Low-grade energy cascade recycling system and method

Abstract

The invention provides a low-grade energy gradient recycling system and method, and relates to the technical field of thermal power generation. The low-grade energy gradient recycling system comprises a water distribution device used for distributing and replenishing water; the drying equipment is used for absorbing the waste heat of the dried waste gas by the distributed condensation and replenishment water, and the condensation and replenishment water becomes first condensation and replenishment water after absorbing heat; the compression equipment is used for compressing air in a staged manner, the distributed condensation and replenishment water absorbs waste heat of the compressed air in each stage, and the condensation and replenishment water becomes first condensation and replenishment water after absorbing heat; and the slag recovery device is connected with the drying equipment and the compression equipment, slag is stored in the slag recovery device, and the first coagulation and replenishment water absorbs waste heat of the slag and is heated to become second coagulation and replenishment water. The temperature of the condensed and replenished water is increased by absorbing the waste heat of the drying waste gas, the compressed air and the slag, and the requirement for steam exhaust of the back pressure turbine is reduced. According to the low-grade energy gradient recycling system and method, the problem that in the prior art, the heat supply capacity of a back pressure turbine is reduced due to the fact that the back pressure turbine is used for supplying steam to increase the condensate replenishing water temperature is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and in particular to a low-grade energy cascade recovery and utilization system and a low-grade energy cascade recovery and utilization method. Background Art

[0002] In thermal power plants, the thermal cycle will cause a certain amount of steam and water loss. In order to ensure the normal operation of the system, condensate must be replenished in time. Due to the high quality requirements of boiler feed water, the condensate replenishment system usually uses chemical desalted water as the replenishment water source. In back-pressure steam turbines, the role of the condensate replenishment system is particularly critical. The exhaust steam of the back-pressure machine is directly sent to the heat network to provide heat for heat users. The condensate replenishment system needs to replenish the water lost due to the thermal cycle in time. Usually, the condensate replenishment water is heated by steam to increase its temperature, so as to meet the temperature requirements of the condensate replenishment water and ensure the stable operation of the system. However, with the increase in the heating demand of heat users, the steam supply of the back-pressure machine must not only meet the user's heating, but also provide a heat source for the condensate replenishment water temperature increase, resulting in the back-pressure machine's steam supply capacity being limited and the heating capacity being reduced. Therefore, how to use low-grade heat to heat the condensate replenishment water to reduce the steam extracted from the back-pressure machine for heating the condensate replenishment water has become a topic that needs to be studied urgently for back-pressure heating units.

[0003] Therefore, there is an urgent need for a device that can solve at least one of the above problems. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a low-grade energy cascade recovery and utilization system and method, which is used to solve the problem of reduced heating capacity of the back pressure machine caused by using the back pressure machine to supply steam to increase the condensate and make-up water temperature in the prior art.

[0005] In order to achieve the above-mentioned object, the present invention provides a low-grade energy cascade recovery and utilization system on the one hand, and the low-grade energy cascade recovery and utilization system comprises: A water distribution device is connected to the condensate replenishment water system, and the condensate replenishment water from the condensate replenishment water system is distributed through the water distribution device; Drying equipment: after the sludge is dried by the drying equipment, drying waste gas is generated. The drying equipment is connected to the water distribution device. The condensation water distributed by the water distribution device absorbs the residual heat of the drying waste gas and becomes the first condensation water. The compression equipment is used to compress the air in stages. The compression equipment is connected to the water distribution device. The condensate water distributed by the water distribution device absorbs the waste heat of each stage of compressed air and becomes the first condensate water. The slag recovery device connected to the drying equipment and the compression equipment stores slag, and the first condensation replenishment water from the drying equipment and the compression equipment absorbs the residual heat of the slag to become the second condensation replenishment water.

[0006] Specifically, the drying equipment includes: a sludge drying device and a drying heat exchanger; The sludge drying device is used to dry the sludge, and after the sludge is dried, drying waste gas is generated; A connecting pipe is arranged between the drying heat exchanger, the sludge drying device and the water distribution device. The condensate replenishment water distributed by the water distribution device enters the drying heat exchanger to exchange heat with the drying waste gas entering the drying heat exchanger. The condensate replenishment water absorbs the waste heat of the drying waste gas and becomes the first condensate replenishment water.

