CN115288819A - Supercritical CO under oxygen-enriched combustion of coal 2 Recompression Brayton cycle coupling carbon capture novel combined system and simulation method - Google Patents
Supercritical CO under oxygen-enriched combustion of coal 2 Recompression Brayton cycle coupling carbon capture novel combined system and simulation method Download PDFInfo
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Abstract
The invention relates to supercritical CO under coal oxygen-enriched combustion 2 The invention discloses a recompression Brayton cycle coupling carbon capture novel combined system and a simulation method, belongs to the technical field of energy power, and mainly provides a system for supercritical CO 2 Novel combined system of power cycle: supercritical CO under oxygen-enriched combustion of coal 2 And then compressing the Brayton cycle coupled carbon capture system. Firstly, the coal is supercritical CO under oxygen-enriched combustion 2 And the heat source is provided by the compression Brayton cycle, so that the fuel is more fully combusted, and the efficiency of the whole power cycle is improved. Then the coupling carbon capture system realizes the emission reduction and low carbon of power cycle and is constructed simultaneouslyA thermodynamic simulation model was developed that was modular programmed using Python. The boiler inlet O can be obtained by utilizing the simulation model 2 The influence of concentration and exhaust gas temperature on boiler efficiency and electric efficiency, the influence of turbine inlet temperature and pressure and the influence of main compressor inlet temperature and pressure on cycle efficiency and electric efficiency provide the basis of optimizing reference for a novel combined system.
Description
Technical Field
The invention relates to supercritical CO 2 Recompression Brayton power cycle technology, in particular to supercritical CO under coal oxygen-enriched combustion 2 A novel recompression Brayton cycle coupled carbon capture combined system and a simulation method belong to the technical field of energy power.
Background
As global climate changes increase, there is an increasing interest in reducing carbon emissions. CO is introduced according to the type of combustion 2 The trapping technique is divided into: carbon capture before combustion, oxygen-enriched combustion carbon capture and carbon capture after combustion. Researchers have studied and evaluated the detailed arrangement of pulverized coal oxygen-rich combustion power plants, and the results showed that up to 93.3% of CO is produced during the combustion process 2 And 95% SO 2 Can be captured and compressed to a supercritical pressure of 110bar, producing sequesterable CO having a purity of 95.5mol% 2 Flow, carbon capture is achieved, but the energy penalty of this set of technology is equivalent to a reduction in the net plant efficiency of about 8.5%. Development of supercritical CO with research 2 (Supercritical CO 2 ,sCO 2 ) The power cycle has the advantages of low critical parameters (304.13K, 7.377 MPa), compact system and high heat source temperature>The efficiency at 550 ℃ is higher than that of a steam Rankine cycle, and CO 2 The chemical reaction rate with metal materials is less than that of water vapor, and the like, and the method is widely concerned by the scientific field. In which supercritical CO is based on oxygen-enriched combustion of coal 2 The recompression cycle compound power generation system can improve the power supply efficiency of the system to 43.76 percent by using an air separation device and cycle heat integration, which is 1.93 percent higher than that of a system without integration, but the content of generated carbide is much higher than that of the system without integration due to oxygen-enriched combustion, thereby causing serious carbon emission.
The prior technical scheme is that the traditional carbon capture and the traditional steam cycle power plant are combined and transformed, and sCO is generated under the condition of lack of oxygen-enriched combustion 2 The design of the coupling construction of the power cycle and the carbon capture system is not specially used for oxygen-enriched combustion carbon capture and sCO 2 Techniques for analyzing the impact of system performance of power cycle coupling.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides supercritical CO under coal oxygen-enriched combustion 2 And then a novel combined system and a simulation method for coupling the recompression Brayton cycle and the carbon capture are adopted. The invention mainly provides a method for supercritical CO 2 Novel combined system of power cycle: supercritical CO under coal oxygen-enriched combustion 2 And then compressing the Brayton cycle coupled carbon capture system. Firstly, supercritical CO is generated by using coal under oxygen-enriched combustion 2 And the heat source is provided by the compression Brayton cycle, so that the fuel is more fully combusted, and the efficiency of the whole power cycle is improved. And then the carbon capture system is coupled to realize emission reduction and low carbon of a power cycle, and the conception and the design of the whole system are shown in figure 1. Supercritical CO for coal oxygen-enriched combustion 2 The recompression brayton cycle coupled carbon capture system builds a thermodynamic simulation model that is modularly programmed using Python. The boiler inlet O can be obtained by utilizing the simulation model 2 The influence of concentration and exhaust gas temperature on boiler efficiency and electric efficiency, the influence of turbine inlet temperature and pressure and the influence of main compressor inlet temperature and pressure on cycle efficiency and electric efficiency provide optimization reference for novel combined systemAccording to the method.
The technical scheme of the invention is as follows:
sCO under oxygen-enriched combustion of coal 2 A recompression Brayton cycle coupled carbon capture novel combined system comprising sCO 2 Then compressing Brayton cycle and oxygen-enriched combustion and carbon capture external cycle;
the external circulation comprises an air separation plant, a combustion chamber, a denitration device, an electrostatic dust collector, a desulfurization device and CO according to the flowing direction of gas 2 The outlet end of the electrostatic dust collector is connected to the inlet end of the combustion chamber through a shunt pipeline as circulating flue gas, and an external circulating machine is arranged on the shunt pipeline; air intake air separation plant manufacturing O 2 Mixing with circulating flue gas in proportion, feeding into combustion chamber, and performing oxygen-enriched combustion with coal to obtain CO 2 The flue gas is divided after passing through the denitration device and the electrostatic dust collector in sequence, one part of the flue gas is returned to the combustion chamber as circulating flue gas to adjust the flame temperature of the boiler, and the other part of the flue gas enters the desulphurization device to be desulfurized and then enters CO 2 Compression and purification unit to form CO 2 The product is convenient to store or transport;
sCO 2 the recompression Brayton cycle comprises a turbine, a heat regenerator, a precooler and a compressor in the flow direction, wherein the heat regenerator comprises a high-temperature heat regenerator and a low-temperature heat regenerator, the compressor comprises a main compressor and a recompressor, and a working medium flows through a combustion chamber to absorb heat to form high-temperature high-pressure sCO 2 Fluid, sCO 2 After entering a turbine expansion working, the mixed gas enters a high-temperature heat regenerator and a low-temperature heat regenerator in sequence to release heat in an isobaric manner, then is divided into two streams according to a flow dividing ratio, one stream enters a main compressor through a precooler to be subjected to adiabatic compression, then enters the low-temperature heat regenerator to absorb heat, the other stream directly enters a recompressor to be subjected to adiabatic compression, the two streams are converged and mixed, then enter the high-temperature heat regenerator to absorb heat, finally returns to a combustion chamber to recover to a high-temperature high-pressure state, and the whole cycle is completed.
Supercritical CO 2 The specific heat capacity of (C) varies greatly with pressure, so that sCO 2 The simple Brayton cycle has great irreversibility in the regenerator due to imbalance of heat capacity between hot side and cold side fluids, and the problem of pinch point in the regenerator, so the power system of the invention adopts sCO 2 Recompression of the Brayton cycle, partial CO being discharged without heat by splitting 2 The stream is recompressed to compensate for the difference in heat capacity in the Low Temperature Regenerator (LTR), improving efficiency. As the LTR efficiency increases, the heat flux enters the High Temperature Regenerator (HTR) at a higher temperature, which in turn increases the temperature of the heat flux leaving the HTR, thereby increasing the average temperature of the heating and thus increasing the cycle efficiency. Oxygen-enriched combustion is adopted, and pure oxygen replaces conventional air for combustion, so that coal is combusted more fully, and CO in generated flue gas 2 And (4) enriching. Using a carbon capture system, CO can be carried out after dust and pollutants are removed 2 CO with purity over 96 percent can be obtained by trapping 2 The product finally realizes near zero carbon emission. Captured CO 2 Can be used as chemical raw material and supercritical CO 2 A supplement of working fluid in the power cycle.
