CN113237075B - Design optimization and regulation and control method of flue gas waste heat recovery system - Google Patents

Design optimization and regulation and control method of flue gas waste heat recovery system Download PDF

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CN113237075B
CN113237075B CN202110486424.3A CN202110486424A CN113237075B CN 113237075 B CN113237075 B CN 113237075B CN 202110486424 A CN202110486424 A CN 202110486424A CN 113237075 B CN113237075 B CN 113237075B
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封又琳
刘明
杨凯旋
严俊杰
刘继平
邢秦安
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Xian Jiaotong University
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22DPREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
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    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
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    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
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Abstract

The invention discloses a design optimization and regulation method of a flue gas waste heat recovery system, which is characterized in that the total annual average load rate and the annual average minimum ambient temperature of a coal-fired unit for nearly 3 years are respectively used as the design reference load rate and the design reference ambient temperature of the system, and a multi-parameter optimization intelligent algorithm is matched, so that the optimal design configuration considering the variable working condition characteristics of the unit can be obtained, an operation regulation strategy for ensuring the operation safety and economy under the full working condition is provided, and the efficient and safe cooperative operation of the waste heat recovery system under the full working condition is realized. The waste heat recovery system obtained by the method has the advantages of high technical economy, strong adaptability and strong flexibility.

Description

Design optimization and regulation and control method of flue gas waste heat recovery system
Technical Field
The invention relates to the technical field of flue gas waste heat recovery, in particular to a design optimization and regulation method of a flue gas waste heat recovery system.
Background
In recent years, with the rapid development of new energy power generation in China, the coal-fired power generation has been transited from main energy to basic energy, which puts new requirements on the flexibility of the operation of a coal-fired power generating set. Coal fired power generation will be more tasked with peak shaving and will frequently run at variable loads for a long period of time. The boiler flue gas waste heat recovery technology is still an effective means for improving the efficiency of the coal-fired generator set and promoting energy conservation and emission reduction. The high-efficiency operation of the flue gas waste heat recovery system of the coal-fired generator set in the whole working condition range is realized, and the method has important significance for improving the overall efficiency of the coal-fired generator set.
However, the actual operation condition of the existing unit shows that: when the rated load rate and the normal temperature of the coal-fired unit are used as the design reference load rate and the design reference environment temperature of the flue gas waste heat recovery system, the performance of the optimal waste heat recovery system obtained through multi-parameter optimization during variable-working-condition operation is difficult to guarantee. However, most of the existing related researches are system optimization researches under rated design conditions, and comprehensive consideration on system safety and technical economy under variable working condition operation conditions is lacked. Therefore, on the basis of the study on the variable working condition characteristics of the waste heat recovery system of the coal-fired unit, the design of the waste heat recovery system of the coal-fired unit is developed so as to obtain a design configuration of the waste heat recovery system capable of realizing the high-efficiency and safe cooperative operation under the full working condition and a corresponding optimized operation strategy, and the method has important practical significance.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a design optimization and regulation method of a flue gas waste heat recovery system, which obtains an optimal waste heat recovery system design configuration considering the variable working condition characteristics of a unit and a corresponding operation regulation method by taking a system design reference load rate and a design reference environment temperature reflecting the variable working condition characteristics of the unit and combining a multi-parameter optimization intelligent algorithm. The method can obtain the optimal design configuration and the regulation and control method considering the variable working condition characteristics of the unit, and is suitable for the current energy situation that the peak load regulation and frequency modulation of the current unit and the variable load of a waste heat recovery system of the unit are more and more frequent. The method is simple and easy to implement, and has good optimization design and operation regulation and control effects.
