Full-redundancy pressure swing adsorption nitrogen generation equipment control system

Abstract

The invention relates to the technical field of nitrogen making equipment control, and particularly discloses a full-redundancy pressure swing adsorption nitrogen making equipment control system which comprises a master control cabinet, two refrigeration dryer control cabinets and three full-redundancy pressure swing adsorption nitrogen making equipment sequence control boxes, and single-chip microcomputers are arranged in the refrigeration dryer control cabinets and the full-redundancy pressure swing adsorption nitrogen making equipment sequence control boxes. The refrigeration dryer control cabinet and the full-redundancy pressure swing adsorption nitrogen generation equipment sequence control box can both achieve local start-stop operation and remote start-stop operation, the master control cabinet can control start-stop of the refrigeration dryer and the full-redundancy pressure swing adsorption nitrogen generation equipment in a remote start-stop mode, and full-redundancy design is adopted in the master control cabinet. Starting from the aspects of equipment network layout, component type selection, program control and redundancy safety, a series of problems of action time sequence and valve control when the refrigeration dryer and the PSA equipment work at the same time are solved; the comprehensiveness and safety of the functions meet the international high standard requirements, and the application under various environment working conditions is met.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrogen production equipment control, and in particular to a fully redundant pressure swing adsorption nitrogen production equipment control system. Background Art

[0002] Nitrogen, as an inert gas, is widely used as a chemical raw material and protective gas in various industries, including shipping, petrochemicals, and healthcare. Due to the unique application environment of nitrogen generators in the petrochemical industry, users have extremely high requirements for nitrogen production efficiency, stability, and safety. Conventional nitrogen generator control systems often experience alarm shutdowns and other issues during operation due to various faults. This situation can directly lead to the suspension of production at the entire production site, causing significant economic losses and fundamentally failing to meet the high-stability nitrogen equipment requirements of today's oil and gas industry. Therefore, to improve this situation, we propose a fully redundant pressure swing adsorption nitrogen generator control system. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems in the prior art and provide a fully redundant pressure swing adsorption nitrogen production equipment control system.

[0004] The technical solution of the present invention is: A fully redundant pressure swing adsorption nitrogen making equipment control system includes a main control cabinet, two cold dryer control cabinets and three fully redundant pressure swing adsorption nitrogen making equipment sequential control boxes. The cold dryer control cabinet and the fully redundant pressure swing adsorption nitrogen making equipment sequential control boxes are both equipped with single-chip microcomputers. The cold dryer control cabinet and the fully redundant pressure swing adsorption nitrogen making equipment sequential control boxes can both realize local start and stop operation and remote start and stop. The main control cabinet can control the start and stop of the cold dryer and the fully redundant pressure swing adsorption nitrogen making equipment in the remote start and stop mode. Hard wiring and Modbus communication connections are established between the main control cabinet and the cold dryer and the fully redundant pressure swing adsorption nitrogen making equipment sequential control boxes. The main control cabinet adopts a fully redundant design.

[0005] Preferably, the main control cabinet is provided with an internal switching power supply, a PLC controller, a CPU, an IO module and a communication module. The internal switching power supply, the PLC controller, the CPU, the IO module and the communication module are all designed to be redundant. When a module fails, the system can automatically switch without stopping the main control cabinet. The system adopts a fully redundant design. During the operation of the equipment, if a device fails and stops working, the main control cabinet will automatically switch to the backup machine to ensure production continuity.

[0006] Preferably, the main control cabinet is also responsible for monitoring the operating parameters of the entire set of fully redundant pressure swing adsorption nitrogen production equipment and the control of the gas supply valve, and at the same time establishes a connection with the DCS system and SIS system, and sends various operating data and alarm information to the host computer; The start, stop and emergency stop of each device are instructed by the main control cabinet and implemented through hard wiring to ensure system stability; the equipment operating status, operating parameters and alarm information are summarized in the main control cabinet through communication for unified management.

