Dynamic theoretical prediction method for heat storage of CFB unit during near zero depth peak regulation process

Abstract

The present application belongs to the technical field of subcritical circulating fluidized bed unit participating in the flexibility reconstruction of power grid peak regulation, and particularly relates to a dynamic theoretical prediction method for heat storage in the near-zero deep peak regulation process of a CFB unit. According to the state of the subcritical CFB power unit in the near-zero deep peak regulation process, three state parameters are divided, i.e. high-parameter heat storage state, process heat release state and safe and stable heat state. The heat storage corresponding to the safe and stable heat state includes apparent total heat storage, apparent dynamic heat storage surplus and apparent dynamic heat release. Through the calculation of the apparent total heat storage, apparent dynamic heat storage surplus and apparent dynamic heat release obtained by the difference of the three state parameters and the effective apparent dynamic heat storage surplus, the dynamic theoretical prediction of the boiler heat storage in the near-zero deep peak regulation process is realized. The present application provides a theoretical basis for the quantitative calculation of heat storage and release in the near-zero deep peak regulation process of a circulating fluidized bed boiler, and provides a reference for the optimization of a control system and the improvement of unit flexibility.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of subcritical circulating fluidized bed unit participating in grid peak shaving flexibility reconstruction theory and method, and particularly relates to a dynamic theoretical prediction method for heat storage capacity in a near-zero deep peak shaving process of a CFB unit. BACKGROUND

[0002] With large-scale access of new energy, the power system will present significant "double peak double high" and "double-sided randomness", and the operation safety of the power grid is facing new challenges. Deep peak shaving of thermal power units has far-reaching significance for promoting low-carbon, flexible and efficient development of thermal power under the new power system. Circulating fluidized bed units can use their strong heat storage capacity for high-pressure fire operation - near-zero super-long deep peak shaving, and have significant advantages in dealing with instability of wind power and photovoltaic and volatility of extreme weather. The estimation of the heat storage capacity of the circulating fluidized bed unit plays an important guiding role in the near-zero super-long deep peak shaving of the subcritical CFB boiler. However, there is no report on the system calculation of the heat storage capacity in the near-zero super-long deep peak shaving process of the circulating fluidized bed unit. Therefore, it is of important practical significance to establish a heat storage calculation and analysis method in the deep peak shaving process of the circulating fluidized bed unit and apply it to the theoretical guidance of the actual operation of the near-zero super-long deep peak shaving, so as to ensure the safe and stable operation of the power system.

[0003] In order to improve the flexibility of deep load regulation of thermal power plants, many studies are devoted to the monitoring of fuel combustion heat storage and the feedforward processing of heat storage coefficient during variable load process of the boiler, and the technical description of the pressure fire operation of the circulating fluidized bed boiler. At present, the main pressure fire operation and protection method, patent CN101709873A invents a 300000KW circulating fluidized bed boiler pressure fire operation method with an external bed; patent CN110296436A invents a method for improving the stability of pressure fire and fire raising by computer control to improve the success rate of boiler pressure fire restart and start-up stability; patent CN204986988U discloses a circulating fluidized bed boiler pressure fire explosion-proof system, which avoids the accumulation of combustible gas in the air chamber and improves the safety performance of the boiler equipment. The above patents are all for pressure fire protection for safety defect elimination, and are not for high pressure fire of near zero super long deep load regulation. Moreover, the heat storage and available heat storage during the pressure fire process are not quantitatively calculated. In the current patents about circulating fluidized bed heat storage calculation and prediction, patent CN105243178A discloses a system and method for quantitatively calculating the coal heating release time of circulating fluidized bed boiler under different load sections and different operating conditions; patent CN112214735A discloses an online calculation method for the difference between the set value and the real-time value of the heat storage of metal and working medium during variable load process of the boiler; patent CN109991845A discloses a method and system for calculating the energy storage coefficient of a thermal power unit by using the steam drum heat storage ratio and the main steam pressure deviation function, and introducing it into the coordinated control system of the thermal power unit; CN105042582A discloses a system and method for monitoring the heat released by the combustion of various substances in the furnace during coal feeding. The heat storage considered in the above patents is only applicable to the variable load operation process of the circulating fluidized bed unit, and is not applicable to the near zero deep load regulation process of the circulating fluidized bed unit. Patent CN111322602A invents a method for adapting to deep load regulation of power grid by reducing the steam turbine load to 3-8MW through subcritical CFB boiler pressure fire, ensuring 2-3 hours of low load operation without network disconnection; patent CN111322602A invents a method for realizing deep load regulation of 0-100% full load section, ensuring that the boiler does not stop without stopping the machine, and meeting the load regulation requirements of the power grid. However, the above patents are only deep load regulation methods, and the heat storage during near zero deep load regulation process is not quantitatively calculated. SUMMARY

[0004] In view of the above technical problems, the present application provides a dynamic theoretical prediction method for heat storage during near zero deep load regulation process of CFB unit, which can provide a basis for quantitatively calculating the heat storage and release during near zero super long deep load regulation process of circulating fluidized bed boiler, and provide a reference for optimization of control system and improvement of unit flexibility.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is:

[0006] The dynamic theoretical prediction method for heat storage amount in the near-zero long-depth peak regulation process of CFB unit is based on the state of the subcritical CFB power unit in the near-zero long-depth peak regulation process, and is divided into three state parameters of high-parameter heat storage state, process heat release state and safe and stable heat state. The heat storage amount corresponding to the safe and stable heat state includes apparent total heat storage amount, apparent dynamic heat storage surplus and apparent dynamic heat release amount.

