TSB
screen printing => Equipment => Topic started by: beanie357 on April 07, 2012, 06:55:15 PM
-
Wondered if anyone has figured a way to salvage the heat up the stack without pulling the burnt hydrocarbons into the working environment. Same query goes for electrics.
-
A heat exchanger is the only safe way to do it... that gets pricey.
It's not just the CO and CO2 that are concerns.... there's a lot of water vapor too.
-
Wondered if anyone has figured a way to salvage the heat up the stack without pulling the burnt hydrocarbons into the working environment. Same query goes for electrics.
Check the following link
http://www.cpnuk.com/Clean%20Burn%20Brochure%20-%20NEW%20June%202010.pdf (http://www.cpnuk.com/Clean%20Burn%20Brochure%20-%20NEW%20June%202010.pdf)
Page 2 at the bottom.
They cost around $5000 but save you a lot of cash during the winter on heating the workplace.
-
Never thought about this but it's a GREAT topic.
one thing you could do is look at something like what you can do in an upstairs shower. Wrap some copper tubing around the stack (drain pipe) and it will heat the water in the pipe.
You could set up a storage tank and use thermal siphoning to collect even more heat and store it if you are operating that dryer all day... I would guess you could go even further in this situation and make a custom exhaust with some plumbing INSIDE the vent so you could collect even more. It would need to be over sized to keep the same air flow as well as you would need to monitor it for it clogging up with lint (you should be doing this anyway).
-
My M&R tech was telling me about a shop that had a radiator system connected to his dryer and it heated all the water for the shop. We had a cap on our exhaust that we would take off on the freezing mornings and let the heat blow into the shop for short periods of time. It worked and nobody died.
-
thats how it is in most shops..i guess over the years it can take a toll though.
-
Sounds like a CO monitor/alarm would be in order.
They are now required in California homes, but probably not businesses.
Years ago, kerosene heaters were all the rage for relatively cheap heat, but, of course, many did not heed the warning to vent.
-
I bet if you got together with a havoc company they could rig a system up with some basic equipment maybe even spare stuff that could work well, surely those guys would know the most efficient and safest way to do it.
-
You may mean HVAC (unless you then intend to unleash the dogs of war) lol!
But, yes, those would be the guys.
-
Gotta love apples auto correct lol.
-
Our shop is over 6k sqft. We don't use the "wasted" heat, there is plenty of heat without using the "wasted" lol. It's HOT even in the winter out there.
-
A timely discussion for me- I have a meeting tomorrow am with an HVAC guy in our new space and was planning on getting a bid for a heat exchanger installed. The concept is so fundamentally simple that I don't see these costing an arm and a leg. Seems to me that you could use a variety of reclaimed materials to build one of these and I have access to a lot of that. I'll post here regarding the final verdict. My figuring is that the exchanger just has to 'help out' the rest of your heat system and not be anything overly fancy. Although, like GD says I'm expecting our old beast to radiate out plenty of warmth without this feature.
I extra like the idea of using it to warm up the water so long as the line was all PEX and had a good filter on the end to keep it clean. I find that cold water is sufficient but luke warm water really speeds up a lot of the screen making and cleaning process. This also sounds like a pretty easy thing to add on.
Those Clean Burn dryers look excellent. I especially like the hinge top and the cool down section. It's about time someone started thinking about it more.
-
I think the expensive part with heat exchangers is just the huge amount of surface area needed to make them efficient. Seems like it would be a great project for DIY, if you have the materials, and an expert to double check it.
-
"Most drying processes use heat and air to remove moisture from a process. The moisture is absorbed by the hot air. The hot and moist (and extremely energy-rich!) exhaust air is removed through exhaust gas ducts and chimneys and out into the atmosphere. Very efficient drying indeed! Or is it? Many companies are blowing tens of thousands of kWh of energy per year straight into the air.
For example recovery of 100 kW of heat from exhaust air operating for 6000 hours per year will with an energy price of say, $0.02 per kWh, be equivalent to a loss of $12,000 per year."
Personally, I've had talks with some guys from this field and according to them using hot air from the dryer to keep screen drying cabinet warm at around 40C (around 100 F) won't be any problem trough the simple heat exchanger. Fan heater in my drying cabinet is working almost 5-6 hours a day (drying after reclaiming, drying after coating) and this should be a solid saving for the start.
-
"Most drying processes use heat and air to remove moisture from a process. The moisture is absorbed by the hot air. The hot and moist (and extremely energy-rich!) exhaust air is removed through exhaust gas ducts and chimneys and out into the atmosphere. Very efficient drying indeed! Or is it? Many companies are blowing tens of thousands of kWh of energy per year straight into the air.
