Flue gas desulfurization, CO removal and denitration synergistic treatment system and control method thereof

Abstract

The invention discloses a flue gas desulfurization, CO removal and denitration collaborative treatment system and a control method thereof, and belongs to the technical field of atmospheric pollutant treatment. The system comprises a temperature control device, an activated carbon desulfurization and denitrification device, a low-temperature CO removal device, an ultralow-temperature denitrification device and a chimney which are sequentially arranged in the flowing direction of flue gas, and is provided with a graded ammonia spraying control device, a fan, a plurality of flue gas emission continuous monitoring mechanisms and a cooperative controller. According to the method, SO2 is efficiently removed through front activated carbon desulfurization and denitrification so as to protect a CO removal catalyst, meanwhile, temperature rise is self-maintained for rear ultralow-temperature denitrification through desulfurization and CO removal reaction heat, external heat compensation is not needed in the whole process, and a GGH is not arranged; and the cooperative controller and graded ammonia spraying control are combined, so that precise ammonia spraying and multi-pollutant cooperative treatment are realized. The method has the advantages of being simple in process, low in investment and operation cost, low in energy consumption, free of external heat compensation and the like.

Description

Technical Field

[0001] This invention belongs to the field of air pollutant treatment technology, and relates to air pollutant SO2, CO and NOx purification technologies, specifically a flue gas desulfurization, deCO and denitrification synergistic treatment system and its control method. Background Technology

[0002] Currently, industrial flue gas emissions typically contain multiple pollutants such as sulfur dioxide, nitrogen oxides, and carbon monoxide, requiring coordinated treatment to meet emission standards before discharge. Traditional integrated flue gas treatment processes often employ a combination of desulfurization and SCR denitrification technologies, which have been widely adopted. However, this process has the following shortcomings in practical applications: Conventional SCR denitrification catalysts typically operate within a high-efficiency reaction temperature range of 200℃ to 400℃. However, after wet or semi-dry desulfurization, the temperature of the flue gas usually drops below 100℃, failing to directly meet the temperature requirements of SCR denitrification. To increase the flue gas temperature, existing technologies typically require supplementary heating devices such as flue gas reheaters, hot air furnaces, and electric heaters, or the configuration of gas heat exchangers (GGHs) to recover waste heat. This not only leads to high system investment and large footprint but also significantly increases fan energy consumption and operating costs. Especially under the current trend of energy conservation and carbon reduction, supplementary heating or the configuration of GGHs consumes a large amount of fuel and electricity, increasing carbon emission pressure. Furthermore, heat exchange equipment such as GGHs are prone to blockage, corrosion, and leakage, increasing system failure rates and maintenance difficulty, and reducing the stability and reliability of the flue gas treatment system.

[0003] Although existing low-temperature denitrification technologies can operate at lower temperatures, most of them do not fully utilize the reaction heat of the flue gas components themselves and still rely on external heat sources or complex heat exchange systems, making it difficult to achieve low energy consumption and self-balancing operation.

[0004] The removal of CO from flue gas during catalytic oxidation releases a large amount of heat, with each 1000 mg / m³ of CO removed generating heat. 3 CO can raise the flue gas temperature by about 6-7°C. However, in current technology, this heat is not directly used to provide the required temperature rise for the denitrification unit, resulting in energy waste. In addition, CO catalytic oxidation catalysts are highly sensitive to SO2 and moisture in the flue gas, and are easily poisoned and deactivated due to increased moisture and SO2 content. However, the poisoned catalyst can regain its activity after high-temperature regeneration.

[0005] Chinese patent application CN118987964A discloses a combined desulfurization, carbon monoxide removal, and denitrification device. It employs medium-high temperature denitrification and utilizes a supplementary heating system based on activated coke regeneration to supplement the heat for both CO removal and denitrification processes. It also includes a gas-cooled gas turbine (GGH) for heat exchange, but does not consider the online regeneration of the CO removal catalyst.

[0006] Chinese patent CN222694429U discloses a device for removing CO before ammonia injection in sintering flue gas denitrification. This patent also requires the use of a gas heat exchanger (GGH) and the installation of a supplementary heating system for temperature rise, and does not consider the operation of the CO removal catalyst under regeneration conditions.

[0007] Chinese patent application CN118416690A discloses a CO removal system and method for sintering flue gas. It employs a semi-dry desulfurization process, where the desulfurized flue gas undergoes CO removal and SCR denitrification sequentially after passing through a gas-heat exchanger (GGH). While this method utilizes the heat generated during CO removal, it requires CO removal temperatures greater than 180℃ and denitrification temperatures greater than 200℃. However, the temperature of the flue gas after semi-dry desulfurization is typically below 100℃, thus requiring a large amount of fuel for supplemental heating. Furthermore, in actual production, the SO2 content after semi-dry desulfurization is generally greater than 30 mg / m³. 3 Furthermore, the semi-dry process increases the moisture content in the flue gas, which seriously affects the service life of the CO removal catalyst.

[0008] Chinese patent application CN112403232A discloses a process and apparatus for synergistic purification of multiple pollutants in flue gas. It employs ammonia desulfurization, followed by a selective catalytic reduction (SCR), and then CO removal, or an additional first-stage SCR. This method requires high reaction temperatures, and the CO removal step is placed after the SCR or between two SCR stages, failing to effectively utilize the heat generated during CO removal. Furthermore, the CO removal catalyst cannot be regenerated online. In addition, this scheme includes a gas-cooled gas collector (GGH), resulting in a high system failure rate.