[0007] Through the calculation of apparent total heat storage amount, apparent dynamic heat storage surplus and apparent dynamic heat release amount and effective apparent dynamic heat storage surplus obtained by the difference of the three state parameters, the dynamic theoretical prediction of boiler heat storage amount in the near-zero long-depth peak regulation process is realized.

[0008] Further, the high-parameter heat storage state is the initial state in the near-zero long-depth peak regulation, and stopping feeding and air supply is taken as the symbol; the process heat release state is the process state in the near-zero long-depth peak regulation process, and the near-zero load operation is taken as the symbol; and the safe and stable heat state is the state at the end of the near-zero long-depth peak regulation, and the bed temperature and the steam temperature are taken as the main safety and stable heat state.

[0009] Further, the apparent total heat storage amount is the theoretical total heat storage amount obtained by the difference between the high-parameter heat storage state and the safe and stable heat state.

[0010] The apparent total heat storage amount calculation method is:

[0011] Q T，the =Q T，w +Q T，m +Q T，a +Q T，c +Q T，f

[0012] In the formula, Q T，the is the apparent total heat storage amount, Q T，w is the total steam and water heat storage amount, Q T，m is the total metal wall heat storage amount, Q T，a is the total bed material carrier heat storage amount, Q T，c is the total pouring layer heat storage amount, and Q T，f is the total flue gas heat storage amount.

[0013] Further, the total steam and water heat storage amount calculation method is:

[0014] Q T，w =∑ρ i，H h i，H V i，H -∑ρ i，S h i，S V i，S

[0015] In the formula: Q T，w is the total amount of steam-water heat storage, GJ; p i，H , h i，H , p i，S , h i，S are the high-parameter heat storage state steam-water density, high-parameter heat storage state steam-water enthalpy, safe and stable heat state steam-water density, safe and stable heat state steam-water enthalpy, kg / m 3 , kJ / kg, kg / m 3 , kJ / kg; V i，H , V i，S are the high-parameter heat storage state steam-water volume, m 3 ;

[0016] The calculation method of the total amount of metal wall heat storage is:

[0017] Q T，m =∑C pj m j (T j，H -T j，S )

[0018] In the formula: Q T，m is the total amount of metal wall heat storage, GJ; C pj is the specific heat capacity of the metal wall, kJ / (kg·K); m j is the mass of the metal wall, kg; T j，H , T j，S are the high-parameter heat storage state metal wall temperature and the safe and stable heat state metal wall temperature, ℃;

[0019] The calculation method of the total amount of bed material carrier heat storage is:

[0020] Q T，a =∑C pa m k (T k，H -T k，S )

[0021] In the formula: Q T，a is the total amount of bed material carrier heat storage, C pa is the specific heat capacity of the bed material carrier, kJ / (kg·K); m k is the mass of the bed material carrier, kg; T k，H is the high-parameter heat storage state bed material carrier average temperature, ℃; T k，S is the safe and stable heat state bed material carrier average temperature, ℃;

[0022] The calculation method of the total amount of pouring layer heat storage is:

[0023] Q T，c =∑C pc m c (T c，H -T c，S )

[0024] In the formula: Q T，c The total heat storage of the casting layer, GJ;C pc The specific heat capacity of the casting layer is kJ / (kg·K); m c For the mass of the cast layer, kg; T c，H The average temperature of the high-parameter heat storage layer in the casting state is ℃; T c，S The average temperature of the hot-state pouring layer is ℃;

[0025] The method for calculating the total heat storage of flue gas is as follows:

[0026] Q T，f =∑ρ fH h fH V fH -∑ρ fS h fS V fS

[0027] In the formula: Q T，f The total heat storage of flue gas, GJ; ρ fH The average density of the high-parameter regenerated flue gas is kg / m³. 3 h fH The average enthalpy of the high-parameter regenerated flue gas is given in kJ / kg; V fH For high-parameter heat storage state flue gas volume, m 3 ;ρ fS To ensure the safe and stable average density of flue gas in a hot state, kg / m³ 3 h fS For safe and stable thermal average enthalpy of flue gas, kJ / kg; V fS To ensure a safe and stable hot flue gas volume, m 3 .

[0028] Furthermore, the apparent dynamic heat storage margin is the real-time heat storage margin obtained by subtracting the heat release state from the safe steady-state; the calculation method for the apparent dynamic heat storage margin is as follows:

[0029] Q R，the =Q R，w +Q R，m +Q R，a +Q R，c +Q R，f

[0030] In the formula: Q R，the Q represents the apparent dynamic heat storage margin. R，w Q represents the heat storage capacity of the soft drink. R，m Q is the heat storage margin for the metal wall. R，a Q is the heat storage margin for the bed material carrier. R，c Q is the heat storage margin for the casting layer. n，f This is the residual heat storage capacity of the flue gas.

