A Thermal Calculation Method, System, Equipment and Medium for Variable Working Conditions during the Vaporization of the Economizer of a Waste Heat Boiler

Abstract

The present invention belongs to the field of gas-steam combined cycle units, and discloses a time-varying condition thermal calculation method, system, device and medium for economizer vaporization in a waste heat boiler. The method includes: calculating a first water-side heat transfer value, a second water-side heat transfer value and a first deviation value of the economizer based on relevant parameters of the economizer; if the first deviation value is less than the first residual standard, determining whether the enthalpy value at the water-side outlet of the economizer is less than the enthalpy value of saturated water on the water side; if the enthalpy value at the water-side outlet of the economizer is greater than the enthalpy value of saturated water on the water side, dividing the economizer into a first part and a second part; calculating a third water-side heat transfer value, a fourth water-side heat transfer value and a second deviation value of the second part; and if the second deviation value is less than the second residual standard, outputting key data under the time-varying conditions of the economizer. By judging the state of the working medium at the water-side outlet of the economizer, the present invention can more accurately calculate the time-varying condition thermal performance during vaporization at the economizer outlet, and improve the efficiency of the waste heat boiler and even the combined cycle unit.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-steam combined cycle units, and in particular to a thermal calculation method, system, equipment and medium for time-varying working conditions of a waste heat boiler economizer during vaporization. Background Art

[0002] In recent years, in order to cope with the severe challenges posed by the large-scale access of intermittent and fluctuating renewable energy to the safe and stable operation of the power grid, the installed capacity of efficient and flexible gas-fired generators has continued to grow. Since combined cycle units usually undertake peak load regulation tasks and gas turbines are extremely sensitive to changes in environmental parameters, combined cycle units are often operated under variable conditions. As the hub connecting gas turbines and steam turbines, the accurate calculation of the thermal performance of waste heat boilers under variable conditions is very important for analyzing and diagnosing the overall performance of combined cycle units under variable conditions.

[0003] The waste heat boiler is generally composed of multiple economizers, evaporators and superheaters connected in series. The overall variable operating condition calculation of the waste heat boiler is calculated by independently calculating the variable operating conditions of multiple components and then solving them jointly. In general, the working conditions of the economizer, evaporator and superheater inlet and outlet are usually determined. However, when the deviates far from the design operating conditions, the water side outlet of the last economizer is easily heated to wet saturated steam and contains a small amount of steam. At this time, the traditional variable operating condition theory of the waste heat boiler economizer will no longer be applicable, which may cause distortion of the calculation results and make it impossible to accurately calculate the overall variable operating condition thermal performance of the waste heat boiler. Summary of the invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a thermal calculation method and system for time-varying operating conditions of a waste heat boiler economizer vaporization to solve the problem that when the actual operation of the waste heat boiler deviates greatly from the design operating conditions, the water side outlet of the last economizer vaporizes, and the traditional economizer variable operating condition calculation method cannot accurately calculate the overall variable operating condition thermal performance of the waste heat boiler.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for calculating the thermal power of a waste heat boiler economizer under time-varying vaporization conditions, comprising:

[0008] Get economizer related parameters;

[0009] Based on the economizer related parameters, a first water-side heat exchange value, a second water-side heat exchange value, and a first deviation between the first water-side heat exchange value and the second water-side heat exchange value of the economizer are calculated;

[0010] If the first deviation value is less than the first residual standard, determine whether the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side;

[0011] If the enthalpy value at the water side outlet of the economizer is greater than the enthalpy value of saturated water on the water side, divide the economizer into a first part and a second part;

[0012] Calculate the third heat transfer value on the water side, the fourth heat transfer value on the water side, and the second deviation value between the third heat transfer value on the water side and the fourth heat transfer value on the water side of the second part;

[0013] If the second deviation value is less than the second residual standard, output the key data of the economizer under off-design conditions.

