A coke dry quenching thermal system efficiency device and method

Abstract

The application provides a coke dry quenching heat system efficiency device and method, which can overcome the problems of small heat exchange temperature difference, large fan load and low-grade heat loss caused by high-temperature feed water due to traditional heat oxygen removal, realize energy saving and consumption reduction, and eliminate oxygen corrosion. The condensed water refining module comprises a water storage tank, a filter, a membrane desalination unit and a water quality on-line monitor. The low-temperature deep oxygen removal module comprises a hollow fiber membrane oxygen removal device, the water inlet of the hollow fiber membrane oxygen removal device is communicated with the qualified water outlet of the water quality on-line monitor. The hollow fiber membrane oxygen removal device is provided with a vacuum pump and a nitrogen purging unit. The waste heat step recovery module comprises a fixed continuous waste water heat exchanger, a flue heat exchanger and a steam water fine adjustment heater which are sequentially connected through pipelines. The shell side of the fixed continuous waste water heat exchanger is connected with the fixed continuous waste water of the coke dry quenching boiler. The flue heat exchanger is installed on the flue gas flow path of the coke oven flue. The water outlet of the steam water fine adjustment heater is communicated with the economizer inlet of the coke dry quenching boiler.

Description

Technical Field

[0001] This invention relates to the field of dry quenching coke thermal system optimization technology, specifically to an efficiency-enhancing device and method for a coke oven dry quenching thermal system. Background Technology

[0002] Coke dry quenching (CDQ) is a core energy-saving process in the coking industry. Its working principle involves inert nitrogen circulating within the quenching furnace, exchanging heat with the high-temperature red-hot coke. This cooling process transfers heat to the circulating nitrogen. The high-temperature circulating nitrogen then enters the waste heat boiler, passing through a heater, evaporator, and economizer to transfer heat to the boiler feedwater, generating steam for power generation or process heating. In this process, the quality of the boiler feedwater, especially its dissolved oxygen content and inlet temperature, directly determines the energy recovery efficiency, equipment safety, and operating costs of the entire system.

[0003] Existing dry quenching thermal systems suffer from the following technical bottlenecks: Traditional thermal deoxygenation requires heating feedwater to the saturation boiling point temperature at the corresponding pressure, typically above 104°C. Steam consumption accounts for a large proportion of the heat generated during the deoxygenation process, resulting in significant energy waste. Furthermore, the deoxygenation effect is greatly affected by fluctuations in steam pressure and temperature. The dissolved oxygen in the effluent cannot meet the high-precision deoxygenation requirements of high-pressure boilers, making oxygen corrosion prone to occur. Corrosion products enter the boiler and form secondary scale, further reducing boiler heat exchange efficiency, exacerbating safety risks, and leading to accidents such as boiler tube rupture. On the other hand, deoxygenation at ambient temperature requires a large amount of steam to heat the feedwater, making it impossible to achieve cascade recovery of waste heat and failing to fully realize energy-saving potential.

[0004] In the traditional process, the feedwater is heated to a high temperature of 104℃, resulting in a high water temperature entering the economizer of the boiler. The small temperature difference at the heat exchange end makes it impossible to fully recover the waste heat in the circulating nitrogen. The cold circulating gas at the inlet of the dry quenching furnace is often as high as 160℃, resulting in low cooling efficiency of red coke. This forces the circulating nitrogen fan in the system to maintain high load operation for a long time, resulting in high power consumption. At the same time, the low-grade heat from the continuous wastewater discharge and the coke oven flue is often directly discarded, resulting in extremely low overall thermal efficiency of the system. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an efficiency-enhancing device and method for a coke oven dry quenching thermal system. This method can overcome the problems caused by traditional thermal deoxygenation, such as small system heat exchange temperature difference, large fan load, and low-grade heat loss due to high-temperature feedwater. It achieves energy saving and consumption reduction, and can also eliminate oxygen corrosion.

[0006] The technical solution is as follows: an efficiency-enhancing device for a dry quenching coke oven thermal system, suitable for dry quenching coke boiler systems, characterized in that it includes components connected sequentially via pipes: The condensate refining module includes a water storage tank, a filter, and a membrane desalination unit connected in sequence by pipelines, as well as an online water quality monitoring instrument installed on the outlet side of the membrane desalination unit. The water storage tank is provided with a makeup desalination water inlet and a dry quenching boiler continuous discharge wastewater inlet. The non-compliant water outlet of the online water quality monitoring instrument is connected to the water storage tank through a reflux valve to form a non-compliant water reflux treatment loop. The low-temperature deep deoxygenation module includes a hollow fiber membrane deoxygenation device, the inlet of which is connected to the qualified water outlet of the online water quality monitoring instrument; the hollow fiber membrane deoxygenation device is equipped with a vacuum pump and a nitrogen purging unit, the vacuum pump is used to establish a negative pressure environment on the shell side of the hollow fiber membrane deoxygenation device, and the nitrogen purging unit is used to introduce nitrogen into the shell side of the hollow fiber membrane deoxygenation device for stripping; The waste heat recovery module includes a continuous wastewater heat exchanger, a flue heat exchanger, and a steam-water fine-tuning heater connected in series via pipelines. The shell side of the continuous wastewater heat exchanger is connected to the continuous wastewater from the dry quenching coke boiler. The flue heat exchanger is installed on the flue gas flow path of the coke oven's main flue. The outlet of the steam-water fine-tuning heater is connected to the economizer inlet of the dry quenching coke boiler.

