Method for testing hydrogen within a liquid hydrogen trailer

Abstract

A method and apparatus for testing hydrogen within a liquid hydrogen trailer are provided. The system allows for the analysis of hydrogen purity without pressurizing the entire trailer, thereby maintaining a lower heat content within the liquid hydrogen payload. The apparatus includes a sampling vessel (10) configured to receive liquid hydrogen from the trailer via a liquid fill valve (5). A pressure building circuit, comprising a pressure-building coil (20) and a PBU valve (25), is configured to withdraw liquid hydrogen from the sampling vessel (10), vaporize it, and return it to the sampling vessel ( 10) to increase internal pressure. Once the pressure reaches a predetermined threshold, an offtake valve (40) opens to transfer pressurized gaseous hydrogen to an analyzer. A controller may be used to automate the sequence of filling, pressurizing, and analyzing based on inputs from pressure transmitters (15, 35).

Description

[0001] IMPROVING COLD CONTENT OF LIQUID HYDROGEN LOADED INTO TRAILERS of the Invention

[0002] An enormous amount of heat is removed from gaseous hydrogen to create liquid hydrogen. Once liquid hydrogen (LH2) is in the liquid form, heat continuously transfers into the liquid. In order to maximize the useful life of the LH2, the LH2needs to have the lowest heat content when loaded into trailers at the liquefier.

[0003] At the end of a delivery, the liquid hydrogen is analyzed in order to confirm the purity of the LH2. The analyzers need gas at a pressure of approximately 25 psig in order for the analysis process to work. In order to provide the necessary pressure, warm gas is introduced into the trailer. The warm gas causes extra heat to be absorbed by the liquid hydrogen, thereby resulting in LH2 having a higher than ideal temperature.

[0004] Summary of the Invention

[0005] The present invention is directed to a method and apparatus that satisfies at least one of these needs. In certain embodiments of the present invention, the method for improving the cold content of liquid hydrogen loaded into trailers may include the use of a sampling vessel in fluid communication with an interior of the trailer. This sampling vessel can be filled with liquid hydrogen from the trailer, and after a desired amount is introduced into the sampling vessel, the flow of liquid hydrogen may be stopped. The pressure of the sampling vessel, which is below the desired testing pressure, can be increased using known techniques, e.g., pressurebuilding coils. Once the pressure in the sampling vessel is at or above the desired testing pressure, the now pressurized hydrogen can be sent from the sampling vessel to an analyzer in order to determine the purity of the hydrogen within the trailer.

[0006] In one embodiment of the present invention, a method for testing hydrogen within a liquid hydrogen trailer is provided. This method can include the steps of: a) transferring liquid hydrogen from the liquid hydrogen trailer to a sampling vessel, wherein the sampling vessel is at an initial pressure; b) pressurizing the sampling vessel by withdrawing a portion of the liquid hydrogen from the sampling vessel, vaporizing the portion of the liquid hydrogen and returning the vaporized hydrogen to the sampling vessel; c) measuring the pressure within the sampling vessel; d) upon a determination that the pressure within the sampling vessel is at or above a threshold pressure, transferring gaseous hydrogen from the sampling vessel to an analyzer; and e) determining a purity of the gaseous hydrogen using the analyzer.

[0007] According to other optional features of the method:

[0008] • step b) further comprises vaporizing the liquid hydrogen using a pressurebuilding coil;

[0009] • the steps of the method are automated using a controller, the controller having a processor configured with a control logic to, in response to the determination made in step d), initiate opening of the offtake valve, thereby executing the step of transferring gaseous hydrogen from the sampling vessel to the analyzer;

[0010] • the control logic is further configured to command a pressure building unit valve to close upon a determination that the pressure within the sampling vessel has reached a first predetermined threshold;

[0011] • the method may also include, prior to step a), a step of fluidly connecting the sampling vessel with the liquid trailer; and / or

[0012] • the liquid hydrogen trailer is maintained at a pressure below 10 psig, for example near 3 psig, during the step of transferring liquid hydrogen to the sampling vessel.

[0013] In another embodiment, an apparatus for testing hydrogen within a liquid hydrogen trailer is provided. In certain embodiments, the apparatus may include: a sampling vessel; means for pressurizing the sampling vessel; and means for sending pressurized gaseous hydrogen from the sampling vessel to an analyzer.

