Challenges of Thermal Power Unit Peak Regulation in the Evolving Energy Landscape

In recent years, China's power generation mix has undergone significant changes, with renewable energy capacity accounting for an increasingly larger share. To ensure grid stability, thermal power units must perform deep peak regulation to complement intermittent renewable generation, while simultaneously responding flexibly to grid dispatch commands according to load variations.

However, the conventional one-to-one design paradigm of pulverizing systems (where each coal bunker feeds a single coal mill) fails to meet the flexible load-ramping requirements of modern thermal units. This limitation has emerged as a critical bottleneck constraining the efficient operation of thermal power plants.

Intelligent Coal Blending System for Deep Peak Regulation: An Innovative Solution

To address these challenges, Datong Longyuan has developed an Intelligent Coal Blending System for Deep Peak Regulation. The system prioritizes bunker structural safety and stability in its design, rejecting the commonly-used external mini-bunker approach in favor of an innovative buffer bunker concept. This design effectively mitigates structural strength risks caused by load variations while reducing the probability of fuel spontaneous combustion and compaction, thereby ensuring long-term stable system operation.

The intelligent control system equipped in the system can precisely manage coal type switching without modifying the main logic of the power plant. Under different load conditions, it can not only ensure stable boiler combustion to meet the requirement of the unit for quickly reaching full load, but also optimize the coal combustion cost during deep peak shaving to reduce the economic burden of thermal power plants.

One-to-Three Retrofit Solution: Core Principles of Intelligent Coal Blending System

Taking the PC-fired tangential burner boiler configuration as an example, to ensure combustion stability, Bunker A and B (serving the first and second burner levels) typically store high-calorific-value coal, while other bunkers are flexibly loaded based on fuel inventory. Some plants only store high-CV coal in Bunker B. This section details the intelligent coal blending system principles through a one-to-three retrofit solution.

1.System architecture construction: Install a discharge pipe at the upper part of the existing coal bunker, add a buffer bin at the lower part, and configure a scraper rotating blockage removal device to build a bidirectional conveying belt coal feeder system, realizing flexible coal blending for the pulverizing systems corresponding to three coal bunkers.

2.Optimization of high-calorific value coal supply: Considering that the B bunker in most power plants stores high-calorific value coal, two discharge pipes and corresponding buffer bins are added to the upper part of the B bunker, enabling the high-calorific value coal stored in one coal bunker to be shared by three pulverizing systems, which greatly improves the flexibility of coal feeding and operation in the power plant. Meanwhile, a set of discharge pipe and buffer bin system is added to the upper part of the A and C bunkers.

3.Raw coal bunker renovation and feeding optimization: Renovate the on-site raw coal bunker, design three feeding outlets for the bidirectional conveying belt coal feeder, which are respectively connected to the coal feeders of the A, B, and C pulverizing systems, and install a scraper rotating blockage removal device at the connection of the coal dropping pipe to effectively solve the problem of coal blocking.

4.Precise control of coal flow: The intelligent coal blending system uses the original coal feeder weighing system to control the coal flow without switching the operation mode, ensuring the stability and accuracy of coal flow control.

5.Flexible coal blending mode: The system can realize the blending of high-calorific value coal from the B bunker to the A and C bunkers individually or simultaneously, and the low-calorific value coal from the A and C bunkers can also be blended to the B bunker, or in combinations of A and B bunkers, or B and C bunkers, which greatly enhances the system's ability to adapt to unit peak shaving and load carrying.

6.System withdrawal guarantee: When the intelligent coal blending system is withdrawn from operation, all the coal inside the buffer bins can be emptied to avoid affecting the load and structural strength of the raw coal bunker and prevent safety accidents. At the same time, the coal feeder and the outlet coal dropping pipe will also be emptied to eliminate the problems of spontaneous combustion and caking caused by long-term coal accumulation.

7.New control means: The new control system provided by the system can effectively overcome the sudden disturbance of the calorific value of the coal entering the furnace during the fuel switching process, solving the control problem of combustion stability during the rapid switching of coal types.

The Outstanding Characteristics of the Deep Peak Shaving Intelligent Coal Blending System

The deep peak shaving intelligent coal blending system possesses a series of remarkable features, giving it prominent advantages in the field of peak shaving for thermal power units.

1.High coal blending flexibility: The system is simple and flexible, supporting bidirectional coal blending of high and low calorific value coals to meet the coal combustion requirements under different working conditions.

2.Safe and reliable structure: Adopting the design concept of buffer bins, it eliminates the potential safety hazards of structural strength caused by changes in external loads during the long-term operation of raw coal bunkers.

3.Prevention of fuel risks: The blocking design of the discharge pipe effectively avoids problems such as fuel spontaneous combustion, caking, and coal blocking caused by long-term shutdown of the newly added storage and transportation system.

4.Flexible interface design: The interface position with the original coal feeder is flexibly designed, not restricted by the space layout of the coal feeder platform, facilitating installation and renovation.

5.Stable combustion process: Fully considering the logical relationship between the fuel quantity of a single coal feeder and the total fuel quantity of the boiler, it avoids disturbances to boiler combustion caused by the switching of the coal blending system.

6.Enhanced anti-blocking function: Comprehensive anti-blocking design is carried out during coal blending transportation and storage to effectively prevent coal blocking.

Intelligent Control System: Boosting Efficient Operation of Thermal Power Units

The intelligent control system of the deep peak shaving intelligent coal blending system is one of its core advantages. Without modifying the main logic of the power plant, this system can precisely manage coal type switching to ensure stable combustion of the boiler under different load conditions. This not only meets the operation requirements for the unit to quickly reach full load but also optimizes coal combustion costs during deep peak shaving, effectively reducing the economic pressure on thermal power plants and providing strong support for the efficient and economical operation of thermal power units.