System and method for stabilized supply of steam

Abstract

The invention belongs to the field of steam pipe networks, and particularly relates to a system for supplying steam and a method for stably supplying steam. According to the system and the method, the operation reliability and the construction safety of the annular steam pipe network can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of steam pipe networks, and in particular relates to a system for supplying steam and a method for stably supplying steam. Background Art

[0002] In chemical production, steam is both a critical process medium and an important energy carrier. It provides thermal 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 chemical production. Large-scale integrated petrochemical complexes typically include multiple steam-generating and steam-consuming units, and the operating status of a single unit often has a cascading impact on upstream and downstream units, placing extremely high demands on the reliability of the steam supply.

[0003] Such bases often need to be built and put into production in phases. During the initial design and construction phase of the steam supply network (steam network), it is difficult to accurately predict the steam demand of subsequent devices and it is impossible to pre-set all interfaces. During the subsequent production operation phase, the steam network often needs to be modified and upgraded. In addition, leaks that occur in the steam network when it is not shut down also need to be repaired and plugged. However, steam is a high-energy substance, and the risk of performing pressurized operations on steam pipelines is extremely high, and related accidents occur from time to time. Therefore, when working in the construction area, the corresponding pipe section must be isolated and the high-pressure steam inside it must be discharged, while ensuring that the steam supply of the already-commissioned units is not disturbed.

[0004] Traditional chemical plants generally use a branched pipe network for steam supply with a single steam flow direction. This structure has obvious defects, namely that the failure or isolation of any single node will lead to the interruption of its downstream steam supply, which makes it difficult to meet the requirements of integrated bases for steam pipe network construction safety and steam supply reliability.

[0005] CN115234840A provides a steam transportation method for an annular steam network. The method aims to find the minimum pressure on the upstream pipeline source side that satisfies the minimum steam parameter condition relative to the downstream pipeline demand side, and adjusts the upstream pipeline source side pressure to this minimum value, thereby minimizing the sum of condensate or heat losses in all pipelines from the source side to the demand side. While this method can reduce energy consumption and condensate generation through pressure regulation, thereby improving the reliability and safety of the annular network, its implementation relies on a variety of complex environmental and pipeline parameters to accurately determine upstream and downstream pressures.

[0006] Therefore, there is still a need to develop an annular steam pipe network that can improve operational reliability and construction safety. Summary of the Invention

[0007] An 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 stably supplying steam.

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

[0009] The system includes one or more annular steam pipe networks,

[0010] Wherein, each of the annular steam pipe networks comprises:

[0011] a) Annular steam pipeline for conveying steam,

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

[0013] c) multiple steam consumers,

[0014] Wherein, each of the steam supply device and the steam consumption device is connected to the annular steam pipeline through two branch pipes arranged in parallel, and the two branch pipes are standby for each other. A first double block-and-relief valve group and a second double block-and-relief valve group are respectively provided on the two branch pipes, and a third double block-and-relief valve group is provided on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double block-and-relief valve group includes two block valves and a relief valve located between the two block valves.

[0015] Wherein, a bidirectional flow meter is provided 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 present invention, a method for stably supplying steam is provided, characterized in that the method comprises providing the system of the present invention to supply steam.

[0017] It has been unexpectedly discovered that the system and method of the present invention can improve the operational reliability and construction safety of the annular steam network by combining the annular steam network with a specific valve group, combining the connections between the annular steam network, and monitoring and regulating the steam flow within the annular steam network. In particular, it can achieve pressure-free maintenance or modification while ensuring the steam supply of the already commissioned equipment and prevent water hammer accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram showing a system for supplying steam according to the present invention, wherein the system comprises a circular steam pipe network.