[0007] Furthermore, it also includes a main control module, which dynamically adjusts the vacuum level of the vacuum pump, the flow rate of the nitrogen purging unit, and the opening degree of the corresponding valves based on the temperature, pressure, and water quality signals collected by the sensors in the system.

[0008] Furthermore, it also includes a backup protection module, which is connected in parallel with the main process link containing the low-temperature deep deoxygenation module and the waste heat cascade recovery module; the backup protection module includes a thermal deaerator, the inlet of which is connected to the qualified water outlet of the online water quality monitoring instrument, and the outlet of which is connected to the outlet of the steam-water fine-tuning heater through a switching valve and then connected to the inlet of the economizer to form a backup branch.

[0009] Furthermore, the hollow fiber membrane deoxygenation device includes a high-temperature resistant metal shell, inside which hollow fiber membrane bundles are arranged, and a water distribution plate is also arranged parallel to the cross-section of the high-temperature resistant metal shell; one end of the high-temperature resistant metal shell is provided with a liquid phase water inlet chamber and a water inlet, and the other end is provided with a liquid phase water outlet chamber and a water outlet; the side of the high-temperature resistant metal shell is provided with a nitrogen gas inlet and a vacuum extraction port, and the internal space of the shell between the nitrogen gas inlet and the vacuum extraction port constitutes a gas phase purging chamber.

[0010] Furthermore, the low-temperature deep deoxygenation module also includes a booster pump, which is located between the qualified water outlet of the online water quality monitor and the inlet of the hollow fiber membrane deoxygenation device to stabilize the inlet water pressure.

[0011] Furthermore, the waste heat cascade recovery module also includes an insulated conveying pipeline, which is connected to the continuous wastewater heat exchanger, the flue heat exchanger, and the steam-water fine-tuning heater.

[0012] A method for enhancing the efficiency of a coke oven dry quenching thermal system, based on the aforementioned coke oven dry quenching thermal system enhancement device, is characterized by comprising the following steps: Step S1: The wastewater from the dry quenching coke boiler and the supplementary demineralized water are introduced into the storage tank for buffering and mixing. After the suspended impurities are removed by the filter of the condensate refining module and the deep desalination treatment by the membrane desalination unit, the water is tested by the online water quality monitoring instrument. The qualified water is sent to the next step, and the unqualified water is returned to the storage tank for reprocessing. Step S2: Qualified refined demineralized water with a temperature not exceeding 65℃ enters the hollow fiber membrane deoxygenation device. The vacuum pump is started to establish a negative pressure environment on the shell side. At the same time, nitrogen is introduced into the shell side through the nitrogen purging unit for stripping. The dissolved oxygen concentration of the effluent is controlled below the preset safety threshold to obtain oxygen-free demineralized water. Step S3: The deoxygenated demineralized water first enters the continuous wastewater heat exchanger to recover the waste heat of the continuous wastewater from the dry quenching coke boiler for the first stage of heating; then it enters the flue heat exchanger to absorb the waste heat of the flue gas from the coke oven's main flue for the second stage of heating; finally, it passes through the steam-water fine-tuning heater, using steam to fine-tune the water temperature to the target temperature before sending it to the economizer inlet of the dry quenching coke boiler.

[0013] Furthermore, step S4 is also included: the main control module acquires the thermal balance parameters of the entire system in real time, and maintains the economizer inlet temperature stable by adjusting the steam flow rate of the steam-water fine-tuning heater; it adaptively adjusts the operating load of the circulating fan in the system according to the change of feedwater temperature; and it issues an alarm signal when the water quality or deoxygenation index exceeds the safety threshold.

[0014] Furthermore, step S5 is also included: when the main control module detects a fault in the main process link, including the low-temperature deep deoxygenation module and the waste heat cascade recovery module, it automatically controls the switching valve to switch the water circuit to the backup branch where the thermal deaerator is located. After the fault is cleared, it switches back to the main process link.

[0015] Furthermore, in step S3, the oxygen-free demineralized water is heated to 75°C~80°C after recovering waste heat through a continuous wastewater heat exchanger; it is heated to 85°C~88°C after absorbing waste heat from the flue gas through a flue heat exchanger; and it is heated to 90°C after being finely adjusted by a steam-water fine-tuning heater before being sent to the economizer inlet.

[0016] The coke oven dry quenching thermal system enhancement device of the present invention, through its hollow fiber membrane deoxygenation device, can achieve a stable dissolved oxygen level of <7ppb in the effluent at ≤65℃, which is a significant improvement over traditional thermal deoxygenation. The oxygen-free process of the present invention, which involves deoxygenation followed by heating, greatly reduces the corrosion rate of boiler tubes, extends the service life of boiler tubes, significantly extends the scale removal cycle, and eliminates the risk of safety accidents such as boiler tube rupture.