[0031] Further, the steam-water heat storage residual amount calculation method is:

[0032] Q R，w =∑ρ i，M h i，M V i，M -∑ρ i，S h i，S V i，S

[0033] In the formula: Q R，w is the steam-water heat storage residual amount, GJ; ρ i，M , h i，M , ρ i，S , h i，S are the process heat-releasing state steam-water density, process heat-releasing state steam-water enthalpy, safe and stable heat state steam-water density, safe and stable heat state steam-water enthalpy, kg / m 3 , kJ / kg, kg / m 3 , kJ / kg, respectively; V i，M , V i，S are the process heat-releasing state steam-water volume, m 3 ;

[0034] The metal wall heat storage residual amount calculation method is:

[0035] Q R，m =∑C pj m j (T j，M -T j，s )

[0036] In the formula: Q R，m is the metal wall heat storage residual amount, GJ; C pj is the specific heat capacity of the metal wall, kJ / (kg·K); m j is the mass of the metal wall, kg; T j，M , T j，s are the process heat-releasing state metal wall temperature and the safe and stable heat state metal wall temperature, ℃, respectively;

[0037] The bed material carrier heat storage residual amount calculation method is:

[0038] Q R，a =∑C pa m k (T k，M -T k，s )

[0039] In the formula: Q R，a is the bed material carrier heat storage residual amount, GJ; T k，M is the process heat-releasing state bed material carrier average temperature, ℃; T k，S is the safe and stable heat state bed material carrier average temperature, ℃;

[0040] The method for calculating the heat storage surplus of the casting layer is:

[0041] Q R，c =∑C pc m c (T c，M -T c，s )

[0042] In the formula, Q R，c is the heat storage surplus of the casting layer, GJ; T c，M is the average temperature of the casting layer in the heat releasing state of the process, ℃; T c，S is the average temperature of the casting layer in the safe and heat stabilizing state, ℃.

[0043] The method for calculating the heat storage surplus of the flue gas is:

[0044] Q R，f =∑ρ fM h fM V fM -∑ρ fS h fS V fS

[0045] In the formula, Q R，f is the heat storage surplus of the flue gas, GJ; ρ fM is the average density of the flue gas in the heat storage state of the high parameter, kg / m 3 ; h fM is the average enthalpy of the flue gas in the heat storage state of the high parameter, kJ / kg; V fM is the amount of the flue gas in the heat storage state of the high parameter, m 3 ; ρ fS is the average density of the flue gas in the safe and heat stabilizing state, kg / m 3 ; h fS is the average enthalpy of the flue gas in the safe and heat stabilizing state, kJ / kg; V fS is the amount of the flue gas in the safe and heat stabilizing state, m 3 .

[0046] Further, the apparent dynamic heat releasing amount is the difference between the apparent total heat storage amount and the apparent dynamic heat storage surplus, and the apparent dynamic heat releasing amount is mainly composed of three parts of heat consumption, i.e., the heat consumption of the steam turbine, the heat consumption of the boiler body and the heat consumption of the flue gas; the method for calculating the apparent dynamic heat releasing amount is:

[0047] Q U，the =Q T，the -Q R，the

[0048] In the formula, Q U，the is the apparent dynamic heat releasing amount, Q T，the is the apparent total heat storage amount, and Q R，the is the apparent dynamic heat storage surplus.

[0049] Further, the ratio of the heat consumption of the steam turbine to the apparent dynamic heat release amount is the effective heat release rate;

[0050] The effective heat release rate calculation method is:

[0051]

[0052] In the formula: η v is the effective heat release rate, Q t is the heat consumption of the steam turbine, Q U，the is the apparent heat storage total amount;

[0053] The heat consumption calculation method of the steam turbine is:

[0054] Q 热耗 = D0 x h0 - D fw x h fw + D rh x h rh - D rc x h rc - D rcw x h rcw - D rhw x h rhw

[0055] In the formula: Q 热耗 is the heat consumption of the steam turbine, GJ / h; D0, h0 are the main steam flow and enthalpy, t / h, kJ / kg; D fw , h fw are the main feed water flow and enthalpy, t / h, kJ / kg; D rh , h rh are the reheat steam flow and enthalpy, t / h, kJ / kg; D rc , h rc are the high-pressure cylinder exhaust steam flow and enthalpy, t / h, kJ / kg; D rw , h rw are the reheat water flow and enthalpy, t / h, kJ / kg; D rcw , h rcw are the superheater water flow and enthalpy, t / h, kJ / kg;

[0056] Q t = ∫0 t Q 热耗 dt

[0057] In the formula: Q t is the heat consumption of the steam turbine, GJ.

[0058] Further, the effective apparent dynamic heat storage residual amount is the product of the apparent dynamic heat storage residual amount and the effective heat release rate, that is, the apparent dynamic heat storage residual amount actually playing a role in the heat consumption of the steam turbine; the effective apparent dynamic heat storage residual amount calculation method is:

[0059] Q R，v = Q R，the x η v

[0060] Q = Q R，v is the effective apparent dynamic heat storage, Q R，the is the apparent dynamic heat storage, η v is the effective heat release rate.

[0061] Compared with the prior art, the present application has the beneficial effects that:

[0062] According to the state of the subcritical CFB power generating unit in the near-zero super-long depth peak regulation process, three state parameters are divided, including the high parameter heat storage state marked by stopping feeding air, the process heat release state marked by near-zero load operation, and the safe and stable heat state with bed temperature and steam temperature as the main safety fire boundary. Through the calculation of the apparent heat storage, the apparent dynamic heat storage, the apparent dynamic heat release, and the effective apparent dynamic heat storage obtained by the difference of the three state parameters, the dynamic theoretical prediction of the boiler heat storage in the near-zero super-long depth peak regulation process can be realized.

