A waste incineration waste heat utilization device and method for recovering flue gas and slag heat

Abstract

The invention discloses a waste incineration waste heat utilization device and method for recovering heat from flue gas and slag. The waste incineration waste heat utilization device comprises a waste incinerator, a slag waste heat boiler, a first steam turbine, a third steam turbine, a flue gas waste heat boiler, a first condenser, a first heat exchanger and a third heat exchanger; through the step-by-step recovery of flue gas and slag heat and the matching and coupling between heat of different grades, the output power and energy utilization efficiency of the waste incineration power plant are improved; by using the waste heat boiler to recover the slag heat for steam Rankine cycle power generation, the cooling water consumption in the conventional slag treatment process is greatly reduced; by recovering the heat of turbine exhaust steam and low-temperature flue gas through heat network return water, the heat supply and heating income of the power plant are increased, and the economic benefits of the power plant are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy utilization, and in particular relates to a device and method for utilizing waste incineration waste heat by recovering heat from flue gas and slag. Background Art

[0002] Landfill was once the main way to deal with garbage. Its advantages are simple operation and low cost, but its disadvantage is that it occupies a large area. In the long run, the leachate generated during the landfill process is difficult to handle, which will cause the land and groundwater resources in the area to be polluted. With the advancement of urbanization, the pressure on landfill is increasing. Waste incineration power generation is to release the chemical energy stored in domestic waste through incineration, convert it into heat energy and utilize it. Compared with landfill, the amount of pollutant gas emissions generated by waste incineration is much lower. At the same time, the electricity and heat it generates can also reduce the consumption of non-renewable energy, achieve energy conservation and emission reduction, and is gradually becoming the mainstream of urban domestic waste treatment in my country.

[0003] Although incineration has significant advantages in the harmless treatment of urban domestic waste, there are also some key issues to be resolved. The most widespread problem is that the overall energy efficiency of waste incineration power plants is low, and there is a large loss of low-grade energy, mainly due to the heat loss of boiler combustion and the low-temperature heat loss of exhaust gas. In addition, the bottom ash particles at the bottom of the incinerator of the waste incineration power plant also contain a large amount of waste heat energy, but current waste incineration power plants rarely use this part of heat. Waste heat recovery and utilization needs to consider the regional energy product needs, because waste heat resources can not only be used for power generation, but also for regional heating, providing domestic hot water, and providing cold energy through refrigeration technology.

[0004] The prior art has not utilized the heat in the slag at the bottom of the incinerator of the waste incineration power plant, but only utilized the waste heat in the flue gas. Summary of the invention

[0005] The object of the present invention is to provide a waste incineration waste heat utilization device and method for recovering the heat of flue gas and slag, so as to achieve the purpose of dual recovery of flue gas and slag heat.

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

[0007] In a first aspect of the present invention, there is provided a waste incineration waste heat utilization device for flue gas slag heat recovery, comprising a waste incinerator, a slag waste heat boiler, a first steam turbine, a third steam turbine, a flue gas waste heat boiler, a first condenser, a first heat exchanger and a third heat exchanger;

[0008] The high-temperature flue gas outlet at the top of the waste incinerator is connected to the flue gas waste heat boiler, the steam outlet of the flue gas waste heat boiler is connected to the steam inlet of the third steam turbine, the exhaust steam outlet of the third steam turbine is connected to the inlet of the first condenser, and the water outlet of the first condenser is connected to the water inlet of the flue gas waste heat boiler;

[0009] The high-temperature slag outlet at the bottom of the waste incinerator is connected to the feed port of the slag waste heat boiler, the superheated steam outlet of the slag waste heat boiler is connected to the first steam turbine, the exhaust steam outlet of the first steam turbine is connected to the steam heat exchange inlet of the first heat exchanger, the steam heat exchange outlet of the first heat exchanger is connected to the steam heat exchange inlet of the third heat exchanger, and the outlet of the third heat exchanger is connected to the circulating water inlet of the slag waste heat boiler.

[0010] Optionally, it also includes a second steam turbine, a second heat exchanger and a second condenser;

[0011] The circulating organic working fluid heat exchange outlet of the first heat exchanger is connected to the circulating organic working fluid heat exchange inlet of the second heat exchanger, the circulating organic working fluid heat exchange outlet of the second heat exchanger is connected to the second steam turbine, the exhaust steam outlet of the second steam turbine is connected to the inlet of the second condenser, and the condensation outlet of the second condenser is connected to the circulating organic working fluid heat exchange inlet of the first heat exchanger through a circulating organic working fluid pipeline.

[0012] Optionally, it also includes a heat network return pipeline and a fourth heat exchanger, and the heat network return pipeline is connected to the third heat exchanger and the fourth heat exchanger in sequence.

