WO2010133726A1 - Rankine cycle with absorption step using hygroscopic compounds - Google Patents
Rankine cycle with absorption step using hygroscopic compounds Download PDFInfo
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- WO2010133726A1 WO2010133726A1 PCT/ES2010/000208 ES2010000208W WO2010133726A1 WO 2010133726 A1 WO2010133726 A1 WO 2010133726A1 ES 2010000208 W ES2010000208 W ES 2010000208W WO 2010133726 A1 WO2010133726 A1 WO 2010133726A1
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- Prior art keywords
- steam
- turbine
- cycle
- absorber
- hygroscopic
- Prior art date
Links
- 150000001875 compounds Chemical class 0.000 title claims abstract description 34
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 24
- 239000006096 absorbing agent Substances 0.000 claims abstract description 29
- 238000001816 cooling Methods 0.000 claims abstract description 25
- 238000009833 condensation Methods 0.000 claims abstract description 11
- 230000005494 condensation Effects 0.000 claims abstract description 11
- 238000004090 dissolution Methods 0.000 claims abstract description 9
- 239000000126 substance Substances 0.000 claims abstract description 9
- 238000001179 sorption measurement Methods 0.000 claims abstract description 8
- 238000011084 recovery Methods 0.000 claims abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 22
- 230000003247 decreasing effect Effects 0.000 claims description 6
- 238000001471 micro-filtration Methods 0.000 claims description 5
- 238000001728 nano-filtration Methods 0.000 claims description 5
- 238000001223 reverse osmosis Methods 0.000 claims description 5
- 230000002441 reversible effect Effects 0.000 claims description 5
- 238000000108 ultra-filtration Methods 0.000 claims description 5
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical group [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 4
- 238000013021 overheating Methods 0.000 claims description 4
- 239000011734 sodium Substances 0.000 claims description 4
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 4
- 235000011152 sodium sulphate Nutrition 0.000 claims description 4
- 239000002028 Biomass Substances 0.000 claims description 3
- 230000008901 benefit Effects 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 230000014759 maintenance of location Effects 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 230000008929 regeneration Effects 0.000 claims description 3
- 238000011069 regeneration method Methods 0.000 claims description 3
- 238000007865 diluting Methods 0.000 claims description 2
- 239000012528 membrane Substances 0.000 claims description 2
- 238000009434 installation Methods 0.000 claims 4
- 238000010348 incorporation Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 20
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 8
- 239000012530 fluid Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- 239000002250 absorbent Substances 0.000 description 6
- 230000002745 absorbent Effects 0.000 description 6
- 235000002639 sodium chloride Nutrition 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- AMXOYNBUYSYVKV-UHFFFAOYSA-M lithium bromide Chemical compound [Li+].[Br-] AMXOYNBUYSYVKV-UHFFFAOYSA-M 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- -1 lithium bromide Chemical class 0.000 description 2
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Inorganic materials [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- FFBHFFJDDLITSX-UHFFFAOYSA-N benzyl N-[2-hydroxy-4-(3-oxomorpholin-4-yl)phenyl]carbamate Chemical compound OC1=C(NC(=O)OCC2=CC=CC=C2)C=CC(=C1)N1CCOCC1=O FFBHFFJDDLITSX-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000740 bleeding effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003034 coal gas Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 239000012809 cooling fluid Substances 0.000 description 1
- 229910000365 copper sulfate Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- YWEUIGNSBFLMFL-UHFFFAOYSA-N diphosphonate Chemical compound O=P(=O)OP(=O)=O YWEUIGNSBFLMFL-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000010442 halite Substances 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000006193 liquid solution Substances 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000006199 nebulizer Substances 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003204 osmotic effect Effects 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- DLYUQMMRRRQYAE-UHFFFAOYSA-N phosphorus pentoxide Inorganic materials O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000011555 saturated liquid Substances 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 239000011592 zinc chloride Substances 0.000 description 1
- 235000005074 zinc chloride Nutrition 0.000 description 1
Classifications
-
- 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
- F01K3/00—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein
- F01K3/18—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein having heaters
- F01K3/20—Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein having heaters with heating by combustion gases of main boiler
-
- 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
- F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
- F01K25/06—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids
- F01K25/065—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids with an absorption fluid remaining at least partly in the liquid state, e.g. water for ammonia
Definitions
- the Rankine cycle is a power cycle that operates with steam. It is currently used in the generation of electricity in thermoelectric or thermal steam plants. Water is used as a working fluid through different equipment and producing mechanical work thanks to its expansion (steam state) inside a steam turbine; A generator connected to the turbine outlet delivers the electrical power produced.
- the performance of the Rankine cycle is determined as the ratio between the subtraction of the work0 produced by the turbine and the one consumed by the pump, split from the heat transferred to the steam from the steam generator (boiler plus superheater).
- the decrease in the expansion term pressure is limited by the temperature of the cooling agent (mainly water or air) in the condenser. 5
- the hygroscopic compounds are all those substances that attract water in the form of steam or liquid from their environment, hence its main application as desiccants. Many of them react chemically with water such as hydrides or alkali metals. Others catch it as hydration water in its crystalline structure as is the case with sodium sulfate. Water It can also be physically adsorbed. In these last two cases, the retention is reversible and the water can be desorbed. In the first case, having reacted, it cannot be recovered simply.
- Deliquescent materials are substances (mostly salts) that have a strong chemical affinity for moisture and absorb relatively high amounts of water if they are exposed to the atmosphere, forming a liquid solution.
- deliquescent substances are: calcium chloride, ferric chloride, magnesium chloride, zinc chloride, potassium carbonate, potassium hydroxide and sodium hydroxide.
- the presence of these compounds in dilution with water modifies their properties in relation to their pure state. These modifications are known as properties of a solution, classified as constitutive (viscosity, density, electrical conductivity, etc.) and colligative or collective (decrease in solvent vapor pressure, increase in boiling point, decrease in freezing point and pressure osmotic) of special interest in this patent.
- hygroscopic compounds One of the main applications of hygroscopic compounds is the absorption cycles used for refrigeration. These machines began to be marketed at the beginning of the 50s.
- the absorption cycles are physically based on the ability of some substances, such as water and some salts such as lithium bromide, to absorb, in liquid phase, other vapors substances such as ammonia and water, respectively. By similarity, in this cycle the water would be the cooling fluid and the hygroscopic compound the absorbent.
- the hygroscopic cycle is a power plant cycle that works with water and with this type of compounds or materials, which must have the following characteristics:
- the vapor pressure of the absorbent / water solution depends on the nature of the absorbent, its temperature and its concentration. At a lower temperature of the absorbent and at a higher concentration, the lowest vapor pressure will be in the solution.
- hygroscopic compounds are: - Sodium Chloride (Halite) (ClNa) Calcium Chloride (CaCl 2 )
- the hygroscopic cycle incorporates the physical and chemical principles of absorption machines to provide the Rankine cycle with better performance and better cooling conditions. It comprises the following main equipment: a) Steam turbine. b) Absorber. It can be a venturi, jet type, scrubber, spray tower gas scrubber. c) Condensate pump. d) Dissolution pump. e) Heat recovery. It can be a shell and tube or plate type heat exchanger. f) Thermal degasser. g) Steam generator. It can be evaporator, boiler or shell and tube exchanger. h) Steam separator. Deposit with "demister" (nebulizer) or rectification column. i) Superheater. j) Expansion valve. k) Air cooler, cooling tower or heat exchanger.