In order to achieve the purpose, the invention adopts the following technical scheme:
design optimization method of flue gas waste heat recovery system, and m air heaters PAPHj(j 1-m) and n flue gas coolers FGCi(i is 1-n), the boiler, the air preheater APH, the turbine regenerative system RS and the dust remover ESP are connected through a pipeline valve system PVS to form a heat exchange network of the flue gas waste heat recovery system;
the optimized reference load rate and reference environment temperature of the flue gas waste heat recovery system are respectively the average load rate of the coal-fired unit in the total year of nearly 3 years and the average minimum environment temperature in the past year, and the optimization method of the flue gas waste heat recovery system is composed of an objective function, parameters to be optimized, constraint conditions and a solving method, and specifically comprises the following steps:
(1) the optimized objective function of the flue gas waste heat recovery system is as follows: total net present value C within age zNPVMaximum:
Figure BDA0003050520270000021
CIk=Δb·Nd·Pc·h
Figure BDA0003050520270000022
Figure BDA0003050520270000023
in the formula: cNPVIs the total net present value, Yuan; k is the kth year of the z years of service life; z is the service life of the flue gas waste heat recovery system; CIkEarnings, yuan, for the k year; CO 2kCost for the k year, Yuan; r is a reference yield; delta b is the standard coal saving rate of the flue gas waste heat recovery system, kg/kWh; n is a radical ofdFor turbine power, kW; pcThe standard coal price is Yuan/kg; h is the annual operating hours, hours/year of the flue gas waste heat recovery system; e is the total construction cost of the waste heat recovery system, Yuan; eFCGiFor flue gas coolers FGCiThe construction cost of (1) is low; ePAPHjIs a fan heater PAPHjThe construction cost of (1) is low; etThe total of annual system maintenance cost, management cost and material cost;
(2) the parameters to be optimized for optimizing the flue gas waste heat recovery system are as follows:
flue gas cooler FGCiArea A ofFi,m2(ii) a Air heater PAPHjArea A ofPj,m2(ii) a Air heater PAPHjWater side circulation water flowD wcjKg/s; flue gas cooler FGC introduced from turbine regenerative systemiAmount of condensed water DwiKg/s; flue gas cooler FGC introduced from turbine regenerative systemiWater temperature t of condensed waterwi(ii) a Inlet air temperature t of air preheater1DEG C; air heater PAPHjWater side circulating water outlet water temperature twj,℃;
(3) The optimized constraint conditions of the flue gas waste heat recovery system are as follows: flue gas cooler FGCi、PAPHjThe temperature of the inner water is higher than 70 ℃; the temperature of the flue gas at the inlet of the dust remover ESP is 95 +/-5 ℃;
(4) the solving method for the optimization of the flue gas waste heat recovery system comprises the following steps: the non-dominated sorting genetic algorithm with elite strategy NSGA-II, namely:
max CNPV=NSGA(AFi,APj,Dwcj,Dwi,twi,twj,t1)
the constraint conditions are as follows:
Figure BDA0003050520270000031
in the formula thFor tail flue gas coolers FGCnThe temperature of the outlet flue gas entering the dust remover ESP is lower than the temperature of the outlet flue gas entering the dust remover ESP; t is t1,minThe lower limit of the temperature of the air at the inlet of the APH of the air preheater is DEG C; t is t1,maxThe upper limit of the APH inlet air temperature of the air preheater is DEG C; dwcj,minIs a fan heater PAPHjThe lower limit of the water side circulating water flow, kg/s; dwcj,maxIs a fan heater PAPHjThe upper limit of the water side circulating water flow of (1), kg/s; dwi,minFor flue gas coolers FGCiThe lower limit of the amount of the condensed water (g/s); dwi,maxFor flue gas coolers FGCiThe upper limit of the amount of the condensed water of (4), kg/s.
