Industrial waste heat coupling isothermal non-afterburning compressed air energy storage system

Abstract

The invention relates to the technical field of compressed air energy storage, in particular to an industrial waste heat coupling isothermal non-afterburning compressed air energy storage system which comprises an isothermal compression energy storage module, an isothermal compression heat recovery module, an industrial waste heat conversion module and an expansion power generation module. The isothermal compression energy storage module achieves multi-section compression of air and stores compressed air through electric energy in the valley period, and the isothermal compression heat recovery module is used for collecting compression heat generated by the isothermal compression energy storage module during multi-section compression of the air. The expansion power generation module receives the industrial waste heat stored by the industrial waste heat conversion module and is used for compressed gas expansion power generation; the isothermal compressor technology is adopted for compressing air, the compressed air energy storage efficiency is improved, the compression power consumption is reduced, meanwhile, industrial waste heat is fully utilized for heating the compressed air in the expansion stage, the problem that compression heat is insufficient in the isothermal compression process is solved, and the energy storage efficiency and the energy-saving effect are higher.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to an industrial waste heat coupled isothermal non-supplementary combustion type compressed air energy storage system. Background Art

[0002] Compressed air energy storage technology refers to a storage method that uses electrical energy to compress air during the low load period of the power grid, seals the air at high pressure in abandoned salt caverns, mines, sunken seabed gas storage containers, caves, expired oil and gas wells or newly built gas storage wells, and releases the compressed air to drive the expander to generate electricity during the peak load period of the power grid.

[0003] The engineering practice research of compressed air energy storage technology in my country is mainly focused on the research of adiabatic non-supplementary compressed air energy storage technology. Although it started late, we have achieved certain achievements through unremitting efforts. Adiabatic non-supplementary compressed air energy storage system refers to a compressed air energy storage system that does not require an external heat source when working. The system relies on storing heat energy in the compression stage and then uses it to heat the high-pressure air entering each section of the expander in the expansion stage, thereby improving the system's electric-to-electric conversion efficiency. This technical solution is implemented in this way: when storing energy, the low-valley electricity drive motor drives the compressor, and the compressor outlet gas is input into the gas storage container for storage after heat exchange. The compressed heat energy is stored in a high-temperature storage tank by the heat storage medium. When releasing energy, the stored compressed air is heated by the reheater and the high-temperature and high-pressure gas enters the expander to drive the generator to generate electricity and send it to the power grid. The advantage of this method is that it can deliver stable electricity to the power grid by controlling the work of the expander.

[0004] my country is rich in industrial waste heat resources, which account for about 17% to 67% of its total fuel consumption, of which the recoverable rate is 60%. At present, the utilization rate of waste heat resources in my country is low, and the waste heat utilization rate of large steel enterprises is about 30% to 50%, while that of other industries is even lower. There is great potential for improving waste heat utilization. In the metallurgical process, the waste heat quality of the second stage flue gas of the sintering ring cooler in the sintering section is better, and the flue gas temperature can reach 340 to 360°C.

[0005] Although the existing adiabatic compression technology has gotten rid of the dependence on fossil fuels and improved the system efficiency compared to the traditional supplementary combustion compressed air energy storage technology, the following problems still exist: the existing adiabatic compression energy storage technology uses compression heat to supplement the heat of the expansion power generation process. In order to improve the expansion power generation efficiency, high-temperature compression is generally used to increase the compression temperature. However, increasing the compression heat will put higher requirements on the performance, materials and safety of the compressor. At the same time, compared with other thermodynamic cycle processes, the adiabatic compression cycle process has the highest power consumption and energy loss. How to reduce compressor heat and make full use of industrial waste heat for the heat of the expansion power generation process is a problem that must be solved in this field.

[0006] In the prior art, a utility model with patent publication number CN 220870963 U discloses a multi-energy cogeneration system including energy storage. It mainly solves the regional cooling, heating, electricity and other energy supply needs by coupling the compressed air energy storage system with the regional cooling and heating needs, and achieves the technical problems of reducing the operating costs of cooling and heating and low heat / pressure decoupling. However, its compressed air energy storage adopts the current mainstream adiabatic compression technology solution, which has high compression power consumption. At the same time, the expansion reheat temperature is affected by the insufficient compression heat temperature, and the electricity-to-electricity conversion efficiency in the whole system is not high. Summary of the invention

[0007] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to propose an industrial waste heat coupled isothermal non-supplementary compressed air energy storage system, which stores low-period electrical energy in compressed gas through isothermal compression and reduces electrical energy losses, while fully coupling industrial waste heat to heat compressed gas to realize expansion and power generation by the expander; the present invention makes full use of industrial waste heat, while reducing the power consumption and electrical energy losses of the compressor in the adiabatic compression stage, thereby improving the energy utilization rate of the compressed energy storage system as a whole.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] An industrial waste heat coupled isothermal non-supplementary compressed air energy storage system comprises an isothermal compression energy storage module, an isothermal compression heat recovery module, an industrial waste heat conversion module, and an expansion power generation module. The isothermal compression energy storage module utilizes valley period electricity to realize multi-stage air compression and store compressed gas. The isothermal compression heat recovery module is used to collect the compression heat generated by the multi-stage air compression of the isothermal compression energy storage module. The expansion power generation module receives the industrial waste heat stored in the industrial waste heat conversion module and uses it for the compressed gas expansion power generation.

