Energy Savings Result from Compressed Air Dryer Selection

不同类型的压缩空气干燥机,所达到的不同的节能效果


作者:Christopher Ursillo   翻译:郝超


Every facility has differing application needs and usage demands, but selecting the right compressed air dryer for the situation will have a significant impact on energy savings and efficiencies.

每种工厂设备都有不同的应用需求和用气量要求,根据具体情况选择合适的压缩空气干燥器将对节能和效率产生重大影响。

Compressed air systems account for a significant portion of a facility’s overall operating costs. Choosing the right type of compressed air dryer for the application, and making sure that dryer is using energy in proportion to the demand when possible, can yield major savings over the life of the system.

压缩空气系统占整体设备运行成本的很大一部分。为不同应用选择合适类型的压缩空气干燥机,并确保干燥机的能耗尽可能地符合需求比例,就可以在系统的使用寿命期间,极大地节省成本。

Two categories of air dryers — refrigerated dryers and desiccant dryers — are widely used in industrial applications, and both have a place in the market. There isn’t a one-size-fits-all dryer solution for every facility. However, looking at the energy costs associated with the various options can help determine which solution will be most beneficial.

有两种类型的干燥机-冷冻式干燥机和吸附式干燥机(干燥剂吸附)-这两种干燥机在工业中都得到广泛应用,都在市场上占有一席之地。没有一种适用于所有设备的干燥机解决方案。然而,我们可以查看能源成本并做出相关选择;从而可以帮助确定哪种解决方案最有益。


Refrigerated Dryers冷冻式干燥机

意大利富瑞FRIULAIR冷冻式干燥机


Typically, refrigerated dryers are the most economical to purchase and maintain, and they work well for most general manufacturing applications. These dryers yield air with a pressure dew point between 38 and 50 degrees F.

 通常情况下,冷冻式干燥机在购买和维护上是最经济的,而且它们在大多数一般的制造应用中,运行良好。这些冷冻式干燥机产生空气的压力露点在38到50华氏度之间。(3.3-10摄氏度)

Refrigerated dryers reduce the temperature of compressed air through contact with a cold medium. Since cold air cannot hold as much moisture as hot air, saturated air condenses out moisture as the air temperature decreases, drying the air. The resultant moisture is removed using a moisture separator within the dryer and eliminated from the dryer through the drain system.

冷冻式干燥机通过与冷媒接触来降低压缩空气的温度。由于冷空气不能容纳像热空气那样多的水分,随着空气温度的降低,饱和的空气凝结出水分,使空气干燥。由此产生的水分通干燥机内的气水分离器除去,并通过排水系统从干燥机中排出。

Refrigerated dryers generally fall into two categories: non-cycling and cycling, both of which use a refrigeration system to cool the compressed air. The two technologies differ in that once a non-cycling dryer is powered on, the refrigeration system runs continuously regardless of demand, while a cycling dryer can store cold energy within the unit until it is needed, which offers the ability to use energy in proportion to the demand. Most non-cycling dryers include a hot gas bypass valve to keep the dryer from freezing.

冷冻式干燥器一般分为两类:非循环式和循环式(周期工作型),两者都通过制冷系统来冷却压缩空气。两者在技术的不同之处在于,一旦非循环式冷干机启动,制冷系统就会持续运行,而不管需求如何;而循环式(周期工作型)冷干机可以在机组内储存冷能,直到需要时才使用,这就提供了根据需求使用能源的能力。大多数非循环式冷干机包含一个热气体旁通,以防止冷干机冰堵。

Because cycling dryers can store cold energy until it is needed, they help facilities conserve energy. Cycling dryers use the refrigeration system to cool a glycol-water mixture. Thisthermal massexchanges heat with the warm air coming into the system, thereby cooling the air and warming the thermal mass. Once the thermal mass temperature rises above a set point, the refrigeration system is activated. The refrigeration system drives down the temperature of the thermal mass until it reaches the desired low temperature, at which point the refrigeration system turns off. This type of operation uses only the energy required to address the incoming air load on the dryer, another boost to energy efficiency.

