JP7249109B2 - steam generator - Google Patents

Description

The present invention relates to steam generation equipment.

Patent Literature 1 listed below discloses a combustion apparatus such as a boiler or a gas turbine that uses ammonia as fuel, and a power generation facility using the same (prior invention). This prior invention generates electric power by driving the steam turbine with steam generated by an exhaust heat recovery steam generator operated by the exhaust heat of the gas turbine, and uses the hot water generated by the exhaust heat steam generator to generate electricity. vaporizes ammonia (liquid), which is the fuel of

International Publication No. 2017/187619 pamphlet

By the way, in the above-mentioned prior invention, since hot water for vaporizing ammonia is generated by the exhaust heat recovery boiler that generates steam to be supplied to the steam turbine generated by the heat recovery boiler, the overall power generation efficiency of the power generation equipment is lowered. . That is, in the above prior art, part of the thermal energy recovered by the heat recovery steam generator is consumed to generate the hot water, so the power generation efficiency is reduced by the amount of this energy consumption.

SUMMARY OF THE INVENTION The present invention has been made in view of the circumstances described above, and an object of the present invention is to improve energy acquisition efficiency when acquiring energy by burning ammonia.

In order to achieve the above object, in the present invention, as a first solution related to steam generation equipment, a main body for generating steam by burning gaseous ammonia as a part of fuel, a tank for storing liquid ammonia, a vaporizer for vaporizing liquid ammonia to generate the gaseous ammonia, wherein the vaporizer employs means for vaporizing the liquid ammonia using combustion gas passing through a flue as a heat source.

In the present invention, as a second solution related to steam generation equipment, in the first solution, the vaporizer vaporizes the liquid ammonia using the combustion gas immediately before being released to the atmosphere in the flue as a heat source. adopt the means of

In the present invention, as a third solution to the steam generation equipment, the first or second solution is further provided with a heat exchanger for exchanging heat between the combustion gas and a predetermined heat medium,
The vaporizer employs means for vaporizing the liquid ammonia using the heat medium as a heat source.

In the present invention, as a fourth solving means relating to the steam generating equipment, in the third solving means, the heat medium is water.

In the present invention, as a fifth solution related to steam generation equipment, in the first solution, the vaporizer exchanges heat between the liquid ammonia and the combustion gas to vaporize the liquid ammonia. adopt means.

In the present invention, as a sixth solution related to steam generation equipment, in the fifth solution, the vaporizer separates the combustion gas and the liquid ammonia in the latter stage of the desulfurization device provided in the flue. Employ a means of exchanging heat.

In the present invention, as a seventh solving means related to the steam generating equipment, in any one of the first to sixth solving means, the main body adopts means for co-firing the pulverized coal with the gaseous ammonia.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to improve the energy acquisition efficiency at the time of burning ammonia and acquiring energy compared with the past.

1 is a system configuration diagram of power generation equipment according to an embodiment of the present invention; FIG. It is a system block diagram of the power generation equipment which concerns on the 1st modification of one embodiment of this invention. It is a system block diagram of the power generation equipment which concerns on the 2nd modification of one Embodiment of this invention.

An embodiment of the present invention will be described below with reference to the drawings.
The power generation equipment according to the present embodiment generates power using steam obtained by burning pulverized coal and ammonia. More specifically, gaseous ammonia obtained by vaporizing liquid ammonia (liquid ammonia) is co-fired with pulverized coal to generate power.

As shown in FIG. 1, this power generation facility includes a pulverized coal supply device 1, an ammonia supply device 2, a boiler 3 (main body), an exhaust gas treatment facility 4, a chimney 5, a steam turbine 6, a generator 7, a condenser 8, and a water supply. A pump 9 and the like are provided. The pulverized coal supply device 1, the ammonia supply device 2, the boiler 3 (main body), the exhaust gas treatment equipment 4, and the chimney 5 in the power generation equipment constitute steam generation equipment in the present invention.

The ammonia supply device 2 is the most characteristic component in this embodiment, and includes an ammonia tank 2a, a first pump 2b, an ammonia vaporizer 2c, a circulation pipe 2d, a second pump 2e, and a heat exchanger 2f. I have.

The pulverized coal supply device 1 is a device that produces pulverized coal and supplies the pulverized coal to the boiler 3 as one fuel. This pulverized coal supply device 1 grinds coal in a mill to produce pulverized coal having a predetermined particle size, and supplies the pulverized coal to a boiler 3 sequentially and continuously.

