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Hello all,
We are a batch processing industry with varying products depending on season. We have to provide all utilities(steam, Cooling Tower Water, Chilled water & Chilled Brine) to the Jacket as per process requirement. We face the problem of intermixing of these utilities either by mistake or by valve passing. I presume this will be a common problem in all industries. Is there is any good way or better system to ensure that if one utility is online then the other utility valve cannot be opened etc. ? How this is being tackled in Industry ?
Thanks in advance.
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Brine Mixing In Other Utilities
Started by Guest_Selvan_*, Jan 07 2004 09:24 AM
4 replies to this topic
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#2
Diederik Zwart
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Posted 08 January 2004 - 08:06 AM
Selvan,
If you want to ensure that there is no valve leakage I'd suggest using double block and bleed (two block valves in series, with a drain inbetween). If you leave the drain open and both block valves shut, then any leakage past the valves will exit via the drain valve.
To make sure the operator cannot accidently open a utility connection when another is already lined up, you can either use a DCS interlock system (for automatic block valves), or you can use a key system (for manually operated valves). The latter means that you need one key to open any valve and that key is stuck in its lock as long as the valve is open. To change from one utility to another you close the valve, take out the key and put it in the lock for the other valve, after which you can open that one. Just see to it that there is only one key available and that no one makes copies of it.
Regards,
Diederik Zwart
If you want to ensure that there is no valve leakage I'd suggest using double block and bleed (two block valves in series, with a drain inbetween). If you leave the drain open and both block valves shut, then any leakage past the valves will exit via the drain valve.
To make sure the operator cannot accidently open a utility connection when another is already lined up, you can either use a DCS interlock system (for automatic block valves), or you can use a key system (for manually operated valves). The latter means that you need one key to open any valve and that key is stuck in its lock as long as the valve is open. To change from one utility to another you close the valve, take out the key and put it in the lock for the other valve, after which you can open that one. Just see to it that there is only one key available and that no one makes copies of it.
Regards,
Diederik Zwart
#3
Guest_Ben Thayer_*
Guest_Ben Thayer_*
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- guestGuests
Posted 08 January 2004 - 08:56 AM
One of the headaches with this type of system is where the brine goes even if not valved wrong. A typical set-up may use MeOH/H2O for the brine cold service, H2O for cooling and steam for heating. There is always some small amount of MeOH still in the system when you switch jacket service.
Some plants have converted users to heat transfer fluids such as Dow Syltherm XLT and then use this for heating and cooling with supplemental exchangers. That way, there is no change of fluid in the jacket and there are minimal environmental issues.
I agree with the concept of double block/bleeds and also make sure you have decent check valves properly oriented. If your system is strictly a manual system, the keyed approach can work but a good written procedure should suffice if this is done relatively frequently.
We upgraded several systems to Syltherm so that we could be independent of the procedures issue, even the best procedures resulted in ppm levels of MeOH going into the cooling water system where blowdown caused us environmental issues.
You may consider an intermittent flush to get rid of the MeOH residue to a waste treatment system/facility prior to the use of the steam or cooling water.
Some plants have converted users to heat transfer fluids such as Dow Syltherm XLT and then use this for heating and cooling with supplemental exchangers. That way, there is no change of fluid in the jacket and there are minimal environmental issues.
I agree with the concept of double block/bleeds and also make sure you have decent check valves properly oriented. If your system is strictly a manual system, the keyed approach can work but a good written procedure should suffice if this is done relatively frequently.
We upgraded several systems to Syltherm so that we could be independent of the procedures issue, even the best procedures resulted in ppm levels of MeOH going into the cooling water system where blowdown caused us environmental issues.
You may consider an intermittent flush to get rid of the MeOH residue to a waste treatment system/facility prior to the use of the steam or cooling water.
#4
Guest_Selvan_*
Guest_Selvan_*
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- guestGuests
Posted 09 January 2004 - 09:14 AM
Mr. Diederik Zwart ,
Thanks for Ur response. We had already thought of the former but due to space constraints and involvement of Huge capital investment we are thinking of some other alternatives. Moreover, we observed that many times the mixing is due to maloperation rather than that of passing. Your second suggestion is good let us try the feasibility of the same.
