US3611718A - Waste heat steam generating cycle - Google Patents

Waste heat steam generating cycle Download PDF

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Publication number
US3611718A
US3611718A US34718A US3611718DA US3611718A US 3611718 A US3611718 A US 3611718A US 34718 A US34718 A US 34718A US 3611718D A US3611718D A US 3611718DA US 3611718 A US3611718 A US 3611718A
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steam
water
pressure
turbine
flash
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US34718A
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English (en)
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William H Nebgen
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Treadwell Corp
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Treadwell Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
    • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
    • F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle

Definitions

  • WASTE HEAT STEAM GENERATING CYCLE Filed may 5, 1.970
  • the recovery cycle is particularly illustrated as applied to the waste heat contained in the exhaust gases of a Brayton cycle combustion gas turbine.
  • the exhause gases available usually at about 850 F., heat 1500 p.s.i.a. pressurized water to about 596 F.
  • the hot pressurized water is then introduced into one of a plurality of water receivers in which it is permitted to flash at gradually decreasing pressures.
  • the resulting flash steam is superheated to about 800 F. by the 850 F. exhaust gases, and introduced into the steam chest of a multiple nozzle steam turbine.
  • the number of nozzles passing steam is gradually increased as the steam pressure drops so as to keep power production substantially constant.
  • the unflashed water is transferred to another receiver and is permitted to flash down to a lower pressure.
  • This flash steam is similarly superheated and is introduced into the steam chest of a similar multiple nozzle intermediate pressure turbine.
  • the water is finally introduced into a low pressure water receiver where it is flashed to about condensing pressure, the flash steam is again superheated, and expanded through a multiple nozzle low pressure turbine to the condenser.
  • the residual water and condensate are then joined, and pumped at high pressure to be heated again by the exhaust gases as described above.
  • the pressures of the receivers in the first line drop to the preselected lower pressures, a fresh line of receivers at the higher pressures is cut in, thus providing continuous operation.
  • waste heat boilers In the past, in an attempt to improve overall efficiency, waste heat boilers have frequently been employed, and recently two waste heat boilers in series, producing steam at successively lower pressures have been used.
  • a thermal efficiency of. 35 .1 is theoretically attainable by a cycle operating with a waste heat source whose initial 850 F. temperature declines to 100 F. This efliciency could be reached by using a very large number of boilers in series, operating at progressively lower pressures, but in practice the cost of the equipment and parasitic losses such as pressure and temperature drop limit the number to two or at most three boilers in series.
  • the present invention consists of a waste heat boiler system in which the sensible heat, particularly sensible heat from a Brayton cycle gas turbine, is used first to 3,011,718 Patented Oct. 12, I971 superheat the vapor of a working fluid, as will be described below, and is then used to heat the working fluid in the liquid form at a pressure sufliciently high substantially to prevent vaporization.
  • the present invention is not concerned in its broadest aspect with the exact working fluid concerned. Water is by far the cheapest and in many cases the preferred working fluid.
  • other known working fluids such as suitable fluoro carbons, for example the one referred to by the trade designation Freon R11, ammonia and the like.
  • water at a pressure of. 1500 p.s.i.a. can be heated without vaporization to a temperature of 596 'F.
  • This hot, high pressure water is introduced into the high pressure receiver of one line of a plurality of lines of receivers, for example, two or three, each line consisting of a high, an intermediate, and a low pressure receiver.
  • the water in the high pressure receiver is permitted to gradually flash down to an intermediate pressure, and the steam evolved is superheated by the exhaust gases, as has been referred to above, and then expanded in a high pressure steam turbine with multiple nozzles.
  • the rate of flashing is controlled by the number of turbine nozzles in use; at the highest pressure a single nozzle may be used, while as the pressure drops and the weight of steam passed by an individual nozzle also drops, more nozzles are successively cut in to keep the power output reasonably constant.
  • the water in the high pressure receiver When the water in the high pressure receiver has flashed down to a preselected lower pressure, it is transferred to an intermediate pressure receiver and the empty high pressure receiver is recharged with hot water.
  • the water in the intermediate pressure receiver is permitted to flash as before to a lower pressure.
  • the evolved steam joins the high pressure turbine exhaust steam, and after being superheated the combined steam is introduced into a multiple nozzle intermediate pressure turbine.
