CN215863335U - Cold air heating and flue gas waste heat cascade utilization system for power station - Google Patents
Cold air heating and flue gas waste heat cascade utilization system for power station Download PDFInfo
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Abstract
The utility model protects a cold air heating and flue gas waste heat cascade utilization system of a power station, a flue at the downstream of an air preheater is provided with a flue gas cooler, a high-temperature steam pipeline is connected with at least 1 steam inlet of a backpressure steam turbine generator set, and a steam outlet of the backpressure steam turbine generator set is connected with a steam inlet of a fan heater system; the air inlet of the air heater system is connected with a cold air pipeline, the cold air pipeline at the downstream of an air outlet of the air heater system is communicated with the air inlet of the air preheater, the air heater system further comprises a condensate water pipeline, a water inlet of the condensate water pipeline is connected with a condensate water pipe at the downstream of the last-stage low-pressure heater of the unit, and the condensate water pipeline sequentially passes through the smoke cooler and the smoke-condensate water heat exchanger according to the flow direction of condensate water and then returns to the upstream of the first-stage low-pressure heater of the unit. The utility model utilizes the exhaust steam of the back pressure steam turbine to heat the boiler cold air in a grading way, and replaces the heat energy of the high-temperature flue gas to heat the condensed water and the water supply, thereby realizing the gradient utilization of energy and saving the use amount of coal.
Description
Technical Field
The utility model belongs to the field of thermal power generation energy conservation and emission reduction, and relates to a cascade comprehensive utilization system for cold air heating and flue gas waste heat of a power station boiler.
Background
Energy conservation and emission reduction of large-scale thermal power generating sets are important fields of energy conservation and emission reduction in China, and meanwhile, energy conservation and emission reduction are basic strategies which need to be adhered to for a long time in coal-fired power plants in China. At present, coal-fired power plants consume more than half of the nationwide produced coal, so that the potential for energy-saving modification of thermal power generating units is huge. In order to adapt to the development of the electric power market, improve the operation efficiency of power generation equipment and exploit the energy-saving potential of a power plant, a large-scale coal-fired unit develops and implements research and application of a large amount of waste heat utilization, and remarkable coal-saving and emission-reducing effects are obtained. How to further improve the energy utilization rate of the units of the coal-fired power station, reduce the coal consumption of power generation, deeply optimize the system and excavate the energy-saving potential becomes the next research subject of the coal-fired power station.
The boiler exhaust gas temperature of the conventional large coal-fired unit is between 120 ℃ and 140 ℃, and the exhaust gas with the temperature directly discharged to the atmosphere without being treated causes certain energy waste. According to different coal qualities, the thermal efficiency of the boiler is generally between 93% and 95%, wherein the heat loss of exhaust gas is the largest one of the heat losses of the boiler, the heat loss of the exhaust gas of the boiler accounts for about 80% of the total loss of the boiler, the efficiency of the boiler is reduced by 1% when the temperature of the exhaust gas is increased by 10 ℃ to 15 ℃, and the standard coal consumption is increased by 3g to 4 g/kwh. Therefore, the key to improving the thermal efficiency of the boiler is to try to reduce the flue gas temperature or to maximize the recovery of the flue gas heat.
At present, a medium-speed mill positive pressure direct-blowing pulverizing system is generally adopted by a large coal-fired power station in China, for example, fig. 1 shows a structural schematic diagram of a cold air heating and flue gas waste heat utilization system of a conventional power station.
In the coal-fired power plant in northern areas of China, the air temperature is lower in winter, the conventional design of a cold air heating and flue gas waste heat utilization system of the power plant is that a coal-fired unit is provided with a steam air heater heating system, cold air pressurized by a primary fan and a blower adopts a steam air heater heating mode, and the heated cold air enters an air preheater. Because the cold air temperature that gets into air heater only promotes to a certain extent, has increased the heat absorption capacity of cold air in air heater, leads to the flue gas temperature through air heater lower, consequently the temperature promotion effect of the comdenstion water after the heating of low temperature cigarette cold ware and high temperature cigarette cold ware is not obvious, consequently, present solution all has great energy waste, still has great energy-conserving space.
SUMMERY OF THE UTILITY MODEL
The technical problem to be solved by the utility model is to provide a gradient utilization system for cold air heating and flue gas waste heat of a power station, which can effectively solve the problems and utilize the flue gas waste heat in a gradient manner as much as possible.
The technical means adopted by the utility model are as follows.
