KR20140023113A - The carbon dioxide capture and storage system by using heat pump and fuel cell - Google Patents

Abstract

The present invention can improve the economical efficiency of a carbon dioxide capture and storage system by recovering low-temperature heat from an absorption heat pump in the process of operating the absorption heat pump using the exhaust heat of a fuel cell and high-temperature heat being generated from a heat recovery system. The carbon dioxide capture and storage system according to the present invention can be put to practical use earlier via the capacity increase of the carbon dioxide capture and storage system and the improvement of economical efficiency by operating the generation tower of the carbon dioxide capture and storage system needing a large amount of energy using thermal energy coming from the absorption heat pump. Thereby, the present invention can solve the problems of global warming and climate change by applying technologies for capturing carbon dioxide being discharged from a massive carbon dioxide emission source such as power plants, steel plants, cement plants and oil refineries, wherein carbon dioxide is emitted by the use of fossil fuels. Also, the technology of the carbon capture and storage system capable of stably using sustainable fossil fuels can be applied until economical new renewable energy is developed. [Reference numerals] (100) Boiler; (101) Turbine; (102) Power generation; (103) Condenser; (104) Cooling tower; (105) Pump; (106) Feedwater heater; (107) Deaerator; (130) Carbon capture; (140) Fuel cell; (150) Absorption heat pump; (AA) Exhaust gas

Description

The Carbon Dioxide Capture and Storage System by Using Heat Pump and Fuel Cell}

The present invention provides a technique for supplying a large amount of thermal energy required to capture carbon generated in a power generation or industrial plant. In order to solve this problem, the present invention relates to a carbon dioxide capture storage system that separates and recovers an absorbent and carbon dioxide by heating the heat pump by using heat generated during a power generation cycle using a fuel cell.

 Carbon Dioxide Capture & Storage System

The technology of the carbon capture storage system is to capture, transport and store carbon dioxide from fossil fuel-generated power generation or other industrial processes to prevent carbon dioxide from being released into the atmosphere.

This alleviates the problem of carbon dioxide emissions from fossil fuels, the main culprit of global warming.

Carbon dioxide capture technology is one of the core technologies that accounts for 70 ~ 80% of the total cost.

  Post-Combustion Technology

  -Pre-Combustion Technology

Oxy-Fuel Combustion Technology

Post-combustion carbon capture technology can reduce carbon dioxide emissions in the atmosphere of a power plant equipped with a carbon dioxide capture plant by 80-90% compared to a plant without a facility.

Currently used carbon capture techniques include absorption (Absorption Type), Adsorption (Adsorption Type), Membrane Type, Cryogenics.

Absorption process is easy to apply a large amount of hydrolysis, and is suitable for low concentration gas separation, so that it is easy to apply to most power generation and industrial plants, the absorption process using the amine-based or ammonia-based absorbent is currently in operation.

As shown in FIG. 1, a carbon dioxide capture technology using an absorption method absorbs carbon dioxide into an absorbent by reacting an absorbent with a mixed gas in an absorption tower, and then transfers the carbon dioxide to a stripper tower to collect carbon dioxide from the absorbent. Separation process.

The regeneration tower separates the absorbent and carbon dioxide from the heat energy supplied from the pre-heater applied to the boiler of the plant. At this time, in order to supplement the thermal energy supplied to the regeneration tower, a reboiler (Re-Boiler) is additionally installed and operated as an auxiliary heat source.

In the regeneration tower, the absorbent and carbon dioxide are separated by using thermal energy, and since a large amount of thermal energy is required, the production cost of the product is greatly increased while decreasing the efficiency of the plant due to the use of the thermal energy.

Absorption method is divided into wet and dry. Wet absorption method is technically reliable because of fast reaction with carbon dioxide and high carbon dioxide removal rate, but it is expensive to separate carbon dioxide for recycling absorbent.

On the other hand, the dry absorption method has the advantages of low cost, strong corrosion resistance, and relatively weak reaction with carbon dioxide when the absorbent is regenerated, resulting in relatively low facility construction and operation costs.

