CN209093018U - A low-energy carbon dioxide capture and storage system - Google Patents

Abstract

The utility model relates to a kind of low energy consumption collecting carbonic anhydride and seal system up for safekeeping, the high temperature flue gas that coal-burning power plant generates becomes low-temperature flue gas after passing first into heat recovering heat exchanger release high-temperature residual heat, enter compressor set after carrying out desulphurization denitration processing later, compressed flue gas is cooled down by intercooled regeneration device, liquid carbon dioxide therein is separated subsequently into gas-liquid separation device, high pressure gas after carbon dioxide removal sequentially enters the cold side of expansion unit acting and intercooled regeneration devices at different levels, gas after expansion working finally recycles heat using heat recovering heat exchanger, chimney is transported to after reaching exhaust temperature, it is discharged into atmosphere.The utility model combines flue gas compressor with expansion work recycling, the recycling of regenerator waste heat, saves power consumption to the maximum extent, by combining with energy storage, hold over system, plays the function of peak regulation of power plant, reduce unit initial cost cost；Cold source needed for the system can also provide low temperature carbon dioxide removal is improved efficiency with reducing power consumption.

Description

A low-energy carbon dioxide capture and storage system

technical field

The utility model belongs to the technical field of carbon dioxide capture from coal-fired power plant flue gas and power plant energy saving and consumption reduction, and relates to a carbon dioxide capture and storage system, more particularly, to a flue gas carbon dioxide capture and storage system.

Background technique

Existing carbon capture and storage methods are mainly divided into: pre-combustion capture, oxy-combustion capture and post-combustion capture. Pre-combustion capture technology is a carbon capture method that separates carbon dioxide from high-carbon fossil fuels before combustion. Typical systems such as integrated coal gasification combined cycle, the process of separating carbon dioxide is mainly divided into two steps: 1) High-carbon fossil energy It is converted into hydrogen and carbon dioxide in an environment with sufficient oxygen; 2) The hydrogen and carbon dioxide are separated, and hydrogen is used as fuel, and the obtained product is mainly water, which is clean and pollution-free. However, this clean and non-polluting pre-combustion carbon capture method has too large initial investment, too complicated process and low technical reliability, which limits its large-scale industrial application.

The main method of oxygen-enriched combustion and capture is to separate nitrogen in the air to form an oxygen-enriched combustion environment. When high-carbon fossil energy is fully burned in such an environment, the generated tail gas is mainly carbon dioxide, which is then stored. Although the process of oxy-fuel combustion and capture technology is simple, the production of pure oxygen environment in oxy-fuel combustion and capture technology is very difficult, and the investment in this process is relatively large, which limits its application.

Post-combustion capture technology is a carbon capture method that directly captures carbon dioxide at the flue gas outlet of traditional large-scale coal-fired power plants for storage and utilization. Because post-combustion capture technology has less retrofit to large coal-fired power plants, it is recognized as the most likely carbon capture method for commercial application. However, the high energy consumption of post-combustion capture technology limits its commercial application. Therefore, how to reduce the decarbonization energy consumption of post-combustion capture technology has become the focus of research at home and abroad.

At present, a variety of post-combustion capture methods have been proposed at home and abroad: hydrate separation technology (such as Chinese patent application CN201710252686.7, etc.), physical absorption method (such as Chinese patent application CN201110140000.8, etc.), chemical absorption method (such as Chinese patent application Application CN201711360255.9, etc.), membrane separation technology (such as Chinese patent application CN201810108522.1, etc.), low-temperature separation technology (such as Chinese patent application CN201810037835.2, etc.), photocatalytic reduction of carbon dioxide (such as Chinese patent application CN201620778801.5, etc.), etc. . The working principle of low temperature separation technology is to cool and compress the mixed gas, and then to achieve the effect of gas separation through distillation. However, due to the reduction of carbon dioxide content in the tail gas of large coal-fired power plants, the existing low-temperature separation technology has relatively low efficiency, high investment and energy consumption, and cannot be used in carbon capture systems of large coal-fired power plants.

