Systems and methods for stabilizing steam supply

Abstract

This invention belongs to the field of steam pipeline networks, specifically relating to systems for supplying steam and methods for ensuring a stable steam supply. The systems and methods of this invention can improve the operational reliability and construction safety of ring-shaped steam pipeline networks.

Description

Technical Field

[0001] This invention belongs to the field of steam pipeline networks, specifically relating to systems for supplying steam and methods for stable steam supply. Background Technology

[0002] In chemical production processes, steam is both a critical process medium and an important energy carrier. It provides heat energy for heating, separating, and purifying products, and participates in chemical reactions to increase reaction rates and product yields, thus playing a vital role in ensuring the smooth operation of chemical production. Large-scale integrated petrochemical plants typically contain multiple steam generation and consumption units, and the operating status of a single unit often has a cascading effect on upstream and downstream units, thus placing extremely high demands on the reliability of the steam supply.

[0003] Such facilities often require phased construction and commissioning. During the initial design and construction phase of the steam supply network (steam pipeline network), it is difficult to accurately predict the steam demand of subsequent units and to pre-set all interfaces. In the subsequent production and operation phase, the steam pipeline network often needs to be upgraded and modified. Furthermore, leaks in the steam pipeline network that occur while the system is not shut down require repair and plugging. However, steam is a high-energy substance, and performing pressurized work on steam pipelines carries extremely high risks, with related accidents occurring frequently. Therefore, when working in the construction area, the corresponding pipe sections must be isolated and the high-pressure steam inside must be released, while ensuring that the steam supply to already commissioned units is not disturbed.

[0004] Traditional chemical plants typically use a branched pipeline network for steam supply, with a single steam flow direction. This structure has a significant drawback: the failure or isolation of any single node will lead to an interruption of the downstream steam supply, making it difficult to meet the requirements of integrated bases for the safety of steam pipeline construction and the reliability of steam supply.

[0005] CN115234840A provides a steam transport method for a ring-shaped steam network. The method aims to find the minimum upstream pipeline source-side pressure that satisfies the lowest steam parameter conditions relative to the downstream pipeline demand side. By adjusting the upstream pipeline source-side pressure to this minimum value, the total condensate or heat loss across all pipelines from the source side to the demand side is minimized. While this method can reduce energy consumption and condensate generation through pressure regulation, thereby improving the reliability and safety of the ring-shaped network, its implementation relies on various complex environmental and pipeline parameters to accurately determine the upstream and downstream pressures.

[0006] Therefore, there is still a need to develop ring-shaped steam networks that can improve operational reliability and construction safety. Summary of the Invention

[0007] One object of the present invention is to overcome at least one disadvantage of the prior art and to provide a system for supplying steam and a method for stable steam supply.

[0008] Therefore, in a first aspect of the invention, a system for supplying steam is provided, characterized in that,

[0009] The system includes one or more ring-shaped steam pipe networks.

[0010] Each of the aforementioned annular steam pipe networks includes:

[0011] a) A ring-shaped steam pipeline used to transport steam.

[0012] b) One or more steam supply devices, and

[0013] c) Multiple steam consumption devices.

[0014] Each of the steam supply device and the steam consumption device is connected to the annular steam pipeline through two parallel branch pipes, which serve as backups for each other. A first double-stop-release valve group and a second double-stop-release valve group are respectively installed on the two branch pipes. A third double-stop-release valve group is installed on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double-stop-release valve group includes two stop valves and a release valve located between the two stop valves.

[0015] A bidirectional flow meter is installed on the annular steam pipeline between adjacent steam supply devices or steam consumption devices to detect the steam flow rate in the annular steam pipeline in real time.

[0016] In a second aspect of the invention, a method for stably supplying steam is provided, characterized in that the method includes providing the system of the invention to supply steam.

[0017] It has been unexpectedly discovered that the system and method of the present invention, through the combination of a ring steam network with specific valve groups, the connection combination between the ring steam networks, and the monitoring and regulation of the steam flow within the ring network, can improve the operational reliability and construction safety of the ring steam network. In particular, it can enable pressureless maintenance or modification while ensuring the steam supply to the already commissioned equipment and can prevent water hammer accidents. Attached Figure Description

[0018] Figure 1 A schematic diagram of the system for supplying steam according to the present invention is shown, wherein the system includes a ring-shaped steam network.

[0019] Figure 2A schematic diagram illustrating pressureless maintenance or modification in the method of the present invention is shown.

[0020] The annotations in the attached figures are explained as follows:

[0021] System 10 for supplying steam; ring steam network 101; ring steam pipeline 1011; steam supply device 1012; steam consumption device 1013; branch pipes 1014a, 1014b; first double shut-off and vent valve assembly 1015a, 1015a-i, 1015a-ii; second double shut-off and vent valve assembly 1015b, 1015b-i, 1015b-ii; third double shut-off and vent valve assembly 1015c, 1015c-i, 1015c-ii; bidirectional flow meter F; site to be constructed C.

[0022] Figure 3 Another schematic diagram of the system for supplying steam according to the present invention is shown, wherein the system includes three annular steam pipe networks.