[0019] Figure 2Schematic diagram showing pressure-free repair or renovation in the method of the present invention

[0020] The following are the descriptions of the reference numerals:

[0021] A system 10 for supplying steam; an annular steam network 101; an annular steam pipeline 1011; a steam supply device 1012; a steam consumption device 1013; branch pipes 1014a, 1014b; a first double block-and-relief valve group 1015a, 1015a-i, 1015a-ii; a second double block-and-relief valve group 1015b, 1015b-i, 1015b-ii; a third double block-and-relief valve group 1015c, 1015c-i, 1015c-ii; a two-way flow meter F; and a location C to be constructed.

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

[0023] The following are the descriptions of the reference numerals:

[0024] A system 20 for supplying steam; a higher-pressure annular steam network 201; an annular steam network 202 at this level; a lower-pressure annular steam network 203; annular steam pipelines 2011, 2021, 2031 of each network; inter-stage steam conversion devices 2001a, 2001b; a steam supply device 2022 of the annular steam network 202 at this level; a steam consumption device 2023 of the annular steam network 202 at this level; a double-stop and one-release valve group (not shown), which is arranged on the two pairs of branch pipes connecting the inter-stage steam conversion devices 2001a, 2001b with the annular steam networks at each level, and on the pipelines between the two pairs of branch pipes and the connection points of the corresponding annular steam networks.

[0025] Figure 4 Another schematic diagram shows a system for supplying steam according to the present invention, wherein the system comprises two annular steam pipe networks.

[0026] The following are the descriptions of the reference numerals:

[0027] A system 30 for supplying steam; a high-pressure annular steam network 301; a low-pressure annular steam network 303; annular steam pipelines 3011, 3031 of each network; an inter-stage steam supply and demand device 3002; a steam consumption device 3033 of the low-pressure annular steam network 303; a steam supply device 3012 of the high-pressure annular steam network 301; a double-blocking and one-release valve group (not shown), which is arranged on the two pairs of branch pipes connecting the inter-stage steam supply and demand device 3002 and the annular steam networks at each stage, and on the pipelines between the two pairs of branch pipes and the corresponding annular steam network connection points. DETAILED DESCRIPTION

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

[0029] The recitation of numerical endpoints includes all numbers and fractions within the corresponding range, as well as the recited endpoints. It should be noted that in specifying any range of numerical values, any particular upper value can be associated with any particular lower value.

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

[0031] In the context of the present invention, unless otherwise defined, all terms used in the present invention, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0032] As used herein, the term "comprising" is synonymous with "including" or "containing" and is inclusive or open-ended and does not exclude additional, unrecited ingredients, components or process steps.

[0033] In the present invention, unless otherwise specified, the term "steam consuming device" used refers to a conventional steam-consuming device known in the art, which consumes the steam in a current-level pipe network in a ring-shaped steam pipe network. The steam inlet of the steam consuming device is connected to the ring-shaped steam pipeline through two branch pipes arranged in parallel. The two branch pipes arranged in parallel are standby for each other. The steam consuming device can obtain steam from the connected ring-shaped steam pipeline through one or both of the branch pipes. The steam outlet (if any) of the steam consuming device is usually no longer connected to the current-level pipe network. The steam consuming device used herein can be a heater, an endothermic reactor, a stripping tower, a power plant, a steam turbine, a temperature reducing device, etc.

[0034] In the present invention, unless otherwise specified, the term "steam supply device" refers to a conventional device known in the art for generating and outputting steam, which supplies steam to the pipeline network at the corresponding level within a circular steam network. The steam outlet of the steam supply device is connected to the circular steam pipeline via two parallel branch pipes. The two parallel branch pipes serve as backup for each other. The steam supply device can supply steam to the connected circular steam pipeline via one or both of the branch pipes. The steam supply device useful herein can be a steam boiler, such as a superheated steam boiler, an electrically heated steam superheater, a gas turbine waste heat boiler, etc.

