CN210568527U - Device for backheating and heating flue gas by using condensed water - Google Patents
Device for backheating and heating flue gas by using condensed water Download PDFInfo
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- CN210568527U CN210568527U CN201921205101.7U CN201921205101U CN210568527U CN 210568527 U CN210568527 U CN 210568527U CN 201921205101 U CN201921205101 U CN 201921205101U CN 210568527 U CN210568527 U CN 210568527U
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Abstract
The utility model discloses a device for reheating flue gas by using condensed water, which comprises a flue gas pipeline, a waste heat utilization device, boiler tail equipment and a flue gas reheating device, wherein the waste heat utilization device and the flue gas reheating device are both arranged to exchange heat with the flue gas pipeline; the waste heat utilization device and the flue gas reheating device are arranged on two sides of the boiler tail device; flue gas passes through the flue gas duct. The waste heat utilization device, the boiler tail equipment and the flue gas reheating device sequentially flow through. The device utilizes the condensed water at the condensed water side outlet of the low-pressure heater as a supplementary heat source, the condensed water at the outlet of the low-pressure heater is led out to a certain flow to the flue gas reheating device, the condensed water exchanges heat with the flue gas through the flue gas reheating device and then flows back to the inlet of the low-pressure heater, the condensed water is mixed with the condensed water at the inlet of the original low-pressure heater, then the mixed condensed water enters the low-pressure heater for heating, and then flows out through the low-pressure heater to.
Description
Technical Field
The utility model relates to a power plant field especially relates to an utilize low pressure feed water heater export condensate depth to heat device of flue gas.
Background
Wet desulphurization is a main technology for desulphurization in coal-fired power plants, and large coal-fired units basically adopt wet desulphurization, which accounts for about 91% in China. The saturated wet smoke is discharged from a chimney and mixed with ambient air with lower temperature for cooling, wherein the water vapor is supersaturated and condensed, and refracts and scatters light, so that the smoke plume presents white or gray wet smoke plume (commonly called as large white smoke). With the increasingly frequent appearance of haze weather in China, the phenomenon of 'big white smoke' draws wide attention, the visual pollution is serious, and the surrounding environment and the life of residents are seriously influenced.
In 6 months of 2017, Shanghai city was issued "technical requirements for testing gypsum rain and colored smoke plume of coal-fired power plants in Shanghai city" (trial run), and it was required that "the coal-fired power generation boiler should adopt smoke temperature control and other effective measures to eliminate the phenomena of gypsum rain, colored smoke plume, etc.", that is, by adopting a corresponding technique to control the smoke discharge temperature at the outlet of the chimney and reduce the moisture content of the smoke, the moisture in supersaturated water vapor in the smoke is collected, and the discharge of condensable particles such as soluble salt, sulfuric acid mist, organic matters, etc. in the smoke is reduced.
The existing wet smoke plume treatment technology can be classified into three major types, namely heating type, condensing type and condensing reheating type. The heating type and the condensing heating type flue gas heating technology is used for heating wet saturated flue gas at a desulfurization outlet, so that the relative humidity of the flue gas is far away from a saturated humidity curve.
The heating technology is divided into two categories according to the heat exchange mode: namely indirect heat exchange and direct heat exchange. The main representative techniques of indirect heat exchange are: rotary type GGH, tubular type GGH, heat pipe type GGH, MGGH, steam heater, etc. The main representative techniques of direct heat exchange are: hot secondary air mixing heating, direct gas heating, hot air mixing heating and the like.
The MGGH heats the flue gas passing through the desulfurizing tower by using the flue gas waste heat absorbed by the flue gas waste heat utilization device before the desulfurizing tower or electric dust removal, so that the temperature of the flue gas passing through the desulfurizing tower is raised to a required temperature, and the MGGH is more energy-saving compared with other methods. However, in the practical application process, due to the change of the load of the unit and the change of the ambient temperature and humidity, the heat in the flue gas waste heat utilization device is not enough to raise the flue gas temperature to the corresponding value under the corresponding environmental parameters. Therefore, except the flue gas waste heat utilization device, the unit needs to provide other heat sources to assist in heating the flue gas passing through the desulfurizing tower. The prior auxiliary heat source is mainly steam exhausted from a high-pressure cylinder of a steam engine or other auxiliary steam sources, the energy consumption of the system is increased due to the input of the auxiliary heat source, and the treatment cost of the wet smoke plume is increased. Therefore, a technical method is needed to ensure that the unit can provide enough heat for the flue gas, ensure the temperature of the flue gas and have smaller energy loss.
