Submersible Mixer

Technical Performance Requirements for Duan Environmental Submersible Mixers:

Duan Environmental submersible mixers can be fully and compatibly installed on existing mounting brackets without stopping water flow on-site.

All electrical interfaces of the submersible mixer are consistent with the on-site electrical control equipment interfaces to avoid causing failures in the electrical control system.

Performance and Structure of the Submersible Mixer:

The submersible mixer mainly consists of a two-blade propeller, gear reduction box, submersible motor, and underwater sealed cable.

The output power of the submersible mixer ensures thorough mixing of the pool water, with no significant sedimentation, and guarantees the required hydraulic and flow conditions.

The submersible mixer is mounted on a bracket at the bottom of the pool via guide rails, allowing free vertical movement along the guides. Emptying the pool is not required for installation or lifting. The entire weight of the submersible mixer should be supported by the lifting bracket, which can withstand the thrust generated by the mixer.

Each submersible mixer must operate continuously at a maximum allowable submersion depth of 20 meters underwater, while also supporting intermittent operation and resuming operation after prolonged shutdowns. Throughout operation, the mixer must run smoothly without jamming or vibration.

Housing Material:

The housing of the submersible mixer is made of high-quality gray cast iron GG25 or better. The housing design thickness is sufficient to withstand loads, with a smooth surface free of pores and a compact structure. All water-sealed surfaces should use nitrile rubber O-ring seals.

Propeller Impeller Material:

The propeller is two-bladed, made of polyurethane or fiberglass with an internal metal skeleton, coated with a protective layer, and designed for handling conventional wastewater. It features a swept-back, hydraulically balanced, non-clogging, self-cleaning design. The propeller has excellent hydraulic performance to promote wastewater flow in pool channels.

The blades should be "flexible" and capable of absorbing varying hydraulic loads. Each blade is mounted in a socket on the hub side via a cast iron shaft. The hub is fixed to the shaft end with a single key, sealed with a protective cap, and secured with a locking washer system.

Main Shaft Material Description:

The motor shaft and propeller shaft are connected via a gearbox. The shafts are made of wear-resistant stainless steel and can withstand all axial and radial loads. The propeller shaft is fully protected by mechanical seals, O-rings, and radial seals, isolating it from the mixing medium to prevent corrosion.

Bearing Description:

All bearings in the submersible mixer are high-quality, maintenance-free bearings with long-term grease lubrication, capable of withstanding axial and radial loads. The designed bearing life is not less than 100,000 hours.

Shaft Seal or Mechanical Seal:

Between the mixer gearbox and hub, there is one mechanical seal and two radial seal rings. The radial seal rings are placed on bronze sleeves, providing additional protection for the mechanical seal and facilitating replacement. The shaft seal system includes a sealed oil chamber where the mechanical seal is installed and operates. A pair of radial seal rings is also installed between the motor chamber and the gearbox. The mechanical seal is maintenance-free and can rotate clockwise or counterclockwise without affecting its sealing function. The mechanical seal is made of silicon carbide or tungsten carbide, offering good mechanical strength and resistance to thermal shock, with a medium pH range of 4–10. The seal material is nitrile rubber, which is highly tear-resistant and has a long service life. The designed service life of the mechanical seal is over 25,000 hours.

Submersible Motor Description:

The submersible motor is a three-phase squirrel-cage induction motor. The motor has an IEC IP68 protection rating and an F-class insulation rating (155°C). The rated power of the motor ensures that the submersible mixer does not experience overload during use. The motor can be started more than 10 times per hour. The motor shaft and rotor have passed dynamic and static balance tests. The motor is designed to operate in environments up to 40°C (104°F), capable of submersion and continuous mixing of liquids at 40°C, with an average stator winding temperature rise not exceeding 80°C. To monitor the temperature of each phase winding, thermal switches are installed in each stator winding coil, set to open at 130°C. The thermal switches are connected to the control cabinet and linked to control relays.