- This cycle may include many of the improvements made to the Rankine cycle (pressure increase start of expansion, decreasing the pressure term expansion, vapor superheat, reheat, regeneration, superc ⁇ conditions' tics) described above and incorporating any equipment that allows the steam to be in contact with the chosen hygroscopic compound (both absorption and adsorption).
- pressure increase start of expansion decreasing the pressure term expansion, vapor superheat, reheat, regeneration, superc ⁇ conditions' tics
- any equipment that allows the steam to be in contact with the chosen hygroscopic compound both absorption and adsorption.
- This vapor is directed to the absorber where it is absorbed and diluted in contact with the selected hygroscopic compounds (mainly salts), for example lithium bromide (LiBr), lithium chloride (LiCl), sodium sulfate (Na 2 SO 4 ), etc.
- the solution contained in the absorber is usually at a higher temperature than that of the feed water vapor. This temperature difference depends on the hygroscopic compound or mixture chosen and its concentration. To reduce the corrosion produced by the dissolution of the hygroscopic compounds it is recommended to use inhibitors.
- This diluted solution from the absorber is aspirated by the condensate pump and one part is driven, after passing through the enthalpy recuperator, to the thermal degasser or deaerator tank of the steam generator and the other part acts as a reflux of the absorber.
- the thermal degasifier is a tank used to extract oxygen and other dissolved gases from the solution and heat and store the feed water to the steam generator. This equipment can be connected to a low pressure steam line from a bleeding of the steam turbine in order to remove the oxygen and dissolved gases and favor its elimination.
- the heat recuperator is an exchanger that preheats the diluted solution from the absorber, with the hot solution returning from the steam separator. Its objective is to increase the temperature of the solution that feeds the degasser and cool the concentrated solution that returns to the absorber.
- the diluted solution from the degasser is driven at high pressure to the steam generator by means of the dissolution pump.
- the necessary energy to boil at high pressure and temperature is supplied in order to concentrate the absorbent solution and obtain a clean water vapor that will be fed to the steam turbine, previously passing through the superheater, from which a Superheated steam needed to increase the process performance and achieve a drier steam at the turbine outlet.
- Steam purity is achieved thanks to the steam separator with built-in "demister” (de-fogger) or a rectification tower.
- the energy provided to the steam generator and superheater can come from a thermal fluid, nuclear energy, solar energy, a combustion process, whose energy sources can be the heat of the exhaust gases of an internal combustion engine, heat of the exhaust gases of a gas turbine, heat obtained from the burning of a fuel or biomass, waste heat from industrial processes ...
- the concentrated solution that leaves the heat recuperator is directed to the air cooler, heat exchanger or cooling tower in order to dissipate the absorption heat (condensation heat plus dissolution heat) to prevent the temperature from rising and thus be absorbed a maximum amount of water vapor. After cooling, it enters the absorber at low pressure after passing through the expansion valve where it loses almost all the pressure that the fluid has.
- the outlet steam of the superheater (live steam) is at the necessary conditions to be expanded in the steam turbine, which is connected to a generator that will produce the electric power thanks to the work produced.
- the steam at low pressure and temperature would return to the cycle described above.
- the cycle performance ( ⁇ ) is determined as the ratio between the subtraction of the work produced by the turbines (steam turbine plus hydraulic turbine (if any), W1 and W4 respectively) and that consumed by the condensate pump (W2), dissolution pump (W3) and reverse osmosis, nanofiltration, ultrafiltration or microfiltration system (W5), if any, split from heat transferred to steam from the steam generator (Q2), superheater (OJ) and absorption machine (Q3) , if the latter exists. It is represented in the following formula: WI + W4- W2 - W3 - W5
- the hygroscopic cycle achieves:
- the necessary refrigeration temperature of the cycle is normally between 1 and 80 ° C above the steam temperature at the turbine outlet, with the possibility of eliminating cooling (endothermic mixing). This effect allows working in more severe vacuum conditions (around 0.01 bar) without having the cooling temperature limited.
- thermoelectric plants oil, coal and natural gas, other fuels
- nuclear nuclear
- biomass nuclear
- Figure 1 represents the process diagram of the hygroscopic cycle including the main equipment as detailed in the description.
- Figure 2 represents the process diagram of the hygroscopic cycle including as optional equipment a hydraulic turbine, a reverse osmosis filtration system, ultrafiltration or microfiltration nanofiltration and an absorption or adsorption machine; equipment explained above.
- Figure 3 represents a typical temperature - entropy diagram of Rankine cycles.
- Process 1 - 2 ' Isoentropic expansion of the working fluid in the turbine from the generator pressure to the absorber pressure.
- Process 2 ' - 3 ' Steam heat transmission with the hygroscopic compound at constant pressure in the absorber to the state of saturated liquid.
- Process 3 ' - 4 ' Isoentropic compression in the pump. It increases the pressure of the fluid through a compressor or pump that is given a certain job.
- Process 4 ' - 1 ' Heat transmission to the working fluid at constant pressure in the generator and superheater. The processes are not internally reversible, there are different irreversibilities and losses.
- Performance 2 whose points are 1 ' , 2 ' , 3 ' and 4 ' is greater than performance 1 of the first case, whose points are 1, 2, 3 and 4.
- This increase in performance can be observed in the scratched area , being typical of hygroscopic cycles versus Rankine or similar cycles, since it is possible to work with higher vacuum conditions (lower temperature) for the same cooling conditions.
- the heat of absorption can be used to produce steam at a temperature higher than that of the steam supplied to the absorber.
- Figure 4 shows the consumption or generation of energy in the form of work or heat of existing equipment, showing at each point of the process a description of each current.
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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)
Abstract
The hygroscopic cycle is a power cycle that operates with steam and hygroscopic compounds. These compounds absorb steam at low pressure and temperature that has been expanded in the turbine and desorbed therefrom in the generator under the required operating conditions. In the absorber, the enthalpy of the steam is utilized and increased in the generator with the provision of heat. The turbine is able to work at high vacuums and cooling temperatures above the exit temperature of the steam in the turbine. The invention comprises the following main items of equipment: absorber, dissolution pump, condensation pump, heat recovery means, thermal degasser, steam generator, steam separator, expansion valve, air cooler or cooling tower, superheater, steam turbine and, optionally, hydraulic turbine, inverse-osmosis system and absorption/adsorption machine. It may include many of the improvements made to the Rankine cycle, being characterized by the incorporation of the physical and chemical principles of absorption machines for achieving better performance from the Rankine cycle and improved cooling conditions.