On the other hand, the carbon dioxide removal rate is small compared to wet because of its low reactivity with carbon dioxide.

B) Fuel Cell System

As shown in FIG. 2, a fuel cell is a system that generates electricity by a coupling reaction between hydrogen gas (H ₂ ) and oxygen (O ₂ ) in air obtained by reforming city gas. At the positive electrode, hydrogen ions (H +), which have migrated in solution from the negative electrode, and hydroxyl ions (OH-) generated at the positive electrode react to generate water (H ₂ O) and generate heat of reaction at the same time. Hydrogen, the main fuel of a fuel cell, is supplied through a reformer, and hydrogen, a key fuel of a fuel cell, is a partial oxidation (POX) reaction, an auto-thermal reforming (ATR) reaction, and steam of methane. It is produced by a reforming reaction (Methane Steam Reforming), etc. This method is known that the steam reforming reaction is more hydrogen production and the reforming efficiency is higher than the two processes described above. However, steam reforming is slow to reach the equilibrium state of reaction, carbon monoxide (CO) which poisons the catalyst, and is a powerful endothermic reaction, so it needs to supply a lot of heat from the outside. Fuel cells have a variety of solid polymers (PEFC), phosphoric acid (PAFC), molten carbonate (MCFC), solid oxide (SOFC), etc., depending on the chemical composition of the stack that causes the chemical reaction between hydrogen and oxygen. There is a type of fuel cell.

The power generation efficiency of fuel cell is 40 ~ 60% which is much higher than that of general thermal power plant. By recovering the exhaust heat from the reaction process, the energy efficiency can be increased up to 80% and the combined heat power (CHP) power generation It is possible. In addition, various fuels such as LNG, liquefied petroleum gas (LPG), naphtha, kerosene, and coal gasification can be used, making it easy to secure energy resources, and do not burn fuel. Is one of.

C) Absorption Heat Pump System

As shown in FIG. 3, the absorption system, which is composed of four heat exchangers and is operated by a thermodynamic cycle, has a different calorie usage condition at each installation site when not in home use, and thus, the usage conditions are carefully examined, and then the absorption heat is obtained. The system must be designed and manufactured in consideration of the heat balance. At this time, the pressure of the generator, the absorber, the condenser, the evaporator constituting the absorption cycle, and the recovered water capacity of the cold part (evaporator) considering the temperature, the high temperature part (condenser) The heat balance of the heat source and the heat balance of the heat source and the flow rate and concentration of the refrigerant that can drive the absorption heat pump will determine whether the absorption system is applied.

Republic of Korea Patent No. 10-0114189, Name of the invention "carbon capture storage system and heat pump" European Patent 10192643.4, "Fossil fuel combustion thermal power system including carbon dioxide separation and capture unit"

Haibo Zhai, Edward S. Rubin, Peter L. Versteeg, "Water Use at Pulverized Coal Power Plants with Postcombustion Carbon Capture and Storage", Environmental Science & Technology, 2011, 45, 2479-2485 Baek, Lee Hyun, "CCS emerging as an alternative for low carbon green economy", Korea Gas Federation Forum, 2009 Quarterly Winter Issue Sang Do Park, "CO2 Capture and Storage Technology," Physics and Advanced Technology, 2009 June, 19-23 IPCC, “IPCC Special Report on Carbon Capture and Storage”, 2005

As shown in FIG. 4, the carbon capture technology using the conventional absorption method absorbs carbon dioxide into the absorber by reacting the absorbent and the mixed gas in an absorption tower, and then transfers the carbon dioxide to the stripper tower from the absorber. It consists of a process of separating carbon dioxide.

The regeneration tower separates the absorbent and carbon dioxide from the heat energy supplied from the pre-heater applied to the boiler of the plant. At this time, in order to supplement the thermal energy supplied to the regeneration tower, a reboiler (Re-Boiler) is additionally installed and operated as an auxiliary heat source.

