Frequent Startup/Shutdown Effects on Fertilizer Plant Equipments

Dunno about books etc. But it's common sense.
Have you ever known a TV to fail? If so, I'll bet it was at switch on.
There are often very high surge currents in any electricl/electronic equipment at switch on.
Then add in mechanical inertia to any mechanical/hydraulic system.
Then factor in that some materials my tend to clog and solidify if not agitated.
Del

This is a good question, with good thinking behind it. I suspect that data may be hard to come by on frequency of startups/shutdowns and the effects on temperature/pressure cycling.

In accordance to the above True answers, same goes to the energy consumption. By logic, you will need to have large amount energy to move anything from the start than when it's already moving.

Frequent start-ups effect losses to the system.

Hi everyone!

I Googled this and got some hits. There may be some reading there for you.

Books! Nothing better than the real world hands on experience, and come this Monday after a 3 day holiday weekend (Happy Easter by the way)will be another one of those early building startup from hell.

This is not a fertilizer company, but this is what I will experience come Monday morning four hours before production starts.

At least one out of 150 plus freq drives will fail (end of live). Another 3 or 4 will have multiple overvoltage faults until stiff lube on conveyor chains loosen.

Will be hunting all those selector switch, push/pull button in the wrong position, or hunting down the house air, high pressure air, gas, water, coolant shutoff valve are always fun. Or banging on stuck fluid flow sensors those are also fun to find.

I've been doing early startup for the last four years and it never seem to amaze me how somebody can do something to a piece of a equipment that can stump you to the point to move on and come back later to solve the problem once everything else is up and running.

I see the pros and cons of shut down equipment. I hate walking by a line that's been running for hours, not being used to make product, I shut it off. With plenty of complains by maintainers.

I look at it this way. It's like me going home and seeing a window open and the furnace running. I just shut the furnace off. When the boss complains about how cold it is, I point to the window, walk away. Then sometime later just before the pipes freeze I'll turn it back on.

In my experience, it takes 150% of the normal maintenance staff to start up a production facility

what I mean by normal maintenance staff is what it would take during an extended run of several days

Make a graph of mechanical breakdowns vs time. It will become clear when most of the problems occur

What kind of breakdowns & the quantity will be greatly influenced by the preventative maintenance program [or lack]

It is difficult to guide you to some reference (books, web, etc) on this issue because a common yardstick can not be applied for all equipments or even similar equipments of different sizes and sevices. Heat exchangers, piping, valves, compressors, pumps, turbine, etc are used in most of the process industries, not only for fertiliser plants. With commonsense & experience I can say the following on negative effects of Frequent start-up/shutdowns:

1. Practically nothing may happen for static equipments like heat exchangers, piping, valves etc. Only possibility is accumulation of scale or silt while no flow condition. Piping for steam service may experience unusual vibration while starting due to condensate formation.

2. For rotating equipments like compressors, pumps, turbine, etc frequent Start-up/Shutdown badly affect the parts like seals and bearings resulting lesser life than expected. It also affect the rotor shafts by causing torsional creep, which may result in shearing-off the shaft.

Thank you all.

I am in a situation where I cant just argue on the basis of experience. However, I found some data in UREA SYMPOSIUMS and IFA CONFERENCES REPORTS. These are also based on experience but I think I can refer them. So it will be good.

Regards,

Tabby