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The first urea workshop of Lutianhua Co., Ltd. renovated the entire instrument system in 2006. The pneumatic instruments used on site were replaced with intelligent electric instruments. The DCS is the FOXBORO I/A's system, which uses the 50 series based on the UNIX operating system, which is safe and reliable. The real-time monitoring software used in this system has a user-friendly interface. You can easily complete the operation by just clicking the ball mark. Together with the operator's special keyboard embedded on the operating table, the real-time monitoring operation of the production process is more convenient and faster. 1 Network structure of I/A Series The communication network of the I/A Series system is based on the Open System Interconnection (OSI) standard defined by the International Organization for Standardization (1SO) and complies with the IEEE specifications. It is a standard network constructed according to the local concept. Figure 1 is a diagram of the DCS network structure. http://www.nmtech.com.cn/jishuwang/upload1/0707201129523726.jpg 2 Hardware composition 2.1 Control room (1) AW51F engineering station host (AW5121) - 64-bit processor, 512MB memory, CD-RW optical drive, 80GB hard drive, 3.5 "1.44MB floppy drive, standard keyboard/ball mark, 100MB Ethernet card (RJ45 port, used to connect to the management network): 19”EIZOLCD。 The AW51F engineering station host is placed in the operating console, and the LCD is placed on the table. The connecting cable length to the main cabinet is 30 meters. (2) WP51F operator station configuration (WP5122-WP5126) - 64-bit processor, 512MB memory, CD-DVD drive, 80GB hard drive, 3.5 "1.44MB floppy drive, standard keyboard/ball mark, 100MB Ethernet card (RJ45 port, used to connect to the management network): 19" EIZO LCD. Operator keyboard, GCIO. WP51P operator station host, GCIO is placed in the operating console, and LCD is placed on the table. The connecting cable length to the main cabinet is 30 meters. (3) CP60FT control processor (CP6021-CP6022) - AMD DX5 processor/133MHz main frequency/8MB memory (can configure 4000 function blocks) processing speed of 3400 function blocks/second. (4) Auxiliary console: 1 set for operator assistance. (5)Communication dispatch console: 1 set, used to place the dispatch telephone. (6)A4 color inkjet printer: 1 unit for screen copying. 2.2 Computer room (1) Processor cabinet - 1, used to place the control processor and communication cards. (2) FBM card cabinets - 3, used to place FBM input/output cards. (3) Relay cabinet - 1, placed for relays, AC contactors and 24VDC regulated power supply. (4) 220VAC power distribution cabinet - 1, used for 220VAC power supply. 2.3 Fieldbus component FBM: FBM (Field Bus Module) The field bus component FBM (Field Bus Module) of the UA Series system can be connected to the control processor or PC running the I/A Series comprehensive control software. Fieldbus components can be installed locally with a control processor or PC, or remotely. Fieldbus components match the various field signals commonly encountered in industrial sites. And, because these components are configured by software, they come in far less variety than previous systems. For example, only one component is required for each type of thermocouple and millivolt signal. Fieldbus components provide an interface between field sensors/actuators and redundant fieldbuses. These components perform appropriate conversion of the electrical input/output signals used by field devices so that they can communicate with these devices via the fieldbus. Table 1 introduces several commonly used FBMs in urea plants. http://www.nmtech.com.cn/jishuwang/upload1/0707201130334831.jpg Here we need to explain the naming rules of FBM cards: ABBCDE, where: A——CP60 serial number, 1(CP6021), 2(CP6022) ； BB——FBM card model, such as 01 (FBM01), 05 (FBM05) ； C——FBM cabinet number, such as 2(E00002), 3(E00003), 4(E00004), 5(E00005) ； D——FBM card layer number, such as 1 (representing one layer) ； E——FBM slot number, such as 1 (Slot1), A (Slot 1), B (Slot 1), C (Slot 1). The 205421 mentioned below means that the CP is CP6022, the card is FBM05, the cabinet number is E00004, the FBM card layer number is layer 2, and the FBM slot number is 1. 3. Control configuration After the I/Ag system software and hardware are installed in place, the next thing to do is to configure the control scheme into the machine, so that you can start driving. I/A's provides some default display operation methods. Due to the openness of I/A's, we do not have to wait for the equipment to arrive before doing this work. As long as there is a personal computer with PW-C software installed, all configuration work can be done. 3.1 Concepts of Compound and Block Before starting the configuration, we need to first understand the Compound and Block. In order to illustrate, first look at Figure 2 to construct a urine-synthesis tower R1 liquid level control loop. The on-site measurement signal LT-403 is connected to the analog signal input module AIN through the first channel of the FBM (205421), and is converted into a digital quantity and processed by the PID module. The PID module calculates the opening of the valve according to the control requirements. Finally, the AOUT module converts the digital quantity controlling the opening of the valve LV-403 into an analog signal and sends it to the site through the eighth channel of the FBM (205421). In such a simple control loop, three modules, AIN, PID and