Heat recovery gasification system
By introducing a waste boiler section and a multi-stage flash evaporation system into the coal gasification system, the problems of sensible heat waste of high-temperature crude synthesis gas and large water system circulation volume are solved, achieving efficient heat recovery and environmental protection and energy saving effects.
Patent Information
- Application Number
- CN202410280379.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-12
- Publication Date
- 2025-09-12
AI Technical Summary
During the coal gasification process, a large amount of sensible heat of the high-temperature raw synthesis gas is wasted. A large amount of quenching water is required in the quenching process, which leads to an increase in the water system circulation volume and the amount of discharged wastewater. The heat recovery efficiency is low and it pollutes the environment.
The combined design of gasifier, waste boiler section, quenching section, synthesis gas scrubber, synthesis gas separation tank, Venturi scrubber and three-stage flash evaporation system is adopted to achieve efficient heat energy recovery through sensible heat recovery and multi-stage flash evaporation, reduce the consumption of quenching water and reduce the circulation volume of the water system.
The effective recovery of sensible heat of high-temperature gas is achieved, and the by-product high-pressure saturated steam is used for power generation or steam supply to the pipeline network, which reduces the consumption of quenching water. The system operation is energy-saving and environmentally friendly, reduces wastewater discharge, and improves energy utilization efficiency.
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Figure CN120624065A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of coal gasification, and in particular relates to a heat recovery gasification system. Background Art
[0002] Currently, the most widely used gasification process in the coal gasification industry is the entrained-flow gasifier. Pulverized coal (coal-water slurry) is partially oxidized at temperatures between 1300 and 1700°C, ensuring complete coal gasification at high temperatures. Current gasifiers typically employ a chilling process, where the feed gas is cooled to 200-300°C using chilled water. This process wastes a significant amount of high-temperature sensible heat. For downstream processes that don't require significant steam, such as methanol synthesis, this simple chilling process suffers from low energy efficiency and high cooling water consumption.
[0003] In particular, the heat recovery method of high-temperature raw synthesis gas is mainly based on the quenching process. Its process technology is simple, easy to operate and highly reliable, and it has always been highly praised. However, with the maturity and development of gasification technology, the single quenching process faces severe tests.
[0004] At present, there are the following technical problems to be solved in the coal gasification process, such as:
[0005] (1) In order to reduce the temperature of high-temperature crude synthesis gas at 1300-1700℃ to 200-300℃, a large amount of quenching water is required for cooling in the quenching process, which leads to an increase in the circulation volume of the water system of the gasification unit and an increase in the amount of discharged wastewater.
[0006] (2) The high-temperature crude synthesis gas at 1300-1700°C is directly quenched by water to 200-300°C, and a large amount of sensible heat of the high-temperature crude synthesis gas is wasted, resulting in low heat recovery efficiency. Summary of the Invention
[0007] In view of the above problems existing in the prior art, the present invention provides a heat recovery gasification system which is safe, reliable, easy to operate, has a high heat recovery rate, and is energy-saving and environmentally friendly.
[0008] To achieve the above objectives, the technical solution adopted in the embodiment of the present invention is:
[0009] A heat recovery gasification system comprises: a gasifier, comprising a gasification section, a waste boiler section and a quenching section arranged in sequence from top to bottom; the outlet of the gasification section is connected to the inlet of the waste boiler section, and the outlet of the waste boiler section is connected to the inlet of the quenching section; the crude synthesis gas generated by the oxidation reaction in the gasification section is recovered through the sensible heat of the waste boiler section and enters the quenching section; a synthesis gas washing tower is connected to the quenching section and supplies quenching water to the quenching section to quench the crude synthesis gas in the quenching section; a synthesis gas separation tank, the inlet of which is connected to the outlet of the quenching section The syngas separator is connected to the syngas washing tower through the venturi scrubber; the crude syngas after gas-liquid separation enters the syngas washing tower through the venturi scrubber and is washed in the syngas washing tower; a three-stage flash evaporation system; the bottom of the syngas separator and the bottom of the syngas washing tower are respectively provided with drainage outlets; and they are respectively connected to the three-stage flash evaporation system through the drainage outlets.
