Valve with remelt expansion port

Abstract

The valve for controlling the molten liquid includes an expansion port in liquid communication with an internal volume of the valve that is filled with the molten liquid. The expansion valve can open during thawing of the valve to allow the molten process material to expand from the internal volume into the expansion line as it melts. During initialization of the valve, an inert gas source, a pressure regulator, and an ultrasonic transition level sensor can be used to establish a liquid / gas interface at a desired height in the expansion line. The valve can include a multi-zone heater, with a first zone adjacent to the expansion port so that during thawing, after the first zone melts, the remaining zones can be sequentially activated in an order that ensures that each zone is activated only after the adjacent zone has melted.

Description

Statement of Government Interest

[0001] Portions of this invention were made with Government funding under Contract No. DE-NA0003525 and the Government may have certain rights.

[0002] This application claims the benefit of U.S. Patent Application No. 17 / 485,676, filed September 27, 2021, the disclosure of which is incorporated herein by reference in its entirety for all purposes. [Technical field]

[0003] The present invention relates to valves, and more particularly to valves used to control the flow of molten liquids that are solid at ambient temperatures. [Background technology]

[0004] Some process valves are required to control the flow of hot molten process liquids that are solid at room temperature. Often, when the molten process liquid cools and solidifies, its volume decreases, and when the process material re-melts, its volume expands again. Molten chloride salts are one example of such materials, which are of increasing importance to processes in several industries, including the concentrated solar power (CSP) industry and the thorium-based nuclear industry.

[0005] For example, during an upset condition, if the molten process liquid cools and solidifies or "freezes out" in the valve, freeze recovery may be difficult if the process material expands as it melts. This is because when the valve heats up, the remelted process material may not find the space in the valve for the necessary expansion, especially if the material remains solid at the inlet and outlet of the valve as it melts in the valve. As a result, the valve may be structurally damaged by the liquid expanding and remelting, which may render the valve inoperable. This risk is exacerbated when the valve design includes a substantial internal volume that would normally be filled with the molten process liquid.

[0006] Bellows sealed valves are typically used in critical valve applications where even a minimal amount of external valve leakage cannot be tolerated. In the case of molten process liquids, the thawing process can be particularly dangerous for bellows valves due to the large internal volume that tends to fill with process liquid (either inside or outside the bellows) and the inherent fragility of the bellows.

[0007] 1, the bellows sealed valve comprises an accordion-like bellows 100. One end 102 of the bellows 100 is welded or otherwise attached to a valve stem 104. The other end 106 of the bellows 100 is welded to a component 108 that is clamped or otherwise attached to a valve bonnet 109. When the valve is operated, the valve stem 104 is moved in a linear valve stroke to control the position of a valve plug 110 relative to a valve seat 112. During the valve stroke, the bellows 100 compresses or expands with the linear movement of the sliding valve stem 104.

[0008] The bellows 100 has static seals at each end 102, 106, and the bellows 100 surrounds the valve stem 104, providing a metal barrier between the process liquid inside the valve and the outside atmosphere, eliminating leakage at the valve stem 104. In the example of FIG. 1, the process liquid is outside the bellows 100 and the atmosphere is inside the bellows 100. For other bellows valves, the process liquid is inside the bellows 100 and the atmosphere is outside the bellows 100. The bellows valve (or other molten liquid valve) may further include a heater 116 controlled by a thermal controller 118, which may be used to thaw the valve if necessary.

[0009] Inherent in the design of a bellows valve is the presence of a substantial internal volume that is typically filled by process liquid. In particular, the process liquid typically contacts either the interior or exterior surface of the bellows 100 along its entire length. Because the metal bellows 100 flexes as the valve stem 104 moves, it is necessarily somewhat fragile and can be easily damaged by the expanding thawing process material.

[0010] Thus, there is a need for a valve design that is configured to accommodate the expansion of a normally molten process liquid as it freezes within the valve and then re-melts. Summary of the Invention

[0011] The present invention includes a valve design configured to accommodate expansion as a normally molten process liquid re-melts after freezing within the valve. In an embodiment, the valve is a bellows valve. Embodiments of the invention further include an expansion control system and a method for safely thawing the disclosed valve.

