System for deep dehydration and self-recuperation of carbon black tail gas

Abstract

The application relates to a system for deep dehydration and self-heat recovery of carbon black tail gas, which comprises a carbon black tail gas flow path, a GGH heat exchanger, a heating heat exchanger and a deep cooling heat exchanger arranged in the carbon black tail gas flow path, and the GGH heat exchanger has a first channel for flowing high-temperature high-moisture carbon black tail gas and a second channel for flowing low-temperature carbon black tail gas after dehydration. The system for deep dehydration and self-heat recovery of carbon black tail gas designed in the application realizes deep dehydration of high-temperature high-moisture carbon black tail gas and energy cascade utilization by arranging the GGH heat exchanger, the heating heat exchanger and the deep cooling heat exchanger and constructing a specific tail gas serial and self-heat recovery flow path. The system can effectively reduce the moisture content of the tail gas from 35-45% to 12-15%, greatly improving the calorific value of the tail gas and the subsequent incineration efficiency; meanwhile, the high-temperature section waste heat is recovered to the dried tail gas, the medium-temperature section waste heat is recovered for heating, and the low-temperature section condensed water can be recycled, so that the waste heat resources and water resources are maximally utilized.

Description

Technical Field

[0001] This application relates to the field of flue gas waste heat recovery and purification technology, and in particular to a system for deep dehydration and self-heating of carbon black tail gas. Background Technology

[0002] In the carbon black production process, the large amount of carbon black tail gas generated by the pyrolysis furnace is a complex byproduct. On the one hand, this tail gas contains high concentrations of combustible components such as carbon monoxide (CO) and hydrogen (H2), making it valuable for recycling as a low-calorific-value fuel. On the other hand, it also presents a series of technical challenges that urgently need to be addressed, posing a significant challenge to its efficient and stable utilization: First, due to the introduction of process water, the carbon black tail gas has an extremely high water content, typically ranging from 35% to 45% by volume. The large amount of water vapor not only fails to generate heat but also absorbs heat during combustion, effectively lowering the overall calorific value of the tail gas. This results in low combustion efficiency and unstable flames when directly fed into subsequent waste gas boilers for incineration, sometimes requiring the addition of high-calorific-value auxiliary fuels, leading to secondary energy consumption and increased operating costs. Second, the carbon black tail gas temperature is typically above 220℃, with a high dust content, and the flue gas generated after combustion contains sulfur oxides (SOx). When the flue gas temperature drops below the acid dew point, it forms a highly corrosive acidic condensate, which causes severe low-temperature acid corrosion to the downstream boiler tail section, flue, and flue gas purification equipment, greatly shortening the service life of the equipment and increasing maintenance costs and safety risks.

[0003] To address the aforementioned issues, existing technologies typically employ direct cooling, which involves using traditional shell-and-tube heat exchangers and circulating cooling water to directly cool the exhaust gas from approximately 230°C to around 60°C. While this method can remove some moisture, it has significant drawbacks: (1) severe energy waste, as a large amount of heat energy carried by the exhaust gas is carried away by the cooling water and not effectively utilized; (2) prominent equipment corrosion and blockage issues, as the acidic condensate precipitated in the low-temperature section severely corrodes the metal heat exchange tubes, and dust easily adheres to the wet tube walls, forming difficult-to-clean scale, leading to decreased heat exchange efficiency and unstable operation; (3) large investment and floor space requirements, as the equipment is typically bulky to achieve the desired heat exchange effect. Utility Model Content

[0004] To address the aforementioned issues, this application provides a system for deep dehydration and self-regenerating carbon black tail gas, enabling energy cascade utilization.

[0005] To achieve the above objectives, the present application designs a system for deep dehydration and self-reheating of carbon black tail gas, including a carbon black tail gas flow path, and a GGH heat exchanger, a heating heat exchanger and a cryogenic heat exchanger installed in the carbon black tail gas flow path. The GGH heat exchanger has a first channel for flowing high-temperature, high-moisture-content carbon black tail gas and a second channel for flowing low-temperature carbon black tail gas after dehydration. The flow direction of the high-temperature, high-moisture-content carbon black tail gas in the carbon black tail gas flow path is as follows: The material enters the first channel of the GGH heat exchanger for initial cooling. After flowing out of the first channel, it enters the heating heat exchanger for medium-temperature cooling; After flowing out of the heating heat exchanger, it enters the cryogenic heat exchanger for deep cooling to precipitate condensate; After exiting the cryogenic heat exchanger, the resulting low-temperature carbon black tail gas returns to the second channel of the GGH heat exchanger, where it exchanges heat with the high-temperature, high-moisture-content carbon black tail gas in the first channel and is reheated before being discharged.