[0014] As a preferred solution of a method for off-design thermal calculation of an economizer during vaporization in a waste heat boiler according to the present invention, wherein: based on the relevant parameters of the economizer, calculate the first heat transfer value on the water side and the second heat transfer value on the water side of the economizer, including:

[0015] Based on the design conditions of the economizer and the relevant parameters during off-design conditions, calculate the water side pressure drop, the product of the first overall heat transfer coefficient and the total heat transfer area, and the first heat transfer value on the water side of the economizer during off-design conditions;

[0016] Based on the water side pressure drop, the product of the first overall heat transfer coefficient and the total heat transfer area, and the first heat transfer value on the water side, combined with the input parameters during off-design conditions of the economizer, obtain the second heat transfer value on the water side of the economizer during off-design conditions.

[0017] As a preferred solution of a method for off-design thermal calculation of an economizer during vaporization in a waste heat boiler according to the present invention, wherein: the first deviation value includes:

[0018] If the first deviation value is less than the first residual standard, then output the water side outlet pressure, temperature and enthalpy values and the inlet temperature of the flue gas side of the economizer during off-design conditions;

[0019] If the first deviation value is not less than the first residual standard, update the first heat transfer value on the water side through the Newton-Raphson algorithm, iteratively calculate and compare the first deviation value with the first residual standard until the first deviation is less than the first residual standard.

[0020] As a preferred solution of a method for off-design thermal calculation of an economizer during vaporization in a waste heat boiler according to the present invention, wherein: determining whether the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side includes:

[0021] If the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side, the calculation ends, and the key data of the economizer under off-design conditions are output;

[0022] If the enthalpy value at the water side outlet of the economizer is not less than the enthalpy value of saturated water on the water side, the economizer is divided into a first part and a second part;

[0023] The first part is the process of heating subcooled water to saturated water, and the second part is the process of heating saturated water to wet saturated steam.

[0024] As a preferred scheme of a variable working condition thermal calculation method for the vaporization of an economizer in a waste heat boiler according to the present invention, wherein: calculating the third heat transfer amount value and the fourth heat transfer amount value on the water side of the second part includes:

[0025] Calculating the inlet flue gas temperature, outlet saturated water temperature and heat transfer ratio of the first part;

[0026] Calculating the third heat transfer amount value on the water side of the second part;

[0027] Based on the inlet flue gas temperature, outlet saturated water temperature, heat transfer ratio of the first part and the third heat transfer amount value on the water side of the second part, the fourth heat transfer amount value on the water side is obtained.

[0028] As a preferred scheme of a variable working condition thermal calculation method for the vaporization of an economizer in a waste heat boiler according to the present invention, wherein: if the second deviation value is less than the second residual standard, output the key data under the variable working condition of the economizer, including:

[0029] If the second deviation value is less than the second residual standard, then output the water side outlet pressure, temperature and enthalpy value and the inlet temperature on the flue gas side under the variable working condition of the economizer;

[0030] If the second deviation value is not less than the second residual standard, update the third heat transfer amount value on the water side through the Newton-Raphson algorithm, and iteratively calculate and compare the second deviation value with the second residual standard until the second deviation is less than the second residual standard.

[0031] As a preferred scheme of a variable working condition thermal calculation method for the vaporization of an economizer in a waste heat boiler according to the present invention, wherein: the economizer related parameters include the economizer design working condition parameters and variable working condition parameters;

[0032] The design working condition parameters include the product of the second total heat transfer coefficient and the total heat transfer area, the heat dissipation coefficient, the inlet and outlet pressures, temperatures and flow rates on the water side, and the inlet and outlet compositions, temperatures and flow rates on the flue gas side;

[0033] The variable working condition parameters include the water side inlet pressure, temperature and flow rate, and the flue gas side outlet composition, temperature and flow rate.

[0034] Another object of the present invention is to provide a variable working condition thermal calculation system for the vaporization of an economizer in a waste heat boiler.

