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压缩空气技术知识

什么是压缩空气?

什么是压缩空气        压缩空气是一种以压缩后的环境空气形式存在的能源。压缩空气最终会膨胀回到环境压力,因此在膨胀过程中需要执行工作。此外电能压缩空气是工业生产过程中最重要的电力方式之一,诸多优点使得压缩空气广泛使用: • 可以在需要时就地生产 • 容易存储且无损耗 • 运输简单 • 单位容积能量大 • 可以在狭小的空间内轻易转换成其它能源方式,比如:  - 爆炸空气(压缩空气枪或喷嘴)  - 快速线性运动增加力量(压缩空气缸)  - 快速运动增加扭矩(压缩空马达) •  各种应用领域        压缩空气中含有环境空气的污染物和在工作压力下产生的湿气。油润滑压缩机将大量的油带入压缩空气中(残油)。       当压缩后的热空气冷却到一个合适的工作温度时,大量的水会凝结(冷凝)。未经处理的压缩空气污染物将污染和损坏压缩空气系统、压缩空气消耗设备和直接与压缩空气接触的产品。

什么是压缩空气处理?

      压缩空气处理就是去除不想要的污染物并提供各种应用所需的纯净压缩空气,比如:标准的仪表气、无油工艺压缩空气直到无菌超纯空气或者医疗呼气空气。许多工业对压缩空气质量有特定的要求。      压缩空气处理的目标是确保持续、无故障使用压缩空气的领域,最小化停机时间、非预定保养和维修工作,并且去除对产品有害的特定污染物。 最重要的是,压缩空气处理能有效的对环境保护作出贡献同时保护职业健康和安全。     液态油滴、微油雾、被油污染的颗粒和气态的臭味油蒸汽等污染物会出现在压缩空气的生产现场。这些污染物可以彻底去除,不污染当地的环境。      压缩空气处理系统由几个连续的处理部件构成,也叫处理链,分阶段处理压缩空气以达到所需的纯度。

什么是压缩空气冷却?

        压缩空气冷却发生在每一个压缩空气系统中。 通常空压机中会集成后部冷却器,没有后部冷却器的空压机排气温度会达到70°C 甚至120°C。        冷却后会产生大量的冷凝水,这些冷凝水必须直接从后部冷却器排出压缩空气系统。 然而没有后部冷却器的空压机或者现有的冷却器效率低下时,下游的处理系统就需要更低的压缩空温度,这样就需要安装单独的后部冷却器以降低到合适的温度。

什么是压缩空气干燥?

     压缩空气干燥是最基本的关键压缩空气处理部件。压缩空气干燥最重要的任务是把压缩空气中的水分减少到特定的残留值。空压机出口的水分含量是所有污染物的1000倍,100%的饱和空气意味着下游轻微的温度下降就会产生液态水,冷凝水就会在压缩空气中凝结。    压缩空气干燥机消除水分从而生产干燥、不饱和的压缩空气,这样冷凝就不会发生-即使在整个压缩空气系统中或者在用气终端。 备注       冷却器和干燥机都能减少压缩空气中的水分。 经过冷却器后的压缩空气任然是100%的饱和湿气,经过干燥机的压缩空气是不饱和的。     因此冷却器用于单纯的降低温度,而干燥机用于真正的压缩空气干燥从而降低水份到一定的露点,以确保冷凝不会发生。备注   不饱和的干燥压缩空气容易再次潮湿。因此压缩空气系统“湿”的部分可用干燥的压缩空气再次干燥。需要一定的时间,但是有效果。

什么是压缩空气过滤?

      压缩空气过滤是压缩空气处理中的基本部件,在处理链中不止出现一次。压缩空气过滤器分阶段从压缩空气中去除各种类型的固态和液态污染物。比如大量的冷凝液和粗污染颗粒如铁锈、磨损颗粒、油滴和灰尘在第一阶段被过滤掉,然后微油和微颗粒在第二级被过滤掉。压缩空气过滤器中的活性炭也能去除臭气和油蒸汽。 特定的压缩空气过滤器甚至能去除病毒和细菌从而产生无菌压缩空气。

冷凝液管理有什么好处?