In the regeneration tower as described above, the absorber and carbon dioxide are separated using heat energy, and the amount of heat energy required at this time is enormous, thereby lowering the energy efficiency of the plant and affecting heat balance, thereby reducing the production cost of the product. Is increased.

For example, if the capacity of the CO2 capture and storage system is large in the power plant, heat energy is insufficient to recover the exhaust heat and operate the regeneration tower. Therefore, additional turbine steam extraction steam is used to drive the regeneration tower. By using the turbine's extraction steam to drive the regeneration tower, the reduction of power generation capacity due to the decrease in turbine output and the overuse of the extraction steam affect the dynamic characteristics of the turbine, thus limiting the regeneration tower operating capacity.

The present invention is intended to solve the problem of energy efficiency reduction due to the limit of carbon capture capacity by the large amount of thermal energy required in the regeneration tower when carbon capture in power generation or industrial plants and energy use in the plant process.

In the present invention, in order to solve the problem of limiting the carbon capture capacity due to the large amount of thermal energy required in the regeneration tower when carbon capture in power generation or industrial plants and energy efficiency degradation due to energy use in the plant process (Exhaust Heat) and The absorption heat pump is driven by using a heat source discharged from a heat recovery system.

By using the steam heated by the absorption heat pump as a driving heat source of the regeneration tower for carbon capture, it operates a large-capacity CO2 capture storage system that does not affect the process of power generation or industrial plant. can do.

In the present invention, the capacity of the carbon capture storage system can be increased by driving a regeneration tower of a carbon capture storage system requiring enormous energy using a high temperature heat source generated from an exhaust heat and a heat recovery system. Early practical use can be achieved through economic improvement.

By doing so, the problem of global warming and climate change caused by the application of technology to capture carbon dioxide emitted from large-scale carbon dioxide sources such as power plants, steel, cement, refinery, etc. can be solved. In addition, it becomes possible to apply the technology of carbon capture storage system that can stably use sustainable fossil fuel until economic renewable energy is developed.

1 carbon dioxide capture system configuration
Energy conversion in the fuel cell (electric energy + heat energy)
3 is a schematic diagram of an absorption heat pump cycle
4 is a block diagram of a carbon dioxide capture storage system using a steam extraction steam turbine
5 is a block diagram of a carbon dioxide capture storage system using a fuel cell

As shown in FIG. 1 and FIG. 4, FIG. 1 shows a detailed process of the carbon capture system 130 (CCS) in the power plant process of FIG. 4 and FIG. The overall process is shown.

The carbon capture system of FIG. 1 is a process of absorbing carbon dioxide into an absorbent by reacting an absorbent and a mixed gas in an absorption tower (10: Absorption Tower), and then transferring the carbon dioxide to a regeneration tower (20: Stripper Tower) to separate carbon dioxide from the absorbent. Is done.

The regeneration tower separates the absorbent and carbon dioxide from the heat energy supplied from the pre-heater applied to the boiler of the power plant. In this case, in order to supplement the thermal energy supplied to the regeneration tower, a reboiler 70 is additionally installed and operated as an auxiliary heat source. In addition, when the capacity of the carbon capture system 130 (CCS) increases, there is a limit to the capacity of the reboiler (70: Re-Boiler), thereby supplying thermal energy to the regeneration tower using the extraction steam of the power plant turbine. .

As described above, in the regeneration tower, the absorber and carbon dioxide are separated using heat energy, and since the amount of heat energy required is enormous, it affects the heat balance by lowering the energy efficiency of the power plant or the industrial plant. Lowers the economics of a carbon capture system.