[0023] The annotations in the attached figures are explained as follows:

[0024] System 20 for supplying steam; higher pressure annular steam network 201; local annular steam network 202; lower pressure annular steam network 203; annular steam lines 2011, 2021, 2031 of each network; interstage steam conversion devices 2001a, 2001b; steam supply device 2022 of local annular steam network 202; steam consumption device 2023 of local annular steam network 202; double shut-off and venting valve assembly (not shown), which is installed on two pairs of branch pipes connecting the interstage steam conversion devices 2001a, 2001b to each annular steam network, and on the pipelines between the two pairs of branch pipes and the corresponding annular steam network connection points.

[0025] Figure 4 Another schematic diagram of the system for supplying steam according to the present invention is shown, wherein the system includes two annular steam networks.

[0026] The annotations in the attached figures are explained as follows:

[0027] A system 30 for supplying steam; a high-pressure ring steam network 301; a low-pressure ring steam network 303; ring steam lines 3011 and 3031 of each network; an interstage steam supply and demand device 3002; a steam consumption device 3033 for the low-pressure ring steam network 303; a steam supply device 3012 for the high-pressure ring steam network 301; and a double shut-off and venting valve assembly (not shown), which is installed on two pairs of branch pipes connecting the interstage steam supply and demand device 3002 to each level of the ring steam network, and on the pipelines between the two pairs of branch pipes and the corresponding ring steam network connection points. Detailed Implementation

[0028] The invention is described in more detail in the following paragraphs. For the avoidance of doubt, any feature of one aspect of the invention may be used in any other aspect of the invention. Unless explicitly stated otherwise, each aspect described may be combined with any other aspect or combination thereof. In particular, any feature indicated as preferred may be combined with any other feature indicated as preferred or combination thereof.

[0029] The list of numerical endpoints includes all numbers and fractions within the corresponding range, along with the listed endpoints. It should be noted that when specifying any range of numerical values, any particular upper limit can be associated with any particular lower limit.

[0030] All references cited in this specification are incorporated herein by reference in their entirety.

[0031] In the context of this invention, unless otherwise specified, all terms used herein, including technical and scientific terms, shall have the meaning commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] The term “comprising” as used herein is synonymous with “including” or “containing” and is open-ended and does not exclude additional, unlisted ingredients, components or process steps.

[0033] In this invention, unless otherwise stated, the term "steam consuming device" refers to a conventional steam-consuming device known in the art that consumes steam from a local steam pipeline within a ring-shaped steam network. The steam inlet of the steam consuming device is connected to the ring-shaped steam pipeline via two parallel branch pipes. These two parallel branch pipes serve as backups for each other. The steam consuming device can obtain steam from the connected ring-shaped steam pipeline via one or both of the branch pipes. The steam outlet of the steam consuming device (if present) is typically not connected to the local pipeline network. The steam consuming device used herein can be a heater, endothermic reactor, stripping tower, power unit, steam turbine, desuperheater, pressure reducer, etc.

[0034] In this invention, unless otherwise stated, the term "steam supply device" refers to a conventional device known in the art for generating and outputting steam, which supplies steam to a local network within a ring-shaped steam pipeline. The steam outlet of the steam supply device is connected to the ring-shaped steam pipeline via two parallel branch pipes. These two parallel branch pipes serve as backups for each other. The steam supply device can supply steam to the connected ring-shaped steam pipeline via one or both of the branch pipes. Steam supply devices available herein can be steam boilers, such as superheated steam boilers, electrically heated superheated steam boilers, gas turbine waste heat boilers, etc.

[0035] As used herein, the term "interstage steam unit" includes an interstage steam conversion unit and an interstage steam supply and demand unit, which connects at least two annular steam networks, preferably annular steam networks supplying steam at different pressures to form a cascaded annular steam network. The interstage steam unit can be connected to each of the at least two annular steam networks via two parallel branch pipes. The two parallel branch pipes serve as backups for each other. The interstage steam unit can supply steam to and / or obtain steam from the connected annular steam networks via one or both of the two branch pipes. A first double-stop-vent valve assembly and a second double-stop-vent valve assembly are respectively installed on the two backup branch pipes, and a third double-stop-vent valve assembly is installed on the annular steam network between the connection points of the two branch pipes and the annular steam network. Each double-stop-vent valve assembly includes two stop valves and a vent valve located between the two stop valves.

[0036] In the context of interstage steam units in this invention, unless otherwise stated, the terms "(higher) pressure" and "(lower) pressure" refer to the steam pressure at the connection point of the interstage steam unit to one annular steam network compared to the steam pressure at the connection point of the interstage steam unit to another annular steam network, or to the steam pressure at the inlet of the interstage steam unit compared to the steam pressure at the outlet of the interstage steam unit. For example, two annular steam networks supplying steam at different pressures are interconnected by an interstage steam unit, wherein the annular steam network connected to which the higher-pressure steam is supplied is relative to the pressure at the connection point of the interstage steam unit to the other annular steam network. For example, the high / low pressure steam acquired / consumed by the interstage steam unit is relative to the pressure of the steam output / generated by the interstage steam unit, and vice versa.

