Ethylene device carbon emission method and system
Through the integrated solar thermal collecting technology and amine washing carbon capture, the problem of the increase in carbon emissions caused by the need for additional steam during the carbon capture process of ethylene devices is solved, and efficient carbon emission reduction and carbon dioxide purity improvement are achieved.
Patent Information
- Application Number
- CN202510165362.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-14
- Publication Date
- 2025-05-09
AI Technical Summary
Traditional ethylene devices require additional steam during carbon capture, resulting in an increase in carbon emissions. Traditional amine absorbers require higher heat during carbon dioxide desorption, which is less economical.
The steam cracked ethylene production route using integrated solar heat collection technology and amine washing method carbon capture is used to save heat consumption caused by solvent regeneration through bypass heat exchange, and solar energy is used as the source of heat required for the regeneration of absorbents of the carbon capture system.
It has achieved carbon emission reduction in the ethylene production process without increasing additional carbon emissions, reducing the heat consumption of the carbon capture system, and improving the purity and capture efficiency of carbon dioxide.
Smart Images
Figure CN119951282A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of petrochemical industry and relates to a carbon emission reduction method and system for a steam cracking ethylene production route using solar energy technology and amine washing method carbon capture. Background Art
[0002] Ethylene is an important petrochemical product, and its production route is mainly based on steam cracking. In the process of thermal cracking of raw materials, a large amount of carbon dioxide will be emitted into the atmosphere due to the combustion of fuel in the furnace of the cracking furnace, thereby exacerbating the greenhouse effect. This problem can be solved by using post-combustion carbon capture based on chemical absorption. By washing the flue gas rich in carbon dioxide with an amine solution, most of the carbon dioxide in the flue gas can be removed. This method is suitable for treating flue gas with a low carbon dioxide partial pressure and is suitable for carbon emission reduction in steam cracking production processes. Amine solvents have high selectivity for acidic gases and are suitable as absorbents for carbon capture systems. However, traditional amine absorbents such as ethanolamine require high heat for carbon dioxide desorption, and have poor technical and economic performance.
[0003] The amine-wash carbon capture method requires steam as a heat source to heat the CO2-rich 2 The solvent is regenerated to desorb CO 2 In actual operation, the steam cracker will produce a certain amount of steam at different pressures. However, the traditional ethylene plant will not have excess steam to provide to the carbon capture device, and the production of steam will increase the combustion of fossil fuels. The additional resource consumption will result in a decrease in the carbon emission reduction effect.
[0004] Therefore, there is a need in the art for a carbon emission solution for ethylene plants that can reduce carbon emissions for ethylene production and maximize emission reductions without generating additional carbon dioxide emissions. Summary of the invention
[0005] In view of the above problems existing in the prior art, the present invention proposes a carbon emission method and system for a steam cracking ethylene production route that integrates solar thermal collection technology and amine washing carbon capture. In order to treat a large amount of carbon dioxide with a low partial pressure contained in the flue gas, the present invention uses an amine washing method to treat the flue gas, and saves the heat consumption caused by solvent regeneration through a bypass heat exchange strategy. In order to solve the problem of additional carbon emissions caused by purchasing steam for the carbon capture system, solar energy is used as the ultimate source of heat required for absorbent regeneration in the carbon capture system.
[0006] Specifically, one aspect of the present invention provides a carbon emission method for an ethylene device, the carbon emission method for an ethylene device comprising the following steps:
[0007] Step S1: Cool the flue gas generated by the cracking furnace of the ethylene device and send it to a carbon capture system. The carbon capture system includes an absorption tower. The flue gas is mixed with a gas for absorbing CO in the absorption tower. 2 The absorbent is a piperazine aqueous solution;
[0008] Step S2: using steam to heat the absorbed CO 2 absorbent to obtain a regenerated absorbent; the steam comes from a steam generation system; the steam generation system utilizes solar energy to heat a working medium, and then exchanges heat between water and the heated working medium to obtain the steam.
