A design method and device for a water heat storage compressed air energy storage system

Abstract

The present invention relates to a design method for a water heat storage compressed air energy storage system, comprising: S1, obtaining the air flow of the compressor; S2, calculating the total power consumption of the compressor; S3, setting the end difference of the heat exchanger on the compressor side; and calculating the flow of a heat storage medium based on the end difference of the heat exchanger on the compressor side; S4, setting the air flow of the expander; S5, setting the end difference of the heat exchanger on the expander side; and calculating the flow of a heat release medium based on the end difference of the heat exchanger on the expander side; S6, calculating the total output of the expander based on the air flow of the expander; and S7, judging whether a state of equilibrium is in effect based on the air flow of the compressor, the air flow of the expander, the flow of the heat storage medium, and the flow of the heat release medium; if an unbalanced state is in effect, returning to step S5 and resetting the end difference of the heat exchanger on the expander side.

Description

Technical Field

[0001] The present invention relates to a design method and device for a water heat storage compressed air energy storage system, belonging to the field of compressed air energy storage systems. Background Art

[0002] The compressed air energy storage system (CAES system) includes system components such as a compressor unit, a heat exchange unit, a heat storage unit, an expander unit, and an air storage chamber. When the grid load is low, the compressed air energy storage system absorbs excess electricity from the grid, drives the compressor to work, compresses the air into high-pressure air and stores it in the air storage chamber. Heat is generated during the compression process, which is exchanged out through the heat exchange system and stored in the heat storage unit. When the grid load is peak, the compressed air energy storage system releases high-pressure air from the air storage chamber, enters the expander to expand and work, generates electricity and sends it to the grid. During the work process, the heat stored in the heat storage unit is absorbed by the heat exchange system.

[0003] To determine the economic viability of a compressed air energy storage project, accurate and efficient calculations of the compressed air energy storage system are necessary, ensuring that the system is designed for high efficiency. Currently, compressed air energy storage is in its infancy in China, and there are relatively few design and analysis methods for compressed air energy storage systems. These methods primarily focus on improving the efficiency of compressed air energy storage systems, while lacking research on overall system performance. Therefore, a design method that can ensure the overall performance of CAES systems is needed.

[0004] Patent publication number CN112883509A, "A Design Method and System for an Adiabatic Compressed Air Energy Storage System," has the following shortcomings: 1) This method uses the final compressor outlet temperature as a boundary condition to determine the number of compressor and expander stages, and thus the corresponding system parameter configuration. This method, in pursuit of lower exhaust temperatures, results in the accumulation of compression heat in the heat storage tank, which, if not utilized, also leads to heat loss. 2) Furthermore, excessive pursuit of low exhaust temperatures can result in excessively low design end differentials for the heat exchanger, increasing investment in the heat exchanger and negatively impacting investment returns. 3) It fails to consider the distribution of heat within each compressor / expander stage, making it difficult to achieve heat balance with this algorithm, potentially leading to heat accumulation or insufficient heat for heating the air. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the present invention designs a design method and device for a water heat storage compressed air energy storage system, adjusts the end difference of the heat exchanger on the expander side, so that the CAES system reaches a gas balance and thermal equilibrium state, and the air mass flow ratio during the compression-expansion process is equal to the heat ratio generated or consumed during the compression-expansion process, fully utilizing the heat during the compression process to achieve a higher electric-to-electric conversion efficiency.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] Technical solution 1:

[0008] A method for designing a water heat storage compressed air energy storage system comprises the following steps:

[0009] Get the compressor air flow;

[0010] Calculate the total power consumption of the compressor;

[0011] Set the end difference of the heat exchanger on the compressor side; calculate the flow rate of the heat storage medium based on the end difference of the heat exchanger on the compressor side;

[0012] Set the expander air flow rate;

[0013] Set the end difference of the heat exchanger on the expander side; calculate the flow rate of the heat release medium based on the end difference of the heat exchanger on the expander side;

[0014] Calculate the total output of the expander based on the expander air flow rate;

[0015] Whether the compressed air energy storage system is balanced is determined based on the compressor air flow, expander air flow, heat storage medium flow, and heat release medium flow. If unbalanced, the expander side heat exchanger end difference is reset to balance the compressed air energy storage system.

[0016] Furthermore, the determination of whether the compressed air energy storage system is balanced is specifically as follows:

[0017] Calculate the first indicator E0, expressed as follows:

[0018]

[0019] Where, Indicates the flow rate of heat storage medium; Indicates the flow rate of heat release medium; q c_a Indicates the compressor air flow; q t_a represents the expander air flow rate;

[0020] If the first indicator E0 is greater than a preset threshold, it is considered that the system is in an unbalanced state.

[0021] Furthermore, it also includes:

[0022] According to the total power consumption of the compressor and the total output of the expander, it is judged whether the output of the compressed air energy storage system meets the requirements. If it does not meet the requirements, the air flow of the expander is reset to make the output of the compressed air energy storage system meet the requirements.

