Drainage integrated boiler for carbon dioxide capture and drainage system

Abstract

The drainage integrated boiler for carbon dioxide capture comprises a boiler body and a drainage tank body, the drainage integrated boiler comprises a liquid inlet and a liquid outlet which are located in a first end socket and a second end socket respectively, and further comprises a steam inlet and a liquid outlet which are located in the side wall of a shell; the boiler body provides a place for heat exchange between an amine solution and water vapor; the water draining tank body is arranged on the side close to the second sealing head and is positioned below the boiler body; and the water draining tank body is configured to store liquefied water vapor. The invention further discloses a drainage system which comprises the drainage integrated boiler, a drainage pump and an adjusting valve. The drainage pump is configured to pump condensed water vapor to a power plant condensed water system or a unit drainage tank. According to the method, the drained water can be recycled in a large-scale carbon dioxide capture project, energy and a working medium are recycled at the same time, a large amount of energy is saved, and conditions are created for popularization and application of the carbon dioxide capture project (CCUS).

Description

Technical Field

[0001] The present application relates to the technical field of carbon dioxide capture, and in particular to a hydrophobic integrated boiler for carbon dioxide capture, and also to a hydrophobic system including the above-mentioned hydrophobic integrated boiler. Background Art

[0002] my country's resource endowment determines that high-efficiency coal-fired power generation units will continue to occupy an important position in my country's power system in the medium and long term. Carbon dioxide capture and utilization storage technology (CCUS), as the only negative carbon solution, is one of the important ways to reduce carbon dioxide emissions from coal-fired power plants in the future. Therefore, it is of great practical significance to carry out research and engineering demonstration of carbon dioxide capture and utilization storage technology (CCUS). my country has carried out some large-scale carbon dioxide capture demonstration projects, and some large-scale carbon dioxide capture demonstration projects are still in progress. Carbon dioxide capture is an environmental protection project. The capture process is also accompanied by energy utilization, working fluid loss and equipment maintenance. Reducing the energy consumption loss of the carbon dioxide capture process and improving the safety and reliability of the equipment are the current research focuses.

[0003] According to the characteristics of flue gas in coal-fired power plants, the alcohol amine absorption method is the preferred technology for capturing carbon dioxide from flue gas in coal-fired power plants. The technical principle is: the flue gas coming out of the boiler first undergoes purification measures such as denitrification, dust removal, desulfurization, and water washing, and the temperature, pressure and other parameters of the flue gas are adjusted to meet the requirements of the carbon dioxide absorption tower. The purified flue gas enters the carbon dioxide absorption device, and the carbon dioxide in the flue gas reacts with the lean amine solution to be removed, and the flue gas that does not contain (or contains a small amount of) carbon dioxide (the main components are nitrogen and water vapor) is discharged through the chimney. The CO2-rich rich amine solution is desorbed in the desorption tower, and the desorption process is heated by a boiler to release high-purity CO2, and the absorbent is regenerated to become a lean amine solution for recycling. After the high-purity CO2 is captured, it is pressurized and liquefied for transportation, storage or utilization. See the system flow. Figure 1 shown.

[0004] The energy consumption of the carbon dioxide capture process mainly occurs in the desorption process of the rich amine solution. A large amount of steam needs to be input into the boiler to heat the rich amine solution, release the carbon dioxide adsorbed by the amine solution, and then separate the carbon dioxide through subsequent drying, purification, liquefaction and other processes. The carbon dioxide capture and desorption process requires a large amount of steam, generally about 1.2-1.5t steam / t CO2. When the capture scale is small, the steam is converted into condensate with a temperature of about 100°C after releasing heat in the boiler. The condensate can be sent to the unit drainage trough or pit for working fluid recovery; when large-scale carbon dioxide capture is adopted, such as 50-100t / h of carbon dioxide capture per hour, according to the higher efficiency of carbon dioxide capture 1.2 steam / t CO2, the steam / drainage volume reaches 60-120t / h. The above-mentioned large amount of high temperature (100°C) condensate, if directly discharged, will cause energy loss and visual (water vapor) pollution, and also requires a large amount of cooling water to cool before it can be sent to the pit or unit drainage trough.