Description
CICLO DE RANKINE CON ETAPA DE ABSORCIÓN MEDIANTE COMPUESTOS HIGROSCÓPICOS RANKINE CYCLE WITH ABSORPTION STAGE THROUGH HYGROSCOPIC COMPOUNDS
El ciclo de Rankine es un ciclo de potencia que opera con vapor. Se utiliza actualmente en la generación de energía eléctrica en las centrales termoeléctricas o térmicas de vapor. El agua se 5 utiliza como fluido de trabajo pasando por diferentes equipos y produciendo un trabajo mecánico gracias a su expansión (estado vapor) en el interior de una turbina de vapor; un generador conectado a la salida de la turbina entrega la potencia eléctrica producida.The Rankine cycle is a power cycle that operates with steam. It is currently used in the generation of electricity in thermoelectric or thermal steam plants. Water is used as a working fluid through different equipment and producing mechanical work thanks to its expansion (steam state) inside a steam turbine; A generator connected to the turbine outlet delivers the electrical power produced.
El rendimiento del ciclo Rankine se determina como el cociente entre la resta del trabajo0 producido por la turbina y el consumido por la bomba, partido del calor cedido al vapor desde el generador de vapor (caldera más sobrecalentador).The performance of the Rankine cycle is determined as the ratio between the subtraction of the work0 produced by the turbine and the one consumed by the pump, split from the heat transferred to the steam from the steam generator (boiler plus superheater).
Son numerosas las mejoras que se han ido introduciendo al ciclo de Rankine con el objetivo de aumentar el rendimiento del ciclo, y con ello mejorar la eficiencia de la central eléctrica5 tratada. Además de incrementar el rendimiento de los propios equipos participantes en el ciclo (bomba, turbina, caldera...), se ha hecho necesario introducir modificaciones a la disposición de la planta. Entre las principales mejoras realizadas para incrementar el rendimiento del ciclo de Rankine se encuentran las siguientes: 0 • Sobrecalentamiento del vapor al inicio de expansión (ciclo de Hirn).There are numerous improvements that have been introduced to the Rankine cycle in order to increase the cycle performance, and thereby improve the efficiency of the power plant5 treated. In addition to increasing the performance of the teams participating in the cycle (pump, turbine, boiler ...), it has become necessary to make changes to the layout of the plant. Among the main improvements made to increase the performance of the Rankine cycle are the following: 0 • Steam overheating at the beginning of expansion (Hirn cycle).
• Modificaciones de las condiciones de operación al inicio y término de expansión (aumento de la presión de inicio de expansión, la disminución de la presión de término de expansión, condiciones supercríticas).• Modifications of the operating conditions at the beginning and end of expansion (increase in the pressure of expansion start, decrease in pressure of expansion term, supercritical conditions).
• Recalentamiento (se trabaja con presiones mayores evitando la formación de humedad al5 final de la expansión, para ello se extrae el vapor en su totalidad en una etapa de presión intermedia y se recalienta en la caldera hasta una temperatura media llevándolo posteriormente a una nueva expansión).• Reheating (working with higher pressures avoiding the formation of moisture at the end of the expansion, for this purpose the steam is completely extracted in an intermediate pressure stage and reheated in the boiler to an average temperature subsequently taking it to a new expansion ).
• Regeneración (se precalienta el agua de alimentación antes de que llegue a la caldera utilizando calentadores abiertos o cerrados). 0 • Ciclo Binario (dos circuitos en paralelo: uno trabajando a alta temperatura y otro a baja temperatura).• Regeneration (feed water is preheated before it reaches the boiler using open or closed heaters). 0 • Binary Cycle (two circuits in parallel: one working at high temperature and one at low temperature).
La disminución de la presión de término de expansión se encuentra limitada por la temperatura del agente refrigerante (agua o aire principalmente) en el condensador. 5The decrease in the expansion term pressure is limited by the temperature of the cooling agent (mainly water or air) in the condenser. 5
Los compuestos higroscópicos son todas aquellas sustancias que atraen agua en forma de vapor o de líquido de su ambiente, de ello su principal aplicación como desecantes. Muchos de ellos reaccionan químicamente con el agua como los hidruros o los metales alcalinos. Otros lo atrapan como agua de hidratación en su estructura cristalina como es el caso del sulfato sódico. El agua
también puede adsorberse físicamente. En estos dos últimos casos, la retención es reversible y el agua puede ser desorbida. En el primer caso, al haber reaccionado, no se puede recuperar de forma simple.The hygroscopic compounds are all those substances that attract water in the form of steam or liquid from their environment, hence its main application as desiccants. Many of them react chemically with water such as hydrides or alkali metals. Others catch it as hydration water in its crystalline structure as is the case with sodium sulfate. Water It can also be physically adsorbed. In these last two cases, the retention is reversible and the water can be desorbed. In the first case, having reacted, it cannot be recovered simply.
Los materiales delicuescentes son sustancias (en su mayoría sales) que tienen una fuerte afinidad química por la humedad y que absorben cantidades relativamente altas de agua si son expuestos a la atmósfera, formando una solución líquida. Ejemplos de sustancias delicuescentes son: cloruro de calcio, cloruro férrico, cloruro de magnesio, cloruro de zinc, carbonato de potasio, hidróxido de potasio y el hidróxido de sodio. La presencia de estos compuestos en dilución con el agua modifica las propiedades de la misma en relación a su estado puro. Estas modificaciones se conocen como propiedades de una solución, clasificándose en constitutivas (viscosidad, densidad, conductividad eléctrica, etc) y coligativas o colectivas (descenso de la presión de vapor del solvente, aumento del punto de ebullición, disminución del punto de congelación y presión osmótica) de especial interés en esta patente.Deliquescent materials are substances (mostly salts) that have a strong chemical affinity for moisture and absorb relatively high amounts of water if they are exposed to the atmosphere, forming a liquid solution. Examples of deliquescent substances are: calcium chloride, ferric chloride, magnesium chloride, zinc chloride, potassium carbonate, potassium hydroxide and sodium hydroxide. The presence of these compounds in dilution with water modifies their properties in relation to their pure state. These modifications are known as properties of a solution, classified as constitutive (viscosity, density, electrical conductivity, etc.) and colligative or collective (decrease in solvent vapor pressure, increase in boiling point, decrease in freezing point and pressure osmotic) of special interest in this patent.
Una de las principales aplicaciones de los compuestos higroscópicos son los ciclos de absorción utilizados para refrigeración. Estas máquinas empezaron a comercializarse a principio de los años 50. Los ciclos de absorción se basan físicamente en la capacidad que tienen algunas sustancias, tales como el agua y algunas sales como el bromuro de litio, para absorber, en fase líquida, vapores de otras sustancias tales como el amoniaco y el agua, respectivamente. Por similitud, en este ciclo el agua sería el fluido refrigerante y el compuesto higroscópico el absorbente.One of the main applications of hygroscopic compounds is the absorption cycles used for refrigeration. These machines began to be marketed at the beginning of the 50s. The absorption cycles are physically based on the ability of some substances, such as water and some salts such as lithium bromide, to absorb, in liquid phase, other vapors substances such as ammonia and water, respectively. By similarity, in this cycle the water would be the cooling fluid and the hygroscopic compound the absorbent.
El ciclo higroscópico es un ciclo de planta de fuerza que trabaja con agua y con este tipo de compuestos o materiales, los cuales deben tener las siguientes características:The hygroscopic cycle is a power plant cycle that works with water and with this type of compounds or materials, which must have the following characteristics:
• Deben ser compuestos altamente higroscópicos, materiales delicuescentes.• They must be highly hygroscopic compounds, deliquescent materials.
