Disclosure of Invention
The invention provides a system and a method for absorbing carbon dioxide in a caustic soda solution in flue gas of a thermal power plant, which can reduce the carbon dioxide absorption cost, namely carbon capture cost.
In order to achieve the purpose, the thermal power plant flue gas caustic soda solution carbon dioxide absorption system comprises a carbon dioxide reaction absorption tower, a sodium hydroxide feeding system and a sodium bicarbonate solution supply pipeline, wherein the lower part of the carbon dioxide reaction absorption tower is provided with a flue gas inlet connected with a tower bottom gas conveying pipeline, and the upper part of the carbon dioxide reaction absorption tower is provided with a liquid inlet used for inputting a sodium hydroxide solution; the flue gas entry is connected to the clean flue gas connecting line of the boiler of thermal power plant, and the inlet passes through absorption liquid confession liquid pipeline and sodium hydroxide charge-in system and connects, and carbon dioxide reaction absorption tower passes through reaction liquid discharge line and solution holding vessel and connects.
Furthermore, a sodium hydroxide feeding system is connected with an electrolytic cell for preparing caustic soda by electrolyzing brine in a thermal power plant, and the electrolytic cell for preparing caustic soda by electrolyzing brine is powered by peak-adjusting frequency-adjusting surplus electric power of the thermal power plant.
Further, a hydrogen outlet of the electrolytic tank for preparing the caustic soda by electrolyzing the brine is sent to a boiler for afterburning or a steel cylinder for storage or is sent to an external pipeline through a pipeline, and a chlorine outlet of the electrolytic tank for preparing the caustic soda by electrolyzing the brine is connected to a compression steel cylinder.
Further, the bottom of the carbon dioxide reaction absorption tower is provided with a sodium hydroxide solution or a reaction solution, the clean flue gas of the boiler is subjected to any one or combination of suspended jet flow, jet flow immersed in the solution, mixing of the flue gas and the sodium hydroxide solution through a jet flow guide air extractor and aeration of the flue gas from an aeration pipe at the bottom of the solution, so that the flue gas, the sodium hydroxide solution and the reaction solution are fully mixed and reacted.
Further, the sodium hydroxide solution is subjected to any one or combination of suspension jet flow, jet flow immersed in the solution and mixing of flue gas and the sodium hydroxide solution through an air jet drainage air extractor from the liquid inlet.
Furthermore, a spraying unit and/or an absorption liquid jet nozzle are arranged in the carbon dioxide reaction absorption tower, and the spraying unit and/or the absorption liquid jet nozzle are connected with a sodium hydroxide feeding system through an absorption liquid supply pipeline.
Furthermore, a carbon dioxide recovery pipeline is led out from the top of the carbon dioxide reaction absorption tower and connected to a boiler clean flue gas connecting pipeline, and a stop control valve and a gas dryer are arranged on the carbon dioxide recovery pipeline.
Further, a carbon dioxide concentration monitoring device is arranged at the top of the carbon dioxide reaction absorption tower.
A method for absorbing carbon dioxide in flue gas of a thermal power plant by using the absorption system, comprising the following steps:
s1: planning the scale of a flue gas carbon dioxide absorption system according to the surrounding land use condition of the thermal power plant, and determining the flow rate of flue gas entering the absorption system;
s2: according to the capacity of the thermal power plant unit, a device for preparing caustic soda by electrolyzing saline water or a purchased caustic soda preparation solution supply absorption system is arranged;
s3: according to the smoke discharge condition of a chimney of a thermal power plant, designing a clean smoke gas connecting pipeline to be connected to a carbon dioxide reaction absorption tower through a route, and sending the carbon dioxide in the smoke gas and a sodium hydroxide solution into a microalgae cultivation water tank or a solution storage tank for storage;
s4: and a system control program is set, and a control unit is used for monitoring the parameters of temperature, pressure, carbon dioxide concentration, nitrogen concentration, air pressure, sodium bicarbonate solution concentration, sodium hydroxide solution concentration and solution flow of each part of the system and accurately controlling the parameters in real time.
