Carbon calcination flue gas cold, heat, electricity triple supply waste heat utilization system

Abstract

The application discloses a carbon calcination flue gas "cold, heat and electricity" triple supply waste heat utilization system, which comprises a main power supply unit, a reheating power supply unit, a refrigeration unit, a steam heat supply unit, a circulating water unit and a steam distribution cylinder. A plurality of calcination furnaces are divided into two paths by a mother flue, and the flue gas is respectively input into the main power supply unit and the reheating power supply unit, and then the flue gas is supplied to a generator through a steam turbine to generate electricity. The steam output pipelines of the main power supply unit and the reheating power supply unit are connected to the steam distribution cylinder. The steam of the steam distribution cylinder is respectively output to the refrigeration unit, the steam heat supply unit and the heat exchange circulating unit. The output pipelines of the heat exchange circulating unit are respectively connected back to the main power supply unit and the reheating power supply unit, so that the calcination flue gas cold, heat and electricity triple supply waste heat circulation recycling is completed. The application efficiently utilizes the waste heat of the tank furnace flue gas, provides a stable and reliable cold, heat and electricity triple supply system, reduces the energy loss in the heat utilization process, realizes the step-by-step utilization of energy, improves the steam power generation capacity and the recovery efficiency.

Description

Technical Field

[0001] This invention relates to the field of flue gas waste heat utilization technology, specifically to a combined cooling, heating, and power system for carbon calcination flue gas waste heat utilization. Background Technology

[0002] Prebaked anodes for aluminum electrolysis are one of the main materials in aluminum electrolysis production, often referred to as the "heart" of the electrolytic cell. Prebaked anodes are manufactured using petroleum coke as aggregate and pitch as a binder. After high-temperature calcination, raw petroleum coke produces calcined coke, which generates a large amount of high-temperature flue gas at 800–1050°C. The calcined coke is crushed and screened, then mixed with other materials, stirred and kneaded with molten pitch, and finally fired and cleaned to become the finished carbon product. Heating is required during the kneading and molding process and the melting of the pitch; the heating medium is often heat transfer oil. Therefore, the waste heat from the high-temperature flue gas generated during calcination must first meet the heat requirements for heating the prebaked anodes.

[0003] Currently, the steam utilization rate of waste heat pipe steam boilers is not high, and the steam power generation capacity and efficiency are low. It cannot be efficiently converted into other power recovery and utilization. For example, the steam discharged from the waste heat pipe steam boiler is generally used for bathroom steam, etc. Bathroom steam use is intermittent, but the steam production of the waste heat pipe steam boiler is continuous. When the bathroom is not in use, the steam in the waste heat pipe steam boiler will be discharged, resulting in waste, or the waste heat pipe steam boiler will operate at low load. The consequence of low load operation is that the flue gas temperature is too high, which is very detrimental to the induced draft fan downstream of the system.

[0004] Some carbon plants have large office buildings and dormitories, which require a lot of cooling in the hot summer. In the past, they usually used split air conditioners for cooling, without utilizing the waste heat of flue gas to convert into energy, which also resulted in energy waste. Summary of the Invention

[0005] In view of the above-mentioned shortcomings and deficiencies, the present invention provides a combined cooling, heating and power (CCHP) waste heat utilization system for carbon calcination flue gas. The purpose is to efficiently utilize the waste heat of the remaining flue gas after meeting the heat requirements for prebaked anode production, provide a stable and reliable combined cooling, heating and power system, reduce energy loss during heat utilization, and realize the cascade utilization of energy.

[0006] To achieve the above objectives, the main technical solution adopted in this invention includes: a main power supply unit, a reheat power supply unit, a refrigeration unit, a steam heating unit, a circulating water unit, and a steam distribution cylinder. Multiple calcining furnaces are divided into two paths through a mother flue, and the flue gas is respectively input to the main power supply unit and the reheat power supply unit, and then fed by a steam turbine to generate electricity. Part of the steam output pipelines of the main power supply unit and the reheat power supply unit are connected to the steam distribution cylinder. The steam from the steam distribution cylinder is respectively output to the refrigeration unit, the steam heating unit, and the heat exchange circulation unit. The output pipelines of the heat exchange circulation unit are respectively connected back to the main power supply unit and the reheat power supply unit, thus completing the combined cooling, heating, and power supply of calcining flue gas and the recycling of waste heat.