[0014] According to other optional features of the apparatus:

[0015] • the apparatus may also include a differential pressure transmitter;

[0016] • the means for pressurizing the sampling vessel comprise a pressure-building coil;

[0017] • the pressure-building coil is disposed outside of the sampling vessel;

[0018] • the pressure-building coil comprises an absence of outer insulation such that the pressure-building coil is configured to transfer heat from ambient air to liquid hydrogen flowing within the pressure-building coil;

[0019] • the pressure-building coil is disposed inside of the sampling vessel, wherein the pressure-building coil is configured to transfer heat from a heat transfer fluid to the liquid hydrogen within the sampling vessel; • the apparatus may also include means for transferring liquid hydrogen from the liquid hydrogen trailer to the sampling vessel, wherein the means for transferring liquid hydrogen comprise a liquid fill valve;

[0020] • the apparatus is disposed on a mobile sampling device configured to be temporarily connected to the liquid hydrogen trailer; and / or

[0021] • the sampling vessel 10 is fixedly disposed on the liquid hydrogen trailer.

[0022] In yet another aspect of the invention, an apparatus for testing hydrogen within a liquid hydrogen trailer is provided. In this embodiment, the apparatus may include: a sampling vessel; a liquid fill valve configured to control flow from the trailer to the sampling vessel; a pressure building circuit comprising a pressure-building coil configured to receive liquid hydrogen from the sampling vessel, vaporize the liquid hydrogen and return gaseous hydrogen to the sampling vessel; and an offtake valve configured to release pressurized gaseous hydrogen from the sampling vessel to an analyzer.

[0023] The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

[0024] The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.

[0025] These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the invention and are therefore not to be considered limiting of the invention’s scope as it can admit to other equally effective embodiments.

[0026] The Figure shows an embodiment of the invention.

[0027] Detailed

[0028] While the invention will be described in connection with several embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary', it is intended to cover all the alternatives, modifications and equivalence as may be included within the spirit and scope of the invention defined by the appended claims.

[0029] As noted earlier, the current state of the art relies on loading liquid hydrogen from the liquefaction unit into the trailer, followed by pressurization of the trailer with warm gaseous hydrogen, and then analyzing the trailer contents. Unfortunately, this method results in warmer trailer temperatures. For example, current methods often result in the liquid hydrogen in the trailer having a saturation pressure near 10 psig. In contrast, the sequence and apparatus of certain embodiments of the present invention allow the liquid hydrogen in the trailer to maintain a saturation pressure near 3 psig, resulting in significantly lower heat content and improved useful life of the payload.

[0030] In order to achieve this sequence, certain embodiments of the present invention can include a method and apparatus for pressurizing a sample of hydrogen externally from the trailer so that analyzers can perform analytical processes on the sample gas without adding heat to the bulk trailer contents.

[0031] In certain embodiments, the method can include the steps of loading a trailer with liquid hydrogen, withdrawing a sample of liquid hydrogen from the trailer and sending same to a sampling vessel; pressurizing the sampling vessel to a predetermined pressure; and then sending gaseous hydrogen from the sampling vessel to an analyzer. As shown in the Figure, sampling vessel 10, which, for example, can be a vacuum insulated vessel (or pipe), is configured to be filled with liquid hydrogen from a trailer via line 2. The apparatus includes a liquid fill valve 5 controlling the flow from the trailer. A differential pressure transmitter 15 is provided to measure the liquid level within the sampling vessel 10.

[0032] To facilitate pressurization, the apparatus includes a pressure building circuit. A pressure building unit (PBU) valve 25 controls flow into an uninsulated pressure-building coil 20. In this coil 20, atmospheric air transfers heat to the liquid hydrogen, causing vaporization. The resulting gas flows back into the sampling vessel 10 via line 12.

[0033] The apparatus further includes an offtake circuit for analysis. An offtake valve 40 controls the flow of hydrogen to an analyzer. Secondary' pressure-building coils 30 may be disposed upstream of the analyzer to ensure the sample gas is at the correct temperature. A pressure transmitter 35 (PT) is provided to monitor the pressure of the gas available for analysis. Additionally, the system includes a vent valve 50 for safety relief and a warm gas supply valve 45. In certain embodiments, the warm gas supply line associated with warm gas supply valve 45 includes a regulator set at approximately 10 psig to maintain a positive pressure in the system during standby modes to prevent contamination. Furthermore, a check valve can preferably be disposed downstream of the warm gas supply valve 45 to prevent high-pressure hydrogen from the vessel back-flowing into the warm gas supply system.

