Marine Ejector Sewage Pump

I. Product Overview

Marine ejector sewage pumps are the "efficient sewage discharge core" of ship sewage treatment systems, designed specifically to collect and convey ship domestic sewage, kitchen wastewater, and engine room oily sewage. Through the ejector principle, they form negative pressure to suck in sewage containing feces, food residues, emulsified oil, and other impurities, which is then discharged to sewage treatment devices or overboard (after treatment) after mixing and pressurization. Without an impeller, they can handle complex sewage media with a solid content of ≤8%. Constructed with cast iron (HT250), wear-resistant cast iron (KmTBCr15Mo), or stainless steel (316L) as the main material, they rely on high-speed jet from the nozzle to generate vacuum suction in the mixing chamber, drawing sewage from the collection tank and conveying it under pressure, fundamentally solving the clogging issue of traditional centrifugal pumps. The pump body undergoes anti-corrosion and wear-resistant treatment, with a service life of ≥8 years in -5℃~60℃ environments. It meets IMO International Convention for the Prevention of Pollution from Ships (MARPOL Annex IV) and sewage pump certification requirements of classification societies such as RS, LR, ABS, and CCS, widely used in sewage treatment systems of passenger ships, cargo ships, oil tankers, and other vessel types.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

2.Key Technical Parameters

Flow range: 8-80m³/h, suitable for ships with 100-1000 personnel (e.g., 500-person passenger ships require flow ≥30m³/h)

Head coverage: 8-25m, meeting pressure requirements for transportation from sewage collection tanks to treatment devices (including filter and elbow resistance losses)

Medium compatibility: Capable of conveying domestic sewage (containing feces, toilet paper), kitchen wastewater (containing food residues), engine room oily sewage (oil content ≤15ppm), with temperatures ranging from -5℃ to 60℃, solid content ≤8% (particle diameter ≤10mm)

Self-priming performance: Self-priming height ≥5m, priming time ≤40 seconds, capable of directly drawing water from low-level sewage tanks without manual priming

Anti-clogging capability: Suction port diameter ≥80mm, combined with impeller-free design, achieving 95% passage rate for long fibers (≤50mm), plastic bags, and other impurities, with a clogging rate 85% lower than centrifugal pumps

3.Safety and Anti-Pollution Design

Explosion-proof certification: Motors of stainless steel pumps handling oily sewage adopt Ex d IIB T4 Gb explosion-proof grade, suitable for Zone 2 hazardous areas in engine rooms to prevent oil and gas explosions

Overload protection: Equipped with pressure sensors, automatically shutting down and alarming when pipeline pressure exceeds 1.5 times the rated value due to blockage, avoiding pump body damage

Anti-backflow design: A check valve installed at the outlet prevents sewage backflow to the collection tank after shutdown, avoiding secondary pollution

III. Technical Advantages and Innovative Design

1. Complex Sewage Conveying Capacity

Dual-nozzle ejector structure: Adopts a main nozzle (50mm diameter) + auxiliary nozzle (20mm diameter) design. The main nozzle generates negative pressure for sewage suction, while the auxiliary nozzle produces high-speed jets to break large impurities (e.g., food residues), increasing impurity passage rate by 40% compared to single-nozzle designs.

Wide-channel flow path: The flow path diameter gradually expands from 80mm to 120mm from suction port to discharge port, reducing turbulent resistance. Pressure loss for fiber-containing sewage ≤0.1MPa, 30% lower than centrifugal pumps of the same specification.

2. Wear Resistance and Corrosion Resistance Enhancement

Wear-resistant cast iron surface treatment: The inner wall of KmTBCr15Mo pump bodies is overlay-welded with a wear-resistant alloy layer (2mm thick) to achieve HRC55 hardness, doubling service life against fiber scratches compared to ordinary cast iron pumps.

Stainless steel anti-adhesion treatment: 316L flow components undergo sandblasting + Teflon coating (0.1mm thick) to reduce adhesion of oil and sludge, extending cleaning intervals to 500 hours and reducing maintenance frequency by 50% compared to ordinary stainless steel pumps.

