Fluidized-bed heat exchanger for conversion of thermal energy to electricity

A heat exchanger configured to transfer thermal energy between a gas stream and a stream of solid particles, the heat exchanger comprising:

• a means for contacting the gas stream with the stream of solid particles resulting in a transfer of thermal energy between the gas stream and the stream of solid particles;
• an outer shell;
• an inner shell;
• and
• a means for directing the solid particles stream to the means for contacting comprising a port which penetrates the inner shell and outer shell;
• wherein
• the heat exchanger is configured to gravitationally pass the stream of solid particles through the means for contacting,
• the heat exchanger is configured such that the gas stream flows counter-current to the stream of solid particles, and
• the means for directing is positioned before the means for contacting, relative to the direction of flow of the stream of solid particles through the heat exchanger.