AOUT, are used, and these three modules are closely related in the loop. We usually put mutually related modules into a set, and call this set a Compound combination module (or function block combination). http://www.nmtech.com.cn/jishuwang/upload1/0707201131124470.jpg 3.2 Parameter name of function block combination (Compound): The name of the Compound, up to 12 characters, can be 1-9, A-E and - (underscore). The Compound name must be unique in the entire system (that is, two Compounds cannot have the same name). In order to facilitate memory during configuration in the entire system, we have several requirements when doing Compound. We have Compounded each section of the urine system. The principle is the instrument tag number of each section, such as: U700-1 is an instrument represented by 700#, UKYJ-1 means that the instrument number belongs to the air compressor. DESCRP: The description of Compound can be up to 32 characters. PERIOD: Compound's processing cycle. Its processing cycle must be less than or equal to the minimum processing cycle of all modules it contains so that all modules can be processed. Generally, the default value "1" is used, which is the basic processing cycle of the control processor where it is located. 3.3 Module (Block) parameters Different types of modules have different parameters, but the following parameters are common to all modules. NAME: The module name is a string name defined by the user that must be unique in the same combination. It can be up to 12 characters and can take numbers (0-9), uppercase letters (A~Z) and underscores (_). TYPE: The module type that identifies the control function defined by the system, up to 6 characters. If you can't remember the module type name, you can list all module type names through a BlockType Names. DESCRP: Description of the user-defined module, up to 32 characters. PERIOD: Processing cycle number of the module. The usage is the same as Compound's processing cycle. You can also use +CP ProcessingPeriods to find the cycle number of the corresponding time. 3.4 Connection of parameters Modules are connected to each other via parameters. Each connection consists of connectable source parameters and destination parameters of the connection. All output parameters are connectable. They can be used as source parameters, and connectable input parameters can be destination parameters or source parameters. The connection method between parameters is to specify the path name of the source parameter at the destination parameter. Function block combination name: Module name. The parameter name is called the full path name. If these two modules are in the same combination block, the combination block name can be omitted and written as : Module name. Note that the colon cannot be omitted in the parameter name. To access the combination block parameter value, you can specify the function block combination name.parameter name. Function block combination name. Parameter name 3.5 FoxSelect FOXBOROI/A's system has a very good function, that is, you can check each module without connecting it to the on-site instrument to see if the configuration connection is correct. After we have assembled the program in CP, a similar configuration screen will automatically appear in Select. Press the key from the top menu to enter the Compound&Block selection screen. Through this screen, you can directly access the detailed display of Compounds and Blocks in CP. * The left side lists all Compounds names in CP and their ON/OFF status. The number after the ON/OFF characters indicates that there is currently an alarm with the highest alarm level of this value in the combination. If we enter this screen for the first time after turning on the computer, since the CP name has not been specified, it will be blank and there will be no combination name list. * The right side lists a list of module names in the currently selected Compound and their working status, as well as the current highest alarm level. Before the Compound name is determined, this is also blank. * The middle dialog box provides methods to search and select CP, Compound, and Block. Fill in the CP name you want in the CPNAME dialog box, and all Compounds under the CP will be listed on the left. The wildcard asterisk (,) represents all CPs. At this time, all CP names and their accompanying Compounds are listed on the left. Fill in the Compound name you want in the COMPOUNDS SEARCH dialog box, and you can directly select the Compound, or you can use the mouse to click on a Compound from the list on the left. The selected Compound name will appear in the SELECT box, and all module names in the Compound will be listed on the right. The BLOCKS dialog box is used in the same way. For the selected Compound, we can use TURNCOMPOUNDS ON/TURN COMPOUNDS OFF to turn it on/off. Of course, sometimes it is not convenient to turn on/off one by one. GROUPCOMPOUNDS provides a method to select a group of Compounds and perform on/off operations on this group of Compounds at the same time. The method of operation is to first click on GROUPCOMPOUNDS, then select the desired Compounds one by one. The selected ones will turn blue, and then use ON/OFF to turn them on/off. After we select it, we can enter the value directly from the keyboard to perform a simulation check. Here we only explain the analog input quantities in Compounds. In fact, the analog output quantities and digital input and output quantities are the same, so we will not explain them one by one here. Listed below are the main module types used in