[0037] As used in this invention, the term "interstage steam converter" refers to a device that consumes high-pressure steam and produces low-pressure steam by means of work or non-work, and is connected to at least two annular steam networks with steam at different pressures. Those skilled in the art will understand that the interstage steam converter can serve as a steam consumption device for supplying annular steam networks with higher pressure steam, and simultaneously as a steam supply device for supplying annular steam networks with lower pressure steam.

[0038] As used in this invention, the term "interstage steam supply and demand device" refers to a device connecting at least two annular steam networks, including a multi-condition production device capable of dynamically consuming or generating steam under different conditions. For example, in a first condition, the multi-condition production device can consume steam from an annular steam network connected to it; in a second condition, the multi-condition production device can generate steam at a higher or lower pressure than the consumed steam and supply the generated steam to the same or different annular steam networks connected to it.

[0039] The term “double block and bleed (DBB) valve assembly” as used in this invention refers to a double block and bleed (DBB) valve assembly known in the art, which may include two block valves and a bleed valve located between the two block valves.

[0040] The term "steam turbine" as used in this invention refers to a commonly known turbine in the art that can consume high-pressure steam and generate low-pressure steam by expanding and doing work.

[0041] The term "de-cooling and pressure reducing device" as used in this invention refers to commonly known de-cooling and pressure reducing devices in the art, which can consume high-pressure steam and generate low-pressure steam through non-work methods such as throttling and pressure reduction and water spraying for cooling. It typically includes valves such as pressure reducing valves or regulating valves and water spraying for cooling, and usually does not output shaft work externally.

[0042] Unless otherwise stated, the terms “(higher) pressure steam” and “(lower) pressure steam” as used in this invention refer to the comparison between the inlet and outlet steam pressures of the same steam consuming device, steam supply device, interstage steam device, interstage steam conversion device, or interstage steam supply and demand device.

[0043] The term "superheated steam" as used in this invention refers to steam with a temperature higher than the saturation temperature of the medium. Unless otherwise specified, "steam" in this invention refers to superheated steam. The superheated steam of this invention typically has a pressure of 0.4 to 5.0 MPa or a temperature of 150 to 320°C.

[0044] The term "steam consuming device with low pressure drop" as used in this invention refers to a steam pressure that is lower than the steam pressure supplied by the nearest steam supply device, with the decrease being less than or equal to 2%, 5%, 10%, 15%, or 20%. The steam consuming device with low pressure drop can obtain steam through one of its two branch pipes, with the other serving as a backup, to reduce energy loss during steam transport.

[0045] As used in this invention, the term "steam consuming device with a large pressure drop" refers to a steam pressure decrease of more than 20% compared to the steam pressure supplied by the nearest steam supply device, for example, greater than or equal to 25%, 30%, 35%, 40%, or even greater. The steam consuming device with a large pressure drop can obtain steam through only one or both of its two mutually redundant branch pipes. In the system of this invention, the pressure drop between the steam consuming device and the nearest steam supply device is dynamically changing.

[0046] The term "water hammer accident" used in this invention refers to a hydraulic transition phenomenon in a steam pipeline where internal steam condenses into liquid water due to a sudden change in pressure or temperature, and the pressure changes due to a sudden change in water flow velocity. This phenomenon is very harmful to the pipeline system.

[0047] The term "adjacent steam supply device and / or steam consumption device" as used in this invention means that there are no other steam supply devices or steam consumption devices between two adjacent devices. The combination of adjacent devices may include two adjacent steam supply devices, two adjacent steam consumption devices, and / or one steam supply device and one adjacent steam consumption device.

[0048] According to one aspect of the present invention, a system for supplying steam is provided, characterized in that,

[0049] The system includes one or more ring-shaped steam pipe networks.

[0050] Each of the aforementioned annular steam pipe networks includes:

[0051] a) A ring-shaped steam pipeline used to transport steam.

[0052] b) One or more steam supply devices, and

[0053] c) Multiple steam consumption devices.

[0054] Each of the steam supply device and the steam consumption device is connected to the annular steam pipeline through two parallel branch pipes, which serve as backups for each other. A first double-stop-release valve group and a second double-stop-release valve group are respectively installed on the two branch pipes. A third double-stop-release valve group is installed on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double-stop-release valve group includes two stop valves and a release valve located between the two stop valves.

[0055] A bidirectional flow meter is installed on the annular steam pipeline between adjacent steam supply devices or steam consumption devices to detect the steam flow rate in the annular steam pipeline in real time.

[0056] In one embodiment of the invention, the system may include multiple annular steam networks, wherein at least two annular steam networks supply steam with different pressures and are interconnected via interstage steam devices to form a cascaded annular steam network. Preferably, the interstage steam device may include:

[0057] An interstage steam converter that can obtain higher-pressure steam from a connected annular steam network supplying higher-pressure steam and output lower-pressure steam to a connected annular steam network supplying lower-pressure steam, and / or

[0058] An interstage steam supply and demand device that can obtain steam from one of the at least two annular steam networks connected to it under one operating condition, and output steam to the other of the at least two annular steam networks connected to it under another operating condition, particularly outputting steam with higher or lower pressure.