[0034] Controller and Automation Logic

[0035] In one aspect of the invention, a controller is used to automate the process. The controller may comprise a processor configured with control logic to execute specific method steps in response to sensor inputs and system requests. For example, the controller can communicate with various pieces of equipment (e.g., valves, pressure indicators, flow indicators, analyzer, etc. . . ) via known techniques, which may include, but are not limited to, both hardwired and wireless communications.

[0036] Filling Sequence:

[0037] The controller may be configured to, in response to a request for analysis gas (e.g., a "PLC Request = ON" signal), initiate a filling sequence. During this sequence, the control logic commands the vent valve 50 to open and the liquid fill valve 5 to open. Simultaneously, the controller commands the PBU valve 25, the warm gas supply valve 45, and the offtake valve 40 to close (or remain closed). Termination of Fill:

[0038] The controller is further configured to monitor the liquid level via the differential pressure transmitter (DPT) 15. In response to the DPT 15 indicating that the vessel 10 is full, the controller commands the liquid fill valve 5 to close.

[0039] Pressurization Sequence:

[0040] Following the filling step, the controller can initiate a pressurization sequence. The controller can monitor the pressure within the vessel (e.g., via PT 35 or DPT 15). In certain embodiments, the control logic is configured to control the PBU valve 25 based on a pressure setpoint. Specifically, the controller commands the PBU valve 25 to open when the pressure is less than a first predetermined threshold (e.g., 35 psig) to allow liquid to flow through coil 20 and repressurize the vessel. Once the pressure reaches or exceeds this first predetermined threshold, the controller can command the PBU valve 25 to close to prevent over-pressurization and maintain the vessel at the desired state for analysis. This cycle may repeat if the pressure drops below the threshold during the offtake process. The warm gas supply valve 45 remains closed during this operational phase.

[0041] Analysis / Offtake Sequence:

[0042] The controller is configured to manage the offtake valve 40 based on a multi-variable logic condition. Specifically, the controller commands the offtake valve 40 to open only if: (1) a request for analysis is active (PLC Request = ON); AND (2) the pressure within the system is greater than a minimum analysis pressure (e g., greater than 25 psig). If the pressure drops below this minimum, the controller may close the offtake valve 40 to rebuild pressure.

[0043] Safety and Standby Modes:

[0044] The controller may also provide safety and maintenance functions. For example, in response to the pressure exceeding a safety limit (e.g., 100 psig), the controller can command the vent valve 50 to open. Furthermore, in response to the request for analysis gas being removed (triggering "Standby" mode), the controller can be configured to close the liquid fill valve 5, close the PBU valve 25, and close the offtake valve 40. Simultaneously, the controller opens the warm gas supply valve 45. As noted, this supply may be regulated (e.g., at 10 psig) to keep the system inert and ready for the next cycle. Manual Operation

[0045] While the specific steps described above (Filling, Pressurization, Offtake) are described in connection with an automated controller, it is recognized that these steps can be conducted manually. For example, an operator may manually actuate the various valves (5, 25, 40, 45, 50) based on visual readings from the pressure transmitters (15, 35) to achieve the same sequence of loading, pressurizing, and analyzing the hydrogen sample.

[0046] Mobile Embodiment:

[0047] In one embodiment, the sampling vessel 10 is fixedly disposed on the trailer, such that a plurality of trailers will each have their own dedicated, sampling vessel. In another embodiment, the sampling vessel 10 is part of a mobile sampling device used to sample multiple trailers. In this mobile embodiment, the fluid communication between the trailer and the apparatus (Line 2) is established using a temporary connection, such as a vacuum-insulated flexible hose or a quick-connect coupling, allowing the device to be connected to a trailer, perform the filling and testing sequence described above, and then be disconnected. In another embodiment not shown, the means for increasing the pressure of the sampling vessel can include a heating coil disposed inside the sampling vessel, rather than (or in addition to) the external pressure building coil 20.

