Marine carbon dioxide trapping pretreatment system and working principle thereof

Abstract

The invention discloses a marine carbon dioxide capture pretreatment system which comprises a marine diesel engine tail gas carbon dioxide capture pretreatment system and a marine natural gas engine tail gas carbon dioxide capture pretreatment system. The marine diesel engine tail gas carbon dioxide capture pretreatment system comprises a denitration unit, a desulfurization cooling unit, a dust removal unit, a water removal unit, a booster fan, a carbon dioxide capture system, an oxygen production unit and a circulating tail gas unit which are connected in series. The marine natural gas engine tail gas carbon dioxide capture pretreatment system comprises a denitration unit, a cooling unit, a booster fan, a carbon dioxide capture system, an oxygen production unit and a circulating tail gas unit which are connected in series. By accurately controlling the flow and proportion of air, oxygen and circulating waste gas, the treatment capacity and treatment difficulty of a rear carbon dioxide capture system are greatly reduced, and the one-time investment and operation cost of the carbon dioxide capture system are further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of marine environmental protection technology, and in particular to a marine carbon dioxide capture pretreatment system and its working principle. Background Art

[0002] As global climate change becomes increasingly severe, reducing greenhouse gas emissions has become a global consensus. As an important means of transportation, the carbon dioxide emitted by ships has a significant impact on the atmospheric environment. The International Maritime Organization has gradually introduced medium- and short-term carbon emission reduction measures based on the combination of technology and market. The use of shipboard carbon dioxide capture technology will become one of the optional paths to reduce the pressure on shipowners to fulfill their obligations. Currently available technical routes include chemical absorption, physical absorption, adsorption, membrane separation, low-temperature separation, etc. The mainstream shipboard carbon capture equipment currently developed at home and abroad mostly adopts the alcoholamine absorption method, but this method has problems such as complex system, high space occupancy, large investment, high energy consumption, and does not consider the new problems brought about by the application of new marine fuels. Therefore, the development of an efficient marine carbon dioxide capture system is of great significance to the realization of green and low-carbon development of the shipping industry. Summary of the invention

[0003] The purpose of the present invention is to address the defects and shortcomings of the prior art and provide a ship-based carbon dioxide capture pretreatment system that can treat exhaust gas emitted from ships, improve the cleanliness of the exhaust gas and the concentration of carbon dioxide, and reduce the exhaust gas treatment volume of the carbon dioxide capture system, so as to reduce the volume and operating energy consumption of the carbon dioxide capture system, thereby significantly reducing its energy consumption compared to conventional carbon dioxide capture systems and achieving green carbon reduction.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a marine carbon dioxide capture pretreatment system, the innovation of which is: comprising a marine diesel engine exhaust carbon dioxide capture pretreatment system and a marine natural gas engine exhaust carbon dioxide capture pretreatment system; the marine diesel engine exhaust carbon dioxide capture pretreatment system comprises a denitration unit, a desulfurization and cooling unit, a dust removal unit, a water removal unit, a booster fan, a carbon dioxide capture system, an oxygen production unit and a circulating exhaust unit connected in series; the marine natural gas engine exhaust carbon dioxide capture pretreatment system comprises a denitration unit, a cooling and cooling unit, a booster fan, a carbon dioxide capture system, an oxygen production unit and a circulating exhaust unit connected in series; the circulating exhaust unit comprises a circulating exhaust pipeline, a circulating exhaust regulating valve and a circulating exhaust check valve.

[0005] Furthermore, the denitration unit includes an SCR reactor, a urea solution tank, and a urea pump.

[0006] Furthermore, the desulfurization and cooling unit includes a desulfurization tower, a seawater pump, a circulating water tank, a cooling water pipeline, a water supply pipeline, an impurity treatment unit and related valves; the impurity treatment unit includes a primary separator water supply pump, a primary separator, a dryer, an intermediate liquid storage tank, a secondary separator, a secondary separator water supply pump and a control system.

[0007] Furthermore, the dust removal unit includes a dust removal device, a flushing water pump and a gray water discharge pipeline; the dust removal device mainly includes a shell, a power supply and insulation unit, a cathode top fixing device, a cathode wire fixing beam, a cathode wire, an anode fixing device, an anode tube group, a cathode bottom plate fixing locking device and a flushing device.

[0008] Furthermore, the water removal unit includes a water removal device and a drainage pipeline; the water removal device is divided into two modules: a condensation water removal unit and an adsorption water removal unit, and mainly includes a refrigerant compressor, an oil-water separator, a condenser, a liquid storage tank, a water removal device, an air-water separator, an adsorber A, an adsorber B, a vacuum pump and related valves and pipelines.

[0009] Furthermore, the oxygen production unit includes an oxygen generator fan, an oxygen generator, an oxygen regulating valve, a pressure reducing valve, an oxygen check valve, an air check valve and related pipelines.

[0010] Furthermore, the cooling unit includes a water cooler, a seawater pump, a circulating water tank, a cooling water pipeline, a water supply pipeline, an air cooler, a drainage pipeline and related valves.

[0011] The invention discloses a working principle of a marine carbon dioxide capture pretreatment system, the innovation of which lies in: comprising the working principle of a marine diesel engine exhaust carbon dioxide capture pretreatment system and the working principle of a marine natural gas engine exhaust carbon dioxide capture pretreatment system.