Preferably, the diversion point at the outlet of the low-temperature heat regenerator is point a, the confluence point at the outlet of the recompressor is point b, the confluence point of the circulating flue gas and the oxygen is point c, and the diversion point at the outlet section of the electrostatic dust collector is point d.
Further preferably, the pipeline between the combustion chamber and the turbine is numbered 1, the pipeline between the turbine and the high-temperature regenerator is numbered 2, the pipeline between the high-temperature regenerator and the low-temperature regenerator is numbered 3, the pipeline between the low-temperature regenerator and the point a is numbered 4, the pipeline between the precooler and the main compressor is numbered 5, the pipeline between the main compressor and the low-temperature regenerator is numbered 6, the pipeline between the low-temperature regenerator and the point b is numbered 7, the pipeline between the secondary compressor and the point b is numbered 8, the pipeline between the point b and the high-temperature regenerator is numbered 9, the pipeline between the high-temperature regenerator and the combustion chamber is marked with 10, the pipeline between the air separation plant and the point c is marked with 11, the pipeline between the air separation plant and the point c is marked with 12, the pipeline between the point c and the combustion chamber is marked with 13, the pipeline between the combustion chamber and the denitration device is marked with 14, the pipeline between the denitration device and the electrostatic precipitator is marked with 15, the pipeline between the electrostatic precipitator and the point d is marked with 16, the pipeline between the point d and the external circulation machine is marked with 17, the pipeline between the external circulation machine and the point c is marked with 18, the pipeline between the point d and the desulfurization device is marked with 19, the desulfurization device and the CO are marked with 18 2 Compression and purification deviceThe intermediate line is numbered 20, CO 2 The compression and purification unit outlet line is numbered 21.
Supercritical CO under oxygen-enriched combustion of coal 2 According to the simulation method of the recompression Brayton cycle coupling carbon capture novel combined system, the following coupling cycle system mathematical model is established for each part of the system according to energy conservation and mass conservation:
(1) Supercritical CO 2 Recompression Brayton power cycle mathematical model building
The working process of the turbine can be approximately regarded as the adiabatic expansion process, the work W of the turbine t And isentropic efficiency η t Comprises the following steps:
in the formula:
the total mass flow of the working medium is kg/s;
the heat regenerator is a counter-flow heat regenerator and has a pressure loss coefficient of C p And the performance epsilon based on the enthalpy difference represents the performance of the heat regenerator, and the performance epsilon is defined as the ratio of the actual heat exchange quantity to the theoretical maximum heat exchange quantity;
the high-temperature regenerator is regarded as an isobaric heat exchange process, and the efficiency of the high-temperature regenerator is epsilon htr Comprises the following steps:
the low-temperature regenerator is regarded as an isobaric heat exchange process, and the efficiency epsilon of the low-temperature regenerator ltr Comprises the following steps:
or
Wherein if the specific heat capacity of the high pressure fluid exiting the main compressor is greater than the specific heat capacity of the low pressure fluid exiting the high temperature regenerator, then ε ltr Adopting a formula (4); otherwise, adopting formula (5); because carbon dioxide is used as a circulating working medium, the specific heat capacity difference of cold and hot fluids flowing through the low-temperature heat regenerator is large, and the efficiency epsilon of the low-temperature heat regenerator in the programming design of the invention ltr The formula (4) is adopted for calculation, but if the program is changed into water vapor as the working medium, the program design calculation formula of the invention is changed into the formula (5) for calculation;
according to the energy conservation, the heat exchange quantity of the cold fluid and the hot fluid in the heat regenerator reaches heat balance;
heat balance of the high-temperature heat regenerator:
h 2 -h 3 ＝h 10 -h 9 (6)
thermal balance of the low-temperature heat regenerator:
h 3 -h 4 ＝x·(h 7 -h 6 ) (7)
in the formula: x is a flow dividing ratio which is defined as the ratio of the mass flow of the working medium entering the main compressor to the total mass flow of the circulating working medium, preferably, the value of the flow dividing ratio can be selected according to different working conditions, in order to ensure the system circulation efficiency, the value range of the program design is between 0.65 and 0.8, and further preferably, the value selected by the flow dividing ratio in the invention is 0.721;
precooler considered isobaric heat release, process heat change Q pc Comprises the following steps:
the main compressor is regarded as an adiabatic compression process, and the power consumption W of the main compressor mc And isentropic efficiency η mc Comprises the following steps:
the recompressor is regarded as an adiabatic compression process, and the work consumption W of the recompressor rc And isentropic efficiency eta rc Comprises the following steps:
the convergence point b is obtained according to energy conservation:
h 9 ＝x·h 7 +(1-x)h 8 (13)
the heat absorption capacity Q of the working medium is regarded as the isobaric heat absorption process in the combustion chamber c Comprises the following steps:
in the above formula: h is n Is sCO 2 Enthalpy values at each state point of the cycle, kJ/kg; h is ns Is sCO 2 Ideal enthalpy at each state point of the cycle, kJ/kg; t is a unit of n Is sCO 2 And (3) circulating the temperature and the DEG C of each state point, wherein the value of n is the corresponding pipeline mark number, and taking the state point on the pipeline.
(2) Establishment of external circulation mathematical model for oxygen-enriched combustion and carbon capture
Setting heat loss q of exhaust smoke 2 Chemical incomplete combustion heat loss q 3 Heat loss due to incomplete combustion of machine q 4 Loss of heat dissipation q 5 Physical heat loss of ash q 6 ，
Preferably, heat loss q of exhaust fume 2 Comprises the following steps:
in the formula: h is py Is the enthalpy of boiler exhaust smoke, kJ/kg; h is r Is the boiler inlet enthalpy, kJ/kg; q r For the boiler to input heat, the coal-fired boiler of the invention does not utilize external heat source to preheat coal and air, and the moisture M in the coal is ar ＜Q net,ar /630, so that the boiler input heat is equal to the base lower heating value received by the coal, i.e. Q r ＝Q net,ar ，kJ/kg。
Heat loss due to incomplete combustion of chemical species q 3 Comprises the following steps: solid slag discharging furnace q 3 ＝0。
Heat loss due to incomplete combustion of machinery q 4 Comprises the following steps: according to the power plant boiler q 4 According to the invention, q is selected 4 =1.1. The setting of the value can be modified according to the boiler parameters designed by the manufacturer, so that the method is suitable for the change of the system.
Heat loss q 5 Comprises the following steps: in the invention, q is selected 5 And =0.2. The value can be set according to the parameters of the compressor designed by the manufacturer, so that the method is suitable for the change of the system.