urinary-DCS systems: AIN (Analoglnput) analog signal input module ACCUM (Accumulator) accumulation module AOUT (AnalogOutput) analog signal output module CIN (Contactlnput) switch signal input module COUT (ContactOut) switch signal output module PID (Proportional, Integral, Derivative) proportional-integral-derivative control module CALC module: The calculation module provides logical operations, arithmetic operations and: RS trigger and other functions. Its instructions are similar to assembly language. All operations are performed on the stack. The stack of the calculation block is a first-in, last-out stack. The operands mentioned below refer to the data on the top of the stack. The actual number used depends on whether the specific operation instruction is a single-eye operation, a binocular operation, or a multi-eye operation. For example, ADD addition is a binocular operation, which adds the two data on the top of the stack, while LOG is a single-eye operation. The result of the operation is still placed back on top of the stack. The CALC module can be programmed with up to 50 steps. The following uses the calculation block to implement split-range adjustment to illustrate. Please see Figure 3. The output signal of the PID regulator is used to control two regulating valves LV-101A and LV-101B. Among them, valve A starts to operate at 0% to 50%, and valve B starts to operate at 50% to 100%. http://www.nmtech.com.cn/jishuwang/upload1/0707201132089456.jpg In order to realize the above function, we use a CALC to realize its split-range adjustment function. Please see the schematic diagram of the calculation steps in Figure 4.: First, the analog measurement signal LT-101 passes through the AIN module to the PID, and then is calculated through the calculation module CALC. It is output to the regulating valve LV-101A through the module AOUTl, and the AOUT2 output controls the regulating valve LV-101B. ； Thereby realizing its split-range adjustment function. The specific programming steps are: STEP01 CST clear stack ； STEP02 1NRl01 Enter the value of LT-101 ； STEP03 1N 50 Enter 50 ； STEP04 SUB for RDl-50 ； STEP05 BINl0 When their difference result is less than 0, go to step 10 ； STEP06 OUTR002 The result of step 4 is output to R002 ； STEP07 1N 100 Enter 100 ； STEP08 OUTR001 output to R001 ； STEP09 E * T program exits midway ； STEP010 1NRl01 Enter the value of LT-101 ； STEPll MUL2 When it is less than 50, multiply R101 by 2 ； STEPl2 OUTR001 Output the process to R001. STEPl2 END program ends ； In order to realize the above split-range control here, we only need to input the AIN of LT-101 into the intermediate variable RDl of the program, and then connect the output value of the regulating valve LV-101A to the program R001, and the output value of the regulating valve LV-101B to R002 to realize the above function. 4 System Management 4.1 Power-on Steps After the system is installed, it can be powered on. Before turning on the power, please check whether the mains power is normal, whether the UPS is working normally, and whether the power supply wiring is accurate. After the inspection is completed, first power on the CRT, printer and other equipment to self-check. Then, power on the cabinet containing the station components. Turn on the AW Sun workstation and pay attention to the flashing of the traffic lights of the DNBI or DNBX component connected to the AW. At first, the red light is on and the green light flashes regularly. After the component self-test is completed and the workstation enters the working software loading, only the green light will be on the component. Then, turn on other workstations and FBM component cabinets. After a period of self-test and startup, all components display green lights, all CRTs display images, and the system is put into normal operation. The first thing to do after the system is turned on is to set the clock. When the system has a main and auxiliary power supply, be sure to turn on the main power supply first and then the auxiliary power supply. 4.2 Shutdown steps I/A uses a multi-user, multi-tasking operating system, so even if no one is using the computer, the power cannot be cut off at will. The computer must be shut down according to the following steps, otherwise the file system or hard disk may be damaged. AW／WP: Enter the process engineer environment, select Shutdown AW and wait for the # prompt to appear (if you want to transport, enter the command halt) before powering off or restarting. The command to restart is reboot. It is best to wait 1.5 minutes before moving after a power outage. Note, do not use the method of entering the VTl00 window and entering the Shut down command to shut down AW/WP. PW: Enter the process engineer environment and select →PW_Shutdown, confirm Shutdown and wait for the shutdown and hot start prompts to appear. If you want to cut off the power, wait for 10 seconds after the prompts appear before powering off. AP: Enter the command init 0 on the VTl00 terminal to enter single user, wait for the OK prompt to appear, then enter the command shutdown now (if you want to move, use shutdown-h now), power off or restart. 5 Conclusion So far, the urea instrument has successfully passed the first 100 days after the transformation. Compared with before the transformation, not only the accuracy and reliability of the instrument measurement have been greatly improved during this period, but also the degree of automation has been strengthened. Only in this way can we better serve the safe and stable operation of chemical production.