Open type flue gas waste heat utilization system

Abstract

The utility model provides an open type flue gas waste heat utilization system. Comprising a low-temperature economizer, a condensed water input pipeline, a condensed water output pipeline, a low-temperature economizer inlet valve, a low-temperature economizer outlet valve, a bypass pipeline, a low-temperature economizer bypass valve, a condensed water vapor heater, a first input pipeline, a condensed water vapor heater inlet valve, a first output pipeline and a condensed water vapor heater outlet valve. A condensed water vapor heater bypass valve; and a condensed water air heater. According to the utility model, when the low-temperature economizer cannot operate, the condensed water vapor heater is used for heating cold water, and heated hot water is used for heating cold air entering the condensed water air heater, so that the temperature of hot air from the hot air interface of the air pre-heater meets the requirement of entering the air pre-heater.

Description

Technical Field

[0001] The utility model belongs to the technical field of flue gas waste heat utilization in coal-fired thermal power plants, and more specifically, relates to an open flue gas waste heat utilization system. Background Art

[0002] Boiler exhaust heat loss is one of the main heat losses in thermal power plants. The use of exhaust waste heat utilization system can reduce the exhaust temperature, greatly improve the economy of the power plant, and is one of the important ways to improve the thermal efficiency of the unit.

[0003] With the gradual development of flue gas waste heat utilization technology of coal-fired thermal power units, one of the current mainstream flue gas waste heat utilization technologies is the low-temperature economizer-open condensate water heater combined flue gas waste heat utilization technology, which uses open condensate water to absorb the flue gas waste heat of the low-temperature economizer to heat the air preheater inlet cold air required for boiler combustion. Figure 1 The existing low-temperature economizer-open condensate heater combined with flue gas waste heat utilization system is demonstrated. The following problems are inevitable in the use of this system: 1) The exhaust temperature is too low at low load and the flue gas waste heat utilization system cannot operate; 2) The low-temperature economizer is out of operation due to wear, corrosion and leakage, and the flue gas waste heat utilization system also cannot operate.

[0004] The above problems lead to the system being unable to heat the cold air at the air preheater inlet, resulting in the air preheater cold end comprehensive temperature failing to meet equipment requirements, leading to air preheater blockage, low temperature corrosion, and ammonium bisulfate cross-boundary corrosion. Therefore, it is necessary to design a reasonable and optimized flue gas waste heat utilization system that is open, all-weather, and full-load. Utility Model Content

[0005] The purpose of the utility model is to provide an open flue gas waste heat utilization system to ensure that the comprehensive temperature of the cold end of the air preheater is met, adapt to open, all-weather, full-load working conditions, prevent the air preheater from clogging, low-temperature corrosion and ammonium bisulfate cross-border corrosion, and other problems, and the economic benefits are obvious.

[0006] To achieve the above purpose, the utility model provides an open flue gas waste heat utilization system, comprising:

[0007] A low-temperature economizer, which is provided with a flue gas inlet, a flue gas outlet, a condensate inlet and a condensate outlet;

[0008] A condensate input pipeline, one end of which is connected to the condensate inlet.

[0009] A condensate output pipeline, one end of which is connected to the condensate outlet;

[0010] A low-temperature economizer inlet valve is provided on the condensate input pipeline;

[0011] A low-temperature economizer outlet valve is provided on the condensate output pipeline;

[0012] A bypass pipeline, two ends of which are respectively connected to the condensate input pipeline and the condensate output pipeline;

[0013] A low-temperature economizer bypass valve is provided on the bypass pipeline;

[0014] A condensate steam heater is provided with a steam inlet, a drain outlet, a cold water inlet and a hot water outlet;

[0015] A first input pipeline, two ends of which are respectively connected to the cold water inlet and the condensate output pipeline;

[0016] An inlet valve of the condensate steam heater is arranged on the first input pipeline;

[0017] A first output pipeline, two ends of which are respectively connected to the hot water outlet and the condensate output pipeline;

[0018] The condensate steam heater outlet valve is arranged on the first output pipeline;

[0019] a condensate steam heater bypass valve, disposed between the connection points of the first input pipeline, the first output pipeline and the condensate output pipeline; and

[0020] The condensate water heater is provided with a cold air inlet, an air preheater hot air interface, a hot water inlet and a cold water outlet; the other end of the condensate water output pipeline is connected to the hot water inlet;

[0021] The first input pipeline and the first output pipeline are both connected to the outlet side of the bypass pipeline.

