Jesus you guys dont give up with the bro science.
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Wide till the condensor where the gas needs to get in contact as fast as possible with the cold surface
So a lot off thiner pipes or plates
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Yes, the larger the orifice (A) the larger the flow rate. So even if you run into the issue of a choke point (based on pressure difference) increasing the diameter of your flow orifice Willa improve flow rate
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If the recovery vessel is kept @ -80c there might not need to be a coil. 
Thought this design out a while ago then saw Bhogart moved to all hard lines on their system.
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It will work but I think it be better if a forced touching off cryo surface is implemented either by coil/ angel/ tube in shell like the glass coldtrap s
For a coil I now use a sshotwater boiler set in a maner that by means of gravity the coil empty s itself of liquids
We are used to putting the coil in a bucket having to push all condensate out
By cutting the botom of a hot water boiler tank and flipping it I have the coil set in. The tank(bucket) and place dry ice in there
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That was my theory when designing our system. However, maintaining -80c tank temperature, while recovering up to 10 lbs per minute is literally impossible with dry ice and open jackets. The coils are necessary to increase surface area, but don’t be fooled, they do not aid in reducing dry ice consumption, only rather allowing you to recover faster.
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There seems to be several branches to these issues worthy of detailed cost, energy, product quality and engineering analysis.
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Solvent pre-chilling (Ethanol is the most demanding for this)
a. LN2 or Electric Refrigeration with chilled Ethanol or butane at (-40,-48 or -60 Deg C)
b. In the case of hydrocarbon you could run warm(room temp) Butane and CRC later…(ick)
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Solvent Recovery (This one is tough because it is heavily influenced by extractor design, bizzybee systems would be good comparison benchmark as they can run LN2 or electric and are designed with large connections between vessels)
a. Passive via Electric Refrigeration or LN2 (Ethanol or butane)
b. Active via Pump (Hydrocarbons only)
i. Type of Pump (TRXX, MXX, HaXXXX, CoXXX) (Others?)
ii. Electric or Air Compressor driven (Includes power/capital costs)
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Solvent Heating Evaporation
a. COTS stand alone heat source (Electric or natural gas, costs)
b. Waste heat recovery from electric refrigeration system
c. Combination of a and b
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Overall complexity of extraction system and process
a. Review which parts are required for each possible configuration and estimated costs from various vendors, extractors heat exchangers etc. Difficult to do a true apples to apples comparison.
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Why do you prefer ln2 over lc02? Or is that just what you used in your trials as a control?
LN2 was supposed to be the control but I guess we could include both if there is interest.
Was just curious.
What does CLS stand for?
Closed Loop System
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Here to follow.
Running a passive cls currently eith just bho
I appreciate your explanations
What I am curious about is in the heat exchanger you use in your unit
What material is it made of ?
What is the heat transfer on butane and propane and the 30/70 mix ?
What diameter is the tubing ?
In a perfect situation what would the max condensation rate be ?
Thx
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This is helpful, thank you.
Their calculations support the same trends I was getting which is total ownership and operating cost of a mechanical refrigeration system which is ~8 times lower than LN2.
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For the food grade direct (R-507) refrigeration heat Ex see pg 2 of the spec sheet for a picture:
https://www.greenprocess.solutions/2020/01/13/40-ton-refrigeration-system/
The heat Ex is double pass and uses seamless 316 tubing, and has ASME and CRN numbers. It can be optionally electropolished for an additional 26,430.-USD
See example PID below:
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I’m confused by your CNG vs LNG analogy.
When you talk about CNG being better for small scale and LNG “dominating” at large scale, what exactly are you talking about? Fleets of vehicles? Or the general transmission and storage of natural gas on a global scale?
Either way your association of pumps (CNG) with smaller capital costs and smaller scale doesn’t seem to make sense here.
Recovery rate (speed) is generally not determined or provided by any pump/compressor or lack thereof. It’s determined by vapor generation in the evaporator or collection pot.
A pump that’s undersized will act as a restriction but a pump that’s oversized will generally not increase recovery rate although there may be some minor “scavenging” effect like a car’s exhaust manifold.
The recovery setup of an extractor is all about overall system design and workflow.
Generally at smaller scales in cannabis extraction the recovery pumps used (TR21, CMEPOL) often act as a major restriction due to their small pumping capacities and people see an increase in recovery rate switching to passive but sacrifice certain operating abilities.
Fluid characteristics and flow characteristics are two different things.
Just because the fluid itself is compressible, doesn’t mean the flow is.
Whether or not a flow is considered compressible is directly related to the value of the Mach number (speed) of the flow not the properties of the fluid itself.
Mach number is the ratio of flow velocity past a boundary compared to the speed of sound in that fluid.
Choked flow only occurs when the exit velocity from the orifice is at or very close to Mach 1, or 100% the speed of sound in that fluid. This is related to the critical pressure ratio across the orifice like you mentioned, but where are you thinking this is occurring in an extraction system? Why do you think the inlet of the pump would cause this?
I don’t see how the inlet to the compressors used in extraction would cause choked flow as you describe.
I think it’s possible you might be confusing choked flow through an orifice with compressor choking or stonewalling. Compressor choke is a property of dynamic (centrifugal) compressors, not positive displacement compressors like the ones we typically use in extraction.
Although some people erroneously think so, a gas compressor (pump) is not used in an extraction system to speed up recovery rate.
I agree that it’s very important to not have any restrictive orifices in the vapor recovery stream. The typical Swagelok GS series process valves that are used do indeed have a restrictive orifice size at the larger connection sizes and I make sure to use 63 series or full port valves on my vapor side to avoid flow restriction.
I’m not saying it’s impossible to have choked flow conditions in extraction systems, especially huge falling films and very large collection pots but I think it’s very unlikely.
