heating an oil tank.. not boiler related

[sxturbo]

I presume that the gensets have operated for the last 15 years, so the oil heating is marginal rather that fundamentally underpowered.

As the elements are thermostatically controlled, i'd just replace both elements with 1kw units and just double the capacity.

Calculating the heat loss out of that tank and heat sink will be difficult.

yes, the sets are 20 years old, and we have been looking after them for the past 2 years. there is little information from the past (rig has changed hands a few times) and there have been a few upgrade/downgrades aswell for which their appears to be zero paperwork for and so we do not have clear historical data.

it is presumed their hasn't been an issue in the past, in this particular instance the batteries on 1x of the machines have deteriorated with the cold weather and has caused some spurious alarms, this is ultimately the fault for them not starting, but it isn't helped with the low oil temp, the other engine is also very sluggish to start, again this is mostly due to the batteries but compounded by the lack of oil heating.

The rig have confirmed that the oil temp was only 11 degrees yesterday afternoon and was 7 degrees first thing this morning, and is now back to 11 degrees, with both heaters on all 3 sets being on permanently being confirmed as working suggests that they are not sufficient

our first thought would be to up the 2x heating units to 1kw each, but then we get asked whether this will be sufficient... and tbh i have no idea.

 

[bernardgreen]

anyway, the oil is currently not getting up to temperature and is causing issues with the starting of the machines

Assuming the machines are generating the electricity used on the rig. Where does the electricity for the heaters come from if none of the machines are running ?

 

[sxturbo]

Assuming the machines are generating the electricity used on the rig. Where does the electricity for the heaters come from if none of the machines are running ?

they shouldn't all go down at the same time, however ultimately in the rare event they do, they have an emergency power line from a neighbouring rig, but this is only enough to give them the basics the platform staff need, however it does cause issues with production.

new batteries are currently on their way by boat, and an engineer is attending on the flight monday.

 

[fixitflav]

Oil has a SHeat of about 4 kJ/(Kg.°C)

Did you mean Water has a SHeat of about 4 kJ/(Kg.°C)?

 

[ianmcd]

You shouldnt be touching anything on an oil rig very specialised and highly regulated

 

[SFK]

Did you mean Water has a SHeat of about 4 kJ/(Kg.°C)?

yes.
thanks.
typo corrected.

 

[sxturbo]

You shouldnt be touching anything on an oil rig very specialised and highly regulated

You talking to me or someone else??

It's my job to work on them....

It's a bit late, I've already overhauled 2 of the sets and upgraded the controls on 1, and have a 3 rd in the workshop partially stripped down.

 

[sxturbo]

Thought i's update on this.

so the maximum the size the elements can be is 1kw each, this is due to restraints from the wiring, and we have to upgrade the MCB to 10 amp, which will now be the maximum allowable for the wiring size.

We did do some testing and the 2x 1kw units will increase the temperature but only by around 7 degrees from its coldest temperature of 11 degrees, which is still significant enough to make the swap worthwhile.

we did look at the possibility of lagging the tank, but it is impossible.