  • the intermediate pressure receiver When the water in the intermediate pressure receiver has flashed down to a preselected lower pressure, it is transferred to a low pressure receiver.
  • the empty intermediate pressure receiver is then recharged with the water which had previously flashed in the high pressure receiver.
  • the water in the lower pressure receiver is permitted to flash as before to condensing pressure.
  • the evolved steam joins the intermediate pressure turbine exhaust steam and after being superheated, the combined stream is introduced into a multiple nozzle low pressure turbine, through which it expands to the condenser.
  • the receiver When the water in the low pressure receiver has flashed down to a preselected pressure, the receiver is emptied and then recharged with the water which had previously flashed in the intermediate pressure receiver.
  • the flashed water from the low pressure receiver and the condensate are joined and pumped back for reheating by the exhaust gases.
  • each batch of hot water provides as it vaporizes the equivalent of an infinite number of boilers operating at successively lower pressures.
  • the cycle efficiency can, therefore, closely approach the previously mentioned maximum theoretical efficiency of 35.1%.
  • the present invention will produce from a given quantity of 850 F. exhaust gases, 54% more work than a single waste heat boiler, more work than two waste heat boilers in series, and 23% more work than three boilers in series.
  • the dead spot in power production which could occur While the batches are being transferred from receiver to receiver can be eliminated by employing an alternately operating line of three receivers feeding the same three turbines.
  • the smoothness of the flow of power from the waste heat boilers can be assured by using a hot water surge tank to which the pressurized hot water flows before entering the high pressure water receiver, and a cold water surge tank to which the cooled, flashed water is pumped from the low pressure water receiver and from the condenser.
  • the holding capacities of the surge tanks must be sufficient to balance the cyclic water requirements of the receiver lines with the uniform water flow rate of the waste heat recovery system.
  • any vapor space remaining in the receivers when the water is transferred will cause a loss of efficiency because of the irreversible nature of the isenthalpic flash of the hotter liquid into the momentarily lower pressure space of the receiver into which it is being transferred.
  • a small vapor space is necessary for mechanical reasons, however, to insure that no liquid water is introduced into the steam turbines, and the resultant small loss in efficiency must be tolerated as a safety factor. It should, however, be kept as small as practicable.
  • the interfacial contact areas of the receivers must be kept as small as possible.
  • One practical design is a top and bottom header connected by relatively long tubes or small diameter pipes.
  • thermal efiiciency of the waste heat boilers of the present invention is so great that often the best overall efliciency when used with a Brayton cycle gas turbine is maximized with a much smaller number of turbine stages than is normally desirable where there is not available such a highly efiicient waste heat system.
  • a single stage gas turbine may be used, which of course saves on equipment which would otherwise be necessary for maximum turbine efficiency with multiple stages, reheats, and the like. This possibility of saving in the preferred modification of the present invention is of real practical importance.
  • atmospheric air 1 enters compressor 2 of a Brayton cycle turbine, is compressed therein and directed to com'bustor 64, which is supplied with suitable fuel 65.
  • the hot high pressure air after being expanded and partially cooled in expander 63 of the Brayton cycle gas turbine, goes to heat recovery section 3 in which it gives up heat to superheaters 4, 5, and 6, and water heater 7, and is finally discharged cooled to atmosphere at 66-.
  • Cold, low pressure water is pressurized by pump 13 to about 1500 p.s.i.a., heated in water heater 7 to about 596 F., and directed through surge tank 15 and valve 16 to high pressure receiver 17 of line A.
  • water receivers 24 and 31 and condenser 11 operate at successively lower absolute pressures, which ideally at the start of the cycle should be such that Pump 18 circulates the water from receiver 17 through valve 19 to steam separator 20, in which the water flashes at progressively decreasing temperature and pressure as the flash vapor is removed.
  • the flash vapor produced is directed via valve 21 through superheater 4 to the multiple nozzles of turbine 8, through which it expands to line 60, where it is joined by flash vapor similarly produced in steam separator 27
  • the combined vapor stream is heated in superheater 5 and flows to the multiple nozzles of turbine 9, through which it expands to line 61, where it is joined by flash vapor similarly produced in steam separator 34.
  • the combined vapor stream is again heated in superheater 6 and flows to the multiple nozzles of turbine 10, through which it expands to condenser 11.