[0005] In the current typical process route, the commonly used amine solution is limited by the reaction temperature, which is 105-110℃, and the required steam is within 150℃, so the required steam is low-quality (about 0.3MPa, 140℃) saturated steam; the heat required in the desorption process is about 2.2-2.8GJ / t CO2 (converted to about 1.2-1.5t steam / t CO2). Therefore, a large amount of steam is required in the large-scale carbon dioxide capture process reaction process. For example, the engineering projects that have been put into operation have a carbon dioxide capture capacity of about 120,000-150,000 tons / year, which requires 18-24t of steam per hour. After the steam is condensed, condensate water of about 100℃ is produced. The common measure is to recover the above condensate water as a simple working medium, and the heat is not recovered. The water quality of the condensate itself is equivalent to that of desalted water, but in the recovery process, due to mixing with industrial water, the impurities in the water increase, and the quality of the mixed water is basically equivalent to that of industrial water, and further purification and treatment are required to become desalted water again.

[0006] In the thermal system of a thermal power plant, the low-pressure heater also uses steam and condensate for heat exchange. A water storage tank is provided at the bottom of the low-pressure heater, and a drain pump is provided to transport the condensate in the tank to a location with a suitable temperature in the condensate system to recover the working fluid and energy.

[0007] At present, the common flue gas carbon dioxide capture technology of coal-fired power plants is that the steam drainage of the boiler system is mostly discharged directly to the ditch or to the unit drainage tank. Figure 2 The disadvantages of this solution are:

[0008] 1. The quality of steam condensate is equivalent to desalted water, which is discharged into the ditch or unit drainage tank and mixed with industrial water. The chemical water treatment system then treats the industrial water to desalted water quality for recycling, which increases the cost of chemical water treatment;

[0009] 2. The conventional condensate temperature is about 100℃, and it is discharged into the ditch or the unit drainage system. In order to reduce water vapor loss and visual pollution and protect pumps and other equipment from being scalded, a large amount of cooling water needs to be added. All the energy in the condensate is lost, and the complexity of the system is increased. Specifically, the enthalpy of 0.3MPa steam is 2738kJ / kg, and the enthalpy of saturated water at the same pressure is 604kJ / kg. The heat of saturated water accounts for 22% of saturated steam.

[0010] 3. The current common coal-fired power plant flue gas carbon dioxide capture technology is relatively suitable for medium-sized coal-fired power plant flue gas carbon dioxide capture systems. When the capture scale is further expanded, for example to 500,000 tons / year-1 million tons / year, it will have a greater impact on ditches, unit drainage ditches, etc., which is not conducive to large-scale coal-fired power plant flue gas carbon dioxide capture systems.

[0011] 4. Install a steam trap, which has a high failure rate.

[0012] 5. The system is relatively complex and requires the installation of a hydrophobic expansion tank for capacity expansion and a cooling water system for cooling. Summary of the invention

[0013] The purpose of the present application is to provide a drain-integrated boiler for carbon dioxide capture, and a drain system including the above-mentioned drain-integrated boiler. According to the characteristics of large-scale flue gas carbon dioxide capture systems in coal-fired power plants, working fluids and energy are recovered simultaneously, and a carbon dioxide capture system boiler and a drain system with a drain-integrated function are provided.

[0014] The present application discloses a hydrophobic integrated boiler for carbon dioxide capture, comprising: a boiler body and a hydrophobic tank body, wherein:

[0015] The hydrophobic integrated boiler comprises a liquid inlet located at a first end cap, a liquid outlet located at a second end cap, and also comprises a steam inlet and a liquid outlet located at a side wall of the shell;

[0016] The boiler body is constructed to: provide a place for heat exchange between the amine solution and water vapor;

[0017] The hydrophobic tank body is arranged near the second head side and below the boiler body, and the hydrophobic tank body is configured to store liquefied water vapor.

[0018] In a preferred example, the storage capacity of the hydrophobic tank ranges from 1.5 to 5 tons.