[0035] As used herein, the term "interstage steam device" includes an interstage steam conversion device and an interstage steam supply and demand device, which connect at least two annular steam networks, preferably annular steam networks that supply steam at different pressures, to form a cascaded annular steam network. The interstage steam device can be connected to the annular steam pipeline included in each of the at least two annular steam networks via two parallel branch pipes. The two parallel branch pipes serve as backup for each other. The interstage steam device can supply steam to and / or receive steam from the connected annular steam network via one or both of the two branch pipes. A first double block-and-relief valve group and a second double block-and-relief valve group are respectively provided on the two backup branch pipes, and a third double block-and-relief valve group is provided on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double block-and-relief valve group includes two block valves and a relief valve located between the two block valves.

[0036] In the context of the interstage steam device in the present invention, unless otherwise specified, the terms "(relatively / higher) high pressure" and "(relatively / lower) pressure" refer to the steam pressure at the connection between the interstage steam device and one annular steam network compared to the steam pressure at the connection between the interstage steam device and another annular steam network, or refer to the steam pressure at the inlet of the interstage steam device compared to the steam pressure at the outlet of the interstage steam device. For example, two annular steam networks with steam of different pressures are connected to each other through the interstage steam device, and the annular steam network connected thereto that supplies steam with higher pressure refers to the pressure relative to the connection between the interstage steam device and the other annular steam network. For example, the high / low pressure steam obtained / consumed by the interstage steam device is relative to the pressure of the steam output / generated by the interstage steam device, and vice versa.

[0037] As used herein, the term "interstage steam conversion device" refers to a device that consumes high-pressure steam and produces low-pressure steam, either through power generation or non-power generation, and is connected to at least two annular steam pipeline networks supplying steam at different pressures. Those skilled in the art will appreciate that the interstage steam conversion device can serve as a steam consumer for the annular steam pipeline network supplying steam at the higher pressure, and can also serve as a steam supplier for the annular steam pipeline network supplying steam at the lower pressure.

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

[0039] The term "double block and bleed valve assembly" used in the present 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 the present invention refers to a conventional turbine known in the art that can consume high-pressure steam and generate low-pressure steam by performing work through expansion.

[0041] The term "desuperheater and pressure reducer" used in the present invention refers to a commonly used desuperheater and pressure reducer known in the art, which can consume high-pressure steam and generate low-pressure steam by non-work methods such as throttling and water spraying. It can usually include valves such as pressure reducing valves or regulating valves and water spraying cooling devices and usually does not output shaft work to the outside.

[0042] Unless otherwise specified, the terms "(relatively / higher) high pressure steam" and "(relatively / higher) low pressure steam" used in the present invention refer to the steam pressures at the inlet and outlet of the same steam consuming device, steam supply device, interstage steam device, interstage steam conversion device, or interstage steam supply and demand device.

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

[0044] As used herein, the term "steam consuming device with a small pressure drop" means that the steam pressure to be supplied to the steam consuming device decreases by less than or equal to 2%, 5%, 10%, 15%, or 20% compared to the steam pressure provided by the nearest steam supply device. The steam consuming device with a small pressure drop can obtain steam through one of its two branch pipes, with the other branch pipe serving as a backup, thereby reducing energy loss during steam transportation.

[0045] As used herein, the term "steam consuming device with a large pressure drop" means that the steam pressure to be input to the steam consuming device is reduced by more than 20%, such as greater than or equal to 25%, 30%, 35%, 40%, or even greater, compared to the steam pressure provided by the nearest steam supply device. The steam consuming device with a large pressure drop may obtain steam through only one or both of its two mutually redundant branch pipes. In the system of the present invention, the pressure drop between the steam consuming device and the nearest steam supply device is dynamically variable.

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

[0047] The term "adjacent steam supply devices and / or steam consumption devices" used in the present invention means that there is no other steam supply device or steam consumption device 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 steam consumption device adjacent.

