Thermodynamic system capable of rapidly adjusting unit load

Abstract

The utility model belongs to the technical field of thermal power generation, and relates to a thermodynamic system capable of quickly adjusting unit load, which comprises a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder and a regenerative system, the high-pressure cylinder and the intermediate-pressure cylinder are respectively connected with main steam and reheat steam of the boiler, and steam exhaust of the intermediate-pressure cylinder is connected with the low-pressure cylinder. The regenerative system comprises a mixed heater, a plurality of high-pressure heaters, a plurality of low-pressure heaters, an oxygen removal water supply assembly and a condenser assembly, and the mixed heater is connected with a first-stage steam extraction opening of a high-pressure cylinder; the condenser assembly is used for condensing dead steam of the low-pressure cylinder into water, then the water is heated by the low-pressure heater, the deoxygenization water supply assembly, the high-pressure heater and the mixed heater in sequence, and then the water enters the boiler again. According to the utility model, when the unit needs to quickly increase and decrease the load, the aim of increasing the load adjusting speed of the unit is fulfilled in a manner of squeezing or strengthening heat regeneration through the inherent heat storage function.

Description

Technical Field

[0001] The utility model belongs to the technical field of thermal power generation, and in particular relates to a thermal system for rapidly adjusting the load of a unit. Background Art

[0002] The operational design characteristics of future thermal power plants pose new requirements, requiring them to possess rapid load changes and deep peak regulation capabilities. In principle, thermal power units primarily control output by adjusting the amount of fuel and water entering the boiler. However, due to the complexity of this process and the long control loop time, additional auxiliary methods are required to achieve the rapid load changes required by the power grid.

[0003] At present, the typical thermal system of a thermal power plant is mainly composed of a high-pressure heater, a deaerator, and a low-pressure heater. Large-capacity units of 300MW and above generally have 3-5 stages of high-pressure heaters, 4-5 stages of low-pressure heaters, and one stage of deaerator, with a total of 8-11 heat recovery stages. Due to the low heat storage quality of the deaerator, it only has the function of short-term frequency regulation and does not have the function of assisting the unit to quickly change load. At the same time, the best level that the thermal power unit can achieve is when the unit load rate is above 50%, the load change rate is 2.5%Pe / min, which is far from the target of 4%-5%Pe / min required for thermal power units to adapt to new power systems in the future. Utility Model Content

[0004] The purpose of the utility model is to solve the defects and deficiencies in the prior art and to design a thermal system for quickly adjusting the load of a unit.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a thermal system for rapidly adjusting the load of a unit, comprising a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder and a heat recovery system;

[0006] The high-pressure cylinder and the medium-pressure cylinder are connected to the main steam and reheated steam of the boiler respectively, and the exhaust steam of the medium-pressure cylinder is connected to the low-pressure cylinder;

[0007] The heat recovery system includes a hybrid heater, multiple high-pressure heaters, multiple low-pressure heaters, a deaerator water supply assembly and a condenser assembly. The hybrid heater is connected to the first-stage steam extraction port of the high-pressure cylinder. The condenser assembly is used to condense the exhaust steam from the low-pressure cylinder into water, which is then heated in sequence by the low-pressure heater, the deaerator water supply assembly, the high-pressure heater and the hybrid heater before re-entering the boiler.

[0008] Preferably, the hybrid heater and the deaeration water supply assembly are connected to the high-pressure water supply pump and the low-pressure water supply pump respectively, and a pre-pump is provided between the hybrid heater and the high-pressure water supply pump, and between the deaeration water supply assembly and the low-pressure water supply pump.

[0009] Preferably, the high-pressure water supply pump and the low-pressure water supply pump are both driven electrically or pneumatically.

[0010] Preferably, the multiple high-pressure heaters are respectively connected to the high-pressure cylinder and the medium-pressure cylinder, the multiple low-pressure heaters are respectively connected to the low-pressure cylinder, the deoxygenation water supply assembly is connected to the medium-pressure cylinder, and the deoxygenation water supply assembly is located between the multiple high-pressure heaters and the multiple low-pressure heaters.

[0011] Preferably, there are two low-pressure cylinders, and the condenser assembly includes two condensers respectively connected to the two low-pressure cylinders, and a condensate pump connected to the two condensers.

[0012] Preferably, a desalting device and a steam seal steam cooler are provided between the condenser assembly and the low-pressure heater.