[0006] Preferably, it further includes a medium pipeline for supplying heat exchange medium to the heating heat exchanger, and a switching valve assembly disposed on the medium pipeline; the switching valve assembly is used to selectively introduce heating hot water or cooling circulating water into the heating heat exchanger according to the operating mode.

[0007] Preferably, it further includes a spraying device, which is installed at the carbon black tail gas inlet of the first channel of the GGH heat exchanger and is used to spray the carbon black tail gas entering the first channel.

[0008] Preferably, it also includes a main tower body that forms the carbon black tail gas flow path; the GGH heat exchanger, the heating heat exchanger and the cryogenic heat exchanger are arranged in a vertical stack from top to bottom in the main tower body.

[0009] Preferably, the heating heat exchanger and / or the cryogenic heat exchanger are configured as a pull-out heat exchange core module; the side wall of the main tower is provided with an opening corresponding to the heat exchange core module, and a quick-opening blind plate for sealing the opening; the heat exchange core module can be horizontally pulled out or inserted into the main tower through the opening.

[0010] Preferably, the bottom of the cryogenic heat exchanger is provided with a condensate collection outlet for collecting and discharging the condensate that precipitates during the deep cooling process.

[0011] Preferably, the GGH heat exchanger is a plate heat exchanger.

[0012] Preferably, the plate heat exchanger is made of 2205 duplex stainless steel.

[0013] Preferably, the heat exchange tubes of the heating heat exchanger and the cryogenic heat exchanger are made of fluoroplastic steel or polymer graphite tubes.

[0014] The system designed in this application for deep dehydration and self-regenerating carbon black tail gas achieves deep dehydration and cascaded energy utilization of high-temperature and high-humidity carbon black tail gas by setting up a GGH heat exchanger, a heating heat exchanger, and a cryogenic heat exchanger, and constructing a specific series and self-regenerating flow path for the tail gas. This system can effectively reduce the moisture content of the tail gas from 35-45% to 12-15%, significantly improving the calorific value and subsequent combustion efficiency. Simultaneously, the waste heat from the high-temperature section is reheated into the dried tail gas, the waste heat from the medium-temperature section is recovered for heating, and the condensate from the low-temperature section is recycled, maximizing the utilization of waste heat and water resources. It also effectively avoids the risk of low-temperature corrosion of equipment present in traditional technologies, ensuring the long-term stable operation of the system. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the planar structure of the system for deep dehydration and self-regenerating carbon black tail gas provided in the embodiments of this application.

[0016] Figure 2 This is a flow chart and heat balance diagram of a carbon black tail gas treatment process in one embodiment of this application.

[0017] The components include: main tower body 10, opening 11, GGH heat exchanger 20, heating heat exchanger 30, medium pipeline 31, switching valve group 32, cryogenic heat exchanger 40, condensate collection outlet 41, and spray device 50. Detailed Implementation

[0018] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0019] like Figure 1 As shown in the figure, the system for deep dehydration and self-regenerating carbon black tail gas described in this embodiment includes a carbon black tail gas flow path, and a GGH heat exchanger 20, a heating heat exchanger 30, and a cryogenic heat exchanger 40 disposed within the carbon black tail gas flow path. In a specific implementation, it also includes a main tower body 10 constituting the carbon black tail gas flow path, which has a compact structure and small footprint; the GGH heat exchanger 20 (i.e., the gas-to-gas heat exchanger), the heating heat exchanger 30, and the cryogenic heat exchanger 40 are arranged vertically from top to bottom within the main tower body 10. This layout facilitates the collection and discharge of condensate using gravity.

