A process for preparing acetic acid using carbon dioxide

Abstract

This invention discloses a process for preparing acetic acid using carbon dioxide, relating to the field of carbon dioxide emission reduction, including the following steps: S1, slag gasification; S2, deoxygenation; S3, low-temperature methanol washing; S4, low-temperature separation; S5, acetic acid generation. This application can solve the problem of utilization after carbon capture and recovery, helping to achieve the goal of carbon neutrality, and realizing a win-win situation of ecological, climatic, and economic benefits. At the same time, during the feeding process, semi-coke and limestone are mixed to ensure the reaction effect after entering the gasifier.

Description

Technical Field

[0001] This invention relates to the technical field of carbon dioxide emission reduction, specifically a process for preparing acetic acid using carbon dioxide. Background Technology

[0002] With the development of modern industry, global energy consumption has been increasing dramatically, and carbon dioxide emissions have been rising, exacerbating the deterioration of the human living environment. Carbon dioxide is not only the most important greenhouse gas, but also the most widely distributed and abundant carbon-1 resource on Earth. As an important chemical raw material, carbon dioxide can be converted into products with high economic value, such as acetic acid, through chemical processing.

[0003] In the existing technology for preparing acetic acid from carbon dioxide, the feeding system requires screening and belt metering of semi-coke before adding limestone into the gasifier. However, the limestone is difficult to mix during the addition process, which affects the reaction effect in the gasifier. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a process for preparing acetic acid using carbon dioxide, so as to solve the technical problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A process for preparing acetic acid using carbon dioxide, wherein the process includes the following steps:

[0007] Step S1: Slag gasification. Oxygen from the air separation unit is mixed with carbon dioxide from the outside in the mixing flame arrestor. The mixed gasifying agent is injected into the gasifier from the bottom of the gasifier through the nozzle for gasification. The crude CO gas from the gasifier is dedusted by a cyclone separator, then enters a metal filter, and then enters the waste heat boiler. The crude CO gas after exiting the waste heat boiler enters the gas scrubbing tower, where it is cooled and scrubbed by the gasification circulating cooling water. The crude CO gas after exiting the tower is sent to the next process section.

[0008] Step S2, deoxygenation: The crude CO gas from step S1 is pressurized and passes through a heat exchanger, an organic sulfur hydrogenation conversion reactor, and a deoxygenation reactor. While removing organic sulfur, some of the oxygen is converted and sent to the next process.

[0009] Step S3, Low-temperature methanol washing; The gas from step S2 passes through the low-temperature methanol washing unit to obtain synthesis gas, which is then sent to the next process.

[0010] Step S4, low-temperature separation: The syngas from step S3 is purified by the molecular sieve adsorber of the purification system to obtain raw material gas, and then filtered to remove mechanical impurities before entering the cryogenic separation unit to obtain product gas, and then compressed to obtain CO gas.

[0011] Step S5: Acetic acid is generated. CO gas enters the reactor. Methanol is pressurized by the methanol feed pump in the intermediate storage tank area and mixed with dilute acetic acid from the distillation process and the returned iodomethane mixture. The mixture then enters the reactor and reacts with CO to generate acetic acid.

[0012] Specifically, the slag gasification system in this technical solution mainly includes a gasifying agent inlet system, a feeding device, a gasifier body, a slag discharge system, a cooling water system, a self-generated steam system, and a CO dust removal and heat recovery system.

[0013] The low-temperature methanol wash includes a cold zone, a hot zone, a methanol emission collection system, a methanol storage system, and a refrigeration system.

[0014] Specifically, the feeding device includes a semi-coke hopper, a limestone hopper, and a metering belt conveyor. The outer walls of the semi-coke hopper and the limestone hopper are connected. The metering belt conveyor is located below the semi-coke hopper and the limestone hopper. Inclined buffer plates are provided on both inner walls of the semi-coke hopper. A discharge pipe is connected to the center of the bottom of the semi-coke hopper, and a first valve is installed on the discharge pipe. A discharge port is opened at the bottom of the limestone hopper, and a second valve is installed above the discharge port. A tilting plate is provided below the discharge port, and a weight sensor is embedded in the tilting plate. A drive chamber is opened inside the limestone hopper on one side of the discharge port, and a drive assembly is installed in the drive chamber. The execution end of the drive assembly is connected to the tilting plate. A connected stirring assembly is provided on one side of the drive assembly. The stirring end of the stirring assembly is located above the belt of the metering belt conveyor. A cleaning assembly is provided on the side of the metering belt conveyor away from the semi-coke hopper, and the cleaning end of the cleaning assembly is in contact with the bottom of the belt.