[0012] Furthermore, the working principle of the marine diesel engine exhaust carbon dioxide capture pretreatment system includes the following steps:

[0013] S1. The exhaust gas generated by the diesel engine contains a certain amount of nitrogen oxides, sulfur dioxide, smoke and water. The exhaust gas enters the denitrification unit for denitrification. According to the feedback results of the NOx sensor and the emission index requirements, the urea pump extracts urea solution from the urea solution tank and transports it to the SCR reactor, and sprays a certain amount of urea solution to reduce the NOx in the exhaust gas to nitrogen and water under the action of the catalyst; the denitrification unit can operate intelligently in real time according to the emission data and emission indicators, and give priority to the original denitrification unit of the ship;

[0014] S2. The exhaust gas after denitrification enters the desulfurization and cooling unit. A certain amount of seawater is stored in the circulating water tank and enters the desulfurization tower through the seawater pump. After removing the SO in the exhaust gas, 2At the same time, the exhaust gas is cooled; the cooling water pipeline forms a heat exchange coil in the circulating water tank, which can take away the heat of the circulating water and keep the seawater at a constant and suitable temperature; when the water volume in the circulating water tank is insufficient, fresh and clean seawater is added through the water supply pipeline; the impurity treatment unit can separate, compress and store the ash, oil, floating objects and other impurities in the circulating water tank in real time to maintain the circulating water quality in line with the working requirements; the desulfurization and cooling unit controls the flow of the seawater pump, cooling water and make-up water to keep the whole unit in thermal balance and reduce the SO in the exhaust gas 2 The content meets the requirements of CO2 capture systems.

[0015] S3. Normal temperature exhaust gas enters the dust removal unit, which removes dust and water from the exhaust gas, making the particulate matter content in the exhaust gas less than 1mg / m 3 ; And it shares the circulating water tank with the desulfurization and cooling unit, and the collected gray water is processed together;

[0016] S4. The clean exhaust gas enters the dehydration device, which can reduce the water content in the exhaust gas to the level allowed by the carbon dioxide capture system by condensation or adsorption. The separated water is discharged to the circulating water tank through the drainage pipeline, and the exhaust gas is transported to the booster fan;

[0017] S5. The booster fan can increase a small part of the clean exhaust gas to the pressure required by the carbon dioxide capture system, and then capture, store and utilize it in the carbon dioxide capture system; the flow of the booster fan is controlled to be 20% of the rated flow of the exhaust gas; most of the clean exhaust gas is returned to the air intake of the diesel engine through the control of the circulating exhaust gas regulating valve, and there is a circulating exhaust gas check valve before the connection between the circulating exhaust gas pipeline and the diesel engine intake pipeline, so that the circulating exhaust gas can only flow from the rear of the water removal device to the diesel engine inlet; the circulating exhaust gas regulating valve can adjust the valve opening in real time according to the flow feedback to achieve the purpose of controlling the circulating gas flow;

[0018] S6. At the same time, the oxygen production unit passes a certain flow rate and concentration of oxygen into the diesel engine intake pipeline, and mixes it with the circulating exhaust gas and air to form the intake gas of the diesel engine; the oxygen generator fan provides air with a certain flow rate and pressure for the oxygen generator. The oxygen generator adopts VPSA low-energy oxygen production technology with an oxygen concentration of more than 90%. The oxygen regulating valve can accurately control the oxygen flow rate and can quickly adjust it according to the system command; the pressure reducing valve can reduce the oxygen pressure to normal pressure so that it does not affect the diesel engine intake and prevent the air check valve from being unable to open; the air check valve can ensure that oxygen and circulating exhaust gas can only flow to the diesel engine.

[0019] Furthermore, the working principle of the marine natural gas engine exhaust carbon dioxide capture pretreatment system includes the following steps:

[0020] S1. The exhaust gas generated by the natural gas engine contains a certain amount of nitrogen oxides and water. The exhaust gas enters the denitrification unit for denitrification. According to the feedback results of the NOx sensor and the emission index requirements, the urea pump extracts urea solution from the urea solution tank and transports it to the SCR reactor, and sprays a certain amount of urea solution to reduce the NOx in the exhaust gas to nitrogen and water under the action of the catalyst; the denitrification unit can operate intelligently in real time according to the emission data and emission indicators, and give priority to the original denitrification unit of the ship;

[0021] S2. The exhaust gas after denitrification enters the cooling unit. The circulating water tank stores a certain amount of seawater, which enters the water cooler through the seawater pump, so that the exhaust gas is cooled from more than 300°C to tens of degrees or even the ambient temperature; the cooling water pipeline forms a heat exchange coil in the circulating water tank, which can take away the heat of the circulating water and keep the seawater at a constant and appropriate temperature; when the water volume in the circulating water tank is insufficient, fresh and clean seawater is added through the water supply pipeline; the exhaust gas cooled by the water cooler enters the air cooler, and further cooled, so that part of the water in the exhaust gas can be liquefied and precipitated, and returned to the circulating water tank through the drainage pipeline, and the exhaust gas is transported to the booster fan at the same time;

[0022] S3. The booster fan can increase a small part of the clean exhaust gas to the pressure required by the carbon dioxide capture system, and then capture, store and utilize it in the carbon dioxide capture system; the flow of the booster fan is controlled to be 20% of the rated flow of the exhaust gas; most of the clean exhaust gas is returned to the air intake of the diesel engine through the control of the circulating exhaust gas regulating valve, and there is a circulating exhaust gas check valve before the connection between the circulating exhaust gas pipeline and the diesel engine intake pipeline, so that the circulating exhaust gas can only flow from the rear of the water removal device to the diesel engine inlet; the circulating exhaust gas regulating valve can adjust the valve opening in real time according to the flow feedback to achieve the purpose of controlling the circulating gas flow;

[0023] S4. At the same time, the oxygen production unit passes a certain flow rate and concentration of oxygen into the diesel engine intake pipeline, and mixes it with the circulating exhaust gas and air to form the intake gas of the diesel engine; the oxygen generator fan provides air with a certain flow rate and pressure for the oxygen generator. The oxygen generator adopts VPSA low-energy oxygen production technology, with an oxygen concentration of more than 90%. The oxygen regulating valve can accurately control the oxygen flow rate and can quickly adjust it according to the system command; the pressure reducing valve can reduce the oxygen pressure to normal pressure so that it does not affect the diesel engine intake and prevent the air check valve from being unable to open; the air check valve can ensure that oxygen and circulating exhaust gas can only flow to the diesel engine.

