取样冷却装置选型指南（中英文）

各种工厂和设施都使用取样冷却器来冷却来自工艺流的样品。

作为蒸汽和水采样系统的一部分，冷却样品对于保持样品的安全性和代表性至关重要。

例如，如果发电厂中的样品过热而无法处理，操作员可能会将流量限制到不可接受的低水平，这意味着样品不再具有代表性或可接受性。

另一个例子来自碳氢化合物加工或过程分析。冷却过程以处理样品是必要的。如果用户采集某种碳氢化合物的样本，无论是液体还是气体，最安全的方式是在低于 140F 的温度下处理样品。这可以保护操作员在处理需要安全地带到实验室进行分析的热样品时的安全。

为了获得准确的数据，电力研究所 (EPRI)、ASTM 和 ASME 建议将水样冷却至 77°F (25°C)，以确保一致、准确的测试结果。

Plants and facilities of all kinds use sample coolers to cool a sample from a process stream.

Cooling samples as part of your steam and water sampling system is essential to maintaining safety and the representativeness of the sample.

For example, if a sample in a power plant is too hot to handle, the operator might throttle the flow to unacceptably low levels, which means the sample is no longer representative or acceptable.

Another example comes from Hydrocarbon processing or Process Analytics. Cooling the process to handle the sample is necessary.   If you take a grab sample of a certain hydrocarbon whether it be of a liquid or a gas, the safest way is to handle the sample at below 140F.  This protects the operator when handling hot samples that need to be physically taken to the lab safely for analysis.   

In order to achieve accurate data, the Electric Power Research Institute (EPRI), ASTM and ASME recommend cooling water samples to 77°F (25°C) to ensure consistent, accurate test results.

取样冷却器的工作原理

HOW SAMPLE COOLERS WORK

取样冷却器只是一个小型壳管式热交换器，其工作原理如下：

要冷却的样品流过冷却器的管侧

冷却液（通常是水）流过壳侧以降低样品的温度。

冷却后的样品被送往实验室进行分析或通过管道输送到在线过程仪表，以连续监测某些特性，例如电导率、pH 值或化学成分

A sample cooler is simply a small shell and coil heat exchanger that works like this:

The sample to be cooled flows through the tube side of the cooler

The cooling fluid, usually water, flows through the shell side to cool the temperature of the sample.

The cooled sample is taken to a laboratory for analysis or piped to on-line process instrumentation for continuous monitoring of certain properties such as conductivity, pH or chemical constituent

满足需求的3 种冷却器

3 TYPES OF COOLERS TO FIT YOUR NEEDS

有多种冷却器设计用于液体、气体或蒸汽工艺中的大多数应用。

1. 螺旋盘管 – 紧凑、高效的取样冷却器，包括一根螺旋盘绕并安装在壳体中的连续管。

2. 螺旋管 – 这些冷却器具有螺旋盘管和歧管组件，安装在紧凑的壳体中，可优化传热效率和空间。盘管和壳体流道的螺旋形状产生离心力，从而以真正的逆流布置增强两侧的传热。它们经过优化设计，可用于腐蚀性流体和气体。

3. 管中管 – 这些螺旋缠绕的全逆流热交换器非常适合各种需要加热或冷却低流速高压和/或高温流体的应用。

There are several types of coolers designed for most applications in liquid, gas or steam processes.

1. Helical Coil – The most compact and highly efficient kind of sample coolers, these include a single continuous tube that’s helically coiled and fitted in a shell.

2. Spiral Tube – These coolers have a spirally coiled tube and manifold assembly fitted into a compact shell that optimizes heat transfer efficiency and space. The spiral shape of the coil and shell flow paths creates centrifugal force that enhances heat transfer on both sides in a true counterflow arrangement. They’re optimally designed for use with corrosive fluids and gases.

3. Tube-In-Tube – These helically wound, full counter-flow heat exchangers are well-suited for a variety of applications where low flow rates of high-pressure and/or high-temperature fluids need heating or cooling.

选择取样冷却器时需要考虑的事项

CONSIDERATIONS NEEDED WHEN CHOOSING A SAMPLE COOLER

足够的流量

真正具有代表性的样品需要足够的样品流量。因此，取样冷却器的尺寸将由样品所需的流速和蒸汽入口压力决定。例如，EPRI 建议水样的流速为每秒 6 英尺（1.8 米）。对于蒸汽样品，由于蒸汽流向样品面板时速度很快，因此流速较低。通常，每分钟 500-1,000 cc 之间的流速就足够了。

两级冷却

如果要将样品送入在线分析仪，粗略冷却可能不够。一些分析仪，特别是电导率和 pH 值分析仪，对温度非常敏感。为了达到推荐的 77°F (25°C) 温度，样品的两级冷却首先使用工厂冷却水粗略冷却热样品，然后使用机械制冷。

安装

取样冷却器可以垂直或水平安装，但最好将其垂直安装在高温管线上。冷却器通常还安装在冷却水管道中隔离阀，以方便维修。

维护和维修

大多数冷却器只需要偶尔对壳体侧进行除垢，这可以在拆除壳体后以化学或机械方式完成。

在为设施选择合适的取样冷却器时，重要的是要考虑每条取样管线的要求，以确保足够的流速并优化冷却水的使用。

Adequate flow

A truly representative sample requires adequate sample flow. Because of this, the sample cooler size will be determined by your samples’ required flow rate and the steam inlet pressure. For example, EPRI recommends a flow rate of 6 feet (1.8 m) per second on water samples. For steam samples, flow rates are lower due to the high velocity of the steam as it flows to the sample panel. Generally, flow rates of between 500-1,000cc per minute are adequate.

Two-stage cooling

If the sample is to be fed to an in-line analyzer, rough cooling might not be sufficient. Some analyzers, particularly conductivity and pH, are very sensitive to temperature. To reach the recommended temperature of 77°F (25°C), two-stage cooling of the sample first rough cools the hot sample using plant cooling water, then uses mechanical refrigeration.

Installation

Sample coolers can be mounted either vertically or horizontally, but it’s best to mount them vertically on high-temperature lines. Coolers are also typically installed with isolation valves in the cooling water piping to facilitate service.

Maintenance and service

Most coolers need only occasional descaling of the shell side, which can be done chemically or mechanically after removing the shell.

When selecting the right sample cooler for your facility, it’s important to consider the requirements for each sample line to ensure adequate flow rates and optimize cooling water usage.