Gasification device and method for removing scale before starting up

Abstract

This invention relates to the field of gasification equipment technology, specifically to a gasification equipment and its pre-start descaling method. The equipment includes a gasifier; a syngas scrubbing tower for scrubbing the syngas from the gasifier and conveying the resulting ash water back to the gasifier as quench water; and a black water flash evaporation system for flash evaporating the black water generated from the gasifier's quenching process and returning the flash-evaporated water to the syngas scrubbing tower as scrubbing water. Using this equipment, by using the ash water from the syngas scrubbing tower as quench water for the gasifier, and flash evaporating the black water from the gasifier and then reusing it in the syngas scrubbing tower, not only can the water from the gasifier and syngas scrubbing tower be recycled, saving water consumption, but it can also effectively prevent scaling on the equipment and its pipelines.

Description

Technical Field

[0001] This invention relates to the field of gasification equipment technology, specifically to a gasification equipment and a method for descaling before startup. Background Technology

[0002] Fluidized bed gasification technology is the mainstream development direction in the current coal gasification field. Among them, dry coal powder pressurized gasification technology has been widely used in industry due to its advantages such as wide adaptability to coal types, low specific oxygen consumption and specific coal consumption, high content of effective gas (CO+H2) components, high carbon conversion rate, high cold gas efficiency, environmental friendliness and long operating cycle.

[0003] In a typical dry pulverized coal pressurized gasification process, raw coal from the coal storage and transportation system is ground, sorted, and dried in a preparation unit to obtain qualified pulverized coal, which is then transported to the gasification unit. The pulverized coal is injected into the gasifier's reaction chamber via pipeline through the main burner, where it undergoes a complex incomplete combustion reaction under high temperature and pressure, generating syngas rich in hydrogen and carbon monoxide (commonly known as "effective gas"). The high-temperature syngas and liquid molten slag enter the quench chamber through a downcomer, where they are cooled by quench water spray. The liquid slag solidifies in a water bath at the bottom of the quench chamber. The crude syngas, after preliminary washing and cooling, is further purged by a Venturi scrubber and then sent to a syngas scrubbing tower for fine washing. The quench water is discharged from the bottom of the gasifier. However, during the gasification process, in addition to generating syngas rich in hydrogen and carbon monoxide, gases such as CO2 and NH3 are also produced. CO2 reacts with quench water to form HCO3-. 3- HCO 3- It will decompose into CO3 at high temperatures. 2- With Ca in chilled water 2+ Mg 2+ Plasma produces CaCO3 and MgCO3, which precipitate out and easily cause scaling on equipment and pipelines. In addition, NH3 reacts with quench water to generate ammonia nitrogen, which neutralizes acidic substances such as HCl and HCN in the quench water, leading to an increase in the alkalinity of the water and thus exacerbating scaling.

[0004] Currently, in the water circulation process of coal-to-oil gasification units, the quench black water is mainly clarified in a clarification tank, and flocculants and dispersants are added separately through a dosing device to settle suspended particles in the suspension to avoid scaling. However, this method can only slow down the scaling process, but cannot fundamentally and effectively prevent scaling.

[0005] Therefore, there is an urgent need for a gasification device and a method for descaling before startup to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to address the problem that in the existing technology of water circulation process in coal-to-oil gasification units, the quench black water is mainly clarified in a clarification tank, and flocculants and dispersants are added separately by a dosing device to settle suspended particles in the suspension to avoid scaling. However, this method can only slow down the scaling process and cannot fundamentally and effectively prevent scaling. The invention provides a gasification unit and a method for descaling before start-up.

[0007] To achieve the above objectives, a first aspect of the present invention provides a gasification apparatus, the gasification apparatus comprising: Gasification furnace; A syngas scrubbing tower is used to scrub the syngas from the gasifier and to transport the ash water generated from the scrubbing to the gasifier as quench water for the gasifier. The black water flash evaporation system is used to flash-dry the black water generated from the gasifier quenching, and to return the flash-dryed recycled water to the syngas scrubbing tower as the scrubbing water for the syngas scrubbing tower.