[0023] Furthermore, the determination of whether the compressed air energy storage system output meets the requirements is specifically as follows:

[0024] Calculate the second indicator E1, expressed as follows:

[0025] E1=|W c -W t | / W c

[0026] Where W t Indicates the total output of the expander; W c Indicates the total power consumption of the compressor;

[0027] If the second indicator E1 is greater than the preset threshold, it is considered that the output does not meet the requirements.

[0028] Furthermore, it also includes:

[0029] According to the end difference of the heat exchanger on the compressor side and the end difference of the heat exchanger on the expander side, it is judged whether the end difference of the heat exchanger in the compressed air energy storage system meets the requirements. If it does not meet the requirements, the end difference of the heat exchanger on the compressor side is reset to make the end difference of the compressed air energy storage system meet the requirements.

[0030] Furthermore, the determination of whether the heat exchanger end difference in the compressed air energy storage system meets the requirements is specifically as follows:

[0031] Calculate the third indicator E3, expressed as follows:

[0032] E3=|Δ c_hx_u_i -Δ t_hx_u_i | / Δ c_hx_u_i

[0033] Where, Δ c_hx_u_i Indicates the upper end difference of the i-th section heat exchanger on the compressor side; Δ t_hx_u_i It represents the upper end difference of the i-th heat exchanger on the expander side;

[0034] If the third indicator E3 is greater than the preset threshold, it is considered that the heat exchanger end difference does not meet the requirements.

[0035] Furthermore, it also includes:

[0036] The fourth indicator E4 is calculated as follows:

[0037] E4=|Δ c_hx_d_i -Δ t_hx_d_i | / Δ c_hx_d_i

[0038] Where, Δ c_hx_d_i Indicates the difference at the lower end of the i-th heat exchanger on the compressor side; Δ t_hx_d_i It represents the difference at the lower end of the heat exchanger in the i-th section on the expander side;

[0039] If the third indicator E3 or the fourth indicator E4 is greater than the preset threshold, it is considered that the heat exchanger end difference does not meet the requirements.

[0040] Furthermore, the flow rate of the heat storage medium is calculated based on the end difference of the compressor side heat exchanger, which is expressed as follows:

[0041] q c_w_i =(h hx_a_in_i -h hx_a_out_i )q c_a η hx / (h hx_w_out_i -h hx_w_in_i )

[0042] Where h hx_a_in_i represents the enthalpy of the air at the inlet of the i-th stage heat exchanger, h hx_a_out_i represents the enthalpy of the air at the outlet of the i-th stage heat exchanger, q c_a is the compressor air flow rate, η hx Indicates the heat transfer efficiency of the heat exchanger, h hx_w_out_i represents the enthalpy of the heat storage medium at the outlet of the i-th stage heat exchanger, h hx_w_in_i It represents the enthalpy of the heat storage medium at the inlet of the i-th stage heat exchanger.

[0043] Furthermore, the flow rate of the heat release medium is calculated based on the end difference of the expander side heat exchanger, which is expressed as follows:

[0044] q t_w_i =(h hx_a_in_i -h hx_a_out_i )q t_a / [(h hx_w_out_i -h hx_w_in_i )η hx ]

[0045] Where h hx_a_in_i represents the enthalpy of the air at the inlet of the i-th stage heat exchanger, h hx_a_out_i represents the enthalpy of the air at the outlet of the i-th stage heat exchanger, q t_a is the air flow rate during expansion, η hx Indicates the heat transfer efficiency of the heat exchanger, h hx_w_out_i Indicates the enthalpy of the heat release medium at the outlet of the i-th stage heat exchanger, h hx_w_in_i It represents the enthalpy value of the heat release medium at the inlet of the i-th stage heat exchanger.

[0046] Technical solution 2:

[0047] A design device for a water heat storage compressed air energy storage system, comprising:

[0048] A data acquisition unit, wherein the data acquisition unit is used to acquire the air flow of the compressor;

[0049] A parameter setting unit, the parameter setting unit is used to set the end difference of the heat exchanger on the compressor side, the air flow of the expander, and the end difference of the heat exchanger on the expander side;

[0050] A calculation unit, the calculation unit is used to calculate the total power consumption of the compressor; calculate the flow rate of the heat storage medium according to the end difference of the heat exchanger on the compressor side; calculate the flow rate of the heat release medium according to the end difference of the heat exchanger on the expander side; calculate the total output of the expander according to the air flow rate of the expander;

[0051] A correction unit is used to determine whether the compressed air energy storage system is balanced based on the compressor air flow, the expander air flow, the flow of the heat storage medium and the flow of the heat release medium; and when the compressed air energy storage system is unbalanced, reset the expander side heat exchanger end difference to balance the compressed air energy storage system.

[0052] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0053] 1. The present invention adjusts the end difference of the expander-side heat exchanger to enable the CAES system to reach gas and thermal equilibrium. The air mass flow rate ratio during the compression-expansion process is equal to the heat ratio generated or consumed during the compression-expansion process, fully utilizing the heat during the compression process to achieve a high electric-to-electric conversion efficiency.

[0054] 2. The present invention determines whether the system output meets the requirements based on the total power consumption of the compressor and the total output of the expander, and corrects the air flow of the expander accordingly, so as to obtain relatively close compressor power consumption and expander output, so that the incoming and outgoing line sections of the power system of the power plant can be used more economically, saving investment in power wiring.