[0007] The waste heat power generation boiler of the main power supply unit receives the flue gas generated by the calcining furnace. The flue gas is converted into steam after exchanging heat with the deoxygenated water output from the heat exchange circulation unit. The steam is divided into two paths: one path is sent to the high-pressure end of the steam turbine to power the generator, and the other path is sent to the steam distribution cylinder through the first pressure reducing device.

[0008] The reheat power supply unit includes a waste heat thermal oil furnace, a waste heat heat pipe steam boiler, a boiler reheater, and a dehumidification device. The waste heat thermal oil furnace receives the flue gas generated by the calcining furnace. The flue gas is converted into steam by the waste heat heat pipe steam boiler and then divided into two paths. One path of the steam is sent to the steam distribution cylinder through the second pressure reducing device. The other path is sent to the boiler reheater and then divided into two paths. One path of the reheated steam is sent to the intermediate pressure end of the steam turbine through the dehumidification device to supply power to the generator. The other path is sent to the steam distribution cylinder through the third pressure reducing device.

[0009] The turbine is equipped with an extraction pipe connected to the steam distribution cylinder at the low-pressure end.

[0010] The heat exchange circulation unit includes a circulating water pipeline, a condenser, and a deaerator. The steam-water mixture generated by the turbine flows to the condenser through the pipeline. The circulating water in the circulating water pipeline flowing through the condenser serves as the cooling medium for the condenser, converting the steam-water mixture into condensate. The condensate flows to the deaerator to undergo deaeration to form deoxygenated water. The deoxygenated water is divided into two streams and fed into the waste heat power generation boiler of the main power supply unit and the waste heat heat pipe steam boiler of the reheat power supply unit, respectively.

[0011] The heat exchange circulation unit also includes a heat exchanger that receives steam from the steam distribution cylinder. The circulating water in the circulating water pipeline serves as the cooling medium for the heat exchanger, converting the steam into condensate. The condensate flows to the deaerator to perform deaeration, forming deoxygenated water. The deoxygenated water is divided into two streams and fed into the waste heat power generation boiler of the main power supply unit and the waste heat heat pipe steam boiler of the reheat power supply unit, respectively.

[0012] The present invention has the following beneficial effects and advantages:

[0013] 1. High-temperature flue gas in the mother flue enters the waste heat power generation boiler and the waste heat thermal oil furnace + waste heat heat pipe steam boiler respectively. The main steam generated by the waste heat power generation boiler enters the steam turbine to generate electricity; the steam generated by the waste heat heat pipe steam boiler is reheated and fed into the intermediate pressure end of the steam turbine to generate electricity, thereby improving the steam power generation capacity and recovery efficiency.

[0014] 2. In order to ensure the continuous supply of cooling and heating and to avoid the inability to operate normally during turbine maintenance or accidents, this invention sets up a backup steam source. The main steam and reheat steam enter the steam distribution cylinder through the pressure reducing device for steam redistribution, so as to ensure the stable operation of cooling and heating.

[0015] 3. By utilizing the existing turbine circulating water system, the turbine circulating water is used as the cooling medium for the steam-water heat exchanger, which cools the excess steam in the steam distribution cylinder into condensate. The condensate is then fed into the deaerator for recycling, achieving the goal of recycling and saving resources.

[0016] 4. To prevent the reheat steam temperature from being too low during the low-load operation of the waste heat power generation boiler, which could lead to water hammer in the turbine, a dehumidification device is installed before the reheat steam is sent to the turbine to ensure the safe and stable operation of the turbine. Attached Figure Description

[0017] Figure 1 This is a system flowchart of the present invention.

