Deep peak regulation device for coal power unit and operation method

Abstract

The invention discloses a deep peak shaving device for a coal power unit and an operation method.The deep peak shaving device comprises the coal power unit, a high-pressure bypass and a low-pressure bypass, the coal power unit comprises a boiler, a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder, and a superheater outlet of the boiler is connected with a steam inlet of the high-pressure cylinder through a main steam pipeline; the main steam pipeline is communicated with a heat control system, a temperature and pressure reducer system is arranged on the main steam pipeline, a plurality of branch steam pipelines are arranged on the main steam pipeline on one side of the temperature and pressure reducer system, and a first stop valve and a first electric valve are arranged on each branch steam pipeline. The branch steam pipelines are connected with the heat control system, and a plurality of drainage pipelines are arranged on the main steam pipeline on the other side of the temperature and pressure reducer. According to the invention, the cost investment is greatly reduced, the main steam heat supply transformation is realized while the deep peak regulation operation transformation of the lowest rated load is realized, and the external heat supply capability is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of peak regulation of coal-fired power generation units, and in particular to a deep peak regulation device for coal-fired power generation units and an operating method thereof. Background Art

[0002] It is known that the flexibility transformation of coal-fired power units is the main measure to improve the regulation capacity of the power system, and it is also one of the key supports for promoting the large-scale and high-proportion development of new energy. In February 2024, the National Development and Reform Commission and the National Energy Administration issued the relevant "Guiding Opinions on Strengthening the Construction of Power Grid Peak-shaving Energy Storage and Intelligent Dispatching Capabilities", proposing to carry out in-depth flexibility transformation of coal-fired power units, and to achieve "all changes should be made" in the existing coal-fired power units by 2027. In areas where the proportion of new energy is high and the peak-shaving capacity is insufficient, explore deep peak-shaving of coal-fired power units on the premise of ensuring safety, and the minimum power generation output reaches 30% below the rated load.

[0003] According to statistics, Jiangsu currently has 125 coal-fired power units with a total installed capacity of 72.64 million kilowatts that have deep peak-shaving capabilities, with an average deep peak-shaving capacity of 31.4% and a total deep peak-shaving capacity of 13.48 million kilowatts, both of which are among the highest in the country. In February 2024, the "Supplementary Technical Specifications for Deep Peak-shaving of Coal-fired Power Generation Units in Jiangsu Power Grid" was issued, which clarified more detailed requirements for the recognition of deep peak-shaving capabilities of coal-fired units below 30% of rated load. At the same time, as the power auxiliary service market has formed a deep peak-shaving, the deeper the depth, the higher the price, so the enthusiasm of power generation companies to participate in peak-shaving has been fully mobilized.

[0004] At present, deep peak-shaving operation of coal-fired units is mainly achieved through boiler-side modifications, including full-load denitrification modification, combustion system modification, hydraulic system optimization, air preheater anti-blocking modification and control part optimization. On the one hand, the cost of boiler-side modification is relatively high, and the modification cost of 300 megawatt (MW) level units is generally more than 20 million yuan. On the other hand, when the operation rate is less than 20% through boiler-side modification, the boiler combustion is unstable, and the operating requirements for the operating personnel are high. It is also easy to cause boiler fire extinguishing, which causes metal fatigue to the boiler metal equipment, reduces the equipment operation reliability, and reduces the unit operation life. Therefore, it is necessary to improve the existing technology. Summary of the invention

[0005] 1. Technical issues that need to be resolved

[0006] In view of the deficiencies in the prior art, the present invention provides a deep peak-shaving device and an operating method for coal-fired power units, which have a reasonable design and a simpler structure, reduce the cost investment, and realize the main steam heating transformation while achieving the deep peak-shaving operation transformation of the minimum rated load, thereby greatly improving the external heating capacity.

[0007] (II) Technical solutions that need to be adopted

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A deep peak-shaving device for a coal-fired power unit comprises a coal-fired power unit, a high-pressure bypass and a low-pressure bypass. The coal-fired power unit comprises a boiler, a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder. The superheater outlet of the boiler is connected to the steam inlet of the high-pressure cylinder through a main steam pipe, the superheater outlet of the boiler is connected to the steam inlet of the intermediate-pressure cylinder through a hot re-steam pipe, the exhaust steam of the intermediate-pressure cylinder is connected to the steam inlet of the low-pressure cylinder through an intermediate- and low-pressure connecting pipe, a regulating valve is arranged on the intermediate- and low-pressure connecting pipe, the main steam pipe is used to communicate with a thermal control system, a temperature reducing and pressure reducing device system is arranged on the main steam pipe, and a plurality of branch steam pipes are arranged on the main steam pipe on one side of the temperature reducing and pressure reducing device system, each of the branch steam pipes is provided with a first stop valve and a first electric valve, the branch steam pipes are connected to the thermal control system, and a plurality of drainage pipes are arranged on the main steam pipe on the other side of the temperature reducing and pressure reducing device.

