Technical information - Welded spiral heat exchangers

How do spiral heat exchangers work

Alfa Laval spiral heat exchangers are circular units containing two concentric spiral flow channels, one for each fluid. The different media flow counter currently: one fluid enters the centre of the unit and flows towards the periphery, the other enters the unit at the periphery and moves towards the centre. The channels are curved and have a uniform cross section. There is no risk of intermixing.

The product channel is normally open on one side and closed on the other. The channel for the heating/cooling medium can sometimes be closed on both sides, depending on the cleanliness of the heating/cooling medium. Each channel has one connection in the centre and one on the periphery of the heat exchanger.

The single-channel geometry also creates a scrubbing effect that we refer to as the SelfClean™ design. If fouling does occur in the heat transfer channel, the cross-section of this part of the channel is decreased. However, since the entire flow must still pass through the channel, the velocity increases, the resulting fluid force then flushing away any accumulations of deposits as they form.

Compare this design with shell-and-tube heat exchangers where the flow enters different tubes in parallel. When tubes start to foul, pressure drop increases pushing the fluid to find alternative flow paths. The result is that fouling and clogging of the tubes happens very quickly. With Alfa Laval spirals, on the other hand, fouling and clogging is virtually eliminated.

Our welded spiral product range

阿法拉伐的 SelfClean™ 构造使 SpiralPro 模型换热器成为处理脏液、污泥、乳液、浆液、纤维或颗粒负载液体时的明智选择。 由于流体在单个通道中连续流动，因此流体力可作用于任何沉积物，“推动”它们通过通道，并从另一端流出。

SpiralPro 模型的紧凑特性使得我们通常可使用一台 SpiralPro 交换器来替换几个大型管壳式换热器。除了减少维护和清洁要求外，还可以带来可观的基础设施优势。 如果设备需要清洁，可以很容易地拆下盖子，并用水力喷射器清洗。

应用

• 含有固体、纤维、液体、浆液和污泥的污垢液体
• 液体至液体的预热、加热、冷却、互换和热回收

还提供经过优化、可用来蒸汽加热高度污染的液体的 SpiralPro 型号换热器。 与所有 SpiralPro 装置一样，这些装置完全可以通过液压喷头快速方便地清洁。
逆流流动还确保了非常小的温差，以实现最大的热效率。

应用

• 需要蒸汽加热的含有固体或纤维、液体、浆液和污泥的污垢液体以及其他具有挑战性的流体。

SpiralCond 模型换热器为挑战两相任务提供了高效解决方案，包括冷凝和蒸发（再沸）。 与同等的管壳式换热器相比，SpiralCond 的紧凑设计和垂直配置使其占地面积非常小，同时还减少了支撑结构和管道复杂性。

SpiralCond 装置具有交叉流动，而非逆流流动。 每个单元都根据所需的负载完全定制，通道间距经过调整，可提供最低压降。 因此，阿法拉换热器SpiralCond 非常适合真空冷凝应用。

应用

• 气体：纯蒸气和含有惰性气体的混合物
• 蒸汽/液体：顶部冷凝器、回流冷凝器、真空冷凝器、排气冷凝器、带有污垢液的再沸器、气体冷却器 

对于涉及多种冷却介质的冷凝和蒸发的应用，阿法拉伐可以提供集成在塔中的 SpiralCond 型号换热器。 与单独的独立式阿法拉伐换热器 SpiralCond 一样，这种配置具有交叉流动和开放通道，可在真空情况下实现极低压降。

与传统塔式解决方案相比，高效率 SpiralCond 使塔的高度更短，直径更小，从而大大节省了基础设施和安装成本。

应用

• 汽液：顶部冷凝器、回流冷凝器、真空冷凝器和通风冷凝器

Unique features of Alfa Laval Welded spiral heat exchangers

Superior cleaning and extended performance

The SelfClean design of Alfa Laval spirals provides a reliable solution for fouling and clogging in duties involving challenging fluids, sludges, emulsions, slurries, fibres or particle loaded liquids.

Each circuit on a spiral unit consists of a single flow channel. This continuously curving, single-channel geometry creates high turbulence to minimize fouling from the start. If fouling does start to occur, local velocity increases, since the entire flow must still pass through the channel. This creates a scrubbing effect that flushes away any accumulations of deposits as they form.

An additional benefit of this design is that it eliminates the risk of dead spots and stagnation for more efficient heat transfer.

Automated, reliable channel enclosure

The manufacturing of Alfa Laval’s spiral heat exchangers incorporates an automated process for bending the edge of the channels. This is followed by a cold-metal-transfer automatic welding machine for the final closure weld.

The combined effect of this so-called RollWeld technique is consistent quality of the channel closure. That, in turn, is critical for the strength and corrosion resistance of the channel welds and thus the reliability of the overall unit.

A custom solution for high-pressure duties

For customers whose processes demand higher design and differential pressures than traditional spiral heat exchangers can provide, Alfa Laval offers capabilities to fully tailor a unique solution to match their needs.

We design our HighP spiral heat exchangers using a range of features, including a double gasket system, a self-supporting internal coil, and a special body and shell with bolted cover. Our experienced engineers work with you throughout the design process to make sure you get the ideal heat exchanger for your specific challenges.