Coke oven gas low-temperature coalescence purification process and method
By employing a low-temperature coalescence purification process for coke oven gas, utilizing gas-liquid separation and condensation cooling technologies, the problems of equipment blockage, safety hazards, and incomplete resource recovery in coke oven gas purification have been solved, achieving efficient, safe, and environmentally friendly gas purification and resource recovery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAANXI HUAXIANG ENERGY TECH GRP CO LTD
- Filing Date
- 2026-03-27
- Publication Date
- 2026-04-28
AI Technical Summary
Existing coke oven gas purification processes suffer from problems such as equipment blockage, safety hazards, low resource recovery efficiency, and serious environmental pollution. In particular, traditional primary cooling and electrostatic precipitator methods have problems such as large equipment footprint, high investment, high safety risks, and incomplete resource recovery.
The low-temperature coalescence purification process for coke oven gas is adopted. This process involves connecting a coking oven, a gas-liquid separator, a primary gas-liquid coalescence separation tower, a primary cold condensation recovery tower, a secondary gas-liquid coalescence separation tower, a centrifugal fan, a secondary cold condensation recovery tower, and a desulfurization tower in series to achieve low-temperature coalescence and purification of coke oven gas. This includes gas-liquid separation, condensation and cooling, and desulfurization treatment, replacing the traditional primary cooling and electrostatic tar removal methods.
It improves resource recycling efficiency, reduces equipment footprint and operating costs, eliminates safety hazards, reduces environmental pollution, increases gas dryness and utilization value, and extends the operating cycle of the unit.
Smart Images
Figure CN121930883A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of coal chemical technology, and in particular relates to a low-temperature coalescence purification process and method for coke oven gas. Background Technology
[0002] Coke oven gas, produced during the coking process, contains usable gaseous energy sources such as carbon monoxide, hydrogen, and methane, as well as harmful gases such as hydrogen sulfide, sulfur dioxide, hydrogen cyanide, and organic sulfur compounds. Coke oven gas can be utilized as both fuel gas and feedstock gas. Before comprehensive utilization, it needs to undergo staged cooling, purification, and resource recovery treatment to remove tar and improve the dryness of the purified gas.
[0003] Currently, the coke oven gas purification process adopts the "primary cooling (full intermittent cooling or intermittent cooling + direct cooling) + electrostatic tar removal method". This process is used to collect both large and small tar particles in the coke oven gas. However, the "primary cooling (full intermittent cooling or intermittent cooling + direct cooling) + electrostatic tar removal method" has a series of significant technical drawbacks, environmental and economic benefits issues.
[0004] (1) For the initial cooling (intermittent cooling) of the horizontal pipe, it is impossible to simultaneously ensure both the prevention of naphthalene crystallization and precipitation that could block the equipment pipelines and the recovery of low-pour-point tar. The amount of coal tar collected by the equipment is small, and the equipment is large in size, occupies a large area, and has high initial investment and operating costs. The reasons are as follows: ① If it is a fully intercooled system: the temperature gradient of the coke oven gas in the horizontal tube primary cooler (intercooler) is insufficient, and the gas outlet temperature is around 20-25℃; ② If it is a combination of indirect cooling and direct cooling: the temperature gradient of the coke oven gas in the horizontal tube primary cooler (indirect cooling) is insufficient, and the gas outlet temperature is around 40-45℃; ③ To prevent naphthalene crystallization and blockage of condensate pipes and equipment during the cooling process, the process temperature of coke oven gas cooling is required to be no lower than 25℃. Low-pour-point tar cannot be recovered, which poses an environmental hazard. ④ The coke oven gas flows from top to bottom in the horizontal tube cooler. The coke oven gas flows between the tubes, while the cooling water flows inside the tubes. The distribution of the gas in the horizontal tube cooler is uneven. ⑤ To solve the problem of low heat exchange efficiency caused by uneven distribution of coke oven gas, a large amount of circulating cooling water is needed to indirectly exchange heat with coke oven gas in the horizontal tube cooler, which greatly increases the volume of the horizontal tube cooler, resulting in a large footprint and correspondingly increased investment and operating costs. ⑥ The direct cooling tower washes and dissolves naphthalene in the coal gas, generating a large amount of washing wastewater that needs to be treated.
