Abstract: This paper introduces the development process of an automatic coal quality industrial analyzer based on virtual instrument technology. The software and hardware structure and workflow of the analyzer are described. The hardware mainly includes various sensors, analog and digital input/output boards, an analytical balance, and a heating device. LabVIEW was used as the development platform to develop a complete automatic coal quality industrial analysis software integrating functions such as analysis process monitoring, automatic or manual control, data processing, and database management. Finally, the software and hardware workflow of the analyzer during the analysis experiment is described in detail, and the characteristics and advantages of the analyzer are summarized. Keywords: Automatic coal quality industrial analyzer, Virtual instrument, LabVIEW 1 Introduction Coal costs account for approximately 70% of the power generation cost of thermal power plants. Coal quality supervision and management are directly related to the safe and economical operation of power plants. After the liberalization of the national coal market, the proportion of state-allocated coal in power plants has gradually decreased, while the proportion of coal from small kilns has increased, resulting in a widespread phenomenon of variable coal quality in power plants across the country. With the separation of power plants and grids, reducing power generation costs has become the primary task of coal-fired power plants. To improve boiler combustion efficiency and automate production and management, power plants need to accurately detect coal quality indicators to adjust boiler oxygen supply, promptly adjust boiler thermal efficiency, and maintain stable efficiency over the long term. With the continuous development of information science, the technical requirements for signal acquisition, data processing, and control operation are becoming increasingly stringent. Traditional testing and analysis instruments are increasingly unable to meet the demands of the times, especially in complex environments with numerous testing parameters, where their limitations become more pronounced. The rapid development of electronic technology objectively requires testing and analysis instruments to evolve towards automation, intelligence, and flexibility, while also providing technical support for their development. Currently existing coal quality analyzers have many shortcomings in terms of expandability, technological updates, reusability, and configurability; once the equipment is developed, it is difficult to improve it. These limitations dictate that such equipment will be replaced by automated analysis instruments that are more convenient to operate, more flexible in function, and provide more accurate and intuitive output results. Introducing virtual instrument technology into the design and development of an automated industrial coal quality analyzer based on a PC as its hardware core can conveniently and quickly assemble a comprehensive analytical instrument. Using the graphical programming environment provided by LabVIEW, single-function virtual test panels are programmed for different test and analysis objects. Each panel is equivalent to a single-function test analyzer. By calling each panel as a sub-panel, a comprehensive analytical instrument capable of measuring multiple parameters can be assembled. Although the programming approach is similar to general programming languages, the characteristics of virtual instrument technology determine its outstanding advantages in terms of ease of operation, user-friendly interface, and shorter development cycle. The introduction of virtual instrument technology can accelerate the development of test and analysis instruments in China and narrow the gap with foreign countries. 2. Hardware Design of Automatic Coal Quality Industrial Analyzer The hardware of the automatic coal quality industrial analyzer needs to perform several functions, including analog input signal acquisition, digital switch signal reading and control, communication between the computer and the analytical balance, transmission and calculation of weighing data, and result output. The analog input signal acquisition and digital switch signal reading and control boards used are the USB2010 data acquisition boards produced by Beijing Altai Company. This board is a USB bus-compatible data acquisition board with a 12-bit resolution A/D converter. It provides 32 single-ended or 16 dual-ended analog input channels and 2 D/A output channels. The A/D converter input signal range is ±5V, ±10V, and 0～10V. It has 16 digital inputs and 16 digital outputs. It provides a LabVIEW-based driver software interface module, fully compatible with the LabVIEW software platform. This allows programmers to utilize the advantages of USB interface technology while freely choosing the convenient and easy-to-use graphical programming language LabVIEW. The board acquires thermocouple transmitter signals via the USB2010 acquisition board, which are then converted to obtain the furnace temperature. The acquired nitrogen and oxygen pressure and flow signals can be displayed in real time on the user's control panel, allowing the user to determine the normal status of the nitrogen and oxygen cylinders. The photoelectric detector signal determines whether the sample tray rotation has reached the zero or sample position, in order to execute the next weighing operation. The input/output operations of the USB2010 switch are used to determine and control the actions of peripheral devices, such as the raising and