S5: and a carbon dioxide concentration monitoring device is arranged at the top of the carbon dioxide reaction absorption tower, when the concentration of carbon dioxide at the top is lower than a certain numerical value, an empty discharge valve of the led-out carbon dioxide recovery pipeline is opened, and the residual flue gas is discharged to a chimney of a thermal power plant or directly discharged to the air.
Further, in S3, the concentration of the sodium hydroxide solution input into the carbon dioxide reaction absorption tower by the sodium hydroxide feeding system is 10% -100%, and the concentration of the sodium bicarbonate solution sent into the microalgae cultivation water tank or the solution storage tank is 5% -80%.
Compared with the prior art, the invention has at least the following beneficial technical effects:
by utilizing the carbon dioxide absorption tower, the sodium hydroxide solution and the flue gas are fully mixed and reacted in the tower by any one or combination of the suspension jet flow, the jet flow immersed in the solution and the mixing mode of the flue gas and the sodium hydroxide solution through the jet flow guide air extractor, and the generated reaction liquid falls to the bottom of the absorption tower, so that the mixing and reaction of the high-efficiency carbon dioxide and the sodium hydroxide solution are realized. The low-price sodium hydroxide solution is utilized to realize high-efficiency carbon dioxide absorption, namely carbon capture.
Furthermore, the sodium hydroxide solution is produced at low price by electrolyzing the sodium chloride brine by utilizing the peak-adjusting frequency-modulating surplus electric power of the thermal power plant, and the sodium hydroxide solution is produced by electrolyzing the sodium chloride brine by utilizing the peak-adjusting frequency-modulating surplus electric power of the thermal power plant, so that the production cost is reduced, and the peak-adjusting frequency-modulating of the thermal power plant can be assisted.
Further, the final product sodium bicarbonate solution is used for cultivating microalgae, and final carbon capture and carbon sequestration are realized.
Furthermore, a carbon dioxide recovery pipeline is led out from the top of the carbon dioxide reaction absorption tower and connected to a boiler clean flue gas connecting pipeline, so that carbon dioxide gas which does not participate in reaction absorption escape returns to the clean flue gas connecting pipeline and reenters the reaction absorption tower for further reaction absorption.
Further, a carbon dioxide concentration monitoring device is arranged at the top of the carbon dioxide reaction absorption tower, when the concentration of carbon dioxide at the top is lower than a set value, an air discharge valve of a led-out carbon dioxide recovery pipeline is opened, and residual flue gas is discharged to a boiler chimney or directly discharged to the air.
According to the method, carbon dioxide is absorbed by using sodium hydroxide solution absorption liquid according to the flow rate of flue gas entering an absorption system; the chemical substance types of the absorption liquid and the specific absorption method and process route are determined, the carbon dioxide absorption efficiency is improved, and the carbon dioxide absorption cost is reduced.
Detailed Description
In order to make the objects and technical solutions of the present invention clearer and easier to understand. The present invention will be described in further detail with reference to the following drawings and examples, wherein the specific examples are provided for illustrative purposes only and are not intended to limit the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified. In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1, the flue gas caustic soda solution carbon dioxide absorption system of the thermal power plant comprises a boiler of the thermal power plant, a steam turbine, a generator and its accessories, a boiler clean flue gas connecting pipeline 4 of the thermal power plant 10 is connected to a tower bottom gas pipeline in a carbon dioxide reaction absorption tower 1 through a flue gas supply pipeline 17, a flue gas inlet is formed on the tower bottom gas pipeline, and a liquid inlet for inputting a sodium hydroxide solution is formed at the upper part of the carbon dioxide reaction absorption tower 1; the flue gas supply pipeline 17 is sequentially provided with a first gas drier 5, a first pressure control valve 6 and a first stop control valve 7 along the flow direction of the clean flue gas, and the carbon dioxide reaction absorption tower 1 is connected with the sodium hydroxide feeding system 2 through an absorption liquid supply pipeline 13; the absorption liquid supply pipeline 13 is provided with a feed pump 9 and a second stop control valve 23, and the carbon dioxide reaction absorption tower 1 is provided with a third stop control valve 25 through a reaction liquid discharge pipeline 8 and a reaction liquid discharge pipeline 8 of the solution storage tank 3.