Still this is not going to solve the problem of mal operation because using the key I can open in the supply the Chilled water and in the return the Chilled Brine valve. What we were thinking is that we have some mechanism were in if a supply of Chilled Water is opened then automatically the return of the Chilled Water only will open and at the same time no other utility valves should be open. The former can be done by connecting both the handles by a single piece but how to ensure that there is no other utility valve open is the consideration ?
Mr. Ben Thayer,
Thanks for the response sir. I forgot to mention my Brine system it is with Calcium Chloride. I think though we may be having the system of other fluids it has to be heated or cooled using the utility systems only is it correct ? Then how do u avoid the problem over there (say heat exchanger) ? Moreover is this system going to be economical for a large scale production unit sir as changeover is very frequent in our case and we have to heat or cool the entire system from T1 to T2 ? SOrry if I am wrong sir from What I understood I have raised the questions.
- Selvan.
Thanks for Ur response. We had already thought of the former but due to space constraints and involvement of Huge capital investment we are thinking of some other alternatives. Moreover, we observed that many times the mixing is due to maloperation rather than that of passing. Your second suggestion is good let us try the feasibility of the same.
Still this is not going to solve the problem of mal operation because using the key I can open in the supply the Chilled water and in the return the Chilled Brine valve. What we were thinking is that we have some mechanism were in if a supply of Chilled Water is opened then automatically the return of the Chilled Water only will open and at the same time no other utility valves should be open. The former can be done by connecting both the handles by a single piece but how to ensure that there is no other utility valve open is the consideration ?
Mr. Ben Thayer,
Thanks for the response sir. I forgot to mention my Brine system it is with Calcium Chloride. I think though we may be having the system of other fluids it has to be heated or cooled using the utility systems only is it correct ? Then how do u avoid the problem over there (say heat exchanger) ? Moreover is this system going to be economical for a large scale production unit sir as changeover is very frequent in our case and we have to heat or cool the entire system from T1 to T2 ? SOrry if I am wrong sir from What I understood I have raised the questions.
- Selvan.
#5
Guest_Ben Thayer_*
Guest_Ben Thayer_*
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- guestGuests
Posted 09 January 2004 - 03:43 PM
Go to http://www.plantserv...ID/CBOH-5U4SM2/ and review their article.
I am assuming that you are using a variation of something like "The Easy Way" (Fig. 1) but with the brine included as another cooling method but possible with a circulation pump to be used for the brine and cooling water.
Our system is more like Figure 4. Figure 4 is really quite complex because it shows the entire system. You do not necessarily need the entire system as shown.
If you have a single expansion tank for the jacket fluid and a jacket circulation pump, you then would have a steam heater to heat the fluid that is circulating. You would have another exchanger to cool the fluid using your brine. This way, you do not have the brine or steam in direct contact with the jacket fluid.
Advantages: No environmental issues to speak of with regards to the brine entering the cooling water.
Disadvantages: Higher equipment costs and the since the brine has to chill the loop which in turn cools your equipment, you cannot get the degree of cooling that you would otherwise.
I am assuming that you are using a variation of something like "The Easy Way" (Fig. 1) but with the brine included as another cooling method but possible with a circulation pump to be used for the brine and cooling water.
Our system is more like Figure 4. Figure 4 is really quite complex because it shows the entire system. You do not necessarily need the entire system as shown.
If you have a single expansion tank for the jacket fluid and a jacket circulation pump, you then would have a steam heater to heat the fluid that is circulating. You would have another exchanger to cool the fluid using your brine. This way, you do not have the brine or steam in direct contact with the jacket fluid.
Advantages: No environmental issues to speak of with regards to the brine entering the cooling water.
Disadvantages: Higher equipment costs and the since the brine has to chill the loop which in turn cools your equipment, you cannot get the degree of cooling that you would otherwise.
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