[0010] In some embodiments of the present disclosure, the synthesis gas separation tank is constructed as a gravity gas-liquid separation structure or a cyclone gas-liquid separation structure.
[0011] In some embodiments of the present disclosure, the venturi scrubber is configured for one-stage scrubbing or two-stage scrubbing.
[0012] In some embodiments of the present disclosure, the three-stage flash evaporation system includes: a high-pressure flash tank and a high-pressure flash steam stripping tower connected to each other; the synthesis gas separation tank and the synthesis gas washing tower are respectively connected to the high-pressure flash tank through the drainage outlet; the liquid at the bottom of the high-pressure flash steam stripping tower is pumped into the synthesis gas washing tower; the steam at the top of the high-pressure flash steam stripping tower is cooled by a heat exchanger and then sent to the gas-liquid separation tank for gas-liquid separation.
[0013] In some embodiments of the present disclosure, the three-stage flash evaporation system further includes: a low-pressure flash tank, a low-pressure flash steam stripping tower and a vacuum flash tank; the high-pressure flash tank is connected to the low-pressure flash tank through the drainage outlet at its bottom; the low-pressure flash tank is connected to the vacuum flash tank through the drainage outlet at its bottom; the low-pressure flash tank is connected to the low-pressure flash steam stripping tower through its top; the liquid at the bottom of the low-pressure flash steam stripping tower is pumped into the high-pressure flash steam stripping tower.
[0014] In some embodiments of the present disclosure, the high-pressure flash steam stripping tower and the low-pressure flash steam stripping tower are respectively constructed as plate towers including sieve plates or three-dimensional sieve plates, fixed valves or bubble caps, or packed towers containing packings.
[0015] In some embodiments of the present disclosure, the heat recovery gasification system also includes an ash water treatment system; the ash water treatment system includes an ash water tank and a sedimentation tank connected to each other; black water flows into the sedimentation tank by gravity or is pumped through the vacuum flash tank; the ash water in the upper layer of the sedimentation tank flows into the ash water tank through its top and is pumped into the low-pressure flash steam stripping tower.
[0016] Compared with the prior art, the present invention has the following beneficial effects:
[0017] (1) The waste boiler section provided in the gasifier in the heat recovery gasification system of the embodiment of the present invention can effectively recover the sensible heat of the high-temperature gas and produce high-pressure saturated steam for power generation or to be sent to the pipeline network, thereby achieving energy recovery and utilization.
[0018] (2) As the temperature of the high-temperature crude synthesis gas drops after heat exchange in the waste boiler, the amount of quenching water consumed when entering the quenching section is relatively small, and the circulation volume of the water system also decreases accordingly, reducing the load of the black water flash evaporation system.
[0019] In addition, through the synergistic effect between the gasifier, synthesis gas washing tower, synthesis gas separation tank, Venturi scrubber and three-stage flash evaporation system, efficient heat recovery is achieved, and energy saving and environmental protection are achieved during the operation of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar components in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar components. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the description and claims, serve to illustrate the disclosed embodiments. Where appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive of the embodiments of the present apparatus or method.
[0021] Figure 1 This is a structural schematic diagram of a heat recovery gasification system according to an embodiment of the present invention.
[0022] Description of Reference Numerals
[0023] 1-gasifier; 2-gasification section; 3-waste boiler section; 4-quenching section; 5-syngas separation tank;
[0024] 6-Venturi scrubber; 7-synthesis gas scrubber; 8-high-pressure flash tank;
[0025] 9-high-pressure flash steam stripping tower; 10-low-pressure flash tank; 11-low-pressure flash steam stripping tower;
[0026] 12-Vacuum flash tank; 13-Ash water tank; 14-Sedimentation tank DETAILED DESCRIPTION
[0027] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings, but does not limit the present invention. The following describes the embodiments of the present invention in detail with reference to the accompanying drawings and the accompanying drawings, but does not limit the present invention.
