Intelligent joint control desulfurization oxidation air energy-saving control system based on compressed air

Abstract

The invention relates to the field of energy conservation and environmental protection, in particular to an intelligent joint control desulfurization oxidation air energy-saving control system based on compressed air, which comprises a fan, an oxidation air mother pipe, an absorption tower and a PLC (programmable logic controller) system, a fan outlet valve, a desuperheating water pipe, a pressure transmitter and a thermocouple are sequentially mounted on the oxidation air mother pipe from the fan to the absorption tower, a desuperheating water valve is mounted on the desuperheating water pipe, and the fan, the fan outlet valve, the pressure transmitter, the thermocouple and the desuperheating water valve are in electric signal connection with a PLC (programmable logic controller) system. A pipeline between a fan outlet valve on the oxidation air mother pipe and the desuperheating water pipe is connected to a compressed air pipe network through an alternative air supply pipeline, a compressed air primary regulating valve, a compressed air secondary regulating valve and a compressed air manual regulating valve are sequentially mounted on the alternative air supply pipeline, and the compressed air secondary regulating valve is in electric signal connection with a PLC (programmable logic controller) system.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and environmental protection, and in particular to an intelligent integrated control system for desulfurization and oxidation air based on compressed air. Background Technology

[0002] Traditional desulfurization tower oxidation air systems typically employ forced oxygen supply equipment using blowers (Roots blowers or centrifugal blowers, etc.). The blowers pressurize the air, treat it with desuperheating water, and then send it into the absorption tower to promote the oxidation reaction of the desulfurization tower slurry. While this design is mature and reliable, it suffers from high energy consumption, high noise levels, system complexity, and a large maintenance workload. Especially for small gas turbine units with low sulfur content (such as the Taiyuan Iron & Steel Group's 80MW gas turbine unit), the oxidation air volume requirement is relatively small, and traditional blower systems are often overpowered, resulting in low energy efficiency.

[0003] Existing improvements mostly focus on increasing the efficiency of the fans themselves, such as using variable frequency control, high-efficiency impellers, or magnetic levitation fans. However, these improvements do not deviate from the technical route of "dedicated fans for air supply," and are only partial optimizations, failing to integrate energy and streamline the structure at the system level. Furthermore, existing factory areas generally have compressed air pipeline networks, often resulting in a significant surplus of compressed air. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to effectively utilize the surplus compressed air in the compressed air pipeline network to supply air to the desulfurization tower, thereby reducing energy consumption and noise.

[0005] The technical solution adopted in this invention is: an intelligent joint control desulfurization oxidation air energy-saving control system based on compressed air, including a fan, an oxidation air main pipe, an absorption tower and a PLC system. The fan is connected to the absorption tower through the oxidation air main pipe. The oxidation air main pipe is installed sequentially from the fan to the absorption tower with a fan outlet valve (7), a desuperheating water pipe, a pressure transmitter (5) and a thermocouple (6). A desuperheating water valve (4) is installed on the desuperheating water pipe. The fan, the fan outlet valve (7), the pressure transmitter (5), the thermocouple (6) and the desuperheating water valve (4) are electrically connected to the PLC system. The pipeline between the fan outlet valve (7) and the desuperheating water pipe on the oxidation air main pipe is connected to the compressed air network through a substitute air supply pipeline. A compressed air primary regulating valve (1), a compressed air secondary regulating valve (2) and a compressed air manual regulating valve (3) are sequentially installed on the substitute air supply pipeline. The compressed air secondary regulating valve (2) is electrically connected to the PLC system. During use, when the amount of compressed air in the compressed air pipeline is sufficient to meet the desulfurization oxidation air demand, close the fan, fan outlet valve (7) and desuperheating water valve (4), open the primary compressed air regulating valve (1), secondary compressed air regulating valve (2) and manual compressed air regulating valve (3), and adjust the flow rate of compressed air entering the oxidation air main pipe to meet the air supply demand. When the amount of compressed air in the compressed air pipeline is insufficient to meet the desulfurization oxidation air demand, close the primary compressed air regulating valve (1), secondary compressed air regulating valve (2) and manual compressed air regulating valve (3), open the fan, fan outlet valve (7) and desuperheating water valve (4), and use the fan to supply air to meet the air supply demand.

[0006] The compressed air manual regulating valve (3) is a compressed air manual regulating gate valve. The alternative air supply duct is a DN50 pipe made of 316L stainless steel.