由于循环式(周期工作型)冷干机可以储存冷能量,直到需要时才使用,它们有助于节约能源。循环式(周期工作型)冷干机使用制冷系统来冷却乙二醇-水混合物。这种储热体与进入冷干机系统的热空气交换热量,从而冷却空气并加热储热体。一旦储热体温度上升到一定的温度点以上,制冷系统就会启动。储热体的温度,直到达到预期的低温为止,制冷系统就会关闭。这种操作只根据进入冷干机的空气负荷来使用能量,这又提高了能量利用效率。

Different air drying technologies yield different energy costs. The electrical costs for refrigerated dryers are essentially the refrigeration compressor, the controls and, in the case of an air-cooled unit, the condenser fans. Some units might have other components, such as a thermal mass pump, that make a minor contribution to the overall energy consumption.

不同的空气干燥技术会带来不同的能源成本。冷冻式干燥机的耗电成本主要是制冷压缩机、控制装置,如果是风冷机组,则是冷凝器风扇。有些机组可能有其他部件,如储热体,占总体能耗的很小一部分。

Non-cycling refrigerated dryers are the least expensive models to purchase. However, cycling dryers provide the ability to use energy in proportion to demand, so they may ultimately be the least costly to own over the life of the dryer.

非循环式冷冻式干燥机是购买成本最低的机型。然而,循环冷干机根据实际需求,按比例消耗能源,因此在冷干机的全寿命周期内,它们最终可能是成本最低的。


Desiccant Dryers 吸附式干燥机(干燥剂吸附)

Desiccant dryers, which provide air with a pressure dew point ranging from -40 to -100 degrees F, use two towers, each filled with desiccant material. While one tower adsorbs the moisture and dries the air, the second tower is regenerated. By alternating tower functions, desiccant dryers provide a constant stream of very dry air. 

吸附式干燥机(干燥剂吸附)为压缩空气提供-40到-100华氏度(-40到-73摄氏度)的压力露点,使用两个塔,每个塔都充满吸附剂。当一个塔吸附水分并干燥空气时,第二个塔被再生。通过2个塔的交替切换,吸附式干燥机提供持续的非常干燥的空气流。 

Instead of relying upon a refrigeration system that cools the air, desiccant dryers use porous desiccant beads to adsorb moisture from untreated air. Desiccant dryers, which provide air with a pressure dew point ranging from -40 to -100 degrees F, use two towers, each filled with desiccant material. While one tower adsorbs the moisture and dries the air, the second tower is regenerated. By alternating tower functions, desiccant dryers provide a constant stream of very dry air. 

吸附式干燥机不依赖冷却空气的制冷系统,而是使用多孔干燥剂吸附未经处理的空气中的水分。吸附式干燥机为空气提供-40到-100华氏度的压力露点,使用两个塔,每个塔都充满干燥剂。当一个塔吸附水分并干燥空气时,第二个塔被再生。通过交替切换功能,吸附式干燥机提供稳定的非常干燥的空气流

Desiccant dryers are good for applications where outdoor compressed air piping is subject to freezing. Critical applications, such as pharmaceutical and food applications, require the particularly dry air that is beyond what a refrigerated dryer is able to provide. There are three types of desiccant dryers used widely in the market: heatless, heated and blower purge. Energy costs vary by the type of desiccant dryer, with the energy use tied mostly to the manner of regeneration of the desiccant material.  

吸附式干燥机适用于室外压缩空气管道被冻结的场合。苛刻的应用环境,例如制药和食品行业,需要特别干燥的压缩空气,冷冻式干燥机无法提供。市场上广泛使用的吸附式干燥机有三种:无热再生吸附式干燥机、有热再生吸附式干燥机和鼓风机式再生吸附式干燥机。能源成本因吸附式干燥机的类型而异,能源的消耗量取决于干燥剂的再生方式。

Generating compressed air is an expensive process, and heatless dryers use about 15 percent of the compressed air emerging from the dryer to remove moisture from the desiccant beads, in order to regenerate it. This means that even though heatless desiccant dryers are less elaborate and often have no added electrical components other than the controls on the dryer, they can actually be higher consumers of energy compared to the other desiccant technologies because the cost of diverting 15 percent of the compressed air must be factored into overall energy costs.