[0013] Preferably, a high-pressure feedwater pump turbine and a low-pressure feedwater pump turbine are respectively arranged between the deaeration feedwater assembly and the two condensers.

[0014] Preferably, regulating valve groups are provided between the main steam and the high-pressure cylinder, and between the reheated steam and the medium-pressure cylinder.

[0015] Preferably, a high-pressure bypass valve is provided between the main steam and the boiler reheat steam inlet, and a low-pressure bypass valve is provided between the reheat steam and the condenser assembly.

[0016] After adopting the above technical solution, the thermal system for rapidly adjusting the unit load provided by the utility model has the following beneficial effects:

[0017] 1) The thermal system of the present invention is designed with a large-capacity hybrid heater connected to the first-stage extraction steam of the high-pressure cylinder, and is equipped with a corresponding pre-pump and high-pressure feed water pump. When the unit needs to quickly increase or decrease the load, the unit can increase the rate of load adjustment by displacing or enhancing heat recovery.

[0018] 2) The thermal system of the present invention, through the design of a hybrid heater, can effectively reduce the heat exchange end difference of this section of heat exchanger, reduce the water feed volume of the subsequent high-pressure heaters, thereby reducing the steam extraction volume of the subsequent high-pressure heaters and increasing the power generation, thereby effectively reducing the heat consumption of the unit, saving coal consumption and reducing carbon emissions.

[0019] 3) The thermal system of the present invention can reduce the operating pressure of the original high-pressure heater system from about 32MPa to about 10MPa, which can significantly reduce the investment in the corresponding high-pressure heater system equipment, pipelines, and valves. Since the leakage at the rupture point in the accident condition is relatively small, the capacity of the high-pressure heater emergency drain system can also be reduced.

[0020] 4) Under low-load conditions, the thermal system of the present invention can increase the peak-shaving depth within a certain period of time by utilizing the heat storage capacity of the hybrid heater of the system. When in the energy storage state, the actual operating load is high and the heat consumption of the unit is low, which can save coal consumption and reduce carbon emissions.

[0021] 5) In the thermal system of the present invention, since the pressure of the high-pressure heater system is reduced from about 32 MPa to about 10 MPa, the risk of water ingress into the steam turbine is reduced, and the action time requirement of the corresponding control valve is reduced, thereby reducing investment and system risks.

[0022] 6) The design of the thermal system of the present invention is completely linear and progressive in the load regulation mode switching process. Under the maximum output condition, the steam turbine still has about 20% flow rate for extraction. There are no temperature steps or load steps in any part of the system, and the control is relatively easy to implement. Compared with other energy storage technologies, under the premise of achieving the same load regulation performance, the thermal system of the present invention has a lower cost and less system impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a thermal system for quickly adjusting unit load according to the present invention.

[0024] Among them: boiler 1, high-pressure cylinder 2, medium-pressure cylinder 3, low-pressure cylinder 4, hybrid heater 5, high-pressure heater 6, low-pressure heater 7, deaeration water supply assembly 8, high-pressure feed water pump 9, low-pressure feed water pump 10, pre-pump 11, condenser 12, condensate pump 13, desalination device 14, steam seal steam cooler 15, high-pressure feed water pump turbine 16, low-pressure feed water pump turbine 17, regulating valve group 18, high-pressure bypass valve 19, low-pressure bypass valve 20. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments described are merely a portion of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and in no way limits the present invention, its application, or use. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0026] 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 application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0028] In the description of the present invention, it needs to be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0029] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0030] In addition, it should be noted that the use of words such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood as limiting the scope of protection of this utility model.

[0031] The utility model is a thermal system for quickly adjusting the unit load, which is suitable for new units or renovation projects with single or double reheating, such as Figure 1 As shown, it includes a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4 and a heat recovery system;

[0032] The high-pressure cylinder 2 and the intermediate-pressure cylinder 3 are connected to the main steam and reheated steam of the boiler 1 respectively, and the exhaust of the intermediate-pressure cylinder 3 is connected to the low-pressure cylinder 4. That is, the main steam generated by the boiler 1 enters the high-pressure cylinder 2 to perform work, and the exhaust of the high-pressure cylinder 2 enters the boiler reheater for reheating and then enters the intermediate-pressure cylinder 3. The exhaust of the intermediate-pressure cylinder 3 enters the low-pressure cylinder 4;