[0010] Furthermore, the isothermal compression energy storage module comprises an nth (n=1, 2, ..., n)th compressor unit, a qth (q=1, 2, ..., n-1)th heat exchange unit, a cooling unit, an air storage unit and an intake pipe, each compressor unit comprises a compressor unit and a motor, each compressor unit comprises an sth (s=1, 2, ..., s)th compressor, and each compressor of each compressor unit is axially connected in series; the outside air enters the first compressor unit and the first heat exchange unit, the second compressor unit and the second heat exchange unit, ..., the n-1th compressor unit and the n-1th heat exchange unit, the nth compressor unit, the cooling unit in sequence through the intake pipe, and finally enters the storage unit. The air unit realizes air compression and storage; after passing through each compressor of the nth (n=1, 2, ..., n-1)th compressor unit, the outside air first passes through the corresponding nth (n=1, 2, ..., n-1)th heat exchange unit for heat exchange before entering the next compressor; the motor in the nth (n=1, 2, ..., n)th compressor unit is connected to the compressor group to realize the air boosting function; the qth (q=1, 2, ..., n-1)th heat exchange unit includes a heat exchanger to realize the recovery and utilization of the compression heat generated by each compressor of the nth (n=1, 2, ..., n-1)th compressor unit; the cooling unit includes a cooler to realize the heat exchange cooling of each compressor in the nth compressor unit.

[0011] Furthermore, the isothermal compression heat recovery module includes a condensate water network, a lithium bromide unit and / or an absorption heat pump unit, one side of the lithium bromide unit is connected in series with the condensate water network to form a closed loop, the other side of the lithium bromide unit is connected in series with the cooling network, and the lithium bromide unit is connected in parallel with the qth (q=1, 2, ..., n-1) heat exchange unit through the condensate water network; one side of the absorption heat pump unit is connected in series with the condensate water network to form a closed loop, the other side of the absorption heat pump unit is connected in series with the steam network, and the absorption heat pump unit is connected in parallel with the qth (q=1, 2, ..., n-1) heat exchange unit through the condensate water network.

[0012] Furthermore, the industrial waste heat conversion module includes a flue gas heat exchanger, a high-temperature storage tank, a multi-stage reheater, a low-temperature storage tank and a circulation pipeline. The flue gas heat exchanger is connected in series with the high-temperature storage tank, the multi-stage reheater and the low-temperature storage tank in sequence through the circulation pipeline to form a closed loop. The multi-stage reheater includes the mth (m=1, 2, ..., m)th reheater, and each reheater in the mth (m=1, 2, ..., m)th reheater is connected in parallel. The high-temperature flue gas outlet of the industrial waste heat is connected to the input end of the flue gas heat exchanger. The high-temperature flue gas of the industrial waste heat transfers heat to the heat exchange medium in the circulation pipeline through the flue gas heat exchanger. The heat exchange medium stores the heat in the high-temperature storage tank. When needed, the heat exchange medium transfers the heat to the expansion power generation module through the mth (m=1, 2, ..., m)th reheater in sequence.

[0013] Furthermore, the expansion power generation module comprises an mth (m=1, 2, ..., m)th expansion machine unit, a generator and an air outlet pipe, each expansion machine unit is axially connected in series, the power output end of the first expansion machine unit is connected to the power input end of the generator, the air outlet pipe is connected to the gas storage unit, the first reheater, the first expansion machine unit, the second reheater, the second expansion machine unit, ..., the mth reheater, the mth expansion machine unit in sequence, and each expansion machine unit comprises an expansion machine group; the compressed air in the gas storage unit passes through the first reheater, the first expansion machine unit, the second reheater, the second expansion machine unit, ..., the mth reheater, the mth expansion machine unit in sequence through the air outlet pipe and is finally discharged, and the compressed air is heated at the mth (m=1, 2, ..., m)th reheater and drives the subsequent expansion machine unit to work and generate electricity.

[0014] Furthermore, the number of stages s of each compressor group in each compressor unit is 3 to 7, and the outlet air temperature of each compressor unit is 80-105°C.

[0015] Furthermore, the gas storage unit includes a gas storage container, and the gas storage container is divided into an above-ground gas storage container and an underground gas storage container.

[0016] Furthermore, the inlet and outlet temperatures of the driving heat source of the lithium bromide unit are 90-100°C and 80-90°C respectively, and the inlet and outlet temperatures of the cold water of the lithium bromide unit are 5-8°C and 10-15°C respectively.

[0017] Furthermore, the waste hot water inlet temperature of the absorption heat pump unit is 55-140° C., and the saturated steam pressure generated by the absorption heat pump unit is 0.04-0.28 MPa.

[0018] Furthermore, the temperature gradient of the industrial waste heat is above 220°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The power consumption of the isothermal compression method in the isothermal compression energy storage module is significantly lower than that of polytropic compression and adiabatic compression. The isothermal compression method has higher compression efficiency, lower exhaust temperature, and less compression heat, which can reduce heat loss. At the same time, the isothermal compression method reduces power consumption through multi-stage compression and improves system efficiency.

[0021] 2. The compression heat generated by the isothermal compression method in the isothermal compression energy storage module can be used for refrigeration of the lithium bromide unit in the isothermal compression heat recovery module to meet the cooling needs of production and life. The compression heat can also enter the absorption heat pump unit to increase the temperature level, produce saturated steam, and enter the factory steam pipeline network for production use, thereby improving the utilization rate of compression heat in the isothermal compression energy storage module and ensuring the complete and effective recovery of surplus energy.