The regulation and control method for the optimized waste heat recovery system obtained by the optimized design method comprises the following steps:
1) when the flue gas temperature at the inlet of the dust collector ESP is more than 100 ℃, the flue gas cooler FGC is adjustediThe opening of the regulating valve of the condensed water pipeline is mixed with low-temperature condensed water to ensure that the temperature t of the condensed water led into the flue gas cooler is equal towiReducing under the condition of ensuring that low-temperature corrosion does not occur so as to ensure that the temperature of the flue gas at the inlet of an ESP (electronic stability program) of the dust remover does not exceed 100 ℃;
2) if the temperature or load factor is reduced along with the ambient temperature, the PAPH of the air heaterjWater side circulating water outlet water temperature twjWhen the temperature is lower than 70 ℃, the rotating frequency of the circulating water pump is increased to 1-2 times to improve the circulating water flow, and the PAPH of the air heater is ensuredjWater side circulating water outlet water temperature twjNot less than 70 ℃;
3) if the temperature is reduced or the load factor is reduced along with the environmental temperature, the method in the step 2) still cannot ensure the PAPH of the air heaterjWater side circulating water outlet water temperature twjAt the temperature of not less than 70 ℃, on the basis of the measures in 2), ensuring the temperature t of the condensed water introduced into the flue gas coolerwiThe opening degree of the regulating valve is unchanged and regulated to lead the flue gas to the flue gas cooler FGCiAmount of condensed water DwiReduce the temperature to 1-0.2 times of the original temperature, and ensure the PAPH of the air heaterjWater side circulating water outlet water temperature twjNot lower than 70 ℃.
THE ADVANTAGES OF THE PRESENT INVENTION
(1) The flue gas waste heat recovery system covered by the invention has wide types and strong applicability;
(2) the total annual average load rate and the annual average lowest environmental temperature of the coal-fired unit in nearly 3 years are respectively used as the design reference load rate and the design reference environmental temperature of the system, and the method can be more suitable for the trend that the load of the current coal-fired unit is more frequent than the method that the rated load rate and the normal temperature of the coal-fired unit are used as the design reference load rate and the design reference environmental temperature of the system;
(3) the design reference load rate and the design reference environment temperature adopted by the invention can be effectively combined with the multi-parameter optimization intelligent algorithm, the advantages of the multi-parameter optimization intelligent algorithm in the design of the thermodynamic system are fully exerted, and the defect that the conventional design by adopting the multi-parameter optimization intelligent algorithm cannot take into account the variable working condition characteristics is overcome;
(4) the invention reasonably utilizes the existing unit operation data and environmental meteorological data, scientifically and reasonably considers the variable working condition which the flue gas waste heat recovery system may experience in the design stage, the obtained design configuration is more perfect and reasonable, and only the internal operation parameters of the system need to be adjusted to be used as the system operation regulation and control measure without additionally installing other equipment. The operation regulation and control measures have low cost and are simple and easy to implement;
(5) the method simply and effectively considers the influence of the variable working conditions of the coal-fired unit on the flue gas waste heat recovery system into the design of the flue gas waste heat recovery system, and is simple, convenient and easy to implement.
Drawings
FIG. 1 is a diagram of a flue gas waste heat recovery system of a coal-fired power plant.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The design optimization method of the flue gas waste heat recovery system comprises the steps that as shown in figure 1, m air heaters PAPHj(j 1-m) and n flue gas coolers FGCiAnd (i is 1-n), the boiler, the air preheater APH, the turbine regenerative system RS and the dust remover ESP are connected through a pipeline valve system PVS to form a heat exchange network of the flue gas waste heat recovery system.
The optimized reference load rate and reference environment temperature of the flue gas waste heat recovery system are respectively the average load rate of the coal-fired unit in the total year of nearly 3 years and the average minimum environment temperature in the past year, and the optimization method of the flue gas waste heat recovery system is composed of an objective function, parameters to be optimized, constraint conditions and a solving method, and specifically comprises the following steps:
(1) the optimized objective function of the flue gas waste heat recovery system is as follows: total net present value C within age zNPVMaximum:
Figure BDA0003050520270000061
CIk=Δb·Nd·Pc·h
Figure BDA0003050520270000062
Figure BDA0003050520270000063
in the formula: cNPVIs the total net present value, Yuan; k is the kth year of the z years of service life; z is flue gasThe service life of the waste heat recovery system; CIkEarnings, yuan, for the k year; CO 2kCost for the k year, Yuan; r is a reference yield; delta b is the standard coal saving rate of the flue gas waste heat recovery system, kg/kWh; n is a radical ofdFor turbine power, kW; pcThe standard coal price is Yuan/kg; h is the annual operating hours, hours/year of the flue gas waste heat recovery system; e is the total construction cost of the waste heat recovery system, Yuan; eFCGiFor flue gas coolers FGCiThe construction cost of (1) is low; ePAPHjIs a fan heater PAPHjThe construction cost of (1) is low; etThe total of annual system maintenance, management and material costs.