The ammonia supply device 2 is a device that produces gaseous ammonia and supplies the gaseous ammonia to the boiler 3 as the other fuel. That is, the ammonia supply device 2 vaporizes liquid ammonia to produce gaseous ammonia, and sequentially and continuously supplies the gaseous ammonia to the boiler 3 . Here, the pulverized coal is the main fuel in the power generation facility, and gaseous ammonia is supplementary fuel supplied to the boiler 3 to the pulverized coal (main fuel).

In such an ammonia supply device 2, the ammonia tank 2a is a container with a predetermined capacity that temporarily stores liquid ammonia. The first pump 2b pumps out a predetermined flow rate of liquid ammonia from the ammonia tank 2a and supplies it to the ammonia vaporizer 2c. The ammonia vaporizer 2c is a device that heats and vaporizes liquid ammonia to generate gaseous ammonia. The ammonia vaporizer 2c heats liquid ammonia to a vaporization temperature or higher by exchanging heat with a heat medium.

The circulation pipe 2d is a pipe that connects the ammonia vaporizer 2c and the heat exchanger 2f, and provides a route (circulation route) for a predetermined heat medium to circulate between the ammonia vaporizer 2c and the heat exchanger 2f. Configure. The second pump 2e is provided in the middle of the circulation pipe 2d, and is a power source for circulating (fluidizing) the heat medium in a predetermined direction in the circulation pipe 2d. The second pump 2e circulates (fluidizes) the heat medium from the ammonia vaporizer 2c toward the heat exchanger 2f, as shown. The heat medium is, for example, water or seawater.

The heat exchanger 2f exchanges heat between the combustion gas supplied from the exhaust gas treatment facility 4 to the chimney 5 and the heat medium. That is, the heat exchanger 2f heats the heat medium supplied from the second pump 2e to a predetermined temperature exceeding the vaporization temperature of liquid ammonia using the thermal energy of the combustion gas, and the heat medium after the heating is vaporized into ammonia. output to the device 2c.

The boiler 3 includes a furnace body for co-firing the above-described pulverized coal and gaseous ammonia, and generates steam by heating water flowing through hydrothermal tubes provided in the furnace body with combustion heat. In the above-mentioned furnace body, the lower part provided with a nozzle for injecting pulverized coal inside, a nozzle for injecting gaseous ammonia inside, a nozzle for supplying combustion air inside, etc. is a combustion that mixes pulverized coal and gaseous ammonia Space. Further, in the furnace body, the upper portion where a plurality of hydrothermal tubes are provided on the furnace wall or the like is a heat exchange area where the combustion gas generated by combustion exchanges heat with the water in the hydrothermal tubes. Such a boiler 3 corresponds to the main body in the present invention.

The exhaust gas treatment equipment 4 is equipment for treating combustion gas (exhaust gas) discharged from the boiler 3 toward the chimney 5 , and is provided in the flue connecting the boiler 3 and the chimney 5 . Since the exhaust gas contains nitrogen oxides, sulfides, and other components that must be removed from the exhaust gas, the exhaust gas treatment equipment 4 separates and removes such components from the exhaust gas.

As illustrated, the exhaust gas treatment facility 4 includes a denitration device 4a, a GAH (Gas Air Heater) 4b, an EP (Electrostatic Precipitator) 4c, an IDF (Induced Draft Fan) 4d, and a wet desulfurization device 4e. That is, the exhaust gas treatment equipment 4 is provided in the order of denitrification device 4a→GAH 4b→EP 4c→IDF 4d→wet desulfurization device 4e from the upstream side (boiler 3 side) to the downstream side (chimney 5 side) in the flue.

The denitration device 4a removes nitrogen oxides (NOx) contained in the exhaust gas. This denitrification device 2 decomposes nitrogen oxides (NO _x ) into nitrogen (N ₂ ) and water (H ₂ O) by causing a predetermined reducing agent to act on exhaust gas in the presence of a catalyst, for example. The GAH 4b is an air preheater that preheats the combustion air supplied to the boiler 3 using the heat of the exhaust gas. The GAH 4 b is a kind of heat exchanger, and heats (preheats) the combustion air by exchanging heat between the combustion air taken in from outside and the exhaust gas, and supplies it to the boiler 3 .