A cold air heating and flue gas waste heat cascade utilization system of a power station, a flue at the downstream of an air preheater is provided with a flue gas cooler, the air preheater comprises an air inlet, a high-temperature steam pipeline is connected with a steam inlet of at least 1 backpressure steam turbine generator set, and a steam outlet of the backpressure steam turbine generator set is connected with a steam inlet of at least one group of fan heater systems; the air inlet of the air heater system is connected with the inlet of a cold air pipeline, and the cold air pipeline downstream of the air outlet of the air heater system is communicated with the air inlet of the air preheater; the water inlet of the condensed water pipeline is connected with a condensed water pipe at the downstream of the final-stage low-pressure heater of the unit, and the condensed water pipeline sequentially passes through the smoke cooler and the smoke-condensed water heat exchanger according to the flow direction of condensed water and then returns to the upstream of the first-stage low-pressure heater of the unit; the flue gas-condensed water heat exchanger and the air preheater are arranged in the flue side by side.
The number of the backpressure steam turbine generator sets is 2, and the backpressure steam turbine generator sets are a first backpressure steam turbine generator set and a second backpressure steam turbine generator set which are connected in parallel; a cold air pipeline at the downstream of an air outlet of the air heater system is branched into a primary air pipeline and a secondary air pipeline which are connected in parallel, and the primary air pipeline and the secondary air pipeline are communicated with an air inlet of the air preheater; the air heater system comprises a low-temperature air heater and a high-temperature air heater, wherein the low-temperature air heater and the high-temperature air heater are sequentially arranged on a cold air pipeline according to the flowing direction of cold air; a booster fan is arranged at the upstream of the cold air pipeline; a steam outlet of the first backpressure steam turbine generator set is connected with a steam inlet of a low-temperature air heater, and a condensed water outlet of the low-temperature air heater is communicated with a condensed water inlet of the smoke cooler; a steam outlet of the second backpressure steam turbine generator set is connected with a steam inlet of the high-temperature air heater, and a condensate outlet of the high-temperature air heater is communicated with a condensate inlet of the smoke cooler.
The exhaust back pressure of the first back pressure steam turbine generator set is 15.5kpa, and the exhaust back pressure of the second back pressure steam turbine generator set is 65 kpa.
The back pressure steam turbine generator set is 1 back pressure steam turbine generator set with 15.5kpa of exhaust back pressure, and comprises at least 2 steam outlets; a cold air pipeline at the downstream of an air outlet of the air heater system is branched into a primary air pipeline and a secondary air pipeline which are connected in parallel, and the primary air pipeline and the secondary air pipeline are communicated with an air inlet of the air preheater; the air heater system comprises a low-temperature air heater and a high-temperature air heater, wherein the low-temperature air heater and the high-temperature air heater are sequentially arranged on the cold air pipeline according to the flowing direction of cold air; a booster fan is arranged at the upstream of the cold air pipeline; a steam outlet of the backpressure steam turbine generator set is connected with a steam inlet of a low-temperature air heater, and a condensed water outlet of the low-temperature air heater is communicated with a condensed water inlet of the smoke cooler; and the other steam outlet pressure of the backpressure steam turbine generator set is 65kpa, the steam inlet of the high-temperature air heater is connected, and the condensed water outlet of the high-temperature air heater (6) is communicated with the condensed water inlet of the smoke cooler.
The number of the backpressure steam turbine generator sets is 2, and the backpressure steam turbine generator sets are a third backpressure steam turbine generator set and a fourth backpressure steam turbine generator set which are connected in parallel; the air heater system comprises a first group of air heaters and a second group of air heaters; the cold air pipeline is divided into a primary air-cooled air pipeline and a secondary air-cooled air pipeline which are mutually independent, the first group of air heaters are arranged on the primary air-cooled air pipeline, and the second group of air heaters are arranged on the secondary air-cooled air pipeline; the first group of air heaters comprise a primary air low-temperature air heater and a primary air high-temperature air heater which are sequentially arranged according to the flow direction of cold air, and the second group of air heaters comprise a secondary air low-temperature air heater and a secondary air high-temperature air heater which are sequentially arranged according to the flow direction of the cold air; a steam outlet of the third backpressure steam turbine generator set is provided with 2 branches which are respectively connected with steam inlets of the primary air low-temperature air heater and the secondary air low-temperature air heater, and condensed water outlets of the primary air low-temperature air heater and the secondary air low-temperature air heater are respectively communicated with a condensed water inlet of the smoke cooler; a steam outlet of the fourth backpressure steam turbine generator set is provided with 2 branches which are respectively connected with steam inlets of a primary air high-temperature air heater and a secondary air high-temperature air heater, and condensate water outlets of the primary air high-temperature air heater and the secondary air high-temperature air heater are respectively communicated with a condensate water inlet of a smoke cooler.