[0007] Specifically, the compression equipment includes: a plurality of groups of compression heat exchange components connected in sequence; Each compression heat exchange assembly includes: a compressor and a compression heat exchanger; The compressor of each compression heat exchange assembly is used to compress the air flowing to the group; A connecting pipe is provided between the compression heat exchanger of each compression heat exchange assembly and the water distribution device and the compressor of the group of compression heat exchange assemblies, which is used to absorb the waste heat of the compressed air using the condensed make-up water distributed by the water distribution device. After absorbing heat, the condensed make-up water becomes the first condensed make-up water.

[0008] Specifically, the compression equipment includes: multiple compression coolers, a compression cooler is arranged between the compression heat exchanger of the upper group of compression heat exchange components and the compressor of the next group of compression heat exchange components, and the compression cooler is used to cool the compressed air after heat loss discharged from the compression heat exchanger of the upper group of compression heat exchange components.

[0009] Specifically, a cooling passage is provided between the compressed air outlet of the compressor and the cooling inlet of the next compression cooler, and the compressed air can flow into the next compression cooler through the cooling passage.

[0010] Specifically, a temperature control valve is provided on the cooling passage to adjust the flow rate of compressed air flowing through the cooling passage.

[0011] Specifically, the water distribution device includes: a distribution controller, a plurality of distribution control valves and a corresponding plurality of temperature detectors; A temperature detector is provided at the exhaust gas inlet of the drying heat exchanger to detect the temperature of the exhaust gas entering the drying heat exchanger; A temperature detector is provided at the compressed air inlet of each compression heat exchanger to detect the temperature of the compressed air entering the compression heat exchanger; Distribution control valves are provided on the connecting pipes between the water distribution device and the drying heat exchanger and on the connecting pipes between the water distribution device and the compression heat exchanger. The flow of condensate and makeup water flowing through the connecting pipes can be controlled by adjusting the opening of the distribution control valves. The distribution controller is connected to each temperature detector and each distribution control valve signal, and is used to adjust the opening of the corresponding distribution control valve according to the temperature detected by the temperature detector; Specifically, the slag recovery device includes: a slag cooler for storing slag; the slag cooler has a condensate replenishment water inlet, which is connected to the water outlet of the drying heat exchanger and the water outlet of the compression heat exchanger. The first condensate replenishment water discharged from the drying heat exchanger and the first condensate replenishment water discharged from the compression heat exchanger enter the slag cooler through the condensate replenishment water inlet to exchange heat with the slag, and the first condensate replenishment water absorbs the waste heat of the slag to become the second condensate replenishment water.

[0012] Another aspect of the present invention provides a low-grade energy cascade recovery and utilization method, which is implemented based on any of the above-mentioned low-grade energy cascade recovery and utilization systems, and the low-grade energy cascade recovery and utilization method comprises: The condensate replenishment water is distributed to the drying equipment and the compression equipment through the water distribution device; wherein the condensate replenishment water absorbs the waste heat of the drying exhaust gas generated by the drying equipment and then heats up to become the first condensate replenishment water, and the condensate replenishment water absorbs the waste heat of each stage of compressed air in the compression equipment and then heats up to become the first condensate replenishment water; The first condensation feed water is transported to the slag recovery device to absorb the waste heat of the slag, and then heated to become the second condensation feed water.

[0013] Specifically, the method of distributing condensate replenishment water to the drying equipment and the compression equipment through the water distribution device includes: Obtain the temperature of the dried exhaust gas and the temperature of the compressed air at each stage of the compression equipment; The flow rate of condensate and make-up water allocated to the drying equipment and compression equipment is adjusted according to the temperature of the dried exhaust gas and the temperature of each stage of compressed air.