[0007] Under normal operating conditions, one cold dryer is in use and one is in standby mode, and two of the three fully redundant PSA nitrogen generators are in use and one is in standby mode. The two cold dryer control cabinets are connected to the cold dryers, and the three fully redundant PSA nitrogen generators have sequential control boxes connected to the fully redundant PSA nitrogen generators. Under extreme operating conditions, the standby cold dryer and the fully redundant PSA nitrogen generators are automatically put into use to ensure the back-end gas consumption. The cold dryer control cabinets and the fully redundant PSA nitrogen generators have sequential control boxes connected to the standby cold dryer and the fully redundant PSA nitrogen generators. In the event of a fault, the system can switch without stopping to ensure production continuity.

[0008] Preferably, the main control cabinet is equipped with an air conditioner to ensure the normal operation of the system in high temperature environments in summer. The air conditioner needs to fully cooperate with the main control cabinet to ensure the protection level inside the main control cabinet; Adapt to the different use environments and areas of use to ensure the normal operation of the main control cabinet in high temperature environments in summer.

[0009] Preferably, a double-opening cabinet door is provided on the front side of the main control cabinet, and a touch screen, an emergency stop button, multiple buttons and indicator lights are provided on the cabinet door. The buttons are operation buttons, and the indicator lights are indicator lights that work in conjunction with the buttons. Ensure that the main control cabinet is easy to operate and various operations and results are displayed clearly.

[0010] Preferably, the internal program of the single chip microcomputer is solidified to ensure the stability of operation; When using a single-chip microcomputer, the main considerations are its stability, durability and anti-interference performance. The equipment control logic needs to be clear in the early design and development stage. After the control logic is developed, the internal program of the single-chip microcomputer is solidified and no changes are made after the equipment is debugged.

[0011] The present invention adopts the above structure and has the following advantages: 1. The overall system is safe and reliable, highly versatile, highly integrated, and adopts a modular design; 2. Starting from the aspects of equipment network layout, component selection, program control and redundant safety, the operation sequence and valve control series problems of the simultaneous operation of the cold dryer and PSA equipment were solved; 3. The comprehensiveness and safety of the functions meet the high international standards and can be used in various environmental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the topological structure of the present invention; Figure 2 This is a schematic diagram of the network configuration of the present invention; Figure 3 This is the main structural diagram of the main control cabinet; Figure 4 This is a schematic diagram of the right side structure of the main control cabinet; Figure 5 A working baseline for blank non-redundant controller memory; Figure 6 The redundant memory usage is not enabled. Figure 7 To enable redundant memory usage one; Figure 8 The second case is when redundant memory usage is not enabled; Figure 9 To enable redundant memory usage two; Figure 10 This is a schematic diagram of the automatic control interface; Figure 11 This is a schematic diagram of the manual control interface; Figure 12 This is a schematic diagram of the automatic control switching pressure value; Figure 13 is a process flow chart; Figure 14 This is a schematic diagram of the timing of the two groups of adsorption towers; Figure 15 This is a schematic diagram of the timing of the three groups of adsorption towers; Figure 16 This is the control system and instrument connection block diagram.

[0013] In the picture, 1. Touch screen; 2. Buttons and indicator lights; 3. Emergency stop button; 4. Air conditioning. DETAILED DESCRIPTION

[0014] In order to make the technical means, technical features, invention objectives and technical effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific illustrations.

