DL/T 775-2025 in English
VALIDTechnical Code for Ash and Slag Removal Control System in Thermal Power Plants
- Issued on:2025-06-30
- Implemented on:2025-12-30
- File Format:PDF
- Delivery:Via email within 5 business days
$466.00
| Standard No: | DL/T 775-2025 |
| Document status: | VALID |
| Title in English: | Technical Code for Ash and Slag Removal Control System in Thermal Power Plants |
| Title in Chinese: | 火力发电厂除灰除渣控制系统技术规程 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | Via email within 5 business days |
| Issued on: | 2025-06-30 |
| Implemented on: | 2025-12-30 |
| Chinese Classification: | F23-Power plant and electric power system operating maintenance |
| Professional Classification: | DL-Electricity |
Introduction
DL/T 775-2025 Standard Revision Background and Technological Evolution
DL/T 775-2025, "Technical Specification for Ash and Slag Handling Control Systems in Thermal Power Plants," a key technical standard for the power industry, has undergone a comprehensive revision based on the 2012 edition. This revision fully considers the development trends of digital power plants and intelligent control, with a focus on strengthening fieldbus technology, communication protocol standardization, and system reliability requirements.
The scope of application of the standard specifically targets ash and slag handling control systems for units of 300MW and above, while also providing a reference for smaller units. As the automation level of thermal power plants continues to improve, the standardization of control technology for ash and slag handling systems, as important auxiliary systems, is of great significance to ensuring the safe and stable operation of power plants.
Comparative analysis of technical requirements for control system hardware platforms
| Technical indicators | Programmable logic controller system | Distributed control system | Fieldbus control system |
|---|---|---|---|
| Redundancy configuration requirements | Data communication system, controller module, operator station, and power supply module should be redundantly configured | Data communication system, controller module, operator station, and power supply module should be redundantly configured | Increase fieldbus network redundancy according to PLC or DCS requirements |
| Processing capacity margin | Controller processing capacity 40% margin | Controller processing capacity 40% margin | Bus macrocycle matching needs to be considered |
| Memory margin | Internal memory 50% margin, external memory 60% margin | Internal memory 50% margin, external memory 60% margin | Device description file storage needs to be considered |
| Communication load rate | Ethernet ≤20%, other networks ≤40% | Ethernet ≤20%, other networks ≤40% | The impact range of bus failures needs to be assessed |
In-Depth Analysis of Fieldbus Technology Applications
The 2025 version of the standard features significant updates to fieldbus technology applications, clarifying the technical requirements for mainstream bus standards such as Profibus and FF_H1. Detailed regulations are provided for network segment configuration, the number of connected devices, and anti-interference measures.
Profibus Application Example
In the pneumatic conveying control of an ash handling system, Profibus DP is used to connect remote I/O stations. The transmission rate is set according to device requirements, and the maximum transmission distance is selected within the range of 100-1200 meters depending on the transmission rate. The number of devices connected to each PA segment should not exceed 60% of the maximum allowable value. The bus power supply capacity and I/O range must also be considered.
Fieldbus Anti-Interference Technical Requirements
The standard explicitly mandates seven anti-harmonic interference measures when connecting a VFD to a network segment. These include selecting an VFD that complies with EMC standards, physical isolation, independent power supply, filtering devices, dedicated cables, system grounding, and standardized cabling. These measures effectively address fieldbus stability issues in high-interference environments.
System Commissioning Technical Requirements and Implementation Key Points
Commissioning is divided into two phases: pre-startup commissioning and post-startup commissioning, covering the entire process from equipment inspection to system optimization. Before commissioning, ensure that the control system is correctly installed, the air supply is of qualified quality, and the cabling is properly laid.
| Debugging phase | Debugging content | Technical indicators | Acceptance criteria |
|---|---|---|---|
| Functional test after power-on | Controller redundancy, communication bus redundancy, power switching, module maintenance | No errors or freezes during switching | Stable system operation |
| Performance test | Signal accuracy, response time, system load rate | Screen response ≤2s, CPU load ≤60% | Meet operation requirements |
| Partial debugging | Program logic of each subsystem, equipment action sequence | Operate according to the designed program | Correct logical functions |
| Post-startup commissioning | Parameter optimization and operating mode verification | Suitability for load operation | System economical and reliable |
System acceptance standards and technical document requirements
The standard stipulates a strict acceptance indicator system. The availability of the ash and slag handling control system must not be less than 99.9%, the measurement point utilization rate must be greater than 99%, and the interlock protection utilization rate must reach 100%. New units should be accepted after 168 hours of continuous trial operation.
Technical document requirements include 9 major document categories, including design specifications, control strategy logic diagrams, instrument and control equipment lists, power distribution diagrams, and communication network wiring diagrams, to ensure system maintainability and traceability.
Standard Implementation Recommendations and Best Practices
Based on the technical requirements of DL/T 775-2025, it is recommended to focus on the following aspects during the implementation of ash and slag handling control systems:
Hardware Configuration Optimization Recommendations
Following the standard's margin configuration principle, in actual projects, it is recommended to retain a 50% margin for controller processing power (higher than the standard 40%) and a 70% margin for memory (higher than the standard 50-60%) to accommodate future system expansion needs.
Fieldbus Implementation Strategy
A hybrid architecture is recommended, with hardwiring for critical protection circuits and fieldbus for general monitoring. The number of devices on the Profibus PA segment should be limited to 50% of the maximum allowable value (lower than the standard 60%) to ensure system reliability.
Commissioning Process Quality Control
Establish a three-level acceptance system: single-unit commissioning acceptance, subsystem commissioning acceptance, and complete startup commissioning acceptance. Complete commissioning records and acceptance reports are generated for each stage to ensure a closed-loop quality control system.
The implementation of DL/T 775-2025 will significantly improve the standardization and operational reliability of ash and slag handling control systems in thermal power plants, providing technical support for the high-quality development of the power industry.
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