System for improving steam supply stability of paper machine production line

Abstract

According to the system for improving the steam supply stability of the paper machine production line, the steam supply pipeline is additionally arranged between the steam extraction main pipe and the low-pressure pipeline on the basis of an existing air supply system of the paper machine production line, so that the problem that high-pressure steam cannot be stably supplied when a high-pressure double-pressure reducer breaks down can be effectively solved; and during the failure or maintenance period of the low-pressure steam turbine, the low-pressure steam turbine keeps running, and low-pressure steam can be provided for each production line of the paper machine through the steam supply pipeline, so that the high-pressure steam source and the low-pressure steam source of each production line of the paper machine are communicated, and the steam supply stability of the production line of the paper machine is improved.

Description

Technical Field

[0001] The utility model relates to the field of papermaking equipment, in particular to a system for improving the steam supply stability of a paper machine production line. Background Art

[0002] The papermaking production process requires various energy supplies, the most common of which are electricity and steam. The common energy supply method is to use boilers to generate steam and use steam turbines to generate electricity. Steam turbines convert thermal energy into mechanical energy through high-speed rotation and generate electricity through generators for power supply. Therefore, steam turbines are widely used in paper mills.

[0003] During the long-term papermaking production and operation, the applicant has continuously improved the steam supply system due to the early design defects, as shown in the attached Figure 1 As shown in the figure, after the No. 2 steam turbine is modified and put into operation, the exhaust steam of the No. 2 steam turbine can only supply low-pressure steam for each production line of the paper machine. The paper machine uses the No. 1 steam turbine and the No. 3 steam turbine in conjunction with the No. 1 desuperheater and pressure reducer as the high-pressure steam source. Since the cost of self-generation is higher than the cost of power supply from the external power grid, the generator sets of the No. 1 and No. 3 steam turbines are in a state of shutdown for a long time. The high-pressure steam supply of each production line of the paper machine can only be provided by the long-term single-line operation of the No. 1 desuperheater and pressure reducer. Once the No. 1 desuperheater and pressure reducer fails and stops operating, the paper machine production line will have no high-pressure steam available. Utility Model Content

[0004] To this end, it is necessary to provide a system to improve the stability of steam supply to the paper machine production line, so as to solve the problem that high-pressure steam can only be supplied by the No. 1 desuperheater and pressure reducer for a long time. Once the No. 1 desuperheater and pressure reducer fails and stops operating, the paper machine production line will have no high-pressure steam available.

[0005] To achieve the above-mentioned object, the utility model provides a system for improving the steam supply stability of a paper machine production line, comprising a main control device and a boiler, a low-pressure steam turbine, a high-pressure steam turbine, a low-pressure sub-cylinder, a high-pressure sub-cylinder, a low-pressure double reducer, and a high-pressure double reducer, each electrically connected to the main control device;

[0006] The steam outlet of the boiler is connected to the main steam main pipe, and a plurality of auxiliary steam outlet pipes are provided on the main steam main pipe and are respectively connected to the steam inlet of the low-pressure double reducer, the steam inlet of the high-pressure double reducer, the steam inlet of the low-pressure steam turbine and the steam inlet of the high-pressure steam turbine; the steam outlet of the low-pressure steam turbine is connected to the low-pressure sub-cylinder, and the steam outlet of the high-pressure steam turbine is connected to the high-pressure sub-cylinder through the steam extraction main pipe; the steam outlet of the low-pressure double reducer is connected to the low-pressure sub-cylinder through the low-pressure pipeline, and the steam outlet of the high-pressure double reducer is connected to the high-pressure sub-cylinder; the steam extraction main pipe is connected to the low-pressure pipeline through the steam supply pipeline.

[0007] Furthermore, an isolation valve is provided on the steam supply pipeline.

[0008] Furthermore, bypass valves are connected in parallel at both ends of the isolation valve.

[0009] Furthermore, a drain valve is provided at the inlet of the isolation valve, and the other end of the drain valve is connected to the cooling recovery pool.