Physical heat loss q of ash 6 Comprises the following steps: for the solid state slagging pulverized coal furnace, only the ash content is
Are only considered when needed. For the purposes of the present invention, q 6 ＝0。
Calculating boiler efficiency eta by adopting counter-balance method b ：
η b ＝100-(q 2 +q 3 +q 4 +q 5 +q 6 ) (16)
The coal burning quantity M is as follows:
Q c is sCO 2 Heat absorbed in the boiler;
sCO 2 efficiency of circulation eta sCO2 Comprises the following steps:
in the formula: w is a group of asu Power consumption of the air separation equipment; w cpu Is CO 2 Compression and purification equipment power consumption; w eq For the sum of the power consumption of other main units in the system (including the power consumption W of the trip device) src Electrostatic dust collector power consumption W esp And power consumption W of the desulfurization apparatus fgd )；W ap The auxiliary power consumption is removed from the main equipment;
electrical efficiency of η e Comprises the following steps:
(3) Obtaining a boiler inlet O by using the simulation model obtained in the step (1) and the step (2) 2 The influence of concentration and exhaust gas temperature on boiler efficiency and electric efficiency is realized by programming the mathematical model by python language and changing the boiler inlet O 2 The combustion degree of the boiler can be changed by the concentration parameter, and different O can be calculated by a mathematical model 2 The effect of concentration on boiler efficiency; the parameters for the flue gas temperature can also be modified in the program, the higher the flue gas temperature, which means the more heat loss of the boiler, the sCO 2 CO with less heat and energy absorbed by working medium 2 The thrust to the turbine is small, thus affecting the electric efficiency;
for the whole sCO 2 In the power cycle system, the two most important components are a turbine and a compressor, and the efficiency of the two components can greatly affect the cycle efficiency of the whole unit. For turbomachinery, turbine inlet temperature and pressure are factors that affect its efficiency, and different inlet temperatures and pressures cause changes in turbine efficiency that can be calculated by modifying the turbine inlet temperature and pressure during the programThe efficiency of the turbine is obtained, so that a designer can find a proper turbine model; for the main compressor, the same as the turbine part, the inlet temperature and pressure of the main compressor are calculated through designed parameters, the inlet temperature and pressure can be changed according to actual equipment parameters, the efficiency of the part is calculated through a program, and meanwhile, the cycle efficiency and the electric efficiency of the whole system are calculated. Therefore, designers can conveniently judge whether the selected component model parameters are matched with the whole circulation system, the selected component combination can enable the efficiency of the system to reach the maximum value, and the basis of optimization reference is provided for the old power generation circulation system.
Preferably, the model operation method in step (3) comprises the following steps:
for a brayton cycle:
1) Reading in system design parameters including the flow dividing ratio x and the total mass flow of the working medium
The turbine inlet temperature, the main compressor inlet temperature, the high-temperature heat regenerator efficiency, the low-temperature heat regenerator efficiency, the turbine isentropic efficiency, the main compressor isentropic efficiency and the recompressor isentropic efficiency, and the parameter values are shown in table 1;
2) First, the sCO is solved 2 Recompression power cycle turbine work W t Power consumption W of main compressor mc And then the power consumption W of the compressor is calculated rc Heat absorption capacity Q of working medium c (ii) a Known as T 1 、T 5 And the pressure at the pipeline marked 1-10 points, for the unknown quantity T 3 Making assumptions, setting an initial value, the initial value being at T 2 And T 6 Then using the assumed temperature T 3 And other known quantities, the low-pressure gas outlet temperature T of the low-temperature regenerator is solved according to the efficiency of the low-temperature regenerator 4 And outlet CO 2 Enthalpy value h 4 ；
3) Calculating the high-pressure side gas outlet temperature T by using the energy conservation in the low-temperature heat regenerator 7 And outlet CO 2 Enthalpy value h 7 ；
4) According to the isentropic efficiency eta of the recompressor rc The calculation formula of the recompression machine is solved to obtain the outlet of the recompression machineTemperature T of supercritical carbon dioxide 8 And CO 2 Enthalpy value h 8 ；
5) Mixing carbon dioxide in the recompressor and carbon dioxide fluid on the high-pressure side of the low-temperature heat regenerator at a point b, and calculating the temperature T of the high-pressure side entering the high-temperature heat regenerator according to the energy conservation principle of mixing 9 And CO 2 Enthalpy value h 9 Calculating the efficiency epsilon of the high-temperature heat regenerator by the enthalpy value of the high-temperature heat regenerator calculated in the previous step htr_j ；
6) The actual high temperature regenerator efficiency epsilon htr And the calculated efficiency epsilon of the high-temperature heat regenerator htr_j Making a comparison if ∈ htr > ε htr_j Decreasing the temperature T assumed in step 2) 3 Recalculating; if epsilon htr <ε htr_j Increasing the temperature T assumed in step 2) 3 Recalculating; up to epsilon htr -ε htr_j The value of | is less than the set error value, and the temperature T is stopped 3 Selecting the current value to carry out subsequent calculation;
7) The temperature T of the fluid flowing out of the high-temperature regenerator from the high-pressure side is calculated according to the law of conservation of energy of the high-temperature regenerator 10 And h 10 ；
8) Thus, the enthalpy values of 1-10 points are calculated, and sCO is calculated 2 Recompression power cycle turbine work W t Power consumption W of main compressor mc And the power consumption W of the recompressor rc Heat absorption capacity Q of working medium c ；
For the external circulation, the main calculation is the power consumption W of the release device src Electrostatic dust collector power consumption W esp And the power consumption W of the desulfurizer fgd Power consumption W of air separation plant asu 、CO 2 Power consumption W of compression and purification equipment cpu And power consumption W of service power except for main equipment ap ；
9) Calculating theoretical oxygen amount, calculating actual oxygen amount according to the excess oxygen coefficient alpha calculated by the gas analyzer, and calculating the amount of circulating flue gas;
10 Calculating the volume of components in the flue gas according to a flue gas component table under oxygen-enriched combustion;
11 The volume, the inlet enthalpy and the flue gas enthalpy of the flue gas are calculated according to a branch-of-law of Dalton partial pressure unified by disciplines by the amount of the circulating flue gas and the volume of components in the flue gas;
12 Calculate the heat loss q of the exhaust gas according to equation (15) 2 ；
13 Calculating the boiler efficiency eta according to the formula (16) b ；
14 Calculating the coal-fired quantity M according to the formula (17);
15 The smoke gas amount of the whole external circulation one-time smoke gas amount obtained by calculating the sum of the smoke gas amount generated by the combustion coal amount M and the circulating smoke gas amount by utilizing the component table of the smoke gas under the oxygen-enriched combustion;
16 Calculated is the power consumption W of the knock-out mechanism src Electrostatic dust collector power consumption W esp Power consumption W of desulfurizing device fgd Power consumption W of air separation plant asu 、CO 2 Power consumption W of compression and purification equipment cpu And the consumption W of service power except the main equipment ap ；
17 Calculate sCO according to equation (18) 2 Efficiency of circulation
The electrical efficiency is calculated according to equation (19) for designer reference.
Compared with the proposed supercritical carbon dioxide Brayton power cycle power generation system with carbon dioxide capture, the invention adopts the supercritical carbon dioxide recompression Brayton power cycle which can reduce the irreversible loss caused by heat exchange, reduces the energy loss compared with the Brayton cycle and has higher efficiency. Meanwhile, the invention also adopts oxygen-enriched combustion, so that the coal material is more fully combusted, more heat is provided, and the efficiency of the overall supercritical carbon dioxide recompression Brayton power cycle is improved. The invention provides a new cycle mode and a mathematical model of the cycle mode at the same time for checking and optimizing the cycle model.
The invention has the beneficial effects that:
1. the system design of the present invention employs advanced supercritical CO 2 The recompression Brayton power cycle has the advantages of high speed response, high density energy flow and the like, and the recompression cycle can avoid the problem of unbalanced heat capacity of fluid on the cold side and the hot side.
2. The invention adopts oxygen-enriched combustion to provide heat for power circulation, the combustion is more sufficient, and the overall efficiency of the power circulation is higher than that of the power circulation using a common boiler.