[0015] Specifically, in this technical solution, the semi-coke hopper and the limestone hopper are welded together. The drive chamber is equipped with a horizontal plate. The drive assembly includes a forward and reverse motor installed at the top of the drive chamber. The output end of the forward and reverse motor is connected to a drive shaft. The bottom end of the drive shaft passes through the horizontal plate and is connected to a transverse bevel gear. A vertical bevel gear is meshed with one side of the transverse bevel gear. A connecting shaft passes through the center of the vertical bevel gear. One end of the connecting shaft passes through the wall of the limestone hopper and is connected to a tilting plate. A drive wheel is provided on the drive shaft above the transverse bevel gear. The drive wheel is connected to the stirring assembly.

[0016] Specifically, in this technical solution, the outer wall of the horizontal plate is welded to the inner wall of the drive cavity, the forward and reverse motors are fixed to the drive cavity by bolts, the transmission shaft is connected to the output flange of the forward and reverse motors, the horizontal bevel gear and the drive wheel are both fixedly sleeved on the transmission shaft, the vertical bevel gear is fixedly sleeved on the connecting shaft, and the two ends of the connecting shaft are respectively rotatably connected to the inner wall of the drive cavity and fixedly connected to the outer wall of the flipping plate.

[0017] Specifically, the mixing assembly includes a rotating shaft located on one side of the drive shaft, a driven wheel mounted on the rotating shaft, the driven wheel meshing with the driving wheel, a mixing column connected to the bottom end of the rotating shaft through the bottom surface of the limestone hopper, a mixing blade provided on the outer wall of the mixing column, the mixing column being located above the belt of the metering belt conveyor, and baffles provided on both sides of the bottom of the limestone hopper at the mixing column, with the bottom ends of both baffles contacting the surface of the belt of the metering belt conveyor.

[0018] Specifically, in this technical solution, the top end of the rotating shaft is rotatably connected to the lower surface of the horizontal plate, the driven wheel is fixed to the rotating shaft, the stirring column is fixedly connected to the bottom end of the rotating shaft, the stirring blade is threaded and welded to the outer wall of the stirring column, and fixed rods are symmetrically welded to the top outer side of the stirring column. The top ends of the two fixed rods are each embedded with a ball bearing. The bottom surface of the limestone hopper is provided with an annular groove, and the upper half of the two balls are located in the annular groove and are rotatably connected to it.

[0019] Specifically, the cleaning component includes a mounting plate welded to the frame of the metering belt conveyor. A groove is provided on one side of the top of the mounting plate, and a slider is slidably disposed in the groove. A bracket is welded to the side of the slider away from the groove, and a brush is adhered to the top of the bracket. The brush is in contact with the belt of the metering belt conveyor. A snap-fit ​​cavity is provided in the mounting plate on one side of the groove, and an electromagnet is installed on the side of the mounting plate away from the bracket. The electromagnet is located in the snap-fit ​​cavity.

[0020] Specifically, the locking cavity is provided with a movable plate, the top and bottom of which are both mounted on guide rods. An iron sheet is embedded in the center of the side of the movable plate near the electromagnet, and the iron sheet is magnetically connected to the electromagnet. Springs are sleeved on the outer side of the two guide rods near the electromagnet. A locking block is provided in the center of the other side of the movable plate. A locking groove is opened on the side of the slider away from the bracket. The locking block passes through the locking cavity and is locked and connected to the locking groove.

[0021] Specifically, in this technical solution, the outer wall of the movable plate is in contact with and slidably connected to the inner wall of the snap-fit ​​cavity, the movable plate is slidably connected to the guide rod, both ends of the two guide rods are fixedly connected to the inner wall of the snap-fit ​​cavity, both ends of the two springs are fixedly connected to the snap-fit ​​cavity and the movable plate respectively, and the snap block is welded to the movable plate.

[0022] In summary, the present invention has the following main beneficial effects:

[0023] This application can solve the problem of utilization after carbon capture and recovery, help achieve the goal of carbon neutrality, and achieve a win-win situation in terms of ecological, climate and economic benefits.

[0024] The drive component can continuously drive the tilting plate to reciprocate, so that the weighed limestone can fall more evenly onto the metering belt conveyor. At the same time, it can drive the stirring component to mix the passing semi-coke and limestone to ensure the reaction effect after entering the gasifier.