[0022] Furthermore, the other end of the condensate input pipeline is connected to a condensate system.

[0023] Furthermore, the cold water outlet is connected to a condensate water system.

[0024] Furthermore, a condensate booster pump is provided on the condensate input pipeline.

[0025] Furthermore, the condensate booster pump is arranged at the inlet side of the low-temperature economizer inlet valve and the bypass pipeline.

[0026] Furthermore, the steam inlet is connected to a steam pipeline for inputting heating steam into the condensate vapor heater.

[0027] Furthermore, the drain outlet is connected to a drainage pipeline for discharging condensed water after heat exchange cooling.

[0028] Furthermore, the flue gas inlet is connected to the flue gas pipeline at the air preheater outlet.

[0029] Furthermore, the low-temperature economizer is provided in plurality, and the plurality of the low-temperature economizers are connected in parallel; the condensate water heater is provided in plurality, and the plurality of the condensate water heater is connected in parallel.

[0030] Furthermore, the low-temperature economizer inlet valve, the low-temperature economizer outlet valve, the low-temperature economizer bypass valve, the condensate steam heater inlet valve, the condensate steam heater outlet valve and the condensate steam heater bypass valve are all electric valves.

[0031] Compared with the prior art, the utility model has the following technical effects:

[0032] The utility model discloses an open flue gas waste heat utilization system which adds bypass pipelines and condensate steam heaters and other equipment. When the low-temperature economizer cannot operate, the condensate steam heater can be used to heat cold water, and the heated hot water can be used to heat the cold air entering the condensate water heater, so that the temperature of the hot air coming out of the hot air interface of the air preheater meets the requirements for entering the air preheater, ensuring that the comprehensive temperature of the cold end of the air preheater is met, and can adapt to open, all-weather, full-load working conditions, prevent the air preheater from being blocked, low-temperature corrosion, and ammonium bisulfate cross-border corrosion, and has obvious economic benefits.

[0033] The utility model provides an open flue gas waste heat utilization system which can control the states of various devices and valves according to the specific situation and state of the unit, thereby ensuring the stable operation of the flue gas waste heat utilization system and improving the economic efficiency of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 A schematic diagram of the structure of an existing low-temperature economizer-open condensate heater combined with flue gas waste heat utilization system provided as background technology;

[0036] Figure 2 A schematic structural diagram of an open flue gas waste heat utilization system provided in an embodiment of the utility model.

[0037] Among them, the reference numerals in the figure are:

[0038] 1. Low-temperature economizer, 2. Condensate heater, 3. Condensate booster pump, 4. Low-temperature economizer inlet valve, 5. Low-temperature economizer outlet valve, 6. Low-temperature economizer bypass valve, 7. Condensate steam heater inlet valve, 8. Condensate steam heater outlet valve, 9. Condensate steam heater bypass valve, 10. Condensate steam heater, 100. Condensate input pipeline, 200. Condensate output pipeline, 300. Bypass pipeline, 400. First input pipeline, 500. First output pipeline. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0041] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0042] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present invention, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0043] See also Figure 2 Now, an open flue gas waste heat utilization system provided by an embodiment of the utility model is described.

