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Types of mill visits
Across the range of mill visits they range from a system review which is typically a light touch that can be started remotely by reviewing DCS screens for abnormal conditions. On the other end there is subsystem optimization which starts at 3 to 5 days depending on objectives and can really stretch out from there. An audit is in the middle, focusing on the stock prep equipment installed and what could be done better / differently, depending on mill objectives.
What is an audit?
Audits start with a pre-visit meeting for discussion on audit goals and information that may be available (DCS Screens, P&IDs, Flowsheet, Equipment list, Balance, test data, etc).
The audit is generally conducted by two applications engineers or product managers. These engineers have a wide range of experience in a lot of mills can aid in project justifications.
At the mill site there is a kick-off meeting and the audit starts. Equipment installation is reviewed to check for issues that could affect operation. The control scheme is reviewed.
Why an audit
Mills can run for years with often little physical change to their fiber recycling process. However, there are many other changes that happen:
- operators retire (knowledge lost)
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slow wear of components
- Instrumentation failure
- operational changes are made to address symptoms (not the root cause)
- furnish changes
- mill objectives like tonnage and quality change.
Operator retirement may be a bigger issue than many recognize. Decades ago, there was less distraction, in the control room and out on the floor. Having covered for operators in one mill I knew all the automatic valve positions, agitator motor loads and other values. This is being lost – yes it can be trended easier, but it’s easier to troubleshoot when the operator can tell you everything that has changed leading up to an event.
In many mills, typically with larger organizations, there is a considerable amount of scheduled meeting times. One process engineer we know had 60% of his time scheduled for meetings & training. While there are more and better tools for troubleshooting – there is less time to do it in. Having an external viewpoint can help.
We like to hear directly from the operators where the problems are, but we work on troubleshooting to get to the root cause.
Audit results have included:
- Mill bottlenecked at beginning & end of process, the audit determines simple way to debottleneck thickener with minor process change.
- Older mill with a lot of equipment capacity, but poorly instrumented (& controlled) gets a path forward to mill expansion with limited additional equipment required.
- Mill addressing specific issue of Styrofoam with new equipment
- Mill had pulping & detrashing issues, audit determined that equipment was incorrectly installed, recommendations made for correction at very low cost
Getting the most from a process audit
Having an independent look at your system from someone with knowledge of stock preparation equipment capacities and capabilities can be eye-opening. In addition, sampling of the process can often confirm system weaknesses.
The more the mill can provide in terms of data; lab testing, balances, flowsheets and operational difficulties the faster we can focus in on problem areas.
Audit objectives always include looking for low-cost wins that aren’t always realized by mill employees. Objectives from there can include recommendations on:
- Operational issues
- Control improvements
- Debottlenecking
- Tonnage upgrades
- Quality improvements
- Yield improvements
- Where to add equipment coming from “sister” mills
On going benefits from a process audit
When we get calls from customers with operational issues, it can be possible to start remote troubleshooting when they’ve had an audit in recent years. If they haven’t had an audit recently troubleshooting remotely is difficult at best.
Pitfalls from a bad process audit
Missed opportunity(s) or projects without expected payback are two pitfalls of a bad process audit. Opportunities that mills don’t capitalize on can threaten long term viability as projects do without payback.
Conclusions
Process Audits are an excellent tool for helping uncover opportunities or providing solutions for challenges in the mill.
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