  • the shafts of turbines 8, '9 and 10 produce power, which is shown diagrammatically at 62. It can be any power absorbing element, such as a generator.
  • the power output of the turbine 63 of the Brayton cycle is shown connected to a power utilizing element 68. In the latter case, of course, the output power is the difference between the power produced and that absorbed by the compressor 2 which is driven by the turbine 63.
  • a second line of receivers and flash tanks, labeled B, is provided, with receivers 39, 46 and 53 corresponding to 17, 24 and 31 of line A; flash tanks 42, 49 and 56 corresponding to 20, 27 and 34, and pumps 40, 47 and 54 correpsonding to 18, 25 and 32.
  • Valve connections in line B are 38, 43, 45, 50, 52, '57 and 55 and 59 respectively.
  • the check valves 44, 45 and 58 are provided.
  • Water admission valves 16, 23 and 30 are then opened, pressurizing line A, and causing check valves 22, 29 and 36 to close, thus trapping the liquid and vapor contents of steam separators 20, 27 and 34 at the respective pres sures prevailing at the end of the cycle. It is necessary to have some residual vapor space in the separators in order to prevent liquid from entering the turbines when operations resume. However, the volumes of these spaces should be kept as small as possible, since they cause a loss in cycle efliciency, as will be explained later.
  • Water outlet valve 37 is then opened, permitting hot high pressure water to displace the lower temperature water contained in water receiver 17, which in turn displaces the water contained in water receiver 24, which displaces the water contained in water receiver 31.
  • the flow rate of water to surge drum is controlled by valve 67, which by regulating flow keeps the temperature of the water leaving heater 7 constant.
  • the holding capacity of drum 15 must be suflicient to permit balancing the cyclic water requirements of vapor generating lines A and B with the substantially uniform flow rate to drum 15.
  • Valves 37, 30, 23 and 16 close when the liquid level of drum 15 falls a predetermined amount, corresponding to the cycle displacement volume. Pump valves 19, 26, and 33 are then reopened and line A is again ready to go on stream.
  • Line B operates in the same manner as has been described for line A, its corresponding pumps, valves, flash tanks and the like operating in the same manner, including the operation of check valves 44, 51 and 58 when the B line has contributed its power and is repressurized.
  • the interfacial contact areas of the receivers must be kept as small as practicable. This is readily achieved by constructing the receivers 17, 24 and 31 of line A and 39, 46 and 53 of line B of top and bottom headers, connected by relatively long tubes or small diameter pipes, as shown schematically in the drawing.
  • the cycle timing is automatically set to keep the peak liquid level of drum 15 constant, thus equalizing in-flow and out-flow.
  • multiple nozzles of turbine 8 are automatically operated to adjust the pressure decay rate of steam separator so as to conform both to this cycle timing and to the requirement for a substantially constant power production rate.
  • the absolute pressure of steam separator 27 is automatically controlled at a desired percentage of the absolute pressure of separator 20 by the operation of the multiple nozzles of turbine 9, and in the same Way the desired absolute pressure relationship between separators 34 and 27 is automatically controlled by the operation of the nozzles of turbine 10.
  • the pressure of the steam produced in the steam separators decays from a high value at the start of a cycle to a low value at the end of a cycle, with a comparable reduction in weight flow through a given turbine nozzle passing steam at a given temperature through a given expansion ratio.
  • steam is admitted to a progressively larger number of nozzles as the steam pressure decreases.
  • the exhaust steam from turbine 8 cooled as a result of its expansion, joins the steam generated in separator 27 and is reheated in superheater 5. The same process occurs with the exhaust from turbine 9.
  • the reheats improve the efliciency of the cycle.
  • a waste heat working fluid vapor generating system comprising,
  • thermoelectric heat exchangers and a means to supply waste heat gases thereto, the heat exchangers including fluid heating elements and vapor superheating elements;
  • each turbine stage having a plurality of steam introducing nozzles
  • control means for introducing hot pressurized liquid from the heat exchanger in the waste heat section to the highest pressure liquid receiver in each series;
  • (j) means for sequentially and cumulatively opening the sets of nozzles as the vapor temperature and pressure in the flash chamber is reduced to maintain substantially uniform power production in the turbine stage;
  • valved means connecting said flash chamber to a second superheater exchanger in the waste heat section and thence to a set of sequenced nozzle sets in the next section of the vapor turbine and means for opening them sequentially and cumulatively as the vapor temperature and pressure decreases in the same manwhen the second series has flashed liquid down to ner as the nozzles in the high temperature section the predetermined temperature.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)
US34718A 1970-05-05 1970-05-05 Waste heat steam generating cycle Expired - Lifetime US3611718A (en)