Compressible flow and choked flow seem to be more an issue in high speed (mach 1) aircraft, jet engines, rocket nozzles and high pressure gas pipelines (I am familiar with orifice plates).
I would say this really depends on the specific situation.
For a very large batch or continuous system with intermediate tanks and falling film evaporators it could be a good choice to just go passive. Just like for ethanol and other hydrocarbons.
I personally think that for batch systems up to very large batch sizes that want to rely on a one tank closed loop system (recovering into the same tank you flood from), it will be simplest and most efficient to have a vapor recovery pump in the loop, probably as part of a hybrid recovery setup.
I think the real answer for ultimate efficiency with a balance of overall system ease of workflow and recovery rate a hybrid recovery circuit would be the best choice, see my post in the other active/passive thread.
There are definitely periods during my (active) recovery toward the top of the bell curve of the difference between vessel pressures where a passive circuit would make sense to add and I have pondered putting a simple bypass line with a one-way check valve around the pump to take full advantage.
As systems and vessels get larger, I think it becomes more difficult to keep the entire volume of solvent at low enough vapor pressure on the recovery side to keep up peak passive recovery efficiency. Not to mention vapor assisting. This is all compounded if the operator wishes to use a high propane mix.
I think your assertions about noise and hazards from recovery pumps and air compressors is somewhat moot. Obviously some people are more sensitive than others but I have worked in shops my whole life and don’t have any problems with these issues. I know the old Haskel’s can be a little loud in the operating booth with all the knocking but pumps like Corken, Blackmer and LeRoi are very quiet pumps and not a problem at all.
With respect to teflon and metal shavings, I don’t think the effect is really that bad. Especially with a proper pump like a Corken that is actually designed to pump hazardous gases like ammonia for years and years. A diaphragm pump like an MVP is probably even less prone to shedding contaminates.
Also, most extracts are filtered down to 1 micron these days with the advent of CRC which would handle any detritus that would find its way in.
Honestly, I think most contaminates come into the system on the input material itself.
I remember I was out in the hills one time and I saw some guys working on a greenhouse frame around plants and had to take a grinder to something they were working on. They had setup a blanket to act as a shield but I’m sure some metal shavings made their way onto the plants.
I understand that you’re trying to do some marketing here for your company and that’s all good.
It’s not a surprise to me that a mechanical chiller will be cheaper over time than a constant consumable like liquid air gases. That seems very obvious and I don’t think anyone is debating that fact.
However there are still several arguments for why someone would want to stick with liquid air gases over a mechanical chiller like financial ability, equipment reliability, electrical hookup availability, ability to modify the existing building, etc.
Marketing this from the angle that chiller systems like the ones you offer save money in the long run vs a constant consumable makes sense.
I think using this logic to say that passive is a better or simpler option for batch extraction systems is a stretch and may be the result of some confirmation bias you have toward the products you’re trying to sell.
The active/passive debate is much more about workflow design, throughput and system design simplicity, IMO, than it is about overall recovery rate.
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Respectfully, you are incorrect dear sir.
I dont have the time/energy to respond to your entire post.
Please review my underlying calculations if you wish, specifically:
https://www.instagram.com/p/B4ZTOKch4Vl/
Which uses formula for Mdot found here:
I maintain that most if not all extractors passive or active experience flow choking.
Review the numbers below, tell me if you can find fault with them:
Nomenclature:
Mdot = Mass flow rate [g/s]
M = Mach Number [Dimensionless]
γ = Ratio of specific heats [Dimensionless]
P = Pressure [Pa]
Rho = Density [kg/m^3]
u = Speed of gas in the pipe [m/s]
c = Sound speed of the gas [m/s]
Cd = Coefficient of Discharge [Dimensionless]
Cv = Flow Coefficient [Dimensionless]
A = Orifice cross sectional area [m^2]
k = (1.094) Butane, Propane (1.13),
Example Pressure P0 = 206,843 [Pa] (30 psia)
Example Density ρ = 5.29 kg/m^3 (5.29 g/L)
Example Area (for 0.5” Dia) orifice A = 0.0001267 m^2
Example Cd for smooth surface Cd = 1 (ideal, typical values 0.8-0.9)
I understand your point about confirmation bias, and yes at smaller scale a pump may be more expedient, however analytically speaking I have not found a valid counterargument to my analysis in your post.
Respectfully,
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I get it man. I’m busy over here too.
But you did have the time/energy to write out your whole OP.
And time to bump up other active vs passive threads while pointing people to this thread to buy your chillers.
If you pop up on the scene one day and make some new claims, it would make sense for you to respond to a rebuttal of your claims. Especially if you’re selling something.
Why not at least explain the CNG vs LNG thing?
I don’t think you’ve really provided sufficient evidence for a lot of what you’re claiming here.
Your OP just kind of stumbles into the idea of choked flow out of nowhere with no real context.
This is sounding a little like charlatanism to me. Or the confirmation bias thing.
Below is my work solving the given equation using the variables you provided for a 1/2" orifice in your last post.
The answer I get for max (choked) flow rate of butane vapor through a 1/2" orifice is 594 lbs/hr or about 10 lbs/min.
That’s not too bad by current industry standards for medium/large batch butane extraction systems, active or passive.
Most aren’t even close to that limit but some are.
I’m very confused by your chart.
For example, it looks like you are implying that the choke limit for butane vapor through a 1.5" orifice is 160 lbs/hr or 2.6 lbs/min.
If I solve the equation for a 1.5" orifice size (.001142 m2) using your given variables for pressure and density, same as I did above, I get about 5,351 lbs/hr or 89 lbs/min max butane vapor flow rate through a 1.5" orifice.
Why does your chart imply that the limit is only 160 lbs/hr (2.6 lbs/min)?
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