[0019] The present application also discloses a drainage system for carbon dioxide capture, comprising: a drainage integrated boiler as described above; and also comprising: a drainage pump and a regulating valve;

[0020] The liquid inlet of the hydrophobic integrated boiler is connected to the desorption tower;

[0021] The drain tank of the integrated drain boiler is connected to one or more drain pumps through a regulating valve; when there are multiple drain pumps, they are arranged in parallel; the drain pumps are configured to pump condensed water vapor to the power plant condensate system or unit drain tank.

[0022] In a preferred example, the steam flow rate of the degassing system ranges from 18 to 30 tons / hour.

[0023] In a preferred example, the hydrophobic integrated boiler is arranged vertically or horizontally.

[0024] In a preferred example, the vertical distance between the bottom of the integrated drain boiler and the drain pump is at least 5 meters.

[0025] In a preferred example, the drain pump is arranged on the ground, or in a negative excavation arrangement.

[0026] The present application also discloses a drainage system for carbon dioxide capture, comprising: a boiler, a drainage tank; and also comprising: a drainage pump and a regulating valve;

[0027] The liquid inlet of the boiler is connected to the desorption tower, and the liquid outlet is connected to the drain tank;

[0028] The drain tank is connected to one or more drain pumps through a regulating valve; when there are multiple drain pumps, they are arranged in parallel; the drain pump is configured to pump the condensed water vapor to the condensate system of the power plant or the unit drainage tank;

[0029] The vertical distance between the drain tank and the drain pump is at least 5 meters.

[0030] This application has at least the following technical effects:

[0031] (1) A drain tank is provided below the boiler, which can be arranged integrally with the boiler or connected with a pipeline in the middle;

[0032] (2) The boiler can be of tubular or plate type, horizontal or vertical type;

[0033] (3) The amine working fluid side of the boiler is connected to the absorption tower, and the inlet and outlet heights meet the process requirements of the absorption tower;

[0034] (4) a water storage space or a separate drain tank is provided at the bottom of the boiler;

[0035] (5) A drain pump is installed to deliver the high-temperature condensate in the drain tank to the condensate system or the condensate or water supply system such as the low-pressure heater and deaerator. A closed system is used without an expansion tank.

[0036] (6) The height difference between the drain tank and the water pump meets the anti-cavitation requirements of the drain pump. The drain pump is preferably arranged on the ground; if the site is insufficient, the negative excavation arrangement can also be adopted;

[0037] (7) The drain pump group can be set up with one or more pumps.

[0038] The specification of the present application records a large number of technical features, which are distributed in various technical solutions. If all possible combinations of technical features of the present application (i.e., technical solutions) are to be listed, the specification will be too long. In order to avoid this problem, the various technical features disclosed in the above-mentioned invention content of the present application, the various technical features disclosed in the various embodiments and examples below, and the various technical features disclosed in the accompanying drawings can be freely combined with each other to form various new technical solutions (these technical solutions should all be regarded as having been recorded in this specification), unless the combination of such technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed, and features C and D are equivalent technical means that play the same role. Technically, only one can be used, and it is impossible to use them at the same time. Feature E can be combined with feature C technically. Then, the solution of A+B+C+D should not be regarded as having been recorded because it is technically infeasible, and the solution of A+B+C+E should be regarded as having been recorded. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the structure of a CO2 capture system according to the prior art;

[0040] Figure 2 is a schematic diagram of a boiler for carbon dioxide capture according to the prior art, and a drainage system thereof;

[0041] Figure 3 is a schematic structural diagram of a hydrophobic system for carbon dioxide capture according to an embodiment of the present application;

[0042] Figure 4 is a schematic structural diagram of a hydrophobic system for carbon dioxide capture according to another embodiment of the present application;

[0043] Description of reference numerals:

[0044] 1- boiler body;

[0045] 2-drain tank;

[0046] 3-Drain pump;

[0047] 4- Regulating valve. DETAILED DESCRIPTION

[0048] After extensive and in-depth research, the inventors have proposed a carbon dioxide capture system boiler and a drain system with a drain tank. In large-scale carbon dioxide capture projects, drain can be recovered, and energy and working fluid can be recovered at the same time. The matching drain pump is reliable and can save a lot of energy, creating conditions for the promotion and application of carbon dioxide capture projects (CCUS).

