Why we Need Pre Heat Exchanger

[oilhunter]

Im just wondering since our pre heat exchanger is in bypass due to fouling. Why we need it? out emulsion temp is about 25 deg C and heater treater is operating at 50 deg C to 55 deg C.. Can someone why they designed to have pre heat exchanger there?

[kampret06]

i don't quite sure about the bypass you talking about. which bypass is it? i mean by pass from ..(where).. to .. (where)..
i assume this pre heater and heater treater are arranged as series in a single line.
pre heat exchanger are used to heat the emulsion a bit before it will be heated again using the heater treater. the use of pre heater was depend on your heater treater capacity. if the heater treater are unable to rise as much as the delta temperature needed then it will be needed to add a pre heater on upstream of heater treater to help. but there is maybe also another cause of why you should put a pre heater depend on the conditions of emulsion and the process you have (check on your PFD)

[oilhunter]

kampret06

The bypass Im saying is the Pre Heat Exchanger is not online.. It means its on bypass mode and just idle.. and there is only one PHE in our inlet line. Im sure that heater treater can able to rise the required temp becaused it is a direct fire heater so we can heat up the emulsion as per the required temp. I just wanted some more reason why it has been designed to have a PHE..

[kampret06]

ok, i see.. i guess now i get which by pass did you mean.
so the PHE is offline. then it mean that your PHE is used as a spare for your heater treater. your PHE will only usable during the shutdown/maintenance of your heater treater.
by the way, how about the temperature of the emulsion before entering the heater treater? is it freezing your emulsion so you have an ice particle (solid) within the emulsion.? if it was the case. if you think you are okay with those conditions then you can remove your PHE, i mean if there was a shutdown to your heater treater and you have to route your emulsion through bypass without PHE.of course all of your equipments on downstream will have to handle those ice particle (solid). i think you should make sure of it. cause i think those solid particle will give more damage to your equipments downstream.

cheers

adi cahyanto

[oilhunter]

No we dont get ice particles on our emulsion.. out normal temp. is 25 to 30 deg C during summer and worst winter can be 10 deg C.. the only problem is wax formation . Im considering installing of strainer upstream of the PHE but I have concern how frequent we need to clean those strainers...

Main caused for PHE failure is "fouling" with sludge,wax, sand for for temp. problem and heating capacity still with in the specs

[kampret06]

----

[kampret06]

if there is sands and wax formations, what about adding sand trap on upstream of PHE.
i think sands is far more destructive on high pressure flow rather than wax. if your emulsions is clean from sand, i guess wax is not much troublesome with heater treater

cheers


adi cahyanto

[gusgon]

For treating (dehydration and desalting) of heavy crudes here in Venezuela we preheat the warm wet crude with hot dry crude, for two (02) reasons:
1) Energy efficiency
2) Cooling the hot dry treated crude for safe storage and minimum evaporation loss.
I worked in a facility where some preheating was accomplished through the use of plate heat exchager. The work fine as long as you keep them clean and prevent fouling. The did not do that for a time and the exchanger got clogged which reduce the efficiency of the system. Later the bough an special washing machine for keeping the equipment clean but was too late they have to remove them and take them to the shop for an overall. The learned the lesson: the equipment runs well as long as you keep it clean.

[oilhunter]

kampret06

What kind of snad trap can you suggest?? we do have de sanding system in Heater treater itself which they carried out almost 2times a week. but before entering the HT we dont have that's why I want to put inlet strainer. but as I said Im affraid of the maintainance like how often we are gonna clean it.

gusgon
Thanks for sharing we also do the same and keeping temp. into the right spec. have you ever had fouling in your Pre Heat Exchanger?

[kampret06]

i guess its all depend on how much of sands content on your emulsions.
by having desanding system integrated inside your heater treater then what about your pre heater, do you have desanding system integrated in pre heater also? if you don`t, than i think that's where your problem all came from. by looking at your descriptions that you need to do maintenance/cleaning of heater treater 2 times per week i really not recommend you to remove your pre heater (back up of your heater treater) as long as you don`t put a sand trap on the upstream. by adding sand trap in the upstream we hope that all emulsion entering heater treater are already clean of sand so you will need not to do the shut down of your heater treater for maintenance 2 times a week.

here i have an image of one of our sand trap (this picture are taken during modifications of the sand trap)

[link Point to another website Only the registered members can access]
this sand trap are set before entering choke manifold (not quite high pressure well, its around 2000 - 3000 psi)
by adding this sand trap before choke manifold, we hope that all of our equipment downstream will be safe of internally sand grinding. and of course less maintenance also.

cheers,


adi cahyanto

[oilhunter]

kampret06
Thank you for your time. we do have those kind of sand trap in offshore not in onshore..our PHE is a plate type so I don't know if there is a plate type that has desanding features..And as you're saying it can be a back up in our heater treater. there is no way to do that since PHE is taking heat from the outlet of Heater treater to heat up the inlet of PHE before entering to main Heater Treater.. so there is no way that we can run PHE alone without Heater Treater.

[kampret06]

owh i see..
so your pre heater is the plate type. yes, i think there is no desanding feature on it.
btw, i am saying that your pre heater used as back up since i assume that you put this pre heater on by pass placed parallel with heater treater just like my assumption on my previous post. that's because i don`t know your arrangement (PFD) and you don`t give me enough information for that.
and if you don`t mind, where is your plant located? just curious though.
but any way, glad that can be a help.
cheers


adi cahyanto