[0028] All terms (including technical or scientific terms) used in this disclosure have the same meaning as those understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined herein.
[0029] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.
[0030] It should be noted that in this embodiment, the reaction devices involved in the heat recovery gasification system, such as the gasifier 1 and the syngas separator 5, typically have a liquid discharge outlet or a slag discharge outlet at the bottom. Therefore, the phrase "communicating with..." through the bottom has the same meaning as "communicating with..." through the liquid discharge outlet or slag discharge outlet at the bottom. Similarly, "communicating with..." through the top can be understood as communicating with..." through the exhaust outlet at the top.
[0031] At present, there are many technical problems to be solved in the coal gasification process. For example, (1) in order to cool the high-temperature crude synthesis gas with a temperature of 1300-1700℃ to 200-300℃, a large amount of quenching water is required for cooling in the quenching process, which increases the circulation volume of the water system of the gasification device and the amount of wastewater discharged, thereby causing huge pollution to the environment. (2) the high-temperature crude synthesis gas with a temperature of 1300-1700℃ is directly quenched by water to 200-300℃, which wastes a lot of sensible heat of the high-temperature crude synthesis gas and has a low heat recovery efficiency. To solve the above technical problems, the present invention provides the following technical solutions.
[0032] A heat recovery gasification system, see Figure 1It comprises: a gasifier 1, including a gasification section 2, a waste boiler section 3 and a quenching section 4 arranged in order from top to bottom; the outlet of the gasification section 2 is connected to the inlet of the waste boiler section 3, and the outlet of the waste boiler section 3 is connected to the inlet of the quenching section 4; the crude synthesis gas generated by the oxidation reaction in the gasification section 2 is recovered through the sensible heat of the waste boiler section 3 and enters the quenching section 4; a synthesis gas washing tower 7 is connected to the quenching section 4 and supplies quenching water to the quenching section 4 to quench the crude synthesis gas in the quenching section 4; a synthesis gas separation tank 5, the inlet of which is connected to the outlet of the quenching section 4; after quenching, The crude syngas and quenching water enter the syngas separator 5 for gas-liquid separation; a venturi scrubber 6 is provided; the syngas separator 5 is connected to the syngas scrubber 7 via the venturi scrubber 6; the crude syngas after gas-liquid separation enters the syngas scrubber 7 via the venturi scrubber 6 and is scrubbed within the syngas scrubber 7; a three-stage flash evaporation system is provided; drain outlets (not shown) are provided at the bottom of the syngas separator 5 and the bottom of the syngas scrubber 7; these drain outlets are connected to the three-stage flash evaporation system. The above design achieves efficient heat recovery, and is both energy-efficient and environmentally friendly throughout the operation of the system.
[0033] In one embodiment, see Figure 1 The outlet of the waste boiler section 3 and the quenching section 4 are respectively provided with a plurality of cooling water nozzles (not shown in the figure) for cooling the synthesis gas; the cooling water nozzles are distributed around the outlet of the waste boiler section 3 and the inner wall of the quenching section 4. In this embodiment, through this arrangement, the raw synthesis gas passing through the outlet of the waste boiler section 3 and entering the quenching section 4 can be quickly and effectively heat exchanged, thereby achieving the purpose of efficiently recovering the sensible heat of the high-temperature gas. In addition, in this embodiment, preferably, the cooling water nozzles are evenly distributed around the outlet of the waste boiler section 3 and the quenching section 4. Since the outlet of the waste boiler section 3 and the quenching section 4 are respectively provided with evenly distributed cooling water nozzles, the effect of cooling and heat exchange of the synthesis gas is more ideal. The cooling water of the cooling water nozzles can be made up of water outside the system, or can be quenched water pumped back to the system by a water pump.