[0010] Furthermore, the isolation valve is an electric isolation valve, a manual isolation valve or a vacuum isolation valve.

[0011] Furthermore, there are multiple boilers; and / or

[0012] There are at least two high-pressure steam turbines; and / or

[0013] There are at least two low-voltage double reducers.

[0014] Furthermore, the steam outlet end of the low-pressure sub-cylinder or the steam outlet end of the low-pressure sub-cylinder is respectively connected to a plurality of terminals.

[0015] Furthermore, it also includes a plurality of steam pressure monitors electrically connected to the main control device, and the plurality of steam pressure monitors are respectively arranged at the steam outlet end of the low-pressure double reducer, the steam outlet end of the high-pressure double reducer and the steam extraction main pipe.

[0016] Different from the existing technology, the above technical solution can effectively avoid the problem of inability to stably supply high-pressure steam when the high-pressure double reducer fails by adding a steam supply pipeline between the steam extraction main pipe and the low-pressure pipeline on the basis of the existing paper machine production line air supply system. In addition, during the failure or maintenance of the low-pressure steam turbine, the low-pressure steam turbine remains in operation and low-pressure steam can be provided to each paper machine production line through the steam supply pipeline, thereby realizing the interconnection of high-pressure steam sources and low-pressure steam sources of each paper machine production line and improving the steam supply stability of the paper machine production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a portion of the structure of the system described in the background art, in which the steam extraction main pipe and the low-pressure pipeline are not connected;

[0018] Figure 2 This is a partial structural diagram of the system provided with a steam supply pipeline and an isolation valve according to a specific embodiment;

[0019] Figure 3 This is a partial structural diagram of another specific embodiment of the system provided with a bypass valve;

[0020] Figure 4 A partial structural diagram of another embodiment of the system including a steam trap and a cooling recovery tank;

[0021] Figure 5 Schematic diagram of the structure of the system according to another specific embodiment.

[0022] Description of reference numerals:

[0023] 10. Boiler; 20. Low-pressure steam turbine; 21. High-pressure steam turbine; 30. Low-pressure steam distributor; 31. High-pressure steam distributor; 40. Low-pressure double reducer; 41. High-pressure double reducer; 50. Main steam manifold; 51. Extraction steam manifold; 52. Steam supply pipeline; 53. Low-pressure pipeline; 60. Isolation valve; 61. Bypass valve; 62. Steam trap; 63. Cooling recovery tank. DETAILED DESCRIPTION

[0024] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0025] References to "embodiments" herein mean that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the word "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the various technical features mentioned in the embodiments can be combined in any manner to form a corresponding implementable technical solution.

[0026] Unless otherwise defined, the technical terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0027] In the description of this application, the term "and / or" is used to describe a logical relationship between objects, indicating that three possible relationships exist. For example, A and / or B means: A exists, B exists, and both A and B exist. In addition, the character " / " in this document generally indicates that the objects before and after are in a logical "or" relationship.

[0028] In this application, terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual quantity, priority or sequence relationship between these entities or operations.

[0029] Without further limitations, in this application, the words "include", "comprise", "have" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those defined elements, but also other elements not explicitly listed, or elements inherent to such process, method or product.

[0030] Consistent with the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceed" are understood to exclude the number itself; expressions such as "above," "below," and "within" are understood to include the number itself. Furthermore, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this manner, such as "multiple groups," "multiple times," etc., unless otherwise specifically defined.

[0031] In the description of the embodiments of the present application, the space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, it should not be understood as a limitation on the embodiments of the present application.

[0032] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms "installed", "connected", "connected", "fixed", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art of the present application, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0033] See also Figures 1 to 5 This embodiment provides a system for improving the steam supply stability of a paper machine production line, including a main control device and a boiler 10, a low-pressure steam turbine 20, a high-pressure steam turbine 21, a low-pressure sub-cylinder 30, a high-pressure sub-cylinder 31, a low-pressure double reducer 40, and a high-pressure double reducer 41, which are electrically connected to the main control device respectively.

