Compressed air energy storage and sludge recycling complementary energy and waste heat coupling utilization process system

Abstract

The utility model discloses a process system for coupling utilization of compressed air energy storage and sludge recycling complementary energy and waste heat. The process system comprises a compressed air energy storage system, a sludge recycling system and a coupling system, the coupling system comprises a first heat exchanger, a second heat exchanger, a third heat exchanger and a dedusting purification device. The compressed air energy storage system comprises an air compression device, an air storage device, an expansion power generation device and a heat storage device; the sludge recycling system comprises a sludge pretreatment device, a sludge drying device and a sludge incineration device. In conclusion, coupling utilization of waste energy and waste heat resources of the two systems is achieved, low-temperature waste heat generated in the compression stage of the compressed air energy storage system is used as a heat source in the sludge recycling system and the sludge drying stage, low-quality waste heat is fully utilized, and meanwhile, energy is saved. High-temperature flue gas generated after sludge drying and incineration serves as a heat storage heat source in the expansion stage of the compressed air energy storage system, and the compressed air power generation efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of sludge resource utilization and compressed air energy storage, and in particular to a process system for coupled utilization of compressed air energy storage and sludge resource utilization surplus energy and waste heat. Background Art

[0002] The wet sludge from domestic municipal sewage plants has a high moisture content and a large amount of sand, with inorganic components accounting for about 60%, resulting in low energy density and volume density of the sludge, that is, low unit calorific value. Regardless of whether it is used for aerobic composting / fermentation, anaerobic fermentation, co-incineration or direct incineration, it has a great impact on the reduction and resource utilization of sludge. In order to achieve sludge reduction, stabilization, harmlessness and resource utilization, the sludge needs to be pretreated and tempered, and the organic and inorganic matter in the sludge need to be separated by chemical and physical methods. The inorganic sludge can be mechanically dehydrated and then utilized as a building material auxiliary resource. The organic sludge with a higher calorific value can reduce the sludge moisture content to 10-15% through mechanical dehydration, thermal drying and other methods, and the calorific value can be increased to 3500-4500KJ / kg. It can be directly incinerated to generate high-quality heat for utilization, thereby achieving the goal of sludge resource utilization. In the process of sludge separation and drying, a large amount of heat and electricity are consumed. If external low-quality waste heat and low-cost electricity can be used to reduce the operating cost of sludge resource utilization, the application scenarios of sludge resource utilization will be more diverse and the economy will be more obvious.

[0003] Major breakthroughs have been made in the research of compressed air energy storage systems in China, and large-scale (300MW and above) demonstration compressed air energy storage projects have been launched one after another. However, compared with other new energy storage methods, the power generation efficiency of compressed air energy storage systems is relatively low (60-70%), and the low-temperature waste heat generated in the air compression process is released and lost through water cooling and is not fully utilized. Therefore, the industry is exploring various technical methods, such as reducing the compressor inlet air temperature, and comprehensively utilizing the waste energy and waste heat in the compressed air and expansion power generation stages, in order to improve the electricity-to-electricity conversion efficiency of compressed air energy storage systems.

[0004] In summary, in specific application scenarios, compressed air energy storage and sludge resource utilization will couple their respective waste energy and waste heat, that is, the waste heat generated by compressed air is used for sludge drying and provides low electricity costs for sludge resource utilization. At the same time, the high-quality waste heat generated by sludge incineration is provided to compressed air for expansion and power generation, thereby improving the overall power generation efficiency. Therefore, how to achieve the coupled utilization of compressed air energy storage and sludge resource utilization waste energy and waste heat is particularly critical. Utility Model Content

[0005] In view of the above-mentioned current situation, the purpose of the present utility model is to provide a process system for coupling the utilization of compressed air energy storage and sludge resource surplus energy and waste heat.