[0035] To solve the above technical problems, the present invention provides the following technical solutions: A variable-condition thermal calculation system for economizer vaporization in a waste heat boiler, comprising:

[0036] A data acquisition module for acquiring relevant parameters of the economizer;

[0037] A first calculation module for calculating a first heat transfer value on the water side, a second heat transfer value on the water side, and a first deviation value between the first heat transfer value on the water side and the second heat transfer value on the water side based on the relevant parameters of the economizer;

[0038] A first judgment module for judging whether the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side if the first deviation value is less than the first residual standard; if the enthalpy value at the water side outlet of the economizer is greater than the enthalpy value of saturated water on the water side, the economizer is divided into a first part and a second part;

[0039] A second calculation module for calculating a third heat transfer value on the water side, a fourth heat transfer value on the water side, and a second deviation value between the third heat transfer value on the water side and the fourth heat transfer value on the water side of the second part;

[0040] A second judgment module for outputting key data under variable conditions of the economizer if the second deviation value is less than the second residual standard.

[0041] The present invention provides a computer device, comprising a memory and a processor, the memory is used for storing computer-executable instructions, and the processor is used for executing the computer-executable instructions, and when the computer-executable instructions are executed by the processor, the steps of the variable-condition thermal calculation method for economizer vaporization in a waste heat boiler are realized.

[0042] The present invention provides a computer-readable storage medium, which stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the steps of the variable-condition thermal calculation method for economizer vaporization in a waste heat boiler are realized.

[0043] Advantages of the present invention: The present invention solves the problem of distorted results in the traditional calculation method when vaporization occurs at the outlet of the economizer. In the case of frequent off-design operation of a gas-steam combined cycle unit, when vaporization occurs at the water-side outlet of the last-stage economizer of the waste heat boiler, the parameters such as the average logarithmic temperature difference, heat transfer amount, enthalpy value at the water-side outlet, and flue gas inlet temperature calculated by the traditional method have large deviations. The present invention judges the state of the working medium at the water-side outlet of the economizer, divides the economizer under the vaporization condition into two parts for calculation, and makes the calculation process more in line with the actual heat transfer process. Compared with the traditional method, the enthalpy value at the water-side outlet and the flue gas-side inlet temperature calculated by the present invention are closer to the true values, can more accurately calculate the off-design thermal performance when vaporization occurs at the economizer outlet, provides a calculation basis for the safe and efficient operation of the waste heat boiler and even the combined cycle unit under off-design conditions, helps to optimize the unit operation parameters, improve the energy utilization efficiency, and enhance the adaptability and stability of the combined cycle unit under complex conditions such as peak shaving. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a schematic diagram of the general process logic for the off-design thermal calculation method of the economizer vaporization in a waste heat boiler according to an embodiment of the present invention.

[0046] Figure 2 It is a schematic diagram of the overall process logic of the traditional method for the off-design thermal calculation method of the economizer vaporization in a waste heat boiler according to an embodiment of the present invention.

[0047] Figure 3 It is a schematic diagram of the overall process logic of the new method for the off-design thermal calculation method of the economizer vaporization in a waste heat boiler according to an embodiment of the present invention.

[0048] Figure 4 It is a schematic diagram of the temperature change of the non-vaporization condition at the economizer outlet in the off-design thermal calculation method of the economizer vaporization in a waste heat boiler according to an embodiment of the present invention.

[0049] Figure 5 It is a schematic diagram of the temperature change of the vaporization condition at the economizer outlet in the off-design thermal calculation method of the economizer vaporization in a waste heat boiler according to an embodiment of the present invention.

[0050] In the figure: Figure 2 It is a flow chart of the traditional method for the off-design thermal calculation of the economizer vaporization in a waste heat boiler, Figure 3The figure is a flow chart of the thermal calculation method for the economizer of a waste heat boiler during the variable working conditions of vaporization of the new method. Based on Figure 2 After outputting the water-side outlet pressure, temperature, enthalpy value under variable working conditions of the economizer and the inlet temperature of the flue gas side, the present invention further judges the economizer and re-outputs the water-side outlet pressure, temperature, enthalpy value under variable working conditions of the economizer and the inlet temperature of the flue gas side. Specific embodiments

[0051] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0052] Example 1, referring to Figures 1 - 5 This is an embodiment of the present invention, which provides a thermal calculation method for the economizer of a waste heat boiler during the variable working conditions of vaporization, including: S100: Obtain the relevant parameters of the economizer;