3. The invention simultaneously integrates the carbon capture system, and produces high-purity CO while realizing low carbon emission reduction 2 Can be used as a derivative product for chemical industry, and improves the overall economic performance of power cycle.
4. The invention designs the supercritical CO aiming at the coal eutrophication combustion by utilizing a python program 2 And a recompression Brayton cycle coupled carbon capture system performance analysis module can provide reference for the integration optimization of the system.
5. The boiler module in the programming of the invention can be used for setting the boiler inlet O 2 The influence of the boiler efficiency and the electric efficiency is obtained through the concentration and the exhaust gas temperature, and reference is provided for the design of the boiler in a power system.
6. The turbine module in the programming of the invention can calculate the cycle efficiency and the electric efficiency of the whole cycle according to the set turbine inlet temperature and the set inlet pressure, and provides a reference basis for the selection of turbine parts in the power cycle.
7. The compressor module in the programming of the invention can obtain the corresponding cycle efficiency and electric efficiency according to the set inlet temperature and inlet pressure of the main compressor, and provides reference basis for the selection of the compressor part model in the power cycle.
8. The modular design of the program is helpful for adding or changing different system components to adapt to the change of the circulation system.
Drawings
FIG. 1 is a flow diagram of the system;
FIG. 2 is a logic diagram for a system model solution.
Detailed Description
The present invention will be further described by way of examples, but not limited thereto, with reference to the accompanying drawings.
Example 1:
sCO under oxygen-enriched combustion of coal 2 A recompression Brayton cycle coupled carbon capture novel combined system, which comprises sCO 2 And then compressing the Brayton cycle and the external cycle of oxygen-enriched combustion and carbon capture.
The external circulation comprises an air separation plant, a combustion chamber, a denitration device, an electrostatic dust collector, a desulfurization device and CO according to the flowing direction of gas 2 The outlet end of the electrostatic dust collector is connected to the inlet end of the combustion chamber through a shunt pipeline to serve as circulating flue gas, and an external circulating machine is arranged on the shunt pipeline; air intake air separation plant manufacturing O 2 (11-12), mixing with the circulating flue gas in proportion, entering a combustion chamber to perform oxygen-enriched combustion with coal (13-14), and enriching CO 2 The flue gas passes through a denitration device (14-15) and an electrostatic dust collector (15-16) in sequence and then is divided at a position d, one part of the flue gas is returned to a combustion chamber as circulating flue gas to adjust the flame temperature of the boiler, and the other part of the flue gas enters a desulfurization device for desulfurization (19-20) and then enters CO 2 Compression and purification unit (20-21) to form CO 2 The product is used for storage or transportation; as shown in FIG. 1;
sCO 2 the recompression Brayton cycle comprises a turbine, a heat regenerator, a precooler and a compressor in the flow direction, wherein the heat regenerator comprises a high-temperature heat regenerator and a low-temperature heat regenerator, the compressor comprises a main compressor and a recompressor, and a working medium flows through a combustion chamber to absorb heat (13-14) to form high-temperature high-pressure sCO 2 Fluid, sCO 2 After entering a turbine expansion acting part (1-2), the heat-absorbing material sequentially enters a high-temperature heat regenerator (2-3) and a low-temperature heat regenerator (3-4) for isobaric heat release, then is divided into two streams at a position a according to a split ratio, one stream enters a main compressor for adiabatic compression (5-6) through a precooler (a-5), then enters a low-temperature heat regenerator for heat absorption (6-7), the other stream directly enters a recompressor for adiabatic compression (a-8), the two streams are converged and mixed at a junction point b, then enter the high-temperature heat regenerator for heat absorption (9-10), and finally returns to a combustion chamber to recover to a high-temperature and high-pressure state, so that the whole cycle is completed.
And setting the flow dividing point at the outlet of the low-temperature heat regenerator as a point a, the confluence point at the outlet of the recompressor as a point b, the confluence point of the circulating flue gas and the oxygen as a point c, and the flow dividing point at the outlet section of the electrostatic dust collector as a point d. The pipeline between the combustion chamber and the turbine is numbered 1, the pipeline between the turbine and the high-temperature regenerator is numbered 2, the pipeline between the high-temperature regenerator and the low-temperature regenerator is numbered 3, the pipeline between the low-temperature regenerator and the point a is numbered 4, the pipeline between the precooler and the main compressor is numbered 5, the pipeline between the main compressor and the low-temperature regenerator is numbered 6, the pipeline between the low-temperature regenerator and the point b is numbered 7, the pipeline between the recompressor and the point b is numbered 8, the pipeline between the point b and the high-temperature regenerator is numbered 9, the pipeline between the high-temperature regenerator and the combustion chamber is numbered 10, the inlet pipeline of the air separation equipment is numbered 11, the pipeline between the air separation equipment and the point c is numbered 12, the pipeline between the point c and the combustion chamber is numbered 13, the pipeline between the combustion chamber and the denitration device is numbered 14, the pipeline between the denitration device and the electrostatic precipitator is numbered 15, the pipeline between the electrostatic precipitator and the electrostatic precipitator is numbered 16, the pipeline between the point d and the external circulation machine is numbered 17, the pipeline between the external circulation machine and the point c is numbered 18, the pipeline between the point d and the desulfurization device is numbered 19, the pipeline between the desulfurization device and the CO are numbered 19 2 The line between the compression and purification units is numbered 20 2 The compression and purification unit outlet line is numbered 21.
Example 2:
sCO Using the coal oxycombustion described in example 1 2 According to the simulation method of the recompression Brayton cycle coupling carbon capture novel combined system, the following coupling cycle system mathematical model is established for each part of the system according to energy conservation and mass conservation:
(1) Supercritical CO 2 Recompression Brayton power cycle mathematical model building
The turbine work process (1-2) can be approximately regarded as an adiabatic expansion process, the turbine work W t And isentropic efficiency η t Comprises the following steps:
in the formula:
the total mass flow of the working medium is kg/s;
the heat regenerator is a counterflow heat regenerator and uses a pressure loss coefficient C p And the performance epsilon based on the enthalpy difference represents the performance of the heat regenerator, and the performance epsilon is defined as the ratio of the actual heat exchange quantity to the theoretical maximum heat exchange quantity;
the high-temperature regenerator (2-3) is regarded as an isobaric heat exchange process, and the efficiency epsilon of the high-temperature regenerator htr Comprises the following steps:
the low-temperature regenerator (3-4) is regarded as an isobaric heat exchange process, and the efficiency epsilon of the low-temperature regenerator ltr Comprises the following steps:
or
Wherein if the specific heat capacity of the high pressure fluid exiting the main compressor is greater than the specific heat capacity of the low pressure fluid exiting the high temperature regenerator, then ε ltr Adopting a formula (4); otherwise, adopting formula (5); because carbon dioxide is used as a circulating working medium, the specific heat capacity difference of cold and hot fluids flowing through the low-temperature heat regenerator is large, so the low-temperature heat regenerator in the program design of the invention has the efficiency epsilon ltr The formula (4) is adopted for calculation, but if the program is changed into water vapor as the working medium, the program design calculation formula of the invention is changed into the formula (5) for calculation;
according to the energy conservation, the heat exchange quantity of the cold fluid and the hot fluid in the heat regenerator reaches heat balance;
heat balance of the high-temperature heat regenerator:
h 2 -h 3 ＝h 10 -h 9 (25)
and (3) thermal balance of the low-temperature heat regenerator:
h 3 -h 4 ＝x·(h 7 -h 6 ) (26)
in the formula: x is a flow dividing ratio which is defined as the ratio of the mass flow of the working medium entering the main compressor to the total mass flow of the circulating working medium, preferably, the value of the flow dividing ratio can be selected according to different working conditions, in order to ensure the efficiency of the system circulation, the value range of the program design is between 0.65 and 0.8, and further preferably, the value selected by the flow dividing ratio in the invention is 0.721;
precooler (a-5) sees isobaric heat release, process heat change Q pc Comprises the following steps:
the main compressor (5-6) is regarded as an adiabatic compression process, the main compressor power consumption W mc And isentropic efficiency η mc Comprises the following steps:
the recompressor (a-8) is regarded as an adiabatic compression process and the work consumption W of the recompressor rc And isentropic efficiency η rc Comprises the following steps:
the junction b is obtained according to energy conservation:
h 9 ＝x·h 7 +(1-x)h 8 (32)
the combustion chamber (10-1) is regarded as an isobaric heat absorption process, and the heat absorption capacity Q of the working medium c Comprises the following steps:
in the above formula: h is a total of n Is sCO 2 Enthalpy at each state point of the cycle, kJ/kg; h is ns Is sCO 2 Ideal enthalpy at each state point of the cycle, kJ/kg; t is n Is sCO 2 And (3) circulating the temperature and the DEG C of each state point, wherein the value of n is the corresponding pipeline mark, and taking the state point on the pipeline.
