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CN-121977359-A - High-temperature flue gas waste heat recycling system

CN121977359ACN 121977359 ACN121977359 ACN 121977359ACN-121977359-A

Abstract

The invention relates to the technical field of energy conservation and environmental protection of coal-fired power generation, in particular to a high-temperature flue gas waste heat recycling system, which comprises a primary inlet of a high-temperature heat exchanger, wherein the primary inlet of the high-temperature heat exchanger is connected with a smoke exhaust pipeline of a reaction furnace, the high-temperature heat exchanger is provided with a constant-wall temperature control system in a coupling mode, the high-temperature heat exchanger is respectively connected with a waste heat generator and a hot water supply pipeline through the constant-wall temperature control system, a starting temperature threshold value is set by the constant-wall temperature control system, the wall surface temperature of a heat exchange surface is controlled to be always above the acid dew point temperature of flue gas, and the heat exchanger is guaranteed to be free from low-temperature corrosion and dust accumulation. The flue gas output side of the high-temperature heat exchanger is provided with a heat exchange pipeline and a flue gas bypass in parallel, the heat exchange pipeline between the high-temperature heat exchanger and the primary low-temperature heat exchanger is provided with a heat exchange valve and a heat exchange check valve, and heat energy is fully absorbed and utilized through the primary low-temperature heat exchanger and the secondary low-temperature heat exchanger. And a reheater is arranged between the secondary low-temperature heat exchanger and the flue gas bypass in a coupling way, so that the flue gas is heated to be above the condensation temperature, and the condensation corrosion of the chimney is effectively prevented. And the second-stage low-temperature heat exchanger is coupled with a heat pump combined supply module for heat exchange to obtain hot water and water for the terminal and refrigeration for the terminal.

Inventors

  • XU CHUNSHENG
  • XU XIAOHUI
  • CHENG CHUAN
  • GUO JUNLI
  • SUN XUEJIAN

Assignees

  • 江苏洋井环保服务有限公司

Dates

Publication Date
20260505
Application Date
20251222

Claims (8)