Another more serious problem exists in that the updating of the flue gas heating technology is not only needed in newly built power plants, but also needs to be updated to eliminate visible wet smoke plume caused by the saturation of the humidity of the discharged flue gas for more power plants which are already built for use. Therefore, the technical personnel in the field need to develop a device for reheating flue gas by using condensed water, and the device needs to be based on the existing equipment and pipelines of the existing power plant, has low modification cost and increases the energy utilization rate as much as possible.
SUMMERY OF THE UTILITY MODEL
In view of the above defects in the prior art, the technical problem to be solved by the present invention is to increase the temperature of the flue gas to the value that should be reached under the corresponding environmental parameters only by the heat in the flue gas waste heat utilization device in the wet smoke plume treatment process; the technical problem that the technical updating of the power plant cannot be independently carried out and the existing equipment and pipeline of the power plant must be modified is also solved.
In order to achieve the above object, the present invention provides a device for reheating flue gas by using condensed water, comprising a flue gas pipeline, a waste heat utilization device, a boiler tail device, and a flue gas reheating device, wherein both the waste heat utilization device and the flue gas reheating device are arranged to exchange heat with the flue gas pipeline; the waste heat utilization device and the flue gas reheating device are arranged at two ends of the boiler tail device; flue gas passes through the flue gas duct. The waste heat utilization device, the boiler tail equipment and the flue gas reheating device sequentially flow through.
Further, heat exchange can be carried out between the waste heat utilization device and the flue gas reheating device.
Further, the waste heat utilization device comprises a low-pressure heater, a condensed water main pipeline, a condensed water first branch pipeline, a booster pump and a flow regulating valve; the low-pressure heater is used for providing heat for condensed water, and the condensed water exchanges heat with the flue gas pipeline through the first branch pipeline of the condensed water to heat the flue gas; the first branch pipeline of the condensed water is connected with the main pipeline of the condensed water, so that the condensed water can be circularly heated.
Further, the booster pump is arranged in the first branch pipeline and used for pumping the condensate water to the flue gas pipeline.
Further, the flow regulating valve is used for controlling the flow of the condensed water so as to control the temperature of the flue gas.
Furthermore, the first branch pipeline of the condensed water and the main pipeline of the condensed water are made of the same material.
Further, the relation between the pipe diameter and the pipe wall thickness of the first branch pipe of the condensed water and the main pipe of the condensed water meets the requirements of the design specification of the steam-water pipe of the DL/T50542016 thermal power plant according to the condensed water pressure.
Further, the number of the low-pressure heaters is 2, and the low-pressure heaters are respectively a first low-pressure heater and a second low-pressure heater.
Furthermore, the waste heat utilization device further comprises a condensed water second branch pipeline, the condensed water first branch pipeline is connected with the first low-pressure heater, and the condensed water second branch pipeline is connected with the second low-pressure heater.
Furthermore, the condensed water second branch pipeline and the condensed water main pipeline are made of the same material.
Compared with the prior art, the utility model discloses at least, following advantage has:
1. the utility model utilizes the condensed water led out from the outlet of the first low-pressure heater as a supplementary heat source to heat the flue gas, and the condensed water flows back to the inlet of the first low-pressure heater after heat exchange, thereby saving more energy than the method utilizing steam supplementary heating or hot secondary air and flue gas mixed heating;
2. the utility model utilizes the condensed water led out from the outlet of the low-pressure heater as a supplementary heat source to exchange heat with the flue gas, the condensed water at the outlet of the low-pressure heater is a lower grade heat source compared with the exhausted steam or the auxiliary steam of a high-pressure cylinder of the unit, and the flue gas is heated by utilizing the low grade heat source, thereby having better energy-saving effect;
3. the utility model discloses the condensate water that draws certain flow from the low pressure feed water heater export flows back to A3 low pressure feed water heater import behind flue gas heat exchanger, has improved the condensate water flow through low pressure feed water heater, makes low pressure feed water heater extraction flow increase, and the extraction flow work capacity of increase loses to some extent, but its steam extraction loss reduces, and the influence of unit whole circulation efficiency is very little.
