High and medium parameter unit heat supply system for low-quality steam composite upgrading

Abstract

The utility model discloses a high-medium parameter unit heat supply system for low-quality steam composite upgrading, which belongs to the technical field of thermal power unit heat supply and comprises a steam-steam heat exchanger, a flue gas heat exchanger, a medium-pressure heat supply header and a high-pressure heat supply header. The steam-steam heat exchanger comprises a first steam inlet, a first steam outlet, a second steam inlet and a second steam outlet. The flue gas heat exchanger comprises a first medium inlet, a first medium outlet, a second medium inlet and a second medium outlet. Effective utilization of heat energy is achieved, the temperature of low-temperature heat supply steam is increased, the heat supply coupling phenomenon of high and medium parameters is avoided, and the flexibility of the system is improved; the requirement for additional equipment is lowered, and meanwhile the boiler feed water temperature is increased; the recycling rate of the heat energy is increased, the energy consumption is reduced, and important economic value is achieved; different steam parameters can be provided according to actual heat supply requirements, the flexibility of the system is improved, and the system can better adapt to various operation conditions.

Description

Technical Field

[0001] This utility model belongs to the field of thermal power unit heating technology, specifically relating to a high and medium parameter unit heating system for low-quality steam composite upgrading. Background Technology

[0002] In modern industrial heating systems, steam, as the heat energy carrier, is crucial to process requirements due to its quality and parameters. However, because different processes have varying steam requirements, traditional unit designs often prioritize overall efficiency and economy when selecting extraction points, resulting in extraction pressures and temperatures that cannot simultaneously meet the needs of all heat users. This mismatch leads to inefficiency, with some processes requiring low-pressure steam to prevent equipment damage, while others require high-temperature steam to achieve optimal reaction rates. To resolve this contradiction, many systems choose to extract steam from high-pressure or high-temperature extraction points and adjust it to the required parameters using desuperheating and pressure-reducing devices. While this method can meet heating demands in the short term, it results in significant energy waste and reduces the overall thermal efficiency of the system. Utility Model Content

[0003] The technical problem solved by this utility model is to provide a high- and medium-parameter unit heating system for composite upgrading of low-quality steam, which avoids the direct de-cooling and de-pressure operation of high-quality steam, comprehensively improves the utilization efficiency of low-grade steam, reduces energy consumption, and improves the economy and environmental protection of the heating system.

[0004] Technical solution: To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0005] A high- and medium-parameter unit heating system for low-quality steam composite upgrading includes a steam-to-steam heat exchanger, a flue gas heat exchanger, a medium-pressure heating header, and a high-pressure heating header. The steam-to-steam heat exchanger includes a first steam inlet, a first steam outlet connected to the first steam inlet, a second steam inlet, and a second steam outlet connected to the second steam inlet. The first steam inlet is connected to a reheat steam pipeline, the first steam outlet is connected to the medium-pressure heating header, the second steam inlet is connected to the unit's high-pressure cylinder, and the second steam outlet is connected to the high-pressure heating header. The flue gas heat exchanger includes a first medium inlet, a first medium outlet connected to the first medium inlet, a second medium inlet, and a second medium outlet connected to the second medium inlet. The first medium inlet is connected to the unit's high-pressure cylinder, the first medium outlet is connected to the high-pressure heating header, and the second medium inlet is connected to a flue gas pipeline.

[0006] Furthermore, it also includes a steam cooler, which includes a third medium inlet, a third medium outlet connected to the third medium inlet, a fourth medium inlet, and a fourth medium outlet connected to the fourth medium inlet. The first steam outlet is connected to the third medium inlet, the third medium outlet is connected to the medium-pressure heating header, and the fourth medium inlet is connected to the boiler feedwater pipeline.

[0007] Furthermore, the first steam inlet is connected to the hot reheat steam pipeline via a first pipeline, and the first pipeline is equipped with a first inlet shut-off valve, a first extraction steam pressure reducing valve, and a first extraction steam regulating valve.