  1. 1. The high-temperature flue gas waste heat recycling system is characterized by comprising a high-temperature heat exchanger (3), wherein a primary inlet of the high-temperature heat exchanger is connected with a smoke exhaust pipeline (2) of a reaction furnace (1), the high-temperature heat exchanger is coupled with a constant-wall temperature control system (4), the constant-wall temperature control system comprises a controller, and the high-temperature heat exchanger is respectively connected with a waste heat generator (12) and a hot water supply pipeline (9) through the constant-wall temperature control system; The flue gas output side of the high-temperature heat exchanger (3) is provided with a heat exchange pipeline (302) and a flue gas bypass (301) in parallel, a heat exchange valve (321) and a heat exchange one-way valve (322) are arranged on the heat exchange pipeline between the high-temperature heat exchanger and the first-level low-temperature heat exchanger, the heat exchange pipeline (302) is sequentially provided with the first-level low-temperature heat exchanger (5) and the second-level low-temperature heat exchanger (501), a reheater (6) is arranged between the second-level low-temperature heat exchanger (501) and the flue gas bypass (301) in a coupling mode, the reheater heats flue gas to a temperature above the condensation temperature through heat exchange with the second-level low-temperature heat exchanger, the second-level low-temperature heat exchanger is provided with a heat pump combined supply module (8), the heat pump combined supply module (8) comprises a heat pump (801), the heat pump and the second-level low-temperature heat exchanger (501) and the first-level low-temperature heat exchanger (5) sequentially conduct primary heating and secondary heating on a water body in the hot water supply pipeline, and then terminal hot water is formed through final heating of the high-temperature heat exchanger (3).
  2. 2. The high-temperature flue gas waste heat recycling system according to claim 1, wherein the heat pump combined supply module (8) further comprises a refrigerant circulation loop (802) formed by the heat pump (801), a waste heat refrigerator (15) is arranged in the refrigerant circulation loop, the waste heat refrigerator (15) is connected with a cooling tower (14) through an air cooling pipeline, a water supply pump (13) is arranged at the bottom of the cooling tower, and the water supply pump is electrically connected with the waste heat generator (12).
  3. 3. The high-temperature flue gas waste heat recycling system according to claim 2, wherein a high-voltage frequency converter (11) is arranged between the waste heat generator (12) and the constant-wall temperature control system (4), and the waste heat generator is electrically connected with a power utilization terminal (10).
  4. 4. The high-temperature flue gas waste heat recycling system according to claim 3, wherein the waste heat refrigerator (15) supplies low-temperature heat energy in the high-temperature heat exchanger (3) to an evaporator of the waste heat refrigerator for preheating starting through the constant-wall temperature control system (4) and the high-temperature heat exchanger (3).
  5. 5. The high-temperature flue gas waste heat recycling system according to claim 4, wherein the waste heat refrigerator (15) is connected with the indoor refrigeration terminal in an outward circulating mode, a water outlet pipeline (803) and a water return pipeline (804) are arranged between the waste heat refrigerator and the indoor refrigeration terminal, a water outlet pump (831) is arranged on the water outlet pipeline, a water return pump (841) is arranged on the water return pipeline, the waste heat refrigerator (15) conveys low-temperature chilled water to the indoor refrigeration terminal (805) along the water outlet pipeline, and after heat absorption and temperature rising, the low-temperature chilled water flows back to the waste heat refrigerator to be cooled and circulated again, and the indoor refrigeration terminal is an air processing unit or a fan coil.
  6. 6. The high-temperature flue gas waste heat recycling system according to claim 1, wherein an electric dust collector (201), a first smoke exhaust valve (202) and a first temperature sensor (203) are sequentially arranged on a smoke exhaust pipeline between the reaction furnace and the inlet side of the high-temperature heat exchanger along the smoke outlet direction, and a second smoke exhaust valve (204), a second temperature sensor (205) and an induced draft fan (206) are sequentially arranged on the smoke exhaust pipeline at the outlet side of the high-temperature heat exchanger.
  7. 7. The high-temperature flue gas waste heat recycling system according to claim 1, wherein a flue gas bypass (301) is sequentially provided with a flue gas discharge valve (311), a first one-way valve (312) and a third temperature sensor (313) along the flue gas discharge direction, the flue gas bypass is arranged behind the third temperature sensor (313) and is provided with a first bypass (314) and a second bypass (317), the first bypass is connected with a chimney (7), the first bypass is provided with a first flue gas discharge valve (315), the second bypass (317) is connected with a heat exchange pipe in a reheater, the second bypass is provided with a second flue gas discharge valve (316), and an outlet pipeline of the heat exchange pipe of the reheater is connected with the chimney; The third temperature sensor (313) monitors the temperature of the flue gas in real time, the temperature of the flue gas is higher than the condensation temperature of the flue gas, the first flue gas outlet valve is started, and the flue gas is directly discharged along a chimney; The temperature of the flue gas is less than the condensation temperature of the flue gas, the second flue gas outlet valve is started, the flue gas is reheated by the reheater (6) and is heated to be above the condensation temperature, and the flue gas is discharged through a chimney.
  8. 8. The high-temperature flue gas waste heat recycling system according to claim 1, wherein a first water supply valve (902) is arranged between a water supply end (901) of the hot water supply pipeline (9) and the second low-temperature heat exchanger (501), a second water supply valve (903) is arranged on the hot water supply pipeline between the second low-temperature heat exchanger (501) and the first low-temperature heat exchanger (5), a second one-way valve (905) and a fourth temperature sensor (906) are sequentially arranged on the hot water supply pipeline between the first low-temperature heat exchanger and the constant-wall temperature control system along the water supply direction, and a third one-way valve (908) and a fifth temperature sensor (907) are sequentially arranged on the hot water supply pipeline between the constant-wall temperature control system and the hot water supply terminal (904) along the water supply direction.