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

[0049] The system includes one or more annular steam pipe networks,

[0050] Wherein, each of the annular steam pipe networks comprises:

[0051] a) Annular steam pipeline for conveying steam,

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

[0053] c) multiple steam consumers,

[0054] Wherein, each of the steam supply device and the steam consumption device is connected to the annular steam pipeline through two branch pipes arranged in parallel, and the two branch pipes are standby for each other. A first double block-and-relief valve group and a second double block-and-relief valve group are respectively provided on the two branch pipes, and a third double block-and-relief valve group is provided on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double block-and-relief valve group includes two block valves and a relief valve located between the two block valves.

[0055] Wherein, a bidirectional flow meter is provided 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 present invention, the system may include multiple annular steam networks, wherein at least two annular steam networks supply steam having different pressures and are interconnected through an interstage steam device to form a cascade annular steam network. Preferably, the interstage steam device may include:

[0057] An interstage steam conversion device 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, which can obtain steam from one of the at least two annular steam pipe networks connected to it in one operating condition, and output steam to the other of the at least two annular steam pipe networks connected to it in another operating condition, especially output steam with higher or lower pressure.

[0059] In one embodiment of the present invention, the inter-stage steam conversion device may include a steam turbine and / or a desuperheater for consuming steam at a higher pressure to generate steam at a lower pressure.

[0060] In one embodiment of the present invention, the inter-stage steam supply and demand device may include a multi-mode production device, which consumes the obtained steam in a first mode and generates steam with a higher pressure or lower pressure than the obtained steam in a second mode.

[0061] In one embodiment of the present 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 drop of 2%, 5%, 10%, 15% or 20% relative to the steam pressure provided by the nearest steam supply device. The large pressure drop may be a pressure drop of more than 20%, such as greater than or equal to 25%, 30%, 35%, 40% or even greater relative to the steam pressure provided by the nearest steam supply device. Preferably, the steam consuming device with a large pressure drop can obtain steam through one or both of the two respective branches, while the steam consuming device with a small pressure drop can obtain steam only through one of the two respective branches, with the other serving as a backup. The two branches of each of the steam consuming devices are mutually backup.

[0062] In one embodiment of the present invention, the steam consuming device may include a steam consuming device with a large pressure drop relative to the nearest steam supply device, and the steam consuming device with a large pressure drop may obtain steam through one or both of the two branch pipes that are mutually redundant. The large pressure drop may be a pressure drop of more than 20% relative to the steam pressure provided 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 present invention, the steam consuming device may include a steam consuming device with a small pressure drop relative to the nearest steam supply device, and the steam consuming device with a small pressure drop may obtain steam through only one of its two branch pipes, with the other branch pipe serving as a backup. The small pressure drop may be a pressure drop of 2%, 5%, 10%, 15% or 20% relative to the steam pressure provided by the nearest steam supply device.

[0064] In one embodiment of the present 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 present invention, the steam may be superheated steam, and the system includes three or more annular steam pipe networks, wherein the superheated steam in the three annular steam pipe networks respectively 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.

[0066] In one embodiment of the present invention, each of the bidirectional flow meters is integrated with a low flow rate alarm, wherein when the steam flow rate detected by any one of the bidirectional flow meters is lower than the preset minimum allowable flow rate, a low flow rate alarm signal is triggered to indicate the low steam flow rate at the corresponding position of the annular steam network at this level where the corresponding bidirectional flow meter is located.

[0067] In one embodiment of the present invention, in each of the annular steam pipe 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 consuming devices is adjustable. Preferably, when the low flow rate alarm signal is triggered, the steam supply rate of the steam supply devices and / or the steam consumption rate of the steam consuming devices in the corresponding annular steam pipe network are adjusted to eliminate the low flow rate phenomenon.

