A system for purifying synthesis gas and rapeseed oil methyl ester regeneration

Abstract

The application discloses a system for purifying synthetic gas and regenerating rapeseed oil methyl ester, which regenerates the rapeseed oil methyl ester by removing impurities and tar by means of the steam method of a stripping unit, and adds the regenerated rapeseed oil methyl ester into a washing unit, so that the rapeseed oil methyl ester in the washing unit can better absorb the tar under the condition that a small amount of fresh rapeseed oil methyl ester is added into the washing unit, and the phenomenon of supersaturation is reduced as much as possible; the application also uses the regenerated rapeseed oil methyl ester and the mixed emulsion after cooling to make the moisture in the synthetic gas into condensed liquid through condensation, and capture the water-soluble pollutants of the synthetic gas through the condensed liquid; in conclusion, the application can remove the tar and the water-soluble pollutants at the same time under mild conditions, and can efficiently utilize the rapeseed oil methyl ester.

Description

Technical Field

[0001] This invention belongs to the field of syngas scrubbing technology, specifically relating to a system for purifying syngas and regenerating rapeseed oil methyl ester. Background Technology

[0002] Gasification is a thermochemical process in which organic or inorganic substances react with a gasifying agent (such as air, oxygen, or water vapor) under high-temperature conditions to produce syngas, a combustible gas containing carbon monoxide, hydrogen, methane, and other combustible gases. Based on temperature conditions, gasification can be divided into high-temperature gasification and low-temperature gasification. High-temperature gasification typically occurs above 1000℃, resulting in complete decomposition of raw material molecules and a high proportion of combustible gas components in the syngas, leading to a high calorific value. This is advantageous in large-scale power generation and chemical synthesis, where high-quality syngas is required. However, it demands equipment with high heat and corrosion resistance, resulting in high costs and limited adaptability to raw materials. Low-temperature gasification generally occurs around 700-900℃, with a milder reaction, lower equipment requirements, and lower costs. It is suitable for raw materials with low calorific value and complex composition, and the processed syngas can meet the needs of small-scale energy utilization scenarios such as distributed power generation and heating. Compared to high-temperature gasification, although its investment and operating costs are lower, it may produce byproducts such as tar and ammonia.

[0003] Among the many applications of gasification, biomass and sludge gasification have attracted significant attention. Biomass has a wide range of sources, such as crop straw and forestry waste. Its gasification can convert waste biomass into clean fuel for power generation, heating, or as a chemical feedstock, while simultaneously addressing the issue of biomass waste disposal and reducing environmental pollution. Sludge is a solid waste generated from wastewater treatment, containing a large amount of organic matter and potentially harmful substances. Gasification can reduce and render the sludge harmless, converting it into useful energy products and achieving resource recycling. However, the characteristics of biomass and sludge raw materials are complex and varied. For example, biomass has high volatile matter and low calorific value, while sludge has high moisture content and unstable composition, requiring targeted optimization of gasification processes and equipment.

[0004] Gas scrubbing is a crucial step in the gasification process. The crude syngas produced contains impurities such as tar, dust, acidic gases (e.g., hydrogen chloride), ammonia, and heavy metals. Failure to remove these impurities will severely impact the efficiency of subsequent gas utilization and the lifespan of equipment. Gas scrubbing can employ a combination of methods, including physical scrubbing (e.g., water washing, cyclone dust collection), chemical scrubbing (e.g., alkaline washing to remove acidic gases), and biological scrubbing (utilizing microorganisms to degrade tar and other organic matter). The scrubbing process requires comprehensive consideration of detergent selection, scrubbing tower design, control of operating parameters (e.g., temperature, pressure, flow rate), and wastewater treatment to achieve efficient gas purification, ensuring the syngas reaches ideal purity. This provides a reliable guarantee for the widespread application of biomass and sludge gasification technologies, better serving the energy production and environmental protection sectors. Even after the syngas is filtered by a bag filter to remove suspended solids and cooled, it still contains a large amount of gaseous tar and hydrogen chloride, which must be removed by a scrubbing tower to meet industrial standards. After washing, the syngas can be used to synthesize fuels, generate electricity, synthesize ammonia, synthesize methanol, separate high-purity hydrogen, and synthesize fertilizer raw materials through the Fischer-Tropsch reaction.