[0017] The coke oven dry quenching thermal system efficiency enhancement device of this invention can achieve cascaded energy utilization, significantly reduce steam consumption, and achieve full absorption of low-grade waste heat. The lower temperature, oxygen-free demineralized water, continuous wastewater, and coke oven flue gas have a larger heat exchange temperature difference, allowing for the full absorption of low-grade waste heat. Only a small amount of steam is needed for temperature adjustment before entering the boiler. Taking a 140t / h dry quenching system as an example, a full-process model of the system was established using Aspen Plus software. The model was validated using actual operating data from a certain plant, and the deviation between the simulated and measured values ​​was less than 3%. Based on the validated model, simulation calculations were performed on the optimized system. The results show that the total steam consumption of the system decreased from 15t / h to 1.2t / h, a reduction of 92%, saving over 100,000 tons of steam annually; the overall thermal efficiency of the system increased from 40.2% to 89.7%.

[0018] The coke oven dry quenching thermal system efficiency enhancement device of the present invention reduces energy consumption in synergy with the circulation system, fully releasing the energy-saving potential. The economizer inlet feedwater temperature is reduced, the heat exchange temperature difference between the hot and cold ends is greatly increased, and the cold circulating gas temperature at the dry quenching furnace inlet is reduced. The cold circulating gas density is increased, the volumetric flow rate requirement of the circulating fan is reduced, and the operating power is reduced, thus reducing power consumption.

[0019] In addition, the coke oven dry quenching thermal system efficiency enhancement device of the present invention is also equipped with a backup protection module that forms a parallel structure with the main process link. When the main process link fails, it can automatically switch to the backup branch operation in a short time to ensure that the boiler feedwater is not interrupted and improve the overall operational reliability of the system.

[0020] The device of this invention can be directly connected to the existing dry quenching thermal system without significant changes to the original system structure. It has a short construction period and minimal impact on production stoppage, making it suitable for new construction and renovation projects of various series of dry quenching systems. Attached Figure Description

[0021] Figure 1 This is a block diagram of a coke oven dry quenching thermal system efficiency enhancement device according to one embodiment of the present invention; Figure 2 This is a detailed system composition block diagram of the coke oven dry quenching thermal system efficiency enhancement device in one embodiment of the present invention; Figure 3This is a schematic diagram of the hollow fiber membrane deoxygenation device in the embodiment; Figure 4 This is a schematic diagram illustrating the application of the coke oven dry quenching thermal system enhancement device of the embodiment to the dry quenching coke boiler system. Figure 5 This is a block diagram of a coke oven dry quenching thermal system efficiency enhancement device according to one embodiment of the present invention; Figure 6 This is a detailed system composition block diagram of a coke oven dry quenching thermal system enhancement device according to one embodiment of the present invention. Detailed Implementation

[0022] See Figure 1 , 2 This invention discloses an efficiency-enhancing device for a coke oven dry quenching thermal system, applicable to a dry quenching boiler system. The dry quenching boiler system includes a dry quenching boiler 600, an economizer 601, and a boiler flue. The efficiency-enhancing device for the coke oven dry quenching thermal system comprises the following components connected sequentially by pipes: The condensate refining module 100 includes a water storage tank 101, a filter 102, and a membrane desalination unit 103 connected in sequence by pipelines, as well as an online water quality monitor 104 installed on the outlet side of the membrane desalination unit. The water storage tank 101 is provided with a supplemental demineralized water inlet and a dry quenching boiler continuous discharge wastewater inlet. The unqualified water outlet of the online water quality monitor 104 is connected to the water storage tank 101 through a return valve 105 to form an unqualified water return treatment loop. The low-temperature deep deoxygenation module 200 includes a hollow fiber membrane deoxygenation device 201, the inlet of which is connected to the qualified water outlet of the online water quality monitor 104. The hollow fiber membrane deoxygenation device 201 is equipped with a vacuum pump 202 and a nitrogen purging unit 203. The vacuum pump 202 is used to establish a negative pressure environment on the shell side of the hollow fiber membrane deoxygenation device, and the nitrogen purging unit 203 is used to introduce nitrogen into the shell side of the hollow fiber membrane deoxygenation device for stripping. The waste heat recovery module 300 includes a continuous wastewater heat exchanger 301, a flue heat exchanger 302, and a steam-water fine-tuning heater 303 connected in series via pipelines. The shell side of the continuous wastewater heat exchanger 301 is connected to the continuous wastewater of the dry quenching coke boiler. The flue heat exchanger 302 is installed on the flue gas flow path of the coke oven's main flue. The outlet of the steam-water fine-tuning heater 303 is connected to the inlet of the economizer 601 of the dry quenching coke boiler.

[0023] In an embodiment of the present invention, the renovation of four dry quenching coke boilers in the third phase of a steel plant base is taken as the application scenario. The implementation method of the device of the present invention is described in detail. The model is Q261 / 880-92-10.3 / 540, with a single unit designed evaporation capacity of 49t / h and a total actual evaporation capacity of 140t / h.

[0024] In this embodiment, the condensate purification module 100 includes a water storage tank 101, a filter 102, and a membrane desalination unit 103 connected in sequence by a pipeline, as well as an online water quality monitor 104 installed on the outlet side of the membrane desalination unit. In this embodiment, the filter 102 is a ceramic membrane filter, and the membrane desalination unit 103 is an ultra-nano EDI membrane desalination unit.

