Audited Supplier
Functionality of Multi-Channel Jet Aerators/Ejectors
The high-pressure wastewater is introduced through the inlet pipe at the tank bottom, evenly distributed among the integrated jet pipes. A vortex generator at the jet pipe entrance initiates a robust vortex, inducing a powerful swirling motion.
This swirling flow generates a negative pressure zone at the throat pipe's end due to the high-velocity jet passing through. Compressed air is introduced into the air chamber through an air inlet pipe, then guided into the integrated jet pipe via vent holes in the air chamber and the air inlet of the throat pipe.
The integrated jet pipes are positioned at a 60-degree angle relative to the cylinder, causing the ejected air-water mixture to impact the tank bottom forcefully. This action effectively agitates sediment at the tank bottom, preventing sludge accumulation in stagnant areas and enhancing the trajectory of microbubbles in the water, thereby improving oxygen dissolution efficiency.
Advantages of Multi-Channel Jet Aerators/Ejectors
- Maintenance-free: No moving parts
- High oxygen efficiency: Fine bubbles create extensive air-water contact surfaces with high turbulence for surface renewal.
- No deposits: The directed jet flow towards the tank bottom inhibits biomass deposition.
- Precise control of oxygen supply
- Non-clogging design: The nozzle diameter defines the narrowest flow cross-section.
- No sealing issues: Water ingress into the air pipeline during plant inactivity has no adverse effects, and the ejector's entraining effect expels any residual liquid upon restart.
- Customizable design: Various sizes can be tailored and adjusted to specific requirements.
COMPARATIONS TO OTHER AERATION SYSTEMS
| Jet-aeration | Micro-bubble air aeration | Surface aeration | |
| Service life | Long Simple structure and long service life | Short Complex system and short-lived diffuser membrane | Fair |
| Installation | Easy Easy and quick mounting, | Complex Complex mounting requirement | Difficult Heavy device and difficult to mount |
| Adjusting flexibility | Flexible Both air and circulation water flow can be adjusted independently. | Only air flow can be adjusted. | Oxygen supply and mixture shall be adjusted simultaneously |
| Oxygen-supply efficiency | High | Low | Low |
| Maintenance | Convenient maintenance | Difficult to maintain and trouble-shoot | High rusting risk at air-liquid mixing part, and need frequent overhaul |
| Blocking problem | No blocking | Easy to be blocked | -- |
| Mixture of water and sludge | Abundant mixture of water and sludge | Little mixture of water and sludge | Easy to produce short-cut and blind angle |
| Sludge sediment characteristics | Good Zooglea is compact and active | Fair Risk of sludge filamentation bulking is high. | Good Zooglea is compact and active |
INSTALLATION
When installing multi-path ejectors in an aeration tank, the absence of moving parts within the tank eliminates the need for maintenance. The mechanical stress on the ejectors is equivalent to that of a pipeline with increased flow velocity. Roots blowers/compressors and pumps can be situated outside the tank for convenient maintenance purposes.
Once the tank's geometry, water depth, and oxygen requirements are determined, the number, design, and arrangement of the multi-path ejectors can be customized for the specific case. Mounting them is straightforward, requiring only two flanges in the pipelines for motive flow and compressed air. Installing compact units on the tank floor ensures thorough aeration and complete mixing of the wastewater.
Installation from Outside Through the Tank Wall
The stainless steel ejector featured here is mounted "through-the-wall," with connections for motive flow and compressed air located externally from the aeration tank.
These relatively large units include a secondary downstream mixing zone that enhances intermixing within the tank by drawing in additional liquid.
If necessary, a shut-off device can be added downstream of the motive nozzle, allowing for easy inspection without emptying the tank.
This installation option facilitates a continuous application of the oxygen transfer system, even in scenarios with elevated calcium carbonate levels in the wastewater. While these larger ejectors may have lower oxygen efficiency compared to our multi-path ejectors with finer air bubbles, their consistent availability often proves crucial for customers. As a result, numerous installations have been implemented in the paper industry, sometimes as retrofits to replace inadequate systems.
Oxygen Efficiency
Oxygen transfer efficiency is not solely determined by bubble size but also by the renewal of gas bubble contact surfaces. Ejectors, with their continuous circulation of wastewater, can achieve higher oxygen efficiency than other aerators. By directing flow towards the tank floor, Körting ejectors fully utilize the tank depth as an entry point. Oxygen supply tests in clean water form the basis for designing Körting ejectors, with measurements conducted on full-scale plants and validated through inspection tests.
At typical depths of 5 to 8 meters, an oxygen efficiency (OC20) of 11 g O2/Nm3 • m can be achieved in clean water. In partial load operation, the oxygen efficiency can exceed this value, reaching up to 14 g O2/Nm3 • m. Depending on depth and oxygen requirements, a single ejector can inject approximately 400-500 Nm3/h of compressed air into the tank.
Control Range and Oxygen Yield
Oxygen supply regulation is achieved by adjusting the air volume flow, with reduced air supply leading to lower inlet pressure and improved specific oxygen efficiency. This results in a consistently high oxygen yield across the control range, with peak efficiency during partial load operation near the design point. Ejectors are designed for an optimal air/water ratio based on activated sludge properties, ensuring enhanced system performance through air supply adjustments and maintaining optimal oxygen efficiency in all conditions.
FEATURED PRODUCTS