[0013] Optionally, the flue gas outlet of the flue gas waste heat boiler is connected to the flue gas heat exchange inlet of the second heat exchanger.

[0014] Optionally, the flue gas heat exchange outlet of the second heat exchanger is connected to the flue gas heat exchange inlet of the fourth heat exchanger.

[0015] Optionally, the feed inlet of the waste incinerator is connected to a domestic waste conveying device.

[0016] Optionally, the feed inlet of the waste incinerator is connected to an air conveying device.

[0017] Optionally, a solid particle discharge outlet is provided at the bottom of the slag waste heat boiler.

[0018] A second aspect of the present invention provides a method for utilizing waste incineration waste heat by recovering heat from flue gas and slag. The waste incineration waste heat utilization device based on the waste incineration waste heat recovery device comprises the following steps:

[0019] Domestic waste enters the waste incinerator and burns with the help of air, producing high-temperature slag and high-temperature flue gas;

[0020] The high-temperature slag enters the slag waste heat boiler to exchange heat with the circulating water, and the solid particles are discharged after cooling;

[0021] The circulating water absorbs the heat of the slag to become superheated steam, which is sent to the first steam turbine to generate power. The steam after working enters the first heat exchanger to exchange heat with the circulating organic working medium, and then enters the third heat exchanger to continue to exchange heat with the return water of the heat network, and then condenses into water and continues to return to the slag waste heat boiler;

[0022] The high-temperature flue gas discharged from the waste incinerator enters the flue gas waste heat boiler. The steam generated in the flue gas waste heat boiler enters the third steam turbine to generate power. The exhaust steam enters the first condenser and condenses into water and then returns to the flue gas waste heat boiler to complete the cycle.

[0023] The beneficial effects of the present invention are as follows:

[0024] The waste incineration waste heat utilization device provided in the embodiment of the present invention includes a waste incinerator, a slag waste heat boiler, a first steam turbine, a third steam turbine, a flue gas waste heat boiler, a first condenser, a first heat exchanger, a second heat exchanger, a third heat exchanger, and a fourth heat exchanger; the output power and energy utilization efficiency of the waste incineration power plant are improved by the step-by-step recovery of flue gas and slag heat and the matching and coupling between heat of different grades; the slag heat is recovered by the waste heat boiler for steam Rankine cycle power generation, which greatly reduces the cooling water consumption in the conventional slag treatment process; the heat of turbine exhaust steam and low-temperature flue gas is recovered by heat network return water, which increases the heat supply and heating income of the power plant and improves the economic benefits of the power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 A structural block diagram of a waste incineration waste heat utilization device provided in an embodiment of the present invention;

[0027] Figure 2 A structural block diagram of a waste incineration waste heat utilization device provided in a preferred embodiment of the present invention;

[0028] Figure 3 A structural block diagram of a waste incineration waste heat utilization device provided in another preferred embodiment of the present invention;

[0029] Among them: 1 garbage incinerator; 2 slag waste heat boiler; 3 first steam turbine; 4 second steam turbine; 5 third steam turbine; 6 flue gas waste heat boiler; 7 first condenser; 8 first heat exchanger; 9 second heat exchanger; 10 third heat exchanger; 11 fourth heat exchanger; 12 second condenser; 13 domestic waste conveying device; 14 air conveying device; 15 high-temperature flue gas outlet; 16 high-temperature slag outlet; 17 heat network return water pipeline; 18 circulating water inlet; 19 superheated steam outlet; 20 circulating organic working fluid pipeline. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0031] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, the embodiment of the present invention provides a waste incineration waste heat utilization device for flue gas slag heat recovery, comprising a waste incinerator 1, a slag waste heat boiler 2, a first steam turbine 3, a third steam turbine 5, a flue gas waste heat boiler 6, a first condenser 7, a first heat exchanger 8 and a third heat exchanger 10;

[0034] The high-temperature flue gas outlet 15 at the top of the waste incinerator 1 is connected to the flue gas waste heat boiler 6, the steam outlet of the flue gas waste heat boiler 6 is connected to the steam inlet of the third steam turbine 5, the exhaust steam outlet of the third steam turbine 5 is connected to the inlet of the first condenser 7, and the water outlet of the first condenser 7 is connected to the water inlet of the flue gas waste heat boiler 6; the high-temperature slag outlet at the bottom of the waste incinerator 1 is connected to the feed inlet of the slag waste heat boiler 2, the superheated steam outlet 19 of the slag waste heat boiler 2 is connected to the first steam turbine 3, the exhaust steam outlet of the first steam turbine 3 is connected to the steam heat exchange inlet of the first heat exchanger 8, the steam heat exchange outlet of the first heat exchanger 8 is connected to the steam heat exchange inlet of the third heat exchanger 10, and the outlet of the third heat exchanger 10 is connected to the circulating water inlet 18 of the slag waste heat boiler 2.