[0009] In summary, existing technologies for treating multiple pollutants in flue gas generally suffer from drawbacks such as complex processes, high investment, high energy consumption, and the need for external heating or the installation of a gas-fired heating system (GGH), making it difficult to simultaneously meet the synergistic requirements of efficient desulfurization, denitrification, CO removal, and energy conservation and emission reduction. Summary of the Invention

[0010] To address the problems of existing flue gas co-treatment systems requiring external heating, GGH heat exchange, and insufficient utilization of reaction heat, this invention provides a flue gas desulfurization, CO removal, and denitrification co-treatment system and its control method. By sequentially installing a temperature control device, an activated carbon desulfurization and denitrification device, a low-temperature CO removal device, and an ultra-low-temperature denitrification device along the flue gas flow direction, and pre-positioning activated carbon desulfurization to protect the CO removal catalyst, the system utilizes the reaction heat of desulfurization and CO removal for self-sustaining temperature rise in denitrification, eliminating the need for a GGH or external heating. Combined with staged ammonia injection and co-control, this system achieves efficient, energy-saving, and stable co-treatment of multiple pollutants.

[0011] The technical solution adopted by this invention to solve its technical problem is as follows: A flue gas desulfurization, CO denitrification, and denitrification synergistic treatment system includes a temperature control device, an activated carbon desulfurization and denitrification device, a low-temperature CO denitrification device, an ultra-low temperature denitrification device, and a chimney, which are sequentially connected through a flue along the flue gas flow direction; it also includes: A fan, connected in series in the flue gas flow duct, is used to provide power for the flow of flue gas; A section of ammonia injection control device is connected to the reactor inside the activated carbon desulfurization and denitrification unit via a pipeline; The two-stage ammonia injection control device is connected to the upstream flue of the ultra-low temperature denitrification unit via a pipeline; The regeneration waste gas pipeline of the low-temperature CO removal device is connected to the upstream flue of the temperature control device; A continuous flue gas emission monitoring device is installed between the temperature control device and the activated carbon desulfurization and denitrification device, between the activated carbon desulfurization and denitrification device and the low temperature CO removal device, between the low temperature CO removal device and the ultra-low temperature denitrification device, and on the chimney. It also includes a coordination controller, which is connected to the signals of each continuous flue gas emission monitoring unit, the first-stage ammonia injection control device, the second-stage ammonia injection control device, the temperature control device, the activated carbon desulfurization and denitrification device, the low-temperature CO removal device, and the ultra-low temperature denitrification device, respectively, and is used to coordinately control flue gas emissions based on the measurement values ​​of the continuous flue gas emission monitoring unit.

[0012] Furthermore, the activated carbon desulfurization and denitrification device is equipped with at least one set of activated carbon desulfurization and denitrification reactors; the low-temperature deCO device is equipped with at least two sets of low-temperature deCO reactors, used to switch one set of low-temperature deCO reactors between operating and regeneration states, and the low-temperature deCO reactors use low-temperature deCO catalysts with an activity temperature range of 100~200℃; the ultra-low temperature denitrification device is equipped with at least one set of denitrification reactors, each set of denitrification reactors is equipped with at least two layers of ultra-low temperature denitrification catalysts, and the ultra-low temperature denitrification catalysts have an activity temperature range of 120~200℃.

[0013] Furthermore, the temperature control device employs either a cooling air mixing method or a flue gas cooler to limit the maximum temperature of the flue gas entering the activated carbon desulfurization and denitrification unit. When the cooling air mixing method is used to control the temperature, the temperature is adjusted by regulating the opening of the cooling air mixing valve. When a flue gas cooler is used, the temperature is adjusted by regulating the flow rate of the cooling medium.

[0014] Furthermore, the ammonia injection control device includes a hot air duct and an ammonia duct connected to the hot air duct. The ammonia duct is equipped with an ammonia flow meter and an ammonia flow regulating valve. Both the ammonia flow meter and the ammonia flow regulating valve are connected to the coordinating controller for signal connection, and are used to adjust the opening of the ammonia flow regulating valve to make the ammonia injection flow reach the set value. The two-stage ammonia injection control device includes a two-stage hot air duct and a two-stage ammonia duct that connects to the two-stage hot air duct. The two-stage ammonia duct is equipped with a two-stage ammonia flow meter and a two-stage ammonia flow regulating valve. Both the two-stage ammonia flow meter and the two-stage ammonia flow regulating valve are connected to the coordinating controller for signal connection. They are used to adjust the opening of the two-stage ammonia flow regulating valve to make the two-stage ammonia injection flow reach the set value.

[0015] Furthermore, the variables measured by each continuous emission monitoring agency include: flue gas flow rate, flue gas pressure, flue gas temperature, SO2 content, NOx content, particulate matter content, CO content, NH3 content, and moisture content.

[0016] This application also provides a control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system. Based on the above system implementation, the method includes: Inlet flue gas temperature control: Based on the preset upper limit of the inlet flue gas temperature of the activated carbon desulfurization and denitrification device, the temperature control device is used to regulate the temperature of the flue gas entering the activated carbon desulfurization and denitrification device. Low-temperature CO removal unit regeneration control: A combination of timed regeneration and forced regeneration is used to perform regeneration switching regulation on the low-temperature CO removal reactor in the low-temperature CO removal unit; Primary ammonia injection control: Calculate and adjust the primary ammonia injection rate based on the inlet flue gas parameters of the activated carbon desulfurization and denitrification unit and the preset denitrification efficiency; Secondary ammonia injection control: Calculate and adjust the secondary ammonia injection rate based on the inlet flue gas parameters of the ultra-low temperature denitrification unit, the flue gas emission parameters of the chimney, and environmental emission requirements; All of the above adjustments are performed through the coordination controller.

[0017] Furthermore, the inlet flue gas temperature control specifically involves setting an upper limit value Ts1 for the inlet flue gas temperature of the activated carbon desulfurization and denitrification device. When the temperature T1 measured by the CEMS1 continuous emission monitoring mechanism for flue gas before desulfurization, which is set between the temperature control device and the activated carbon desulfurization and denitrification device, exceeds Ts1, the co-controller starts the temperature control device for cooling. The value of Ts1 is in the range of 140~160℃.