[0009] In one or more embodiments, the ethylene plant is an ethylene plant using a steam cracking process.
[0010] In one or more embodiments, the ethylene device carbon emission method further comprises: extracting the absorbed CO from the bottom of the absorption tower. 2 The absorbent absorbs CO 2 The absorbent is a rich solution, and the rich solution is divided into a first rich solution and a second rich solution; the carbon capture system also includes a stripping tower, a bypass heat exchanger, a cold liquid heat exchanger, a hot liquid heat exchanger and a steam heater. After the kettle liquid of the stripping tower is produced, it passes through the hot liquid heat exchanger and the cold liquid heat exchanger in sequence. The first rich solution enters the bypass heat exchanger to exchange heat with the top distillate of the stripping tower, and the second rich solution enters the cold liquid heat exchanger to exchange heat with the kettle liquid of the stripping tower flowing out of the hot liquid heat exchanger; the rich solution heated by the bypass heat exchanger enters the top of the stripping tower; the rich solution heated by the cold liquid heat exchanger is divided into two streams, one enters the top of the stripping tower, and the other enters the hot liquid heat exchanger to exchange heat with the kettle liquid of the stripping tower, and then enters the kettle of the stripping tower after being heated by the steam heater. The steam used by the steam heater comes from the steam generation system.
[0011] In one or more embodiments, the mass of the first rich solution accounts for 10%-40% of the total mass of the rich solution withdrawn from the bottom of the absorption tower, for example, 15%, 20%, 25%, 30%, 35%.
[0012] In one or more embodiments, the mass of the rich solution entering the top of the stripping tower after being heated by the cold liquid heater accounts for 40%-80% of the total mass of the rich solution after being heated by the cold liquid heater, for example, 45%, 50%, 55%, 60%, 65%, 70%, 75%.
[0013] In one or more embodiments, a stream of rich solution heated by the cold liquid heat exchanger is mixed with a stream of rich solution heated by the bypass heat exchanger and then enters the top of the stripping column.
[0014] In one or more embodiments, the stripping tower distills high purity CO 2 , the high purity CO 2 CO 2 The content is ≥ 99.5wt%, for example 99.6wt%, 99.7wt%, 99.8wt%, 99.9wt%.
[0015] In one or more embodiments, the pressure of the stripping column is 1.6-2.0 bar, such as 1.7 bar, 1.8 bar, 1.9 bar.
[0016] In one or more embodiments, the steam generation system includes an energy storage medium tank group, a solar thermal field, a heat storage tank group, a working medium and a heat exchanger. The energy storage medium tank group, the solar thermal field, the heat storage tank group and the heat exchanger are sequentially connected to form a loop, and the working medium exists in the loop; water exchanges heat with the working medium heated by solar energy in the heat exchanger to obtain the steam.
[0017] In one or more embodiments, the piperazine mass fraction of the piperazine aqueous solution is 30%-40%, for example, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%.
[0018] In one or more embodiments, the working medium is sodium nitrate, potassium nitrate, or a mixture of sodium nitrate and potassium nitrate.
[0019] In one or more embodiments, in step S1, the flue gas is cooled to 40-45°C (eg, 41°C, 42°C, 43°C, 44°C) and then fed into the absorption tower.
[0020] In one or more embodiments, in step S1, the pressure of the absorption tower is 1.0-1.1 atm.
[0021] In one or more embodiments, in step S2, the heating 2 The temperature of the absorbent vapor is 118-120°C.
[0022] Another aspect of the present invention provides a carbon emission system for an ethylene device, the carbon emission system for an ethylene device comprising:
[0023] Flue gas cooler, used to cool the flue gas generated by the cracking furnace of the ethylene plant;
[0024] A carbon capture system, the carbon capture system comprising an absorption tower, the absorption tower is used to make the flue gas and absorb CO 2 contact with an absorbent;
[0025] The steam generation system is used to heat the working medium using solar energy, and then exchange heat between water and the heated working medium to obtain steam, which is used to heat the absorbed CO 2 of absorbent to obtain a regenerated absorbent.
