JP2011094962A - Heat recovery equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat recovery equipment which can improve power generation efficiency in a power generation equipment by effectively utilizing heat of a power plant. <P>SOLUTION: The heat recovery equipment includes the power plant 10 for driving a steam turbine 13 by superheated steam 12 from a boiler 11 and an exhaust gas treatment line 20 for treating exhaust gas G from the boiler 11 for performing heat recovery from the exhaust gas G. The heat recovery equipment includes a heat recovery device 31 provided between an air preheater 21 provided for the exhaust gas treatment line 20 and a dry type electric dust collector 22, and a condensate heater 32 interposed between a condenser 15 which is a condenser of a condensate line of the power plant 10 and a low-pressure water supply heater 16 for heating the condensate by heat recovered by the heat recovery device 31. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat recovery facility that effectively uses waste heat of exhaust gas from a boiler.

As a technique for effectively utilizing waste heat in exhaust gas from a coal fired boiler, proposals have been made to recover the heat of the boiler exhaust gas and to heat the exhaust gas discharged to the outside.
An example of this is shown in FIG. As shown in FIG. 19, in the conventional exhaust gas treatment facility, the untreated exhaust gas A1 emitted from the coal fired boiler 1 is first guided to the heat recovery device of the air heater (AH) 2 and supplied to the boiler 1 with the heat of the exhaust gas A1. The air B to be heated is heated. Here, the untreated exhaust gas A1 is cooled to 120 ° C to 160 ° C.

  Next, the exhaust gas A1 is introduced into the heat recovery unit 3a of the non-leak type gas gas heater (GGH), recovered by heat, cooled to about 80 ° C. to 110 ° C., and then guided to the dry electrostatic precipitator (EP) 4. In the electric dust collector 4, a considerable amount of dust is removed from the exhaust gas A1, the dust concentration is reduced, and the exhaust gas A2 is discharged.

  The exhaust gas A2 exiting the electrostatic precipitator 4 is introduced into a mixed-type desulfurization device 5, and mainly absorbs and removes sulfurous acid gas. Here, too, dust is collected and removed, and then discharged as a treated exhaust gas A3. .

  The exhaust gas A3 exiting the desulfurization apparatus 5 is about 50 ° C., and is heated by the heat medium 6 recovered from the exhaust gas A1 in the reheating unit 3b of the gas gas heater (GGH), so that the temperature preferable for atmospheric release (about 90 ° C. to 100 ° C.) and discharged from the chimney 7 (Patent Document 1).

Japanese Patent Laid-Open No. 11-179147

  However, in the conventional proposal, effective heat utilization of the entire facility has not been achieved, and further improvement of the thermal efficiency of the facility is desired, for example, to improve the power generation efficiency of the power generation facility.

Moreover, when waste heat is used for this power generation facility, the reliability of the heat recovery device is required, but there is a problem that a heat recovery device capable of stable heat recovery at low cost has not yet appeared. . In particular, as shown in FIG. 19, the reheating unit 3b installed on the downstream side of the desulfurization apparatus 5 is in its severe corrosive environment such as SO ₃ fume remaining in the exhaust gas, so that all possible countermeasures against corrosion are taken. It will be necessary.

  Moreover, since the removal of the ash adhering to the tube surface of the heat recovery device is conventionally performed by always spraying steel balls (about 8 to 10 mm), there is a problem in durability.

  In view of the above problems, an object of the present invention is to provide a heat recovery facility that can effectively improve the power generation efficiency of a power generation facility by effectively using the heat of the power plant.

  1st invention of this invention for solving the subject mentioned above is equipped with the power plant which drives a steam turbine with the superheated steam from a boiler, and the exhaust gas treatment line which processes the exhaust gas from the said boiler, The above-mentioned In a heat recovery facility for recovering heat from exhaust gas, a heat recovery device provided between an air preheater provided in the exhaust gas treatment line and a dry electrostatic precipitator, a condenser in a condensate line of a power plant, and low-pressure water supply The heat recovery facility includes a condensate heater that is interposed between the heater and heats the condensate with heat recovered by the heat recovery unit.