• Deben ser menos volátiles que el agua (presión de vapor menor que el agua) y fácilmente separables, la retención sea reversible y el vapor pueda ser fácilmente desorbido en el generador, obteniéndose un vapor limpio, sin mezcla. En el absorbedor, la presión de vapor de la solución absorbente/agua depende de la naturaleza del absorbente, de su temperatura y de su concentración. A menor temperatura del absorbente y a mayor concentración, se tendrá la menor presión de vapor en la solución.• They must be less volatile than water (vapor pressure less than water) and easily separable, the retention is reversible and the steam can be easily desorbed in the generator, obtaining a clean, unmixed steam. In the absorber, the vapor pressure of the absorbent / water solution depends on the nature of the absorbent, its temperature and its concentration. At a lower temperature of the absorbent and at a higher concentration, the lowest vapor pressure will be in the solution.
• Buena solubilidad en agua a bajas o moderadas temperaturas.• Good water solubility at low or moderate temperatures.
• Deben trabajar correctamente y ser estables químicamente a las presiones y temperaturas de trabajo (las altas del generador y las bajas del absorbedor) a las cuales será sometido.• They must work correctly and be chemically stable at the pressures and temperatures of work (the high of the generator and the low of the absorber) to which it will be subjected.
• Se aconsejan fluidos no tóxicos ni inflamables.• Non-toxic or flammable fluids are advised.
Algunos ejemplos de los compuestos higroscópicos más conocidos son:
- Cloruro de Sodio (Halita)(ClNa) Cloruro calcico (CaCl2)Some examples of the best known hygroscopic compounds are: - Sodium Chloride (Halite) (ClNa) Calcium Chloride (CaCl 2 )
- Hidróxido de Sodio (NaOH) - Ácido sulfúrico (H2SO4)- Sodium Hydroxide (NaOH) - Sulfuric acid (H 2 SO 4 )
- Sulfato de cobre(CuSO4)- Copper sulfate (CuSO 4 )
Pentóxido de fósforo (P2O5 o más correctamente P4O10) Silica gelPhosphorus pentoxide (P 2 O 5 or more correctly P 4 O 10 ) Silica gel
- Sales hidratadas como Na2SO4-IOH2O - LiBr (el más utilizado en la actualidad, sobretodo en máquinas de absorción para generación de frío)- Hydrated salts such as Na 2 SO 4 -IOH 2 O - LiBr (the most commonly used today, especially in absorption machines for cold generation)
- LiCl- LiCl
El ciclo higroscópico incorpora los principios físicos y químicos de las máquinas de absorción para aportar al ciclo Rankine mayor rendimiento y mejores condiciones de refrigeración. Comprende los siguientes equipos principales: a) Turbina de vapor. b) Absorbedor. Puede ser lavador de gases tipo venturi, tipo jet, torre de relleno, torre de pulverización. c) Bomba de condensado. d) Bomba de disolución. e) Recuperador de calor. Puede ser intercambiador de calor tipo carcasa y tubos o tipo placas. f ) Desgasificador térmico. g) Generador de vapor. Puede ser evaporador, caldera o intercambiador de carcasa y tubos. h) Separador de vapor. Depósito con "demister" (desnebulizador) o columna de rectificación. i) Sobrecalentador. j) Válvula de expansión. k) Aerorefrigerante, torre de refrigeración o intercambiador de calor.The hygroscopic cycle incorporates the physical and chemical principles of absorption machines to provide the Rankine cycle with better performance and better cooling conditions. It comprises the following main equipment: a) Steam turbine. b) Absorber. It can be a venturi, jet type, scrubber, spray tower gas scrubber. c) Condensate pump. d) Dissolution pump. e) Heat recovery. It can be a shell and tube or plate type heat exchanger. f) Thermal degasser. g) Steam generator. It can be evaporator, boiler or shell and tube exchanger. h) Steam separator. Deposit with "demister" (nebulizer) or rectification column. i) Superheater. j) Expansion valve. k) Air cooler, cooling tower or heat exchanger.
I) Turbina hidráulica (opcional). m) Sistema de osmosis inversa, nanofiltración, ultrafiltración o microfiltración (opcional). n) Máquina de absorción o adsorción (opcional).I) Hydro turbine (optional). m) Reverse osmosis, nanofiltration, ultrafiltration or microfiltration system (optional). n) Absorption or adsorption machine (optional).
Este ciclo puede incluir muchas de las mejoras incorporadas al ciclo de Rankine (aumento de la presión de inicio de expansión, la disminución de la presión de término de expansión, sobrecalentamiento del vapor, recalentamiento, regeneración, condiciones supercπ'ticas) antes descritas e incorporar cualquier equipo que permita poner en contacto el vapor con el compuesto higroscópico elegido (tanto absorción como adsorción).
Siguiendo el diagrama de proceso de la figura 1 , se partirá del vapor saturado a baja presión y temperatura (desde 0,01 a 0,2 bar(a) generalmente) que abandona la turbina de vapor. Este vapor se dirige al absorbedor donde se absorbe y diluye en contacto con los compuestos higroscópicos seleccionados (principalmente sales), por ejemplo bromuro de litio (LiBr), cloruro de litio (LiCl), sulfato sódico (Na2SO4), etc., cuya concentración dependerá de la presión del vapor a absorber y las condiciones de refrigeración disponibles. La energía térmica liberada durante el proceso de absorción proviene del calor de condensación, calor sensible y calor de disolución ó dilución. Debido a este calor de absorción, la disolución contenida en el absorbedor suele estar a una temperatura más alta que la del vapor de agua de alimentación. Esta diferencia de temperaturas depende del compuesto higroscópico o mezcla de ellos elegida y su concentración. Para disminuir la corrosión producida por la disolución de los compuestos higroscópicos se recomienda utilizar inhibidores.This cycle may include many of the improvements made to the Rankine cycle (pressure increase start of expansion, decreasing the pressure term expansion, vapor superheat, reheat, regeneration, supercπ conditions' tics) described above and incorporating any equipment that allows the steam to be in contact with the chosen hygroscopic compound (both absorption and adsorption). Following the process diagram in Figure 1, it will start from saturated steam at low pressure and temperature (from 0.01 to 0.2 bar (a) generally) leaving the steam turbine. This vapor is directed to the absorber where it is absorbed and diluted in contact with the selected hygroscopic compounds (mainly salts), for example lithium bromide (LiBr), lithium chloride (LiCl), sodium sulfate (Na 2 SO 4 ), etc. , whose concentration will depend on the pressure of the vapor to be absorbed and the available cooling conditions. The thermal energy released during the absorption process comes from the heat of condensation, sensible heat and heat of dissolution or dilution. Due to this heat of absorption, the solution contained in the absorber is usually at a higher temperature than that of the feed water vapor. This temperature difference depends on the hygroscopic compound or mixture chosen and its concentration. To reduce the corrosion produced by the dissolution of the hygroscopic compounds it is recommended to use inhibitors.