[0026] In one or more embodiments, the carbon capture system further comprises a stripper, a bypass heat exchanger, a cold liquid heat exchanger, a hot liquid heat exchanger, and a steam heater;
[0027] The absorbed CO 2 The absorbent is a rich solution, the rich solution is divided into a first rich solution and a second rich solution, and the rich solution outlet at the bottom of the absorption tower is connected to the rich solution inlet of the bypass heat exchanger and the rich solution inlet of the cold liquid heat exchanger;
[0028] The bypass heat exchanger is used to exchange heat between the first rich solution and the overhead product of the stripping tower;
[0029] The stripping tower kettle liquid is extracted and sequentially passed through a hot liquid heat exchanger and a cold liquid heat exchanger, wherein the stripping tower kettle liquid inlet of the hot liquid heat exchanger is connected to the stripping tower kettle liquid outlet, and the stripping tower kettle liquid outlet of the hot liquid heat exchanger is connected to the stripping tower kettle liquid inlet of the cold liquid heat exchanger;
[0030] The cold liquid heat exchanger is used to exchange heat between the second rich solution and the kettle liquid of the stripping tower flowing out of the hot liquid heat exchanger;
[0031] The rich solution outlet of the bypass heat exchanger is connected to the top of the stripping tower, and the rich solution heated by the bypass heat exchanger enters the top of the stripping tower;
[0032] The rich solution outlet of the cold liquid heat exchanger is connected to the top of the stripping tower and the rich solution inlet of the hot liquid heat exchanger, the rich solution outlet of the hot liquid heat exchanger is connected to the rich solution inlet of the steam heater, the rich solution outlet of the steam heater is connected to the bottom of the stripping tower, and the rich solution heated by the cold liquid heat exchanger is divided into two streams, one stream enters the top of the stripping tower, and the other stream first enters the hot liquid heat exchanger to exchange heat with the bottom liquid of the stripping tower, and then enters the bottom of the stripping tower after being heated by the steam heater;
[0033] The steam inlet of the steam heater is connected to the steam generating system, and the steam used by the steam heater comes from the steam generating system.
[0034] In one or more embodiments, the steam generation system includes an energy storage medium tank group, a solar thermal collection field, a heat storage tank group, a working medium and a heat exchanger. The energy storage medium tank group, the solar thermal collection field, the heat storage tank group and the heat exchanger are sequentially connected to form a loop, and the working medium exists in the loop; the heat exchanger is used to exchange heat between water and the working medium heated by solar energy to obtain the steam.
[0035] The carbon emission method of the ethylene device of the present invention can be implemented using the carbon emission system of the ethylene device of the present invention.
[0036] The present invention uses an aqueous solution of piperazine as a carbon dioxide absorbent, which can significantly reduce the heat consumption of the carbon capture system. The carbon dioxide captured by the present invention has high purity and can be used for carbon sequestration (such as geological sequestration, marine sequestration, mineral sequestration, etc.) after being transported by pipeline, road or rail, or can be used as a raw material to produce chemicals (such as methanol, urea, etc.). The method of the present invention can process a large amount of carbon dioxide contained in the flue gas discharged by the ethylene cracking furnace, while avoiding the additional greenhouse gas emissions caused by the purchase of steam, and can achieve efficient emission reduction in ethylene production. BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Figure 1 This is a schematic diagram of the process flow of the carbon emission system of an ethylene plant in some embodiments of the present invention.
[0038] Explanation of the reference numerals: 1 to 41 represent the first to forty-first pipelines respectively, and Q represents the steam generated by the steam generating system. DETAILED DESCRIPTION
[0039] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in this document. Unless otherwise specified, all technical and scientific terms used in this document have the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definitions in this specification shall prevail.
[0040] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.
[0041] Herein, “comprising”, “including”, “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of”. For example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to be disclosed herein.
