I. Project Overview
The 725 Oil Depot of China National Petroleum Corporation's Tibet Sales Branch is located in the western suburbs of Lhasa, Tibet Autonomous Region. Completed in May 1972, the depot currently has a total oil storage capacity of 86,000 m³, classifying it as a Class II oil depot. Originally, it had 25 oil tanks with a total capacity of 86,000 tons. The depot handles five types of oil products, with the main products supplied via military pipelines, and other products transported by truck. The oil distribution system has a 3-platform, 12-loader gravity-flow oil distribution facility, handling 240,000 tons of oil annually.
With the continuous development of computer and field instrument technology, the level of automation in oil depots has greatly improved in all aspects compared with the 1990s. Most oil depots have successively installed systems such as automated oil dispensing systems, automatic liquid level metering systems, and security monitoring systems. However, these systems are often independent of each other and have not been effectively integrated. Their information has not been organically integrated, and the improvement of automation level on one side has not formed the overall automation information advantage of the oil depot. The automation system still has certain defects.
This renovation of the Tibet 725 oil depot will not only improve the automated system at the operational level, but also establish an information network system for the oil depot. Based on the refined oil depot management system, and with business management, equipment management, and safety management as the core, it will cover all aspects of the oil depot and provide a complete information solution.
II. System Design
Based on the current status of the oil depot and user needs, this solution introduces and improves various subsystems at the oil depot's production operation level. It establishes an automated information platform for the oil depot by integrating data from these subsystems using popular databases, leveraging network communication, and utilizing the Internet, thereby achieving automated production process control and information-based data management. Overall system design goals:
1) A local area network was established in the reservoir area, achieving comprehensive network coverage;
2) Centralized and shared production data resources;
3) Automation and information management of the quantitative loading process for oil delivery on highways.
4) Automated dynamic monitoring and metering of tank area liquid levels;
5) Automated control of tank farm process flow;
6) Computerized management of oil depot equipment;
7) Intelligent security monitoring;
8) Streamlining and documenting production processes;
9) The oil depot management team maintains transparency in all aspects of production;
10) Provide data interfaces for provincial and municipal companies to upload production data.
III. System Architecture
The structure of the oil depot automation system is divided into three levels according to business functions: the management decision-making level, the business management level, and the production operation level.
The production operation layer is located at the bottom of the oil depot automation system. It mainly provides control, safety and data guarantees for the operation and management of the oil depot from five aspects: metering, safety interlock, security monitoring, automatic control and operation management. While completing the data collection and process control of the oil depot production operation, it provides production data to the business management and management decision-making level.
The business management layer is the core of the entire oil depot production data management system. It is an information management system that organizes, processes, analyzes, and publishes basic data, and mainly handles the daily business management of oil products entering, selling, and storing within the oil depot.
The management decision-making level data terminal generates statistical graphs and reports from the basic data provided by the production operation level, providing data-driven decision-making support for management (as shown in the figure).
1) Using ForceControl 6.1 SCADA software as the monitoring center and ForceControl real-time historical database pSpace as the core, an I/OServer real-time data server is established to realize online data monitoring, collect and process various data of the oil depot, and provide a safe, reliable and effective data platform for the oil depot's information system.
2) Industrial-grade Ethernet switches are used to establish a regional redundant ring network. The rings are connected by a coupled topology to establish a highly reliable dedicated energy data acquisition and communication network.
3) The pSafetyLink isolation gateway server is used to isolate the collection of various parameters from the production control system of the oil depot, providing continuous, accurate, and reliable data. pSafetyLink is a protection facility specifically designed for industrial network applications, used to solve the problem of how industrial SCADA control networks can securely access information networks (external networks). Its fundamental difference from network security devices such as firewalls is that it blocks direct network connections, only completing the exchange of specific industrial application data. Because there is no network connection, attacks have no medium, much like "physical isolation" of the network. Due to current security technologies, neither firewalls nor UTM protection systems can guarantee complete blocking of attacks, and intrusion detection and other monitoring systems cannot guarantee complete capture of intrusion behavior; therefore, the safest approach is physical separation.
IV. System Functions
The oil depot production operation system consists of five parts: automatic oil dispensing subsystem, tank area monitoring subsystem, integrated metering subsystem, equipment management system, and security monitoring subsystem. The security monitoring subsystem includes three parts: combustible gas monitoring, video monitoring, and electronic inspection.
4.1 Automatic Oil Dispensing Subsystem
The system implements the following functions:
1) Operation management functions.
a. Set three levels of passwords: system administrator password, administrator password, and operator password, with the system administrator being the highest level.
b. All important operations require password confirmation before execution. Operator IDs, operation details, and operation times are all recorded. Only administrators with passwords have the authority to retrieve, display, or print the operation logs. This is designed to investigate the cause of incidents; no one can modify the log content.
c. All important events (including alarms) are automatically recorded, including the event details and the time of occurrence. These records can be retrieved and displayed or printed at any time using an operator's password, but no one may modify the recorded content.
d. System operations such as modifying user permissions, control parameters, flow coefficients, report generation time, and printing operation logs all require the system administrator's password.