(2) The parameters to be optimized for optimizing the flue gas waste heat recovery system are as follows:
flue gas cooler FGCiArea A ofFi,m2(ii) a Air heater PAPHjArea A ofPj,m2(ii) a Air heater PAPHjWater side circulation water flowD wcjKg/s; flue gas cooler FGC introduced from turbine regenerative systemiAmount of condensed water DwiKg/s; flue gas cooler FGC introduced from turbine regenerative systemiWater temperature t of condensed waterwi(ii) a Inlet air temperature t of air preheater1DEG C; air heater PAPHjWater side circulating water outlet water temperature twj,℃。
(3) The optimized constraint conditions of the flue gas waste heat recovery system are as follows: flue gas cooler FGCi、PAPHjThe temperature of the inner water is higher than 70 ℃; the temperature of the flue gas at the inlet of the dust remover ESP is 95 +/-5 ℃; the air temperature at the inlet of the air preheater, the water side circulating water flow of the air heater and the condensed water amount of the flue gas cooler are correspondingly limited.
(4) The solving method for the optimization of the flue gas waste heat recovery system comprises the following steps: the non-dominated sorting genetic algorithm NSGA-II with elite strategy. Namely:
max CNPV=NSGA(AFi,APj,Dwcj,Dwi,twi,twj,t1)
the constraint conditions are as follows:
Figure BDA0003050520270000071
in the formula thFor tail flue gas coolers FGCnThe temperature of the outlet flue gas entering the dust remover ESP is lower than the temperature of the outlet flue gas entering the dust remover ESP; t is t1,minThe lower limit of the temperature of the air at the inlet of the APH of the air preheater is DEG C; t is t1,maxThe upper limit of the APH inlet air temperature of the air preheater is DEG C; dwcj,minIs a fan heater PAPHjThe lower limit of the water side circulating water flow, kg/s; dwcj,maxIs a fan heater PAPHjThe upper limit of the water side circulating water flow of (1), kg/s; dwi,minFor flue gas coolers FGCiThe lower limit of the amount of the condensed water (g/s); dwi,maxFor flue gas coolers FGCiThe upper limit of the amount of the condensed water of (4), kg/s.
As a preferred embodiment of the invention, the flue gas cooler FGCiConstruction cost E ofFCGiAir heater PAPHjConstruction cost E ofPAPHjThe calculation methods are respectively as follows:
EFCGi=aFCGi·cFCGi·AFi
EPAPHj=aPAPHj·cPAPHj·APj
in the formula: a. theFiFor flue gas coolers FGCiHeat exchange area of m2;APjIs a fan heater PAPHjHeat exchange area of m2;cFCGiFor flue gas coolers FGCiPrice per unit area heat exchange surface, yuan/m2;cPAPHjIs a fan heater PAPHjPrice per unit area heat exchange surface, yuan/m2;aFCGiFor flue gas coolers FGCiThe conversion coefficient of the construction cost of the heat exchange surface and the whole construction cost; a isPAPHjIs a fan heater PAPHjThe conversion coefficient of the construction cost of the heat exchange surface and the whole construction cost.