[0042] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values within the range (including integers and fractions).
[0043] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.
[0044] Herein, the sum of the percentages of the various components of the composition is 100%.
[0045] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, modifications and equivalents of the methods and materials described in the present invention are all within the scope of the present invention.
[0046] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.
[0047] In some embodiments, the carbon emission method of an ethylene device of the present invention includes: cooling the flue gas of the cracking furnace of the ethylene device using the steam cracking process and sending it into the carbon capture system through a blower; in the carbon capture system, using a piperazine aqueous solution as an absorbent; a steam generation system composed of a solar energy collection field and a molten salt heat storage system uses solar energy as a heat source to provide the carbon capture system with steam required for absorbent regeneration.
[0048] In some embodiments, the ethylene device carbon emission method of the present invention comprises the following steps:
[0049] The flue gases from multiple ethylene cracking furnaces are mixed, cooled, and sent to the absorption tower of the carbon capture system through a blower. Piperazine aqueous solution is used to contact the flue gas in reverse, and the rich solution that reaches chemical equilibrium with carbon dioxide flows out from the bottom of the absorption tower;
[0050] The rich solution is divided into a first rich solution and a second rich solution. The first rich solution enters the stripping tower from the top of the stripping tower after heat exchange with the produced stream from the top of the stripping tower, and the second rich solution enters the stripping tower from the top of the stripping tower and the stripping tower kettle after heat exchange with the produced stream from the stripping tower kettle; wherein the rich solution entering the stripping tower from the stripping tower kettle is heated by a steam heater before entering the stripping tower kettle; the steam used by the steam heater comes from a steam generation system, and the steam generation system includes a solar collector field, an energy storage medium storage tank group, a heat storage tank group, a working medium and a heat exchanger;
[0051] The top distillate of the stripping tower is high-purity carbon dioxide, which is cooled to 25-50°C and then 2 The compressor unit compresses it to 3-15MPa; the high-purity carbon dioxide can be stored geologically, in the ocean and / or in minerals, or used as a raw material to produce chemicals (such as methanol and urea).
[0052] In some preferred embodiments, in the carbon capture system, the rich solution extracted from the bottom of the absorption tower is pressurized by a rich liquid pump and then divided into a first rich solution and a second rich solution. The first rich solution enters the bypass heat exchanger for heat exchange with the distillate from the top of the stripping tower, and the second rich solution enters the cold liquid heat exchanger for heat exchange with the stripping tower kettle liquid flowing out of the hot liquid heat exchanger; the rich solution heated by the cold liquid heat exchanger is divided into two streams, one stream is mixed with the rich solution heated by the bypass heat exchanger and then enters the top of the stripping tower, and the other stream first enters the hot liquid heat exchanger for heat exchange with the kettle liquid of the stripping tower, and then enters the kettle of the stripping tower after being heated by a steam heater.
[0053] In some preferred embodiments, in the steam generation system, the working medium is stored in the energy storage medium storage tank group. When the solar energy is sufficient, it is pumped to the solar thermal field to absorb heat and convert into high-temperature working medium, and the high-temperature working medium is stored in the heat storage tank group; the high-temperature working medium and boiler feed water are heat exchanged in the heat exchanger to obtain steam, which is supplied to the steam heater. The temperature of the steam can be 118-120°C. The pressure of the steam can be 2.0±0.2bar.
[0054] In some preferred embodiments, the flue gas passes through a flue gas cooler before entering the absorption tower, and the flue gas cooler cools the flue gas to 40-45° C. before entering the absorption tower.
[0055] In some preferred embodiments, the mass fraction of piperazine in the piperazine aqueous solution is 30%-40%.
[0056] In some preferred embodiments, liquid collecting trays, intercoolers and liquid redistributors are provided between the packed sections of the absorption tower.
[0057] In some preferred embodiments, the solvent for washing the flue gas is extracted from the absorption tower, cooled, and then fed to the top of the packing at the bottom of the absorption tower.