  According to a second aspect of the present invention, in the first aspect of the present invention, the heat medium is provided with a heat medium line for supplying the heat recovered by the heat recovery unit to the condensate heater by a heat medium, and returns to the heat recovery unit. The heat recovery equipment is provided with a heat medium heater for heating the heater.

  A third invention is the heat recovery facility according to the second invention, wherein the heat medium line includes a bypass pipe.

  A fourth invention is a heat recovery facility comprising a power plant that drives a steam turbine with superheated steam from a boiler, and an exhaust gas treatment line that processes exhaust gas from the boiler, and recovering heat from the exhaust gas. A heat recovery unit provided between an air preheater provided in the exhaust gas treatment line and a dry electrostatic precipitator, and an air introduction side of the air preheater, and air is removed by heat recovered by the heat recovery unit. A heat recovery facility comprising a preheater for air to be heated.

  A fifth invention is a heat recovery facility comprising a power plant that drives a steam turbine with superheated steam from a boiler, and an exhaust gas treatment line that processes exhaust gas from the boiler, and recovering heat from the exhaust gas. A heat recovery unit provided between an air preheater provided in the exhaust gas treatment line and a dry electrostatic precipitator, and a condenser and a low-pressure feed water heater in a condensing line of a power plant. A condensate heater that heats the condensate with heat recovered by the recovery unit, and an air preheater that is provided on the air introduction side of the air preheater and heats the air with the heat recovered by the heat recovery unit It is in the heat recovery equipment characterized by comprising.

  A sixth aspect of the invention relates to a heat recovery facility according to the fifth aspect of the invention, further comprising an adjustment device that adjusts a heat supply amount of a heat medium supplied to the condensate heater or the air preheater. is there.

  According to a seventh aspect of the present invention, there is provided the heat recovery facility according to the fifth or sixth aspect, further comprising a heat medium heater for heating the heat medium supplied to the condensate heater or the air preheater. is there.

  An eighth invention is the heat recovery facility according to any one of the first to seventh inventions, further comprising a heating device for heating the bottom plate of the heat recovery device.

  A ninth invention is a heat recovery facility comprising a power plant that drives a steam turbine by superheated steam from a boiler, and an exhaust gas treatment line that processes exhaust gas from the boiler, and recovering heat from the exhaust gas. And a heat recovery device provided between the air preheater provided in the exhaust gas treatment line and the dry electrostatic precipitator, and the heat medium supplied to the heat recovery device is configured to convert the condensate itself from the steam turbine. It exists in the heat recovery equipment characterized by using.

  A tenth aspect of the invention relates to a heat recovery facility that includes a power plant that drives a steam turbine with superheated steam from a boiler, and an exhaust gas treatment line that processes exhaust gas from the boiler, and that recovers heat from the exhaust gas. The first rotary air preheater provided in the exhaust gas treatment line for preheating air and the second rotary air provided on the downstream side of the first rotary air preheater for preheating air A heat recovery facility comprising: a preheater; and a dry electric dust collector provided on the downstream side of the second rotary air preheater and removing dust in the exhaust gas.

  An eleventh invention includes a power plant that drives a steam turbine with superheated steam from a boiler, an exhaust gas treatment line that treats exhaust gas from the boiler, an air preheater provided in the exhaust gas treatment line, and a dry electric dust collector A heat recovery facility comprising a heat remover provided therebetween.

  A twelfth invention is the heat recovery facility according to the eleventh invention, wherein the refrigerant for lowering the exhaust gas temperature is seawater.

  A thirteenth invention is the heat recovery facility according to any one of the first to twelfth inventions, further comprising a desulfurization device for desulfurizing exhaust gas on the downstream side of the dry electrostatic precipitator. .

  According to a fourteenth aspect of the invention, in any one of the first to thirteenth aspects, the soot blower for removing ash adhering to the heat exchange tube of the heat recovery unit, and a drain removing device for removing vapor drain of the soot blower. It exists in the heat recovery equipment characterized by providing.

