Hydrogen generation assemblies and hydrogen purification devices
Hydrogen generation assemblies, hydrogen purification devices, and their components are disclosed. In some embodiments, the devices may include a permeate frame with a membrane support structure having first and second membrane support plates that are free from perforations and that include a plurality of microgrooves configured to provide flow channels for at least part of the permeate stream. In some embodiments, the assemblies may include a return conduit fluidly connecting a buffer tank and a reformate conduit, a return valve assembly configured to manage flow in the return conduit, and a control assembly configured to operate a fuel processing assembly between run and standby modes based, at least in part, on detected pressure in the buffer tank and configured to direct the return valve assembly to allow product hydrogen stream to flow from the buffer tank to the reformate conduit when the fuel processing assembly is in the standby mode.
1. A hydrogen generation assembly, comprising:
a fuel processing assembly configured to receive a feed stream and to be operable among a plurality of modes, including a run mode in which the fuel processing assembly produces a product hydrogen stream from the feed stream, and a standby mode in which the fuel processing assembly does not produce the product hydrogen stream from the feed stream, the fuel processing assembly including:
a hydrogen-producing region containing a reforming catalyst and configured to receive the feed stream and produce a reformate stream,
one or more hydrogen-selective membranes configured to receive the reformate stream and produce at least part of the product hydrogen stream and a byproduct stream from the reformate stream, and
a reformate conduit fluidly connecting the hydrogen-producing region and the one or more hydrogen-selective membranes;
a buffer tank configured to contain the product hydrogen stream;
a product conduit fluidly connecting the fuel processing assembly and the buffer tank;
a return conduit fluidly connecting the buffer tank and the reformate conduit;
a tank sensor assembly configured to detect pressure in the buffer tank;
a control assembly configured to operate the fuel processing assembly between the run and standby modes based, at least in part, on the detected pressure in the buffer tank; and
a return valve assembly configured to manage flow in the return conduit, the control assembly being configured to direct the return valve assembly to allow the product hydrogen stream to flow from the buffer tank to the reformate conduit when the fuel processing assembly is in the standby mode.
2. The assembly of claim 1 , wherein the control assembly is configured to direct the return assembly to allow the product hydrogen stream to flow from the buffer tank to the reformate conduit at one or more predetermined time intervals when the fuel processing assembly is in the standby mode.
3. The assembly of claim 2 , wherein the control assembly is configured to direct the return assembly to allow the product hydrogen stream to flow from the buffer tank to the reformate conduit for a predetermined duration at the one or more predetermined time intervals when the fuel processing assembly is in the standby mode.
4. The assembly of claim 1 , wherein the return valve assembly includes at least one valve that is configured to operate between an open position in which the product hydrogen stream from the buffer tank flows through the return conduit and into the reformate conduit, and a closed position in which the product hydrogen stream from the buffer tank does not flow through the return conduit and into the reformate conduit.
5. The assembly of claim 4 , wherein the control assembly is configured to move the at least one valve to the open position for a predetermined duration when the fuel processing assembly is in the standby mode.
6. The assembly of claim 5 , wherein the control assembly is configured to move the at least one valve to the open position for a predetermined duration at one or more predetermined time intervals when the fuel processing assembly is in the standby mode.
7. The assembly of claim 4 , wherein the control assembly is configured to move the at least one valve to the open position at one or more predetermined time intervals when the fuel processing assembly is in the standby mode.
8. The assembly of claim 1 , further comprising a plurality of heaters in thermal communication with the hydrogen-producing region and the one or more hydrogen-selective membranes, wherein the control assembly is configured to operate the plurality of heaters to maintain the hydrogen-producing region and the one or more hydrogen-selective membranes within a predetermined temperature range when the fuel processing assembly is in the standby mode.