[0025] The water storage tank 101 has two inlets, one of which is connected to the continuous discharge wastewater from the dry quenching boiler 600, and the other is connected to the demineralized water supply pipeline. The two are buffered and mixed in the water storage tank 101. The mixed water passes through the filter 102 to remove suspended particles, oil, and iron oxides, and then passes through the membrane desalination unit 103 to remove hardness ions, silica, and trace salts. The treated water enters the online quality monitoring instrument 104 for real-time monitoring. The monitoring items include hardness, iron, copper, silica, and dissolved oxygen. The detection accuracy is ±0.1μmol / L for hardness, ±1μg / L for iron, ±0.5μg / L for copper, ±1μg / L for silica, and ±0.07ppb for dissolved oxygen. Qualified water with a temperature of about 60℃ is sent to the low-temperature deep deoxygenation module 200; unqualified water is returned to the water storage tank 101 for reprocessing through the return valve 105.

[0026] See Figure 3 In this embodiment, the low-temperature deep deoxygenation module includes a hollow fiber membrane deoxygenation device 201. This embodiment configures one set with a processing capacity of 144.2 t / h. In this embodiment, the hollow fiber membrane deoxygenation device 201 includes a high-temperature resistant metal shell 2011. Hollow fiber membrane bundles 2013 are arranged inside the high-temperature resistant metal shell 2011. A water distribution plate is also arranged parallel to the cross-section of the high-temperature resistant metal shell. One end of the high-temperature resistant metal shell 2011 is provided with a liquid phase water inlet chamber 2014 and a water inlet 2015, and the other end is provided with a liquid phase water outlet chamber 2016 and a water outlet 2017. The side of the high-temperature resistant metal shell is provided with a nitrogen inlet 2018 and a vacuum extraction port 2019. The internal space of the shell between the nitrogen inlet 2018 and the vacuum extraction port 2019 constitutes a gas phase purging chamber 20110. In the embodiment, the ratio of nitrogen purging flow rate to water inlet flow rate of the nitrogen purging unit is 1:10 to 1:20; the working negative pressure of the vacuum pump is 0.001 to 0.005 MPa.

[0027] In this embodiment, the low-temperature deep deoxygenation module 200 also includes a booster pump 204, which is located between the qualified water outlet of the online water quality monitor 104 and the water inlet of the hollow fiber membrane deoxygenation device 201 to stabilize the inlet water pressure.

[0028] During operation, refined demineralized water at approximately 60°C is pressurized by booster pump 204 and enters the liquid phase inlet chamber through the inlet. It flows from bottom to top along the inner cavity of the hollow fiber membrane bundle and collects in the liquid phase outlet chamber at the other end, then is discharged from the outlet. Simultaneously, vacuum pump 202 establishes a negative pressure environment of 0.003 MPa in the gas phase purging chamber. Nitrogen purging unit 203 introduces high-purity nitrogen into the gas phase purging chamber through nitrogen inlet. The nitrogen flows from bottom to top across the outer surface of the membrane fibers in the gas phase purging chamber, forming a countercurrent contact with the oxygenated water in the inner cavity of the membrane fibers. Under the dual drive of concentration difference and pressure difference, dissolved oxygen permeates through the membrane wall from the aqueous phase to the gas phase, is carried by nitrogen, and is discharged from the system through the vacuum port.

[0029] The deoxygenation effect can be theoretically verified using Henry's law and the two-film mass transfer equation. The calculation basis for the nitrogen purging flow rate is as follows: Among them, Q n Nitrogen purging flow rate, unit: Nm³ 3 / h; C is the deoxygenated water flow rate, in t / h; C0 is the dissolved oxygen concentration in the influent, in ppb; C e The target dissolved oxygen value for effluent is ppb; in this example, the target dissolved oxygen value is <7ppb; M is the molar mass of oxygen, 32 g / mol; P is the system pressure, in MPa; y is the mole fraction of oxygen in nitrogen; k la The volumetric mass transfer coefficient is expressed in h. -1 V represents the effective volume of the deaerator, in cubic meters (m³). 3 .

[0030] Under the above operating conditions, the dissolved oxygen in the effluent is stable at 0.5ppb~0.8ppb, with a pass rate of nearly 100%, which is more than 15 times higher than the precision of traditional thermal deoxygenation; and there is no steam consumption throughout the entire process.

[0031] The hollow fiber membrane deoxygenation device 201 achieves deep deoxygenation at temperatures not exceeding 65℃, stably controlling the dissolved oxygen in the effluent to below 7 ppb. This represents an improvement of more than an order of magnitude compared to the 15-25 μg / L accuracy of traditional thermal deoxygenation. Membrane deoxygenation utilizes the mass transfer process driven by the concentration and pressure differences across the membrane. Its deoxygenation efficiency is unaffected by fluctuations in feed water temperature. Furthermore, through the dual drive of vacuum negative pressure and nitrogen stripping, the oxygen partial pressure on the outside of the membrane fibers can be maintained at an extremely low level, ensuring efficient mass transfer. The force is far greater than that of boiling alone in thermal deoxygenation. Since deoxygenation is completed at a low temperature, the subsequent cascade heat exchange and heating processes are all carried out in an oxygen-free state. The feedwater will not cause oxygen corrosion to the pipes and heat exchangers from the time it is deoxygenated until it enters the boiler. This cuts off the path of high-temperature oxygen-containing water corrosion of pipes in the traditional process of heating first and then deoxygenating. According to engineering measurement data, the corrosion rate of boiler tubes can be reduced from 0.12 mm / a to 0.009 mm / a, a reduction of more than 92%.