[0034] The boiler converts the chemical energy of the fuel into thermal energy, which is then transferred to the water in the boiler, turning the water into steam, thereby meeting various needs during paper production. Specifically, the boiler generates thermal energy by burning fuel, which is transferred to the water, evaporating it into steam. Steam has various uses in the papermaking process, such as processing and shaping paper and concentrating black pulp. The boiler type can be selected based on the production scale of the production line. Specifically, oil-fired and gas-fired boilers can be used, which have high thermal efficiency, high combustion efficiency, clean and pollutant-free properties, making them suitable for small-scale production. Chain grate boilers offer low energy consumption, complete combustion, high efficiency, and clean, pollution-free properties, making them suitable for medium- and large-scale production. Circulating fluidized bed boilers offer high combustion efficiency, excellent desulfurization performance, a wide range of coal types, and low operating costs, making them suitable for medium- and large-scale production. Biomass boilers utilize biomass as fuel, meeting paper production needs while reducing environmental pollution, making them suitable for medium- and large-scale production. Preferably, there are multiple boilers, and the specific number can be set according to the steam demand. Each boiler is connected to the main steam pipe through a transmission pipeline. Redundant steam supply is achieved through multiple boilers, ensuring sufficient steam supply and improving stability.

[0035] The low-pressure steam turbine is used to produce steam with the same temperature and pressure as the steam produced by the low-pressure double reducer, and is transported to the low-pressure sub-cylinder through a pipeline. Similarly, the high-pressure steam turbine is used to produce steam with the same temperature and pressure as the steam produced by the high-pressure double reducer, and is transported to the high-pressure sub-cylinder through an extraction main pipe. The low-pressure steam turbine and the high-pressure steam turbine can be of the same or different models. By adjusting and controlling the excess steam pressure generated by them or combining multiple low-pressure steam turbines to form a high-pressure steam turbine, the steam outlets of the low-pressure steam turbine and the high-pressure steam turbine are connected to the low-pressure sub-cylinder and the high-pressure sub-cylinder respectively, so as to achieve the purpose of reusing the steam surplus of the steam turbine. The steam input ends of the low-pressure steam turbine and the high-pressure steam turbine are respectively connected to the main steam main pipe. After the steam generated by the boiler is uniformly input into the main steam main pipe, it is transported to the low-pressure steam turbine or the high-pressure steam turbine respectively by the main steam main pipe. Preferably, there are at least two high-pressure steam turbines, and the excess steam from these multiple high-pressure steam turbines is delivered to the steam extraction main, thereby stably generating steam at the same temperature and pressure as the steam produced by the high-pressure double reducer, thereby supplementing the high-pressure steam cylinders and improving energy utilization. Both the high-pressure and low-pressure steam turbines can utilize existing conventional steam-driven turbines.

[0036] The high-pressure sub-cylinder and the low-pressure sub-cylinder are used to accommodate high-pressure steam and low-pressure steam, respectively. The sub-cylinder is used to distribute the steam generated during the operation of the boiler and the steam turbine to various pipelines. It is a pressure-bearing container, and the specific structure can refer to the sub-cylinder in the prior art. In this new model, the high-pressure sub-cylinder is connected to the high-pressure steam turbine and the main steam manifold, respectively, and the low-pressure sub-cylinder is connected to the low-pressure steam turbine and the main steam manifold, respectively. In some instances, the steam outlet end of the low-pressure sub-cylinder or the steam outlet end of the low-pressure sub-cylinder is connected to multiple terminals, respectively. The terminal refers to each steam-using equipment or device located at the rear end of the low-pressure sub-cylinder or the high-pressure sub-cylinder.