The exhaust back pressure of the third back pressure steam turbine generator set is 15.5kpa, and the exhaust back pressure of the fourth back pressure steam turbine generator set is 73 kpa.
The backpressure steam turbine generator set is a fifth backpressure steam turbine generator set with 1 set of exhaust steam backpressure of 15.5kpa, and the fifth backpressure steam turbine generator set comprises at least 2 steam outlets; the air heater system comprises a first group of air heaters and a second group of air heaters, the cold air pipeline is divided into a primary air-cooled air pipeline and a secondary air-cooled air pipeline which are mutually independent, the first group of air heaters are arranged on the primary air-cooled air pipeline, and the second group of air heaters are arranged on the secondary air-cooled air pipeline; the first group of air heaters comprise a primary air low-temperature air heater and a primary air high-temperature air heater which are sequentially arranged according to the flow direction of cold air, and the second group of air heaters comprise a secondary air low-temperature air heater and a secondary air high-temperature air heater which are sequentially arranged according to the flow direction of the cold air; a steam outlet of the fifth back pressure steam turbine generator set is provided with 2 branches which are respectively connected with steam inlets of a primary air low-temperature air heater and a secondary air low-temperature air heater, and condensed water outlets of the primary air low-temperature air heater and the secondary air low-temperature air heater are respectively communicated with a condensed water inlet of the smoke cooler; and the other steam outlet of the fifth back pressure steam turbine generator set is provided with 2 branches which are respectively connected with steam inlets of the primary air high-temperature air heater and the secondary air high-temperature air heater, and condensate water outlets of the primary air high-temperature air heater and the secondary air high-temperature air heater are respectively communicated with a condensate water inlet of the smoke cooler.
And the steam of the high-temperature steam pipeline is from unit extraction steam or auxiliary steam or cold-section steam or hot-section steam.
The flue at the upper part of the flue gas-condensed water heat exchanger is provided with a flue gas-water supply heat exchanger which is communicated with a water supply pipeline; the water inlet pipeline of the water supply pipeline is connected with a high-pressure water supply pipe, and the water outlet pipeline of the water supply pipeline is connected with a high-pressure water pipe in front of a high-pressure heater of the unit; the high-pressure heater of the unit is connected with the flue gas-water supply heat exchanger in parallel.
The smoke cooler comprises a high-temperature smoke cooler and a low-temperature smoke cooler which are arranged along the smoke direction, and the condensed water pipeline is connected to the smoke-condensed water heat exchanger after sequentially passing through the low-temperature smoke cooler and the high-temperature smoke cooler according to the flow direction of condensed water.
The beneficial effects produced by the utility model are as follows.
1. The back pressure steam turbine exhaust steam stage heating boiler primary cold air and secondary cold air heats the boiler cold air to 95 ℃, so that the back pressure steam turbine exhaust steam stage heating boiler can replace a traditional steam air heater device, thereby reducing steam extraction of a steam turbine and improving the operation efficiency of a unit.
2. The utility model greatly increases the temperature of the cold air entering the air preheater, increases the temperature of the cold air entering the air preheater from about 35 ℃ to about 95 ℃ in the original design, and reduces the heat absorption capacity of the cold air in the air preheater.
3. The utility model greatly improves the temperature of the cold air of the boiler, thereby avoiding low-temperature corrosion of the heating surface of the air preheater and finally replacing the heat energy of the high-temperature flue gas, wherein the heat energy of the high-temperature flue gas is used for heating condensed water and water supply, reducing the steam extraction of a high-pressure cylinder and a low-pressure cylinder of a steam turbine and improving the power generation of a main engine; meanwhile, the energy gradient utilization is realized, and the heat efficiency of the unit is improved.
4. The generating capacity of the back pressure machine generator set can be incorporated into a power system of a power plant, so that the plant power consumption rate is reduced, and the power generation coal consumption of the power plant is reduced.
5. The backpressure machine generator set can provide a starting power supply for the black start process of a power plant.
6. The steam of the steam source steam pipeline can select unit extraction steam or auxiliary steam, so that the heat efficiency of the unit is improved.
7. The utility model can effectively save the usage amount of coal and has obvious economic benefit.
Drawings
Fig. 1 is a schematic structural diagram of a conventional cold air heating and flue gas waste heat utilization system of a power station.
Fig. 2 is a schematic system structure diagram of the first embodiment of the present invention.
Fig. 3 is a schematic system structure diagram of a second embodiment of the present invention.
Fig. 4 is a schematic system structure diagram of a third embodiment of the present invention.