[0018] Furthermore, in the regeneration control of the low-temperature CO removal device: during timed regeneration, a regeneration cycle Tims1 is set. When the low-temperature CO removal operation time reaches the regeneration cycle Tims1, the coordinating controller controls each group of low-temperature CO removal reactors to regenerate sequentially. The trigger condition for forced regeneration is: when the CO removal efficiency of the low-temperature CO removal unit is lower than the set value E. COS1 At that time, or the CO concentration C4 measured by the CEMS4 continuous emission monitoring system installed on the chimney. CO When the emission concentration exceeds the environmentally permissible level, the coordinating controller controls each group of low-temperature CO removal reactors to undergo forced regeneration in sequence.

[0019] Furthermore, the primary ammonia injection control specifically involves setting the denitrification efficiency E of the activated carbon desulfurization and denitrification device. NOxs1 According to the inlet flue gas flow rate V1 and NOx content C1 measured by the CEMS1 continuous emission monitoring system for flue gas before desulfurization, which is set up between the temperature control device and the activated carbon desulfurization and denitrification device;NOx Moisture content C1 H2O And the denitrification efficiency setpoint E of the activated carbon desulfurization and denitrification device. NOxs1 And the excess coefficient k1, the first-stage ammonia injection setpoint V1 is calculated using the following formula. NH3 : V1 NH3 =k1×V1×C1 NOx ×(1-C1 H2O )×10 -6 ×22.4 / 46; The ammonia flow regulating valve of the first stage is adjusted by the co-controller so that the flow rate measured by the first stage ammonia flow meter is equal to the set value V1 of the first stage ammonia injection. NH3 .

[0020] Furthermore, the secondary ammonia injection control specifically involves: based on the continuous emission monitoring system (CEMS3) for pre-denitrification flue gas, which is installed between the low-temperature CO removal unit and the ultra-low-temperature denitrification unit, measuring the inlet flue gas flow rate V3 and NOx content C3 at the denitrification inlet. NOx Moisture content C3 H2O Ammonia content C3 NH3 And the chimney emission flow rate V4 and NOx content C4 measured by the CEMS4 continuous emission monitoring system installed on the chimney. NOx Moisture content C4 H2O And environmental protection requirements for NOx emission concentration C NOx Environmental protection requirements for ammonia emission escape C NH3 The secondary ammonia injection rate setpoint V2 is calculated using the following formula. NH3 : V2 NH3 =[V3×C3 NOx ×(1-C3 H2O )-V4×C NOx ×(1-C4 H2O )]×10 -6 ×22.4 / 46-[V3×C3 NH3 -V4×C NH3 ]×10 -6 ×22.4 / 17; The secondary ammonia flow regulating valve is adjusted by the co-controller so that the flow rate measured by the secondary ammonia flow meter is equal to the secondary ammonia injection rate set value V2. NH3 .

[0021] The beneficial effects of this invention include: This invention sequentially arranges a temperature control device, an activated carbon desulfurization and denitrification device, a low-temperature CO removal device, and an ultra-low temperature denitrification device along the flue gas flow direction, and coordinates with a staged ammonia injection control and a collaborative controller. The pre-installed activated carbon desulfurization and denitrification device efficiently removes SO2 from the flue gas, effectively protecting the subsequent low-temperature CO removal catalyst from SO2 and moisture poisoning and deactivation, extending the catalyst's lifespan. Simultaneously, as a primary denitrification stage, it reduces the load on the subsequent ultra-low temperature denitrification. By placing the low-temperature CO removal device between the activated carbon desulfurization and denitrification device and the ultra-low temperature denitrification device, the reaction heat released during the activated carbon desulfurization and denitrification process and the CO catalytic oxidation process can be fully utilized. This allows the flue gas temperature to naturally rise to the active temperature range required for ultra-low temperature denitrification after desulfurization and CO removal, achieving self-heating balance operation without external heating devices or GGH flue gas heat exchangers. This significantly reduces system investment costs, floor space, fan energy consumption, and fuel consumption, while avoiding system failures and maintenance difficulties caused by GGH equipment blockage, corrosion, and leakage.

[0022] In addition, by setting up at least two sets of low-temperature CO removal reactors and configuring regeneration waste gas pipelines to connect to the upstream of the temperature control device, one set of low-temperature CO removal reactors can be switched between operating and regeneration states according to control needs. This enables online regeneration of the deactivated CO removal catalyst without shutting down the system, and the regeneration waste gas is returned to the front end of the system for recycling, ensuring continuous and stable operation of the system without secondary pollution.

[0023] By setting up multiple continuous emission monitoring devices for flue gas and connecting them to the coordinated controller, the concentration changes of pollutants such as SO2, NOx, CO, and NH3 in the flue gas can be monitored in real time. Based on this, the cooling intensity of the temperature control device, the amount of ammonia injected in stages, and the regeneration timing of the CO removal reactor can be automatically adjusted to achieve coordinated control of the entire process. Under the premise of ensuring that SO2, NOx, CO, and ammonia escape all meet the environmental emission standards, the system energy consumption and operating costs are reduced to the minimum.

