Flue gas waste heat recovery saturated steam flash evaporation power system

Abstract

The present invention discloses a flue gas waste heat recovery saturated steam flash evaporation power generation system, the system comprises: a flash evaporation expander, a steam turbine, a condenser and a flue gas heat exchanger, the flash evaporation expander, the steam turbine, the condenser and the flue gas heat exchanger are connected end to end in sequence, the flue gas heat exchanger is suitable for being arranged in the flue gas exhaust path of the boiler to perform heat exchange between flue gas and condensate. Thus, the system can effectively reduce the flue gas exhaust temperature of the boiler and reduce heat loss on the one hand, and can reasonably use the flue gas temperature to increase the condensate temperature on the other hand, so that the system can generate electricity, which can not only save energy but also save the investment cost of the project.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat power generation, and in particular to a flue gas waste heat recovery saturated steam flash power generation system. Background Art

[0002] At present, my country's total energy consumption is large, and pollutant emissions are high. The impact on the global climate and environment has attracted much attention from the international community. Reducing pollutant emissions is currently the main way to control environmental pollution.

[0003] In the related art, when the boiler is working, the temperature of the flue gas coming out of the chimney is called the exhaust temperature. The exhaust temperature is 60℃ (electricity)-250℃ (steel / chemical / coking). In addition to the increase of boiler exhaust heat loss and the decrease of boiler efficiency, it will also have a certain impact on the safety and economic operation of subsequent equipment such as dust collectors, fans, desulfurization devices, etc. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide a flue gas waste heat recovery saturated steam flash evaporation power generation system, which can use flue gas waste heat to generate electricity, thereby reducing exhaust heat loss, saving energy, and being environmentally friendly.

[0005] A flue gas waste heat recovery saturated steam flash evaporation power generation system according to an embodiment of the present invention comprises: a flash expansion tank, a steam turbine, a condenser and a flue gas heat exchanger, wherein the flash expansion tank, the steam turbine, the condenser and the flue gas heat exchanger are connected end to end in sequence, and the flue gas heat exchanger is suitable for being arranged in the flue gas exhaust path of the boiler to perform heat exchange between flue gas and condensate at the flue gas heat exchanger.

[0006] According to the flue gas waste heat recovery saturated steam flash evaporation power generation system of the embodiment of the present invention, on the one hand, the exhaust gas temperature can be effectively reduced, and the flue gas heat exchanger reduces the flue gas temperature to 60°C. On the other hand, the flue gas temperature can be reasonably used to increase the condensate temperature, so that the system can generate electricity. This method can effectively recover the flue gas waste heat and use it for power generation, which is in line with the technical scope of energy conservation and comprehensive utilization of resources. It can not only save energy but also save the investment cost of the project.

[0007] In some examples of the present invention, the number of the flash expander is at least two.

[0008] In some examples of the present invention, there are two flash expansion tanks, namely a first-stage flash expansion tank and a second-stage flash expansion tank. Both the first-stage flash expansion tank and the second-stage flash expansion tank are provided with a condensate inlet, a steam outlet and a condensate outlet. The steam outlet of the first-stage flash expansion tank and the steam outlet of the second-stage flash expansion tank are both connected to the steam turbine, the condensate inlet of the first-stage flash expansion tank is connected to the flue gas heat exchanger, the condensate outlet of the first-stage flash expansion tank is connected to the condensate inlet of the second-stage flash expansion tank, and the condensate outlet of the second-stage flash expansion tank is connected to the flue gas heat exchanger.

[0009] In some examples of the present invention, the system further includes: a water mixer, through which the condensate outlet of the secondary flash expansion tank and the condensate outlet of the condenser are connected to the flue gas heat exchanger.

[0010] In some examples of the present invention, a steam inlet control valve is provided between the steam outlet of the first-stage flash expansion tank and the steam inlet of the steam turbine, and a supplementary steam control valve is provided between the steam outlet of the second-stage flash expansion tank and the supplementary steam inlet of the steam turbine.

