CN103752142A - Solar aided carbon dioxide trapping integrated system - Google Patents

Abstract

The invention discloses an integrated system for solar energy-assisted carbon dioxide capture, which is mainly composed of three parts: a power generation subsystem, a carbon dioxide capture subsystem and a solar heat collection subsystem. The subsystems are mainly connected through the boiler feed water heater, reboiler and flue gas pretreatment device to form the whole integrated system. For the heat output end of the solar heat collection subsystem, by adopting different connection methods, the energy demand grades of the related components between the solar heat collection and power generation sub-system and the carbon dioxide capture subsystem are reasonably distributed and integrated to achieve The cascade utilization of energy can greatly reduce the energy consumption of extracting steam from the steam turbine in the power plant, and realize the dual effects of renewable energy utilization and carbon dioxide emission reduction in the power plant while maintaining the stability of the power plant, and effectively promote the integration of solar energy and flue gas capture in my country Large-scale application of technology.

Description

A solar-assisted carbon dioxide capture integrated system

technical field

The invention relates to a medium and low temperature solar energy assisted carbon dioxide capture integration technology, specifically relates to the integration of a medium and low temperature solar heat collection system and a carbon dioxide capture system in flue gas, using solar energy to provide energy compensation for the carbon dioxide capture system, and realizing cascaded utilization of solar energy At the same time, it effectively reduces the efficiency drop of the power plant due to steam extraction.

Background technique

In the current chemical absorption capture system, a large amount of power plant steam is consumed during solution regeneration, which causes a decrease in power plant efficiency and increases the cost of capture, which has become the main factor restricting the large-scale application of _CO2 capture technology.

For the capture of CO ₂ in the flue gas of existing power plants, the technical solution of post-combustion carbon capture is widely recognized, and the ethanolamine (MEA) method is a relatively mature commercial method among them, which has the potential for large-scale application. However, the regeneration process in the desorption tower often requires heat energy at a temperature of 100-120°C, and at the same time, the energy consumption of the reboiler reaches 3-4GJ/ton CO ₂ . Conventional power plants usually use gas turbine extraction as a heat source to meet the energy consumption requirements of the regeneration process, resulting in a 15-30% drop in power generation efficiency. Therefore, the energy consumption corresponding to the process (the heat energy required by the reboiler, the electric energy required by the lean-rich liquid circulation pump, etc.) and the resulting high capture cost have become the biggest resistance factors to the promotion of the MEA method.

As a renewable clean energy, solar energy has great potential for development and utilization. Combining solar energy with the existing carbon dioxide capture system, using solar energy to generate heat at the temperature required for desorption of the capture system for desorption, can greatly reduce the energy consumption of steam extraction from the steam turbine in the power plant, and achieve The dual effects of renewable energy and carbon dioxide emission reduction in power plants have strongly promoted the large-scale application of integrated solar energy and flue gas capture technology in my country.

Contents of the invention

Aiming at the high energy consumption problem caused by the current capture system, the present invention proposes a solar-assisted carbon dioxide capture integrated system, which can make full use of medium and low temperature solar heat collection to compensate the energy consumption of the traditional capture system according to different integration connection relationships Demand, while realizing cascade utilization of solar energy, effectively reduce the efficiency drop caused by steam extraction in power plants.