  According to a fifteenth aspect, in the fourteenth aspect, the soot blower includes a first cylinder that introduces steam from the boiler, a second cylinder that can be inserted into and removed from the first cylinder, and the first cylinder. The heat recovery facility is provided with a steam hole that is provided at a leading end of the second cylindrical body on the extraction side and ejects steam from the first cylindrical body.

  A sixteenth invention is the heat recovery facility according to the fourteenth or fifteenth invention, wherein the gas flow passing through the heat recovery device is a horizontal flow heat recovery device.

  A seventeenth aspect of the present invention is the heat recovery facility according to any one of the fourteenth to sixteenth aspects, wherein the heat exchange tube of the heat recovery unit is a carbon steel fin tube.

  ADVANTAGE OF THE INVENTION According to this invention, the waste heat of waste gas can be utilized for the heating of the condensate of boiler power generation equipment, and the effective heat utilization of the whole equipment can be aimed at. As a result, the power generation efficiency in the facility can be improved.

  Further, when removing the ash in the heat recovery unit, the steam drain can be removed to perform the soot blower, and the reliability of the heat recovery unit can be improved.

FIG. 1 is a schematic diagram of a heat recovery facility according to the first embodiment. FIG. 2 is a schematic diagram of another heat recovery facility according to the first embodiment. FIG. 3 is a schematic diagram of another heat recovery facility according to the first embodiment. FIG. 4 is a schematic diagram of another heat recovery facility according to the first embodiment. FIG. 5 is a schematic diagram of another heat recovery facility according to the second embodiment. FIG. 6 is a schematic diagram of another heat recovery facility according to the third embodiment. FIG. 7 is a schematic diagram of a heat recovery facility according to the fourth embodiment. FIG. 8 is a schematic diagram of a heat recovery facility according to the fifth embodiment. FIG. 9 is a schematic diagram of another heat recovery facility according to the sixth embodiment. FIG. 10 is a conceptual perspective view of a heat recovery device according to the seventh embodiment. FIG. 11 is a conceptual perspective view of a heat recovery device according to the seventh embodiment. FIG. 12 is a front view of the heat recovery device according to the seventh embodiment. FIG. 13 is a front view of the heat recovery device according to the seventh embodiment. FIG. 14 is a schematic diagram of a soot blower according to the eighth embodiment. FIG. 15 is a vertical view of the drain removing apparatus according to the eighth embodiment. FIG. 16 is a lateral view of the drain removing apparatus according to the eighth embodiment. FIG. 17 is an initial operation schematic diagram of the soot blower according to the eighth embodiment. FIG. 18 is an operation schematic diagram of the soot blower according to the eighth embodiment. FIG. 19 is a schematic view of a heat recovery facility according to the prior art.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

A heat recovery facility according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram illustrating a heat recovery facility according to the first embodiment.
As shown in FIG. 1, a heat recovery facility according to the present embodiment includes a power plant 10 that drives a steam turbine 13 with superheated steam 12 from a boiler 11, and an exhaust gas treatment line 20 that processes exhaust gas G from the boiler 11. In a heat recovery facility for recovering heat from the exhaust gas G, a heat recovery device 31 provided between an air preheater 21 provided in the exhaust gas treatment line 20 and a dry electrostatic precipitator 22; A condensate heater 32 is interposed between a condenser 15 and a low-pressure feed water heater 16 which are condensers of the condensate line of the power plant 10 and heats the condensate with heat recovered by the heat recovery unit 31. It comprises. In FIG. 1, reference numeral 23 denotes a desulfurization device for removing sulfur oxides in the exhaust gas, and 24 denotes a chimney.

  Here, an example of the system of the power plant 10 will be described. As shown in FIG. 1, the power plant 10 includes a condenser 15 that cools and condenses exhaust gas from a steam turbine 13 that drives a generator 14, and condensate from the condenser 15 as low-pressure extraction steam from the turbine 13. A boiler having a low-pressure feed water heater 16 for heating and a high-pressure feed water heater 18 for heating the feed water supplied through the boiler feed pump 17 with high-pressure extraction steam from the turbine 13 after degassing heated oxygen in water. 11.