[0034] In one embodiment, see Figure 1 The shell of the quenching section 4 is configured as an inner and outer sleeve structure, and a gap is provided between the inner and outer sleeves to allow cooling water to flow in. The inner and outer sleeve structure effectively improves the heating condition of the shell and reduces the damage to the shell caused by the high-temperature crude synthesis gas. In particular, the high-temperature crude synthesis gas contains coal powder, oxygen and water vapor, and runs rapidly in a high-temperature and high-pressure environment. If it runs for a long time, the high-temperature crude synthesis gas will collide with the inner wall of the shell, causing the inner wall to be damaged to varying degrees. In this embodiment, after applying the inner and outer sleeve structure, since cooling water is passed into the gap, the temperature of the shell is at least maintained at a relatively low state, which relatively reduces and improves the degree of damage to the shell in the collision with the coal powder, thereby increasing the service life of the gasifier 1 and reducing the frequency of maintenance.
[0035] In one embodiment, see Figure 1 The gasification section 2 and the waste boiler section 3 are both equipped with water-cooled walls (not shown) and water-cooled shields (not shown) from the inside to the outside. The water-cooled walls are constructed as tubes or coils, and the water-cooled shields are constructed as tubes. In this embodiment, the installation of these water-cooled walls and shields effectively reduces direct heat exposure in the gasification section 2 and the waste boiler section 3, extending their service life and reducing maintenance cycles.
[0036] In one embodiment, see Figure 1 The syngas separator 5 is constructed as either a gravity gas-liquid separation structure or a cyclonic gas-liquid separation structure. In the gravity separation structure, after the crude syngas enters the sidewall of the syngas separator 5, its flow rate decreases within the tank, causing the liquid to flow downward and be discharged from the bottom of the tank, while the gas rises and is discharged from the top, thus achieving separation. Alternatively, a cyclonic gas-liquid separation structure is used. The crude syngas enters the channel tangentially to the shell of the syngas separator 5, swirling along the inner wall, ejecting the liquid and discharging the gas from the top.
[0037] In one embodiment, see Figure 1 , the venturi scrubber 6 is set to one-stage washing or two-stage washing. In this embodiment, different levels of washing can be set according to the washing requirements for high-temperature raw synthesis gas. Among them, the one-stage venturi washing is to add water to the synthesis gas in the venturi scrubber 6, and the water flows at a high speed inside the venturi tube, mixes with the synthesis gas for washing, and then enters the washing tower for gas-liquid separation. The two-stage venturi washing is to add another venturi scrubber 6 on the basis of the first-stage venturi scrubber 6; during the washing process, after the synthesis gas enters the first-stage venturi scrubber 6 for washing, it enters a subsequent gas-liquid separation tank for gas-liquid separation, and then enters the second-stage venturi scrubber 6 for mixed washing, and then enters the washing tower for gas-liquid separation. In this embodiment, one or two stages specifically refers to washing once or twice.
[0038] In one embodiment, see Figure 1The three-stage flash evaporation system includes: a high-pressure flash tank 8 and a high-pressure flash stripper 9, both interconnected. A syngas separator 5 and a syngas scrubber 7 are each connected to the high-pressure flash tank 8 via a liquid outlet. Liquid at the bottom of the high-pressure flash stripper 9 is pumped into the syngas scrubber 7. Steam at the top of the high-pressure flash stripper 9 is cooled in a heat exchanger and then fed into the gas-liquid separator for gas-liquid separation. In this embodiment, the syngas scrubber 7 can be a plate tower containing sieve plates, three-dimensional sieve plates, fixed valves, bubble caps, or other trays, or a packed tower containing packing. The outlet of the syngas scrubber 7 may also include other scrubbing and separation processes to further enhance the scrubbing effect, such as a filter process or a gas-liquid direct contact mixing process for scrubbing and gas-liquid separation. Furthermore, in this embodiment, the high-pressure flash tank 8 and the high-pressure flash stripper 9 can be separate devices or combined into a single device. This can be adjusted based on the specific needs of the application scenario and is not limited here. In the combined equipment, flash evaporation can be carried out in the lower part, and the steam rises from the inside of the equipment into the upper part to achieve heat exchange by contact with water.