[0005] Currently, the commonly used syngas scrubbing towers in the industry include the following methods: traditional water scrubbing, packed scrubbing tower purification, cryogenic methanol scrubbing, liquid nitrogen scrubbing, combined Venturi scrubber and scrubbing tower purification, and syngas scrubbing tower purification with backflushing mechanism. Among these, traditional water scrubbing is difficult to treat due to the easy emulsification of tar; packed scrubbing tower purification occupies too much space and has high energy consumption; cryogenic methanol scrubbing has complex equipment, high energy consumption, and the risk of equipment corrosion; liquid nitrogen scrubbing is too costly, has very high equipment requirements, and consumes a lot of energy; the combined Venturi scrubber and scrubbing tower purification method has complex equipment and extremely high operation and maintenance requirements; and the syngas scrubbing tower purification method with backflushing mechanism has a complex structure and is difficult to maintain. Summary of the Invention

[0006] This invention provides a system for purifying syngas and regenerating rapeseed oil methyl ester. This system can simultaneously remove tar and water-soluble pollutants from syngas at a low temperature, and can regenerate and efficiently utilize rapeseed oil methyl ester.

[0007] This invention provides a system for purifying syngas and regenerating rapeseed oil methyl esters, comprising: The washing unit receives syngas and regenerated rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is injected from the top and flows countercurrently to the syngas. The regenerated rapeseed oil methyl ester dissolves the tar in the syngas, and the water in the syngas is condensed into condensate. The condensate captures water-soluble pollutants in the syngas, thereby purifying and discharging the syngas. At the same time, a mixed emulsion formed by rapeseed oil methyl ester and water condensate emulsion is deposited at the bottom of the washing unit. The mixed emulsion is also used to circulate the mixed emulsion, discharge part of the washing emulsion and condensate containing water-soluble pollutants, and receive fresh rapeseed oil methyl ester and settled rapeseed oil methyl ester. A settling tank is connected to a washing unit. The settling tank is used to receive a mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion. First, the mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion is separated into rapeseed oil methyl ester containing tar and washing emulsion. Then, the washing emulsion is further settled into condensate containing water-soluble contaminants. The rapeseed oil methyl ester containing tar is further settled. Finally, the rapeseed oil methyl ester at the top is transported to the washing unit. The stripping unit is connected to the washing unit and the bottom of the settling tank. The stripping unit is used to obtain tar-containing rapeseed oil methyl ester after settling. The tar and other impurities in the tar-containing rapeseed oil methyl ester after settling are removed by steam lifting to obtain regenerated rapeseed oil methyl ester, and the regenerated rapeseed oil methyl ester is transported to the washing unit.

[0008] Preferably, the washing unit includes: A scrubbing tower is used to receive syngas and regenerated rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is injected from the top and flows countercurrently with the syngas. The regenerated rapeseed oil methyl ester dissolves the tar in the syngas. Water in the syngas is condensed into condensate, which captures water-soluble pollutants in the syngas, thereby purifying and discharging the syngas. A mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion is deposited at the bottom of the scrubbing unit. The mixed emulsion is transported to a settling tank. The scrubbing tower is also used to receive fresh rapeseed oil methyl ester and settled rapeseed oil methyl ester to dilute the tar concentration in the mixed emulsion. The washing tower circulation module has one end connected to the top of the washing tower and the other end connected to the bottom of the washing tower. The washing tower circulation module is used to cool the mixed emulsion located at the bottom of the washing tower and pump it into the top of the washing tower, thereby realizing the circulation of the mixed emulsion. The washing tower circulation module is also connected to the stripping unit for cooling and conveying the regenerated rapeseed oil methyl ester to the top of the washing tower. The washing tower condensate pump and the washing emulsion discharge pump are connected to the settling tank respectively, and are used to discharge a portion of the washing emulsion and the condensate containing water-soluble pollutants from the settling tank. A detergent circulation pump is used to pump the settled rapeseed oil methyl ester into the top of the mixed emulsion within the washing tower.

[0009] Preferably, the scrubbing tower includes a scrubbing tower body, and a scrubbing tower liquid distributor and scrubbing tower packing located inside the scrubbing tower body, wherein: The washing tower liquid distributor is located at the top of the washing tower body and is used to evenly distribute the regenerated rapeseed oil methyl ester and the mixed emulsion within the washing tower packing. The washing tower packing is located below the washing tower liquid distributor. The uniformly distributed regenerated rapeseed oil methyl ester and the mixed emulsion flow downward through the washing tower packing. The syngas flows upward from the bottom of the washing tower through the washing tower packing. At the washing tower packing, the regenerated rapeseed oil methyl ester and the rapeseed oil methyl ester in the mixed emulsion flow countercurrently with the syngas. The regenerated rapeseed oil methyl ester and the rapeseed oil methyl ester in the mixed emulsion dissolve the tar in the syngas. The water in the syngas condenses with the cooled regenerated rapeseed oil methyl ester and the mixed emulsion to form condensate. The equipment captures water-soluble pollutants in the syngas through the condensate, thereby purifying the syngas.