[0053] Preferably, the relevant parameters of the economizer include the design working condition parameters and variable working condition parameters of the economizer;

[0054] In the embodiment of the present invention, the design working condition parameters include the product of the second overall heat transfer coefficient and the total heat transfer area, the heat dissipation coefficient, the inlet and outlet pressures, temperatures and flows on the water side, and the inlet and outlet compositions, temperatures and flows on the flue gas side, etc.;

[0055] In the embodiment of the present invention, the variable working condition parameters include the inlet pressure, temperature and flow on the water side, the outlet composition, temperature and flow on the flue gas side, each residual standard, and the initial value of the heat transfer amount of the economizer etc.

[0056] S102: Based on the relevant parameters of the economizer, calculate the first water-side heat transfer amount value, the second water-side heat transfer amount value, and the first deviation value between the first water-side heat transfer amount value and the second water-side heat transfer amount value;

[0057] Preferably, based on the relevant parameters of the economizer under the design working condition and variable working conditions, calculate the water-side pressure drop, the product of the first overall heat transfer coefficient and the total heat transfer area, and the first water-side heat transfer amount value of the economizer under variable working conditions;

[0058] In the embodiment of the present invention, the formula for calculating the water-side pressure drop of the economizer under variable working conditions is:

[0059] ,

[0060] Wherein, is the water-side pressure drop of the economizer under off-design conditions, is the water-side inlet flow rate of the economizer under off-design conditions, is the water-side inlet flow rate of the economizer under design conditions, is the water-side pressure drop of the economizer under design conditions.

[0061] In the embodiment of the present invention, the calculation formula for the water-side pressure drop of the economizer under design conditions is:

[0062] ,

[0063] wherein, is the water-side pressure drop of the economizer under design conditions, is the water-side inlet pressure of the economizer under design conditions, is the water-side outlet pressure of the economizer under design conditions.

[0064] In the embodiment of the present invention, the calculation formula for the water-side outlet pressure of the economizer under off-design conditions is:

[0065] ,

[0066] wherein, is the water-side inlet pressure of the economizer under off-design conditions, is the water-side inlet pressure of the economizer under off-design conditions, is the water-side pressure drop of the economizer under off-design conditions.

[0067] In the embodiment of the present invention, the calculation formula for the product of the first overall heat transfer coefficient and the total heat transfer area of the economizer under off-design conditions is:

[0068] ,

[0069] wherein, is the product of the first overall heat transfer coefficient and the total heat transfer area of the economizer under off-design conditions, is the product of the second overall heat transfer coefficient and the total heat transfer area of the economizer under design conditions, is the flue gas-side outlet flow rate of the economizer under off-design conditions, is the flue gas-side outlet flow rate of the economizer under design conditions.

[0070] It should be noted that the water-side inlet and outlet flow rates of the economizer are the same, and the inlet and outlet components and flow rates of the flue gas side are the same.

[0071] In the embodiment of the present invention, the calculation formula for the first water-side heat transfer value of the economizer under off-design conditions is:

[0072] ,

[0073] wherein, is the first heat transfer value on the water side under off-design conditions of the economizer, is the heat transfer value on the water side under design conditions of the economizer, is the water side inlet flow rate under off-design conditions of the economizer, is the water side inlet flow rate under design conditions of the economizer.

[0074] In the embodiment of the present invention, the calculation formula for the heat transfer value on the water side under design conditions of the economizer is:

[0075] ,

[0076] wherein, is the heat transfer value on the water side under design conditions of the economizer, and are the water side outlet pressure and temperature under design conditions of the economizer, and are the water side inlet pressure and temperature under design conditions of the economizer, is the water side inlet flow rate under design conditions of the economizer.

[0077] Preferably, based on the product of the water side pressure drop, the first overall heat transfer coefficient and the total heat transfer area, and the first heat transfer value on the water side, combined with the input parameters under off-design conditions of the economizer, the second heat transfer value on the water side under off-design conditions of the economizer is obtained;

[0078] In the embodiment of the present invention, the input parameters under off-design conditions of the economizer include the flue gas side inlet temperature, the water side outlet temperature and the logarithmic mean temperature difference.

