US 9,341,084 B2Granted

Supercritical carbon dioxide power cycle for waste heat recovery

AssigneeEchogen Power Systems, LLC

InventorsTao Xie, Michael Vermeersch, Timothy Held

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Abstract

Aspects of the invention disclosed herein generally provide heat engine systems and methods for recovering energy, such as by generating electricity from thermal energy. In one configuration, a heat engine system contains a working fluid (e.g., sc-CO2) within a working fluid circuit, two heat exchangers configured to be thermally coupled to a heat source (e.g., waste heat), two expanders, two recuperators, two pumps, a condenser, and a plurality of valves configured to switch the system between single/dual-cycle modes. In another aspect, a method for recovering energy may include monitoring a temperature of the heat source, operating the heat engine system in the dual-cycle mode when the temperature is equal to or greater than a threshold value, and subsequently, operating the heat engine system in the single-cycle mode when the temperature is less than the threshold value.

Claims13

Dependent claims

A heat engine system, comprising:

a working fluid circuit comprising a working fluid, wherein the working fluid comprises carbon dioxide and at least a portion of the working fluid circuit contains the working fluid in a supercritical state;
a first heat exchanger fluidly coupled to and in thermal communication with the working fluid circuit, configured to be fluidly coupled to and in thermal communication with a heat source stream, and configured to transfer thermal energy from the heat source stream to the working fluid within the working fluid circuit;
a second heat exchanger fluidly coupled to and in thermal communication with the working fluid circuit, configured to be fluidly coupled to and in thermal communication with the heat source stream, and configured to transfer thermal energy from the heat source stream to the working fluid within the working fluid circuit;
a first expander fluidly coupled to the working fluid circuit and the first heat exchanger and disposed downstream of the first heat exchanger;
a second expander fluidly coupled to the working fluid circuit and the second heat exchanger and disposed downstream of the second heat exchanger;
a first recuperator fluidly coupled to the working fluid circuit, the first expander, and the first heat exchanger, the first recuperator disposed downstream of the first expander and upstream of the first heat exchanger;
a second recuperator fluidly coupled to the working fluid circuit, the second expander, and the second heat exchanger, the second recuperator disposed downstream of the second expander and upstream of the second heat exchanger;
a condenser fluidly coupled to the working fluid circuit and the first and second recuperators and disposed downstream of the first and second recuperators;
a first pump fluidly coupled to the working fluid circuit, the condenser, and the first and second recuperators, the first pump disposed downstream of the condenser and upstream of the first and second recuperators;
a second pump fluidly coupled to the working fluid circuit, the condenser, and the first recuperator, the second pump disposed downstream of the condenser and upstream of the first recuperator;
and
a plurality of valves operatively coupled to the working fluid circuit and configured to switch the heat engine system between a dual-cycle mode, in which the first and second heat exchangers and the first and second pumps are active, and a single-cycle mode, in which the first heat exchanger and the first expander are active and at least the second heat exchanger and the second pump are inactive,
wherein the second pump is a turbopump, the second expander is a drive turbine, and the drive turbine is coupled to the turbopump and operable to drive the turbopump when the heat engine system is in the dual-cycle mode.

10 more elements

A heat engine system, comprising:

