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Runpower Heating Industry Solutions
In modern heating systems, heat exchange stations play a pivotal role by utilizing centrally supplied heat sources, such as hot water or steam, as the heating medium. These stations distribute heat to targeted areas through a network of circulating hot water pipes. To ensure efficient and reliable operation, various sensors are employed to gather real-time data from within the heat exchange station. This data is then transmitted to a Runpower PLC (Programmable Logic Controller) for acquisition and control. The PLC, in turn, displays and allows for the adjustment of operational parameters through a touchscreen interface.
Based on the collected data, the PLC automatically executes control strategies, incorporating intelligent algorithms to regulate actuators and achieve precise control of secondary network supply and return water temperatures, pressures, and other critical parameters. This enhanced automation significantly improves the stability and reliability of the heat exchange station, ultimately enabling unmanned operation.
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Automation and Remote Monitoring of Heat Exchange Stations in Heating Systems
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Furthermore, the PLC control system within the heat exchange station utilizes diverse communication methods, including Ethernet, 4G, serial ports, and wireless radio frequencies, to transmit operational data to a regional heat network dispatch center. The Runpower PLC, coupled with a supervisory software system, allows administrators to remotely monitor and manage the regional heat network, including the heat exchange stations. Through extensive data analysis, this software aids in scheduling and maintaining the stations, enabling remote supervision and maintenance without the need for onsite personnel, thus realizing unmanned heat exchange stations.
Automation and Remote Monitoring in Unattended Heat Exchange Stations for Enhanced Heating Efficiency
Amidst the steady growth of the national economy and the subsequent improvement in residents' living standards, centralized heating has emerged as a prominent trend in residential heating systems due to its remarkable advantages in energy conservation and environmental protection. Traditionally, the operational parameters of secondary heat exchange stations have been manually adjusted to meet varying heating demands. However, with constant fluctuations in outdoor temperatures and heating requirements, frequent manual adjustments are necessary to maintain the secondary water supply temperature at acceptable levels. Such manual adjustments, relying solely on empirical values, often result in crude adjustments that fail to consistently maintain stable indoor temperatures for users. Additionally, this approach leads to high operational costs and low energy efficiency in the heating network.
To address these challenges, the heating industry has been exploring the development of automatic and efficient regulation methods that can adapt to varying heat loads. The aim is to achieve stable and reliable operation of heat exchange stations while also enabling unattended operation, ultimately delivering superior heating performance and economic efficiency. With the advancing automation technology, newly constructed and retrofitted heat exchange stations have increasingly adopted advanced unattended automatic control techniques. This has significantly improved the stations' management, maintenance, energy efficiency, and safety, marking a inevitable trend towards automation, intelligence, and informatization in heat exchange station control.
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The unattended heat exchange station monitoring system based on Runpower PLC offers a comprehensive solution. It not only ensures stable and reliable operation of the heat exchange stations without the need for personnel onsite, but also enables remote monitoring of real-time operational data. This allows for remote maintenance and dispatch management, greatly enhancing operational efficiency. The Runpower PLC, with its single CPU equipped with multiple communication interfaces and powerful expansion modules capable of handling up to 200 analog points, offers high precision in analog data acquisition and control, making it an ideal choice for unattended automatic control systems in heat exchange stations.
Introduction to the Heat Exchange Station System
The heat exchange station, also known as the secondary heat exchange station, serves as the core component of the heating network system. Its primary function is to transfer the heat from the primary side's steam or high-temperature water to the heating water that directly reaches the end-users. Typically, a heat exchange station comprises four main subsystems: a heat exchanger system for heat transfer, a circulating water pump system for fluid circulation, a makeup water pump system for replenishment, and a PLC and control cabinet-based control system for operational management.
The regional heating network dispatch center is responsible for overseeing and managing the regional heat sources, such as boiler rooms, as well as the heat exchange stations. Through an upper-level computer monitoring system, it performs remote monitoring and management of the heat sources and heat exchange stations within the designated area.
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In unmanned heat exchange stations, the control process primarily involves the PLC collecting operational parameters within the station. These parameters include supply and return water temperatures and pressures on both the primary and secondary sides, outdoor temperature, cumulative heat quantity, instantaneous flow rate, and three-phase electrical parameters. Based on these data, the PLC performs variable frequency and fixed-frequency control of the circulating pumps and makeup pumps. The operational status and parameters are then uploaded to the heating network dispatch center through various communication protocols such as Ethernet, 4G, serial ports, and wireless radio frequencies for scheduling analysis.
Overall Design of the Control System
The unmanned heat exchange station monitoring system constitutes a multi-layered and complex control framework. Its primary objectives are twofold: firstly, to achieve automatic control and unmanned operation of the heat exchange station; secondly, to transmit the operational parameters and status of the station to the regional dispatch center for unified management and scheduling.
The PLC plays a pivotal role in ensuring the stable and reliable operation of the systems within the heat exchange station. It regulates the flow rate on the primary side based on outdoor temperature measurements from temperature sensors or user-set temperatures, thereby controlling the secondary supply water temperature and enhancing heating quality. Additionally, the PLC controls the secondary supply water pressure through water pressure sensors and variable frequency drives (VFDs) for the circulating pumps, and the secondary return water pressure through return water pressure sensors and VFDs for the makeup pumps.
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The operational program of the heat exchange station resides independently within its PLC control system, enabling it to operate standalone without reliance on the supervisory control software on the upper computer. However, the operational status can be observed and adjustments can be made through the central control room's supervisory management system. While achieving unmanned operation, the system transmits operational status data to the supervisory management system for reference and accepts remote parameter adjustments from the management software.
