KR20180132194A - Integrated condenser capable of recovering latent heat and removing pollutants of exhaust gas and power generation system using pressurized oxygen combustion comprising the same - Google Patents

Abstract

The present invention relates to an integrated flue gas condenser and a pressurized oxyfuel combustion power generation system having the same. The present invention comprises: an exhaust gas condensing tank in which exhaust gas discharged from a boiler in which pressurized pure oxygen is combusted is introduced and internal pressure is maintained at a predetermined level or higher; and a heat exchange tube disposed at one side of the exhaust gas condensing tank and having a heating medium flowing therein. The present invention provides the integrated flue gas condenser, wherein water in the exhaust gas is condensed by heat exchange between the heating medium supplied to the heat exchange tube and the exhaust gas flowing into the exhaust gas condensing tank, latent heat contained in the exhaust gas is recovered through the heating medium, and contaminants contained in the exhaust gas are dissolved in the condensed water and discharged in a form of an aqueous solution.

Description

TECHNICAL FIELD The present invention relates to an integrated flue gas condenser capable of recovering latent heat in an exhaust gas and removing air pollutants, and a pressurized oxyfuel combustion power generation system using the same. same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device capable of collecting latent heat of steam evaporation in an exhaust gas and an integrated reduction of air pollutants in a pressurized pure oxyfuel combustion power generation system and a power generation system including the same, Which collects the latent heat of evaporation of steam by condensing the exhaust gas generated by the exhaust gas by heat exchange and dissolves or collects the acid gas and fine dust which are air pollutants into the condensed water to perform the integrated treatment of the pollutants, Condenser and a pressurized oxyfuel combustion power generation system including the same.

In a conventional thermal power generation system employing a steam turbine using heat generated by combustion of fuel and air, as shown in FIG. 3, in the boiler 1, air is used as an oxidizer to burn fuel, Pressure steam generated by the steam turbine 2, and the heat of the combustion gas is recovered through heat exchange between the water passing through the heat transfer tube of the boiler and the hot combustion gas, And the generator is interlocked with the steam turbine to generate electric power.

The exhaust gas produced by the boiler 1 to produce high-temperature and high-pressure steam and the exhaust gas discharged from the boiler 1 together with nitrogen, carbon dioxide, surplus oxygen, some incomplete combustion products (such as carbon monoxide) and air pollutants (NOx, SOx and Dust) In the case of a combustion system employing air as an oxidizer, the mole fraction of water in the flue gas usually has a value of about 10% or so.

The flue gas passes through the SCR (3) (Selective Catalytic Reactor), EP (4) (Electrostatic Precipitator) and FGD (5) (Flue gas desulfurizer) connected to the boiler. NOx among the air pollutants contained in the exhaust gas is SCR 3), dust is sequentially removed from EP 4 and SOx is sequentially removed from FGD 5.

In the SCR (3), EP (4) and FGD (5), the flue gas from which air pollutants are removed is discharged to the outside through the chimney.

As described above, the fact that the moisture in the exhaust gas is discharged into the atmosphere in the form of water vapor means that the latent heat of evaporation contained in the water vapor generated in the process of burning the fuel and the air is lost to the outside of the power generation system. The condensation temperature of the steam having a partial pressure of about 0.1 atmospheres is very low at about 50 DEG C so that it is difficult to recover the latent heat of vaporization by cooling the flue gas so as to condense the water vapor in the flue gas, Is lower than the condensation temperature and thus shows a very inefficient problem in terms of available energy

In recent years, in order to reduce the emission of greenhouse gases (carbon dioxide) generated from thermal power generation, pure oxygen is supplied as an oxidizing agent instead of air to constitute the main components of the exhaust gas by carbon dioxide and water vapor and the steam is condensed to collect the carbon dioxide Oxyfuel combustion power generation system is being researched and developed.

In this regard, Patent Document 1 discloses a power generation system through combustion of pure oxygen and fuel.

4, when oxygen is separated from the air through the ASU 20 (Air Separation Unit) and is supplied to the boiler 10 for combustion, the flow rate of the exhaust gas, as well as nitrogen It is possible to simplify the structure of the SCR 40, the EP 50 and the FGD 60 for treating the pollutants to a certain extent, And the CPU 70 (CO2 Process Unit) that pressurizes the exhaust gas and collects carbon dioxide is added to the downstream side of the system in order to collect / purify the carbon dioxide generated by the oxygen combustion. There is a problem that the overall power generation efficiency is reduced by 10% or more.