  In this embodiment, a condensate heater 32 for heating the condensate is interposed between the condenser 15 and the low-pressure feed water heater 16. Particularly preferably, the low pressure feed water heater 16 is arranged on the upstream side of the first feed water heater. Moreover, you may make it abolish the conventional 1st feed water heater depending on an installation.

  As a result, the heat medium recovered by the heat recovery device 31 in the gas temperature range of 120 to 200 ° C. is sent to the condensate heater 32 through the heat medium line 33, where the heat medium has a temperature range of about 25 to 50 ° C. The condensate is heated.

As a result, the gas temperature upstream of the dry electrostatic precipitator 22 is lowered to the acid dew point, the SO ₃ in the gas is condensed and adsorbed to the soot, and the SO ₃ is removed together with the soot by the dry electrostatic precipitator. In addition, by reducing the gas temperature, the specific resistance of the dust is reduced, the reverse ionization phenomenon in the dry electrostatic precipitator is avoided, and the dust removal performance is improved.

By reducing the temperature of the exhaust gas below the acid dew point, SO ₃ is efficiently collected to reduce opacity (light shielding), prevent acid corrosion downstream of the heat recovery unit, and reduce purple smoke from the chimney. effective. Regarding the effect of reducing the opacity, the opacity can be maintained or reduced after applying this facility. In addition, in the case of a new establishment, it can be expected to be 20% or less.

In addition, for dust, after applying this facility, the exhaust gas temperature at the inlet of the dry dust collector is lowered to reduce the dust concentration in the exhaust gas at the outlet of the desulfurizer to at least the current level if it is a modification of the existing equipment. I can expect that. Furthermore, if it is a newly installed facility, it can be expected to reduce it to at least 30 mg / Nm ³ or less, and depending on the type of desulfurization apparatus, to 10 mg / Nm ³ or less.

By reducing the temperature of the exhaust gas, high-efficiency collection of heavy metals such as mercury as well as soot and SO ₃ can be expected in the dry electrostatic precipitator 22.

  Further, by installing the condensate heater 32, it is possible to partially reduce the bleed from the turbine to the low-pressure feed water heater 16 that has been used for condensate heating. Thereby, the amount of steam to the turbine 13 increases, leading to an increase in turbine output.

  Thus, conventionally, in the power plant 10, the condensate is heated by extraction from the turbine. However, as in the present invention, the condensate heater 32 is provided upstream of the low-pressure feed water heater 16 in the condensate line. Since the condensate is heated by the recovered heat, it is possible to partially reduce the bleed air from the turbine that has been performed so far, and to increase the output.

  The following “Table 1” is a result of roughly calculating the heat balance under the rated operation conditions in the plant having the power generation end output of 600 MW in the facility as shown in FIG. It is found that the condensate temperature is increased by about 20 ° C. by installing the condensate heater 32 in the condensate line.

  As shown in “Table 1”, for example, when the inlet temperature of the condensate introduced into the condensate heater 32 is 34 ° C., the outlet that passes through the condensate heater 32 and is heat-exchanged by the heat medium. The temperature is 57 ° C. For example, in a 600 MW class power generation facility, the output is increased by about 2000 kW.

Next, another heat recovery facility according to the first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 2, in this example, four heat recovery devices 31A to 31D are provided, and four dry electrostatic precipitators 22A to 22D are provided on the downstream side of the heat recovery devices 31A to 31D.
In this way, when the exhaust gas G is branched and processed in four systems using a plurality of heat recovery units and corresponding dry electrostatic precipitators 22, even if any line is abnormal, the other line Can be covered. Further, since maintenance work can be performed for each system, work processing is facilitated. Moreover, when there is little load of waste gas, it can respond by either 1/4-3/4, and an efficient waste gas process can be performed.

  Next, another heat recovery facility according to the first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, in the heat medium line 33 from the heat recovery device 31 to the condenser heater 32, a heat medium heater 34 for heating the heat medium introduced into the heat recovery device 31 is interposed. Also good.