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US3471870A 1970-05-05 1970-05-05

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US (1) US3611718A (es)
AT (1) AT316935B (es)
BE (1) BE766744A (es)
CA (1) CA933370A (es)
DE (1) DE2122063A1 (es)
ES (1) ES390878A1 (es)
FR (1) FR2091250A5 (es)
GB (1) GB1342777A (es)
NL (1) NL7105620A (es)
SE (1) SE364558B (es)
ZA (1) ZA712245B (es)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4178754A (en) * 1976-07-19 1979-12-18 The Hydragon Corporation Throttleable turbine engine
US4204401A (en) * 1976-07-19 1980-05-27 The Hydragon Corporation Turbine engine with exhaust gas recirculation
US4276747A (en) * 1978-11-30 1981-07-07 Fiat Societa Per Azioni Heat recovery system
US20070251256A1 (en) * 2006-03-20 2007-11-01 Pham Hung M Flash tank design and control for heat pumps
US20150330258A1 (en) * 2013-01-28 2015-11-19 Eaton Corporation Volumetric energy recovery system with three stage expansion
US20170058707A1 (en) * 2014-03-05 2017-03-02 Siemens Aktiengesellschaft Flash tank design
CN107191232A (zh) * 2017-06-06 2017-09-22 大唐东北电力试验研究所有限公司 电热机组供热系统
EP3486440A1 (en) * 2017-11-21 2019-05-22 Siemens Aktiengesellschaft Heat recovery steam generator, method for generating steam for a steam turbine and system comprising a steam turbine and a heat recovery steam generator
CN116968241A (zh) * 2023-07-31 2023-10-31 青岛冠铭包装制品有限公司 一种泡沫塑料成型机的余热回收设备

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2116139B1 (es) * 1993-05-14 1999-04-16 Rosado Serafin Mendoza Perfeccionamientos introducidos en la patente de invencion n- 9301044 titulada un procedimiento de mejora para centrales electricas de ciclo combinado con aporte paralelo de energia al ciclo de vapor en una caldera de combustible fosil.
ES2116137B1 (es) * 1993-05-14 1999-04-16 Rosado Serafin Mendoza Un procedimiento de mejora para centrales electricas de ciclo combinado con aporte de energia al ciclo de vapor en una caldera de combustible fosil.
DE19720881A1 (de) 1997-05-17 1998-11-19 Asea Brown Boveri Kombikraftwerk mit Kraftwärmekopplung

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4178754A (en) * 1976-07-19 1979-12-18 The Hydragon Corporation Throttleable turbine engine
US4204401A (en) * 1976-07-19 1980-05-27 The Hydragon Corporation Turbine engine with exhaust gas recirculation
US4276747A (en) * 1978-11-30 1981-07-07 Fiat Societa Per Azioni Heat recovery system
US8020402B2 (en) 2006-03-20 2011-09-20 Emerson Climate Technologies, Inc. Flash tank design and control for heat pumps
US20080047284A1 (en) * 2006-03-20 2008-02-28 Emerson Climate Technologies, Inc. Flash tank design and control for heat pumps
US20110139794A1 (en) * 2006-03-20 2011-06-16 Emerson Climate Technologies, Inc. Flash tank design and control for heat pumps
US20070251256A1 (en) * 2006-03-20 2007-11-01 Pham Hung M Flash tank design and control for heat pumps
US8505331B2 (en) 2006-03-20 2013-08-13 Emerson Climate Technologies, Inc. Flash tank design and control for heat pumps
US20150330258A1 (en) * 2013-01-28 2015-11-19 Eaton Corporation Volumetric energy recovery system with three stage expansion
US20170058707A1 (en) * 2014-03-05 2017-03-02 Siemens Aktiengesellschaft Flash tank design
US10054012B2 (en) * 2014-03-05 2018-08-21 Siemens Aktiengesellschaft Flash tank design
CN107191232A (zh) * 2017-06-06 2017-09-22 大唐东北电力试验研究所有限公司 电热机组供热系统
EP3486440A1 (en) * 2017-11-21 2019-05-22 Siemens Aktiengesellschaft Heat recovery steam generator, method for generating steam for a steam turbine and system comprising a steam turbine and a heat recovery steam generator
CN116968241A (zh) * 2023-07-31 2023-10-31 青岛冠铭包装制品有限公司 一种泡沫塑料成型机的余热回收设备
CN116968241B (zh) * 2023-07-31 2024-06-07 青岛冠铭包装制品有限公司 一种泡沫塑料成型机的余热回收设备

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Publication number Publication date
DE2122063A1 (de) 1971-11-18
BE766744A (fr) 1971-11-05
FR2091250A5 (es) 1972-01-14
NL7105620A (es) 1971-11-09
ZA712245B (en) 1972-11-29
CA933370A (en) 1973-09-11
GB1342777A (en) 1974-01-03
ES390878A1 (es) 1973-07-01
SE364558B (es) 1974-02-25
AT316935B (de) 1974-08-12

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