Marine Centrifugal Sewage Pump

I. Product Overview

Marine centrifugal sewage pumps are core equipment in ship sewage treatment systems, designed specifically to transport mixed liquids such as domestic sewage, kitchen wastewater, engine room oily sewage, and small amounts of solid impurities. They prevent sewage accumulation from polluting cabins and ensure compliance with discharge regulations. Constructed with cast iron (HT250) or stainless steel (316L) as the main material, they generate pressure through high-speed rotation of centrifugal impellers to draw sewage from collection tanks, pressurize it, and deliver it to sewage treatment devices or overboard (after reaching discharge standards) after being filtered by screens. The pump body undergoes anti-corrosion treatment and precision machining, with a corrosion-resistant service life of ≥8 years in freshwater, low-salinity seawater, and oily sewage environments. It meets IMO Ship Domestic Sewage Treatment System Specifications (MEPC.227(64)) and sewage equipment certification requirements of classification societies such as RS, LR, ABS, and CCS, widely used in sewage treatment systems of passenger ships, cargo ships, fishing boats, and other vessel types.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

2.Key Technical Parameters

Flow range: 3-100m³/h, suitable for 50-5000 ship occupants (e.g., 1000-passenger ships require flow ≥10m³/h)

Head coverage: 10-40m, meeting pressure requirements for transportation from sewage tanks to treatment devices (including pipeline elbows and grille resistance losses)

Medium compatibility: Capable of conveying domestic sewage (solid content ≤5%), kitchen wastewater (with food residues), engine room oily sewage (oil content ≤10%), and mixed sewage with temperature ≤60℃

Anti-clogging capability: Can pass solid particles ≤15mm in diameter (e.g., bone fragments, fibrous impurities), reducing clogging rates by 70% compared to ordinary centrifugal pumps

Self-priming performance: Self-priming models have a suction lift ≥4m and priming time ≤60 seconds, suitable for water absorption from low-level sewage tanks without manual priming

3.Safety and Anti-Pollution Design

Liquid level linkage control: Equipped with electronic liquid level sensors, automatically starting when sewage tank level ≥300mm and stopping when ≤100mm to prevent pump damage from dry operation

Stepped filtration system: Inlet fitted with coarse filters (15mm aperture) to intercept large impurities and fine filters (5mm aperture) to filter small particles, cooperating with cutting impellers to crush fibrous impurities

Explosion-proof design: Motor adopts Ex d IIB T4 explosion-proof grade, suitable for Zone 2 hazardous areas such as engine rooms to prevent safety risks from mixing of oil and gas with sewage

III. Technical Advantages and Innovative Design

1. High-Impurity Sewage Conveying Capacity

Cutting impeller: Uses double-blade serrated impellers to crush solid impurities ≤20mm in diameter (e.g., plastic fragments, food residues) with a crushing efficiency ≥95%, avoiding clogging from fiber entanglement.

Wide-channel design: Flow channel cross-sectional area is 30% larger than ordinary centrifugal pumps, with flow velocity controlled at 1.5-2.5m/s, preventing impurity deposition while reducing energy consumption (12% more efficient than conventional pumps).

2. Corrosion Resistance and Wear Resistance Enhancement

Stainless steel flow components: 316L impellers and pump casings undergo solution treatment, with a pitting resistance equivalent (PREN) ≥35, showing no significant rust after 2000-hour immersion in a 5% salt spray + 5% oil mixture environment.

Cast iron pump anti-corrosion coating: HT250 pump inner walls are sprayed with epoxy resin coating (thickness ≥0.3mm) with adhesion ≥5MPa and salt spray resistance up to 1000 hours, extending maintenance intervals for inland ships to 1 year.

3. Adaptation to Ship Sewage Characteristics

Dry-wet separation structure: Motor and pump body adopt a mechanical seal + isolation chamber design, completely isolating sewage from the motor to prevent motor burnout from liquid leakage, extending seal life to 8000 hours.

Low-noise operation design: Impellers and volutes are optimized for dynamic and static balance, with operating noise ≤75dB (at 1 meter), cooperating with rubber shock pads to meet passenger cabin noise requirements (≤60dB).

IV. Typical Application Scenarios

1. Domestic Sewage Treatment

Centralized sewage discharge for passenger ships: 3000-passenger ships are equipped with stainless steel centrifugal sewage pumps (flow 20-30m³/h, head 25m) to transport bathroom and toilet sewage to biochemical treatment devices. Impellers cut hair, paper towels, and other fibrous impurities to ensure stable operation of the treatment system.

Domestic sewage discharge for fishing boats: Offshore fishing boats use cast iron sewage pumps (flow 5-10m³/h) to discharge kitchen and toilet sewage, cooperating with simple filtration devices to meet coastal navigation discharge requirements (COD ≤125mg/L).

2. Engine Room and Special Sewage Conveyance

Engine room oily sewage treatment: Cargo ship engine rooms are equipped with explosion-proof stainless steel sewage pumps (flow 15-25m³/h, head 20m) to transport oily sewage to oil-water separators, with effluent oil content ≤15ppm after separation, meeting MARPOL Annex I requirements.

Kitchen wastewater treatment: Cruise ship kitchens use cutting-type centrifugal sewage pumps (flow 10-15m³/h) to crush food residues (e.g., bones, fruit peels) before delivering them to oil separators, preventing pipeline blockages.

3. Extreme Environment Adaptation

Tropical high-humidity environment: In 45℃ high-temperature environments, stainless steel sewage pumps with heat sinks can operate continuously, controlling motor temperature ≤75℃ and maintaining flow at ≥95% of the rated value.

Polar low-temperature sewage: In -20℃ environments, sewage pumps with heating jackets can transport 0℃ domestic sewage (preventing freezing) at 8-15m³/h, ensuring normal operation of research vessel sewage treatment systems.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Sewage type: Cast iron pumps for domestic sewage and inland ships; stainless steel pumps for oily sewage and coastal ships

Flow calculation: Configure 150L per person per day for domestic sewage; e.g., 500-person ships require flow ≥75m³/d (3.1m³/h)

Installation scenarios: Low-noise models for passenger ships; explosion-proof models for engine rooms; compact models (length ≤1.2m) for narrow spaces

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa), bearing temperature (≤70℃), and seal leakage (≤5mL/h) every 500 hours

Regular maintenance: Clean inlet filters weekly; replace mechanical seals (oil-resistant fluoroelastomer) every 1500 hours; inspect impeller wear (allowable radial clearance ≤0.5mm)

In-depth maintenance: Disassemble and inspect every 2 years; perform acid pickling and passivation on stainless steel components; spray anti-corrosion coating on cast iron components; test crushing capability of cutting impellers (ensuring ≥90%)

VI. Compliance and Certification

International standards: Complies with IMO MEPC.227(64) domestic sewage discharge requirements and ISO 14001 environmental equipment standards

Classification society certifications: Passed type approval for sewage pumps by RS, LR, ABS, and CCS (including 1000-hour oily sewage operation tests)

Discharge compliance: When used with sewage treatment devices, effluent quality meets MARPOL Annex IV requirements (BOD ≤50mg/L, suspended solids ≤50mg/L)