A self-balancing reheating system for a waste incineration power station and its operation method

Abstract

The present invention provides a self-balancing reheating system for a waste incineration and disposal power station and an operation method thereof. The biogas does not directly enter the furnace for incineration, which will not affect the operation of the waste heat boiler, and avoids the problems of high-temperature corrosion of the reheater in the traditional in-furnace reheating method and the low economy of the out-of-furnace reheating unit. The landfill leachate treatment station is connected to the biogas storage tank; the biogas storage tank is connected to the biogas incineration furnace through a biogas booster fan; the steam outlet of the superheater is connected to the steam inlet of the high-pressure cylinder of the steam turbine; the steam outlet of the high-pressure cylinder of the steam turbine is connected to the low-temperature steam inlet of the low-temperature reheater; the low-temperature reheater is connected to the high-temperature reheater; the steam outlet of the high-temperature reheater is connected to the steam inlet of the intermediate and low-pressure cylinders of the steam turbine; the extraction steam outlet of the high-pressure cylinder of the steam turbine is connected to the extraction steam inlet of the low-temperature reheater; the exhaust steam outlet of the intermediate and low-pressure cylinders of the steam turbine is connected to the exhaust steam inlet of the condenser; the low-temperature reheater is connected to the deaerator; the condenser is connected to the deaerator through a condensate pump; the deaerator is connected to the superheater through a boiler feed pump.

Description

Technical Field

[0001] The present invention relates to a self - balancing reheating system for a waste incineration disposal power station and an operation method thereof. Background Art

[0002] Biogas is a by - product of a waste leachate treatment station. At present, biogas in domestic waste incineration disposal power stations is generally disposed of by torch combustion or direct incineration in the furnace. The following main problems exist:

[0003] 1. Disposing of biogas by torch combustion causes energy waste.

[0004] 2. Incinerating biogas in the furnace is a relatively common disposal method. The advantage is that energy can be effectively utilized. The disadvantages are that incinerating biogas in the furnace will cause problems such as local over - temperature and coking in the waste heat boiler; due to the limitation of the heat capacity of the waste heat boiler, the heat generated by the increased incineration of biogas in the furnace will squeeze the upstream waste incineration treatment volume, which may cause the waste incineration treatment volume not to meet the standard, further affecting the economic benefits of the power station.

[0005] Compared with non - reheating units, units using reheating technology can significantly improve efficiency. Currently, according to whether the reheater is arranged in the waste heat boiler, the existing reheating methods can be divided into in - furnace reheating and out - of - furnace reheating. The following problems exist in the existing reheating methods and operations:

[0006] 1. In - furnace reheating arranges the reheater in the waste heat boiler flue. After domestic waste is incinerated, a large amount of corrosive gases are generated, mainly the generation of chlorides. There are safety problems such as high - temperature corrosion in the reheater. The use of surfacing welding and other methods for the reheater leads to an increase in the complexity and investment of the waste heat boiler. Due to the above limitations, the outlet temperature of the reheater in the domestic in - furnace reheating method generally does not exceed 450°C.

[0007] 2. The reheater of the out - of - furnace reheating method is arranged outside the flue. Although it avoids safety problems such as high - temperature corrosion, it uses saturated steam from the steam drum of the waste heat boiler or extraction steam from the steam turbine to heat the low - temperature reheated steam. The increase in the reheated steam temperature is limited, and the outlet temperature of the reheater generally does not exceed 350°C, which is less economical than in - furnace reheating. Summary of the Invention

[0008] The purpose of the present invention is to overcome the above - mentioned deficiencies in the prior art, and provide a self - balancing reheating system for a waste incineration disposal power station with a reasonable structural design and an operation method thereof. Biogas does not directly enter the furnace for incineration, which will not affect the operation of the waste heat boiler, and avoids the high - temperature corrosion of the reheater in the traditional in - furnace reheating method and the low economic efficiency of the out - of - furnace reheating unit.