Fig. 5 is a schematic system structure diagram of a fourth embodiment of the present invention.
Detailed Description
The utility model relates to a cold air heating and flue gas waste heat cascade utilization system of a power station, wherein a flue at the downstream of an air preheater 1 is provided with a flue gas cooler, the flue gas cooler comprises a high-temperature flue gas cooler 14 and a low-temperature flue gas cooler 13 which are arranged along the direction of flue gas, the air preheater 1 comprises an air inlet, a high-temperature steam pipeline is connected with at least one steam inlet of 1 backpressure steam turbine generator set, and a steam outlet of the backpressure steam turbine generator set is connected with steam inlets of at least one group of fan heater systems; the air inlet of the air heater system is connected with the inlet of a cold air pipeline, and the cold air pipeline downstream of the air outlet of the air heater system is communicated with the air inlet of the air preheater 1;
the water inlet of the condensate water pipeline is connected with a condensate water pipe at the downstream of the final-stage low-pressure heater of the unit, and the condensate water pipeline sequentially passes through a condensate water booster pump, the smoke cooler and the smoke-condensate water heat exchanger 2 according to the flow direction of condensate water and then returns to the water side outlet of the first-stage low-pressure heater of the unit; the flue gas-condensed water heat exchanger 2 and the air preheater 1 are arranged in the flue side by side.
At least 1 backpressure steam turbine generating set can be 1 or 2 or more than 2, and its quantity can set up according to actual need, and this backpressure steam turbine generating set's backpressure design can be adjusted according to system's needs to satisfy the requirement of air stage heating extraction pressure.
The number of the at least one group of the fan heater systems can be 1 group or 2 groups, and the number of the at least one group of the fan heater systems can be set according to actual needs.
As shown in fig. 2, the number of the back pressure turbine generator sets in this embodiment is 2, which is a first back pressure turbine generator set 3 and a second back pressure turbine generator set 5 connected in parallel; the exhaust back pressure of the first back pressure steam turbine generator set 3 is 15.5kpa, and the exhaust back pressure of the second back pressure steam turbine generator set 5 is 65 kpa. A cold air pipeline at the downstream of an air outlet of the air heater system is branched into a primary air pipeline 8 and a secondary air pipeline 9 which are connected in parallel, and the primary air pipeline 8 and the secondary air pipeline 9 are communicated with an air inlet of the air preheater 1; the air heater system comprises a low-temperature air heater 4 and a high-temperature air heater 6, wherein the low-temperature air heater 4 and the high-temperature air heater 6 are sequentially arranged on a cold air pipeline according to the flowing direction of cold air; a booster fan 21 is arranged at the upstream of the cold air pipeline; a steam outlet of the first backpressure steam turbine generator set 3 is connected with a steam inlet of a low-temperature air heater 4, and a condensed water outlet of the low-temperature air heater 4 is communicated with a condensed water inlet of the low-temperature smoke cooler 13; a steam outlet of the second backpressure steam turbine generator set 5 is connected with a steam inlet of the high-temperature air heater 6, and a condensed water outlet of the high-temperature air heater 6 is communicated with a condensed water inlet of the low-temperature smoke cooler 13.
As shown in fig. 3, in this embodiment, the number of the back pressure steam turbine generator sets is 1, and the back pressure steam turbine generator set 10 has 1 exhaust back pressure of 15.5kpa and extraction pressure of 65kpa, and the back pressure steam turbine generator set 10 includes at least 2 steam outlets; a cold air pipeline at the downstream of an air outlet of the air heater system is branched into a primary air pipeline 8 and a secondary air pipeline 9 which are connected in parallel, and the primary air pipeline 8 and the secondary air pipeline 9 are communicated with an air inlet of the air preheater 1; the air heater system comprises a low-temperature air heater 4 and a high-temperature air heater 6, wherein the low-temperature air heater 4 and the high-temperature air heater 6 are sequentially arranged on the cold air pipeline according to the flow direction of cold air; a booster fan 21 is arranged at the upstream of the cold air pipeline; a steam outlet of the backpressure steam turbine generator set 10 is connected with a steam inlet of a low-temperature air heater 4, and a condensed water outlet of the low-temperature air heater 4 is communicated with a condensed water inlet of the low-temperature smoke cooler 13; the other steam outlet of the backpressure steam turbine generator set 10 is connected with the steam inlet of the high-temperature air heater 6, and the condensed water outlet of the high-temperature air heater 6 is communicated with the condensed water inlet of the low-temperature smoke cooler 13.