[0005] (2) For the electrostatic tar removal method, the flammable and explosive gases such as carbon monoxide, hydrogen, methane and hydrocarbons contained in the coke oven gas may explode after entering the electrostatic tar (dust) remover due to the presence of a high voltage electric field, posing certain safety hazards.
[0006] (3) The coke oven gas after “initial cooling (full intermittent cooling or intermittent cooling + direct cooling) and electrostatic purification” is “wet gas”. The low-condensation-point components tar and a large amount of saturated water vapor in the coke oven gas are carried away with the gas without being released. The tar removal efficiency is low, which is not conducive to the subsequent utilization of coke oven gas.
[0007] To address the problems existing in the above-mentioned coke oven gas purification process of primary cooling + electrostatic tar removal, a low-temperature coalescence purification process and method for coke oven gas is provided to solve the above-mentioned production problems. Summary of the Invention
[0008] This invention provides a low-temperature coalescence purification process and method for coke oven gas to solve existing problems.
[0009] This invention provides a low-temperature coalescence purification process and method for coke oven gas, comprising: The coking oven, gas-liquid separator, primary gas-liquid coalescence separation tower, primary cold condensation recovery tower, secondary gas-liquid coalescence separation tower, centrifugal fan, secondary cold condensation recovery tower, desulfurization tower, cooling water circulation pump, cooling water circulation system and refrigeration water circulation system are connected in series. The coke oven gas produced by the coke oven enters the gas-liquid separator after being sprayed and cooled by the riser pipe and bridge pipe. The gas outlet of the gas-liquid separator is connected to the first-stage gas-liquid coalescence separation tower, the first-stage gas-liquid coalescence separation tower is connected to the first-stage cold condensation recovery tower, the first-stage cold condensation recovery tower is connected to the second-stage gas-liquid coalescence separation tower, and the second-stage gas-liquid coalescence separation tower is connected to the centrifugal fan. The centrifugal fan is connected to a secondary cold condensation and recovery tower, which is connected to a desulfurization tower. The desulfurization tower produces dry and clean coke oven gas, which can be used as industrial raw material gas and fuel gas for users.
[0010] Preferably, the coke oven gas discharged from the top of the coke oven at 650℃-850℃ is rapidly cooled by spraying circulating ammonia water into the riser pipe and bridge pipe. After the temperature drops sharply to 85℃±5℃, it enters the gas-liquid separator to complete gas-liquid separation. The separated tar and ammonia water are transported to the condensate recovery tank. The gas enters the first-stage gas-liquid coalescence separation tower to remove large particles of tar, ammonia water and tar residue. The subsequent gas enters the first-stage cold condensation recovery tower to cool down to 40℃±5℃, and then enters the second-stage gas-liquid coalescence separation tower. Through the swirling, collision and coalescence action of the special structure separation blades in the tower, tar, impurities and dust are further removed. After purification, the coke oven gas is pressurized by a centrifugal fan and sent to the top of the secondary cold condensation and recovery tower. The coke oven gas flows downward in the pipe, and the refrigeration water generated by the refrigeration water circulation system is transported to the lower tube bundle for counter-current heat exchange by the refrigeration water circulation pump. When the temperature drops to 15℃±5℃, the tar and water mist in the gas are basically precipitated out. Finally, the dry and clean coke oven gas enters the desulfurization tower to complete the desulfurization treatment, solving the technical problem of long-term stable operation of the coke oven gas desulfurization system.
