[Genma Saotome]

If you want to code up a simple feedwater heater try this: take an amount of steam whose latent heat will raise the injector water to 211F or thereabouts, and having done so that "spent" steam will condense back to water where it is returned to the tender. And so the question becomes how much steam is needed? The answer appears to be that on average all feedwater heaters will return to the tender 15% of the water that has been boiled, which I assume means 15% of the steam is used in Feedater heating.

My guess is injecting 211F water into the boiler will serve much better in keep the pressure up than water at ambient temperatures.

I can dig up the manual if more info is needed.

[copperpen]

If you can find it, please send relevant info to steamer_ctn as he is the one writing the steam code.

[scottb613]

Hi Mervyn,

Thanks for the additional info - let me give that a try...
:p

Regards,
Scott

[steamer_ctn]

Some feedback to some of the comments:

scottb613, on 25 January 2015 - 03:42 PM, said:

Are feed water heaters modeled in ORTS and if so - which injector would they be associated with... I don't recall seeing any values in the ENG files associated with them...

There is some simple code that allows for feedwater to be heated, hence, as you suggest, the variations in the temp values near the injector values.

scottb613, on 25 January 2015 - 04:11 PM, said:

A little more information - I'm trying to hand fire - and I'm having great difficulty keeping my boiler pressure up... By the Steam HUD attached - it seems as if I am making way more steam than I'm using - but - that surplus steam doesn't seem to be making boiler pressure increase... I turned off the injectors - I have the Reverser pretty close to cut off - and - still I can't seem to recover the boiler pressure - max 220 lbs... Any idea on my screenshot on what I am doing wrong ???

What is happening to the "Heat" figure on the RHS side of the HUD? Is it going up or down? This figure is one of the main variables that will impact the boiler pressure.

Lindsayts, on 25 January 2015 - 05:13 PM, said:

Try an earlier version , I am getting a simliar thing from the 23rd Jan release the previous release tried from a week or so back worked OK.

There appears to be some change in the steam code which has changed it a good bit.

The burn rate curve was adjusted to a more realistic prototypical value. It determines the amount of coal burnt based upon the amount of steam used by the locomotive.

scottb613, on 26 January 2015 - 04:06 AM, said:

I was going to ask about the "Stoker" on the HUD - as it always seems to be set to false - I didn't see any way to set it to "True"... That said - currently - I do seem able to increase the "Firing Rate" sufficiently to keep the "Fire" at 100% - not sure if that's due to an "Eng" file setting or how a mechanical stoker would change that ???

There is a parameter that needs to be set in the ENG file. Have you looked at the manual?

Maintaining the firemass is not as important as matching the burn rate to the steam usage. The firemass can afford to drop a bit without overly impacting the performance.

scottb613, on 26 January 2015 - 04:06 AM, said:

As posted above - I had read an article that agrees - stated that the engineer would simply leave the regulator open - and - use the Reverser for speed/steam control - which is typically how I run in ORTS...

That is certainly the ideal way to drive.

Eventually if the locomotive goes fast enough with a heavy load, then steam usage will exceed the steam generation rate, and the steam pressure will fall. In this case the driver will need to maintain the speed at a lower rate.

In general, the AI and manual fireman are two completely different functions.

For example, a manual fireman is more intelligent then the AI fireman, as he can "know" the route, and build up his fire in advance when expecting extra effort required by the locomotive, whereas the AI fireman reacts to the steam usage, and therefore will always be "late" in responding. Thus it is possible to see steam pressure dropping when first starting, depending upon how "fast" the rate of start is, but provided the start is not too aggressive, and the reverser is wound back at the correct time, then hopefully it should start to recover.

So it is important to only operate in one of the firing modes, and any comparisons between the two may not unrealistic.

[scottb613]

Hi Peter,

Thanks for the detailed response... LOL - I did read the steam part of the manual - I wasn't specifically looking for the stoker at that time - let me go back and look again... I'll play with some more - the ENG file is my own so there could be mistakes in that as well...

Let me do some more runs and watch the "heat" figure you mentioned - from my experience - if I keep the boiler pressure up - I can manage to keep it up - if for any reason I let it drop - that's when I find it almost impossible to gain it back again...

Regards,
Scott

[steamer_ctn]

scottb613, on 27 January 2015 - 10:14 AM, said:

Let me do some more runs and watch the "heat" figure you mentioned - from my experience - if I keep the boiler pressure up - I can manage to keep it up - if for any reason I let it drop - that's when I find it almost impossible to gain it back again...

Sounds like a good plan.

If you are still having problems, let me know and we can set up a standard test to try and sort it out.

[Genma Saotome]

Feedwater Heater Principles / The Superheater Company (The LS Co. -- Elesco).

The applies to heat exchanger Feedwaters, such as Elesco and Coffin.

• Perhaps as much as 58% of the BTU's used to create the steam exit the locomotive via the stack.
  
• Feedwater Heaters divert a portion of that escaping heat to transfer heat by conduction into the water going into the boiler.
  
• Conduction of heat from the exhaust steam will raise the temperature of the feedwater to 200F to 250F degrees (it says that by being contained within the unit the water temp can be raised to 250f and remain water).
  
• Live Steam is used to operate a pump drawing water from the tender.
  
• After the Conduction of heat the exhaust steam condenses into water and by gravity returns to the tender. This averages 13-15% of water used, more likely towards the higher number.
  
• The event of condensation produces a slight vacuum that reduces back pressure in the cylinders.
  
• Normal operation is to run the Feedwater pump on a continual basis injecting a low quantity of water at all times. Adjustments can be made to the pump rate to reasonable adjust to water requirements due to changes in the water level.

The text implies but does not clearly state there is a close relationship between the amount of exhaust steam being used for the Feedwater and the amount of water recovered. It seems to me that ought to be 1:1 but the literature suggests it is not equal... that perhaps a ratio of 1:0.875 (water:steam) is correct). Why? I dunno.

Mixing type Feedwater Heaters (e.g., Worthington) are not in the manual I have but reviewing material on the web it doesn't appear the overall differences are very great.

=====================
Given the above it seems a simple approximation of a Feedwater Heater could be added to OR by:

• Increasing the water temps going into the boiler to somewhere in the range of 212F to 250F.
  
• Assume usage of live steam is already covered in loss due to Auxillaries.
  
• Return 15% of all boiled water to the tender.

If more information becomes available it might be possible to code the differences in the type types of Feedwaters -- Exhaust/Heat Exchanger types and Mixing types but for now that information is not in hand.

Is there a Feedwater Heater() parameter in the .eng files?

[steamer_ctn]

Genma Saotome, on 27 January 2015 - 12:30 PM, said:

Feedwater Heater Principles / The Superheater Company (The LS Co. -- Elesco).

Thanks for the information. I would prefer some more details to be confident of building a reasonably accurate representation of the water heater.

For those interested:

The injectors in the current OR model are based upon information extracted from this publication.

Sellers Injector

It indicates that the temperature into the boiler is based upon the steam pressure, and the amount of water flowing through the injectors.

A series of reference tables were built to represent the performance described in the above publication. This can be seen by watching the injector information in the Steam extended HUD.

[Genma Saotome]

Peter, I there are a number of tables in Google Books for the Worthington heat that shows how many BTU's are being used under different conditions to heat the water. Is that what you need?

[Genma Saotome]

Well.. a very nice discover: Johnson's Steam Locomotive (1945) has been digitized and given full view. Feedwater discussion begins on page 101.