[0039] In one embodiment, see Figure 1 The three-stage flash system also includes: a low-pressure flash tank 10, a low-pressure flash steam stripping tower 11 and a vacuum flash tank 12; the high-pressure flash tank 8 is connected to the low-pressure flash tank 10 through the drainage outlet at its bottom; the low-pressure flash tank 10 is connected to the vacuum flash tank 12 through the drainage outlet at its bottom; the low-pressure flash tank 10 is connected to the low-pressure flash steam stripping tower 11 through its top; the liquid at the bottom of the low-pressure flash steam stripping tower 11 is pumped into the high-pressure flash steam stripping tower 9.
[0040] In this embodiment, the three-stage flash evaporation system fully utilizes flash evaporation and gas-liquid separation. For example, black water is depressurized and enters the high-pressure flash tank 8 for flash evaporation and gas-liquid separation. Steam from the top of the high-pressure flash tank 8 undergoes direct contact heat exchange with water from the bottom of the low-pressure flash steam stripping tower 11 in the high-pressure flash steam stripping tower 9. The black water at the bottom of the high-pressure flash tank 8 is depressurized again and enters the low-pressure flash tank 10 for flash evaporation and gas-liquid separation. In other words, different stages of flash evaporation and gas-liquid separation can achieve the desired separation requirements.
[0041] In one embodiment, see Figure 1 The high-pressure flash steam stripping tower 9 and the low-pressure flash steam stripping tower 11 are each constructed as a plate tower including sieve plates or three-dimensional sieve plates, fixed valves or bubble caps, or a packed tower containing packing. In this embodiment, different structures of the high-pressure flash steam stripping tower 9 and the low-pressure flash steam stripping tower 11 can be selected according to the specific design process.
[0042] In one embodiment, see Figure 1The heat recovery gasification system also includes an ash water treatment system; the ash water treatment system includes an ash water tank 13 and a settling tank 14, which are interconnected. Black water flows into the settling tank 14 via a vacuum flash tank 12 by gravity or by pump. The ash water in the upper layer of the settling tank 14 flows into the ash water tank 13 through the top of the settling tank 14 and is pumped into the low-pressure flash steam stripping tower 11. In this embodiment, for example, steam from the top of the low-pressure flash tank 10 and water from the ash water tank 13 undergo direct contact heat exchange in the low-pressure flash steam stripping tower 11. The black water at the bottom of the low-pressure flash tank 10 is again depressurized and enters the vacuum flash tank 12, where it undergoes pressure reduction flash evaporation and gas-liquid separation. The steam at the top of the vacuum flash tank 12 is cooled and subjected to gas-liquid separation before being pumped out by a vacuum pump. The black water at the bottom enters the settling tank 14 for solid-liquid sedimentation separation. The gray water at the top of the sedimentation tank 14 flows into the gray water tank 13 at a slightly lower position, and is pumped into the low-pressure flash steam stripping tower 11 for recycling. The concentrated black water at the bottom of the sedimentation tank 14 is further discharged after solid-liquid separation.
[0043] Furthermore, although illustrative embodiments are described herein, the scope includes any and all embodiments having equivalent elements, modifications, omissions, combinations (e.g., combinations of schemes across various embodiments), adjustments, or variations based on the present disclosure. The elements of the claims are to be interpreted broadly based on the language used in the claims and are not limited to the examples described in this specification or during the continuation of this application. Furthermore, the steps of the disclosed methods may be modified in any manner, including by reordering steps or inserting or deleting steps. Therefore, it is intended that the description be considered as examples only, with the true scope being indicated by the following claims and their full scope of equivalents.