[0011] Preferably, the tar-ammonia-water mixture collected at the bottom of the gas-liquid separator, together with the condensate discharged from the bottom of the first-stage gas-liquid coalescing separation tower, the first-stage cold condensation recovery tower, the second-stage gas-liquid coalescing separation tower, and the second-stage cold condensation recovery tower, are collected through pipelines and flow by gravity to the condensate recovery tank. The oil (water) pump then delivers the condensate to the oil-water separator to achieve rapid oil-water separation. The separated tar is then transported to the oil storage tank for recycling, and the remaining condensate is transported to the wastewater treatment plant for standardized treatment.
[0012] Preferably, this process achieves a gradient cooling of coke oven gas from 85℃±5℃ to 15℃±5℃. The gas is cooled by a first-stage gas-liquid coalescence separation tower, a first-stage cold condensation recovery tower, and a second-stage gas-liquid coalescence separation tower before the centrifugal fan. This replaces the horizontal tube primary cooler and electrostatic tar remover in the traditional primary cooling + electrostatic tar removal method. After purification, the tar content in the coke oven gas is ≤ mg / Nm³.
[0013] Preferably, the primary cold condensation recovery tower cools the coke oven gas to a saturation temperature of 40℃±5℃, causing most of the tar in the gas to condense and precipitate, and removing condensate water, thereby reducing the gas dew point temperature.
[0014] Preferably, both the primary and secondary cold condensation recovery towers adopt a vertical pipe structure, which facilitates the smooth discharge of tar and condensate. The gas flows inside the pipes and the cooling water flows between the pipes, achieving uniform gas distribution and improving heat exchange efficiency. The heat exchange tubes are made of graphite.
[0015] Preferably, the secondary gas-liquid coalescence separation tower is equipped with an axial blade separation device. For the water mist contained in the coal gas after condensation and cooling, the gas-liquid separation is achieved through the multiple swirling coalescence action of the device. The liquid droplets merge into large particles under the action of surface tension, transform into sheet-like flow and form a liquid film, which is discharged to the bottom of the separator through the downcomer in the tower, thus achieving the technical effect of efficient water mist removal.
[0016] Preferably, the cooling medium of the secondary cold condensation recovery tower is chilled water, and a magnetic levitation variable frequency chiller unit is selected.
[0017] Preferably, the oil-water separator adopts an optimized structural design and is equipped with a dedicated oil removal element, which can achieve rapid oil-water separation. The equipment has strong anti-fouling ability, high processing efficiency, and wide applicability. The separation process does not require the addition of chemical agents, has low energy consumption, and the separated oil can be directly recycled. In addition, the equipment is easy to clean, easy to maintain, and convenient to install and operate.
[0018] Preferably, addressing the technical problem of ineffective removal of light tar from coke oven gas and subsequent contamination of the desulfurization liquid in traditional wet oxidation desulfurization processes, a two-stage cold condensation recovery tower is used to cool the coke oven gas from 40℃±5℃ to 15℃±5℃, allowing the light tar in the gas to fully separate out and preventing it from entering the desulfurization liquid and causing contamination. This effectively solves the problems of desulfurization liquid contamination, obstructed gas-liquid mass transfer, difficulty in sulfur foam formation, and poor absorption effect in traditional processes, thereby improving desulfurization efficiency and ensuring long-term stable operation of the wet desulfurization unit.
[0019] Beneficial effects
[0020] 1. Improve resource recovery efficiency, achieve gradient cooling from 85℃ to 15℃, and fully extract low-pour-point tar. The tar content in the coal gas is ≤10mg / Nm³ and the naphthalene content is ≤1.0g / m³. The tar recovery rate is 1-2% higher than that of traditional processes, and the oil can be directly recovered, thereby increasing the added value of resources. To address the pain point of equipment blockage and improve operational efficiency, the system avoids naphthalene crystallization blockage at its source. The riser structure and graphite heat exchange tubes ensure smooth condensate discharge, while the axial blade separation device achieves efficient gas-liquid separation. The dryness of the purified gas is significantly improved, and the continuous operation cycle of the unit is extended.