Esta disolución diluida procedente del absorbedor es aspirada por la bomba de condensado y una parte es impulsada, previo paso por el recuperador entálpico, al desgasificador térmico o tanque desaireador del generador de vapor y la otra parte actúa de reflujo del absorbedor. El degasificador térmico es un tanque utilizado para extraer el oxígeno y otros gases disueltos de la disolución y calentar y almacenar el agua de alimentación al generador de vapor. Este equipo puede conectarse a una línea de vapor a baja presión procedente de un sangrado de la turbina de vapor con el fin de remover el oxígeno y gases disueltos y favorecer su eliminación. El recuperador de calor es un intercambiador que precalienta la disolución diluida procedente del absorbedor, con la disolución caliente que retorna del separador de vapor. Su objetivo es aumentar la temperatura de la disolución que alimenta al desgasificador y enfriar la disolución concentrada que retorna al absorbedor.This diluted solution from the absorber is aspirated by the condensate pump and one part is driven, after passing through the enthalpy recuperator, to the thermal degasser or deaerator tank of the steam generator and the other part acts as a reflux of the absorber. The thermal degasifier is a tank used to extract oxygen and other dissolved gases from the solution and heat and store the feed water to the steam generator. This equipment can be connected to a low pressure steam line from a bleeding of the steam turbine in order to remove the oxygen and dissolved gases and favor its elimination. The heat recuperator is an exchanger that preheats the diluted solution from the absorber, with the hot solution returning from the steam separator. Its objective is to increase the temperature of the solution that feeds the degasser and cool the concentrated solution that returns to the absorber.
La disolución diluida desde el desgasificador es impulsada a alta presión al generador de vapor mediante la bomba de disolución. En el generador se suministra la energía necesaria para hervir a alta presión y temperatura con el fin de concentrar la disolución absorbente y obtener un vapor de agua limpio que será alimentado a la turbina de vapor, pasando previamente por el sobrecalentador, del cual se obtendrá un vapor sobrecalentado necesario para aumentar el rendimiento del proceso y conseguir un vapor más seco a la salida de la turbina. La pureza del vapor se consigue gracias al separador de vapor con "demister" (desnebulizador) incorporado o una torre de rectificación. La energía aportada al generador de vapor y sobrecalentador puede proceder de un fluido térmico, energía de origen nuclear, energía solar, un proceso de combustión, cuyas fuentes energéticas pueden ser el calor de los gases de escape de un motor de combustión interna, calor de los gases de escape de una turbina de gas, calor obtenido a partir del quemado de un combustible o biomasa, calor residual de procesos industriales...
La disolución concentrada que abandona el recuperador de calor se dirige al aerorefrigerante, intercambiador de calor o torre de refrigeración con el objetivo de disipar el calor de absorción (calor de condensación más calor de disolución) para evitar que la temperatura suba y así se pueda absorber una cantidad máxima de vapor de agua. Después de enfriarse entra en el absorbedor a baja presión previo paso por la válvula de expansión donde pierde casi toda la presión que tiene el fluido.The diluted solution from the degasser is driven at high pressure to the steam generator by means of the dissolution pump. In the generator the necessary energy to boil at high pressure and temperature is supplied in order to concentrate the absorbent solution and obtain a clean water vapor that will be fed to the steam turbine, previously passing through the superheater, from which a Superheated steam needed to increase the process performance and achieve a drier steam at the turbine outlet. Steam purity is achieved thanks to the steam separator with built-in "demister" (de-fogger) or a rectification tower. The energy provided to the steam generator and superheater can come from a thermal fluid, nuclear energy, solar energy, a combustion process, whose energy sources can be the heat of the exhaust gases of an internal combustion engine, heat of the exhaust gases of a gas turbine, heat obtained from the burning of a fuel or biomass, waste heat from industrial processes ... The concentrated solution that leaves the heat recuperator is directed to the air cooler, heat exchanger or cooling tower in order to dissipate the absorption heat (condensation heat plus dissolution heat) to prevent the temperature from rising and thus be absorbed a maximum amount of water vapor. After cooling, it enters the absorber at low pressure after passing through the expansion valve where it loses almost all the pressure that the fluid has.
El vapor de salida del sobrecalentador (vapor vivo) se encuentra a las condiciones necesarias para poder ser expandido en la turbina de vapor, la cual está conectada a un generador que producirá la potencia eléctrica gracias al trabajo producido. El vapor de salida a baja presión y temperatura volvería a realizar el ciclo antes descrito.The outlet steam of the superheater (live steam) is at the necessary conditions to be expanded in the steam turbine, which is connected to a generator that will produce the electric power thanks to the work produced. The steam at low pressure and temperature would return to the cycle described above.
Se incluye en la presente patente el proceso representado en la figura 2. Se trata del mismo proceso explicado anteriormente pero incluyendo opcionalmente una serie de equipos que mejoran las prestaciones del ciclo y con ello el rendimiento global. Los equipos son los siguientes:The process represented in Figure 2 is included in this patent. It is the same process explained above but optionally including a series of equipment that improves the performance of the cycle and thereby the overall performance. The teams are as follows:
1. Turbina hidráulica. Su misión es recuperar la mayor parte de la energía que origina el salto de presión de la disolución concentrada desde el separador de vapor hasta el absorbedor. La válvula de expansión en este caso perdería muy poca presión.1. Hydro turbine. Its mission is to recover most of the energy that causes the pressure jump of the concentrated solution from the steam separator to the absorber. The expansion valve in this case would lose very little pressure.
2. Sistema, membrana o filtros de osmosis inversa, nanofiltración, ultrafiltración o microfiltración. Dependiendo del tipo de compuestos higroscópicos seleccionados se instalará uno u otro tipo de sistemas. El objetivo es separar la mayor parte de los compuestos higroscópicos del agua, los cuales se recirculan al absorbedor. Gracias a ello, se puede incrementar la presión del vapor en el generador de vapor la cual se ve afectada por la presencia de los compuestos higroscópicos seleccionados y su concentración. También se reduce el coste de los materiales a emplear en el generador de vapor y se aumenta la vida útil de los equipos. La energía requerida en este tipo de filtros la mayoría de las veces es en forma de presión, cuya bomba formará parte del sistema de filtración seleccionado.2. System, membrane or filters of reverse osmosis, nanofiltration, ultrafiltration or microfiltration. Depending on the type of hygroscopic compounds selected, one or the other type of system will be installed. The objective is to separate most of the hygroscopic compounds from water, which are recirculated to the absorber. Thanks to this, the steam pressure in the steam generator can be increased which is affected by the presence of the selected hygroscopic compounds and their concentration. The cost of the materials to be used in the steam generator is also reduced and the useful life of the equipment is increased. The energy required in this type of filters is mostly in the form of pressure, whose pump will be part of the selected filtration system.
3. Máquina de absorción/adsorción. Después del aprovechamiento térmico en el generador de vapor, la mayoría de las veces tenemos energía disponible a baja temperatura la cual puede ser aprovechada para enfriar la disolución diluida que debe retornar al absorbedor. Al requerirse niveles de temperatura a partir de 80 0C en el caso de las máquinas de absorción y 50 0C para las máquinas de adsorción, estos equipos permiten optimizar energéticamente el proceso y aportar bajas temperaturas de refrigeración necesarias para bajar la presión de condensación de la turbina. En motores de gas, diesel
u otros, se puede aprovechar para este propósito la energía que se necesita disipar en el circuito de refrigeración de alta temperatura.3. Absorption / adsorption machine. After thermal use in the steam generator, most of the time we have energy available at low temperature which can be used to cool the diluted solution that must return to the absorber. When temperature levels from 80 0 C are required in the case of absorption machines and 50 0 C for adsorption machines, these equipments allow energy optimization of the process and provide low cooling temperatures necessary to lower the condensation pressure of the turbine In gas engines, diesel or others, the energy that needs to dissipate in the high temperature cooling circuit can be used for this purpose.