[0020] The GGH heat exchanger 20 serves as the core heat exchange unit of the system, and its internal structure is divided into a first channel and a second channel that are isolated from each other but can conduct heat. The first channel is used for the flow of high-temperature, high-moisture-content carbon black tail gas initially entering the system, while the second channel is used for the flow of low-temperature carbon black tail gas after it has undergone deep dehydration treatment by the system.

[0021] The flow direction of the high-temperature, high-moisture-content carbon black tail gas in the carbon black tail gas flow path, i.e., the specific flow direction and treatment process of the carbon black tail gas in the carbon black tail gas flow path, are as follows: The gas enters the first channel of the GGH heat exchanger 20 for initial cooling. Specifically, the high-temperature, high-moisture-content carbon black tail gas with an initial temperature of approximately 220°C enters from the upper inlet of the main tower body 10 and first flows through the first channel of the GGH heat exchanger 20. Here, it exchanges heat with the low-temperature tail gas, which has undergone cryogenic treatment and is flowing upward from the second channel, for example, at 54°C. The high-temperature tail gas transfers some of its heat to the low-temperature tail gas, and its own temperature is initially reduced, for example, to 145°C, creating favorable conditions for subsequent condensation and dehydration.

[0022] After exiting the first channel, the gas enters the heating heat exchanger 30 for medium-temperature cooling. Specifically, the carbon black tail gas, after initial cooling, continues to flow downwards and enters the heating heat exchanger 30. In this embodiment, as... Figure 1 As shown, the system also includes a medium pipeline 31 for supplying heat exchange medium to the heating heat exchanger 30, and a switching valve assembly 32 installed on the medium pipeline 31. The switching valve assembly 32 is used to selectively introduce heating hot water or cooling circulating water into the heating heat exchanger 30 according to the operating mode. During the heating season, the switching valve assembly 32 introduces external heating circulating water into the heating heat exchanger 30, and the medium-temperature heat in the exhaust gas is used to heat the heating water, realizing the resource utilization of waste heat. During the non-heating season, the switching valve assembly 32 introduces ordinary industrial cooling circulating water, which is only used to cool the exhaust gas, thereby ensuring the system's continuous operation capability throughout the year.

[0023] After exiting the heating heat exchanger 30, the exhaust gas enters the cryogenic heat exchanger 40 for deep cooling to condense condensate. Specifically, after leaving the heating heat exchanger 30, the exhaust gas enters the bottommost cryogenic heat exchanger 40, where it exchanges heat with a lower-temperature cooling medium. The exhaust gas is then deeply cooled to below its acid dew point, for example, 54°C, causing most of its water vapor to condense into liquid water. Furthermore, as... Figure 1 As shown, at the bottom of the main tower body 10, that is, below the cryogenic heat exchanger 40, a condensate collection outlet 41 is provided to collect the liquid water formed by condensation and discharge it from the system, thereby realizing the deep dehydration of the exhaust gas and the recovery of water resources.

[0024] After exiting the cryogenic heat exchanger 40, the resulting low-temperature carbon black tail gas returns to the second channel of the GGH heat exchanger 20, where it exchanges heat with the high-temperature, high-moisture-content carbon black tail gas in the first channel and is reheated before being discharged. Specifically, after deep dehydration, the resulting low-temperature, low-humidity carbon black tail gas, for example, at 54°C, is deflected back through a pipe at the bottom of the main tower 10 and enters the second channel of the GGH heat exchanger 20. Here, it absorbs heat from the high-temperature tail gas in the first channel, and its own temperature is raised back to a higher level, for example, 160°C. Then, it is discharged from the upper outlet of the main tower 10 and sent to the subsequent incineration boiler. This self-regenerating process not only effectively utilizes the waste cooling of the dehydrated tail gas but also significantly improves its thermal efficiency for combustion in the furnace, while avoiding corrosion of subsequent equipment and white smoke caused by the low-temperature flue gas.

[0025] In some embodiments, such as Figure 1 As shown, it also includes a spraying device 50, which is installed at the carbon black exhaust gas inlet of the first channel of the GGH heat exchanger 20, and is used to spray the carbon black exhaust gas entering the first channel. In this way, by spraying a small amount of atomized water onto the entering exhaust gas through the spraying device 50, the exhaust gas is pre-washed and conditioned, effectively keeping the heat exchange surface clean.

