CN119013515A

CN119013515A - Combustion system

Info

Publication number: CN119013515A
Application number: CN202380032722.2A
Authority: CN
Inventors: 崔原荣; 藤森俊郎
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 2022-07-05
Filing date: 2023-04-06
Publication date: 2024-11-22
Also published as: JPWO2024009575A1; JP7491483B1; KR20240172753A; WO2024009575A1

Abstract

A combustion system (100) is provided with: a gasifier (2) for heating the liquid ammonia by means of a thermal medium; a boiler (3) connected to the gasifier (2) for burning a fuel containing ammonia from the gasifier (2); an induction ventilator (6) which is disposed in a flue (L4) connected to the boiler (3) and which induces exhaust gas from the boiler (3); and a heat exchanger (4) disposed upstream of the induction ventilator (6) in the flue (L4). The heat exchanger (4) is connected to the gasifier (2) in a circulating manner through a circulating passage (L5) through which the heat medium flows. The heat exchanger (4) cools the exhaust gas flowing through the flue (L4) by using a heat medium from which cold energy is obtained from the liquid ammonia.

Description

Combustion system

Technical Field

The present disclosure relates to combustion systems. The present application claims priority based on japanese patent application No. 2022-108342, filed on day 5, 7, 2022, and the contents of which are incorporated herein by reference.

Background

Ammonia is known as a fuel that does not release CO ₂. For example, patent documents 1 and 2 disclose apparatuses using ammonia as a fuel. In these documents, ammonia is stored in a liquid state. The liquid ammonia is gasified before combustion and burned in a gaseous state. In these documents, exhaust heat after combustion is used for gasifying ammonia.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2020-139638

Patent document 2: japanese patent application laid-open No. 2019-196882

Summary of The Invention

Problems to be solved by the invention

In the above-described combustion system, further improvement in energy efficiency is desired.

An object of the present disclosure is to provide a combustion system capable of improving energy efficiency.

Means for solving the problems

The combustion system according to one aspect of the present disclosure includes: a gasifier that heats the liquid ammonia with a thermal medium; a boiler connected to the gasifier for burning fuel containing ammonia from the gasifier; an induction ventilator which is disposed in a flue connected to the boiler and induces exhaust gas from the boiler; and a heat exchanger disposed upstream of the induction fan in the flue, the heat exchanger being connected to the gasifier in a circulating manner through a circulating passage through which the heat medium flows, the heat exchanger cooling the exhaust gas flowing in the flue by the heat medium from which cold energy is obtained from the liquid ammonia.

The combustion system may include a recovery device that recovers condensed water from the cooled exhaust gas.

The recoverer may be connected to a boiler, and supply condensed water as makeup water to the boiler.

The combustion system may include a control device that adjusts the flow rate of the heat medium based on at least one of the temperature of the exhaust gas, the flow rate of the exhaust gas, and the flow rate of the ammonia.

Effects of the invention

According to the present disclosure, energy efficiency can be improved.

Drawing translation

Fig. 1 is a schematic diagram illustrating a combustion system according to an embodiment.

Fig. 2 is a graph showing a relationship between temperature and saturated water vapor pressure.

Detailed Description

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The specific dimensions, materials, numerical values, and the like shown in this embodiment are merely examples for easy understanding, and the present disclosure is not limited thereto except for the case of specific description. In the present specification and the drawings, elements having substantially the same functions and structures are denoted by the same reference numerals, and overlapping description thereof is omitted, and elements not directly related to the present disclosure are not shown.

Fig. 1 is a schematic diagram illustrating a combustion system 100 according to an embodiment. Hereinafter, the combustion system 100 may also be simply referred to as a "system". For example, the system 100 includes a tank 1, a gasifier (EVA) 2, a boiler 3, a Heat Exchanger (HEX) 4, an electric dust collector (ESP) 5, an Induced Draft Fan (IDF) 6, a stack 7, a regenerator 8, a steam turbine 50, a generator 60, and a control device 90. The components of the system 100 are not limited thereto, and the system 100 may further include other components. In addition, the system 100 may not include at least one of the above-described components.

