air-cooler winterization options

[vesselguy]

Hi,

I searched this site for posts on this subject and came up empty so I'd thought I'd start a new thread.

I know of two choices for winterization of forced draft coolers: electric heating coil at air inlet to coil and hot air recirculation. I'm no expert on air-coolers so I don't know if there are other viable options. Can anyone give me some pointers on this subject and the pros and cons of each? I don't have API RP632 so I'm at a disadvantage in this matter. Thanks.

 

[dcasto]

We used gatural gas direct, yuck! You can also use a hot oil system that is like the recirculation system where you recirculate and warm with hot oil in in coils. This takes a second fan.

 

[vesselguy]

dcasto,
What do you mean by natural gas direct?

For the second method, you mention hot oil. Are you saying heating the inlet air to fin-fan with a hot oil coil?

 

[speco]

Vesselguy,

The other common option is to use a steam coil below the process tube bundle. Of course, it only works if you have steam available. A steam coil would be used primarily for startup, and in conjunction with a warm-air recirculation system.

Regards,

Speco (

http://www.stoneprocess.com)

 

[dcasto]

What do you mean by natural gas direct?

A burner ring under the fan burning gas. The hot gases are pulled through the coils. I would only use in water cooling service.

Yes, you'd have a fan blowing air across coils that have hot oil running through them. That air would be mixed with the recirculation air on an enclosed cooling fan to assure you get enough heat into the system. You could control the oil flow or fan flow based on the air temperature as it starts to pass by the tubes in the exchanger.

 

[djack77494]

Depending on what you mean by winterization,
- Adjust position of louvers to reduce air flow
- Use a 2 speed or VFD fan to same effect (Can even reverse air flow for more dramatic impact)
- Vary the fan blade pitch to impact air movement
- For multiple bays, isolate/remove from service some bays in cooler weather.
- Hot fluid bypass can be effective in obtaining desired mixed temperature regardless of ambient conditions, but only if the cooled fluid would not freeze

For a higher quality response, please provide better information about what your needs are.
Doug

 

[chief]

Fit an AMOT 3-way type thermostatic valve to your process ,configure it to bypass your cooler and set it to maintain whatever temperature your process requires.

Offshore Engineering&Design

 

[geodesia]

For winterization tpes, control required, etc...please refer to API661