[0026] In some embodiments, for the convenience of system maintenance and repair, such as Figure 1 As shown, the heating heat exchanger 30 and / or the cryogenic heat exchanger 40 are configured as pull-out heat exchange core modules. Correspondingly, an opening 11 corresponding to the heat exchange core module is provided on the side wall of the main tower 10, along with a quick-opening blind flange for sealing the opening 11. When cleaning, maintenance, or replacement of the heat exchanger is required, simply opening the quick-opening blind flange allows the entire heat exchange core module to be horizontally pulled out or inserted into the main tower 10 through the opening 11, making the operation extremely convenient and significantly reducing downtime for maintenance. In practice, the quick-opening blind flange can be a commercially available product purchased according to the actual specifications of the opening 11 for installation.

[0027] In some embodiments, considering the corrosive characteristics of carbon black exhaust gas at different temperature zones, the GGH heat exchanger 20 in the high-temperature inlet section is preferably a plate heat exchanger, with its plates made of 2205 duplex stainless steel to resist corrosion from high-temperature sulfur-containing flue gas. For the heating heat exchanger 30 and cryogenic heat exchanger 40, which generate large amounts of acidic condensate in the medium and low-temperature zones, the heat exchange tubes in contact with the flue gas are preferably made of non-metallic materials with extremely strong acid corrosion resistance, such as fluoroplastic steel or polymer graphite tubes, to ensure long-term safe and stable operation of the equipment.

[0028] To further illustrate the technical effects achievable by this invention, a specific engineering example will be used as an example below.

[0029] Assume a carbon black company produces carbon black exhaust gas with a flow rate of 190,000 Nm³. 3 The gas has a humidity of 37% and an exhaust gas temperature of 220℃. The system provided in this embodiment of the invention is used to treat the gas; the specific heat balance parameters can be found in the appendix. Figure 2 .

[0030] Reference Figure 2 As shown, the data changes throughout the entire processing flow are as follows: Initial state and initial cooling: Initial state (node ​​3 in the figure - carbon black tail gas) 190000 Nm 3 The high-temperature and high-humidity exhaust gas at 220℃ enters the system and first flows through the first channel of the GGH heat exchanger 20 (4-GGH in the figure). After exchanging heat with the low-temperature and dry exhaust gas from the back end of the system, the exhaust gas temperature drops to 145.0℃ (node ​​13 in the figure).

[0031] Medium-temperature cooling and heating heat recovery: The 145.0℃ exhaust gas then enters the heating heat exchanger 30 (1-dehydrator in the figure). Here, the exhaust gas exchanges heat with heating water at 45.0℃ and a flow rate of 2392t / h (node ​​6-heating water inlet in the figure), further reducing its own temperature to 60.00℃ (node ​​14 in the figure), while simultaneously heating the heating water to 55.00℃ (node ​​7-heating water outlet in the figure), achieving an effective heat recovery of 27.7MW. During this process, the exhaust gas flow rate drops to 149038Nm³ due to the condensation of some water vapor. 3 / h, and 32.92t / h of condensate is produced (node ​​16 in the figure - condensate).

[0032] Deep cooling and dehydration: The 60.00℃ exhaust gas then enters the cryogenic heat exchanger 40 (5-dehydrator in the diagram), where it exchanges heat with the 33.00℃ circulating water (node ​​8-circulating water inlet in the diagram), ultimately reducing the temperature to 54.00℃ (node ​​15 in the diagram). During this stage, the exhaust gas flow rate is further reduced to 140534 Nm³. 3 / h, and 6.833t / h of condensate is released again (node ​​17 in the figure - condensate).

[0033] Self-regenerative heating: At this point, the flow rate is 140534 Nm³ at 54.00℃. 3 The low-temperature dried exhaust gas is then returned to the second channel of GGH heat exchanger 20 (4-GGH in the figure) for reheating. After absorbing the heat from the initial high-temperature exhaust gas, its final outlet temperature is raised to 160.3℃ (node ​​12-dry exhaust gas in the figure), and then it is sent to the subsequent boiler.