As shown in fig. 2 and 3, cold air enters through the cold air pipeline inlet, is pressurized by the booster fan 21, and then sequentially enters the low-temperature air heater 4 and the high-temperature air heater 6 for staged heating. The temperature of the cold air after two-stage heating can reach 95 ℃, the heated cold air respectively enters the primary air pipeline 8 and the secondary air pipeline 9, the primary air pipeline 8 is provided with a primary fan 81, the secondary air pipeline 9 is provided with a blower 91, and then the cold air is pressurized by the primary fan 81 and the blower 91 and respectively enters the air preheater 1 through 2 air inlets of the air preheater 1.
Preferably, as shown in fig. 2 and 3, a first damper 71 is provided in a pipeline downstream of the low temperature air heater 4 and upstream of the high temperature air heater 6, and a second damper 72 is provided in a pipeline between a branch of the pipeline downstream of the high temperature air heater 6 and the high temperature air heater 6. The first damper 71 and the second damper 72 are used for adjusting the air flow passing through the low-temperature air heater 4 and the high-temperature air heater 6, so as to ensure the stable back pressure of the back pressure turbine. In the starting process of the main steam turbine generator set, the first air damper 71 and the second air damper 72 are opened by firstly starting the small back pressure generator set, so that the service power consumption in the starting process of the main engine of the power plant can be offset, and the power consumption in the power grid in the starting process is reduced.
As shown in fig. 4, the number of the back pressure turbine generator sets in this embodiment is 2, which is a third back pressure turbine generator set 31 and a fourth back pressure turbine generator set 32 connected in parallel; the exhaust back pressure of the third back pressure turbine generator set 31 is 15.5kpa, and the exhaust back pressure of the fourth back pressure turbine generator set 32 is 73 kpa. The air heater system comprises 2 groups of air heaters; the cold air pipeline is divided into a primary air-cooling air pipeline 82 and a secondary air-cooling air pipeline 92 which are independent from each other, the first group of air heaters are arranged on the primary air-cooling air pipeline 82, and the second group of air heaters are arranged on the secondary air-cooling air pipeline 92; the first group of air heaters includes a primary air low-temperature air heater 41 and a primary air high-temperature air heater 61 which are sequentially arranged according to the cold air flow direction, and the second group of air heaters includes a secondary air low-temperature air heater 42 and a secondary air high-temperature air heater 62 which are sequentially arranged according to the cold air flow direction. A steam outlet of the third back pressure steam turbine generator set 31 is provided with 2 branches which are respectively connected with steam inlets of the primary air low-temperature air heater 41 and the secondary air low-temperature air heater 42, and condensed water outlets of the primary air low-temperature air heater 41 and the secondary air low-temperature air heater 42 are respectively communicated with a condensed water inlet of the low-temperature smoke cooler 13; a steam outlet of the fourth back pressure steam turbine generator set 32 is provided with 2 branches which are respectively connected with steam inlets of the primary air high-temperature air heater 61 and the secondary air high-temperature air heater 62, and condensed water outlets of the primary air high-temperature air heater 61 and the secondary air high-temperature air heater 62 are respectively communicated with a condensed water inlet of the low-temperature smoke cooler 13.
As shown in fig. 5, in this embodiment, the back pressure steam turbine generator set is 1 fifth back pressure steam turbine generator set 33 with the exhaust back pressure of 15.5kpa, and the fifth back pressure steam turbine generator set 33 includes at least 2 steam outlets. The air heater system comprises 2 groups of air heaters. The cold air pipeline is divided into a primary air-cooling air pipeline 82 and a secondary air-cooling air pipeline 92 which are independent from each other, the first group of air heaters are arranged on the primary air-cooling air pipeline 82, and the second group of air heaters are arranged on the secondary air-cooling air pipeline 92; the first group of air heaters includes a primary air low-temperature air heater 41 and a primary air high-temperature air heater 61 which are sequentially arranged according to the cold air flow direction, and the second group of air heaters includes a secondary air low-temperature air heater 42 and a secondary air high-temperature air heater 62 which are sequentially arranged according to the cold air flow direction. A steam outlet of the fifth back pressure steam turbine generator set 33 is provided with 2 branches which are respectively connected with steam inlets of a primary air low-temperature air heater 41 and a secondary air low-temperature air heater 42, and condensed water outlets of the primary air low-temperature air heater 41 and the secondary air low-temperature air heater 42 are respectively communicated with a condensed water inlet of the low-temperature smoke cooler 13; another steam outlet of the fifth back pressure steam turbine generator set 33 is provided with 2 branches which are respectively connected with steam inlets of the primary air high-temperature air heater 61 and the secondary air high-temperature air heater 62, and condensed water outlets of the primary air high-temperature air heater 61 and the secondary air high-temperature air heater 62 are respectively communicated with a condensed water inlet of the low-temperature smoke cooler 13.