[0059] In one embodiment of the invention, the interstage steam conversion device may include a steam turbine that consumes higher-pressure steam to produce lower-pressure steam and / or a desuperheater / pressure reducer.

[0060] In one embodiment of the present invention, the interstage steam supply and demand device may include a multi-condition production device, which consumes the acquired steam in a first condition and generates steam at a higher or lower pressure than the acquired steam in a second condition.

[0061] In one embodiment of the invention, the steam consuming device may include a steam consuming device with a small pressure drop of less than 20% relative to the nearest steam supply device and a steam consuming device with a large pressure drop of more than 20%. The small pressure drop may be a pressure decrease of 2%, 5%, 10%, 15%, or 20% relative to the steam pressure supplied by the nearest steam supply device. The large pressure drop may be a pressure decrease of more than 20% relative to the steam pressure supplied by the nearest steam supply device, for example, greater than or equal to 25%, 30%, 35%, 40%, or even greater. Preferably, the steam consuming device with the large pressure drop can obtain steam through one or both of its respective two branch pipes, while the steam consuming device with the small pressure drop can obtain steam through only one of its respective two branch pipes, with the other as a backup. The two branch pipes of each steam consuming device are mutually redundant.

[0062] In one embodiment of the invention, the steam consuming device may include a steam consuming device with a large pressure drop relative to the nearest steam supply device, the steam consuming device with the large pressure drop obtaining steam through one or both of two mutually redundant branch pipes. The large pressure drop may be a pressure drop exceeding 20% ​​relative to the steam pressure supplied by the nearest steam supply device, for example, greater than or equal to 25%, 30%, 35%, 40%, or even greater.

[0063] In one embodiment of the invention, the steam consuming device may include a steam consuming device with a small pressure drop relative to the nearest steam supply device, wherein the steam consuming device with the small pressure drop can obtain steam only through one of its two branch pipes, with the other as a backup. The small pressure drop may be a pressure drop of 2%, 5%, 10%, 15%, or 20% of the steam pressure provided by the nearest steam supply device.

[0064] In one embodiment of the invention, the steam may be superheated steam. Preferably, the superheated steam may have a pressure of 0.4 to 5.0 MPa, for example 1.5, 2.0, 3.0, 3.5, 4.0 or 4.5 to 5.0 MPa, 0.6, 0.8, 1, 1.2, 1.4 or 1.6 to 2.0 MPa, 0.4 or 0.5 to 0.6 MPa, 0.5 to 4.5 MPa, 1 to 4 MPa, 1.5 to 3.5 MPa, or 2.0 to 3.0 MPa. Preferably, the superheated steam may have a temperature of 150 to 320°C, for example 150 to 190°C, 200 to 240°C, 220 to 260°C, 210 to 250°C, 220 to 240°C, or 250 to 320°C.

[0065] In one embodiment of the invention, the steam may be superheated steam, and the system includes three or more annular steam networks, wherein the superheated steam in the three annular steam networks has a pressure of 0.4 to 0.6 MPa and a temperature of 150 to 190°C; a pressure of 1.2 to 2.0 MPa and a temperature of 200 to 240°C; and a pressure of 3.5 to 5.0 MPa and a temperature of 250 to 320°C, respectively.

[0066] In one embodiment of the present invention, each of the bidirectional flow meters integrates a low flow rate alarm, wherein when any of the bidirectional flow meters detects a steam flow rate lower than a preset minimum allowable flow rate, a low flow rate alarm signal is triggered to indicate the low steam flow rate at the corresponding location in the local annular steam pipeline network where the corresponding bidirectional flow meter is located.

[0067] In one embodiment of the invention, in each of the annular steam networks, the steam supply rate of some or all of the steam supply devices is adjustable, and / or the steam consumption rate of some or all of the steam consumption devices is adjustable. Preferably, when the low flow rate alarm signal is triggered, the low flow rate phenomenon is eliminated by adjusting the steam supply rate of the steam supply devices and / or the steam consumption rate of the steam consumption devices in the corresponding annular steam network.

[0068] In one embodiment of the invention, the annular steam pipeline may be provided with a reserved interface for subsequent expansion to connect additional steam supply devices and / or steam consumption devices. In another embodiment, the annular steam pipeline is extended at any point to form an interface, for example, by cutting and forming an interface at the desired pipeline location, for subsequent expansion to connect additional steam supply devices and / or steam consumption devices.

[0069] In one embodiment of the present invention, such as Figure 1 As shown, a system 10 for supplying steam is provided, characterized in that the system includes a ring-shaped steam network 101, wherein the ring-shaped steam network 101 includes:

[0070] a) 1011 ring-shaped steam pipeline for transporting steam.