[0007] The primary compressed air regulating valve (1) is a manual regulating valve (isolation valve), the secondary compressed air regulating valve (2) is an electric regulating valve, and the manual compressed air regulating valve (3) is a gate valve.

[0008] The beneficial effects of this invention are: using compressed air to supply part or all of the air supply (oxygen supply) results in significant energy savings; simultaneously, shutting down the air supply eliminates noise sources. It also reduces the frequency of use of certain equipment (such as air supply and desuperheating water equipment), thus lowering maintenance costs. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the overall structure of the present invention; Among them, 1. primary compressed air regulating valve, 2. secondary compressed air regulating valve, 3. manual compressed air regulating valve, 4. desuperheating water valve, 5. pressure transmitter, 6. thermocouple, and 7. fan outlet valve. Detailed Implementation

[0010] The following is in conjunction with the appendix Figure 1 This invention will be further described in detail to enable those skilled in the art to implement it based on the description. This invention is applicable to low-sulfur limestone-gypsum wet desulfurization oxidation air systems. Specifically, taking the desulfurization system of an 80MW gas turbine unit in a steel plant as an example, the implementation steps of this method are explained as follows: 1. Assessment and Design: Calculate the oxidation air demand of the desulfurization tower under low sulfur content conditions (e.g., SO2 concentration < 500 mg / Nm³, oxidation air volume < 1000 m³ / h). Assess the stability and remaining supply capacity of the compressed air system.

[0011] Taking advantage of the fact that the demand for oxidation air in desulfurization towers under low-sulfur conditions is much lower than the supply capacity of conventional compressed air systems, the widely available and highly reliable compressed air systems in factories are used as alternative sources of oxidation air for desulfurization. And through an intelligent control system, precise parameter matching and system redundancy backup are achieved.

[0012] 2. System Construction: An existing system, an intelligent joint control desulfurization oxidation air energy-saving control system based on compressed air, includes a fan, an oxidation air main pipe, an absorption tower, and a PLC system. The fan is connected to the absorption tower through the oxidation air main pipe. The oxidation air main pipe is sequentially installed from the fan to the absorption tower with a fan outlet valve 7, a desuperheating water pipe, a pressure transmitter 5, and a thermocouple 6. A desuperheating water valve 4 is installed on the desuperheating water pipe. The fan, fan outlet valve 7, pressure transmitter 5, thermocouple 6, and desuperheating water valve 4 are electrically connected to the PLC system.

[0013] Improvement: Based on existing technology. The pipeline between the fan outlet valve 7 and the desuperheating water pipe on the oxidation air main pipe is connected to the compressed air network through a replacement air supply pipeline. The replacement air supply pipeline is sequentially installed with a primary compressed air regulating valve 1, a secondary compressed air regulating valve 2, and a manual compressed air regulating valve 3. The primary compressed air regulating valve 1 and the secondary compressed air regulating valve 2 are electrically connected to the PLC system.

[0014] When using alternative air supply lines to connect to the compressed air network, a desuperheating device is not required (by closing the desuperheating water valve), and the inherent dryness and temperature characteristics of the compressed air in the plant network can be utilized to avoid condensation problems.

[0015] 3. Intelligent Control System: Pressure sensor (pressure transmitter): Installed on the main duct of the oxidation air to monitor the pressure signal in real time; Electric regulating valves (compressed air primary regulating valve 1 and compressed air secondary regulating valve 2): receive pressure sensor signals and automatically adjust the valve opening through PID control algorithm to maintain the main pipe pressure within the set range (e.g., 40–60 kPa); when switching to fan air supply, the electric regulating valve becomes the fan outlet valve.

[0016] PLC system: integrates pressure setting, valve position control, fault diagnosis and system switching logic; integrates PID control algorithm, fault diagnosis module and system switching logic; the PID algorithm dynamically adjusts the opening of electric regulating valve according to pressure sensor feedback, with a set pressure range of 40–60 kPa and control accuracy of ±2 kPa. Human-Machine Interface (HMI): Used for parameter setting, equipment status display, energy efficiency display, and manual intervention; used to display main pipe pressure, valve status, and system operating mode in real time, and allows operators to set pressure parameters, switch between manual / automatic modes, and view fault alarms.

[0017] Alarm and interlock module: When the main pipe pressure is lower than 30 kPa, the standby oxidation fan system will be automatically started.

[0018] 4. Control system debugging: The pressure control range of the oxidation air main pipe is set to 40–60 kPa; Adjust the PID parameters to ensure stable pressure; Configure low pressure alarm (<30kPa) and automatic switching logic.