[0010] Preferably, the settling tank includes a first settling device and a second settling device, wherein the first settling device and the second settling device are adjacent to each other, wherein: The first settling device is used to receive and settle the mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion; the tar-containing rapeseed oil methyl ester is located at the top, the washing emulsion is located in the middle, and the condensate containing water-soluble contaminants is located at the bottom. The second settling device is used to receive tar-containing rapeseed oil methyl ester from the top of the first settling device, further settle the tar-containing rapeseed oil methyl ester, and transport the rapeseed oil methyl ester at the top to the washing unit.

[0011] Preferably, the top of the settling tank is provided with a nitrogen inlet and a syngas release outlet, wherein: The nitrogen inlet is used to introduce nitrogen gas to form a nitrogen-sealing gas on the liquid surface in the first and second settling devices. When the pressure in the settling tank exceeds the set value, the pressure stabilizing device installed at the syngas release port will open to release the syngas and nitrogen sealing gas in the settling tank, ensuring that the working pressure of the settling tank does not exceed the design value.

[0012] Preferably, a spare heater is provided at the bottom of the first settling device and the second settling device, respectively.

[0013] Preferably, the stripping unit includes: The feeding module is connected at one end to the bottom of the settling tank and is used to heat the tar-containing rapeseed oil methyl ester after settling. A stripping tower, the top of which is connected to the other end of the feed module, is used to receive heated rapeseed oil methyl ester containing tar, and to use steam to remove impurities and tar from the rapeseed oil methyl ester containing tar to obtain regenerated rapeseed oil methyl ester. The discharge module is connected at one end to the bottom of the stripping tower and at the other end to the washing unit, and is used to transport the regenerated rapeseed oil methyl ester to the washing unit.

[0014] Preferably, the feeding module includes: The stripping tower feed pump has one end connected to the bottom of the settling tank and is used to pump the tar-containing rapeseed oil methyl ester into the stripping tower after settling. The detergent reheater is connected at one end to the other end of the stripping tower feed pump and is adjacent to or intersects with the pipeline that transmits the regenerated rapeseed oil methyl ester. It uses the heat of the regenerated rapeseed oil methyl ester to preheat the tar-containing rapeseed oil methyl ester. The preheater for contaminated detergent is connected at one end to the other end of the detergent reheater and at the other end to the top of the stripping tower. It uses a heat medium to reheat the preheated tar-containing rapeseed oil methyl ester and then deliver it to the top of the stripping tower.

[0015] Preferably, the stripping tower includes a stripping tower body, and a stripping tower liquid distributor and stripping tower packing located inside the stripping tower body, wherein: The stripping tower liquid distributor is located at the top of the stripping tower body and is used to evenly distribute the settled tar-containing rapeseed oil methyl ester. The stripping tower packing is located below the stripping tower liquid distributor. The uniformly distributed, settled rapeseed oil methyl ester containing tar flows downward through the stripping tower packing, while steam flows upward from the bottom of the stripping tower through the stripping tower packing. At the stripping tower packing, the settled rapeseed oil methyl ester containing tar and the steam flow countercurrently. The steam lifts the impurities and tar in the rapeseed oil methyl ester containing tar to obtain regenerated rapeseed oil methyl ester.

[0016] Preferably, the stripping tower includes a waste gas outlet at the top of the stripping tower body and a steam inlet at the bottom of the stripping tower body, wherein: The steam inlet is used to introduce steam into the stripping tower body. The exhaust outlet is used to discharge vapor containing impurities and tar.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a steam stripping unit to remove impurities and tar, thereby regenerating rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is then reintroduced into the washing unit. This allows the addition of only a small amount of fresh rapeseed oil methyl ester to the washing unit, enabling better absorption of tar and minimizing supersaturation. Furthermore, this invention utilizes the cooled regenerated rapeseed oil methyl ester and a mixed emulsion to condense water in the syngas into a condensate. The condensate then captures water-soluble pollutants from the syngas. In summary, this invention achieves simultaneous removal of tar and water-soluble pollutants under mild conditions and efficiently utilizes rapeseed oil methyl ester.

[0018] This invention utilizes a settling tank to settle a mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion, separating it into tar-containing rapeseed oil methyl ester and a washing emulsion. The tar-containing rapeseed oil methyl ester is then further settled, and the top rapeseed oil methyl ester is transported to a washing unit. The bottom settled tar-containing rapeseed oil methyl ester is then regenerated to obtain regenerated rapeseed oil methyl ester, thereby improving the utilization rate of rapeseed oil methyl ester. Attached Figure Description

[0019] Figure 1 A structural diagram of a system for purifying syngas and regenerating rapeseed oil methyl esters is provided for a specific embodiment of the present invention; Among them, 1-washing unit, 11-washing tower, 111-washing tower body, 112-washing tower distributor, 113-washing tower packing, 12-washing tower circulation module, 121-washing tower feed pump, 122-washing tower cooler, 13-washing tower condensate pump, 14-washing emulsion collection pump, 15-detergent circulation pump, 2-sedimentation tank, 21-first sedimentation device, 22-second sedimentation device, 23-first standby heater, 24-second standby heater, 3-stripping unit, 31-feeding module, 311-stripping tower feed pump, 312-detergent reheater, 313-contaminated detergent preheater, 32-stripping tower, 321-stripping tower body, 322-stripping tower liquid distributor, 323-stripping tower packing, 33-discharge module, 331-stripping tower pump. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0021] A specific embodiment of the present invention provides a system for purifying syngas and regenerating rapeseed oil methyl esters, such as... Figure 1 As shown, it includes: washing unit 1, settling tank 2 and stripping unit 3.