The carbon dioxide reaction absorption tower 1 is connected with the flue gas supply pipeline 17 through a carbon dioxide recovery pipeline 20, and a second gas dryer 24 and a second pressure control valve 26 are sequentially arranged on the carbon dioxide recovery pipeline 20 along the medium conveying direction, so that the carbon dioxide gas which does not participate in the reaction absorption escape returns to the clean flue gas connection pipeline and enters the reaction absorption tower again for further reaction absorption.
The bottom of the carbon dioxide reaction absorption tower 1 is sodium hydroxide solution, and the flue gas is introduced into the solution from the bottom of the solution to react with the solution; or the flue gas enters the tower from the bottom, the sodium hydroxide solution enters the tower from the upper part of the tower through the atomizing nozzle, and the atomized solution droplets are mixed and reacted with the flue gas from top to bottom in a convection manner to generate the sodium bicarbonate solution.
The boiler clean flue gas is subjected to any one or combination of modes of suspended jet flow, jet flow immersed in the solution, mixing of the flue gas and the sodium hydroxide solution through a jet flow guide air extractor, aeration of the flue gas from an aeration pipe at the bottom of the solution and the like, so that the flue gas, the sodium hydroxide solution and the reaction liquid are fully mixed and reacted.
The bottom of the carbon dioxide reaction absorption tower 1 is provided with a sodium hydroxide solution or a reaction solution, the sodium hydroxide solution is fully mixed and reacted with the flue gas in any one or combination of modes of suspension jet flow, jet flow immersed in the solution, mixing of the flue gas and the sodium hydroxide solution through a jet flow guide air extractor and the like, the concentration of the sodium hydroxide solution is 10%, and the concentration range of the sodium bicarbonate solution is 5%.
The top of the carbon dioxide reaction absorption tower 1 is provided with a carbon dioxide concentration monitoring device, when the carbon dioxide concentration at the top of the carbon dioxide reaction absorption tower 1 is lower than a set value, an air discharge valve of the led-out carbon dioxide recovery pipeline 20 is opened, and the residual flue gas is discharged to a boiler chimney or directly discharged to the air.
Preferably, the carbon dioxide absorption system further comprises a parameter monitoring and controlling unit for monitoring and controlling the temperature, pressure, carbon dioxide concentration, nitrogen concentration, air pressure, sodium hydroxide solution concentration, reaction solution concentration, solution flow and other parameters of each part of the system, and the parameter monitoring and controlling unit is used for realizing real-time monitoring and accurate control of the parameters.
Example 2
Referring to fig. 2, the flue gas caustic soda solution carbon dioxide absorption system of the thermal power plant comprises a boiler, a steam turbine, a generator and its accessories of the thermal power plant, a boiler clean flue gas connecting pipeline 4 of the thermal power plant 10 is connected to a carbon dioxide reaction absorption tower 1 through a flue gas supply pipeline 17, a flue gas inlet connected to a tower bottom gas transmission pipeline is arranged at the lower part of the carbon dioxide reaction absorption tower 1, and an inlet for inputting sodium hydroxide solution is arranged at the upper part of the carbon dioxide reaction absorption tower 1A liquid port; a first gas drier 5, a first pressure control valve 6 and a first stop control valve 7 are sequentially arranged on the flue gas supply pipeline 17 along the flow direction of the purified flue gas, and the carbon dioxide reaction absorption tower 1 is connected with the sodium hydroxide feeding system 2 through an absorption liquid supply pipeline 13; the absorption liquid supply pipeline 13 is provided with a feed pump 9 and a second stop control valve 23, and the carbon dioxide reaction absorption tower 1 passes through NaHCO3The supply pipeline 27 is connected with the microalgae cultivation water tank 12, the reaction liquid discharge pipeline 8 is provided with a third stop control valve 25, the carbon supplement amount required in the culture solution is met, the pH value of the water tank solution is adjusted, the sodium bicarbonate solution is supplemented to the microalgae cultivation water tank, the absorption of the microalgae on the bicarbonate ions is met, and therefore the carbon supplement requirement of the microalgae is met. The reaction liquid discharge line 8 is provided with a third stop control valve 25.