[0022] 3. Through the coupling of the industrial waste heat conversion module and the expansion power generation module, the preheating of the compressed gas entering the expander to do work is completely provided by the industrial waste heat, which effectively improves the quality of the compressed air entering the expander to do work and improves the working capacity of the expander. At the same time, the industrial waste heat is also fully and reasonably utilized, which improves the electricity-to-electricity conversion efficiency in this system and effectively achieves energy saving.

[0023] To summarize, the present invention uses isothermal compressor technology to compress air, improves the efficiency of compressed air energy storage technology, and reduces the power consumption of the adiabatic compression process. At the same time, it makes full use of industrial waste heat to heat the compressed air in the expansion stage, making up for the lack of compression heat in the isothermal compression process and the inability to meet the defects of compressed air preheating in the energy release process. The present invention uses industrial waste heat coupled isothermal non-supplementary compressed air energy storage system, which has more efficient energy storage efficiency and energy-saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the industrial waste heat coupled isothermal non-supplementary combustion compressed air energy storage system of the present invention.

[0025] Figure 2 PV diagrams for different thermodynamic cycles. DETAILED DESCRIPTION

[0026] The present invention rationally utilizes industrial waste heat, realizes waste heat recovery and utilization, and perfectly couples with the compressed air energy storage system, applying industrial waste heat to the isothermal non-flammable compressed air energy storage system, effectively solving the problems existing in the adiabatic compressed air energy storage technology, improving the energy conversion efficiency, and improving the feasibility of the isothermal non-flammable compressed air energy storage technology.

[0027] Combine the following Figure 1 to Figure 2 The present invention is described in further detail:

[0028] like Figure 1As shown, an industrial waste heat coupled isothermal non-supplementary compressed air energy storage system includes an isothermal compression energy storage module, an isothermal compression heat recovery module, an industrial waste heat conversion module, and an expansion power generation module. The isothermal compression energy storage module uses low-period electricity to achieve multi-stage air compression and store compressed gas. The isothermal compression heat recovery module is used to collect the compression heat generated by the multi-stage air compression of the isothermal compression energy storage module. The expansion power generation module receives the industrial waste heat stored in the industrial waste heat conversion module and uses it for the compressed gas expansion power generation.

[0029] Furthermore, the isothermal compression energy storage module comprises an nth (n=1, 2, ..., n)th compressor unit, a qth (q=1, 2, ..., n-1)th heat exchange unit, a cooling unit, an air storage unit and an intake pipe, each compressor unit comprises a compressor unit and a motor, each compressor unit comprises an sth (s=1, 2, ..., s)th compressor, and each compressor of each compressor unit is axially connected in series; the outside air enters the 1st compressor unit and the 1st heat exchange unit, the 2nd compressor unit and the 2nd heat exchange unit, ..., the n-1th compressor unit and the n-1th heat exchange unit, the nth compressor unit, and the cooling unit in sequence through the intake pipe, and finally enters the air storage unit to realize air compression and storage.

[0030] At the same time, after passing through each compressor of the nth (n=1, 2, ..., n-1)th compressor unit, the outside air first passes through the corresponding nth (n=1, 2, ..., n-1)th heat exchange unit for heat exchange before entering the next compressor. The exhaust temperature of each compressor is between 80 and 105°C. The compression heat generated after each compressor of each compressor unit compresses the air is absorbed by the heat exchange unit to ensure that the intake temperature of the next compressor is between 30 and 40°C. This method can achieve isothermal compression of each compressor and reduce power loss; the motor in the nth (n=1, 2, ..., n)th compressor unit is connected to the compressor group to realize the air boosting function; the qth (q=1, 2, ..., n-1)th heat exchange unit includes a heat exchanger to realize the recovery and utilization of the compression heat generated by each compressor of the nth (n=1, 2, ..., n-1)th compressor unit; the cooling unit includes a cooler to realize heat exchange cooling of each compressor in the nth compressor unit.

[0031] The isothermal compression energy storage module is used to realize the functions of air compression and storage. In order to ensure the realization of isothermal compression, the nth (n=1, 2, ..., n) compressor units are generally connected in series. The number of stages s of each compressor unit in each compressor unit is 3 to 7, and the outlet air temperature of each compressor unit is 80-105°C. The number of compressor stages n in the isothermal compression energy storage module is determined according to the storage pressure level flow of the system design, and is generally 10 to 20 stages.

[0032] The gas storage unit includes a gas storage container, which is used to store the high-pressure gas generated by the compressor unit. The gas storage container is divided into above-ground gas storage containers (including steel storage tanks, pipeline steel, etc.) and underground gas storage containers (including underground salt caverns, artificial chambers, etc.). The gas storage container is determined according to the project scale and the actual conditions of the location. The gas storage pressure bearing capacity of the gas storage container is higher than the pressure of the stored compressed air, and a certain design margin is considered.

[0033] At the same time, in order to ensure that the inlet air temperature of each compressor stage in each compressor unit is low, a heat exchange unit is connected to the outlet of each compressor stage of the nth (n=1, 2, ..., n-1) compressor unit for heat exchange to ensure that the inlet air temperature of the next compressor stage is between 30 and 40°C; a cooler is connected to the outlet of each compressor stage of the nth compressor unit to adjust the temperature of the compressed air that finally enters the air storage unit, and the heat generated by the nth compressor unit is not used for recovery.