(2) Establishment of external circulation mathematical model for oxygen-enriched combustion and carbon capture
Setting heat loss q of exhaust smoke 2 Chemical incomplete combustion heat loss q 3 Heat loss due to incomplete combustion of machinery q 4 Loss of heat dissipation q 5 Physical heat loss of ash q 6 ，
Heat loss q of exhaust 2 Comprises the following steps:
in the formula: h is a total of py Is the enthalpy of boiler exhaust smoke, kJ/kg; h is r Is the boiler inlet enthalpy, kJ/kg; q r For inputting heat to the boiler, the coal-fired boiler of the invention has the advantages that the coal and the air are not preheated by using an external heat source, and the moisture M in the coal is ar ＜Q net,ar /630, so that the boiler input heat is equal to the base lower heating value received by the coal, i.e. Q r ＝Q net,ar ，kJ/kg。
Heat loss due to incomplete combustion of chemical species q 3 Comprises the following steps: solid slag discharging furnace q 3 ＝0。
Heat of incomplete combustion of machineryLoss q 4 Comprises the following steps: according to the boiler q of the power plant 4 According to the invention, q is selected 4 =1.1. The setting of the value can be modified according to the boiler parameters designed by the manufacturer, so that the method is suitable for the change of the system.
Heat loss q 5 Comprises the following steps: in the invention, q is selected 5 =0.2. The value can be set according to the parameters of the compressor designed by the manufacturer, so that the method is suitable for the change of the system.
Physical heat loss q of ash 6 Comprises the following steps: for the solid state slagging pulverized coal furnace, only the ash content is
Are only considered when needed. For the purposes of the present invention, q 6 ＝0。
Calculating boiler efficiency eta by adopting a reverse balance method b ：
η b ＝100-(q 2 +q 3 +q 4 +q 5 +q 6 ) (35)
The coal burning quantity M is as follows:
Q c is sCO 2 Heat absorbed in the boiler;
sCO 2 efficiency of circulation eta sCO2 Comprises the following steps:
in the formula: w asu Power consumption of the air separation equipment; w is a group of cpu Is CO 2 Compression and purification equipment power consumption; w eq For the sum of the power consumption of other main units in the system (including the power consumption W of the trip device) src Electrostatic dust collector power consumption W esp And the power consumption W of the desulfurization apparatus fgd )；W pa The auxiliary power consumption except the main equipment is removed;
electrical efficiency of η e Comprises the following steps:
(3) Obtaining the boiler inlet O by using the simulation model obtained in the step (1) and the step (2) 2 The influence of concentration and exhaust gas temperature on boiler efficiency and electric efficiency is realized by programming the mathematical model by python language and changing the boiler inlet O 2 The combustion degree of the boiler can be changed by the concentration parameter, and different O can be calculated by a mathematical model 2 The effect of concentration on boiler efficiency; the parameters for the flue gas temperature can also be modified in the program, the higher the flue gas temperature, which means the more heat loss of the boiler, the sCO 2 CO with less heat and energy absorbed by working medium 2 The thrust to the turbine is small, thus affecting the electrical efficiency;
for the whole sCO 2 In the power cycle system, the most important two parts are a turbine and a compressor, and the efficiency of the two parts can greatly influence the cycle efficiency of the whole unit. For a turbomachine, the temperature and the pressure of a turbine inlet are factors influencing the efficiency of the turbomachine, the efficiency of the turbine can be changed due to different inlet temperatures and pressures, and the efficiency of the turbine can be calculated by changing the temperature and the pressure of the turbine inlet in a program, so that a designer can find a proper turbine model; for the main compressor, the same as the turbine part, the inlet temperature and pressure of the main compressor are calculated through designed parameters, the inlet temperature and pressure can be changed according to actual equipment parameters, the efficiency of the part is calculated through a program, and meanwhile, the cycle efficiency and the electric efficiency of the whole system are calculated. Therefore, designers can conveniently judge whether the selected component model parameters are matched with the whole circulation system, the selected component combination can enable the efficiency of the system to reach the maximum value, and the basis of optimization reference is provided for the old power generation circulation system.
The model operation method in the step (3) comprises the following steps:
for the brayton cycle:
1) Reading in system design parameters including the flow dividing ratio x and the total mass flow of the working medium
Turbine inlet temperature, main compressor inlet temperature, high temperature heat regenerator efficiency, low temperature heat regenerator efficiency, turbine isentropic efficiency, main compressor isentropic efficiency, recompressor isentropic efficiency, and the parameter values are shown in table 1;
2) First, the sCO is solved 2 Recompression power cycle turbine work W t Power consumption W of main compressor mc And the power consumption W of the recompressor rc Heat absorption capacity Q of working medium c (ii) a Known as T 1 、T 5 And the pressure at the 1-10 point of the pipeline index, to the unknown quantity T 3 Making assumptions, setting an initial value, the initial value being at T 2 And T 6 Then using the assumed temperature T 3 And other known quantities, the low-pressure gas outlet temperature T of the low-temperature regenerator is solved according to the efficiency of the low-temperature regenerator 4 And outlet CO 2 Enthalpy value h 4 ；
3) Calculating the high-pressure side gas outlet temperature T by using the energy conservation in the low-temperature heat regenerator 7 And outlet CO 2 Enthalpy value h 7 ；
4) According to the isentropic efficiency eta of the recompressor rc The temperature T of the supercritical carbon dioxide at the outlet of the recompression machine is obtained through solving the calculation formula 8 And CO 2 Enthalpy value h 8 ；
5) Mixing carbon dioxide in the recompressor and carbon dioxide fluid on the high-pressure side of the low-temperature heat regenerator at a point b, and calculating the temperature T of the high-pressure side entering the high-temperature heat regenerator according to the energy conservation principle of mixing 9 And CO 2 Enthalpy value h 9 Calculating the efficiency epsilon of the high-temperature heat regenerator by the previously calculated enthalpy value of the high-temperature heat regenerator htr_j ；
6) The actual high temperature regenerator efficiency epsilon htr And the calculated efficiency epsilon of the high-temperature heat regenerator htr_j Making a comparison if ε htr > ε htr_j Decreasing the temperature T assumed in step 2) 3 Recalculating; if epsilon htr <ε htr_j Increasing the temperature T assumed in step 2) 3 Recalculating; up to epsilon htr -ε htr _ j The value of | is less than the set error value, and the temperature T is stopped 3 Selecting the current value to carry out subsequent calculation;
7) The temperature T of the fluid flowing out of the high-temperature regenerator from the high-pressure side is calculated according to the law of conservation of energy of the high-temperature regenerator 10 And h 10 ；
8) Thus, the enthalpy values of 1-10 points are calculated, and sCO is calculated 2 Recompression power cycle turbine work W t Power consumption W of main compressor mc And the power consumption W of the recompressor rc Heat absorption capacity Q of working medium c ；
For the external circulation, the power consumption W of the lock-out device is mainly calculated src Electrostatic dust collector power consumption W esp Power consumption W of desulfurizing device fgd Power consumption W of air separation plant asu 、CO 2 Power consumption W of compression and purification equipment cpu And the consumption W of service power except the main equipment ap ；
9) Calculating theoretical oxygen amount, calculating actual oxygen amount according to the excess oxygen coefficient alpha calculated by the gas analyzer, and calculating the amount of circulating flue gas;
10 Calculating the volume of components in the flue gas according to a flue gas component table under oxygen-enriched combustion;
11 The volume, the inlet enthalpy and the smoke enthalpy are calculated according to a branch law of Dalton pressure which is unified by disciplines according to the volume of the circulating smoke and the volume of components in the smoke;
12 Calculate the heat loss q of the exhaust gas according to equation (15) 2 ；
13 Calculating the boiler efficiency eta according to the formula (16) b ；
14 Calculating the amount of coal fired M according to the formula (17);
15 Using a component table of the flue gas under the oxygen-enriched combustion to calculate the sum of the flue gas generated by the combustion coal quantity M and the circulating flue gas quantity to obtain the flue gas quantity of the whole external circulation once;
16 Calculated is the power consumption W of the knock-out mechanism src Electrostatic dust collector power consumption W esp Power consumption W of desulfurizing device fgd Power consumption W of air separation plant asu 、CO 2 Power consumption W of compression and purification equipment cpu And power consumption W of service power except for main equipment ap ；
17 Calculates sCO according to equation (18) 2 Efficiency of circulation
The electrical efficiency is calculated according to equation (19) for designer reference.