[0037] To ensure that the steam delivered from the main steam main to the high-pressure and low-pressure sub-cylinders meets the temperature and pressure requirements of the terminal equipment, a high-pressure double reducer and a low-pressure double reducer must be installed between the main steam main and the high-pressure sub-cylinder, and between the main steam main and the low-pressure sub-cylinder, respectively. Both the high-pressure double reducer and the low-pressure double reducer are temperature and pressure reducers. The difference between the two is that the high-pressure double reducer is installed between the main steam main and the high-pressure sub-cylinder. The steam that is reduced in temperature and pressure by the high-pressure double reducer meets the steam demand of the high-pressure sub-cylinder's rear-end terminal. Similarly, the low-pressure double reducer is installed between the main steam main and the low-pressure sub-cylinder. The steam that is reduced in temperature and pressure by the low-pressure double reducer meets the steam demand of the low-pressure sub-cylinder's rear-end terminal. To reduce learning and maintenance costs, the same model of temperature and pressure reducer can also be used. In some embodiments, the low-pressure double reducer can be configured as at least two temperature and pressure reducers, achieving the effect of producing low-pressure steam through two stages of temperature and pressure reduction, while the high-pressure double reducer only needs to be configured with a single temperature and pressure reducer. The temperature and pressure reducer can be integrated or split.

[0038] The main control device can be a PLC controller or PC, and can control the system by loading existing control software. This new technology achieves its technical effect solely through structural improvements and does not involve software improvements. It should be noted that the specific connection structure of the main control device is not shown in the accompanying drawings; reference should be made to existing conventional settings.

[0039] The steam outlet of the boiler is connected to the main steam main pipe 50, and a plurality of auxiliary steam outlets are provided on the main steam main pipe and are respectively connected to the steam inlet of the low-pressure double reducer, the steam inlet of the high-pressure double reducer, the steam inlet of the low-pressure steam turbine and the steam inlet of the high-pressure steam turbine; the steam outlet of the low-pressure steam turbine is connected to the low-pressure sub-cylinder, and the steam outlet of the high-pressure steam turbine is connected to the high-pressure sub-cylinder through the steam extraction main pipe 51; the steam outlet of the low-pressure double reducer is connected to the low-pressure sub-cylinder through the low-pressure pipeline 53, and the steam outlet of the high-pressure double reducer is connected to the high-pressure sub-cylinder; the steam extraction main pipe is connected to the low-pressure pipeline through the steam supply pipeline 52.

[0040] It should be noted that the drawings mainly show the connection relationship and some valve settings, and the necessary valves or other conventional pipe fittings in other positions are not shown one by one. They can be set according to needs with reference to the existing technology.

[0041] This new model adds a steam supply pipeline between the steam extraction main pipe and the low-pressure pipeline on the basis of the existing paper machine production line air supply system, which can effectively avoid the problem of unstable supply of high-pressure steam when the high-pressure double reducer fails. During the failure or maintenance of the low-pressure steam turbine, the low-pressure steam turbine remains in operation, and low-pressure steam can also be provided to each paper machine production line through the steam supply pipeline, thereby realizing the interconnection of high-pressure steam source and low-pressure steam source of each paper machine production line, and improving the steam supply stability of the paper machine production line.

[0042] Furthermore, an isolation valve 60 is provided on the steam supply pipeline. The isolation valve can adopt a gas-liquid linked wedge-shaped double-disc gate valve, including a drive head, a main body and a hydraulic system. The valve is driven to open and maintain the open state by the hydraulic system. When it needs to be closed, the hydraulic pressure at the bottom of the piston flows out, and the high-pressure nitrogen at the top closes the valve. The fast closing time is 2 to 5 seconds, and the slow closing time is 3 minutes. The isolation valve model can be Q641F-16P, Q647H / Y or Q941H-16C / 25, etc. By setting the isolation valve, the activation or closure of the steam supply pipeline can be flexibly controlled. It should be noted that the isolation valve can be controlled individually, or it can be electrically connected to the main control device and controlled by the main control device.

[0043] Furthermore, bypass valves 61 are connected in parallel at both ends of the isolation valve. The bypass valves enable pipe warm-up, hydrostatic testing, tightness isolation, engine warm-up during cold start, and pressure balancing on both sides when the automatic main steam valve is open. The bypass valves can be flanged or welded, and can be driven manually or electrically. Models include Z41H-16C, CS41H-16C, or Z941Y. The isolation valves can be electric, manual, or vacuum.