Como anotación importante, se recomienda elegir compuestos o combinaciones entre ellos donde el calor de disolución sea endotérmico (mezclado endotérmico), para compensar el calor de condensación exotérmico liberado en la fase de absorción o adsorción, aumentando con ello el rendimiento del ciclo y consiguiendo ahorrar energía en el sistema de refrigeración elegidoAs an important annotation, it is recommended to choose compounds or combinations between them where the heat of dissolution is endothermic (endothermic mixing), to compensate for the heat of exothermic condensation released in the absorption or adsorption phase, thereby increasing the cycle performance and saving energy in the chosen cooling system
(intercambiador de calor, aerorefrigerante o torre de refrigeración) con posibilidad de eliminarlo. El calor de absorción que mantiene la disolución diluida a una temperatura superior a la del vapor que abandona la turbina se utilizará después para producir vapor útil al proceso. Por ello que se aproveche parte de la entalpia del vapor de salida de la turbina en el absorbedor y se aumente en el generador con el aporte de calor.(heat exchanger, air cooler or cooling tower) with the possibility of eliminating it. The heat of absorption that keeps the diluted solution at a temperature higher than that of the steam leaving the turbine will then be used to produce steam useful to the process. For this reason, part of the enthalpy of the steam coming out of the turbine in the absorber is used and the generator is increased with the heat input.
También se recomienda trabajar con compuestos higroscópicos con buena solubilidad a las bajas o moderadas temperaturas del absorbedor (<100°C) y baja solubilidad a las altas temperaturasIt is also recommended to work with hygroscopic compounds with good solubility at low or moderate absorber temperatures (<100 ° C) and low solubility at high temperatures
(>1 OO0C) existentes en el generador de vapor (solubilidad decreciente con la temperatura o solubilidad inversa). En este punto se favorece la condensación en el absorbedor a temperaturas superiores al vapor de alimentación y se consiguen presiones de vapor cercanas a las del agua pura en el generador de vapor. En este caso la disolución procedente del separador de vapor estaría sobresaturada, diluyéndose completamente al disminuir su temperatura mediante su paso por el recuperador entálpico. Ejemplo de compuesto higroscópico con tal comportamiento es el sulfato sódico (Na2SO4 ).(> 1 OO 0 C) existing in the steam generator (decreasing solubility with temperature or inverse solubility). At this point condensation in the absorber at temperatures higher than the feed vapor is favored and vapor pressures close to those of pure water in the steam generator are achieved. In this case, the solution from the steam separator would be supersaturated, diluting completely by decreasing its temperature by passing through the enthalpy recuperator. An example of a hygroscopic compound with such behavior is sodium sulfate (Na 2 SO 4 ).
En este ciclo la condensación del vapor tiene lugar encima de una película de líquido del absorbente donde unas moléculas condensan inmediatamente y se disuelven en la película de solución dejando espacio para nuevas moléculas reduciendo así la presión de condensación. Para ello, es necesario disipar el calor de absorción antes comentado para que el proceso no se interrumpa. Las condiciones de refrigeración de este sistema son menos exigentes que los actuales ciclos de Rankine trabajando a vacío.In this cycle the condensation of the steam takes place on top of a film of liquid of the absorbent where some molecules condense immediately and dissolve in the solution film leaving space for new molecules thus reducing the condensation pressure. For this, it is necessary to dissipate the heat of absorption mentioned above so that the process is not interrupted. The cooling conditions of this system are less demanding than the current Rankine cycles working under vacuum.
El rendimiento del ciclo (η) se determina como el cociente entre la resta del trabajo producido por las turbinas (turbina de vapor más turbina hidráulica (si existe), W1 y W4 respectivamente) y el consumido por la bomba de condensado (W2), bomba de disolución (W3) y sistema de osmosis inversa, nanofiltración, ultrafiltración o microfiltración (W5), si existe, partido del calor cedido al vapor desde el generador de vapor (Q2), sobrecalentador (OJ ) y máquina de absorción (Q3), si esta última existe. Se representa en la siguiente fórmula:
WI + W4- W2 - W3 - W5The cycle performance (η) is determined as the ratio between the subtraction of the work produced by the turbines (steam turbine plus hydraulic turbine (if any), W1 and W4 respectively) and that consumed by the condensate pump (W2), dissolution pump (W3) and reverse osmosis, nanofiltration, ultrafiltration or microfiltration system (W5), if any, split from heat transferred to steam from the steam generator (Q2), superheater (OJ) and absorption machine (Q3) , if the latter exists. It is represented in the following formula: WI + W4- W2 - W3 - W5
7 = QI + Q2 + Q37 = QI + Q2 + Q3
El rendimiento depende de las condiciones de operación seleccionadas y los compuestos higroscópicos elegidos y su concentración. Los rendimientos típicos se encuentran entre 1 y 5% por encima de los actuales ciclos de Rankine.The performance depends on the selected operating conditions and the hygroscopic compounds chosen and their concentration. Typical yields are between 1 and 5% above the current Rankine cycles.
El ciclo higroscópico consigue:The hygroscopic cycle achieves:
> Elevados rendimientos al aprovechar parte de la entalpia del vapor a la salida de la turbina, disminuir las pérdidas térmicas, aprovechar la energía térmica de la disolución concentrada procedente del generador de vapor para aportar a la disolución diluida la energía necesaria para alcanzar las condiciones de desgasificación, y sobretodo por poder trabajar la turbina con mayor diferencia de presiones (elevado vacío a la salida de la turbina) sin tener limitada la temperatura de refrigeración. El calor de absorción puede ser utilizado para producir vapor a temperatura superior a la del vapor de alimentación del absorbedor. Este aumento de rendimiento se puede observar en la figura 3 (diagrama T-S del ciclo de Rankine).> High yields when taking advantage of part of the enthalpy of steam at the exit of the turbine, reducing thermal losses, taking advantage of the thermal energy of the concentrated solution from the steam generator to provide the diluted solution with the energy needed to reach the conditions of degassing, and above all for being able to work the turbine with greater pressure difference (high vacuum at the turbine outlet) without having limited the cooling temperature. The heat of absorption can be used to produce steam at a temperature higher than that of the feed steam of the absorber. This increase in performance can be seen in Figure 3 (T-S diagram of the Rankine cycle).
> Mejorar las condiciones de refrigeración del ciclo. Se disminuye la energía calorífica disipada en el aerorefrigerante, torre de refrigeración o intercambiador de calor.> Improve the cooling conditions of the cycle. The heat energy dissipated in the air cooler, cooling tower or heat exchanger is decreased.