[0063] In summary, through the heat storage calculation method in the near-zero super-long depth peak regulation process of the subcritical CFB power generating unit provided by the present application, the dynamic theoretical prediction of the boiler heat storage in the near-zero super-long depth peak regulation process is obtained, which provides a theoretical basis for the quantitative calculation of heat storage and release in the near-zero super-long depth peak regulation process of the circulating fluidized bed boiler, and provides a reference for the optimization of the control system and the improvement of the unit flexibility. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is the schematic diagram of heat storage of each part of the subcritical circulating fluidized bed boiler in the present application;

[0065] Figure 2 is the schematic diagram of defining the state of each heat storage part in the near-zero super-long depth peak regulation process in the present application;

[0066] Figure 3 is the trend graph of bed temperature changing with the near-zero super-long depth peak regulation process in Example 1 of the present application;

[0067] Figure 4 is the trend graph of the calculated apparent dynamic heat storage changing with time in Example 1 of the present application;

[0068] Figure 5 is the trend graph of the calculated apparent dynamic heat release changing with time in Example 1 of the present application;

[0069] Figure 6 is the trend graph of the main steam temperature changing with the near-zero super-long depth peak regulation process in Example 2 of the present application;

[0070] Figure 7 is a trend chart of the calculated apparent dynamic heat storage amount over time in Example 2 of the present application;

[0071] Figure 8 is a trend chart of the calculated apparent dynamic heat release amount over time in Example 2 of the present application. DETAILED DESCRIPTION

[0072] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0073] As shown in Figure 1 and 2 , the dynamic theoretical prediction method of heat storage amount in the near-zero depth peak regulation process of CFB unit, which includes, according to the state of the subcritical CFB power unit in the near-zero depth peak regulation process, is divided into high-parameter heat storage state, process heat release state and safe stable heat state; the heat storage amount corresponding to the high-parameter heat storage state, the process heat release state and the safe stable heat state includes the apparent total heat storage amount, the apparent dynamic heat storage amount and the apparent dynamic heat release amount; in the actual operation process, the apparent dynamic heat storage amount is affected by the non-ideal heat consumption, and is not all used for the ideal conversion of the steam turbine heat consumption, so the effective apparent dynamic heat storage amount is also defined.

[0074] As a further improvement of the above-mentioned scheme, the high-parameter heat storage state is the starting state in the near-zero depth peak regulation process, marked by stopping the feeding of the material and air; the parameters used for the boiler heat storage calculation include: high-parameter heat storage state inlet temperature, outlet temperature, inlet pressure, outlet pressure, steam-water density, steam-water enthalpy, steam-water volume, metal wall temperature, bed material carrier average temperature, bed material carrier mass, casting layer average temperature, casting layer mass, flue gas average density, flue gas average enthalpy, flue gas volume, flue gas average temperature, flue gas pressure.

[0075] As a further improvement of the above-mentioned scheme, the process heat release state is the process state in the near-zero depth peak regulation process, marked by near-zero load operation; the parameters used for the boiler heat storage calculation include: process heat release state inlet temperature, outlet temperature, inlet pressure, outlet pressure, steam-water density, steam-water enthalpy, steam-water volume, metal wall temperature, bed material carrier average temperature, bed material carrier mass, casting layer average temperature, casting layer mass, flue gas average density, flue gas average enthalpy, flue gas volume, flue gas average temperature, flue gas pressure.

[0076] As a further improvement of the above-mentioned scheme, the safe steady state is the state at the end of near-zero super-long deep peak shaving, with bed temperature and steam temperature as the main safe fire boundary; the parameters used for boiler heat storage calculation include: safe steady state inlet temperature, outlet temperature, inlet pressure, outlet pressure, steam and water density, steam and water enthalpy, steam and water volume, metal wall temperature, bed material carrier average temperature, bed material carrier mass, pouring layer average temperature, pouring layer mass, flue gas average density, flue gas average enthalpy, flue gas volume, flue gas average temperature, flue gas pressure.

[0077] As a further improvement of the above-mentioned scheme, the apparent total heat storage is the theoretical total heat storage obtained by subtracting the safe steady state from the high parameter heat storage state, and the apparent total heat storage used for boiler heat storage calculation includes steam and water total heat storage, metal wall total heat storage, bed material carrier total heat storage, pouring layer total heat storage, flue gas total heat storage.

[0078] The apparent total heat storage calculation method is:

[0079] Q T，the =Q T，w +Q T，m +Q T，a +Q T，c +Q T，f

[0080] In the formula: Q T，the is the apparent total heat storage, Q T，w is the steam and water total heat storage, Q T，m is the metal wall total heat storage, Q T，a is the bed material carrier total heat storage, Q T，c is the pouring layer total heat storage, and Q T，f is the flue gas total heat storage.