[0033] The heat recovery system includes a hybrid heater 5, multiple high-pressure heaters 6, multiple low-pressure heaters 7, a deaerator water supply component 8 and a condenser component. The hybrid heater 5 is connected to the first-level steam extraction port of the high-pressure cylinder 2. The condenser component is used to condense the exhaust steam of the low-pressure cylinder 4 into water, and then heat it in sequence through the low-pressure heater 7, the deaerator water supply component 8, the high-pressure heater 6 and the hybrid heater 5 before re-entering the boiler 1. Specifically, the multiple high-pressure heaters 6 are respectively connected to the high-pressure cylinder 2 and the medium-pressure cylinder 3, the multiple low-pressure heaters are respectively connected to the low-pressure cylinder 4, the deaerator water supply component 8 is connected to the medium-pressure cylinder 3, and the deaerator water supply component 8 is located between the multiple high-pressure heaters 6 and the multiple low-pressure heaters 7. Furthermore, the deaerator water supply component 8 includes a deaerator and a water tank. The hybrid heater 5 selects a large-capacity hybrid heater and has a large-capacity heat storage function. As a heat storage device, the heat storage medium is the heat passing through during operation. Hot water, due to the high saturation pressure, the working medium in the first-stage hybrid heater 5 has a large energy density, and only about 200-300 cubic meters of additional water storage is required to meet the rapid load change of the 1000MW unit from 50% to 100% capacity, so that the coal-fired power unit can better increase the proportion of the power grid's consumption of new energy, which has a great carbon reduction significance; the large amount of water storage in the large-capacity first-stage hybrid heater 5 can ensure that the water inlet demand of the boiler 1 is met during the entire load increase process when the water volume of the high- and low-pressure heaters changes. The water flow through the high and low-pressure heaters in this system is synchronized, and at the same time, by reducing the flow rate of the heaters to squeeze out the steam turbine work, the unit load adjustment rate is quickly increased. The main water medium flow is from the condenser to the condensate pump, low-pressure heater, deaerator, low-pressure feed water pump, high-pressure heater, hybrid heater, high-pressure feed water pump, and finally into the boiler, and each stage of the heater corresponds to the first-stage steam turbine extraction.

[0034] It should be noted that the number of large-capacity first-stage hybrid heaters 5 can be 1 to 4, and its operating pressure is determined by the first-stage steam extraction. In order to prevent water from entering the steam turbine, two quick-closing doors and two check valves are set on the pipeline. In the load-raising state, the make-up water temperature is still high-temperature water during the water discharge process of the heater. Although the steam extraction steam is discharged, the flow rate is always maintained. During the entire process, no cold water will be mixed into the hybrid heater 5.

[0035] In addition, in the secondary reheat unit, the first-stage steam extraction port is at the exhaust position of the ultra-high pressure cylinder. Those skilled in the art can make adaptive adjustments as needed, which will not be elaborated again.

[0036] The hybrid heater 5 and the deaeration water supply assembly 8 are respectively connected to the high-pressure water supply pump 9 and the low-pressure water supply pump 10. A pre-pump 11 is provided between the hybrid heater 5 and the high-pressure water supply pump 9, and between the deaeration water supply assembly 8 and the low-pressure water supply pump 10. The high-pressure water supply pump 9 and the low-pressure water supply pump 10 are both driven electrically or pneumatically. With this design, the original one-stage water supply pump is disassembled into two stages, which can reduce the operating pressure of the original high-pressure heater system from about 32MPa to about 10MPa, and can significantly reduce the investment in corresponding high-pressure heater system equipment, pipelines, and valves. Since the leakage of the rupture is small under accident conditions, the capacity of the high-pressure heater emergency drain system can also be reduced, that is, the manufacturing cost and maintenance difficulty of the equipment are reduced to a certain extent, the risk of equipment leakage is reduced, and the safety of the system is improved.

[0037] There are two low-pressure cylinders 4, and the condenser assembly includes two condensers 12 respectively connected to the two low-pressure cylinders 4, and a condensate pump 13 connected to the two condensers 12. A desalting device 14 and a steam seal steam cooler 15 are arranged between the condenser assembly and the low-pressure heater 7. Furthermore, a high-pressure feed water pump turbine 16 and a low-pressure feed water pump turbine 17 are respectively arranged between the deoxygenation feed water assembly 8 and the two condensers 12.

[0038] A regulating valve group 18 is provided between the main steam and the high-pressure cylinder 2, and between the reheated steam and the medium-pressure cylinder 3. A high-pressure bypass valve 19 is provided between the main steam and the reheated steam inlet of the boiler 1, and a low-pressure bypass valve 20 is provided between the reheated steam and the condenser assembly.