[0071] b) Two steam supply units 1012a and 1012b, and

[0072] c) Two steam consumption devices 1013a and 1013b,

[0073] Each of the steam supply devices 1012a and 1012b and the steam consumption devices 1013a and 1013b is connected to the annular steam pipeline 1011 via two parallel branch pipes 1014a and 1014b, which serve as backups for each other. A first double-stop-release valve group 1015a and a second double-stop-release valve group 1015b are respectively installed on the two branch pipes 1014a and 1014b. A third double-stop-release valve group 1015c is installed on the annular steam pipeline 1011 between the connection points of the two branch pipes 1014a and 1014b and the annular steam pipeline 1011. Each of the double-stop-release valve groups 1015a to 1015c includes two stop valves and a release valve located between the two stop valves.

[0074] A bidirectional flow meter F is installed on the annular steam pipeline 1011 between adjacent steam supply devices 1012a and 1012b, between adjacent steam consumption devices 1013a and 1013b, between adjacent steam supply device 1012a and steam consumption device 1013a, and between adjacent steam supply device 1012b and steam consumption device 1013b, to detect the steam flow rate in the annular steam pipeline in real time.

[0075] In a further implementation scheme, such as Figure 1 As shown, steam consuming device 1013a has a large pressure drop (e.g., more than 20%) relative to the nearest steam supply device 1012a. Steam consuming device 1013a can obtain steam through one of its two backup branch pipes 1014a or both 1014a and 1014b. Steam consuming device 1013b has a small pressure drop (e.g., less than 20%) relative to the nearest steam supply device 1012b. Steam consuming device 1013b can obtain steam only through one of its two backup branch pipes 1014a, with the other branch pipe 1014b as a backup, to increase steam flow rate and reduce heat loss.

[0076] In one embodiment of the present invention, such as Figure 3 As shown, a system 20 for supplying steam is provided, characterized in that the system includes three annular steam networks: a primary annular steam network 202, a higher-pressure annular steam network 201 supplying steam at a higher pressure than 202, and a lower-pressure annular steam network 203 supplying steam at a lower pressure than 202.

[0077] Each of the aforementioned annular steam pipe networks includes:

[0078] a) Annular steam pipelines 2011, 2021, or 2031 used for transporting steam.

[0079] b) Multiple steam supply units, and

[0080] c) Multiple steam consumption devices.

[0081] Each of the steam supply device and the steam consumption device is connected to the annular steam pipeline via two parallel branch pipes, which serve as backups for each other. A first double-stop-release valve group (not shown) and a second double-stop-release valve group (not shown) are respectively installed on the two branch pipes. A third double-stop-release valve group (not shown) is installed on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double-stop-release valve group includes two stop valves and a release valve located between the two stop valves.

[0082] A bidirectional flow meter (not shown) is installed on the annular steam pipeline between adjacent steam supply devices and / or steam consumption devices to detect the steam flow rate in the annular steam pipeline in real time.

[0083] In a further embodiment of the invention, such as Figure 3 As shown, the system 20 includes three annular steam networks: a primary annular steam network 202, a higher-pressure annular steam network 201 supplying steam at a higher pressure than the primary annular steam network 202, and a lower-pressure annular steam network 203 supplying steam at a lower pressure than the primary annular steam network 202. These three annular steam networks supply steam at different pressures. The primary annular steam network 202, the higher-pressure annular steam network 201, and the lower-pressure annular steam network 203 are respectively connected by an interstage steam conversion device 2001a and... The interstage steam converters 2001a and 2001b are interconnected, wherein the interstage steam converter 2001a obtains higher-pressure steam from the higher-pressure annular steam network 201 and outputs lower-pressure steam to the annular steam network 202 of its own stage, serving as a steam supply device 2022 for the annular steam network 202; and the interstage steam converter 2001b obtains higher-pressure steam from the annular steam network 202 of its own stage and outputs lower-pressure steam to the lower-pressure annular steam network 203, serving as a steam consumption device 2023 for the annular steam network 202 of its own stage, thereby forming a cascaded annular steam network. Preferably, the steam flux of the interstage steam converters 2001a and 2001b is adjustable.

[0084] In a further embodiment, the interstage steam converters 2001a and 2001b can independently function as steam turbines or desuperheaters that generate lower-pressure steam from higher-pressure steam.

[0085] In a further embodiment, the steam supplied by the three annular steam networks 201, 202, and 203 may be superheated steam. For example, the superheated steam in the lower-pressure annular steam network 203 may have a pressure of 0.4 to 0.6 MPa, and preferably a temperature of 150 to 190°C; the superheated steam in the same-level annular steam network 202 may have a pressure of 1.2 to 2.0 MPa, and preferably a temperature of 200 to 240°C; and the superheated steam in the higher-pressure annular steam network 201 may have a pressure of 3.5 to 5.0 MPa, and preferably a temperature of 250 to 320°C.

[0086] In one embodiment of the present invention, such as Figure 4As shown, a system 30 for supplying steam is provided, characterized in that the system 30 includes two annular steam networks: a high-pressure annular steam network 301 for supplying steam at higher pressure and a low-pressure annular steam network 303 for supplying steam at lower pressure, wherein each of the annular steam networks includes:

[0087] a) Circular steam pipelines 3011 or 3031 used for transporting steam.

