JPH08254397A - Heat exchanger for condenser - Google Patents

Abstract

PURPOSE: To recover a condensate while holding it so as not to prevent it from being blown to a downstream side by a gas flow, suppress an increase in a gas flow resistance, and realize an excellent latent heat recovering characteristics. CONSTITUTION: A heat exchanger for condensers comprises a cooling pipe 15 which is disposed in crosswise relationship with a gas flow containing therein a condensate component, in which a refrigerant flows and which permits a condensate component to condense on an outside thereof, and fins 20 provided on an outer periphery of the cooling pipe at least on a side, against which the gas flow strikes. The fins 20 comprises a windbreak portion for preventing the condensate component condensed from scattering due to the gas flow, and a guide portion for permitting the condensate component condensed to flow along the cooling pipe 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for a condenser used as a condenser for recovering condensable components (steam etc.) from combustion exhaust gas from thermal power plants and boilers for general industries.

[0002]

2. Description of the Related Art In a steam turbine power plant or the like, a sensible heat recovery device such as a economizer or an air preheater is installed to recover the sensible heat of a boiler exhaust gas in order to improve thermal efficiency. When the fuel is a high water content fuel such as liquefied natural gas (LNG),
Since the exhaust gas contains a large amount of water vapor, it has been proposed to recover the latent heat of the water vapor to further improve the efficiency. Since LNG is a clean energy source whose main component is hydrocarbons that do not contain corrosive components such as sulfur, corrosive substances such as sulfuric acid are not generated even if latent heat recovery is performed.
There is no risk of low temperature corrosion. For this reason, a condenser is actively used in a thermal power generation boiler or the like that uses LNG as a fuel.

As the cooling pipe 15 of the conventional heat exchanger for condenser, there is a vertical array pipe having a smooth outer peripheral surface as shown in FIGS. 6 and 7. In addition, as shown in FIGS. 8 and 9, the cooling pipe 15
There are a number of annular fins 17 attached to the outer periphery of the. In these heat exchangers, cold water 16 is caused to flow in the cooling pipe 15, and the heat of the gas is recovered by cooling the gas 2 containing the condensed component flowing on the outside of the pipe and condensing the contained steam to recover the heat of the gas. The temperature of the cold water 16 is raised. Further, the liquid condensed on the outer circumference of the pipe descends along the cooling pipe 15 or the fins 17 due to gravity, and is collected by a recovery device (not shown) provided below the cooling pipe 15.
The collected water is used as boiler water supply.

[0004]

However, in the former smooth tube, the condensate is blown to the downstream side by the gas flow in the heat exchanger during the downward movement along the outer surface. In the latter fin-equipped cooling pipe, the droplets are blown to the downstream side by the gas flow in the process of falling from the fins. as a result,
The gas flowing in the heat exchanger contains droplets, which increases the flow resistance. Further, the latent heat recovery characteristic of the condenser is deteriorated by the re-evaporation of these scattered droplets.

The present invention has been made in order to solve the above problems, and it is possible to recover the liquid condensed on the outer peripheral surface of the cooling pipe while holding it so as not to be blown to the downstream side by the gas flow. An object of the present invention is to provide a heat exchanger for a condenser which can suppress an increase in resistance and can realize excellent latent heat recovery characteristics.

[0006]

A heat exchanger for a condenser according to the present invention is arranged so as to intersect a gas flow containing a condensed component, a refrigerant flows through the inside, and the condensed component is discharged outside. A cooling pipe for condensing and a fin provided at least on the outer circumference of the cooling pipe on the side where the gas flow collides are provided, and this fin is for preventing the condensed component condensed from being scattered by the gas flow. It is characterized by having a windbreak part and a guide part for allowing the condensed component thus condensed to flow along the cooling pipe.

The windbreak portion is preferably formed by setting a part of the fin vertically above the flow direction of the gas flow by a predetermined angle. Also,
It is preferable that the fins are provided so as to be inclined vertically downward along the flow direction of the gas flow. Further, it is preferable that a plurality of cuts be provided at the tip portion of the fin.

[0008]

In the heat exchanger for a condenser according to the present invention, the windproof portion of the fins prevents the gas flow from colliding with the cooling pipe, so that the condensate does not scatter and descends along the outer peripheral surface of the cooling pipe. To do. Further, since the condensate collected in the fins is guided downward and discharged by the guide portion of the fins, the condensate is reliably collected without scattering. Further, since the condensate is strongly held in the cut portion of the fin due to the capillary phenomenon, the condensate does not easily scatter even when the gas flow velocity is high.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings. In this embodiment, the case of a heat exchanger for a condenser provided in a steam turbine power plant will be described.