By installing the heat medium heater 34, the temperature of the heat medium introduced into the heat recovery device 31 is controlled. For example, when there is little soot in the exhaust gas from the boiler and the SO ₃ concentration is high, heat exchange is performed. Since it becomes a critical condition for SO ₃ corrosion for the tube, the temperature of the heat medium is raised by a heat medium heater. As a result, a temperature drop inside the heat recovery unit 31 can be prevented, and corrosion of the heat exchange tube due to SO ₃ can be prevented.

As a result, internal corrosion due to SO ₃ adhesion in the heat exchange tube of the heat recovery unit 31 is prevented.

  Further, as shown in FIG. 3, a bypass pipe 36 is provided in the heat medium line 33, a bypass valve 35 is provided in the bypass pipe 36, and the supply amount of the heat medium to the condenser heater 32 is adjusted. It may be.

  By installing this bypass pipe 36, the amount of heat to the condensate heater 32 can be adjusted, and priority can be given to returning the heat medium to the heat recovery unit 31 side. As a result, a decrease in the temperature of the heating medium can be suppressed, and internal corrosion is prevented from occurring.

  Next, another heat recovery facility according to the first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 4, in addition to the heat recovery equipment of FIG. 3, an opacity meter 26 for measuring the opacity in the flue gas is further installed on the outlet side of the dry electrostatic precipitator 22, and the measurement result of the opacity meter 26 The amount of heating by the heat medium heater 34 is adjusted by the control device (CPU) 27 using the above.

  In FIG. 4, the opacity meter 26 is installed on the outlet side of the dry electrostatic precipitator 22, but the present invention is not limited to this, and the opacity in the flue gas is reduced on the outlet side of the desulfurization device 23. You may make it install the opacity meter 26 to measure.

As a result, the temperature of the heat medium increases, the amount of heat exchange per unit area of the heat recovery unit in the heat recovery unit 31 decreases, the gradient of cooling of the exhaust gas in the heat recovery unit becomes gentle, and the generation of SO ₃ fume is suppressed. be able to. As a known technique, a technique for improving the dust removal performance of the dust collector by injecting SO ₃ into the upstream of the dry electrostatic precipitator is known, but the adjustment is made so as to suppress the concentration to the SO ₃ fume concentration generated at that time.

Moreover, since generation of excessive SO ₃ fume having a small particle size is suppressed, space charge is not increased, and generation of spark discharge in the dry electrostatic precipitator 22 can be suppressed.

Therefore, for example, even when the amount of SO ₃ fume increases due to different coal types, the exhaust gas treatment and heat recovery can be performed stably.

A heat recovery facility according to a second embodiment of the present invention will be described with reference to the drawings.
FIG. 5 is a conceptual diagram illustrating a heat recovery facility according to the second embodiment. In addition, about the same member as the heat recovery equipment shown in Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In the facility of Example 1, as shown in FIG. 1, a condensate heater 32 was installed in order to reuse the recovered heat, but in this example, as shown in FIG. Condensate is directly used as a heat medium for the recovery unit 31 and the condensate heater 32 is omitted.

  As a result, it is not necessary to install the condensate heater 32 as compared with the first embodiment, so that the equipment becomes compact.

A heat recovery facility according to a third embodiment of the present invention will be described with reference to the drawings.
FIG. 6 is a conceptual diagram illustrating a heat recovery facility according to the third embodiment. In addition, about the same member as the heat recovery equipment shown in Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
As shown in FIG. 6, in the heat recovery facility of Example 3, a heat remover 70 is provided between the air preheater 21 and the dry electrostatic precipitator 22 provided in the exhaust gas treatment line 20.
In the heat remover 70, seawater 71 is used as a destination of the recovered heat.

  As a result, comparing the case where the heat remover 70 is installed with the case where the heat remover 70 is not installed under the gas conditions shown in Table 1, the exhaust gas temperature which was 137 ° C. when the heat remover 70 is not installed is installed. As a result, the temperature could be lowered to 92 ° C. Moreover, in the desulfurization apparatus 23, when the loss of the evaporated water amount when the exhaust gas temperature is high is taken into consideration, it is possible to save about 25 to 30 ton / h of water.