The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings, so as to fully understand the objects, the features and the effects of the present invention.
Drawings
FIG. 1 is a schematic diagram of a flue gas side system before a conventional power plant is transformed in a preferred embodiment of the present invention;
FIG. 2 is a schematic diagram of a flue gas side system using a single low pressure heater according to a preferred embodiment of the present invention;
fig. 3 is a schematic diagram of a flue gas side system using a two-way low pressure heater according to another preferred embodiment of the present invention.
Detailed Description
The technical contents of the preferred embodiments of the present invention will be more clearly understood and appreciated by referring to the drawings attached to the specification. The present invention may be embodied in many different forms of embodiments, and the scope of the invention is not limited to the embodiments described herein.
A schematic diagram of a flue gas side system of a conventional power plant in the prior art is shown in fig. 1. Comprising a flue gas duct 1, the arrows in the flue gas duct 1 indicating the flow direction of the flue gas. The flue gas firstly flows through the waste heat utilization device 2, exchanges heat with the waste heat utilization device 2, and then passes through the boiler tail device 3. The boiler tail equipment 3 can be a combination of different equipment such as an electric dust remover, an induced draft fan, a booster fan, an absorption tower, a flue gas condenser and the like. After passing through the boiler tail device 3, the flue gas passes through the flue gas reheating device 4. The flue gas reheating device 4 and the waste heat utilization device 2 can exchange heat. The flue gas reheating device 4 further heats the flue gas, so that the flue gas meets the emission standard when being discharged. However, in the prior art, the heat provided by the waste heat utilization device 2 is not enough to provide enough heat to make the flue gas reach the required temperature. If measures such as high-pressure cylinder exhaust or other auxiliary steam and hot secondary air supplementary heating are adopted, the energy-saving effect is poor. Therefore, the utility model provides a following technical scheme.
Example 1:
as shown in fig. 2, the present embodiment connects the low-pressure heater duct, which is not originally associated, to the flue gas reheating device 4 through a branch duct. The low pressure heater may be multiple and is labeled a1, a2, A3, a4 in fig. 2. In the embodiment, a branch pipeline is additionally arranged on the condensed water outlet pipeline of the low-pressure heater A3, a medium flows to the condensed water inlet pipeline of the flue gas reheating device 4 through the booster pump, and is mixed with the condensed water absorbing heat from the waste heat utilization device 2 and then enters the flue gas reheating device 4, so that the temperature of the condensed water entering the flue gas reheating device 4 is increased, the flue gas can be heated to a required temperature, and the condensed water finally flows back to the inlet of the low-pressure heater A3. A flow regulating valve can be added into the branch pipeline so as to regulate the flow of the condensed water and play a role in controlling the temperature of the flue gas.
Example 2:
as shown in fig. 3, if the outlet condensed water of the aforementioned low-pressure heater a3 still cannot make the flue gas reach the required temperature, the flow rate of the condensed water needs to be further increased. A branch line may be added to the condensate outlet line of low pressure heater a4 and led to the front of the booster pump. Under the required condition, the condensed water at the outlet of the low-pressure heater A4 with a certain flow can be led out by switching and enters the flue gas reheating device 4, so that the temperature of the condensed water is further increased, and the aim of increasing the temperature of the flue gas is fulfilled.