[0081] The steam and water total heat storage calculation method is:

[0082] Q T，w =∑ρ i，H h i，H V i，H -∑ρ i，S h i，S V i，S

[0083] In the formula: Q T，w is the steam and water total heat storage, GJ; ρ i，H , h i，H , ρ i，S , h i，SHigh parameter regenerative state steam-water density, high parameter regenerative state steam-water enthalpy, safe steady state steam-water density, safe steady state steam-water enthalpy (i includes: 1 unsaturated water in economizer, 2 saturated water in boiler water cooling system (water cooling wall and the part below the interface of steam-water in steam drum), 3 superheated steam above the interface of steam-water in steam drum, 4 superheated steam in cyclone separator, 5 superheated steam in superheater, 6 reheat steam in reheater), kg / m 3 , kJ / kg, kg / m 3 , kJ / kg; V i，H , V i，S High parameter regenerative state steam-water volume (i includes 1 economizer, 2 all of water cooling wall plus 1 / 2 of steam drum, 3 1 / 2 of steam drum, 4 cyclone separator, 5 superheater, 6 reheater), m 3 .

[0084] The calculation method of the total heat storage amount of the metal wall is:

[0085] Q T，m =∑C pj m j (T j，H -T j，S )

[0086] In the formula, Q T，m is the total heat storage amount of the metal wall, GJ; C pj is the specific heat capacity of the metal wall, kJ / (kg·K); m j is the mass of the metal wall, kg; T j，H and T j，S are the metal wall temperature of the high parameter regenerative state and the safe steady state respectively, ℃ (j includes 1 economizer, 2 water cooling wall, 3 steam drum, 4 cyclone separator, 5 superheater, 6 reheater).

[0087] The calculation method of the total heat storage amount of the bed material carrier is:

[0088] Q T，a =∑C pa m k (T k，H -T k，S )

[0089] In the formula, Q T，a is the total heat storage amount of the bed material carrier, C pa is the specific heat capacity of the bed material carrier, kJ / (kg·K); m k is the mass of the bed material carrier, kg; T k，H is the average temperature of the bed material carrier of the high parameter regenerative state, ℃; T k，S is the average temperature of the bed material carrier of the safe steady state, ℃ (wherein k includes 1 bed material, 2 circulating ash; T k，S ≥520℃, the critical temperature is different due to different fuels).

[0090] The method for calculating the total heat storage of the casting layer is as follows:

[0091] Q T，c =∑C pc m c (T c，H -T c，s )

[0092] In the formula: Q T，c The total heat storage of the casting layer, GJ;C pc The specific heat capacity of the casting layer is kJ / (kg·K); m c For the mass of the cast layer, kg; T c，H The average temperature of the high-parameter heat storage state cast layer is ℃; T c，S The average temperature of the safe and stable hot-state pouring layer is ℃.

[0093] The method for calculating the total heat storage of flue gas is as follows:

[0094] Q T，f =∑ρ fH h fH V fH -∑ρ fs h fS V fs

[0095] In the formula: Q T，f The total heat storage of flue gas, GJ; ρ fH The average density of the high-parameter regenerated flue gas is kg / m³. 3 h fH The average enthalpy of the high-parameter regenerated flue gas is given in kJ / kg; V fH For high-parameter regenerated flue gas volume, m 3 ;ρ fS To ensure the safe and stable average density of flue gas in a hot state, kg / m³ 3 h fS For safe and stable thermal average enthalpy of flue gas, kJ / kg; V fS To ensure a safe and stable hot flue gas volume, m 3 .

[0096] As a further improvement to the above scheme, the apparent dynamic heat storage margin is the real-time heat storage margin obtained by subtracting the heat release state from the safe steady-state. The apparent dynamic heat storage margin used for boiler heat storage calculations includes steam-water heat storage margin, metal wall heat storage margin, bed material carrier heat storage margin, cast-in-place layer heat storage margin, and flue gas heat storage margin. The calculation method for the apparent dynamic heat storage margin is as follows:

[0097] Q R，th e = Q R，w +Q R，m +Q R，a +QR，c +Q R，f

[0098] wherein: Q R，the is the apparent dynamic heat storage, Q R，w is the steam-water heat storage, Q R，m is the metal wall heat storage, Q R，a is the bed material carrier heat storage, Q R，c is the cast layer heat storage, Q R，f is the flue gas heat storage.

[0099] The steam-water heat storage calculation method is:

[0100] Q R，w =∑ρ i，M h i，M V i，M -∑ρ i，S h i，S V i，S

[0101] wherein: Q R，w is the steam-water heat storage, GJ; ρ i，M , h i，M , ρ i，S , h i，S are the process heat-releasing state steam-water density, process heat-releasing state steam-water enthalpy, safe and stable heat state steam-water density, safe and stable heat state steam-water enthalpy (i includes: 1 unsaturated water in the economizer, 2 saturated water in the boiler water cooling system (water cooling wall and the portion below the interface of the steam drum steam-water), 3 superheated steam above the interface of the steam drum steam-water, 4 superheated steam in the cyclone separator, 5 superheated steam in the superheater, 6 reheat steam in the reheater), kg / m 3 , kJ / kg, kg / m 3 , kJ / kg; V i，M , V i，S are the process heat-releasing state steam-water volume (i includes 1 economizer, 2 all of the water cooling wall plus 1 / 2 of the steam drum, 3 1 / 2 of the steam drum, 4 cyclone separator, 5 superheater, 6 reheater), m 3 .

[0102] The metal wall heat storage calculation method is:

[0103] Q R，m =∑C pj m j (T j，M -T j，s )

[0104] wherein: Q R，m is the metal wall heat storage, GJ; C pj is the specific heat capacity of the metal wall, kJ / (kg·K); m jM is the mass of the metal wall, kg; T j，M , T j，S are the process heat-releasing state metal wall temperature and the safe heat-stabilizing state metal wall temperature, respectively (j includes 1 economizer, 2 water-cooled wall, 3 steam drum, 4 cyclone separator, 5 superheater, 6 reheater), ℃.