In order to solve this problem, as shown in FIG. 5, an absorption type heat pump driven by an array may be applied by using heat energy of an array heat exchanger of a flue gas emitted from the fuel cell power generation system 140. . As shown in Fig. 3, the absorption cycle for driving the absorption heat pump is composed of four basic elements. Basic elements for driving the absorption cycle include a regenerator (151), a condenser (152), an absorber (153), and an evaporator (154). As shown in Figure 3, the cycle is configured by adding a receiver (Receiver: 160), a solution heat exchanger (Solution Heat Exchanger), etc. to the cycle process as necessary. Looking at the progress of the absorption cycle, the solution circulates between the absorber (153) and the regenerator (151: Generator) where the refrigerant is absorbed at low pressure in the absorber and the refrigerant is desorbed at high pressure in the regenerator. ) As the strong solution leaves the absorber, it is preheated in the solution heat exchanger, enters the regenerator, and circulates between the regenerators (151: Generator) in the absorber where the refrigerant is absorbed at low pressure and in the regenerator at high pressure. Refrigerant is desorbed. As the strong solution leaves the absorber, it is preheated in the solution heat exchanger and enters the regenerator. The regenerator acts like a boiler for secondary heating by high temperature driving energy (steam, high temperature water), and the weak solution is returned to the absorber (153: Absorber) via a pressure reducing valve (162). Goes.

Meanwhile, another vapor (Vapour) is completely condensed in the condenser (152: Condenser) is passed through the receiver (Receiver: 160) is expanded in the expansion valve (161: Expansion Valve) and enters the evaporator 154. At this time, depending on the water content of the mixture evaporation is caused by the temperature gradient (Temperature Glide) and the temperature rises during the evaporation process. Absorption cycle ends as it enters absorber 153 as it passes through evaporator 154 and becomes a low proportion of liquid vapor. At this time, an important element of the cooling function is the evaporator 154, and the absorption cycle is operated by the driving heat source (hot water / steam) supplied to the regenerator.

Through the same process as described above, the exhaust heat from the fuel cell power generation system 140 has a one-step temperature rise at the regenerator 151 and recovers the low-temperature heat source at the evaporator 154 to increase the two-step temperature. Thermal energy is supplied to the regeneration tower 20 through the absorber 153. The heat energy supplied in this way may be operated by absorbing heat pump by the exhaust heat of the fuel cell to recover the low temperature heat source provided from the evaporator 154 to increase the thermal efficiency.

The present invention solves the heat balance problem by using the heat energy supplied from the fuel cell power generation system and the absorption type heat pump of an independent type without using the extraction steam in the process of the existing power plant or industrial plant. The capacity limitation of the carbon capture system can be solved by limiting the use of additional steam.

As described above, an embodiment of the present invention illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the scope of the present invention as long as they are obvious to those skilled in the art.

10: Absorption Tower
20: stripper tower
30: Cooler
40: Pre-heater
50: condenser
70: Re-Boiler
80: Heat Exchanger
100: Boiler
101: Turbine
102: generator
103: condenser
104: Cooling Tower
105: feed pump
106: Feedwater Heater
107 Deaereator
121: Selective Catalytic Reactor (SCR)
122: air pre-heater (APH)
123: Electrostatic Precipitator (ESP)
124: Flue Gas Desulphurization (FGD)
130: Carbon Dioxide Capture System
140: Fuel cell power generation system (Fuel Cell)
150: Absorption Heat Pump
151: Generator
152: condenser
153: Absorber
154: Evaporator

Claims (2)

As a system for collecting carbon dioxide by driving the absorption type heat pump 150 by the arrangement of the fuel cell power generation system 140.
It includes a fuel cell power generation system 140 for generating the high temperature heat source,
The absorption heat pump 150 includes a regenerator 151, an absorber 153, a condenser 152, and an evaporator 154.
The carbon dioxide capture system includes a regeneration tower 20,
The high temperature heat source is cooled to reflux while passing through a regenerator,
The supplied steam is heated while passing through the absorber and the condenser to supply thermal energy to the regeneration tower 20 of the carbon dioxide capture system.
The refrigerant of the absorption heat pump is a carbon dioxide collection and storage system using an absorption heat pump and a fuel cell, wherein the refrigerant is configured to circulate an absorber, a regenerator, a condenser and an evaporator.
In claim 1
Carbon dioxide capture storage system using an absorption heat pump and a fuel cell, comprising an absorption heat pump system driven by a lithium bromide refrigerant

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