In order to accurately control the temperature of the flue gas, a control method for reheating the flue gas by using condensed water is also needed:
firstly, calculating the heat absorption capacity required by the flue gas according to the difference between the current temperature of the flue gas and the target temperature required to be reached by the flue gas and the flow rate of the flue gas; and determining the flow rate of the low-pressure heater A3 led to the flue gas reheating device 4 from the outlet of the low-pressure heater A3 according to the difference between the original temperature of the condensed water in the waste heat utilization device 2 and the temperature of the condensed water at the outlet of the low-pressure heater A3. And then selecting the pipe diameter of the branch pipeline of the condensed water outlet of the low-pressure heater A3 according to the flow, wherein the pipe wall thickness can be selected according to the condensed water pressure, and the specific selection can be according to the design specification of the steam-water pipeline of the DL/T50542016 thermal power plant. The branch pipeline is made of the same material as the main pipeline. Selecting a flow regulating valve matched with the pipeline, selecting a proper booster pump according to the flow, connecting according to the connection mode in the figure 2 or the figure 3, and adopting a welding process at the connection part. The method for selecting the pipe diameter of the branch pipe of the condensed water outlet of the low-pressure heater A4 is the same as the method for selecting the pipe diameter of the branch pipe of the condensed water outlet of the low-pressure heater A3.
It should be further explained that the present invention is also applicable to other systems using heating method or condensation heating method to eliminate wet flue gas. The technical method provided by the utility model can be applied to all cases where the temperature of the flue gas at the desulfurization outlet needs to be raised in the wet flue gas treatment link.
The foregoing has described in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the teachings of this invention without undue experimentation. Therefore, the technical solutions that can be obtained by a person skilled in the art through logic analysis, reasoning or limited experiments based on the prior art according to the concepts of the present invention should be within the scope of protection defined by the claims.
Claims (9)
1. A device for reheating and heating flue gas by using condensed water comprises a flue gas pipeline, a waste heat utilization device, boiler tail equipment and a flue gas reheating device, and is characterized in that the waste heat utilization device and the flue gas reheating device are arranged to exchange heat with the flue gas pipeline; the waste heat utilization device and the flue gas reheating device are arranged at two ends of the boiler tail device; the flue gas passes through the flue gas pipeline, flows through in proper order waste heat utilization equipment, boiler tail equipment, flue gas reheating device.
2. The apparatus for reheating flue gas using condensed water according to claim 1, wherein heat exchange is performed between the waste heat utilization apparatus and the flue gas reheating apparatus.
3. The apparatus for reheating flue gas using condensed water according to claim 2, wherein the waste heat utilization apparatus comprises a low-pressure heater, a main condensed water pipe, a first branch condensed water pipe, a booster pump, and a flow control valve; the low-pressure heater is used for providing heat for condensed water, and the condensed water exchanges heat with the flue gas pipeline through the first branch pipeline of the condensed water to heat the flue gas; the first branch pipeline of the condensed water is connected with the main pipeline of the condensed water, so that the condensed water can be circularly heated.
4. The apparatus for regenerative heating of flue gas using condensed water as claimed in claim 3, wherein said booster pump is disposed in said first branch conduit for pumping said condensed water to said flue gas conduit.
5. The apparatus for regenerative heating of flue gas with condensed water as claimed in claim 3, wherein said flow control valve is adapted to control the flow of said condensed water to control the temperature of said flue gas.
6. The apparatus according to claim 3, wherein said first branch conduit of condensed water and said main conduit of condensed water are made of the same material.
7. The apparatus for regenerative heating of flue gas with condensed water according to claim 3, wherein the number of said low pressure heaters is 2, and the low pressure heaters are a first low pressure heater and a second low pressure heater.
8. The apparatus for regenerative heating of flue gas with condensed water according to claim 7, wherein said waste heat utilization apparatus further comprises a second branch conduit of condensed water, said first branch conduit of condensed water being connected to said first low pressure heater, said second branch conduit of condensed water being connected to said second low pressure heater.
9. The apparatus for regenerative heating of flue gas with condensed water as claimed in claim 8, wherein said second branch conduit of condensed water is made of the same material as said main conduit of condensed water.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921205101.7U CN210568527U (en) | 2019-07-29 | 2019-07-29 | Device for backheating and heating flue gas by using condensed water |
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| CN201921205101.7U CN210568527U (en) | 2019-07-29 | 2019-07-29 | Device for backheating and heating flue gas by using condensed water |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110425561A (en) * | 2019-07-29 | 2019-11-08 | 上海外高桥第三发电有限责任公司 | A kind of device and method using condensed water backheat heating flue gas |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110425561A (en) * | 2019-07-29 | 2019-11-08 | 上海外高桥第三发电有限责任公司 | A kind of device and method using condensed water backheat heating flue gas |
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