[0024] After adopting the above structure, the beneficial effects of the present invention are:

[0025] The present invention achieves a significant reduction in the exhaust gas flow rate and an increase in the carbon dioxide concentration in the exhaust gas by precisely controlling the flow rate and ratio of air, oxygen and circulating exhaust gas without affecting the normal operation of the engine, thereby greatly reducing the processing capacity and processing difficulty of the rear carbon dioxide capture system, and further reducing the one-time investment and operating costs of the carbon dioxide capture system. Taking a 250kW marine diesel engine as an example, its exhaust gas flow rate is about 1500Nm 3 / h, if only 20% of the exhaust gas is sent to the carbon dioxide capture system, and the remaining 80% of the exhaust gas is treated with oxygen addition and mixing and recycled into the diesel engine for operation, the beneficial effects of the present invention are verified by the following theoretical calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of Example 1;

[0027] Figure 2 is a schematic structural diagram of the impurity treatment unit in Example 1;

[0028] Figure 3 It is a schematic diagram of the structure of the dust removal device in Example 1;

[0029] Figure 4 It is a structural schematic diagram of the water removal device in Example 1;

[0030] Figure 5 It is a structural schematic diagram of Example 2;

[0031] Figure 6 CO in exhaust gas at different times 2 Concentration change curve.

[0032] Description of reference numerals:

[0033] 1 diesel engine, 2 denitrification unit, 21-SCR reactor, 22 urea solution cabinet, 23 urea pump, 3 desulfurization and cooling unit, 31 desulfurization tower, 32 seawater pump, 33 circulating water tank, 34 cooling water pipeline, 35 water supply pipeline, 36 impurity treatment unit, 361 primary separator water supply pump, 362 primary separator, 363 dryer, 363 intermediate liquid storage tank, 364 secondary separator, 364 secondary separator water supply pump, 367 control system, 4 dust removal unit, 41 dust removal device, 411 shell, 412 power supply and insulation unit, 413 cathode top fixing device, 414 cathode wire fixing beam, 415 cathode wire, 416 anode fixing device, 417 anode tube group, 418 cathode bottom plate fixing locking device, 419 flushing device, 42 flushing water pump, 43 ash water discharge pipeline, 5 water removal unit, 51 water removal device, 511 refrigerant compressor, 512 oil-water separator, 513 condenser, 514 liquid storage tank, 515 water remover, 516 gas-water separator, 517 adsorber A, 518 adsorber B, 519 vacuum pump, 52 drainage pipeline, 6 booster fan, 7 carbon dioxide capture system, 8 oxygen production unit, 81 oxygen production machine fan, 82 oxygen production machine, 83 oxygen regulating valve, 84 pressure reducing valve, 85 oxygen check valve, 86 air check valve, 9 natural gas engine, 10 cooling and cooling unit, 101 water cooler, 102 air cooler, 11 circulating exhaust unit, 111 circulating exhaust pipeline, 112 circulating exhaust regulating valve, 113 circulating exhaust check valve. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings.

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] Example 1

[0037] See also Figure 1-4 The exhaust gas produced by the diesel engine 1 contains a certain amount of nitrogen oxides (NOx), sulfur dioxide (SO 2 ), smoke dust (PM), and moisture. These components have an adverse effect on the carbon dioxide capture system. Therefore, they need to be removed before the exhaust gas enters the carbon dioxide capture system.

[0038] First, the high-temperature flue gas enters the denitrification (SCR) unit 2. The SCR unit mainly consists of an SCR reactor 21, a urea solution tank 22, and a urea pump 23. According to the feedback results of the NOx sensor and the emission index requirements, the urea pump extracts urea solution from the urea solution tank and transports it to the SCR reactor, and sprays a certain amount of urea solution to reduce the NOx in the exhaust gas to nitrogen and water under the action of the catalyst; the denitrification unit can operate intelligently in real time according to the emission data and emission indicators, and gives priority to the use of the ship's original denitrification unit.

[0039] Further, the exhaust gas enters the desulfurization and cooling unit 3, which is mainly composed of a desulfurization tower 31, a seawater pump 32, a circulating water tank 33, a cooling water pipeline 34, a water supply pipeline 35, an impurity treatment unit 36, and related valves, sensors, etc. The circulating water tank stores a certain amount of seawater, which enters the desulfurization tower through the seawater pump to remove SO in the exhaust gas. 2 At the same time, the exhaust gas is cooled; the cooling water pipeline forms a heat exchange coil in the circulating water tank, which can take away the heat of the circulating water and keep the seawater at a constant and suitable temperature; when the water volume in the circulating water tank is insufficient, fresh and clean seawater is added through the water supply pipeline; the impurity treatment unit can separate, compress and store the ash, oil, floating objects and other impurities in the circulating water tank in real time to maintain the circulating water quality in line with the working requirements; the desulfurization and cooling unit controls the flow of the seawater pump, cooling water and make-up water to keep the whole unit in thermal balance and reduce the SO in the exhaust gas 2 The content meets the requirements of CO2 capture systems.