In addition, the latent heat recovery rate of the exhaust gas described above is also high because the condensation temperature of the water vapor in the flue gas is higher than that of the air combustion due to the limitation of the gas flow operated at normal pressure. However, The temperature of the heat medium recovered from the latent heat is lower than the condensation temperature of the steam in the exhaust gas, so that the energy available for recycling in the boiler system is not large.

In order to prevent the temperature of the combustion gas in the boiler 10 from becoming too high, a part of the exhaust gas must be recycled back to the boiler 10 side and mixed with the supplied oxygen to be used as an oxidizing agent. Thus, sulfuric acid The concentration of SOx or the like is concentrated, which inevitably causes a problem.

In order to solve this problem, a pressurized oxyfuel combustion system that pressurizes the oxidant and exhaust gas of the operating oil of a boiler and an exhaust gas processing apparatus passing through a gas and performs a pure oxygen combustion is receiving attention.

The pressurized pure oxyfuel combustion system can reduce the flue gas flow rate by eliminating the flue gas recirculation and increase the pressure so that the size of the boiler and other devices can be reduced to a level much smaller than the boiler and related systems operated at the conventional atmospheric conditions. And the compression heat is recovered in advance, thereby saving the compression power and minimizing the reduction of power generation efficiency in the conventional atmospheric-pressure pure oxygen combustion.

In addition, the partial pressure of water vapor in the flue gas during the operation of pressurized pure oxygen can increase the partial pressure of the exhaust gas and the mole fraction of water vapor, so that the water vapor can have a high partial pressure far exceeding the atmospheric pressure. Since the condensation temperature can be much higher than 100 ° C, the latent heat of vaporization can be recovered through simple heat exchange and further reduction of power generation efficiency can be further reduced. In the process of condensing water vapor, NOx and SOx Since it can be controlled in the form of an aqueous solution, there is an advantage that no additional acid gas treatment device is required.

As a result, the pressurized pure oxyfuel combustion power generation system can (1) reduce the volume of the power generation facility, (2) recover the latent heat of the steam and the compression energy of the working fluid to improve the thermal efficiency, and (3) Is a thermal power generation system capable of capturing CO2 with the advantage of being able to simplify the system because it can be controlled by integrating it with the recovery facility of latent heat.

Patent Document 1: KR 2011-0016679 A

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to solve the above problems, and it is an object of the present invention to recover the latent heat of vaporization of steam in a pressurized exhaust gas discharged from a boiler in a pressurized pure oxy- And an object of the present invention is to provide a combined-type flue gas condenser and a pressurized pure oxyfuel combustion-based power generation system including the flue gas condenser, which can integrally perform removal and cleaning of pollutants using the flue gas.

In order to accomplish the above object, the present invention provides a flue gas condensing tank in which flue gas discharged from a boiler in which pressurized pure oxygen is combusted is introduced and the internal pressure is maintained at a predetermined level or higher; And a heat exchange tube disposed at one side of the flue gas condensing tank and through which the heating medium flows, wherein heat exchange is performed between the heating medium supplied to the heat exchange tube and the flue gas introduced into the flue gas condensing tank, And the latent heat contained in the exhaust gas is recovered through the heating medium, and the pollutant contained in the exhaust gas is dissolved in the condensed moisture to be discharged in the form of an aqueous solution.

Further, the integrated flue gas condenser; A boiler for burning pressurized oxygen and fuel at a predetermined pressure and discharging exhaust gas generated by combustion to the integrated heat recovery apparatus; A pressurized ASU which separates pure oxygen from air and pressurizes and supplies the pure oxygen to the boiler; A steam turbine power generator for generating electricity using steam produced through heat exchange in the boiler; And a CPU for separating carbon dioxide contained in the exhaust gas discharged from the integrated flue gas condenser.

It is preferable that the latent heat of the exhaust gas recovered in the integrated exhaust gas condenser is supplied to the pressurized ASU to preheat pure oxygen supplied to the boiler.

And a scrubber disposed on the other side of the flue gas condensing tank, wherein particulate matter contained in the flue gas is removed and the dust is cleaned by the washing water supplied from the scrubber.

And a purifier for purifying the pollutant in an aqueous solution containing contaminants discharged from the integrated flue gas condenser, wherein the purified water in the purifier is supplied to the cleaner as cleansing water.

It is preferable that the latent heat of the flue gas recovered in the integrated flue gas condenser is supplied to a heat exchanger passing through the boiler to heat the heat medium flowing in the heat exchanger.

As described above, the integrated flue gas condenser and the pressurized pure oxyfuel combustion power generation system according to the present invention have various advantages as compared with the thermal power generation system using the normal atmospheric air.