[0058] In some preferred embodiments, a water washing section is provided at the top of the absorption tower to recover the solvent volatilized during the operation of the absorption tower.
[0059] In some preferred embodiments, the temperature of the steam heater is maintained at 118-120°C.
[0060] In some preferred embodiments, the absorption tower pressure is maintained at 1.0-1.1 atm.
[0061] In some preferred embodiments, the stripping column pressure is maintained at 1.6-2.0 bar.
[0062] In some preferred embodiments, the working medium is sodium nitrate, potassium nitrate, or a mixture of sodium nitrate and potassium nitrate.
[0063] In some preferred embodiments, CO 2 The compressor unit includes three-stage compressors, and an intercooler can be provided between the compressors to control the exhaust temperature of the carbon dioxide at 25-50°C.
[0064] In the present invention, the rich solution extracted from the absorption tower is divided into a first rich solution and a second rich solution. The first rich solution enters the stripping tower from the top of the stripping tower after heat exchange with the produced stream from the top of the stripping tower, and the second rich solution enters the stripping tower from the top of the stripping tower and the bottom of the stripping tower after heat exchange with the produced stream from the bottom of the stripping tower. This design can recover the heat in the produced materials from the top and bottom of the stripping tower. Compared with the traditional stripping tower, this design eliminates the reflux of the condensate and reduces the heat loss in the condenser. In some preferred embodiments, the mass of the first rich solution accounts for 10%-40% of the total mass of the rich solution extracted from the bottom of the absorption tower, which is conducive to more fully recovering the heat in the produced materials from the top and bottom of the stripping tower.
[0065] In the present invention, the rich solution flowing out of the cold liquid heat exchanger is divided into two streams and sent to the top of the stripping tower and the hot liquid heat exchanger respectively. One stream is sent to the top of the tower so that the feed at the top of the stripping tower has been fully preheated; the other stream is heated by the hot liquid heat exchanger and the steam heater and then sent to the bottom of the stripping tower. The hot liquid heat exchanger is used to recover the heat in the lean solution produced in the bottom of the stripping tower, and the steam heater continues to boil the liquid in the stripping tower and CO 2 The desorption process provides the required heat. Compared with the reboiler of the traditional stripping tower, the steam heater has a lower liquid residence time, which can avoid thermal degradation of the solvent. The mass of the rich solution entering the top of the stripping tower after being heated by the cold liquid heater accounts for 40%-80% of the total mass of the rich solution after being heated by the cold liquid heater, which is conducive to reducing the steam consumption of the steam heater and reducing energy consumption.
[0066] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents, materials and devices used in the examples and comparative examples are, unless otherwise stated, conventional methods, reagents, materials and devices in the art.
[0067] Example 1
[0068] This embodiment adopts Figure 1 The carbon emission system of the ethylene plant shown in the figure is used to treat the CO2 Flue gas treatment.
[0069] The carbon emission system of the ethylene plant includes a flue gas cooler, a carbon capture system and a steam generation system. The flue gas cooler is used to cool the flue gas generated by the cracking furnace of the ethylene plant using the steam cracking process. The carbon capture system includes an absorption tower, which is used to mix the flue gas with the steam generator to absorb CO. 2 The steam generation system is used to heat the working medium using solar energy, and then exchange heat between water and the heated working medium to obtain steam. The steam is used to heat the absorbed CO 2 absorbent and obtain regenerated absorbent.
[0070] The front end of the absorption tower is provided with a first flue gas cooler, a blower, a second flue gas cooler and a condensed water separator. The flue gas generated by the ethylene cracking furnace group passes through the first flue gas cooler, the blower, the second flue gas cooler, the condensed water separator in sequence and enters the bottom of the absorption tower.
[0071] The absorption tower includes a water washing section, an upper section and a lower section.
[0072] The water washing section is set at the top of the absorption tower to recover the solvent volatilized during the operation of the absorption tower. Water enters the water washing section through the water washing pump. The water after water washing enters the solution storage tank.
