If the ejector or piping is steam jacketed to prevent ice buildup, its orientation will affect the operation and drainage of the jackets. In fact, care must be exercised during system design, so that external loads caused by thermal movement and mechanical loading are minimized. Adequate piping support should be provided to minimize external loads on the ejectors, since any misalignment will adversely affect system performance. In most cases, the ejector is an integral part of a steam-jet vacuum system, but it is not intended to provide physical support for the system. Drain valves installed at low points can be either manual or automatic, depending on customer requirements, and the drain cycle must relate to the type of process: Batch systems should be drained before each cycle, while continuous processes may be drained during operation if needed. Provisions should be made to ensure proper drainage of the ejector bodies, since any condensed steam or process vapors may reduce throughput capacity. However, to keep condensate and any entrained solids from collecting, low points in the vacuum piping system should be avoided during design and installation. Adding an aftercondenser will not affect overall system performance, but may ease disposal of vapors.Įjectors may be installed at any angle. An aftercondenser can also be added, to condense vapors from the final stage. Precondensers can be added to reduce the load on the first-stage ejector, and allow for a smaller unit. This allows smaller ejectors to be used, and reduces steam consumption. By condensing the vapors before sending the stream on to the next stage, the vapor load is reduced. In a multi-stage system, condensers are typically used between successive ejectors.
![electrode in a pneumatic sewage ejector system electrode in a pneumatic sewage ejector system](http://www.chinathz.com/upfile/productpic/Water_Romg_Vacuum_Pumps_With_Air_Ejector(PQ-6_2SK-6A)_b.jpg)
For greater throughput capacity of gas or vapor, two or more ejectors can be arranged in parallel. For greater compression, two or more ejectors can be arranged in series. Since the capacity of a single ejector is fixed by its dimensions, a single unit has practical limits on the total compression and throughput it can deliver. In the diffuser, its velocity energy is converted into pressure energy, which helps to discharge the mixture against a predetermined back pressure, either to atmosphere or to a condenser (Figure 1). As these gases are entrained in the steam, the mixture travels through the ejector, into a venturi-shaped diffuser. This steam jet creates a vacuum, which extracts air or gas from the adjoining vessel.
![electrode in a pneumatic sewage ejector system electrode in a pneumatic sewage ejector system](https://3.imimg.com/data3/DD/TB/MY-2527194/pneumatic-sewage-ejector-systems-for-hydro-power-house-250x250.gif)
![electrode in a pneumatic sewage ejector system electrode in a pneumatic sewage ejector system](https://cpimg.tistatic.com/06940221/b/4/Semi-Electrodes-Sewage-Treatment-Plant.jpg)
The steam nozzle discharges a high velocity jet across the suction chamber. The gas that is to be induced into the suction chamber can be any fluid that is compatible with the steam and the components’ materials of construction. In a steam-jet ejector, the suction chamber is connected to the vessel or pipeline that is to be evacuated under vacuum. Since an ejector has no valves, rotors, pistons or other moving parts, it is a relatively lowcost component, is easy to operate and requires relatively little maintenance. Specific guidelines should be followed during equipment layout and installation, to optimize system performance.Įquipment Arrangement: Ejectors - An ejector is a type of vacuum pump or compressor. Finally, the appropriate monitoring and control instrumentation must be specified. A reliable source of steam and cooling water must be available, and provisions must be made to carry out condensate removal under vacuum. These systems operate on the ejector-venturi principle, which relies on the momentum of a high-velocity jet of steam to move air and other gases from a connecting pipe or vessel.ĭuring system design, critical decisions must be made regarding process conditions, component orientation and layout. Steam-jet vacuum systems combine ejectors, condensers and interconnecting piping to provide relatively low-cost and low-maintenance vacuum pumping.