Dependiendo de los compuestos higroscópicos elegidos y su concentración, la temperatura de refrigeración necesaria del ciclo se encuentra normalmente entre 1 y 80 0C por encima de la temperatura del vapor a la salida de la turbina, con posibilidad de eliminar la refrigeración (mezclado endotérmico). Este efecto permite trabajar en condiciones de vacío más severas (en torno 0,01 bar) sin tener limitada la temperatura de refrigeración.Depending on the hygroscopic compounds chosen and their concentration, the necessary refrigeration temperature of the cycle is normally between 1 and 80 ° C above the steam temperature at the turbine outlet, with the possibility of eliminating cooling (endothermic mixing). This effect allows working in more severe vacuum conditions (around 0.01 bar) without having the cooling temperature limited.
Aplicaciones industrialesIndustrial applications
En todas aquellas plantas que utilicen o puedan utilizar un ciclo de Rankine o similar, para generación de trabajo mecánico, o producción de energía eléctrica. Las principales plantas de potencia donde puede instalarse son las centrales termoeléctricas (petróleo, carbón y gas natural, otros combustibles), nucleares, de biomasa y termosolares.In all those plants that use or can use a Rankine cycle or similar, for the generation of mechanical work, or production of electrical energy. The main power plants where it can be installed are thermoelectric plants (oil, coal and natural gas, other fuels), nuclear, biomass and solar thermal.
También en aquellas plantas de cogeneración o trigeneración donde el calor de condensación que debe liberarse en el aerorefrigerante, torre de refrigeración o intercambiador de calor es recuperado como energía térmica para otro proceso.
Explicación de los dibujosAlso in those cogeneration or trigeneration plants where the heat of condensation that must be released in the air cooler, cooling tower or heat exchanger is recovered as thermal energy for another process. Explanation of the drawings
La figura 1 representa el diagrama de proceso del ciclo higroscópico incluyendo los equipos principales tal como se detalla en la descripción.Figure 1 represents the process diagram of the hygroscopic cycle including the main equipment as detailed in the description.
La figura 2 representa el diagrama de proceso del ciclo higroscópico incluyendo como equipos opcionales una turbina hidráulica, un sistema de filtración por osmosis inversa, nanofiltración ultrafiltración o microfiltración y una máquina de absorción o adsorción; equipos explicados anteriormente.Figure 2 represents the process diagram of the hygroscopic cycle including as optional equipment a hydraulic turbine, a reverse osmosis filtration system, ultrafiltration or microfiltration nanofiltration and an absorption or adsorption machine; equipment explained above.
La figura 3 representa un diagrama temperatura - entropía típico de los ciclos de Rankine.Figure 3 represents a typical temperature - entropy diagram of Rankine cycles.
Existen cuatro procesos distintos en el desarrollo del ciclo, los cuales van cambiando el estado del fluido. Los procesos son los siguientes (suponiendo ciclo ideal con procesos internamente reversibles):There are four different processes in the development of the cycle, which change the state of the fluid. The processes are as follows (assuming an ideal cycle with internally reversible processes):
• Proceso 1 - 2' : Expansión isoentrópica del fluido de trabajo en la turbina desde la presión del generador hasta la presión del absorbedor.• Process 1 - 2 ' : Isoentropic expansion of the working fluid in the turbine from the generator pressure to the absorber pressure.
• Proceso 2'- 3' : Transmisión de calor del vapor con el compuesto higroscópico a presión constante en el absorbedor hasta el estado de líquido saturado. • Proceso 3' - 4' : Compresión isoentrópica en la bomba. En él se aumenta la presión del fluido mediante un compresor o bomba al que se le aporta un determinado trabajo.• Process 2 ' - 3 ' : Steam heat transmission with the hygroscopic compound at constant pressure in the absorber to the state of saturated liquid. • Process 3 ' - 4 ' : Isoentropic compression in the pump. It increases the pressure of the fluid through a compressor or pump that is given a certain job.
• Proceso 4' - 1 ' : Transmisión de calor hacia el fluido de trabajo a presión constante en el generador y sobrecalentador. Los procesos no son internamente reversibles, existen distintas irreversibilidades y pérdidas.• Process 4 ' - 1 ' : Heat transmission to the working fluid at constant pressure in the generator and superheater. The processes are not internally reversible, there are different irreversibilities and losses.
En dicha figura se detalla la ecuación de rendimiento para dos casos cuya diferencia principal radica en las condiciones de temperatura a la salida de la turbina y el ligero sobrecalentamiento aportado para mantener el mismo grado de humedad en la salida. El rendimiento 2, cuyos puntos son 1 ' , 2' , 3 ' y 4' es mayor que el rendimiento 1 del primer caso, cuyos puntos son 1 , 2, 3 y 4. Este incremento de rendimiento se puede observar en el área rayada, siendo típica de los ciclos higroscópicos frente a los ciclos de Rankine o similares, dado que se puede trabajar con mayores condiciones de vacío (menor temperatura) para las mismas condiciones de refrigeración. Además se puede aprovechar el calor de absorción para producir vapor a temperatura superior a la del vapor de alimentación al absorbedor.This figure details the performance equation for two cases whose main difference lies in the temperature conditions at the turbine outlet and the slight overheating provided to maintain the same degree of humidity at the outlet. Performance 2, whose points are 1 ' , 2 ' , 3 ' and 4 ' is greater than performance 1 of the first case, whose points are 1, 2, 3 and 4. This increase in performance can be observed in the scratched area , being typical of hygroscopic cycles versus Rankine or similar cycles, since it is possible to work with higher vacuum conditions (lower temperature) for the same cooling conditions. In addition, the heat of absorption can be used to produce steam at a temperature higher than that of the steam supplied to the absorber.
En la figura 4 se representa el consumo o generación de energía en forma de trabajo o de calor que tienen los equipos existentes, mostrando en cada punto del proceso una descripción de cada corriente.
Figure 4 shows the consumption or generation of energy in the form of work or heat of existing equipment, showing at each point of the process a description of each current.
Claims
1. Ciclo higroscópico basado en las propiedades de los compuestos higroscópicos para absorber o adsorber agua en forma de vapor. Incorpora los principios físicos y químicos de las máquinas de absorción para aportar al ciclo Rankine mayor rendimiento y mejores condiciones de refrigeración. Se caracteriza porque estos compuestos absorben el vapor de agua a baja presión y temperatura que ha sido expandido en la turbina y se desorben del agua en el generador a las condiciones necesarias de operación. En el absorbedor se aprovecha la entalpia del vapor y se aumenta en el generador con el aporte de calor. Los compuestos higroscópicos deben ser químicamente estables, con buena solubilidad a bajas y moderadas temperaturas con el agua, fácilmente separables (retención reversible) y menos volátiles que el agua, aportando elevada afinidad por la misma. La turbina puede trabajar con altos vacíos (en torno 0,01 bar) y dependiendo de los compuestos higroscópicos elegidos y su concentración, las condiciones de refrigeración del proceso se encuentran normalmente entre 1 y 800C por encima de la temperatura de salida del vapor en la turbina, con posibilidad de eliminar la refrigeración (mezclado endotérmico de los compuestos).1. Hygroscopic cycle based on the properties of hygroscopic compounds to absorb or adsorb water in the form of steam. It incorporates the physical and chemical principles of absorption machines to provide the Rankine cycle with better performance and better cooling conditions. It is characterized in that these compounds absorb water vapor at low pressure and temperature that has been expanded in the turbine and are desorbed from the water in the generator at the necessary operating conditions. The enthalpy of the steam is used in the absorber and is increased in the generator with the heat input. The hygroscopic compounds must be chemically stable, with good solubility at low and moderate temperatures with water, easily separable (reversible retention) and less volatile than water, providing high affinity for it. The turbine can work with high voids (around 0.01 bar) and depending on the hygroscopic compounds chosen and their concentration, the cooling conditions of the process are normally between 1 and 80 0 C above the steam outlet temperature in the turbine, with the possibility of eliminating cooling (endothermic mixing of the compounds).