[0022] The washing unit 1 provided in this specific embodiment of the invention is used to receive syngas and regenerated rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is injected from the top and flows countercurrently to the syngas. The regenerated rapeseed oil methyl ester dissolves the tar in the syngas, and the water in the syngas is condensed into condensate. The condensate captures water-soluble pollutants in the syngas, thereby purifying and discharging the syngas. At the same time, a mixed emulsion of rapeseed oil methyl ester and water-condensate emulsion is deposited at the bottom of the washing unit. This emulsion is used not only to circulate the mixed emulsion, but also to discharge part of the washing emulsion and condensate containing water-soluble pollutants, and to receive fresh rapeseed oil methyl ester and settled rapeseed oil methyl ester.

[0023] In one specific embodiment, the syngas provided by this invention is obtained by burning biomass / residue in a gasification unit consisting of two interconnected chambers: a gasification furnace (bubble-forming fluidized bed) and a combustion chamber (discharge fluidized bed). The gasification furnace is fluidized by superheated steam blown in through a nozzle system located at the bottom of the gasification furnace. The biomass / residue is supplied by an alternative fuel metering and feeding system and immediately mixed with the hot, turbulent bed material in the gasification furnace. The generated syngas rises and escapes from the top of the gasification furnace, while the bed material remains within the system. The first stage of syngas cooling is designed as a radiant cooler with heat-conducting oil cooling the walls, and is part of a high-temperature cooling system. The syngas flows from top to bottom and exits the first stage cooler at approximately 560°C. The second stage of cooling is also designed as a radiant cooler with heat-conducting oil cooling the walls, and is also part of a high-temperature cooling system. The syngas flows from bottom to top and exits the second stage cooler at approximately 460°C. To proceed with the subsequent dust removal steps, the syngas needs to be further cooled to approximately 350°C.

[0024] When solid particles become so small that they can be carried away by the rising syngas flow, they constitute part of the syngas ash. The relatively coarse and heavier ash is separated and recycled in the gasifier ash hopper. The finer and relatively lighter particles are separated by a syngas filter designed as a high-temperature gas filtration device.

[0025] The synthesis gas provided in the specific embodiment of the present invention enters the washing unit 1 from the bottom after undergoing cooling and dust removal operations (temperature is 350°C, composition is mainly hydrogen, carbon dioxide, carbon monoxide, water vapor, tar, hydrogen chloride, ammonia, etc.).

[0026] The washing unit 1 provided in the specific embodiment of the present invention includes a washing tower 11, a washing tower circulation module 12, a washing tower condensate pump 13, a washing emulsion collection pump 14, and a detergent circulation pump 15.

[0027] The scrubbing tower 11 provided in this specific embodiment of the invention is used to receive syngas and regenerated rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is injected from the top and flows countercurrently with the syngas. The regenerated rapeseed oil methyl ester dissolves the tar in the syngas, and the water in the syngas is condensed into condensate. The condensate captures water-soluble pollutants in the syngas, thereby purifying and discharging the syngas. A mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion is deposited at the bottom of the scrubbing unit, and the mixed emulsion is transported to a settling tank. The settling tank is also used to receive fresh rapeseed oil methyl ester and settled rapeseed oil methyl ester to dilute the tar concentration in the mixed emulsion.

[0028] The washing tower 11 provided in a specific embodiment of the present invention includes a washing tower body 111, a washing tower liquid distributor 112 and a washing tower packing 113 located inside the washing tower body 111, wherein: The washing tower liquid distributor 112 provided in a specific embodiment of the present invention is located at the top of the washing tower body 111 and is used to uniformly distribute the regenerated rapeseed oil methyl ester and the mixed emulsion in the washing tower packing, and then flow downward through the washing tower packing 113.