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

[0069] In one embodiment of the present invention, Figure 1 As shown, a system 10 for supplying steam is provided, wherein the system comprises an annular steam pipe network 101, wherein the annular steam pipe network 101 comprises:

[0070] a) a ring-shaped steam pipeline 1011 for conveying steam,

[0071] b) two steam supply devices 1012a and 1012b, and

[0072] c) two steam consumers 1013a and 1013b,

[0073] wherein 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, the two branch pipes 1014a and 1014b being standby for each other, a first double block-and-relief valve group 1015a and a second double block-and-relief valve group 1015b being respectively provided on the two branch pipes 1014a and 1014b, and a third double block-and-relief valve group 1015c being provided 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 block-and-relief valve groups 1015a to 1015c including two block valves and a relief valve located between the two block valves;

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

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

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

[0077] Wherein, each of the annular steam pipe networks comprises:

[0078] a) a circular steam pipeline 2011, 2021 or 2031 for conveying steam,

[0079] b) a plurality of steam supply devices, and

[0080] c) multiple steam consumers,

[0081] Each of the steam supply device and the steam consumption device is connected to the annular steam pipeline via two parallel branch pipes, the two branch pipes serving as backup for each other, a first double block-and-relief valve group (not shown) and a second double block-and-relief valve group (not shown) are respectively provided on the two branch pipes, and a third double block-and-relief valve group (not shown) is provided on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline, each of the double block-and-relief valve groups including two block valves and a relief valve located between the two block valves;

[0082] Wherein, a bidirectional flow meter (not shown) is provided 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 present invention, Figure 3 As shown, the system 20 includes three annular steam pipe networks, namely, an annular steam pipe network 202 of the current stage, a higher-pressure annular steam pipe network 201 for supplying steam at a higher pressure than the annular steam pipe network 202 of the current stage, and a lower-pressure annular steam pipe network 203 for supplying steam at a lower pressure than the annular steam pipe network 202 of the current stage. The three annular steam pipe networks supply steam with different pressures, wherein the annular steam pipe network 202 of the current stage is connected to the higher-pressure annular steam pipe network 201 and the lower-pressure annular steam pipe network 203 through interstage steam conversion devices 2001a and 2002, respectively. The interstage steam conversion device 2001a is interconnected with the annular steam network 2001b, wherein the interstage steam conversion device 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 the same stage, serving as the steam supply device 2022 of the annular steam network 202 of the same stage, while the interstage steam conversion device 2001b obtains higher-pressure steam from the annular steam network 202 of the same stage and outputs lower-pressure steam to the lower-pressure annular steam network 203 of the same stage, serving as the steam consumption device 2023 of the annular steam network 202 of the same stage, thereby forming a cascade annular steam network. Preferably, the steam flux of the interstage steam conversion devices 2001a and 2001b is adjustable.

[0084] In a further embodiment, the inter-stage steam conversion devices 2001a and 2001b can be independently steam turbines or desuperheaters that consume higher-pressure steam to generate lower-pressure steam.

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

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

[0087] a) a circular steam pipeline 3011 or 3031 for conveying steam,

[0088] b) a plurality of steam supply devices (not shown), and

[0089] c) a plurality of steam consumers (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, the two branch pipes serving as backup for each other, a first double block-and-relief valve group (not shown) and a second double block-and-relief valve group (not shown) are respectively provided on the two branch pipes, and a third double block-and-relief valve group (not shown) is provided on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline, each of the double block-and-relief valve groups including two block valves and a relief valve located between the two block valves;

[0091] Wherein, a bidirectional flow meter (not shown) is provided 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.

[0092] In a further embodiment, Figure 4 As shown, the system includes a high-pressure annular steam network 301 for supplying steam at a higher pressure and a low-pressure annular steam network 303 for supplying steam at a lower pressure. The two annular steam networks supply steam with different pressures and are interconnected through an inter-stage steam supply and demand device 3002 to form a cascade annular steam network.

[0093] The inter-stage steam supply and demand device 3002 is only connected 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, and is only connected to the high-pressure annular steam network 301 in the second operating condition 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 embodiment, Figure 4As shown, the inter-stage steam supply and demand device 3002 comprises a multi- condition production device which consumes the obtained low-pressure steam in a first condition and produces high-pressure steam of higher pressure than the obtained low-pressure steam in a second condition.