[0039] When the thermal system of the utility model is working to quickly adjust the load of the unit, when the unit needs to quickly increase or decrease the load, the rate of load adjustment of the unit can be effectively improved by adjusting the water volume of the heaters at each stage to exclude or enhance the heat recovery; excluding heat recovery is a flexible adjustment method, which reduces the amount of heat recovery extraction and uses more steam for work, thereby quickly increasing the output power of the unit; when the load rises rapidly, this method can quickly mobilize more steam energy, so that the unit can quickly respond to the needs of the power system, and enhancing heat recovery plays a role when the load needs to be reduced rapidly, and by increasing the amount of heat recovery extraction, the output power of the unit can be quickly reduced; this adjustment method can be flexibly adjusted according to the needs of load changes, so that the unit can respond quickly when facing various operating conditions, thereby improving the response speed and adjustment ability of the unit, although the amount of water passing through the heaters at each stage changes, because the large-capacity first-stage hybrid heater 5 stores enough high-temperature water, it can meet the boiler water inlet needs of the entire load increase process.

[0040] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited to this. Any technician familiar with the technical field within the technical scope disclosed by the present invention can make equivalent replacements or changes based on the technical solution and utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A thermal system for rapidly adjusting unit load, characterized by: It includes a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4) and a heat recovery system; The high-pressure cylinder (2) and the medium-pressure cylinder (3) are respectively connected to the main steam and reheated steam of the boiler (1), and the exhaust steam of the medium-pressure cylinder (3) is connected to the low-pressure cylinder (4); The heat recovery system comprises a hybrid heater (5), a plurality of high-pressure heaters (6), a plurality of low-pressure heaters (7), a deaeration water supply assembly (8) and a condenser assembly. The hybrid heater (5) is connected to the first-stage steam extraction port of the high-pressure cylinder (2). The condenser assembly is used to condense the exhaust steam of the low-pressure cylinder (4) into water, which is then heated in sequence by the low-pressure heater (7), the deaeration water supply assembly (8), the high-pressure heater (6) and the hybrid heater (5) before re-entering the boiler (1).

2. A thermal system for rapidly adjusting unit load according to claim 1, characterized in that: The hybrid heater (5) and the deoxygenation water supply assembly (8) are respectively connected to a high-pressure water supply pump (9) and a low-pressure water supply pump (10). A pre-pump (11) is provided between the hybrid heater (5) and the high-pressure water supply pump (9), and between the deoxygenation water supply assembly (8) and the low-pressure water supply pump (10).

3. A thermal system for rapidly adjusting unit load according to claim 2, characterized in that: The high-pressure water supply pump (9) and the low-pressure water supply pump (10) are both driven electrically or pneumatically.

4. The thermal system for rapidly adjusting unit load according to claim 1, characterized in that: The multiple high-pressure heaters (6) are respectively connected to the high-pressure cylinder (2) and the medium-pressure cylinder (3), the multiple low-pressure heaters are respectively connected to the low-pressure cylinder (4), the deaeration water supply assembly (8) is connected to the medium-pressure cylinder (3), and the deaeration water supply assembly (8) is located between the multiple high-pressure heaters (6) and the multiple low-pressure heaters (7).

5. The thermal system for rapidly adjusting unit load according to claim 1, characterized in that: There are two low-pressure cylinders (4), and the condenser assembly includes two condensers (12) respectively connected to the two low-pressure cylinders (4), and a condensate pump (13) connected to the two condensers (12).

6. The thermal system for rapidly adjusting unit load according to claim 1, characterized in that: A desalting device (14) and a steam seal steam cooler (15) are provided between the condenser assembly and the low-pressure heater (7).

7. The thermal system for rapidly adjusting unit load according to claim 5, characterized in that: A high-pressure feedwater pump turbine (16) and a low-pressure feedwater pump turbine (17) are respectively arranged between the deoxygenated feedwater assembly (8) and the two condensers (12).

8. The thermal system for rapidly adjusting unit load according to claim 1, characterized in that: A regulating valve group (18) is provided between the main steam and the high-pressure cylinder (2), and between the reheated steam and the medium-pressure cylinder (3).

9. The thermal system for rapidly adjusting unit load according to claim 1, characterized in that: A high-pressure bypass valve (19) is provided between the main steam and the reheat steam inlet of the boiler (1), and a low-pressure bypass valve (20) is provided between the reheat steam and the condenser assembly.

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