[0024] In summary, this invention provides a highly efficient and energy-saving solution for the synergistic treatment of multiple pollutants in flue gas that requires no external heating, no GGH, allows for online regeneration of the CO removal catalyst, and can self-maintain the reaction temperature, thus offering significant economic and environmental benefits. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0026] In the diagram: 1-Activated carbon desulfurization and denitrification device, 2-Low temperature CO removal device, 3-Ultra-low temperature denitrification device, 4-Chimney, 5-Regenerated waste gas pipeline, 6-Temperature control device, 7-First stage ammonia injection control device, 8-Second stage ammonia injection control device, 9-Coordination controller, 10-Fan, 201-Regenerated waste gas outlet valve, 202-Flue gas inlet shut-off valve, 203-Regenerated hot air inlet valve, 204-Flue gas outlet shut-off valve, 701-First stage ammonia flow meter, 702-First stage ammonia flow regulating valve, 801-Second stage ammonia flow meter, 802-Second stage ammonia flow regulating valve, CEMS1-Continuous emission monitoring mechanism for flue gas before desulfurization, CEMS2-Continuous emission monitoring mechanism for flue gas before CO removal, CEMS3-Continuous emission monitoring mechanism for flue gas before denitrification, CEMS4-Continuous emission monitoring mechanism for flue gas from the chimney. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0028] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1: A flue gas desulfurization, deCO removal, and denitrification synergistic treatment system, referenced Figure 1 It includes a temperature control device 6, an activated carbon desulfurization and denitrification device 1, a low-temperature CO removal device 2, an ultra-low temperature denitrification device 3, and a chimney 4, which are connected sequentially through the flue along the flue flow direction. A section of ammonia injection control device 7 is connected to the reactor inside the activated carbon desulfurization and denitrification device 1 via a pipeline; The second-stage ammonia injection control device 8 is connected to the upstream flue of the ultra-low temperature denitrification device 3 via a pipeline; The regeneration exhaust gas pipeline 5 of the low-temperature CO removal device 2 is connected to the upstream flue of the temperature control device 6; The fan 10 is connected in series in the flue gas flow duct to provide power for flue gas flow. The fan 10 can be set before the activated carbon desulfurization and denitrification device 1, or between the activated carbon desulfurization and denitrification device 1 and the low temperature deCO removal device 2, or between the low temperature deCO removal device 2 and the ultra-low temperature denitrification device 3, or between the ultra-low temperature denitrification device 3 and the chimney 4. Preferably, in this embodiment, the fan 10 is set between the low temperature deCO removal device 2 and the ultra-low temperature denitrification device 3, and is located downstream of the access point of the second-stage ammonia injection control device 8.

[0030] A continuous emission monitoring system (CEMS1) for flue gas before desulfurization is provided between the temperature control device 6 and the activated carbon desulfurization and denitrification device 1; a continuous emission monitoring system for flue gas before denitrification (CEMS2) is provided between the activated carbon desulfurization and denitrification device 1 and the low temperature deCO removal device 2; a continuous emission monitoring system for flue gas before denitrification (CEMS3) is provided between the low temperature deCO removal device 2 and the ultra-low temperature denitrification device 3; and a continuous emission monitoring system for flue gas before denitrification (CEMS4) is provided in the upper part of the chimney 4.

[0031] The collaborative controller 9 is connected to each continuous flue gas emission monitoring unit, the first-stage ammonia injection control device 7, the second-stage ammonia injection control device 8, the temperature control device 6, the activated carbon desulfurization and denitrification device 1, the low-temperature CO removal device 2, and the ultra-low temperature denitrification device 3, respectively, and is used to collaboratively control the emission of each pollutant in the flue gas according to the measurement values ​​of the continuous flue gas emission monitoring unit.

[0032] The collaborative controller 9 can be controlled by a PLC or a DCS. The collaborative controller 9 can be set up independently or share the same controller system with the activated carbon desulfurization and denitrification device 1, the low temperature CO removal device 2, and the ultra-low temperature denitrification device 3.

[0033] Preferably, a heat recovery device can be installed between the ultra-low temperature denitrification device 3 and the chimney 4 as needed. The heat recovery device includes, but is not limited to, a waste heat boiler, a heat exchanger, or a heat exchange tube bundle.

[0034] Temperature control device 6 uses either a cooling air mixing method or a flue gas cooler to limit the maximum temperature of the flue gas at the inlet of activated carbon desulfurization and denitrification device 1. When the temperature is controlled by mixing cooling air, the temperature is adjusted by regulating the opening of the cooling air mixing valve. When a flue gas cooler is used, the temperature is adjusted by regulating the flow rate of the cooling medium, which is air or circulating cooling water.

[0035] The activated carbon desulfurization and denitrification device 1 is equipped with at least one set of activated carbon desulfurization and denitrification reactors; The low-temperature CO removal device 2 is equipped with at least two sets of low-temperature CO removal reactors. Each set of low-temperature CO removal reactors is equipped with shut-off valves at the flue gas inlet, flue gas outlet, regeneration hot air inlet, and regeneration waste gas outlet, allowing one set of low-temperature CO removal reactors to be switched between operating and regeneration states as needed. The low-temperature CO removal catalyst used in the low-temperature CO removal reactor has an activity temperature range of 100~200℃, preferably 140~160℃.

[0036] The ultra-low temperature denitrification device 3 is equipped with at least one set of denitrification reactors, and each set of denitrification reactors is equipped with at least two layers of ultra-low temperature denitrification catalysts. The activity temperature range of the ultra-low temperature denitrification catalysts is 120~200℃.

[0037] The ammonia injection control device 7 includes a hot air duct and an ammonia duct connected to the hot air duct. The ammonia duct is equipped with an ammonia flow meter 701 and an ammonia flow regulating valve 702. Both the ammonia flow meter 701 and the ammonia flow regulating valve 702 are connected to the coordinating controller 9 for signal connection. The ammonia injection flow rate is adjusted to a set value by adjusting the opening of the ammonia flow regulating valve 702. The mixed ammonia-air gas is injected into the upper half of the flue gas inlet channel of the activated carbon desulfurization and denitrification reactor, or into the rear layer of the activated carbon bed.