[0095] According to another aspect of the present application, there is provided a method of stabilizing steam supply, characterized in that the method comprises providing the system of the present application to supply steam.

[0096] In one embodiment of the present application, each bi-directional flow meter can be integrated with a low flow alarm, and when a low flow alarm signal is triggered upon detecting a steam flow rate lower than a preset minimum allowable flow rate, the method further comprises:

[0097] by adjusting the steam supply amount and / or the steam consumption amount of the current stage ring-shaped steam pipe network corresponding to the low flow alarm signal until the steam flow rate detected by the corresponding bi-directional flow meter is not lower than the preset minimum allowable flow rate.

[0098] In one embodiment of the present application, the adjusting the steam supply amount of the current stage ring-shaped steam pipe network can comprise:

[0099] a) adjusting the steam supply amount of a steam supply device included in the current stage ring-shaped steam pipe network and being a steam boiler, and / or

[0100] b) adjusting the steam flux of an inter-stage steam conversion device connecting the current stage ring-shaped steam pipe network with a ring-shaped steam pipe network supplying steam of higher pressure, and / or

[0101] c) adjusting the steam output amount of an inter-stage steam supply and demand device outputting steam to the current stage ring-shaped steam pipe network.

[0102] In one embodiment of the present application, the adjusting the steam consumption amount of the current stage ring-shaped steam pipe network can comprise:

[0103] a) adjusting the steam consumption amount of an adjustable steam consumption device included in the current stage ring-shaped steam pipe network, and / or

[0104] b) adjusting the steam flux of an inter-stage steam conversion device connecting the current stage ring-shaped steam pipe network with a ring-shaped steam pipe network supplying steam of lower pressure, and / or

[0105] c) adjusting the steam acquisition amount of an inter-stage steam supply and demand device acquiring steam from the current stage ring-shaped steam pipe network.

[0106] In one embodiment of the present application, when the system is under pressureless maintenance or modification, the method can further comprise the following steps:

[0107] (1) Determine the site to be constructed, particularly the site to be constructed on the annular steam pipeline, and close all double block-and-release valve groups directly adjacent to the annular steam pipeline and the branch pipe to form an isolation area around the site;

[0108] (2) evacuate the steam from the isolation area until no steam is discharged from the discharge valves in all immediately adjacent double block-and-blow valve groups, and

[0109] (3) Carry out repairs or renovations at the site to be constructed;

[0110] During the maintenance or modification, the second or first double block-and-relief valve group serving as a backup for the closed first or second double block-and-relief valve group is in an open state.

[0111] In a further embodiment, in step (1) of the method, the site to be constructed is located on a ring steam pipeline, two third double block-and-relief valve groups, one first double block-and-relief valve group, and one second double block-and-relief valve group 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 block-and-relief valve group and the connection point with the annular steam pipeline, two third double block-and-relief valve groups, one first double block-and-relief valve group, and one second double block-and-relief 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 block-and-relief valve group and its corresponding device, only the first or second double block-and-relief valve group is closed.

[0114] In one embodiment of the present invention, a method for stably supplying steam is provided, characterized in that the method comprises providing Figure 2 The system 10 of the present invention is shown to supply steam, and

[0115] When the system 10 is repaired or modified without pressure, 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 the double block-and-relief valve groups directly adjacent to the annular steam pipeline 1011 and the branch pipes 1014a and 1014b to form an isolation area around the site. Here, directly adjacent means that there is no other double block-and-relief valve group between the double block-and-relief valve group and the construction site, that is, close the two third double block-and-relief valve groups 1015c-i and 1015c-ii, the first double block-and-relief valve group 1015a-ii, and the second double block-and-relief valve group 1015b-i directly adjacent to the site C;

[0117] (2) evacuate the steam from the isolation area until there is no steam being discharged from the discharge valves in all of the immediately adjacent double block-and-blow valve groups 1015c-i, 1015c-ii, 1015a-ii, and 1015b-i, and

[0118] (3) Repair or renovate the site C to be constructed;

[0119] During the maintenance or modification period, the second double block-and-relief valve group 1015b-ii and the first double block-and-relief valve group 1015a-i, which serve as backup for the closed first double block-and-relief valve group 1015a-ii and the second double block-and-relief valve group 1015b-i, are in an open state to ensure that the steam supply device 1012a and the steam consumption device 1013a normally supply and consume steam, respectively.