[0034] After being compressed by each stage of the multi-stage compressor unit, the air pressure and temperature increase. Before entering the next stage of the compressor unit, it is first subjected to heat exchange through the corresponding heat exchange unit, which can transfer the heat in the air to the condensate. After absorbing the compression heat, the condensate temperature reaches about 100°C and enters the lithium bromide unit as a driving heat source to produce chilled water for cooling the factory or building. The isothermal compression energy storage module and the isothermal compression heat recovery module realize the reuse of compression heat and increase the demand for cooling, thereby improving the overall efficiency of the system.

[0035] Furthermore, the isothermal compression heat recovery module includes a condensate water network, a lithium bromide unit and / or an absorption heat pump unit, one side of the lithium bromide unit is connected in series with the condensate water network to form a closed loop, the other side of the lithium bromide unit is connected in series with the cooling network, and the lithium bromide unit is connected in parallel with the qth (q=1, 2, ..., n-1) heat exchange unit through the condensate water network; one side of the absorption heat pump unit is connected in series with the condensate water network to form a closed loop, the other side of the absorption heat pump unit is connected in series with the steam network, and the absorption heat pump unit is connected in parallel with the qth (q=1, 2, ..., n-1) heat exchange unit through the condensate water network.

[0036] The condensed water in the condensate network is subjected to the pump pressure of the condensate pump and enters the qth (q=1, 2, ..., n-1)th heat exchange unit for compression heat exchange. After the temperature of the condensed water rises, it enters the lithium bromide unit and / or the absorption heat pump unit for compression heat recovery and conversion. After the temperature of the condensed water drops, the condensed water enters the qth (q=1, 2, ..., n-1)th heat exchange unit again through the condensate pump for heat exchange to complete the heat cycle. The hot water in the cooling network is refrigerated by the lithium bromide unit and then enters the chilled water demand end of the cooling network for use. The medium-temperature water in the steam network is heated by the absorption heat pump unit to generate steam and enters the steam demand end for use.

[0037] Furthermore, the industrial waste heat conversion module comprises a flue gas heat exchanger, a high temperature storage tank, a multi-stage reheater, a low temperature storage tank and a circulation pipeline. The flue gas heat exchanger is connected in series with the high temperature storage tank, the multi-stage reheater and the low temperature storage tank in sequence through the circulation pipeline to form a closed loop. The multi-stage reheater comprises an mth (m=1, 2, ..., m)th stage reheater, and each stage reheater in the mth (m=1, 2, ..., m)th stage reheater is connected in parallel. The high temperature flue gas outlet of the industrial waste heat is connected to the flue gas heat exchanger. The input end of the heat exchanger is connected; when storing industrial waste heat, the hot water storage pump pumps the heat exchange medium from the low-temperature storage tank to the high-temperature storage tank. In this process, the high-temperature flue gas of the industrial waste heat transfers heat to the heat exchange medium in the circulation pipeline through the flue gas heat exchanger. The heat exchange medium stores the heat in the high-temperature storage tank. The heat exchange medium generally uses heat transfer oil. When it is needed, the hot water pump will pump the heat exchange medium through the mth (m=1, 2, ..., m) reheater in sequence to transfer the heat to the expansion power generation module.

[0038] Furthermore, the expansion power generation module comprises an mth (m=1, 2, ..., m)th expansion machine unit and an outlet pipe of a generator, each expansion machine unit is axially connected in series, the power output end of the first expansion machine unit is connected to the power input end of the generator, the outlet pipe is connected to the gas storage unit, the first reheater, the first expansion machine unit, the second reheater, the second expansion machine unit, ..., the mth reheater, and the mth expansion machine unit in sequence, and each expansion machine unit comprises an expansion machine group; the compressed air in the gas storage unit passes through the first reheater, the first expansion machine unit, the second reheater, the second expansion machine unit, ..., the mth reheater, and the mth expansion machine unit in sequence through the outlet pipe and is finally discharged; the compressed air is heated at the mth (m=1, 2, ..., m)th reheater and drives the subsequent expansion machine unit to generate power; the compressed air is heated, cooled, and reheated to generate power through a continuous cycle, thereby realizing the power generation function of the expansion power generation module.

[0039] In a general expansion power generation module, the number m of the mth (m=1, 2, ..., m) expansion machine units involved in the heating and expansion work process is between 2 and 4; before the 40°C low-temperature and high-pressure compressed air in the gas storage container enters the first expansion machine unit through the air inlet pipe of the multi-stage expansion machine unit, the compressed air is heated to 320°C by the reheater to drive the expansion unit to work, thereby achieving medium and high temperature expansion, improving the quality of the compressed air, and improving the work capacity of the expander; the temperature and pressure of the compressed air that has worked in the first expansion machine unit are reduced, and then the temperature is increased to 320°C again after being heated by the second reheater, driving the second expansion machine unit to work and generate electricity, and the temperature and pressure of the compressed air output by the second expansion machine unit are further reduced after working, and so on, the temperature and pressure of the compressed air after multiple expansion works are reduced to the discharge conditions and then directly discharged, and at the same time, the heat exchange medium from the high-temperature storage tank is reduced to 40-50°C after heat exchange and then enters the low-temperature storage tank for storage, forming a heat cycle of the industrial waste heat conversion module.

[0040] Furthermore, the inlet and outlet temperatures of the driving heat source of the lithium bromide unit are 90-100°C and 80-90°C respectively, and the inlet and outlet temperatures of the cold water of the lithium bromide unit are 5-8°C and 10-15°C respectively.