[0055] 3. The present invention determines whether the system heat exchanger end difference meets the requirements based on the upper and lower end differences of the heat exchangers on the compressor and expander sides of the same level, and corrects the compressor side heat exchanger end difference accordingly. The advantage is that it can make the heat exchanger design and operation under a more economical state, and the heat exchanger end difference is set at a reasonable value, which not only saves heat exchanger investment but also improves system operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a flow chart of the present invention;

[0057] Figure 2 It is a structural diagram of the compressed air energy storage system. DETAILED DESCRIPTION

[0058] The present invention will be described in more detail below with reference to the embodiments.

[0059] Example 1

[0060] like Figure 2 As shown, a water heat storage compressed air energy storage system includes: a compressor, an expander, a heat exchange unit, a heat storage unit, an air storage unit, etc.

[0061] The compressor includes several compression cylinders, which are connected in series with the heat exchanger through air pipes. The inlet of the first-stage compression cylinder is connected to the atmospheric environment, and the final exhaust outlet of the compression cylinder is connected to the inlet of the air storage unit through an air pipe.

[0062] The expander includes several turbine cylinders, which are connected in series with the heat exchanger through air pipes. The inlet of the first-stage turbine cylinder is connected to the outlet of the air storage unit through an air pipe, and the final exhaust outlet of the turbine cylinder is connected to the atmospheric environment; the heat exchange unit includes several heat exchangers, the air side of which is connected to the compression cylinder of the compressor and the turbine cylinder of the expander respectively, and the water side is connected to the high-temperature water storage tank and the low-temperature water storage tank in the heat storage unit respectively through water pipes.

[0063] The heat storage unit includes a high-temperature water storage tank and a low-temperature water storage tank, which are respectively connected to the water side of the heat exchanger in the heat exchange unit through water pipes; the gas storage unit includes a gas storage cave, which is connected to the expander inlet and the compressor outlet through air pipes.

[0064] During the inflation operation, the compressor receives electrical energy from the power system and performs work through several compression cylinders to compress the air from atmospheric pressure to a certain pressure and store it in the air storage cavern. The compression process generates heat, which is transferred to the water through the heat exchanger and stored in the high-temperature water storage tank.

[0065] During the deflation condition, the compressed air in the gas storage cave enters the expander to perform work and generate electricity. The temperature of the air drops during expansion, and the air is heated by the heat in the high-temperature water storage tank. The heated air enters the expander, and the water cooled by the air enters the low-temperature water storage tank.

[0066] like Figure 1 As shown, the design method of the water heat storage compressed air energy storage system includes the following steps:

[0067] S1. Determine the compressor air flow q c_a .

[0068] S2. Calculate the total power consumption W of the compressor c .

[0069] S3. Set the end difference of the heat exchanger on the compressor side, specifically the upper end difference Δ of the i-th stage heat exchanger on the compressor side. c_hx_u_i , compressor side i-th stage heat exchanger lower end difference Δ c_hx_d_i .

[0070] Calculate the temperature and flow rate q of the heat storage medium based on the end difference of the heat exchanger on the compressor side c_w_i Preferably, the heat storage medium is water.

[0071] S4. Set the expander air flow rate q t_a , gas storage outlet temperature T1, pressure p1;

[0072] S5. Set the end difference of the heat exchanger on the expander side, specifically the upper end difference Δ of the i-th stage heat exchanger on the expander side. t_hx_u_i , the difference Δ at the lower end of the i-th stage heat exchanger on the expander side t_hx_d_i .

[0073] Calculate the expander air temperature and the flow rate q of the heat release medium based on the end difference of the expander side heat exchanger t_w_i Preferably, the exothermic medium is water.

[0074] S6, according to the expander air flow q t_a , calculate the total output W of the expander t .

[0075] S7. Determine whether the CAES system is balanced:

[0076] Calculate the first index E0, which is the absolute value of the difference between the ratio of the heat storage medium flow rate to the heat release medium flow rate and the ratio of the compressor air mass flow rate to the expander air mass flow rate, and is expressed as follows:

[0077]

[0078] Where, is the heat balance formula, which expresses the ratio of the heat storage medium flow rate to the heat release medium flow rate, q c_a / q t_a is the gas balance formula, which expresses the ratio of the compressor air mass flow rate to the expander air mass flow rate.

[0079] If the first indicator E0 is within the error range, proceed to the next step; otherwise, return to step S5 to reset the expander side heat exchanger end difference. In this embodiment, the expander side heat exchanger upper end difference is reset based on the previous expander heat release medium flow rate and air parameters. The calculation formula is:

[0080] h hx_a_out_i =h hx_a_in_i +(h hx_w_out_i -h hx_w_in_i )q t_w_i η hx / q t_a

[0081] Δ t_hx_d_i =Th x_a_out_i -T hx_w_in_i

[0082] Where h hx_w_out_i Indicates the enthalpy of the heat release medium at the outlet of the i-th stage heat exchanger, h hx_w_in_i represents the enthalpy value of the heat release medium at the inlet of the i-th stage heat exchanger; q t_w_i represents the flow rate of heat release medium in the i-th stage heat exchanger; qt_a is the air flow rate during the expansion process; η hx Indicates the heat transfer efficiency of the heat exchanger. Temperature T is a function of enthalpy h and pressure p, meaning that temperature T can be solved based on enthalpy h and pressure p.