      冷凝液管理适用于压缩空气处理中的几乎每一个部分。 分为冷凝液排放和冷凝液处理两部分。     在冷凝液排水过程中,需要把冷凝或特定分离产生的大量液体排出压缩空气系统。这样就避免液体污染物贯穿压缩空气系统。    冷凝液处理过程是把污染物、油和碳氢化合物中的冷凝液分离出来。这些冷凝液会进入废水系统或以生态兼容方式进入河流、湖泊等。

什么是压力露点?

In a gas, loaded with moisture (gaseous water), while cooling down at a specific temperature liquid water will occur in the form of fine mist suspended in the gas or dew on surfaces by means of condensation. This specific temperature is called dew-point temperature or simply dew-point.For many application processes neither liquid water at all nor even the tendency of forming liquid water within the gas is wanted or permitted. Therefore drying methods are applied in order to reduce the dew-point of the process gas (e.g. compressed air) so no condensation will take place and thus no liquid water can or will form within the process gas any more.The dew-point, simply to understand since given as a temperature in °C or °F and thus directly related to many processes parameters, is the most favoured expression when measuring or indicating the moisture content in a gas. Compared to indications of a concentration, which describes the ratio of amounts of water and gas (e.g. stated as g/m³), the dew-point describes the "behaviour" of the moisture within the gas depending on the gas temperature. Thus, the dew-point itself is not suitable for a mass balance indication, but can be converted by means of formulas or tables (see water vapour content table). In return there is a direct relationship between the dew-point and the relative humidity (rh). Identical gas temperature and dew-point temperature means a relative humidity of 100% and thus a gas saturated with moisture.Furthermore, it’s important to distinguish between dew-point and pressure dew-point: • dew-point is related to non-pressurised, atmospheric air (atmospheric dew-point)  • pressure dew-point is related to a compressed gas (e.g. compressed air) at a specific operating pressureWhen expanding a compressed gas to atmospheric pressure, its volume expands. The moisture, suspended in the gas, is dispensed to a bigger volume – the gas gets more dry. As a consequence, the dew-point of a gas, measured at atmospheric conditions, is much lower than the pressure dew-point of the same gas, measured in compressed condition. Therefore when indicating a dew-point always the related pressure must be stated as well in order to avoid a mix-up and as a consequence mistakes when selecting and sizing a dryer.Dew-points of compressed air dryers are usually stated as pressure dew-points, but it's worth to double-check! In case, atmospheric dew-point and pressure dew-point can be converted into each other.ExampleSummertime – sitting in a beer garden. The waitress serves a cold glass of beer. Fantastic – but something’s going on at the beer glass. The cold glass cools down the warm, non-saturated but moisture containing ambient air on its surface. As long as the temperature does not fall below the dew-point, the glass stays dry. Below dew-point, the moisture condenses to water on the cold glass surface – first as a thin wet film, later forming even droplets.

水蒸汽含水量表

The water vapour content table defines the maximum amount of moisture that can be contained in air or compressed air at a specific temperature.The maximum amount of moisture just depends on the temperature and is independent from the pressure!• Air or compressed air containing the maximum amount of moisture is called saturated.• Air or compressed air containing less than the maximum amount of moisture is called non-saturated.• Air or compressed air containing more than the maximum amount of moisture is "theoretically over-saturated" – the excessive amount of moisture will condense to liquid water while the air becomes saturated again.

著名的ISO 8573-1:2010空气质量等级

[1] - reference conditions 1 bar(a) and 20°C at 0% relative humidity[2] - unless otherwise agreed or stated, reference conditions 7 bar and 20°C[3] - measured according to ISO 8573-2 and ISO 8573-5[4] - measured according to ISO 8573-2 ; measurement according to ISO 8573-5 optional[5] - measured according to ISO 8573-3 and, if required, ISO 8573-9[6] - measured according to ISO 8573-4[7] - measured according to ISO 8573-8[8] - measured according to ISO 8573-9[9] - if particles greater than 5 µm have been measured, class 0-5 cannot be applied[10] - liquid, aerosol and vapour oil content