[0038] The two-stage ammonia injection control device 8 includes a two-stage hot air duct and a two-stage ammonia duct connected to the two-stage hot air duct. The two-stage ammonia duct is equipped with a two-stage ammonia flow meter 801 and a two-stage ammonia flow regulating valve 802. Both the two-stage ammonia flow meter 801 and the two-stage ammonia flow regulating valve 802 are connected to the coordinating controller 9 for signaling, and are used to adjust the opening of the two-stage ammonia flow regulating valve 802 to make the two-stage ammonia injection flow reach the set value.

[0039] The variables measured by each continuous emission monitoring station (CEMS1~4) include: flue gas flow rate, flue gas pressure, flue gas temperature, SO2 content, NOx content, particulate matter content, CO content, NH3 content, and moisture content. It should be noted that each CEMS1~4 uses existing online flue gas monitoring equipment in the field, which integrates flue gas flow sensor, flue gas pressure sensor, temperature sensor, sulfur dioxide sensor, nitrogen oxide sensor, particulate matter sensor, carbon monoxide sensor, ammonia sensor, and moisture sensor. It can detect and output monitoring parameters such as flue gas flow rate, flue gas pressure, flue gas temperature, SO2 content, NOx content, particulate matter content, CO content, NH3 content, and moisture content in real time. The relevant detection principles and structures are existing technologies and will not be elaborated here.

[0040] Example 2: A control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system, based on the system described in Example 1, the method comprising: (1) Inlet flue gas temperature control: Set the upper limit value Ts1 for the inlet flue gas temperature of the activated carbon desulfurization and denitrification device 1. When the temperature T1 measured by the continuous emission monitoring mechanism CEMS1 before desulfurization exceeds Ts1, the co-controller 9 starts the temperature control device 6 for cooling; the value of Ts1 is in the range of 140~160℃. Preferably, when the SO2 content C1 measured by the continuous emission monitoring mechanism CEMS1 before desulfurization exceeds Ts1, the temperature control device 6 starts the temperature control device 6 for cooling. SO2 Greater than 1200mg / m 3 At that time, Ts1 = 145℃; when C1 SO2 Less than or equal to 1200 mg / m 3 And greater than 800 mg / m 3 When Ts1 = 150℃; when C1 SO2Less than or equal to 800 mg / m 3 At that time, Ts1 = 155℃.

[0041] (2) Regeneration control of low-temperature CO removal device 2: The control adopts a combination of timed regeneration and forced regeneration. During timed regeneration, the regeneration cycle Tims1 is set. When the low-temperature CO removal operation time reaches the regeneration cycle Tims1, the coordinating controller 9 controls each group of low-temperature CO removal reactors to regenerate in sequence; the regeneration cycle Tims1 is set within the range of 24~360h.

[0042] The trigger condition for forced regeneration is: when the CO removal efficiency of the low-temperature CO removal unit 2 is lower than the set value E. COS1 At that time, or the CO concentration C4 measured by the CEMS4 continuous emission monitoring agency for chimney flue gas. CO When the emission concentration exceeds the environmentally permissible limit, the coordinating controller 9 controls each group of low-temperature CO removal reactors to undergo forced regeneration sequentially. The CO removal efficiency setpoint E of the low-temperature CO removal unit 2 is... COS1 The value range is 60% to 90%.

[0043] (3) Primary ammonia injection control: Set the denitrification efficiency E of the activated carbon desulfurization and denitrification device (1). NOxs1 The value ranges from 20% to 40%. Preferably, the SO2 content C1 measured by the CEMS1 continuous emission monitoring system before desulfurization is... SO2 Greater than 1200mg / m 3 At that time, E NOxs1 =20%; when C1 SO2 Less than or equal to 1200 mg / m 3 And greater than 800 mg / m 3 At that time, E NOxs1 =30%; when C1 SO2 Less than or equal to 800 mg / m 3 At that time, E NOxs1 =40%.

[0044] According to the inlet flue gas flow rate V1 (unit Nm) measured by CEMS1, the continuous emission monitoring agency for flue gas before desulfurization. 3 / h), NOx content C1 NOx (Unit: mg / m³) 3 Moisture content C1 H2O (Unit: V%), and the denitrification efficiency setpoint E of activated carbon desulfurization and denitrification device 1. NOxs1 And the excess coefficient k1, the first-stage ammonia injection setpoint V1 is calculated using the following formula. NH3 (unit Nm) 3 / h): V1 NH3 =k1×V1×C1 NOx ×(1-C1H2O )×10 -6 ×22.4 / 46; The excess system k1 ranges from 1.2 to 3. Preferably, when the SO2 content C1 measured by CEMS1... SO2 Greater than 1200mg / m 3 When k1 = 2.5; when C1 SO2 Less than or equal to 1200 mg / m 3 And greater than 800 mg / m 3 When, k1=2; when C1 SO2 Less than or equal to 800 mg / m 3 At that time, k1=1.5.

[0045] The ammonia flow regulating valve 702 is adjusted by the co-controller 9 so that the flow rate measured by the ammonia flow meter 701 is equal to the set value V1 of the first-stage ammonia injection. NH3 .

[0046] (4) Secondary ammonia injection control: Based on the flue gas flow rate V3 (unit Nm³) at the denitrification inlet measured by the CEMS3 continuous emission monitoring system before denitrification. 3 / h), NOx content C3 NOx (Unit: mg / m³) 3 Moisture content C3 H2O (Unit: V%), Ammonia content (C3) NH3 And the chimney emission flow rate V4 (unit Nm³) measured by CEMS4, a continuous emission monitoring organization for chimneys. 3 / h), NOx content C4 NOx (Unit: mg / m³) 3 Moisture content C4 H2O (Unit: V%), and environmental protection requirements for NOx emission concentration C NOx (Unit: mg / m³) 3 Environmental protection requirements for ammonia escape emissions (C) NH3 (Unit: mg / m³) 3 The secondary ammonia injection rate setpoint V2 is calculated using the following formula. NH3 (unit Nm) 3 / h): V2 NH3 =[V3×C3 NOx ×(1-C3 H2O )-V4×C NOx ×(1-C4 H2O )]×10 -6 ×22.4 / 46-[V3×C3 NH3 -V4×C NH3 ]×10 -6 ×22.4 / 17; The secondary ammonia flow regulating valve 802 is adjusted by the co-controller 9 so that the flow rate measured by the secondary ammonia flow meter 801 is equal to the secondary ammonia injection rate set value V2. NH3 .