[0021] 2. Eliminate safety hazards and ensure more stable operation. Replace the electrostatic tar remover with coalescence separation / condensation recovery equipment, eliminate the high-voltage DC power supply, completely eliminate the safety risks of high-voltage electric fields in flammable and explosive environments, adapt to the explosion-proof requirements of coking production, and greatly improve the stability of system operation. Reduce overall lifecycle costs and minimize site requirements: The core equipment is small in size and compact in layout, replacing traditional large equipment and reducing one-time investment and floor space requirements; the magnetic levitation variable frequency chiller is highly efficient and energy-saving, the graphite heat exchange tubes require low maintenance frequency, and the process does not require the addition of chemical agents, significantly reducing operating and maintenance costs.
[0022] 3. Reduce environmental pollution, lower the processing load, eliminate the naphthalene washing process in the direct cooling tower, and avoid the generation of large amounts of washing wastewater; the condensate is centrally collected and efficiently separated into oil and water, tar is recovered, and the condensate is treated in a targeted manner, with no secondary pollution and a significant reduction in environmental hazards; To ensure the efficient operation of subsequent processes and enhance the utilization value of coal gas, low-temperature condensation removes light tar, preventing it from contaminating the desulfurization liquid. It solves the mass transfer and foaming problems of traditional wet desulfurization, ensuring the long-term stable operation of the desulfurization unit. The purified coal gas is hot and dry, with impurities thoroughly removed, and can be directly used as industrial fuel gas and chemical raw material gas, significantly improving its comprehensive utilization value.
[0023] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description
[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0025] Figure 1 This is a process diagram of a low-temperature coalescence purification process and method for coke oven gas according to the present invention; Figure 2 This is a process diagram for purifying coke oven gas using a combination of primary cooling (intermittent cooling + direct cooling) and electrostatic tar removal. Figure 3 This is a process diagram for coke oven gas primary cooling (full intermittent cooling) + electrostatic precipitator tar purification.
[0026] Explanation of reference numerals in the attached figures: Figure 1 The components are as follows: 1. Coking oven; 2. Gas-liquid separator; 3. Primary gas-liquid coalescing separation tower; 4. Primary cold condensation recovery tower; 5. Secondary gas-liquid coalescing separation tower; 6. Centrifugal fan; 7. Secondary cold condensation recovery tower; 8. Desulfurization tower; 9. Cooling water circulation pump; 10. Cooling water circulation system; 11. Refrigeration water circulation system; 12. Refrigeration water circulation pump; 13. Condensate recovery tank; 14. Oil (water) pump; 15. Oil-water separator.
[0027] Figure 2 The components are as follows: 1. Coking oven; 2. Gas-liquid separator; 3. Primary cooler (intermittent cooler); 4. Direct cooling tower; 5. Electrostatic tar (dust) remover; 6. Gas blower; 7. Desulfurization tower; 8. Ammonia water clarification tank; 9. Tar clarification tank; 10. Ammonia water intermediate tank; 11. Circulating ammonia water pump; 12. Residual ammonia water intermediate tank; 13. Tar remover; 14. Residual ammonia water tank; 15. Residual ammonia water pump; 16. Circulating water pump; 17. Circulating water pool.
[0028] Figure 3The components are as follows: 1. Coking oven; 2. Gas-liquid separator; 3. Primary cooler (intercooler); 4. Electrostatic tar (dust) remover; 5. Gas blower; 6. Desulfurization tower; 7. Ammonia water clarification tank; 8. Tar clarification tank; 9. Ammonia water intermediate tank; 10. Circulating ammonia water pump; 11. Residual ammonia water intermediate tank; 12. Tar remover; 13. Residual ammonia water tank; 14. Residual ammonia water pump; 15. Upper condensate tank; 16. Lower condensate tank. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the description, claims and drawings of this invention are intended to cover non-exclusive inclusion.