[0079] In the embodiment of the present invention, the calculation formula for the second heat transfer value on the water side under off-design conditions of the economizer is:

[0080] ,

[0081] wherein, is the second heat transfer value on the water side under off-design conditions of the economizer, is the product of the first overall heat transfer coefficient and the total heat transfer area under off-design conditions of the economizer, is the logarithmic mean temperature difference under off-design conditions of the economizer.

[0082] In the embodiment of the present invention, the calculation formula for the logarithmic mean temperature difference under off-design conditions of the economizer is:

[0083] ,

[0084] ,

[0085] ,

[0086] ,

[0087] ,

[0088] Among them, is the logarithmic mean temperature difference during off-design conditions of the economizer, is the inlet temperature on the flue gas side of the economizer, is the outlet temperature on the flue gas side of the economizer, is the outlet temperature on the water side of the economizer, is the inlet temperature on the water side of the economizer, is the inlet flow rate on the water side during off-design conditions of the economizer, is the outlet pressure on the water side of the economizer, is the outlet enthalpy value on the water side during off-design conditions of the economizer, is the inlet pressure on the water side of the economizer, is the first heat transfer amount value on the water side during off-design conditions of the economizer, is the outlet composition on the flue gas side of the economizer, is the inlet enthalpy value on the flue gas side of the economizer, is the outlet flow rate on the flue gas side during off-design conditions of the economizer, is the heat dissipation coefficient of the economizer.

[0089] Preferably, the calculation formula for the first deviation value is:

[0090] ,

[0091] Among them, is the first deviation value, is the first heat transfer amount value on the water side during off-design conditions of the economizer, is the second heat transfer amount value on the water side during off-design conditions of the economizer.

[0092] S104: If the first deviation value is less than the first residual standard, determine whether the outlet enthalpy value on the water side of the economizer is less than the saturated water enthalpy value on the water side; if the outlet enthalpy value on the water side of the economizer is greater than the saturated water enthalpy value on the water side, divide the economizer into a first part and a second part;

[0093] Preferably, if the first deviation value is less than the first residual standard, output the outlet pressure, temperature and enthalpy value on the water side and the inlet temperature on the flue gas side during off-design conditions of the economizer;

[0094] Preferably, if the first deviation value is not less than the first residual standard, update the first heat transfer amount value on the water side through the Newton-Raphson algorithm, iteratively calculate and compare the first deviation value with the first residual standard until the first deviation is less than the first residual standard.

[0095] In an alternative embodiment, the first residual standard can be set to , , .

[0096] Preferably, determining whether the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side includes:

[0097] If the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side, the calculation ends, and the key data under off-design conditions of the economizer is output; the key data includes the water side outlet pressure, temperature and enthalpy value when the economizer is under off-design conditions and the inlet temperature on the flue gas side;

[0098] In the embodiment of the present invention, the calculation formulas for the enthalpy value at the water side outlet of the economizer and the enthalpy value of saturated water on the water side are:

[0099] ,

[0100] ,

[0101] wherein, is the enthalpy value at the water side outlet when the economizer is under off-design conditions, is the enthalpy value of saturated water at the water side outlet, is the water side outlet temperature when the economizer is under off-design conditions, is the water side outlet pressure when the economizer is under off-design conditions.

[0102] If the enthalpy value at the water side outlet of the economizer is not less than the enthalpy value of saturated water on the water side, the economizer is divided into a first part and a second part;

[0103] The first part is the process of heating subcooled water to saturated water, and the second part is the process of heating saturated water to wet saturated steam.