[0029] In a specific embodiment of the present invention, the washing tower packing 113 is located below the washing tower liquid distributor 112. The uniformly distributed regenerated rapeseed oil methyl ester and the mixed emulsion flow downwards through the washing tower packing 113, while the syngas flows upwards from the bottom of the washing tower through the packing 113. At the washing tower packing 113, the regenerated rapeseed oil methyl ester and the rapeseed oil methyl ester in the mixed emulsion flow counter-currently with the syngas. The regenerated rapeseed oil methyl ester and the mixed emulsion dissolve the tar in the syngas. The water in the syngas condenses into a condensate after cooling by the regenerated rapeseed oil methyl ester and the mixed emulsion. The condensate captures water-soluble pollutants in the syngas, thereby purifying the syngas. The mixed emulsion formed by the rapeseed oil methyl ester and the condensate emulsion deposited at the bottom is introduced into the settling tank 2 under gravity and liquid level control. This washing tower packing 113 ensures uniform distribution of the medium and provides a large reaction surface area during the intense gas-liquid two-phase contact process. The temperature of the mixed emulsion in the washing tower 11 is 60-70℃. It is kept in continuous flow in the washing tower by a stirring device to achieve the best absorption effect and prevent phase separation in the circulation loop.

[0030] In a specific embodiment of the present invention, the washing tower circulation module 12 is connected at one end to the top of the washing tower 11 and at the other end to the bottom of the washing tower 11. The washing tower circulation module 12 is used to cool the mixed emulsion located at the bottom of the washing tower 11 and pump it into the top of the washing tower 11, thereby realizing the circulation of the mixed emulsion. Due to the replenishment of fresh rapeseed oil methyl ester and regenerated rapeseed oil methyl ester, the rapeseed oil methyl ester in the mixed emulsion can always adsorb tar, thereby achieving efficient utilization of rapeseed oil methyl ester through circulating the mixed emulsion. The washing tower circulation module 12 is also connected to the stripping unit 3, which is used to cool the regenerated rapeseed oil methyl ester and transport it to the top of the washing tower 11. Since the rapeseed oil methyl ester containing tar is regenerated through the stripping unit 3 in this specific embodiment of the present invention, the regenerated rapeseed oil methyl ester is recycled again, thereby achieving efficient removal of tar from the synthesis gas by adding only a relatively small amount of rapeseed oil methyl ester, and realizing efficient utilization of rapeseed oil methyl ester.

[0031] The washing tower circulation module 12 provided in a specific embodiment of the present invention includes a washing tower feed pump 121 and a washing tower cooler 122. One end of the washing tower feed pump 121 is connected to the bottom of the mixed emulsion in the washing tower 11, and the other end is connected to the washing tower cooler 122. The washing tower feed pump 121 is used to pump the mixed emulsion located at the bottom of the washing tower 11 into the top of the washing tower 11. One end of the washing tower cooler 122 is connected to the washing tower feed pump 121 and the stripping tower 3 respectively, and the other end is connected to the top of the washing tower 11. It is used to cool the mixed emulsion and the regenerated rapeseed oil methyl ester, and input the cooled mixed emulsion and the regenerated rapeseed oil methyl ester into the top of the washing tower 11. The cooled mixed emulsion and the regenerated rapeseed oil methyl ester can condense the moisture in the higher temperature synthesis gas. The washing tower cooler 122 can achieve the cooling effect through heat exchange of cooling water.

[0032] In a specific embodiment of the present invention, the washing tower condensate pump 13 and the washing emulsion collection pump 14 are respectively connected to the settling tank 2 to discharge a portion of the washing emulsion and the condensate containing water-soluble pollutants.

[0033] The detergent circulation pump 15 provided in the specific embodiment of the present invention is used to pump the settled rapeseed oil methyl ester into the top of the mixed emulsion in the washing tower 11. The settled rapeseed oil methyl ester is a relatively pure rapeseed oil methyl ester, which can help dilute the mixed emulsion located at the bottom of the washing tower 11.

[0034] The settling tank 2 provided in a specific embodiment of the present invention includes a first settling device 21 and a second settling device 22, wherein the first settling device 21 and the second settling device 22 are adjacent to each other, wherein: The first settling device 21 provided in the specific embodiment of the present invention is used to receive the mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion transported from the bottom of the washing tower 11 by liquid level control and gravity. During the settling process of the mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion, the washing emulsion is formed first, and the water continues to settle to form condensate. Thus, the tar-containing rapeseed oil methyl ester is located at the top, the washing emulsion is located in the middle, and the condensate containing water-soluble pollutants is located at the bottom. The tar-containing rapeseed oil methyl ester at the top overflows to the second settling device 22. The second settling device 22 provided in this specific embodiment of the invention is used to receive tar-containing rapeseed oil methyl ester from the top of the first settling device and further settle the tar-containing rapeseed oil methyl ester. The tar settles at the bottom, and the top is divided into relatively pure rapeseed oil methyl ester, that is, the settled rapeseed oil methyl ester and the tar-containing rapeseed oil methyl ester at the bottom. The rapeseed oil methyl ester at the top is transported to the bottom of the washing tower 11 to dilute the mixed emulsion, so that the mixed emulsion has the ability to adsorb tar. Then, the tar-containing rapeseed oil methyl ester at the bottom is transported to the stripping tower 3 for regeneration, thereby efficiently utilizing the rapeseed oil methyl ester.