[0031] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0032] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
[0033] This invention provides, for example Figure 1 - Figure 3 The present invention discloses a low-temperature coalescence purification process and method for coke oven gas, comprising: The coking oven 1, gas-liquid separator 2, primary gas-liquid coalescence separation tower 3, primary cold condensation recovery tower 4, secondary gas-liquid coalescence separation tower 5, centrifugal fan 6, secondary cold condensation recovery tower 7, desulfurization tower 8, cooling water circulation pump 9, cooling water circulation system 10 and refrigeration water circulation system 11 are connected in series. The coke oven gas produced by the coke oven 1 enters the gas-liquid separator 2 after being sprayed and cooled by the riser pipe and bridge pipe. The gas outlet of the gas-liquid separator 2 is connected to the first-stage gas-liquid coalescence separation tower 3. The first-stage gas-liquid coalescence separation tower 3 is connected to the first-stage cold condensation recovery tower 4. The first-stage cold condensation recovery tower 4 is connected to the second-stage gas-liquid coalescence separation tower 5. The second-stage gas-liquid coalescence separation tower 5 is connected to the centrifugal fan 6. The centrifugal fan 6 is connected to the secondary cold condensation and recovery tower 7, which is connected to the desulfurization tower 8. The desulfurization tower 8 produces dry and clean coke oven gas, which can be used as industrial raw material gas and fuel gas for users.
[0034] In this embodiment, the coke oven gas discharged from the top of the coke oven 1 at 650℃-850℃ is rapidly cooled by spraying circulating ammonia water into the riser pipe and bridge pipe, and the temperature drops sharply to 85℃±5℃ before entering the gas-liquid separator 2 to complete gas-liquid separation. The separated tar and ammonia water are transported to the condensate recovery tank 13. The gas then enters the primary gas-liquid coalescence separation tower 3 to remove large particles of tar, ammonia water, and tar residue. The subsequent gas enters the primary cold condensation recovery tower 4 to be cooled to 40℃±5℃, and then enters the secondary gas-liquid coalescence separation tower 5, where it is separated by the special structure of the separation blades. Through flow, collision, and coalescence, tar, impurities, and dust are further removed. The purified coke oven gas is pressurized by centrifugal fan 6 and sent to the top of the secondary cold condensation and recovery tower 7. The coke oven gas flows downward in the pipe, and the refrigeration water generated by the refrigeration water circulation system 11 is transported to the lower tube bundle of the tube bundle by the refrigeration water circulation pump 12 for counter-current heat exchange. When the temperature drops to 15℃±5℃, the tar and water mist in the gas are basically precipitated. Finally, the dry and clean coke oven gas enters the desulfurization tower 8 to complete the desulfurization treatment, solving the technical problem of long-term stable operation of the coke oven gas desulfurization system.
[0035] In this embodiment, the tar-ammonia-water mixture collected at the bottom of the gas-liquid separator 2, together with the condensate discharged from the bottom of the primary gas-liquid coalescence separation tower 3, the primary cold condensation recovery tower 4, the secondary gas-liquid coalescence separation tower 5, and the secondary cold condensation recovery tower 7, are collected through pipelines and flow by gravity to the condensate recovery tank 13. The oil (water) pump 14 then delivers the condensate to the oil-water separator 15 to achieve rapid oil-water separation. The separated tar is then transported to the oil storage tank for recycling, and the remaining condensate is transported to the wastewater treatment plant for standardized treatment.