As a preferred embodiment of the invention, the method for calculating the standard coal saving rate Delta b of the flue gas waste heat recovery system comprises the following steps:
Δb=SCCR-SCCR1
Figure BDA0003050520270000081
Figure BDA0003050520270000082
ηnet=ηb·ηp·ηi·ηm·ηg(1-ξ)
ηnet1=ηb1·ηp·ηi1·ηm·ηg(1-ξ1)
in the formula: SCCR is original standard coal consumption rate of power plant, g (kWh)-1;SCCR1Standard coal consumption for a Power plant coupled with a waste Heat recovery System, g (kW h)-1;LHV0Lower calorific value of standard coal, LHV0=29,270kJ kg-1;ηnetThe original net thermal efficiency of the power plant; etanet1The net heat efficiency of the power plant after the waste heat recovery system is coupled for the power plant; etabThe original boiler efficiency of the power plant is obtained; etab1Coupling the boiler efficiency of the waste heat recovery system for the power plant; etapThe pipeline efficiency of the power plant; etaiThe absolute internal efficiency of the original turbine unit of the power plant is obtained; etai1The absolute internal efficiency of a steam turbine unit after a waste heat recovery system is coupled to a power plant; etamThe mechanical efficiency of the power plant; etagThe power plant generator efficiency; xi is the power consumption rate of the original power plant; xi1The power plant power consumption rate after the waste heat recovery system is coupled for the power plant.
As a preferred embodiment of the present invention, the sum E of the annual system maintenance fee, the management fee and the material feetThe estimation is carried out according to the percentage of the total construction cost E of the flue gas waste heat recovery system, and the percentage is taken as 2.5 percent of the total construction cost.
In a preferred embodiment of the present invention, the following features: the reference yield r is estimated according to 10%, and the service life z of the waste heat utilization system is estimated according to 10-15 years.
The regulation and control method for the optimized waste heat recovery system obtained by the optimized design method comprises the following steps:
1) when the flue gas temperature at the inlet of the dust collector ESP is more than 100 ℃, the flue gas cooler FGC is adjustediThe opening of the regulating valve of the condensed water pipeline is mixed with low-temperature condensed water to ensure that the temperature t of the condensed water led into the flue gas cooler is equal towiReducing under the condition of ensuring that low-temperature corrosion does not occur (the temperature of condensed water is not lower than 70 ℃) to ensure that the temperature of the flue gas at the inlet of an ESP (electronic stability program) of the dust remover does not exceed 100 ℃;
2) if the temperature or load factor is reduced along with the ambient temperature, the PAPH of the air heaterjWater side circulating water outlet water temperature twjWhen the temperature is lower than 70 ℃, the rotating frequency of the circulating water pump is increased to 1-2 times to improve the circulating water flow, and the PAPH of the air heater is ensuredjWater side circulating water outlet water temperature twjNot less than 70 ℃;
3) if the temperature is reduced or the load factor is reduced along with the environmental temperature, the method in the step 2) still cannot ensure the PAPH of the air heaterjWater side circulating water outlet water temperature twjAt the temperature of not less than 70 ℃, on the basis of the measures in 2), ensuring the temperature t of the condensed water introduced into the flue gas coolerwiThe opening degree of the regulating valve is unchanged and regulated to lead the flue gas to the flue gas cooler FGCiAmount of condensed water DwiReduce the temperature to 1-0.2 times of the original temperature, and ensure the PAPH of the air heaterjWater side circulating water outlet water temperature twjNot lower than 70 ℃.
The invention discloses a multi-parameter intelligent optimization algorithm represented by a non-dominated sorting genetic algorithm (NSGA-II) with an elite strategy, which is an optimization solving method for searching an optimal solution by simulating biological phenomena in nature. The method does not need to know the mathematical characteristics of the optimal solution of the optimization problem, but carries out heuristic optimization solution on the optimization problem, and can obtain the solution closest to the optimal solution in the shortest time. Has wide application in the engineering field. By utilizing the characteristic of the multi-parameter intelligent optimization algorithm, the multi-parameter optimization problem of thermodynamic systems such as a flue gas waste heat recovery system and the like can be solved quickly and effectively. And obtaining an optimal optimization scheme which is integrally and comprehensively optimal under corresponding constraint and design conditions.