[0035] The settling tank 2 provided in the specific embodiment of the present invention is provided with a nitrogen inlet and a syngas release port at the top. The nitrogen inlet is used to introduce nitrogen to form a nitrogen sealing gas on the liquid surface in the first settling device 21 and the second settling device 22. The syngas release port is provided with a pressure stabilizing device, which is used to release the syngas and nitrogen sealing gas in the settling tank in case of overpressure, so as to ensure that the working pressure of the settling tank does not exceed the design value.

[0036] In specific embodiments of the present invention, the bottom of the first settling device and the second settling device are respectively provided with a spare heater.

[0037] The stripping unit 3 provided in a specific embodiment of the present invention includes a feeding module 31, a stripping tower 32, and a discharging module 33.

[0038] One end of the feeding module 31 is connected to the bottom of the second settling device 22, and is used to heat the tar-containing rapeseed oil methyl ester after settling and transport it to the stripping tower 32.

[0039] The top of the stripping tower 32 is connected to the other end of the feed module 31 to receive the heated rapeseed oil methyl ester containing tar, and to use steam to remove impurities and tar from the top of the stripping tower to obtain regenerated rapeseed oil methyl ester. One end of the discharge module 33 is connected to the bottom of the stripping tower 32, and the other end is connected to the washing tower cooler 122, for conveying the regenerated rapeseed oil methyl ester to the washing unit 1.

[0040] The feeding module 31 provided in a specific embodiment of the present invention includes a stripping tower feed pump 311, a detergent reheater 312, and a contaminated detergent preheater 313.

[0041] One end of the stripping tower feed pump 311 is connected to the bottom of the second settling device 22. The stripping tower feed pump is used to pump the settled tar-containing rapeseed oil methyl ester into the stripping tower 32.

[0042] One end of the detergent reheater 312 is connected to the other end of the stripping tower feed pump 311, and is adjacent to or intersects with the pipeline that transmits recycled rapeseed oil methyl ester, for preheating tar-containing rapeseed oil methyl ester by using the heat of recycled rapeseed oil methyl ester.

[0043] One end of the contaminated detergent preheater 313 is connected to the other end of the detergent reheater 312, and the other end is connected to the top of the stripping tower 32. This is used to reheat the preheated tar-containing rapeseed oil methyl ester and then convey it to the top of the stripping tower 32. This invention utilizes the principle that the tar in the tar-containing rapeseed oil methyl ester is more soluble at high temperatures and is carried away by steam. If the temperature is too low, the steam condenses and cannot remove impurities and tar. Furthermore, this invention also utilizes recycled rapeseed oil methyl ester for heat exchange, thereby reducing the temperature of the recycled rapeseed oil methyl ester and reducing energy consumption for subsequent cooling.

[0044] The stripping tower 32 provided in a specific embodiment of the present invention includes a stripping tower body 321, a stripping tower liquid distributor 322 and a stripping tower packing 323 located inside the stripping tower body 321, wherein: the stripping tower liquid distributor 322 is located at the top of the stripping tower body 321 and is used to uniformly distribute the settled tar-containing rapeseed oil methyl ester. The stripping tower packing 323 is located below the stripping tower liquid distributor 322. The uniformly distributed, settled rapeseed oil methyl ester containing tar flows downwards through the stripping tower packing 323. Stripping steam from the steam generator enters the stripping tower from the lower side and flows counter-currently through the packing from bottom to top. The steam flows upwards from the bottom of the stripping tower through the stripping tower packing 323. At the stripping tower packing 323, the settled rapeseed oil methyl ester containing tar and the steam flow counter-currently. The steam carries away impurities and tar from the rapeseed oil methyl ester containing tar, resulting in regenerated rapeseed oil methyl ester. The evaporated impurities (such as tar) are carried out by the steam and form waste gas, which is then enriched in the stripping tower and can be sent for external treatment.

[0045] The stripping tower provided in a specific embodiment of the present invention includes a waste gas outlet disposed at the top of the stripping tower body and a steam inlet disposed at the bottom of the stripping tower body. The steam inlet is used to fill the interior of the stripping tower body with steam; the waste gas outlet is used to discharge steam containing impurities and tar.

[0046] This scheme can use rapeseed oil methyl ester to wash away tar in syngas, and can also use water from the condensate formed by the condensation of moisture contained in the flue gas to wash away hydrogen chloride and ammonia. Since the system does not have overly complex equipment (such as Venturi), the difficulty of equipment operation is significantly reduced. Since the operating temperature of the scrubbing tower and stripping tower is below 350℃, the operating conditions are not harsh and can be tolerated by ordinary tower materials. Rapeseed oil methyl ester can vaporize at a relatively low temperature, so it does not require excessive energy consumption for heating operations.