[0012] In accordance with the present invention, the valve design includes a process liquid expansion port that allows liquid communication between the expansion line and the valve's internal process liquid volume, which is normally filled with process liquid. During normal operation of the valve, process liquid is prevented from exiting through the expansion port by closing an expansion valve in the expansion line. During thawing of the process material, such as when recovering from an upset condition, the expansion valve is temporarily opened, thereby providing an expansion path for the molten process material.

[0013] In an embodiment, the expansion control system further includes a source of inert gas, such as nitrogen gas, and a pressure regulator capable of controlling the pressure of the inert gas in the expansion line. According to the disclosed method, when the valve is first activated and molten process liquid begins to flow into the expansion line, the inert gas is used to pressurize the expansion line, thereby preventing the process liquid from reaching the expansion valve.

[0014] In some of these embodiments, adjustment of the inert gas pressure continues during operation of the valve. In other embodiments, once the appropriate inert gas pressure is established in the expansion line, the expansion valve is closed, thereby leaving a constant amount of inert gas in contact with the process liquid and a liquid / gas boundary is established in the expansion line. If the process liquid expands or contracts during normal operation, for example due to temperature fluctuations of the process liquid, this is accommodated by shifting the liquid / gas boundary in the expansion line.

[0015] An embodiment further includes a liquid-gas transition sensor, such as an ultrasonic sensor, that can detect the level of the liquid / gas boundary in the expansion line, and the pressure of the inert gas is adjusted so that the liquid / gas boundary is at a desired location in the expansion line.

[0016] In embodiments, the valve further includes a heater configured to heat the valve, thereby maintaining the process material in the valve as a liquid during normal operation as needed, and remelting the process material if the valve needs to be thawed. In some of these embodiments, the heater is divided into separately controlled heating zones configured to heat corresponding portions of the internal process liquid volume of the valve. According to an embodiment of the method of the present invention, the heating zone extending to the expansion port is heated first, then the process material proximate to the expansion port is melted, and then the adjacent zones are heated sequentially, so that in each case the process material can expand as it melts into the adjacent already melted zone. As a result, damage and excessive stress to the valve during remelting of the process material in the valve is avoided.

[0017] Much of the following description is directed to an exemplary embodiment in which the valve is a bellows valve and the process liquid within the valve contacts the outside of the bellows, however, one skilled in the art will be able to readily adapt the principles of the present invention to virtually any type of process valve that controls a molten process liquid, including bellows valves in which the process liquid occupies the interior of the bellows, and including valves that are not bellows valves.

[0018] A first general aspect of the invention is a valve system configured to control a flow of molten process liquid, the valve system including a valve having an internal process liquid volume that is normally filled with process liquid during operation of the valve, an expansion port in the valve in liquid communication with the internal process liquid volume, and An inflation line in fluid communication with the inflation port and an inflation valve operable to allow or block fluid flow through the inflation line.

[0019] The embodiment further includes an expansion volume into which process liquid can flow from the expansion line when the expansion valve is open.

[0020] Any of the above embodiments may further include a pressurized inert gas source in gas communication with the expansion line. Some of these embodiments may further include a pressure regulator configured to regulate the pressure of the inert gas in the expansion line. In some of these embodiments, the expansion line includes a liquid / gas transition sensor capable of detecting a liquid / gas interface level in an interface zone of the expansion line. In some of these embodiments, the liquid / gas transition sensor is an ultrasonic sensor. And, any of these embodiments may further include a gas controller configured to control the pressure regulator to regulate the height of the liquid-gas interface level in the interface zone according to interface data provided to the gas controller by the liquid / gas transition sensor.

[0021] Any of the above embodiments may further include a pressure sensor included in the expansion line and configured to measure the pressure of the inert gas within the expansion line.

[0022] Any of the above embodiments may further include a temperature sensor included in the expansion line and configured to measure a temperature of the inert gas in the expansion line.

[0023] Any of the above embodiments may further include a gas heater configured to heat the inert gas in the expansion line.