A tank (ammonia supply source) 1 supplies liquid ammonia to a gasifier 2. Tank 1 stores liquid ammonia. Tank 1 is connected to vaporizer 2 through flow path L1. The liquid ammonia in the tank 1 is supplied to the gasifier 2 through the flow path L1. For example, a pump P1 for delivering liquid ammonia is provided in the flow path L1. The pump P1 may be communicatively connected to the control device 90 by wire or wirelessly, and the control device 90 may control the operation of the pump P1.

The vaporizer 2 heats the liquid ammonia from the tank 1 by a heat medium heated by the heat exchanger 4, which will be described later. The heated liquid ammonia gas is converted to gaseous ammonia. In another aspect, the heat medium is cooled by liquid ammonia in the gasifier 2, from which cold energy is extracted. The gasifier 2 is connected to the boiler 3 through a flow path L2.

The boiler 3 comprises a burner 31 for burning a fuel comprising gaseous ammonia from the gasifier 2. For example, the burner 31 may burn a mixed fuel containing ammonia and other fuel such as pulverized coal. For example, the burner 31 may burn only ammonia. For example, the burner 31 may burn only fuel other than ammonia, if necessary. The boiler 3 heats water by using heat generated by combustion to generate steam. In the burner 31, exhaust gas is generated by combustion.

The steam turbine 50 is connected to the boiler 3 through a flow path L3. The steam generated by the boiler 3 is supplied to the steam turbine 50 through the flow path L3. The steam turbine 50 is rotated by the steam from the boiler 3. The generator 60 rotates together with the steam turbine 50 to generate electricity.

In the present embodiment, the heat exchanger 4, the electric dust collector 5, and the induction ventilator 6 are disposed in this order from the boiler 3 in the flue L4 connecting the boiler 3 and the chimney 7. The system 100 may include other devices not shown in the drawing in the flue L4. In the flue L4, the exhaust gas generated by the boiler 3 flows from the boiler 3 toward the stack 7.

The heat exchanger 4 is disposed downstream of the boiler 3 in the flue L4, and is connected to the boiler 3. The heat exchanger 4 is connected to the gasifier 2 in a circulating manner through a circulating passage L5. The heat medium flows through the circulation flow path L5. The heat exchanger 4 cools the exhaust gas flowing through the flue L4 by using a heat medium that has acquired cooling energy from the liquid ammonia in the gasifier 2. Thereby, a part of the water vapor in the exhaust gas is condensed into water. In another aspect, the heat medium is heated by the exhaust gas in the heat exchanger 4.

Regarding the amount of water vapor in the exhaust gas flowing in the flue L4, the combustion reaction formula of ammonia is represented by 2NH ₃+1.5O₂→N₂+3H₂ O. At an equivalence ratio of 1,3 molecules of water are produced from 2 molecules of ammonia. Therefore, in the case where only ammonia is burned in the boiler 3, more than 70% of the exhaust gas may become water vapor in the volume ratio. For example, when only pulverized coal is burned in the boiler 3, about 10% to 20% of the exhaust gas can be steam.

In this way, when the boiler 3 burns the fuel containing ammonia, the exhaust gas flowing through the flue L4 contains more water vapor. However, in the present embodiment, the exhaust gas is cooled by the heat medium in the heat exchanger 4, and a part of the water vapor in the exhaust gas is condensed into water. Therefore, even when the exhaust gas contains more water vapor, the water vapor in the exhaust gas can be reduced in the heat exchanger 4.

The heat medium flowing through the circulation flow path L5 may be, for example, brine. For example, the brine may be an aqueous solution containing sodium chloride, calcium chloride, or the like. The heat medium is not limited thereto, and other fluids may be used. For example, the heat medium may be a fluid having a freezing point lower than the boiling point of liquid ammonia.

The heat exchanger 4 is provided with a recovery device 8. The recoverer 8 recovers condensed water from the exhaust gas cooled by the heat medium in the heat exchanger 4. For example, the recycler 8 may also be a tank or pit (pit) connected to the bottom of the heat exchanger 4. For example, the recoverer 8 may recover condensed water falling from the exhaust gas to the bottom of the heat exchanger 4. The position where the recoverer 8 is provided is not limited to this, and the recoverer 8 may be provided in the flue L4 at a position downstream of the heat exchanger 4, for example, at a position between the heat exchanger 4 and the induction ventilator 6.