As shown in fig. 4 and 5, a primary air blower 81 is disposed on the upstream pipeline of the primary air-cooling air pipeline 82, and after entering through the inlet of the primary air-cooling air pipeline 82 and being pressurized by the primary air blower 81, the cold air enters the primary air low-temperature air heater 41 and the primary air high-temperature air heater 61 in sequence for staged heating. A blower 91 is arranged on the upstream pipeline of the secondary air-cooling air pipeline 92, and cold air entering from the inlet of the secondary air-cooling air pipeline 92 is pressurized by the blower 91 and then sequentially enters the secondary air low-temperature air heater 42 and the secondary air high-temperature air heater 62 for graded heating. The temperature of the cold air can reach 95 ℃ after the cold air is heated by two stages, and the heated cold air enters the air preheater 1 through 2 air inlets of the air preheater 1 respectively.
Preferably, as shown in fig. 4 and 5, a third damper 73 is provided in a pipeline downstream of the primary air low-temperature air heater 41 and upstream of the primary air high-temperature air heater 61, and a fourth damper 74 is provided in a pipeline downstream of the primary air high-temperature air heater 61. A fifth damper 75 is arranged on the pipeline at the downstream of the secondary air low-temperature air heater 42 and at the upstream of the secondary air high-temperature air heater 62, and a sixth damper 76 is arranged on the pipeline at the downstream of the secondary air high-temperature air heater 62. The third damper 73 and the fourth damper 74 are used for regulating the air flow passing through the primary air low-temperature air heater 41 and the primary air high-temperature air heater 61, and the fifth damper 75 and the sixth damper 76 are used for regulating the air flow passing through the secondary air low-temperature air heater 42 and the secondary air high-temperature air heater 62, so as to ensure the stable back pressure of the back pressure turbine; meanwhile, in the starting process of the main steam turbine generator set, the third air damper 73, the fourth air damper 74, the fifth air damper 75 and the sixth air damper 76 are opened, so that the unit power consumption in the starting process of the power plant main engine can be reduced, and the power taking amount from the power grid in the starting process is reduced.
As shown in fig. 2 to 5, the condensed water pipeline passes through the low-temperature flue gas cooler 13 and the high-temperature flue gas cooler 14 in sequence according to the flow direction of the condensed water and then is connected to the flue gas-condensed water heat exchanger 2. Since the temperature of the cold air entering the air preheater 1 rises from about 35 c, which is a conventional design, to about 95 c, the amount of heat absorption of the cold air in the air preheater 1 is greatly reduced, thereby resulting in a substantial increase in the flue gas temperature downstream of the air preheater 1. Therefore, the condensed water in the condensed water pipeline can be heated by utilizing the high temperature of the flue gas of the downstream flue, and the temperature raising effect of the condensed water is obvious.
As shown in fig. 2 to 5, a flue gas-feedwater heat exchanger 7 is arranged in the upstream flue of the flue gas-condensate heat exchanger 2, and the flue gas-feedwater heat exchanger 7 is communicated with a feedwater pipeline. A water inlet pipeline of the water supply pipeline is connected with a high-pressure water supply pipe, and a water outlet pipeline of the water supply pipeline is connected with a high-pressure water pipe in front of a high-pressure heater of the unit; the high-pressure heater of the unit is connected in parallel with the flue gas-feedwater heat exchanger 7. The high temperature of the flue gas is used for heating the water supply, thereby replacing the heat of the steam extraction of the high-pressure heater, saving the high-pressure steam extraction and increasing the work capacity of the unit.
Preferably, the steam of the high-temperature steam pipeline is from unit extraction steam or auxiliary steam or cold-stage steam or hot-stage steam.
According to the measurement and calculation of relevant host parameters of a power plant with 2 x 660MW directly air-cooled by lignite for combustion in the north of China, the method is calculated according to the condition that the annual average air temperature in the north is 0 ℃, the steam extractor system is set to adopt a steam turbine to extract steam for steam supply, the inlet temperature of an air preheater 1 is about 95 ℃, and the back pressure machine supplies steam to adopt four-section steam extraction for steam supply, the economical efficiency is measured and calculated according to the boiler efficiency of 94.3%, and the measurement and calculation result is that the coal quantity is saved by about 3-4g/kw.h compared with the conventional flue gas waste heat utilization scheme, and the coal quantity is saved by about 6-7g/kw.h compared with the smokeless waste heat utilization scheme.
