of the slag bin 4 is connected to the first slag box 5 through a slag discharge pipe 7. The upper end of the first slag box 5 is connected to the second slag box 6 through an exhaust pipe 8. The carbon dioxide blower 3 is connected to the lower end of the second slag box 6. The upper end of the second slag box 6 is connected to the feeding mechanism through a diversion pipe 9.
[0037] The working process of a coal gasification unit that reuses bottom ash is as follows:
[0038] The bottom ash discharged from the ash discharge port of gasifier 1 enters the screw conveyor mechanism 2 and is transported to the ash bin 4. The bottom ash in the ash bin 4 enters the first ash box 5 through the ash discharge pipe 7. The gasified bottom ash in the ash box rises into the second ash box 6 through the exhaust pipe 8. In the second ash box 6, the carbon dioxide airflow blown into the second ash box 6 by the carbon dioxide blower 3 mixes with the gasified bottom ash and carries the gasified bottom ash along the guide pipe 9 to the feeding mechanism. After the metal and non-metal oxides in the gasified bottom ash are mixed with the coal, they re-enter the gasifier 1 for another coal gasification reaction.
[0039] In the technical solution of this invention, the above process realizes the recycling of coal gasification bottom ash, improves the yield of coal gasification reaction, and enhances the effective utilization of solid waste resources.
[0040] Specifically, the advantages of this device are further explained as follows:
[0041] First, this device recycles the bottom ash from coal gasification, achieving efficient utilization of solid waste resources and reducing environmental pollution.
[0042] Secondly, this device uses carbon dioxide as the medium for pneumatic conveying of bottom ash, and carbon dioxide participates in the gasification reaction as a gasifying agent, realizing the efficient utilization of syngas energy and reducing the cost of conveying bottom ash.
[0043] Third, the bottom ash contains coal gasification additives such as kaolin. Reusing the kaolin and other coal gasification additives in the bottom ash significantly reduces the amount of fresh additives that need to be added.
[0044] Fourth, the screw conveyor mechanism used in this device has an outlet end higher than the inlet end, which keeps the inlet end of the bottom ash feeder fully sealed and prevents carbon dioxide from backflowing along the screw conveyor mechanism.
[0045] like Figure 1 , Figure 2 and Figure 3 As shown, in a specific embodiment, the backflushing section also includes a distribution plate 10, which is disposed inside the second slag box 6 to divide the second slag box 6 into an upper space and a lower space. The distribution plate 10 is evenly distributed with a plurality of vent holes 11, and the exhaust pipe 8 is connected to the side wall of the upper space.
[0046] In this embodiment, specifically, the carbon dioxide blower 3 blows carbon dioxide into the second slag box 6, which rises from the bottom and passes through multiple vent holes 11, improving the uniformity of the carbon dioxide airflow after passing through the distribution plate 10. The exhaust pipe 8 is connected to the side wall of the upper space. In the upper space, the uniformly dispersed carbon dioxide airflow and the gasification bottom slag are fully mixed. The mixed airflow reaches the feeding mechanism along the guide pipe 9, which can increase the probability of the gasification bottom slag flowing back to the feeding mechanism.
[0047] like Figures 1 to 3 As shown, in a specific embodiment, the distribution plate 10 is inclined, and the upper end of the inclined surface of the distribution plate 10 is close to the exhaust pipe 8.
[0048] Specifically, after the gasification bottom ash enters the second ash box 6 along the exhaust pipe 8, it inevitably carries solid ash particles into the second ash box 6. If the distribution plate 10 is set horizontally, the solid ash particles will most likely settle into the distribution plate 10 area next to the exhaust pipe 8, which is not conducive to the automatic dispersion of solid ash particles.
[0049] In this embodiment, the settled solid ash particles roll down along the inclined surface of the distribution plate 10, which improves the dispersion of ash particles on the distribution plate 10 and avoids the deposition of solid ash particles. At the same time, the carbon dioxide gas flow continuously passes through multiple air holes 11, lifting the solid ash particles on the distribution plate 10, thereby reducing the probability of solid ash particles being left in the second slag box 6.
[0050] like Figure 1 As shown, in a specific embodiment, the outlet end of the screw conveyor 2 is higher than the inlet end of the screw conveyor 2.