[0049] In the following description, many technical details are provided to help readers better understand the present application. However, those skilled in the art can understand that the technical solution claimed in the present application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0050] the term

[0051] Carbon dioxide capture and storage (CCUS): Carbon dioxide capture technology is used to remove carbon dioxide from gas streams or separate carbon dioxide as a gas product (carbon capture and storage, referred to as CCS technology). The power industry is the main application area of ​​CCS technology. Carbon dioxide released by the combustion of fossil fuels is the main source of greenhouse gases, among which the power generation industry accounts for the largest proportion of emissions. The capture technology described in this article is the absorption capture technology of carbon dioxide in the flue gas of coal-fired power plants.

[0052] Reboiler: As the name implies, the reboiler vaporizes the liquid again. Its structure is similar to that of the condenser, but the condenser is used to cool down, while the reboiler is used to heat up and vaporize. The material expands or even vaporizes due to heat in the reboiler (boiler), and its density decreases, so it leaves the vaporization space and smoothly returns to the tower. The gas and liquid phases in the tower return upward through the tower tray, while the liquid phase falls to the bottom of the tower. Due to the static pressure difference, the bottom of the tower will continuously replenish the part of the liquid level that has been evaporated.

[0053] Cavitation: The process of formation, development and collapse of vapor or gas cavities (cavitation bubbles) inside the liquid or on the liquid-solid interface when the local pressure inside the liquid decreases. Cavitation can cause damage to the pump. For working fluids close to saturation temperature, cavitation problems should be considered in particular; cavitation margins need to be reserved when designing pumps.

[0054] The following is a brief description of some innovative aspects of the implementation methods of this application:

[0055] CO2 capture system boiler and drain system with integrated drain function Figure 3As shown in the figure, the system is used for large-scale flue gas carbon dioxide capture system in coal-fired power plants. A boiler with integrated drain function is set up, and 3-5 minutes of drain can be stored in the boiler. The amine working fluid side of the boiler is connected to the desorption tower to meet the amine working fluid circulation elevation requirements. At the same time, the lower part of the boiler is kept at a certain height from the ground, with a height difference of more than 5m from the drain pump, meeting the cavitation margin requirements of the drain pump. A drain pump is set up on the ground to recover condensate to thermal systems such as low-pressure heating or deaerators in coal-fired power plants, and at the same time, the working fluid and heat are fully recovered.

[0056] The system makes full use of the lower space of the boiler and sets up a drain storage tank. The condensed water and the upper heat exchange steam maintain the same pressure, and there is no need to expand the expansion tank later; the pressurized saturated water is stored in the drain storage tank and maintains a certain height difference with the drain pump to meet the anti-cavitation requirements of the drain pump. Recycling the steam drain of the flue gas carbon dioxide capture system of the coal-fired power plant, while recovering the working fluid and energy, has good benefits. Create conditions for the promotion and application of carbon dioxide capture engineering (CCUS).

[0057] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with the accompanying drawings.

[0058] Embodiment 1,

[0059] Hydrophobic integrated boiler for carbon dioxide capture Figure 3 As shown, it includes: a boiler body 1 and a hydrophobic tank body 2, wherein the hydrophobic integrated boiler includes a liquid inlet located at the first head and a liquid outlet located at the second head for the inflow and outflow of the amine solution; the liquid inlet is connected to the desorption tower. The integrated boiler also includes a steam inlet and a liquid outlet for water vapor located on the side wall of the shell. In the vertical arrangement, the steam inlet is located below the gas outlet. The boiler body is constructed to provide a place for heat exchange between the amine solution and the water vapor. The hydrophobic tank body is arranged near the second head side and below the boiler body, and the hydrophobic tank body is constructed to store liquefied water vapor. Calculated based on a water vapor flow rate of 30 tons / hour, i.e. 0.5 tons / minute, the hydrophobic tank body can store condensed water for 5 minutes, i.e. the storage capacity is 2.5 tons.

[0060] The drain system includes the above-mentioned drain-integrated boiler; and also includes: a plurality of drain pumps 3 and regulating valves 4. The drain tank of the drain-integrated boiler is connected to a plurality of parallel drain pumps through regulating valves. The drain pumps are configured to pump condensed water vapor to the condensate system of the power plant or the drainage tank of the unit.

