System for improving on-load performance of steam drum boiler coal power unit

Abstract

The utility model discloses a system for improving the on-load performance of a steam drum boiler coal generator set. The system comprises a communicating pipe and a regulating valve arranged on the communicating pipe. The communicating pipe is communicated with the upper header and the ceiling distribution header, and an outlet of the ceiling distribution header is connected with the superheater. A direct-flow steam generation system and a bypass steam pocket are arranged between an upper header and a ceiling distribution header of a steam pocket furnace, part of steam-water mixture in the upper header directly enters the ceiling distribution header without passing through the steam pocket, so that a steam mode is changed into direct-flow steam generation from circulating steam generation, and steam output by the ceiling distribution header is heated through a superheater; the main steam quantity can be rapidly increased, the problem that in the prior art, a steam drum boiler can only adjust the main steam quantity through combustion, the lag attribute exists, and consequently the steam drum boiler cannot supplement steam consumption in time is solved, and the on-load performance of a steam drum boiler unit is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal-fired power generation units, and particularly relates to a system for improving the load-carrying performance of coal-fired power generation units with a steam drum boiler. Background Art

[0002] The statements here only provide the background art related to the utility model, and do not necessarily constitute the prior art.

[0003] With the continuous increase in the consumption of renewable energy in the new power system, the pressure on grid stability is increasing. There is an urgent need for coal-fired power generation units to improve their auxiliary service capabilities such as rapid load change. Units with poor auxiliary service capabilities will find it difficult to survive and develop in the increasingly fierce market.

[0004] The inventor found that there is still a large stock of coal-fired power generation units with steam drum boilers. Compared with supercritical units, their energy consumption and economy are in a disadvantaged position, and there is a strong need to improve their load change performance (especially the load-carrying performance). From the current situation of the AGC (Automatic Generation Control) function response, it is very difficult for steam drum boiler units to meet the national standard requirement of 1.5% Pe (rated load) / min load-carrying performance within 15 minutes. The main reason is that the heat storage in the steam drum is large, and the inertial lag of the boiler in carrying load is much higher than that of supercritical units without a steam drum and downcomers: from adding coal to the change of the main steam pressure in a steam drum boiler, the lag time is about 5 minutes. Therefore, solving the problem that the steam drum boiler cannot replenish steam consumption in time due to its lag property is the key to improving the load-carrying performance of the unit. Summary of the Utility Model

[0005] The purpose of the utility model is to overcome the above-mentioned deficiencies in the prior art, and provide a system for improving the load-carrying performance of coal-fired power generation units with a steam drum boiler. By adding an adjustable DC steam generation system to the steam drum boiler, the problem that the steam drum boiler cannot replenish steam consumption in time can be solved, and the load-carrying performance of the steam drum boiler unit can be improved.

[0006] To achieve the above purpose, the utility model is realized by the following technical solutions:

[0007] A system for improving the load-carrying performance of coal-fired power generation units with a steam drum boiler includes a connecting pipe and a regulating valve arranged on the connecting pipe; the connecting pipe connects the upper header and the ceiling distribution header, so that part of the steam-water mixture in the upper header directly enters the ceiling distribution header through the connecting pipe without passing through the steam drum; the outlet of the ceiling distribution header is connected to the superheater; the ceiling distribution header is connected to the steam drum through a saturated steam pipe, and the upper header is connected to the steam drum through a riser pipe.

[0008] Further, one end of the connecting pipe is connected to the second steam-water mixture outlet of the upper header, and the other end is connected to the second steam-water mixture inlet of the ceiling distribution header.

[0009] Further, the capacity of the connecting pipe is designed according to 5% of the rated evaporation capacity of the boiler.

[0010] Further, the regulating valve adjusts the flow rate of the steam-water mixture flowing through the connecting pipe according to the steam increment corresponding to the required load increase rate.

[0011] Further, a flow meter is also provided on the connecting pipe for monitoring the flow rate of the steam-water mixture flowing through the connecting pipe.

[0012] Further, at least one saturated steam outlet is provided at the top of the steam drum; one end of the saturated steam outlet is connected to one end of the saturated steam delivery pipe, and the other end of the saturated steam delivery pipe is connected to the saturated steam inlet of the ceiling distribution header.

[0013] Further, at least one first steam-water mixture inlet is provided in the middle of the steam drum; one end of the first steam-water mixture inlet is connected to one end of the riser pipe, and the other end of the riser pipe is connected to the first steam-water mixture outlet of the upper header.

[0014] Further, a circulating water outlet is also provided at the bottom of the steam drum; one end of the circulating water outlet is connected to one end of the downcomer pipe, and the other end of the downcomer pipe is connected to the circulating water inlet of the lower header.

