PDA

View Full Version : New here. Need help upgrading ice block plant!







aakbar
27-11-2016, 11:01 PM
Hi everyone,

I've been browsing these forums for a few months now. I decided to post because I was hoping someone could help me answer a few questions. Fair warning. This is a long post!

Background:
My family has been in the Ice Block manufacturing business in Islamabad, Pakistan since 1979. I inherited the plant in December last year and after some initial back and forth -quite literally as I live in the US - I decided to give it the best I got and let the chips fall where they may. Fast forward to today. We recently finished our first season and my big take-away from it was that we need to upgrade our plants. Our current set up includes two 8x8 and three 6x6 open type, 2 cylinder, belt driven reciprocating compressors, using ammonia. (What that 8x8 or 6x6 refers to? I have no clue!) They produce 135kg blocks in 48 hours. Our ice cans are made out of mild steel and due to continuous corrosion, no two cans produce the same size blocks so there is no way for me to tell the cooling capacity in tons that each tank needs. (I multiply the number of blocks into size of each block and divide it by a 1000 to reach a rough estimate) We use water cooled-condensers that sit on the roof top accumulate an incredible amount of silt , which I don't believe is doing any good to the efficiency of our system. We use three 10hp motors to cycle the water from pool to the condensers. Our electric bill is our biggest variable overhead, by a long shot and I feel that if we upgraded our machinery, we could reduce our cost of production(cop) significantly. Any cost savings we have, we plan to invest in solar panels, further reducing our(cop). But here's the problem:

I know next to nothing about industrial refrigeration! My background is in business and this is the first time I've ever even come heard terms like solenoid and expansion valves in my life! I've been watching videos about industrial refrigeration online and have picked up the “Industrial Refrigeration Handbook” by Wilbert Stoecker but all of the technical jargon is so esoteric it's making me crossed-eyed. At this point I feel like I know just enough to be dangerous. (You'll see)

So anyway, over the past several months, I spoke with a few vendors on alibaba and received quite a few quotes to upgrade our machinery. Every time I learned something new, I asked them to revise the quote based on the new info. Beyond the total amounts on their quotations, I am having trouble telling which system is superior to the other. I mean, who makes the best expansion valve anyway? And do we really need 90kw refrigeration power or 115?
The other issue is that these vendors tell me that they can reduce the freezing time for our blocks to 24 hours, while reducing energy consumption. Initially I believed them but the more I read, the more I am unconvinced of those claims. I just want to make sure that their claims are valid. Can they freeze those big blocks in 24 hours all the while reducing electricity consumption? Sounds too good to be true. The reason I bring this up is that I initially considered switching to Halocarbons but it recently came to my attention that Ammonia is actually a more efficient refrigerant. Secondly the vendors told me that the screw compressors are more efficient across the board but I just read in the industrial refrigeration handbook that open type reciprocating compressors are actually more efficient in small sizes. (I am starting with the smallest tank, in case things don't work out) So in a nutshell, we have the most efficient refrigerant in ammonia, we are using the most efficient compressor type, albeit very old. Should I upgrade at all? If we upgraded to the latest open type reciprocating compressor or screw compressors using r-404 or sthg like that, what kind of cost reductions should we expect in percentage terms? Would the ice freezing time time go down? It seems the more I learn, the more difficult the decision gets. Six months ago, I was all set on buying those new screw compressors. Now I don't know. And I need help. Anyone?

I am attaching a couple of pictures for reference showing our plant.

Thank you for reading this far! I really appreciate it.

NH3LVR
28-11-2016, 12:10 AM
I commend you for the work you have done so far. You have put a lot of effort into educating yourself.
Let us have some more information as to the current operating pressures and the changes that the new equipment would make to them.
Ice block plants are not something I know much about. They are rapidly growing extinct here in the US.
What do your customers do with the ice? Would converting to flake ice be a possibility?
In your case you might have the most efficient compressors for the job. Ammonia is most likely something you would want to stick with as well. Converting to a different refrigerant would be a huge task.
One issue you might face is the quality of advice being offered. I have no help to offer in that regard for a project in Pakistan. Other members might be able to help.
I would be skeptical about cutting the freezing time in half.

aakbar
28-11-2016, 12:32 AM
Hi NH3LVR, Thanks for the quick response. Flake ice is not an option because what happens with the ice once it leaves our plant is that it ends up at small kiosks set up by "ice dealers" across the city. Now these kiosks are temporary in nature and so there are no freezers to keep the ice. The dealers in turn sell pieces of these blocks by the KG to their end customers. My mother-in-law's mother tells me this is how things were in the US back in the day. Anyway, flake ice won't last in 45C environment. That's why the ice block weigh a lot as well. Even after they melt, the dealer/wholesalers can sell enough of it to make a profit.