[0015] like Figure 1 and Figure 16 As shown in the figure, a fully redundant PSA nitrogen generator control system includes a master control cabinet, two refrigerated dryer control cabinets, and three fully redundant PSA nitrogen generator (fully redundant PSA nitrogen generator can be referred to as PSA) sequential control boxes. Hard wiring and Modbus communication connections are established between the master control cabinet and the refrigerated dryers and the fully redundant PSA nitrogen generator sequential control boxes. The master control cabinet is also responsible for monitoring the operating parameters of the entire set of fully redundant PSA nitrogen generators and controlling the gas supply valves. At the same time, it establishes connections with the DCS system and SIS system, and sends various operating data and alarm information to the host computer. Figure 2As shown in the figure, the main control cabinet adopts a fully redundant design. The main control cabinet is equipped with an internal switching power supply, PLC controller, CPU, IO module and communication module. The internal switching power supply, PLC controller, CPU, IO module and communication module are all designed with redundancy. When a module fails, the system can automatically switch without stopping through the main control cabinet. like Figure 3 As shown, the main control cabinet is equipped with a double-door on the front side, on which a touch screen 1, an emergency stop button 3, multiple buttons and indicator lights 2 are installed. The buttons are operation buttons, and the indicator lights are indicators that work in conjunction with the buttons. Figure 4 As shown, the main control cabinet is equipped with an air conditioner 4 to ensure the normal operation of the system in a high temperature environment in summer. The air conditioner 4 needs to fully cooperate with the main control cabinet to ensure the protection level inside the main control cabinet. Both the refrigerated dryer control cabinet and the fully redundant PSA nitrogen generator control box are equipped with single-chip microcomputers. The internal programs of the single-chip microcomputers are solidified. The use of single-chip microcomputers is mainly based on their stability, durability and anti-interference performance. The equipment control logic needs to be clear in the early design and development stage. After the control logic is developed, the internal programs of the single-chip microcomputer are solidified. After the equipment is debugged, no changes are made. The refrigerated dryer control cabinet and the fully redundant PSA nitrogen generator control box can realize local start and stop operation and remote start and stop. In the remote start and stop mode, the main control cabinet can control the start and stop of the refrigerated dryer and the fully redundant PSA nitrogen generator. Under normal operating conditions, one cold dryer is in use and one is in standby mode, and two of the three fully redundant PSA nitrogen generators are in use and one is in standby mode. The two cold dryer control cabinets are connected to the cold dryers, one in use and one in standby mode, and the three fully redundant PSA nitrogen generators have their control boxes connected to the fully redundant PSA nitrogen generators. Under extreme operating conditions, the standby cold dryer and the fully redundant PSA nitrogen generators are automatically put into operation to ensure back-end gas consumption. The cold dryer control cabinets and the fully redundant PSA nitrogen generators have their control boxes connected to the standby cold dryer and the fully redundant PSA nitrogen generators. During equipment operation, if a device fails and stops, the main control cabinet will automatically switch to the standby device to ensure production continuity. Example 1 1. Redundancy solution design A. The main control cabinet adopts a fully redundant design. The control system power supply, CPU, IO module, communication module, etc. are all redundant. When a problem occurs in a module, the system can be switched without stopping. B. The two cold dryers and three PSA equipment are all controlled by single-chip microcomputers, and the internal program is solidified to ensure the stability of operation. In addition, under normal working conditions, one cold dryer is in use and one is in standby; the three PSA equipment are in use and one is in standby. Under extreme working conditions, the standby cold dryer and PSA equipment are automatically put into use to ensure the gas consumption at the back end. C. Hard wiring and Modbus communication connections are established between the main control cabinet, the cold dryer, and the PSA sequential control box. The start, stop, and emergency stop of each device are issued by the main control cabinet and implemented through hard wiring to ensure system stability. The equipment operating status, operating parameters, and alarm information are summarized in the main control cabinet through communication for unified management. D. During the operation of the equipment, if a device fails and stops, the main control cabinet will automatically switch to the backup machine to ensure production continuity; 2. Selection calculation 1) Component selection All instruments and control functions of the control system must meet the requirements of the PID drawings. The redundancy performance of components in the main control cabinet must be fully considered. The switching power supply, CPU, IO module, communication module, etc. in the cabinet must be selected according to the redundancy requirements. The