[0009] The technical solution adopted by the present invention to solve the above problems is as follows: A self-balancing reheating system for a waste incineration power station, which includes a waste leachate treatment station and a steam turbine generator set system; the steam turbine generator set system includes a superheater, a high-pressure cylinder of the steam turbine, a low-temperature reheater, a high-temperature reheater, a medium-low pressure cylinder of the steam turbine, a condenser, a condensate pump, a deaerator and a boiler feed pump; it is characterized in that: it further includes a biogas storage tank, a biogas booster fan, a combustion-supporting fan and a biogas incinerator; the gas outlet of the waste leachate treatment station is connected to the gas inlet of the biogas storage tank; the gas outlet of the biogas storage tank is connected to the gas inlet of the biogas booster fan; the gas outlet of the biogas booster fan is connected to the gas inlet of the biogas incinerator; the air outlet of the combustion-supporting fan is connected to the air inlet of the biogas incinerator; the high-temperature reheater is arranged in the biogas incinerator; the steam outlet of the superheater is connected to the steam inlet of the high-pressure cylinder of the steam turbine; the steam outlet of the high-pressure cylinder of the steam turbine is connected to the low-temperature steam inlet of the low-temperature reheater; the low-temperature steam outlet of the low-temperature reheater is connected to the steam inlet of the high-temperature reheater; the steam outlet of the high-temperature reheater is connected to the steam inlet of the medium-low pressure cylinder of the steam turbine; the extraction steam outlet of the high-pressure cylinder of the steam turbine is connected to the extraction steam inlet of the low-temperature reheater; the exhaust steam outlet of the medium-low pressure cylinder of the steam turbine is connected to the exhaust steam inlet of the condenser; the condensate outlet of the low-temperature reheater is connected to the water inlet of the deaerator; the condensate outlet of the condenser is connected to the water inlet of the condensate pump; the water outlet of the condensate pump is connected to the water inlet of the deaerator; the water outlet of the deaerator is connected to the water inlet of the boiler feed pump, and the water outlet of the boiler feed pump is connected to the water inlet of the superheater.

[0010] The superheater described in the present invention is built in the waste incineration furnace waste heat boiler.

[0011] An isolation valve is provided on the pipeline connecting the air inlet and outlet of the biogas booster fan of the present invention.

[0012] An isolation valve is provided on the pipeline connecting the water inlet and outlet of the condensate pump of the present invention.

[0013] An isolation valve is provided on the pipeline connecting the water inlet and outlet of the boiler feed pump of the present invention.

[0014] The steam turbine generator set system described in the present invention further includes a generator, and the generator is connected to the medium-low pressure cylinder of the steam turbine.

[0015] The main steam temperature at the steam outlet of the superheater described in the present invention is 450 °C.

[0016] The steam temperature at the low-temperature steam outlet of the low-temperature reheater described in the present invention is 300 - 350 °C.

[0017] The steam temperature at the steam outlet of the high-temperature reheater described in the present invention is higher than 450 °C.

[0018] There are two condensate pumps, boiler feed pumps, and biogas booster fans described in the present invention. During normal operation, one is in use and the other is in standby.

[0019] An operation method of a self-balancing reheating system for a waste incineration disposal power station, characterized in that the process is as follows:

[0020] The waste leachate treatment station stores biogas in the biogas storage tank; the biogas booster fan is started, and after the biogas is pressurized by the biogas booster fan, the biogas is transported to the biogas incinerator; at the same time, the combustion-supporting fan transports the combustion-supporting air to the biogas incinerator; the heat generated by the combustion of the biogas is absorbed by the high-temperature reheater built in the biogas incinerator;

[0021] The waste incinerator waste heat boiler operates normally, heating the feed water, and the feed water is heated to form superheated steam, which is transported to the high-pressure cylinder of the steam turbine through the superheater to do work; the steam after doing work leaves the high-pressure cylinder of the steam turbine and is transported to the low-temperature reheater for preliminary heating to form low-temperature reheated steam, and the low-temperature reheated steam is then transported to the high-temperature reheater for further heating to form high-temperature reheated steam; the high-temperature reheated steam is transported to the intermediate and low-pressure cylinders of the steam turbine to continue doing work, and the exhausted steam is discharged to the condenser to be condensed into condensate; the extraction steam from the high-pressure cylinder of the steam turbine is transported to the low-temperature reheater to be used as a heat source to heat the low-temperature reheated steam; the condensate of the low-temperature reheater is transported to the deaerator;