2) The fuel dispensing monitoring station and the fuel dispensing PLC control station communicate in real time via MPI to achieve centralized monitoring and management of quantitative loading;
3) The PLC control station realizes the automation of quantitative loading process control, has the function of automatically measuring the oil flow rate in the pipeline during loading, realizes the self-adaptive control function, and ensures high-precision loading control.
4) The system can control the oil dispensing in two metering methods: liters or kilograms. It has a dynamic temperature compensation function and realizes two oil dispensing metering functions.
5) The system has two oil dispensing operation modes: automatic and manual, which are available for both control room and field use, allowing users to choose whichever mode they prefer.
6) It realizes functions such as oil spill protection, static electricity protection, overspeed protection, over-temperature protection, and dual protection in the field and control room to ensure the safety and reliability of the system.
7) Event logging and access control functions; the operator station records abnormal alarm events that occur at the oil handling site, as well as operator logins and modifications to important system parameters, and these records are unmodifiable.
8) Set up a digital display screen on site to synchronously display the fuel loading value for easy on-site viewing.
9) Utilize dedicated configuration software to achieve dynamic and intuitive display and monitoring functions of various simulated screens.
10) The system has comprehensive management functions, which can automatically generate, query and output class reports, daily reports, monthly reports, annual reports, comprehensive reports and error reports, and has key management functions at all levels.
11) The PLC control station can transmit the loading production data to the data server via the warehouse Ethernet.
12) The system has strong control scale and functional expansion capabilities, and can arbitrarily expand the number of oil crane positions to increase control and management functions.
13) The system has a fault self-diagnosis function and an operation alarm function.
4.2 Tank Farm Monitoring System
The tank farm automation system has the same structure as the oil dispensing control system. Both systems use an operator station and a control station connected to the oil depot's local area network (LAN) via a network interface, with the LAN serving as the data transmission medium between the operator station and the control station. The host computer uses ForceControl 6.1 monitoring and configuration software.
The main functions implemented are as follows:
(1) Operation and management functions: Same as loading system
(2) Interface display function:
a. The operator station display shows the tank farm monitoring screen, operation prompts, and alarm information in real time.
b. Any alarm information that occurs at any time will be immediately reported in Chinese characters in a prominent area, and an alarm sound will be generated at the same time.
c. All operations are prompted with Chinese characters or graphics, using menus and buttons for selection, which is convenient and simple, and operators can operate without special training.
d. The system provides the following display area:
Overall liquid level view: The liquid level simulation bar of all storage tanks in the tank area, with the liquid level, temperature, volume, weight values of each tank and the estimated time for the liquid level to reach the set limit marked with numbers.
Process: Divide the area into zones by region and oil type, display storage tanks, pipelines, valves, pumps, simulate the liquid level in the tank, and label the liquid level and temperature. The valves and pumps are marked with colors to indicate their on/off status.
Tank parameters: One chart for each tank, including the tank's geometric dimensions, safety height, liquid level, temperature, set limits for liquid level and temperature, time to reach the limit, volume, specific gravity, weight, name of the stored material, simulated liquid level and temperature bar chart for the tank, etc.
e. Event Log: A pop-up displays production events that occurred on a specific day that have been logged in, such as alarms, machine start/stop times, communication failures, equipment malfunctions, etc.
f. Operation Log: Displays important operations that occurred on a specific day by popping up with a special password.
g. Real-time time: Always displayed on the screen.
(3) Remote monitoring function: Production operators can remotely monitor the electric ball valves in the tank area from the tank area operation station.
(4) Dynamic monitoring: liquid level, single-point temperature, oil leakage, quality, inventory, oil inflow, oil outflow, total volume, actual volume, and empty volume of the storage tank.
(5) Tank farm operation functions
a. Payment and receipt operations
The receiving and payment operation mainly completes the receiving and dispatching of oil from storage tanks. Based on the pre-tank and post-tank related data for each operation, it obtains the tank volume and its corresponding table volume for that operation, and completes the storage, printing and query functions of the operation records.
Complete the basic information of the tank operation based on the bill of lading number, the type and direction of the collection/payment operation, the inspector, and the time.
The system automatically or manually acquires the tank's liquid level, temperature, density, and draft height. Based on this data and the material properties in the tank, it automatically calculates the tank capacity and volume. Additionally, it manually or automatically records the corresponding flow meter number and reading. All this information is then entered into the database.
b. Inventory check
The inventory system is a tool that collects data such as oil level, water level, temperature, and density from manual/automatic extraction tanks at fixed times each day (as determined by the user), automatically calculates tank capacity and volume, and stores, prints, and queries the data.
c. Comparison of work data
Operational data comparison refers to comparing the tank volume corresponding to this operation station with the flow meter reading, truck measurement, and tank truck volume to obtain the difference in operation volume. The comparison results can be stored, printed, queried, and traced.