[0006] In order to achieve the above tasks, the utility model adopts the following technical solutions:

[0007] A process system for coupling utilization of compressed air energy storage and sludge resource utilization surplus energy and waste heat, comprising a compressed air energy storage system, a sludge resource utilization system and a coupling system; wherein the coupling system comprises a first heat exchanger, a second heat exchanger, a third heat exchanger and a dust removal and purification device;

[0008] The compressed air energy storage system comprises an air compression device, an air storage device, an expansion power generation device and a heat storage device, wherein the first output end of the air compression device is connected to the input end of the air storage device, and the output end of the air storage device and the output end of the heat storage device are respectively connected to the first input end and the second input end of the expansion power generation device; the second output end of the air compression device is respectively connected to the first input end of the first heat exchanger and the first input end of the heat storage device; the first output end of the expansion power generation device serves as a peak discharge end; the second output end of the expansion power generation device is respectively connected to the second input end of the first heat exchanger and the first input end of the second heat exchanger;

[0009] The sludge resource utilization system includes a sludge pretreatment device, a sludge drying device and a sludge incineration device, wherein the output end of the sludge pretreatment device is connected to the first input end of the sludge drying device, and the output end of the sludge drying device is connected to the input end of the sludge incineration device; the output end of the first heat exchanger and the first output end of the second heat exchanger are both connected to the second input end of the sludge drying device, and the second output end of the second heat exchanger is connected to the input end of the dust removal and purification device; the output end of the sludge incineration device is connected to the input end of the third heat exchanger; the first output end of the third heat exchanger is connected to the second input end of the second heat exchanger, and the second output end of the third heat exchanger is connected to the second input end of the heat storage device.

[0010] Furthermore, the air compression device adopts a compressor, including a large axial flow, centrifugal or combination of the two compressor units.

[0011] Furthermore, the air storage device adopts natural rock caves, artificial concrete chambers or pipeline steel.

[0012] Furthermore, the expansion power generation device adopts an expander turbine unit.

[0013] Furthermore, the medium of the heat storage device is lava or water.

[0014] Compared with the prior art, the utility model has the following technical features:

[0015] 1. Through the efficient use of the low-temperature waste heat generated in the compression stage of the compressed air energy storage system, the originally unusable low-temperature heat energy is recovered through heat exchange and used as one of the low-temperature heat sources for sludge drying. It is used in the sludge drying stage, saving the consumption of internal heat energy for sludge resource utilization.

[0016] 2. The high-temperature flue gas thermal energy generated by sludge incineration is stored in the heat storage unit of the compressed air energy storage system, and the high-temperature flue gas is efficiently utilized. The low-temperature flue gas after heat exchange is also used as one of the low-temperature heat sources for sludge drying. The step-by-step utilization of the high-temperature flue gas thermal energy not only effectively utilizes the waste heat as a heat source for sludge drying, but also improves the overall power generation efficiency of compressed air energy storage, and the effect is very obvious.

[0017] 3. The low-cost electricity generated by the compressed air energy storage system can be used in the sludge resource utilization system to reduce the operating electricity cost of the sludge resource utilization system.

[0018] In summary, the utility model realizes the coupled utilization of the waste energy and waste heat resources of the two systems, and utilizes the low-temperature waste heat generated in the compression stage of the compressed air energy storage system as the heat source of the sludge resource utilization system in the sludge drying stage, making full use of the low-quality waste heat. At the same time, the high-temperature flue gas generated after the sludge drying and incineration is used as the heat storage source of the compressed air energy storage system in the expansion stage, thereby improving the compressed air power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process system of the utility model.

[0020] The present invention is further explained below in conjunction with the accompanying drawings and specific implementation methods. DETAILED DESCRIPTION

[0021] Following the above technical solution, Figure 1 As shown, the utility model provides a process system for coupling the utilization of compressed air energy storage and sludge resource utilization surplus energy and waste heat, including a compressed air energy storage system, a sludge resource utilization system and a coupling system; wherein the coupling system includes a first heat exchanger, a second heat exchanger, a third heat exchanger and a dust removal and purification device;

[0022] The compressed air energy storage system comprises an air compression device, an air storage device, an expansion power generation device, and a heat storage device, wherein the first output end of the air compression device is connected to the input end of the air storage device, and the output end of the air storage device and the output end of the heat storage device are respectively connected to the first input end and the second input end of the expansion power generation device; the second output end of the air compression device is respectively connected to the first input end of the first heat exchanger and the first input end of the heat storage device; the first output end of the expansion power generation device serves as a peak discharge end; the second output end of the expansion power generation device is respectively connected to the second input end of the first heat exchanger and the first input end of the second heat exchanger;