[0034] Data analysis from this example shows that the total exhaust gas flow rate increased from the initial 190,000 Nm³. 3 / h decreased to a final 140534 Nm 3 The total dehydration capacity reached approximately 39.75 t / h. Calculations show that the moisture content of the exhaust gas was significantly reduced from the initial 37% to approximately 15%, achieving the goal of deep dehydration and significantly improving the calorific value of the exhaust gas. The system not only uses the heat from the mid-temperature section for heating but also recovers heat from the treated exhaust gas by utilizing the waste heat from the high-temperature section, realizing efficient cascade utilization and internal circulation of energy.

[0035] The system for deep dehydration and self-regenerating carbon black tail gas provided in this application embodiment achieves deep dehydration and cascaded energy utilization of high-temperature and high-humidity carbon black tail gas by setting up a GGH heat exchanger, a heating heat exchanger, and a cryogenic heat exchanger and constructing a specific tail gas serial and self-regenerating flow path. This system can effectively reduce the moisture content of the tail gas from 35-45% to 12-15%, significantly improving the calorific value of the tail gas and subsequent combustion efficiency. Simultaneously, the waste heat from the high-temperature section is reheated into the dried tail gas, the waste heat from the medium-temperature section is recovered for heating, and the condensate from the low-temperature section is recycled, maximizing the utilization of waste heat and water resources and effectively avoiding the risk of low-temperature corrosion of equipment present in traditional technologies, ensuring the long-term stable operation of the system.

[0036] In the description of this application, it should be noted that the terms "vertical", "up", "down", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0037] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A system for deep dehydration and self-regenerating carbon black tail gas, characterized in that, It includes a carbon black tail gas flow path, and a GGH heat exchanger, a heating heat exchanger and a cryogenic heat exchanger installed in the carbon black tail gas flow path. The GGH heat exchanger has a first channel for flowing high-temperature carbon black tail gas with high moisture content and a second channel for flowing low-temperature carbon black tail gas after dehydration. The flow direction of the high-temperature, high-moisture-content carbon black tail gas in the carbon black tail gas flow path is as follows: The material enters the first channel of the GGH heat exchanger for initial cooling. After flowing out of the first channel, it enters the heating heat exchanger for medium-temperature cooling; After flowing out of the heating heat exchanger, it enters the cryogenic heat exchanger for deep cooling to precipitate condensate; After exiting the cryogenic heat exchanger, the resulting low-temperature carbon black tail gas returns to the second channel of the GGH heat exchanger, where it exchanges heat with the high-temperature, high-moisture-content carbon black tail gas in the first channel and is reheated before being discharged.

2. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 1, characterized in that, It also includes a medium pipeline for supplying heat exchange medium to the heating heat exchanger, and a switching valve assembly installed on the medium pipeline; the switching valve assembly is used to selectively introduce heating hot water or cooling circulating water into the heating heat exchanger according to the operating mode.

3. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 1, characterized in that, It also includes a spraying device, which is installed at the carbon black tail gas inlet of the first channel of the GGH heat exchanger and is used to spray the carbon black tail gas entering the first channel.

4. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 1, characterized in that, It also includes the main tower body that forms the carbon black tail gas flow path; the GGH heat exchanger, the heating heat exchanger and the cryogenic heat exchanger are arranged in a vertical stack from top to bottom in the main tower body.

5. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 4, characterized in that, The heating heat exchanger and / or the cryogenic heat exchanger are configured as a pull-out heat exchange core module; the side wall of the main tower is provided with an opening corresponding to the heat exchange core module, and a quick-opening blind plate for sealing the opening; the heat exchange core module can be horizontally pulled out or inserted into the main tower through the opening.

6. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 1, characterized in that, The bottom of the cryogenic heat exchanger is equipped with a condensate collection outlet for collecting and discharging the condensate that precipitates during the deep cooling process.

7. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 1, characterized in that, The GGH heat exchanger is a plate heat exchanger.

8. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 7, characterized in that, The plate heat exchanger is made of 2205 duplex stainless steel.

9. The system for deep dehydration and self-regenerating carbon black tail gas according to claim 1, characterized in that, The heat exchange tubes of the heating heat exchanger and the cryogenic heat exchanger are made of fluoroplastic steel or high-molecular graphite tubes.

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