A flare system including a flare stack and a modular flare unit connected in parallel with the flare stack. The modular flare unit includes a frame, at least two energy conversion modules detachably supported by the frame, a fuel manifold, an air manifold, an exhaust manifold, and an electric generator. Each energy conversion module includes a combustion chamber configured to receive a flow of residue gas through the fuel inlet for combustion in the chamber at (or close to) atmospheric pressure, and a Stirling engine configured to convert heat from the combustion chamber into mechanical energy. The electric generator is connected to generate electric power from the mechanical energy.

A constant density heat exchanger is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid held at constant density within the chamber by the first and second control devices.

A constant density heat exchanger is provided. The constant density heat exchanger includes a housing extending between a first end and a second end and defining a chamber having an inlet and an outlet. A first flow control device is positioned at the inlet of the chamber and movable between an open position in which a working fluid is permitted into the chamber and a closed position in which the working fluid is prevented from entering the chamber. A second flow control device is positioned at the outlet of the chamber and movable between an open position in which the working fluid is permitted to exit the chamber and a closed position in which the working fluid is prevented from exiting the chamber. A heat exchange fluid imparts thermal energy to the volume of working fluid held at constant density within the chamber by the first and second control devices.

A rotary heat engine including a central crankshaft and a plurality of cylinder assemblies and a heat exchanger assembly. At least one of the plurality of cylinders, and preferably all of the plurality of cylinders includes a cylinder member, a piston member slidably positionable within the cylinder member, a connecting rod and a rolling diaphragm. The rolling diaphragm is positioned between the piston and the cylinder assembly to define a working volume which is in fluid communication with an opening that is in communication with the heat exchanger body.

An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly. The engine assembly may include a first monolithic body segment and a plurality of second monolithic body segments directly coupled or directly couplable to the first monolithic body segment. The first monolithic body segment may define a combustion chamber and a recirculation pathway in fluid communication with the combustion chamber. The recirculation pathway may be configured to recirculate combustion gas through the combustion chamber. The plurality of second monolithic body segments may respectively define at least a portion of a piston chamber and a plurality of working-fluid pathways fluidly communicating with the piston chamber.

An energy conversion apparatus may include an engine assembly, such as a monolithic engine assembly. The engine assembly may include a first monolithic body segment and a plurality of second monolithic body segments directly coupled or directly couplable to the first monolithic body segment. The first monolithic body segment may define a combustion chamber and a recirculation pathway in fluid communication with the combustion chamber. The recirculation pathway may be configured to recirculate combustion gas through the combustion chamber. The plurality of second monolithic body segments may respectively define at least a portion of a piston chamber and a plurality of working-fluid pathways fluidly communicating with the piston chamber.

A Stirling engine including a crosshead mechanism includes a low-pressure space and a high-pressure space. In the high-pressure space, a piston is driven by a heating/cooling cycle of a working fluid. The low-pressure space accommodates a crosshead portion connected to the piston via a piston rod, and a crank mechanism that rotates a crankshaft along with movement of the crosshead portion. A high-pressure gas seal in which a lip angle of a seal lip on the high-pressure side is smaller than that on the low-pressure side is provided around the piston rod at a partition between the low-pressure space and the high-pressure space.

Exemplary embodiments are directed to a heat engine. The heat engine includes a pipe that defines a continuous internal path. The pipe includes a first pipe section and a second pipe section. The heat engine includes a first piston disposed within the first pipe section. The heat engine includes a second piston disposed within the second pipe section. The first and second pistons are magnetically linked to travel along the continuous internal path of the pipe.

A rod seal assembly. The rod seal assembly includes a housing between two spaces configured to receive a reciprocating rod, the reciprocating rod disposed within a first space and a second space, a floating bushing configured to move axially and radially within the housing and disposed coaxially around the reciprocating rod, a rod seal configured to seal the outside diameter of the reciprocating rod relative to an inside surface of the floating bushing, and at least one stationary bushing fixed within the housing that may form a seal with the floating bushing to the axial flow of fluid in the presence of a pressure difference between the two spaces.

A Stirling engine can take advantage of adiabatic compression (which heats working gas leaving the cold cylinder) and adiabatic expansion (which cools working gas leaving the hot cylinder) to increase efficiency. In some implementations, partially-heated gas leaving the cold cylinder and partially-cooled gas leaving the hot cylinder can be routed directly to a regenerator using bypass paths that are opened using one-way valves. The resultant relatively reduced temperature difference across the regenerator, e.g., as compared to a typical Stirling engine, can reduce thermal loss and improve efficiency. In some implementations, the compression ratios of the Stirling engine can be adjusted such that the temperature of the adiabatic heated gas is the same or higher than the temperature of the adiabatic cooled temperatures, thus eliminating the need for a regenerator.