[0083] S8. Based on the total power consumption of the compressor and the total output of the expander, determine whether the CAES system output meets the requirements:

[0084] The second indicator E1 is calculated as the ratio of the difference between the total output of the expander and the total power consumption of the compressor to the total power consumption of the compressor, which can be expressed as follows:

[0085] E1=|W c -W t | / W c

[0086] Where W t Indicates the total output of the expander; W c Indicates the total power consumption of the compressor.

[0087] If E1 is within the error range, it is considered that the CAES system output meets the requirements and the process proceeds to the next step; otherwise, the process returns to step S4 to reset the expander air flow.

[0088] S9. Determine whether the heat exchanger end difference meets the requirements based on the compressor side heat exchanger end difference and the expander side heat exchanger end difference;

[0089] Calculate the third index E3 and the fourth index E4. The third index E3 is the ratio of the difference between the upper end difference of the heat exchangers of the same stage on the compressor and the expander side to the upper end difference of the heat exchangers of the same stage on the compressor side. The fourth index E4 is the ratio of the difference between the lower end difference of the heat exchangers of the same stage on the compressor and the expander side to the lower end difference of the heat exchangers of the same stage on the compressor side. The formula is:

[0090] E3=|Δ c_hx_u_i -Δ t_hx_u_i | / Δ c_hx_u_i

[0091] E4=|Δ c_hx_d_i -Δ t_hx_d_i | / Δ c_hx_d_i

[0092] Where, Δ c_hx_u_i Indicates the upper end difference of the i-th section heat exchanger on the compressor side; Δ t_hx_u_i Indicates the upper end difference of the i-th heat exchanger on the expander side; Δ c_hx_d_i Indicates the difference at the lower end of the i-th heat exchanger on the compressor side; Δ t_hx_d_i It represents the difference at the lower end of the heat exchanger in the i-th section on the expander side;

[0093] If E3 and E4 are within the error range, the design is completed. Otherwise, return to step S3 to reset the end difference of the compressor side heat exchanger. The calculation formula is:

[0094] New upper difference Δ u_新 =(Δ c_hx_u_i +Δ t_hx_u_i ) / 2

[0095] New lower end difference Δ d_新 =(Δ c_hx_d_i +Δ t_hx_d_i ) / 2

[0096] Where, Δ c_hx_u_i Indicates the upper end difference of the i-th stage heat exchanger on the compressor side; Δ t_hx_u_i Indicates the upper end difference of the i-th stage heat exchanger on the expander side; Δ c_hx_d_i Indicates the lower end difference of the i-th stage heat exchanger on the compressor side; Δ t_hx_d_i Indicates the lower end difference of the i-th stage heat exchanger on the expander side.

[0097] Example 2

[0098] Furthermore, the total power consumption of the compressor is calculated as follows:

[0099] S21. Calculate the pressure ratio of the i-th compressor:

[0100]

[0101] Where, e represents the natural logarithm; subscript c represents the compressor; subscript out represents the compressor outlet; subscript in represents the compressor inlet; subscript c_i represents the i-th compressor; ε c_i Indicates the pressure ratio of the compressor section i; m i is the polytropic index of the compressor section i; T c_in_i is the inlet temperature of the compressor section i; T c_out_i is the outlet temperature of the compressor section i.

[0102] S22. Calculate the outlet pressure of the compressor in section i:

[0103] p c_out_i =ε c_ipc_in_i

[0104] Among them, p c_out_i represents the outlet pressure of the compressor section i, p c_in_i Indicates the inlet pressure of the compressor section i.

[0105] S23. Calculate the shaft power of the compressor in section i:

[0106]

[0107] Among them, Wc_d_i is the shaft power of the compressor section i; R is the gas constant of air; T c_in_i is the inlet temperature of the compressor section i; η d_i is the variable efficiency of the compressor section i.

[0108] S24. Calculate the actual power consumption of the compressor in section i:

[0109]

[0110] Where W c_i is the actual power consumption of the compressor section i, η c_d is the motor efficiency of the compressor section i, η c_j is the mechanical efficiency of the i-th section of the compressor.

[0111] S25. Calculate the total power consumption of the compressor:

[0112]

[0113] Where n represents the number of compressor stages.