The recoverer 8 is connected to the boiler 3 through a flow path L6. The condensed water recovered by the recovery unit 8 is supplied as makeup water to the boiler 3 through the flow path L6. Therefore, water generated by the combustion of ammonia can be reused in the boiler 3. For example, a pump P2 for conveying condensed water is provided in the flow path L6. The pump P2 may be communicatively connected to the control device 90 by wire or wirelessly, and the control device 90 may control the operation of the pump P2. A filter (not shown), for example, a reverse osmosis membrane (RO), for purifying condensed water may be provided in the flow path L6. Alternatively or additionally, the recoverer 8 may be connected to other equipment not shown in the system 100, and the condensed water may be reused as industrial water in the equipment. For example, the condensed water may be reused as water for injection in the cooling tower. For example, the condensed water may be reused as agricultural water or beverage water after purification.

The electric vacuum cleaner 5 is disposed downstream of the heat exchanger 4 in the flue L4, and is connected to the heat exchanger 4. The electric dust collector 5 removes particles (coal dust) from the exhaust gas. Specifically, the electric vacuum cleaner 5 applies a high voltage between the discharge electrode and the suction electrode, and generates corona discharge. Ions are generated by corona discharge. Particles in the exhaust gas charged by the ions are attracted to the dust collection electrode by electrostatic attraction. Particles collected in the suction electrode are removed.

The induction ventilator 6 is disposed downstream of the electric vacuum cleaner 5 in the flue L4, and is connected to the electric vacuum cleaner 5. The induction ventilator 6 induces the exhaust gases from the boiler 3 to the stack 7. The induced draft fan 6 maintains the boiler 3 at a negative pressure. In the induction ventilator 6, the exhaust gas is pressurized.

As described above, when the boiler 3 burns the fuel containing ammonia, the exhaust gas flowing through the flue L4 contains more water vapor. In the case where the exhaust gas containing more water vapor flows into the induction ventilator 6, the load of the induction ventilator 6 increases. However, in the present embodiment, in the heat exchanger 4, a part of the water vapor in the exhaust gas is condensed into water, and the water vapor in the exhaust gas is reduced. Therefore, even when the boiler 3 burns the fuel containing ammonia, an increase in the load of the induction ventilator 6 can be suppressed. Therefore, in the case where the system 100 uses ammonia as fuel, energy efficiency can be improved.

In the present embodiment, the exhaust gas is cooled by the heat medium in the heat exchanger 4, and therefore the volume of the exhaust gas flowing through the flue L4 is reduced. Thus, the volume of the exhaust gas flowing into the induction ventilator 6 is reduced. This also reduces the load on the induced ventilator 6. In addition, the boiler 3 is easily maintained at a negative pressure with a decrease in the volume of the exhaust gas.

The chimney 7 is disposed downstream of the induction ventilator 6 in the flue L4, and is connected to the induction ventilator 6. The stack 7 releases the exhaust gas to the outside.

The circulation flow path L5 is provided with a pump P3 for circulating the heat medium. The pump P3 is connected to the control device 90 so as to be capable of communication by wire or wireless. The control device 90 controls the operation of the pump P3.

The circulation flow path L5 is provided with a valve V1. For example, the valve V1 is connected to the control device 90 in a manner capable of communication by wire or wireless. The control device 90 adjusts the flow rate of the heat medium flowing through the circulation flow path L5 by controlling the opening degree of the valve V1.

The system 100 includes a temperature sensor S1 in the flue L4. The temperature sensor S1 is configured to measure the temperature of the exhaust gas flowing out of the heat exchanger 4. For example, the temperature sensor S1 is disposed in the flue L4 at a position downstream of the heat exchanger 4. However, the position of the temperature sensor S1 is not limited to this, and the temperature sensor S1 may be disposed at another position.

The system 100 includes a flow sensor S2 in the flue L4. The flow sensor S2 is configured to measure the flow rate of the exhaust gas flowing through the flue L4. For example, the flow sensor S2 is disposed in the flue L4 at a position downstream of the heat exchanger 4. However, the position of the flow sensor S2 is not limited to this, and the flow sensor S2 may be disposed at another position.