In order to effectively solve the above technical problems, the present invention provides a solar-assisted carbon dioxide capture integrated system, including a power generation sub-system, a carbon dioxide capture sub-system, and a solar thermal collection sub-system; A steam power generation system composed of boilers, steam turbines and exhaust steam condensers in series; the carbon dioxide capture subsystem includes flue gas pretreatment devices, absorption towers, rich liquid pumps, lean liquid condensers, lean/rich liquid heat exchangers, lean Liquid pump, desorption tower, gas-liquid separator and reboiler; the exhaust port of the boiler is connected to the inlet of the flue gas pretreatment device, and the outlet of the flue gas pretreatment device is connected to the gas inlet of the lower part of the absorption tower The outlet of the lean liquid condenser is connected with the upper liquid spray inlet of the absorption tower; the lean/rich liquid heat exchanger is respectively connected with the outlet of the lean liquid pump and the rich liquid spray at the top of the desorption tower The drenching inlet, the outlet of the rich liquid pump and the inlet of the lean liquid condenser are connected; the inlet at the bottom of the desorption tower is connected with the outlet of the reboiler and the inlet of the lean liquid pump respectively, and the desorption The gas outlet at the top of the tower is connected to the bottom of the gas-liquid separator as the reflux of the condensate; the steam extraction port of the steam turbine is connected to the high temperature side inlet of the reboiler, and the high temperature side outlet of the reboiler It is connected with the exhaust steam condenser; a steam extraction valve is arranged on the connecting pipeline between the steam turbine and the reboiler; the solar heat collection subsystem is composed of a series of solar heat collectors and a working medium pump in series,

The present invention provides two integration methods according to the heat collection temperature range of solar energy, that is, the connection relationship between the heat output end of the solar heat collection subsystem and the reboiler includes one of the following two situations: one Yes: the outlet port of the working medium in the solar heat collection subsystem is connected to the high-temperature side inlet of the feedwater heat exchanger, and the high-temperature side outlet of the feedwater heat exchanger is connected to the high-temperature side inlet of the reboiler, The outlet on the high temperature side of the reboiler is connected to the inlet port of the working medium of the solar heat collection subsystem; this connection can collect heat from the solar heat collection subsystem to a medium-high temperature of about 200-350°C, and through heat exchange The feed water temperature of the power plant is heated by the boiler, and after the heat exchange, the heat exchange is continued through the reboiler to provide the heat of the reboiler, and the insufficient part of the heat required by the reboiler is provided by extracting the low-temperature and low-pressure steam of the steam turbine, thus forming The solar heating cycle realizes the cascade utilization of energy grades and reduces the irreversible loss of the system; the other is: the outlet end of the working fluid of the solar heat collection subsystem is connected to the high temperature side inlet end of the reboiler, and the The outlet on the high temperature side of the reboiler is connected to the inlet port of the working medium of the solar heat collection subsystem, and this connection can directly use the solar heat collection subsystem to collect heat from the working medium fluid in the solar heat collector series to reboil The temperature range required by the reboiler is used by the reboiler. While simplifying the system, it also makes full use of the high heat collection efficiency of the solar heat collection system at low temperatures, and reduces the heat dissipation loss of the working fluid at high temperatures. Both of the above two connection methods are designed with connecting pipelines for extracting steam from the steam turbine, so that the extracted steam can be used to provide heat when the solar energy is insufficient.

In the present invention, after the combustion of the boiler in the power generation system, a large amount of flue gas with a certain concentration will be produced, and the flue gas will enter the absorption tower from the bottom of the tower after being processed by the pretreatment device, and contact with the chemical absorption liquid sprayed on the top of the tower to absorb the flue gas. The carbon dioxide in the gas forms rich liquid, and the rich liquid is sprayed from the top of the tower to the desorption tower for regeneration after heat exchange between the rich liquid pump and the lean/rich liquid heat exchanger. At the same time, the reboiler provides the heat required for desorption, and the desorption The carbon dioxide is condensed and returned to the desorption tower through the gas-liquid separator, and the separated carbon dioxide is compressed and stored. The lean liquid after desorbing carbon dioxide passes through the lean liquid pump, lean/rich liquid heat exchanger and lean liquid condenser, and then sprays to the absorption tower again to form the entire absorption and desorption cycle.

Compared with prior art, the beneficial effect of the present invention is:

(1) Combining the medium and low temperature solar heat collection with the _CO2 capture system can make full use of the high heat collection efficiency of the medium and low temperature solar heat collection system in the temperature range of capture and regeneration, so as to reduce the loss caused by the extraction of high-grade energy by traditional power plants The reduction of capture efficiency improves the overall efficiency of the system.