[0024] Any of the above embodiments may further include a gas vent configured to vent the inert gas from the expansion line.

[0025] Any of the above embodiments may include a valve heater controlled by a thermal controller. Wow In some of these embodiments, the heater is divided into multiple heating zones that can be separately controlled by a thermal controller, with a first heating zone being proximate to the expansion port.

[0026] A second general aspect of the invention is a method for initializing a flow of molten process liquid through a valve, the method comprising: A) providing a valve system according to a first general aspect; B) Open the expansion valve. C) filling the internal process liquid volume with pressurized inert gas; D) introducing molten process liquid into the valve; E) controlling the pressure regulator so that the molten process liquid fills the interior process liquid volume and displaces the inert gas therein and enters the expansion line, whereby a liquid / gas interface is formed between the molten process liquid and the inert gas in the expansion line. Includes.

[0027] In an embodiment, the valve system further comprises a gas heater, and the method further comprises heating the inert gas before performing step B).

[0028] Any of the above embodiments may further include closing the expansion valve after step E).

[0029] In any of the above embodiments, the valve system may further include a liquid / gas transition sensor, and step E) includes monitoring the height of the liquid / gas interface in the expansion line using the liquid / gas transition sensor. In some of these embodiments, the method further includes, after step E), controlling the pressure regulator to maintain the liquid / gas interface within a specified height range in the expansion line.

[0030] A third general aspect of the invention is a method of thawing a valve configured to control a flow of a molten process liquid after the molten process liquid cools and solidifies into a solid process material within the valve, the method comprising: A) providing a valve according to a second general aspect; B) Open the expansion valve. C) The first heating The first process is continued until substantially all of the process material in the zone is melted. heating Activate the zone D) The first heating The next adjacent zone heating Continue until virtually all process material in the zone is melted. heating Activate the zone E) if the plurality of heating zones includes three or more heating zones, repeating step D) until all of the process material within the valve is melted, each of the heating zones being activated only after the process material in an adjacent heating zone has melted; F) Re-establishing the flow of molten process liquid through the valve. Includes.

[0031] In an embodiment, the valve system further includes a gas heater, and the method further includes, prior to performing step B), heating the inert gas and introducing the heated inert gas into the expansion line until the process material in the expansion line melts.

[0032] The features and advantages described herein are not exhaustive, and in particular many additional features and advantages will become apparent to those skilled in the art upon consideration of the drawings, specification, and claims.Furthermore, it should be noted that the language used in this specification has been chosen primarily for purposes of readability and instruction, and not to limit the scope of the inventive subject matter. [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is an isometric cross-sectional view of a prior art bellows valve.

[0034] [Diagram 2] FIG. 2 is an isometric cross-sectional view of one embodiment of the present invention.

[0035] [Diagram 3] FIG. 3 is an enlarged cross-sectional view of a portion of the valve of FIG. 2 shown connected to an expansion control system, the valve being drawn to scale.

[0036] [Figure 4] FIG. 4 is a flow diagram illustrating a method for implementing the disclosed valve in one embodiment of the present invention.

[0037] [Diagram 5] FIG. 5 is a cross-sectional view of a valve in one embodiment of the present invention, in which the valve includes multiple independently controlled heating zones.

[0038] [Figure 6] FIG. 6 is a flow diagram illustrating a method of thawing the valve of FIG. 5 in one embodiment of the present invention, the valve being drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] The present invention includes a valve design configured to accommodate expansion as a normally molten process liquid re-melts after freezing within the valve. In an embodiment, the valve is a bellows valve. Embodiments of the invention further include an expansion control system and a method for safely thawing the disclosed valve.

[0040] Referring to Figure 2, in accordance with the present invention, the valve design includes a process liquid expansion port 200 that allows liquid communication between an expansion line 204 and the valve's internal process liquid volume 202, which is normally filled with process liquid. During normal operation of the valve, process liquid is prevented from flowing out through the expansion port 200 by closing the expansion valve 206. During thawing of the process material, e.g., when recovering from an upset condition, the expansion valve 206 is temporarily opened, thereby providing an expansion volume for the molten process material. In the embodiment of Figure 2, the expansion valve 206 can withstand contact with the molten process liquid and can carry the newly melted process liquid to the expansion volume 208.