[0088] b) Multiple steam supply devices (not shown), and

[0089] c) Multiple steam consuming devices (not shown),

[0090] Each of the steam supply device and the steam consumption device is connected to the annular steam pipeline via two parallel branch pipes, which serve as backups for each other. A first double-stop-release valve group (not shown) and a second double-stop-release valve group (not shown) are respectively installed on the two branch pipes. A third double-stop-release valve group (not shown) is installed on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double-stop-release valve group includes two stop valves and a release valve located between the two stop valves.

[0091] A bidirectional flow meter (not shown) is installed between adjacent steam supply devices or steam consumption devices on the annular steam pipeline to detect the steam flow rate in the annular steam pipeline in real time.

[0092] In a further implementation scheme, such as Figure 4 As shown, the system includes a high-pressure annular steam network 301 supplying higher-pressure steam and a low-pressure annular steam network 303 supplying lower-pressure steam. The two annular steam networks supply steam at different pressures and are interconnected via an interstage steam supply and demand device 3002 to form a cascaded annular steam network.

[0093] The interstage steam supply and demand device 3002 is connected only to the low-pressure annular steam network 303 in the first operating condition and obtains low-pressure steam from the low-pressure annular steam network 303, serving as a steam consumption device 3033 of the low-pressure annular steam network 303. In the second operating condition, it is connected only to the high-pressure annular steam network 301 and outputs high-pressure steam to the high-pressure annular steam network 301, serving as a steam supply device 3012 of the high-pressure annular steam network 301.

[0094] In a further implementation scheme, such as Figure 4As shown, the interstage steam supply and demand device 3002 includes a multi-condition production device, which consumes the obtained low-pressure steam in the first condition and generates high-pressure steam with a higher pressure than the obtained low-pressure steam in the second condition.

[0095] According to another aspect of the present invention, a method for stably supplying steam is provided, characterized in that the method includes providing the system of the present invention to supply steam.

[0096] In one embodiment of the present invention, each bidirectional flow meter may integrate a low flow rate alarm. When the detected steam flow rate is lower than a preset minimum allowable flow rate and a low flow rate alarm signal is triggered, the method further includes:

[0097] Adjust the steam supply and / or steam consumption of the local ring steam network corresponding to the low flow rate alarm signal until the steam flow rate detected by the corresponding bidirectional flow meter is not lower than the preset minimum allowable flow rate.

[0098] In one embodiment of the present invention, adjusting the steam supply of the local annular steam network may include:

[0099] a) Adjusting the steam supply of the steam supply devices that serve as steam boilers within the aforementioned annular steam network, and / or

[0100] b) Adjusting the steam flux of the interstage steam converter that connects the current-stage annular steam network to an annular steam network supplying higher-pressure steam, and / or

[0101] c) Adjust the steam output of the interstage steam supply and demand device that outputs steam to the local annular steam network.

[0102] In one embodiment of the present invention, adjusting the steam consumption of the local annular steam network may include:

[0103] a) Adjusting the steam consumption of the adjustable steam consuming devices included in the annular steam network of this stage, and / or

[0104] b) Adjusting the steam flux of the interstage steam converter that connects the current-stage annular steam network to an annular steam network supplying lower-pressure steam, and / or

[0105] c) Adjust the amount of steam obtained from the annular steam network of this stage as an interstage steam supply and demand device.

[0106] In one embodiment of the present invention, when performing pressureless maintenance or modification of the system, the method may further include the following steps:

[0107] (1) Identify the site to be constructed, particularly the site to be constructed on the annular steam pipeline, and close all double shut-off and vent valve assemblies directly adjacent to each other on the annular steam pipeline and the branch pipe to form an isolation zone around the site.

[0108] (2) Purge the steam within the isolation area until no steam is discharged from the discharge valves of all directly adjacent double-stop-vent valve assemblies, and

[0109] (3) To carry out repairs or modifications at the sites to be constructed;

[0110] During the maintenance or modification, the second or first double shut-off valve group, which serves as a backup to the first or second double shut-off valve group that is closed, is in the open state.

[0111] In a further embodiment, in step (1) of the method, at the site to be constructed located on an annular steam pipeline, two third double-stop-release valve assemblies, one first double-stop-release valve assembly, and one second double-stop-release valve assembly adjacent to the site are closed.

[0112] In another embodiment, in step (1) of the method, when the site to be constructed is located between the first or second double-stop-vent valve group and the connection point with the annular steam pipeline, two third double-stop-vent valve groups, one first double-stop-vent valve group, and one second double-stop-vent valve group adjacent to the site are closed.

[0113] In another embodiment, in step (1) of the method, when the site to be constructed is located between the first or second double shut-off and relief valve assembly and its corresponding device, only the first or second double shut-off and relief valve assembly is closed.