[0018] The components include: 1. Waste heat power generation boiler; 1.1 Boiler reheater; 2. Waste heat thermal oil boiler; 3. Waste heat heat pipe steam boiler; 4. Steam turbine; 5. Generator; 6. Condenser; 7.1 First pressure reducing device; 7.2 Second pressure reducing device; 7.3 Third pressure reducing device; 8. Steam distributor; 9. Heat exchanger; 10. Main steam pipeline to the steam turbine; 10.1 Pressure-reducing steam pipeline to the steam distributor; 11. Low-temperature reheat steam pipeline; 11.1 Low-temperature reheat steam to pressure-reducing steam distributor; 12. High-temperature reheat steam pipeline; 12.1 High-temperature reheat steam to pressure-reducing steam distributor; 13. Extraction steam pipeline; 14. Steam pipeline to the refrigeration unit; 15. Steam pipeline to the heating unit; 16. Steam pipeline to the heat exchanger; 17. Circulating water pipeline; 18. Dehumidification device; 19. Deoxygenation device. Detailed Implementation

[0019] The invention will now be further described with reference to the accompanying drawings. Figure 1As shown, this invention is a combined cooling, heating, and power (CCHP) waste heat utilization system for carbon calcination flue gas. Its features include: a main power supply unit, a reheat power supply unit, a refrigeration unit, a steam heating unit, a heat exchange circulation unit, and a steam distribution cylinder. Multiple calcination furnaces are divided into two paths via a mother flue, with flue gas fed into the main power supply unit and the reheat power supply unit respectively. The flue gas is then fed into a generator 5 via a steam turbine 4. Part of the steam output pipelines from the main power supply unit and the reheat power supply unit are connected to the steam distribution cylinder 8. The flue gas from the steam distribution cylinder 8 is output to the refrigeration unit (in this embodiment, an absorption chiller unit) via a steam pipeline 14 to the refrigeration unit, to the steam heating unit (in this embodiment, steam heating) via a steam pipeline 15, and to the heat exchange circulation unit. The output pipelines of the heat exchange circulation unit are connected back to the main power supply unit and the reheat power supply unit, thus completing the combined cooling, heating, and power waste heat recycling system for calcination flue gas.

[0020] The waste heat power generation boiler 1 of the main power supply unit receives the flue gas generated by the calcining furnace. The flue gas is converted into steam after exchanging heat with the deoxygenated water output by the heat exchange circulation unit. The steam is divided into two paths. One path is transported to the high-pressure end of the turbine 4 through the main steam pipeline 10 to power the generator 5. The other path is transported to the steam distributor 8 through the first pressure reducing device 7.1 and the pressure reducing steam pipeline 10.1 to the steam distributor 8.

[0021] The reheat power supply unit includes a waste heat thermal oil furnace 2, a waste heat heat pipe steam boiler 3, a boiler reheater 1.1, and a dehumidification device 18. The waste heat thermal oil furnace 2 receives the flue gas generated by the calcining furnace. The flue gas is converted into steam by the waste heat heat pipe steam boiler 3 and then split into two paths. One path of steam is transported to the steam distributor 8 via the second pressure reducing device 7.2 and the low-temperature reheat steam to the steam distributor pressure reducing steam pipeline 11.1. The other path is transported to the boiler reheater 1.1 via the low-temperature reheat steam pipeline 11 and then split into two paths. One path of the reheated steam is transported to the intermediate pressure end of the steam turbine 4 via the high-temperature reheat steam pipeline 12 and the dehumidification device 18 to power the generator 5. The other path is transported to the steam distributor 8 via the third pressure reducing device 7.3 and the high-temperature reheat steam to the steam distributor pressure reducing steam pipeline 12.1.

[0022] The steam turbine 4 is equipped with an extraction pipe 13 connected to the steam distributor cylinder 8 at the low-pressure end.

[0023] The heat exchange circulation unit includes a circulating water pipeline 17, a condenser 6, and a deaerator 19. The steam-water mixture generated by the turbine 4 flows to the condenser 6 through the pipeline. The circulating water in the circulating water pipeline 17 flowing through the condenser 6 serves as the cooling medium for the condenser 6, converting the steam-water mixture into condensate. The condensate flows to the deaerator 19 for deaeration to form deoxygenated water. The deoxygenated water is divided into two streams and fed into the waste heat power generation boiler 1 of the main power supply unit and the waste heat heat pipe steam boiler 3 of the reheat power supply unit, respectively.

[0024] The heat exchange circulation unit also includes a heat exchanger 9, which receives steam delivered by the steam distribution cylinder 8. The circulating water in the circulating water pipeline 17 serves as the cooling medium for the heat exchanger 9, converting the steam into condensate. The condensate flows to the deaerator 19 to perform deaeration, forming deoxygenated water. The deoxygenated water is divided into two streams and fed into the waste heat power generation boiler 1 of the main power supply unit and the waste heat heat pipe steam boiler 3 of the reheat power supply unit, respectively.