[0073] The solution storage tank is used to prepare the absorbent. The absorbent enters the upper end of the absorber tower through the lean liquid pump and lean liquid cooler. After the absorbent passes through the upper part of the absorber tower and contacts the flue gas in reverse, it is extracted from the lower end of the upper part of the absorber tower, cooled by the intermediate cooler, and then sent to the top of the lower part of the absorber tower.
[0074] Absorbs CO 2 The absorbent (i.e., rich solution) is extracted from the bottom of the absorption tower and is divided into two streams (a first rich solution and a second rich solution) after passing through a rich solution pump. The mass of the first rich solution accounts for 30% of the total mass of the rich solution extracted from the bottom of the absorption tower.
[0075] The carbon capture system also includes a stripping tower, a bypass heat exchanger, a cold liquid heat exchanger, a hot liquid heat exchanger and a steam heater. The bypass heat exchanger is used to exchange heat between the first rich solution and the overhead distillate of the stripping tower. The cold liquid heat exchanger is used to exchange heat between the second rich solution and the kettle liquid produced from the stripping tower. The rich solution is the CO absorbed solution produced from the bottom of the absorber tower. 2The rich solution is divided into a first rich solution and a second rich solution. The rich solution outlet of the bypass heat exchanger is connected to the top of the stripping tower. The rich solution outlet of the cold liquid heat exchanger is connected to the top of the stripping tower and the steam heater. The steam heater is connected to the bottom of the stripping tower. The rich solution heated by the cold liquid heat exchanger is divided into two streams, one of which is mixed with the rich solution heated by the bypass heat exchanger and enters the top of the stripping tower, and the other stream is heated by the hot liquid heat exchanger and the steam heater in turn and enters the bottom of the stripping tower, wherein the mass of the rich solution entering the top of the stripping tower accounts for 50% of the total mass of the rich solution heated by the cold liquid heat exchanger. The steam heater is connected to the steam generation system, and the steam used by the steam heater comes from the steam generation system. The hot liquid heat exchanger is used to exchange heat between the rich solution heated by the cold liquid heat exchanger and the bottom liquid extracted from the stripping tower. The bottom liquid extracted from the stripping tower is a lean solution. The lean solution is sequentially passed through the hot liquid heat exchanger and the cold liquid heat exchanger to exchange heat with the rich solution. The top distillate of the stripping tower (i.e. high-purity carbon dioxide) is heat exchanged with the rich solution through the bypass heat exchanger, cooled by the condenser, and then 2 After compression by the compressor unit, the carbon is removed and stored or utilized.
[0076] The steam generation system includes an energy storage medium tank group, a solar thermal field, a heat storage tank group, a working medium and a heat exchanger. The energy storage medium tank group, the solar thermal field, the heat storage tank group and the heat exchanger are connected to form a loop. The heat exchanger is used to exchange heat between water and the working medium heated by solar energy to obtain steam. The working medium is stored in the energy storage medium tank group, and after being heated by sunlight in the solar thermal field, it is stored in the heat storage tank group. The heated working medium heats the water into steam through the heat exchanger, and the working medium returns to the energy storage medium tank group.
[0077] The flue gas from the ethylene cracking furnace group is mixed, cooled to 40°C by a flue gas cooler, and then sent to the absorption tower by a blower. The operating pressure of the absorption tower is 1.0 atm. The carbon capture system includes an absorption tower. The carbon capture tower is used to absorb CO 2 The absorbent is a piperazine water solvent with a piperazine mass fraction of 40%.
[0078] The rich solution extracted from the bottom of the absorber is pressurized by the rich liquid pump and is divided into the first rich solution and the second rich solution. The first rich solution enters the bypass heat exchanger to exchange heat with the distillate from the top of the stripper, and the second rich solution enters the cold liquid heat exchanger to exchange heat with the kettle liquid from the stripper; the rich solution heated by the cold liquid heat exchanger is divided into two streams, one of which is mixed with the rich solution heated by the bypass heat exchanger and then enters the top of the stripper, and the other is heated by the steam heater and enters the kettle of the stripper. The pressure of the stripper is controlled at 1.6-2.0bar.