[0008] Preferably, the black water flash evaporation system includes: A medium-pressure flash evaporator is used to perform medium-pressure flash evaporation treatment on the black water generated from the quenching of the gasifier. A low-pressure flash evaporator is used to perform low-pressure flash evaporation treatment on black water that has been flashed in the medium-pressure flash evaporator. A vacuum flash evaporator is used to perform vacuum flash evaporation on black water that has been flashed in the low-pressure flash evaporator. A clarification tank is used to precipitate and clarify the black water from the flash evaporation process in the vacuum flash tank. The circulating water tank returns a portion of the overflow water from the clarification tank to the syngas scrubbing tower as scrubbing water for the middle trays of the syngas scrubbing tower, and discharges the remaining portion.

[0009] Preferably, the flash pressure of the medium-pressure flash tank is 0.5~0.55MPa, the flash pressure of the low-pressure flash tank is 0.2~0.3MPa, and the flash pressure of the vacuum flash tank is -0.1~-0.05MPa, wherein the pressure difference between the flash pressure of the medium-pressure flash tank and the flash pressure of the low-pressure flash tank is 0.25~0.35MPa.

[0010] Preferably, the circulating water tank also contains demineralized water and / or a dispersant.

[0011] Preferably, the black water flash evaporation system further includes: A humidification tower is used to condense the gas phase from the medium-pressure flash tank. A medium-pressure flash cooler is used to cool the gas phase from the humidification tower. The first gas-liquid separator is used to perform gas-liquid separation treatment on the gas phase from the medium-pressure flash cooler, and to transport the separated gas phase to the downstream processing device and the liquid to the circulating water tank. A low-pressure flash condenser is used to condense the gas phase from the low-pressure flash tank. A low-pressure flash condenser is used to cool the gas phase from the low-pressure flash condenser. The second gas-liquid separator is used to perform gas-liquid separation on the gas phase from the low-pressure flash cooler, and to transport the separated gas phase to the downstream processing device and the liquid phase to the circulating water tank. A vacuum flash cooler is used to cool the gas phase from the vacuum flash tank. The third gas-liquid separator is used to perform gas-liquid separation treatment on the gas phase from the vacuum flash cooler, and discharge the separated gas phase and transport the liquid phase to the circulating water tank.

[0012] Preferably, the recycled water from the circulating water tank is preheated sequentially by the low-pressure flash condenser and the humidification tower and then returned to the syngas scrubbing tower as scrubbing water for the middle trays of the syngas scrubbing tower.

[0013] Preferably, the gasification device further includes a quench water pH monitoring device for monitoring the pH value of the quench water and controlling the pH value of the quench water at 6-8 by increasing the external drainage of the circulating water tank and / or adding acid-base regulators.

[0014] Preferably, the gasification device further includes: A Venturi scrubber is used to pre-wash the syngas from the gasifier. The fourth gas-liquid separator is used to perform gas-liquid separation on the syngas after pre-washing by the Venturi scrubber, and to transport the separated gas phase to the syngas scrubbing tower for washing, while the liquid phase is used as quench water for the gasifier.

[0015] Preferably, the gasification device further includes a filter for filtering the quench water entering the gasifier; A steam supply device, the steam supply end of which is connected to the filter at the front end of the gasifier and / or the syngas scrubbing tower; The demineralized water supply device is connected to the syngas scrubbing tower at its demineralized water supply end.

[0016] A second aspect of the present invention provides a method for descaling a gasification device before startup, applicable to the aforementioned gasification device, the method comprising the following steps: S1. Steam is introduced into the filter at the front end of the syngas scrubbing tower and / or gasifier to establish a circulation preheating, and the steam is stopped after 50-70 minutes of preheating. S2. Demineralized water is introduced into the syngas scrubbing tower to establish a water circulation, and the demineralized water is stopped after 100-120 minutes. In a preferred embodiment, the demineralized water flow rate is adjusted to change every 10-15 minutes between 50% and 100% during the water circulation process. S3. Open the drain port of the filter to discharge the loose scale; S4. If it is confirmed that no scale is discharged from the drain port of the filter, the descaling is complete and the device is started. If scale continues to be discharged from the drain port of the filter, repeat steps S1-S3 until it is confirmed that no scale is discharged from the drain port of the filter.