Experimental example 3:
python programming and arithmetic verification calculations.
The system is modularly programmed by adopting Python, the programming adopts a modularized programming idea, a large program is divided into a plurality of small program modules according to the functions of components, necessary relation is established among the modules, and the whole program design is completed through mutual cooperation of the modules.
Solving logic As shown in FIG. 2, the design parameters of the system are input, and the unknown quantity T is first calculated 3 Supposing that the efficiency of the high-temperature heat regenerator is set according to the set value of the invention under the premise of ensuring that the obtained temperatures conform to the temperature cycle logic, so as to obtain the error of the efficiency of the high-temperature heat regenerator less than 10 -8 As a judgment standard to T 3 Iterations are performed and then the parameters throughout the loop system are solved. Meanwhile, the boiler efficiency is solved by calculating the heat loss, the coal burning quantity, the power consumption of each external circulation device and the like are further solved, and the circulation efficiency and the electric efficiency of the two parts of solving systems are integrated.
The equipment parameters and experimental data of the American Sandia laboratory are adopted as the verification of the accuracy of the program design, and because the data of the Sandia laboratory does not give the turbine isentropic efficiency and the main/recompressor isentropic efficiency, the data are properly assumed. Meanwhile, since the pressure loss of all pipes and components is assumed to be ignored when constructing the mathematical model, the pressure at the state point 7 should not be taken as laboratory pressure data, but should be kept consistent with the pressure at the state point 6, and the specific parameter settings are shown in table 1 and table 2. Because the experiments and the simulation of the quasi-critical zone are less at present, and the verification data of the adopted Sandia laboratory does not relate to the quasi-critical zone, the verification and the subsequent simulation are mainly carried out on the normal supercritical working condition.
The simulation data of table 1 was entered and the mathematical model was simulated, and the comparison of the simulation results with the Sandia laboratory data is shown in table 2. In table 2, the difference between the laboratory temperature data and the simulation output temperature is 1.24 ℃ at most, and the maximum error is 0.80% <1.00%, so that the program designed by the invention is accurate and feasible for the result of the power cycle calculation.
TABLE 1 setting of cycling parameters for the Sandia laboratory
TABLE 2 Sandia laboratory data vs. simulation data
Claims (8)
1. Supercritical CO under oxygen-enriched combustion of coal 2 The recompression Brayton cycle coupled carbon capture novel combined system is characterized by comprising sCO 2 Then compressing Brayton cycle and oxygen-enriched combustion and carbon capture external cycle;
the external circulation comprises an air separation plant, a combustion chamber, a denitration device, an electrostatic dust collector, a desulfurization device and CO according to the flowing direction of gas 2 The outlet end of the electrostatic dust collector is connected to the inlet end of the combustion chamber through a shunt pipeline to serve as circulating flue gas, and an external circulating machine is arranged on the shunt pipeline; air intake air separation plant manufacturing O 2 Mixing with circulating flue gas in proportion, and introducing into combustion chamber for oxygen-enriched combustion with coal to obtain CO-enriched fuel 2 The flue gas is divided after passing through the denitration device and the electrostatic dust collector in sequence, one part of the flue gas is returned to the combustion chamber as circulating flue gas to adjust the flame temperature of the boiler, and the other part of the flue gas enters the desulphurization device to be desulfurized and then enters CO 2 Compression and purification unit to form CO 2 Producing a product;
sCO 2 the recompression Brayton cycle includes in the flow direction a turbine, a regenerator, a precooler, and a compressor,the heat regenerator comprises a high-temperature heat regenerator and a low-temperature heat regenerator, the compressor comprises a main compressor and a secondary compressor, and the working medium flows through the combustion chamber to absorb heat to form high-temperature high-pressure sCO 2 Fluid, sCO 2 After entering a turbine expansion working, the mixed gas enters a high-temperature heat regenerator and a low-temperature heat regenerator in sequence to release heat at equal pressure, then is divided into two streams according to a flow dividing ratio, one stream enters a main compressor through a precooler to be compressed in an adiabatic way, then enters the low-temperature heat regenerator to absorb heat, the other stream directly enters a recompressor to be compressed in an adiabatic way, the two streams are converged and mixed, then enter the high-temperature heat regenerator to absorb heat, and finally return to a combustion chamber to recover to a high-temperature and high-pressure state.
2. The supercritical CO under oxygen-enriched combustion of coal as claimed in claim 1 2 The recompression Brayton cycle coupling carbon capture novel combined system is characterized in that the flow dividing point at the outlet of the low-temperature heat regenerator is a point a, the confluence position of the outlet of the recompressor is a point b, the confluence position of the circulating flue gas and the oxygen is a point c, and the flow dividing position of the outlet section of the electrostatic dust collector is a point d.