[0041] Furthermore, the waste hot water inlet temperature of the absorption heat pump unit is 55-140° C., and the saturated steam pressure generated by the absorption heat pump unit is 0.04-0.28 MPa.

[0042] The lithium bromide unit or absorption heat pump unit operates with the low-grade compression heat in the isothermal compression process as the driving heat source. It can absorb heat from the low-grade compression heat source to produce hot water, steam and cold water products that meet the production process requirements or heating needs, effectively recycle and utilize low-temperature thermal energy, and have good energy-saving effects.

[0043] Furthermore, the industrial waste heat has a temperature gradient of more than 220°C, such as the flue gas waste heat of sintering ducts in steel enterprises, the hot exhaust gas waste heat of ring coolers, and the flue gas waste heat of hot blast furnaces.

[0044] The steel industry sintering waste heat includes the flue gas waste heat from the second or third ring cooling stage of a typical sintering line in the metallurgical industry process, and its temperature and flue gas volume are suitable for air preheating in the expansion stage.

[0045] The formula for compression power consumption in different thermodynamic cycles is as follows:

[0046]

[0047] In formula (1), Wc is the compression power consumption, J; p2 is the compressed air pressure, Pa; p1 is the initial pressure of the air in the pressure vessel, Pa; V2 is the initial air volume, m 3; V1 is the volume of compressed air, m 3 .

[0048] From formula (1) and Figure 2 it can be seen that: the indicated work of the isothermal compression theoretical cycle Wdb is represented by the area d-a-db-c-d, the indicated work of the adiabatic compression theoretical cycle Wjb is represented by the area d-a-jb-c-d, and the indicated work of the polytropic compression theoretical cycle Wbb is represented by the area d-a-bb-c-d. It can be seen that Wdb < Wbb < Wjb, and the indicated work of the isothermal compression theoretical cycle is the smallest.

[0049] Embodiment 1

[0050] In this Embodiment 1, the isothermal compression energy storage module adopts 10 compressor units and 9 heat exchange units. Each compressor unit includes a compressor and an electric motor. Each compressor adopts an axial flow or centrifugal compressor. The compression ratio of each compressor is 1.47 - 1.8, the flow rate is 100 - 120 kg / s, and the power is 5315 - 7556 kW. Each heat exchange unit includes a heat exchanger, and the heat exchanger can adopt a shell-and-tube or hairpin type gas-liquid heat exchanger; among them, the 10th compressor unit has an adjustment function and can adjust the final exhaust pressure of the compressor, and the exhaust pressure is 12 - 14 MPa.

[0051] Each cycle of the isothermal compression energy storage module compresses and stores energy for 8 hours, and the compressed air storage pressure is 12 - 14 MPa; in the expansion power generation module, the expansion releases energy for 4 hours, and the expansion release pressure is 12 MPa.

[0052] Since the outlet temperature of the isothermal compression basically remains at about 102 °C and the quality is relatively low, the isothermal compression heat recovery module adopts a lithium bromide unit to receive the compression heat released by the compressed air to drive the lithium bromide unit for refrigeration to solve the chilled water demand of the plant area.

[0053] In the industrial waste heat conversion module, the industrial waste heat adopts the sintering waste heat of the iron and steel industry, specifically the flue gas waste heat of the second stage of the ring cooler in the typical sintering line in the metallurgical industrial process. After the sintering ring cooler system completes heat exchange with the sintered ore, it forms high-temperature flue gas at 340 - 360 °C, and the corresponding flue gas flow rate is 220000 - 400000 Nm 3 / h. The high-temperature flue gas enters the flue gas heat exchanger through the high-temperature flue gas outlet, transfers the high-temperature waste heat in the flue gas to the heat exchange medium from the low-temperature storage tank. The heat exchange medium generally adopts heat-conducting oil. After the high-temperature flue gas exchanges heat and its temperature decreases, it is discharged to reduce energy waste; the heat exchange medium from the low-temperature storage tank exchanges heat in the flue gas heat exchanger, and the temperature of the heat exchange medium rises to 320 - 340 °C. The heated heat exchange medium enters the high-temperature storage tank for heat energy storage to be used for heating the compressed air entering the expander during the energy release process of the expansion power generation module.

[0054] The multi-stage expander unit in the expansion power generation module adopts the first to fourth stage expander units, wherein the expander group adopts an axial flow or centripetal turbine.

[0055] By carrying out energy efficiency analysis and calculation through Example 1, the calculation results are compared with the energy efficiency of the traditional adiabatic non-supplementary compressed air energy storage system, proving that the efficiency of the compressed air energy storage system proposed by the present invention is better. The calculation results are as follows:

[0056] (1) Analysis of the total effective heat of flue gas waste heat in the industrial waste heat conversion stage

[0057] This case uses a 200m 2 The waste heat from the second stage of the sintering ring cooler is used to supplement the heat of the 100MW isothermal non-supplementary compressed air energy storage system. The temperature of the compressed air at the expander inlet can be increased to 280°C through heat supplementation, thereby effectively increasing the total amount of expansion energy released.

[0058] The calculation formula for the effective total heat of sintering flue gas in the industrial waste heat conversion module is as follows:

[0059] M1=Q1×h1 (2)

[0060] In formula (2), M1 represents the total effective heat of sintering flue gas, kWh; Q1 represents the available power after heat exchange, kW; h1 represents the flue gas release time, h.