[0008] Furthermore, the second steam inlet is connected to the high-pressure cylinder of the unit through a second pipeline, and the second pipeline is equipped with a second inlet shut-off valve, a second extraction steam pressure reducing valve, and a second extraction steam regulating valve.

[0009] Furthermore, the first medium inlet is connected to the unit's high-pressure cylinder via a third pipeline, which is equipped with a third inlet shut-off valve, a third extraction steam pressure reducing valve, and a third extraction steam regulating valve.

[0010] Furthermore, a first outlet shut-off valve is provided on the pipe of the first steam outlet, a second outlet shut-off valve is provided on the pipe of the second steam outlet, and a third outlet shut-off valve is provided on the pipe of the first medium outlet.

[0011] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0012] 1. By setting up steam-to-steam heat exchangers, flue gas heat exchangers, medium-pressure heating headers, high-pressure heating headers, and steam coolers, steam-to-steam heat exchangers can effectively utilize thermal energy by adjusting the flow rate and temperature of high- and low-temperature heating steam. Flue gas heat exchangers can increase the temperature of low-temperature heating steam by utilizing flue gas when the medium-pressure heating load is insufficient, thus avoiding the coupling phenomenon of high and medium parameter heating and improving the flexibility of the system.

[0013] 2. After steam-to-steam heat exchange, the steam temperature at the hot side outlet is still very high. The feedwater is directly heated by the high-temperature steam through the steam cooler, so that the steam temperature at the hot side outlet can be reduced to the heating temperature required for medium pressure without the use of desuperheating water. This reduces the need for additional equipment while increasing the boiler feedwater temperature.

[0014] 3. The high and medium parameter heating steam in this system undergoes a combined process of steam reheating and flue gas reheating to improve its quality, which not only increases the heat energy recovery and utilization rate but also reduces energy consumption, thus having significant economic value.

[0015] 4. The combination of steam reheat and flue gas reheat can provide different steam parameters according to actual heating needs, which improves the system's flexibility and better adapts to various operating conditions. Attached Figure Description

[0016] Figure 1 This is a system connection block diagram of an embodiment of the present utility model;

[0017] Figure 2 This is a connection diagram of the flue gas heat exchanger in the embodiment;

[0018] Figure 3 This is a schematic diagram of the connection at the steam cooler in the embodiment. Detailed Implementation

[0019] The present invention will be further illustrated below with reference to specific embodiments. The embodiments are implemented based on the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0020] like Figure 1 As shown, a high- and medium-parameter unit heating system for low-quality steam composite upgrading includes a steam-to-steam heat exchanger 1, a flue gas heat exchanger 2, a medium-pressure heating header 3, a high-pressure heating header 4, and a steam cooler 5. The steam-to-steam heat exchanger 1 uses an existing gas-to-gas heat exchanger and includes a first steam inlet 11, a first steam outlet 12, a second steam inlet 13, and a second steam outlet 14. The first steam outlet 12 is connected to the first steam inlet 11, and the second steam outlet 14 is connected to the second steam inlet 13. The first steam inlet 11 is connected to the unit's hot reheat steam pipeline 91. The high-temperature heating steam extracted from the unit enters the steam-to-steam heat exchanger 1 through the first steam inlet 11. The second steam inlet 13 is connected to the high-pressure cylinder 92 of the unit. The low-temperature heating steam extracted from the high-pressure cylinder 92 of the unit enters the steam-to-steam heat exchanger 1 through the second steam inlet 13. The low-temperature heating steam and the high-temperature heating steam exchange heat in the steam-to-steam heat exchanger 1. The high-temperature heating steam heats the low-temperature heating steam. The first steam outlet 12 is connected to the steam cooler 5. After heat exchange, the high-temperature heating steam enters the steam cooler 5. The second steam outlet 14 is connected to the high-pressure heating header 4. After heat exchange, the low-temperature heating steam enters the high-pressure heating header 4.