3. The supercritical CO under oxygen-enriched combustion of coal as claimed in claim 2 2 The recompression Brayton cycle coupled carbon capture novel combined system is characterized in that the pipeline between a combustion chamber and a turbine is 1, the pipeline between the turbine and a high-temperature heat regenerator is 2, the pipeline between the high-temperature heat regenerator and a low-temperature heat regenerator is 3, the pipeline between the low-temperature heat regenerator and a point a is 4, the pipeline between a precooler and a main compressor is 5, the pipeline between the main compressor and the low-temperature heat regenerator is 6, the pipeline between the low-temperature heat regenerator and a point b is 7, the pipeline between a recompressor and a point b is 8, the pipeline between a point b and the high-temperature heat regenerator is 9, the pipeline between the high-temperature heat regenerator and the combustion chamber is 10, the inlet pipeline of an air separation device is 11, the pipeline between the air separation device and the point c is 12, the pipeline between the point c and the combustion chamber is 13, the pipeline between the combustion chamber and a denitration device is 14, the pipeline between the denitration device and the dust remover is 15, the pipeline between the dust remover and the electrostatic precipitator is 16, the pipeline between the point d and the external circulation machine is 17, the pipeline between the external circulation machine and the point c, the electrostatic precipitator and the point are 18, the pipeline between the point d and the point d, the point d and the point d point are 18Line number 19 between the desulphurisation units, desulphurisation unit and CO 2 The line between the compression and purification units is numbered 20 2 The compression and purification unit outlet line is numbered 21.
4. Supercritical CO combustion under oxygen-enriched combustion of coal according to claim 3 2 The simulation method of the recompression Brayton cycle coupling carbon capture novel combined system is characterized in that the following mathematical models of the coupling cycle system are established for each part of the system according to energy conservation and mass conservation:
(1) Supercritical CO 2 Recompression Brayton power cycle mathematical model establishment
The work-doing process of the turbine is regarded as an adiabatic expansion process, the work W of the turbine t And isentropic efficiency eta t Comprises the following steps:
in the formula:
the total mass flow of the working medium is kg/s;
the heat regenerator is a counterflow heat regenerator and uses a pressure loss coefficient C p And the performance epsilon based on the enthalpy difference represents the performance of the heat regenerator, and the performance epsilon is defined as the ratio of the actual heat exchange quantity to the theoretical maximum heat exchange quantity;
the high-temperature regenerator is regarded as an isobaric heat exchange process, and the efficiency of the high-temperature regenerator is epsilon htr Comprises the following steps:
the low-temperature regenerator is regarded as an isobaric heat exchange process, and the efficiency epsilon of the low-temperature regenerator ltr Comprises the following steps:
or
Wherein if the specific heat capacity of the high pressure fluid exiting the main compressor is greater than the specific heat capacity of the low pressure fluid exiting the high temperature regenerator, then ε ltr Adopting a formula (4); otherwise, adopting formula (5);
according to the energy conservation, the heat exchange quantity of the cold fluid and the hot fluid in the heat regenerator reaches heat balance;
heat balance of the high-temperature heat regenerator:
h 2 -h 3 ＝h 10 -h 9 (6)
and (3) thermal balance of the low-temperature heat regenerator:
h 3 -h 4 ＝x·(h 7 -h 6 ) (7)
in the formula: x is a split ratio which is defined as the ratio of the mass flow of the working medium entering the main compressor to the total mass flow of the circulating working medium;
precooler considered isobaric heat release, process heat change Q pc Comprises the following steps:
the main compressor is regarded as an adiabatic compression process, and the power consumption W of the main compressor mc And isentropic efficiency eta mc Comprises the following steps:
the recompressor is regarded as an adiabatic compression process and the work consumption W of the recompressor rc And isentropic efficiency η rc Comprises the following steps:
the convergence point b is obtained according to energy conservation:
h 9 ＝x·h 7 +(1-x)h 8 (13)
the heat absorption capacity Q of the working medium is regarded as the isobaric heat absorption process in the combustion chamber c Comprises the following steps:
in the above formula: h is a total of n Is sCO 2 Enthalpy at each state point of the cycle, kJ/kg; h is ns Is sCO 2 Ideal enthalpy at each state point of the cycle, kJ/kg; t is a unit of n Is sCO 2 Circulating the temperature and the DEG C of each state point, wherein the value of n is the corresponding pipeline mark number, and taking the state point on the pipeline;
(2) Establishment of external circulation mathematical model for oxygen-enriched combustion and carbon capture
Setting heat loss q of exhaust smoke 2 Chemical incomplete combustion heat loss q 3 Heat loss due to incomplete combustion of machinery q 4 Loss of heat dissipation q 5 Physical heat loss of ash q 6 ，
Heat loss q of exhaust 2 Comprises the following steps:
in the formula: h is py Is the enthalpy of boiler exhaust smoke, kJ/kg; h is r Is the boiler inlet enthalpy, kJ/kg; q r For inputting heat to the boiler, the coal-fired boiler of the invention has the advantages that the coal and the air are not preheated by using an external heat source, and the moisture M in the coal is ar ＜Q net,ar /630, so that the boiler input heat is equal to the base lower heating value received from the coal, i.e. Q r ＝Q net,ar ，kJ/kg；；
Calculating boiler efficiency eta by adopting counter-balance method b ：
η b ＝100-(q 2 +q 3 +q 4 +q 5 +q 6 ) (16)
The coal burning quantity M is as follows:
Q c is sCO 2 Heat absorbed in the boiler;
sCO 2 efficiency of circulation
Comprises the following steps:
in the formula: w asu Power consumption of the air separation equipment; w cpu Is CO 2 Compression and purification equipment power consumption; w is a group of eq For the sum of the power consumptions of other main equipment in the system, including the power consumption W of the tripping device src Electrostatic dust collector power consumption W esp And power consumption W of the desulfurization apparatus fgd ；W ap The auxiliary power consumption except the main equipment is removed;
electrical efficiency of η e Comprises the following steps:
(3) Obtaining the boiler inlet O by using the simulation model obtained in the step (1) and the step (2) 2 The influence of concentration and exhaust gas temperature on boiler efficiency and electric efficiency is realized by programming the mathematical model by python language and changing the inlet O of the boiler 2 The combustion degree of the boiler can be changed by the concentration parameter, and different O can be calculated by a mathematical model 2 The effect of concentration on boiler efficiency; the parameters of the flue gas temperature can also be modified in the program, and the higher the flue gas temperature is, the more heat loss of the boiler is shown, and the sCO 2 CO with less heat and energy absorbed by working medium 2 The thrust to the turbine is small, thus affecting the electrical efficiency;
for turbomachinery, turbine inlet temperature and pressure are factors influencing efficiency of the turbomachinery, different inlet temperatures and pressures can cause change of turbine efficiency, the efficiency of a turbine can be calculated by changing the turbine inlet temperature and pressure in a program, the inlet temperature and pressure of a main compressor are also calculated by designed parameters, the change is carried out according to actual equipment parameters, the program calculates component efficiency, and meanwhile, the cycle efficiency and the electric efficiency of the whole system are calculated.