[0061] Among them, the calculation formula of the power after heat exchange that can be used in the total effective heat of sintering flue gas is as follows:

[0062] Q1=C P1 ×(T 烟2 -T 烟1 )×q 烟 (3)

[0063] In formula (3), C P1 represents the heat capacity of flue gas, kJ / kg.K; T2 represents the sintering flue gas temperature, K; T1 represents the flue gas temperature after heat exchange, K; q 烟 Represents the sintering flue gas flow rate, kg / s.

[0064] After calculation, the total effective heat of sintering flue gas is M1=Q1×h1=17516.38×24=420393.12kWh.

[0065] The specific parameters of the second stage flue gas of the sintering ring cooler are shown in Table 1:

[0066] Table 1 Specific parameters of the second stage flue gas of the sintering ring cooler

[0067] Serial number parameter unit Numeric 1 <![CDATA[Sintering flue gas temperature T 烟2 > k 603 2 <![CDATA[Flue gas temperature T after heat exchange 烟1 > k 333 3 <![CDATA[Sintering flue gas flow rate q 烟 > kg / s 79.02 4 <![CDATA[Flue gas heat capacity C P1 > kJ / kg.K 1.07 5 Sintering flue gas power kW 21895.47 6 <![CDATA[The available power Q1 after heat exchange]]> kW 17516.38

[0068] (2) Analysis of the heat required for the expansion process of compressed air to release energy during the expansion power generation stage

[0069] The total heat required to release energy by expanding compressed air is calculated as follows:

[0070] M2=Q2×h2 (4)

[0071] In formula (4), M2 represents the total heat required to release the energy of compressed air expansion, kWh; Q2 represents the power required to release the energy of compressed air expansion, kW; h2 represents the expansion time, h.

[0072] Among them, the power required for the compressed air energy release and expansion process is calculated as follows:

[0073] Q2=C P2 ×(T2-T1)×q (5)

[0074] In formula (5), C P2 represents the specific heat of compressed air, kJ / kg.K; T2 represents the exhaust temperature, k; T1 represents the intake temperature, K; T2-T1 represents the temperature rise, K; q represents the mass flow rate of compressed air, kg / s.

[0075] After calculation, the total heat required for compressed air expansion and energy release is M2=Q2×h2=102521.68×4=410086.72kWh.

[0076] The specific parameters of the total power required for the compressed air energy release and expansion process are shown in Table 2:

[0077] Table 2 Total power parameters required for compressed air energy release and expansion process

[0078]

[0079] From the above calculations, it can be seen that for a 100MW compressed air energy storage system, the total heat required to heat the high-pressure air entering the expander to 280°C during the energy release process is 410086.72kWh. The effective total calorific value of the second-stage sintering flue gas of the sintering ring cooler in the metallurgical process (net value from 330°C to 60°C, and considering heat loss) is 420393.12kWh. The sintering waste heat is greater than the expansion heat required by the expander. The waste heat from the second stage of sintering can fully ensure the reliable and efficient operation of the energy storage system.

[0080] (3) Analysis of total power consumption during isothermal compression

[0081] Calculation of the compression process, total compression power: 59895.93kW, detailed calculation results are as follows:

[0082] The total power consumption during compression is calculated as follows:

[0083] W1=K1×N1×h1 (6)

[0084] In formula (6), W1 represents the total power consumption of compression, kWh; K1 represents the compression power loss coefficient;

[0085] N1 represents the total compression power, kW; h1 represents the compression time, h.

[0086] After calculation, the total compression power consumption W1=K1×N1×h1=1.04×59895.93×8=498334.14kWh.

[0087] The specific parameters of the multi-stage compressor unit in the isothermal compression stage are shown in Table 3:

[0088] Table 3 Specific parameters of multi-stage compressor unit in isothermal compression stage

[0089]

[0090] Table 3:

[0091]

[0092] (4) Analysis of total power generation during expansion energy release

[0093] The calculation formula of total power generation of expansion energy is as follows:

[0094] W2=K2×N2×h2 (7)

[0095] In formula (7), W2 represents the total power generation of expansion energy release, kWh; K2 represents the expansion power loss coefficient; N2 represents the total expansion power, kW; h2 represents the expansion time, h.

[0096] In this embodiment, a four-stage expansion process is used to release energy. After calculation, the total power generation of expansion energy is W2 = K2 × N2 × h2 = 0.96 × 98140.17 × 4 = 376858.25 kWh.

[0097] The specific parameters of the total power generation of expansion energy release are shown in Table 4:

[0098] Table 4 Specific parameters of total power generation of expansion energy release

[0099]

[0100] The calculation formula of the electric-to-electric conversion efficiency between compression energy storage and expansion power generation in this system is as follows:

[0101] η1=W2÷W1 (8)

[0102] In formula (8), η1 represents the electricity-to-electricity conversion efficiency, W2 represents the total power generation of expansion energy release, kWh, and W1 represents the total power consumption of compression, kWh.

[0103] Combined with the above calculation results, the electricity-to-electricity conversion efficiency between compression energy storage and expansion power generation in this system is specifically η1=W2÷W1=376858.25÷498334.14=75.6%.

[0104] According to calculations, the electric-to-electric conversion efficiency of the second-stage sintering waste heat coupled with the non-supplementary isothermal compressed air energy storage technology reaches 75.6%, which is much higher than the electric-to-electric conversion efficiency of the existing conventional adiabatic non-supplementary compressed air energy storage technology (generally around 50%). After considering the heat storage and heat exchange losses, the system can be fully guaranteed to operate reliably and efficiently. The total amount of electricity released by expansion after heat supplementation increases, and the electric-to-electric conversion efficiency is significantly improved, effectively improving energy utilization.

