Cast Iron Ejector Sewage Pump

I. Product Overview

Marine cast iron ejector sewage pumps are high-efficiency treatment equipment designed for ship sewage discharge systems. Made of gray cast iron (HT250) or ductile iron (QT400-18), they enable rapid pumping and transportation of ship sewage (containing oil, solid particles, fibrous impurities, etc.) based on the ejector pump principle (Venturi effect). The core principle is that high-pressure working water forms a high-speed jet through a nozzle, creating vacuum negative pressure in the suction chamber to draw in sewage, which is then pressurized by a diffuser and discharged. Suitable for treating ship domestic sewage, engine room sewage, and cargo hold sewage, they meet IMO MARPOL Annex IV anti-pollution conventions and classification society certifications such as CCS, ABS, and DNV. After surface treatment with epoxy ceramic coating, the cast iron material can operate stably in seawater with Cl⁻≤20,000ppm and sewage with pH 5-10, widely used in various ship types including cargo ships, passenger ships, and engineering vessels.

II. Core Technologies and Material Characteristics

1.Cast Iron Material Selection and Performance

2.Key Technical Parameters

Flow range: 20-150m³/h, suitable for ships of 500-20,000 tons

Head: 15-30m, self-priming height ≥7m, no priming required at startup

Impurity passing capacity: Can pass ≤5mm solid particles and ≤10mm fibrous impurities, reducing clogging risk by 90%

Corrosion resistance design: Cast iron surface with epoxy ceramic coating (thickness ≥250μm), passing 2,000-hour salt spray test without rust, sewage erosion resistance increased by 60%

III. Technical Advantages and Innovative Design

1. Anti-Clogging and Efficient Sewage Disposal

Non-rotating component design: Ejector pumps have no vulnerable parts such as impellers or shafts. Fluid dynamics design ensures smooth transportation of solid particles (such as sediment, rags) and fibrous impurities in sewage, especially suitable for ship sewage with complex impurities.

Oil-water stratification technology: The diffuser uses guide vane design to achieve oil-water stratified discharge in oily sewage (oil content ≤300ppm), improving the efficiency of oil-water separators by 40%.

2. Marine Condition Adaptability

Anti-tilt performance: Stable drainage under ship trim 15° and list 10°, adapting to ship swaying environments to ensure continuous operation of the sewage system.

Anti-winding structure: Comb-shaped anti-winding grilles at the suction chamber inlet effectively intercept fibrous impurities, extending the maintenance cycle to 12 months.

3. Low Maintenance and Cost Advantage

No-disassembly cleaning: Flow channel with wear-resistant coating treatment (roughness Ra≤12.5μm), scaling rate 70% lower than traditional pumps, reducing annual cleaning frequency by 50%.

Modular design: Pump body and pipelines use quick-release connections, eliminating the need for overall disassembly during maintenance, reducing single maintenance time by 60% and maintenance costs by 40%.

IV. Typical Application Scenarios

1. Ship Domestic Sewage Treatment

Passenger ship sewage discharge: Gray cast iron ejector pumps treat domestic sewage for cruise ships, flow 50-80m³/h, combined with domestic sewage treatment plants (STP) to meet IMO MARPOL Annex IV emission standards.

Crew toilet sewage discharge: Provide negative pressure pumping for ship toilets, self-priming height 8m, adapting to multi-deck cabin layouts.

2. Engine Room and Cargo Hold Sewage

Engine room sewage pumping: Ductile iron ejector pumps extract oily sewage from engine rooms, flow 30-100m³/h, anti-oil film adhesion design to avoid clogging.

Cargo hold sewage emergency discharge: Rapid drainage in case of cargo hold flooding, combined with emergency drainage systems to meet SOLAS convention requirements.

3. Special Ships and Offshore Platforms

Engineering ship sewage systems: Treat sediment-containing sewage for dredgers and salvage ships, passing ≤5mm sediment particles to ensure sewage discharge during construction.

Offshore platform sewage: High-pressure ejector pumps (head ≥25m) treat platform domestic sewage and industrial wastewater, adapting to complex offshore conditions.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Sewage type: Choose HT250 for domestic sewage, QT400-18 for oily/particulate sewage

Ship tonnage: Select HT250 for <10,000 tons, QT400-18 for ≥10,000 tons

Flow matching: Configure at 1.5 times the maximum sewage generation, e.g., 5,000-ton cargo ships recommend flow 80-120m³/h

2. Maintenance Key Points

Daily monitoring: Check inlet/outlet pressure and pipeline tightness daily, ensure pressure fluctuation ≤±8%

Regular maintenance: Clean suction grilles (accuracy ≤10mm) quarterly, remove pump cavity oil sludge with special cleaners annually

Anti-corrosion maintenance: Reapply epoxy ceramic paint every two years, inspect zinc sacrificial anode wear and replace timely

VI. Compliance and Certification

International standards: Complies with IMO MARPOL Annex IV Regulations for the Prevention of Pollution by Sewage from Ships

Classification society certifications: Passed CCS Rules for the Classification of Steel Ships and ABS Rules for Building and Classing Ships

Environmental requirements: Discharged water quality complies with GB 3552 Discharge Control Standard for Water Pollutants from Ships