[0017] Compared with the prior art, the beneficial effects of this invention are as follows: by using the ash water from the syngas scrubbing tower as the quench water for the gasifier, and the black water generated by the gasifier quenching is flash-evaporated and then reused for washing in the syngas scrubbing tower, in practical applications, not only can the water of the gasifier and the syngas scrubbing tower be recycled, saving water consumption, but also the scaling of the equipment and its pipelines can be effectively avoided. Attached Figure Description

[0018] Figure 1 This is a process diagram of the gasification apparatus of the present invention; Figure 2 This is a process diagram of the black water flash evaporation system of the gasification device of the present invention.

[0019] Explanation of reference numerals in the attached figures 1. Gasifier; 2. Venturi scrubber; 3. Fourth gas-liquid separator; 4. Syngas scrubbing tower; 5. Filter; 61. Medium-pressure flash tank; 62. Humidification tower; 63. Medium-pressure flash cooler; 64. First gas-liquid separator; 65. Low-pressure flash tank; 66. Low-pressure flash condenser; 67. Low-pressure flash cooler; 68. Second gas-liquid separator; 691. Vacuum flash tank; 692. Vacuum flash cooler; 693. Third gas-liquid separator; 694. Clarifying tank; 695. Vacuum filter; 696. Circulating water tank. Detailed Implementation

[0020] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the present invention.

[0021] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of indicated technical features. Therefore, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean a non-exclusive inclusion, the possibility of the presence or addition of one or more other features, units, components, and / or combinations thereof.

[0022] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0023] The first aspect of the present invention provides a gasification apparatus, such as... Figures 1-2 As shown, the gasification device includes: Gasifier 1; Syngas scrubbing tower 4 is used to scrub the syngas from the gasifier 1 and to transport the ash water generated from the scrubbing to the gasifier 1 as quench water for the gasifier 1. The black water flash evaporation system is used to flash evaporate the black water generated from the quenching of the gasifier 1, and to return the flash-treated recycled water to the syngas scrubbing tower 4 as the scrubbing water of the syngas scrubbing tower 4.

[0024] According to the above technical solution, based on the gasification device, the ash water from the syngas scrubbing tower is used as the quench water for the gasifier. The black water generated by the quenching of the gasifier is flash-evaporated and then reused for washing in the syngas scrubbing tower. In practical applications, not only can the water of the gasifier and the syngas scrubbing tower be recycled, saving water consumption, but also scale formation on the equipment and its pipelines can be effectively prevented.

[0025] In some preferred embodiments, such as Figure 2 As shown, the black water flash evaporation system includes: Medium-pressure flash evaporator 61 is used to perform medium-pressure flash evaporation treatment on the black water generated from the quenching of the gasifier 1. The low-pressure flash tank 65 is used to perform low-pressure flash treatment on the black water after it has been flashed by the medium-pressure flash tank 61. Vacuum flash evaporator 691 is used to perform vacuum flash evaporation treatment on black water that has been flashed by the low-pressure flash evaporator 65. Clarification tank 694 is used to precipitate and clarify the black water after flash evaporation treatment from the vacuum flash tank 691. The circulating water tank 696 returns a portion of the overflow water from the clarifier 694 to the syngas scrubber 4 as scrubbing water for the middle trays of the syngas scrubber 4, and discharges the remaining portion.

[0026] In this embodiment of the invention, by sequentially subjecting the black water generated from the gasifier to medium-pressure, low-pressure, and vacuum flash evaporation, gases such as CO2 and NH3 in the black water can be effectively removed, thereby effectively preventing scale buildup on the equipment and pipelines during the recycling process.

[0027] The reason for discharging a portion of the water from the circulating water tank 696 is that water quality deteriorates after repeated recycling. By discharging a portion, the corresponding amount of clean cleaning water is replenished by the syngas scrubbing tower. Figure 1 The top of the tower, as shown, effectively ensures water quality stability, preventing scaling and reduced syngas cleaning effectiveness due to water quality deterioration. By returning water to the middle tray of the syngas scrubbing tower 4, the consumption of clean cleaning water is reduced while effectively ensuring the syngas scrubbing effect.

[0028] To accelerate the clarification process, flocculant is added to the clarification tank 694, causing most of the solid particles to settle out. The clarified water overflows into the circulating water tank, while the concentrated mud water in the clarification tank is pumped out by the mud pump and sent to the vacuum filter 695 for filtration. The resulting filter cake is loaded onto a truck and sent out, and the filtrate is then sent back to the clarification tank.