[0025] After screening, the semi-coke falls from the semi-coke hopper onto the metering belt conveyor. At this time, the second valve in the limestone hopper opens, allowing the limestone to fall onto the tilting plate for weighing. When a certain amount is reached, the second valve closes, and the forward and reverse motors in the drive assembly start working. The forward and reverse motors drive the horizontal bevel gear and the drive wheel to rotate reciprocally through the transmission shaft. The horizontal bevel gear drives the meshing vertical bevel gear to rotate, and the connecting shaft follows the rotation of the vertical bevel gear to drive the tilting plate to deflect reciprocally, so that the weighed limestone falls evenly onto the metering belt conveyor below. At this time, the rotation of the drive wheel drives the driven wheel in the stirring assembly to rotate. The driven wheel drives the stirring column to rotate reciprocally through the rotating shaft, so that the stirring blades mix the passing semi-coke and limestone. The mixed semi-coke and limestone enter the gasifier from the top to react inside. Attached Figure Description

[0026] Figure 1 This is a simplified process flow diagram of the present invention;

[0027] Figure 2 This is a flowchart of the present invention;

[0028] Figure 3 This is a structural diagram of the feeding device of the present invention;

[0029] Figure 4 This is a front view structural diagram of the present invention;

[0030] Figure 5 This is a schematic diagram of the driving component of the present invention;

[0031] Figure 6 This is an enlarged view of point A in the present invention;

[0032] Figure 7 This is an enlarged view of section B of the present invention;

[0033] Figure 8 This is a schematic diagram of the cleaning component of the present invention.

[0034] Figure Descriptions: 1. Feeding device; 2. Semi-coke hopper; 201. Buffer plate; 202. Feeding pipe; 2021. First valve; 3. Limestone hopper; 301. Discharge port; 3011. Second valve; 302. Tilting plate; 3021. Weight sensor; 303. Drive chamber; 3031. Horizontal plate; 304. Annular groove; 305. Baffle; 4. Drive assembly; 401. Connecting shaft; 402. Vertical bevel gear; 403. Horizontal bevel gear; 404. Transmission shaft; 405. Drive wheel; 406. Forward and reverse... 5. Motor; 501. Stirring assembly; 502. Driven wheel; 503. Stirring column; 5031. Stirring blade; 504. Fixed rod; 5041. Ball bearing; 6. Cleaning assembly; 601. Mounting plate; 6011. Slide groove; 6012. Snap-fit ​​cavity; 602. Slider; 6021. Snap-fit ​​groove; 603. Bracket; 6031. Brush; 604. Electromagnet; 605. Guide rod; 6051. Spring; 606. Movable plate; 6061. Iron sheet; 607. Clamping block; 7. Metering belt conveyor. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] The embodiments of the present invention will now be described.

[0037] Example

[0038] Please see Figure 1 and Figure 2 A process for preparing acetic acid using carbon dioxide, the process comprising the following steps:

[0039] Step S1: Slag gasification;

[0040] The slag gasification system mainly includes a gasifying agent inlet system, a feeding device 1, a gasifier body, a slag discharge system, a cooling water system, a self-generated steam system, and a CO dust removal and heat recovery system.

[0041] The gasifying agent inlet system mainly consists of a carbon dioxide buffer tank, an oxygen buffer tank, and a mixing flame arrestor. Oxygen from the air separation unit enters the oxygen buffer tank, then flows through a regulating valve into the mixing flame arrestor, where it mixes with external carbon dioxide. The mixed gasifying agent is then injected into the gasifier from the bottom through a special nozzle for gasification. The CO2 / O2 ratio is a crucial control parameter. The heat generated by the large-scale combustion in the oxidation layer carries the heat required for gasification into the reduction reaction layer. Changing the CO2 / O2 ratio essentially adjusts and controls the temperature of the combustion process. By controlling the gasifier's operating temperature at its optimal value, high production capacity and optimal economic benefits can be achieved. The determination of the CO2 / O2 ratio is primarily based on the melting point of the raw materials and the melting characteristics of the ash, followed by the reactivity of the raw materials. The adjustment of the CO2 / O2 ratio is mainly based on the ash discharge status of the gasifier.

[0042] The gasifier mainly consists of three parts from top to bottom: the feeding device, the gasifier body, and the slag removal system. Semi-coke, after being screened and metered via conveyor belt, is mixed with a certain amount of limestone and enters the rooftop silo. It then enters the feeding lock, and by opening the lower valve of the feeding lock, it enters the gasifier from the top. The feeding lock is equipped with carbon dioxide pressurization protection to prevent gas leakage.