The system 100 includes a flow sensor S3 in the flow path L1. The flow sensor S3 is configured to measure the flow rate of the liquid ammonia delivered from the tank 1 to the gasifier 2. For example, the flow sensor S3 is disposed in the flow path L1 at a position upstream of the gasifier 2 and upstream of the pump P1. However, the position of the flow sensor S3 is not limited to this, and the flow sensor S3 may be disposed at another position.

The temperature sensor S1 and the flow sensors S2 and S3 are connected to the control device 90 so as to be capable of communication by wire or wireless, and transmit measured data to the control device 90. In other embodiments, the system 100 may also be provided with other sensors. In other embodiments, the system 100 may not include at least one of the temperature sensor S1 and the flow sensors S2 and S3.

The control device 90 controls the whole or a part of the system 100. For example, the control device 90 may also include one or more computers. For example, the operations of the control device 90 described in the present disclosure may be executed by one computer, or may be executed separately by a plurality of computers. The control device 90 includes, for example, a processor 90a, a storage device 90b, and a connector 90c, which are connected to each other via a bus. For example, the processor 90a includes a CPU (Central Processing Unit ) or the like. For example, the storage device 90b includes a hard disk, a ROM storing programs and the like, a RAM as a work area, and the like. The control device 90 is connected to the components of the system 100 via a connector 90c so as to be capable of communication by wire or wireless. For example, the control device 90 may include a display device such as a liquid crystal display or a touch panel, and other components such as an input device such as a keyboard, buttons, or a touch panel. For example, the operations of the control device 90 described in the present disclosure may be realized by causing the processor 90a to execute a program stored in the storage device 90 b.

Next, the operation of the control device 90 will be described.

Fig. 2 is a graph showing a relationship between temperature and saturated water vapor pressure. In fig. 2, the horizontal axis represents temperature and the vertical axis represents saturated water vapor pressure.

The 1 atmosphere is approximately 1000hPa. For example, in the case where the concentration of water vapor in the exhaust gas is controlled to be less than 20% at 1 atmosphere, it is necessary to adjust the saturated water vapor pressure to be less than about 200hPa (200 hpa=1000 pa×0.2). As shown in fig. 2, the saturated water vapor pressure can be adjusted to less than about 200hPa by controlling the temperature of the exhaust gas to less than about 60 ℃. Therefore, for example, under the above-described conditions, the control device 90 may store 60 ℃ as the threshold value of the temperature of the exhaust gas in the storage device 90b. The threshold value is not limited to 60 ℃, and may vary depending on various factors such as the performance of the induced ventilator 6.

Referring to fig. 1, the processor 90a of the control device 90 controls the system 100 in such a manner that the temperature of the exhaust gas received from the temperature sensor S1 is less than the above-described threshold value. For example, the processor 90a controls the valve V1 to adjust the flow rate of the heat medium flowing in the circulation flow path L5 so that the temperature of the exhaust gas received from the temperature sensor S1 is less than the threshold value. For example, when the temperature of the exhaust gas received from the temperature sensor S1 increases, the processor 90a may control the valve V1 to increase the flow rate of the heat medium. Conversely, when the temperature of the exhaust gas received from the temperature sensor S1 decreases, the processor 90a may control the valve V1 to decrease the flow rate of the heat medium.

Alternatively or additionally, the processor 90a may adjust the flow rate of the heat medium based on a parameter other than the temperature of the exhaust gas.

For example, the processor 90a may adjust the flow rate of the heat medium based on the flow rate of the exhaust gas received from the flow sensor S2. For example, when the flow rate of the exhaust gas received from the flow sensor S2 increases, the processor 90a may control the valve V1 to increase the flow rate of the heat medium. Conversely, when the flow rate of the exhaust gas received from the flow sensor S2 decreases, the processor 90a may also control the valve V1 to decrease the flow rate of the heat medium.