[0047] Based on the above solution, the present invention has the following advantages: (1) Activated carbon desulfurization and denitrification is used as a pre-unit to efficiently remove SO2 and protect the subsequent deCO catalyst, and as a first-stage denitrification unit to reduce the load of subsequent ultra-low temperature denitrification.

[0048] (2) It makes full use of the heat generated by physical adsorption and chemical reaction of activated carbon desulfurization, denitrification and low temperature CO removal, without the need for a heat exchanger or GGH, forming a self-heating synergy of "desulfurization-denitrification-denitrification".

[0049] (3) The entire process does not require additional flue gas reheating or GGH, which simplifies the process and reduces related equipment, reduces system resistance and fuel consumption, and achieves the dual benefits of energy saving and carbon reduction.

[0050] Application example: Taking the comprehensive treatment of flue gas from the sintering machine head of a steel plant as an example, the temperature of the flue gas after dust removal at the machine head is 140℃, and the flow rate is 800,000 Nm³. 3 / h, SO2 content 1000mg / m 3 NOx content 300mg / m³ 3 CO content 8000 mg / m³ 3 It contains 10% water (volume). Local environmental emission standards require SO2 content to be less than 35 mg / m³. 3 NOx content less than 50 mg / m³ 3 CO content less than 2800 mg / m³ 3 Ammonia content less than 2.5 mg / m³ 3 .

[0051] After dust removal, the flue gas passes through temperature control device 6 and then enters activated carbon desulfurization and denitrification unit 1. The main function of the temperature control device is to limit the maximum temperature of the flue gas entering activated carbon desulfurization and denitrification unit 1, preventing excessively high temperatures from causing safety hazards. Simultaneously, while ensuring safety, it maintains a relatively high flue gas temperature to provide suitable temperatures for subsequent CO removal and denitrification processes. When the flue gas temperature is below the set value, temperature control device 6 will not activate. When an abnormality in upstream production causes the flue gas temperature to exceed the set value, temperature control device 6 will activate to ensure the safety of activated carbon desulfurization and denitrification unit 1. This application example uses a cooling method incorporating cold air, with a cold air regulating valve installed. The maximum temperature of the flue gas entering the system is controlled by adjusting the opening of the cold air regulating valve.

[0052] The activated carbon desulfurization and denitrification unit 1 is equipped with three sets of desulfurization and denitrification reactors connected in parallel, employing a cross-flow stratified bed design. Under the control of the co-controller 9, the first-stage ammonia injection control device 7 injects an ammonia-air mixture into the upper half of the inlet and the rear of the activated carbon bed of the activated carbon desulfurization and denitrification unit 1. Part of the injected ammonia completes the first-stage denitrification, while the other part reacts with SO2 to assist in desulfurization. If the denitrification rate of the activated carbon desulfurization and denitrification unit 1 is set at 30%, then the NOx content in the flue gas after passing through the activated carbon desulfurization and denitrification unit 1 will be 210 mg / m³. 3 SO2 content dropped to 10 mg / m³ 3 the following.

[0053] Since the activated carbon desulfurization and denitrification process is exothermic, after desulfurization by activated carbon desulfurization and denitrification unit 1 and first-stage denitrification, the flue gas temperature rises from the original 140℃ to 145℃, and then enters the low-temperature CO removal unit 2. The low-temperature CO removal unit 2 consists of three sets of low-temperature CO removal reactors, each equipped with a regeneration waste gas outlet valve 201, a flue gas inlet shut-off valve 202, a regeneration hot air inlet valve 203, and a flue gas outlet shut-off valve 204, which can be switched for regeneration according to the requirements of the co-controller 9. The activity temperature range of the low-temperature CO removal catalyst is 140~160℃, and the CO removal efficiency is 70% at a flue gas temperature of 145℃. After CO removal, the CO content in the flue gas is 2400 mg / m³. 3 The CO removal chemical reaction causes the flue gas temperature to rise by 37°C, from 145°C to 182°C. The CO-removed flue gas, after mixing with the ammonia injection mixture from the second stage, enters the cryogenic denitrification unit 3 via fan 10. In this application example, fan 10 is positioned between the second-stage ammonia injection control device 8 and the cryogenic denitrification unit 3, ensuring a more uniform mixing of the injected ammonia and flue gas after mixing.

[0054] The ultra-low temperature denitrification unit 3 is equipped with two layers of ultra-low temperature denitrification catalysts. The catalyst activity temperature range is 120~200℃, and the denitrification efficiency is 88% at 182℃. The NOx content in the flue gas after denitrification is 25.2 mg / m³. 3 .

[0055] The SO2 content in the flue gas emitted from the chimney after treatment by the flue gas desulfurization, deCO removal and denitrification combined treatment system is 10 mg / m³. 3 NOx content 25.2 mg / m³ 3 CO content 2400mg / m³ 3 All of them meet the requirements of environmental protection emission standards.

[0056] Collaborative control methods: High-limit control of flue gas inlet temperature in activated carbon desulfurization and denitrification unit: Due to the SO2 content in the raw flue gas being less than or equal to 1200 mg / m³ 3 And greater than 800 mg / m 3The maximum temperature limit setting is Ts1=150℃. When the temperature of the raw flue gas is higher than the set value, the temperature control device 6 is activated to adjust the opening of the cold air regulating valve to prevent the flue gas temperature from being too high and causing a safety accident in the activated carbon desulfurization and denitrification device 1.