[0043] The gasifier shell is a jacketed structure with refractory bricks, and the upper part of the jacket connects to the steam drum of the jacketed boiler. A crude CO gas outlet is located at the top of the gasifier. The reaction zones within the gasifier, from top to bottom, are: drying layer, carbonization layer, methanation layer, reduction layer, oxidation layer, and slag zone. The gasifying agent is introduced into the slag zone from the bottom of the gasifier, reacting upwards sequentially. Passing through the upper reaction zone, it produces crude CO gas which enters the downstream dust removal and heat recovery system. As the semi-coke in the slag and oxidation layers is continuously consumed, the semi-coke in the upper layer continuously falls. The slag layer is the most intensely reacting area in the gasifier, where the main reactions are:

[0044] C + O2 → CO2;

[0045] 2C + O2 → 2CO;

[0046] 2CO + O2 → 2CO2;

[0047] C + H₂O → CO + H₂;

[0048] To increase operating temperature, achieve liquid slag discharge, obtain high gasification intensity, and reduce consumption, a low CO2 / O2 ratio is generally maintained. The core reaction temperature in the slag zone is 1600℃~2000℃. Under high oxygen and high temperature conditions, the carbon in the semi-coke is almost completely burned off. The ash and flux in the semi-coke reach above the flow temperature and are discharged in liquid form through the slag outlet. The gas generated in the slag layer carries a large amount of heat and residual oxygen and carbon dioxide upwards into the combustion zone for combustion. The combustion zone mainly undergoes oxidation reactions, which are the same as those in the slag layer. The reaction temperature range of the oxidation layer is 1100℃~1600℃. The reduction layer is the main gasification zone for CO production, with a reaction temperature range of 900℃~1600℃. In this range, CO reactions mainly occur, and carbon dioxide carrying high heat is reduced. The main chemical reactions are:

[0049] C + CO₂ → 2CO;

[0050] Increasing the reaction temperature of the slag and oxide layers increases the heat carried by the generated gas, promoting the carbon reduction reaction in the reduction layer and ultimately leading to an increase in the CO concentration in the gas. The methanation layer operates at temperatures ranging from 900℃ to 1100℃, where methanation reactions primarily occur.

[0051] C + 2H₂ → CH₄;

[0052] CO + 3H₂ → CH₄ + H₂O;

[0053] 2CO + 2H2 → CH4 + CO2;

[0054] CO2 + 4H2 → CH4 + 2H2O;

[0055] Because the furnace is under low pressure, the methanation reaction is less intense, resulting in a lower concentration of methane. Above the methane layer is the pyrolysis layer, with a temperature range of 700℃ to 900℃, where pyrolysis and a small amount of CO reaction occur (CO + H₂O → H₂ + CO₂). The pyrolysis products are mainly H₂S, H₂, CO, CH₄, CmHn, etc. Above the pyrolysis layer is the drying layer, with a temperature range of 400℃ to 700℃, where high-temperature CO is used to countercurrently dry the semi-coke entering the furnace.

[0056] The lower end of the gasifier houses the slag discharge system, primarily composed of a slag-supporting combustion chamber, a quench chamber, and a slag collection tank. The main function of the slag-supporting combustion chamber is to generate high-temperature flue gas through the combustion of oxygen and fuel gas, maintaining the slag discharge port at a high temperature to ensure good slag fluidity and smooth discharge. Simultaneously, the high-temperature flue gas generated by combustion possesses momentum, which can support a certain height of liquid slag, ensuring the slag melting zone of the gasifier remains in a high-temperature, heat-storing state, thus aiding slag melting. When the potential energy of the liquid slag exceeds the dynamic pressure head of the combustion flue gas, the liquid slag is discharged from the slag outlet. The slag-supporting combustion chamber is equipped with a pressure relief port, which can be used to control slag discharge and regulate the pressure within the combustion chamber and the height of the liquid slag in the gasifier. Flue gas released during start-up and shutdown is discharged after water cooling in the quench chamber. The burners in the combustion chamber need to possess characteristics such as long lifespan and high stability to ensure safe and stable gasification operation.

[0057] After passing through the slag-collecting combustion chamber, the liquid slag enters the quench tank for quenching, forming harmless vitreous slag that enters the slag discharge hopper. The slag in the slag collection tank is discharged periodically (approximately every 4 hours) and finally discharged into the slag remover. The quenching of the liquid slag in the quench tank causes the quench water temperature to rise. When the water temperature rises significantly, a large amount of water vapor is generated in the quench tank during slag discharge. This water vapor rises and mixes with the high-temperature flue gas in the combustion chamber, lowering the flue gas temperature, affecting the slag collection effect, and consuming fuel. Therefore, a cooling circulating water system is designed in the quench tank to ensure the quench water is kept at a lower temperature.