  In this embodiment, in order to lower the exhaust gas temperature, the refrigerant may be directly pumped up from seawater, lakes, and rivers and passed through the heat remover 70.

  In the present embodiment, the heat medium after heat recovery may be directly released to seawater, lakes, and rivers.

A heat recovery facility according to a fourth embodiment of the present invention will be described with reference to the drawings.
FIG. 7 is a conceptual diagram illustrating a heat recovery facility according to the fourth embodiment. In addition, about the same member as the heat recovery equipment shown in Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In the facility of the first embodiment, as shown in FIG. 1, the condensate heater 32 is installed in order to reuse the recovered heat, but in this embodiment, the air supplied to the boiler 11 is preheated. An air preheater 38 for heating the air 37 introduced through the pushing fan 61 is provided on the upstream side of the air preheater 21.

According to the fourth embodiment, the air 37 pushed in from the outside by the pushing fan 61 is provided with the air preheater 38, so that the air temperature is increased by the heat medium from the heat recovery device 31, and preheated air is generated. It is possible to reduce the influence of corrosion caused by SO ₃ condensation on the elements of the air preheater 21 that performs the above operation. As a result, the life of the element of the air preheater 21 can be extended.

A heat recovery facility according to a fifth embodiment of the present invention will be described with reference to the drawings.
FIG. 8 is a conceptual diagram illustrating a heat recovery facility according to the fifth embodiment. In addition, about the same member as the heat recovery equipment shown in FIG. 1 thru | or FIG. 7, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
This embodiment is a combination of the heat recovery equipment of the first embodiment shown in FIG. 1 and the heat recovery equipment of the fourth embodiment shown in FIG. The first adjusting valve 39-1 and the second adjusting valve 39-2 for adjusting the amount of the heat medium flowing into the condensate heater 32 or the air preheater 38 are provided.

  According to the fifth embodiment, as shown in FIG. 8, excessive heat supply for heating the condensate or the pushing air 37 is performed by installing the first regulating valve 39-1 and the second regulating valve 39-2. Can be avoided.

  That is, for example, when the boiler is in a low load operation, the first adjustment valve 39-1 and the second adjustment valve 39-2 are adjusted so as to preheat the air 37. Further, when the boiler is in a high load operation, the first regulating valve 39-1 and the second regulating valve 39-2 are adjusted so as to preheat the condensate.

  As a result, the waste heat of the exhaust gas can be effectively used according to the state of the facility, and the operation efficiency of the facility can be optimally exhibited.

A heat recovery facility according to Embodiment 6 of the present invention will be described with reference to the drawings.
FIG. 9 is a conceptual diagram illustrating a heat recovery facility according to the sixth embodiment. In addition, about the same member as the heat recovery equipment shown in FIG. 1 thru | or FIG. 8, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In this embodiment, in the heat recovery equipment of the fourth embodiment shown in FIG. 7, the heat exchange between the heat recovery device 31 and the air preheater 38 is performed by a heat medium line, and a rotary air preheater is used. Furthermore, another unit is installed as two air preheaters 21A and 21B.

Thereby, compared with the case where only one air preheater is installed, the temperature reduction of the exhaust gas G introduced into the dry electrostatic precipitator 22 can be further reduced, and the dust and SO ₃ removal performance is improved. be able to.
Moreover, the preheating temperature of the external air 37 becomes high, and plant efficiency improves.

In addition, by installing two air preheaters in series, the air supplied from the outside is preheated in two stages, and the exhaust gas G discharged to the outside falls in two stages. Thereby, compared with the case of installation of one air preheater, the heat drop gradient of the exhaust gas becomes gentle.
As a result, the generation of SO ₃ fume in the exhaust gas G can be suppressed. Therefore, the corrosion due to SO _{3 in} the downstream equipment can be reduced and the life can be extended.

  In the above-described embodiments, the condensate and the air are heated as the use destination of the heat recovered by the heat recovery facility. However, the present invention is not limited to this, and the heat of the facility is used. It can also be used for applications such as tracing, heating, and hot water production.