Description

High-temperature flue gas waste heat recycling system Technical Field The invention relates to the technical field of energy conservation and environmental protection of coal-fired power generation, in particular to a high-temperature flue gas waste heat recycling system. Background The flue gas which is generated by heating furnaces, annealing furnaces and similar industrial furnaces (such as forging furnaces and heat treatment furnaces) and carries a large amount of heat has the temperature of 180-300 ℃ when the coal-fired heating furnaces directly discharge, and the direct discharge is equivalent to the discharge of about 10-18Nm3/kg of energy generated by burning coal; The flue gas temperature of the gas heating furnace reaches 150-250 ℃ when directly discharging, the direct discharge is equivalent to discharging energy generated by burning natural gas of about 10-12Nm3/m3, the flue gas temperature of the fuel heating furnace (diesel oil/heavy oil) reaches 160-280 ℃ when directly discharging, the direct discharge is equivalent to discharging energy generated by burning about 11-15Nm3/kg oil, the flue gas temperature of the annealing furnace (special for heat treatment) is 200-400 ℃ when directly discharging through a high-temperature annealing process, the direct discharge is equivalent to discharging about 500-2000Nm3/h of a small-sized furnace along with the fluctuation of the volume and the charging amount of a hearth, and the direct discharge can reach 5000-20000Nm3/h; the heat loss of smoke exhaust is essentially the energy of fuel which is not utilized, more coal, gas and oil are required to be consumed in the production to maintain the process temperature in the furnace, and the fuel purchasing cost is directly increased. In the calculation formula of the heat efficiency of the industrial furnace, the heat loss of the discharged smoke is the largest heat loss term (the heat loss accounts for 8% -30% in general), and the direct discharge can greatly lower the comprehensive heat efficiency of the furnace body, so that the energy utilization efficiency is low. Disclosure of Invention The invention aims to provide a high-temperature flue gas waste heat recycling system to solve the problems in the background art, the invention sets a starting temperature threshold value through a constant-wall temperature control system, the wall temperature of the heat exchange surface is controlled to be always above the acid dew point temperature of the flue gas, so that the heat exchanger is free from low-temperature corrosion and ash deposition. And the heat energy is fully absorbed and utilized by the primary low-temperature heat exchanger and the secondary low-temperature heat exchanger. The reheater is arranged between the secondary low-temperature heat exchanger and the flue gas bypass in a coupling way, so that the flue gas is heated to be above the condensation temperature, and the flue gas can be effectively prevented from condensation corrosion of a chimney. The two-stage low-temperature heat exchanger is coupled with a heat pump combined supply module for heat exchange to obtain the advantages of terminal hot water consumption and terminal refrigeration. The high-temperature flue gas waste heat recycling system comprises a high-temperature heat exchanger, wherein a primary inlet of the high-temperature heat exchanger is connected with a smoke exhaust pipeline of a reaction furnace, the high-temperature heat exchanger is coupled with a constant-wall temperature control system, the constant-wall temperature control system comprises a controller, and the high-temperature heat exchanger is respectively connected with a waste heat generator and a hot water supply pipeline through the constant-wall temperature control system; The flue gas output side of the high-temperature heat exchanger is provided with a heat exchange pipeline and a flue gas bypass in parallel, the heat exchange pipeline between the high-temperature heat exchanger and the first-level low-temperature heat exchanger is provided with a heat exchange valve and a heat exchange one-way valve, the heat exchange pipeline is provided with the first-level low-temperature heat exchanger and the second-level low-temperature heat exchanger in sequence, a reheater is arranged between the second-level low-temperature heat exchanger and the flue gas bypass in a coupling way, the reheater heats flue gas to a temperature higher than the condensation temperature through heat exchange with the second-level low-temperature heat exchanger, the second-level low-temperature heat exchanger is provided with a heat pump combined supply module in a coupling way, the heat pump combined supply module comprises a heat pump, the heat pump and the second-level low-temperature heat exchanger circularly exchange heat, the second-level low-temperature heat exchanger and the first-level low-temperature heat exchanger sequentially heat water in the hot water pipeline, and fina