[0114] In one embodiment of the present invention, a method for stable steam supply is provided, characterized in that the method includes providing steam as described above. Figure 2 The system 10 of the present invention shown supplies steam, and

[0115] When performing pressureless maintenance or modification of the system 10, the method may further include the following steps:

[0116] (1) Determine the site C to be constructed on the annular steam pipeline 1011, and close all double-stop-release valve groups that are directly adjacent to each other on the annular steam pipeline 1011 and branch pipes 1014a and 1014b to form an isolation area around the site. Here, "directly adjacent" means that there are no other double-stop-release valve groups between the double-stop-release valve group and the construction site. That is, close the two third double-stop-release valve groups 1015c-i and 1015c-ii, one first double-stop-release valve group 1015a-ii, and one second double-stop-release valve group 1015b-i that are directly adjacent to the site C.

[0117] (2) Purge the steam within the isolation area until no steam is discharged from the discharge valves of all directly adjacent double-stop-vent valve assemblies 1015c-i, 1015c-ii, 1015a-ii, and 1015b-i.

[0118] (3) Repair or modify the site C where construction is to be carried out;

[0119] During the maintenance or modification, the second double-stop-release valve group 1015b-ii and the first double-stop-release valve group 1015a-i, which are backups of the closed first double-stop-release valve group 1015a-ii and the second double-stop-release valve group 1015b-i, are in the open state to ensure that the steam supply device 1012a and the steam consumption device 1013a supply and consume steam normally, respectively.

[0120] In one embodiment of the present invention, a method for stable steam supply is provided, characterized in that the method includes providing Figure 3 The system 20 of the present invention is shown to supply steam, wherein the system 20 forms a cascaded ring steam network as described above.

[0121] In a further embodiment of the present invention, in the method, each bidirectional flow meter (not shown) may be integrated with a low flow rate alarm (not shown). When the steam flow rate detected in the local annular steam network 202 is lower than a preset minimum allowable flow rate and a low flow rate alarm signal is triggered, the method further includes:

[0122] By adjusting the steam supply and / or steam consumption of the local ring steam network 202 corresponding to the low flow rate alarm signal, until the steam flow rate detected by the corresponding bidirectional flow meter is not lower than the preset minimum allowable flow rate.

[0123] In one embodiment of the present invention, adjusting the steam supply of the local annular steam network 202 may include:

[0124] a) Adjust the steam supply of the steam supply device (not shown) included in the annular steam network 202 as a steam boiler, and / or

[0125] b) Adjust the steam flux of the interstage steam converter 2001a, which connects the current annular steam network 202 to the higher-pressure annular steam network 201 that supplies steam at a higher pressure.

[0126] In one embodiment of the present invention, adjusting the steam consumption of the local annular steam network 202 may include:

[0127] a) Adjusting the steam consumption of the adjustable steam consumption device (not shown) included in the annular steam network 202, and / or

[0128] b) Adjust the steam flux of the interstage steam conversion device 2001b, which connects the current annular steam network 202 to the lower-pressure annular steam network 203 that supplies steam at a lower pressure.

[0129] In one embodiment of the present invention, the interstage steam conversion device 2001a connected to the higher pressure annular steam network 201 and / or the interstage steam conversion device 2001b connected to the lower pressure annular steam network 203 are adjusted until the steam flow rate detected by the bidirectional flow meter in the current annular steam network 202 is not lower than the preset minimum allowable flow rate.

[0130] In one embodiment of the present invention, a method for stable steam supply is provided, characterized in that the method includes providing Figure 4 The system 30 of the present invention shown is used to supply steam, wherein the system 30 forms a cascaded ring steam network as described above.

[0131] In one embodiment of the present invention, in the method, each bidirectional flow meter (not shown) may be integrated with a low flow rate alarm (not shown). When a low flow rate alarm signal is triggered because the steam flow rate detected in the high-pressure annular steam network 301 is lower than a preset minimum allowable flow rate, the method further includes the following steps:

[0132] The steam output of the steam supply device 3012, which is connected to the high-pressure annular steam network 301 as an interstage steam supply and demand device 3002, is adjusted to increase the steam supply, wherein the interstage steam supply and demand device 3002 outputs high-pressure steam to the high-pressure annular steam network 301 under a second operating condition.

[0133] In one embodiment of the present invention, in the method, each bidirectional flow meter (not shown) may be integrated with a low flow rate alarm (not shown). When a low flow rate alarm signal is triggered because the steam flow rate detected in the low-pressure annular steam network 303 is lower than a preset minimum allowable flow rate, the method further includes the following steps:

[0134] The steam consumption of the steam consuming device 3033, which is connected to the low-pressure annular steam network 303 as an interstage steam supply and demand device 3002, is adjusted to reduce the steam consumption, wherein the interstage steam supply and demand device 3002 obtains low-pressure steam from the low-pressure annular steam network 303 under a first operating condition.

[0135] It is understood that, for those skilled in the art, any equivalent substitutions or modifications to the technical solutions and inventive concepts of this invention should fall within the scope of protection of the appended claims.