3. Adaptability to Ship Operating Conditions

Compact design: Single unit weight ≤300kg (50m³/h model), 25% lighter than centrifugal pumps of the same flow, suitable for installation in narrow spaces such as sewage tank tops or engine room corners.

Tilt-resistant performance: Flow attenuation ≤5% under ship heel ±15° and trim ±10° conditions, ensuring uninterrupted sewage treatment in severe sea conditions.

IV. Typical Application Scenarios

1. Domestic Sewage Treatment

Passenger ship toilet sewage discharge: 1000-person passenger ships use wear-resistant cast iron ejector sewage pumps (flow 50-80m³/h, pressure 1.0MPa) to convey toilet sewage (containing feces, toilet paper) to biochemical treatment devices, with an impurity passage rate ≥95% to avoid device blockage.

Cargo ship crew domestic sewage: 200-person cargo ships use cast iron ejector sewage pumps (flow 10-15m³/h, pressure 0.8MPa) to pump domestic sewage into small integrated sewage treatment machines, with treated effluent meeting MARPOL Annex IV standards (COD ≤125mg/L).

2. Kitchen and Food Wastewater Treatment

Cruise ship kitchen sewage discharge: Large cruise ship kitchens are equipped with dual-nozzle ejector pumps (flow 30-50m³/h, pressure 1.2MPa) to extract wastewater containing food residues (particle diameter ≤10mm), which is sent to oil-water separators after filter interception, achieving ≥98% oil removal rate.

Fishing boat fish processing sewage: Processing cabins of ocean-going fishing boats use stainless steel ejector sewage pumps (flow 15-25m³/h, pressure 1.5MPa) to convey sewage containing fish scales and internal organs, improving solid-liquid separation efficiency by 20% when combined with crushers.

3. Oily Sewage Treatment

Oil tanker engine room sewage: 30,000 gross ton oil tankers use explosion-proof stainless steel ejector pumps (flow 40-60m³/h, pressure 1.6MPa) to convey oily sewage (oil content ≤100ppm) to oil-water separators, with treated effluent oil content ≤15ppm, meeting environmental requirements.

Chemical tanker tank washing sewage: 316L ejector pumps (flow 20-30m³/h, pressure 2.0MPa) are used after chemical tanker tank washing to convey sewage containing trace chemicals to incinerators, with pump bodies meeting corrosion resistance requirements for 1000 hours of continuous operation without leakage.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Sewage type: Cast iron/wear-resistant cast iron pumps for domestic sewage; stainless steel pumps for oily sewage and chemical sewage

Flow calculation: Configure according to 150L daily sewage discharge per person (including losses); e.g., a 500-person ship discharging 75m³ sewage daily requires flow ≥12.5m³/h (based on 6 hours of operation)

Pressure requirements: 0.6-1.2MPa for short-distance conveyance (sewage tank to processor); 1.2-2.0MPa for high-head conveyance (multi-floor cabin collection)

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa) and leaks every 500 hours to ensure smooth sewage discharge

Regular maintenance: Clean inlet filters every 1000 hours (to prevent blockage by large impurities); inspect nozzle wear (replace when diameter expands ≤1mm)

Cleaning maintenance: Rinse pump inner walls with high-pressure water guns every 3000 hours to remove attached sludge and oil, restoring flow path smoothness

3. Compliance Inspection

Annual classification society inspection, focusing on verifying impurity-containing sewage conveyance capacity (flow attenuation ≤10% with 8% solid content) and anti-clogging performance

Meets MARPOL Annex IV requirements for ship domestic sewage discharge, ensuring compatibility with sewage treatment devices (treated effluent meets IMO standards)

VI. Compliance and Certification

International standards: Complies with ISO 15749 marine sewage pump performance standards and IMO MARPOL Annex IV sewage treatment regulations

Classification society certifications: Obtained type approval for ejector sewage pumps from RS, LR, ABS, and CCS (including 1000-hour solid-containing sewage operation tests)

Environmental requirements: When used with marine sewage treatment devices, discharged water has COD ≤125mg/L and suspended solids ≤35mg/L, meeting international anti-pollution standards