[0114] Example 3

[0115] Furthermore, the temperature and flow rate of the heat storage medium are calculated based on the end difference of the heat exchanger on the compressor side, as follows:

[0116] S31. Calculate the temperature of the heat storage medium in the i-th stage heat exchanger:

[0117] T hx_w_out_i =T hx_a_in_i -Δ c_hx_u_i

[0118] T hx_w_in_i =T hx_a_out_i -Δ c_hx_d_i

[0119] Wherein, subscript hx represents the heat exchanger, subscript a represents air, subscript w represents water, subscript in represents the heat exchanger inlet, subscript out represents the heat exchanger outlet, subscript u represents the upper end difference, subscript d represents the lower end difference, and subscript i represents the i-th stage heat exchanger; T hx_a_in_i represents the temperature of the air inlet of the i-th stage heat exchanger, T hx_w_out_i Indicates the temperature of the water medium outlet of the i-th stage heat exchanger, Δ hx_u_i Indicates the upper end difference of the i-th stage heat exchanger, T hx_a_out_i represents the temperature of the air outlet of the i-th stage heat exchanger, T hx_w_in_i Indicates the temperature of the water medium inlet of the i-th stage heat exchanger, Δ hx_d_i The air inlet temperature of the i-th stage heat exchanger is equal to the air outlet temperature of the i-th stage compressor, that is,

[0120] T hx_a_in_i =T c_out_i

[0121] S32. Calculate the flow rate of the heat storage medium in the i-th stage heat exchanger:

[0122] q c_w_i =(h hx_a_in_i -h hx_a_out_i )q c_a η hx / (h hx_w_out_i -h nx_w_in_i )

[0123] Where h hx_a_in_i represents the enthalpy of the air at the inlet of the i-th stage heat exchanger, h hx_a_out_i represents the enthalpy of the air at the outlet of the i-th stage heat exchanger, q c_a is the compressor air flow rate, η hx Indicates the heat transfer efficiency of the heat exchanger, h hx_w_out_i Indicates the enthalpy value of the water medium outlet of the i-th stage heat exchanger, h hx_w_in_i It represents the enthalpy value at the water medium inlet of the i-th stage heat exchanger. The enthalpy value h is a function of temperature T and pressure p, that is, the enthalpy value h can be solved based on temperature T and pressure p.

[0124] Example 4

[0125] Furthermore, the temperature and flow rate of the compressed air are calculated based on the end difference of the heat exchanger on the expander side;

[0126] S51. Calculate the temperature of the air in the i-th stage heat exchanger:

[0127] Th x_a_in_i =Th x_w_out_i -Δ c_hx_u_i

[0128] T hx_a_out_i =Th x_w_in_i -Δ c_hx_d_i

[0129] Wherein, subscript hx represents the heat exchanger, subscript a represents air, subscript w represents water, subscript in represents the heat exchanger inlet, subscript out represents the heat exchanger outlet, subscript u represents the upper end difference, subscript d represents the lower end difference, and subscript i represents the i-th stage heat exchanger; T hx_a_in_i represents the temperature of the air inlet of the i-th stage heat exchanger, T hx_w_out_i Indicates the temperature of the water medium outlet of the i-th stage heat exchanger, Δ hx_u_i Indicates the upper end difference of the i-th stage heat exchanger, T hx_a_out_i represents the temperature of the air outlet of the i-th stage heat exchanger, T hx_w_in_i Indicates the temperature of the water medium inlet of the i-th stage heat exchanger, Δhx_d_i The air outlet temperature of the i-th stage heat exchanger is equal to the air inlet temperature of the i-th stage expander, that is,

[0130] T hx_a_out_i =T h_in_i

[0131] Among them, temperature T is a function of enthalpy value h and pressure p, that is, temperature T can be solved based on enthalpy value h and pressure p.

[0132] S52. Calculate the flow rate of the heat release medium (i.e., the water medium in the expander-side heat exchanger):

[0133] q t_w_i =(h hx_a_in_i -h hx_a_out_i )q t_a / [(h hx_w_out_i -h hx_w_in_i )η hx ]

[0134] Where h hx_a_in_i represents the enthalpy of the air at the inlet of the i-th stage heat exchanger, h hx_a_out_i represents the enthalpy of the air at the outlet of the i-th stage heat exchanger, q t_a is the air flow rate during expansion, η hx Indicates the heat transfer efficiency of the heat exchanger, h hx_w_out_i Indicates the enthalpy value of the water medium outlet of the i-th stage heat exchanger, h hx_w_in_i It represents the enthalpy value of the water medium inlet of the i-th stage heat exchanger.

[0135] Example 5

[0136] Furthermore, the total output of the expander is calculated as follows:

[0137] S61. Calculate the output power of the expander. Specifically, calculate the output power of the i-th expander as:

[0138] W t_i =(h t_out_i -h t_in_i )q t_a η t_i

[0139] Where W t_i represents the output power of the i-th expander, h t_out_i represents the outlet air enthalpy of the i-th expander, h t_in_i represents the inlet air enthalpy of the i-th expander, q t_a represents the air mass flow rate through the expander, η t_i Represents the motor efficiency of the i-th expander.

[0140] S62. The total output of the expander can be calculated as:

[0141]

[0142] Wherein, n represents the number of expander stages.

[0143] Example 6

[0144] Step 1: Determine the ambient temperature to be 25°C, the pressure to be 1.01 barA, and the humidity to be 80% RH. The compressed air energy storage system compressor is arranged in two lines, with four compression stages per line and an air flow rate of 850t / h.