[0025] The usage process and principle of this invention are as follows: The main power supply unit and the reheat power supply unit respectively receive the flue gas from the calcining furnace and the deoxygenated water output from the heat exchange circulation unit. The high-temperature flue gas from the waste heat power generation boiler 1 and the waste heat heat pipe steam boiler 3 exchanges heat with the deoxygenated water to obtain hot steam, which enters the steam turbine 4. The steam thermal energy at the high-pressure end and the medium-pressure end of the steam turbine 4 is converted into mechanical energy and then into electrical energy for power generation. The steam extracted by the steam turbine 4 is fed to the steam distribution cylinder 8 and then input to the refrigeration unit and the steam heating unit for refrigeration or heating. The depressurized steam serves as a backup gas source for the steam turbine extraction to ensure that the refrigeration unit and the steam heating unit can perform refrigeration or heating.

Claims

1. A combined cooling, heating, and power system for carbon calcination flue gas waste heat utilization, characterized in that: It includes a main power supply unit, a reheat power supply unit, a refrigeration unit, a steam heating unit, a circulating water unit, and a steam distribution cylinder. Multiple calcining furnaces are divided into two paths through a mother flue, which feed flue gas into the main power supply unit and the reheat power supply unit respectively. The steam generated by the main power supply unit and the reheat power supply unit is powered by a steam turbine to generate electricity. Part of the steam from the main power supply unit and the reheat power supply unit is sent to the steam distribution cylinder through pipelines. The steam from the steam distribution cylinder is output to the refrigeration unit, the steam heating unit, and the heat exchange circulation unit respectively. The output pipeline of the heat exchange circulation unit is connected back to the main power supply unit and the reheat power supply unit respectively, thus completing the combined cooling, heating, and power supply of calcining flue gas and waste heat recycling. The reheat power supply unit includes a waste heat thermal oil furnace, a waste heat heat pipe steam boiler, a boiler reheater, and a dehumidification device. The waste heat thermal oil furnace receives the flue gas generated by the calcining furnace. The flue gas discharged from the waste heat thermal oil furnace is converted into steam by the waste heat heat pipe steam boiler. The steam is divided into two paths. One path of the steam is sent to the steam distribution cylinder through the second pressure reducing device. The other path is sent to the boiler reheater and then divided into two paths. One path of the reheated steam is sent to the intermediate pressure end of the steam turbine through the dehumidification device to supply the generator for power generation. The other path of the reheated steam is sent to the steam distribution cylinder through the third pressure reducing device.

2. The carbon calcination flue gas combined cooling, heating, and power waste heat utilization system according to claim 1, characterized in that: The waste heat power generation boiler of the main power supply unit receives the flue gas generated by the calcining furnace. After exchanging heat with the deoxygenated water output by the heat exchange circulation unit, the flue gas converts the deoxygenated water into steam. The steam is divided into two paths: one path is sent to the high-pressure end of the steam turbine to power the generator, and the other path is sent to the steam distribution cylinder through the first pressure reducing device.

3. The carbon calcination flue gas combined cooling, heating, and power waste heat utilization system according to claim 1, characterized in that: The turbine is equipped with an extraction pipe connected to the steam distribution cylinder at the low-pressure end.

4. The carbon calcination flue gas combined cooling, heating, and power waste heat utilization system according to claim 2, characterized in that: The heat exchange circulation unit includes a circulating water pipeline, a condenser, and a deaerator. The steam-water mixture generated by the turbine flows to the condenser through the pipeline. The circulating water in the circulating water pipeline flowing through the condenser serves as the cooling medium for the condenser, converting the steam-water mixture into condensate. The condensate flows to the deaerator to undergo deaeration to form deoxygenated water. The deoxygenated water is divided into two streams and fed into the waste heat power generation boiler of the main power supply unit and the waste heat heat pipe steam boiler of the reheat power supply unit, respectively.

5. The carbon calcination flue gas combined cooling, heating, and power waste heat utilization system according to claim 4, characterized in that: The heat exchange cycle unit also includes a heat exchanger, which receives steam delivered by the steam distribution cylinder. The circulating water in the circulating water pipeline serves as the cooling medium for the heat exchanger, converting the steam into condensate. The condensate flows to the deaerator.

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