[0029] More preferably, the flash pressure P1 of the medium-pressure flash tank 61 is 0.5~0.55MPa, the flash pressure P2 of the low-pressure flash tank 65 is 0.2~0.3MPa, and the flash pressure of the vacuum flash tank 691 is -0.1~-0.05MPa, controlling the black water temperature at 65-75℃. The pressure difference between the flash pressure of the medium-pressure flash tank 61 and the flash pressure of the low-pressure flash tank 65 is 0.25~0.35MPa.

[0030] In this embodiment of the invention, by coordinating the pressures of medium-pressure flash evaporation, low-pressure flash evaporation, and vacuum flash evaporation, the removal efficiency of gases such as CO2 and NH3 in black water can be maximized in practical applications, thereby effectively preventing scaling of the equipment and its pipelines. It should be noted that the coordinated design of the above parameters has a significant impact on the removal efficiency of acidic gases; deviations from the above parameter ranges will affect the final removal efficiency of acidic gases.

[0031] Specifically, taking a gasifier with a full load of 90t / h as an example, when the gasifier's operating load is ≤70t / h, P1-P2 is at its highest of 0.35MPa; when the gasifier's load is at full load of 90t / h, P1-P2 is at its lowest of 0.2MPa; and when the gasifier's operating load is 70-90t / h, P1-P2 corresponds linearly to 0.2-0.35MPa, in order to ensure the removal effect of gases such as CO2 and NH3 in black water.

[0032] In some other preferred embodiments, the circulating water tank 696 is further filled with demineralized water and / or a dispersant, thereby further effectively preventing scale buildup in the equipment and pipelines caused by the water by adding demineralized water and / or a dispersant to the circulating flash black water.

[0033] In some specific embodiments, the black water flash evaporation system further includes: Humidification tower 62 is used to condense the gas phase from the medium-pressure flash tank 61; The medium-pressure flash cooler 63 is used to cool the gas phase from the humidification tower 62, specifically to 68-72°C. The first gas-liquid separator 64 is used to perform gas-liquid separation treatment on the gas phase from the medium-pressure flash cooler 63, and to transport the separated gas phase to the downstream processing device and the liquid to the circulating water tank 696. A low-pressure flash condenser 66 is used to condense the gas phase from the low-pressure flash tank 65. The low-pressure flash condenser 67 is used to cool the gas phase from the low-pressure flash condenser 66, specifically to 68-72°C. The second gas-liquid separator 68 is used to perform gas-liquid separation treatment on the gas phase from the low-pressure flash cooler 67, and to transport the separated gas phase to the downstream processing device and the liquid phase to the circulating water tank 696. Vacuum flash cooler 692 is used to cool the gas phase from the vacuum flash tank 691; The third gas-liquid separator 693 is used to perform gas-liquid separation processing on the gas phase from the vacuum flash cooler 692, and discharge the separated gas phase and transport the liquid phase to the circulating water tank 696.

[0034] In this embodiment of the invention, by using the above-mentioned process equipment to treat the acidic gas produced by medium-pressure flash evaporation and low-pressure flash evaporation, not only can the acidic gas be effectively removed, but also the heat energy, liquid water and part of the acidic gas can be recovered and utilized. Specifically, for example, the downstream treatment device is a sulfur recovery device.

[0035] More preferably, the recycled water from the circulating water tank 696 is preheated sequentially by the low-pressure flash condenser 66 and the humidification tower 62 and then returned to the syngas scrubbing tower 4 as the scrubbing water for the middle tray of the syngas scrubbing tower 4. This allows for the efficient utilization of thermal energy while condensing and cooling the acidic gas flashed out at medium pressure, and enables the recycled scrubbing water to reach the scrubbing temperature.

[0036] In some other preferred embodiments, the gasification device further includes a quench water pH monitoring device for monitoring the pH value of the quench water and controlling the pH value of the quench water at 6-8 by increasing the outflow of the circulating water tank 696 and / or adding an acid-base regulator.

