Immersed plate heater separation system

1. A separation system for separating a multiphase fluid into an oil fraction and at least one of a water fraction and a gas fraction, the separation system comprising:

an elongated separator vessel which includes a multiphase fluid inlet and an oil outlet which is located downstream of the multiphase fluid inlet;

a first immersed plate heater which is positioned in the separator vessel between the multiphase fluid inlet and the oil outlet;

a heating medium heater which is located externally of the separator vessel and is fluidly connected to the first immersed plate heater;

wherein a heating fluid which is heated in the heating medium heater is circulated through the first immersed plate heater to heat the multiphase fluid;

a second immersed plate heater which is positioned in the separator vessel between the multiphase fluid inlet and the oil outlet, the second immersed plate heater comprising an inlet and an outlet; and

an oil discharge line which is connected between the oil outlet and the inlet of the second immersed plate heater;

wherein the oil fraction discharged from the oil outlet is circulated through the second immersed plate heater to heat the multiphase fluid.

2. The separation system of claim 1 , wherein the second immersed plate heater comprises an immersed plate heater bank.

3. The separation system of claim 2 , wherein the immersed plate heater bank comprises a plurality of generally rectangular, generally parallel, spaced apart heat exchanger plates.

4. The separation system of claim 1 , wherein the separator vessel includes an upstream section which is located downstream of the multiphase fluid inlet and a heating section which is located downstream of the upstream section, and wherein the first immersed plate heater is positioned in the heating section and the second immersed plate heater is positioned in one of the upstream section and the heating section.

5. The separation system of claim 1 , wherein the separator vessel includes a heating section which is located downstream of the multiphase fluid inlet and a separation section which is located downstream of the heating section, and wherein the first immersed plate heater is positioned in the heating section and the second immersed plate heater is positioned in one of the heating section and the separation section.

6. The separation system of claim 1 , wherein the separator vessel includes an upstream section which is located downstream of the multiphase fluid inlet, a heating section which is located downstream of the upstream section, and a separation section which is located downstream of the heating section, and wherein the first immersed plate heater is positioned in the heating section and the second immersed plate heater is positioned in one of the upstream section, the heating section and the separation section.

7. The separation system of any of claims 4 - 6 , wherein the first and second immersed plate heaters are positioned in the heating section.

8. A method for separating a multiphase fluid into an oil fraction and at least one of a water fraction and a gas fraction, the method comprising:

directing the multiphase fluid into an elongated separator vessel which includes a multiphase fluid inlet and an oil outlet;

heating the multiphase fluid with a first immersed plate heater which is positioned in the separator vessel and is fluidly connected to a heating medium heater that is located externally of the separator vessel;

separating the oil fraction from the multiphase fluid and discharging the oil fraction through the oil outlet;

heating the multiphase fluid with a second immersed plate heater which is positioned in the separator vessel and is fluidly connected to the oil outlet;

wherein the oil fraction discharged from the oil outlet is circulated through the second immersed plate heater to heat the multiphase fluid.

9. The method of claim 8 , wherein the second immersed plate heater comprises an immersed plate heater bank.

10. The method of claim 9 , wherein the immersed plate heater bank comprises a plurality of generally rectangular, generally parallel, spaced apart heat exchanger plates.

11. The method of claim 8 , wherein the separator vessel includes an upstream section which is located downstream of the multiphase fluid inlet and a heating section which is located downstream of the upstream section, and wherein the first immersed plate heater is positioned in the heating section and the second immersed plate heater is positioned in one of the upstream section and the heating section.

12. The method of claim 8 , wherein the separator vessel includes a heating section which is located downstream of the multiphase fluid inlet and a separation section which is located downstream of the heating section, and wherein the first immersed plate heater is positioned in the heating section and the second immersed plate heater is positioned in one of the heating section and the separation section.

13. The method of claim 8 , wherein the separator vessel includes an upstream section which is located downstream of the multiphase fluid inlet, a heating section which is located downstream of the upstream section, and a separation section which is located downstream of the heating section, and wherein the first immersed plate heater is positioned in the heating section and the second immersed plate heater is positioned in one of the upstream section, the heating section and the separation section.

14. The method of any of claims 11 - 13 , wherein the first and second immersed plate heaters are positioned in the heating section.