[0021] like Figure 1 and Figure 3As shown, the steam cooler 5 includes a third medium inlet 51, a third medium outlet 52, a fourth medium inlet 53, and a fourth medium outlet 54. The steam cooler 5 uses an existing liquid-gas heat exchanger. The third medium outlet 52 is connected to the third medium inlet 51, and the fourth medium outlet 54 is connected to the fourth medium inlet 53. The first steam outlet 12 is connected to the third medium inlet 51. The third medium outlet 52 is connected to the medium-pressure heating header 3. The fourth medium inlet 53 is connected to the boiler feedwater pipeline 94. The high-temperature heating steam from the first steam outlet 12 enters the steam cooler 5 from the third medium inlet 51 and exchanges heat with the feedwater entering from the fourth medium inlet 53. The high-temperature heating steam heats the boiler feedwater and, while heating the feedwater, lowers its own temperature to the temperature required for medium-parameter heating before being sent to the medium-pressure heating header 3.

[0022] like Figure 1 and Figure 2 As shown, the flue gas heat exchanger 2 adopts an existing gas-to-gas heat exchanger. The flue gas heat exchanger 2 includes a first medium inlet 21, a first medium outlet 22, a second medium inlet 23, and a second medium outlet 24. The first medium outlet 22 is connected to the first medium inlet 21, and the second medium outlet 24 is connected to the second medium inlet 23. The first medium inlet 21 is connected to the unit's high-pressure cylinder 92 for introducing low-temperature heating steam. The first medium outlet 22 is connected to the high-pressure heating header 4. The second medium inlet 23 is connected to the flue gas duct 93 and the flue gas from the boiler's final superheater. The outlets are connected, with a flue gas inlet baffle between them. The second medium outlet 24 is also connected to the flue gas duct 93, with a flue gas outlet baffle between them. The inlet and outlet baffles control the flue gas flow rate. The high-temperature flue gas in the flue gas duct 93 enters the flue gas heat exchanger 2 through the second medium inlet 23 and exchanges heat with the low-temperature heating steam entering through the first medium inlet 21. The flue gas heats the low-temperature heating steam. After heat exchange, the flue gas returns to the flue gas duct 93 through the second medium outlet 24. The low-temperature heating steam reaches the required temperature after heat exchange and enters the high-pressure heating header 4 through the first medium outlet 22. The high-pressure heating header 4 and the medium-pressure heating header 3 are used to store and distribute heating steam, and can also play a certain buffering role when the heat load changes.

[0023] like Figure 1As shown, the first steam inlet 11 is connected to the hot reheat steam pipeline 91 via the first pipeline 61. The first pipeline 61 is equipped with a first inlet shut-off valve 611, a first extraction steam pressure reducing valve 612, and a first extraction steam regulating valve 613. The first extraction steam regulating valve 613 controls the extraction steam flow rate, the first extraction steam pressure reducing valve 612 reduces the extraction steam pressure to the required pressure, and the first inlet shut-off valve 611 controls whether the extraction steam is introduced into the steam-to-steam heat exchanger 1. The second steam inlet 13 is connected to the unit's high-pressure cylinder 92 via the second pipeline 62. The second pipeline 62 is equipped with a second inlet shut-off valve 621, a second extraction steam pressure reducing valve 622, and a second extraction steam regulating valve 623. The second extraction steam regulating valve 623 controls the extraction steam flow rate, the second extraction steam pressure reducing valve 622 reduces the extraction steam pressure to the required pressure, and the second inlet shut-off valve 621 controls whether the extraction steam is introduced into the steam-to-steam heat exchanger 1. The first medium inlet 21 is connected to the unit's high-pressure cylinder 92 through the third pipeline 63. The third pipeline 63 is equipped with a third inlet shut-off valve 631, a third extraction steam pressure reducing valve 632, and a third extraction steam regulating valve 633. The third extraction steam regulating valve 633 controls the extraction steam flow rate, the third extraction steam pressure reducing valve 632 reduces the extraction steam pressure to the required pressure, and the third inlet shut-off valve 631 controls whether the extraction steam is introduced into the flue gas heat exchanger 2.