lowering of the automatic analyzer's cover, the rotation and raising/lowering of the sample tray, the on/off switching of solid-state relays, the activation of the exhaust fan during the experiment and the activation of the cooling fan after the experiment, the opening and closing of nitrogen and oxygen solenoid valves, the switching of compressed air and oxygen as power sources, and the detection and determination of the power supply and resistance furnace power supply by the switch input signals. Based on the accuracy requirements of the analyzer and the actual situation, the BS124S fully automatic analytical balance manufactured by Beijing Saituolas Instrument Systems Co., Ltd., a subsidiary of the German Sartorius Group, was selected. The balance is communicated with via the computer's RS-232 serial port, and the software issues commands to zero the balance and read data. The hardware structure is shown in Figure 2-1. [align=center] Figure 2-1 Hardware Structure Diagram[/align] 3 Automatic Coal Quality Industrial Analysis Software Design The software design uses LabVIEW (Laboratory Virtual Instrument Engineering Workbench) as the development platform. This development software employs fully graphical programming, generating a soft panel on the computer screen using its built-in function library and development tool library. This panel provides input values ​​to the test system and receives its output values. In appearance and operation, the panel mimics tangible devices, maintaining a traditional and intuitive visual and sensory experience, while functionally identical to commonly used programming languages. Users can easily control multiple virtual instruments from a single front panel and treat the system as a single virtual instrument. LabVIEW integrates numerous templates for generating graphical interfaces, such as various switches, knobs, meters, scales, and indicator lights, containing the main controls required to compose an instrument. Users can also easily design controls not found in the library. Industrial analysis of coal, also known as technical or practical analysis, is the fundamental basis for evaluating coal quality. In national standards, industrial analysis of coal includes the determination of indicators such as moisture, ash, volatile matter, and fixed carbon. Typically, moisture, ash, and volatile matter are directly measured, while fixed carbon is calculated using a subtraction method. The industrial analysis process for determining coal quality using thermogravimetric analysis (TGA) involves first measuring the moisture content of the coal sample, then the volatile matter content, and finally the ash content. This is the standard procedure for both domestic and international instruments, with the main differences being the heating temperature and rate of increase. Based on the required functions of the coal quality analyzer and the programming characteristics of LabVIEW, the software is designed with 12 sub-modules, including: analog input module, digital switch input/output module, database module, serial port parameter setting module, serial communication module, parameter setting module, temperature measurement module, moisture measurement module, volatile matter measurement module, ash content measurement module, calculation results module, background database, and results database module. The software structure is shown in Figure 3-1, and the main program panel is shown in Figure 3-2. [align=center] Figure 3-1 Software system composition diagram Figure 3-2 Front panel obtained using LabVIEW programming[/align] 4 Coal Quality Analysis Process After the user has prepared all necessary experimental materials (such as a pre-dried clean empty crucible, air-dried coal samples with a particle size less than 0.2 mm, peripherals, etc.), they can click the "Run" button to run the software. Depending on the actual situation, users need to set the parameters when running the software for the first time. Users can select the next level of the "Settings" menu to access the parameter settings. A pop-up interface will appear, requiring users to set the upper and lower limits for nitrogen and oxygen pressure and flow rate. If the nitrogen and oxygen pressure and flow rate exceed the set limits, the system will consider it unsafe, display a dialog box, and stop all experiments. Users also need to set whether to use oxygen or compressed air as the power source to raise and lower the analyzer chamber cover, and whether to activate the exhaust fan during the experiment. After the initial settings, no further settings are required when running the program, unless the actual situation changes. Users can start the experiment by clicking the "Start Experiment" button or selecting "Start Experiment" from the menu. It should be noted that the table in Figure 3-2 is initially hidden, replaced by a diagram of a turntable and crucible. This table only appears and displays the data in the corresponding places when the experiment begins and the crucible is measured. Furthermore, the "Sample Name" column is entered by the user based on the specific coal sample being tested. The "Stop Experiment," "End Experiment," and "Calculate Results" buttons on the interface are only available after selecting "Start Experiment." The current status bar on the main interface displays the current experimental steps in real time, such as which item is being measured on which crucible. At the beginning of the experiment, the software automatically detects the operating status of the control power supply by checking the input signal return value through the switch input/output