[0040] In this embodiment, see Figure 2The impurity treatment unit 36 ​​includes a primary separator water supply pump 361, a primary separator 362, a dryer 363, an intermediate liquid storage tank 364, a secondary separator 365, a secondary separator water supply pump 366 and a control system 367; when the control system sends a gray water processing signal, the primary separator water supply pump draws the gray water from the circulating water tank and sends it to the primary separator. The primary separator can preliminarily separate the particles and water, and the separated particles are sent to the dryer, and the liquid water enters the intermediate liquid storage tank. Since the liquid entering the intermediate liquid storage tank may still contain a part of the particles, the impurity treatment unit is also provided with a secondary separator; the secondary separator water supply pump sends the gray water in the intermediate liquid storage tank to the secondary separator for further processing, and the further separated particles are also sent to the dryer, and the remaining liquid water returns to the circulating water tank for reuse. The dryer is one of the important components of the impurity treatment unit, and its function is to remove the moisture in the particles screened by the separator to facilitate the storage of the particles. The dryer of the present invention is an energy-saving device, which uses the waste heat of ship engines or boiler flue gas to dry water to obtain dry and concentrated ash, thereby finally realizing the separation and storage of particulate matter and circulating water. Each device of the impurity treatment unit is equipped with a cleaning pipeline, which can automatically perform cleaning work when the equipment stops working or needs maintenance. In addition, automatic valves are installed on the pipelines between the devices, which can be opened and closed according to the instructions of the control system, realizing the automation and unmanned operation of the entire impurity treatment unit.

[0041] Furthermore, the normal temperature exhaust gas enters the dust removal unit 4, which is mainly composed of a dust removal device 41, a flushing water pump 42, and a gray water discharge pipeline 43. The dust removal unit removes dust and water from the exhaust gas, which can reduce the particulate matter content in the exhaust gas to less than 1 mg / m 3 ; and it shares the circulating water tank with the desulfurization and cooling unit, and the collected gray water is treated together.

[0042] In this embodiment, participating Figure 3The dust removal device is a marine wet electrostatic precipitator 41, and its main body mainly includes a shell 411, a power supply and insulation unit 412, a cathode top fixing device 413, a cathode wire fixing beam 414, a cathode wire 415, an anode fixing device 416, an anode tube group 417, a cathode bottom plate fixing locking device 418 and a flushing device 419. The dust removal device of the present invention has the same principle as the wet electrostatic precipitator on land, that is, after the exhaust gas containing smoke and dust enters the interior of the dust removal device, under the action of the electric field force, the particles and droplets are adsorbed into the interior of the anode tube group, and flow out of the dust removal device under the action of gravity, and the remaining clean exhaust gas is discharged from the dust removal device. Different from the wet electrostatic precipitator on land, the anode tube group and cathode wire and other components of the dust removal device of the present invention are fixed, so as to adapt to the special working conditions of the ship tilting and swaying. The functions and specific roles of each component are as follows: The shell is made of corrosion-resistant materials or general carbon steel with an anti-corrosion coating, which is mainly used for exhaust gas channels and fixing various components; the cathode system is a high-voltage discharge component of the equipment, which generates corona to charge the particle droplets, thereby separating them from the gas under the action of Coulomb force. Among them, the power supply and insulation unit is the place where the high-voltage DC power supply is introduced, and the energized part - the cathode is insulated from the shell, and it is also the total support component of the entire cathode system; the cathode top fixing device is connected to the power supply and insulation unit and fixed firmly, and will not be displaced due to the swaying and tilting of the ship; the cathode wire fixing beam is a fixing component installed on the top of the cathode wire, which can place the cathode wire in the center of the anode tube group and fix it. The cathode bottom plate fixing and locking device fixes the bottom of the cathode wire in the center of the anode tube group, connects it to the shell, and maintains insulation. As a result, the entire cathode system (including: power supply and insulation unit, cathode top fixing device, cathode wire fixing beam, cathode wire, cathode bottom plate fixing, locking device) is fixed in the designed position, and is insulated from the anode tube group and the shell. The anode fixture is welded to the shell as a whole. The anode tube group is a component for collecting particulate matter and droplets in the exhaust gas. It is placed on the anode fixture and fixed. When the equipment stops working, the flushing device flushes the cathode system and the anode tube group. The flushing water used is also taken from the circulating water tank. The exhaust gas is treated by this device, and most of the particulate matter and droplets are removed. The particulate matter and droplets flow to the circulating water tank in the form of gray water, so that the exhaust gas meets the conditions for carbon dioxide capture.

[0043] Furthermore, the clean exhaust gas enters the dehydration unit 5, which includes a dehydration device 51 and a drainage pipeline 52. The dehydration device 51 can reduce the water content in the exhaust gas to a level allowed by the carbon dioxide capture system by condensation or adsorption, and the separated water is discharged to the circulating water tank through the drainage pipeline.

