Abstract: Disclosed are methods to produce a high purity biogas from a lignocellulosic biomass. The methods can include inoculating a feedstock mixture comprising the lignocellulosic biomass with a mixed microbial community; contacting the feedstock mixture with effective amount of a soluble pH adjusting agent to increase a pH of the feedstock mixture to an alkaline pH; incubating the feedstock mixture anaerobically at a thermophilic temperature of at least 45° C.; collecting the high purity biogas. In other embodiments, the method comprises inoculating a feedstock mixture comprising the lignocellulosic biomass with a mixed microbial community; anaerobically digesting the feedstock mixture at a pH, temperature, and retention time effective to afford at least 30% carbohydrate conversion of the lignocellulosic biomass to produce high purity biogas having at least 85% methane by volume.

Abstract: A gas turbine engine centrifugal compressor axial forward thrust apparatus bleeds impeller tip aft bleed flow from between an annular centrifugal compressor impeller of a high pressure rotor and a diffuser directly downstream of the impeller. The apparatus then uses the aft bleed flow to pressurize an annular cavity extending radially between an inner combustor casing and the rotor and extending axially between forward and aft thrust balance seals. Forward and aft thrust balance lands are in sealing engagement with the forward and aft thrust balance seals on the high pressure rotor respectively. An annular stator plenum in fluid communication with the annular cavity is bounded in part by a forward end wall having conical diffusion holes therethrough which may be axially or circumferentially or axially and circumferentially angled. The forward thrust balance seal may be on an aft conical arm of the impeller.

Abstract: A gas turbine engine turbine cooling system includes an impeller and a diffuser directly downstream of the impeller, a bleed for bleeding clean cooling air from downstream of the diffuser, and one or more channels in fluid communication with the bleed. Each of the channels having a generally radially extending section followed by a generally axially aftwardly extending section terminating at an annular cooling air plenum connected to accelerators. The radially and axially aftwardly extending sections may be connected by a bend section of the cooling air channel and the axially aftwardly extending section may be angled radially inwardly going from the bend section to the cooling air plenum. Each of the cooling channels includes an inner wall formed by a forward end wall extending radially outwardly from an inner combustor casing, an annular cover covering a radially inner portion of the forward end wall, and the inner combustor casing.

Abstract: A gas turbine engine turbine cooling system includes an impeller and a diffuser directly downstream of the impeller, a bleed for bleeding clean cooling air from downstream of the diffuser, and one or more channels in fluid communication with the bleed. Each of the channels having a generally radially extending section followed by a generally axially aftwardly extending section terminating at an annular cooling air plenum connected to accelerators. The radially and axially aftwardly extending sections may be connected by a bend section of the cooling air channel and the axially aftwardly extending section may be angled radially inwardly going from the bend section to the cooling air plenum. Each of the cooling channels includes an inner wall formed by a forward end wall extending radially outwardly from an inner combustor casing, an annular cover covering a radially inner portion of the forward end wall, and the inner combustor casing.

Abstract: A gas turbine engine centrifugal compressor axial forward thrust apparatus bleeds impeller tip aft bleed flow from between an annular centrifugal compressor impeller of a high pressure rotor and a diffuser directly downstream of the impeller. The apparatus then uses the aft bleed flow to pressurize an annular cavity extending radially between an inner combustor casing and the rotor and extending axially between forward and aft thrust balance seals. Forward and aft thrust balance lands are in sealing engagement with the forward and aft thrust balance seals on the high pressure rotor respectively. An annular stator plenum in fluid communication with the annular cavity is bounded in part by a forward end wall having conical diffusion holes therethrough which may be axially or circumferentially or axially and circumferentially angled. The forward thrust balance seal may be on an aft conical arm of the impeller.