[0032] The feedwater temperature after low-temperature deoxygenation does not exceed 65℃, and there is a larger temperature gradient between it and the continuous discharge wastewater (100℃~130℃) and the coke oven flue gas (183℃~195℃). This gives the waste heat recovery stage a more abundant heat exchange driving force in terms of thermodynamics. After the feedwater absorbs the low-grade waste heat from the continuous discharge wastewater and coke oven flue gas in sequence, it only needs a small amount of steam to be finely adjusted to 90℃ before entering the economizer. The steam consumption in the deoxygenation stage is reduced, and the saved steam can be directly used for power generation. At the same time, the full recovery of waste heat from the continuous discharge wastewater and flue gas increases the overall thermal efficiency of the system from 40.2% to 89.7%.

[0033] In this embodiment, the waste heat recovery module 300 processes the heat as follows: The deoxygenated water at approximately 60°C, after membrane deoxygenation, first enters the continuous wastewater heat exchanger 301. The shell side of the continuous wastewater heat exchanger 301 receives the continuous wastewater discharged from the dry quenching coke boiler 600, while the tube side receives the deoxygenated water. The deoxygenated water absorbs the waste heat from the continuous wastewater and rises to approximately 78°C. The heated oxygen-free demineralized water enters the flue heat exchanger 302. In this embodiment, the flue heat exchanger is a graphene wide-channel flue heat exchanger. In other embodiments, the type of heat exchanger is selected reasonably according to each operating condition. The flue heat exchanger is installed between the fan outlet and the chimney of the coke oven main flue. Utilizing the high thermal conductivity and wide-channel structure design of graphene material, the heat exchange efficiency is not less than 90% while the additional wind resistance is controlled below 550Pa, which meets the requirements of the new national standard GB151-2026 for heat exchangers. The flue gas temperature in the coke oven main flue is about 195°C. After absorbing the waste heat of the flue gas, the oxygen-free demineralized water is heated to about 87°C. After two-stage heat exchange, the oxygen-free demineralized water finally enters the steam-water fine-tuning heater 303, where the water temperature is precisely fine-tuned to 90°C by low-pressure steam.

[0034] At this time, the steam consumption is only 1.2t / h, which is 92% less than the 15t / h steam consumption of the traditional thermal deoxygenation scheme. The oxygen-free demineralized water heated to 90℃ is sent to the inlet of the economizer 601 of the dry quenching coke boiler 600 through the switching valve.

[0035] The waste heat recovery module 300 also includes an insulated conveying pipeline, which is installed in conjunction with the connecting pipeline between the continuous wastewater heat exchanger 301, the flue heat exchanger 302 and the steam-water fine-tuning heater 303, which can reduce heat loss during the conveying process.

[0036] like Figure 4 As shown, the coke oven dry quenching thermal system efficiency enhancement device of this embodiment is applied to the dry quenching boiler system. The dry quenching boiler system includes a dry quenching furnace, primary dust removal, boiler superheater, evaporator, economizer, secondary dust removal, and nitrogen circulating fan. In this embodiment, the heat balance calculation and verification of the entire system were carried out based on the measured operating data of a 140t / h dry quenching boiler system. The core basic parameters in this embodiment are shown in Table 1, including: total boiler feedwater flow rate of 144.2t / h, economizer outlet feedwater temperature of 165℃ (corresponding to enthalpy of 695.1kJ / kg), circulating gas mass flow rate of 225000kg / h, circulating gas specific heat capacity at constant pressure of 1.038kJ / (kg·℃), and economizer inlet circulating gas temperature of 320℃.

[0037] Table 1 The economizer's heat exchange capacity is determined by calculation using the heat transfer equation and the system's heat balance model. The calculation formula is as follows: Among them, Q sm The economizer's heat exchange capacity is expressed in kJ / h; K is the overall heat transfer coefficient, expressed in W / (m³). 2 ℃); A is the heat exchange area, in m² 2 ;Δt m This is the logarithmic mean temperature difference, in °C. This refers to the boiler feedwater flow rate, expressed in kg / h. The value is the enthalpy of the economizer outlet feedwater, in kJ / kg; The value represents the enthalpy of the feedwater at the economizer inlet, expressed in kJ / kg.

[0038] Before the adoption of traditional thermal deaeration modification: The economizer inlet feedwater temperature is 104℃, corresponding to an enthalpy of 436.0 kJ / kg.

[0039] Economizer feedwater heat absorption Q sm1 =144200×(695.1-436.0)=37362220kJ / h.

[0040] The outlet temperature t of the recirculated gas after passing through the economizer gout1 =320-37362220 / (225000×1.038)≈160℃.