For example recovery of 100 kW of heat from exhaust air operating for 6000 hours per year will with an energy price of say, $0.02 per kWh, be equivalent to a loss of $12,000 per year."
Personally, I've had talks with some guys from this field and according to them using hot air from the dryer to keep screen drying cabinet warm at around 40C (around 100 F) won't be any problem trough the simple heat exchanger. Fan heater in my drying cabinet is working almost 5-6 hours a day (drying after reclaiming, drying after coating) and this should be a solid saving for the start.
Great point. Ours is the same most days and those little heaters suck up juice. I am switching to a dehumidifier though.
-
I think the expensive part with heat exchangers is just the huge amount of surface area needed to make them efficient. Seems like it would be a great project for DIY, if you have the materials, and an expert to double check it.
If they are counter flow (parallel) type, yes. To be efficient they need larger area for the fluids to pass trough. But with cross flow type of heat exchangers (cube like core, 90 degrees angle of the plates to each other), it can be done with smaller surface. Up to 60% of the temperature difference between two air streams (fresh air and dryer fumes) can be transferred to the fresh air.
-
As I have mentioned already in my earlier post there are heat exchangers available for gas dryers. This one is made in the UK by CPN for their Clean Burn dryer. Of course that dryer spits out already a lot less CO2 the any other dryer on the market and needs a lot less gas due to the superior airflow system they have developed. So their heat exchanger might work only for their type of gas dryer but it shows you that if there is a will and demand, and there is in Europe for sure, this can be easily achieved and build by any equipment manufacturer.
See page 2 of the pdf for the heat exchanger.
http://www.cpnuk.com/Clean%20Burn%20Brochure%20-%20NEW%20June%202010.pdf (http://www.cpnuk.com/Clean%20Burn%20Brochure%20-%20NEW%20June%202010.pdf)
-
We use heat exchanger on both of our gas dryers. First I installed cube like model which worked air/air. I wasn't too happy because air from dryer is very hot (130-160 deg C) and you can have it two ways:
a) lousy percentage of energy won by not heating fresh air enough
b) make it efficient will either cost you a lot and/or give you lots of air with about 90-100 deg C, which is difficult to use.
Later I installed heat exchanger that works air/water by heating water that's in central heating system. In winter this exchanger heats up 80m2 of office space. According to engineer installing it we win back something like 14-15kW of heating power from our 150cm x 300cm gas dryer. It was made rather primitive with total cost of around 1000 EUR. With this system I'm happy
Boris
-
Hook us up with some pictures!
-
CleanBurn = "Green Marketing Bull$hitt" Carbon Tax Credits!
A 25+ year old design used in the screen print graphic arts side!
Built years ago by Natgraph, Trumax, and a few others
Cleanest Burner? Show me the data
Minimal gas consumption! Low Air Flow. A kitchen oven hardly any gas! Bingo, no airflow.
It is all about the amount of goods, coming out cured, in a specific amount of space, with a
specific amount of energy.
Clean Burn does NOT pass the muster! A Great Marketing Illusion.Period
winston
904.3430848
-
I thought the same thing when I saw their numbers.
-
Winston, you must have some ideas for recycling this energy though... I'd love to hear them.
-
Hook us up with some pictures!
Here you go:
(http://db.tt/VdhD17PP)
Catcher View
(http://db.tt/l6yULEaX)
Boilerman View
Simple concept, we have manual choice of bypass for summer, or going through exchanger unit. We added pump plus two temp/pressure controlls and safety valve. Inside of Exchanger is the same as in any water heating oven. Hot fumes (in our case air only) passes in long curvy way through container filled with water.
Boris
-
Gilligan!
Heat recycling makes total sense! I saw this in more northern states 30 years ago.
It was being done on the screenprint graphic side more often where
average gas burners were one to two million btu's. In the USA 1/2 of the dryers
I see are under vented or vented incorectly! A lot of printers opt for the cheapest
vent which doesn't pass NFPA codes, but do it any way. In Europe were the climate is
colder, shops have been using heat exchanger technology for years. They have different
tax credits for things like this! The amount of shops there is nothing , like the amount here!
There are printers who put some units out, but most are printing 300-400 per hour which
lets them use smaller dryers than here. A 48" wide belt is real wide there. Dryers built here
in the USA are better for Manufacturing than dryers built in Europe! We lose energy here
when we fail to maintain and keep our equipment in top notch condition no matter what the brand!
Saving/ reusing energy makes Total Sense but, needs do be done in a balanced sense with
Amount of energy saved and return on investment!
-
The pictures that Borris B. put up are great!
These help show where to start!
Quality/Type of vent are also correct! They are not the average single wall vent
that is sold at Home Depot! It shows adjustable flaps for adjusting air returns,recirculation.