We gave you a chance last week to write this week's column when we offered a survey for your comments.  Here is what you said:

Question:

In your mind, does more weight (or mass, if you prefer) lead to more reliability when it comes to pulp and paper mill design and operation? 

Answers:

55% said "Yes"

45% said "No"

Comments:

>Mass is equated with stability. Americans traditionally feel safer in a big car that cannot actively avoid a collision (Sherman tank syndrome) but this has nothing to do with reliability, and we all know that more massive (obese) people have poorer health (reliability).

>This also applies to chest volumes and dwell time to eliminate and dampen pulsations and consistency variation.

>Bigger and heavier in buildings has historically lasted without attention for decades and centuries. Lighter and slender might be as strong but my first thought, right or wrong, means more care and maintenance. My own experience when learning to drive on the farm matches that.

>Theoretically, no. In reality, yes! As a project engineer in a P&P mill, the 'customer' (Ops) thinks 'bigger is better'. And it is in some cases when you are considering concrete foundations for rotating equipment and you need mass dampers for vibration. But the culture applies this belief across the board which results in overdesign everywhere! In my experience, arguing with Operations about efficient design erodes any value the efficient design brings to the table.

>1. Safety should always dictate any design/operation change. 2. Fiduciary effects come second.

>It depends - in some cases yes, and in some cases no.

>The strength and compatibility of materials to the process should be more important than sheer mass. Or else, we would be using concrete bleach towers with thin corrosion barriers. However, cost trumps almost everything else, including planning for long service life.

>Quality of design, construction and maintenance are the key. Brains beat brawn any time.

>Your questions are far too broad. It's like asking how high is up? In most of your ideas, you seem to avoid basic science. For instance, aluminum dryer cans. The heat transfer coefficient may be better than steel BUT, wall thickness will be much more since you are building a pressure vessel to code 8, so you may not reduce the weight. Also the pH better be neutral since aluminum corrodes quickly in both acid and basic mediums. Another idea, cantilevered dryer cans, so one eliminates one journal but the remaining one will be at least double in size of the two originals and the base support must be considerably larger to anchor the unit. Also I highly doubt one can make the design stiff enough to prevent wobble on the far end, causing some major tensioning problems with the sheet. You guys need to engage the brain a little more before you come out with such outrageous concepts. I found the vertical paper machine quite amusing. Yes, I think it can be done, just would not want to operate in downtown NY City with neighbors constantly complaining about noise and vibrations. A concrete slab with reasonable steel supports will be far cheaper than a smaller footprint with a huge steel or even concrete tower and the associated support structure to be able to remove dryers and rolls easily. Anything can be designed but I'm sure that you have noticed in your career, paper companies do not have unlimited funds. All your ideas or at least most would be prohibitively expensive. I have always liked "blue sky" thinking, but it has to be based somewhat on reality.