[0019] Operation and maintenance: During normal operation, the compressed air pipeline system supplies air, while the blower provides air supply as a backup. When the compressed air pipeline system cannot meet the air supply demand, the primary compressed air regulating valve 1, the secondary compressed air regulating valve 2, and the manual compressed air regulating valve 3 are closed, and the blower is turned on to supply air. At the same time, the blower outlet valve is opened.

[0020] Regularly inspect valve assemblies and control systems to verify the standby system startup function.

[0021] During normal operation, compressed air is directly injected into the desulfurization tower through the regulating valve group, and the original fan is in hot standby mode; The control system monitors the main pipe pressure in real time and maintains stability through closed-loop regulation. When an abnormal pressure or compressed air system malfunction is detected, the system automatically switches to the backup fan to ensure continuous operation.

[0022] In one embodiment, the air supply is switched from a Roots blower to compressed air: The control unit (PLC system) issues a command to stop the running Roots blower and close its outlet electric valve (blower outlet valve 7) and the desuperheating water electric valve (desuperheating water valve 4) of the oxidation air main pipe. Open the manual isolation valve (compressed air primary regulating valve 1, or electric one) and manual gate valve (compressed air manual regulating valve 3) of the compressed air branch pipe (compressed air supply pipeline), and slowly adjust the opening degree through the electric regulating valve (compressed air secondary regulating valve 2). When the pressure sensor shows that the main pipe pressure is stable within the range of 40-60 kPa, the electric regulating valve (compressed air secondary regulating valve 2) is put into automatic interlock state and continuously controlled by the PLC.

[0023] Switching from compressed air supply back to Roots blower supply: The control unit switches the electric regulating valve to manual mode, gradually closes the manual isolation valve (compressed air primary regulating valve 1, which can also be electric), the manual gate valve (compressed air manual regulating valve 3), and the blower outlet valve 7 via the electric regulating valve (compressed air secondary regulating valve 2). Open the electric valve for desuperheating water in the oxidation air main pipe (desuperheating water valve 4). Start the Roots blower and open its outlet electric valve after it has stabilized. Once the pressure stabilizes, the system switches completely to the Roots blower air supply mode.

Claims

1. A smart joint control desulfurization oxidation air energy-saving control system based on compressed air, comprising a fan, an oxidation air main pipe, an absorption tower, and a PLC system, wherein the fan is connected to the absorption tower through the oxidation air main pipe, and a fan outlet valve (7), a desuperheating water pipe, a pressure transmitter (5), and a thermocouple (6) are sequentially installed on the oxidation air main pipe from the fan to the absorption tower, and a desuperheating water valve (4) is installed on the desuperheating water pipe, and the fan, the fan outlet valve (7), the pressure transmitter (5), the thermocouple (6), and the desuperheating water valve (4) are electrically connected to the PLC system, characterized in that: The pipeline between the blower outlet valve (7) and the desuperheating water pipe on the oxidation air main pipe is connected to the compressed air network through a substitute air supply pipeline. The substitute air supply pipeline is sequentially equipped with a primary compressed air regulating valve (1), a secondary compressed air regulating valve (2), and a manual compressed air regulating valve (3). The secondary compressed air regulating valve (2) is electrically connected to the PLC system. During use, when the amount of compressed air in the compressed air network is sufficient to meet the desulfurization oxidation air, the blower, the blower outlet valve (7), and the desuperheating water valve (4) are closed, and the primary compressed air regulating valve (1), the secondary compressed air regulating valve (2), and the manual compressed air regulating valve (3) are opened to adjust the flow rate of compressed air entering the oxidation air main pipe to meet the air supply requirements. When the amount of compressed air in the compressed air network is insufficient to meet the desulfurization oxidation air, the primary compressed air regulating valve (1), the secondary compressed air regulating valve (2), and the manual compressed air regulating valve (3) are closed, and the blower, the blower outlet valve (7), and the desuperheating water valve (4) are opened to use the blower to supply air to meet the air supply requirements.

2. The intelligent joint control desulfurization oxidation air energy-saving control system based on compressed air according to claim 1, characterized in that: The alternative air supply duct is a DN50 pipe made of 316L stainless steel.

3. The intelligent joint control desulfurization oxidation air energy-saving control system based on compressed air according to claim 1, characterized in that: The primary compressed air regulating valve (1) is a manual regulating valve, the secondary compressed air regulating valve (2) is an electric regulating valve, and the manual compressed air regulating valve (3) is a gate valve.

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