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WO-2026093385-A1 - METHOD FOR UTILIZING HEAT FROM A SECONDARY CIRCUIT OF A GEOTHERMAL SYSTEM

WO2026093385A1WO 2026093385 A1WO2026093385 A1WO 2026093385A1WO-2026093385-A1

Abstract

The invention relates to a method for utilizing heat from a secondary circuit (15) of a geothermal system (1), said method comprising: (a) heating a heat transfer medium flowing through the secondary circuit (15) to a temperature in the region of 120°C to 300°C by transferring heat from hot brine (3) from a geothermal source; (b) evaporating water (35) in a first evaporator (33) by transferring heat from at least one portion of the heated heat transfer medium (31), wherein the at least one portion of the heat transfer medium is cooled to a temperature in the region of 80°C to 140°C; (c) generating steam by using the heat of the heat transfer medium (37) cooled to a temperature in the region of 80°C to 140°C.

Inventors

  • SCHILLING, ROBERT
  • SANDEN, FRANZ JOSEF
  • PATZ, Jacob
  • SCHROEDER, ALEXANDER
  • KOSOLAPOV, Denis

Assignees

  • BASF SE

Dates

Publication Date
20260507
Application Date
20251029
Priority Date
20241030

Claims (15)

  1. 1. Method for utilizing heat from a secondary circuit (15) of a geothermal plant (1 ), comprising: (a) Heating a heat transfer fluid flowing through the secondary circuit (15) to a temperature in the range of 120 to 300 °C by transferring heat from hot brine (3) from a geothermal source; (b) Evaporating water (35) in a first evaporator (33) by transferring heat from at least a part of the heated heat transfer medium (31), wherein the at least a part of the heat transfer medium is cooled to a temperature in a range of 80 to 140 °C; (c) Generating steam by utilizing heat from the heat transfer medium cooled to a temperature in the range of 80 to 140 °C (37).
  2. 2. Method according to claim 1, characterized in that the heat transfer medium is cooled to a temperature in the range of 60 to 100 °C by utilizing the heat in step (c).
  3. 3. Method according to claim 1 or 2, characterized in that in step (c) water (41) is evaporated at a pressure in the range of 100 to 1000 mbar(abs) by heat transfer from the heat transfer medium cooled to a temperature in the range of 80 to 140 °C in a second evaporator (39).
  4. 4. Method according to claim 3, characterized in that the vapor generated in the second evaporator is compressed in at least one compressor with at least one compression stage (43.1 , 43.2) and subsequently mixed with the vapor generated in step (b).
  5. 5. Method according to claim 4, characterized in that the steam is compressed to process steam after mixing in at least one compressor (45) with at least one compression stage (45.1 , 45.2).
  6. 6. Method according to claim 4 or 5, characterized in that water is injected into the steam downstream of at least one compression stage (43.1 , 43.2; 45.1 , 45.2).
  7. 7. Method according to claim 1 or 2, characterized in that the steam in step (c) is generated by using the heat of the heat transfer medium cooled to a temperature in the range of 80 to 140 °C in an absorption heat pump (49). 240595W001 14
  8. 8. Method according to claim 7, characterized in that the absorption heat pump (49) is a multi-stage absorption heat pump and the steam generated in step (b) is compressed in at least one compressor (45) with at least one compression stage (45.1 , 45.2) and is mixed with the steam generated in the absorption heat pump (49) after compression.
  9. 9. Method according to claim 8, characterized in that water is injected into the steam downstream of at least one compression stage.
  10. 10. Method according to claim 7, characterized in that the steam generated in the absorption heat pump (49) is mixed with the steam generated in step (b) to form a total steam flow (57) and the total steam flow (57) is then compressed in at least one compressor (45) with at least one compression stage (45.1 , 45.2).
  11. 11. Method according to claim 10, characterized in that water is injected into the steam downstream of at least one compression stage (45.1 , 45.2).
  12. 12. Method according to claim 10 or 11, characterized in that the heat transfer medium is divided into a first partial flow (61) and a second partial flow (63), wherein the first partial flow (61) flows through the first evaporator (33) and the second partial flow (63) flows through a heat exchanger (59) in which the total steam flow (57) is superheated by heat transfer from the second partial flow (63) before compression.
  13. 13. Method according to claim 12, characterized in that the first partial flow (61 ) after passing through the first evaporator (33) and the second partial flow (63) after passing through the heat exchanger (59) are mixed to form a total flow and the total flow is then supplied to the absorption heat pump (49).
  14. 14. Method according to claim 12 or 13, characterized in that the steam superheated in the heat exchanger (59) is compressed in at least one compressor (45) with at least one compression stage (45.1 , 45.2).
  15. 15. The method according to claim 14, characterized in that water is injected into the steam downstream of at least one compression stage (45.1, 45.2). ```