fault switching time must be fully evaluated to ensure the stability of the control system. At the same time, the selection must comply with local standards based on the different customer environments and regions of use. 2) The overall dimensions and panel openings of the main control cabinet must strictly follow Figure 3 and Figure 4 As shown, the main control cabinet is equipped with air conditioner 4 to ensure the normal operation of the system under high temperature environment in summer. Air conditioner 4 needs to fully cooperate with the cabinet of the main control cabinet to ensure the protection level inside the main control cabinet; 3) The control of the cold dryer and PSA equipment uses a single-chip microcomputer, mainly considering its stability, durability and anti-interference performance. The equipment control logic needs to be clearly defined in the early design and development stage. After the control logic is developed, it is solidified and no changes are made after the equipment is debugged; 4) When selecting redundant PLC controllers, response, switching time, and memory capacity are crucial. The controller's memory needs to be fully considered and calculated during the PLC selection phase. This can be displayed using an offline memory estimation tool: like Figure 5 、 Figure 6 and Figure 7 As shown, the memory of a blank non-redundant controller provides a working baseline. Even though the controller program is empty, some memory will be used. Then some I / O modules will be added to the program. By Figure 6 Subtracting the Max Used bytes under Estimated I / O Memory from the Max Used bytes under Estimated I / O Memory shows that the memory has increased by 2256 bytes. Then, by comparing the working baseline and Figure 7 Subtracting the Max Used bytes under Estimated I / O Memory from the Max Used bytes shows that the memory has increased by 4176 bytes, which is about twice the memory size. like Figure 8 and Figure 9As shown, add a 10,000-element DINT array to the program by Figure 6 and Figure 8 Subtracting the Max Used bytes under Estimated Data and Logic Memory from the Max Used bytes shows that 39,880 bytes have been added to the memory, which is approximately the size of a 10,000-element DINT array. Figure 7 and Figure 9 Subtracting the Max Used bytes under Estimated Data and Logic Memory from the Max Used bytes shows an increase of 80,108 bytes in memory, which is approximately twice the size of the 10,000-element array. The two examples above confirm that I / O and data memory are approximately doubled when redundancy is enabled. The basic goal of the output processing method in redundant PLC controllers is to ensure that no data is sent from the primary controller to the output module without the same value in the output image of the secondary controller. This is achieved through the output buffering mechanism. There are two copies of the output image: 1) the program output image and 2) the output transfer image The Program Output Image (POI) is a copy of the outputs that are directly accessed by the user program. All instructions, including output (write) instructions and input (read) instructions that reference output data values, will use the POI. The second buffer, the Output Transfer Image (OTI), is a copy of the outputs actually sent to the output modules. If there is a qualified secondary controller in the system, changes in the primary controller's POI will be sent to the secondary controller first. The OTI in the primary controller will not be updated with data from the POI until the secondary controller confirms that it has received the data and moves the data to its own OTI. If there is no secondary controller, the data will be copied from the POI to the OTI at the end of each program. Therefore, the amount of I / O memory has doubled due to the creation of the POI. If output were the only I / O that needed to be buffered, then the I / O memory should only be increased in the amount used for output. However, to improve performance, it is easier and faster to make an exact copy of the I / O memory. Then, when moving data from the POI to the OTI, a constant offset needs to be used. Again, the payoff is performance compared to the increased memory usage. As the primary controller executes its program, it tracks the data accessed through the program execution. When the primary controller transfers this tracked data to the secondary controller, it transfers it to a buffer area rather than directly to the active data memory. This buffer has the same layout as the active data memory. Once all tracked data has been transferred to the secondary buffer, the data is moved to the active data memory. The buffer is used to ensure that all data is received from the primary first. This is why the data memory is doubled. Memory usage is calculated as follows: Controller memory usage (bytes) = number of controllers × 4000 The amount of memory used by digital I / O points (bytes) = number of I / O points × 400 The amount of memory used by analog I / O points (bytes) = number of I / O points × 400 The amount of memory used by the network module (bytes) = the number of modules × 7400 Memory used by other communication modules (bytes) = number of modules × 2000 The amount of memory used by the motion axis (bytes) = the number of motion axes × 8000 The amount of memory used for alarm indication (bytes) = number of alarms × 2000 Then calculate the total amount of memory usage to provide a reference when selecting; 3. Heat calculation of control cabinet This control system is required to be used in a variety of environments, such as the desert