[0104] S106: Calculate the third water side heat transfer amount value, the fourth water side heat transfer amount value of the second part, and the second deviation value between the third water side heat transfer amount value and the fourth water side heat transfer amount value;

[0105] Preferably, calculate the inlet flue gas temperature, the outlet saturated water temperature and the heat transfer ratio of the first part;

[0106] In the embodiment of the present invention, the calculation formulas for the inlet flue gas temperature, the outlet saturated water temperature and the heat transfer ratio of the first part are:

[0107] ,

[0108] ,

[0109] ,

[0110] ,

[0111] ,

[0112] Among them, is the inlet flue gas temperature of the first part of the economizer, is the outlet composition on the flue gas side of the economizer, is the enthalpy value at the inlet on the flue gas side of the first part of the economizer, is the outlet flow rate on the flue gas side of the economizer under off-design conditions, is the outlet temperature on the flue gas side of the economizer, is the enthalpy value of saturated water at the outlet on the water side of the economizer, is the inlet pressure on the water side of the economizer, is the inlet temperature on the water side of the economizer, is the inlet flow rate on the water side of the economizer under off-design conditions, is the heat dissipation coefficient of the economizer, is the outlet temperature on the water side of the first part of the economizer, is the outlet pressure on the water side of the economizer, is the heat transfer ratio of the first part of the economizer, is the product of the overall heat transfer coefficient and the total heat transfer area of the first part of the economizer under off-design conditions, is the logarithmic mean temperature difference of the first part of the economizer.

[0113] Preferably, calculate the third heat transfer value on the water side of the second part;

[0114] In the embodiment of the present invention, the third heat transfer value on the water side is equal to the initial heat transfer value of the economizer .

[0115] Preferably, based on the inlet flue gas temperature, outlet saturated water temperature, heat transfer ratio of the first part, and the third heat transfer value on the water side of the second part, obtain the fourth heat transfer value on the water side;

[0116] In the embodiment of the present invention, the calculation formula for the fourth heat transfer value on the water side is:

[0117] ,

[0118] Among them, is the fourth heat transfer value on the water side of the economizer under off-design conditions, is the heat transfer ratio of the first part, is the product of the overall heat transfer coefficient and the total heat transfer area of the first part of the economizer under off-design conditions, is the logarithmic mean temperature difference of the second part of the economizer.

[0119] Preferably, the calculation formula for the second deviation value is:

[0120] ,

[0121] Among them, is the second deviation value, is the third heat transfer value on the water side under off-design conditions of the economizer, is the fourth heat transfer value on the water side under off-design conditions of the economizer.

[0122] S108: If the second deviation value is less than the second residual standard, output the key data under off-design conditions of the economizer;

[0123] Preferably, if the second deviation value is less than the second residual standard, output the outlet pressure, temperature and enthalpy value on the water side and the inlet temperature on the flue gas side under off-design conditions of the economizer;

[0124] Preferably, if the second deviation value is not less than the second residual standard, update the third heat transfer value on the water side through the Newton-Raphson algorithm, iteratively calculate and compare the second deviation value with the second residual standard until the second deviation is less than the second residual standard.

[0125] In an alternative embodiment, the second residual standard can be set to , , .

[0126] As Figure 4 shown, when the economizer outlet is not vaporized, the temperature change trends of the flue gas and water are relatively smooth, and the traditional off-design calculation method can meet the requirements.

[0127] As Figure 5 shown, when the economizer outlet is vaporized, from the start of vaporization to the end, the temperature of the water will remain constant.

[0128] Therefore, if the traditional method is used for calculation, it may cause the result to be distorted. Therefore, the present invention considers this situation and divides the economizer into two parts for calculation. One part is to heat the subcooled water to saturated water, and the other part is to heat the saturated water to wet saturated steam.

[0129] Example 2, referring to Table 1 and Figure 4 and Figure 5 , based on the previous embodiment, this embodiment provides an application case of a variable condition thermal calculation method for the economizer of a waste heat boiler during vaporization to illustrate the feasibility and beneficial effects of our solution.

[0130] From Figure 4 and Figure 5 it can be seen that if the traditional method is used for calculation, it will cause a relatively large average logarithmic temperature difference of the economizer, resulting in an excessive heat transfer amount, and thus an excessive outlet enthalpy value on the water side and an excessive inlet temperature of the flue gas. The calculation method of the present invention is closer to the actual heat transfer process, so the variable condition calculation during vaporization of the economizer outlet can be carried out more accurately.