[0010] Preferably, three branch steam pipes are used, each of which is connected to the thermal control system, and each of which is installed with the first stop valve and the first electric valve, and the first electric valve is a P91 valve. Correspondingly, the main steam pipe and the branch steam pipe are also made of P91 pipes.

[0011] Preferably, eight drainage pipes are used, each of which is provided with two second stop valves, and the drainage pipes are all made of 15CrMo pipes.

[0012] Preferably, a first flow meter, a second check valve, a second electric valve and a second stop valve are sequentially arranged on the main steam pipeline on the other side of the temperature reduction and pressure reduction device system.

[0013] Preferably, the temperature and pressure reducing device system includes a first regulating valve and a desuperheater arranged on the main steam pipeline, the desuperheater is provided with a pipeline, and a third check valve, a third stop valve, a second regulating valve, a third electric valve, a second flow meter, a first throttle valve, a filter and a fourth stop valve are sequentially arranged on the pipeline, and a fifth stop valve is connected in parallel to the pipeline of the third stop valve, the second regulating valve and the third electric valve.

[0014] Preferably, a safety valve is provided on the desuperheater.

[0015] In addition, the present invention also provides an operating method for a deep peak-shaving device for a coal-fired power unit as described above, comprising the following steps:

[0016] S1. The main steam pipeline in the coal-fired power unit extracts the main steam, and the main steam pipeline passes through the temperature and pressure reducing device system to supply heat to the outside;

[0017] S2. By adjusting the pressure in the temperature and pressure reducing device system, it is beneficial to realize the deep peak-shaving operation transformation of the minimum rated load, and at the same time, it realizes the main steam heating transformation and greatly improves the external heating capacity.

[0018] (III) Technical effects to be achieved

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The main steam pipeline of the present invention is provided with a temperature reducing and pressure reducing device system, and a plurality of branch steam pipelines are provided on the main steam pipeline on one side of the temperature reducing and pressure reducing device system, each branch steam pipeline is provided with a first stop valve and a first electric valve, the branch steam pipelines are connected to a thermal control system, and a plurality of drain pipes are provided on the main steam pipeline on the other side of the temperature reducing and pressure reducing device. The design is reasonable, the structure is simpler, the cost investment is reduced, and the main steam heating transformation is realized while realizing the deep peak-shaving operation transformation of the minimum rated load, which greatly improves the external heating capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic diagram of a deep peak regulation device for coal-fired power units.

[0022] In the figure: 1, cooling and pressure reducing device system; 2, first stop valve; 3, first electric valve; 4, second stop valve; 5, first flow meter; 6, second check valve; 7, second electric valve; 8, second stop valve; 11, first regulating valve; 12, cooler; 13, third check valve; 14, third stop valve; 15, second regulating valve; 16, third electric valve; 17, second flow meter; 18, first throttle valve. DETAILED DESCRIPTION

[0023] In the description of the present invention, it should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0024] In the description of the present invention, it should be noted that the terms "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invention product is usually placed when in use, and are only for the convenience of describing the present invention 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 limiting the present invention. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

[0025] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0027] Example 1: See Figure 1, a deep peak regulation device for coal-fired power units, including a coal-fired power unit, a high-pressure bypass and a low-pressure bypass, the coal-fired power unit including a boiler, a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, the superheater outlet of the boiler (and in this example, the steam chamber) is connected to the steam inlet of the high-pressure cylinder through a main steam pipe, the superheater outlet of the boiler is connected to the steam inlet of the medium-pressure cylinder through a hot re-steam pipe, the exhaust steam of the medium-pressure cylinder is connected to the steam inlet of the low-pressure cylinder through a medium- and low-pressure connecting pipe, and a regulating valve is arranged on the medium- and low-pressure connecting pipe. The main steam pipe is used to communicate with a thermal control system (the thermal control system is a prior art, so it will not be described in detail), which is beneficial to the external heat supply of the thermal control system. A temperature reducing and pressure reducing device system 1 is arranged on the main steam pipe, and a plurality of branch steam pipes (heating pipes) are arranged on the main steam pipe on one side of the temperature reducing and pressure reducing device system 1, each branch steam pipe is provided with a first stop valve 2 and a first electric valve 3, the branch steam pipes are connected to the thermal control system, and a plurality of drainage pipes are arranged on the main steam pipe on the other side of the temperature reducing and pressure reducing device 1.