[0024] like Figure 1 As shown, a first outlet shut-off valve 121 is installed on the pipe of the first steam outlet 12, a second outlet shut-off valve 141 is installed on the pipe of the second steam outlet 14, and a third outlet shut-off valve 221 is installed on the pipe of the first medium outlet 22. The outlet shut-off valves are installed to control the opening and closing of the outlets.

[0025] There is a heat exchange coupling phenomenon between the high and low temperature steam supply in the steam-steam heat exchanger 1. That is, the heat exchange flow rates of the high-temperature heating steam and the low-temperature heating steam should be maintained in a certain ratio. This is to prevent insufficient high-temperature steam flow to heat the higher-temperature heating steam flow to the required temperature when the heating demand is low, thus limiting the flexibility of the heating system. To improve system flexibility, the extraction steam flow rate of the second steam inlet 13 of the steam-steam heat exchanger 1 should match the high-temperature heating steam flow rate of the first steam inlet 11. This ensures that the high-temperature heating steam can heat the low-temperature heating steam to the required temperature. Low-temperature heating steam exceeding this flow ratio will be introduced into the flue gas heat exchanger 2, where it will be heated by the boiler's high-temperature flue gas. This ensures that the low-temperature heating steam reaches the temperature required for high pressure and is smoothly introduced into the high-pressure heating header 4, thereby improving the overall thermal efficiency and safety of the system. The first medium inlet 21 of the flue gas heat exchanger 2 is connected between the second extraction steam regulating valve 623 and the extraction steam outlet of the unit's high-pressure cylinder.

[0026] Steam-to-steam heat exchange system:

[0027] The low-temperature heating steam originates from the extraction steam of the high-pressure cylinder 92 of the unit. This steam passes through the second extraction steam regulating valve 623 and the second extraction steam pressure reducing valve 622, entering the steam-steam heat exchanger 1 through the second inlet shut-off valve 621 at the second steam inlet 13. Simultaneously, the high-temperature heating steam originates from the reheat steam pipeline 91, passes through the first extraction steam regulating valve 613 and the first extraction steam pressure reducing valve 612, and enters the steam-steam heat exchanger 1 through the first inlet shut-off valve 611 at the first steam inlet 11. After heat exchange, the low-temperature heating steam is heated to the required heating temperature by the reheat high-temperature heating steam, and enters the high-pressure heating header 4 after passing through the second outlet shut-off valve 141 of the second steam outlet 14 of the steam-steam heat exchanger 1. The high-temperature heating steam, still above the temperature required for medium-pressure heating, exits from the first outlet shut-off valve 121 of the first steam outlet 12 of the steam-steam heat exchanger 1, enters the steam cooler 5 to heat the boiler feedwater, cools it to the required temperature, and then enters the medium-pressure heating header 3. The regulating valve is used to control the flow rate of steam extracted for heating, while the pressure reducing valve reduces the pressure of the extracted steam to the pressure required for high and medium parameter heating.

[0028] Flue gas heat exchange system:

