Pulverized coal distributor distribution accuracy

The distribution accuracy of the pulverized coal distributor (i.e., the deviation in coal flow rate among branch pipes) directly determines the uniformity of coal injection at each blast furnace tuyere, thereby affecting furnace stability and ironmaking efficiency. Its accuracy is influenced by four major categories of factors: structural design, fluid dynamics characteristics, material properties, and system operating parameters. A detailed analysis is as follows:

 1. Structural Design Factors: The "Inherent Determinants" of Distribution Accuracy The structural parameters of the distributor are the core factors affecting accuracy. Unreasonable structural design can directly lead to uneven coal distribution, mainly including the following dimensions: 1. Main Structural Form Different structural types of distributors (such as conical, disc-type, and Venturi-type) exhibit significant differences in their ability to guide airflow and disperse pulverized coal:

 • Conical Distributor: Relies on the vortex effect within the conical cavity to disperse pulverized coal. If the cone angle is improperly designed (too large, causing airflow to directly impact branch pipes; too small, leading to coal accumulation), branch pipes near the inlet will have more coal flow, while those farther away will have less, with distribution errors potentially exceeding 10%.

 • Disc-type Distributor: Distributes pulverized coal through small holes on a disc. If the hole diameters are inconsistent or asymmetrically distributed, differences in airflow resistance among holes will occur, leading to increased deviation in coal flow rates. • Venturi-type Distributor: Utilizes the throttling effect of the Venturi tube to accelerate airflow. If the throat diameter does not match the branch pipes properly, uneven negative pressure at the branch pipe inlets will cause imbalanced coal distribution. 2. Branch Pipe Design Parameters Branch pipes are the "final outlets" for coal distribution, and their layout, size, and angle directly affect flow uniformity:

 • Symmetry of Branch Pipe Arrangement: If branch pipes are not uniformly and symmetrically distributed along the main body of the distributor (e.g., conical axis), such as with angle deviations >5° or unequal spacing, airflow distribution within the cavity will be uneven. Branch pipes on the inlet side typically have 20%-30% more coal flow than those on the opposite side.

 • Branch Pipe Diameter and Number: Inconsistent branch pipe diameters (e.g., design errors >2mm) will cause resistance differences, with larger-diameter pipes having higher flow rates. If the number of branch pipes is excessive (e.g., over 35) and the cavity volume is not proportionally enlarged, insufficient space for airflow dispersion will reduce distribution accuracy.

 • Branch Pipe Inlet Angle: If the angles between branch pipes and the distributor body are not uniform (e.g., some at 90°, some at 120°), the velocity direction of coal entering the branch pipes will change, resulting in higher flow rates in "forward-facing" pipes (aligned with airflow direction) and lower rates in "reverse-facing" pipes. 3. Inlet and Cavity Compatibility The connection method between the distributor inlet pipe and the cavity directly affects the initial distribution of airflow:

 • Inlet Pipe Diameter to Cavity Diameter Ratio: If the inlet pipe diameter is too large (e.g., inlet/cavity diameter ratio >0.5), airflow will struggle to fully diffuse upon entering the cavity, easily forming a "jet effect" that directly impacts opposite branch pipes. If the inlet pipe diameter is too small, insufficient pressure within the cavity will weaken coal dispersion. • Inlet Pipe Verticality/Coaxiality: If the inlet pipe is not coaxial with the distributor cavity (deviation >3mm), airflow will偏向一侧, causing significantly higher coal flow in branch pipes on that side, with distribution errors potentially exceeding 15%.