Claims

1. A system for supplying steam, characterized in that, the system comprises one or more looped steam networks, wherein each of the looped steam networks comprises: a) a looped steam line for transporting steam, b) one or more steam supply devices, and c) a plurality of steam consumption devices, wherein each of the steam supply devices and the steam consumption devices is connected to the looped steam line through two parallelly arranged branch pipes, the two branch pipes are standby for each other, a first double-stop and one-discharge valve group and a second double-stop and one-discharge valve group are arranged on the two branch pipes respectively, and a third double-stop and one-discharge valve group is arranged on the looped steam line between the connection points of the two branch pipes and the looped steam line, each of the double-stop and one-discharge valve groups comprises two stop valves and one discharge valve between the two stop valves; wherein a bidirectional flow meter is arranged between adjacent steam supply devices and / or steam consumption devices on the looped steam line to detect the steam flow rate in the looped steam line in real time, wherein the steam consumption devices include steam consumption devices with a small pressure drop of 20% or less relative to the nearest steam supply device and steam consumption devices with a large pressure drop of more than 20%, wherein the steam consumption devices with a large pressure drop obtain steam through one or both of the respective two branch pipes, and the steam consumption devices with a small pressure drop obtain steam through only one of the respective two branch pipes, the other being a standby.

2. The system of claim 1, wherein, The system comprises a plurality of looped steam networks, wherein at least two looped steam networks supply steam with different pressures and are connected to each other through inter-stage steam devices to form cascaded looped steam networks, wherein the inter-stage steam devices comprise: an inter-stage steam conversion device that obtains high-pressure steam from a looped steam network connected thereto that supplies high-pressure steam and outputs low-pressure steam to a looped steam network connected thereto that supplies low-pressure steam, and the steam flow rate thereof is adjustable, and / or an inter-stage steam supply and demand device that obtains steam from one of the at least two looped steam networks connected thereto in one working condition and outputs steam to the other of the at least two looped steam networks connected thereto in another working condition.

3. The system of claim 2, wherein, The inter-stage steam conversion device comprises a steam turbine and / or a desuperheater that consumes high-pressure steam to generate low-pressure steam.

4. The system of claim 2, wherein, The inter-stage steam supply and demand device comprises a multi-working-condition production device that consumes obtained steam in a first working condition and generates steam with higher or lower pressure than the obtained steam in a second working condition.

5. The system of any one of claims 1 to 4, wherein, The steam is superheated steam, and the system comprises three or more looped steam networks, wherein the superheated steam in the three looped steam networks has pressures of 0.4 to 0.6 MPa and temperatures of 150 to 190℃, 1.2 to 2.0 MPa and 200 to 240℃, and 3.5 to 5.0 MPa and 250 to 320℃, respectively.

6. The system of any one of claims 1 to 4, wherein, Each of the bidirectional flow meters is integrated with a low flow alarm, wherein a low flow alarm signal is triggered when a detected steam flow rate in any of the bidirectional flow meters is below a pre-set minimum allowed flow rate to indicate a low steam flow rate at a corresponding location of the current looped steam pipe network where the bidirectional flow meter is located.

7. The system of claim 6, wherein, In each of the looped steam pipe networks, a steam supply amount of some or all of the steam supply devices is adjustable, and / or a steam consumption amount of some or all of the steam consumption devices is adjustable.

8. The system of any one of claims 1 to 4, wherein, The looped steam pipeline is provided with a reserved interface for later expansion to access additional steam supply devices and / or steam consumption devices.

9. A method of stabilizing a supply of steam, characterized by, The method comprises providing the system of any one of claims 1 to 8 to supply steam.

10. The method of claim 9, wherein, Each bidirectional flow meter is integrated with a low flow alarm, wherein a low flow alarm signal is triggered when a detected steam flow rate is below a pre-set minimum allowed flow rate, the method further comprises: Adjusting a steam supply amount and / or a steam consumption amount of the current looped steam pipe network corresponding to the low flow alarm signal until the detected steam flow rate of the corresponding bidirectional flow meter is not below the pre-set minimum allowed flow rate.

11. The method of claim 10, wherein, The adjusting the steam supply amount of the current looped steam pipe network comprises: a) adjusting a steam supply amount of a steam supply device included in the current looped steam pipe network as a steam boiler, and / or b) adjusting a steam flux of an inter-stage steam conversion device of claim 2 connecting the current looped steam pipe network with a looped steam pipe network supplying steam at a higher pressure.

12. The method of claim 10, wherein, The adjusting the steam consumption amount of the current looped steam pipe network comprises: a) adjusting a steam consumption amount of an adjustable steam consumption device included in the current looped steam pipe network, and / or b) adjusting a steam flux of an inter-stage steam conversion device of claim 2 connecting the current looped steam pipe network with a looped steam pipe network supplying steam at a lower pressure.

13. The method of claim 9 or 10, wherein, When pressureless repairing or modifying the system, the method further comprises the steps of: (1) determining a site to be worked on the looped steam pipeline, and closing all double block and bleed valve sets directly adjacent on the looped steam pipeline and branches to form an isolated area around the site, (2) evacuating steam in the isolated area until no steam is discharged from the bleed valves in all the directly adjacent double block and bleed valve sets, and (3) performing repair or modification at the site to be worked on; wherein, during the repair or modification, a second or first double block and bleed valve set that is a backup of the first or second double block and bleed valve set closed is in an open state.

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