As shown in FIG. 1, the steam turbine power plant has a steam system and an exhaust gas system. In the steam system, LNG is combusted in the boiler 1, the generated steam is sent to the steam turbine 8 to rotate the generator 11, and then condensed in the condenser 9. The condensed water is pressurized by the pump 10,
After being preheated by the economizer 3, it returns to the boiler 1. The alternate long and short dash line in the figure indicates the vapor cycle. Also, the solid line in the figure,
The broken line and the dotted line represent the exhaust gas 2 and the working heat medium 12, respectively.
The flow of (hereinafter abbreviated as heat medium) and the combustion air 14 is shown.

On the other hand, in the exhaust gas system, the exhaust gas 2 emitted from the boiler 1 passes through the economizer 3, the air preheater 4, the heat exchanger 5 for recovering the condensate and the latent heat, and the ventilator 6 for the chimney 7 Released into the atmosphere. Each temperature entered in the figure is the temperature of the exhaust gas 2 and the heat medium 12 at the inlet and outlet of the heat exchanger 5.

The heat exchanger 5 is a condensing heat exchanger in which the exhaust gas 2 and the heat medium 12 exchange heat in a counter-current manner. The temperature of the inflowing exhaust gas 2 is 110 ° C., and the water vapor concentration is about 17 mol.
% (Dew point temperature about 55 ° C.). On the other hand, the inlet temperature of the heat medium 12 is 35 ° C. Since the exhaust gas 2 is cooled to below the dew point temperature by the heat medium 12, the contained water vapor is condensed. At this time, not only the latent heat of steam but also the sensible heat of the exhaust gas are taken away, so that the exhaust gas temperature greatly decreases and the outlet temperature becomes 50 ° C. (that is, the temperature decrease in the condenser is 60 ° C.). On the other hand, the heat medium 12 recovers the latent heat of steam and the sensible heat of exhaust gas and rises in temperature to 50 ° C., but supplies heat to the attached heat pump 13 to lower the temperature and returns to the heat exchanger 5 again. The water condensed in the heat exchanger 5 is used as boiler feed water.

Next, the cooling pipes 15 arranged inside the main body of the heat exchanger 5 will be described in detail with reference to FIGS. 2 and 3. A large number of cooling pipes 15 are arranged substantially vertically inside the main body of the heat exchanger 5 so that the refrigerant flows therein. Boiler exhaust gas 2 is introduced into the main body of the heat exchanger 5 at a predetermined flow rate. The exhaust gas 2 is caused to flow in a direction (horizontal direction) orthogonal to the cooling pipe 15, and heat is exchanged between the exhaust gas 2 and the refrigerant via the wall of the cooling pipe 15.

In the cooling pipe 15, circular fins 20 having a special shape are provided at a predetermined pitch interval substantially perpendicular to the pipe axis. Each fin 20 is provided with a plurality of notches 23 from the outer peripheral side toward the inner peripheral side. Further, the outer peripheral portion 21 having the notch 23 is bent vertically upward with respect to the horizontal plane at a certain angle. The outer peripheral portion 21 has a role as a windbreak portion that weakens the momentum of the exhaust gas 2 that collides with the outer peripheral surface of the pipe.

It should be noted that not only the outer peripheral portion 21 but the entire annular fin 20 may be bent upward with respect to the horizontal plane. Further, four drain holes 22 are provided in the vicinity of the attachment portion of the fin 20 to the cooling pipe 15 so that the condensate drops along the cooling pipe 15. These drain holes 22 have a role as guide portions for discharging the condensate, and at least one drain hole may be provided.

The fin 20 shown in FIGS. 2 and 3 has a structure in which a large number of annular plates are independently attached to the pipe 15, but a ribbon-shaped plate is continuously spirally formed in the circumferential direction of the cooling pipe 15. May be wrapped around to form a fin.

A steel pipe for a boiler is used for the cooling pipe 15, and a steel strip having a thickness of about 1 to 2 mm is used for the fin 20.
The fins 20 are fixed to the outer peripheral surface of the cooling pipe 15 by welding.