The utility model improves the boiler efficiency, reduces the heat consumption of the unit, improves the economical efficiency of the operation of the thermal power plant, and has obvious economic efficiency.
Claims (10)
1. A cold air heating and flue gas waste heat cascade utilization system of a power station, the downstream flue of the air preheater (1) has a flue gas cooler, the air preheater (1) includes the air inlet, characterized by that, the high-temperature steam pipeline connects a steam inlet of at least 1 backpressure steam turbine generator sets, a steam outlet of the backpressure steam turbine generator sets connects the steam inlet of at least a series of air heater systems; the air inlet of the air heater system is connected with the inlet of a cold air pipeline, and the cold air pipeline downstream of the air outlet of the air heater system is communicated with the air inlet of the air preheater (1);
the water inlet of the condensed water pipeline is connected with a condensed water pipe at the downstream of the last-stage low-pressure heater of the unit, and the condensed water pipeline sequentially passes through the smoke cooler and the smoke-condensed water heat exchanger (2) according to the flow direction of condensed water and then returns to the upstream of the first-stage low-pressure heater of the unit; the flue gas-condensed water heat exchanger (2) and the air preheater (1) are arranged in the flue side by side.
2. The cascade utilization system for the cold wind heating and the flue gas waste heat of the power station as claimed in claim 1, wherein the number of the back pressure steam turbine generator sets is 2, and the back pressure steam turbine generator sets are a first back pressure steam turbine generator set (3) and a second back pressure steam turbine generator set (5) which are connected in parallel; a cold air pipeline at the downstream of an air outlet of the air heater system is branched into a primary air pipeline (8) and a secondary air pipeline (9) which are connected in parallel, and the primary air pipeline (8) and the secondary air pipeline (9) are communicated with an air inlet of the air preheater (1); the air heater system comprises a low-temperature air heater (4) and a high-temperature air heater (6), wherein the low-temperature air heater (4) and the high-temperature air heater (6) are sequentially arranged on a cold air pipeline according to the flowing direction of cold air; a booster fan (21) is arranged at the upstream of the cold air pipeline; a steam outlet of the first backpressure steam turbine generator set (3) is connected with a steam inlet of a low-temperature air heater (4), and a condensed water outlet of the low-temperature air heater (4) is communicated with a condensed water inlet of the smoke cooler; a steam outlet of the second backpressure steam turbine generator set (5) is connected with a steam inlet of the high-temperature air heater (6), and a condensed water outlet of the high-temperature air heater (6) is communicated with a condensed water inlet of the smoke cooler.
3. The cascade utilization system for cold wind heating and flue gas waste heat of power station as claimed in claim 2, wherein the exhaust back pressure of the first back pressure steam turbine generator set (3) is 15.5kpa, and the exhaust back pressure of the second back pressure steam turbine generator set (5) is 65 kpa.
4. The cascade utilization system for the cold wind heating and the flue gas waste heat of the power station as claimed in claim 1, wherein the back pressure steam turbine generator set is 1 back pressure steam turbine generator set (10) with 15.5kpa of exhaust steam back pressure, and the back pressure steam turbine generator set (10) comprises at least 2 steam outlets; a cold air pipeline at the downstream of an air outlet of the air heater system is branched into a primary air pipeline (8) and a secondary air pipeline (9) which are connected in parallel, and the primary air pipeline (8) and the secondary air pipeline (9) are communicated with an air inlet of the air preheater (1); the air heater system comprises a low-temperature air heater (4) and a high-temperature air heater (6), wherein the low-temperature air heater (4) and the high-temperature air heater (6) are sequentially arranged on the cold air pipeline according to the flow direction of cold air; a booster fan (21) is arranged at the upstream of the cold air pipeline; a steam outlet of the backpressure steam turbine generator set (10) is connected with a steam inlet of a low-temperature air heater (4), and a condensed water outlet of the low-temperature air heater (4) is communicated with a condensed water inlet of the smoke cooler; the other steam outlet of the backpressure steam turbine generator set (10) is connected with the steam inlet of the high-temperature air heater (6), and the condensed water outlet of the high-temperature air heater (6) is communicated with the condensed water inlet of the smoke cooler.