[0035] The feed inlet of the waste incinerator 1 is connected to a domestic waste conveying device 13 , the feed inlet of the waste incinerator 1 is connected to an air conveying device 14 , and a solid particle discharge port is provided at the bottom of the slag waste heat boiler 2 .

[0036] Through the above settings, the cascade recovery of flue gas and slag heat and the matching and coupling between different grades of heat improve the output power and energy utilization efficiency of the waste incineration power plant; by using waste heat boilers to recover slag heat for steam Rankine cycle power generation, the cooling water consumption in the conventional slag treatment process is greatly reduced.

[0037] Example 2

[0038] like Figure 2 As shown, as a preferred embodiment of the present invention, based on embodiment 1, it further includes a second steam turbine 4, a second heat exchanger 9 and a second condenser 12;

[0039] The circulating organic working medium heat exchange outlet of the first heat exchanger 8 is connected to the circulating organic working medium heat exchange inlet of the second heat exchanger 9, the circulating organic working medium heat exchange outlet of the second heat exchanger 9 is connected to the second steam turbine 4, the exhaust steam outlet of the second steam turbine 4 is connected to the inlet of the second condenser 12, and the condensation outlet of the second condenser 12 is connected to the circulating organic working medium heat exchange inlet of the first heat exchanger 8 through the circulating organic working medium pipeline 20. The flue gas outlet of the flue gas waste heat boiler 6 is connected to the flue gas heat exchange inlet of the second heat exchanger 9.

[0040] Example 3

[0041] like Figure 3 As shown, as a preferred embodiment of the present invention, based on embodiment 2, it further includes a heat network return water pipeline 17 and a fourth heat exchanger 11, and the heat network return water pipeline 17 is sequentially connected to the third heat exchanger 10 and the fourth heat exchanger 11. The flue gas heat exchange outlet of the second heat exchanger 9 is connected to the flue gas heat exchange inlet of the fourth heat exchanger 11.

[0042] The heat of turbine exhaust steam and low-temperature flue gas is recovered through the return water of the heat network, which increases the heat supply and heating income of the power plant and improves the economic benefits of the power plant. Through the heat exchange between the turbine exhaust steam and the return water of the heat network in the steam Rankine cycle, the exhaust steam is cooled and condensed into water, and the condenser is no longer required.

[0043] Embodiment 4, a method for utilizing waste incineration waste heat by recovering heat from flue gas and slag, based on the waste incineration waste heat utilization device by recovering heat from flue gas and slag described in Embodiment 3, comprises the following steps:

[0044] Domestic waste enters the waste incinerator 1 and is burned with the help of air to produce high-temperature slag and high-temperature flue gas; the high-temperature slag enters the slag waste heat boiler 2 to exchange heat with the circulating water, and the solid particles are discharged after cooling; the circulating water receives the heat from the slag to become superheated steam, which is sent to the first steam turbine 3 to generate power. The steam after power generation enters the first heat exchanger 8 to exchange heat with the circulating organic working medium, and then enters the third heat exchanger 10 to continue to exchange heat with the return water of the heat network and condense into water, which continues to return to the slag waste heat boiler 2 to complete the steam Rankine cycle ; The circulating organic working medium exchanges heat with steam in the first heat exchanger 8, enters the second heat exchanger 9, exchanges heat with the cooled flue gas exhaust gas, evaporates into steam, and then enters the second steam turbine 4 to generate power. The organic working medium steam after working passes through the second condenser 12 to condense into liquid, completing the organic Rankine cycle; The high-temperature flue gas discharged from the waste incinerator 1 enters the flue gas waste heat boiler 6, exchanges heat with the circulating water and cools down, then enters the second heat exchanger 9 to exchange heat with the organic working medium, then enters the fourth heat exchanger 11 to exchange heat with the heat network return water and cool down, and then is sent to the purification device. The steam generated in the flue gas waste heat boiler 6 enters the third steam turbine 5 to generate power, and the exhaust steam enters the first condenser 7 to condense into water and then returns to the flue gas waste heat boiler 6 to complete the cycle; The heat network return water 17 passes through the third heat exchanger 10 and the fourth heat exchanger 11 to heat up and then returns to the heat network.

[0045] The present invention simultaneously recycles the heat in the slag and flue gas at the bottom of the incinerator of the waste incineration power plant through multi-stage heat recovery, generates electricity through the steam Rankine cycle and the organic Rankine cycle, and improves the output power of the waste incineration power plant. At the same time, the low-level heat of the steam turbine exhaust steam and flue gas in the steam Rankine cycle is fully recovered by using the return water of the heat network, and the return water of the heat network is sent back to the heat network after being heated, which can increase the heat supply of the power plant.