Further, for example, the processor 90a may adjust the flow rate of the heat medium based on the flow rate of the liquid ammonia received from the flow rate sensor S3. For example, as the flow rate of liquid ammonia received from the flow sensor S3 increases, the processor 90a may control the valve V1 to increase the flow rate of the thermal medium. Conversely, when the flow rate of the liquid ammonia received from the flow sensor S3 decreases, the processor 90a may control the valve V1 to decrease the flow rate of the heat medium.

The system 100 described above includes: a gasifier 2 for heating the liquid ammonia by a thermal medium; a boiler 3 connected to the gasifier 2 for burning fuel containing ammonia from the gasifier 2; a guiding ventilator 6 disposed in a flue L4 connected to the boiler 3, for guiding exhaust gas from the boiler 3; and a heat exchanger 4 disposed upstream of the induction ventilator 6 in the flue L4. The heat exchanger 4 is connected to the evaporator 2 in a circulating manner through a circulating passage L5 through which the heat medium flows. The heat exchanger 4 cools the exhaust gas flowing through the flue L4 by using a heat medium that acquires cooling energy from the liquid ammonia. As described above, in the case where the boiler 3 burns fuel containing ammonia, the exhaust gas contains more water vapor. However, according to this structure, even in the case where the exhaust gas contains more water vapor, the water vapor in the exhaust gas can be reduced in the heat exchanger 4. Therefore, an increase in the load of the induction ventilator 6 can be suppressed. In addition, the heat obtained from the exhaust gas can be used for gasification of liquid ammonia. Therefore, in the case where the system 100 uses ammonia as fuel, energy efficiency can be improved.

The system 100 further includes a recovery unit 8 for recovering condensed water from the cooled exhaust gas. With this configuration, condensed water can be stored for reuse.

In the system 100, the recovery unit 8 is connected to the boiler 3, and condensed water is supplied as makeup water to the boiler 3. With this configuration, the amount of water newly added to the system 100 can be reduced as makeup water for the boiler 3.

The system 100 further includes a control device 90 that adjusts the flow rate of the heat medium based on at least one of the temperature of the exhaust gas, the flow rate of the exhaust gas, and the flow rate of the ammonia. With such a configuration, the flow rate of the heat medium can be appropriately adjusted according to the operation condition of the system 100.

The embodiments have been described above with reference to the drawings, but the present disclosure is not limited to the embodiments. It is obvious that various modifications and corrections can be conceived by those skilled in the art within the scope described in the scope of the claims, and it is understood that they are certainly within the technical scope of the present disclosure.

For example, in the above embodiment, the system 100 includes the electric dust collector 5 in the flue L4. In other embodiments, the system 100 may not include the electric vacuum cleaner 5.

The present disclosure can facilitate the use of ammonia in connection with the abatement of CO ₂ emissions, and thus, for example, can contribute to the Sustainable Development Goal (SDGs) goal 7 "ensuring that a affordable, reliable, sustainable modern energy source is obtained, and goal 13" taking urgent action to cope with climate change and its effects.

Symbol description

2 Gasifier

3 Boiler

4 Heat exchanger

6 Induced ventilator

8 Recoverer

90 Control device

100 Combustion system

L4 flue

L5 circulation flow path.

Claims

1. A combustion system, comprising:

a gasifier that heats the liquid ammonia with a thermal medium;

a boiler connected to the gasifier for combusting a fuel containing ammonia from the gasifier;

An induction ventilator which is disposed in a flue connected to the boiler and induces exhaust gas from the boiler; and

A heat exchanger disposed upstream of the induction ventilator in the flue,

The heat exchanger is connected with the gasifier in a circulating way through a circulating flow path of the heat medium,

The heat exchanger cools the exhaust gas flowing in the flue by the heat medium from which cold energy is extracted from the liquid ammonia.

2. A combustion system as set forth in claim 1, wherein,

The combustion system includes a recovery unit that recovers condensed water from the cooled exhaust gas.

3. A combustion system as set forth in claim 2, wherein,

The recoverer is connected to the boiler and supplies the condensed water as makeup water to the boiler.

4. A combustion system as set forth in any one of claims 1 to 3, wherein,

The combustion system includes a control device that adjusts the flow rate of the heat medium based on at least one of the temperature of the exhaust gas, the flow rate of the exhaust gas, and the flow rate of the ammonia.