[0014] The low-grade energy cascade recovery and utilization system provided by the present invention distributes condensate replenishment water to the drying equipment and the compression equipment through the water distribution device. The drying equipment uses the condensate replenishment water to absorb the waste heat of the drying waste gas generated by the sludge drying. The compression equipment uses the condensate replenishment water to absorb the waste heat of each stage of compressed air. The condensate replenishment water absorbs the waste heat of the drying waste gas and the compressed air and then heats up to become the first condensate replenishment water. Then, the first condensate replenishment water is sent to the slag recovery device, and the first condensate replenishment water is used to absorb the waste heat of the slag recovered by the slag recovery device. The first condensate replenishment water is heated to become the second condensate replenishment water. The condensate replenishment water increases the temperature by absorbing the waste heat of the drying waste gas, compressed air and slag, avoiding the need for exhaust steam from the back pressure machine in the process of increasing the condensate replenishment water temperature, and can make all the exhaust steam from the back pressure machine supplied to the user for heating. The low-grade energy cascade recovery and utilization system and method provided by the present invention solves the problem of reduced heating capacity of the back pressure machine caused by using the back pressure machine to supply steam to increase the condensate replenishment water temperature in the prior art.

[0015] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the layout of the low-grade energy cascade recovery and utilization system provided by the present invention.

[0017] Description of Reference Numerals 1-drying equipment; 2-compression equipment; 3-slag recovery device; 11-sludge drying device; 12-drying heat exchanger; 21-compressor; 22-compression heat exchanger; 23-compression cooler; 24-temperature control valve; 110-wet sludge storage bin; 111-wet sludge conveyor; 112-sludge drying machine; 113-dust collector; 114-dry sludge conveyor. DETAILED DESCRIPTION

[0018] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0019] Figure 1 This is a schematic diagram of the layout of the low-grade energy cascade recovery and utilization system. Figure 1 As shown, the present invention provides a low-grade energy cascade recovery and utilization system on one hand, and the low-grade energy cascade recovery and utilization system comprises: A water distribution device is connected to the condensate replenishment water system, and the condensate replenishment water from the condensate replenishment water system is distributed through the water distribution device; Drying equipment 1, after the sludge is dried by the drying equipment 1, drying waste gas is generated. The drying equipment 1 is connected to the water distribution device. The condensate replenishment water distributed by the water distribution device absorbs the residual heat of the drying waste gas to become the first condensate replenishment water; The compression device 2 is used for compressing air in stages. The compression device 2 is connected to the water distribution device. The condensate replenishment water distributed by the water distribution device absorbs the waste heat of each stage of compressed air to become the first condensate replenishment water. The slag recovery device 3 connected to the drying device 1 and the compression device 2 stores slag, and the first condensed makeup water from the drying device 1 and the compression device 2 absorbs the residual heat of the slag to become the second condensed makeup water.

[0020] The low-grade energy cascade recovery and utilization system provided by the present invention distributes condensate replenishment water from the condensate replenishment water system to the drying device 1 and the compression device 2 through the water distribution device. The condensate replenishment water enters the drying device 1 to absorb the waste heat of the drying waste gas generated by the drying device 1 during the sludge drying process. The condensate replenishment water enters the compression device 2 to absorb the waste heat of the compressed air formed after each stage of compression; the condensate replenishment water absorbs the waste heat of the drying waste gas and the waste heat of the compressed air and then heats up to become the first condensate replenishment water, and the first condensate replenishment water is sent to the slag recovery device 3, and the first condensate replenishment water is used to The first condensate make-up water absorbs the waste heat of the slag recovered in the slag recovery device 3 and is heated up to become the second condensate make-up water after absorbing the heat. The second condensate make-up water is sent to the deaerator. In this way, the condensate make-up water increases its temperature by absorbing the waste heat of the dried exhaust gas, compressed air and the slag. Compared with the prior art in which a large amount of back pressure machine exhaust steam is required to increase the condensate make-up water temperature, the demand for back pressure machine exhaust steam is reduced, and the back pressure machine exhaust steam can be fully supplied to the user for heating, which solves the problem of reduced heating capacity of the back pressure machine caused by using the back pressure machine to supply steam to increase the condensate make-up water temperature in the prior art.