[0105] The calculation method of the heat storage residual amount of the bed material carrier is:

[0106] Q R，a =∑C pa m k (T k，M -T k，S )

[0107] In the formula, Q R，a is the heat storage residual amount of the bed material carrier, GJ; T k，M is the process heat-releasing state bed material carrier average temperature (including bed material and circulating ash), ℃; T k，S is the safe heat-stabilizing state bed material carrier average temperature (including 1 bed material and 2 circulating ash; wherein T k，S ≥520℃, this critical temperature is different due to different fuels), ℃.

[0108] The calculation method of the heat storage residual amount of the cast layer is:

[0109] Q R，c =∑C pc m c (T c，M -T c，S )

[0110] In the formula, Q R，c is the heat storage residual amount of the cast layer, GJ; T c，M is the process heat-releasing state cast layer average temperature, ℃; T c，S is the safe heat-stabilizing state cast layer average temperature, ℃.

[0111] The calculation method of the heat storage residual amount of the flue gas is:

[0112] Q R，f =∑ρ fM h fM V fM -∑ρ fS h fS V fS

[0113] In the formula, Q R，f is the heat storage residual amount of the flue gas, GJ; ρ fM is the high-parameter heat-storage state flue gas average density, kg / m 3 ; h fM is the high-parameter heat-storage state flue gas average enthalpy, kJ / kg; V fM is the high-parameter heat-storage state flue gas volume, m3 ; p fS ρs is the average density of the safe steady state flue gas, kg / m3 3 ; h fS hs is the average enthalpy of the safe steady state flue gas, kJ / kg; V fS Vs is the safe steady state flue gas volume, m3 3 .

[0114] As a further improvement of the above scheme, the apparent dynamic heat release is the difference between the apparent total heat storage and the apparent dynamic heat storage surplus, and the apparent dynamic heat release is mainly composed of three parts of heat consumption, which are the steam turbine heat consumption, the boiler body heat consumption and the flue gas heat consumption, wherein the boiler body heat consumption and the flue gas heat consumption are non-ideal heat consumption, so the ratio of the steam turbine heat consumption to the apparent dynamic heat release can be defined as the effective heat release rate.

[0115] The calculation method of the apparent dynamic heat release is:

[0116] Q U，the = Q T，the - Q R，the

[0117] In the formula: Q U，the is the apparent dynamic heat release, Q T，the is the apparent total heat storage, and Q R，the is the apparent dynamic heat storage surplus.

[0118] As a further improvement of the above scheme, the effective heat release rate is the ratio of the steam turbine heat consumption to the apparent dynamic heat release. Through the effective heat release rate, the non-ideal heat consumption caused by system air leakage or heat exchange barrier during operation can also be measured to a certain extent, which has guiding significance for further improving the utilization efficiency of the apparent dynamic heat release.

[0119] The calculation method of the effective heat release rate is:

[0120]

[0121] In the formula: η v is the effective heat release rate, Q t is the steam turbine heat consumption, and Q U，the is the apparent total heat storage.

[0122] The calculation method of the steam turbine heat consumption is:

[0123] Q 热耗 = D0×h0-D fw ×h fw + D rh ×h rh - D rc ×h rc - D rcw ×h rcw - Drhw ×h rhw

[0124] In the formula: Q 热耗 For steam turbine heat consumption, GJ / h; D0 and h0 are the main steam flow rate and enthalpy, t / h and kJ / kg, respectively; D fw h fw Main feedwater flow rate, enthalpy, t / h, kJ / kg; D rh h rh For reheat steam flow rate and enthalpy, t / h, kJ / kg; D rc h rc For high-pressure cylinder exhaust steam flow rate and enthalpy, t / h, kJ / kg; D rw h rw For the reheater desuperheating water flow rate and enthalpy, t / h, kJ / kg; D rcw h rcw The flow rate and enthalpy of the superheater desuperheating water are given in t / h and kJ / kg.

[0125] Q t =∫0 t Q 热耗 dt

[0126] In the formula: Q t The heat consumption of the steam turbine is expressed in GJ.

[0127] As a further improvement to the above scheme, the effective apparent dynamic heat storage margin is the product of the apparent dynamic heat storage margin and the effective heat release rate, that is, the apparent dynamic heat storage margin that actually plays a role in the heat consumption of the steam turbine. The calculation method for the effective apparent dynamic heat storage margin is as follows:

[0128] Q R，v =Q R，th e×η v

[0129] In the formula: Q R，v To effectively measure the apparent dynamic heat storage margin, Q R，the η represents the apparent dynamic heat storage margin. v For effective heat release rate.

[0130] Example 1

[0131] Record all measured data during a near-zero ultra-long-term deep peak shaving operation of a 300MW subcritical CFB unit, and categorize them according to... Figure 2 The method shown performs state classification, and the measured data is input into the calculation method described in this invention to calculate the state classification respectively. Figure 1 By displaying the heat storage and release of each part, and plotting the calculated apparent dynamic heat storage margin and apparent dynamic heat release, the dynamic and intuitive quantification of the boiler's heat storage and release during near-zero ultra-long-term deep peak shaving can be achieved.