[0057] Low-temperature CO removal unit 2 regeneration control: The timed regeneration time is set to 48 hours. When the running time equals the set value, regeneration operation is performed sequentially on each group of low-temperature CO removal reactors. The exhaust gas generated during regeneration is returned to the temperature control device 6. Forced regeneration: The CO removal efficiency is set to 65%. When the CO removal efficiency is lower than the set value, forced regeneration operation is performed sequentially on each group of low-temperature CO removal reactors. Additionally, the CO concentration measured by the continuous emission monitoring system (CEMS4) is checked against environmental protection requirements (2800 mg / m³). 3 If the time limit is exceeded, forced regeneration will be performed.

[0058] Ammonia injection control device 7: Ammonia injection quantity control: Sets the denitrification efficiency setpoint E of activated carbon desulfurization and denitrification device 1. NOxs1 =30%, calculate the first-stage ammonia injection rate setpoint V1 NH3 =63Nm 3 / h. Based on the ammonia flow rate detected by the ammonia flow meter 701, the opening of the ammonia flow regulating valve 702 is adjusted to make the ammonia injection rate equal to the set value V1. NH3 .

[0059] The second-stage ammonia injection control device 8 controls the ammonia injection quantity: after the first stage of denitrification in the activated carbon desulfurization and denitrification device, the NOx content (C3) before entering the ultra-low temperature denitrification device 3 is controlled. NOx =210mg / m 3 Because the ammonia injected by the ammonia injection control device 7 is excessive, most of the excess ammonia reacts with SO2 to assist in desulfurization and is consumed, while a small amount enters the flue gas. According to the CEMS3 continuous emission monitoring system for flue gas before denitrification, the ammonia content is 5 mg / m³. 3 Environmental regulations permit an ammonia emission concentration of 2.5 mg / m³. 3 Therefore, the secondary ammonia injection rate setpoint V2 is calculated. NH3 =53.5Nm 3 / h. Based on the ammonia flow rate of the first stage detected by the second-stage ammonia flow meter 801, the opening of the second-stage ammonia flow regulating valve 802 is adjusted to make the ammonia injection rate of the second stage equal to the set value V2. NH3 .

[0060] The CEMS2 continuous emission monitoring system for flue gas before CO removal is used to monitor parameters such as temperature, SO2 content, CO content, NOx content, moisture content, and flue gas flow rate of flue gas after treatment by the activated carbon desulfurization and denitrification device in real time. This allows for real-time monitoring of the operating conditions of the flue gas after desulfurization, assessment of the operating status and desulfurization and denitrification effect of the activated carbon desulfurization and denitrification device, and provides operating condition data for the stable operation of the low-temperature CO removal device. It also facilitates system operation monitoring, fault diagnosis, and operation and maintenance management, ensuring the safe, stable, and efficient operation of the collaborative treatment system throughout the entire process.

[0061] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A flue gas desulfurization, CO removal, and denitrification synergistic treatment system, characterized in that, It includes a temperature control device (6), an activated carbon desulfurization and denitrification device (1), a low-temperature CO removal device (2), an ultra-low temperature denitrification device (3), and a chimney (4) connected sequentially through the flue along the flue gas flow direction; it also includes: A fan (10) is connected in series in the flue gas flow duct to provide power for flue gas flow; A section of ammonia injection control device (7) is connected to the reactor inside the activated carbon desulfurization and denitrification device (1) via a pipeline; The second-stage ammonia injection control device (8) is connected to the upstream flue of the ultra-low temperature denitrification device (3) via a pipeline; The regeneration exhaust gas pipeline (5) of the low-temperature CO removal device (2) is connected to the upstream flue of the temperature control device (6); A continuous flue gas emission monitoring mechanism is installed between the temperature control device (6) and the activated carbon desulfurization and denitrification device (1), between the activated carbon desulfurization and denitrification device (1) and the low temperature deCO device (2), between the low temperature deCO device (2) and the ultra-low temperature denitrification device (3), and on the chimney (4). It also includes a collaborative controller (9), which is connected to each continuous flue gas emission monitoring unit, a first-stage ammonia injection control device (7), a second-stage ammonia injection control device (8), a temperature control device (6), an activated carbon desulfurization and denitrification device (1), a low-temperature deCO removal device (2), and an ultra-low temperature denitrification device (3) to coordinately control flue gas emissions based on the measured values ​​of the continuous flue gas emission monitoring unit.

2. The flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 1, characterized in that, The activated carbon desulfurization and denitrification device (1) is equipped with at least one set of activated carbon desulfurization and denitrification reactors; the low-temperature deCO device (2) is equipped with at least two sets of low-temperature deCO reactors, which are used to switch one set of low-temperature deCO reactors between the operating state and the regeneration state, and the low-temperature deCO reactors use low-temperature deCO catalysts with an activity temperature range of 100~200℃; the ultra-low temperature denitrification device (3) is equipped with at least one set of denitrification reactors, and each set of denitrification reactors is equipped with at least two layers of ultra-low temperature denitrification catalysts, and the ultra-low temperature denitrification catalysts have an activity temperature range of 120~200℃.

3. The flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 2, characterized in that, The temperature control device (6) adopts a mixed cold air method or a flue gas cooler to limit the maximum temperature of the inlet flue gas of the activated carbon desulfurization and denitrification device (1); when the mixed cold air method is used to control the temperature, the temperature is adjusted by adjusting the opening of the mixed cold air valve; when a flue gas cooler is used, the temperature is adjusted by adjusting the flow rate of the cooling medium.

