QJB18.5/12-620 Large scale all stainless steel submersible mixer

QJB18.5/12-620 Large scale all stainless steel submersible mixerMainly used for mixing, stirring, and circulating in municipal, industrial, and urban residential sewage treatment processes, such as activated sludge tanks, biological reaction tanks, stirring tanks, sludge storage wells, equalization tanks, sewage tanks, etc; Maintenance equipment for landscape water environment, creating water flow; Increase oxygen content in water and improve water quality; Effectively prevent the deposition of suspended solids and other situations.

QJB18.5/12-620 Large scale all stainless steel submersible mixerStructural disassembly and material selection instructions:

Most submersible mixers use a multipole motor direct drive - the blades are directly driven by the motor shaft. Its structural components mainly include the casing, motor, impeller, guide ring, motor cooling, reduction transmission device, sealing device, oil chamber, bearings, cables and junction boxes, protection system, oil injection holes, etc. It has a compact structure, high operating efficiency, and easy installation.

1. Shell

The submersible mixer is completely submerged in sewage, and the sewage in the sewage treatment plant is mostly a liquid with acidity, alkalinity, organic matter, thermal pollution, and corrosiveness. Therefore, the casing of the submersible mixer must have corrosion resistance, generally using cast iron, stainless steel, or better materials. The main nuts, screws, and washers should also be made of stainless steel or higher grade materials.

2. Motor

According to the water depth of the installation of the submersible mixer, suitable submersible motors are selected, generally including standard stators and rotors with high insulation level F insulation. There are also requirements for the temperature inside the motor, generally allowing the motor to heat up and withstand high temperatures up to 155 ℃. According to the B-level assessment, the highest working temperature of the insulation material is 155 ℃, while the highest temperature of the motor winding at rated load is below 120 ℃, ensuring that the motor has a large safety margin and is more reliable and durable. Under normal temperature rise conditions below 80 ℃, the insulation life of the motor is long, with an IP68 protection level combined with excellent shaft seals. Submersible motors are equally safe and reliable as dry motors.

3. Impeller

Impeller, also known as propeller blade, is currently mostly made of stainless steel, but there are also fiberglass or polyurethane materials for submersible mixers. Generally, hybrid submersible mixers are made of stainless steel, while push flow submersible mixers are made of fiberglass or polyurethane materials. Impellers are usually castings. When designing, effective transmission and the efficiency of the mixer output by the motor should be considered; At the same time, consideration should be given to preventing foreign objects from entangling the propeller blades. Sometimes, in order to meet the requirements of a flow field with a higher lift, a guide vane is also installed outside the impeller. After the manufacturing of the submersible mixer impeller is completed, dynamic and static balance tests are also required. Impellers with a diameter of less than or equal to 900mm should undergo dynamic balance tests, while impellers with a diameter greater than 900mm should undergo static balance tests to verify their performance.

4. Diversion ring

Also known as a diffuser, only hybrid submersible mixers can use a diffuser to generate stable axial flow, reduce shaft power, improve efficiency, reduce vibration, and make operation more stable. However, if the processing medium contains fiber debris, the guide cover should be removed to avoid entanglement and other problems that may cause damage. The guide ring can be made of carbon steel or stainless steel material.

5. Motor cooling

When the motor is working underwater, it relies on the rapidly flowing liquid around it for cooling, which has a better cooling effect than in air. Therefore, its overload resistance will be stronger, which is beneficial for the long-term reliable operation of the motor.

6. Sealing device

Due to the long-term operation of submersible mixers underwater, sealing performance is crucial for them. At present, different manufacturers have different sealing methods for submersible mixers. Many submersible mixer motor shaft seals on the market are external, and their medium leakage direction is the same as the centrifugal force direction, resulting in a large leakage amount. The QJB series submersible mixer motor shaft seal of Autland Environmental Protection adopts two independent series connected mechanical seals, forming two reliable sealing lines. The first mechanical seal is located in the inlet medium of the mixer, relying on the stopper between the rotor wheel housing and the oil chamber to prevent large debris from entering the surrounding area of the mechanical seal, so as not to affect its normal operation. In order to adapt to medium pollution conditions, wear-resistant materials (silicon carbide/silicon carbide) are selected for the mechanical seal friction pair to ensure durability and normal operation. The second mechanical seal is located in the oil chamber, and the working conditions of the mechanical seal in the oil chamber are good, so silicon carbide/graphite is selected as the friction pair. The series connection of two mechanical seals can provide safer and more reliable protection for the motor. The shaft seal of the QJB submersible mixer adopts an internal type, and the direction of medium leakage is opposite to the direction of centrifugal force, resulting in a significant reduction in leakage. Two independent single end mechanical seals are both installed internally, which makes it less likely for the medium to leak compared to the external installation. At the same time, their sealing friction pairs are more easily lubricated by the oil in the oil chamber.

7. Cable and junction box

The size of the submersible motor control cable and power cable should comply with IEC standards and provide sufficient length to connect to the junction box, and cannot be spliced. The cable can be used continuously at least 20m underwater without losing its waterproof function.