[0023] The sludge resource utilization system includes a sludge pretreatment device, a sludge drying device and a sludge incineration device, as well as supporting public auxiliary units, wherein the output end of the sludge pretreatment device is connected to the first input end of the sludge drying device, and the output end of the sludge drying device is connected to the input end of the sludge incineration device; the output end of the first heat exchanger and the first output end of the second heat exchanger are both connected to the second input end of the sludge drying device, and the second output end of the second heat exchanger is connected to the input end of the dust removal and purification device; the output end of the sludge incineration device is connected to the input end of the third heat exchanger; the first output end of the third heat exchanger is connected to the second input end of the second heat exchanger, and the second output end of the third heat exchanger is connected to the second input end of the heat storage device.

[0024] The above-mentioned devices are specifically selected as follows:

[0025] Air compression devices use compressors, including large axial flow, centrifugal or a combination of the two compressor units.

[0026] The air storage device is selected according to the actual situation of the project, including natural rock caves, artificial concrete chambers, pipeline steel, etc.

[0027] The expansion power generation device adopts an expansion turbine unit;

[0028] The heat storage device selects the medium according to the actual situation, such as high-temperature lava, heat transfer oil, water or a combination of the three.

[0029] The sludge pretreatment device is used for sludge quality classification and modification, which can adopt physical, chemical and other methods; the sludge drying device is used for sludge drying and dehydration.

[0030] The first heat exchanger and the second heat exchanger both use gas / gas heat exchangers; the third heat exchanger uses heat storage media such as high-temperature lava and heat transfer oil.

[0031] In the compressed air energy storage system, in order to improve the overall power generation efficiency of the compressed air system, in addition to improving the efficiency of the equipment in the system, it is necessary to combine the process flow to "squeeze out" the waste energy and waste heat in the system or use external high-quality thermal energy to "empower" the system; the air compression device adopts multi-stage compression, and each stage of air compression generates waste heat. The medium-temperature waste heat generated by compression is stored in the heat storage medium in the heat storage unit and is used for the expansion unit to heat the compressed air. However, the waste heat generated by the last stage of air compression is of low quality (70-90°C). This part of the waste heat is usually dissipated into the environment by air cooling tower heat exchange, and is not fully utilized. The first heat exchanger (air / air heat exchanger) can be used to utilize this part of the waste heat as one of the heat sources for sludge drying.

[0032] In the sludge resource utilization system, sludge drying requires a heat source. External low-grade waste heat (i.e., the heat output by the first heat exchanger and the second heat exchanger) can be used to save the consumption of internal high-grade thermal energy. After the sludge is dried and incinerated, a large amount of high-quality thermal energy is generated, which is stored in the heat storage device through the third heat exchanger. The heat storage medium can be heat transfer oil or lava, which is used to heat the air in the compressed air expansion stage to improve the overall efficiency.

[0033] The working process of the utility model is as follows:

[0034] During the step-by-step compression of ambient air by the air compression device (compressor), the air temperature increases due to compression, and the temperature ranges from 80 to 190°C. In order to ensure the isothermal compression working conditions of the compressed air energy storage unit, the low-temperature waste heat (70 to 90°C) of the compressed air is exchanged with the air (40 to 50°C) released after the compressed air energy storage unit expands and generates electricity through the first heat exchanger (gas / gas heat exchanger). After the heat exchange, the temperature of the expanded and released air is increased to 85 to 100°C. This part of hot air serves as one of the heat sources for sludge drying. The medium-temperature waste heat (100 to 190°C) generated during the air compression process is stored in the heat storage device as one of the heat sources for heating and expanding the air during the expansion and power generation stage.