4. The flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 2, characterized in that, A single-stage ammonia injection control device (7) includes a hot air duct and an ammonia duct connected to the hot air duct. An ammonia flow meter (701) and an ammonia flow regulating valve (702) are provided on the ammonia duct. Both the ammonia flow meter (701) and the ammonia flow regulating valve (702) are connected to the coordinating controller (9) for adjusting the opening of the ammonia flow regulating valve (702) to make the ammonia injection flow reach the set value. The two-stage ammonia injection control device (8) includes a two-stage hot air duct and a two-stage ammonia duct connected to the two-stage hot air duct. The two-stage ammonia duct is equipped with a two-stage ammonia flow meter (801) and a two-stage ammonia flow regulating valve (802). Both the two-stage ammonia flow meter (801) and the two-stage ammonia flow regulating valve (802) are connected to the coordinating controller (9) for adjusting the opening of the two-stage ammonia flow regulating valve (802) to make the two-stage ammonia injection flow reach the set value.

5. A flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to any one of claims 1-4, characterized in that, The variables measured by each continuous emission monitoring agency include: flue gas flow rate, flue gas pressure, flue gas temperature, SO2 content, NOx content, particulate matter content, CO content, NH3 content, and moisture content.

6. A control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system, implemented based on the system described in any one of claims 1-5, characterized in that, The method includes: Inlet flue gas temperature control: Based on the preset upper limit of the inlet flue gas temperature of the activated carbon desulfurization and denitrification device (1), the temperature control device (6) is used to adjust the temperature of the flue gas entering the activated carbon desulfurization and denitrification device (1). Low-temperature CO removal unit (2) regeneration control: The low-temperature CO removal reactor in the low-temperature CO removal unit (2) is regenerated by combining timed regeneration and forced regeneration. Primary ammonia injection control: Calculate and adjust the primary ammonia injection amount based on the inlet flue gas parameters and preset denitrification efficiency of the activated carbon desulfurization and denitrification device (1); Secondary ammonia injection control: Calculate and adjust the secondary ammonia injection amount based on the inlet flue gas parameters of the ultra-low temperature denitrification device (3), the emission flue gas parameters of the chimney (4), and environmental emission requirements; All of the above adjustments are performed through the coordination controller (9).

7. The control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 6, characterized in that, The specific control of the inlet flue gas temperature is as follows: set the upper limit value Ts1 of the inlet flue gas temperature of the activated carbon desulfurization and denitrification device (1). When the temperature T1 measured by the CEMS1 continuous monitoring mechanism for flue gas emissions before desulfurization set between the temperature control device (6) and the activated carbon desulfurization and denitrification device (1) exceeds Ts1, the coordinating controller (9) starts the temperature control device (6) for cooling. The value range of Ts1 is 140~160℃.

8. The control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 6, characterized in that, In the regeneration control of the low-temperature CO removal device (2): during timed regeneration, the regeneration cycle Tims1 is set. When the low-temperature CO removal running time reaches the regeneration cycle Tims1, the coordinating controller (9) controls each group of low-temperature CO removal reactors to regenerate sequentially. The trigger condition for forced regeneration is: when the CO removal efficiency of the low-temperature CO removal device (2) is lower than the set value E. COS1 At that time, or the CO concentration C4 measured by the CEMS4 continuous emission monitoring system installed on the chimney (4). CO When the emission concentration exceeds the environmentally permissible emission concentration, the coordinating controller (9) controls each group of low-temperature CO removal reactors to undergo forced regeneration in sequence.

9. The control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 6, characterized in that, The primary ammonia injection control specifically involves setting the denitrification efficiency E of the activated carbon desulfurization and denitrification device (1). NOxs1 According to the inlet flue gas flow rate V1 and NOx content C1 measured by the CEMS1 continuous emission monitoring system for flue gas before desulfurization set between the temperature control device (6) and the activated carbon desulfurization and denitrification device (1), NOx Moisture content C1 H2O And the denitrification efficiency setpoint E of the activated carbon desulfurization and denitrification device (1) NOxs1 And the excess coefficient k1, the first-stage ammonia injection setpoint V1 is calculated using the following formula. NH3 : V1 NH3 =k1×V1×C1 NOx ×(1-C1 H2O )×10 -6 ×22.4 / 46; The ammonia flow regulating valve (702) is adjusted by the coordinating controller (9) so that the flow rate measured by the ammonia flow meter (701) is equal to the set value V1 of the first-stage ammonia injection. NH3 .

10. The control method for a flue gas desulfurization, deCO removal, and denitrification synergistic treatment system according to claim 6, characterized in that, The secondary ammonia injection control specifically involves: based on the continuous emission monitoring system CEMS3 (CEMS3) for pre-denitrification flue gas, which is installed between the low-temperature CO removal device (2) and the ultra-low temperature denitrification device (3), measuring the inlet flue gas flow rate V3 and NOx content C3 at the denitrification inlet. NOx Moisture content C3 H2O Ammonia content C3 NH3 The flue gas flow rate V4 and NOx content C4 of the chimney emissions measured by the CEMS4 continuous emission monitoring system installed on the chimney (4) are also mentioned. NOx Moisture content C4 H2O And environmental protection requirements for NOx emission concentration C NOx Environmental protection requirements for ammonia emission escape C NH3 The secondary ammonia injection rate setpoint V2 is calculated using the following formula. NH3 : V2 NH3 =[V3×C3 NOx ×(1-C3 H2O )-V4×C NOx ×(1-C4 H2O )]×10 -6 ×22.4 / 46-[V3×C3 NH3 -V4×C NH3 ]×10 -6 ×22.4 / 17; The secondary ammonia flow regulating valve (802) is adjusted by the coordinating controller (9) so that the flow rate measured by the secondary ammonia flow meter (801) is equal to the secondary ammonia injection rate set value V2. NH3 .

Images