How To Control Your CO2 in XPS Creation Line

It is popular that CO2 may be the most challengeable blowing agent to take care of during the physical foam extrusion procedure. It really is for factors. For instance, the supercritical point, touchy dry glaciers, and its own density vary when circumstance temp changes etc apparently. For end customers, understanding this information would not enable you to get anywhere. You still need reliable design to warranty the productivity of the production line. I am not going to tell you many terminologies or theories. I just want to talk about our practical knowhow of handling CO2 in XPS production. To better understand the tips at each unit of the complete system, allow’s begin from explanation of our movement chart. The next chart is not the real PID, it is just a sketch which will help you understand just how how exactly we control the CO2. The actual PID is much more complicate than this which involves tens of valves and some additional accessories.



Normally industrial use CO2 is delivered by truck that carries tens of a great deal of liquid CO2. And the CO2 will be stored in a big vacuum insulated container that is generally 25 lots approximately. The heat of CO2 within the tank is about minus 20 degree Celsius, and the pressure is definitely between 1.6-2.0Mpa. When the pressure rise is definitely due to the surroundings temperatures change, the tank will give off CO2 to cool off itself.

As that water is known by you is a lot easier to hand than gas. So we have been gonna manage to keep CO2 in the constant state of liquid during the whole process. Because the CO2 is quite prone to vaporize because of its high vapor pressure, therefore we must hit the total amount between pressure and heat range. This is the basis of how our bodies works.

We employed a booster pump which will transportation the water CO2 from CO2 container to middle container whose wall structure was jacketed style, by which the heat range of the middle tank could be controlled by water temperatures controller. One suggestion I have to take it up here is that the distance between CO2 tank and middle container must be as near as possible. Due to the propensity is usually got by the CO2 of vaporizing so that the longer length, the more risky to vaporize. To take action, the booster pump is recommended to put under the CO2 container. Even so, the vaporizing still occurs occasionally. When the booster pump struggles to pump the CO2 correctly, vaporizing probably happened. The release valve is designed for this situation, therefore open it and let out the vaporized CO2 to be able to cool off the temperatures of the top of the booster pump. This technique must thoroughly be done extremely, because when the discharge valve is certainly opened an excessive amount of, the CO2 is likely to become dried out ice that will block the pipe, and it shall take long time to melt away. To avoid this circumstance happen, the capacity of the booster pump should be ten times bigger than metering pump so that the booster pump doesn't have screw extrusion to work on a regular basis, only works regularly. Besides, longer discharge tube is advised which can avoid the inlet pipe of booster pump from freezing by dried out ice. Furthermore, the insulated piping of the complete program shall contribute to the consistence of CO2 transport, it could save energy also.

The goal of middle tank would be to keep the CO2 at a certain temperature (around 25 level Celsius) in order to maintain the pressure of the complete system is stable and high enough (6.5-7Mpa). These two premises make sure the constant physical home of CO2 and it gets CO2 primed for precise metering into twin screw extruder. As I discussed earlier, the density of CO2 varies when temperature changes. The highest level alarm of CO2 in the middle tank ought to be no more than 70% of the total volume of the center tank in case there is any incident occurred, the charged power slice in the summer in some warm region, which may trigger circumstance heat range of middle container goes high, then the CO2 could become supercritical state whose behavior is usually more difficult to control and forecast. As a total result the quantity of CO2 is going to be expanded greatly. If the free space is not enough, it could get the middle tank in a few danger.

Before CO2 goes into middle tank, it'll be warmed up to ensure the temperature of CO2 in the centre tank at a particular degree as it is intended. Normally it is 25 level Celsius. At this temperatures the pressure of middle container is approximately 6.5Mpa. Why is it to be established at this temp? In lots of countries, 10Mpa is a watershed to split up ruthless vessel and very high pressure vessel. The second option requires challenging certificates and more costly. So 7Mpa is normally safe for high pressure vessel. After going right through the middle tank, the OO2 goes into another cooling vessel that may bring the heat of CO2 right down to 10 ten degree Celsius. The circumstance of 6 now.5Mpa and 10 level Celsius make the CO2 in pure liquid. And the more liquid, the easier to dosage. CO2 with this state could be metered into the main extruder (twin screw extruder) readily. A very important factor has to be addressed would be that the pump head has to be cooled by way of a chiller. When the pump heads are working, it shall generate some high temperature which can make water CO2 vaporized that will trouble the process.

When all above mentioned points have already been looked after, it still cannot warranty that the CO2 can be handled properly. If any section of piping traps vaporized CO2, this system would not function properly. One thing you need to do is to open up the discharge valve with great attention to avoid big dry ice occurs. The discharge valve before injection valve is preferred strongly. When you see the white smoke cigarettes (small particles of dry glaciers) happens, there you go, just close the valve. Today the CO2 can be working out.

That is our way to control CO2 system. This is actually the combination of taking into consideration China-made, economic, dependability and practical. There are some various other methods can also control CO2 very well. By way of example, LINDE PRESUS and DSD bundle can handle the CO2 as well precisely. Our system is based on the health of made-in-China just. According to our long time expertise, China-made piston pumps are no issue in any way in handling CO2. The drawback of piston pump is the fact that the risk of leakage of China-made is bigger than membrane pump as time passes. But CO2 is nonflammable and nontoxic; it doesn’t make sense to be worried about this risk. Furthermore, the sealing stuff is very accessible and cheap. Changing sealing stuff could be put being a routine in to the maintenance function. Nevertheless, the flammable blowing agent like HFC152a, ethanol, DME, Isobutene etc. is better taken care of by membrane pump.

Our foam extrusion lab is using another operational system which can handle little amount CO2 very well. But it is only for lab make use of now. This technique cools the CO2 right down to minus 20 level Celsius to help make the CO2 within the condition of real liquid with just a little pressure. Normally this system works together with a CO2 cylinder which simply contains tens of kilos of CO2. It really is fairly inexpensive and an easy task to run.

All in all, it is best to maintain the CO2 within the condition of pure liquid during the entire handling process. Regarding the so-called supercritical CO2 foam XPS production line, it is because the CO2 becomes supercritical condition when it's injected into the barrel where the temperature is just about 200 degree Celsius. The real name has nothing to do with the handling process.

Write a comment

Comments: 0