environment in the Middle East, where the ambient temperature can reach 55°C in summer. To ensure the normal operation of the control system, it is necessary to calculate the heat dissipation of the control cabinet and configure a suitable air conditioner 4 or eddy current cooler. The calculation process is as follows: Taking the above table as an example, the total heat generated by the components in the control cabinet is W1 343.02W, and the cabinet size is 1200 (W) × 1800 (H) × 600 (D) Step 1: Calculate the surface area of the control cabinet, S=2×(1.2×1.8+1.2×0.6+1.8×0.6)=7.92m 2 Step 2: Calculate the temperature difference, ΔT = ambient temperature 55°C - desired temperature inside the cabinet 40°C = 15°C Step 3: Calculate the heat transfer of the cabinet, the heat conductivity coefficient of the steel plate K1 (W / m 2 ℃) take 5, then the heat transfer of the control cabinet is Q=K1×ΔT×S=594W Step 4: The required cooling capacity of air conditioner 4 is W=K2(Q+W1)=1.1×(343.02+594)=1030.7W. Therefore, the cooling capacity of the selected air conditioner 4 should not be less than the W value. 4. Control Description like Figure 10 and Figure 11 As shown in the figure, A.HMI human-machine interaction interface can select DCS remote control or PLC local control mode. In remote control mode, the operator can control the start and stop of the dryer and PSA equipment through the DCS system; B. In local control mode, the operator can choose automatic control or manual control mode. In manual control mode, the operator can manually control the start and stop of a single refrigerated dryer and PSA equipment, as well as the opening and closing of the refrigerated dryer air supply valve, which is convenient for equipment commissioning or use under fixed gas consumption conditions; C. In local automatic mode, the PLC controller determines the number of PSA devices to be put into operation based on the pressure value of the final outlet of the equipment, such as Figure 12 As shown, the three groups of PSA equipment are set as the master, slave and standby respectively. The PLC controller automatically switches according to the actual gas consumption. In addition, in order to avoid the loss caused by long-term operation of a single device, the device is set with a timed rotation function. After a period of operation, the master, slave and standby are rotated. The HMI interface is set with a mode switching button. In the "MODEA" mode, A is the master, B is the slave, C is the standby, and so on. The device rotation time can be set through the parameter setting interface; D. Figure 13 As shown, pneumatic ball valves are respectively installed at the air inlets of the cold dryers, which can be opened manually in manual mode. In automatic mode, when a certain cold dryer is started, the corresponding pneumatic ball valve automatically opens to supply air. Each group of PSA equipment outlets is equipped with two pneumatic ball valves, which respectively serve as venting and air supply. In manual mode, when a certain row of PSA equipment produces nitrogen with qualified purity and the air supply pressure reaches the set value, the air supply valve opens and the corresponding vent valve closes; otherwise, the air supply valve closes and the vent valve opens. 5. Interconnection between the main control cabinet and DCS and SIS systems The main control cabinet and DCS are interconnected through hard wiring and Modbus communication. The DCS system can realize remote start and shutdown of on-site equipment through hard wiring. At the same time, the equipment's various operating status, alarm information and operating data are transmitted to the DCS system through communication, which can monitor the equipment operation status in real time and realize unmanned operation. The remote emergency stop circuit of the SIS system is connected to the local control system through a safety relay. The local control system also has an emergency stop circuit. If an emergency occurs during equipment operation and the equipment needs to be shut down, an emergency stop can be performed through the SIS system or the local emergency stop button 3 to ensure system safety. 6. Timing control The timing control of PSA equipment is very important to the stability of the equipment process. If two or three groups of adsorption towers are in the pressure equalization state at the same time, it will cause fluctuations in the system pressure and flow rate within a large range (the equipment does not produce gas to the outside in the pressure equalization state). In order to ensure the stability of the system pressure and flow rate, the pressure equalization time of each group of adsorption towers needs to be staggered. The three groups of PSA equipment in the present invention adopt a modular design. The operation of each group of adsorption towers is completed by the local fully redundant pressure swing adsorption nitrogen production equipment sequential control box. The fixed program ensures the stable operation of each group of equipment. The main control cabinet controls the number of adsorption towers put into operation through the pressure monitoring of the final outlet. The main control cabinet can automatically match the input and interval time of each group of PSA equipment adsorption towers according to different PSA equipment operation groups, adsorption time, pressure equalization time and other parameters to ensure that the time intervals between each group of towers are evenly distributed, thereby ensuring the stability of the product gas. Figure 14 and Figure 15 Timing control of the system shown.