[0029] When the heating load is low, the high-temperature heating steam may not be able to heat all the low-temperature heating steam to the required temperature. In this case, the second extraction steam regulating valve 623 on the pipe at the second steam inlet 13 of the steam-steam heat exchanger 1 needs to be adjusted to control the inlet flow rate and ensure that the low-temperature heating steam can be fully heated to the required temperature by the high-temperature heating steam. The required additional high-parameter low-temperature heating steam enters the flue gas heat exchanger 2 through the second extraction steam regulating valve 623 and the second extraction steam pressure reducing valve 622 on the pipe at the first medium inlet 21 of the flue gas heat exchanger 2, and then enters the high-pressure heating header 4 through the third inlet shut-off valve 631 to exchange heat with the high-temperature flue gas. It then enters the high-pressure heating header 4 through the third outlet shut-off valve 221 of the first medium outlet 22. The flue gas originates from the flue gas outlet of the final superheater, and its flow rate is controlled by the flue gas inlet baffle. Flue gas enters the flue gas reheat system from the flue gas outlet of the final superheater, passes through the hot side flue gas inlet baffle of flue gas heat exchanger 2, enters flue gas heat exchanger 2, exchanges heat with steam, and then returns to the boiler flue through the hot side outlet baffle of flue gas heat exchanger 2.

[0030] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A high- and medium-parameter unit heating system for composite upgrading of low-quality steam, characterized in that, The system includes a steam-to-steam heat exchanger (1), a flue gas heat exchanger (2), a medium-pressure heating header (3), and a high-pressure heating header (4). The steam-to-steam heat exchanger (1) includes a first steam inlet (11), a first steam outlet (12) connected to the first steam inlet (11), a second steam inlet (13), and a second steam outlet (14) connected to the second steam inlet (13). The first steam inlet (11) is connected to a reheat steam pipeline (91), the first steam outlet (12) is connected to the medium-pressure heating header (3), and the second steam inlet (13) is connected to the high-pressure heating header of the unit. The cylinder (92) is connected, the second steam outlet (14) is connected to the high-pressure heating header (4), the flue gas heat exchanger (2) includes a first medium inlet (21), a first medium outlet (22) connected to the first medium inlet (21), a second medium inlet (23) and a second medium outlet (24) connected to the second medium inlet (23), the first medium inlet (21) is connected to the unit high-pressure cylinder (92), the first medium outlet (22) is connected to the high-pressure heating header (4), and the second medium inlet (23) is connected to the flue gas pipe (93).

2. The high- and medium-parameter unit heating system for low-quality steam composite upgrading according to claim 1, characterized in that, It also includes a steam cooler (5), which includes a third medium inlet (51), a third medium outlet (52) connected to the third medium inlet (51), a fourth medium inlet (53), and a fourth medium outlet (54) connected to the fourth medium inlet (53). The first steam outlet (12) is connected to the third medium inlet (51), the third medium outlet (52) is connected to the medium-pressure heating header (3), and the fourth medium inlet (53) is connected to the boiler feedwater pipeline (94).

3. The high- and medium-parameter unit heating system for low-quality steam composite upgrading according to claim 2, characterized in that, The first steam inlet (11) is connected to the hot reheat steam pipeline (91) through the first pipeline (61). The first pipeline (61) is equipped with a first inlet shut-off valve (611), a first extraction steam pressure reducing valve (612), and a first extraction steam regulating valve (613).

4. The high- and medium-parameter unit heating system for low-quality steam composite upgrading according to claim 1, characterized in that, The second steam inlet (13) is connected to the high-pressure cylinder (92) of the unit through the second pipe (62). The second pipe (62) is equipped with a second inlet shut-off valve (621), a second extraction steam pressure reducing valve (622) and a second extraction steam regulating valve (623).

5. The high- and medium-parameter unit heating system for low-quality steam composite upgrading according to claim 1, characterized in that, The first medium inlet (21) is connected to the high-pressure cylinder (92) of the unit through the third pipe (63). The third pipe (63) is equipped with a third inlet shut-off valve (631), a third extraction steam pressure reducing valve (632) and a third extraction steam regulating valve (633).

6. The high- and medium-parameter unit heating system for low-quality steam composite upgrading according to claim 1, characterized in that, The first steam outlet (12) is provided with a first outlet shut-off valve (121) on the pipeline, the second steam outlet (14) is provided with a second outlet shut-off valve (141) on the pipeline, and the first medium outlet (22) is provided with a third outlet shut-off valve (221) on the pipeline.

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