a working fluid circuit comprising a working fluid, wherein the working fluid comprises carbon dioxide and at least a portion of the working fluid circuit contains the working fluid in a supercritical state;
a first heat exchanger fluidly coupled to and in thermal communication with the working fluid circuit, configured to be fluidly coupled to and in thermal communication with a heat source stream, and configured to transfer thermal energy from the heat source stream to the working fluid within the working fluid circuit;
a second heat exchanger fluidly coupled to and in thermal communication with the working fluid circuit, configured to be fluidly coupled to and in thermal communication with the heat source stream, and configured to transfer thermal energy from the heat source stream to the working fluid within the working fluid circuit;
a first expander fluidly coupled to the working fluid circuit and the first heat exchanger and disposed downstream of the first heat exchanger;
a second expander fluidly coupled to the working fluid circuit and the second heat exchanger and disposed downstream of the second heat exchanger;
a first recuperator fluidly coupled to the working fluid circuit, the first expander, and the first heat exchanger, the first recuperator disposed downstream of the first expander and upstream of the first heat exchanger;
a second recuperator fluidly coupled to the working fluid circuit, the second expander, and the second heat exchanger, the second recuperator disposed downstream of the second expander and upstream of the second heat exchanger;
a condenser fluidly coupled to the working fluid circuit and the first and second recuperators and disposed downstream of the first and second recuperators;
a first pump fluidly coupled to the working fluid circuit, the condenser, and the first and second recuperators, the first pump disposed downstream of the condenser and upstream of the first and second recuperators;
a second pump fluidly coupled to the working fluid circuit, the condenser, and the first recuperator, the second pump disposed downstream of the condenser and upstream of the first recuperator;
and
a plurality of valves operatively coupled to the working fluid circuit and configured to switch the heat engine system between a single-cycle mode and a dual-cycle mode, wherein the plurality of valves further comprises:
a first valve operatively coupled to the working fluid circuit, disposed downstream of the first pump, and disposed upstream of the second recuperator;
a second valve operatively coupled to the working fluid circuit, disposed downstream of the second recuperator, and disposed upstream of the condenser;
a third valve operatively coupled to the working fluid circuit, disposed downstream of the first pump, and disposed upstream of the first recuperator;
a fourth valve operatively coupled to the working fluid circuit, disposed downstream of the second pump, and disposed upstream of the first recuperator;
and
a fifth valve operatively coupled to the working fluid circuit, disposed downstream of the condenser, and disposed upstream of the second pump,
wherein each of the first, second, fourth, and fifth valves is in an opened-position during the dual-cycle mode of the heat engine system and a closed-position during the single-cycle mode of the heat engine system, and the third valve is in an opened-position during the single-cycle mode of the heat engine system and a closed-position during the dual-cycle mode of the heat engine system.

16 more elements

A method for recovering energy from a heat source, comprising:

operating a heat engine system in a dual-cycle mode, comprising:
heating a first mass flow of a working fluid in a first heat exchanger fluidly coupled to and in thermal communication with a working fluid circuit and a heat source stream, wherein the first heat exchanger is configured to transfer thermal energy from the heat source stream to the first mass flow of the working fluid within the working fluid circuit, the working fluid comprises carbon dioxide, and at least a portion of the working fluid circuit contains the working fluid in a supercritical state;
expanding the first mass flow in a first expander fluidly coupled to the first heat exchanger via the working fluid circuit;
heating a second mass flow of the working fluid in a second heat exchanger fluidly coupled to and in thermal communication with the working fluid circuit and the heat source stream, wherein the second heat exchanger is configured to transfer thermal energy from the heat source stream to the second mass flow of the working fluid within the working fluid circuit;
expanding the second mass flow in a second expander fluidly coupled to the second heat exchanger via the working fluid circuit;
at least partially condensing the first and second mass flows in one or more condensers fluidly coupled to the working fluid circuit;
pressurizing the first mass flow in a first pump fluidly coupled to the condenser via the working fluid circuit;
pressurizing the second mass flow in a second pump fluidly coupled to the condenser via the working fluid circuit;
transferring heat via a first recuperator from the first mass flow downstream of the first expander and upstream of the condenser to the first mass flow downstream of the second pump and upstream of the first heat exchanger;
and
transferring heat via a second recuperator from the second mass flow downstream of the second expander and upstream of the condenser to the second mass flow downstream of the first pump and upstream of the second heat exchanger;
and
switching the heat engine system from the dual-cycle mode to a single-cycle mode, comprising:
de-activating the second heat exchanger, the second expander, and the second pump;
directing the working fluid from the condenser to the first pump;
directing the working fluid from the first pump to the first heat exchanger;
and
de-activating the second recuperator and directing the working fluid from the second pump to the first recuperator.

15 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/051,433Filed 10 Oct 2013 · us provisional application
Priority: 12 Oct 2012
Published: US 2014/0102101 A117 Apr 2014
Granted: 17 May 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

F01K 7/32
Steam engine plants characterised by the use of specific types of engine ; Plants or engines characterised by their use of special steam…
F01K 25/103
The vapours being cold, e.g. ammonia, carbon dioxide, ether: carbon dioxide
F01K
Steam engine plants