[0022] The condensate pump is started, and the condensate water comes out of the condenser and is transported to the deaerator after being pressurized by the condensate pump; the boiler feed pump is started, and the feed water comes out of the deaerator and is transported to the superheater after being pressurized by the boiler feed pump.

[0023] Compared with the prior art, the present invention has the following advantages and effects:

[0024] 1. The biogas is disposed of through an external independent biogas incinerator, and the biogas does not enter the incinerator, making the waste incineration treatment volume more stable and the operation of the waste heat boiler safer, avoiding problems such as local overheating of the waste heat boiler caused by the combustion of biogas in the furnace.

[0025] 2. The present invention combines the heat energy generated by the combustion of biogas with waste incineration power generation, thus ensuring the full and effective utilization of the heat energy generated by the combustion of biogas. The biogas incinerator is equipped with a high-temperature reheater to fully and effectively utilize the heat energy generated by the combustion of biogas. Since the biogas combustion temperature is relatively high, the temperature rise of the reheated steam can be significantly increased. The outlet temperature of the high-temperature reheater is allowed to exceed 450°C, breaking through the temperature limits of traditional in-furnace reheating and out-of-furnace reheating. The high-temperature and efficient reheating scheme makes the power generation efficiency higher, meeting the relevant national policies, and there is no problem of high-temperature corrosion of the reheater, avoiding the problems of high-temperature corrosion of the reheater in the traditional in-furnace reheating method and the low economy of the out-of-furnace reheating unit.

[0026] 3. The waste incinerator and the biogas incinerator adopt a coupled self-balancing operation mode. Even if one of them deviates from the design conditions, the system can spontaneously reach a new stable operation condition, realizing the self-balancing operation function of the system and having the operability of the actual system. Brief Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. Detailed Embodiment

[0028] The present invention will be further described in detail below with reference to the drawings and through embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0029] The embodiment of the present invention includes a landfill leachate treatment station 1, a biogas storage tank 2, a biogas booster fan 3, a combustion-supporting fan 4, a biogas incinerator 5, a steam turbine generator system, and a chimney 16.

[0030] The air outlet of the landfill leachate treatment station 1 and the air inlet of the biogas storage tank 2 are connected through a first biogas pipeline L01; the air outlet of the biogas storage tank 2 and the air inlet of the biogas booster fan 3 are connected through a second biogas pipeline L02; the air outlet of the biogas booster fan 3 and the air inlet of the biogas incinerator 5 are connected through a third biogas pipeline L03; the air outlet of the combustion-supporting fan 4 and the air inlet of the biogas incinerator 5 are connected through an air pipeline L04. Isolation valves are provided on the pipelines connecting the air inlet and air outlet of the biogas booster fan 3, and a pneumatic quick shut-off valve is installed on the third biogas pipeline L03.

[0031] The steam turbine generator system includes a superheater 6, a high-pressure cylinder 7 of the steam turbine, a low-temperature reheater 8, a high-temperature reheater 9, a medium-low pressure cylinder 10 of the steam turbine, a generator 11, a condenser 12, a condensate pump 13, a deaerator 14, and a boiler feed pump 15. The high-temperature reheater 9 is arranged in the biogas incinerator 5. The low-temperature reheater 8 is built in the steam-steam heat exchanger.

[0032] The steam outlet of the superheater 6 and the steam inlet of the high-pressure cylinder 7 of the steam turbine are connected through a main steam pipeline L05; the flue gas outlet of the superheater 6 and the chimney 16 are connected through a first flue gas pipeline L015.