[0028] Embodiment 2: It can be explained on the basis of embodiment 1 that three branch steam pipes are used, each branch steam pipe is connected to a thermal control system, each branch steam pipe is installed with a first stop valve 2 and a first electric valve 3, and the first electric valve 3 is a P91 valve, and correspondingly, the main steam pipe and the branch steam pipe are also made of P91 pipes, which are suitable for higher temperatures and pressures and are more suitable for use in such places.

[0029] Embodiment 3: It can be explained on the basis of Embodiment 1 or Embodiment 2 that the drainage pipe (SS, representing drainage, this project The following drainage pipes are to be laid by yourself according to the site conditions) are eight, and each drainage pipe is provided with two second stop valves 4, and the drainage pipes are all 15CrMo pipes, which are heat-resistant pipes, which can greatly improve the reliability of the equipment. Further explanation, the main steam pipe on the other side of the temperature and pressure reducer system 1 is provided with a first flow meter 5, a second check valve 6, a second electric valve 7 and a second stop valve 8 in sequence, which is more conducive to convenient control.

[0030] Embodiment 4: It can be explained on the basis of embodiment 1 or embodiment 2 or embodiment 3 that the temperature reducing and pressure reducing device system 1 includes a first regulating valve 11 and a temperature reducing device 12 arranged on the main steam pipeline, and a pipeline is arranged on the temperature reducing device 12, and a third check valve 13, a third stop valve 14, a second regulating valve 15, a third electric valve 16, a second flow meter 17, a first throttle valve 18, a filter 19 and a fourth stop valve are arranged on the pipeline in sequence, and a fifth stop valve is connected in parallel on the pipeline of the third stop valve 14, the second regulating valve 15 and the third electric valve 16, and this arrangement is reasonable, and the water is pumped through the pipeline on the fourth stop valve. It is further explained that a safety valve is arranged on the temperature reducing device 12, and this arrangement is reasonable, which improves the safety of use. In the present invention, the temperature reducing and pressure reducing device system 1 cannot meet the needs of heat users because the main steam extraction pressure is too high, so it is necessary to adjust the parameters to a suitable range through the temperature reducing device 12. In the desuperheater 12, the operating pressure of the desuperheating water pipeline is 7-10MPa, the operating temperature is 170°C, the design pressure is 11MPa, and the design temperature is 180°C.

[0031] Embodiment 5: It can be described on the basis of Embodiment 1 or Embodiment 2 or Embodiment 3 or Embodiment 4, a method for operating a deep peak regulation device for a coal-fired power unit as described above, comprising the following steps:

[0032] S1, the main steam pipeline in the coal-fired power unit extracts the main steam, and the main steam pipeline passes through the temperature and pressure reducing device system 1 to supply heat to the outside;

[0033] S2. By adjusting the pressure in the temperature and pressure reducing device system 1, it is beneficial to realize the deep peak-shaving operation transformation of the minimum rated load, and at the same time, realize the main steam heating transformation, which greatly improves the external heating capacity.

[0034] In the prior art, the minimum operating condition of a general boiler design is 30% of the rated condition, and the boiler load during deep peak regulation operation is greater than 30% of the rated load. The main steam pipeline of the present invention is provided with a plurality of branch steam pipelines (heating pipelines), and thermal and electrical decoupling is achieved through main steam heating. When the boiler is operating under 30% of the rated load condition, the main steam is extracted for external heating, which reduces the amount of steam entering the turbine and reduces the generator output, thereby achieving 18% deep peak regulation operation. The key to achieving 20% ​​deep peak-shaving operation of coal-fired power units lies in the stability of boiler combustion during deep regulation. Generally, the initial design of coal-fired power units is that the minimum load for stable operation is 30% of the rated load. The present invention mainly reduces the steam intake of the turbine and reduces the output of the turbine by ensuring the minimum technical output of the boiler, that is, 30% of the rated load, so as to achieve 20% deep peak-shaving operation. While achieving the operation of the unit below 20% of the rated load, the unit has the ability to supply heat to the outside with a large flow rate. For example, the corresponding load of the boiler of a 330MW unit is 99MW when the rated load is 30%. Generally, the main steam of a 300MW-level unit with 30t / h corresponds to a load of 10MW. To achieve a rated load below 20% (i.e. 66MW), at least 99t / h needs to be extracted. Finally, 120t / h of main steam is extracted from the main steam pipeline to supply heat to the outside to achieve 18% rated load deep peak-shaving operation while realizing the external heating transformation of the main steam of the unit. It can be seen that the transformation cost is reduced by about 80% compared with the cost of the conventional technical route, which greatly saves the transformation cost, reduces the workload of the transformation, and reduces the transformation equipment. Secondly, the boiler can operate above 30% of the rated load, which reduces the operating pressure on operators and the impact on equipment life.