[0011] In some examples of the present invention, the flue gas heat exchanger includes a cold end heating wall corresponding to the flue gas, and the cold end heating wall is an ND steel plate wall, a Corten steel plate wall, or a fluoroplastic plate wall.

[0012] In some examples of the present invention, the system further includes: a vacuum pumping device connected to the condenser to extract the non-condensable gas inside the condenser.

[0013] In some examples of the present invention, the vacuum pumping equipment includes: a water jet pump and a water jet vacuum pump, the water jet pump is connected to the water jet vacuum pump, and the water jet vacuum pump is also connected to the condenser.

[0014] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0016] Figure 1 is a schematic diagram of a flue gas waste heat recovery saturated steam flash evaporation power system according to an embodiment of the present invention;

[0017] Figure 2 It is a schematic diagram of a flue gas waste heat recovery saturated steam flash evaporation power system according to another embodiment of the present invention.

[0018] Reference numerals:

[0019] Flue gas waste heat recovery saturated steam flash evaporation power generation system 100;

[0020] Boiler 1; dust collector 2; fan 3; flue gas heat exchanger 4; desulfurization device 5; chimney 6;

[0021] The first-stage flash expansion tank 21; the second-stage flash expansion tank 22; the steam turbine 23; the condenser 24; the water mixer 25; the steam inlet control valve 26, and the steam supplement control valve 27. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Embodiments of the present invention are described in detail below.

[0023] Reference below Figure 1-Figure 2 A flue gas waste heat recovery saturated steam flash evaporation power generation system 100 according to an embodiment of the present invention is described. The flue gas waste heat recovery saturated steam flash evaporation power generation system 100 is implemented on a flue gas waste heat recovery system 10, which can reasonably utilize the flue gas of the flue gas waste heat recovery system 10 and can effectively reduce the flue gas temperature.

[0024] like Figure 1 and Figure 2 As shown, the flue gas waste heat recovery system 10 includes: a boiler 1, a dust collector 2, a fan 3 and a desulfurization device 5, which are connected in sequence. The flue gas waste heat recovery system 10 also includes: a chimney 6, which is used to discharge flue gas and is connected after the desulfurization device 5. The desulfurization device 5 can be a desulfurization tower.

[0025] like Figure 1 and Figure 2 As shown, the flue gas waste heat recovery saturated steam flash evaporation power generation system 100 includes: a flash expansion tank, a steam turbine 23, a condenser 24 and a flue gas heat exchanger 4. The flash expansion tank, the steam turbine 23, the condenser 24 and the flue gas heat exchanger 4 are connected end to end in sequence to form a circulation loop, and the flue gas heat exchanger 4 is suitable for being arranged in the exhaust path of the boiler 1 of the flue gas waste heat recovery system 10. The condenser 24 can use the cooling water of the cooling tower to condense the steam exhausted from the steam turbine 23 into condensate.

[0026] Among them, the condensate discharged from the condenser 24 flows into the flue gas heat exchanger 4 and exchanges heat with the flue gas at the flue gas heat exchanger 4, thereby deeply reducing the exhaust temperature. The temperature of the condensate entering the flue gas heat exchanger 4 is 70°C, and the water temperature of the condensate can be increased from 70°C to 100°C, thereby achieving the requirement of saturated steam power generation. The high-temperature condensate enters the flash expansion tank, and a part of the condensate becomes saturated steam after expansion and decompression of the flash expansion tank and is supplied to the turbine 23, thereby generating electricity. The steam passing through the steam turbine 23 is condensed into condensate through the condenser 24, thereby completing a cycle.

