Method and device for detecting an accumulation of sand in a separator vessel

#This application claims priority to Norwegian patent application 20034429 filed Oct. 3, 2003.

#The present invention relates to a method of detecting an accumulation of sand in a separator vessel, the separator being filled with a fluid that has a first temperature and being at least partly surrounded by a fluid that has a second temperature.

#The invention also relates to a separator device comprising a vessel for separating water from oil.

#Hereinafter, a preferred embodiment will be described by way of example with reference to the accompanying drawings on which:

#FIG. 1 is a schematic view showing a gravity separation vessel with a device according to the invention,

#FIG. 2 is a cross section of a part of a section of vessel, including a heap of sand on the bottom thereof, and

#According to FIG. 1, a device according to the invention comprises a gravity separator 1 of the kind used in the oil and gas industry for the separation of water and gas from oil that has been won out of an oil well.

#The separator 1 defines a vessel or tank 2 provided with an inlet 3 and separate outlets 4-6 for gas, oil and water respectively. The vessel 2 also comprises an outlet 8 for sand or other particulate, solid material that follows the oil and water from the well and accumulates at the bottom of the separator 1 due to the gravitational force. A flushing system (not shown) inside the separator vessel flushes out the sand through outlet 8 when required. In order to monitor the efficiency of this flushing system, and decided when to flush, it is imperative to monitor the solids build-up everywhere on the vessel bottom, as the solids may accumulate anywhere. A heap of sand 9 is indicated in FIG. 1. Typically, the vessel is a cylindrical vessel with a length of approximately 10 metres and width of approximately 3 metres. However the invention is not delimited to such vessel dimensions. The separator is surrounded by a fluid 7 such as sea water, in the case of a submerged subsea separator, said fluid having a temperature lower than the temperature of the liquid in the vessel 2.

#As can be seen in FIG. 2, the vessel consists of a steel wall 10 on the outside of which there is provided a layer 11 of a thermally insulating material, preferably rubber. Here, sand 9 covers the inside of the steel wall 10 at a bottom region thereof. In this example, the wall thickness is 100 mm, the rubber insulation thickness is 100 mm and the sand deposit thickness is 25 mm. The temperature of the fluid inside the vessel 2 is 100° C., and the temperature of the surrounding fluid, sea water, is 4° C.