5. The supercritical CO under oxygen-enriched combustion of coal as claimed in claim 4 2 The simulation method of the recompression Brayton cycle coupled carbon capture novel combined system is characterized in that the model operation method in the step (3) comprises the following steps:
for the brayton cycle:
1) Reading in system design parameters including the split ratio x and the total mass flow of the working medium
Turbine inlet temperature, main compressor inlet temperature, high temperature heat regenerator efficiency, low temperature heat regenerator efficiency, turbine isentropic efficiency, main compressor isentropic efficiency, recompressor isentropic efficiency;
2) First, the sCO is solved 2 Recompression power cycle turbine work W t Main compressionMechanical power consumption W mc And then the power consumption W of the compressor is calculated rc Heat absorption capacity Q of working medium c (ii) a Known as T 1 、T 5 And the pressure at the pipeline marked 1-10 points, for the unknown quantity T 3 Making assumptions, setting an initial value, the initial value being at T 2 And T 6 Then using the assumed temperature T 3 And other known quantities, the low-pressure gas outlet temperature T of the low-temperature regenerator is solved according to the efficiency of the low-temperature regenerator 4 And outlet CO 2 Enthalpy value h 4 ；
3) Calculating the high-pressure side gas outlet temperature T by using the energy conservation in the low-temperature heat regenerator 7 And outlet CO 2 Enthalpy value h 7 ；
4) According to the isentropic efficiency eta of the recompressor rc The temperature T of the supercritical carbon dioxide at the outlet of the recompression machine is obtained by solving the calculation formula 8 And CO 2 Enthalpy value h 8 ；
5) Mixing carbon dioxide in the recompressor and carbon dioxide fluid on the high-pressure side of the low-temperature heat regenerator at a point b, and calculating the temperature T of the high-pressure side entering the high-temperature heat regenerator according to the energy conservation principle of mixing 9 And CO 2 Enthalpy value h 9 Calculating the efficiency epsilon of the high-temperature heat regenerator according to the enthalpy value of the high-temperature heat regenerator calculated in the previous step htr_j ；
6) The actual high temperature regenerator efficiency epsilon htr And the calculated efficiency epsilon of the high-temperature heat regenerator htr_j Making a comparison if ε htr >ε htr_j Decreasing the temperature T assumed in step 2) 3 Recalculating; if epsilon htr <ε htr_j Increasing the temperature T assumed in step 2) 3 Recalculating; up to epsilon htr -ε htr_j The value of | is less than the set error value, and the temperature T is stopped 3 The current value is selected to be brought into subsequent calculation;
7) The temperature T of the fluid flowing out of the high-temperature regenerator from the high-pressure side is calculated according to the law of conservation of energy of the high-temperature regenerator 10 And h 10 ；
8) Thus, the enthalpy values of 1-10 points are calculated, and sCO is calculated 2 Recompression power cycle turbine work W t Main compressor power consumption W mc And then the power consumption W of the compressor is calculated rc Heat absorption capacity Q of working medium c ；
For the external circulation, the main calculation is the power consumption W of the release device src Electrostatic dust collector power consumption W esp Power consumption W of desulfurizing device fgd Power consumption W of air separation plant asu 、CO 2 Power consumption W of compression and purification equipment cpu And power consumption W of service power except for main equipment ap ；
9) Calculating theoretical oxygen amount, calculating actual oxygen amount according to the excess oxygen coefficient alpha calculated by the gas analyzer, and calculating the amount of circulating flue gas;
10 Calculating the volume of components in the flue gas according to a flue gas component table under oxygen-enriched combustion;
11 Calculating the volume, the inlet enthalpy and the smoke enthalpy according to the Dalton partial pressure law by using the amount of the circulating smoke and the volume of components in the smoke;
12 Calculate the heat loss q of the exhaust gas according to equation (15) 2 ；
13 Calculating the boiler efficiency eta according to the formula (16) b ；
14 Calculating the amount of coal fired M according to the formula (17);
15 The smoke gas amount of the whole external circulation one-time smoke gas amount obtained by calculating the sum of the smoke gas amount generated by burning the coal amount M and the circulating smoke gas amount by utilizing the component table of the smoke gas under the oxygen-enriched combustion;
16 Calculated is the power consumption W of the knock-out mechanism src Electrostatic dust collector power consumption W esp Power consumption W of desulfurizing device fgd Power consumption W of air separation plant asu 、CO 2 Power consumption W of compression and purification equipment cpu And power consumption W of service power except for main equipment ap ；
17 Calculate sCO according to equation (18) 2 Efficiency of circulation
The electrical efficiency is calculated according to equation (19) for designer reference.
6. The supercritical CO under oxygen-enriched combustion of coal as claimed in claim 4 2 The simulation method of the recompression Brayton cycle coupled carbon capture novel combination system is characterized in that in the step (1), different shunt ratios are selected according to different working conditions according to the magnitude of the shunt ratio x, and the value range is between 0.65 and 0.8.
7. The supercritical CO under oxygen-enriched combustion of coal as claimed in claim 6 2 The simulation method of the recompression Brayton cycle coupled carbon capture novel combination system is characterized in that in the step (1), the value of the split-flow ratio x is 0.721.
8. The supercritical CO under oxygen-enriched combustion of coal as claimed in claim 4 2 The simulation method of the recompression Brayton cycle coupled carbon capture novel combined system is characterized in that in the step (2), the chemical incomplete combustion heat loss q is generated 3 Comprises the following steps: solid slag discharging furnace q 3 =0; heat loss due to incomplete combustion of machinery q 4 Comprises the following steps: q. q.s 4 =1.1; heat loss q 5 Comprises the following steps: q. q.s 5 =0.2; physical heat loss q of ash 6 Comprises the following steps: q. q of 6 ＝0。
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117076830A (en) * | 2023-10-13 | 2023-11-17 | 中国空气动力研究与发展中心计算空气动力研究所 | Method and device for determining power of nitrogen axial flow compressor, electronic equipment and medium |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108979768A (en) * | 2018-06-04 | 2018-12-11 | 东南大学 | The supercritical carbon dioxide joint organic Rankine cycle power generation system that the oxygen-enriched fluidized bed that pressurizes drives |
| CN109322744A (en) * | 2018-11-15 | 2019-02-12 | 中国华能集团清洁能源技术研究院有限公司 | A kind of the coal gasification supercritical carbon dioxide electricity generation system and method for waste heat recycling |
| CN109715916A (en) * | 2016-09-22 | 2019-05-03 | 气体技术学院 | Power circulation system and method |
| CN112267920A (en) * | 2020-09-14 | 2021-01-26 | 华北电力大学（保定） | Closed supercritical carbon dioxide power generation system and method with carbon capture and utilization and fuel gas circulating waste heat utilization |
| CN113294770A (en) * | 2021-04-28 | 2021-08-24 | 东南大学 | Oxygen-enriched combustion coupled supercritical CO2Cyclic cogeneration system |
| CN114738071A (en) * | 2022-03-17 | 2022-07-12 | 中国华能集团清洁能源技术研究院有限公司 | A two pressure circulation system for carbon is retrieved |
-
2022
- 2022-08-11 CN CN202210960825.2A patent/CN115288819B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109715916A (en) * | 2016-09-22 | 2019-05-03 | 气体技术学院 | Power circulation system and method |
| CN108979768A (en) * | 2018-06-04 | 2018-12-11 | 东南大学 | The supercritical carbon dioxide joint organic Rankine cycle power generation system that the oxygen-enriched fluidized bed that pressurizes drives |
| CN109322744A (en) * | 2018-11-15 | 2019-02-12 | 中国华能集团清洁能源技术研究院有限公司 | A kind of the coal gasification supercritical carbon dioxide electricity generation system and method for waste heat recycling |
| CN112267920A (en) * | 2020-09-14 | 2021-01-26 | 华北电力大学（保定） | Closed supercritical carbon dioxide power generation system and method with carbon capture and utilization and fuel gas circulating waste heat utilization |
| CN113294770A (en) * | 2021-04-28 | 2021-08-24 | 东南大学 | Oxygen-enriched combustion coupled supercritical CO2Cyclic cogeneration system |
| CN114738071A (en) * | 2022-03-17 | 2022-07-12 | 中国华能集团清洁能源技术研究院有限公司 | A two pressure circulation system for carbon is retrieved |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117076830A (en) * | 2023-10-13 | 2023-11-17 | 中国空气动力研究与发展中心计算空气动力研究所 | Method and device for determining power of nitrogen axial flow compressor, electronic equipment and medium |
| CN117076830B (en) * | 2023-10-13 | 2024-03-12 | 中国空气动力研究与发展中心计算空气动力研究所 | Method and device for determining power of nitrogen axial flow compressor, electronic equipment and medium |
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