A heat recovery device applied to a heat recovery facility according to Embodiment 7 of the present invention will be described with reference to the drawings.
FIG. 10 is a conceptual perspective view illustrating a heat recovery apparatus according to the seventh embodiment. FIG. 11 is a front view thereof. As shown in FIGS. 10 and 11, the heat recovery unit includes a heat recovery unit body 40 having an inlet 40 a for introducing exhaust gas for heat recovery and an outlet 40 b for discharging the exhaust gas recovered by heat, and heat of the exhaust gas G. A tube bundle 41 formed by collecting a plurality of heat transfer tubes, and a steam line 42 provided on the bottom portion 40c of the heat recovery body 40 to heat the entire bottom portion 40c.
Note that the gas flow is not limited to the flow in the vertical direction as in the heat recovery device of FIGS. 10 and 11, and may be in the horizontal direction, for example. An example of this is shown in FIGS. Here, FIG. 12 is a conceptual perspective view showing the heat recovery device when the gas flow is in the horizontal direction. FIG. 13 is a front view thereof.

  As the steam supplied to the steam line 42, for example, steam having a temperature of about 70 to 180 ° C. can be used.

By installing the steam line 42, the entire bottom 40 c of the heat recovery unit main body 40 can be heated by steam, and the fall ash accompanied with the exhaust gas G is heated in the heat recovery unit main body 40. When the ash is heated, the moisture absorption of SO ₃ attached to the ash decreases. For example, when the moisture in the exhaust gas is 10%, it has been found that if the temperature rises by 20 ° C., the moisture absorption of SO ₃ decreases by about 10%. By reducing the moisture in the ash, the fluidity of the ash is improved, and the ash is accompanied again with the exhaust gas G, so that it can easily flow into a dust collector hopper (not shown) installed on the downstream side.

  As a result, for heat recovery, even if the gas flow of the heat recovery device is horizontal, ash does not accumulate at the bottom, and not only vertical flow but also horizontal flow heat recovery devices can be employed.

  Inexpensive carbon steel can be used as the material of the heat exchange tube of the heat recovery device 31 according to the present embodiment. Moreover, it is desirable that the heat exchange tube be a finned tube with increased heat recovery efficiency and dust adhesion area.

  Moreover, the heat recovery efficiency is improved by installing the heat recovery device according to the seventh embodiment in the heat recovery facilities according to the first to fifth embodiments illustrated in FIGS. 1 to 8.

The soot blower installed in the heat recovery device applied to the heat recovery equipment according to the eighth embodiment of the present invention will be described with reference to the drawings.
FIG. 14 is a conceptual diagram illustrating a soot blower for a heat recovery device according to the fifth embodiment. 15 and 16 are cross-sectional views of the pre-purge box, and FIGS. 17 and 18 are operation schematic diagrams of the soot blower. As shown in these drawings, the soot blower 50 is inserted into the heat exchanger main body 40, and the ash of the tube bundle is removed by high temperature / high pressure steam. The soot blower 50 includes an inner cylinder 51 that is a first cylinder for introducing high-pressure and high-temperature steam from the boiler, and a lance tube 52 that is a second cylinder that can be inserted into and removed from the inner cylinder 51. The lance tube 52 is provided with a steam hole 53 provided at the leading end on the extraction side. The lance tube is configured so that a driving device M can simultaneously perform a feed / return operation and a rotation operation.

In the present embodiment, the lance tube 52 as the second cylinder is configured to move outside the inner cylinder of the first cylinder. However, the present invention is not limited to this. A lance tube, which is a second cylindrical body, may be inserted into and removed from the inner side of one cylindrical body.
In the case where the lance tube 52 is an outer cylinder as in the present embodiment, a drive device for insertion and removal can be provided, which is more preferable.

  Thereby, the lance tube 52 is moved back and forth inside the heat exchanger main body 40 by the driving device M, and the ash of the tube bundle is removed by steam spraying.

  Further, a drain removing device 54 for removing the steam drain of the soot blower 50 at the initial stage of the soot blower is provided on the side surface of the heat exchanger main body 40. Since the soot blower is about several times a day, the drain removing device 54 removes steam drain generated in the steam line during the stop period. At the gas temperature (about 90-120 ° C) of the heat exchanger where the soot blower is installed, spraying the drain into the high dust will fix the dust and affect the operation of the entire plant, so draining the soot blower is indispensable. It is.