[0037] In this embodiment of the invention, the pH value of the quench water is monitored, and the pH value is controlled between 6 and 8 by increasing the external drainage volume and adding acid-base adjusters. In practical applications, this effectively avoids high concentrations of scale-forming ions in the water, which can lead to scaling. Furthermore, it has been found in practical applications that high alkalinity in the water easily leads to precipitation and scaling. Therefore, this invention primarily uses the addition of acids, such as sulfuric acid, to reduce the alkalinity of the water. However, excessive addition should be avoided to prevent corrosion of equipment and pipelines. Preferably, the pH value of the quench water is controlled between 6 and 8, or the total hardness + total alkalinity of the quench water is ≤800 mg / L.

[0038] In some other preferred embodiments, the gasification apparatus further includes: Venturi scrubber 2 is used to pre-wash the syngas from the gasifier 1; The fourth gas-liquid separator 3 is used to perform gas-liquid separation on the syngas after pre-washing treatment by the Venturi scrubber 2, and to transport the separated gas phase to the syngas scrubbing tower 4 for washing, while the liquid phase is used as quench water for the gasifier 1.

[0039] In this embodiment of the invention, by setting up a Venturi scrubber 2 and a fourth gas-liquid separator 3 to pre-wash the syngas, especially by performing gas-liquid separation after pre-washing, the liquid content of the syngas entering the syngas scrubbing tower can be effectively avoided, which would prevent the demister from completely removing the liquid and result in the syngas entering the downstream conversion unit after being treated by the demister still having a high liquid content, thus affecting the catalyst activity in the conversion unit.

[0040] In some other preferred embodiments, the gasification apparatus further includes: Filter 5 is used to filter the quench water entering the gasifier 1; A steam supply device, the steam supply end of which is connected to the filter 5 at the front end of the gasifier 1 and / or the syngas scrubbing tower 4; The demineralized water supply device is connected to the syngas scrubbing tower 4 at its demineralized water supply end.

[0041] In this embodiment of the invention, by designing the filter 5, steam supply device, and demineralized water supply device to work synergistically, abnormal operating conditions such as scale flakes falling off and clogging equipment pipelines during startup after unplanned shutdowns of the gasifier can be effectively avoided, thus improving the startup success rate. Specifically, when the steam supply end of the steam supply device is connected to the filter 5 at the front end of the gasifier 1 and the syngas scrubbing tower 4, steam consumption can be reduced while effectively establishing circulating preheating. Furthermore, the steam is low-pressure steam, and the demineralized water is low-temperature demineralized water, thereby further effectively achieving descaling before startup based on the temperature difference.

[0042] In other preferred embodiments, when the ash content of the pulverized coal is 13-16% and the gasifier load (pulverized coal flow rate into the gasifier) ​​is ≤70t / h, the wastewater discharge flow rate from the circulating water tank 696 is at least 40t / h, and for every 5t / h increase in load, the wastewater discharge flow rate increases by 6-10t / h to ensure no ion concentration in the system. When the gasifier load remains constant, and the ash content of the pulverized coal is higher than 16%, for every 1% increase in ash content, the wastewater discharge flow rate increases by 8-10t / h to ensure no ion concentration in the circulating water.

[0043] A second aspect of the present invention provides a method for descaling a gasification device before startup, applicable to the aforementioned gasification device, the method comprising the following steps: S1. Steam is introduced into the filter 5 at the front end of the syngas scrubbing tower 4 and / or gasifier 1 to establish a circulation preheating, and the steam is stopped after preheating for 50-70 minutes. S2. Introduce demineralized water into the syngas scrubbing tower 4 to establish a water circulation, and stop introducing demineralized water after 100-120 minutes. During the water circulation process, adjust the demineralized water flow rate to be between 50% and 100% and change it every 10-15 minutes. S3. Open the drain port of filter 5 to discharge the detached scale; S4. If it is confirmed that no scale is discharged from the drain port of filter 5, the descaling is completed and the device is started. If scale continues to be discharged from the drain port of filter 5, repeat steps S1-S3 until it is confirmed that no scale is discharged from the drain port of filter 5.

[0044] According to the above technical solution, by descaling the equipment and pipelines before the gasifier is started, especially before the gasifier is restarted after an abnormal shutdown, the abnormal situation of scale flakes falling off and blocking the equipment and pipelines during the restart process after an unplanned shutdown of the gasifier can be effectively avoided, thereby improving the start-up success rate.