Utility model content

Aiming at the shortcomings and deficiencies of the existing post-combustion carbon dioxide capture technology, such as high energy consumption, low efficiency, and large investment, the utility model aims to provide a flue gas carbon dioxide capture and storage system, which is based on high pressure The principle of liquefaction and separation combines flue gas compression with expansion power recovery and regenerator waste heat recovery to maximize power savings; at the same time, combined with energy storage and heat storage systems, it functions as a power plant for peak regulation, achieving One investment for multiple uses reduces the initial investment cost per unit; in addition, the system can also provide the cold source required for low-temperature carbon dioxide removal, further reducing power consumption and improving efficiency.

The technical scheme adopted by the utility model for solving its technical problems is:

A low-energy-consumption carbon dioxide capture and storage system, comprising a heat recovery heat exchanger, a desulfurization and denitrification tower, a compressor unit, an expansion unit, a gas-liquid separation device and a chimney,

in,

The compressor group includes several stages of compressors, and the discharge ports and the air inlets of the adjacent two-stage compressors are connected by pipelines, and the discharge pipelines of each stage of compressors are provided with one-stage intercooling and heat recovery. The exhaust gas of the compressors of each stage releases heat after passing through the hot side of the intercooling regenerator of the corresponding stage,

The expansion unit includes several stages of expanders, and the exhaust ports and the air inlets of the adjacent two-stage expanders are connected by pipelines, and the exhaust pipelines of each stage of the expanders pass through a corresponding intercooler. The cold side of the regenerator then communicates with its downstream components,

It is characterized in that,

The hot side inlet of the heat recovery heat exchanger is passed into the medium and high temperature flue gas,

The hot side outlet of the heat recovery heat exchanger is communicated with the low temperature flue gas inlet of the desulfurization and denitrification tower through a pipeline,

The flue gas outlet of the desulfurization and denitrification tower is communicated with the air inlet of the first-stage compressor through a pipeline, and the exhaust port of the first-stage compressor is connected to the next stage after passing through the hot side of the first-stage intercooling regenerator. The air inlet of the compressor is connected,

The exhaust port of the last stage compressor is communicated with the inlet of the gas-liquid separation device through the hot side of the last stage intercooling regenerator, and the normal temperature and high pressure gas-liquid mixture entering the gas-liquid separation device is separated into Liquid carbon dioxide and high-pressure gas for removing carbon dioxide, the liquid discharge port of the gas-liquid separation device is communicated with a carbon dioxide storage tank,

The high-pressure gas outlet of the gas-liquid separation device is communicated with the air inlet of the first-stage expander, and the exhaust port of the first-stage expander is connected to the next-stage expander after passing through the cold side of the last-stage intercooling regenerator. connected to the air intake,

The exhaust port of the last stage expander passes through the cold side of the first intercooling regenerator or after passing through the cold side of the first intercooling regenerator and the cold side of the heat recovery heat exchanger, and then passes through the cold side of the first intercooling regenerator. The chimney is connected.

The low-energy-consumption carbon dioxide capture and storage system of the utility model works as follows: the medium-high temperature flue gas generated by the coal-fired power plant is first introduced into the hot side of the heat recovery heat exchanger, and the high-temperature waste heat is released to the heat recovery and heat exchanger. After the heater, it becomes low-temperature flue gas, which is then passed into the desulfurization and denitrification tower for desulfurization and denitrification treatment. Intercooling until the carbon dioxide becomes a liquid at room temperature, and then enters the gas-liquid separation device, the separated liquid carbon dioxide is recovered and stored, and the high-pressure gas after carbon dioxide removal enters the cold side of the intercooling regenerator and the expander in turn. After doing work, the gas after expansion and work finally passes through the heat recovery heat exchanger before the desulfurization and denitrification tower to recover the heat of the flue gas, and after reaching the discharge temperature, it is transported to the chimney and discharged to the atmosphere.

Preferably, a dryer is provided on the flue gas outlet pipeline of the desulfurization and denitrification tower, and the dryer is used for drying the flue gas discharged from the desulfurization and denitrification tower.

Preferably, each stage compressor is drivingly connected with the first stage expander, and each stage compressor includes a drive motor. The expander is connected with the compressor, and the work done by the expander is used to assist the drive of the compressor, which can reduce the power consumption of the drive motor.

Preferably, the gas-liquid separation device is a gas-liquid separator or a fractionation tower.

Preferably, a fan is provided on the air intake pipeline of the chimney.