[0058] The crude CO gas exiting the gasifier has a temperature of approximately 300-400℃ and a pressure of approximately 80 kPa(g). It is discharged from the top of the furnace, passes through a cyclone separator for dust removal, and then enters a metal filter to reduce the dust concentration in the crude CO gas to 5 mg / Nm³. 3 The gas then enters the waste heat boiler, where the sensible heat of the crude CO gas is recovered, and steam is produced as a byproduct. This steam is combined with the steam produced byproducts from the gasifier jacket and superheated to 200-220°C in the upper section of the waste heat boiler before being sent to other systems. The crude CO gas exiting the waste heat boiler has a temperature of approximately 150-200°C and enters the gas scrubbing tower, where it is cooled and scrubbed by circulating cooling water from the gasification unit. The temperature is reduced to ≤45°C, and any remaining trace amounts of dust and tar are washed away. The crude CO gas exiting the scrubbing tower then enters the CO gas main through a water seal and is sent to the next processing section.

[0059] The water discharged from the bottom of the gas scrubbing tower is piped to the gasification circulating water treatment section, and the treated gasification circulating water is then transported back to the gasification section for continued recycling.

[0060] Description of the quench water flow path: Hot water from the quench tank (approximately 80m³ per boiler) 3The quench water, heated to approximately 40–60°C, is filtered to remove any entrained slag. It is then pressurized by a quench water circulation pump and sent to a quench water heat exchanger, where it is cooled to 30–40°C with clean circulating water. The cooled quench water is then returned to the quench tank. Because the quench water comes into contact with the high-temperature slag in the quench tank, some of it evaporates and participates in the reaction. Therefore, a certain amount of clean circulating water needs to be added to the quench tank, approximately 1 m³ per furnace. 3 / h.

[0061] Multipurpose water flow description: Water exiting the multipurpose water buffer tank (approximately 30m³ per boiler) 3 The hot water (approximately 40-60°C) is pressurized by a multi-purpose water circulation pump and then split into three streams: the combustion section jacket, the slag outlet jacket, and the oxygen vapor nozzle jacket. The hot water from these three points is then sent to a multi-purpose water heat exchanger, where it is cooled to 30-40°C with clean circulating water before entering the multi-purpose water buffer tank. The multi-purpose water system operates in a closed-loop circulation system, generally with no loss.

[0062] Step S2, deoxygenation;

[0063] The crude CO gas from step S1 is heated to 180-250°C by heat exchanger E101 at a pressure of 2.2 MPa and a certain temperature, and then enters the organic sulfur hydrogenation conversion reactor R101A / B. Under the action of the catalyst, organic sulfur is removed and some of the oxygen is converted.

[0064] Considering the two reactors are connected in series / parallel, the gas temperature exiting the hydroconversion reactor R101A / B is 210-310℃. After entering the heat exchanger E102 and being heated to 210-280℃, it enters the deoxidation reactor R102A / B. Under aluminum-based platinum sulfide operation, it is ensured that the outlet oxygen is removed to below 1ppm and COS is removed to below 10ppm, meeting the technical requirements. The gas temperature exiting the deoxidation reactor R102A / B is 230-300℃. After passing through the heat exchanger E103, it is heated to below 45℃ and sent to the next process.

[0065] Step S3: Low-temperature methanol wash;

[0066] 1) Cold zone:

[0067] The scrubbing tower (T1601), flash tank (V1602), and H2S concentration tower (T1603), along with related equipment, are referred to as the cold zone because their operating temperatures are below 0°C.

[0068] Pre-cooling of raw material gases and absorption of CO2, H2S, etc.:

[0069] The raw gas enters the methanol washing process. To prevent the moisture in the raw gas from freezing during the pre-cooling process, methanol is injected into the raw gas. The raw gas passes through the raw gas cooler (E1601) and exchanges heat with the purified gas and tail gas to cool down. Then it enters the washing tower (T1601). The liquid phase separated at the bottom of the tower is a condensate containing methanol / water. The condensate is sent to the methanol / water separation tower (T1605) in the hot zone.

[0070] H2S and COS in the feed gas are absorbed in the desulfurization section of the scrubbing tower (T1601), and the H2S+COS concentration in the gas exiting the desulfurization section is less than 0.1 mg / Nm³. 3 The gas is then introduced into the upper decarbonization section of the scrubbing tower (T1601). The scrubbing liquid in the desulfurization section comes from sulfur-free, CO2-rich methanol after CO2 absorption in the decarbonization section. H2S and COS have higher solubility in methanol than CO2. After absorbing H2S and COS, it becomes sulfur-rich methanol, which is drawn from the bottom of the desulfurization section, cooled by the sulfur-containing methanol-propylene cooler (E1603), and then sent to the flash tank (V1602) after depressurization.