[0015] Further, the lower header is provided with at least one lower header outlet, which is connected to the water wall inlet through a delivery pipeline, and the water wall outlet is connected to the upper header inlet.

[0016] Further, the regulating valve is in a closed state during the stable operation of the unit;

[0017] The regulating valve opens when the unit receives an AGC load signal and the main steam pressure drops to the set value.

[0018] The beneficial effects of the technical solution of the present utility model are as follows:

[0019] 1) By providing a connecting pipe between the upper header of the steam drum boiler and the ceiling distribution header and a regulating valve on the connecting pipe, bypassing the steam drum, a part of the steam-water mixture in the upper header directly enters the ceiling distribution header without passing through the steam drum, so that the steam generation method changes from cyclic steam generation to direct steam generation. Then, the superheater heats the steam output from the ceiling distribution header, which can quickly increase the main steam flow rate, solves the problem in the prior art that the steam drum boiler can only adjust the main steam flow rate by combustion with a lag property, resulting in the steam drum boiler being unable to timely supplement the steam consumption, and improves the load-carrying performance of the steam drum boiler unit.

[0020] 2) A regulating valve and a flowmeter with adjustable flow rate are provided on the connecting pipe between the ceiling distribution header and the upper header of the present utility model. By controlling the opening speed and opening degree of the regulating valve, a load ramping performance of about 5% Pe / min can be obtained, and a significant increase in the load rate of the drum boiler can be achieved.

[0021] 3) When the drum boiler coal-fired power unit quickly takes on load, due to the lag property of the boiler, the main steam pressure drops significantly. At this time, the "pressure pull-back" function of the coordinated control system will be triggered, which prevents the main steam pressure from further dropping by closing the main steam valve. This causes reverse regulation and affects the AGC qualification rate of the drum boiler coal-fired power unit. In this embodiment, an adjustable DC steam generation system is added to the drum boiler to achieve rapid DC steam generation, so that the main steam flow rate increases rapidly, the deviation of the main steam pressure drop can be eliminated in time, the triggering of the "pressure pull-back" function can be avoided, and the problem that the reverse regulation of the main steam valve affects the AGC qualification rate of the unit can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The schematic diagrams forming a part of the present utility model are used to provide a further understanding of the present utility model. The illustrative embodiments and descriptions thereof of the present utility model are used to explain the present utility model and do not constitute an improper limitation of the present utility model.

[0023] Figure 1 is a schematic diagram of the system according to one or more embodiments of the present utility model;

[0024] In the figure: 1. Drum; 1-1. Saturated steam outlet; 1-2. First steam-water mixture inlet; 1-3. Circulating water outlet; 2. Ceiling distribution header; 2-1. Saturated steam inlet; 2-2. Second steam-water mixture inlet; 3. Upper header; 3-1. First steam-water mixture outlet; 3-2. Second steam-water mixture outlet; 3-3. Upper header inlet; 4. Lower header; 4-1. Circulating water inlet; 4-2. Lower header outlet; 5. Superheater; 6. Saturated steam pipe; 7. Rising pipe; 8. Downcomer; 9. Water wall; 10. Connecting pipe; 11. Regulating valve; 12. Flowmeter.

[0025] The distances or dimensions between each part are exaggerated for showing the positions of each part, and the schematic diagram is only for illustration. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present utility model. Unless otherwise specified, all technical and scientific terms used in the present utility model have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present utility model belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present utility model. As used herein, unless the present utility model clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or their combinations;

[0028] For the convenience of description, if the words "upper", "lower", "left", and "right" appear in the present utility model, they only indicate the same directions as the upper, lower, left, and right directions of the accompanying drawings themselves, and do not limit the structure. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present utility model.

[0029] Term explanation part: Terms such as "installation", "connection", "connection", and "fixation" in the present utility model should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection, it can be a direct connection, or an indirect connection through an intermediate medium, it can be an internal connection between two components, or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] The steam generation mechanism of a drum boiler is to generate steam in a certain circulation ratio. The ratio of the furnace water circulation volume to the steam output of the drum is the circulation ratio. The circulation ratio of a subcritical furnace is 4 - 6, indicating that the unit furnace water volume needs to circulate 4 - 6 times to be completely vaporized. In fact, due to the heat storage of the drum and the functions of steam - water separation and steam cleaning, the saturated steam volume led out of the drum is reduced by 20% - 25% compared with the steam content of the steam - water mixture entering the drum. If part of the steam - water mixture is directly led to the steam outlet of the drum without passing through the drum, the steam generation changes from cyclic steam generation to once - through steam generation; and then through superheater heating, the main steam volume can be quickly increased, which can solve the problem that the drum boiler cannot timely supplement steam consumption and improve the load - carrying performance of the drum boiler unit.