The carbon dioxide reaction absorption tower 1 is connected with the flue gas supply pipeline 17 through a carbon dioxide recovery pipeline 20, and a second gas dryer 24 and a second pressure control valve 26 are sequentially arranged on the carbon dioxide recovery pipeline 20 along the medium conveying direction, so that the carbon dioxide gas which does not participate in the reaction absorption escape returns to the clean flue gas connection pipeline and enters the reaction absorption tower again for further reaction absorption.
The bottom of the carbon dioxide reaction absorption tower 1 is sodium hydroxide solution or reaction solution, the concentration of the sodium hydroxide solution is 45%, and the concentration range of the sodium bicarbonate solution is 42%.
The top of the carbon dioxide reaction absorption tower 1 is provided with a carbon dioxide concentration monitoring device, when the carbon dioxide concentration at the top of the carbon dioxide reaction absorption tower 1 is lower than a set value, an air discharge valve of the led-out carbon dioxide recovery pipeline 20 is opened, and the residual flue gas is discharged to a boiler chimney or directly discharged to the air.
The boiler clean flue gas is subjected to any one or combination of modes of suspended jet flow, jet flow immersed in the solution, mixing of the flue gas and the sodium hydroxide solution through a jet flow guide air extractor, aeration of the flue gas from an aeration pipe at the bottom of the solution and the like, so that the flue gas, the sodium hydroxide solution and the reaction liquid are fully mixed and reacted.
The sodium hydroxide solution enters the carbon dioxide reaction absorption tower 1 from the upper part through an atomizing nozzle or a spray nozzle, and the atomized or sprayed sodium hydroxide solution droplets are mixed and reacted with the flue gas from top to bottom in a convection manner, so that the generated reaction liquid falls into the bottom of the carbon dioxide reaction absorption tower 1.
Preferably, the carbon dioxide absorption system further comprises a parameter monitoring and controlling unit for monitoring and controlling the temperature, pressure, carbon dioxide concentration, nitrogen concentration, air pressure, sodium hydroxide solution concentration, reaction solution concentration, solution flow and other parameters of each part of the system, and the parameter monitoring and controlling unit is used for realizing real-time monitoring and accurate control of the parameters.
The sodium hydroxide solution comes from an electrolytic tank 11 for preparing caustic soda by electrolyzing brine in a thermal power plant; the power used by the electrolytic tank 11 for preparing caustic soda by electrolyzing saline water is the peak-load and frequency-modulation surplus power of a thermal power plant. Hydrogen generated by an electrolytic tank for preparing caustic soda by electrolyzing brine is sent to a boiler for afterburning or a steel cylinder for storage or an external pipeline for delivery, and the generated chlorine is compressed by the steel cylinder for storage and is sold for external use.
Example 3
Referring to fig. 2, the flue gas caustic soda solution carbon dioxide absorption system of the thermal power plant comprises a boiler of the thermal power plant, a steam turbine, a generator and its accessories, wherein a clean flue gas connection pipeline 4 of the boiler of the thermal power plant is connected to a carbon dioxide reaction absorption tower 1 through a flue gas supply pipeline 17, a flue gas inlet connected with a tower bottom gas transmission pipeline is arranged at the lower part of the carbon dioxide reaction absorption tower 1, and a liquid inlet for inputting a sodium hydroxide solution is arranged at the upper part of the carbon dioxide reaction absorption tower; a first gas drier 5, a first pressure control valve 6 and a first stop control valve 7 are sequentially arranged on the flue gas supply pipeline 17 along the flow direction of the purified flue gas, and the carbon dioxide reaction absorption tower 1 is connected with a sodium hydroxide feeding system 2 through an absorption liquid supply pipeline 13; the absorption liquid supply pipeline 13 is provided with a feed pump 9 and a second stop control valve 23, and the carbon dioxide reaction absorption tower 1 passes through NaHCO3The supply pipeline 27 is connected with the microalgae cultivation water tank 12, the reaction liquid discharge pipeline 8 is provided with a third stop control valve 25, the carbon supplement amount required in the culture solution is met, the pH value of the water tank solution is adjusted, the sodium bicarbonate solution is supplemented to the microalgae cultivation water tank, the absorption of the microalgae on the bicarbonate ions is met, and therefore the carbon supplement requirement of the microalgae is met. The reaction liquid discharge line 8 is provided with a third stop control valve 25.