Claims (6)

1. A design optimization method of a flue gas waste heat recovery system is characterized by comprising the following steps:
m air heater PAPHj1-m and n flue gas coolers FGCi1-n, a boiler, an air preheater APH, a steam turbine regenerative system RS and a dust remover ESP are connected through a pipeline valve system PVS to form a heat exchange network of the flue gas waste heat recovery system;
the optimized reference load rate and reference environment temperature of the flue gas waste heat recovery system are respectively the average load rate of the coal-fired unit in the total year of nearly 3 years and the average minimum environment temperature in the past year, and the optimization method of the flue gas waste heat recovery system is composed of an objective function, parameters to be optimized, constraint conditions and a solving method, and specifically comprises the following steps:
(1) the optimized objective function of the flue gas waste heat recovery system is as follows: total net present value C within age zNPVMaximum:
Figure FDA0003456867560000011
CIk=Δb·Nd·Pc·h
Figure FDA0003456867560000012
Figure FDA0003456867560000013
in the formula: cNPVIs the total net present value, Yuan; k is the kth year of the z years of service life; z is the service life of the flue gas waste heat recovery system; CIkEarnings, yuan, for the k year; CO 2kCost for the k year, Yuan; r is a reference yield; delta b is the standard coal saving rate of the flue gas waste heat recovery system, kg/kWh; n is a radical ofdFor turbine power, kW; pcThe standard coal price is Yuan/kg; h is the annual operating hours, hours/year of the flue gas waste heat recovery system; e is a waste heat recovery systemTotal construction cost of the system, yuan; eFCGiFor flue gas coolers FGCiThe construction cost of (1) is low; ePAPHjIs a fan heater PAPHjThe construction cost of (1) is low; etThe total of annual system maintenance cost, management cost and material cost;
(2) the parameters to be optimized for optimizing the flue gas waste heat recovery system are as follows:
flue gas cooler FGCiArea A ofFi,m2(ii) a Air heater PAPHjArea A ofPj,m2(ii) a Air heater PAPHjWater side circulation water flowD wcjKg/s; flue gas cooler FGC introduced from turbine regenerative systemiAmount of condensed water DwiKg/s; flue gas cooler FGC introduced from turbine regenerative systemiWater temperature t of condensed waterwi(ii) a Inlet air temperature t of air preheater1DEG C; air heater PAPHjWater side circulating water outlet water temperature twj,℃;
(3) The optimized constraint conditions of the flue gas waste heat recovery system are as follows: flue gas cooler FGCi、PAPHjThe temperature of the inner water is higher than 70 ℃; the temperature of the flue gas at the inlet of the dust remover ESP is 95 +/-5 ℃;
(4) the solving method for the optimization of the flue gas waste heat recovery system comprises the following steps: the non-dominated sorting genetic algorithm with elite strategy NSGA-II, namely:
max CNPV=NSGA(AFi,APj,Dwcj,Dwi,twi,twj,t1)
the constraint conditions are as follows:
Figure FDA0003456867560000021
in the formula thFor tail flue gas coolers FGCnThe temperature of the outlet flue gas entering the dust remover ESP is lower than the temperature of the outlet flue gas entering the dust remover ESP; t is t1,minThe lower limit of the temperature of the air at the inlet of the APH of the air preheater is DEG C; t is t1,maxThe upper limit of the APH inlet air temperature of the air preheater is DEG C; dwcj,minIs a fan heater PAPHjWater side circulation ofThe lower limit of the circulation water flow is kg/s; dwcj,maxIs a fan heater PAPHjThe upper limit of the water side circulating water flow of (1), kg/s; dwi,minFor flue gas coolers FGCiThe lower limit of the amount of the condensed water (g/s); dwi,maxFor flue gas coolers FGCiThe upper limit of the amount of the condensed water of (4), kg/s.
2. The design optimization method of the flue gas waste heat recovery system according to claim 1, characterized in that: flue gas cooler FGCiConstruction cost E ofFCGiAir heater PAPHjConstruction cost E ofPAPHjThe calculation methods are respectively as follows:
EFCGi=aFCGi·cFCGi·AFi
EPAPHj=aPAPHj·cPAPHj·APj
in the formula: a. theFiFor flue gas coolers FGCiHeat exchange area of m2;APjIs a fan heater PAPHjHeat exchange area of m2;cFCGiFor flue gas coolers FGCiPrice per unit area heat exchange surface, yuan/m2;cPAPHjIs a fan heater PAPHjPrice per unit area heat exchange surface, yuan/m2;aFCGiFor flue gas coolers FGCiThe conversion coefficient of the construction cost of the heat exchange surface and the whole construction cost; a isPAPHjIs a fan heater PAPHjThe conversion coefficient of the construction cost of the heat exchange surface and the whole construction cost.