[0031] Embodiment 1

[0032] As Figure 1As shown in the figure, this embodiment discloses a system for improving the load-carrying performance of a coal-fired generator unit with a steam drum boiler, which includes a connecting pipe 10 and a regulating valve 11 provided on the connecting pipe 10. The connecting pipe 10 connects the upper header 3 and the ceiling distribution header 2. One end of it is connected to the second steam-water mixture outlet 3-2 of the upper header 3, and the other end is connected to the second steam-water mixture inlet 2-2 of the ceiling distribution header 2. It can enable some of the steam-water mixture in the upper header 2 to directly enter the ceiling distribution header 2 through the connecting pipe 10 without passing through the steam drum, realizing bypassing the steam drum, and changing the steam generation method from cyclic steam generation to once-through steam generation. The regulating valve 11 can adjust the flow rate of the steam-water mixture flowing through the connecting pipe 10. The outlet of the ceiling distribution header 2 is connected to the superheater 5, and the superheater 5 heats the steam output from the ceiling distribution header 2 to rapidly increase the main steam flow rate, which can solve the problem that the steam drum boiler cannot timely supplement steam consumption and improve the load-carrying performance of the steam drum boiler unit.

[0033] The above-mentioned connecting pipe 10, regulating valve 11, ceiling distribution header 2, upper header 3 and superheater 5 together form a system capable of once-through steam generation. When once-through steam generation is required, the regulating valve 11 is opened, and some of the steam-water mixture in the upper header 3 enters the ceiling distribution header 2 through the connecting pipe 10, and then is output from the ceiling distribution header 2 to the superheater 5 for heating to rapidly increase the main steam flow rate.

[0034] The capacity of the connecting pipe 10 can be designed according to 5% of the rated evaporation capacity of the boiler, which is achieved by controlling the pipe diameter of the connecting pipe. The regulating valve 11 adjusts the flow rate of the steam-water mixture flowing through the connecting pipe 10 according to the steam increment corresponding to the required load increase rate. A flow meter 12 is also provided on the connecting pipe 10 to monitor the flow rate of the steam-water mixture flowing through the connecting pipe 10.

[0035] The ceiling distribution header 2 is connected to the steam drum 1 through a saturated steam pipe 6, and the upper header 3 is connected to the steam drum 1 through a riser 7. Specifically:

[0036] At least one saturated steam outlet 1-1 is provided at the top of the steam drum 1 for leading out the saturated steam in the steam drum 1. The saturated steam outlet 1-1 is connected to one end of the saturated steam delivery pipe 6, and the other end of the saturated steam delivery pipe 6 is connected to the saturated steam inlet 2-1 of the ceiling distribution header 2, which can enable the saturated steam generated in the steam drum 1 to enter the ceiling distribution header 2 through the saturated steam outlet 1-1 via the saturated steam delivery pipe 6.

[0037] At least one first steam-water mixture inlet 1-2 is provided in the middle of the steam drum 1 for introducing the steam-water mixture into the steam drum. The first steam-water mixture inlet 1-2 is connected to one end of the riser 7, and the other end of the riser 7 is connected to the first steam-water mixture outlet 3-1 of the upper header 3, enabling the steam-water mixture in the upper header 3 to enter the steam drum 1 through the first steam-water mixture outlet 3-1 via the riser 7 for the steam-water separation process.

[0038] A circulating water outlet 1-3 is also provided at the bottom of the steam drum 1 for leading the water in the steam drum 1 out of the steam drum 1 for circulation. The circulating water outlet 1-3 is connected to one end of the downcomer 8, and the other end of the downcomer 8 is connected to the circulating water inlet 4-1 of the lower header 4, enabling the water in the steam drum 1 to enter the lower header 4 through the circulating water outlet 1-3 via the downcomer 8.

[0039] The lower header 4 is provided with at least one lower header outlet 4-2, which is connected to the inlet of the water wall 9 through a conveying pipeline, and the outlet of the water wall is connected to the inlet 3-3 of the upper header, enabling the supplement of the steam-water mixture in the upper header 3.

[0040] The working principle of a system for improving the load-carrying performance of a steam drum boiler coal-fired power unit disclosed in this embodiment is as follows:

[0041] When the steam drum boiler coal-fired power unit operates stably, the flow regulating valve 11 on the connecting pipe 10 is in the closed state. At this time, the upper header 3 and the ceiling distribution header 2 are not connected, and the steam generation mode of the steam drum boiler is cyclic steam generation.

