Water jet unit

▍ Working principle

The working principle of a water jet generator is based on the Venturi effect in fluid mechanics.

1. Power Supply: The unit's centrifugal water pump draws water from the tank and pressurizes it to a high-pressure working water pressure of 0.2-0.5 MPa (adjustable according to design).

2. High-Speed Jet: The high-pressure working water passes through a specially designed nozzle installed inside the PP jet, forming an extremely high-speed jet.

3. Vacuum Generation: This high-speed jet enters the diffuser tube (Venturi tube) of the jet. Due to the sudden reduction in cross-sectional area at the throat of the diffuser tube, the water velocity increases sharply. According to Bernoulli's law, the dynamic pressure increases while the static pressure decreases significantly, thus creating a continuous and stable low-pressure (vacuum) zone in the throat region.

4. Gas Suction: This vacuum zone is connected to the container being evacuated through the suction port, thereby drawing air or other gaseous media from the container into the jet.

5. Mixing and Discharge: The intake gas and high-speed water flow undergo thorough mixing and energy exchange within the diffuser. The velocity of the mixed gas-water two-phase fluid decreases, while the pressure increases. Finally, it is discharged from the drain outlet at a pressure slightly higher than atmospheric pressure, returning to the water tank to complete one working cycle.

The water tank is typically designed with a separation structure. The intake gas escapes from the water surface, while the water is recycled, achieving media circulation and energy conservation.

▍ Structural features

1. High-Quality PP Material Body:

● Strong Corrosion Resistance: The main equipment (ejector, water tank, exhaust tank, etc.) is welded from polypropylene (PP) sheets, possessing excellent resistance to acid, alkali, and salt solution corrosion. It can handle various corrosive gases and liquids for extended periods, ensuring a long service life.

● Pollution-Free: PP is a food-grade plastic, non-toxic and odorless, and will not cause secondary pollution to the treated media, fully meeting the hygiene requirements of the pharmaceutical, food, and other industries.

● Lightweight: Compared to stainless steel or cast iron equipment, PP material is lightweight, facilitating transportation and installation.

2. High-Efficiency Ejector Design:

● The nozzle and throat are precisely hydraulically calculated and designed, using integral precision casting or CNC machine tool processing to ensure smooth inner walls and flowing curves. This maximizes the conversion of water pressure energy into kinetic energy, resulting in higher pumping efficiency and ultimate vacuum.

3. Integrated Design:

● The unit integrates the water jet injector, water tank, centrifugal water pump, check valve, piping and instrumentation onto a robust base, resulting in a compact structure and small footprint. Users only need to connect the power supply and cooling water (if needed) to put it into operation; installation is simple.

4. Multifunctional Water Tank:

● The water tank serves as both an air-water separator and a circulating water pool. Internal baffles effectively separate air and water. Overflow outlet, drain outlet, and water inlet are provided for convenient daily maintenance and cleaning.

5. Flexible Configuration:

● Single-stage, double-stage, or even multi-stage series configurations can be selected to achieve higher vacuum levels, depending on actual operating conditions.

● The water pump can be configured with pump heads of different materials (such as PP, stainless steel) to match different working fluid properties.

▍ Main advantages

1. **Superior Corrosion Resistance:** This is its core advantage, capable of handling highly corrosive conditions that most metal pumps cannot, with extremely low maintenance costs.

2. **Environmentally Friendly and Safe:** Using water as the working medium, it produces no oil mist pollution, poses no explosion risk, and is intrinsically safe. The pumped gas dissolves directly in water or is absorbed by water, providing some exhaust gas treatment capability.

3. **Simple Structure and Easy Maintenance:** With no moving mechanical parts (referring to the vacuum-generating section), it avoids the wear and jamming problems common in metal vacuum pumps. It operates stably and reliably with a low failure rate, requiring only routine maintenance of the water pump.

4. **Multi-functional:** It can be used for vacuuming, as well as as a condenser, absorption tower, and dust collector. Its effectiveness is particularly pronounced when pumping condensable gases.

5. **Low Investment and Operating Costs:** The initial purchase cost is lower than that of comparable corrosion-resistant metal vacuum pumps. Although the working water requires circulating cooling, its overall water and power consumption is relatively low.

6. Easy to operate: Quick start-up, simple operation, no need for complex upstream and downstream valve control systems.

▍ Scope of application

This unit is widely used in applications requiring low to medium vacuum levels and in the presence of corrosive media, specifically including:

● Chemical Industry: Vacuum filtration, vacuum crystallization, vacuum concentration, vacuum drying, material conveying, reactor vacuuming, esterification, distillation, and other processes.

● Pharmaceutical Industry: Drug extraction, vacuum drying, drug recovery, and creation of laboratory vacuum environments.

● Environmental Protection: Vacuum filtration in wastewater treatment, and waste gas absorption and treatment (e.g., absorption of acidic gases such as HCl and SO₂).

● Food Industry: Vacuum source in food concentration, dehydration, and vacuum packaging lines.

● Metallurgical Industry: Vacuum degassing and flue gas purification.

● Other Fields: Assisted degassing in plastic extrusion, vacuum impregnation of power capacitors, and building material testing, etc.

▍ Summarize:

PP material water jet vacuum units, with their unique corrosion resistance, pollution-free operation, safety, reliability, and multi-functional integration, have become benchmark equipment for handling vacuum needs of corrosive media in modern industry. They perfectly resolve the conflict between production efficiency, equipment lifespan, and environmental protection, making them an excellent choice for upgrading, retrofitting, or constructing new projects in the chemical, pharmaceutical, and other related industries.