[0132] Implementation steps:

[0133] I. Two key parameters from the measured data are selected as examples: the average temperature of the high-parameter thermal storage bed material carrier is 814℃, and the high-parameter thermal storage load is 122MW; the average temperature of the safe and stable thermal bed material carrier is 608℃, and the safe and stable thermal load is 5.54MW. Their trend curves with the near-zero ultra-long depth peak-shaving process are shown below. Figure 3 As shown.

[0134] II. Calculation of apparent dynamic heat storage margin:

[0135] Q R，the =Q R，w +Q R，m +Q R，a +Q R，c +Q R，f

[0136] In the formula: Q R，the Q represents the apparent dynamic heat storage margin. R，w Q represents the heat storage capacity of the soft drink. R，m Q is the heat storage margin for the metal wall. R，a Q is the heat storage margin for the bed material carrier. R，c Q is the heat storage margin for the casting layer. R，f This is the residual heat storage capacity of the flue gas.

[0137] The calculated trend of apparent dynamic heat storage margin changing over time is as follows: Figure 4 show.

[0138] III. Perform apparent dynamic heat release calculation:

[0139] Q U，the =Q T，the -Q R，the

[0140] In the formula: Q U，the To show the dynamic release of heat, Q T，the Q represents the apparent heat storage. R，the This refers to the apparent dynamic heat storage margin.

[0141] The calculated trend of apparent dynamic heat release over time is as follows: Figure 5 show.

[0142] Example 2

[0143] Record all measured data from another near-zero ultra-long-term deep peak shaving operation of a 300MW subcritical CFB unit, and categorize them according to... Figure 2 The method shown performs state classification, and the measured data is input into the calculation method described in this invention to calculate the state classification respectively. Figure 1The display of each part of the heat storage and release, the calculated apparent dynamic heat storage and apparent dynamic heat release are plotted, so as to realize the dynamic and intuitive quantification of the boiler heat storage and release in the near zero super-long deep peak regulation process.

[0144] Implementation steps:

[0145] I. Select two main parameters of the measured data for example: the high parameter heat storage state main steam temperature is 542℃, and the high parameter heat storage state load is 122.39MW; the safe and stable heat state main steam temperature is 466.42℃, and the safe and stable heat state load is 6.14Mv. The variation trend curve thereof with the near zero super-long deep peak regulation process is as shown in Figure 6

[0146] II. Calculate the apparent dynamic heat storage:

[0147] Q R，the = Q R，w + Q R，m + Q R，a + Q R，c + Q R，f

[0148] In the formula: Q R，the is the apparent dynamic heat storage, Q R，w is the steam-water heat storage, Q R，m is the metal wall heat storage, Q R，a is the bed material carrier heat storage, Q R，c is the cast layer heat storage, and Q R，f is the flue gas heat storage.

[0149] The variation trend of the calculated apparent dynamic heat storage with time is as shown in Figure 7

[0150] III. Calculate the apparent dynamic heat release:

[0151] Q U，the = Q T，the - Q R，the

[0152] In the formula: Q U，the is the apparent dynamic heat release, Q T，the is the apparent heat storage total, and Q R，the is the apparent dynamic heat storage.

[0153] The variation trend of the calculated apparent dynamic heat release with time is as shown in Figure 8

[0154] ​​​The preferred embodiments of the present application have been described in detail above, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application, and all such changes are intended to be included within the scope of the present application.

Claims

1. A dynamic theoretical prediction method for heat storage amount in a near-zero depth peak regulation process of a CFB unit, characterized in that: According to the state of the subcritical CFB generator set in the process of near-zero super-long deep load regulation, three state parameters are divided into high parameter heat storage state, process heat release state and safe and stable heat state; Through the calculation of the apparent heat storage total amount, the apparent dynamic heat storage surplus and the apparent dynamic heat release amount and the effective apparent dynamic heat storage surplus obtained by the difference of the three state parameters, the dynamic theoretical prediction of the boiler heat storage amount in the process of near-zero super-long deep load regulation is realized; The high parameter heat storage state is the initial state in the process of near-zero super-long deep load regulation, and stopping feeding and air supply is taken as the symbol; the process heat release state is the process state in the process of near-zero super-long deep load regulation, and near-zero load operation is taken as the symbol; The safe and stable heat state is the state at the end of the near-zero super-long deep load regulation, and the bed temperature and the steam temperature are taken as the main safety fire boundary; The apparent heat storage total amount is the theoretical heat storage total amount obtained by the difference between the high parameter heat storage state and the safe and stable heat state; The calculation method of the apparent heat storage total amount is: wherein: is the total amount of apparent heat storage, is the total amount of steam-water heat storage, is the total amount of metal wall heat storage, is the total amount of bed material carrier heat storage, is the total amount of cast layer heat storage, is the total amount of flue gas heat storage; The apparent dynamic heat storage surplus is the real-time heat storage surplus obtained by the difference between the process heat release state and the safe and stable heat state; the calculation method of the apparent dynamic heat storage surplus is: wherein: available dynamic storage, steam-water storage, metal wall storage, bed material carrier storage, cast layer storage, flue gas storage; The apparent dynamic heat release amount is the difference between the apparent heat storage total amount and the apparent dynamic heat storage surplus, and the apparent dynamic heat release amount is mainly composed of three parts of heat consumption, which are the steam turbine heat consumption, the boiler body heat consumption and the flue gas heat consumption; the calculation method of the apparent dynamic heat release amount is: In the formula: is the apparent dynamic heat release amount, is the apparent total heat storage amount, is the apparent dynamic heat storage surplus.