[0041] 3, in an embodiment, the expansion control system further includes a source 300 of an inert gas, such as nitrogen gas, and a pressure regulator 302 capable of controlling the pressure of the inert gas in the expansion line 204. In the embodiment of FIG. 3, the expansion line 204 further includes a gas heater 304 and a gas vent 306, as well as a temperature sensor 308 and a pressure sensor 310.

[0042] 4, in embodiments of the method of the present invention, before molten process liquid is introduced into the valve, an inert gas is heated 400 and an expansion valve is opened 402, thereby pressurizing 404 the expansion line 204 and the process liquid volume 202 inside the valve with the heated inert gas. The molten process liquid is then introduced into the valve 406 and the pressure of the inert gas is adjusted so that the process liquid fills the process liquid volume 202 in the valve and enters the expansion line 204, forming a liquid / gas interface (500 in FIG. 5) in the expansion line 204. The embodiments further include a liquid / gas transition sensor (502 in FIG. 5), such as an ultrasonic sensor, that can detect the level of the liquid / gas interface 500 in the expansion line 204. In some of these embodiments, the pressure of the inert gas is adjusted 408 to adjust the liquid / gas interface 500 to the desired level 500 in the expansion line 204.

[0043] In some of these embodiments, adjusting 408 the inert gas pressure continues 410 while the valve is operating. In other embodiments, once the appropriate inert gas pressure is established in the expansion line 204, the expansion valve 206 is closed 410, thereby leaving a constant amount of inert gas in contact with the process liquid. If the process liquid expands or contracts during normal operation, for example due to temperature fluctuations in the process liquid, this is accommodated by shifting the liquid / gas boundary 500 in the expansion line 204.

[0044] 5, in some embodiments, the heater 116 is divided into multiple heating zones 504-514 that are configured to heat corresponding portions of the valve's internal process liquid volume 202. The heating zones 504-514 are separately controlled by a thermal controller 516.

[0045] 6, according to some method embodiments of the present invention, the process of thawing the valve begins with opening 600 the expansion valve 206 and heating 602 the first heating zone 504 adjacent the expansion port 200. In an embodiment, prior to heating 602 the first heating zone 504, a gas heater 304 is used to heat an inert gas, and the heated inert gas is then used to melt any process liquid that may be frozen in the expansion line 204.

[0046] Once the process material is melted 602 in the first heated zone 504, a second heated zone 506 adjacent the first heated zone is heated 604 until the process material in the second heated zone 506 is melted. This process continues 606, so that adjacent heated zones are heated in sequence, so that in each case the melting process material can expand into the adjacent already melted heated zone. As a result, damage and excessive stress to the valve during re-melting of the process material in the valve is avoided. Finally, flow of molten process liquid is re-established 608 in the valve.

[0047] Many of the figures and corresponding descriptions presented herein refer to exemplary embodiments in which the valve is a bellows valve and the process liquid within the valve is in contact with the outside of the bellows, however, those skilled in the art will readily appreciate that the scope of the invention is not limited to these exemplary cases, but rather extends to virtually any type of process valve that controls a molten process liquid, including bellows valves in which the process liquid occupies the interior of the bellows, and also including valves that are not bellows valves.

[0048] The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. Every page of this submission, and all of its contents, however characterized, identified, or numbered, regardless of format or location within the application, is considered a substantial part of this application for all purposes. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure.

[0049] Although the present application is presented in a limited number of forms, the scope of the present invention is not limited to these forms only, and various changes and modifications are possible. The disclosure presented herein does not explicitly disclose all possible combinations of features that fall within the scope of the present invention. The features disclosed herein with respect to various embodiments can generally be interchanged and combined in any combination that is not self-contradictory without departing from the scope of the present invention. In particular, the limitations presented in the following dependent claims can be combined with their corresponding independent claims in any number and in any order without departing from the scope of the present disclosure, unless the dependent claims are logically incompatible with each other.