The carbon dioxide reaction absorption tower 1 is connected with the flue gas supply pipeline 17 through a carbon dioxide recovery pipeline 20, and a second gas dryer 24 and a second pressure control valve 26 are sequentially arranged on the carbon dioxide recovery pipeline 20 along the medium conveying direction, so that the carbon dioxide gas which does not participate in the reaction absorption escape returns to the clean flue gas connection pipeline and enters the reaction absorption tower again for further reaction absorption.
The top of the carbon dioxide reaction absorption tower 1 is provided with a carbon dioxide concentration monitoring device, when the carbon dioxide concentration at the top of the carbon dioxide reaction absorption tower 1 is lower than a set value, an air discharge valve of the led-out carbon dioxide recovery pipeline 20 is opened, and the residual flue gas is discharged to a boiler chimney or directly discharged to the air.
The bottom of the carbon dioxide reaction absorption tower 1 is sodium hydroxide solution or reaction solution, the concentration of the sodium hydroxide solution is 100%, and the concentration range of the sodium bicarbonate solution is 85%.
The boiler clean flue gas is aerated by an aeration pipe at the bottom of the solution, so that the flue gas, the sodium hydroxide solution and the reaction liquid are fully mixed and reacted. The sodium hydroxide solution enters the carbon dioxide reaction absorption tower 1 from the upper part through an atomizing nozzle or a spray nozzle, and the atomized or sprayed sodium hydroxide solution droplets are mixed and reacted with the flue gas from top to bottom in a convection manner, so that the generated reaction liquid falls into the bottom of the carbon dioxide reaction absorption tower 1.
Preferably, the carbon dioxide absorption system further comprises a parameter monitoring and controlling unit for monitoring and controlling the temperature, pressure, carbon dioxide concentration, nitrogen concentration, air pressure, sodium hydroxide solution concentration, reaction solution concentration, solution flow and other parameters of each part of the system, and the parameter monitoring and controlling unit is used for realizing real-time monitoring and accurate control of the parameters.
The sodium hydroxide solution comes from an electrolytic tank 11 for preparing caustic soda by electrolyzing brine in a thermal power plant; the power used by the electrolytic tank 11 for preparing caustic soda by electrolyzing saline water is the peak-load and frequency-modulation surplus power of a thermal power plant. Hydrogen generated by an electrolytic tank for preparing caustic soda by electrolyzing brine is sent to a boiler for afterburning or a steel cylinder for storage or an external pipeline for delivery, and the generated chlorine is compressed by the steel cylinder for storage and is sold for external use.
Example 4
As shown in fig. 3, the method for absorbing carbon dioxide from flue gas based on the system of embodiment 1, embodiment 2 or embodiment 3 includes the following steps:
s1: planning and designing the scale of a flue gas carbon dioxide absorption system according to the surrounding land use condition of a thermal power plant, and particularly determining the flow rate of flue gas entering the absorption system;
s2: according to the condition of a thermal power plant unit (such as unit capacity), a device for preparing caustic soda by electrolyzing saline water or a system for supplying a purchased caustic soda preparation solution to a flue gas carbon dioxide absorption system is arranged;
s3: designing a clean flue gas connecting pipeline route to be connected to a carbon dioxide absorption tower according to the smoke discharging condition of a chimney of a thermal power plant, reacting carbon dioxide in flue gas with a sodium hydroxide solution in a carbon dioxide reaction absorption tower 1 to generate a sodium bicarbonate solution, and sending the sodium bicarbonate solution into a microalgae cultivation water tank 12 or a solution storage tank 3 for storage;
s4: and a system control program is set, and the system control program is used for monitoring and controlling the parameters of the temperature, the pressure, the carbon dioxide concentration, the nitrogen concentration, the air pressure, the sodium bicarbonate solution concentration, the sodium hydroxide solution concentration, the solution flow and the like of all parts of the system, and is used for realizing real-time monitoring and accurate control of the parameters.
S5: when the concentration of the carbon dioxide at the top is lower than a set value, an empty discharge valve of the carbon dioxide recovery pipeline 20 is opened, and the residual flue gas is discharged to a chimney of a thermal power plant or directly discharged to the air.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The boiler flue gas carbon dioxide absorption system and the boiler flue gas carbon dioxide absorption method provided by the invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.