Both the motor and cable can be used continuously at a maximum submersion depth of 20 meters without losing their waterproof performance (compliant with IP68 rating). The submersible motor is adequately cooled by the surrounding medium without relying on a cooling jacket or external cooling system. Additionally, the motor chamber is filled with insulating oil to ensure excellent insulation and cooling performance, preventing water leakage and motor burnout.

Underwater Sealed Cable Description:

The motor is equipped with a submersible sealed cable that includes both control and power cores in the same cable. The motor has a separate, reliable cable entry. The cable complies with IEC standards and is provided with sufficient length to connect to the junction box or local control cabinet without splicing. The cable enters the terminal chamber using a reusable double-compression rubber sleeve seal, allowing quick cable replacement. The cable seal head is specially vulcanized to prevent liquid ingress into the motor due to cable sheath damage. The cable outlet should be axial, flush with the outer surface of the motor housing, and secured with cable clamps to the cable tensioner to avoid flow-induced vibration and snagging during lifting. Both the motor and cable can be used continuously at a 20-meter submersion depth without losing waterproof performance.

Gearbox Description:

The submersible mixer is driven by an efficient planetary gearbox. The gearbox housing is integrated with the mixer housing, with a smooth transition to the hub and motor housing, ensuring high flow stability and excellent hydraulic characteristics, thereby improving the overall efficiency of the submersible mixer. The gearbox is equipped with high-precision, high-efficiency, low-load two-stage planetary gears made of high-wear-resistant alloy steel. The gearbox is filled with oil to lubricate and cool the transmission system. The gearbox brand is Shuntian or SEW. The designed service life is not less than 100,000 hours.

Monitoring System Description:

Three series-connected thermal switches are installed in the three-phase stator coils of the submersible mixer to monitor stator temperature rise. Thermal protection activates at 130°C, triggering an alarm and stopping the motor. The submersible mixer is equipped with a leakage sensor to detect leaks in the sealed oil chamber, preventing water ingress and motor damage. The leakage sensor is an electrode-type sensor, whose signal can be monitored by a protection relay, triggering an alarm if water enters the motor.

Main Materials Description:

The materials used in the submersible mixer are suitable for industrial wastewater treatment requirements.

Anti-Corrosion Coating Description:

All materials used in the manufacture of the submersible mixer are suitable for the corrosive environment of industrial sewage plants. Unprotected or non-corrosion-resistant materials are treated according to general technical requirements.

Technical Parameters of the Submersible Mixer:

The submersible mixer can be operated via local manual control or PLC automatic control.

1. Manual Control

The submersible mixer should be equipped with manual control to allow operation when automatic control is unavailable. When the "selection switch" on the control panel is set to manual control, the machine can be operated manually via control switches on-site, with handle control buttons for starting and stopping the equipment.

2. Automatic Control

Under PLC automatic operation, the submersible mixer is controlled by time, operating either continuously or intermittently.

When the selection switch is set to full automatic control, the machine can operate in the following ways:

Via the start button on the control panel.

Via time control on the control panel.

Other Random Accessories or Requirements

The submersible mixer is supplied with six sets of hand-operated lifting devices (including steel cables and three-prong hooks) installed on existing lifting brackets. Some steel cables and hooks can be reused, with replacements and supplements provided based on on-site conditions. The lifting device materials: underwater parts require stainless steel 304 or better, above-water parts require stainless steel 201, 304, or 316 or better. The lifting device should allow flexible forward and reverse operation, with immediate braking upon stopping and automatic brake release during manual operation. The hand crank installation must include an anti-loosening structure to prevent detachment.

The submersible mixer has a two-year warranty. During the warranty period, on-site or remote guidance is provided for maintenance. If a non-human-caused failure occurs, repairs will be arranged, and the warranty for that mixer will be recalculated from the date it resumes operation. If the same failure occurs twice or more for the same mixer during the warranty period, a free replacement with a new mixer of the same model will be provided.

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