First, since the pressurized pure oxygen is used as the oxidizing agent, it is possible to completely burn the low-grade fuel having a high moisture content and a low calorie content. Also, since the flow rate of the exhaust gas generated through the combustion is small, It is advantageous to apply a high efficiency boiler suitable for producing high-temperature and high-pressure steam in which an expensive heat exchange tube material is used.

Since the water vapor in the exhaust gas discharged from the boiler has a high mole fraction and a high pressure of the exhaust gas, the partial pressure of water vapor far exceeds the atmospheric pressure. Therefore, through the heat medium passing through the heat exchanger installed in the flue gas condenser, , The latent heat is condensed into water while discharging the latent heat, so that the latent heat of the water vapor can be recovered through the heating medium to increase the thermal efficiency of the total pressurized oxyfuel combustion power generation system.

NO and SO2, which are oxides of nitrogen and sulfur contained in high-pressure flue gas, are mostly converted into NO2 and SO3 which are highly water-soluble in the temperature range of the flue gas condenser as the pressure increases according to the law of thermal equilibrium. In the process of condensing water in the condenser, it can be removed from the flue gas with nitric acid and sulfuric acid aqueous solution together with water, so that it is possible to control the nitrogen oxides and sulfur oxides without a separate acid gas purifying device.

In addition, when dust is contained in the exhaust gas passing through the integral flue gas condenser, it is possible to collect natural gas in the process of condensing water, so that desulfurization, denitrification, and exhaustion can be simultaneously achieved.

Therefore, when a pressurized pure oxyfuel combustion power generation system integrated with an integrated flue gas condenser is applied, it is possible to (1) diversify the generation fuels capable of completely burning low-grade fuels, (2) recycle the latent heat of steam contained in the flue gas, (3) It is possible to simplify and compact the apparatus that can be implemented in the integrated flue gas condenser without depending on a separate environment control device, and to reduce the power generation cost and the power generation facility cost. have.

1 schematically shows a pure oxygen pressurized combustion power generation system according to an embodiment of the present invention.
2 schematically shows an integral flue gas condenser, which is a constitution of a pure oxygen pressurized combustion power generation system according to an embodiment of the present invention.
Fig. 3 schematically shows a conventional thermal power generation system.
Fig. 4 schematically shows a conventional oxy-fuel combustion power generation system.

These and other objects, features and other advantages of the present invention will become more apparent by describing in detail preferred embodiments of the present invention with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, the definitions of these terms should be described based on the contents throughout this specification.

In addition, the described embodiments are provided for illustrative purposes and do not limit the technical scope of the present invention.

The constituent elements of the pressurized oxyfuel combustion power generation system of the present invention can be used integrally or separately. In addition, some components may be omitted depending on the usage pattern.

Hereinafter, a pressurized oxyfuel combustion power generation system (hereinafter, simply referred to as a 'power generation system') according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a power generation system according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating an integrated type flue gas condenser, which is one example of a power generation system according to an embodiment of the present invention.

It should be noted that the term "pure oxygen" as used herein means a gas containing a predetermined amount of oxygen rather than air and does not necessarily mean 100% oxygen.

First, a configuration of a power generation system according to an embodiment of the present invention will be described with reference to FIG. 1 attached hereto.

1, a power generation system according to an embodiment of the present invention includes a boiler 100, an integrated flue gas condenser 300, and a CPU (CO 2 process unit) 700.

Fuel and pure oxygen are supplied into the boiler 100 for combustion.

The pure oxygen supplied to the boiler 100 is pressurized to a predetermined pressure or higher, and may be pressurized to a pressure of 3 to 20 bar. However, the present invention is not limited thereto.

The pure oxygen supplied to the boiler 100 is pure oxygen in which gases other than oxygen (such as nitrogen) are separated from the air introduced into the pressurized ASU 200 (Air Separation Unit), and pure oxygen separated from the air is pressurized, (100).

In addition, the fuel is supplied to the boiler 100, and the combustion of the pure oxygen and the fuel supplied in the boiler 100 is performed.

In this way, by supplying the pressurized pure oxygen to the boiler 100, even if the fuel supplied is of relatively low quality (for example, the water content is high), combustion can be performed with high efficiency.

The heat generated by the combustion in the boiler 100 is recovered as steam through a heat exchanger 110 in which a heating medium (water) flows, and is supplied to the turbine 300 or the like to generate electricity.

Meanwhile, the ash or slag generated in the combustion in the boiler 100 is discharged to one side of the boiler 100.

Hereinafter, an integrated flue gas condenser 400, which is an embodiment of the present invention, will be described with reference to FIG.

The integrated flue gas condenser 400 includes a flue gas condensation tank 410 and a heat exchange tube located within the flue gas condensation tank 410.