Preferably, a compressed gas storage tank is arranged on the communication pipeline between the high-pressure gas outlet of the gas-liquid separation device and the air inlet of the first-stage expander, and each of the intercooling regenerators is a regenerative intercooler. device. The high-pressure gas from which carbon dioxide has been removed can be temporarily stored in the compressed gas storage tank to form an energy storage system. When the power is surplus at night, the flue gas is compressed by the driving motor, and the high-pressure gas is stored, and the high-pressure gas is released during the day to drive the expander to replace the The drive motor compresses the flue gas, or is used to drive other power and power generation equipment to play a role in peak regulation. For a system with a compressed gas storage tank, the cold air cannot be supplied at any time after expansion. The intercooling regenerators at all levels can use a regenerative intercooler, which releases heat during compression and takes heat during expansion, which is not limited by time difference.

Preferably, a water-cooled heat exchanger is arranged on the inlet pipeline of the gas-liquid separation device, and the exhaust port of the last-stage expander communicates with the flue gas discharge tower after passing through the cold side of the first-stage intercooling regenerator. , the cold side of the heat recovery heat exchanger is communicated with an absorption chiller, and the cold water generated by the absorption chiller is passed into the cold side of the water-cooled heat exchanger. For natural gas boilers, boilers operating in summer, etc., the flue gas can be discharged at a low temperature, so it is not necessary to reheat heating before discharge. At this time, the medium and high temperature flue gas waste heat before the desulfurization and denitrification tower can be used to drive the absorption chiller. After entering the water-cooled heat exchanger, it is used to further cool the high-pressure flue gas passed into the gas-liquid separation device, so as to improve the carbon dioxide capture effect. The high-pressure gas separated by the gas-liquid separation device can be heated by the heat exhausted from the absorption chiller, so as to further improve the expansion performance.

Compared with the prior art, the low-energy-consumption carbon dioxide capture and storage system of the present invention has significant technical effects: (1) the system can combine flue gas compression with expansion work recovery and regenerator waste heat recovery to maximize (2) The system can also be combined with energy storage and thermal storage systems to play the function of peak regulation of power plants, achieving multiple uses for one investment, and reducing the initial investment cost of the unit; (3) The system can also provide low temperature The cold source required to remove carbon dioxide further reduces power consumption and improves efficiency.

Description of drawings

1 is a schematic diagram of Embodiment 1 of the low-energy-consumption carbon dioxide capture and storage system of the present invention;

2 is a schematic diagram of Embodiment 2 of the low-energy-consumption carbon dioxide capture and storage system of the present invention;

3 is a schematic diagram of Embodiment 3 of the low-energy-consumption carbon dioxide capture and storage system of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below with reference to the accompanying drawings and examples.

Example 1

FIG. 1 is a schematic diagram of Example 1. FIG. As shown in Figure 1, the low-energy-consumption carbon dioxide capture and storage system of the present invention includes a heat recovery heat exchanger 1, a desulfurization and denitrification tower 2, a dryer 3, a compressor unit, an expansion unit, an interstage cooling regenerator 61, 62. Gas-liquid separation device 7, chimney 8, drive motors 91, 92, fan 10. The compressor unit includes two-stage compressors 41 and 42. The exhaust ports and the intake ports of adjacent two-stage compressors 41 and 42 are connected through pipelines, and the exhaust pipes of each stage of compressors 41 and 42 are connected by pipelines. There are one-stage intercooling regenerators 61 and 62 on the roads. The exhaust gas from the compressors 41 and 42 of each stage passes through the hot side of the corresponding stage's intercooling regenerators 61 and 62 to release heat. The expansion unit includes two-stage expanders. 51, 52, the exhaust ports and the air inlets of the adjacent two-stage expanders 51, 52 are connected through pipelines, and the exhaust pipelines of each stage expander 51, 52 are reheated through a corresponding indirect cooling The cold sides of the devices 62, 61 are then communicated with their downstream components. Each stage of the compressors 41 and 42 is drivingly connected with the first stage of the expanders 52 and 51 , and each stage of the compressors 41 and 42 includes a drive motor 91 and 92 . The expander is connected with the compressor, and the work done by the expander is used to assist the drive of the compressor, which can reduce the power consumption of the drive motor.