Claims

1. 1. A valve system configured to control a flow of a molten process liquid, comprising: a valve having an internal process liquid volume that is normally filled with the process liquid during operation of the valve; an expansion port in the valve that is in fluid communication with the internal process liquid volume; an inflation line in fluid communication with the inflation port; an expansion valve operable to allow or block the flow of fluid through the expansion line; A valve system comprising:

2. 2. The valve system of claim 1, further comprising: A valve system comprising an expansion volume into which process liquid can flow from the expansion line when the expansion valve is open.

3. 2. The valve system of claim 1, further comprising: A valve system comprising a source of pressurized inert gas in gas communication with the expansion line.

4. 4. The valve system of claim 3, further comprising: A valve system comprising a pressure regulator configured to regulate a pressure of the inert gas in the expansion line.

5. 5. The valve system of claim 4, The expansion line includes a liquid / gas transition sensor capable of detecting a liquid / gas interface level within an interface zone of the expansion line.

6. 6. The valve system of claim 5, The valve system, wherein the liquid / gas transition sensor is an ultrasonic sensor.

7. 6. The valve system of claim 5, further comprising: a gas controller configured to control the pressure regulator to adjust the height of the liquid-gas interface level in the interface zone according to interface data provided to the gas controller by the liquid / gas transition sensor;

8. 4. The valve system of claim 3, further comprising: A valve system comprising a pressure sensor included in the expansion line and configured to measure a pressure of the inert gas in the expansion line.

9. 4. The valve system of claim 3, further comprising: A valve system comprising a temperature sensor included in the expansion line and configured to measure a temperature of the inert gas in the expansion line.

10. 4. The valve system of claim 3, further comprising: A valve system comprising a gas heater configured to heat the inert gas in the expansion line.

11. 4. The valve system of claim 3, further comprising: A valve system comprising a gas vent configured to vent the inert gas from the expansion line.

12. 2. The valve system of claim 1, further comprising: A valve system comprising a valve heater controlled by a thermal controller.

13. 13. The valve system of claim 12, The heater is divided into a plurality of heating zones that can be separately controlled by the thermal controller, a first of the heating zones being adjacent to the expansion port.

14. 1. A method of initializing a flow of molten process liquid through a valve, comprising: A) providing a valve system according to claim 4, B) opening the expansion valve; C) filling said internal process liquid volume with said pressurized inert gas; D) introducing the molten process liquid into the valve; E) controlling the pressure regulator such that the molten process liquid fills the interior process liquid volume and displaces the inert gas therein and enters the expansion line, whereby a liquid / gas interface is formed between the molten process liquid and the inert gas in the expansion line; A method comprising:

15. 15. The method of claim 14, The method, wherein the valve system further comprises a gas heater, the method further comprising heating the inert gas prior to performing step B).

16. 15. The method of claim 14, After step E), the method further comprises closing the expansion valve.

17. 15. The method of claim 14, The method, wherein the valve system further comprises a liquid / gas transition sensor, and step E) includes monitoring a height of the liquid / gas interface in the expansion line using the liquid / gas transition sensor.

18. 20. The method of claim 17, The method further comprises, after step E), controlling the pressure regulator to maintain the liquid / gas interface within a specified height range in the expansion line.

19. 1. A method of thawing a valve configured to control flow of a molten process liquid after the process liquid has cooled and solidified into a solid process material within the valve, comprising: A) providing the valve according to claim 13; B) opening the expansion valve; C) activating the first heating zone until substantially all of the process material within the first heating zone is melted; D) activating a subsequent heating zone adjacent to the first heating zone until substantially all of the process material in the subsequent heating zone is melted; E) if the plurality of heating zones includes three or more heating zones, repeating step D) until all of the process material within the valve is melted, each of the heating zones being activated only after the process material in an adjacent heating zone has melted; F) re-establishing the flow of the molten process liquid through the valve. A method comprising:

20. 20. The method of claim 19, The valve system further comprises a gas heater, and the method further comprises, prior to performing step B), heating an inert gas and introducing the heated inert gas into the expansion line until a process material in the expansion line melts.

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