[0027] The location of the flue gas heat exchanger 4 is not unique. Figure 1 As shown, the flue gas heat exchanger 4 is connected before the desulfurization device 5. Specifically, the flue gas heat exchanger 4 is connected between the dust collector 2 and the fan 3. The flue gas heat exchanger 4 is arranged before the desulfurization device 5, which can reduce the exhaust gas temperature from a relatively high 175 (electricity)-270°C (steel / chemical / coking) to 115°C (electricity)-210°C (steel / chemical / coking). For another example, Figure 2 As shown, the flue gas heat exchanger 4 is connected after the desulfurization device 5, specifically, the flue gas heat exchanger 4 is connected between the desulfurization device 5 and the chimney 6. The flue gas heat exchanger 4 is arranged after the desulfurization device 5, which can reduce the exhaust gas temperature from a relatively high 250°C (steel / chemical / coking) to 190°C (steel / chemical / coking). Both of the above two types of flue gas heat exchangers 4 can realize energy-saving transformation and utilization of deeply reducing the exhaust gas temperature.

[0028] Therefore, according to the flue gas waste heat recovery saturated steam flash evaporation power generation system 100 of the embodiment of the present invention, on the one hand, the exhaust gas temperature can be effectively reduced. The flue gas heat exchanger 4 reduces the flue gas temperature to 60°C, which can slow down the corrosion of related components of the flue gas waste heat recovery system 10. On the other hand, the flue gas temperature can be reasonably used to increase the condensate temperature, so that the flue gas waste heat recovery saturated steam flash evaporation power generation system 100 can generate electricity. In this way, the condensate after the waste heat flue gas heat exchange can deeply tap its latent heat after the temperature is increased to generate electricity, which greatly improves the energy utilization efficiency, meets the technical scope of energy conservation and comprehensive resource utilization, and can not only save energy but also save the investment cost of the project.

[0029] According to an optional embodiment of the present invention, there are at least two flash expansion tanks. In other words, the flash expansion tank can be a multi-stage flash expansion tank, rather than a single-stage flash expansion tank. The multi-stage flash expansion tank can be used to expand and reduce the pressure of high-temperature condensate water multiple times, so that more flash steam can be used for power generation by the steam turbine 23, which can improve the power generation efficiency of the flue gas waste heat recovery saturated steam flash power generation system 100.

[0030] Furthermore, if Figure 1 and Figure 2 As shown, there are two flash expansion tanks, and the two flash expansion tanks are respectively a primary flash expansion tank 21 and a secondary flash expansion tank 22. Both the primary flash expansion tank 21 and the secondary flash expansion tank 22 are provided with a condensate inlet, a steam outlet and a condensate outlet. The steam outlet of the primary flash expansion tank 21 and the steam outlet of the secondary flash expansion tank 22 are both connected to the steam turbine 23, the condensate inlet of the primary flash expansion tank 21 is connected to the flue gas heat exchanger 4, the condensate outlet of the primary flash expansion tank 21 is connected to the condensate inlet of the secondary flash expansion tank 22, and the condensate outlet of the secondary flash expansion tank 22 is connected to the flue gas heat exchanger 4. In other words, between the flue gas heat exchanger 4 and the steam turbine 23, the first-stage flash expansion tank 21 and the second-stage flash expansion tank 22 are connected in series in sequence, and the second-stage flash expansion tank 22 can also supply the condensed water to the flue gas heat exchanger 4 again for heat exchange. This method can deeply tap the energy in the process of heating the condensed water, and can improve the efficiency of the power plant.

[0031] Among them, a steam inlet control valve 26 is arranged between the steam outlet of the first-stage flash expansion tank 21 and the steam inlet of the steam turbine 23, and the steam inlet control valve 26 can control the amount of steam from the first-stage flash expansion tank 21 entering the steam turbine 23, and a steam supplement control valve 27 is arranged between the steam outlet of the second-stage flash expansion tank 22 and the steam supplement port of the steam turbine 23, and the steam supplement control valve 27 can control the amount of steam from the second-stage flash expansion tank 22 entering the steam turbine 23.