[0120] In one embodiment of the present invention, a method for stably supplying steam is provided, characterized in that the method comprises providing Figure 3 The system 20 of the present invention is shown for supplying steam, wherein the system 20 forms a cascaded annular 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 annular steam pipe network 202 of the current level is lower than a preset minimum allowable flow rate and a low flow rate alarm signal is triggered, the method further includes:

[0122] The steam supply and / or steam consumption of the annular steam pipe network 202 at this level corresponding to the low flow rate alarm signal is adjusted 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 annular steam pipe network 202 at this stage may include:

[0124] a) regulating the steam supply of the steam supply device (not shown) serving as a steam boiler included in the annular steam pipe network 202 at this level, and / or

[0125] b) regulating the steam flux of the inter-stage steam conversion device 2001a which connects the annular steam network 202 of the current stage to the higher-pressure annular steam network 201 supplying steam at a higher pressure.

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

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

[0128] b) regulating the steam flux of the inter-stage steam conversion device 2001b which connects the annular steam network 202 of the current stage with the lower pressure annular steam network 203 which 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 annular steam network 202 of this stage is not lower than the preset minimum allowable flow rate.

[0130] In one embodiment of the present invention, a method for stably supplying steam is provided, characterized in that the method comprises providing Figure 4 The system 30 of the present invention is shown for supplying steam, wherein the system 30 forms a cascaded annular 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 the steam flow rate detected in the high-pressure annular steam pipe network 301 is lower than a preset minimum allowable flow rate and a low flow rate alarm signal is triggered, the method further includes the following steps:

[0132] Adjust the steam output of the steam supply device 3012, which serves as the interstage steam supply and demand device 3002 and is connected to the high-pressure annular steam network 301, 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 the 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 the steam flow rate detected in the low-pressure annular steam pipe network 303 is lower than a preset minimum allowable flow rate and a low flow rate alarm signal is triggered, the method further includes the following steps:

[0134] Adjust the steam consumption of the steam consumption device 3033 connected to the low-pressure annular steam network 303 as the interstage steam supply and demand device 3002 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 the first operating condition.

[0135] It is understandable that for those skilled in the art, any equivalent replacement or change to the technical solution and inventive concept of the present invention should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A system for supplying steam, characterized in that The system includes one or more annular steam pipe networks, Wherein, each of the annular steam pipe networks comprises: a) Annular steam pipeline for transporting steam, b) one or more steam supply devices, and c) multiple steam consumers, Wherein, each of the steam supply device and the steam consumption device is connected to the annular steam pipeline through two branch pipes arranged in parallel, and the two branch pipes are standby for each other. A first double block-and-relief valve group and a second double block-and-relief valve group are respectively provided on the two branch pipes, and a third double block-and-relief valve group is provided on the annular steam pipeline between the connection points of the two branch pipes and the annular steam pipeline. Each double block-and-relief valve group includes two block valves and a relief valve located between the two block valves. Wherein, a bidirectional flow meter is provided 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.

2. The system according to claim 1, wherein: The system comprises a plurality of annular steam pipe networks, wherein at least two annular steam pipe networks supply steam with different pressures and are interconnected through an interstage steam device to form a cascade annular steam pipe network. The interstage steam device comprises: An interstage steam conversion device that obtains higher-pressure steam from a connected annular steam network supplying higher-pressure steam and outputs lower-pressure steam to a connected annular steam network supplying lower-pressure steam, and whose steam flux is adjustable, and / or An interstage steam supply and demand device obtains steam from one of the at least two annular steam pipe networks connected thereto in one operating condition, and outputs steam to the other of the at least two annular steam pipe networks connected thereto in another operating condition.