[0048] While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

[0049] The singular forms "a", "an" and "the" include plural referents, unless the context clearly dictates otherwise.

[0050] "Comprising" in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e.. anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms "consisting essentially of and “consisting of’ unless otherwise indicated herein.

[0051] “Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

[0052] Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur. Ranges may be expressed herein as from about one particular value, and / or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and / or to the other particular value, along with all combinations within said range.

Claims

CLAIMSI claim:

1. A method for testing hydrogen within a liquid hydrogen trailer, the method comprising the steps of: a) transferring liquid hydrogen (2) from the liquid hydrogen trailer to a sampling vessel, wherein the sampling vessel (10) is at an initial pressure; b) pressurizing the sampling vessel by withdrawing a portion of the liquid hydrogen from the sampling vessel, vaporizing (20) the portion of the liquid hydrogen and returning the vaporized hydrogen (12) to the sampling vessel (10); c) measuring (15) the pressure within the sampling vessel (10); d) upon a determination that the pressure within the sampling vessel (10) is at or above a threshold pressure, transferring gaseous hydrogen from the sampling vessel (10) to an analyzer; and e) determining a purity of the gaseous hydrogen using the analyzer.

2. The method as claimed in Claim 1, wherein step b) further comprises vaporizing the liquid hydrogen using a pressure-building coil (20).

3. The method as claimed in Claim 1 , wherein the steps of the method are automated using a controller, the controller having a processor configured with a control logic to, in response to the determination made in step d), initiate opening of the offtake valve (40), thereby executing the step of transferring gaseous hydrogen from the sampling vessel (10) to the analyzer.

4. The method as claimed in Claim 1, wherein the control logic is further configured to command a pressure building unit valve (25) to close upon a determination that the pressure within the sampling vessel (10) has reached a first predetermined threshold.

5. The method as claimed in Claim 1, further comprising, prior to step a), a step of fluidly connecting the sampling vessel (10) with the liquid trailer.

6. The method as claimed in Claim 1, wherein the liquid hydrogen trailer is maintained at a pressure below 10 psig, for example near 3 psig, during the step of transferring liquid hydrogen to the sampling vessel.

7. An apparatus for testing hydrogen within a liquid hydrogen trailer, the apparatus comprising: a sampling vessel (10); means for pressurizing (20) the sampling vessel (10); and means for sending (30, 40) pressurized gaseous hydrogen from the sampling vessel (10) to an analyzer.

8. The apparatus as claimed in Claim 7, further comprising a differential pressure transmitter (15).

9. The apparatus as claimed in Claim 7, wherein the means for pressurizing the sampling vessel (10) comprise a pressure-building coil (20).

10. The apparatus as claimed in Claim 9, wherein the pressure-building coil (20) is disposed outside of the sampling vessel (10).1 1. The apparatus as claimed in Claim 10, wherein the pressure-building coil (20) comprises an absence of outer insulation such that the pressure-building coil is configured to transfer heat from ambient air to liquid hydrogen flowing within the pressure-building coil.

12. The apparatus as claimed in Claim 9, wherein the pressure-building coil (20) is disposed inside of the sampling vessel (10). wherein the pressure-building coil is configured to transfer heat from a heat transfer fluid to the liquid hydrogen within the sampling vessel (10).

13. The apparatus as claimed in Claim 7, further comprising means for transferring liquid hydrogen (2, 5) from the liquid hydrogen trailer to the sampling vessel (10), wherein the means for transferring liquid hydrogen comprise a liquid fill valve (5).

14. The apparatus as claimed in Claim 7. wherein the apparatus is disposed on a mobile sampling device configured to be temporarily connected to the liquid hydrogen trailer.

15. The apparatus as claimed in Claim 7, wherein the sampling vessel 10 is fixedly disposed on the liquid hydrogen trailer.

16. An apparatus for testing hydrogen within a liquid hydrogen trailer, the apparatus comprising: a sampling vessel (10); a liquid fill valve (5) configured to control flow from the trailer to the sampling vessel (10); a pressure building circuit comprising a pressure-building coil (20) configured to receive liquid hydrogen from the sampling vessel (10) and return gaseous hydrogen to the sampling vessel (10); and an offtake valve (40) configured to release pressurized gaseous hydrogen from the sampling vessel (10) to an analyzer.

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