RIMS set ups ?

slnies · 01-14-2008, 07:47 PM

Ladies, gentlemen and fellow brewers! This thread is to explore possible RIMS set ups and there successes or failures. I am in the phase of collecting parts for a RIMS set up, and want to hear feed back from the more experienced practitioners of this semi automated medium of brewing. Please feel free to post pictures, give advice, or brag about your prize equipment. Some of my questions are as follows:

1. Will direct heating of wort in a manifold with a low density element scorch or carmelize wort if used in combination with a PID?
2. What are your preferred methods of RIMS?
3. This is not a question. Yes I like to tinker.

Thanks in advance for your time and effort. S.

slnies · 01-14-2008, 08:28 PM

Let me also state that I have searched the web on the subject, and in general read everything I can get my greedy little paws on. And as this thread grows I will still be reading current threads elsewhere on this forum. I don't want anyone to get the wrong impression. LOL. S.

superfluent · 01-14-2008, 09:29 PM

I have a 2kw direct heated PID controlled RIMS about half way done. I'd say, sure you can tune a PID controlled (electrical) direct heat system to scorch a high gravity wort, but properly tuned, it shouldn't.

I picked a farly simple PID controller that has a thermocouple/resistive/alien technology temperature probe input and a SSR (solid state relay) output. It has a programmable duty cycle length that is in a range where I am pretty sure I will be able to obtain a fairly long duty cycle but that is still short enough to provide a reasonably smooth heat from the element during the duty cycle (mine is selectable between 2-250 seconds). The SSR is designed for the load and control application (it's basically a zero crossing switching SSR for resistive AC loads).

The main danger for scorching will be when doing temperature step-ups because a simple PID controller will basically just push as much energy as possible into the worth to raise the temperature to the new target. Just to be sure I won't run into that situation I choose a controller that can do temperature ramps, ie I have some control over how fast the temperature transitions will be.

I'll let you know how it turns out.

H

slnies · 01-14-2008, 10:27 PM

That sounds cool. I have acquired a Watlow SD type PID. I am certain I can ramp temp.s, but I don't think I can do soak times with it. So ramping is a key. Very cool. S

**kladue** · 01-14-2008, 10:36 PM

Here are some formulas that will help in the RIMS design:
Btu's needed for a step= Gallons x 8.35 x temperature rise (rough calc as ignored mash heating)
Btu's per minute per KW = (KW x 3413)/60
Temperature rise across heat source = Btu's minute/(Gpm x 8.35)
Step time = Btu's needed/Btu's minute

Some of the observed limits in past RIMS design have been approximately 1 Gpm flow limit through mash to limit compaction, surface temperatures of > 1kw elements with low velocity flow across element. The faster you can move the liquid past the element the lower the surface temperature will be, the less likely to have scorching. A better design would have 5+ gpm over element and 1 gpm diverted to mash circulation.

**CodeRage** · 01-14-2008, 11:19 PM

Quote:

Originally Posted by Henrik

The main danger for scorching will be when doing temperature step-ups because a simple PID controller will basically just push as much energy as possible into the worth to raise the temperature to the new target. Just to be sure I won't run into that situation I choose a controller that can do temperature ramps, ie I have some control over how fast the temperature transitions will be.

Nah, you can 'detune' a pid for slow reactions. Moderate porportion, low integral, low derivative. Ought to make for a nice slow curve with little overshoot.

slnies · 01-14-2008, 11:43 PM

Quote:

Originally Posted by kladue

Here are some formulas that will help in the RIMS design:
Btu's needed for a step= Gallons x 8.35 x temperature rise (rough calc as ignored mash heating)
Btu's per minute per KW = (KW x 3413)/60
Temperature rise across heat source = Btu's minute/(Gpm x 8.35)
Step time = Btu's needed/Btu's minute

Some of the observed limits in past RIMS design have been approximately 1 Gpm flow limit through mash to limit compaction, surface temperatures of > 1kw elements with low velocity flow across element. The faster you can move the liquid past the element the lower the surface temperature will be, the less likely to have scorching. A better design would have 5+ gpm over element and 1 gpm diverted to mash circulation.

Would this still be true if you were under powering the element, so that your total wattage would be some fraction of its total, if it were fully powered? I am just thinking that the intensity of heat would also be a fraction. I realize that then my heating efficiency would go down in temp. rise/time, but would that work, or would the surface temperature of the element be the same no matter what? Thanks for the Calc.'s those will be helpful. S,

**CodeRage** · 01-14-2008, 11:58 PM

Quote:

Originally Posted by slnies

Would this still be true if you were under powering the element, so that your total wattage would be some fraction of its total, if it were fully powered?

Yes, Wattage is just the amount of energy being used by the element. just about 100% of that energy is being directly converted to heat.

slnies · 01-15-2008, 12:58 AM

I think I may have answered my own question. According to Kladue's calc.s BTU's are a function of wattage. So a 3500w element at 220v would produce 199.03 BTU's per minute, and the same element powered at 120v would have a wattage of 1056w, so now the BTU's per minute would be 60.1. If I am using this calculation correctly, that would mean that the surface heat is not as intense at a lower wattage. So maybe the element has the ability to get to the same surface temperature, but it will not be able as fast. This would also mean that your flow rate would not have to be as much either. Does this sound correct? S.

**kladue** · 01-15-2008, 03:30 AM

The trick we worked out over a decade ago was to put a tee in the pump suction and after the heating chamber with a ball valve to control flow. In operation you adjusted bypass valve closed until the flow to the sparge ring in the mashtun was adequate. This greatly increased the flow through the chamber and reduced the surface temperature on the element, but required user adjustment at startup. The traditional method of all flow through the chamber with no bypass is what everyone seems to use as it is tamper proof. The biggest problem with the RIMS system is need to keep wattage/element surface temp down which makes it difficult to make protien-conversion steps in a reasonable time, hence burners under the mashtun for direct fire.