[0036] In this embodiment, the process achieves a gradient cooling of coke oven gas from 85℃±5℃ to 15℃±5℃. The gas is separated by a primary gas-liquid coalescence separation tower 3 before the centrifugal fan 6, a primary condensation and recovery tower 4, and a secondary gas-liquid coalescence separation tower 5. This replaces the horizontal tube primary cooler and electrostatic tar remover used in the traditional primary cooling + electrostatic tar removal method. After purification, the tar content in the coke oven gas is ≤10mg / Nm³, and the tar recovery rate is 1-2% higher than that of the traditional process. This effectively improves the dryness of the gas after condensation and cooling, and solves problems such as naphthalene crystallization clogging equipment, inability to recover low-pour-point tar, uneven gas distribution, large equipment size, high operating energy consumption, and safety hazards posed by high-voltage power supplies in the traditional process, thereby enhancing the utilization value of the coke oven gas.
[0037] In this embodiment, the primary cold condensation recovery tower 4 cools the coke oven gas to a saturation temperature of 40℃±5℃, causing most of the tar in the gas to condense and precipitate, and removing condensate, thereby lowering the gas dew point temperature; the secondary cold condensation recovery tower 7 cools the coke oven gas to a saturation temperature of 15℃±5℃, achieving full precipitation of low-pour-point tar, significantly improving the tar recovery rate, and converting the coke oven gas into hot dry gas; the naphthalene in the gas enters the condensate recovery tank 13 along with the tar and ammonia water, so that the naphthalene content of the cooled coke oven gas is ≤1.0g / m³.
[0038] In this embodiment, both the primary cold condensation recovery tower 4 and the secondary cold condensation recovery tower 7 adopt a vertical pipe structure, which facilitates the smooth discharge of tar and condensate. The gas flows inside the pipe and the cooling water flows between the pipes, achieving uniform gas distribution and improving heat exchange efficiency. The heat exchange tubes are made of graphite, which has a smooth surface, low resistance coefficient, good coalescence effect, excellent heat transfer performance, and high chemical stability. It does not react chemically with the medium, and the condensed tar does not easily adhere to the pipe wall, which is beneficial for tar recovery and can extend the equipment maintenance cycle. During the cooling process, this structure can simultaneously achieve the dual technical effects of preventing naphthalene crystallization and precipitation that blocks the equipment pipeline and recovering low-pour-point tar.
[0039] In this embodiment, the secondary gas-liquid coalescence separation tower 5 is equipped with an axial blade separation device. For the water mist contained in the coal gas after condensation and cooling, the gas-liquid separation is achieved through the multiple swirling coalescence action of the device. The liquid droplets merge into large particles under the action of surface tension, transform into sheet-like flow and form a liquid film, which is discharged to the bottom of the separator through the downcomer in the tower, thus achieving the technical effect of efficient water mist removal.
[0040] In this embodiment, the cooling medium of the secondary cold condensation recovery tower 7 is chilled water, and a magnetic levitation variable frequency chiller unit is selected. This unit can reduce the temperature of the chilled water to 8-10℃. Compared with traditional lithium bromide absorption chillers and screw-type graphite / graphite centrifugal electric chillers, it has the characteristics of high efficiency and energy saving, low noise and low vibration, no lubricating oil, maintenance-free, and long service life. It also supports intelligent control, flexible start-up, and strong adaptability.
[0041] In this embodiment, the oil-water separator 15 adopts an optimized structural design and is equipped with a dedicated oil removal element, which can achieve rapid oil-water separation. The equipment has strong anti-fouling ability, high processing efficiency, and wide applicability. The separation process does not require the addition of chemical agents and has low energy consumption. The separated oil can be directly recycled and reused. The equipment is easy to clean, easy to maintain, and convenient to install and operate.
[0042] In this embodiment, addressing the technical problem of ineffective removal of light tar from coke oven gas and subsequent contamination of the desulfurization liquid in traditional wet oxidation desulfurization processes, a secondary cold condensation recovery tower 7 is used to cool the coke oven gas from 40℃±5℃ to 15℃±5℃, allowing the light tar in the gas to fully separate out and preventing it from entering the desulfurization liquid and causing contamination. This effectively solves the problems of desulfurization liquid contamination, obstructed gas-liquid mass transfer, difficulty in sulfur foam generation, and poor absorption effect in traditional processes, thereby improving desulfurization efficiency and ensuring long-term stable operation of the wet desulfurization unit.