[0041] After modification using the device in the embodiments: The economizer inlet feedwater temperature is 90℃, corresponding to an enthalpy of 376.9kJ / kg.

[0042] Economizer feedwater heat absorption Q sm2 =144200×(695.1-376.9)=45884240kJ / h, heat exchange capacity increased by 22.8%. See Table 2 for a comparison of core parameters before and after the economizer modification: Table 2 According to the heat transfer equation Q=K×A×Δtm, with the economizer heat transfer coefficient K and heat exchange area A remaining constant, the heat transfer is proportional to the logarithmic mean temperature difference. The outlet circulating gas temperature t of the modified economizer can be obtained through iterative calculation. gout2 ≈132℃.

[0043] Thermal balance calculations show that after the economizer inlet feedwater temperature is reduced from 104℃ to 90℃, the dry quenching furnace inlet cold circulating gas temperature is reduced from 160℃ to 132℃, a decrease of 28℃.

[0044] The coke oven dry quenching thermal system efficiency enhancement device of this embodiment is applied to the dry quenching coke boiler system for energy-saving verification of the circulating fan, as detailed below: The shaft power of the circulating fan is directly proportional to the volumetric flow rate of the gas being transported under operating conditions. In the formula: N is the fan shaft power, in kW; The gas volumetric flow rate under operating conditions, in cubic meters per second (m³). 3 / h; P is the total pressure of the fan, in Pa. When the system resistance remains constant, P is constant; η is the total pressure efficiency of the fan, in %, when the operating conditions are stable, η is constant.

[0045] According to Charles's Law, the gas volume flow rate is directly proportional to the thermodynamic temperature: Qv2 / Qv1=T2 / T1=(132+273.15) / (160+273.15)=405.15 / 433.15≈0.9354.

[0046] With the total pressure P and efficiency η of the fan remaining constant, the shaft power is proportional to the volumetric flow rate. The actual operating power of the modified wind turbine, N2, is 594kW.

[0047] Energy saving per hour ΔN: ΔN = 635 - 594 = 41kW Based on 8600 hours of operation per year, the annual electricity saving is calculated as: 41kW × 8600h = 352600kWh ≈ 352,600kWh; based on a price of 0.45 yuan per kWh, the annual electricity saving benefit is calculated as: 352600kWh × 0.45 yuan / kWh ≈ 158,700 yuan.

[0048] The instrument measurement data from continuous operation at the aforementioned steel plant phase III project in this embodiment are as follows: In terms of deoxygenation effect: under 60℃ operating conditions, the dissolved oxygen in the effluent is stable at 0.5ppb~0.8ppb, with a pass rate of 100%, which is more than 15 times higher than the precision of traditional thermal deoxygenation.

[0049] In terms of energy saving: the total steam consumption of the system has been reduced from 15t / h to 1.2t / h, a reduction of 92%, saving approximately 144,480t of steam per year; the circulating fan saves approximately 352,600 kWh of electricity per year.

[0050] In terms of system efficiency: the overall system thermal efficiency increased from 40.2% to 89.7%; the boiler evaporation capacity increased from 140t / h to 147t / h.

[0051] In terms of corrosion prevention: the corrosion rate of boiler tubes decreased from 0.12 mm / a to 0.009 mm / a, a reduction of 92.5%; the service life of boiler tubes was extended from 10 years to more than 18 years; and the scale removal cycle was extended from 1 year to 6 years.

[0052] In terms of environmental benefits: Zero discharge of wastewater from continuous discharge system; annual reduction of CO2 emissions by 28,000 tons and dust emissions by 185 tons.

[0053] See Figure 5 , Figure 6 In one embodiment of the present invention, the coke oven dry quenching thermal system efficiency enhancement device further includes: a backup protection module 400, which is connected in parallel with the main process link where the low temperature deep deoxygenation module 200 and the waste heat cascade recovery module 300 are located; the backup protection module 400 includes a thermal deaerator 401, the inlet of the thermal deaerator is connected to the qualified water outlet of the online water quality monitoring instrument 104, and the outlet of the thermal deaerator 401 is connected to the outlet of the steam-water fine-tuning heater 303 through a switching valve 402 and then connected to the inlet of the economizer to form a backup branch.

[0054] The main control module 500 dynamically adjusts the vacuum level of the vacuum pump, the flow rate of the nitrogen purging unit, and the opening degree of the corresponding valves based on the temperature, pressure, and water quality signals collected by the sensors in the system. The main control module 500 is also electrically connected to the switching valve 402 of the backup protection module.

[0055] The main control module 500 monitors the temperature, pressure, and water quality signals collected by sensors in the real-time monitoring system. All parameter optimizations adhere to the principle of safety first: when a parameter approaches a safety threshold, optimization and adjustment automatically stop and the current parameter is locked; when a parameter exceeds a safety threshold, such as dissolved oxygen ≥7ppb, water quality indicators exceeding standards, or abnormal nitrogen circulation pressure, an alarm signal is immediately issued and an emergency interlock protection program is triggered. When a serious fault is detected in the main process link, the main control module 500 automatically controls the switching valve 402 to switch the water circuit to the backup branch where the original thermal deaerator 401 is located, ensuring uninterrupted feedwater supply to the dry quenching boiler.