[0046] The output power and energy efficiency of the waste incineration power plant are improved through the cascade recovery of flue gas and slag heat and the matching and coupling of heat of different grades. The cooling water consumption in the conventional slag treatment process is greatly reduced by using waste heat boilers to recover slag heat for steam Rankine cycle power generation. The heat of turbine exhaust steam and low-temperature flue gas is recovered through heat network return water, which increases the heat supply and heating income of the power plant and improves the economic benefits of the power plant.

[0047] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A waste incineration waste heat utilization device for recovering heat from flue gas and slag, characterized in that: It comprises a waste incinerator (1), a slag waste heat boiler (2), a first steam turbine (3), a third steam turbine (5), a flue gas waste heat boiler (6), a first condenser (7), a first heat exchanger (8) and a third heat exchanger (10); The high-temperature flue gas outlet (15) at the top of the waste incinerator (1) is connected to the flue gas waste heat boiler (6), the steam outlet of the flue gas waste heat boiler (6) is connected to the steam inlet of the third steam turbine (5), the exhaust steam outlet of the third steam turbine (5) is connected to the inlet of the first condenser (7), and the water outlet of the first condenser (7) is connected to the water inlet of the flue gas waste heat boiler (6); The high-temperature slag outlet at the bottom of the waste incinerator (1) is connected to the feed port of the slag waste heat boiler (2), the superheated steam outlet (19) of the slag waste heat boiler (2) is connected to the first steam turbine (3), the exhaust steam outlet of the first steam turbine (3) is connected to the steam heat exchange inlet of the first heat exchanger (8), the steam heat exchange outlet of the first heat exchanger (8) is connected to the steam heat exchange inlet of the third heat exchanger (10), and the outlet of the third heat exchanger (10) is connected to the circulating water inlet (18) of the slag waste heat boiler (2); It also includes a second steam turbine (4), a second heat exchanger (9) and a second condenser (12); The circulating organic working medium heat exchange outlet of the first heat exchanger (8) is connected to the circulating organic working medium heat exchange inlet of the second heat exchanger (9), the circulating organic working medium heat exchange outlet of the second heat exchanger (9) is connected to the second steam turbine (4), the exhaust steam outlet of the second steam turbine (4) is connected to the inlet of the second condenser (12), and the condensation outlet of the second condenser (12) is connected to the circulating organic working medium heat exchange inlet of the first heat exchanger (8) via a circulating organic working medium pipeline (20); It also includes a heat network return water pipeline (17) and a fourth heat exchanger (11), wherein the heat network return water pipeline (17) is connected to the third heat exchanger (10) and the fourth heat exchanger (11) in sequence; The bottom of the slag waste heat boiler (2) is provided with a solid particle discharge outlet.

2. The waste incineration waste heat utilization device for recovering flue gas and slag heat according to claim 1 is characterized in that: The flue gas outlet of the flue gas waste heat boiler (6) is connected to the flue gas heat exchange inlet of the second heat exchanger (9).

3. The waste incineration waste heat utilization device for recovering heat from flue gas and slag according to claim 2 is characterized in that: The flue gas heat exchange outlet of the second heat exchanger (9) is connected to the flue gas heat exchange inlet of the fourth heat exchanger (11).

4. The waste incineration waste heat utilization device for recovering heat from flue gas and slag according to claim 1 is characterized in that: The feed inlet of the waste incinerator (1) is connected to a domestic waste conveying device (13).

5. The waste incineration waste heat utilization device for recovering heat from flue gas and slag according to claim 1 is characterized in that: The feed inlet of the waste incinerator (1) is connected to an air conveying device (14).

6. A method for utilizing waste incineration waste heat by recovering heat from flue gas and slag, based on the waste incineration waste heat utilization device by recovering heat from flue gas and slag according to any one of claims 1 to 5, characterized in that: The steps include: Domestic waste enters the waste incinerator (1) and is burned with the aid of air, producing high-temperature slag and high-temperature flue gas; The high-temperature slag enters the slag waste heat boiler (2) to exchange heat with circulating water, and the solid particles are discharged after being cooled; The circulating water absorbs the heat of the slag to become superheated steam, which is sent to the first steam turbine (3) to generate power. The steam after the power generation enters the first heat exchanger (8) to exchange heat with the circulating organic working medium, and then enters the third heat exchanger (10) to continue to exchange heat with the return water of the heat network and condense into water, which then continues to return to the slag waste heat boiler (2); High-temperature flue gas discharged from the waste incinerator (1) enters the flue gas waste heat boiler (6), steam generated in the flue gas waste heat boiler (6) enters the third steam turbine (5) to generate power, and exhaust steam enters the first condenser (7) to be condensed into water and then returns to the flue gas waste heat boiler (6) to complete the cycle.

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