When the exhaust gas 2 is flowed so as to be orthogonal to such a row of the cooling pipes 15, condensed components in the exhaust gas are condensed on the surfaces of the cooling pipes 15 and the fins 20 to generate a condensed liquid. The condensate tends to descend or fall from the cooling pipe 15 or the fin 20 due to gravity, but tends to be blown off when the gas flow velocity is high. However, the fin outer peripheral portion 21
As a result, the collision force of the gas 2 is relaxed, the condensate is received by the upwardly inclined annular fin 20, and the liquid is held so as not to be scattered by the capillary force generated in the narrow space of the notch 23. , The condensate does not scatter downstream. Then, the condensate is provided with a drain hole 2 provided at a position where it is difficult for the condensate to be blown off by the gas flow of the fin 20.
2 is discharged from the cooling pipe 15, flows along the outer peripheral surface of the cooling pipe 15,
It is collected by the lower collection device.

According to the above-described embodiment, the efficiency of recovering the condensed component in the exhaust gas is greatly improved by mounting the fin having a simple structure suitable for mass production. Further, since the condensate is not scattered, the flow resistance of gas in the heat exchanger body does not increase, and the latent heat recovery characteristic is further improved.

Next, another embodiment will be described with reference to FIGS. 4 and 5. In this embodiment, a large number of inclined fins 30 are attached to the outer circumference of the cooling pipe 15 at a predetermined pitch. As shown in FIG. 4, the inclined fins 30 are provided so as to be inclined vertically downward along the flow direction of the exhaust gas 2.
A windbreak portion 31 is formed on the gas collision side (upstream side) of the inclined fin 30 in the same manner as shown in FIG. 2, so that the collision force of the exhaust gas 2 on the outer peripheral surface of the cooling pipe 15 is mitigated. There is. A discharge passage 32 is formed on the gas wraparound side (downstream side) of the inclined fin 30, and the condensate is collected along the fin 30 and discharged downward through the drain groove 32.

According to the above-mentioned embodiment, since the condensate is guided to the gas sneak-in side and discharged from there through the drain groove 36, the condensate is further less affected by the gas flow, and the gas flow velocity is increased. Even if it is large, the condensate can be reliably recovered without scattering.

[0022]

According to the present invention, since the windbreak portion of the fin blocks the gas flow that is about to collide with the cooling pipe,
The condensed liquid descends along the outer peripheral surface of the cooling pipe without scattering. Also, since the condensate collected on the fins is guided downward through the drain holes of the fins, etc.,
The condensate is reliably recovered without scattering. Therefore, the efficiency of collecting the condensate is significantly improved. Further, since the condensate does not scatter, the flow resistance of gas does not increase, and a heat exchanger having better latent heat recovery characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a system flow diagram showing an outline of a steam turbine power plant.

FIG. 2 is a side view showing a cooling pipe provided in the condenser heat exchanger according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a cooling pipe provided in the heat exchanger for a condenser according to the embodiment of the present invention.

FIG. 4 is a side view showing a cooling pipe provided in a heat exchanger for a condenser according to another embodiment.

FIG. 5 is a cross-sectional view showing a cooling pipe provided in a heat exchanger for a condenser according to another embodiment.

FIG. 6 is a view showing a conventional heat exchanger.

FIG. 7 is a diagram showing a conventional heat exchanger.

FIG. 8 is a diagram showing a conventional heat exchanger.

FIG. 9 is a diagram showing a conventional heat exchanger.

[Explanation of symbols]

 2 ... Exhaust gas 5 ... Heat exchanger main body 15 ... Cooling pipes 20, 30 ... Fins 21, 31 ... Windproof part 22 ... Drain hole (guide part) 23 ... Notch 32 ... Drain groove (guide part)

Claims (4)

[Claims] 1. A cooling pipe, which is arranged so as to intersect with a gas flow containing a condensed component, has a coolant flowing through the inside thereof, and condenses the condensed component outside, and a cooling pipe at least on the side where the gas flow collides. Fins provided on the outer circumference of the cooling pipe,
And a fin for preventing the condensed condensed component from being scattered by the gas flow, and a guide for causing the condensed condensed component to flow along the cooling pipe. A heat exchanger for a condenser, comprising: 2. The heat for a condenser according to claim 1, wherein the windbreak part is formed by setting a part of the fin vertically upward with respect to a flow direction of the gas flow. Exchanger. 3. The heat exchanger for a condenser according to claim 1, wherein the fins are provided so as to be inclined vertically downward along a flow direction of the gas flow. 4. The heat exchanger for a condenser according to claim 1, wherein a plurality of cuts are provided at a tip portion of the fin.