module. If normal, the next step of the experiment can proceed; otherwise, a dialog box pops up prompting the user to check the control power supply. Then, it checks if the analyzer's lid is open and instructs the user to place the crucible. If not, it controls the lid to rise and open it. Once the lid is fully open, the action stops, and the user is prompted to place an empty crucible for this experiment. Simultaneously, a zeroing command is sent to the balance via the serial communication module, and the zeroing is considered successful when the balance return value is less than 0.0003, proceeding to the next step. After the user places the empty experimental crucible and clicks "Confirm," the analyzer's lid automatically closes. First, it checks if the sample pan has been raised; if not, it controls the sample pan to rise until it is in the correct position. Then, rotate the sample pan to find the zero point (used to define the crucible sequence). After finding the zero point, stop rotating the sample pan and lower it each time a sample position (i.e., the position where the crucible is placed) is detected, so that the weight of the crucible falls onto the balance. At this time, the balance data can be read via serial communication. Repeat this process until the weight of all empty crucibles is measured. The mass data of each empty crucible can be displayed in the corresponding position on the interface table in Figure 3-2. After the mass measurement of the empty crucibles is completed, the analyzer's lid will automatically open, and a dialog box will pop up prompting the user to add a coal sample. Generally, the mass of the added coal sample is about 1g. After adding the coal sample, the user clicks the "OK" button in the dialog box to enter the coal sample mass measurement stage. The process is the same as measuring the empty crucibles. After the measurement is completed, the result data (each crucible is reduced by the original weight of the empty crucible) will also be displayed in the table on the interface. Next, the user selects the items to be tested in this experiment, which can be moisture, volatile matter, ash, moisture and ash, moisture and volatile matter, volatile matter and ash, or industrial full analysis (i.e., analyzing all three items). If only one or two items are selected, the experimental time can be greatly shortened. It should be noted that if only volatile matter is selected, the experiment still starts with moisture measurement. This is because to obtain the percentage content of volatile matter, simply heating the experiment to (900 ± 10) °C will result in a reduction in coal sample mass including moisture reduction; therefore, the percentage moisture content data must be removed. The same principle applies to experiments involving volatile matter and ash. The modules for measuring moisture, volatile matter, and ash are independent of each other; selecting the required analytical item calls the corresponding module for the experiment. During the experiment, the analyzer obtains the corresponding mass data in the order of heating, isothermal control, and weighing (the temperature, isothermal time, and other parameters during the experiment strictly follow the provisions of GB212-2001 "Industrial Analysis Methods for Coal") and displays it in a table on the interface. This automated coal quality industrial analyzer is a highly automated instrument. Once the measurement begins, user intervention is minimal; the software automatically performs each step and alerts the user to abnormal situations, such as malfunctions in the lid opening/closing, sample pan rising/falling, or balance readings. Dialog boxes will pop up prompting manual adjustments. After the analysis is complete, the user can select the calculation results module. The user needs to input parameters such as the hydrogen coefficient and calorific value coefficient based on experience and the actual coal quality. The analysis results are then calculated according to the relevant formulas defined in GB212-2001 "Industrial Analysis Methods for Coal". The results are saved in the results database for later retrieval and printing. 5. Conclusion The innovation of this paper lies in the first application of virtual instrument technology to the field of coal quality industrial analysis, combining virtual instruments with traditional coal thermogravimetric analysis techniques. This greatly simplifies hardware connection and control design, facilitating maintenance and management by operators. Furthermore, using a virtual instrument panel instead of a traditional physical instrument reduces system costs, improves experimental efficiency, enhances system flexibility and scalability, and facilitates experiments for operators. References [1] Zhang Hongliang, Lin Musong. Current status of application of rapid coal quality analysis instruments. Thermal Power Generation, 2002(4): 7-9. [2] Chen Wenyan. On the application progress of thermal analysis technology in coal quality analysis. Modern Scientific Instruments, 2002(6): 52-54. [3] Guo Enquan. Development trend of virtual instruments and its impact on testing technology. Computer Automatic Measurement and Control, 1999(7): 5-7. [4] Cai Jijun, Zhang Yanbin, Mi Xiaoyuan et al. Design of virtual instrument human-computer interface based on event-driven programming. Microcomputer Information, 2005, 11(1): 199-120. [5] Yang Leping et al. LabVIEW Programming and Application. Beijing: Electronic Industry Press, 2001. [6] GB/T 212—2001. Industrial analysis methods of coal. National Standard of the People's Republic of China. 2001: 19-27.