A depressurization system in fluid communication with a high pressure, high temperature dense phase solids stream having coarse solid particles with entrained gas therein, the system comprising: - a means for cooling the high pressure, high temperature dense phase solids stream having coarse solid particles with entrained gas therein to a lower temperature to form a high pressure, lower temperature dense phase solids stream having coarse solid particles with entrained gas therein; and - a pressure letdown device configured to at least partially depressurize and separate the coarse solid particles from the high pressure, lower temperature dense phase solids stream having coarse solid particles with entrained gas therein; - wherein the pressure letdown device comprises: -- a housing defining an interior separator cavity and having a housing wall; -- a plurality of granules configured to form a granular filter bed; -- a filter disposed within the interior separator cavity and having an inner wall and a spaced outer wall, the outer wall being spaced from the housing wall and defining an enclosed annulus between the filter and the housing wall, wherein the inner wall defines a filter conduit in fluid communication with the high pressure, lower temperature dense phase solids stream, the inner wall comprising a first plurality of pores having a first pore diameter that is greater than a mean diameter of the coarse solid particles, in which the term 'coarse particles' refers to particles having a mean diameter greater than 40 microns, wherein the outer wall comprises a second plurality of pores having a second pore diameter that is less than a mean diameter of the granules of the granular filter bed, wherein the inner wall and the outer wall of the filter define an enclosed filtration cavity, and wherein the bed of granules is disposed therein the filtration cavity; and -- a gas outlet in selective fluid communication with the annulus configured for egress of at least partially depressurized gas; wherein a distal end of the filter conduit forms a solids outlet configured for egress of the coarse solid particles. - a means for cooling the high pressure, high temperature dense phase solids stream having coarse solid particles with entrained gas therein to a lower temperature to form a high pressure, lower temperature dense phase solids stream having coarse solid particles with entrained gas therein; and - a pressure letdown device configured to at least partially depressurize and separate the coarse solid particles from the high pressure, lower temperature dense phase solids stream having coarse solid particles with entrained gas therein; - wherein the pressure letdown device comprises: -- a housing defining an interior separator cavity and having a housing wall; -- a plurality of granules configured to form a granular filter bed; -- a filter disposed within the interior separator cavity and having an inner wall and a spaced outer wall, the outer wall being spaced from the housing wall and defining an enclosed annulus between the filter and the housing wall, wherein the inner wall defines a filter conduit in fluid communication with the high pressure, lower temperature dense phase solids stream, the inner wall comprising a first plurality of pores having a first pore diameter that is greater than a mean diameter of the coarse solid particles, in which the term 'coarse particles' refers to particles having a mean diameter greater than 40 microns, wherein the outer wall comprises a second plurality of pores having a second pore diameter that is less than a mean diameter of the granules of the granular filter bed, wherein the inner wall and the outer wall of the filter define an enclosed filtration cavity, and wherein the bed of granules is disposed therein the filtration cavity; and -- a gas outlet in selective fluid communication with the annulus configured for egress of at least partially depressurized gas; wherein a distal end of the filter conduit forms a solids outlet configured for egress of the coarse solid particles. -- a housing defining an interior separator cavity and having a housing wall; -- a plurality of granules configured to form a granular filter bed; -- a filter disposed within the interior separator cavity and having an inner wall and a spaced outer wall, the outer wall being spaced from the housing wall and defining an enclosed annulus between the filter and the housing wall, wherein the inner wall defines a filter conduit in fluid communication with the high pressure, lower temperature dense phase solids stream, the inner wall comprising a first plurality of pores having a first pore diameter that is greater than a mean diameter of the coarse solid particles, in which the term 'coarse particles' refers to particles having a mean diameter greater than 40 microns, wherein the outer wall comprises a second plurality of pores having a second pore diameter that is less than a mean diameter of the granules of the granular filter bed, wherein the inner wall and the outer wall of the filter define an enclosed filtration cavity, and wherein the bed of granules is disposed therein the filtration cavity; and -- a gas outlet in selective fluid communication with the annulus configured for egress of at least partially depressurized gas; wherein a distal end of the filter conduit forms a solids outlet configured for egress of the coarse solid particles.