Description

240595W001 Method for utilizing heat from a secondary circuit of a geothermal plant Description The invention relates to a method for utilizing heat from a secondary circuit of a geothermal plant. Geothermal plants are typically used to generate electricity and provide usable heat for specific applications, such as building heating. For electricity generation, hydrothermal springs are used, from which hot brine is extracted and fed into an ORC (Organic Rankine Cycle) process. Alternatively, the hot brine can be used to generate steam or hot water in a secondary circuit and then fed into a steam network or, for example, a district heating network. A geothermal plant utilizing brine from a geothermal source to provide energy for electricity generation or building heating is described, for example, in I. Stober, K. Bucher, "Geothermie" (Geothermal Energy), 3rd edition, Springer-Verlag, 2020. This description illustrates the cascaded utilization of the brine's heat at different temperature levels. The heat at the highest temperature level is used to generate electricity in a power plant. Due to the heat extracted for electricity production, the brine is cooled to a lower temperature level, and some of this heat is used for food processing or refrigeration. This heat utilization leads to a further cooling of the brine to a third temperature level, at which point the heat can be used to heat buildings or greenhouses. Due to the heat extraction, the brine is then at the lowest temperature level still usable for the system, at which the heat of the brine can then be used, for example, for fish farming, before the brine is pumped back to the geothermal source. Particularly in the chemical industry, steam is used as a key energy source alongside electricity. Currently, steam is primarily produced using fossil fuels. Therefore, to reduce carbon dioxide emissions, alternative methods for electricity generation and, in particular, steam production are being sought. CN-A 114321858 discloses the use of geothermal energy to generate steam. For this purpose, water from a geothermal source is used to heat desalinated water in a first heat exchanger. The cooled water from the geothermal source is then used as the heat transfer fluid in a heat pump before being returned to the geothermal source. The water heated in the first heat exchanger is fed into a flash evaporator, where it is vaporized. The water that remains unvaporized is fed into a second flash evaporator, where more water is vaporized. 240595W001 2 The device described in CN-A 114321858 is suitable for steam generation; however, it is not possible to utilize the heat from the geothermal source for other applications. Furthermore, the direct use of water from the geothermal source can lead to mineral precipitation, and the resulting deposits can cause problems in system components. Therefore, the task arose to provide a method for utilizing heat from a geothermal plant that, in addition to steam generation, can also enable further use of the heat. This problem is solved by a method for utilizing heat from a secondary circuit of a geothermal plant, comprising: (a) Heating a heat transfer fluid flowing through the secondary circuit to a temperature in the range of 120 to 300 °C by transferring heat from hot brine from a geothermal source; (b) Evaporation of water in a first evaporator by transferring heat from at least a part of the heated heat transfer medium, wherein the at least a part of the heat transfer medium is cooled to a temperature in the range of 80 to 140 °C; (c) Generating steam by utilizing heat from the heat transfer medium cooled to a temperature in the range of 100 to 140 °C. The use of heat from a secondary circuit of the geothermal plant allows the heat of the hot brine to be used not only to heat the heat transfer medium of the secondary circuit, but also for other tasks, for example for electricity generation or, after heat transfer to the heat transfer medium of the secondary circuit, for cooling systems or heating buildings. Furthermore, it is also possible to use the heat of the heat transfer medium in the secondary circuit not only for steam generation, but also for other purposes, for example for the direct heating of plant components. Another advantage of the method according to the invention is that the heat of the secondary circuit can be used optimally, since the residual heat after use for steam generation in step (b) can also be used for steam generation and thus the amount of steam generated with the heat of the secondary circuit can be greatly increased. In a geothermal plant, hot brine is extracted from a geothermal source. The temperature of the brine depends on the depth from which it is extracted. For deep geothermal energy use, the brine is typically extracted from a depth of 3000 to 240595W001 3 4000 m and has a temperature in the range of 120 to 300 °C, more preferably in the range of 120 to 200 °C and particularly in the ran