[0033] The steam outlet of the high-pressure cylinder 7 of the steam turbine and the low-temperature steam inlet of the low-temperature reheater 8 are connected through a first low-temperature reheating pipeline L06; the low-temperature steam outlet of the low-temperature reheater 8 and the steam inlet of the high-temperature reheater 9 are connected through a second low-temperature reheating pipeline L07; the steam outlet of the high-temperature reheater 9 and the steam inlet of the medium-low pressure cylinder 10 of the steam turbine are connected through a high-temperature reheating pipeline L08; the extraction steam outlet of the high-pressure cylinder 7 of the steam turbine and the extraction steam inlet of the low-temperature reheater 8 are connected through an extraction pipeline L09.

[0034] The exhaust steam outlet of the intermediate and low pressure cylinders 10 of the steam turbine is connected to the exhaust steam inlet of the condenser 12; the condensate outlet of the low-temperature reheater 8 and the water inlet of the deaerator 14 are connected through the drain pipe L010; the condensate outlet of the condenser 12 and the water inlet of the condensate pump 13 are connected through the first condensate pipe L011; the water outlet of the condensate pump 13 and the water inlet of the deaerator 14 are connected through the second condensate pipe L012; the water outlet of the deaerator 14 and the water inlet of the boiler feed pump 15 are connected through the first feed pipe L013, and the water outlet of the boiler feed pump 15 and the water inlet of the superheater 6 are connected through the second feed pipe L014.

[0035] The smoke outlet of the biogas incinerator 5 and the chimney 16 are connected through the second flue gas pipe L016.

[0036] Isolation valves are provided on the pipelines connecting the water inlets and outlets of the condensate pump 13 and the boiler feed pump 15.

[0037] The generator 11 is connected to the intermediate and low pressure cylinders 10 of the steam turbine.

[0038] There are two condensate pumps 13, two boiler feed pumps 15, and two biogas booster fans 3. One is used and the other is in standby during normal operation.

[0039] An operation method of a self-balancing reheating system for a waste incineration power station is as follows:

[0040] The waste leachate treatment station 1 stores biogas in the biogas storage tank 2 through the first pipeline L01. The biogas booster fan 3 (one of them, and the other is in hot standby) is started. After being pressurized by the biogas booster fan 3, it is transported to the biogas incinerator 5 through the third biogas pipe L03. At the same time, the combustion air blower 4 transports the combustion air to the biogas incinerator 5 through the air pipeline L04. The heat generated by the combustion of biogas is absorbed by the high-temperature reheater 9 built in the biogas incinerator 5, and the cooled flue gas is discharged to the atmosphere through the flue gas pipeline and the chimney 16.

[0041] The waste incinerator waste heat boiler operates normally to heat the feed water, and the flue gas is discharged to the atmosphere through the flue gas pipeline and the chimney 16. The feed water is heated to form superheated steam, which enters the high-pressure cylinder 7 of the steam turbine through the superheater 6 and the main steam pipeline L05 to do work. The steam after doing work leaves the high-pressure cylinder 7 of the steam turbine, is preliminarily heated through the first low-temperature reheating pipeline L06 to the low-temperature reheater 8, and then further heated through the second low-temperature reheating pipeline L07 to the high-temperature reheater 9 built in the biogas incinerator 5 to form high-temperature reheated steam. The high-temperature reheated steam enters the intermediate and low pressure cylinders 10 of the steam turbine through the eighth pipeline L08 to continue doing work, and the exhausted steam is discharged into the condenser 12 and condensed into condensate. The extraction steam from the high-pressure cylinder 7 of the steam turbine enters the low-temperature reheater 8 through the ninth pipeline L09 as the heating steam source to heat the low-temperature reheated steam. The condensate of the extraction steam is transported to the deaerator 14 through the tenth pipeline L010.

[0042] Start the condensate pump 13 (one of them, the other is in hot standby). The condensate water comes out of the condenser 12 and is transported to the deaerator 14 after being pressurized by the condensate pump 13. Start the boiler feed pump 15 (one of them, the other is in hot standby). The feed water comes out of the deaerator 14 and is transported to the superheater 6 after being pressurized by the boiler feed pump 15.

