On a different note, there was one new face, and his daughter, present for my service. I feel honoured to introduce them to the United Church. I hope they felt welcome, and not too scared. I know how uncomfortable it is to be surrounded by a bunch of strangers. I would like to see them…
Lectio Divina went well. I think I put the right emphasis in the reading. Honestly, I don’t remember much from that session. I have been busy with this weeks homework. We are starting to analyze different prayers, to identify what the key components are. There is a pattern that a particular prayer should follow, which…
The first group session was interesting, even though we were quiet and uncertain around each other. I think we will be more forward this week (tomorrow evening). It is not surprising that I am on a different end of the religious spectra. My input to the homework and comments on other peoples essays is different.…
I am officially overwhelmed. I just saw the required reading for each week and I am behind. And one of my books has not shown up yet. I did not anticipate this to be such a demanding course. But it is. And my day job is not any less forgiving. The introductory session was last…
What on earth am I doing? Why am I signed up for learning how to lead worship services in the United Church? How did I get here? My first LLWL assignment is to create a short video that describes myself. I will sketch out the rough draft here. I am an engineering consultant in Calgary,…
Controller tuning can a bit of a trial-and-error exercise. There is often no trust that the PID tuning settings recommended by the Engineer will be successful. This is where some modelling is useful. If the simulation results are acceptable, then the real application stands a good chance of working. If the simulation results are not…
Almost every centrifugal pump requires some form of minimum flow protection. Low flow rate can damage the pump through high temperature or flow instabilities that cause excessive vibration. The simplest form of control is a simple orifice plate that dumps a continuous flow rate back to the pump suction. This is acceptable for small pumps,…
The other strategy is adaptive tuning. Here, we assume that the DCS can provide three separate PID tuning constants. The zones, shown in figure below, are selected to span the operating conditions from 20,000 kg/h (gain of 6) to 110,000 kg/h (gain of 0.8), with a uniform ratio from one zone to the next. Now that we have…
In Part 2 we saw that our temperature control process behaved very badly at the low flow rate associated with startup. The root cause of the poor behaviour is that the process behaviour no longer works well with the PID controller. In this section we will look at how to make the process behave better.…
In Part 1, we saw that the hot oil flow rate through the heat exchanger was nearly linear with valve position. Our experience with the exchanger is that the one set of PID tuning parameters is wonderful at one operating point, but fails at another. Why? Good control requires repeatable performance from the PID algorithm…