5. The cascade utilization system for the cold wind heating and the flue gas waste heat of the power station as claimed in claim 1, wherein the number of the back pressure steam turbine generator sets is 2, and the back pressure steam turbine generator sets are a third back pressure steam turbine generator set (31) and a fourth back pressure steam turbine generator set (32) which are connected in parallel; the air heater system comprises a first group of air heaters and a second group of air heaters; the cold air pipeline is divided into a primary air-cooling air pipeline (82) and a secondary air-cooling air pipeline (92) which are independent of each other, the first group of air heaters are arranged on the primary air-cooling air pipeline (82), and the second group of air heaters are arranged on the secondary air-cooling air pipeline (92); the first group of air heaters comprise a primary air low-temperature air heater (41) and a primary air high-temperature air heater (61) which are sequentially arranged according to the flow direction of cold air, and the second group of air heaters comprise a secondary air low-temperature air heater (42) and a secondary air high-temperature air heater (62) which are sequentially arranged according to the flow direction of the cold air; a steam outlet of the third backpressure steam turbine generator set (31) is provided with 2 branches which are respectively connected with steam inlets of the primary air low-temperature air heater (41) and the secondary air low-temperature air heater (42), and condensed water outlets of the primary air low-temperature air heater (41) and the secondary air low-temperature air heater (42) are respectively communicated with a condensed water inlet of the smoke cooler; a steam outlet of the fourth backpressure steam turbine generator set (32) is provided with 2 branches which are respectively connected with steam inlets of a primary air high-temperature air heater (61) and a secondary air high-temperature air heater (62), and condensed water outlets of the primary air high-temperature air heater (61) and the secondary air high-temperature air heater (62) are respectively communicated with a condensed water inlet of the smoke cooler.
6. The cascade utilization system for cold wind heating and flue gas waste heat of power station as claimed in claim 5, wherein the exhaust back pressure of the third back pressure turbine generator set (31) is 15.5kpa, and the exhaust back pressure of the fourth back pressure turbine generator set (32) is 73 kpa.
7. The cascade utilization system for the cold wind heating and the flue gas waste heat of the power station as claimed in claim 1, wherein the back pressure steam turbine generator set is a fifth back pressure steam turbine generator set (33) with 1 exhaust steam back pressure of 15.5kpa, and the fifth back pressure steam turbine generator set (33) comprises at least 2 steam outlets; the air heater system comprises a first group of air heaters and a second group of air heaters, the cold air pipeline is divided into a primary air-cooled air pipeline (82) and a secondary air-cooled air pipeline (92) which are independent of each other, the first group of air heaters are arranged on the primary air-cooled air pipeline (82), and the second group of air heaters are arranged on the secondary air-cooled air pipeline (92); the first group of air heaters comprise a primary air low-temperature air heater (41) and a primary air high-temperature air heater (61) which are sequentially arranged according to the flow direction of cold air, and the second group of air heaters comprise a secondary air low-temperature air heater (42) and a secondary air high-temperature air heater (62) which are sequentially arranged according to the flow direction of the cold air; a steam outlet of the fifth backpressure steam turbine generator set (33) is provided with 2 branches which are respectively connected with steam inlets of a primary air low-temperature air heater (41) and a secondary air low-temperature air heater (42), and condensed water outlets of the primary air low-temperature air heater (41) and the secondary air low-temperature air heater (42) are respectively communicated with a condensed water inlet of the smoke cooler; another steam outlet of the fifth backpressure steam turbine generator set (33) is provided with 2 branches which are respectively connected with steam inlets of a primary air high-temperature air heater (61) and a secondary air high-temperature air heater (62), and condensed water outlets of the primary air high-temperature air heater (61) and the secondary air high-temperature air heater (62) are respectively communicated with a condensed water inlet of the smoke cooler.
8. The cascade utilization system for cold wind heating and flue gas waste heat of power station as claimed in claim 1, wherein the steam of the high temperature steam pipeline is from unit extraction steam or auxiliary steam or cold section steam or hot section steam.
9. The cascade utilization system for cold air heating and waste heat of flue gas in power station as claimed in any one of claims 1 to 8, wherein the flue gas-feed water heat exchanger (7) is arranged in the flue at the upstream of the flue gas-condensed water heat exchanger (2), and the flue gas-feed water heat exchanger (7) is communicated with a feed water pipeline; the water inlet pipeline of the water supply pipeline is connected with a high-pressure water supply pipe, and the water outlet pipeline of the water supply pipeline is connected with a high-pressure water pipe in front of a high-pressure heater of the unit; the high-pressure heater of the unit is connected with the flue gas-water supply heat exchanger (7) in parallel.
10. The cascade utilization system for cold wind heating and flue gas waste heat of power station as claimed in any one of claims 1 to 8, wherein the flue gas cooler comprises a high temperature flue gas cooler (14) and a low temperature flue gas cooler (13) arranged along the flue gas direction, and the condensed water pipeline passes through the low temperature flue gas cooler (13) and the high temperature flue gas cooler (14) in sequence according to the flow direction of condensed water and then is connected to the flue gas-condensed water heat exchanger (2).
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