Systems and methods for using multiple cryogenic hydraulic turbines

Patent metadata

Field	Value
Publication number	US-10648729-B2
Application number	US-201615266634-A
Country	US
Kind code	B2
Filing date	Sep 15, 2016
Priority date	Jul 30, 2010
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

There is provided a system and method for producing liquefied natural gas (LNG). An exemplary method includes flowing a high-pressure stream of LNG through a first series of liquid turbines. The exemplary method also includes generating electricity by reducing the pressure of the high-pressure stream of LNG to form a low-pressure stream of LNG. The exemplary method additionally includes bypassing any one the liquid turbines that has a failure while continuing to produce electricity from the first series.

First claim

What is claimed is:

1. A method for generating electricity from liquid turbines, comprising:
in a normal mode, flowing a high-pressure liquid stream through a first plurality of n liquid turbines coupled in a first series, wherein, after a first turbine in the series, an inlet of each of a second through an n−1 liquid turbine is coupled to an outlet of a liquid turbine;
generating electricity from the first series by removing energy from the high-pressure liquid stream to form a low-pressure liquid stream;
bypassing any one of the first plurality of liquid turbines that has a failure while continuing to produce electricity with the remaining turbines of the first series; and
operating the first plurality of liquid turbines in the first series that are not bypassed to maintain a pressure, temperature, and flow rate of the low-pressure liquid stream to be the same as a pressure, temperature, and flow rate of the low-pressure liquid stream when operating in the normal mode.

2. The method of claim 1 , further comprising:
maintaining a total electrical output from the first series as a constant value when a liquid turbine is bypassed.

3. The method of claim 1 , further comprising:
removing a portion of the high-pressure liquid stream prior to the first series;
flowing the portion through a second plurality of n liquid turbines coupled in a second series, wherein, after a first turbine in the second series, an inlet of each of a second through an n−1 liquid turbine of the second series is coupled to an outlet of a preceding liquid turbine of the second series; and
wherein the second series is in parallel with the first series; and
generating electricity from the second series by removing energy from the portion of the high-pressure liquid stream to form another low-pressure liquid stream.

4. The method of claim 1 , wherein the high-pressure liquid stream comprises a liquefied natural gas.

5. The method of claim 1 , further comprising:
producing liquefied natural gas (LNG).

6. The method of claim 1 , further comprising:
driving a variable frequency drive from the electric generator, and if the variable frequency drive fails:
adjusting a speed of a turbine coupled to the generator to synchronize a generator frequency with a grid frequency; and
directly coupling an output of the generator to the electrical grid.

Assignees

• Holt Christopher G
• Griffith Todd S
• Exxonmobil Upstream Res Co

Inventors

• Holt Christopher G
• Griffith Todd S

Classifications

• F25J1/0042 Primary

  by liquid expansion with extraction of work · CPC title

• F25J2210/06

  Splitting of the feed stream, e.g. for treating or cooling in different ways · CPC title

• F25J2240/04

  Multiple expansion turbines in parallel · CPC title

• F25J1/0205

  as a dual level SCR refrigeration cascade · CPC title

• H02K7/1823

  structurally associated with turbines or similar engines · CPC title