(2) Directly use low-grade heat energy to meet the energy demand of the reboiler, realize the docking of energy grades, and avoid the irreversible loss caused by the traditional capture method using a large amount of steam after cooling and decompression, resulting in waste of high-grade energy.

(3) It reduces the adverse effect on the steam turbine caused by a large amount of steam extraction and regeneration in the traditional original system in the prior art.

(4) Solar heat collection can be well adapted to the operation mode of the power plant. During the peak power consumption during the day, the solar energy can be fully used to realize the energy supply of the capture system. The steam provides heat to keep the power plant running smoothly.

Description of drawings

Fig. 1 is the system principle diagram and structural diagram of Embodiment 1 of the solar energy-assisted carbon dioxide capture integrated system of the present invention;

Fig. 2 is the system schematic diagram and structural diagram of Embodiment 2 of the solar-assisted carbon dioxide capture integrated system of the present invention.

In the figure: 1-power generation subsystem, 2-carbon dioxide capture subsystem, 3-solar heat collection subsystem, 4-feed water heat exchanger, 5-boiler, 6-steam turbine, 7-exhaust steam condenser, 8-flue gas Gas pretreatment device, 9-absorption tower, 10-rich liquid pump, 11-lean liquid condenser, 12-lean/rich liquid heat exchanger, 13-lean liquid pump, 14-desorption tower, 15-gas-liquid separator , 16-reboiler, 17-collector series, 18-working fluid pump, 19-extraction valve.

Detailed ways

The present invention will be further described in detail below in combination with specific embodiments.

A solar-assisted carbon dioxide capture integrated system of the present invention, as shown in FIG. 1 and FIG. 2 , includes a power generation subsystem 1 , a carbon dioxide capture subsystem 2 and a solar heat collection subsystem 3 .

The power generation sub-system 1 is a steam power generation system composed of a feed water heat exchanger 4 , a boiler 5 , a steam turbine 6 and a exhaust steam condenser 7 connected in series.

The carbon dioxide capture subsystem 2 includes a flue gas pretreatment device 8, an absorption tower 9, a rich liquid pump 10, a lean liquid condenser 11, a lean/rich liquid heat exchanger 12, a lean liquid pump 13, a desorption tower 14, a gas A liquid separator 15 and a reboiler 16; the exhaust port of the boiler 3 is connected to the inlet of the flue gas pretreatment device 8, and the outlet of the flue gas pretreatment device 8 is connected to the gas inlet at the bottom of the absorption tower 9, The flue gas after the desulfurization and denitrification of the pretreatment device 8 enters the tower from the bottom of the absorption tower 9 to capture carbon dioxide; the outlet of the lean liquid condenser 11 is connected to the upper liquid spray inlet of the absorption tower 9; The lean/rich liquid heat exchanger 12 is respectively connected to the outlet of the lean liquid pump 13, the rich liquid spray inlet on the upper part of the desorption tower 14, the outlet of the rich liquid pump 10 and the inlet of the lean liquid condenser 11 connected; the inlet at the bottom of the desorption tower 14 is connected to the outlet of the reboiler 16 and the inlet of the lean liquid pump 13 respectively, and the gas outlet at the top of the desorption tower 14 is connected to the gas-liquid separator 15 Bottom, as reflux of condensate. The steam turbine 6 in the power generation sub-system 1 draws extraction steam from it according to the needs of the capture temperature. Therefore, the steam extraction port of the steam turbine 6 is connected to the high-temperature side inlet of the reboiler 16, and the high-temperature side inlet of the reboiler 16 The side outlet is connected to the exhaust steam condenser 7 to maintain water balance in the power generation sub-system; a steam extraction valve 19 is provided on the connecting pipeline between the steam turbine 6 and the reboiler 16 .

The solar heat collection subsystem 3 is composed of a series of solar heat collectors 17 and a working fluid pump 18 connected in series.

In the present invention, depending on the heat collection temperature designed by the solar heat collection subsystem 1, there are two connection relationships between the solar heat collection subsystem 3, the power generation subsystem 1 and the carbon dioxide capture subsystem 2.