[0043] This embodiment can operate in a unit system, or multiple waste heat boilers and multiple steam turbines can operate in parallel respectively, and the thermal system can be a header system.

[0044] The main steam temperature at the steam outlet of the superheater 6 is 450 °C, which is a constant value. The steam temperature at the low-temperature steam outlet of the low-temperature reheater 8 is an adjustable value between 300 - 350 °C, and the rated value is 320 °C (which can be adjusted and determined according to the actual project situation). The steam temperature at the steam outlet of the high-temperature reheater 9 is a certain constant value higher than 450 °C (calculated according to the biogas incineration disposal volume of the project). In this embodiment, it is tentatively set as 500 °C.

[0045] Embodiment 1: Design the rated working condition. The amount of garbage to be disposed of in the project has been determined, and the corresponding biogas production is calculated according to relevant calculations, so as to configure the thermal system and parameters. In this embodiment, the main steam parameters at the outlet of the superheater 6 are constantly 13 Mpa.g / 450 °C. The rated value of the steam temperature at the outlet of the low-temperature reheater 8 is 320 °C, and the outlet temperature of the high-temperature reheater 9 is constantly 500 °C.

[0046] Embodiment 2: Actual operating condition. When the actual biogas production is greater than the designed value. The output of the waste incinerator remains unchanged, and the main steam flow rate and parameters at the outlet of the superheater 6 remain unchanged. The system automatically reduces the extraction steam volume of the high-pressure cylinder to increase the flow rate of the reheating system. The decrease in the extraction steam volume of the high-pressure cylinder leads to a decrease in the load of the low-temperature reheater 8. Therefore, the outlet temperature of the low-temperature reheater 8 will be lower than the rated design value of 320 °C. The system sets the outlet temperature of the high-temperature reheater 9 at 500 °C as a constant. Therefore, the temperature difference of the reheated steam in the high-temperature reheater 9 increases, and at the same time, the flow rate increases. The increased load matches the increase in the actual biogas disposal volume. The system automatically adjusts to a new balance state. That is, the increase in biogas production is ultimately achieved through the increase in the reheated steam flow rate and the increase in the output of the intermediate and low-pressure cylinders 10 of the steam turbine.

[0047] Embodiment 3: The counterexample of Embodiment 2. When the actual biogas production is less than the designed value, the main steam flow rate and parameters at the outlet of the superheater 6 remain unchanged. The system automatically increases the extraction steam volume of the high-pressure cylinder to reduce the flow rate of the reheating system. The load of the low-temperature reheater 8 increases. Therefore, the outlet temperature of the low-temperature reheater 8 will be higher than the rated design value of 320 °C. At this time, the temperature difference of the reheated steam in the high-temperature reheater 9 decreases, and at the same time, the flow rate decreases. The reduced load matches the decrease in the actual biogas disposal volume. A new balance state is reached.

[0048] Embodiment 4: The waste incinerator is in a variable load state, and there is a lag in the change of biogas production, which is quite different from the design conditions. At this time, it is necessary to adjust the amount of biogas entering the biogas incinerator 5 through the biogas storage tank 2. Coarse adjustment is carried out to make the load of the biogas furnace basically match the load of the waste incinerator, and then fine adjustment is carried out through the self-balancing of the system.

[0049] In addition, it should be noted that for the specific embodiments described in this specification, the shapes and names of their components can be different. The above content described in this specification is only an example of the structure of the present invention. Any equivalent changes or simple changes made according to the structure, features and principles conceived in the present invention are included in the protection scope of the present invention. Those skilled in the art to which the present invention pertains can make various modifications, supplements or use similar methods for substitution to the specific embodiments described, as long as they do not deviate from the structure of the present invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.