3. The system according to claim 2, characterized in that The inter-stage steam conversion device includes a steam turbine and / or a temperature and pressure reducer that consumes high-pressure steam to generate low-pressure steam.

4. The system according to claim 2, wherein: The inter-stage steam supply and demand device includes a multi-operating-mode production device, which consumes the obtained steam in a first operating mode and generates steam with a higher or lower pressure than the obtained steam in a second operating mode.

5. The system according to claim 1, wherein: The steam consuming devices include steam consuming devices with a small pressure drop of less than 20% and steam consuming devices with a large pressure drop of more than 20% relative to the nearest steam supply device, wherein, The steam consuming device with large pressure drop obtains steam through one or both of its two branch pipes, while the steam consuming device with small pressure drop obtains steam through only one of its two branch pipes, with the other one serving as a backup.

6. The system according to any one of claims 1 to 5, characterized in that The steam is superheated steam, and the system includes three or more annular steam pipe networks, wherein the superheated steam in the three annular steam pipe networks respectively 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.

7. The system according to any one of claims 1 to 5, characterized in that Each of the bidirectional flow meters is integrated with a low flow rate alarm, wherein when the steam flow rate detected by any one of the bidirectional flow meters is lower than the preset minimum allowable flow rate, a low flow rate alarm signal is triggered to indicate the low steam flow rate at the corresponding position of the annular steam network at this level where the corresponding bidirectional flow meter is located.

8. The system according to claim 7, characterized in that In each of the annular steam pipe networks, the steam supply amount of part or all of the steam supply devices is adjustable, and / or the steam consumption amount of part or all of the steam consumption devices is adjustable.

9. The system according to any one of claims 1 to 5, characterized in that The annular steam pipeline is provided with a reserved interface for subsequent expansion and access to additional steam supply devices and / or steam consumption devices.

10. A method for stable steam supply, characterized in that: The method comprises providing a system as claimed in any one of claims 1 to 9 for supplying steam.

11. The method according to claim 10, characterized in that Each bidirectional flow meter is integrated with a low flow rate alarm. When the detected steam flow rate is lower than the preset minimum allowable flow rate and a low flow rate alarm signal is triggered, the method further includes: By adjusting the steam supply and / or steam consumption of the annular steam network at this level corresponding to the low flow rate alarm signal, until the steam flow rate detected by the corresponding two-way flow meter is not lower than the preset minimum allowable flow rate.

12. The method according to claim 11, characterized in that The regulating the steam supply of the annular steam pipe network at this level includes: a) regulating the steam supply rate of the steam supply device serving as a steam boiler included in the annular steam pipe network at this level, and / or b) regulating the steam flux of the interstage steam conversion device as claimed in claim 2, which connects the annular steam network of the current stage with the annular steam network supplying steam at a higher pressure.

13. The method according to claim 11, characterized in that The regulating the steam consumption of the annular steam network at this level includes: a) regulating the steam consumption of the adjustable steam consuming devices included in the annular steam pipe network at this level, and / or b) regulating the steam flux of the interstage steam conversion device as claimed in claim 2, which connects the annular steam network of the current stage with the annular steam network supplying steam at a lower pressure.

14. The method according to any one of claims 10 to 13, characterized in that When the system is repaired or modified without pressure, the method further comprises the following steps: (1) Determine the location on the annular steam line to be constructed, and close all the double block-and-release valve groups directly adjacent to the annular steam line and the branch pipe to form an isolation area around the location, (2) exhausting the steam from the isolation area until all the relief valves in the immediately adjacent double block-and-relief valve groups are free of steam, and (3) Carry out repairs or renovations at the site to be constructed; During the maintenance or modification, the second or first double block-and-relief valve group serving as a backup for the closed first or second double block-and-relief valve group is in an open state.

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