[0045] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0046] Example 1 Adopting such Figures 1-2 The illustrated gasification apparatus specifically includes: Gasifier 1; Syngas scrubbing tower 4 is used to scrub the syngas from the gasifier 1 and to transport the ash water generated from the scrubbing to the gasifier 1 as quench water for the gasifier 1. The black water flash evaporation system is used to flash evaporate the black water generated from the quenching of the gasifier 1, and to return the flash-treated recycled water to the syngas scrubbing tower 4 as the scrubbing water of the syngas scrubbing tower 4. The black water flash evaporation system includes: Medium-pressure flash evaporator 61 is used to perform medium-pressure flash evaporation treatment on the black water generated from the quenching of the gasifier 1. The low-pressure flash tank 65 is used to perform low-pressure flash treatment on the black water after it has been flashed by the medium-pressure flash tank 61. Vacuum flash evaporator 691 is used to perform vacuum flash evaporation treatment on black water that has been flashed by the low-pressure flash evaporator 65. Clarification tank 694 is used to precipitate and clarify the black water after flash evaporation treatment from the vacuum flash tank 691. The circulating water tank 696 returns a portion of the overflow water from the clarification tank 694 to the syngas scrubbing tower 4 as scrubbing water for the middle tray of the syngas scrubbing tower 4, and discharges the remaining portion. The flash pressure of the medium-pressure flash tank 61 is 0.5~0.55MPa, the flash pressure of the low-pressure flash tank 65 is 0.2~0.3MPa, and the flash pressure of the vacuum flash tank 691 is -0.1~-0.05MPa. The pressure difference between the flash pressure of the medium-pressure flash tank 61 and the flash pressure of the low-pressure flash tank 65 is 0.25~0.35MPa. Specifically, when the ash content of the pulverized coal is 15% and the gasifier operating load is 65t / h, the flash pressure of the medium-pressure flash tank 61 is 0.55MPa, the flash pressure of the low-pressure flash tank 65 is 0.2MPa, the flash pressure of the vacuum flash tank 691 is -0.07MPa, and the external drainage of the circulating water tank 696 is not less than 40t / h. The circulating water tank 696 also contains demineralized water and dispersant; The black water flash evaporation system also includes: Humidification tower 62 is used to condense the gas phase from the medium-pressure flash tank 61; The medium-pressure flash cooler 63 is used to cool the gas phase from the humidification tower 62, specifically to 70°C. The first gas-liquid separator 64 is used to perform gas-liquid separation treatment on the gas phase from the medium-pressure flash cooler 63, and to transport the separated gas phase to the downstream processing device and the liquid to the circulating water tank 696. A low-pressure flash condenser 66 is used to condense the gas phase from the low-pressure flash tank 65. The low-pressure flash condenser 67 is used to cool the gas phase from the low-pressure flash condenser 66, specifically to 70°C. The second gas-liquid separator 68 is used to perform gas-liquid separation treatment on the gas phase from the low-pressure flash cooler 67, and to transport the separated gas phase to the downstream processing device and the liquid phase to the circulating water tank 696. Vacuum flash cooler 692 is used to cool the gas phase from the vacuum flash tank 691; The third gas-liquid separator 693 is used to perform gas-liquid separation on the gas phase from the vacuum flash cooler 692, and discharge the separated gas phase and transport the liquid phase to the circulating water tank 696. The recycled water from the circulating water tank 696 is preheated sequentially by the low-pressure flash condenser 66 and the humidification tower 62 and then sent back to the syngas scrubbing tower 4 as the scrubbing water for the middle tray of the syngas scrubbing tower 4. The gasification device also includes a quench water pH monitoring device, which is used to monitor the pH value of the quench water and control the pH value of the quench water at 6-8 by increasing the external drainage of the circulating water tank 696 and adding acid-base regulators. The gasification device further includes: Venturi scrubber 2 is used to pre-wash the syngas from the gasifier 1; The fourth gas-liquid separator 3 is used to perform gas-liquid separation on the syngas after pre-washing treatment by the Venturi scrubber 2, and to transport the separated gas phase to the syngas scrubbing tower 4 for washing, while the liquid phase is used as quench water for the gasifier 1.