[0056] The backup protection module retains the original thermal deaerator as a parallel backup branch, switching over in the event of a failure in the main process link to ensure uninterrupted feedwater supply to the dry quenching boiler. This backup protection module design not only ensures production safety but also reduces the owner's concerns about the reliability of new technologies in retrofit projects, enhancing the practical scalability of the device in industrial settings.

[0057] In an embodiment of the present invention, a method for enhancing the efficiency of a coke oven dry quenching thermal system is also provided, which is implemented based on the above-mentioned coke oven dry quenching thermal system enhancement device, and includes the following steps: Step S1: The wastewater from the dry quenching coke boiler and the supplementary demineralized water are introduced into the storage tank for buffering and mixing. After the suspended impurities are removed by the filter of the condensate refining module and the deep desalination treatment by the membrane desalination unit, the water is tested by the online water quality monitoring instrument. The qualified water is sent to the next step, and the unqualified water is returned to the storage tank for reprocessing until it is qualified. Step S2: Qualified purified demineralized water with a temperature not exceeding 65℃ enters the hollow fiber membrane deoxygenation unit. The vacuum pump is started to establish a negative pressure environment on the shell side. Simultaneously, nitrogen is introduced into the shell side through the nitrogen purging unit for stripping, controlling the dissolved oxygen concentration of the effluent below a preset safety threshold to obtain oxygen-free demineralized water. The ratio of nitrogen purging flow rate to influent flow rate is 1:10 to 1:20. Under the combined effects of negative pressure and nitrogen stripping, dissolved oxygen in the water diffuses and transfers mass from the liquid phase to the gas phase through the hollow fiber membrane wall, and is continuously removed. The process also includes a dissolved oxygen detection and feedback adjustment mechanism: the dissolved oxygen concentration in the effluent is monitored in real time to determine if it is <7ppb; if it meets the standard, the effluent proceeds to step S3; if it does not meet the standard, the negative pressure value and nitrogen purging flow rate are dynamically adjusted until the dissolved oxygen in the effluent reaches the requirement of <7ppb. Under the condition of ≤65℃, the dissolved oxygen in the effluent can be stably controlled at <7ppb, and no steam consumption is required throughout the process. Step S3: The deoxygenated demineralized water first enters the continuous discharge wastewater heat exchanger to recover the waste heat of the continuous discharge wastewater from the dry quenching coke boiler for the first stage of heating; the deoxygenated demineralized water exchanges heat with the continuous discharge wastewater from the dry quenching coke boiler at 100℃~130℃, and the deoxygenated demineralized water is heated to 75~80℃. Then it enters the flue heat exchanger, where it absorbs the waste heat of the flue gas from the coke oven's main flue for a second stage of heating. It exchanges heat with the flue gas from the coke oven's main flue at 183℃~195℃. The oxygen-free demineralized water is further heated to 85~88℃. After the flue gas is cooled to about 150℃, it is discharged to the denitrification system or the chimney. Finally, the demineralized water is precisely temperature-adjusted by a steam-water fine-tuning heater using low-pressure saturated steam. After the water temperature is adjusted to the target temperature, it is sent to the economizer inlet of the dry quenching boiler to raise the temperature to 90°C. The steam condensate is recycled and reused. The oxygen-free demineralized water heated to 90°C is sent to the economizer inlet of the dry quenching boiler via a switching valve.

[0058] In one embodiment, the system further includes step S4: the main control module acquires the thermal balance parameters of the entire system in real time, and maintains the economizer inlet temperature stable by adjusting the steam flow rate of the steam-water fine-tuning heater; it adaptively adjusts the operating load of the circulating fan in the system according to the change of feedwater temperature; and it issues an alarm signal when the water quality or deoxygenation index exceeds the safety threshold. In one embodiment, step S5 is also included: when the main control module detects a fault in the main process link including the low-temperature deep deoxygenation module and the waste heat cascade recovery module, it automatically controls the switching valve to switch the water circuit to the backup branch where the thermal deaerator is located, and switches back to the main process link after the fault is cleared.

[0059] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An efficiency-enhancing device for a dry quenching coke oven thermal system, applicable to dry quenching coke boiler systems, characterized in that, Including those connected sequentially via pipes: The condensate refining module includes a water storage tank, a filter, and a membrane desalination unit connected in sequence by pipelines, as well as an online water quality monitoring instrument installed on the outlet side of the membrane desalination unit. The water storage tank is provided with a makeup desalination water inlet and a dry quenching boiler continuous discharge wastewater inlet. The non-compliant water outlet of the online water quality monitoring instrument is connected to the water storage tank through a reflux valve to form a non-compliant water reflux treatment loop. The low-temperature deep deoxygenation module includes a hollow fiber membrane deoxygenation device, the inlet of which is connected to the qualified water outlet of the online water quality monitoring instrument; the hollow fiber membrane deoxygenation device is equipped with a vacuum pump and a nitrogen purging unit, the vacuum pump is used to establish a negative pressure environment on the shell side of the hollow fiber membrane deoxygenation device, and the nitrogen purging unit is used to introduce nitrogen into the shell side of the hollow fiber membrane deoxygenation device for stripping; The waste heat recovery module includes a continuous wastewater heat exchanger, a flue heat exchanger, and a steam-water fine-tuning heater connected in series via pipelines. The shell side of the continuous wastewater heat exchanger is connected to the continuous wastewater from the dry quenching coke boiler. The flue heat exchanger is installed on the flue gas flow path of the coke oven's main flue. The outlet of the steam-water fine-tuning heater is connected to the economizer inlet of the dry quenching coke boiler.