The hot side inlet of the heat recovery heat exchanger 1 is passed into the medium and high temperature flue gas, and the hot side outlet of the heat recovery heat exchanger 1 is connected to the low temperature flue gas inlet of the desulfurization and denitrification tower 2 through a pipeline, and the flue gas outlet of the desulfurization and denitrification tower 2 is connected. After passing through the dryer 3, it is communicated with the air inlet of the first-stage compressor 41, and the dryer 3 is used for drying the flue gas discharged from the desulfurization and denitrification tower 2. The exhaust port of the first-stage compressor 41 is communicated with the intake port of the next-stage compressor 42 after passing through the hot side of the first-stage intercooling regenerator 61, and the exhaust port of the last-stage compressor 42 passes through the last stage. The hot side of the interstage cooling regenerator 62 is communicated with the inlet of the gas-liquid separation device 7. The gas-liquid separation device 7 is a gas-liquid separator or a fractionation tower, and the normal temperature and high pressure gas-liquid mixture entering the gas-liquid separation device 7 is separated. It is liquid carbon dioxide and high-pressure gas for removing carbon dioxide, the liquid outlet of the gas-liquid separation device 7 is communicated with a carbon dioxide storage tank, the high-pressure gas outlet of the gas-liquid separation device 7 is communicated with the air inlet of the first-stage expander 51, The exhaust port of the first-stage expander 51 communicates with the air inlet of the next-stage expander 52 after passing through the cold side of the last-stage intercooling regenerator 62, and the exhaust port of the last-stage expander 52 passes through the first-stage expander 52. After the cold side of the intercooling regenerator 61 or after passing through the cold side of the first-stage intercooling regenerator 61 and the cold side of the heat recovery heat exchanger 1, it is communicated with the chimney 8, and a fan is provided on the air intake line of the chimney 8. 10.

In the flue gas carbon dioxide capture and storage system of the present invention, during operation, the medium and high temperature flue gas generated by the coal-fired power plant is first introduced into the hot side of the heat recovery heat exchanger 1, and the high temperature waste heat is released to the heat recovery heat exchanger 1. The flue gas becomes low-temperature flue gas, and then passes into the desulfurization and denitrification tower 2 for desulfurization and denitrification treatment. After the temperature drops to about 60 °C, it enters the compressor. After compression, it is cooled by the intercooling regenerator. Let carbon dioxide become liquid at normal temperature, and then enter the gas-liquid separation device 7, the separated liquid carbon dioxide is recovered and stored, and the high-pressure gas after removing carbon dioxide enters the cold side and the expander of the intercooling regenerators 62 and 61 of each stage in turn. After doing work, the gas after expansion work finally passes through the heat recovery heat exchanger 1 in front of the desulfurization and denitrification tower 2 to recover the heat of the flue gas, and after reaching the discharge temperature, it is transported to the chimney 8 and discharged to the atmosphere.

Example 2

FIG. 2 is a schematic diagram of Example 2. FIG. The difference from Embodiment 1 is that a compressed gas storage tank 11 is provided on the communication pipeline between the high-pressure gas outlet of the gas-liquid separation device 7 and the air inlet of the first-stage expander 51, and each intercooling regenerator 61, 62 is a regenerative intercooler. The high-pressure gas from which carbon dioxide has been removed can be temporarily stored in the compressed gas storage tank 11 to form an energy storage system. When there is excess power at night, the driving motor is used to compress the flue gas and store the high-pressure gas. During the day, the high-pressure gas is released to drive the expander, which is used to replace the drive The motor compresses the flue gas, or is used to drive other power and power generation equipment to play a role in peak regulation. For a system with a compressed gas storage tank, the cold air cannot be supplied at any time after expansion. The intercooling regenerators 61 and 62 of each level can use regenerative intercoolers, which release heat during compression and take heat during expansion, which is not limited by the time difference. .

Example 3

FIG. 3 is a schematic diagram of Example 3. FIG. Different from Embodiment 1, a water-cooled heat exchanger 12 is provided on the inlet pipeline of the gas-liquid separation device 7, and the exhaust port of the last stage expander 52 passes through the cold side of the first-stage intercooling regenerator 61 and is The flue gas discharge tower 8 is communicated, and the cold side of the heat recovery heat exchanger 1 is communicated with an absorption chiller 13 , and the cold water generated by the absorption chiller 13 passes into the cold side of the water-cooled heat exchanger 12 . For natural gas boilers, boilers operating in summer, etc., the flue gas can be discharged at a low temperature, so it is not necessary to reheat heating before discharge. At this time, the medium and high temperature flue gas waste heat before the desulfurization and denitrification tower can be used to drive the absorption chiller. After entering the water-cooled heat exchanger 12, it is used to further cool the high-pressure flue gas passed into the gas-liquid separation device 7, so as to improve the carbon dioxide capture effect. The high-pressure gas separated by the gas-liquid separation device 7 can be heated by the exhaust heat of the absorption chiller, so as to further improve the expansion performance.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall include within the scope of the present invention.