  Further, as shown in FIGS. 15 and 16, the drain removing device 54 has a gas-liquid separation cylinder 55 having a plurality of pores 55 a provided therein, and the steam ejected from the steam hole 53. The drain is separated into gas and liquid, and the steam 64 is discharged from the top hole 54a in the vertical axis direction of the drain removing device, and the drain 65 is discharged from the hole 54b at one bottom.

  By using such a drain removing device 54, at the initial stage of the soot blower, as shown in FIG. 17, the steam line regulating valve 66 is opened and the steam at the tip of the lance tube 52 inside the drain removing device 54. Drain vapor is discharged from the holes 53. Drain the steam in the lance tube for a considerable period of time, or install a thermometer in a place where the steam in the drain removal device does not directly hit, and check that drainage has disappeared due to the change in temperature. Also good.

  Next, after the generation of drain from the steam is stopped, as shown in FIG. 18, the lance tube 52 is inserted into the heat exchanger body 40 with the shutter (not shown) open, and the ash adhering to the tube bundle 41 is removed. Dismiss. Note that the lance tube 52 can be rotated 360 degrees by a rotating device (not shown), and ash is removed by steam to every corner of the heat recovery unit 40. When the ash removal is completed, the lance tube 52 is accommodated in the drain removing device 54 and the shutter (not shown) is closed.

  The steam used for the soot blower is devised so that the drain is not easily generated even in the upstream pipe. Branches and lengths of steam from the main pipe to each soot blower are as short as possible, and the main pipe constantly circulates steam.

As a result, the steam drain accumulated in the steam line and the lance tube 52 can be discharged in the early stage of the soot blower, and only the high-pressure and high-temperature steam is supplied to the soot blower to prevent solidification and adhesion of ash. Can do.
Thereby, even if cheap carbon steel is used as the material of the tube of the heat recovery device, adhesion of ash can be reduced by the soot blower, and heat recovery can be performed stably over a long period of time.
Moreover, since the soot blower operation | work about 2 to 3 or 4 times a day is sufficient, without always spraying the steel ball like the past, durability of a heat recovery device improves.

  Further, a dummy tube that does not supply a heat medium may be provided on the upstream heat recovery tube that contacts the exhaust gas G of the tube bundle 41 in the initial stage. Thereby, in the upstream tube having a high flow velocity, even if a hole is formed in the tube due to wear by ash, the heat medium is not affected, and the reliability of the heat recovery device can be improved.

DESCRIPTION OF SYMBOLS 10 Power generation plant 11 Boiler 12 Superheated steam 13 Steam turbine 14 Generator 15 Condenser 16 Low pressure feed water heater 17 Boiler feed pump 18 High pressure feed water heater 20 Exhaust gas treatment line 21 Air preheater 22 Dry type electric dust collector 23 Desulfurization device 24 Chimney 31 Heat recovery device 32 Condensate heater 33 Heating medium line 34 Heating medium heater 38 Air preheater

Claims (4)

A power plant that drives a steam turbine with superheated steam from a boiler;
An exhaust gas treatment line for treating exhaust gas from the boiler,
In heat recovery equipment for recovering heat from the exhaust gas,
A heat recovery unit provided between an air preheater provided in the exhaust gas treatment line and a dry electrostatic precipitator,
A heat recovery facility characterized in that the heat medium supplied to the heat recovery unit uses condensate itself from a steam turbine. In claim 1,
A heat recovery facility comprising a heat medium heater for heating the heat medium flowing into the heat recovery unit. In claim 1 or 2,
A heat recovery facility comprising a bypass pipe having a bypass valve in the heat medium line. In any one of Claims 1 thru | or 3,
On the outlet side of the dry electrostatic precipitator, an opacity meter is provided to measure opacity during flue gas,
A heat recovery facility, wherein a control device is used to control a heating amount of a heat medium heater using a measurement result of the opacity meter.

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