(6) The liquid level and inventory of the entire tank area are published and monitored online in real time within the local area network.
(7) Alarms and events: The system can provide high and low limit alarms for liquid level and temperature; provide audible and visual prompts when alarm information is detected, and provide alarm confirmation function; the system automatically records alarm content, occurrence time, on-duty operator and other information; the system allows advanced users to define and modify alarms and events; when the fire water tank alarms, the water supply switch of the water tank will automatically open to replenish water.
(8) Reporting function: query, report, print and output of dynamic registration form for each tank/single tank dynamic registration form/single tank operating condition record/oil metering shift report/daily report/monthly report/annual report.
(9) Generate daily sales/inventory reports and profit and loss data analysis for oil tank farms based on oil sales data.
(10) Data storage and archiving: The system can periodically sample and store the process data of the storage tank (liquid level, temperature, oil volume, mass, remaining tank capacity, etc.) (the sampling period can be defined) or periodically (daily, monthly, yearly) inventory and archive.
(11) Tank level interlock alarm.
Each oil tank is equipped with high and low level alarms. When the low level alarm is triggered, the oil pump is interlocked to stop oil delivery. When the high level alarm is triggered, the unloading pump is interlocked to stop unloading oil into the storage tank. There is also an alarm for faulty electrically controlled valves. Any alarm will be accompanied by an audible and visual prompt in the control room, and an alarm confirmation function will be provided. The system automatically records the alarm content, time of occurrence, and operator on duty. Advanced users are allowed to define and modify alarms and events.
(12) Event query function: query the process alarm status and query the tank entry and exit transfer events.
(13) Data management and operation key settings.
4.3 Integrated Metering System
Oil product metering at Oil Depot 725 is divided into three parts: incoming oil metering, outgoing oil metering, and inventory metering. Currently, all three metering processes rely on manual measurement and data management. This upgrade involves implementing a new integrated oil depot metering system. This system combines client/server (C/S) and browser/server (B/S) architectures based on force control monitoring configuration software. It automatically collects data from the existing production operation system and inputs manual metering data, enabling computerized management of the oil depot's physical metering records.
The integrated metering management system provides oil depots with two methods for data entry: manual input and automatic extraction, meeting the current usage and future development requirements of the oil depots.
4.4 Security Monitoring System
4.4.1 Gas Detection
Because the products handled at the oil depot are flammable and explosive, constant concentration monitoring of combustible gases is extremely important to ensure the safety of the storage area. The oil depot currently has one combustible gas alarm detection system with 34 monitoring points on tanks 1-17 and one on the pump room, totaling 35 monitoring points. This design proposes to install two gas alarms on the newly built vehicle-mounted oil dispensing platform and two gas alarms on the two newly built storage tanks. The gas alarms will be the same model as the existing ones. The monitoring software will be ForceControl 6.1.
It mainly implements the following functions:
1) Real-time detection and dynamic simulation monitoring of combustible gas concentration;
2) Gas concentration exceeding the standard alarm function;
3) Alarm record storage and tracing function;
4) Gas detection alarm and production safety interlock function;
4.4.2 Video Surveillance
The system employs advanced digital processing technology, resulting in higher image quality and easier image storage. Images can be remotely transmitted via network devices, enabling functions such as remote image monitoring and remote control.
The system software provides powerful image processing capabilities, adjusting image brightness and contrast, and can obtain high-quality images of monitored objects even in very low lighting conditions. It can also save images in a universal format for further processing in professional image processing software.
Combining current advanced IT technologies, ForceCtrol 6.1 monitoring configuration software, based on SOA architecture and .NET platform technology, supports B/S and C/S hybrid modes, achieving seamless integration with video surveillance and multimedia, and realizing the organic combination of data and video.
4.5 Oil depot purchase, sales, and inventory management and decision-making functions
Oil depot integrated information management mainly refers to storing, integrating, and utilizing production data from the three business processes of oil depot production—inbound, sales, and inventory—to generate various business reports that are beneficial to production management.
The central monitoring center has redundant ForceControl real-time database pSace servers, responsible for collecting real-time data from various subsystems of the oil depot. This data generates statistical graphs and reports for the business management and decision-making levels, providing data-driven decision-making support. The monitoring center provides secure and efficient data to higher-level departments via the ForceControl security isolation gateway pSafetylink in either a client/server or browser/server architecture.
V. Project Summary
This renovation of the Tibet 725 oil depot not only improved the automation system at the operational level but also established an information network system based on the refined oil depot management system. Centered on business management, equipment management, and safety management, the system covers all aspects of the oil depot. This effectively helps the company improve work efficiency, close management loopholes, improve service quality, reduce costs, increase revenue, and enhance its competitiveness.