[0061] The drain pump is arranged on the ground, and the vertical distance between the bottom of the integrated drain boiler and the drain pump is 5 meters. This height difference is the minimum height difference to ensure that the drain pump does not suffer from cavitation.

[0062] Embodiment 2,

[0063] In this embodiment, the boiler and the drain tank are arranged separately. Figure 4 As shown, the drain system includes: a boiler, a drain tank; and also includes: a drain pump and a regulating valve. The liquid inlet of the boiler is connected to the desorption tower, and the liquid outlet is connected to the drain tank. The drain tank is connected to multiple parallel drain pumps through a regulating valve; the drain pump is configured to pump the condensed water vapor to the condensate system of the power plant or the unit drainage tank.

[0064] The drain pump adopts a negative excavation layout, and the vertical distance between the bottom of the integrated drain boiler and the drain pump is 5 meters. This height difference is the minimum height difference to ensure that the drain pump does not suffer from cavitation.

[0065] It should be noted that in the application documents of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one" do not exclude the existence of other identical elements in the process, method, article or device including the elements. In the application documents of this patent, if it is mentioned that an action is performed according to an element, it means that the action is performed at least according to the element, which includes two situations: performing the action only according to the element, and performing the action according to the element and other elements. Expressions such as multiple, multiple, and multiple include 2, 2 times, 2 kinds, and more than 2, more than 2 times, and more than 2 kinds.

[0066] This specification includes combinations of the various embodiments described herein. Individual references to "one embodiment" or a particular embodiment, etc., do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated as mutually exclusive or clear to those skilled in the art. It should be noted that the word "or" is used in this specification in a non-exclusive sense unless the context clearly indicates or requires otherwise.

[0067] All documents mentioned in this application are considered to be included in the disclosure of this application as a whole, so that they can be used as the basis for modification when necessary. In addition, it should be understood that after reading the above disclosure of this application, those skilled in the art can make various changes or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A hydrophobic integrated boiler for carbon dioxide capture, characterized in that: include: Boiler body, drain tank, including: The hydrophobic integrated boiler comprises a liquid inlet located at a first end cap, a liquid outlet located at a second end cap, and also comprises a steam inlet and a liquid outlet located at a side wall of the shell; The boiler body is constructed to: provide a place for heat exchange between the amine solution and water vapor; The hydrophobic tank body is arranged near the second head side and below the boiler body, and the hydrophobic tank body is configured to store liquefied water vapor.

2. The hydrophobic integrated boiler according to claim 1, characterized in that: The storage capacity of the hydrophobic tank body ranges from 1.5 to 5 tons.

3. A hydrophobic system for carbon dioxide capture, characterized in that: include: The integrated drain boiler according to any one of claims 1 or 2; further comprising: a drain pump and a regulating valve; The liquid inlet of the hydrophobic integrated boiler is connected to the desorption tower; The drain tank of the integrated drain boiler is connected to one or more drain pumps through a regulating valve; when there are multiple drain pumps, they are arranged in parallel; the drain pumps are configured to pump condensed water vapor to the power plant condensate system or unit drain tank.

4. The hydrophobic system according to claim 3, characterized in that: The steam flow rate of the degassing system ranges from 18 to 30 tons / hour.

5. The hydrophobic system according to claim 3, characterized in that: The hydrophobic integrated boiler is arranged vertically or horizontally.

6. The hydrophobic system according to claim 3, characterized in that: The vertical distance between the bottom of the integrated drain boiler and the drain pump is at least 5 meters.

7. The hydrophobic system according to claim 3, characterized in that: The drain pump is arranged on the ground or in a negative excavation arrangement.

8. A hydrophobic system for carbon dioxide capture, characterized in that: include: Boiler, drain tank; also includes: drain pump, regulating valve; The liquid inlet of the boiler is connected to the desorption tower, and the liquid outlet is connected to the drain tank; The drain tank is connected to one or more drain pumps through a regulating valve; when there are multiple drain pumps, they are arranged in parallel; the drain pump is configured to pump the condensed water vapor to the condensate system of the power plant or the unit drainage tank; The vertical distance between the drain tank and the drain pump is at least 5 meters.

Images