2. The coke oven dry quenching thermal system efficiency enhancement device according to claim 1, characterized in that: It also includes a main control module, which dynamically adjusts the vacuum level of the vacuum pump, the flow rate of the nitrogen purging unit, and the opening degree of the corresponding valves based on the temperature, pressure, and water quality signals collected by the sensors in the system.

3. The coke oven dry quenching thermal system efficiency enhancement device according to claim 1, characterized in that: It also includes a backup protection module, which is connected in parallel with the main process link containing the low-temperature deep deoxygenation module and the waste heat cascade recovery module; the backup protection module includes a thermal deaerator, the inlet of which is connected to the qualified water outlet of the online water quality monitoring instrument, and the outlet of which is connected to the outlet of the steam-water fine-tuning heater through a switching valve and then connected to the inlet of the economizer to form a backup branch.

4. The coke oven dry quenching thermal system efficiency enhancement device according to claim 1, characterized in that: The hollow fiber membrane deoxygenation device includes a high-temperature resistant metal shell, inside which hollow fiber membrane bundles are arranged. A water distribution plate is also arranged parallel to the cross-section of the high-temperature resistant metal shell. One end of the high-temperature resistant metal shell is provided with a liquid phase water inlet chamber and a water inlet, and the other end is provided with a liquid phase water outlet chamber and a water outlet. The side of the high-temperature resistant metal shell is provided with a nitrogen gas inlet and a vacuum extraction port. The internal space of the shell between the nitrogen gas inlet and the vacuum extraction port constitutes a gas phase purging chamber.

5. The coke oven dry quenching thermal system efficiency enhancement device according to claim 1, characterized in that: The low-temperature deep deoxygenation module also includes a booster pump, which is located between the qualified water outlet of the online water quality monitor and the water inlet of the hollow fiber membrane deoxygenation device to stabilize the inlet water pressure.

6. The coke oven dry quenching thermal system efficiency enhancement device according to claim 1, characterized in that: The waste heat cascade recovery module also includes an insulated conveying pipeline, which is connected to the continuous wastewater heat exchanger, the flue heat exchanger, and the steam-water fine-tuning heater.

7. A method for enhancing the efficiency of a coke oven dry quenching thermal system, implemented based on the coke oven dry quenching thermal system enhancement device according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step S1: The wastewater from the dry quenching coke boiler and the supplementary demineralized water are introduced into the storage tank for buffering and mixing. After the suspended impurities are removed by the filter of the condensate refining module and the deep desalination treatment by the membrane desalination unit, the water is tested by the online water quality monitoring instrument. The qualified water is sent to the next step, and the unqualified water is returned to the storage tank for reprocessing. Step S2: Qualified refined demineralized water with a temperature not exceeding 65℃ enters the hollow fiber membrane deoxygenation device. The vacuum pump is started to establish a negative pressure environment on the shell side. At the same time, nitrogen is introduced into the shell side through the nitrogen purging unit for stripping. The dissolved oxygen concentration of the effluent is controlled below the preset safety threshold to obtain oxygen-free demineralized water. Step S3: The deoxygenated demineralized water first enters the continuous wastewater heat exchanger to recover the waste heat of the continuous wastewater from the dry quenching coke boiler for the first stage of heating; then it enters the flue heat exchanger to absorb the waste heat of the flue gas from the coke oven's main flue for the second stage of heating; finally, it passes through the steam-water fine-tuning heater, using steam to fine-tune the water temperature to the target temperature before sending it to the economizer inlet of the dry quenching coke boiler.

8. The method for enhancing the efficiency of a coke oven dry quenching thermal system according to claim 7, characterized in that, It also includes step S4: the main control module acquires the thermal balance parameters of the entire system in real time, and maintains the economizer inlet temperature stable by adjusting the steam flow of the steam-water fine-tuning heater; it adaptively adjusts the operating load of the circulating fan in the system according to the change of feedwater temperature; and it issues an alarm signal when the water quality or deoxygenation index exceeds the safety threshold.

9. The method for enhancing the efficiency of a coke oven dry quenching thermal system according to claim 7, characterized in that, It also includes step S5: when the main control module detects a fault in the main process link, including the low-temperature deep deoxygenation module and the waste heat cascade recovery module, it automatically controls the switching valve to switch the water circuit to the backup branch where the thermal deaerator is located. After the fault is cleared, it switches back to the main process link.

10. The method for enhancing the efficiency of a coke oven dry quenching thermal system according to claim 7, characterized in that, In step S3, the oxygen-free demineralized water is heated to 75°C~80°C after recovering waste heat through a continuous wastewater heat exchanger; it is heated to 85°C~88°C after absorbing waste heat from the flue gas through a flue heat exchanger; and it is heated to 90°C after being finely adjusted by a steam-water fine-tuning heater before being sent to the economizer inlet.

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