[0051] In this embodiment, (a roller crusher 17 is installed in the connecting pipe between the gasifier 1 and the screw conveyor 2, which can control the bottom ash particle size to 0 to 10 mm. When the bottom ash particles enter the first ash box 5, they are in a gasified suspension state, which makes it easy for the gasified bottom ash to carry as many particles as possible to rise to the second ash box 6). The screw conveyor 2 is set at an inclination, and the outlet end of the screw conveyor 2 is higher than the inlet end of the screw conveyor 2. The bottom ash entering the screw conveyor 2 from the ash discharge port of the gasifier 1 first fills the inlet end of the screw conveyor 2, so that the front half of the shell space of the screw conveyor 2 is kept in a fully sealed state. The bottom ash in the shell is conveyed to the ash bin 4 by the screw blades. In this way, the screw conveyor 2 isolates the gas phase space of the gasifier 1 and the ash bin 4, and prevents the gasified bottom ash or carbon dioxide gas flow from flowing back to the gasifier 1 along the shell space of the screw conveyor 2.
[0052] like Figure 1 As shown, in a specific embodiment, a balance pipe 13 is also included, one end of which is connected to the upper end of the second slag box 6, and the other end is connected to the upper end of the slag bin 4.
[0053] In this embodiment, specifically, with the spiral conveyor mechanism 2 in a gas-phase isolated state, the second slag box 6, the first slag box 5, and the slag bin 4 are interconnected and the air pressure tends to be balanced through the setting of the balance pipe 13, the slag discharge pipe 7, and the exhaust pipe 8. The bottom slag in the slag bin 4 sinks downward due to its own gravity.
[0054] Moreover, the gas phase space formed by the second slag box 6, the first slag box 5, and the slag bin 4 has only one pressure relief channel, the diversion pipe 9, to ensure that the gasified bottom slag can reach the feeding mechanism with the carbon dioxide gas flow.
[0055] Specifically, the lower end of the first slag box 5 is connected to one end of the discharge pipe, and the other end of the discharge pipe is connected to the discharge valve 18. For larger bottom slag particles that cannot rise in the first slag box 5, the operator can periodically open the discharge valve 18 to remove the bottom slag particles and put them into the raw coal as an additive for the coal gasification reaction.
[0056] like Figure 1 As shown, in a specific embodiment, the feeding mechanism includes a mixing bin 14 and an auger conveyor 15. The lower end of the mixing bin 14 is connected to the inlet of the auger conveyor 15, the outlet of the auger conveyor 15 is connected to the feed inlet of the gasifier 1, and the guide pipe 9 is connected to the upper end of the mixing bin 14.
[0057] In this embodiment, specifically, in actual operation, the mixing bin 14 serves as a mixing bin for raw coal and recycled bottom ash. The mixed gas flow of carbon dioxide and gasification bottom ash is mixed into the raw coal, and the auger conveyor 15 transports the raw coal to the gasifier 1 for gasification reaction, ensuring the airtightness of the internal space of the gasifier 1, and also ensuring the smooth recycling of bottom ash.
[0058] In a specific embodiment, the tilt angle of the distribution plate 10 is 5°.
[0059] Specifically, when the tilt angle of the distribution plate 10 is greater than 5°, the solid ash particles slide down the distribution plate 10 at a faster speed, and the carbon dioxide gas flow is not easy to capture and lift the solid ash particles. The solid ash particles are easy to deposit at the lower end of the tilted surface of the distribution plate 10.
[0060] In this embodiment, the distribution plate 10 with an inclination angle of 5° ensures that the solid ash particles have a certain rolling speed and are dispersed on the distribution plate 10, while also preventing them from rolling too fast, so that the carbon dioxide airflow can successfully capture and lift the solid ash particles.
[0061] like Figure 1 As shown, in a specific embodiment, a cyclone separator 16 is also included, with the tangential inlet and lower discharge port of the cyclone separator 16 respectively connected to the gasifier 1.
[0062] In this embodiment, specifically, the upper end of the gasifier 1 is connected to the tangential inlet of the cyclone separator 16, and the lower end of the gasifier 1 is connected to the lower discharge port of the cyclone separator 16. The crude syngas generated by the gasification reaction in the gasifier 1 enters the cyclone separator 16, where solid particles are separated. The syngas without particles is sent to the next stage, while the solid particles are returned to the gasifier 1 to continue the reaction.