[0044] In this embodiment, see Figure 4The dehydration device 51 is divided into two modules: a condensation dehydration unit and an adsorption dehydration unit, which mainly include a refrigerant compressor 511, an oil-water separator 512, a condenser 513, a liquid storage tank 514, a dehydrator 515, an air-water separator 516, an adsorber A 517, an adsorber B 518, a vacuum pump 519 and related valves and pipelines. The dehydrator is one of the important components of this device, which removes most of the moisture in the exhaust gas by condensation. Its cold source comes from the refrigerant, and the working process of the refrigerant is a conventional primary condensation system. The high-temperature and high-pressure gaseous refrigerant discharged from the refrigerant compressor is cooled to a liquid state in the condenser, and then vaporized and absorbed heat in the dehydrator to achieve the purpose of cooling the exhaust gas. The cooling water of the condenser comes from the circulating water tank of the system. The dehydration device can select different refrigerants according to the cooling temperature requirements and automatically operate at a constant temperature. The waste gas after condensation and dehydration further enters the adsorption dehydration unit. The adsorber is filled with dehydration materials. The adsorber A and adsorber B work alternately through valve switching. When one adsorber reaches saturation, it is desorbed by the vacuum pump. The desorbed water vapor and the condensed water of the condensation dehydration unit are returned to the circulating water tank of the system together.

[0045] According to the moisture requirements of different carbon dioxide capture systems, the condensation dehydration unit and the adsorption dehydration unit of the dehydration device can work separately or simultaneously.

[0046] Furthermore, the booster fan 6 can increase a small portion of the exhaust gas to the pressure required by the carbon dioxide capture system 7, and capture, store and utilize it in the carbon dioxide capture system. The flow rate of the booster fan is controlled, preferably 20% of the rated flow rate of the exhaust gas. Most of the clean exhaust gas is returned to the air intake of the diesel engine through the circulating exhaust gas unit 11. The circulating exhaust gas unit 11 includes a circulating exhaust gas pipeline 111, a circulating exhaust gas regulating valve 112 and a circulating exhaust gas check valve 113. The clean exhaust gas is controlled by the circulating exhaust gas regulating valve and returns to the air intake of the diesel engine. There is a circulating exhaust gas check valve before the connection between the circulating exhaust gas pipeline and the diesel engine intake pipeline, so that the circulating exhaust gas can only flow from the rear of the dehydration device to the diesel engine inlet. The circulating exhaust gas regulating valve can adjust the valve opening in real time according to the flow feedback to achieve the purpose of controlling the circulating gas flow.

[0047] At the same time, the oxygen production unit 8 passes a certain flow rate and concentration of oxygen into the intake pipeline of the diesel engine, and mixes with the circulating exhaust gas and air to form the intake gas of the diesel engine. The oxygen production unit 8 is composed of an oxygen generator fan 81, an oxygen generator 82, an oxygen regulating valve 83, a pressure reducing valve 84, an oxygen check valve 85, an air check valve 86, and related pipelines, sensors, control systems, etc. The oxygen generator fan provides air with a certain flow rate and pressure for the oxygen generator. The oxygen generator preferentially uses VPSA low-energy oxygen production technology with an oxygen concentration of more than 90%. The oxygen regulating valve can accurately control the oxygen flow rate and can quickly adjust it according to system commands. The pressure reducing valve can reduce the oxygen pressure to normal pressure so that it does not affect the intake of the diesel engine and prevent the air check valve from being unable to open. The air check valve can ensure that oxygen and circulating exhaust gas can only flow to the diesel engine.

[0048] In summary, when the treatment object is a diesel engine, this system performs pretreatment on its exhaust gas before carbon dioxide capture, including denitration, desulfurization, dust removal, and water removal, and circulates most (preferably 80%) of the exhaust gas for treatment, and only sends the remaining small part of the exhaust gas to the carbon dioxide capture system. A certain amount of high-concentration oxygen and air is added to the circulating exhaust gas before re-entering the engine, so that the mixed gas meets the engine's combustion requirements. In this way, the continuous circulation can make the carbon dioxide concentration in the exhaust gas entering the carbon dioxide capture system much higher than the level in conventional exhaust gas, which is convenient for the carbon dioxide capture system to capture, and at the same time reduces the total exhaust gas treatment capacity of the carbon dioxide capture system, achieving the effect of energy saving, reducing investment costs, and saving installation space.

[0049] Example 2

[0050] See also Figure 5 The exhaust gas generated by the natural gas engine 9 contains a certain amount of nitrogen oxides (NOx) and moisture. These components have an adverse effect on the carbon dioxide capture system. Therefore, they need to be removed before the exhaust gas enters the carbon dioxide capture system.

[0051] First, the high-temperature flue gas enters the denitrification (SCR) unit. The SCR unit is mainly composed of an SCR reactor, a urea solution tank, and a urea pump. According to the feedback results of the NOx sensor and the emission index requirements, the urea pump draws urea solution from the urea solution tank and transports it to the SCR reactor, and sprays a certain amount of urea solution to reduce the NOx in the exhaust gas to nitrogen and water under the action of the catalyst; the denitrification unit can operate intelligently in real time according to the emission data and emission indicators, and gives priority to the use of the ship's original denitrification unit.