[0043] Working principle: Coking gas from the top of coking furnace 1 enters gas-liquid separator 2 after being cooled by spraying through riser pipe and bridge pipe. In the bridge pipe, it is rapidly cooled to about 85°C by spraying with circulating ammonia water. The tar and ammonia water mixture after spraying and washing flows from the bottom of gas-liquid separator 2 to condensate recovery tank 13. The coke oven gas, at approximately 85°C, exiting from the top of gas-liquid separator 2, tangentially enters the primary gas-liquid coalescence separation tower 3. Large particles of tar and ammonia water are separated, and tar residue is removed and discharged from the top. The gas then enters the primary cold condensation recovery tower 4 from the top, flowing downwards within the pipes. Cooling water circulating pump 9 sends cooling water upwards to the pipe space, where indirect heat exchange through the pipe walls cools the coke oven gas to 40°C. It then exits from the bottom of the primary cold condensation recovery tower 4 and directly enters the bottom of the secondary gas-liquid coalescence separation tower 5. Here, its specially structured separation blades further remove tar, impurities, and dust from the coke oven gas. The clean coke oven gas is then pressurized by centrifugal fan 6 and sent to the secondary cold condensation recovery tower. At the top of tower 7, coke oven gas flows downwards inside the pipes. The cooling water generated by the cooling water circulation system 11 is pumped by the cooling water circulation pump 12 to the lower tube bundle for counter-current heat exchange, further cooling the coke oven gas to about 15°C. Tar, water mist and naphthalene in the gas in the primary cold condensation recovery tower 4 and the secondary cold condensation recovery tower 7 are basically precipitated and discharged from the bottom along the pipe wall. During this process, most of the tar is condensed. The mixture of condensate, tar and naphthalene flows by gravity to the condensate recovery tank 13 and is sent to the oil-water separator 15 by the oil pump 14. The oil and water are quickly separated by its reasonable structural design and special oil removal elements. The light tar goes to the storage tank and the condensate goes to the sewage treatment plant for treatment.
[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A low-temperature coalescence purification process and method for coke oven gas, characterized in that, include: The coking furnace (1), gas-liquid separator (2), primary gas-liquid coalescence separation tower (3), primary cold condensation recovery tower (4), secondary gas-liquid coalescence separation tower (5), centrifugal fan (6), secondary cold condensation recovery tower (7), desulfurization tower (8), cooling water circulation pump (9), cooling water circulation system (10) and refrigeration water circulation system (11) are connected in series. The coke oven gas generated by the coke oven (1) enters the gas-liquid separator (2) after being sprayed and cooled by the riser pipe and bridge pipe. The gas outlet of the gas-liquid separator (2) is connected to the first-stage gas-liquid coalescence separation tower (3). The first-stage gas-liquid coalescence separation tower (3) is connected to the first-stage cold condensation recovery tower (4). The first-stage cold condensation recovery tower (4) is connected to the second-stage gas-liquid coalescence separation tower (5). The second-stage gas-liquid coalescence separation tower (5) is connected to the centrifugal fan (6). The centrifugal fan (6) is connected to the secondary cold condensation recovery tower (7), which is connected to the desulfurization tower (8). The desulfurization tower (8) produces dry and clean coke oven gas, which can be used as industrial raw material gas and fuel gas for users.
2. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, The coking furnace (1) discharges coking gas at 650℃-850℃ from the top. After being rapidly cooled by spraying circulating ammonia water in the riser pipe and bridge pipe, the temperature drops sharply to 85℃±5℃ before entering the gas-liquid separator (2) to complete the gas-liquid separation. The separated tar and ammonia water are transported to the condensate recovery tank (13). The gas enters the first-stage gas-liquid coalescence separation tower (3) to remove large particles of tar, ammonia water and tar residue. The subsequent gas enters the first-stage cold condensation recovery tower (4) to cool down to 40℃±5℃, and then enters the second-stage gas-liquid coalescence separation tower (5). Through the swirling, collision and coalescence action of the special structure separation blades in the tower, tar, impurities and dust are further removed. After purification, the coke oven gas is pressurized by a centrifugal fan (6) and sent to the top of the secondary cold condensation recovery tower (7). The coke oven gas flows downward in the pipe. The cooling water generated by the cooling water circulation system (11) is transported to the lower tube of the tube bundle by the cooling water circulation pump (12) for reverse heat exchange. When the temperature drops to 15℃±5℃, the tar and water mist in the gas are basically precipitated. Finally, the dry and clean coke oven gas enters the desulfurization tower (8) to complete the desulfurization treatment.
3. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, The tar-ammonia-water mixture collected at the bottom of the gas-liquid separator (2) and the condensate discharged from the bottom of the first-stage gas-liquid coalescence separation tower (3), the first-stage cold condensation recovery tower (4), the second-stage gas-liquid coalescence separation tower (5), and the second-stage cold condensation recovery tower (7) are collected through pipelines and flow by gravity to the condensate recovery tank (13). The condensate is then transported to the oil-water separator (15) by the oil (water) pump (14) to achieve rapid oil-water separation. The separated tar is transported to the oil storage tank for recycling, and the remaining condensate is transported to the wastewater treatment plant for standardized treatment.
4. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, This process achieves a gradient cooling of coke oven gas from 85℃±5℃ to 15℃±5℃. The gas is separated by a first-stage gas-liquid coalescence separation tower (3), a first-stage cold condensation recovery tower (4), and a second-stage gas-liquid coalescence separation tower (5) before the centrifugal fan (6), replacing the horizontal tube primary cooler (intermittent cooler) and electrostatic tar (dust) remover in the traditional primary cooling + electrostatic tar removal method. After the process purification, the tar content in the coke oven gas is ≤10mg / Nm³.
5. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, The primary cold condensation recovery tower (4) cools the coke oven gas to a saturation temperature of 40℃±5℃, causing most of the tar in the gas to condense and precipitate and remove the condensate, thereby reducing the gas dew point temperature.
6. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, Both the primary cold condensation recovery tower (4) and the secondary cold condensation recovery tower (7) adopt a vertical pipe structure, which facilitates the smooth discharge of tar and condensate. The gas flows inside the pipe and the cooling water flows between the pipes, so as to achieve uniform distribution of gas and improve heat exchange efficiency. The heat exchange tubes are made of graphite.
7. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, The secondary gas-liquid coalescence separation tower (5) is equipped with an axial blade separation device. For the water mist contained in the coal gas after condensation and cooling, the gas-liquid separation is achieved through the multiple swirling coalescence action of the device. The liquid droplets merge into large particles under the action of surface tension, transform into sheet-like flow and form a liquid film, which is discharged to the bottom of the separator through the downcomer in the tower, thus achieving the technical effect of efficient removal of water mist.
8. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, The cooling medium of the secondary cold condensation recovery tower (7) is chilled water, and a magnetic levitation variable frequency chiller unit is selected.
9. The low-temperature coalescence purification process and method for coke oven gas according to claim 3, characterized in that, The oil-water separator (15) adopts an optimized structural design and is equipped with a dedicated oil removal element, which can achieve rapid oil-water separation.
10. The low-temperature coalescence purification process and method for coke oven gas according to claim 1, characterized in that, To address the technical problem that light oil in coke oven gas cannot be effectively removed in traditional wet oxidation desulfurization processes, which leads to pollution of the desulfurization liquid, a two-stage cold condensation recovery tower (7) is used to cool the coke oven gas from 40℃±5℃ to 15℃±5℃, so that the light tar in the gas can be fully separated out, thus avoiding the light oil from entering the desulfurization liquid and causing pollution.