[0021] In one embodiment, Figure 1 As shown, the drying equipment 1 comprises: a sludge drying device 11 and a drying heat exchanger 12; The sludge drying device 11 is used to dry the sludge, and after the sludge is dried, drying waste gas is generated; A connecting pipe is provided between the drying heat exchanger 12, the sludge drying device 11 and the water distribution device. The condensate replenishment water distributed by the water distribution device enters the drying heat exchanger 12 to exchange heat with the drying waste gas entering the drying heat exchanger 12. The condensate replenishment water absorbs the residual heat of the drying waste gas and becomes the first condensate replenishment water.

[0022] like Figure 1 As shown, the sludge drying device 11 can dry sludge, and generates drying waste gas in the process of drying the sludge, and the drying waste gas is sent to the drying heat exchanger 12. The drying heat exchanger 12 has a drying inlet, a drying outlet, a drying water inlet, a drying water outlet and a drying waste outlet. The drying waste gas exchanges heat with the condensate replenishment water distributed to the drying heat exchanger 12 by the water distribution device. The condensate replenishment water absorbs the waste heat of the drying waste gas and heats up to become the first condensate replenishment water. The drying waste gas loses heat and is discharged from the drying heat exchanger 12.

[0023] The sludge drying device 11 includes a wet sludge storage bin 110, a wet sludge conveyor 111, a sludge dryer 112, a dust collector 113 and a dry sludge conveyor 114. The wet sludge stored in the wet sludge storage bin 110 is conveyed to the sludge dryer 112 via the wet sludge conveyor 111, and saturated steam is conveyed to the sludge dryer 112. The saturated steam exchanges heat with the wet sludge to heat the wet sludge. In the process of heating the wet sludge with the saturated steam, the drying waste gas generated from the wet sludge is discharged from the sludge dryer 112. After the saturated steam exchanges heat with the wet sludge, it becomes hydrophobic and is discharged from the sludge dryer 112. The drying waste gas is discharged from the sludge dryer 112 and then enters the dust collector 113. The dust in the drying waste gas is separated by the dust collector 113. After being processed by the dust collector 113, the dry waste gas is discharged from the sludge dryer 112. The drying waste gas enters the drying heat exchanger 12 through the drying inlet, and the condensate replenishment water enters the drying heat exchanger 12 through the drying water inlet. The condensate replenishment water and the drying waste gas exchange heat in the drying heat exchanger 12. The condensate replenishment water absorbs the residual heat of the drying waste gas and then heats up to become the first condensate replenishment water, which is discharged from the drying water outlet. The drying waste gas loses heat in the drying heat exchanger 12 and is discharged from the drying outlet and then sent to the fluidized bed boiler for combustion. After the drying waste gas exchanges heat with the condensate replenishment water in the drying heat exchanger 12, the liquid water condensed in the drying waste gas becomes waste water and is discharged from the drying waste outlet of the drying heat exchanger 12 and recovered by the wastewater treatment device. The wet sludge is heated and dried in the sludge dryer 112 to become dried sludge, and the dried sludge in the sludge dryer 112 is transported to the fluidized bed boiler for combustion through the dry sludge conveyor 114. The slag recovery device 3 can recover the slag discharged from the fluidized bed boiler.

[0024] like Figure 1 As shown, the compression device 2 comprises: a plurality of groups of compression heat exchange components connected in sequence; Each compression heat exchange assembly includes: a compressor 21 and a compression heat exchanger 22; The compressor 21 of each compression heat exchange assembly is used to compress the air flowing to the reformer; A connecting pipe is provided between the compression heat exchanger 22 of each compression heat exchange assembly and the water distribution device and the compressor 21 of the group of compression heat exchange assemblies, for absorbing the waste heat of the compressed air using the condensed make-up water distributed by the water distribution device. After absorbing heat, the condensed make-up water becomes the first condensed make-up water.