[0071] The desulfurized feed gas enters the decarbonization section, where all CO2 is absorbed by the low-temperature lean methanol from the top of tower T1601. The purified gas from the top of tower T1601 has a CO2 content of less than 20 ppm and is sent out of the boundary area. The heat of solution generated by CO2 absorption partially raises the methanol temperature, while part of it is removed by the inter-stage cooler (E1606) and inter-stage propylene cooler (E1605) of the scrubbing towers. All the rich methanol discharged from the bottom of the decarbonization section enters the desulfurization section.

[0072] Swelling of methanol-rich materials:

[0073] In addition to CO2, H2S, and COS, some CO, H2, and other gases usually dissolve in the methanol-rich material leaving the scrubbing tower (T1601). To recover this CO and H2, the methanol-rich material must be pre-cooled and then expanded under reduced pressure. The methanol-rich material exiting the bottom of the desulfurization section is called sulfur-containing methanol-rich material because it contains H2S and COS. This sulfur-containing methanol-rich material first undergoes heat exchange in the sulfur-containing methanol-propylene cooler (E1603), then is cooled, reduced in pressure, and enters the flash tank (V1602) for flash evaporation, desorbing some of the gas. The desorbed gas exiting the flash tank (V1602) is returned to the upstream compressor.

[0074] H2S Concentration:

[0075] The sulfur-containing methanol exiting the flash tank (V1602) continues to be depressurized and enters the top of the H2S concentration tower (T1603), where it flows downwards and desorbs. At the bottom of the upper section of the concentration tower, it is drawn out by a methanol pump (P1601A / B) and exchanged with the regenerated lean methanol in the lean methanol cooler II (E1608). After being cooled by the inter-section cooler (E1606) of the washing tower, the methanol drawn from the absorption tower section has a higher temperature, causing the CO2 and other gases dissolved in the methanol to desorb. The gas and liquid are depressurized together and sent to the upper part of the lower section of the H2S concentration tower (T-1603). In this section, nitrogen stripping is used to desorb CO2, thereby achieving the purpose of H2S concentration.

[0076] Nitrogen and the extracted gas enter the upper section of the H2S concentration tower (T1603) via a riser plate, where they mix with CO2 gas desorbed from methanol at the top of the riser plate and exit the top of the H2S concentration tower (T1603) as tail gas. After recovering its cooling capacity in the feed gas cooler (E1601), the tail gas merges with the acidic gas at the top of the thermal regeneration tower (T1604).

[0077] 2) Hot Zone:

[0078] The thermal regeneration tower (T1604), methanol / water separator (T1605), and related equipment are referred to as the hot zone because their operating temperatures are above 0°C.

[0079] Methanol regeneration:

[0080] The bottom liquid from the H2S concentration tower (T1603) is pressurized by methanol pump #3 (P-1603A / B), filtered through a rich methanol filter (S1602), heated by lean methanol cooler I (E1609), and then heated by heat exchange with the feed heater of the thermal regeneration tower (E1610) before entering the thermal regeneration tower (T1604). In the upper section of the tower, the rich methanol is heated to boiling by methanol vapor from the bottom of the tower and methanol vapor from the methanol / water separator (T1605). At this time, all dissolved H2S, COS, and CO2 are desorbed. The methanol vapor generated in the reboiler (E1611) of the thermal regeneration tower and the methanol vapor from the methanol / water separator (T1605) not only heat the rich methanol but also provide the heat required for the desorption of H2S, COS, and CO2 from the rich methanol. Excess methanol vapor rises to the top of the tower along with the H2S, COS, and CO2.

[0081] The exhaust gas containing H2S, COS, CO2, and methanol vapors at the top of the thermal regeneration tower (T1604) is cooled by the H2S fraction condenser (E1612) and then enters the thermal regeneration tower top reflux tank (V1606). Gas-liquid separation occurs here, and the separated condensate is pressurized by the thermal regeneration tower reflux pump (P1606A / B) and sent to the top of the thermal regeneration tower as reflux liquid. The gas exchanges heat with the cold H2S fraction in the H2S fraction cooler (E1614), and is further cooled by the H2S fraction propylene cooler (E1613) before entering the H2S gas separator (V1605) for gas-liquid separation. The liquid phase flows to the bottom of the H2S concentration tower (T-1603), while the gas phase, containing H2S fraction, is cooled by the H2S fraction cooler (E1614) and then discharged as acidic gas. However, during start-up, abnormal operation, or when the sulfur content in the feed gas is low, to ensure that the H2S concentration in the acidic gas meets the requirements, a portion of the gas phase is sent to the lower part of the H2S concentration tower, and the other portion is sent out of the boundary area after recovering the cold energy through the H2S fraction cooler (E1614). When the system is overpressurized, some gas can be introduced into the flare system.