[0044] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more aspects thereof) can be used in combination with each other. After reading the above description, for example, those of ordinary skill in the art can use other embodiments. Moreover, in the above detailed description, various features can be combined together to simplify the present disclosure. This should not be interpreted as intending that the disclosed features that are not requested for protection are essential to any claim. Therefore, the following claims are incorporated into the specific embodiments as examples or embodiments, wherein each claim itself is a separate embodiment, and it is expected that these embodiments can be combined with each other in various combinations or permutations. The scope of the present invention should be determined with reference to the appended claims and the full range of equivalents given by these claims.
Claims
1. A heat recovery gasification system, characterized in that: It includes: The gasifier comprises a gasification section, a waste boiler section, and a quenching section, which are sequentially arranged from top to bottom; the outlet of the gasification section is connected to the inlet of the waste boiler section, and the outlet of the waste boiler section is connected to the inlet of the quenching section; the crude synthesis gas generated by the oxidation reaction in the gasification section is recovered through the sensible heat of the waste boiler section and enters the quenching section; a syngas scrubber connected to the quenching section and delivering quenching water to the quenching section to quench the raw syngas in the quenching section; A syngas separation tank, the inlet of which is connected to the outlet of the quenching section; the quenched raw syngas and quenching water enter the syngas separation tank and undergo gas-liquid separation; Venturi scrubber; the syngas separation tank is connected to the syngas scrubber through the venturi scrubber; the crude syngas after gas-liquid separation enters the syngas scrubber through the venturi scrubber and is scrubbed in the syngas scrubber; Three-stage flash system; The bottom of the synthesis gas separation tank and the bottom of the synthesis gas washing tower are respectively provided with drainage outlets; and are respectively communicated with the three-stage flash evaporation system through the drainage outlets.
2. The heat recovery gasification system according to claim 1, characterized in that: The synthesis gas separation tank is constructed as a gravity gas-liquid separation structure or a cyclone gas-liquid separation structure.
3. The heat recovery gasification system according to claim 1, characterized in that: The venturi scrubber is configured to perform one-stage scrubbing or two-stage scrubbing.
4. The heat recovery gasification system according to claim 1, characterized in that: The three-stage flash evaporation system comprises: a high-pressure flash tank and a high-pressure flash steam stripping tower connected to each other; The synthesis gas separation tank and the synthesis gas washing tower are respectively connected to the high-pressure flash tank through the drainage outlet; The liquid at the bottom of the high-pressure flash steam stripping tower is pumped into the synthesis gas washing tower; The steam at the top of the high-pressure flash steam stripping tower is cooled by a heat exchanger and then sent to the gas-liquid separation tank for gas-liquid separation.
5. The heat recovery gasification system according to claim 4, characterized in that: The three-stage flash evaporation system further comprises: a low-pressure flash tank, a low-pressure flash steam stripping tower and a vacuum flash tank; The high-pressure flash tank is connected to the low-pressure flash tank through a drainage outlet at the bottom of the high-pressure flash tank; The low-pressure flash tank is connected to the vacuum flash tank through a liquid discharge outlet at the bottom thereof; The low-pressure flash tank is connected to the low-pressure flash steam stripping tower through the top of the low-pressure flash tank; The liquid at the bottom of the low-pressure flash steam stripping tower is pumped into the high-pressure flash steam stripping tower.
6. The heat recovery gasification system according to claim 5, characterized in that: The high-pressure flash steam stripping tower and the low-pressure flash steam stripping tower are respectively constructed as plate towers including sieve plates or three-dimensional sieve plates, fixed valves or bubble caps, or packed towers containing packings.
7. The heat recovery gasification system according to claim 5, characterized in that: It also includes an ash water treatment system; the ash water treatment system includes an ash water tank and a sedimentation tank connected to each other; The black water flows into the settling tank by gravity or is pumped through the vacuum flash tank; The grey water in the upper layer of the sedimentation tank flows into the grey water tank through the top thereof and is pumped into the low-pressure flash steam stripping tower.