A new type of thermoelectric decoupling heating system with low load and high efficiency

Abstract

This invention discloses a novel, low-load, high-efficiency thermoelectric decoupling heating system. The system is characterized by replacing the high-pressure bypass section with an extraction section. This extraction section extracts steam from the middle of the superheater and uses this steam to heat the secondary air or drive the induced draft fan. Compared to existing technologies, this invention, after heating the secondary air or driving the induced draft fan, returns the steam to the cold section, thus overcoming the problem of limited extraction capacity in conventional systems. It also allows for changes in the coal-to-water ratio within the boiler under low load conditions, increasing the outlet steam temperature of the superheater and reheater under low load conditions, and avoiding the widespread problem of underheating of main steam and hot reheat steam under low load conditions.

Description

Technical Field

[0001] This utility model relates to steam heating systems, and in particular to a novel thermoelectric decoupling heating system with low load and high efficiency. Background Technology

[0002] In existing supercritical units, the main steam is desuperheated and depressurized through a high-pressure bypass before entering the cold section, while steam is extracted from the hot section for external heating. This system experiences a decrease in extraction capacity and pressure during low-load operation, making it unable to meet the unit's external heating demands. This is because the main steam, after being desuperheated and depressurized by water injection through the bypass, directly enters the cold section, failing to achieve cascaded energy utilization.

[0003] Therefore, a new type of thermoelectric decoupling heating system with low load and high efficiency is needed. Summary of the Invention

[0004] The present invention aims to provide a novel, low-load, high-efficiency thermoelectric decoupling heating system. Specifically:

[0005] A novel, low-load, high-efficiency thermoelectric decoupling heating system, characterized in that the system includes a boiler and an extraction section; wherein:

[0006] The boiler includes a superheater and a reheater, and the outlet of the superheater is the main steam pipe.

[0007] The extraction section is configured to extract steam from a tap located in the middle of the superheater to obtain diverted steam; after extracting the diverted steam, the extraction section is configured with two paths, one path is configured with a heater, and the other path is configured with a second power generation unit and an induced draft fan, wherein the power generation unit and the induced draft fan are connected to receive the diverted steam as a low-load drive gas source for the induced draft fan.

[0008] In a preferred embodiment, the extraction section is further configured to extract air from a tap on the main steam pipe.

[0009] In a preferred embodiment, the heating system is also equipped with a cold section.

[0010] In a preferred embodiment, the cold section is configured to receive the exhaust steam from the split steam after it has passed through the heater or generator and deliver it to the reheater.

[0011] In a preferred embodiment, the extraction section is equipped with a switching valve.

[0012] In a preferred embodiment, the power generation unit includes a small steam turbine and a small generator.

[0013] In a preferred embodiment, the heater is configured to receive the diverted steam and heat the hot secondary air using the diverted steam.

[0014] In a preferred embodiment, the adjustable valve of the induced draft fan controls the steam flow rate to adapt to different low-load operating conditions.

[0015] In a preferred embodiment, the heating system is further configured with a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder connected to each other, the outlet of the high-pressure cylinder being connected to the cold section, and the low-pressure cylinder being connected to the generator.

[0016] The main advantages of this utility model are:

[0017] (1) The extraction section of this utility model can replace the high-pressure bypass valve in the bypass heating, avoiding the internal leakage problem caused by the frequent opening of the high-pressure bypass valve, and at the same time avoiding the energy waste problem of direct cooling and decompression of high-temperature steam.

[0018] (2) Unlike conventional direct extraction of steam for external heating, this utility model extracts steam from the intermediate tap of the superheater to heat the secondary air or drive the induced draft fan, and then returns to the cold section. This can get rid of the problem of limited extraction volume in conventional systems (conventional low-load extraction steam systems are limited by the reheater overheating problem, and the extraction volume can only be 5%-8% of the reheater flow rate). The extraction volume of this technology is not affected by the reheater overheating problem.

[0019] (3) This utility model improves the temperature of the secondary hot air under low load, thereby improving boiler efficiency.

[0020] (4) This utility model can change the coal-water ratio in the boiler under low load, increase the outlet steam temperature of the superheater and reheater under low load, and avoid the universal problem of underheating of main steam and hot reheat steam under low load.

[0021] (5) The extraction section involved in this utility model has wide applicability and is applicable to various types of steam turbines and boilers.

[0022] The specification of this utility model contains numerous technical features distributed across various technical solutions. Listing all possible combinations of these features (i.e., technical solutions) would make the specification excessively lengthy. To avoid this problem, the various technical features disclosed in the above-described invention, the various technical features disclosed in the following embodiments and examples, and the various technical features disclosed in the accompanying drawings can be freely combined to form various new technical solutions (all of which should be considered as described in this specification), unless such a combination of technical features is technically infeasible. For example, one example discloses feature A+B+C, and another example discloses feature A+B+D+E. Features C and D are equivalent technical means that serve the same function, and technically only one needs to be used; they cannot be used simultaneously. Feature E can technically be combined with feature C. Therefore, the solution A+B+C+D should not be considered as described because it is technically infeasible, while the solution A+B+C+E should be considered as described. Attached Figure Description

[0023] Figure 1 It is a boiler steam system in the existing technology;