[0025] In order to absorb the waste heat of compressed air, the compression device 2 includes: multiple compression coolers 23, a compression cooler 23 is arranged between the compression heat exchanger 22 of the upper group of compression heat exchange components and the compressor 21 of the lower group of compression heat exchange components, and the compression cooler 23 is used to cool the compressed air after losing heat discharged from the compression heat exchanger 22 of the upper group of compression heat exchange components.

[0026] A cooling passage is provided between the compressed air outlet of the compressor 21 and the cooling inlet of the next compression cooler 23 , and the compressed air can flow into the next compression cooler 23 through the cooling passage.

[0027] A temperature control valve 24 is provided on the cooling passage to adjust the flow rate of compressed air flowing through the cooling passage.

[0028] like Figure 1 As shown, three groups of compression heat exchange components are arranged and connected in sequence, and air flows through each group of compression heat exchange components in sequence. When flowing through each group of compression heat exchange components, the air passing through is compressed by the compressor 21 of each group of compression heat exchange components, and the compressed air is heated and pressurized to become compressed air; the air first enters the compressor 21 of the first group of compression heat exchange components, and after the air is compressed by the compressor 21 of the first group of compression heat exchange components, the temperature and pressure of the air are increased to become compressed air, and the compressed air is discharged from the compressor 21 and enters the compression heat exchanger 22 of the first group of compression heat exchange components, and the compressed air exchanges heat with the condensate feed water entering the compression heat exchanger 22 in the compression heat exchanger 22, and the condensate feed water absorbs the waste heat in the compressed air and the temperature is increased, and the heated condensate feed water becomes the first condensate feed water and is sent to the slag recovery device 3, and the compressed air loses heat as the air sent to the next group of compression heat exchange components, in order to avoid the compressor 21 sent to the next group of compression heat exchange components In order to prevent the compressor from malfunctioning or being damaged due to excessively high air temperature, a compression cooler 23 is arranged between the compression heat exchanger 22 of the first group of compression heat exchange components and the compressor 21 of the next group of compression heat exchange components. The air sent to the compressor 21 of the next group of compression heat exchange components is cooled by the compression cooler 23 so that the air temperature entering the compressor 21 of the next group meets the steam inlet requirement of the compressor 21. After the air is compressed by the compressor 21, the temperature rises again to become compressed air. The compressed air enters the compression heat exchanger 22 of the group of compression heat exchange components to exchange heat with the incoming condensate make-up water. The condensate make-up water absorbs the waste heat of the compressed air and becomes the first condensate make-up water, which is sent to the slag recovery device 3. After the compressed air loses heat, it is used as the air sent to the next group of compression heat exchange components. In this way, the air flows through multiple groups of compression heat exchange components for compression, and the waste heat of the compressed air formed after compression of each group of compression heat exchange components is absorbed by the condensate make-up water, thereby making full use of the waste heat of the compressed air to heat the condensate make-up water.

[0029] A cooling passage is provided between the compressed air outlet of the compressor 21 of the previous compression heat exchange component and the cooling inlet of the compression cooler 23 of the compression heat exchange component of this group, and a temperature control valve 24 is provided on the cooling passage. The compressed air compressed by the compressor 21 can flow through the cooling passage and enter the compression cooler 23 after being discharged from the compressed air outlet. In this way, the compression heat exchanger 22 of the compression heat exchange component of this group is connected in parallel with the cooling passage, that is, the compressed air discharged from the compressed air outlet of the compressor 21 can flow in two ways. One way enters the compression heat exchanger 22 and loses heat after heat exchange with condensate water. The compressed air that loses heat then enters the compression cooler 23 for cooling. The other way of compressed air directly enters the compression cooler 23 for cooling after passing through the cooling passage. The flow rate of the compressed air flowing through the cooling passage is adjusted by the temperature control valve 24 provided on the cooling passage. The flow rate of the compressed air flowing through the cooling passage changes, and the flow rate of the compressed air entering the compression heat exchanger 22 changes accordingly. The compressed air and the compressed air that loses heat are cooled by the compression cooler 23 and then used as the air sent to the next group of compression heat exchange components.