3. The design optimization method of the flue gas waste heat recovery system according to claim 1, characterized in that: the standard coal saving rate delta b calculation method of the flue gas waste heat recovery system comprises the following steps:
Δb=SCCR-SCCR1
Figure FDA0003456867560000031
Figure FDA0003456867560000032
ηnet=ηb·ηp·ηi·ηm·ηg(1-ξ)
ηnet1=ηb1·ηp·ηi1·ηm·ηg(1-ξ1)
in the formula: SCCR is original standard coal consumption rate of power plant, g (kWh)-1;SCCR1Standard coal consumption for a Power plant coupled with a waste Heat recovery System, g (kW h)-1;LHV0Lower calorific value of standard coal, LHV0=29,270kJ kg-1;ηnetThe original net thermal efficiency of the power plant; etanet1The net heat efficiency of the power plant after the waste heat recovery system is coupled for the power plant; etabThe original boiler efficiency of the power plant is obtained; etab1Coupling the boiler efficiency of the waste heat recovery system for the power plant; etapThe pipeline efficiency of the power plant; etaiThe absolute internal efficiency of the original turbine unit of the power plant is obtained; etai1The absolute internal efficiency of a steam turbine unit after a waste heat recovery system is coupled to a power plant; etamThe mechanical efficiency of the power plant; etagThe power plant generator efficiency; xi is the power consumption rate of the original power plant; xi1The power plant power consumption rate after the waste heat recovery system is coupled for the power plant.
4. The design optimization method of the flue gas waste heat recovery system according to claim 1, characterized in that: sum E of annual system maintenance, administration and material coststThe estimation is carried out according to the percentage of the total construction cost E of the flue gas waste heat recovery system, and the percentage is taken as 2.5 percent of the total construction cost.
5. The design optimization method of the flue gas waste heat recovery system according to claim 1, characterized in that: the reference yield r is estimated according to 10%, and the service life z of the waste heat utilization system is estimated according to 10-15 years.
6. The method for regulating and controlling an optimized waste heat recovery system obtained by the optimized design method of any one of claims 1 to 5, characterized in that: the method comprises the following steps:
1) when the flue gas temperature at the inlet of the dust collector ESP is more than 100 ℃, the flue gas cooler FGC is adjustediThe opening of the regulating valve of the condensed water pipeline is mixed with low-temperature condensed water to ensure that the temperature t of the condensed water led into the flue gas cooler is equal towiReducing under the condition of ensuring that low-temperature corrosion does not occur so as to ensure that the temperature of the flue gas at the inlet of an ESP (electronic stability program) of the dust remover does not exceed 100 ℃;
2) if the temperature or load factor is reduced along with the ambient temperature, the PAPH of the air heaterjWater side circulating water outlet water temperature twjWhen the temperature is lower than 70 ℃, the rotating frequency of the circulating water pump is increased to 1-2 times to improve the circulating water flow, and the PAPH of the air heater is ensuredjWater side circulating water outlet water temperature twjNot less than 70 ℃;
3) if the temperature is reduced or the load factor is reduced along with the environmental temperature, the method in the step 2) still cannot ensure the PAPH of the air heaterjWater side circulating water outlet water temperature twjAt the temperature of not less than 70 ℃, on the basis of the measures in 2), ensuring the temperature t of the condensed water introduced into the flue gas coolerwiThe opening degree of the regulating valve is unchanged and regulated to lead the flue gas to the flue gas cooler FGCiAmount of condensed water DwiReduce the temperature to 1-0.2 times of the original temperature, and ensure the PAPH of the air heaterjWater side circulating water outlet water temperature twjNot lower than 70 ℃.
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