[0145] The polytropic index, polytropic efficiency, and exhaust temperature of each section of the compressor are shown in Table 1;

[0146] Table 1

[0147] compressor Flow rate t / h Inlet air temperature ℃ Exhaust temperature ℃ Variable efficiency % Volatility Index C 1# 850 25 190 89.3 1.469 C 2# 850 40 190 90.7 1.443 C 3# 850 40 190 90 1.465 C 4# 850 40 190 89.6 1.466

[0148] Step 2: Calculate the pressure ratio of the i-th compressor:

[0149]

[0150] Where, e represents the natural logarithm, subscript c represents the compressor, subscript out represents the compressor outlet, subscript in represents the compressor inlet, and subscript i represents the i-th compressor; ε c_i Indicates the pressure ratio of the i-th compressor, m i is the polynomial index of the i-th compressor; T c_in_i is the inlet temperature of the compressor section i, T c_out_i is the outlet temperature of the i-th compressor section. i 、T c_out_i 、T c_in_i The data in Table 1 can be taken.

[0151] The calculation results are shown in Table 2:

[0152] Table 2

[0153] compressor Flow rate t / h Pressure ratio Inlet air temperature ℃ Exhaust temperature ℃ Variable efficiency % Volatility Index C 1# 850 3.98 25 190 89.3 1.469 C 2# 850 3.58 40 190 90.7 1.443 C 3# 850 3.43 40 190 90 1.465 C 4# 850 3.43 40 190 89.6 1.466

[0154] Calculate the outlet pressure of the compressor in section i:

[0155] p c_out_i =ε c_ipc_in_i

[0156] Where p c_out_i Indicates the outlet pressure of the i-th compressor, p c_in_i represents the inlet pressure of the i-th compressor, ε c_i 、p c_in_i The data in Table 2 can be taken.

[0157] If the inter-stage compressed air heat exchange pressure loss is set to 0.3 barA, the calculation results are shown in Table 3:

[0158] Table 3

[0159]

[0160] Calculate the shaft power of the compressor in section i:

[0161]

[0162] Where W c_d_i is the shaft power of the compressor in section i; m i is the polytropic index of the i-th compressor; R represents the gas constant of air; T c_in_i is the inlet temperature of the i-th compressor; η d_i is the variable efficiency of the i-th compressor.

[0163] Calculate the actual power consumption of the compressor in section i:

[0164]

[0165] Where W c_i is the actual power consumption of the compressor in the i-th section; η c_d is the motor efficiency of the i-th compressor, η c_j is the mechanical efficiency of the i-th section of the compressor, the motor efficiency is taken as 0.99 and the mechanical efficiency is taken as 0.98.

[0166] Calculate the total power consumption of the compressor:

[0167]

[0168] The calculation results are shown in Table 4:

[0169] Table 4

[0170]

[0171]

[0172] Therefore, the total power consumption of the compressor two lines is 303.8MW.

[0173] Step 3: Set the end difference of the heat exchanger on the compressor side and set the upper end difference Δ hx_u_i All are 15℃, the lower end difference is Δ hx_d_i All are 10℃;

[0174] Calculate the temperature and flow of the heat storage medium based on the end difference of the heat exchanger on the compressor side;

[0175] Calculate the temperature of the heat storage medium in the i-th stage heat exchanger:

[0176] Th x_a_in_i =Th x_w_out_i -Δ chx_u_i

[0177] T hx_a_out_i =T hx_w_in_i -Δ c_hx_d_i

[0178] Wherein, subscript hx represents the heat exchanger, subscript a represents air, subscript w represents water, subscript in represents the heat exchanger inlet, subscript out represents the heat exchanger outlet, subscript u represents the upper end difference, subscript d represents the lower end difference, and subscript i represents the i-th stage heat exchanger; T hx_a_in_i represents the temperature of the air inlet of the i-th stage heat exchanger, T hx_w_out_i Indicates the temperature of the water medium outlet of the i-th stage heat exchanger, Δ hx_u_i Indicates the upper end difference of the i-th stage heat exchanger, T hx_a_out_i represents the temperature of the air outlet of the i-th stage heat exchanger, T hx_w_in_i Indicates the temperature of the water medium inlet of the i-th stage heat exchanger, Δ hx_d_i Represents the lower end difference of the i-th stage heat exchanger.

[0179] Among them, the air inlet temperature of the i-th stage heat exchanger is equal to the air outlet temperature of the i-th section compressor, that is,

[0180] T hx_a_in_i =T c_out_i

[0181] Calculate the hot water storage medium flow rate of the i-th stage heat exchanger as:

[0182] q c_w_i =(h hx_a_in_i -h hx_a_out_i )q c_a η hx / (h hx_w_out_i -h hx_w_in_i )

[0183] Where h hx_a_in_i represents the enthalpy of the air at the inlet of the i-th stage heat exchanger, h hx_a_out_i represents the enthalpy of the air at the outlet of the i-th stage heat exchanger, q c_a is the compressor air flow rate, η hx Indicates the heat transfer efficiency of the heat exchanger, h hx_w_out_i Indicates the enthalpy value of the water medium outlet of the i-th stage heat exchanger, h hx_w_in_i It represents the enthalpy value at the water medium inlet of the i-th stage heat exchanger. The enthalpy value h is a function of temperature T and pressure p, that is, the enthalpy value h can be solved based on temperature T and pressure p.