[0016] It should be noted that the above-mentioned switching power supply, PLC controller, CPU, IO module, communication module, DCS system, SIS system and host computer are all applications of existing technologies.

[0017] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. That is, any equivalent changes and modifications made according to the content of the patent application of the present invention should fall within the technical scope of the present invention.

Claims

1. A fully redundant pressure swing adsorption nitrogen production equipment control system, characterized by: It includes a main control cabinet, two cold dryer control cabinets and three fully redundant pressure swing adsorption nitrogen making equipment control boxes. The cold dryer control cabinet and the fully redundant pressure swing adsorption nitrogen making equipment control boxes are both equipped with single-chip microcomputers. The cold dryer control cabinet and the fully redundant pressure swing adsorption nitrogen making equipment control boxes can realize local start and stop operation and remote start and stop. The main control cabinet can control the start and stop of the cold dryer and the fully redundant pressure swing adsorption nitrogen making equipment in the remote start and stop mode. Hard wiring and Modbus communication connections are established between the main control cabinet and the cold dryer and the fully redundant pressure swing adsorption nitrogen making equipment control boxes. The main control cabinet adopts a fully redundant design.

2. The fully redundant pressure swing adsorption nitrogen production equipment control system according to claim 1 is characterized in that: The main control cabinet is equipped with an in-cabinet switching power supply, PLC controller, CPU, IO module and communication module. The in-cabinet switching power supply, PLC controller, CPU, IO module and communication module all adopt a redundant design. When a module has a problem, the system can achieve automatic switching without stopping through the main control cabinet.

3. The fully redundant pressure swing adsorption nitrogen production equipment control system according to claim 2 is characterized in that: The main control cabinet is also responsible for monitoring the operating parameters of the entire set of fully redundant pressure swing adsorption nitrogen production equipment and the control of the gas supply valve, and at the same time establishing a connection with the DCS system and SIS system, and sending various operating data and alarm information to the host computer.

4. The fully redundant pressure swing adsorption nitrogen production equipment control system according to claim 3 is characterized in that: Under normal operating conditions, one cold dryer is in use and one is in standby, two of the three fully redundant pressure swing adsorption nitrogen making equipment are in use and one is in standby, the two cold dryer control cabinets are used as one cold dryer and one is in use, and the three fully redundant pressure swing adsorption nitrogen making equipment sequential control boxes are used as two of the fully redundant pressure swing adsorption nitrogen making equipment. Under extreme operating conditions, the standby cold dryer and the fully redundant pressure swing adsorption nitrogen making equipment are automatically put into use to ensure the gas consumption at the back end, and the cold dryer control cabinet and the fully redundant pressure swing adsorption nitrogen making equipment sequential control box are automatically put into use with the standby cold dryer and the fully redundant pressure swing adsorption nitrogen making equipment.

5. The fully redundant pressure swing adsorption nitrogen production equipment control system according to claim 4 is characterized in that: The main control cabinet is equipped with an air conditioner (4) to ensure the normal operation of the system under high temperature conditions in summer. The air conditioner (4) needs to fully cooperate with the main control cabinet to ensure the protection level inside the main control cabinet.

6. The fully redundant pressure swing adsorption nitrogen production equipment control system according to claim 5, characterized in that: The front side of the main control cabinet is provided with a double-opening cabinet door, and the cabinet door is provided with a touch screen (1), an emergency stop button (3), a plurality of buttons and indicator lights (2), wherein the buttons are operating buttons and the indicator lights are indicator lights that work in conjunction with the buttons.

7. The fully redundant pressure swing adsorption nitrogen production equipment control system according to claim 6, characterized in that: The internal program of the single chip microcomputer is solidified to ensure the stability of operation.

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