[0105] (5) Analysis of compression heat utilization in isothermal compression stage:

[0106] The total heat calculation formula for the compression process is as follows:

[0107] M3=Q3×h3 (9)

[0108] In formula (9), M3 represents the total heat of the compression process, kWh; Q3 represents the power of the compression process, kW; h3 represents the compression time, h;

[0109] After calculation, the total heat of the compression process is M3=Q3×h3=46985.25×8=375882kWh.

[0110] The specific parameters of the total heat that can be stored during the compression process are shown in Table 5:

[0111] Table 5 Parameters of total heat storage during compression

[0112]

[0113] Table 5 continued:

[0114]

[0115] During the isothermal compression process, the gas temperature rise is small and the compression heat quality is not high. Combined with the exhaust temperature characteristics, this part of the compression heat can be used for the following applications:

[0116] ① Produce chilled water through lithium bromide units for refrigeration in the factory area;

[0117] ② Use lithium bromide units to produce medium-temperature water for heating in the factory area;

[0118] ③ Improve the quality of heat source through heat pump technology, and use it for process flow or other purposes with heat demand;

[0119] ④Heat process condensate to improve the circulation thermal efficiency of the boiler system.

[0120] (6) Refrigeration analysis of lithium bromide unit in isothermal compression heat recovery stage:

[0121] The calculation formula of available heat of lithium bromide unit is as follows:

[0122] M4=M3*η (10)

[0123] In formula (10), M3 represents the total heat of the compression process, kWh; M4 represents the heat available after heat exchange, kWh; η represents the efficiency of the steam-water heat exchanger.

[0124] According to calculation, the heat that can be utilized by the lithium bromide unit is M4=M3*η=375882*0.7=263117.4kWh.

[0125] The driving heat source water flow is 2819m 3 / h, according to the driving heat source water volume, the existing lithium bromide unit can be selected. According to the unit scale and parameters, the cooling capacity is determined to be about 24552kW. According to the building cooling index of 120W / m 2 , it can be calculated that the cooling area is about 200,000 m 2 .

[0126] Embodiment 2

[0127] In this embodiment 2, a 265m 2 The waste heat of the flue gas from the three stages of the sintering ring cooler is used to supplement the heat of the 100MW isothermal non-supplementary compressed air energy storage system. The inlet temperature of the expander can be increased to about 170°C through heat supplementation, thereby effectively increasing the total amount of electricity released by expansion. In this embodiment 2, 10 stages of compression and 3 stages of expansion are used. The flue gas parameters and related calculation tables are as follows. The calculation process refers to Case 1.

[0128] (1) Metallurgical process 265m 2 The three-stage flue gas parameters and power calculation of the sintering ring cooler are shown in Table 6:

[0129] Table 6 265m 2 Sintering ring cooler three-stage flue gas parameters and power calculation table

[0130]

[0131]

[0132] (2) The power required for the energy release expansion process is calculated as shown in Table 7:

[0133] Table 7 Calculation table of power required for energy release and expansion process

[0134]

[0135] (3) Calculation of isothermal compression process, total compression power: 70707.65kW, detailed calculation results are shown in Table 8:

[0136] Table 8 Isothermal compression process calculation table

[0137]

[0138] Table 8 continued:

[0139]

[0140] (4) The expansion process uses three-stage expansion energy release, and the total expansion power is 102199.31 kW. The detailed parameters are shown in Table 9:

[0141] Table 9 Three-stage expansion energy release calculation table

[0142]

[0143] (5) The storable power during isothermal compression is 56382.3 kW, as shown in Table 10:

[0144] Table 10 Calculation of heat storage capacity during isothermal compression process

[0145]

[0146] Table 10 continued:

[0147]

[0148] (6) Using absorption heat pump to increase energy and produce process steam analysis:

[0149] According to the analysis in the above formula (10), the available heat of the absorption heat pump is 315740.9 kWh.

[0150] If the coefficient of performance of the heat pump is 0.5, the steam power that can be produced is 157870.45kW. Assuming that saturated steam at 120℃ and 0.2Mpa is produced, the amount of saturated steam at 0.2MPa that can be provided is 26.24t / h.

[0151] The working principle of the present invention is as follows:

[0152] The multi-stage compressor unit in the isothermal compression energy storage module uses low-peak electricity to achieve multi-stage air compression, and transmits the generated compression heat to the isothermal compression heat recovery module through the multi-stage heat exchange unit. At the same time, the high-pressure air after multi-stage compression is stored in the air storage container; the isothermal compression heat recovery module utilizes the compression heat provided by the multi-stage heat exchange unit through the lithium bromide unit and (or) absorption heat pump unit; the industrial waste heat conversion module absorbs the industrial waste heat through the flue gas heat exchanger and stores it in the high-temperature storage tank, and provides air preheating for the expansion power generation stage through the multi-stage reheater; the multi-stage expander unit in the expansion power generation module uses the preheated high-pressure air to expand and generate electricity, thereby realizing energy conversion.