[0184] The calculation results are shown in Table 5:

[0185] Table 5

[0186]

[0187] Step 4: Set the gas storage outlet temperature T1 At 25°C and pressure p1 is 1.01barA, expander air flow rate is 2345t / h.

[0188] Step 5: Set the end difference of the heat exchanger on the expander side. Assume that the upper end difference of the heat exchanger on the expander side is 15°C and the lower end difference of the heat exchanger is 10°C.

[0189] Calculate the temperature of the air in the i-th stage heat exchanger:

[0190] T hx_a_in_i =T hx_w_out_i -Δ c_hx_u_i

[0191] T hx_ a _out_i =T hx_w_in_i -Δ c_hx_d_i

[0192] Wherein, subscript hx represents the heat exchanger, subscript a represents air, subscript w represents water, subscript in represents the heat exchanger inlet, subscript out represents the heat exchanger outlet, subscript u represents the upper end difference, subscript d represents the lower end difference, and subscript i represents the i-th stage heat exchanger; T hx_a_in_i represents the temperature of the air inlet of the i-th stage heat exchanger, T hx_w_out_i Indicates the temperature of the water medium outlet of the i-th stage heat exchanger, Δ hx_u_i Indicates the upper end difference of the i-th stage heat exchanger, T hx_a_out_i represents the temperature of the air outlet of the i-th stage heat exchanger, T hx_w_in_i Indicates the temperature of the water medium inlet of the i-th stage heat exchanger, Δ hx_d_i Represents the lower end difference of the i-th stage heat exchanger.

[0193] Calculate the flow rate of heat release medium:

[0194] q t_w_i =(h hx_a_in_i -h hx_a_out_i )q t_a / [(h hx_w_out_i -h hx_w_in_i )η hx ]

[0195] Where h hx_a_in_i represents the enthalpy of the air at the inlet of the i-th stage heat exchanger, h hx_a_out_i represents the enthalpy of the air at the outlet of the i-th stage heat exchanger, q t_a is the air flow rate during expansion, η hxIndicates the heat transfer efficiency of the heat exchanger, h hx_w_out_i Indicates the enthalpy value of the water medium outlet of the i-th stage heat exchanger, h hx_w_in_i represents the enthalpy value of the water medium inlet of the i-th stage heat exchanger. The temperature T is a function of the enthalpy value h and the pressure p, that is, the temperature T can be solved based on the enthalpy value h and the pressure p.

[0196] The calculation results are shown in Table 6:

[0197] Table 6

[0198]

[0199] Step 6: Calculate the total output of the expander:

[0200] Calculate the expander output power. The output power of the i-th expander can be calculated as:

[0201] W t_i =(h t_out_i -h t_in_i )q t_a η t_i

[0202] Where W t_i represents the output power of the i-th expander, h t_out_i represents the outlet air enthalpy of the i-th expander, h t_in_i represents the inlet air enthalpy of the i-th expander, q t_a represents the air mass flow rate through the expander, η t_i Represents the motor efficiency of the i-th expander.

[0203] The total output of the expander can be calculated as:

[0204]

[0205] Where n represents the number of expander stages.

[0206] The calculation results are shown in Table 7:

[0207] Table 7

[0208] Number of expander stages 1 2 3 4 Total power Power MW 75.9 77.9 77.9 68.3 300

[0209] Step 7: Determine whether the CAES system is balanced:

[0210] Calculate the first indicator E0:

[0211]

[0212] Where, is the heat balance formula, which expresses the ratio of the heat storage medium flow rate to the heat release medium flow rate, q c_a / qt_a is the gas balance formula, which expresses the ratio of the compressor air mass flow rate to the expander air mass flow rate.

[0213] The error range is set to 1.5%; if E0 < 1.5%, the requirement is met and the process goes to step eight.

[0214] Step 8: Determine whether the CAES system output meets the requirements:

[0215] E1=|W c -W t | / W c =(303.8-300) / 303.8=1.25%

[0216] The error range is set to 1.5%; E1 < 1.5% meets the requirement, and proceed to step nine.

[0217] Step 9: Determine whether the end difference of the heat exchanger in the CAES system meets the requirements. The judgment basis is as follows:

[0218] E3=|Δ c_hx_u_i -Δ t_hx_u_i | / Δ c_hx_u_i =|15-15| / 15=0

[0219] E4=|Δ c_hx_d_i -Δ t_hx_d_i | / Δ c_hx_d_i =|10-10| / 10=0

[0220] If E3 and E4 are within the error range, the entire process calculation is completed; otherwise, return to step 3.

[0221] The error range is set to 1.5%; E3 and E4 < 1.5% meet the requirements, and the design calculation of the CAES system is completed.