[0052] Furthermore, the exhaust gas after denitrification enters the cooling unit 10, which is mainly composed of a water cooler 101, a seawater pump 32, a circulating water tank 33, a cooling water pipeline 34, a water supply pipeline 35, an air cooler 102, a drainage pipeline, and related valves, sensors, etc. The circulating water tank stores a certain amount of seawater, which enters the water cooler through the seawater pump, so that the exhaust gas is reduced from more than 300°C to tens of°C or even the ambient temperature; the cooling water pipeline forms a heat exchange coil in the circulating water tank, which can take away the heat of the circulating water and keep the seawater at a constant and appropriate temperature; when the water volume in the circulating water tank is insufficient, fresh and clean seawater is supplemented by the water supply pipeline; the exhaust gas cooled by the water cooler enters the air cooler, and is further cooled, so that part of the water in the exhaust gas can be liquefied and precipitated, and returned to the circulating water tank through the drainage pipeline, and the exhaust gas is transported to the booster fan at the same time;

[0053] Furthermore, the booster fan can increase a small portion of the clean exhaust gas to the pressure required by the carbon dioxide capture system, and capture, store and utilize it in the carbon dioxide capture system; the flow of the booster fan is controlled to be 20% of the rated flow of the exhaust gas; most of the clean exhaust gas is returned to the air inlet of the natural gas engine through the circulating exhaust gas unit, and there is a circulating exhaust gas check valve before the connection between the circulating exhaust gas pipeline and the diesel engine intake pipeline, so that the circulating exhaust gas can only flow from the rear of the water removal device to the diesel engine inlet; the circulating exhaust gas regulating valve can adjust the valve opening in real time according to the flow feedback to achieve the purpose of controlling the circulating gas flow;

[0054] At the same time, the oxygen production unit passes a certain flow and concentration of oxygen into the diesel engine intake pipeline, and mixes it with the circulating exhaust gas and air to form the intake gas of the diesel engine; the oxygen generator fan provides air with a certain flow and pressure for the oxygen generator. The oxygen generator adopts VPSA low-energy oxygen production technology with an oxygen concentration of more than 90%. The oxygen regulating valve can accurately control the oxygen flow and can quickly adjust it according to the system command; the pressure reducing valve can reduce the oxygen pressure to normal pressure so that it does not affect the diesel engine intake and prevent the air check valve from being unable to open; the air check valve can ensure that oxygen and circulating exhaust gas can only flow to the diesel engine.

[0055] In summary, when the treatment object is a natural gas engine, this system pre-treats its exhaust gas before carbon dioxide capture, mainly denitrification and water removal, which is simpler than the diesel engine pre-treatment system. Similarly, most (preferably 80%) of the exhaust gas is recycled through the action of valves and fans, and only the remaining small part of the exhaust gas is sent to the carbon dioxide capture system. A certain amount of high-concentration oxygen and air is added to the circulating exhaust gas before re-entering the engine so that the mixed gas meets the engine's combustion requirements. In this way, the continuous circulation can make the carbon dioxide concentration in the exhaust gas entering the carbon dioxide capture system much higher than the level in conventional exhaust gas, which is convenient for the carbon dioxide capture system to capture, and at the same time reduces the total exhaust gas treatment capacity of the carbon dioxide capture system, achieving the effect of energy saving, reducing investment costs, and saving installation space.

[0056] Example 3

[0057] This system calculation uses a 250KW diesel engine. According to the actual test results, the exhaust gas flow rate of this model of diesel engine is about 1500Nm 3 / h, the measured oxygen content in the exhaust gas is 13%, the carbon dioxide content is 9%, the local atmospheric oxygen content is about 21%, and the atmospheric carbon dioxide content is about 0.04%. When an oxygen generator with an oxygen concentration of 90% is selected, the oxygen generator flow rate and the concentration of carbon dioxide produced by the oil extraction machine during different operating times are calculated. The calculated quantities are shown in Table 1:

[0058] Table 1 List of calculation quantity codes for marine CO2 capture pretreatment system

[0059]

[0060] 1. Calculation of oxygen concentrator flow:

[0061] Total flow of mixed gas: Q 5 =Q 1 (Formula 1-1)

[0062] Recirculation gas flow rate: Q 4 =Q 1 ×80% (Formula 1-2)

[0063] Oxygen content of mixed gas:

[0064] Oxygen flow rate of oxygen concentrator: η 1 =Q 10 ×Q 7 (Formula 1-4)

[0065] Recirculating gas oxygen flow rate: η 2 =Q 4 ×Q 2 (Formula 1-5)

[0066] Oxygen flow rate in supplementary air: η 3 =Q 11 ×Q 8 (Formula 1-6)

[0067] Oxygen concentrator flow:

[0068] Make-up air flow: Q 11 =Q 5 -Q 4 -Q 10 (Formula 1-8)

[0069] Combining formulas 1-1 to 1-8, we can get the oxygen concentrator flow rate and supplementary air flow rate of 90% concentration in this system. The calculation results are shown in Table 2:

[0070] Table 2 90% concentration oxygen concentrator flow rate calculation results statistics

[0071]

[0072] 2. The calculation formula for the CO2 concentration in the exhaust gas entering the CO2 capture system at different times of diesel engine operation is as follows:

[0073]

[0074] Q 3 (t+1)=Q 12 (t)+Q 3

[0075] t: time (unit: h)

[0076] Take t=1,2,3..... (Formula 2-2) Then: The calculation results within 24 hours are shown in Table 3 and Figure 6 As shown:

[0077] Table 3 CO in exhaust gas at different times 2 Concentration calculation results table

[0078] t 1h 2h 3h 4h 5h 6h 7h 8h <![CDATA[Q 12 ]]> 7.20％ 12.97％ 17.58％ 21.27％ 24.22％ 26.58％ 28.47％ 29.98％ <![CDATA[Q 3 ]]> 9.00％ 16.20％ 21.97％ 26.58％ 30.27％ 33.22％ 35.58％ 37.47％ t 9h 10h 11h 12h 13h 14h 15h 16h <![CDATA[Q 12 ]]> 31.19％ 32.15％ 32.93％ 33.55％ 34.04％ 34.44％ 34.75％ 35.01％ <![CDATA[Q 3 ]]> 38.98％ 40.19％ 41.15％ 41.93％ 42.55％ 43.04％ 43.44％ 43.75％ t 17h 18h 19h 20h 21h 22h 23h 24h <![CDATA[Q 12 ]]> 35.21％ 35.37％ 35.50％ 35.61％ 35.69％ 35.76％ 35.81％ 35.85％ <![CDATA[Q 3 ]]> 44.01％ 44.21％ 44.37％ 44.50％ 44.61％ 44.69％ 44.76％ 44.81％

[0079] According to Table 3 and Figure 6 It can be seen that under the conditions based on this system, as time continues to increase, CO 2 The concentration gradually increased, finally approaching 45%.

