topic Re: Filling Fluid Mixer based on Content of Mixer in FlexSim Forum

Filling Fluid Mixer based on Content of Mixer

jim_draper — Wed, 01 Aug 2018 16:32:50 GMT

[ FlexSim 18.1.2 ]

I am using custom code in the step triggers of two Fluid Mixer objects to refill when the step sequence is completed and the mixer is empty. How can I code to trigger a refill when the mixer content falls below a certain level (e.g. 1000 kg) rather than after the two step cycle (step 1 fill; step 2 mix) and then completely emptying. After the refill is complete, the mixer should revert to step 2 (mixing). Each of the two mixers can hold 3000 kg and are being fed from a common tank connected to both mixers. The two mixers are communicating with each other through the central ports.

Here is my current method:

Before step trigger:

/**Custom Code*/

treenode current = ownerobject(c);
int stepnum = parval(1);

if (stepnum == 1)
{
openinput(current);
closeinput(centerobject(current,1));
}

After step trigger:

/**Custom Code*/

treenode current = ownerobject(c);
int stepnum = parval(1);


if (stepnum == 1)
{
closeinput(current);
openinput(centerobject(current,1));
}

Thanks.

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Fri, 31 Aug 2018 15:50:21 GMT

One way you can trigger a refill is to use an event triggered source in process flow where it fires when the content drops below 1000, then have other activities attached to it opening or closing ports.

Re: Filling Fluid Mixer based on Content of Mixer

jim_draper — Fri, 31 Aug 2018 17:04:33 GMT

Joshua,

Thank your for your suggestion. It sounds like a plausible solution. I have not used process flow before and suppose I will have to dig into the user manual to figure out how to recreate the example given above.

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Fri, 31 Aug 2018 17:28:22 GMT

If you upload your model I could make the adjustments. I do recommend going through through the tutorials for Process flow, it's extremely powerful and will give you greater controll over any model you make.

Re: Filling Fluid Mixer based on Content of Mixer

jim_draper — Fri, 31 Aug 2018 17:44:12 GMT

Joshua,

Here is my model. There are a lot of custom objects in the model. Do you need those files as well?

Jim Draper

fresh-burger-line-8-31-18.fsm

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Fri, 31 Aug 2018 18:38:48 GMT

It is fine without the custom objects. One thing with mixers is that they don't "overflow", so they only take in what is needed for the recipe. So I don't think there is a need for refilling, unless the refilling is for other fluid tanks, in that case can you give a brief outline of the flow of your system surrounding just the mixers?

Re: Filling Fluid Mixer based on Content of Mixer

jim_draper — Fri, 31 Aug 2018 19:09:28 GMT

I agree that mixers don't overflow in a model. This model is being used in reality in a meat plant now. The factory has two primary meat mixers that feed material to a final meat mixer downstream. The two primary mixers can hold up to 3,000 lb. The primary mixers are fed by a grinder (tank) and the amount to be put into the primary mixers must be in increments of 2,000 lb. Thus when the primary mixers fall below 1000 lb., they can be refilled and not wait until they are completely empty. The final mixer has a capacity of 2,750 lb. I have been inputting the capacity of the primary mixers to match exactly one batch size of the final mixers (1265 lb. and 1485 lb., respectively). But in reality the primary mixers are initially filled to 2000 lb. and then refilled in increments of 2,000 lb. whenever they fall below the 1,000 lb. mark (after the amount for a final mixer batch has been discharged). The two primary mixers have two 3 minute processing steps after filling is complete.

So I need to have the primary mixers fill to anywhere between 2,000 and 3,000 lb., wait for six minutes, discharge the correct amount to the final mixer and then refill another 2,000 lb. slug if the content is below 1,000 lb. after discharging. Perhaps these two primary mixers should be modeled as tanks instead of mixers. It would be easier control the filling process but I don't know how to make tanks wait for the six minutes between receiving a 2,000 lb. input and the time to start discharge. It may be easier for you help me put code on two tanks to wait the six minutes that is required. I am not coding savvy whatsoever. Thanks for your help.

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Fri, 31 Aug 2018 19:41:48 GMT

You talked about a 2000lb slug, is this added all at once rather than over an extend amount of time? Also the discharge from the mixers, is it instantaneous or over an extend time as well? Tanks are nice to show the filling and refilling and would work if you replaced the lean and fat mixers. Now the 6 minute wait, that is calculating that the final mixer has finished blending the lean and fat mixture and has already discharged its contents as well before accepting more lean and fat meat?

Re: Filling Fluid Mixer based on Content of Mixer

jim_draper — Fri, 31 Aug 2018 20:20:20 GMT

The 2000 lb. is added at a rate of 11.1 lb/sec. but to only one primary mixer at a time. All 2000 lb. must be added. The discharge of the mixers is a rate of 25 lb/sec. I am okay with replacing the mixers with tanks if there is a way for the 6 min. requirement to be met. The 6 min. begins at the time when the 2000 lb. finishes filling. The final mixer will not call for meat from the two primary mixers until it has completely emptied the 2750 lb. I may have to finish with this with you next week as I am leaving for the long holiday soon.

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Fri, 31 Aug 2018 20:25:31 GMT

Same, I will look into it more next week as well

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Tue, 04 Sep 2018 17:57:13 GMT

@jim.draper I think I understand most of this process, just a final question. Do you want the slugs added when it drops below 1000, or below the amount that it will add to the final mixer, because if it doesn't drop below 1000, say it is as 1001, then it will have to do 2 batches worth for the recipe for the final mixer since the recipe calls for 1265 lb. and 1485 lb.

Re: Filling Fluid Mixer based on Content of Mixer

jim_draper — Tue, 04 Sep 2018 18:27:17 GMT

Good catch! Yes, the slug should be added when the level drops below the amount it will add to the final mixer. There may be some instances that it will exceed the 3000 lb. capacity of the primary mixer but in reality, it can hold more than 3000 lb. if need be. The 3000 lb. is the recommended fill level and not a hard ceiling amount. The worst case scenario would be if the level drops to 1,484 lb. and then a slug is added bringing it up to 3,484 lb. I think that is doable.

Re: Filling Fluid Mixer based on Content of Mixer

joshua_s — Tue, 04 Sep 2018 19:44:38 GMT

Take a look at this model and see if this all checks out of what should be happening. the 6 minutes seems to check out with this.meat-example.fsm