[0030] In order to better distribute the flow of condensate water sent to the drying device 1 and the compression device 2, the water distribution device includes: a distribution controller, a plurality of distribution control valves and a corresponding plurality of temperature detectors; A temperature detector is provided at the exhaust gas inlet of the drying heat exchanger 12 to detect the temperature of the exhaust gas entering the drying heat exchanger 12; A temperature detector is provided at the compressed air inlet of each compression heat exchanger 22 to detect the temperature of the compressed air entering the compression heat exchanger 22; A distribution control valve is provided on the connecting pipe between the water distribution device and the drying heat exchanger 12 and on the connecting pipe between the water distribution device and the compression heat exchanger 22. The flow rate of the condensate replenishment water flowing through the connecting pipe can be controlled by adjusting the opening of the distribution control valve. The distribution controller is connected to each temperature detector and each distribution control valve signal, and is used to adjust the opening of the corresponding distribution control valve according to the temperature detected by the temperature detector.

[0031] The flow rate of condensate make-up water entering the drying heat exchanger 12 of the drying equipment 1 is adjusted according to the temperature of the dried exhaust gas and the temperature of the compressed air. The flow rate of condensate make-up water entering the compression heat exchanger 22 of the compression equipment 2 is adjusted according to the temperature of the compressed air generated after each group of compression heat exchange components compresses the air. The opening degree of the corresponding distribution control valve is adjusted by the temperature of the dried exhaust gas, thereby adjusting the flow rate of condensate make-up water sent to the drying equipment. The opening degree of the corresponding distribution control valve is adjusted by the temperature of the compressed air, thereby adjusting the flow rate of condensate make-up water sent to the compression equipment. In this way, the condensate make-up water can better absorb the waste heat of the dried exhaust gas or compressed air.

[0032] The condensate replenishment water is heated by the drying waste gas and compressed air and becomes the first condensate replenishment water. The slag recovery device includes: a slag cooler 31 for storing slag; the slag cooler has a condensate replenishment water inlet, and the condensate replenishment water inlet is connected to the water outlet of the drying heat exchanger 12 and the water outlet of the compression heat exchanger 22. The first condensate replenishment water discharged from the drying heat exchanger 12 and the first condensate replenishment water discharged from the compression heat exchanger 22 enter the slag cooler through the condensate replenishment water inlet to exchange heat with the slag, and the first condensate replenishment water absorbs the waste heat of the slag to become the second condensate replenishment water.

[0033] The slag cooler 31 is provided to absorb the waste heat of the slag stored in the slag cooler 31 through the first condensate replenishment water, that is, the waste heat of the slag is used to cool the slag. The condensate replenishment water can make the temperature of the condensate replenishment water reach the temperature requirement for entering the deaerator by absorbing the waste heat of the drying waste gas, compressed air and slag, and the system for heating condensate replenishment water provided in the present application does not use the exhaust steam of the back pressure machine, and the exhaust steam of the back pressure machine can be fully supplied to the user for heating. Another aspect of the present invention provides a low-grade energy cascade recovery and utilization method, which is implemented based on any of the above-mentioned low-grade energy cascade recovery and utilization systems, and the low-grade energy cascade recovery and utilization method comprises: The condensate replenishment water is distributed to the drying equipment and the compression equipment through the water distribution device; wherein the condensate replenishment water absorbs the waste heat of the drying exhaust gas generated by the drying equipment and then heats up to become the first condensate replenishment water, and the condensate replenishment water absorbs the waste heat of each stage of compressed air in the compression equipment and then heats up to become the first condensate replenishment water; The first condensation feed water is transported to the slag recovery device to absorb the waste heat of the slag, and then heated to become the second condensation feed water.

[0034] The method of distributing condensate replenishment water to the drying equipment and the compression equipment through the water distribution device includes: Obtain the temperature of the dried exhaust gas and the temperature of the compressed air at each stage of the compression equipment; The flow rate of condensate and make-up water allocated to the drying equipment and compression equipment is adjusted according to the temperature of the dried exhaust gas and the temperature of each stage of compressed air.