[0131] Taking the performance assessment condition of the high-pressure final-stage economizer of a non-supplementary-firing triple-pressure reheat waste heat boiler in a combined cycle unit as the design condition, and taking the vaporization condition at the economizer outlet in a certain province as the off-design condition, calculations are carried out using the traditional method and the method proposed in the present invention respectively. The calculation results are shown in Table 1.

[0132] Table 1 Comparison results of off-design condition calculation results between the method of the present invention and the traditional method

[0133] ,

[0134] As can be seen from Table 1, under the condition of the same water-side outlet pressure and temperature, the enthalpy value at the water-side outlet calculated by the traditional method is 1355.60 kJ / kg, and the flue gas-side inlet temperature is 309.32 °C; while the enthalpy value at the water-side outlet calculated by the present invention is 1337.12 kJ / kg, and the flue gas-side inlet temperature is 307.89 °C.

[0135] The enthalpy value at the water-side outlet calculated by the present invention is 18.48 kJ / kg lower than that of the traditional method, and the flue gas-side inlet temperature is 1.43 °C lower. This shows that the present invention can more accurately reflect the true thermodynamic condition during the vaporization at the economizer outlet, avoid misjudgment of the equipment operation state due to calculation deviation, and provide more reliable technical support for the efficient and stable operation of gas-steam combined cycle units.

[0136] Example 3, which is the third example of the present invention, is different from the previous two examples in that:

[0137] If the said function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. And the aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0138] The logic and / or steps represented in the flowchart or otherwise described herein can, for example, be considered as a definitional sequence of executable instructions for implementing logical functions, which can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with the instruction execution system, apparatus, or device.

[0139] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or otherwise processing as appropriate, and then stored in a computer memory.

[0140] It should be understood that the various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), and the like.

[0141] Embodiment 4 is the fourth embodiment of the present invention, which provides a variable-condition thermal calculation system for a waste heat boiler economizer during vaporization, including:

[0142] A data acquisition module for acquiring economizer-related parameters;

[0143] A first calculation module for calculating a first heat transfer value on the water side, a second heat transfer value on the water side, and a first deviation value between the first heat transfer value on the water side and the second heat transfer value on the water side based on the economizer-related parameters;

[0144] The first judgment module is used to judge whether the enthalpy value at the water side outlet of the economizer is less than the enthalpy value of saturated water on the water side if the first deviation value is less than the first residual standard; if the enthalpy value at the water side outlet of the economizer is greater than the enthalpy value of saturated water on the water side, the economizer is divided into a first part and a second part;

[0145] The second calculation module is used to calculate the third water side heat exchange value, the fourth water side heat exchange value of the second part, and the second deviation value between the third water side heat exchange value and the fourth water side heat exchange value;

[0146] The second judgment module is used to output the key data under the off-design conditions of the economizer if the second deviation value is less than the second residual standard.

[0147] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A thermal calculation method for time-varying working conditions of a waste heat boiler economizer vaporization, characterized in that: include: Obtaining economizer related parameters; the economizer related parameters include economizer design operating condition parameters and variable operating condition parameters; The design operating parameters include the product of the second total heat transfer coefficient and the total heat exchange area, the heat dissipation coefficient, the inlet and outlet pressure, temperature and flow rate of the water side, and the inlet and outlet composition, temperature and flow rate of the flue gas side; The variable operating parameters include the water side inlet pressure, temperature and flow rate and the flue gas side outlet composition, temperature and flow rate; Based on the economizer related parameters, a first water-side heat exchange value, a second water-side heat exchange value, and a first deviation between the first water-side heat exchange value and the second water-side heat exchange value of the economizer are calculated; Based on the parameters of the economizer under design conditions and variable conditions, the water side pressure drop, the product of the first total heat transfer coefficient and the total heat exchange area, and the first water side heat exchange value under variable conditions of the economizer are calculated; Based on the water side pressure drop, the product of the first total heat transfer coefficient and the total heat exchange area, and the first water side heat exchange value, combined with the input parameters of the economizer when the operating condition changes, the second water side heat exchange value of the economizer when the operating condition changes is obtained; If the first deviation value is less than the first residual standard, determining whether the water-side outlet enthalpy of the economizer is less than the water-side saturated water enthalpy; If the outlet enthalpy of the economizer on the water side is greater than the saturated water enthalpy on the water side, the economizer is divided into a first part and a second part; The first part is the process of heating supercooled water to saturated water, and the second part is the process of heating saturated water to wet saturated steam; Calculating a third water-side heat exchange value, a fourth water-side heat exchange value, and a second deviation between the third water-side heat exchange value and the fourth water-side heat exchange value of the second part; If the second deviation value is less than the second residual standard, the key data of the economizer under the variable operating condition is output; the key data includes the water side outlet pressure, temperature and enthalpy value and the flue gas side inlet temperature under the economizer under the variable operating condition.