[0044] In one embodiment, an open flue gas waste heat utilization system of an embodiment of the utility model includes: a low-temperature economizer 1, a condensate input pipeline 100, a condensate output pipeline 200, a low-temperature economizer inlet valve 4, a low-temperature economizer outlet valve 5, a bypass pipeline 300, a low-temperature economizer bypass valve 6, a condensate steam heater 10, a first input pipeline 400, a condensate steam heater inlet valve 7, a first output pipeline 500, a condensate steam heater outlet valve 8, a condensate steam heater bypass valve 9 and a condensate heater 2. The low-temperature economizer 1 is provided with a flue gas inlet, a flue gas outlet, a condensate inlet and a condensate outlet; one end of the condensate input pipeline 100 is connected to the condensate inlet on the low-temperature economizer 1, and one end of the condensate output pipeline 200 is connected to the condensate outlet on the low-temperature economizer 1; the low-temperature economizer inlet valve 4 is arranged on the condensate input pipeline 100; the low-temperature economizer outlet valve 5 is arranged on the condensate output pipeline 200; the two ends of the bypass pipeline 300 are respectively connected to the condensate input pipeline 100 and the condensate output pipeline 200; the low-temperature economizer bypass valve 6 is arranged on the bypass pipeline 300; the condensate steam heater 10 is provided with a steam inlet, a drain outlet, a cold water inlet and a hot water outlet; the two ends of the first input pipeline 400 are respectively connected to the cold water inlet on the condensate steam heater 10 The condensate steam heater inlet valve 7 is arranged on the first input pipeline 400; the two ends of the first output pipeline 500 are respectively connected to the hot water outlet on the condensate steam heater 10 and the condensate output pipeline 200; the condensate steam heater outlet valve 8 is arranged on the first output pipeline 500; the condensate steam heater bypass valve 9 is arranged between the connection points of the first input pipeline 400, the first output pipeline 500 and the condensate output pipeline 200; the condensate water heater 2 is provided with a cold air inlet, an air preheater hot air interface, a hot water inlet and a cold water outlet; the other end of the condensate output pipeline 200 is connected to the hot water inlet on the condensate water heater 2; the first input pipeline 400 and the first output pipeline 500 are both connected to the outlet side of the bypass pipeline 300.

[0045] An open flue gas waste heat utilization system according to an embodiment of the utility model is equipped with a bypass pipeline 300 and a condensate steam heater 10 and other equipment. When the low-temperature economizer 1 cannot operate, the condensate steam heater 10 can be used to heat the cold water, and the heated hot water can be used to heat the cold air entering the condensate heater 2, so that the temperature of the hot air coming out of the hot air interface of the air preheater meets the requirements for entering the air preheater, ensuring that the comprehensive temperature of the cold end of the air preheater is met, and can adapt to open, all-weather, full-load conditions, prevent the air preheater from clogging, low-temperature corrosion, and cross-boundary corrosion of ammonium bisulfate, and have obvious economic benefits.

[0046] Furthermore, the other end of the condensate input pipeline 100 of this embodiment is connected to the condensate system, and the cooled condensate enters the low-temperature economizer 1 or the condensate steam heater 10 from the condensate system through the condensate input pipeline 100 to be heated by heat exchange.

[0047] Furthermore, the cold water outlet on the condensate water heater 2 of the present embodiment is connected to the condensate water system, and the water after heat exchange and cooling enters the condensate water system again for storage.

[0048] Furthermore, the condensate input pipeline 100 of this embodiment is provided with a condensate booster pump 3 to boost the pressure of the condensate and overcome the resistance of the condensate pipeline system so that the condensate can smoothly enter the subsequent low-temperature economizer 1 or condensate steam heater 10 .

[0049] Furthermore, the condensate booster pump 3 of this embodiment is arranged at the inlet side of the low-temperature economizer inlet valve 4 and the bypass pipeline 300. In this way, the water entering the low-temperature economizer 1 or the bypass pipeline 300 is all pressurized.

[0050] Furthermore, the steam inlet of the condensate steam heater 10 of the present embodiment is connected to a steam pipeline for inputting heating steam into the condensate steam heater 10 .

[0051] Furthermore, the drain outlet of the condensate steam heater 10 of this embodiment is connected to a drainage pipeline for discharging condensate after heat exchange cooling.

[0052] Furthermore, the flue gas inlet on the low-temperature economizer 1 of the present embodiment is connected to the flue gas pipeline at the air preheater outlet, and the flue gas at the air preheater outlet is used as the heating flue gas for the low-temperature economizer 1 .

[0053] Furthermore, in this embodiment, a plurality of low-temperature economizers 1 are provided, and the plurality of low-temperature economizers 1 are connected in parallel; a plurality of condensate water heaters 2 are provided, and the plurality of condensate water heaters 2 are connected in parallel.

[0054] Furthermore, the low-temperature economizer inlet valve 4, the low-temperature economizer outlet valve 5, the low-temperature economizer bypass valve 6, the condensate steam heater inlet valve 7, the condensate steam heater outlet valve 8 and the condensate steam heater bypass valve 9 of this embodiment are all electric valves.