Claims

1. A self-balancing reheating system for a waste incineration disposal power station, comprising a waste leachate treatment station and a steam turbine generator set system; the steam turbine generator set system includes a superheater, a high-pressure cylinder of the steam turbine, a low-temperature reheater, a high-temperature reheater, a medium-low pressure cylinder of the steam turbine, a condenser, a condensate pump, a deaerator and a boiler feed pump; it is characterized in that: It also includes a biogas storage tank, a biogas booster fan, a combustion air blower, and a biogas incinerator; the gas outlet of the landfill leachate treatment station is connected to the gas inlet of the biogas storage tank; the gas outlet of the biogas storage tank is connected to the gas inlet of the biogas booster fan; the gas outlet of the biogas booster fan is connected to the gas inlet of the biogas incinerator; the air outlet of the combustion air blower is connected to the air inlet of the biogas incinerator; the high-temperature reheater is arranged inside the biogas incinerator; the steam outlet of the superheater is connected to the steam inlet of the high-pressure cylinder of the steam turbine; the steam outlet of the high-pressure cylinder of the steam turbine is connected to the low-temperature steam inlet of the low-temperature reheater; the low-temperature steam outlet of the low-temperature reheater is connected to the steam inlet of the high-temperature reheater; the steam outlet of the high-temperature reheater is connected to the steam inlet of the intermediate and low-pressure cylinders of the steam turbine; the extraction steam outlet of the high-pressure cylinder of the steam turbine is connected to the extraction steam inlet of the low-temperature reheater; the exhaust steam outlet of the intermediate and low-pressure cylinders of the steam turbine is connected to the exhaust steam inlet of the condenser; the condensate outlet of the low-temperature reheater is connected to the water inlet of the deaerator; the condensate outlet of the condenser is connected to the water inlet of the condensate pump; the water outlet of the condensate pump is connected to the water inlet of the deaerator; the water outlet of the deaerator is connected to the water inlet of the boiler feed pump, and the water outlet of the boiler feed pump is connected to the water inlet of the superheater; the superheater is built in the waste incinerator waste heat boiler; isolation valves are arranged on the pipelines connecting the air inlet and outlet of the biogas booster fan; isolation valves are arranged on the pipelines connecting the water inlet and outlet of the condensate pump; isolation valves are arranged on the pipelines connecting the water inlet and outlet of the boiler feed pump; the steam turbine generator set system also includes a generator, and the generator is connected to the intermediate and low-pressure cylinders of the steam turbine.

2. The self-balancing reheating system for a waste incineration power station according to claim 1, wherein: There are two condensate pumps, two boiler feed pumps, and two biogas booster fans, with one in use and one in standby during normal operation.

3. A method for operating the self-balancing reheating system of a waste incineration disposal power station according to claim 1 or 2, characterized in that: The process is as follows: The landfill leachate treatment station stores biogas in the biogas storage tank; the biogas booster fan is started, and after the biogas is pressurized by the biogas booster fan, it is transported to the biogas incinerator; at the same time, the combustion air blower transports combustion air to the biogas incinerator; the heat generated by the combustion of biogas is absorbed by the high-temperature reheater arranged inside the biogas incinerator. The waste incinerator waste heat boiler operates normally, heating the feed water, and the feed water is heated to form superheated steam, which is transported to the high-pressure cylinder of the steam turbine through the superheater to do work; the steam after doing work leaves the high-pressure cylinder of the steam turbine and is transported to the low-temperature reheater for preliminary heating to form low-temperature reheated steam, and the low-temperature reheated steam is then transported to the high-temperature reheater for further heating to form high-temperature reheated steam; the high-temperature reheated steam is transported to the intermediate and low-pressure cylinders of the steam turbine to continue doing work, and the exhaust steam is discharged into the condenser to be condensed into condensate; the extraction steam of the high-pressure cylinder of the steam turbine is transported to the low-temperature reheater to heat the low-temperature reheated steam as a heat source; the condensate of the low-temperature reheater is transported to the deaerator. The condensate pump is started, and the condensate water comes out of the condenser and is transported to the deaerator after being pressurized by the condensate pump. The boiler feed pump is started, and the feed water comes out of the deaerator and is transported to the superheater after being pressurized by the boiler feed pump.

Images