The overall system control scheme is illustrated in Figure 1 below.
Typical PLC System for heat exchange station
(1) Secondary Network Water Supply Temperature Control: The PLC collects data on the supply and return water pressure and temperature from the primary pipeline network. It establishes mathematical models, such as constant temperature models and dynamic temperature models, by correlating these data with environmental temperature, target temperature, and pressure for the primary supply and return water. Utilizing intelligent PID algorithms, the PLC controls the opening of the primary side regulating valves to regulate the secondary side water supply temperature.
(2) Secondary Network Water Supply Pressure Control: Similarly, the PLC gathers data on the supply and return water pressure and temperature from the secondary pipeline network. It establishes mathematical models, including constant pressure models and pressure difference models, based on these readings along with environmental temperature and target temperature and pressure for the secondary side. The PLC employs intelligent PID algorithms to adjust the frequency and mode switching of the secondary side circulating pumps, thereby regulating the secondary side water supply pressure or the supply and return water pressure difference.
Main Functions of Automatic Control
(3) Secondary Network Return Water Pressure Control: The return water pressure in the secondary network is controlled through the makeup water pumps. If the actual pressure value differs from the set value, the PLC adjusts the frequency of the variable frequency drive (VFD) controlling the makeup pumps using PID calculations. This modifies the actual return water pressure in the secondary network to match the set value. A typical monitoring interface for a heat exchange station system is depicted in Figure 2.
(4) Depending on local climatic conditions and the characteristics of the heating targets, multiple corresponding curves between outdoor temperature and secondary supply water temperature are established. The PLC utilizes these curves to control the primary water supply flow based on outdoor temperature measurements obtained from sensors, implementing outdoor temperature compensation control. This aims to regulate the secondary supply water temperature, conserve energy, and enhance heating quality. An example of field curve settings for a typical heat exchange station is shown in Figure 3.
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Figure 2. Heat exchange station monitoring interface
Figure 3. Curve setting interface
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(5) The system incorporates an energy-saving setting for nighttime, allowing the setting of desired heating temperatures during this period. The automatic control system achieves different temperature settings at different times of the day through the integration of a time schedule.
(6) Through multi-channel communication interfaces, the PLC collects data from intelligent field instruments, such as three-phase multi-function meters, heat meters, and water meters. This data is used to automatically measure water replenishment, electricity consumption, and heat production at each heat exchange station, facilitating the evaluation of system efficiency, understanding system losses, and operational costs. The upper-level computer system compiles energy consumption statistics and provides curve charts and reports to assist managers in energy-saving scheduling.
(7) The PLC control system utilizes GPRSDTU for remote data transmission. Through the public network, it uploads field operational status, data, and intelligent instrument readings via GPRS to a centralized management center for operational maintenance and scheduling. The platform leverages advanced information technology, automation, and the Internet of Things to achieve visualization, quantification, and intelligent analysis of energy consumption. It enables data collection, monitoring, energy consumption diagnosis, equipment efficiency analysis, and indicator management for various energy uses, subsystems, zones, and critical equipment within individual thermal stations. This fine-grained energy consumption control optimizes equipment operation and reduces energy consumption.
(8) Auxiliary Protective Functions: If the system pressure falls below the preset lower limit, the circulating water pumps automatically shut down to prevent dry running. Simultaneously, the primary side thermal media temperature control valve closes automatically when the circulating pumps stop operating. The system provides audible and visual alarms for operational status excursions, equipment malfunctions, undervoltage leaks, and other faults.
(9) Other Control Strategies: One such strategy is the control of pressure relief valves based on system return water pressure. When the return water pressure exceeds the set upper limit for pressure relief, an electromagnetic pressure relief valve opens to decompress the circulating water system. Conversely, when the system return water pressure falls below the set lower limit for pressure relief, the electromagnetic valve closes.
The unattended heat exchange station monitoring system based on the Runpower PLC is user-friendly and widely applied in heat exchange station fields. It can operate stably and reliably for extended periods in damp and enclosed high-temperature environments.
Runpower PLC typical application site
(1) Beijing Heat
(2) Tianjin Heat
(3) Changchun Heat
Industries Served
RUNPOWER PLC has been applied in a wide range of industries and automation processes, including those mentioned above such as coal mining, public railway automation, metal processing, water treatment, Heating, ventilation and air conditioning (HVAC) industry, heating industry, transformer substations, smart factories, and so on.
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ABOUT US
Runpower is a high-tech enterprise in automation industries, specializes in a multitude of core technologies including computing, communication, signal processing, embedded software, system monitoring software, industrial internet, and automatic control. Renowned for our RPC3000 series PLC, RPC2000 series PLC, and various specialized automation products, our solutions find widespread applications across industries such as coal, metallurgy, power, petrochemicals, municipal services, transportation, environmental protection, construction, water conservancy, and agriculture. Emphasizing independently developed automation products and an in-depth understanding of industry applications, Runpower offers comprehensive automation solutions encompassing system planning, design, product development, and technical services. Leveraging our technological strengths, we foster deep collaboration with clients and partners, collectively enhancing competitive advantages within the industry chain. Committed to delivering high-quality products and efficient services, we strive for sustainable and healthy company growth, continuously elevating core competitiveness and brand value. Awarded the title of "Top Ten Emerging Companies in China's Automation Field" by the China Automation Society in 2016 and listed in the Ministry of Industry and Information Technology's comprehensive application program for Programmable Logic Controllers (PLC) in the Industrial Foundation Strengthening Project in 2018, Runpower possesses a rich technical background and extensive work experience in product development, production management, quality control, market promotion, industry application, and technical services. Learn more