[0079] The top distillate of the stripping tower is high-purity carbon dioxide (CO 2The content is 99.7wt%), which is cooled to 35°C and passed through a three-stage compressor consisting of CO 2 The compressor unit compresses it to 15MPa and then transports it through pipeline for geological storage.
[0080] The steam used by the steam heater comes from the steam generation system. The steam generation system consists of a solar collector field, an energy storage medium tank group, a working medium, a heat exchanger and a heat storage tank group. The working medium is sodium nitrate. The steam temperature generated by the steam generation system is 120°C. The working medium is stored in the energy storage medium tank group. When the solar energy is sufficient, it is pumped to the solar collector field to be heated and converted into a high-temperature working medium, and the high-temperature working medium is stored in the heat storage tank group. The high-temperature working medium is exchanged with the boiler feed water in the heat exchanger to obtain low-pressure steam, which is supplied to the steam heater.
[0081] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.
Claims
1. A carbon emission method for an ethylene device, characterized in that: The carbon emission method of the ethylene device comprises the following steps: Step S1, cooling the flue gas generated by the cracking furnace of the ethylene device and sending it to a carbon capture system, wherein the carbon capture system comprises an absorption tower, wherein the flue gas contacts an absorbent for absorbing CO2 in the absorption tower, wherein the absorbent is a piperazine aqueous solution; Step S2, using steam to heat the absorbent that has absorbed CO2 to obtain a regenerated absorbent; the steam comes from a steam generation system; the steam generation system uses solar energy to heat a working medium, and then exchanges heat between water and the heated working medium to obtain the steam.
2. The carbon emission method of an ethylene device according to claim 1, characterized in that: The carbon emission method of the ethylene device also includes: extracting the absorbent that absorbs CO2 from the bottom of the absorption tower, the absorbent that absorbs CO2 is a rich solution, and dividing the rich solution into a first rich solution and a second rich solution; the carbon capture system also includes a stripping tower, a bypass heat exchanger, a cold liquid heat exchanger, a hot liquid heat exchanger and a steam heater, the kettle liquid of the stripping tower passes through the hot liquid heat exchanger and the cold liquid heat exchanger in sequence after being extracted, and the first rich solution enters the bypass heat exchanger to exchange heat with the top distillate of the stripping tower The second rich solution enters the cold liquid heat exchanger to exchange heat with the kettle liquid of the stripping tower flowing out of the hot liquid heat exchanger; the rich solution heated by the bypass heat exchanger enters the top of the stripping tower; the rich solution heated by the cold liquid heat exchanger is divided into two streams, one enters the top of the stripping tower, and the other first enters the hot liquid heat exchanger to exchange heat with the kettle liquid of the stripping tower, and then enters the kettle of the stripping tower after being heated by the steam heater, and the steam used by the steam heater comes from the steam generation system.
3. The carbon emission method of an ethylene device according to claim 2, characterized in that: The carbon emission method of the ethylene device has one or more of the following characteristics: The mass of the first rich solution accounts for 10%-40% of the total mass of the rich solution extracted from the bottom of the absorption tower; The mass of the rich solution entering the top of the stripping tower after being heated by the cold liquid heater accounts for 40%-80% of the total mass of the rich solution after being heated by the cold liquid heater; The stripping tower distills high-purity CO2 from the top of the stripping tower, wherein the CO2 content of the high-purity CO2 is ≥99.5wt%; The pressure of the stripping tower is 1.6-2.0 bar.
4. The carbon emission method of an ethylene device according to claim 1, characterized in that: The steam generation system comprises an energy storage medium tank group, a solar thermal collection field, a heat storage tank group, a working medium and a heat exchanger. The energy storage medium tank group, the solar thermal collection field, the heat storage tank group and the heat exchanger are sequentially connected to form a loop, and the working medium exists in the loop; water exchanges heat with the working medium heated by solar energy in the heat exchanger to obtain the steam.