Example 1:

When the heat collection temperature of the solar heat collection subsystem 3 is medium temperature, its connection relationship is: as shown in Figure 1, the outlet end of the working fluid in the solar heat collection subsystem 3 exchanges heat with the feed water in the power generation subsystem 1 The high temperature side inlet of the heat exchanger 4 is connected, and the medium and high temperature solar heat collection heating is used to replace the extraction type feed water heating, and the high temperature side outlet of the feed water heat exchanger 4 is connected with the reboiler 16 in the carbon dioxide capture system 2 The high temperature side inlet is connected, and the high temperature side outlet of the reboiler 16 is connected with the working fluid inlet port of the solar heat collection subsystem 3, thus forming a solar heat collection cycle. The connection method in Example 1 can collect heat from the solar heat collection subsystem to a medium-high temperature of about 200-350°C, heat the feed water temperature of the power plant through a heat exchanger, and continue heat exchange through a reboiler after heat exchange to provide re-heating. The heat of the boiler, and the insufficient part of the heat required by the reboiler is provided by extracting the low-temperature and low-pressure steam of the steam turbine, which constitutes a solar heating cycle, realizes the cascade utilization of energy grades, and reduces the irreversible loss of the system.

Example 2:

The outlet end of the working fluid of the solar heat collection subsystem 3 is connected to the high temperature side inlet port of the reboiler 16 in the carbon dioxide capture subsystem 2, and the high temperature side outlet of the reboiler 16 is connected to the solar collector The working fluid inlets of the thermal subsystem 3 are connected to form a solar heat collection cycle. The connection method of embodiment 2 can directly use the solar heat collection subsystem to collect heat from the working medium fluid in the solar heat collector series to the temperature range required by the reboiler and supply it to the reboiler, which can make full use of the system while simplifying the system. It improves the high heat collection efficiency of the solar heat collection system at low temperature, and reduces the heat dissipation loss of the working medium fluid at high temperature.

To sum up, by adopting different connection methods for the heat output end of the solar heat collection subsystem, the energy demand level of the related components between the solar heat collection and power generation subsystem and the carbon dioxide capture subsystem is reasonably allocated and adjusted. The integration realizes the cascade utilization of energy, which can greatly reduce the energy consumption of extracting steam from the steam turbine in the power plant, and realize the dual effects of renewable energy utilization and carbon dioxide emission reduction in the power plant while maintaining the stability of the power plant. Large-scale application of capture integration technology.

During the working process of the solar energy-assisted carbon dioxide capture integrated system of the present invention, the heat demand of the reboiler 16 is jointly completed by the solar energy and the steam extraction of the steam turbine 6, and the steam extraction valve 19 is closed when the heat provided by the solar energy to the reboiler 16 is sufficient, completely The desorption energy consumption of the capture system is provided by solar energy, and the steam extraction valve 19 is opened when the solar energy is insufficient, and the heat demand of the reboiler is provided by the solar energy and the extraction steam of the steam turbine at the same time.

The power generation sub-system described in the present invention is similar to the traditional power generation system, except that a feed water heat exchanger 4 using solar energy is added on the basis of the traditional power plant, which can switch between using solar energy and not using solar energy to heat the boiler feed water, while introducing Reboiler extraction cycle pipeline, add valves to control.

The carbon dioxide capture subsystem 2 described in the present invention is mainly suitable for the aqueous solution of chemical absorbents based on alcohol amine substances, that is, it can be an absorption solution made of a single chemical absorbent, or it can be a mixture of multiple chemical absorbents. than the composition of the mixed absorbent. The adsorbent used in the present invention belongs to the mature technology in this field, and its formula and preparation process will not be repeated here.

The selected form of the collector series 17 in the solar heat collection subsystem 3 can be a compound parabolic concentrator (CPC), a trough collector, a Fresnel collector, a dish collector, and a tower heat collectors etc.