EP4c is an electrostatic precipitator that adsorbs and removes dust contained in exhaust gas. This EP4c is equipped with a plurality of discharge electrodes (electrodes) and dust collection electrodes (electrodes), and the dust contained in the exhaust gas is charged by corona discharge generated around the discharge electrodes, and the dust collection electrodes generate the charged dust. It is made to adhere to the dust collecting electrode by an electric field. The IDF 4 d is an induced draft fan that ventilates the exhaust gas toward the stack 5 .

The wet desulfurization device 4e separates and removes the sulfur oxides _SOx contained in the exhaust gas based on the wet desulfurization method. That is, the wet desulfurization apparatus 4e uses, for example, a suspension of lime or magnesium hydroxide as an adsorbent, and by dropping the adsorbent into the exhaust gas, the sulfur oxide _SOx is taken into the adsorbent. Separated and removed from exhaust gas. In addition to the wet desulfurization method, a dry desulfurization method is known as a flue gas desulfurization technique. Therefore, a dry desulfurization device based on a dry desulfurization method may be employed instead of the wet desulfurization device 4e as required.

The chimney 5 is a vertical tubular structure having a predetermined length, and discharges exhaust gas supplied from the flue to the lower end into the atmosphere from the upper end (high place). This chimney is provided with an exhaust gas heating device as required. The steam turbine 6 is a rotary machine that rotates using steam supplied from the boiler 3 as a working fluid, and is axially coupled to the generator 7 . That is, the steam turbine 6 functions as a power source that drives the generator 7 to rotate.

The generator 7 is an electrical machine that generates AC power by being rotationally driven by the steam turbine 6 . The electric power generated by the generator 7 is supplied to consumers through predetermined distribution lines. The condenser 8 condenses steam discharged from the steam turbine 6, that is, steam (gas) after power recovery by the steam turbine 6, into condensed water. A water supply pump 9 supplies this condensed water to the boiler 3 . This condensed water is supplied to the hydrothermal tubes of the boiler 3 and becomes steam.

Next, the operation of such power generation equipment will be described in detail.
In this power generation facility, pulverized coal and gaseous ammonia are co-fired in the boiler 3 to generate high-temperature combustion gas, and the heat of the combustion gas is used to generate steam, which is the working fluid of the steam turbine 6 .

The kinetic energy of the steam causes the steam turbine 6 to generate rotational power, and the rotational power drives the generator 7 to generate power. The steam after power recovery by the steam turbine 6 is condensed into condensed water by the condenser 8 and returned to the boiler 3 via the feed water pump 9 .

On the other hand, the combustion gas generated in the boiler 3 is discharged into the atmosphere from the chimney 5 through the flue as exhaust gas. That is, nitrogen oxides NOx, dust and sulfide SOx contained in the combustion gas (exhaust gas) are separated and removed from the combustion gas (exhaust gas) by the exhaust gas treatment equipment 4 while passing through the flue. Then, the sufficiently purified exhaust gas is released into the atmosphere from the chimney 5 .

Here, the temperature of the exhaust gas supplied from the flue to the chimney 5 is generally 100 or higher. That is, the temperature of the exhaust gas input to the heat exchanger 2f that constitutes the ammonia supply device 2 is approximately 100 or higher. The vaporization temperature of the liquid ammonia input to the ammonia vaporizer 2c is approximately 50° C. with respect to such a temperature of the exhaust gas.

The ammonia supply device 2 in the present embodiment utilizes such a relationship between the temperature of exhaust gas and the vaporization temperature of liquid ammonia to vaporize liquid ammonia to generate gaseous ammonia (fuel). That is, by exchanging heat between 100 or more exhaust gases and the heat medium in the heat exchanger 2f, the heat medium is heated to about 100° C. and supplied to the ammonia vaporizer 2c.

Then, in the ammonia vaporizer 2c, the liquid ammonia is heated to a temperature exceeding the vaporization temperature by heat-exchanging a heat medium of about 100° C. with the liquid ammonia. That is, the ammonia vaporizer 2c vaporizes liquid ammonia using the 100 or more exhaust gases flowing into the heat exchanger 2f as heat sources. As a result, in the ammonia vaporizer 2c, the liquid ammonia is sufficiently vaporized into gaseous ammonia (fuel).