压缩空气的生产是一项昂贵的流程,无热再生吸附式干燥机使用干燥机排出的15%左右的压缩空气来去除干燥剂中的水分,以便再生。这意味着,即使无热再生吸附式干燥机原理不那么复杂,而且除了干燥器上的控制器之外,通常没有额外的电气部件,但它们实际上可以比其他吸附式干燥机消耗更多的能源。和其他吸附式干燥机相比,无热再生吸附式干燥机消耗15%的成品干燥压缩空气,这个成本必须计入总能源成本。

Heated desiccant dryers incorporate a heater in the regeneration circuit of the dryer. This type uses a combination of heat and airflow to regenerate the desiccant adsorption beads in the regenerating tower. So while heated dryers consume additional energy with the supplementary heater, they use about half the compressed air for regeneration than that of heatless dryers. Therefore, heated dryers often are less costly to operate than heatless desiccant dryers. 

微热再生吸附式干燥机在干燥机的再生回路中装有加热器。这种吸附式干燥机使用热量和气流相结合的方式来再生塔中的干燥剂吸附剂。因此,当有热再生吸附式干燥机与辅助加热器一起消耗额外能量时,它们使用再生压缩空气的量只是无热再生吸附式干燥机的一半。因此,有热再生吸附式干燥机的操作成本通常比无热再生吸附式干燥机低。

The third type of desiccant dryer, blower purged units, do not use compressed air to regenerate the desiccant. Instead, this model has a dedicated blower to draw air from the surrounding environment. Because the airflow is generated by the blower, the total air capacity of the air compressor is available at the dryer outlet. This means the expense of compressed air for regeneration is not a factor, but there is the added energy use from the electric motor used to drive the blower. 

第三类型吸附式干燥机,使用鼓风机装置,这种吸附式干燥机不再使用压缩空气来进行再生。这种类型的吸附式干燥机有一个专用的鼓风机从周围的环境中吸收空气。因为气流是由鼓风机产生的,所以空气压缩机的所产生的压缩空气,在鼓风机式吸附式干燥机的出口没有损耗。这意味着不再产生再生压缩空气的费用,但是有一个因素要考虑,用于驱动鼓风机的电动机的附加能耗。

The bottom line with desiccant dryers regarding energy consumption: Dryers that rely on large quantities of compressed air for regeneration probably will be more expensive to operate than dryers requiring less compressed air. Of the different desiccant designs, the blower purge type has the greatest up-front cost but is often the most efficient to operate because it does not use expensive compressed air for regeneration. 

吸附式干燥机(使用干燥剂吸附)的底线是能耗:依靠大量压缩空气进行再生的吸附式干燥机运行费用可能比需要较少压缩空气的吸附式干燥机更昂贵。在不同的吸附式干燥机的设计中,鼓风机式的前期成本最大,但由于不使用昂贵的压缩空气进行再生,所以往往是在能耗上效率最高的。

Many manufacturers do make desiccant dryers with technology that can regulate the switching and the compressed air consumption based on the demands on the dryer, which helps to make them more energy efficient. Such energy management systems typically either sense if the moisture front in the tower has reached a certain level, or they measure the actual output dew point of the dryer. This technology can prolong the switch-over of the towers, so the dryer’s regeneration cycle is not starting on a fixed increment of time but instead being initiated based on demand. Alternatively, the energy management systems may hold the purge valves closed, preventing purge air from being used until it is needed for regeneration. 

许多制造商确实通过调节开关,根据实际应用需求,调节干燥机对压缩空气消耗的使用,来制造吸附式干燥机,这有助于提高能源使用效率。这类能源管理系统通常会感应到塔内的湿度是否达到一定的水平,或者测量干燥机的实际输出露点。这种技术可以延长吸附塔的开关时间,因此吸附式干燥机的再生周期不是以固定的时间开始,而是根据需要启动。或者,能源管理系统可以保持再生阀门关闭,防止消耗再生空气,直到需要再生时才使用再生气。

Reliability Issues 可靠性问题

While energy use accounts for a significant portion of a compressed air system’s operating costs, reliability also should be factored in when considering the total cost of ownership. 

