MatchingStandardSpecificationofCoalescingFilterFlowRate&PrecisionforAviationKeroseneDehydration1
Matching Standard Specification of Coalescing Filter Flow Rate & Precision
for Aviation Kerosene Dehydration
Aviation kerosene (Jet A-1/JP-8) refining and dehydration processes cover refinery finished product outlet, tank farm storage and transfer, pipeline transportation, airport fixed fuel supply facilities and aircraft refueling vehicles. Reliable Coalescer & Separator Cartridge is the key core component to purify aviation fuel, as the medium contains solid particulate pollutants (rust, catalyst debris, mineral fine powder, pipeline wear particles), free water and emulsified micro-water droplets. Excessive water and impurities will cause engine combustion failure, fuel system valve corrosion and filter screen blockage, so the Coalescer & Separator Cartridge needs to realize dual functions of particle interception and micro-water coalescence separation.
Core mandatory index limits stipulated by EI 1581 (revised from API 1581), GB/T 21357 and GJB 610:
Outlet free water content of fuel ≤15 ppm; coalescence removal efficiency for inlet water reaches ≥99.5% (inlet water mass fraction up to 0.2%);
Solid particle cleanliness complies with NAS 1638 Class 6 standard, interception efficiency βₓ≥1000 for rated precision particles;
The flux (flow capacity per unit filter area) and filtration accuracy must form a fixed matching relationship. Excessive flux under fixed precision will lead to shortened coalescence residence time, incomplete water droplet agglomeration, reduced particle interception efficiency and rapid pressure difference rise.
1.2 Definition of Core Parameters
Nominal filtration accuracy: Characterized by β value, standard grades for aviation kerosene coalescer: 0.3 μm, 0.5 μm, 1 μm, representing the minimum particle size with β≥1000 interception efficiency, and this parameter is the primary basis for selecting qualified Coalescer & Separator Cartridge;
Cartridge rated flux: Maximum allowable treatment flow under specified medium viscosity, temperature and initial pressure difference (initial ΔP＜0.03 MPa), unit: L/min per single cartridge, users need to match the flow rate according to the specification of each Coalescer & Separator Cartridge;
Area flux (surface flow rate): Flow passing through unit effective filter area, unit L/(min·㎡), the core matching control parameter linking precision and flow;
Coalescence residence time: Dwell time of aviation kerosene in multi-layer coalescence medium, minimum standard ≥0.8 s, directly determined by area flux.
The coalescence medium adopts multi-layer gradient hydrophilic glass fiber composite structure: outer coarse fiber layer intercepts large particles, middle transition layer pre-coalesces tiny water droplets, inner fine precision layer completes deep particle filtration and full water droplet agglomeration. The matching logic follows three physical constraints:
Residence time constraint: The finer the filtration accuracy, the smaller the medium pore size and the higher the flow resistance; if the area flux is too high, the fuel flow velocity rises, and micro-water droplets flow out of the medium without sufficient collision and agglomeration, resulting in excessive outlet water content.
Particle interception constraint: Fine-pore precision media has narrow flow channels; excessive flux increases fluid shear force, and intercepted fine particles are re-carried downstream by high-speed fuel, reducing actual filtration efficiency.
Pressure difference service life constraint: Excessive flux accelerates rapid accumulation of pollutants on the medium surface, shortens the cycle from initial pressure difference to replacement pressure difference (0.15 MPa), and increases cartridge replacement frequency.
Basic matching rule: The higher the filtration precision (smaller nominal μm value), the lower the allowable area flux, and the smaller the single-cartridge rated treatment flow under the same cartridge size.
All data are calibrated under standard working conditions: aviation kerosene viscosity 1.2–1.6 mm²/s, medium temperature 10–40 ℃, inlet water mass fraction ≤0.2%, initial pressure difference ≤0.03 MPa, complying with EI 1581 Category C Type S test conditions.