[0035] In order to heat the condensate make-up water through the waste heat of drying waste gas, compressed air and slag, the condensate make-up water is distributed to the drying equipment and the compression equipment through the water distribution device. In order to ensure that the condensate make-up water can better absorb the waste heat of drying waste gas and compressed air, the flow rate of condensate make-up water distributed to the drying equipment and the compression equipment is adjusted according to the temperature of the drying waste gas and the compressed air, so that the amount of condensate make-up water entering the drying equipment and the compression equipment can be controlled, and the condensate make-up water can fully absorb the waste heat of drying waste gas and compressed air. The condensate make-up water distributed to the drying equipment absorbs the waste heat of the drying waste gas to become the first condensate make-up water, and the condensate make-up water distributed to the compression equipment absorbs the waste heat of the compressed air to become the first condensate make-up water. The first condensate make-up water is sent to the slag recovery device to absorb the waste heat of the slag to heat the condensate make-up water again.

[0036] The low-grade energy cascade recovery and utilization system provided by the present invention distributes condensate replenishment water to the drying equipment and the compression equipment through the water distribution device. The drying equipment uses the condensate replenishment water to absorb the waste heat of the drying waste gas generated by the sludge drying. The compression equipment uses the condensate replenishment water to absorb the waste heat of each stage of compressed air. The condensate replenishment water absorbs the waste heat of the drying waste gas and the compressed air and then heats up to become the first condensate replenishment water. Then, the first condensate replenishment water is sent to the slag recovery device, and the first condensate replenishment water is used to absorb the waste heat of the slag recovered by the slag recovery device. The first condensate replenishment water is heated to become the second condensate replenishment water. The condensate replenishment water increases the temperature by absorbing the waste heat of the drying waste gas, compressed air and slag, avoiding the need for exhaust steam from the back pressure machine in the process of increasing the condensate replenishment water temperature, and can make all the exhaust steam from the back pressure machine supplied to the user for heating. The low-grade energy cascade recovery and utilization system and method provided by the present invention solves the problem of reduced heating capacity of the back pressure machine caused by using the back pressure machine to supply steam to increase the condensate replenishment water temperature in the prior art.

[0037] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0038] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0039] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A low-grade energy cascade recovery and utilization system, characterized in that: include: A water distribution device is connected to the condensate replenishment water system, and the condensate replenishment water from the condensate replenishment water system is distributed through the water distribution device; Drying equipment (1), after the sludge is dried by the drying equipment (1), drying waste gas is generated, the drying equipment (1) is connected to the water distribution device, and the condensate replenishment water distributed by the water distribution device absorbs the residual heat of the drying waste gas to become the first condensate replenishment water; The compression device (2) is used for compressing air in stages, the compression device (2) is connected to a water distribution device, and the condensate replenishment water distributed by the water distribution device absorbs the residual heat of each stage of compressed air to become the first condensate replenishment water; The slag recovery device (3) connected to the drying device (1) and the compression device (2) stores slag, and the first condensation replenishment water from the drying device (1) and the compression device (2) absorbs the waste heat of the slag to become the second condensation replenishment water.

2. The low-grade energy cascade recovery and utilization system according to claim 1 is characterized in that: The drying equipment (1) comprises: a sludge drying device (11) and a drying heat exchanger (12); The sludge drying device (11) is used to dry the sludge, and after the sludge is dried, drying waste gas is generated; A connecting pipe is provided between the drying heat exchanger (12), the sludge drying device (11) and the water distribution device. The condensate replenishment water distributed by the water distribution device enters the drying heat exchanger (12) and exchanges heat with the drying waste gas entering the drying heat exchanger (12). The condensate replenishment water absorbs the residual heat of the drying waste gas and becomes the first condensate replenishment water.