The exhaust gas condensing tank 410 constitutes the outside of the integral exhaust gas condenser 400, and the high-temperature / high-pressure exhaust gas generated by the combustion in the boiler flows into the exhaust gas condensing tank 410, so that the inside of the condenser 410 is maintained at a high pressure.

The heat exchange tube passes through the inside of the one side of the flue gas condensation tank (420), and the heat medium flows into the heat exchange tube (420).

As described above, through the heat exchange tube 420 located in the flue gas condensing tank 410, the integrated flue gas condenser 400 can collect heat from the flue gas introduced and remove the pollutants integrally. Will be described later.

The CPU 700 separates, collects and discharges carbon dioxide contained in the flue gas from which heat recovery, contaminants and impurities are removed in the integrated flue gas condenser 400, and the flue gas from which carbon dioxide has been removed is discharged separately.

The operation of the integrated flue gas condenser and the power generation system including the integrated flue gas condenser according to the embodiment of the present invention will be described below with reference to FIGS. 1 and 2 attached hereto.

Pure oxygen separated from the air supplied to the pressurized ASU 200 and pressurized to a predetermined pressure or higher is supplied to the boiler 100, separately from which fuel is supplied to the boiler 100.

In the boiler 100, the supplied fuel and pure oxygen are burned, and the generated heat is recovered as steam by the heat exchanger 110 provided in the boiler 100 and can be used for power generation through the turbine 300 .

Meanwhile, when pure oxygen pressurized by the boiler 100 is supplied and burned, the generated flue gas is also discharged to a high pressure state and then flows into the integrated flue gas condenser 400.

At this time, the exhaust gas having relatively large particles removed from the dust contained in the exhaust gas through a dust removing device (not shown) positioned between the boiler 100 and the integrated exhaust gas condenser 400 is exhausted to the integrated exhaust gas condenser 400 .

The flue gas introduced into one side of the flue gas condensing tank 410 of the integrated flue gas condenser 400 passes through the flue gas condensing tank 410 and is first introduced into the flue gas condensing tank 410 through the flue gas Condensation of water (water vapor) occurs, and latent heat of the flue gas is recovered.

 The condensation temperature of the moisture contained in the exhaust gas is higher than that at the normal pressure in the high pressure state, so that the higher heat of about 150 ° C or more can be recovered through the condensation of water contained in the exhaust gas.

Such high heat can be utilized to improve the efficiency of the entire power generation system by compensating for the problem of the conventional oxy-fuel combustion system, that is, the energy loss in separating the air from the ASU.

For example, the heat recovered by the integrated flue gas condenser 400 may be supplied to the pressurized ASU 200 to preheat and supply the oxygen supplied to the boiler 100, or may be used to pass through the boiler 100 To the heat exchanger (110) for heating the heat medium flowing in the heat exchanger (110), thereby increasing the efficiency of the combustion system.

The condensed water (condensed water) by the heat exchange in the flue gas condensing tank 410 reacts with the pollutants contained in the flue gas, that is, the sulfur oxides (SOx) and the nitrogen oxides (NOx) Is removed.

As described above, the inside of the flue gas condensing tank 410 is maintained at a high temperature / high pressure atmosphere due to the high temperature / high pressure flue gas introduced into the flue gas condensing tank 410, as described above.

Therefore, the inside of the flue gas condensing tank 410 becomes an atmosphere similar to the lead chamber used for sulfuric acid production. The lead chamber process is a sulfuric acid production method in which sulfuric acid is produced using nitrogen oxide as a catalyst in a high temperature furnace. The inside of the flue gas condensing tank 410 becomes an atmosphere similar to the flue gas, SOx and NOx are mainly water soluble SO2 and NO2 in the pressurized condition, and these pollutants react with water. In this case, NO2 also acts as a catalyst in the process of dissolving in water or reacting with aqueous sulfuric acid solution do.

Accordingly, the sulfur oxides and the nitrogen oxides react with the condensed water and are discharged and removed in the form of an aqueous sulfuric acid solution. Therefore, in order to prevent corrosion of the heat exchange tubes 420 due to this, the heat exchange tubes 420 are made of corrosion- (Not shown) for preventing the sulfuric acid aqueous solution from forming on the heat exchange tube 420 may be provided in the flue gas condensation tank 410.

As shown in FIG. 2, the flue gas condensing tank 410 of the integrated flue gas condenser 400 may further include a scrubber.

One or more of the scrubber 430 is disposed in the other side of the flue gas condensing tank 410. The flue gas discharged from the flue gas condensing tank 410 is scrubbed by scrubbing by spraying the supplied washing water.