Applicable working sections: Refinery finished product terminal filtration, military high-standard fuel depot final refining, fuel supply before aircraft direct refueling (EI 1581 Category C low-pollution terminal working condition)
Core performance indicators: β₀.₃≥1000, water removal efficiency ≥99.9%, outlet free water ≤10 ppm
Allowable area flux upper limit: ≤35 L/(min·㎡)
Standard single-cartridge rated flux reference (φ152 mm × 1000 mm length, effective filter area 16 ㎡): ≤560 L/min
Matching limit correction: When inlet water content exceeds 0.1%, the allowable flux shall be reduced by 20% to ensure residence time ≥1.0 s
Applicable working sections: Intermediate transfer filtration of tank farm, long-distance pipeline intermediate station refining, conventional civil airport fuel storage outlet (EI 1581 Category B medium-pollution working condition)
Core performance indicators: β₀.₅≥1000, water removal efficiency ≥99.7%, outlet free water ≤12 ppm
Allowable area flux upper limit: ≤45 L/(min·㎡)
Standard single-cartridge rated flux reference (φ152 mm × 1000 mm length, effective filter area 16 ㎡): ≤720 L/min
Matching limit correction: When medium temperature exceeds 50 ℃ (viscosity decreases), the flux shall be reduced by 10% to weaken fluid shear force
When the working temperature exceeds 40 ℃, the viscosity of aviation kerosene decreases, fluid shear force increases, and the agglomeration stability of water droplets weakens. For all precision grades, the actual allowable flux shall be multiplied by a temperature correction coefficient:
40–60 ℃: coefficient 0.9;
60–80 ℃: coefficient 0.8;
Operating temperature above 80 ℃ is not recommended for long-term continuous operation of coalescer cartridges.
Classified by EI 1581 pollution grade, the flux reduction coefficient corresponding to each precision grade:
Category A (high water & high solid pollution): all grades ×0.75;
Category B (medium pollution): all grades ×0.85;
Category C (low terminal pollution): all grades ×1.0.
Pleated coalescer media has larger effective filter area than flat winding media under the same outer diameter and length; flat media flux shall be reduced by 30% compared with pleated media of the same precision to avoid exceeding area flux limit.
Step 1: Confirm system maximum continuous treatment flow Q (L/min);Step 2: Select coalescer cartridge precision grade according to working section pollution classification (0.3/0.5/1 μm);Step 3: Query the maximum allowable area flux q corresponding to the precision grade;Step 4: Calculate the minimum total effective filter area required for the system: A_total ≥ Q ÷ q;Step 5: Select single-cartridge effective filter area A₀, calculate minimum cartridge quantity N ≥ A_total ÷ A₀ (round up integer);Step 6: Apply temperature, pollution load correction coefficient to recheck the actual single-cartridge flow Q_single = Q ÷ N, confirm Q_single does not exceed the rated flux limit of the corresponding precision cartridge.
Calculation example: Airport terminal fuel supply system maximum flow 2400 L/min, select 0.5 μm precision cartridge, single-cartridge effective area 16 ㎡, allowable area flux 45 L/(min·㎡)Minimum total area A_total = 2400 ÷ 45 = 53.34 ㎡Minimum cartridge quantity N = 53.34 ÷ 16 ≈ 3.34, take 4 cartridgesActual single-cartridge flow = 2400 ÷ 4 = 600 L/min, lower than the rated upper limit 720 L/min of 0.5 μm cartridge, matching standard compliance.
Root cause: Area flux exceeds the upper limit of the corresponding precision grade, insufficient coalescence residence time; medium temperature is too high without flux reduction correction.Rectification measures: Increase the number of coalescer cartridges to reduce single-cartridge actual flux; install cooling equipment to control medium temperature below 40 ℃.
Root cause: Excessive flux causes fluid shear force to re-carry intercepted fine particles downstream; mismatched high-flow low-precision cartridge for terminal refining working section.Rectification measures: Upgrade to higher-precision coalescer cartridge; reduce system operating flow to meet area flux matching limit.
7. Daily Operation Monitoring Standard to Maintain Matching Performance
Real-time flow recording: Monitor system instantaneous flow, prohibit long-term operation exceeding the design maximum flow by more than 10%;
Pressure difference tracking: Record initial pressure difference of new cartridges and daily pressure difference growth rate; if the daily growth rate exceeds 0.01 MPa, check whether the flux exceeds the matching limit;
Regular water content sampling: Test outlet free water content every shift; once exceeding 15 ppm, prioritize checking flow and area flux matching status;
Seasonal correction: In high-temperature summer environments, reduce system operating flow by 10–20% according to temperature correction coefficient to ensure stable coalescence separation effect.
Matching Standard Specification of Coalescing Filter Flow Rate & Precision for Aviation Kerosene Dehydration
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