The circulating fluid in the solar heat collection subsystem 3 generally uses high-temperature heat transfer oil as the heat transfer medium. In addition, molten salt or water can also be used as the heat transfer medium. When the heat transfer oil is used as the medium to connect to the reboiler, it needs to pass through a first stage. heat exchange, and when water is used as the heat exchange medium, it only needs to be directly connected to the reboiler.

Although the present invention has been described above in conjunction with the drawings, the present invention is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative, rather than restrictive. Under the inspiration, many modifications can be made without departing from the gist of the present invention, and these all belong to the protection of the present invention.

Claims (4)

1. the auxiliary collecting carbonic anhydride integrated system of solar energy, comprises power generation sub-system (1), collecting carbonic anhydride subsystem (2), solar energy heating subsystem (3); Gas is characterised in that:

Described power generation sub-system (1) is served as reasons to water-to-water heat exchanger (4), boiler (5), steam turbine (6) and exhaust steam condenser (7) steam generating system in series;

Described collecting carbonic anhydride subsystem (2) comprises Flue Gas Pretreatment Device (8), absorption tower (9), rich solution pump (10), lean solution condenser (11), lean/rich liquid heat exchanger (12), lean pump (13), desorber (14), gas-liquid separator (15) and reboiler (16);

The exhaust opening of described boiler (3) is connected with the entrance of described Flue Gas Pretreatment Device (8), and the outlet of described Flue Gas Pretreatment Device (8) connects the gas access of bottom, absorption tower (9);

The outlet of described lean solution condenser (11) is connected with the upper liquid spray inlet of described absorption tower (9);

Described lean/rich liquid heat exchanger (12) is connected with rich solution spray inlet, the outlet of described rich solution pump (10) and the entrance of described lean solution condenser (11) on the outlet of described lean pump (13), described desorber (14) top respectively;

The entrance of described desorber (14) bottom is connected with the outlet of described reboiler (16) and the entrance of described lean pump (13) respectively, the gas vent at described desorber (14) top is connected to the bottom of described gas-liquid separator (15), as the backflow of condensate liquid;

The extraction opening of described steam turbine (6) is connected with the high temperature side entrance of described reboiler (16), and the high temperature side outlet of described reboiler (16) is connected with described exhaust steam condenser (7);

Connecting line between described steam turbine (6) and described reboiler (16) is provided with the valve that draws gas (19);

Described solar energy heating subsystem (3) is composed in series by solar thermal collector series (17) and working medium pump (18), annexation between the heat output of described solar energy heating subsystem (3) and described reboiler (16) comprises one of following two kinds of situations: one is: the sender property outlet end in described solar energy heating subsystem (3) is connected with the described high temperature side entrance of giving water-to-water heat exchanger (4), described high temperature side outlet of giving water-to-water heat exchanger (4) is connected with the high temperature side entrance of described reboiler (16), the high temperature side outlet of described reboiler (16) is connected with the working medium arrival end of described solar energy heating subsystem (3), another kind is: the sender property outlet end of described solar energy heating subsystem (3) is connected with the high temperature side arrival end of described reboiler (16), and the high temperature side outlet of described reboiler (16) is connected with the working medium arrival end of described solar energy heating subsystem (3).

2. the auxiliary collecting carbonic anhydride integrated system of solar energy according to claim 1, it is characterized in that, absorbent in described collecting carbonic anhydride subsystem is take alcamines material as the basic chemical absorbent aqueous solution, and described absorbent is the absorbent solution that singly kind chemical absorbing material is made into or the composite absorber being comprised of number of chemical absorbing material proportioning.

3. the auxiliary collecting carbonic anhydride integrated system of solar energy according to claim 1, it is characterized in that, described solar thermal collector series is a kind of or several combination in compound parabolic concentrating collector, groove type heat collector, Fresnel heat collector, dish formula heat collector and tower-type heat collector.

4. the auxiliary collecting carbonic anhydride integrated system of solar energy according to claim 1, is characterized in that, the heat transfer medium of described solar energy heating subsystem is selected the one in conduction oil, fuse salt and water.

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