[0047] In this specific embodiment of the invention, rapeseed oil methyl ester is used as a detergent, which can effectively remove oily substances such as tar; the condensate generated during the cooling process of the washing tower is used to wash away water-soluble substances such as hydrogen chloride and ammonia; a stripping tower is used to recover rapeseed oil methyl ester, realizing the recycling of the detergent; a regenerative heat exchanger is set between the stripping tower and the washing tower to recover the waste heat from cleaning rapeseed oil methyl ester, maximizing energy utilization; a stirring device is installed in the washing tower to maintain the dynamic stability of the rapeseed oil methyl ester-condensate emulsion and prevent the emulsion from becoming turbid; the stripping tower adopts a countercurrent steam stripping process with a steam inlet temperature of 120-150℃; the settling tank has a built-in heating function to ensure that each stream flowing out of it maintains its temperature.

[0048] The specific process parameters provided in this invention are as follows: syngas inlet temperature: 180-220℃, scrubbing tower operating pressure: 0.1-0.3MPa, rapeseed oil methyl ester circulation rate: 5-10m³. 3 / h, stripping steam consumption: 0.5-1.0t / h (based on processed gas volume), pollutant removal efficiency, tar content: from 8-12g / Nm 3 Reduced to <50mg / Nm 3 HCl content: decreased from 500-1000 ppm to <10 ppm; dust content: decreased simultaneously to <10 mg / Nm³. 3 .

Claims

1. A system for purifying syngas and regenerating rapeseed oil methyl esters, characterized in that, include: The washing unit receives syngas and regenerated rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is injected from the top and flows countercurrently to the syngas. The regenerated rapeseed oil methyl ester dissolves the tar in the syngas, and the water in the syngas is condensed into condensate. The condensate captures water-soluble pollutants in the syngas, thereby purifying and discharging the syngas. At the same time, a mixed emulsion formed by rapeseed oil methyl ester and water condensate emulsion is deposited at the bottom of the washing unit. The mixed emulsion is also used to circulate the mixed emulsion, discharge part of the washing emulsion and condensate containing water-soluble pollutants, and receive fresh rapeseed oil methyl ester and settled rapeseed oil methyl ester. A settling tank is connected to a washing unit. The settling tank is used to receive a mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion. First, the mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion is separated into rapeseed oil methyl ester containing tar and washing emulsion. Then, the washing emulsion is further settled into condensate containing water-soluble contaminants. The rapeseed oil methyl ester containing tar is further settled. Finally, the rapeseed oil methyl ester at the top is transported to the washing unit. The stripping unit is connected to the washing unit and the bottom of the settling tank. The stripping unit is used to obtain tar-containing rapeseed oil methyl ester after settling. The tar and other impurities in the tar-containing rapeseed oil methyl ester after settling are removed by steam lifting to obtain regenerated rapeseed oil methyl ester, and the regenerated rapeseed oil methyl ester is transported to the washing unit.

2. The purification syngas and detergent regeneration system according to claim 1, characterized in that, The washing unit includes: A scrubbing tower is used to receive syngas and regenerated rapeseed oil methyl ester. The regenerated rapeseed oil methyl ester is injected from the top and flows countercurrently with the syngas. The regenerated rapeseed oil methyl ester dissolves the tar in the syngas. Water in the syngas is condensed into condensate, which captures water-soluble pollutants in the syngas, thereby purifying and discharging the syngas. A mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion is deposited at the bottom of the scrubbing unit. The mixed emulsion is transported to a settling tank. The scrubbing tower is also used to receive fresh rapeseed oil methyl ester and settled rapeseed oil methyl ester to dilute the tar concentration in the mixed emulsion. The washing tower circulation module has one end connected to the top of the washing tower and the other end connected to the bottom of the washing tower. The washing tower circulation module is used to cool the mixed emulsion located at the bottom of the washing tower and pump it into the top of the washing tower, thereby realizing the circulation of the mixed emulsion. The washing tower circulation module is also connected to the stripping unit for cooling and conveying the regenerated rapeseed oil methyl ester to the top of the washing tower. The washing tower condensate pump and the washing emulsion discharge pump are connected to the settling tank respectively, and are used to discharge a portion of the washing emulsion and the condensate containing water-soluble pollutants from the settling tank. A detergent circulation pump is used to pump the settled rapeseed oil methyl ester into the top of the mixed emulsion within the washing tower.