[0055] When an open flue gas waste heat utilization system of this embodiment is in operation, it can be divided into two categories: normal operating conditions and abnormal accident operating conditions:

[0056] 1) Normal working conditions:

[0057] (1) When the summer ventilation outdoor calculated temperature or the multi-year average temperature is used as the system ambient temperature and the unit is running at a load of 30% or less during startup, the winter heating outdoor calculated temperature is used as the system ambient temperature and the unit is running at a load of 50% or less during startup, or the unit is in deep peak-shifting operation, the air preheater exhaust gas temperature is lower than 90°C, and the flue gas waste heat cannot be used to heat the cold water from the condensate input pipeline 100, the system needs to close the low-temperature economizer inlet valve 4 and the low-temperature economizer outlet valve 5, open the low-temperature economizer bypass valve 6, cut off the low-temperature economizer 1, open the condensate steam heater inlet valve 7 and the condensate steam heater outlet valve 8, close the condensate steam heater bypass valve 9, use the condensate steam heater 10 and the condensate water heater 2 to heat the cold air, and control the air preheater inlet cold air temperature (i.e., the air preheater hot air interface of the condensate water heater 2) to reach the design 40-100°C (typical preferred value 65°C). At the same time, the resistance on the flue gas side of the air preheater is monitored to ensure that the comprehensive temperature at the cold end of the air preheater satisfies the requirement that low-temperature corrosion and ammonium bisulfate cross-boundary corrosion will not occur in the air preheater.

[0058] (2) When the outdoor calculated temperature for summer ventilation or the multi-year average temperature is used as the system ambient temperature and the unit operates at a load of 30% to 50% or above, and the outdoor calculated temperature for winter heating is used as the system ambient temperature and the unit operates at a load of 50% to 75%, the air preheater exhaust temperature is above 90°C, but the available heat of the flue gas waste heat of the low-temperature economizer 1 is insufficient to heat the air preheater inlet cold air to the design temperature of 40 to 100°C (typically preferred value 65°C), the system needs to open the low-temperature economizer inlet valve 4 and the low-temperature economizer outlet valve 5, close the low-temperature economizer bypass valve 6, put the low-temperature economizer 1 into operation, keep the condensate steam heater inlet valve 7 and the condensate steam heater outlet valve 8 in the open state, and use the condensate steam heater 10, the low-temperature economizer 1 and the condensate water heater 2 to heat the cold air to the design temperature of 40 to 100°C (typically preferred value 65°C). At the same time, the resistance on the flue gas side of the air preheater is monitored to ensure that the comprehensive temperature at the cold end of the air preheater satisfies the requirement that low-temperature corrosion and ammonium bisulfate cross-boundary corrosion will not occur in the air preheater.

[0059] (3) When the outdoor calculated temperature for summer ventilation or the multi-year average temperature is used as the system ambient temperature and the unit is running at 50% or more load, and the outdoor calculated temperature for winter heating is used as the system ambient temperature and the unit is running at 100% load, the exhaust gas temperature of the air preheater is above 90°C, and the flue gas waste heat of the low-temperature economizer 1 is sufficient to heat the cold air at the inlet of the air preheater to the design temperature of 40-100°C (typical preferred value 65°C). The low-temperature economizer inlet valve 4 and the low-temperature economizer outlet valve 5 are kept open, the condensate steam heater inlet valve 7 and the condensate steam heater outlet valve 8 are closed, the condensate steam heater bypass valve 9 is opened, and the condensate steam heater 10 is shut down. At the same time, the air preheater flue gas side resistance is monitored to ensure that the comprehensive temperature at the cold end of the air preheater satisfies the air preheater and does not cause low-temperature corrosion and ammonium bisulfate cross-boundary corrosion.

[0060] 2) Abnormal accident conditions:

[0061] When the low-temperature economizer 1 cannot be put into operation due to wear and leakage, the system needs to close the low-temperature economizer inlet valve 4 and the low-temperature economizer outlet valve 5, open the low-temperature economizer bypass valve 6, cut off the low-temperature economizer 1, open the condensate steam heater inlet valve 7 and the condensate steam heater outlet valve 8, close the condensate steam heater bypass valve 9, and only use the condensate steam heater 10 and the condensate water heater 2 to heat the air preheater cold air to the design temperature of 40-100°C (typical preferred value 65°C), and at the same time monitor the air preheater flue gas side resistance so that the comprehensive temperature of the cold end of the air preheater satisfies the air preheater without low-temperature corrosion and ammonium bisulfate cross-boundary corrosion.

