Cooling Water Temperatures

[Alex_Sor]

6 hours ago, Silk City Distillers said:

@Alex_SorWhat do the mathematical models say about the ideal surface area of the reflux condenser in relation to the column diameter or vapor speed?  How are you accounting for thermodynamic efficiency of the reflux condenser when moving from model to actual? (1)

(2) Asking because your models appear to assume 100% condenser efficiency.  13000 watts knock down, 7 liters per minute, calcs to roughly 26.6 delta T.

(3) Suppose you could just work backwards from 'rule-of-thumb' heat transfers and hope for the best.  For example, tube in shell in condensing mode being about ~3000w per square meter surface area, and oversize from there.

Good questions. I numbered them for accuracy.

(1) Thermodynamics has never been an exact science
The advent of computers made it possible to solve many problems at the same time, and choose from them those that are most suitable for the real situation. For example, the "Free Area Ratio of the Dry Packing" is 0.44 and the "Free Area Ratio of the Wet Packing" is 0.3.
What I have given above (picture) is calculated with an approximate safety factor of 1.1. In calculations from old textbooks, it was recommended to use from 1.1 to 1.3.
If we are talking about the full calculation of the column, then everything is more complicated.
The diameter of the column is calculated based on the required productivity for alcohol at the outlet, this gives us the steam velocity inside the column, then we calculate the volumetric flow rate of alcohol steam and water vapor inside the column, while taking into account the flow area of the holes (caps or sink holes). Complex formula
Then we choose the diameter of the column closest to the calculated size, while the Vapor Velocity is considered normal if it is within 0.5-1.2 meters / second. We calculate the minimum steam velocity in the holes of the plate. The shape of the caps or holes is also important, you can create a column that will work well at 2-5 meters per second steam velocity.
We calculate the hydraulic resistance of the tray at the top of the column. This will affect choking (coughing).

And only then we do the "Thermal calculation of the installation".
We calculate the consumption of heat given off to the cooling water in the reflux condenser. We do this for different reflux numbers, and choose something in between. After that we can calculate the "Dephlegmator surface". Heat losses and efficiency of the reflux condenser (or cooler) are calculated separately, taking into account the thickness of the walls of the tubes, the number of tubes, turbulence inside the reflux condenser, etc.

There are a lot of formulas There are a lot of tables of correspondence of theoretical calculations and tests in real devices. But ... it can all be boiled down to a "safety factor". The mathematical model allows you to "play with numbers" in 10 minutes and get the answer you need, with the required safety margin (performance).
This is Engineering Creativity I like creating things. Especially those that no one created, or believes that it is impossible to create them.

(2) The capacitor in the picture is, yes, 100%, but its calculations usually take a safety factor of 1.1. I can very accurately count the capacitor separately.

(3) "Practical heat transfer" is a very vague concept. I can apply a $100 solution to a dephlegmator that will increase its efficiency by a factor of 1.6 to 2.2. But I can do everything "according to the textbook" and get an efficiency of 60% instead of 90% ... Thermodynamics and "vortex processes" cannot be calculated accurately. Only mathematical modeling of flows makes it possible to roughly understand which of the solutions will be better for a particular job.

as an example of what I am saying, I will give a new picture
I played with numbers and got a more effective picture.

I have translated the inscriptions into English.
"cm3 per hour" is the cubic centimeter of the volume of alcohol per hour.

 

 

[crazyhorse67]

Alex_Sor, Southern highlander and SILK, thanks for this info I will be re-routing my cooling water set-up for my Condenser and 2 depheglamators as I have noticed issues with our current cold Canadian winter (H20 at 3 degrees celcius). I am also working on a water reclaimation system for this year( has anyone made or used cooling towers to cool their process water?)

Also, best wishes to Alex_sor with the current madness happening in your country. I hope it stops asap.

Thanks, Crazyhorse67

[SlickFloss]

On 3/1/2022 at 7:41 PM, crazyhorse67 said:

Alex_Sor, Southern highlander and SILK, thanks for this info I will be re-routing my cooling water set-up for my Condenser and 2 depheglamators as I have noticed issues with our current cold Canadian winter (H20 at 3 degrees celcius). I am also working on a water reclaimation system for this year( has anyone made or used cooling towers to cool their process water?)

Also, best wishes to Alex_sor with the current madness happening in your country. I hope it stops asap.

Thanks, Crazyhorse67

We use cooling towers glycol and city water for cooling in different places were basically in Canada , we are near superior 

[crazyhorse67]

I dont know if Alex_Sor or Slickfloss or Southern Highlander are still available for comment?. I am wondering what type of valves are being utilized, normally closed?. I am currently trying day one of this new cooling arrangement (Series) and have normally closed valves on my  2 tower condensers, but they are battling (no by-pass yet) so I have turned my first column PID actuators off (temp is about where I normally have it, within 1 degree C). I am also noticing my flow is starting at about 2 degrees C lower than normal and my steam settings are lower as well. Less heat input and less cooling is good right?. Any more tips would be greatly appreciated.

[Silk City Distillers]

If you are using PID with proportional valves, keep in mind that you can usually configure in an offset that doesn't allow the valve to go to 100% closed position, which will provide a controllable bypass.  For example, if you are using 4-20mA proportional control output to the valve, you can set the active range to 5 or 6-20mA (or some low level of voltage on 0-10v), which will allow for some minor bleed when the PID calls for no cooling.  This eliminates the need for any kind of physical bypass to be plumbed in and manually controlled.

[Alex_Sor]

22 minutes ago, Silk City Distillers said:

If you are using PID with proportional valves, keep in mind that you can usually configure in an offset that doesn't allow the valve to go to 100% closed position, which will provide a controllable bypass.  

PID controllers (for example, CAMOSSI) have an adjustment for the minimum current value (shifting the lower limit of the output signal). Required for valves whose opening is higher than the lower limit of the input signal, i.e. when the duty cycle of the output signal is higher than 0%.
And separately there is an adjustment of the maximum current value (shift of the upper limit of the output signal). Bias
down the maximum current value is used to limit the maximum flow rate of the distributor or when its solenoid is heated.

[crazyhorse67]

Thanks guys , much appreciated I will try to figure out these PID mods (might be above my pay grade being owner, distiller, carpenter,plumber,etc.etc. but why not add programmer to the resume too!) lol . Today I did put in a manually operated bypass !  try that tomorrow.

Alex _Sor I hope you are in a safe place.

 

[Alex_Sor]

9 hours ago, crazyhorse67 said:

Alex _Sor I hope you are in a safe place.

Thank you.
But there are no safe places in Ukraine now... Russian cruise missiles have a range of more than 1200 kilometers and fly at an altitude of about 20-30 meters. The entire territory of Ukraine is reachable by missiles. Our air defense forces shoot down missiles but cannot close the whole sky...
Howling air raid sirens, several times a day. Constant drone attacks...
the Russians are bad soldiers, but they have accumulated a huge amount of missiles and weapons... it is a wild horde, like a swarm of locusts that has no number...
But we will win.
We have no other choice. Either we win or become slaves and die. We choose to fight for our freedom and our lives.