3. The purification syngas and detergent regeneration system according to claim 2, characterized in that, The scrubbing tower includes a scrubbing tower body, a scrubbing tower liquid distributor, and scrubbing tower packing located inside the scrubbing tower body, wherein: The washing tower liquid distributor is located at the top of the washing tower body and is used to evenly distribute the regenerated rapeseed oil methyl ester and the mixed emulsion within the washing tower packing. The washing tower packing is located below the washing tower liquid distributor. The uniformly distributed regenerated rapeseed oil methyl ester and the mixed emulsion flow downward through the washing tower packing. The syngas flows upward from the bottom of the washing tower through the washing tower packing. At the washing tower packing, the regenerated rapeseed oil methyl ester and the rapeseed oil methyl ester in the mixed emulsion flow countercurrently with the syngas. The regenerated rapeseed oil methyl ester and the rapeseed oil methyl ester in the mixed emulsion dissolve the tar in the syngas. The water in the syngas condenses with the cooled regenerated rapeseed oil methyl ester and the mixed emulsion to form condensate. The equipment captures water-soluble pollutants in the syngas through the condensate, thereby purifying the syngas.

4. The purification syngas and detergent regeneration system according to claim 1, characterized in that, The settling tank includes a first settling device and a second settling device, wherein the first settling device and the second settling device are adjacent to each other, wherein: The first settling device is used to receive and settle the mixed emulsion of rapeseed oil methyl ester and hydrogel emulsion; the tar-containing rapeseed oil methyl ester is located at the top, the washing emulsion is located in the middle, and the condensate containing water-soluble contaminants is located at the bottom. The second settling device is used to receive tar-containing rapeseed oil methyl ester from the top of the first settling device, further settle the tar-containing rapeseed oil methyl ester, and transport the rapeseed oil methyl ester at the top to the washing unit.

5. The purification syngas and detergent regeneration system according to claim 4, characterized in that, The settling tank is equipped with a nitrogen inlet and a syngas release outlet at its top, wherein: The nitrogen inlet is used to introduce nitrogen gas to form a nitrogen-sealing gas on the liquid surface in the first and second settling devices. When the pressure in the settling tank exceeds the set value, the pressure stabilizing device installed at the syngas release port will open to release the syngas and nitrogen sealing gas in the settling tank, ensuring that the working pressure of the settling tank does not exceed the design value.

6. The purification syngas and detergent regeneration system according to claim 4, characterized in that, A spare heater is installed at the bottom of the first settling device and the second settling device, respectively.

7. The purification syngas and detergent regeneration system according to claim 1, characterized in that, The stripping unit includes: The feeding module is connected at one end to the bottom of the settling tank and is used to heat the tar-containing rapeseed oil methyl ester after settling. A stripping tower, the top of which is connected to the other end of the feed module, is used to receive heated rapeseed oil methyl ester containing tar, and to use steam to remove impurities and tar from the rapeseed oil methyl ester containing tar to obtain regenerated rapeseed oil methyl ester. The discharge module is connected at one end to the bottom of the stripping tower and at the other end to the washing unit, and is used to transport the regenerated rapeseed oil methyl ester to the washing unit.

8. The purification syngas and detergent regeneration system according to claim 7, characterized in that, The feeding module includes: The stripping tower feed pump has one end connected to the bottom of the settling tank and is used to pump the tar-containing rapeseed oil methyl ester into the stripping tower after settling. The detergent reheater is connected at one end to the other end of the stripping tower feed pump and is adjacent to or intersects with the pipeline that transmits the regenerated rapeseed oil methyl ester. It uses the heat of the regenerated rapeseed oil methyl ester to preheat the tar-containing rapeseed oil methyl ester. The preheater for contaminated detergent is connected at one end to the other end of the detergent reheater and at the other end to the top of the stripping tower. It uses a heat medium to reheat the preheated tar-containing rapeseed oil methyl ester and then deliver it to the top of the stripping tower.

9. The purification syngas and detergent regeneration system according to claim 7, characterized in that, The stripping tower includes a stripping tower body, a stripping tower liquid distributor and stripping tower packing located inside the stripping tower body, wherein: The stripping tower liquid distributor is located at the top of the stripping tower body and is used to evenly distribute the settled tar-containing rapeseed oil methyl ester. The stripping tower packing is located below the stripping tower liquid distributor. The uniformly distributed, settled rapeseed oil methyl ester containing tar flows downward through the stripping tower packing, while steam flows upward from the bottom of the stripping tower through the stripping tower packing. At the stripping tower packing, the settled rapeseed oil methyl ester containing tar and the steam flow countercurrently. The steam lifts the impurities and tar in the rapeseed oil methyl ester containing tar to obtain regenerated rapeseed oil methyl ester.

10. The purification syngas and detergent regeneration system according to claim 9, characterized in that, The stripping tower includes a waste gas outlet at the top of the stripping tower body and a steam inlet at the bottom of the stripping tower body, wherein: The steam inlet is used to introduce steam into the stripping tower body. The exhaust outlet is used to discharge vapor containing impurities and tar.

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