2. The method according to claim 1, wherein the method is characterized by: The calculation method of the steam-water heat storage total amount is: In the formula: GJ is the total amount of steam and water storage; , , respectively, high parameter storage state steam and water density, high parameter storage state steam and water enthalpy, safe and stable heat state steam and water density, safe and stable heat state steam and water enthalpy, kg / m 3 , kJ / kg, kg / m 3 , kJ / kg; , respectively, high parameter storage state steam and water volume, m 3 ; The calculation method of the metal wall heat storage total amount is: wherein: GJ is the total amount of heat stored in the metal wall; Cp is the specific heat capacity of the metal wall, kJ / (kg·K); m is the mass of the metal wall, kg; , Tm,high is the temperature of the metal wall in the high- parameter heat storage state, °C; and Tm,sec is the temperature of the metal wall in the safe warm state, °C. The calculation method of the bed material carrier heat storage total amount is: In the formula: is the total amount of heat storage of the bed material carrier, is the specific heat capacity of the bed material carrier, kJ / (kg·K); is the mass of the bed material carrier, kg; is the average temperature of the high-parameter heat storage bed material carrier, ℃; is the average temperature of the safe and stable heat bed material carrier, ℃; The calculation method of the cast layer heat storage total amount is: In the formula: GJ is the total amount of heat storage of the casting layer; Cp is the specific heat capacity of the casting layer, kJ / (kg·K); M is the mass of the casting layer, kg; T is the average temperature of the high-parameter heat storage state casting layer, ℃; T is the average temperature of the safe and stable heat state casting layer, ℃; The calculation method of the flue gas heat storage total amount is: In the formula: GJ is the total amount of flue gas storage; ρh is the average density of high parameter heat storage state flue gas, kg / m 3 ; wh is the average enthalpy of high parameter heat storage state flue gas, kJ / kg; Gh is the amount of high parameter heat storage state flue gas, m 3 ; ρs is the average density of safe and stable heat state flue gas, kg / m 3 ; ws is the average enthalpy of safe and stable heat state flue gas, kJ / kg; Gs is the amount of safe and stable heat state flue gas, m 3 .

3. The method of claim 1, wherein the method is characterized by: The calculation method of the steam-water heat storage surplus is: wherein: GJ is the steam-water storage excess amount; , , respectively are the process heat-releasing state steam-water density, the process heat-releasing state steam-water enthalpy, the safe and stable heat state steam-water density, the safe and stable heat state steam-water enthalpy, kg / m 3 , kJ / kg, kg / m 3 , kJ / kg; , respectively are the process heat-releasing state steam-water volume, m 3 ; The calculation method of the metal wall heat storage surplus is: wherein: GJ is the metal wall heat storage margin; Cp is the metal wall specific heat capacity, kJ / (kg·K); M is the metal wall mass, kg; , Tm is the process exothermic metal wall temperature, °C; and Tm is the process exothermic metal wall temperature, °C; and The calculation method of the bed material carrier heat storage surplus is: wherein: GJ is the bed material inventory, GJ; T is the average bed material inventory temperature, °C; T is the average bed material inventory temperature, °C; The calculation method of the cast layer heat storage surplus is: In the formula: GJ is the heat storage allowance of the casting layer; is the average temperature of the casting layer in the process heat release state, ℃; is the average temperature of the casting layer in the safe and stable heat state, ℃; The calculation method of the flue gas heat storage surplus is: wherein: GJ is the flue gas storage excess, GJ; GJ is the high parameter storage state flue gas average density, kg / m 3 ; GJ is the high parameter storage state flue gas average enthalpy, kJ / kg; GJ is the high parameter storage state flue gas amount, m 3 ; GJ is the safe and stable heating state flue gas average density, kg / m 3 ; GJ is the safe and stable heating state flue gas average enthalpy, kJ / kg; GJ is the safe and stable heating state flue gas amount, m 3 .

4. The method of claim 1, wherein the method is characterized by: The ratio of the steam turbine heat consumption to the apparent dynamic heat release amount is the effective heat release rate; The calculation method of the effective heat release rate is: wherein: is the effective heat release rate, is the heat rate of the steam turbine, is the apparent total heat storage; The calculation method of the steam turbine heat consumption is: wherein: is the heat rate of the steam turbine, GJ / h; , is the main steam flow, enthalpy, t / h, kJ / kg; , is the main feed water flow, enthalpy, t / h, kJ / kg; , is the reheat steam flow, enthalpy, t / h, kJ / kg; , is the high pressure cylinder exhaust flow, enthalpy, t / h, kJ / kg; is the desuperheating water flow, enthalpy, t / h, kJ / kg, of the reheater; is the desuperheating water flow, enthalpy, t / h, kJ / kg, of the superheater. In the formula: GJ is the heat rate of the steam turbine.

5. The method of claim 4, wherein the method is characterized by: The effective apparent dynamic heat storage surplus is the product of the apparent dynamic heat storage surplus and the effective heat release rate, that is, the apparent dynamic heat storage surplus actually playing a role in the steam turbine heat consumption; the calculation method of the effective apparent dynamic heat storage surplus is: wherein: is the effective dynamic available heat surplus, is the dynamic available heat surplus, is the effective heat release rate.

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