[0042] When the steam drum boiler coal-fired power unit receives the AGC load-carrying signal and the main steam pressure drops by 0.1 MPa (this value can be adjusted and is between 0 and the trigger value of the "pressure pull-back" function of the coordinated control system), the regulating valve 11 on the connecting pipe 10 adjusts the flow rate of the steam-water mixture flowing from the upper header 3 through the connecting pipe 10 into the ceiling distribution header 2 corresponding to the steam increment of 1.5% Pe / min (set according to the required load increase rate). At this time, part of the steam-water mixture in the upper header 3 directly enters the ceiling distribution header 2 through the connecting pipe 10 without passing through the steam drum 1, realizing bypassing the steam drum. At this time, the steam generation mode changes from cyclic steam generation to once-through steam generation. Then, the superheater 5 heats the steam output from the ceiling distribution header to achieve a rapid increase in the main steam flow, which can solve the problem that the steam drum boiler cannot timely supplement the steam consumption due to the lag property of adjusting the main steam flow through combustion, and improve the load-carrying performance of the steam drum boiler unit.

[0043] When the regulating valve 11 on the connecting pipe 10 is opened for 5 min (set according to the boiler lag time) and the main steam pressure returns to the set value, the regulating valve 11 is slowly closed at a certain rate, the once-through steam generation mode exits, and all the steam-water mixture in the upper header 3 enters the steam drum 1 through the riser 7 for the steam-water separation process, and the steam generation changes from once-through steam generation back to circulating steam generation.

[0044] When the coal-fired motor unit of the steam drum boiler quickly takes on load, due to the lag property of the boiler, the main steam pressure drops significantly. At this time, the "pressure pull-back" function of the coordinated control system will be triggered. It prevents the further drop of the main steam pressure by closing the main steam valve, which causes reverse regulation and affects the AGC qualification rate of the coal-fired motor unit of the steam drum boiler. In this embodiment, by adding an adjustable once-through steam generation system to the steam drum boiler, rapid once-through steam generation is realized, so that the main steam flow rate increases rapidly, the deviation of the drop in the main steam pressure can be eliminated in time, the trigger of the "pressure pull-back" function can be avoided, and the problem that the reverse regulation of the main steam valve affects the AGC qualification rate of the unit can be avoided.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A system for improving the load performance of drum boiler coal-fired power units, characterized in that: It comprises a connecting pipe and a regulating valve arranged on the connecting pipe; the connecting pipe connects the upper header and the ceiling distribution header, so that part of the steam-water mixture in the upper header enters the ceiling distribution header directly through the connecting pipe without passing through the steam drum; the outlet of the ceiling distribution header is connected to the superheater; the ceiling distribution header is connected to the steam drum through a saturated steam pipe, and the upper header is connected to the steam drum through a riser.

2. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: One end of the connecting pipe is connected to the second steam-water mixture outlet of the upper header, and the other end is connected to the second steam-water mixture inlet of the ceiling distribution header.

3. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: The capacity of the connecting pipe is designed according to 5% of the rated evaporation capacity of the boiler.

4. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: The regulating valve adjusts the flow rate of the steam-water mixture flowing through the connecting pipe according to the steam increment corresponding to the required load increase rate.

5. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: A flow meter is also provided on the connecting pipe to monitor the flow of the steam-water mixture flowing through the connecting pipe.

6. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: At least one saturated steam outlet is provided on the top of the steam drum; the saturated steam outlet is connected to one end of a saturated steam delivery pipe, and the other end of the saturated steam delivery pipe is connected to the saturated steam inlet of the ceiling distribution header.

7. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: At least one first steam-water mixture inlet is arranged in the middle of the steam drum; the first steam-water mixture inlet is connected to one end of the riser, and the other end of the riser is connected to the first steam-water mixture outlet of the upper header.

8. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: A circulating water outlet is also provided at the bottom of the drum; the circulating water outlet is connected to one end of the downcomer, and the other end of the downcomer is connected to the circulating water inlet of the lower header.

9. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 8, characterized in that: The lower header is provided with at least one lower header outlet, which is connected to the water-cooled wall inlet through a conveying pipeline, and the water-cooled wall outlet is connected to the upper header inlet.

10. A system for improving the load performance of drum boiler coal-fired power units as claimed in claim 1, characterized in that: The regulating valve is in a closed state when the unit is running stably; The regulating valve opens when the unit receives an AGC load signal and the main steam pressure drops to a set value.

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