Glass manufacturing is a science, but there has always been a bit of mystery to it, and it is often treated like an art with touch of black magic and a deep rooted theme of “this is how things have always been done.” The glass industry is one of the most conservative that I have seen. It tends to be slow to change and no one wants to be the first to try something. Glass melting is a 24/7 operation; you cannot stop the flow of glass without impacting the quality, and what you want is consistency, so you really don’t even want to be changing flow rates. This leaves little time for maintenance, whether it be preventive or dealing with some type of catastrophic failure. There is much planning involved when a line or furnace is to be shutdown. It is a window of opportunity and you must accomplish as much as possible when it occurs.
That being said, there is much interest by glass manufacturers to find materials that will last longer, or extend the tank life (leaving even fewer opportunities for downtime and maintenance). Many suppliers are working hard to improve the life of their materials. Unfortunately, there is often a tradeoff. That new material might introduce a new defect or require higher temperatures or more energy. It might cost more and it might cost more to maintain. Glass manufacturers have to weigh all of these factors and determine if they want to try something new or different, because once you put it in the tank it will be a long time before you can change it.
Another way to extend the life is by doing some type of hot repair. With new technology, today manufactures can use thermal imaging or other tools to identify problem areas in the furnace before they become catastrophic. Once identified they can try to fix it or at least monitor it and try to prolong its life. There are the traditional methods of applying cooling (water or air), but there are also new technologies in hot repair like ceramic welding. These can help to extend the life of the furnace so that you can perform a scheduled shutdown instead of experiencing a catastrophic failure that causes you to shut down your process unexpectedly (or shuts it down for you).
When you do shut down a tank, it is a major planned event and there are usually many things that need to get accomplished during that shutdown. Some tanks are only shut down once every four to five years, so planning for maintenance and upgrades is imperative. You really have to look forward – what needs to be done now, and what needs to be done four to five years from now?
The most common need for a shutdown is to replace worn refractory. As the glass is melted and flows through the tank it, it wears the sides and bottom away, as does corrosion caused from all the combustion during the melting process. New tools today to study the state of the furnace, such as thermal imaging and modeling can help identify problem areas before they reach failure.
When you shut down your tank, it is your opportunity to upgrade your batch house, your raw material storage and silos, the furnace feeder area; you might want to make improvements in material handling so you have better flow and glass quality, or automate hand weighments, increase capacity, or just make room for a new material.
Most glass plants are pretty old, so it’s a matter of replacing and bringing up-to-date the batching equipment. A lot of equipment was built in the 70s and 80s (or before), so it’s nearing the end of its useful life and needing considerable repairs and/or replacement.
Normally you hire an industry expert to do your furnace repair. That same company might be the GM that brings in other subcontractors to do the other upgrades, or you may manage it yourself. But that process is very lengthy and requires much coordination.
One of the things Optimation does is perform batch house audits. We go in and assess the batch house while it is running so that you can better plan what you need to do during your next shutdown. We look at throughput, wear and tear on equipment, safety, maintenance concerns, etc. The auditor prepares a report with the state of your equipment and recommendations from our experts on how to proceed with upgrades over the next few years. Use the learnings from your batch house audit and capitalize on that downtime to upgrade by making as many improvements as possible. You don’t know when you’ll have another chance to do them.