[0062] An open flue gas waste heat utilization system of this embodiment can cut off the low-temperature economizer 1 when the load is low or the low-temperature economizer 1 is worn, corroded or leaked, making it impossible to put the low-temperature economizer 1 into operation. The condensate steam heater 10 can be used to heat the cold air to ensure a reasonable air preheater inlet air temperature.

[0063] An open flue gas waste heat utilization system in this embodiment can adapt to open, all-weather, full-load conditions by controlling the states of various devices and valves according to the specific conditions and status of the unit, and prevent problems such as air preheater blockage, low-temperature corrosion, and ammonium bisulfate cross-boundary corrosion, with obvious economic benefits.

[0064] An open flue gas waste heat utilization system in this embodiment is suitable for the flue gas waste heat utilization system of supercritical or ultra-supercritical, single reheat or double reheat coal-fired thermal power plants. While ensuring that the flue gas waste heat utilization system can adapt to various working conditions and operate stably, it can also improve the economy of unit operation.

[0065] The above embodiments only express several implementation methods of the utility model, and the descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. An open flue gas waste heat utilization system, characterized in that: include: A low-temperature economizer, which is provided with a flue gas inlet, a flue gas outlet, a condensate inlet and a condensate outlet; A condensate input pipeline, one end of which is connected to the condensate inlet. A condensate output pipeline, one end of which is connected to the condensate outlet; A low-temperature economizer inlet valve is provided on the condensate input pipeline; A low-temperature economizer outlet valve is provided on the condensate output pipeline; A bypass pipeline, two ends of which are respectively connected to the condensate input pipeline and the condensate output pipeline; A low-temperature economizer bypass valve is provided on the bypass pipeline; A condensate steam heater is provided with a steam inlet, a drain outlet, a cold water inlet and a hot water outlet; A first input pipeline, two ends of which are respectively connected to the cold water inlet and the condensate output pipeline; An inlet valve of the condensate steam heater is arranged on the first input pipeline; A first output pipeline, two ends of which are respectively connected to the hot water outlet and the condensate output pipeline; The condensate steam heater outlet valve is arranged on the first output pipeline; a condensate steam heater bypass valve, disposed between the connection points of the first input pipeline, the first output pipeline and the condensate output pipeline; and The condensate water heater is provided with a cold air inlet, an air preheater hot air interface, a hot water inlet and a cold water outlet; the other end of the condensate water output pipeline is connected to the hot water inlet; The first input pipeline and the first output pipeline are both connected to the outlet side of the bypass pipeline.

2. The open flue gas waste heat utilization system according to claim 1, characterized in that: The other end of the condensate input pipeline is connected to the condensate system.

3. The open flue gas waste heat utilization system according to claim 1, characterized in that: The cold water outlet is connected to a condensate water system.

4. The open flue gas waste heat utilization system according to claim 1, characterized in that: The condensate input pipeline is provided with a condensate booster pump.

5. The open flue gas waste heat utilization system according to claim 4, characterized in that: The condensate booster pump is arranged at the inlet side of the low-temperature economizer inlet valve and the bypass pipeline.

6. The open flue gas waste heat utilization system according to claim 1, characterized in that: The steam inlet is connected to a steam pipeline for inputting heating steam into the condensate steam heater.

7. The open flue gas waste heat utilization system according to claim 1, characterized in that: The drain outlet is connected to a drainage pipeline for discharging condensed water after heat exchange cooling.

8. The open flue gas waste heat utilization system according to claim 1, characterized in that: The flue gas inlet is connected to the air preheater outlet flue gas pipeline.

9. The open flue gas waste heat utilization system according to claim 1, characterized in that: There are multiple low-temperature economizers, which are connected in parallel; there are multiple condensate water heaters, which are connected in parallel.

10. An open flue gas waste heat utilization system according to any one of claims 1 to 9, characterized in that: The low-temperature economizer inlet valve, the low-temperature economizer outlet valve, the low-temperature economizer bypass valve, the condensate steam heater inlet valve, the condensate steam heater outlet valve and the condensate steam heater bypass valve are all electric valves.

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