[0035] The present invention can have multiple main steam pipelines. When the main steam pipelines are all put into the heating pipeline, the operating pressure is 9-10MPa, the operating temperature is 530-538℃, the main steam pipe design pressure is 17.47MPa, and the design temperature is 546℃; after the temperature and pressure reduction of one main steam pipeline, the heating pipeline has an operating pressure of 2.5MPa, an operating temperature of 390℃, a design pressure of 2.65MPa, and a design temperature of 410℃. The present invention can realize that the boiler meets the minimum design output while realizing the main steam external heating and 18% rated load deep peak regulation operation.

[0036] The standard parts used in this application document can all be purchased from the market. The specific connection methods of each part adopt the conventional means such as mature boilers, high-pressure cylinders, medium-pressure cylinders and low-pressure cylinders in the prior art. The internal components of the desuperheater all adopt conventional models in the prior art, and its internal structure belongs to the existing technical structure. Workers can complete normal operation of it according to the existing technical manual. In addition, the circuit connection adopts the conventional connection method in the prior art, and no specific description is given here.

[0037] It should be noted that, although the above embodiments have been described in this article, the scope of patent protection of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, changes and modifications made to the embodiments described herein, or equivalent structures or equivalent process changes made using the contents of the present specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields are all included in the scope of protection of the patent of the present invention.

Claims

1. A deep peak-shaving device for a coal-fired power unit, comprising a coal-fired power unit, a high-pressure bypass and a low-pressure bypass, wherein the coal-fired power unit comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder, wherein the superheater outlet of the boiler is connected to the steam inlet of the high-pressure cylinder through a main steam pipeline, the superheater outlet of the boiler is connected to the steam inlet of the medium-pressure cylinder through a hot re-steam pipeline, the exhaust steam of the medium-pressure cylinder is connected to the steam inlet of the low-pressure cylinder through a medium- and low-pressure connecting pipe, a regulating valve is provided on the medium- and low-pressure connecting pipe, and the main steam pipeline is used to communicate with a thermal control system, characterized in that: The main steam pipeline is provided with a temperature reducing and pressure reducing device system (1), and a plurality of branch steam pipelines are provided on the main steam pipeline on one side of the temperature reducing and pressure reducing device system (1), each of the branch steam pipelines is provided with a first stop valve (2) and a first electric valve (3), and the branch steam pipelines are all connected to the thermal control system, and a plurality of drainage pipelines are provided on the main steam pipeline on the other side of the temperature reducing and pressure reducing device (1).

2. The deep peak regulation device for coal-fired power generation units according to claim 1, characterized in that: The branch steam pipelines are three in number, each of which is connected to the thermal control system, each of which is installed with the first stop valve (2) and the first electric valve (3), and the first electric valve (3) is a P91 valve. The main steam pipeline and the branch steam pipeline are also made of P91 pipes.

3. The deep peak regulation device for coal-fired power generation units according to claim 1 or 2, characterized in that: The drainage water pipes are eight in number, each of which is provided with two second stop valves (4), and the drainage water pipes are all made of 15CrMo pipes.

4. The deep peak regulation device for coal-fired power generation units according to claim 3, characterized in that: A first flow meter (5), a second check valve (6), a second electric valve (7) and a second stop valve (8) are sequentially arranged on the main steam pipeline on the other side of the temperature reducing and pressure reducing device system (1).

5. The deep peak regulation device for coal-fired power generation units according to claim 1, 2 or 4, characterized in that: The desuperheater and pressure reducer system (1) comprises a first regulating valve (11) and a desuperheater (12) arranged on the main steam pipeline, wherein the desuperheater (12) is provided with a pipeline, wherein a third check valve (13), a third stop valve (14), a second regulating valve (15), a third electric valve (16), a second flow meter (17), a first throttle valve (18), a filter (19) and a fourth stop valve are sequentially arranged on the pipeline, and a fifth stop valve is connected in parallel to the pipeline of the third stop valve (14), the second regulating valve (15) and the third electric valve (16).

6. The deep peak regulation device for coal-fired power generation units according to claim 5, characterized in that: The desuperheater (12) is provided with a safety valve.

7. An operating method for a deep peak-shaving device for a coal-fired power unit as claimed in any one of claims 1 to 6, characterized in that: The steps include: S1. The main steam pipeline in the coal-fired power unit extracts the main steam, and the main steam pipeline passes through the temperature and pressure reducing device system to supply heat to the outside; S2. By adjusting the pressure in the temperature and pressure reducing device system, it is beneficial to realize the deep peak-shaving operation transformation of the minimum rated load, and at the same time, it realizes the main steam heating transformation and greatly improves the external heating capacity.

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