[0082] The methanol in the bottom liquid of the thermal regeneration tower (T1604), i.e., lean methanol, is divided into two streams: ① One stream of lean methanol is cooled by the feed heater (E1610) of the thermal regeneration tower and then sent to the lean methanol tank (V1604). The lean methanol pump (P1604A / B) draws the lean methanol from the lean methanol tank (V1604), pressurizes it, and then cools it through the lean methanol water cooler (E1618). After that, it is divided into two streams again: the majority of it is cooled by lean methanol cooler I (E1609) and lean methanol cooler II (E1608) and then enters the upper part of the scrubbing tower (T1601) for circulation; a very small stream is injected into the feed gas. ②Another stream of lean methanol is pressurized by the bottom pump of the thermal regeneration tower (P1605A / B), filtered by the lean methanol filter (S1601), and heated by the methanol / water separator feed heater (E1616) before being sent to the methanol / water separator (T1605).

[0083] In the methanol / water separator (T1605), methanol and water are separated by distillation using a heat source provided by the reboiler (E1615). Methanol vapor leaves the top of the methanol / water separator (T1605) and enters the thermal regeneration tower (T1604), while the wastewater in the bottom of the tower is discharged out of the boundary area.

[0084] The flow rate of lean methanol entering the methanol / water separator (T1605) is adjusted according to the water content in the circulating methanol. That is, when the water content in the circulating methanol is high, the amount of lean methanol is increased appropriately so that the water content in the circulating methanol is reduced to the design value as soon as possible.

[0085] The reflux liquid at the top of the methanol / water separator (T1605) comes from the reflux tank (V1606) of the thermal regeneration tower. Since this reflux liquid is water-free, it helps to reduce the water content in the gas exiting from (T1605). The reflux liquid flow rate can be adjusted according to the water content in the gas exiting from the top of (T1605); that is, when the water content is high, the reflux liquid flow rate can be increased appropriately, and vice versa.

[0086] 3) Methanol emission collection system:

[0087] All methanol discharged from the low-temperature methanol washing process is collected in the waste methanol underground tank (V1608) and then pumped to the methanol storage tank in the methanol tank area by the underground tank pump (P1608).

[0088] 4) Methanol storage system (not within the methanol washing area):

[0089] The fresh methanol used for cryogenic methanol washing comes from methanol storage tanks in the tank area outside the boundary. During shutdowns and maintenance of the cryogenic methanol washing process, the methanol in the system is sent back to the methanol storage tanks.

[0090] 5) Refrigeration system (not within the methanol washing area):

[0091] The cooling required for the low-temperature methanol washing system is provided by an ice machine.

[0092] Step S4: Low-temperature separation;

[0093] 1. Synthesis gas from the low-temperature methanol washing unit passes through the molecular sieve adsorber (D16001A / B) in the front-end purification unit. Trace amounts of CO2 and methanol are removed from the synthesis gas in the molecular sieve before entering the cold box to prevent them from freezing in the cold box and causing blockage of the low-temperature equipment and pipelines.

[0094] 2. The molecular sieve adsorber consists of two units, each containing a molecular sieve. One unit is used while the other is regenerated, and the switching is achieved automatically by a programmable controller. The adsorption cycle is 12 hours, and the regeneration cycle is 12 hours. The gas used for molecular sieve regeneration is conventionally considered to be 0.4 MPaG low-pressure nitrogen. A regeneration gas heater E16006A / B and a regeneration gas cooler E16007, as well as a complete set of switching instruments and valves are required.

[0095] 3. The regeneration process of the molecular sieve adsorption device is generally divided into two main stages:

[0096] A. Heating Stage: Low-pressure nitrogen gas from the boundary area is heated to approximately 200°C in the regenerated gas heater. The hot gas is then discharged through the adsorber. CO2 and trace amounts of methanol are released and carried away by the regenerated gas.

[0097] B. Cooling Stage: After the heating stage, low-pressure nitrogen gas from the boundary area (bypassing the regeneration gas heater) cools the hot adsorbent. The regeneration gas is then fed into the regeneration gas cooler. After the regeneration process, the regenerated adsorber can be used for adsorption again.