3. The low-grade energy cascade recovery and utilization system according to claim 2 is characterized in that: The compression device (2) comprises: a plurality of groups of compression heat exchange components connected in sequence; each compression heat exchange component comprises a compressor (21) and a compression heat exchanger (22); The compressor (21) of each compression heat exchange assembly is used to compress the air flowing to the group; A connecting pipe is provided between the compression heat exchanger (22) of each compression heat exchange assembly and the water distribution device and the compressor (21) of the group of compression heat exchange assemblies, and is used to absorb the residual heat of the compressed air using the condensed make-up water distributed by the water distribution device, and the condensed make-up water becomes the first condensed make-up water after absorbing the heat.

4. The low-grade energy cascade recovery and utilization system according to claim 3 is characterized in that: The compression device (2) comprises: a plurality of compression coolers (23), wherein a compression cooler (23) is arranged between the compression heat exchanger (22) of the upper group of compression heat exchange components and the compressor (21) of the lower group of compression heat exchange components, and the compression cooler (23) is used to cool the compressed air discharged from the compression heat exchanger (22) of the upper group of compression heat exchange components after losing heat.

5. The low-grade energy cascade recovery and utilization system according to claim 4 is characterized in that: A cooling passage is provided between the compressed air outlet of the compressor (21) and the cooling inlet of the next compression cooler (23), and the compressed air can flow into the next compression cooler (23) through the cooling passage.

6. The low-grade energy cascade recovery and utilization system according to claim 5 is characterized in that: A temperature control valve (24) is provided on the cooling passage for adjusting the flow rate of compressed air flowing through the cooling passage.

7. The low-grade energy cascade recovery and utilization system according to claim 3 is characterized in that: The water distribution device includes: a distribution controller, a plurality of distribution control valves and a corresponding plurality of temperature detectors; A temperature detector is provided at the drying exhaust gas inlet of the drying heat exchanger (12) for detecting the temperature of the drying exhaust gas entering the drying heat exchanger (12); A temperature detector is provided at the compressed air inlet of each compression heat exchanger (22) for detecting the temperature of the compressed air entering the compression heat exchanger (22); A distribution control valve is provided on the connecting pipe between the water distribution device and the drying heat exchanger (12) and on the connecting pipe between the water distribution device and the compression heat exchanger (22). The flow rate of condensate replenishment water flowing through the connecting pipe can be controlled by adjusting the opening of the distribution control valve. The distribution controller is connected to each temperature detector and each distribution control valve signal, and is used to adjust the opening of the corresponding distribution control valve according to the temperature detected by the temperature detector.

8. The low-grade energy cascade recovery and utilization system according to claim 7 is characterized in that: The slag recovery device (3) comprises: a slag cooler (31) for storing slag; the slag cooler (31) has a condensate replenishment water inlet, the condensate replenishment water inlet is connected to the water outlet of the drying heat exchanger (12) and the water outlet of the compression heat exchanger (22), the first condensate replenishment water discharged from the drying heat exchanger (12) and the first condensate replenishment water discharged from the compression heat exchanger (22) enter the slag cooler (31) through the condensate replenishment water inlet to exchange heat with the slag, and the first condensate replenishment water absorbs the residual heat of the slag to become second condensate replenishment water.

9. A low-grade energy cascade recycling method, implemented based on the low-grade energy cascade recycling system according to any one of claims 1 to 8, characterized in that: The low-grade energy cascade recovery and utilization method comprises: The condensate replenishment water is distributed to the drying equipment and the compression equipment through the water distribution device; wherein the condensate replenishment water absorbs the waste heat of the drying exhaust gas generated by the drying equipment and then heats up to become the first condensate replenishment water, and the condensate replenishment water absorbs the waste heat of each stage of compressed air in the compression equipment and then heats up to become the first condensate replenishment water; The first condensation feed water is transported to the slag recovery device to absorb the waste heat of the slag, and then heated to become the second condensation feed water.

10. The low-grade energy cascade recovery and utilization method according to claim 9, characterized in that: The method of distributing condensate replenishment water to the drying equipment and the compression equipment through the water distribution device includes: Obtain the temperature of the dried exhaust gas and the temperature of the compressed air at each stage of the compression equipment; The flow rate of condensate and make-up water allocated to the drying equipment and the compression equipment is adjusted according to the temperature of the dried exhaust gas and the temperature of each stage of compressed air.

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