[0047] In practical applications, clean water is first used to establish a water circulation system for the gasifier and syngas scrubbing tower. Then, a black water flash evaporation system is gradually introduced to replace the clean water, thus establishing a water circulation system for the gasifier and syngas scrubbing tower.

[0048] Testing revealed that the gasification device described in this invention, compared to existing technologies, not only enables the recycling of water in the gasifier and syngas scrubbing tower, saving water consumption, but also effectively prevents scaling on the device and its pipelines. Specifically, compared to existing technologies, the stable operation scaling cycle is increased by more than 50%.

[0049] Example 2 Referring to Embodiment 1, the difference is that the gasification device further includes: Filter 5 is used to filter the quench water entering the gasifier 1; A steam supply device, the steam supply end of which is connected to the filter 5 at the front end of the gasifier 1 and the syngas scrubbing tower 4; The demineralized water supply device is connected to the syngas scrubbing tower 4 at its demineralized water supply end.

[0050] In practical applications, S1, steam is introduced into the filter 5 at the front end of the syngas scrubbing tower 4 and the gasifier 1 to establish a cycle preheating, and the steam is stopped after 60 minutes of preheating. S2. Introduce demineralized water at room temperature into the syngas scrubbing tower 4 to establish a water circulation, and stop introducing demineralized water after 110 minutes. During the water circulation process, adjust the demineralized water flow rate between 50% and 100% and change it every 12 minutes. S3. Open the drain port of filter 5 to discharge the detached scale; S4. If it is confirmed that no scale is discharged from the drain port of filter 5, the descaling is completed and the device is started. If scale continues to be discharged from the drain port of filter 5, repeat steps S1-S3 until it is confirmed that no scale is discharged from the drain port of filter 5.

[0051] Testing revealed that, compared to the scheme in Example 1, the gasification device described in this invention, by performing descaling treatment on the equipment pipelines before restarting the gasifier after an abnormal shutdown, can effectively prevent abnormal conditions such as scale flakes falling off and clogging the equipment pipelines during the restart process after an unplanned shutdown of the gasifier, thereby improving the restart success rate.

[0052] The gasification device and its pre-start descaling method provided by this invention use the ash water from the syngas scrubbing tower as the quench water for the gasifier. The black water generated by the gasifier's quenching is flash-evaporated and then reused for washing in the syngas scrubbing tower. In practical applications, this not only achieves the recycling of water from the gasifier and the syngas scrubbing tower, saving water consumption, but also effectively prevents scale buildup on the device and its pipelines. Furthermore, by performing descaling treatment on the device and its pipelines before the gasifier is restarted after an abnormal shutdown, abnormal conditions such as scale flakes falling off and clogging the equipment and pipelines during restart after an unplanned shutdown of the gasifier can be effectively avoided, thus improving the start-up success rate.

[0053] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention. To avoid unnecessary repetition, the present invention will not describe all possible combinations separately. However, these simple modifications and combinations should also be considered as part of the content disclosed in this invention and are all within the protection scope of this invention.

Claims

1. A gasification device, characterized in that, The gasification device includes: Gasification furnace (1); Syngas scrubbing tower (4) is used to scrub the syngas from the gasifier (1) and to transport the ash water generated from the scrubbing to the gasifier (1) as quench water for the gasifier (1); The black water flash evaporation system is used to flash evaporate the black water generated from the quenching of the gasifier (1) and return the flash-treated recycled water to the syngas scrubbing tower (4) as the scrubbing water of the syngas scrubbing tower (4).

2. The gasification apparatus according to claim 1, characterized in that, The black water flash evaporation system includes: Medium-pressure flash evaporator (61) is used to perform medium-pressure flash evaporation on black water generated from the quenching of the gasifier (1); Low-pressure flash tank (65) is used to perform low-pressure flash treatment on black water that has been flashed by the medium-pressure flash tank (61); Vacuum flash evaporator (691) is used to perform vacuum flash evaporation treatment on black water that has been flashed by the low-pressure flash evaporator (65); Clarification tank (694) is used to precipitate and clarify the black water after flash evaporation from the vacuum flash tank (691); The circulating water tank (696) returns a portion of the overflow water from the clarifier (694) to the syngas scrubbing tower (4) as scrubbing water for the middle tray of the syngas scrubbing tower (4), and discharges the remaining portion.