[0024] Figure 2 This is a typical flow chart of a novel thermoelectric decoupling heating system with low load and high efficiency according to an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1-High-pressure cylinder; 2-Medium-pressure cylinder; 3-Low-pressure cylinder; 4-Warm air heater; 5-Induced draft fan; 6-Small steam turbine; 7-Small generator; 8-Superheater; 9-Boiler; 10-Reheater; 11-Water inlet; 12-Generator. Detailed Implementation

[0027] Through in-depth and extensive research, the inventors of this invention have developed a novel low-load, high-efficiency thermoelectric decoupling heating system. This system replaces the high-pressure bypass system by configuring an extraction section to extract steam from the middle tap of the superheater, and uses this steam to heat the secondary air or drive the induced draft fan. Compared to existing technologies, this invention returns steam to the cold section after heating the secondary air or driving the induced draft fan, thus overcoming the problem of limited steam extraction capacity in conventional systems.

[0028] Example

[0029] Specifically, one embodiment of this utility model is as follows: Figure 2 As shown, it includes an extraction section, a boiler 9, a high-pressure cylinder 1, a low-pressure cylinder 3, an intermediate-pressure cylinder 2, and a generator 12: where:

[0030] The boiler 9 is equipped with a superheater 8 and a reheater 10. The superheater 8 is configured to receive the incoming water 11, heat it, and send the heated steam into the high-pressure cylinder through the main steam pipeline.

[0031] The reheater 10 is configured to receive and reheat the exhaust steam delivered from the cold section. The reheated working fluid is then sent to the intermediate pressure cylinder 2 or depressurized and then supplied to the outside for heating.

[0032] The extraction section is configured to extract steam from a tap located in the middle of the superheater 10 to obtain split steam. Specifically, the extraction section is as follows: Figure 2 As shown, after the diverted steam is extracted, there are two channels. One channel is equipped with a heater 4, and the other channel is equipped with a second generator set and an induced draft fan 5. The second generator set and the induced draft fan 5 are connected to receive the diverted steam as a low-load drive gas source for the induced draft fan 5.

[0033] Optionally, in one embodiment, the second power generation unit includes a small steam turbine 6 and a small generator 7.

[0034] Alternatively, in another embodiment, the induced draft fan 5 is equipped with an adjustable valve to control the steam flow rate to adapt to different low-load operating conditions.

[0035] like Figure 2 As shown, the heating system is also equipped with a cold section and interconnected high-pressure cylinder 1, medium-pressure cylinder 2, and low-pressure cylinder 3. The outlet of high-pressure cylinder 1 is connected to the cold section, and low-pressure cylinder 3 is connected to generator 12.

[0036] Alternatively, in one embodiment, the extraction section is further configured to extract air from a tap on the main steam duct.

[0037] Optionally, in one embodiment, the cold section is configured to receive the exhaust steam from the diverted steam after it has passed through the heater 4 or the generator set and deliver it to the reheater. Optionally, in another embodiment, the exhaust steam also includes outlet steam from the high-pressure cylinder 1.

[0038] Optionally, in one embodiment, the extraction section is equipped with a switching valve.

[0039] Furthermore, it should be noted in this embodiment that, in the utility model document of this patent, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In the utility model document of this patent, if it refers to performing an action according to a certain element, it means performing the action at least according to that element, including two cases: performing the action only according to that element, and performing the action according to that element and other elements. Expressions such as "multiple," "repeatedly," and "various" include two, two times, two kinds, and more than two, more than two times, and more than two kinds.

Claims

1. A novel thermoelectric decoupling heating system with low load and high efficiency, characterized in that, The system includes a boiler and an extraction section; wherein: The boiler includes a superheater and a reheater, and the outlet of the superheater is the main steam pipe. The extraction section is configured to extract steam from a tap located in the middle of the superheater to obtain diverted steam; the extraction section is configured with two paths after extracting the diverted steam, one path is equipped with a heater, and the other path is equipped with a second power generation unit and an induced draft fan, wherein the second power generation unit and the induced draft fan are connected to receive the diverted steam as a low-load drive gas source for the induced draft fan.

2. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 1, characterized in that, The extraction section is also configured to extract air from a tap on the main steam pipe.

3. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 1, characterized in that, The heating system is also equipped with a cold section.

4. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 3, characterized in that, The cold section is configured to receive the exhaust steam from the diverted steam after it has passed through the heater or generator and deliver it to the reheater.

5. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 1, characterized in that, The extraction section is equipped with a switch valve.

6. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 1, characterized in that, The second power generation unit includes a small steam turbine and a small generator.

7. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 1, characterized in that, The heater is configured to receive the diverted steam and heat the hot secondary air using the diverted steam.

8. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 1, characterized in that, The induced draft fan is equipped with an adjustable valve to control the steam flow rate, in order to adapt to different low-load operating conditions.

9. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 3, characterized in that, The heating system is also equipped with interconnected high-pressure cylinders, medium-pressure cylinders, and low-pressure cylinders. The outlet of the high-pressure cylinder is connected to the cold section, and the low-pressure cylinder is connected to the generator.

10. The novel thermoelectric decoupling heating system with low load and high efficiency according to claim 9, characterized in that, The intermediate-pressure cylinder is configured to receive the working fluid after it has been reheated by the reheater.

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