[0222] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should analyze that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A design method for a water heat storage compressed air energy storage system, characterized in that: The following steps are involved: Get the compressor air flow; Calculate the total power consumption of the compressor; Set the end difference of the heat exchanger on the compressor side; Calculate the flow rate of the heat storage medium based on the end difference of the heat exchanger on the compressor side; Set the expander air flow rate; Set the end difference of the heat exchanger on the expander side; Calculate the flow rate of the heat release medium based on the end difference of the heat exchanger on the expander side; Calculate the total output of the expander based on the expander air flow rate; Based on the compressor air flow, expander air flow, heat storage medium flow and heat release medium flow, determine whether the compressed air energy storage system is balanced; if it is unbalanced, reset the expander side heat exchanger end difference to make the compressed air energy storage system balanced; The determination of whether the compressed air energy storage system is balanced is specifically as follows: Calculating a first index, where the first index is the absolute value of the difference between the ratio of the heat storage medium flow rate to the heat release medium flow rate and the ratio of the compressor air mass flow rate to the expander air mass flow rate; If the first indicator is greater than a preset threshold, the system is considered to be in an unbalanced state.

2. A water heat storage compressed air energy storage system design method according to claim 1, characterized in that: Also includes: According to the total power consumption of the compressor and the total output of the expander, it is judged whether the output of the compressed air energy storage system meets the requirements. If it does not meet the requirements, the air flow of the expander is reset to make the output of the compressed air energy storage system meet the requirements.

3. A water heat storage compressed air energy storage system design method according to claim 2, characterized in that: The determination of whether the compressed air energy storage system output meets the requirements is specifically as follows: A second indicator is calculated, where the second indicator is the ratio of the absolute value of the difference between the total output of the expander and the total power consumption of the compressor to the total power consumption of the compressor; if the second indicator is greater than a preset threshold, it is considered that the output does not meet the requirement.

4. A water heat storage compressed air energy storage system design method according to claim 1, characterized in that: Also includes: According to the end difference of the heat exchanger on the compressor side and the end difference of the heat exchanger on the expander side, it is judged whether the end difference of the heat exchanger in the compressed air energy storage system meets the requirements. If it does not meet the requirements, the end difference of the heat exchanger on the compressor side is reset to make the end difference of the compressed air energy storage system meet the requirements.

5. A water heat storage compressed air energy storage system design method according to claim 4, characterized in that: The determination of whether the end difference of the heat exchanger in the compressed air energy storage system meets the requirements is specifically as follows: Calculate a third indicator, which is the ratio of the absolute value of the difference between the upper end difference of the same-stage heat exchangers on the compressor and expander sides to the upper end difference of the same-stage heat exchanger on the compressor side; if the third indicator is greater than a preset threshold, it is considered that the heat exchanger end difference does not meet the requirements.

6. A method for designing a water heat storage compressed air energy storage system according to claim 5, characterized in that: Also includes: Calculate a fourth indicator, which is the ratio of the absolute value of the difference between the lower end difference of the heat exchangers of the same stage on the compressor and expander sides to the upper end difference of the heat exchangers of the same stage on the compressor side; if the third indicator or the fourth indicator is greater than the preset threshold, it is considered that the heat exchanger end difference does not meet the requirements.

7. The design method of a water heat storage compressed air energy storage system according to claim 1, characterized in that: The flow rate of the heat storage medium is calculated based on the end difference of the heat exchanger on the compressor side, and is expressed as follows: . No. The enthalpy of the air at the radiator inlet, No. The enthalpy of the air at the radiator outlet, Compressor air flow, The heat transfer efficiency of the heat exchanger, No. The enthalpy of the heat storage medium at the outlet of the heat exchanger, No. Enthalpy of the heat storage medium at the heat exchanger inlet.

8. The design method of a water heat storage compressed air energy storage system according to claim 1, characterized in that: The flow rate of the heat release medium is calculated based on the end difference of the heat exchanger on the expander side, and is expressed as follows: . No. The enthalpy of the air at the radiator inlet, No. The enthalpy of the air at the radiator outlet, Air flow during expansion, The heat transfer efficiency of the heat exchanger, No. The enthalpy of the heat release medium at the outlet of the heat exchanger, No. Enthalpy of the heat release medium at the heat exchanger inlet.

9. A water heat storage compressed air energy storage system design device, characterized in that: include: A data acquisition unit, wherein the data acquisition unit is used to acquire the air flow of the compressor; A parameter setting unit, the parameter setting unit is used to set the end difference of the heat exchanger on the compressor side, the air flow of the expander, and the end difference of the heat exchanger on the expander side; a calculation unit, the calculation unit being used to calculate the total power consumption of the compressor; Calculate the flow rate of the heat storage medium based on the end difference of the heat exchanger on the compressor side; Calculate the flow rate of the heat release medium based on the end difference of the heat exchanger on the expander side; Calculate the total output of the expander based on the expander air flow rate; a correction unit, the correction unit being configured to determine whether the compressed air energy storage system is balanced based on the compressor air flow, the expander air flow, the flow of the heat storage medium, and the flow of the heat release medium; and when the compressed air energy storage system is unbalanced, resetting the end difference of the heat exchanger on the expander side to balance the compressed air energy storage system; The determination of whether the compressed air energy storage system is balanced is specifically as follows: Calculating a first index, where the first index is the absolute value of the difference between the ratio of the heat storage medium flow rate to the heat release medium flow rate and the ratio of the compressor air mass flow rate to the expander air mass flow rate; If the first indicator is greater than a preset threshold, the system is considered to be in an unbalanced state.

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