Boilers - complete novice

[Kinish]

I need to replace an existing steam generator with a new boiler (either superheated steam, superheated water, or thermal oil). The steam generator is used to heat 3 platens in a Sennerskov rubber moulding press. The steam generator is not fit for its purpose and may have been under-spec'd resulting in prolonged heating and cycle times.

What is the best heating medium?
Where is the best place to start when getting specification for a new boiler?
Are there any useful websites I can consult?

 

[quark]

Heat capacity will be same in all cases but superheated water or hot oil units require larger flowrates than a steam boiler for a given heat capacity. It is still worse if you are using only superheated portion of steam rather than its latent heat. Better speak to some boiler manufacturers.

 

[unclesyd]

You need to get all the physical parameters of your machine before you start an inquiry.

This includes but is not limited to heat capacity needed per machine, max temperature, what type controls, and allowable pressure in the heating jacket.

If you could comeback with this information you will probably get a better response to your inquiry.

 

[davefitz]

You will need to determine the requirements of teh rubber platens. Itis my guess that they have an optimum heating temep, and not-to exceed temp. Following that line of thinking , the best boiler for that application is one that provides saturated steam at a saturated steam temp equal to the not-to-exceed value. Maximum rate of heat transfer is avialable by the condensing of the steam within the platen.

 

[slagman]

You will need to define what your steam/power requirements are to run your facility and what degree of fuel flexibility you can live with. Coal is an option but gas/oil may be easier.

Establish your mass of steam per hour requirement and then talk to boiler manufacturers.

 

[Kinish]

The main problem I have is finding out the steam requirement of the platens. Can anyone help regarding this? The manufacturer insist they cannot help. We have been using an under spec'd boiler for 5 years.

Is it dangerous to oversize a boiler?

 

[quark]

The dangers of oversizing can be mitigated by proper controls but you will always loose efficiency if you are running your boiler below 75% load. You will also have problems with wetsteam.

You can make a rough calculation about the steam consumption by calculating the sensible heat given to the rubber (i.e the mass flowrate times specific heat of rubber times the temperature difference of initial and final conditions) and latent leat (i.e how much moisture is being removed from the rubber). For start up loads, you should also consider the steam requirement for heating the plates.

 

[chicopee]

Be careful about your term- superheated water- no such thing.