[0080] Based on the above calculation formula, the control system of the present invention controls the flow and ratio of air, oxygen and circulating exhaust gas in real time according to the operating status of the engine, so as to achieve exhaust gas pretreatment, CO 2 Gas enrichment effect.

[0081] According to the calculation results, it can be found that the carbon dioxide capture pretreatment system of the present invention converts the original flow rate of 1500Nm 3 / h, exhaust gas with a carbon dioxide content of 9% is converted into a flow rate of 300Nm 3 / h, the carbon dioxide content of the treated gas is 45%, thereby reducing the installed volume, power and capture difficulty of the carbon dioxide capture system, which is a great improvement over the currently used system.

[0082] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A marine carbon dioxide capture pretreatment system, characterized in that: It comprises a marine diesel engine exhaust carbon dioxide capture pretreatment system and a marine natural gas engine exhaust carbon dioxide capture pretreatment system; the marine diesel engine exhaust carbon dioxide capture pretreatment system comprises a denitration unit, a desulfurization and cooling unit, a dust removal unit, a water removal unit, a booster fan, a carbon dioxide capture system, an oxygen production unit and a circulating exhaust unit connected in series; the marine natural gas engine exhaust carbon dioxide capture pretreatment system comprises a denitration unit, a cooling and cooling unit, a booster fan, a carbon dioxide capture system, an oxygen production unit and a circulating exhaust unit connected in series; the circulating exhaust unit comprises a circulating exhaust pipeline, a circulating exhaust regulating valve and a circulating exhaust check valve.

2. A marine carbon dioxide capture pretreatment system according to claim 1, characterized in that: The denitration unit includes an SCR reactor, a urea solution tank, and a urea pump.

3. A marine carbon dioxide capture pretreatment system according to claim 1, characterized in that: The desulfurization and cooling unit includes a desulfurization tower, a seawater pump, a circulating water tank, a cooling water pipeline, a water supply pipeline, an impurity treatment unit and related valves; the impurity treatment unit includes a primary separator water supply pump, a primary separator, a dryer, an intermediate liquid storage tank, a secondary separator, a secondary separator water supply pump and a control system.

4. A marine carbon dioxide capture pretreatment system according to claim 1, characterized in that: The dust removal unit includes a dust removal device, a flushing water pump and a gray water discharge pipeline; the dust removal device mainly includes a shell, a power supply and insulation unit, a cathode top fixing device, a cathode wire fixing beam, a cathode wire, an anode fixing device, an anode tube group, a cathode bottom plate fixing locking device and a flushing device.

5. A marine carbon dioxide capture pretreatment system according to claim 1, characterized in that: The dehydration unit includes a dehydration device and a drainage pipeline; the dehydration device is divided into two modules: a condensation dehydration unit and an adsorption dehydration unit, and mainly includes a refrigerant compressor, an oil-water separator, a condenser, a liquid storage device, a dehydrator, an air-water separator, an adsorber A, an adsorber B, a vacuum pump and related valves and pipelines.

6. A marine carbon dioxide capture pretreatment system according to claim 1, characterized in that: The oxygen production unit includes an oxygen generator fan, an oxygen generator, an oxygen regulating valve, a pressure reducing valve, an oxygen check valve, an air check valve and related pipelines.

7. A marine carbon dioxide capture pretreatment system according to claim 1, characterized in that: The cooling unit includes a water cooler, a seawater pump, a circulating water tank, a cooling water pipeline, a water supply pipeline, an air cooler, a drainage pipeline and related valves.

8. A working principle of a marine carbon dioxide capture pretreatment system according to any one of claims 1 to 7, characterized in that: It includes the working principle of the marine diesel engine exhaust carbon dioxide capture pretreatment system and the working principle of the marine natural gas engine exhaust carbon dioxide capture pretreatment system.