Claims (7)

1. A low-energy-consumption carbon dioxide capturing and sealing system comprises a heat recovery heat exchanger, a desulfurization and denitrification tower, a compressor unit, an expansion unit, a gas-liquid separation device and a chimney,

wherein,

the compressor unit comprises a plurality of stages of compressors, the exhaust ports and the air inlets of the adjacent two stages of compressors are communicated through pipelines, an exhaust pipeline of each stage of compressor is provided with an inter-stage cooling heat regenerator, the exhaust of each stage of compressor releases heat after passing through the hot side of the inter-stage cooling heat regenerator of the corresponding stage,

the expansion unit comprises a plurality of stages of expansion machines, the exhaust ports and the air inlets of the adjacent two stages of expansion machines are communicated through pipelines, the exhaust pipeline of each stage of expansion machine is communicated with the downstream components after passing through the cold side of the corresponding intercooling heat regenerator,

it is characterized in that the preparation method is characterized in that,

the hot side inlet of the heat recovery heat exchanger is filled with medium-high temperature flue gas, the hot side outlet of the heat recovery heat exchanger is communicated with the low-temperature flue gas inlet of the desulfurization and denitrification tower through a pipeline,

the flue gas outlet of the desulfurization and denitrification tower is communicated with the gas inlet of the first-stage compressor through a pipeline, the gas outlet of the first-stage compressor is communicated with the gas inlet of the next-stage compressor after passing through the hot side of the first-stage intercooling heat regenerator,

the exhaust port of the last stage compressor is communicated with the inlet of the gas-liquid separation device after passing through the hot side of the last stage cold regenerator, the normal-temperature high-pressure gas-liquid mixture entering the gas-liquid separation device is separated into liquid carbon dioxide and high-pressure gas without carbon dioxide, the liquid outlet of the gas-liquid separation device is communicated with a carbon dioxide sealing tank,

the high-pressure gas outlet of the gas-liquid separation device is communicated with the gas inlet of the first-stage expander, the gas outlet of the first-stage expander is communicated with the gas inlet of the next-stage expander after passing through the cold side of the last inter-stage cold regenerator,

and an exhaust port of the last stage of expansion machine is communicated with the chimney after passing through the cold side of the first interstage cold regenerator or the cold side of the first interstage cold regenerator and the cold side of the heat recovery heat exchanger.

2. The low-energy-consumption carbon dioxide capturing and sequestration system according to claim 1, wherein a dryer is arranged on the flue gas outlet pipeline of the desulfurization and denitrification tower, and the dryer is used for drying the flue gas discharged from the desulfurization and denitrification tower.

3. The low energy consumption carbon dioxide capture and sequestration system of claim 1 wherein each stage of compressor is drivingly connected to a stage of expander and each stage of compressor includes a drive motor.

4. The low energy carbon dioxide capture and sequestration system of claim 1 wherein the gas-liquid separation device is a gas-liquid separator or a fractionation column.

5. The low energy consumption carbon dioxide capture and sequestration system of claim 1, wherein a fan is disposed on the air intake conduit of the chimney.

6. The low energy consumption carbon dioxide capture and sequestration system of claim 1 wherein a compressed gas storage tank is provided on a communication line between the high pressure gas outlet of the gas-liquid separation device and the gas inlet of the first stage expander, and each of the intercooled regenerators is a regenerative intercooler.

7. The system for capturing and storing carbon dioxide with low energy consumption according to claim 1, wherein a water-cooled heat exchanger is arranged on an inlet pipeline of the gas-liquid separation device, an exhaust port of a final stage expander is communicated with the flue gas discharge tower after passing through a cold side of a first inter-stage cold regenerator, a cold side of the heat recovery heat exchanger is communicated with an absorption water chiller, and cold water generated by the absorption water chiller is introduced into the cold side of the water-cooled heat exchanger.