According to such power generation equipment, the ammonia vaporizer 2c vaporizes the liquid ammonia not by using the combustion gas in the boiler 3 as a heat source, but by using the exhaust gas (combustion gas) passing through the flue as a heat source. It is possible to improve power generation efficiency (energy acquisition efficiency) when burning ammonia to acquire electric power (energy).

In addition, since the temperature of the exhaust gas (gas temperature) in the flue increases as it goes upstream, the heat exchanger 2f may be provided further upstream in the flue, but the wet desulfurization apparatus 4e shown in FIG. Since the exhaust gas on the downstream side of is initially free of nitrogen oxides NOx, dust and sulfide SOx contained in the exhaust gas, that is, the combustion gas immediately before release to the atmosphere in the flue (after the wet desulfurization device 4e) Therefore, it is possible to prevent deterioration of the heat exchanger 2f due to nitrogen oxide NOx, dust and/or sulfide SOx.

It should be noted that the present invention is not limited to the above-described embodiments, and for example, the following modifications are conceivable.
(1) In the above embodiment, the case where the present invention is applied to a power generation facility, which is an example of a facility that acquires energy by burning gaseous ammonia, that is, a facility that acquires electric power by burning gaseous ammonia has been described. The invention is not limited to this. The invention is also applicable to other energy harvesting installations.

The present invention is a facility for acquiring steam generated by a boiler 3 as thermal energy, that is, as shown in FIG. 2, from the system configuration of FIG. It is possible to apply to the steam generation equipment that removes

(2) In the above embodiment, the liquid ammonia and the exhaust gas (combustion gas) are not heat-exchanged, but are heat-exchanged via a heat medium. As a result of considering the amount of thermal energy and the positional relationship between the flue and the passage of liquid ammonia, it was adopted as the most rational form.

However, the liquid ammonia and the exhaust gas (combustion gas) may be heat-exchanged without intervening the heat medium. That is, instead of the ammonia supply device 2 described above, as shown in FIG. 3, an ammonia supply device 2A including an ammonia tank 2a, a first pump 2b and an ammonia vaporizer 2c may be employed.

(3) In the above embodiment, pulverized coal and gaseous ammonia are co-fired in the boiler 3, but the present invention is not limited to this. Gaseous ammonia alone may be burned as the sole fuel. In addition, biomass fuel may be co-fired with gaseous ammonia instead of pulverized coal or in addition to pulverized coal, if necessary.

(4) In the above embodiment, the exhaust gas treatment facility 4 including the denitrification device 4a, the GAH 4b, the EP 4c, the IDF 4d, and the wet desulfurization device 4e is employed, but the present invention is not limited to this. For example, when only gaseous ammonia is used as fuel, that is, when pulverized coal is not used as fuel, dust and sulfide are not generated, so EP 4c and wet desulfurization device 4e can be omitted.

Also, the order in the flue of each facility constituting the exhaust gas treatment facility 4 is not limited to the order shown in FIG. The order of each facility in the flue may be changed as needed.

1 pulverized coal supply device 2, 2A ammonia supply device 2a ammonia tank 2b first pump 2c ammonia vaporizer 2d circulation pipe 2e second pump 2f heat exchanger 3 boiler (main body)
4 Exhaust gas treatment equipment 4a Denitration device 4b GAH
4c EP
4d IDE
4e Wet desulfurization equipment 5 Chimney 6 Steam turbine 7 Generator 8 Condenser 9 Feed water pump

Claims (5)

a boiler that burns gaseous ammonia as fuel to generate steam and combustion gases;
a tank for storing liquid ammonia;
a vaporizer for vaporizing liquid ammonia to produce the gaseous ammonia;
A heat exchanger for exchanging heat between the combustion gas passing through the flue and seawater,
The steam generating facility, wherein the vaporizer vaporizes the liquid ammonia using the seawater heat-exchanged by the heat exchanger using the combustion gas as a heat source as a heat source. 2. The steam generating facility according to claim 1, wherein said vaporizer vaporizes said liquid ammonia using said combustion gas immediately before being released to the atmosphere in said flue as a heat source. 2. The steam generating facility according to claim 1, wherein the vaporizer exchanges heat between the liquid ammonia and the seawater to vaporize the liquid ammonia. 4. The steam generating facility according to claim 3, wherein the vaporizer exchanges heat between the combustion gas and the liquid ammonia in the latter stage of the desulfurization device provided in the flue. The steam generating facility according to any one of claims 1 to 4, wherein the boiler co-fires the pulverized coal with the gaseous ammonia.

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