9. The working principle of the marine carbon dioxide capture pretreatment system according to claim 9 is characterized in that: The working principle of the marine diesel engine exhaust carbon dioxide capture pretreatment system comprises the following steps: S1. The exhaust gas generated by the diesel engine contains a certain amount of nitrogen oxides, sulfur dioxide, smoke and water. The exhaust gas enters the denitrification unit for denitrification. According to the feedback results of the NOx sensor and the emission index requirements, the urea pump extracts urea solution from the urea solution tank and transports it to the SCR reactor, and sprays a certain amount of urea solution to reduce the NOx in the exhaust gas to nitrogen and water under the action of the catalyst; the denitrification unit can operate intelligently in real time according to the emission data and emission indicators, and give priority to the original denitrification unit of the ship; S2. The waste gas after denitrification enters the desulfurization and cooling unit. The circulating water tank stores a certain amount of seawater, which enters the desulfurization tower through the seawater pump. While removing S02 from the waste gas, the waste gas is cooled down. The cooling water pipeline forms a heat exchange coil in the circulating water tank, which can take away the heat of the circulating water and keep the seawater at a constant and suitable temperature. When the water volume in the circulating water tank is insufficient, fresh and clean seawater is supplemented by the make-up water pipeline. The impurity treatment unit can separate, compress and store impurities such as ash, oil, and floating objects in the circulating water tank in real time to maintain the circulating water quality in accordance with the working requirements. The desulfurization and cooling unit controls the flow of the seawater pump, cooling water, and make-up water to keep the entire unit in thermal balance and make the S02 content in the waste gas meet the requirements of the carbon dioxide capture system. S3. Normal temperature exhaust gas enters the dust removal unit, which removes dust and water from the exhaust gas, making the particulate matter content in the exhaust gas less than 1mg / m 3 ; And it shares the circulating water tank with the desulfurization and cooling unit, and the collected gray water is processed together; S4. The clean exhaust gas enters the dehydration device, which can reduce the water content in the exhaust gas to the level allowed by the carbon dioxide capture system by condensation or adsorption. The separated water is discharged to the circulating water tank through the drainage pipeline, and the exhaust gas is transported to the booster fan; S5. The booster fan can increase a small part of the clean exhaust gas to the pressure required by the carbon dioxide capture system, and then capture, store and utilize it in the carbon dioxide capture system; the flow of the booster fan is controlled to be 20% of the rated flow of the exhaust gas; most of the clean exhaust gas is returned to the air intake of the diesel engine through the control of the circulating exhaust gas regulating valve, and there is a circulating exhaust gas check valve before the connection between the circulating exhaust gas pipeline and the diesel engine intake pipeline, so that the circulating exhaust gas can only flow from the rear of the water removal device to the diesel engine inlet; the circulating exhaust gas regulating valve can adjust the valve opening in real time according to the flow feedback to achieve the purpose of controlling the circulating gas flow; S6. At the same time, the oxygen production unit passes a certain flow rate and concentration of oxygen into the diesel engine intake pipeline, and mixes it with the circulating exhaust gas and air to form the intake gas of the diesel engine; the oxygen generator fan provides air with a certain flow rate and pressure for the oxygen generator. The oxygen generator adopts VPSA low-energy oxygen production technology with an oxygen concentration of more than 90%. The oxygen regulating valve can accurately control the oxygen flow rate and can quickly adjust it according to the system command; the pressure reducing valve can reduce the oxygen pressure to normal pressure so that it does not affect the diesel engine intake and prevent the air check valve from being unable to open; the air check valve can ensure that oxygen and circulating exhaust gas can only flow to the diesel engine.

10. The working principle of the marine carbon dioxide capture pretreatment system according to claim 9 is characterized in that: The working principle of the marine natural gas engine exhaust carbon dioxide capture pretreatment system includes the following steps: S1. The exhaust gas generated by the natural gas engine contains a certain amount of nitrogen oxides and water. The exhaust gas enters the denitrification unit for denitrification. According to the feedback results of the NOx sensor and the emission index requirements, the urea pump extracts urea solution from the urea solution tank and transports it to the SCR reactor, and sprays a certain amount of urea solution to reduce the NOx in the exhaust gas to nitrogen and water under the action of the catalyst; the denitrification unit can operate intelligently in real time according to the emission data and emission indicators, and give priority to the original denitrification unit of the ship; S2. The exhaust gas after denitrification enters the cooling unit. The circulating water tank stores a certain amount of seawater, which enters the water cooler through the seawater pump, so that the exhaust gas is cooled from more than 300°C to tens of degrees or even the ambient temperature; the cooling water pipeline forms a heat exchange coil in the circulating water tank, which can take away the heat of the circulating water and keep the seawater at a constant and appropriate temperature; when the water volume in the circulating water tank is insufficient, fresh and clean seawater is added through the water supply pipeline; the exhaust gas cooled by the water cooler enters the air cooler, and further cooled, so that part of the water in the exhaust gas can be liquefied and precipitated, and returned to the circulating water tank through the drainage pipeline, and the exhaust gas is transported to the booster fan at the same time; S3. The booster fan can increase a small part of the clean exhaust gas to the pressure required by the carbon dioxide capture system, and then capture, store and utilize it in the carbon dioxide capture system; the flow of the booster fan is controlled to be 20% of the rated flow of the exhaust gas; most of the clean exhaust gas is returned to the air intake of the diesel engine through the control of the circulating exhaust gas regulating valve, and there is a circulating exhaust gas check valve before the connection between the circulating exhaust gas pipeline and the diesel engine intake pipeline, so that the circulating exhaust gas can only flow from the rear of the water removal device to the diesel engine inlet; the circulating exhaust gas regulating valve can adjust the valve opening in real time according to the flow feedback to achieve the purpose of controlling the circulating gas flow; S4. At the same time, the oxygen production unit passes a certain flow rate and concentration of oxygen into the diesel engine intake pipeline, and mixes it with the circulating exhaust gas and air to form the intake gas of the diesel engine; the oxygen generator fan provides air with a certain flow rate and pressure for the oxygen generator. The oxygen generator adopts VPSA low-energy oxygen production technology, with an oxygen concentration of more than 90%. The oxygen regulating valve can accurately control the oxygen flow rate and can quickly adjust it according to the system command; the pressure reducing valve can reduce the oxygen pressure to normal pressure so that it does not affect the diesel engine intake and prevent the air check valve from being unable to open; the air check valve can ensure that oxygen and circulating exhaust gas can only flow to the diesel engine.

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