[0044] Furthermore, a steam trap 62 is installed at the inlet of the isolation valve, the other end of which is connected to a cooling recovery tank 63. The primary function of the isolation valve is to automatically remove steam condensate and non-condensable gases such as air from heating equipment or steam pipes, ensuring the normal operation of the steam system. If condensate is not promptly removed, it will accumulate in pipes and equipment, affecting the normal flow of steam and the thermal efficiency of the equipment. Collecting the condensate discharged from the steam trap in the cooling recovery tank can achieve water recycling, reduce water waste, and lower operating costs.

[0045] Furthermore, the system includes multiple steam pressure monitors, each electrically connected to the main control unit. These monitors are located at the steam outlet of the low-pressure double reducer, the steam outlet of the high-pressure double reducer, and the steam extraction main pipe. These steam pressure monitors monitor steam pressure at various points in real time, thereby determining whether equipment is malfunctioning and whether steam supply is normal, thereby improving steam supply stability.

[0046] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present utility model. Therefore, based on the innovative concept of the present utility model, changes and modifications to the embodiments described herein, or equivalent structural or process transformations made using the contents of the present utility model specification and drawings, and direct or indirect application of the above technical solutions to other related technical fields are all included in the scope of protection of the present utility model patent.

Claims

1. A system for improving steam supply stability in a paper machine production line, characterized by: It includes a main control device and a boiler, a low-pressure steam turbine, a high-pressure steam turbine, a low-pressure sub-cylinder, a high-pressure sub-cylinder, a low-pressure double reducer, and a high-pressure double reducer, which are electrically connected to the main control device respectively; The steam outlet of the boiler is connected to the main steam header, which is provided with a plurality of auxiliary steam outlets and respectively connected to the steam inlet of the low-pressure double reducer, the steam inlet of the high-pressure double reducer, the steam inlet of the low-pressure steam turbine, and the steam inlet of the high-pressure steam turbine; the steam outlet of the low-pressure steam turbine is connected to the low-pressure sub-cylinder, and the steam outlet of the high-pressure steam turbine is connected to the high-pressure sub-cylinder via a steam extraction header; The steam outlet end of the low-pressure double reducer is connected to the low-pressure sub-cylinder through a low-pressure pipeline, and the steam outlet end of the high-pressure double reducer is connected to the high-pressure sub-cylinder; the steam extraction main pipe is connected to the low-pressure pipeline through a steam supply pipeline.

2. The system for improving steam supply stability of a paper machine production line according to claim 1, characterized in that: An isolation valve is provided on the steam supply pipeline.

3. The system for improving steam supply stability of a paper machine production line according to claim 2, characterized in that: Bypass valves are connected in parallel at both ends of the isolation valve.

4. The system for improving steam supply stability of a paper machine production line according to claim 2, characterized in that: A drain valve is provided at the inlet of the isolation valve, and the other end of the drain valve is connected to the cooling recovery pool.

5. The system for improving steam supply stability of a paper machine production line according to claim 2, characterized in that: The isolation valve is an electric isolation valve, a manual isolation valve or a vacuum isolation valve.

6. The system for improving steam supply stability of a paper machine production line according to claim 1, characterized in that: There are multiple boilers; and / or There are at least two high-pressure steam turbines; and / or There are at least two low-voltage double reducers.

7. The system for improving steam supply stability of a paper machine production line according to claim 1, characterized in that: The steam outlet end of the low-pressure sub-cylinder or the steam outlet end of the low-pressure sub-cylinder is respectively connected to a plurality of terminals.

8. The system for improving steam supply stability of a paper machine production line according to claim 1, characterized in that: It also includes a plurality of steam pressure monitors electrically connected to the main control device, and the plurality of steam pressure monitors are respectively arranged at the steam outlet end of the low-pressure double reducer, the steam outlet end of the high-pressure double reducer and the steam extraction main pipe.

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