3. The gasification apparatus according to claim 2, characterized in that, The flash pressure of the medium-pressure flash tank (61) is 0.5~0.55MPa, the flash pressure of the low-pressure flash tank (65) is 0.2~0.3MPa, and the flash pressure of the vacuum flash tank (691) is -0.1~-0.05MPa. The pressure difference between the flash pressure of the medium-pressure flash tank (61) and the flash pressure of the low-pressure flash tank (65) is 0.25~0.35MPa.

4. The gasification apparatus according to claim 2, characterized in that, The circulating water tank (696) also contains demineralized water and / or a dispersant.

5. The gasification apparatus according to any one of claims 2-4, characterized in that, The black water flash evaporation system also includes: A humidification tower (62) is used to condense the gas phase from the medium-pressure flash tank (61); A medium-pressure flash cooler (63) is used to cool the gas phase from the humidification tower (62); The first gas-liquid separator (64) is used to perform gas-liquid separation treatment on the gas phase from the medium-pressure flash cooler (63) and transport the separated gas phase to the downstream processing device, and the liquid to the circulating water tank (696). A low-pressure flash condenser (66) is used to condense the gas phase from the low-pressure flash tank (65); A low-pressure flash condenser (67) is used to cool the gas phase from the low-pressure flash condenser (66); The second gas-liquid separator (68) is used to perform gas-liquid separation on the gas phase from the low-pressure flash cooler (67) and transport the separated gas phase to the downstream processing device, and the liquid phase to the circulating water tank (696). A vacuum flash cooler (692) is used to cool the gas phase from the vacuum flash tank (691); The third gas-liquid separator (693) is used to perform gas-liquid separation processing on the gas phase from the vacuum flash cooler (692), and discharge the separated gas phase and transport the liquid phase to the circulating water tank (696).

6. The gasification apparatus according to claim 5, characterized in that, The recycled water from the circulating water tank (696) is preheated sequentially by the low-pressure flash condenser (66) and the humidification tower (62) and then returned to the syngas scrubbing tower (4) as the scrubbing water for the middle tray of the syngas scrubbing tower (4).

7. The gasification apparatus according to claim 2, characterized in that, The gasification device also includes a quench water pH monitoring device for monitoring the pH value of the quench water and controlling the pH value of the quench water at 6-8 by increasing the external drainage of the circulating water tank (696) and / or adding acid-base regulators.

8. The gasification apparatus according to claim 1, characterized in that, The gasification device further includes: Venturi scrubber (2) is used to pre-wash the syngas from the gasifier (1); The fourth gas-liquid separator (3) is used to perform gas-liquid separation on the syngas after pre-washing treatment by the Venturi scrubber (2), and to transport the separated gas phase to the syngas scrubbing tower (4) for washing, while the liquid phase is used as quench water for the gasifier (1).

9. The gasification apparatus according to claim 1, characterized in that, Also includes: A filter (5) is used to filter the quench water entering the gasifier (1); A steam supply device, the steam supply end of which is connected to the filter (5) at the front end of the gasifier (1) and / or the syngas scrubbing tower (4); The demineralized water supply device is connected to the syngas scrubbing tower (4) at its demineralized water supply end.

10. A method for descaling a gasification device before startup, characterized in that, The descaling method for the gasification device described in any one of claims 1-9 includes the following steps before startup: S1. Steam is introduced into the filter (5) at the front end of the syngas scrubbing tower (4) and / or gasifier (1) to establish a cycle preheating, and the steam is stopped after 50-70 minutes of preheating; S2. Demineralized water is introduced into the syngas scrubbing tower (4) to establish water circulation, and the demineralized water is stopped after 100-120 minutes. During the water circulation process, the demineralized water flow rate is adjusted to change every 10-15 minutes between 50% and 100%. S3. Open the drain port of filter (5) to discharge the detached scale; S4. If it is confirmed that no scale is discharged from the drain port of filter (5), the descaling is completed and the device is started. If scale continues to be discharged from the drain port of filter (5), repeat steps S1-S3 until it is confirmed that no scale is discharged from the drain port of filter (5).

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