[0035] The sludge is separated through pretreatment, conditioning and separation to separate inorganic sludge from organic sludge. The organic sludge with high calorific value enters the subsequent drying process. The sludge drying process requires a drying heat source, and the required temperature range is 70-85°C. The high-temperature flue gas (800-1000°C) generated after sludge incineration passes through the third heat exchanger (high-temperature lava, thermal oil and other heat storage media) to form low-temperature flue gas (200-250°C). The low-temperature flue gas and the air (40-50°C) released after the compressed air energy storage unit expands and generates electricity are exchanged through the second heat exchanger (gas / gas heat exchanger). The temperature of the air released after the heat exchange is 85-100°C. This part of hot air also serves as one of the sludge drying heat sources. The moisture content of the dried organic sludge is ≤15%, and the calorific value is as high as 3500-4500KJ / kg. After incineration, high-temperature flue gas is generated with a temperature range of about 800-1000℃. After this part of the high-temperature flue gas is heat exchanged through the third heat exchanger (high-temperature lava, heat transfer oil and other heat storage media), all the heat is stored in the heat storage device of the compressed air energy storage system, and then used in the expansion and power generation stage of the compressed air energy storage system to improve the overall power generation efficiency of the compressed air energy storage system. The low-temperature flue gas (200-250℃) after heat exchange is heat exchanged again through the second heat exchanger (gas / gas heat exchanger) and then dusted and purified to meet the external discharge environment.

[0036] In summary, the utility model can realize the coupled utilization of waste energy and waste heat of two units. First, the compressor uses valley electricity (low electricity price) to compress normal-pressure air into high-pressure air and store it in the air storage device. The low-temperature waste heat generated in the process of air compression by the compressor is efficiently utilized as a low-grade heat source required for sludge drying. In the peak electricity (high electricity price) discharge stage, the expander uses the stored high-pressure air to release work and generate electricity, and the low-price electricity generated can be used for the sludge resource utilization unit; secondly, the dewatered sludge (water content ≤80%) of the municipal sewage plant enters the sludge separation device after pretreatment and conditioning, and the organic matter and inorganic matter in the sludge are separated. The organic sludge enters the sludge drying device for further drying and dehydration (water content ≤15%) to improve the sludge energy density. Finally, the dried organic sludge enters the incineration device for reduction and resource utilization, and the high-temperature flue gas generated by the sludge incineration device is used as the high-temperature heat source required for the compressed air energy storage expander to discharge and do work, thereby providing the power generation efficiency of the compressed air unit.

Claims

1. A process system for coupling compressed air energy storage with sludge resource utilization of waste energy and waste heat, characterized in that: It includes a compressed air energy storage system, a sludge resource system and a coupling system; wherein the coupling system includes a first heat exchanger, a second heat exchanger, a third heat exchanger and a dust removal and purification device; The compressed air energy storage system comprises an air compression device, an air storage device, an expansion power generation device and a heat storage device, wherein the first output end of the air compression device is connected to the input end of the air storage device, and the output end of the air storage device and the output end of the heat storage device are respectively connected to the first input end and the second input end of the expansion power generation device; the second output end of the air compression device is respectively connected to the first input end of the first heat exchanger and the first input end of the heat storage device; the first output end of the expansion power generation device serves as a peak discharge end; the second output end of the expansion power generation device is respectively connected to the second input end of the first heat exchanger and the first input end of the second heat exchanger; The sludge resource utilization system includes a sludge pretreatment device, a sludge drying device and a sludge incineration device, wherein the output end of the sludge pretreatment device is connected to the first input end of the sludge drying device, and the output end of the sludge drying device is connected to the input end of the sludge incineration device; the output end of the first heat exchanger and the first output end of the second heat exchanger are both connected to the second input end of the sludge drying device, and the second output end of the second heat exchanger is connected to the input end of the dust removal and purification device; the output end of the sludge incineration device is connected to the input end of the third heat exchanger; the first output end of the third heat exchanger is connected to the second input end of the second heat exchanger, and the second output end of the third heat exchanger is connected to the second input end of the heat storage device.

2. The process system for coupled utilization of compressed air energy storage and sludge resource waste energy and waste heat as claimed in claim 1 is characterized in that: The air compression device adopts a compressor, including a large axial flow, centrifugal or combination of the two compressor units.

3. The process system for coupled utilization of compressed air energy storage and sludge resource waste energy and waste heat as claimed in claim 1 is characterized in that: The air storage device adopts natural rock cave, artificial concrete chamber or pipeline steel.

4. The process system for coupled utilization of compressed air energy storage and sludge resource waste energy and waste heat as claimed in claim 1 is characterized in that: The expansion power generation device adopts an expansion turbine unit.

5. The process system for coupled utilization of compressed air energy storage and sludge resource waste energy and waste heat as claimed in claim 1 is characterized in that: The medium of the heat storage device is lava or water.

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