2. A thermal calculation method for time-varying working conditions of a waste heat boiler economizer vaporization as claimed in claim 1, characterized in that: The first deviation value includes: If the first deviation value is less than the first residual standard, the water side outlet pressure, temperature and enthalpy value and the flue gas side inlet temperature of the economizer under the changed operating condition are output; If the first deviation value is not less than the first residual standard, the first water-side heat exchange value is updated by the Newton-Raphson algorithm, and the first deviation value is iteratively calculated and compared with the first residual standard until the first deviation is less than the first residual standard.

3. A thermal calculation method for time-varying working conditions of a waste heat boiler economizer vaporization as claimed in claim 2, characterized in that: Determine whether the water-side outlet enthalpy of the economizer is less than the saturated water enthalpy of the water-side, including: If the outlet enthalpy of the economizer on the water side is less than the saturated water enthalpy on the water side, the calculation ends and the key data of the economizer under variable operating conditions are output; If the outlet enthalpy of the economizer on the water side is not less than the saturated water enthalpy on the water side, the economizer is divided into a first part and a second part.

4. A thermal calculation method for time-varying working conditions of a waste heat boiler economizer vaporization as claimed in claim 3, characterized in that: Calculating the third water-side heat exchange value and the fourth water-side heat exchange value of the second part includes: Calculate the inlet flue gas temperature, outlet saturated water temperature and heat exchange ratio of the first part; Calculate the heat exchange value of the third water side of the second part; Based on the inlet flue gas temperature, outlet saturated water temperature, heat exchange ratio of the first part and the third water side heat exchange value of the second part, the fourth water side heat exchange value is obtained.

5. A thermal calculation method for time-varying working conditions of a waste heat boiler economizer vaporization as claimed in claim 4, characterized in that: The second deviation value includes: If the second deviation value is not less than the second residual standard, the third water-side heat exchange value is updated by the Newton-Raphson algorithm, and the second deviation value is iteratively calculated and compared with the second residual standard until the second deviation is less than the second residual standard.

6. A heat calculation system for time-varying working conditions of a waste heat boiler economizer under vaporization, using a heat calculation method for time-varying working conditions of a waste heat boiler economizer under vaporization as claimed in any one of claims 1 to 5, characterized in that: include: Data acquisition module, used to obtain economizer related parameters; A first calculation module is used to calculate a first water-side heat exchange value, a second water-side heat exchange value, and a first deviation between the first water-side heat exchange value and the second water-side heat exchange value of the economizer based on the economizer related parameters; A first judgment module is used to judge whether the water-side outlet enthalpy of the economizer is less than the saturated water enthalpy of the water side if the first deviation value is less than the first residual standard; if the water-side outlet enthalpy of the economizer is greater than the saturated water enthalpy of the water side, divide the economizer into a first part and a second part; A second calculation module, used for calculating a third water-side heat exchange value, a fourth water-side heat exchange value, and a second deviation between the third water-side heat exchange value and the fourth water-side heat exchange value of the second part; The second judgment module is used to output key data under the variable operating condition of the economizer if the second deviation value is less than a second residual standard.

7. A computer device comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the thermal calculation method for time-varying operating conditions of the waste heat boiler economizer vaporization are implemented as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the thermal calculation method for time-varying operating conditions of a waste heat boiler economizer vaporization as described in any one of claims 1 to 5.

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