In Acrylonitrile (ACN) plants, various types of heat exchangers are commonly used for different purposes. Here are some types typically found in such industrial applications, conforming to standards like ASME Section VIII Div 1 & Div 2, TEMA, API 660, and design software like HTRI and PV Elite:

1. Shell and Tube Heat Exchangers: These are versatile and robust, consisting of a series of tubes (often made of stainless steel or other alloys) through which one fluid flows, while another fluid passes over the tubes within a larger shell. They are used for various heating and cooling duties in ACN plants.

2. Plate Heat Exchangers: These consist of multiple thin, slightly separated plates that have very large surface areas and fluid flow passages for heat transfer. They are efficient in transferring heat between fluids and are compact, which can be advantageous in ACN plant designs.

3. Air Cooled Heat Exchangers (ACHE): ACHEs are used to cool fluids with ambient air. They consist of finned tubes through which process fluid flows while ambient air is blown over the tubes to dissipate heat. They are often used for cooling duties in ACN plants where water availability or quality is a concern.

4. Finned Tube Heat Exchangers: Similar to ACHEs, finned tube heat exchangers use extended surface area (fins) on the tubes to enhance heat transfer between fluids. They are used in ACN plants for specific heating or cooling applications where enhanced heat transfer is required.

5. Coil Wound Heat Exchangers: These are specialized heat exchangers where the tube is wound in a coil configuration. They are used in ACN plants for applications where compact design and efficient heat transfer are critical.

6. Plate-Fin Heat Exchangers: These are compact heat exchangers with layers of corrugated fins sandwiched between flat plates. They offer high heat transfer efficiency and are used in ACN plants for specific applications where space and weight are considerations.

These heat exchangers are designed and fabricated according to various international standards such as ASME Section VIII Div 1 & Div 2, TEMA (Tubular Exchanger Manufacturers Association) standards, API 660 (shell-and-tube heat exchangers), and are often analyzed using software like HTRI (Heat Transfer Research, Inc.) and PV Elite (pressure vessel and heat exchanger design software).

Each type of heat exchanger has its advantages depending on factors such as required heat transfer rates, fluid properties, pressure and temperature requirements, space constraints, and maintenance considerations in ACN plants.