[0032] Specifically, Figure 1 and Figure 2 As shown, the flue gas waste heat recovery saturated steam flash evaporation power generation system 100 also includes: a water mixer 25, and the condensate outlet of the secondary flash expansion tank 22 and the condensate outlet of the condenser 24 are connected to the flue gas heat exchanger 4 through the water mixer 25. In other words, the water mixer 25 has two inlets, and the two inlets are respectively connected to the condensate outlet of the secondary flash expansion tank 22 and the condensate outlet of the condenser 24. The mixer 25 can play a role in mixing condensate, so that the structure of the entire system can be simple, and the condensate flows smoothly and naturally. In addition, it can also be used in the flue gas recovery system of the waste heat boiler 1 of the steel plant, metallurgy, chemical industry, etc. It can not only recover the waste heat of the flue gas, but also improve the power efficiency of the whole plant and reduce the power consumption rate of the plant.

[0033] Optionally, the flue gas heat exchanger 4 includes a cold end heating wall corresponding to the flue gas, and the cold end heating wall is a ND steel plate wall, a Corten steel plate wall, or a fluoroplastic plate wall. Thus, the use of the above materials can solve the problem of low temperature corrosion of the heat transfer tube. According to the test results, it is determined that the operation of the flue gas waste heat recovery system 10 is safe and reliable within the expected 20-year life cycle of the heat exchange equipment using materials such as ND steel, Corten steel, and fluoroplastic.

[0034] If the non-condensable gas in the condenser 24 is not removed in time, the vacuum of the condenser 24 will be gradually destroyed, reducing the operating economy of the unit. In order to ensure the vacuum of the condenser 24 and extract the non-condensable gas in the condenser 24, the flue gas waste heat recovery saturated steam flash evaporation system 100 also includes: a vacuum pump (not shown), which is connected to the condenser 24 to extract the non-condensable gas inside it. The vacuum pump includes: a water jet pump and a water jet vacuum pump, which is connected to the water jet vacuum pump, and the water jet vacuum pump is also connected to the condenser 24. Each unit of this project is equipped with two high-positioned water jet vacuum pumps and two water jet pumps.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0036] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A flue gas waste heat recovery saturated steam flash evaporation power generation system, characterized in that: include: A flash expansion tank, a steam turbine, a condenser and a flue gas heat exchanger, wherein the flash expansion tank, the steam turbine, the condenser and the flue gas heat exchanger are connected end to end in sequence, and the flue gas heat exchanger is suitable for being arranged in the flue gas exhaust path of the boiler so as to perform heat exchange between flue gas and condensed water at the flue gas heat exchanger; There are two flash expansion tanks, which are a primary flash expansion tank and a secondary flash expansion tank respectively. Both the primary flash expansion tank and the secondary flash expansion tank are provided with a condensate inlet, a steam outlet and a condensate outlet. The steam outlet of the primary flash expansion tank and the steam outlet of the secondary flash expansion tank are both connected to the steam turbine. The condensate inlet of the primary flash expansion tank is connected to the flue gas heat exchanger. The condensate outlet of the primary flash expansion tank is connected to the condensate inlet of the secondary flash expansion tank. The condensate outlet of the secondary flash expansion tank is connected to the flue gas heat exchanger. A water mixer, through which the condensate outlet of the secondary flash expansion tank and the condensate outlet of the condenser are connected to the flue gas heat exchanger; A steam inlet control valve is provided between the steam outlet of the first-stage flash expansion tank and the steam inlet of the steam turbine, and a supplementary steam control valve is provided between the steam outlet of the second-stage flash expansion tank and the supplementary steam inlet of the steam turbine; A vacuum pumping device is connected to the condenser to extract the non-condensable gas inside the condenser.

2. The flue gas waste heat recovery saturated steam flash evaporation power generation system according to claim 1 is characterized in that: The flue gas heat exchanger comprises a cold end heating wall corresponding to the flue gas, and the cold end heating wall is an ND steel plate wall, a Corten steel plate wall, or a fluoroplastic plate wall.

3. The flue gas waste heat recovery saturated steam flash evaporation power generation system according to claim 1 is characterized in that: The vacuum pumping equipment comprises: a water jet pump and a water jet vacuum pump, wherein the water jet pump is connected to the water jet vacuum pump, and the water jet vacuum pump is also connected to the condenser.

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