5. The carbon emission method of an ethylene device according to claim 1, characterized in that: The piperazine mass fraction of the piperazine aqueous solution is 30%-40%; and / or The working medium is sodium nitrate, potassium nitrate, or a mixture of sodium nitrate and potassium nitrate.
6. The carbon emission method of an ethylene device according to claim 1, characterized in that: In step S1, the flue gas is cooled to 40-45°C and then fed into the absorption tower; and / or In step S1, the pressure of the absorption tower is 1.0-1.1 atm.
7. The carbon emission method of an ethylene device according to claim 1, characterized in that: In step S2, the temperature of the steam used to heat the absorbent that has absorbed CO2 is 118-120°C.
8. A carbon emission system for an ethylene device, characterized in that: The carbon emission system of the ethylene device comprises: Flue gas cooler, used to cool the flue gas generated by the cracking furnace of the ethylene plant; A carbon capture system, the carbon capture system comprising an absorption tower, the absorption tower being used to contact the flue gas with an absorbent for absorbing CO2; The steam generation system is used to heat the working medium using solar energy, and then exchange heat between water and the heated working medium to obtain steam. The steam is used to heat the absorbent that has absorbed CO2 to obtain a regenerated absorbent.
9. The carbon emission system for an ethylene device according to claim 8, characterized in that: The carbon capture system also includes a stripping tower, a bypass heat exchanger, a cold liquid heat exchanger, a hot liquid heat exchanger and a steam heater; The absorbent that absorbs CO2 extracted from the bottom of the absorption tower is a rich solution, and the rich solution is divided into a first rich solution and a second rich solution. The rich solution outlet at the bottom of the absorption tower is connected to the rich solution inlet of the bypass heat exchanger and the rich solution inlet of the cold liquid heat exchanger; The bypass heat exchanger is used to exchange heat between the first rich solution and the overhead product of the stripping tower; The stripping tower kettle liquid is extracted and sequentially passed through a hot liquid heat exchanger and a cold liquid heat exchanger, wherein the stripping tower kettle liquid inlet of the hot liquid heat exchanger is connected to the stripping tower kettle liquid outlet, and the stripping tower kettle liquid outlet of the hot liquid heat exchanger is connected to the stripping tower kettle liquid inlet of the cold liquid heat exchanger; The cold liquid heat exchanger is used to exchange heat between the second rich solution and the kettle liquid of the stripping tower flowing out of the hot liquid heat exchanger; The rich solution outlet of the bypass heat exchanger is connected to the top of the stripping tower, and the rich solution heated by the bypass heat exchanger enters the top of the stripping tower; The rich solution outlet of the cold liquid heat exchanger is connected to the top of the stripping tower and the rich solution inlet of the hot liquid heat exchanger, the rich solution outlet of the hot liquid heat exchanger is connected to the rich solution inlet of the steam heater, the rich solution outlet of the steam heater is connected to the bottom of the stripping tower, and the rich solution heated by the cold liquid heat exchanger is divided into two streams, one stream enters the top of the stripping tower, and the other stream first enters the hot liquid heat exchanger to exchange heat with the bottom liquid of the stripping tower, and then enters the bottom of the stripping tower after being heated by the steam heater; The steam inlet of the steam heater is connected to the steam generating system, and the steam used by the steam heater comes from the steam generating system.
10. The carbon emission system for an ethylene device according to claim 8, characterized in that: The steam generation system comprises an energy storage medium tank group, a solar thermal collection field, a heat storage tank group, a working medium and a heat exchanger. The energy storage medium tank group, the solar thermal collection field, the heat storage tank group and the heat exchanger are sequentially connected to form a loop, and the working medium exists in the loop; the heat exchanger is used to exchange heat between water and the working medium heated by solar energy to obtain the steam.