[0063] On the other hand, another embodiment of the present invention provides a coal gasification process for bottom ash recycling, comprising the following steps:
[0064] (1) Additives and coal gasification bottom ash are added to raw coal to form a mixture. The additive is one of kaolin, coal gangue, bentonite or quartz sand. The additive can act as a condensation nucleus to reduce coal gas coking.
[0065] (2) The mixture is transported to the gasifier for coal gasification reaction.
[0066] Here are two examples from production practice:
[0067] Example 1
[0068] Raw coal is fed into gasifier 1 at a rate of 200 kg / h via the feeding mechanism to undergo gasification, generating crude syngas and bottom ash. The bottom ash production is approximately 30 kg / h. The bottom ash is discharged from the ash discharge port of gasifier 1 into screw conveyor 2, where its temperature is cooled from approximately 1000℃ to 800℃. It then sequentially enters ash bin 4 and the first ash box 5. Simultaneously, carbon dioxide is pressurized to 0.1-0.5 MPa by carbon dioxide blower 3 and transported into the second ash box 6. Approximately 20 kg / h of bottom ash is carried by the carbon dioxide gas flow to the feeding mechanism, where it mixes with the raw coal and enters gasifier 1 for further reaction.
[0069] Example 2
[0070] Raw coal is fed into gasifier 1 at a rate of 240 kg / h via the feeding mechanism to undergo gasification, generating crude syngas and bottom ash. The bottom ash production is approximately 40 kg / h. The bottom ash is discharged from the ash discharge port of gasifier 1 into screw conveyor 2, where its temperature is cooled from approximately 1000℃ to 800℃. It then sequentially enters ash bin 4 and the first ash box 5. Simultaneously, carbon dioxide is pressurized to 0.1-0.5 MPa by carbon dioxide blower 3 and conveyed into the second ash box 6. Approximately 25 kg / h of bottom ash is carried by the carbon dioxide gas flow to the feeding mechanism, where it mixes with the raw coal and enters gasifier 1 for further reaction.
[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A coal gasification device for bottom ash recycling, characterized in that, include: Gasifier, wherein the gasifier is equipped with a feeding mechanism; A screw conveyor mechanism, the inlet end of which is connected to the slag discharge port of the gasifier; The backflushing section includes a carbon dioxide blower, a slag bin, a first slag box, and a second slag box. The inlet of the slag bin is connected to the outlet end of the screw conveyor mechanism. The lower end of the slag bin is connected to the first slag box through a slag discharge pipe. The upper end of the first slag box is connected to the second slag box through an exhaust pipe. The carbon dioxide blower is connected to the lower end of the second slag box. The upper end of the second slag box is connected to the feeding mechanism through a diversion pipe. The backflushing section also includes a distribution plate, which is disposed inside the second slag box to divide the second slag box into an upper space and a lower space. The distribution plate is evenly distributed with multiple air vents, and the exhaust pipe is connected to the side wall of the upper space. The distribution plate is inclined, and the upper end of the inclined surface of the distribution plate is close to the exhaust pipe; The outlet end of the screw conveyor is higher than the inlet end of the screw conveyor. It also includes a balancing pipe, one end of which is connected to the upper end of the second slag box and the other end of which is connected to the upper end of the slag bin.
2. The coal gasification unit for bottom ash recycling according to claim 1, characterized in that, The feeding mechanism includes a mixing bin and an auger conveyor. The lower end of the mixing bin is connected to the inlet of the auger conveyor, the outlet of the auger conveyor is connected to the feed inlet of the gasifier, and the guide pipe is connected to the upper end of the mixing bin.
3. The coal gasification unit for bottom ash recycling according to claim 1, characterized in that, The tilt angle of the distribution plate is 5°.
4. The coal gasification unit for bottom ash recycling according to claim 1, characterized in that, It also includes a cyclone separator, the tangential inlet and the lower discharge port of which are respectively connected to the gasifier.
5. A coal gasification process for bottom ash recycling, characterized in that, The coal gasification unit for bottom ash recycling as described in claim 1 includes the following steps: (1) Additives and coal gasification bottom ash are added to the raw coal to form a mixture; (2) The mixture is transported to the gasifier for coal gasification reaction.
6. The coal gasification process for bottom ash recycling according to claim 5, characterized in that, In step (1), the additive is one of kaolin, coal gangue, bentonite or quartz sand.