Specifically, the flue gas from which the SOx and NOx are removed flows to the side of the scrubber 430 in the flue gas condensing tank 410, and impurities such as dust contained in the flue gas are scrubbed by the washing water supplied to the scrubber 430 Removed.

In addition, the aqueous sulfuric acid solution produced and discharged as described above can be separated into water and sulfuric acid through the purification unit 500 connected to the integrated flue gas condenser 400. In this case, So that the exhaust gas can be cleaned more efficiently.

As described above, the integrated flue gas condenser 400 has an advantage that it can collectively treat contaminants and impurities contained in the flue gas using condensed water generated by condensation through heat recovery of flue gas, as well as heat recovery of flue gas.

Thus, the configuration of the SCR (4), EP (5), FGD (6), etc. (refer to FIG. 4) provided for the flue gas treatment in the existing thermal power generation is integrally implemented by using the pressurized pure oxygen combustion condition Surplus oxygen in the flue-gas also contributes to the higher purity of the CO2 in the flue-gas.

The exhaust gas passing through the integrated flue gas condenser 400 and having the heat recovery and contaminants removed is substantially made of carbon dioxide, which is collected and processed / discharged through the CPU 800. However, most of the pollutants in the flue gas are removed from the integrated flue gas condenser 400, and the water is condensed to scrub away the dust in the flue gas. As a result, the purity of CO2 in the flue gas is increased as described above, So that the installation burden of the CPU 300 can be greatly reduced.

As described above, according to the integrated flue gas condenser and the pressurized pure oxygen generating system according to the present invention, pure oxygen is pressurized and burned with fuel to obtain a high combustion efficiency, and consequently, the water contained in the pressurized flue gas is condensed It is possible to compensate for thermal efficiency loss due to pure oxygen combustion by collecting heat at a high temperature and simultaneously treat the pollutants contained in the exhaust gas to greatly reduce the burden on facilities for capturing carbon dioxide.

Although the preferred embodiments of the present invention have been described, the present invention is not limited to the specific embodiments described above. It will be apparent to those skilled in the art that numerous modifications and variations can be made in the present invention without departing from the spirit or scope of the appended claims. And equivalents should also be considered to be within the scope of the present invention.

100: Boiler
200: Pressurized ASU
400: Integrated flue gas condenser
410: Flue gas condensing tank
420: Heat exchange tube
430: Washer
500:
700: CPU

Claims (6)

A flue gas condensing tank 410 into which flue gas discharged from a boiler in which pressurized pure oxygen is combusted flows and is maintained at a pressure higher than a predetermined level; And
And a heat exchange tube (420) disposed at one side of the exhaust gas condensing tank (410) and through which the heating medium flows,
The heat exchange between the heat medium supplied to the heat exchange tube 420 and the flue gas introduced into the flue gas condensation tank 410 condenses moisture in the flue gas and the latent heat contained in the flue gas is recovered through the heating medium, Wherein the pollutants contained in the flue gas are dissolved in the water,
Integrated flue gas condenser.
An integrated flue gas condenser (400) according to claim 1;
A boiler (100) for burning pressurized oxygen and fuel at a predetermined pressure, and discharging exhaust gas generated by the combustion to the integrated heat recovery apparatus;
A pressurized ASU 200 for separating pure oxygen from air and supplying it to the boiler 100;
A steam turbine generator 300 for generating electricity using steam produced through heat exchange in the boiler 100; And
And a CPU (700) for separating carbon dioxide contained in the exhaust gas discharged from the integrated flue gas condenser.
Pressurized oxyfuel combustion power generation system.
3. The method of claim 2,
The boiler 100 is supplied with the latent heat of the exhaust gas recovered in the integrated exhaust gas condenser 400 to the pressurized ASU 200 to preheat the pure oxygen supplied to the boiler 100,
Pressurized oxyfuel combustion power generation system.
3. The method of claim 2,
And a scrubber (430) disposed on the other side in the flue gas condensing tank (410)
The cleaning water supplied from the cleaner 430 removes contaminants contained in the exhaust gas and cleans the dust,
Pressurized oxyfuel combustion power generation system.
3. The method of claim 2,
And a purifier (500) for purifying contaminants in an aqueous solution containing contaminants discharged from the integrated flue gas condenser (400)
And the purified water in the purification unit 500 is supplied to the cleaner 430 as cleaning water,
Pressurized oxyfuel combustion power generation system.
3. The method of claim 2,
The heat exchanger 110 supplies the latent heat of the flue gas recovered in the integrated flue gas condenser 400 to the heat exchanger 110 passing through the boiler 100 to heat the heat medium flowing in the heat exchanger 110,
Pressurized oxyfuel combustion power generation system.

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