Claims

1. An industrial waste heat coupled isothermal non-supplementary compressed air energy storage system, comprising an isothermal compression energy storage module, an isothermal compression heat recovery module, an industrial waste heat conversion module, and an expansion power generation module, characterized in that: The isothermal compression energy storage module utilizes the off-peak electric energy to realize multi-stage air compression and store the compressed gas. The isothermal compression heat recovery module is used to collect the compression heat generated by the isothermal compression energy storage module during the multi-stage air compression. The expansion power generation module receives the industrial waste heat stored in the industrial waste heat conversion module and uses it for the compressed gas expansion power generation.

2. The compressed air energy storage system according to claim 1, characterized in that: The isothermal compression energy storage module comprises an nth (n=1, 2, ..., n)th compressor unit, a qth (q=1, 2, ..., n-1)th heat exchange unit, a cooling unit, an air storage unit and an intake pipe, each compressor unit comprises a compressor unit and a motor, each compressor unit comprises an sth (s=1, 2, ..., s)th compressor, and each compressor of each compressor unit is axially connected in series; the outside air enters the first compressor unit and the first heat exchange unit, the second compressor unit and the second heat exchange unit, ..., the n-1th compressor unit and the n-1th heat exchange unit, the nth compressor unit, the cooling unit in sequence through the intake pipe, and finally enters the air storage unit Air compression and storage are achieved; after passing through each compressor of the nth (n=1, 2, ..., n-1)th compressor unit, the outside air first exchanges heat through the corresponding nth (n=1, 2, ..., n-1)th heat exchange unit before entering the next compressor; the motor in the nth (n=1, 2, ..., n)th compressor unit is connected to the compressor group to achieve the air boosting function; the qth (q=1, 2, ..., n-1)th heat exchange unit includes a heat exchanger to achieve the recovery and utilization of the compression heat generated by each compressor of the nth (n=1, 2, ..., n-1)th compressor unit; the cooling unit includes a cooler to achieve heat exchange cooling of each compressor in the nth compressor unit.

3. The compressed air energy storage system according to claim 1, characterized in that: The isothermal compression heat recovery module comprises a condensate network, a lithium bromide unit and / or an absorption heat pump unit. One side of the lithium bromide unit is connected in series with the condensate network to form a closed loop, and the other side of the lithium bromide unit is connected in series with the cooling network. The lithium bromide unit is connected in parallel with the qth (q=1, 2, ..., n-1) heat exchange unit through the condensate network; one side of the absorption heat pump unit is connected in series with the condensate network to form a closed loop, and the other side of the absorption heat pump unit is connected in series with the steam network. The absorption heat pump unit is connected in parallel with the qth (q=1, 2, ..., n-1) heat exchange unit through the condensate network.

4. The compressed air energy storage system according to claim 1, characterized in that: The industrial waste heat conversion module includes a flue gas heat exchanger, a high-temperature storage tank, a multi-stage reheater, a low-temperature storage tank and a circulation pipeline. The flue gas heat exchanger is connected in series with the high-temperature storage tank, the multi-stage reheater and the low-temperature storage tank in sequence through the circulation pipeline to form a closed loop. The multi-stage reheater includes the mth (m=1, 2, ..., m)th stage reheater, and each stage reheater in the mth (m=1, 2, ..., m)th stage reheater is connected in parallel. The high-temperature flue gas outlet of the industrial waste heat is connected to the input end of the flue gas heat exchanger. The high-temperature flue gas of the industrial waste heat transfers heat to the heat exchange medium in the circulation pipeline through the flue gas heat exchanger. The heat exchange medium stores the heat in the high-temperature storage tank. When needed, the heat exchange medium transfers the heat to the expansion power generation module through the mth (m=1, 2, ..., m)th stage reheater in sequence.

5. The compressed air energy storage system according to claim 1, characterized in that: The expansion power generation module comprises an mth (m=1, 2, ..., m)th expansion machine unit, a generator and an air outlet pipe, each expansion machine unit is axially connected in series, the power output end of the first expansion machine unit is connected to the power input end of the generator, the air outlet pipe is connected in sequence to the gas storage unit, the first reheater, the first expansion machine unit, the second reheater, the second expansion machine unit, ..., the mth reheater, the mth expansion machine unit, each expansion machine unit comprises an expansion machine group; the compressed air in the gas storage unit passes through the first reheater, the first expansion machine unit, the second reheater, the second expansion machine unit, ..., the mth reheater, the mth expansion machine unit in sequence through the air outlet pipe and is finally discharged, and the compressed air is heated at the mth (m=1, 2, ..., m)th reheater and drives the subsequent expansion machine unit to work and generate electricity.

6. The compressed air energy storage system according to claim 2, characterized in that: The number of stages s of each compressor group in each compressor unit is 3 to 7, and the outlet air temperature of each compressor unit is 80-105°C.

7. The compressed air energy storage system according to claim 2, characterized in that: The gas storage unit comprises a gas storage container, and the gas storage container comprises an above-ground gas storage container or an underground gas storage container.

8. The compressed air energy storage system according to claim 3, characterized in that: The inlet and outlet water temperatures of the driving heat source of the lithium bromide unit are 90-100°C and 80-90°C respectively, and the inlet and outlet water temperatures of the cold water of the lithium bromide unit are 5-8°C and 10-15°C respectively.

9. The compressed air energy storage system according to claim 3, characterized in that: The waste water inlet temperature of the absorption heat pump unit is 55-140° C., and the saturated steam pressure generated by the absorption heat pump unit is 0.04-0.28 MPa.

10. The compressed air energy storage system according to claim 1, characterized in that: The industrial waste heat temperature gradient is above 220°C.

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