虽然能源使用占压缩空气系统运行成本的很大一部分,但在考虑总的使用拥有成本时也应考虑到运营可靠性的问题。

Refrigerated dryers use hermetic refrigeration systems, meaning the refrigerant is not exposed to the atmosphere, so they typically require low maintenance and service to keep the system running. 

冷冻式干燥机使用密封制冷系统,这意味着制冷剂不暴露在大气中,因此通常需要较低的维护和服务来保持系统的运行。

Desiccant dryers involve frequent valve-switching to direct air to either the drying or regeneration tower, and these models often operate in high-heat, high-demand applications. Therefore, this equipment requires more service and valve maintenance. Downtime for that maintenance should be factored into the overall life cycle cost of the product. 

吸附式干燥机涉及到吸附塔和再生塔之间频繁的阀门切换,并且往往工作在高温和高要求的应用条件下。因此,该设备需要更多的服务和阀门维护。应该把维修的停机时间考虑到整个产品的生命周期成本中。

User Needs 用户需求

First and foremost, user needs should dictate the choice of dryer technology. Refrigerated dryers have substantially lower up-front and energy operating costs than desiccant dryers, but they are not able to provide air that is as dry. For general manufacturing processes, the refrigerated dryer option probably will be sufficient. Desiccant dryers provide the driest air for critical applications, but have higher up-front and energy costs. 

首先也是最重要的是,用户的需求应该决定干燥机的技术选择。冷冻式干燥机比吸附式干燥机具有更低的前期和能耗运行成本,但是它们不能提供像吸附式干燥机那样干燥的空气。对于一般的制造工艺而言,选择冷冻干燥机可能是足够的。吸附式干燥机为苛刻的应用要求提供最干燥的空气,但是有更高的前期和能耗成本。

In making the selection, users should consider if the pipe work associated with the process is located in a conditioned or unconditioned space. Desiccant dryers are the best choice if the piping is exposed to harsh conditions, such as temperatures that are below 40 degrees F. 

在做选择时,用户应考虑压缩空气管道是安装在有温度调节的空间,还是安装在室外。如果管道暴露在恶劣的条件下,如温度低于华氏40度(4.4摄氏度),吸附式干燥机是最好的选择。

If a downstream process machine requires that the air be drier than what a typical refrigerated dryer can deliver, point-of-use equipment may be the right answer. Such a system may use refrigerated dryers for most of the applications and desiccant models only where they are needed for specific applications.

如果下游的加工设备要求空气比典型的冷冻式干燥机所能提供的空气更干燥,那么在用气点根据要求再选择干燥机可能是正确的答案。这样的系统可以在大多数应用中使用冷冻式干燥机,只有在特定应用需要时才能使用吸附式干燥机。

Consider System Optimization考虑系统优化

While energy savings can be achieved by selecting the proper dryer for specific applications, system optimization should also be considered for all air systems to maximize efficiency and minimize operating costs. 

虽然可以通过为特定的应用选择适当的干燥机来节省能源,但也应考虑对所有压缩空气系统进行系统优化,以最大限度地提高效率和尽量减少运行成本。

Dryers are one part of a full compressed air system, and inefficiency of the system as a whole can have as much impact on energy costs as the dryers themselves. Fixing and repairing piping and valve leaks, maximizing air use within a facility and maintaining all compressed air equipment can help recoup the up-front dryer costs by ensuring the system as a whole is operating more efficiently.

压缩空气干燥机是全压缩空气系统的一部分,整个系统的效率低下对能耗成本的影响与压缩空气干燥机本身一样大。安装和修理管道与阀门,最大限度地利用工厂内的空气,以及维护所有压缩空气设备,可以确保整个系统更有效地运行,从而帮助收回前期压缩空气干燥机的成本。

The value of a compressed air audit and consideration of the system as a whole to determine true energy costs should not be overlooked. Compressed air system optimization is key for organizations looking to reduce energy costs. 

对压缩空气系统价值的审核和整个系统的统合考虑,才能确保真正的能耗成本不被忽视。压缩空气系统的优化是企业寻求降低能源成本的关键。


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