Este ciclo puede incluir muchas de las mejoras realizadas al ciclo de Rankine (aumento de la presión de inicio de expansión, la disminución de la presión de término de expansión, sobrecalentamiento del vapor, recalentamiento, regeneración, condiciones supercríticas), y se aplica en plantas donde exista o pueda existir un ciclo de Rankine o similar, para realizar un trabajo mecánico o generación de energía eléctrica (centrales termoeléctricas, nucleares, de biomasa, termosolares).This cycle can include many of the improvements made to the Rankine cycle (increase in the expansion start pressure, decrease in the expansion end pressure, steam overheating, overheating, regeneration, supercritical conditions), and applied in plants where there is or may exist a Rankine cycle or similar, to perform a mechanical work or generation of electrical energy (thermoelectric, nuclear, biomass, thermosolar plants).
Comprende los siguientes equipos principales:It comprises the following main equipment:
a) Turbina de vapor b) Absorbedor c) Bomba de condensado d) Bomba de disolución e) Recuperador de calor f ) Desgasificador térmico g) Generador de vapor h) Separador de Vapor i) Sobrecalentador j) Válvula de expansión k) Aerorefrigerante, torre de refrigeración o intercambiador de calor a) Steam turbine b) Absorber c) Condensate pump d) Dissolution pump e) Heat recovery f) Thermal degasser g) Steam generator h) Steam separator i) Superheater j) Expansion valve k) Air cooler, tower cooling or heat exchanger
2. Una instalación según reivindicación 1 aplicada a una planta de cogeneración o trigeneración. En este caso el calor de condensación que debe liberarse en el aerorefrigerante, torre de refrigeración o intercambiador de calor es recuperado como energía térmica para otro proceso.2. An installation according to claim 1 applied to a cogeneration or trigeneration plant. In this case the heat of condensation that must be released in the air cooler, cooling tower or heat exchanger is recovered as thermal energy for another process.
3. Una instalación según reivindicación 1 que incorpora una turbina hidráulica para poder recuperar la mayor parte de la energía que origina el salto de presión de la disolución concentrada desde el separador de vapor hasta el absorbedor. Con ello se aumenta el rendimiento global del ciclo.3. An installation according to claim 1 incorporating a hydraulic turbine in order to recover most of the energy caused by the pressure drop of the concentrated solution from the steam separator to the absorber. This increases the overall performance of the cycle.
4. Una instalación según reivindicación 1 que incorpora un sistema de filtración o membranas por osmosis inversa, nanofiltración, ultrafiltración o microfiltración (dependiendo del tamaño de los compuestos higroscópicos seleccionados) para separar la mayor parte de los compuestos higroscópicos de la disolución diluida y recircularlos al absorbedor con el fin de diluir aún más la disolución diluida antes de llegar al generador de vapor, consiguiendo aumentar las presiones de vapor en dicho equipo. Con ello se aumenta el rendimiento global del ciclo y vida útil de los equipos.4. An installation according to claim 1 incorporating a filtration system or membranes by reverse osmosis, nanofiltration, ultrafiltration or microfiltration (depending on the size of the selected hygroscopic compounds) to separate most of the hygroscopic compounds from the diluted solution and recirculate them absorber in order to further dilute the diluted solution before reaching the steam generator, increasing steam pressures in said equipment. This increases the overall cycle performance and life of the equipment.
5. Una instalación según reivindicación 1 que incorpora una máquina de absorción o adsorción para enfriar la disolución diluida de retorno al absorbedor aprovechando la energía aún disponible en el proceso. Con ello se aumenta el rendimiento global del ciclo.5. An installation according to claim 1 incorporating an absorption or adsorption machine to cool the diluted solution back to the absorber taking advantage of the energy still available in the process. This increases the overall performance of the cycle.
6. Se hace énfasis en una importante característica que deben tener los compuestos higroscópicos seleccionados. Se recomiendan compuestos higroscópicos con buena solubilidad a las bajas o moderadas temperaturas del absorbedor y baja solubilidad a las altas temperaturas existentes en el generador de vapor (solubilidad decreciente con la temperatura o solubilidad inversa). En este punto se favorece la condensación en el absorbedor a temperaturas superiores al vapor de alimentación y se consiguen presiones de vapor cercanas a las del agua pura en el generador de vapor. En este caso la disolución procedente del separador de vapor estaría sobresaturada, diluyéndose completamente al disminuir su temperatura mediante su paso por el recuperador entálpico. Ejemplo de compuesto higroscópico con tal comportamiento es el sulfato sódico (Na2SO4 ). 6. Emphasis is placed on an important characteristic that selected hygroscopic compounds must have. Hygroscopic compounds with good solubility at low or moderate temperatures of the absorber and low solubility at the high temperatures existing in the steam generator (decreasing solubility with temperature or inverse solubility) are recommended. At this point condensation in the absorber at temperatures higher than the feed vapor is favored and vapor pressures close to those of pure water in the steam generator are achieved. In this case, the solution from the steam separator would be supersaturated, diluting completely by decreasing its temperature by passing through the enthalpy recuperator. An example of a hygroscopic compound with such behavior is sodium sulfate (Na 2 SO 4 ).
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Publication number | Priority date | Publication date | Assignee | Title |
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WO2019224209A1 (en) * | 2018-05-23 | 2019-11-28 | Gios Bart | Closed-cycle absorption system and method for cooling and generating power |
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US4102388A (en) * | 1976-09-23 | 1978-07-25 | Shell Oil Company | Heat recovery process |
US4195485A (en) * | 1978-03-23 | 1980-04-01 | Brinkerhoff Verdon C | Distillation/absorption engine |
EP0101244A2 (en) * | 1982-08-06 | 1984-02-22 | Alexander I. Kalina | Generation of energy |
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2010
- 2010-05-13 WO PCT/ES2010/000208 patent/WO2010133726A1/en active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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US4102388A (en) * | 1976-09-23 | 1978-07-25 | Shell Oil Company | Heat recovery process |
US4195485A (en) * | 1978-03-23 | 1980-04-01 | Brinkerhoff Verdon C | Distillation/absorption engine |
EP0101244A2 (en) * | 1982-08-06 | 1984-02-22 | Alexander I. Kalina | Generation of energy |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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WO2019224209A1 (en) * | 2018-05-23 | 2019-11-28 | Gios Bart | Closed-cycle absorption system and method for cooling and generating power |
BE1026296B1 (en) * | 2018-05-23 | 2019-12-23 | B Gios | ABSORPTION SYSTEM WITH CLOSED CYCLE AND METHOD FOR COOLING AND GENERATING POWER |
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