[0098] 4. The raw gas, after being purified by molecular sieve adsorption, is filtered to remove mechanical impurities before entering the cold box.

[0099] 5. The feed gas from the deep cryogenic separation unit sequentially enters heat exchangers E16001AB, E16003, E16004, and E16002 within the cold box. After being cooled to a certain temperature, it is divided into two parts. One part returns to heat exchanger E16002 for reheating and partial evaporation. The two streams then enter different positions of the stripping tower T16001. The liquid separated at the bottom of the stripping tower is mainly carbon monoxide, while the gas at the top is partly flash vapor. This gas is reheated to room temperature via E16002 and E16001AB to recover the cooling capacity before exiting the cold box.

[0100] 6. After the liquid at the bottom of the stripping tower T16001 is throttled, it is reheated by the heat exchanger E16002 and then enters the demethanizer tower T16002 for distillation. The CO product is obtained at the top of the demethanizer tower and is reheated to room temperature by E16002 and E16001AB to recover the cold energy, and then exits the boundary area.

[0101] 7. CO compressor;

[0102] The crude methane liquid obtained from the bottom of the demethanizer is reheated to room temperature by E16002 and E16001AB to recover the cold energy before exiting the cold box and can be used as fuel.

[0103] 8. At the same time, the stripping tower and the demethanizer tower are respectively equipped with bottom reboilers, and the heat for both reboilers is provided by the cooling of the feed gas;

[0104] 9. Since the system operates at low temperatures, a CO compressor is used for cyclic refrigeration to supplement the cooling capacity in order to maintain the system's energy balance. Due to the low temperature operation of the system, there is still cold loss after using a cold box for insulation and temperature difference loss in the heat exchanger, so a small amount of liquid nitrogen needs to be added to provide cooling capacity.

[0105] 10. Liquid nitrogen also needs to be added for initial cooling of the cold box during startup.

[0106] 11. Because the cold box operates at low temperatures, materials cannot be directly discharged into the flare system in case of shutdown or abnormal conditions. An emergency discharge system is required, including a cold liquid buffer tank V16001 and a flare gas heater E16008. The cold materials enter the flare system after passing through these two devices.

[0107] The syngas from step S3 is purified by the molecular sieve adsorber of the purification system to obtain raw material gas, and then filtered to remove mechanical impurities before entering the cryogenic separation unit to obtain product gas, and then compressed to obtain CO gas.

[0108] S5, acetic acid is generated;

[0109] CO gas with a content ≥98.5% (mol) and a pressure of 3.4 MPa enters the reactor. Methanol, pressurized by the methanol feed pump in the intermediate storage tank, is mixed with dilute acetic acid from the distillation process and returned iodomethane solution before entering the reactor. In the reactor, the mixture reacts thoroughly with CO to produce acetic acid. Unreacted CO gas, saturated organic vapors, and non-condensable gases are discharged from the top of the reactor, pass through the reactor condenser, and then enter a high-pressure separator for gas-liquid separation. The gas phase containing a small amount of saturated organic vapors is discharged from the top of the high-pressure separator and sent to the high-pressure absorption tower, while the liquid phase is returned to the reactor from the high-pressure separator.

[0110] The reaction liquid enters the flash evaporator from the liquid phase outlet of the reactor. Vapor-liquid separation occurs at the top of the flash evaporator, with the vapor phase flowing out from the top. The mother liquor at the bottom of the flash evaporator is pressurized by a mother liquor circulation pump and then enters the reactor.

[0111] The high-pressure carbon monoxide storage tank stores a certain amount of high-pressure raw material CO gas. If the current process carbon monoxide supply system suddenly fails, the CO gas in the high-pressure carbon monoxide storage tank will be immediately turned on to supply the synthesis system for emergency treatment, ensuring the safety of the synthesis system equipment and catalyst.

[0112] The gaseous material from the synthesis section enters the pre-washing tower, where it encounters acetic acid from the reflux spray of the separation tower for preliminary distillation separation. The acid liquid at the bottom of the tower, containing catalyst particles, is returned to the flash evaporator. The overhead vapor, containing acetic acid, water, iodomethane, and other components, enters the separation tower. After distillation separation, the overhead vapor enters the primary cooler of the separation tower, then the light liquid cooler. The condensate enters the separator, and the uncondensed gas phase enters the final cooler of the light liquid removal tower, where it is further condensed and cooled with chilled water. The uncondensed tail gas goes to the low-pressure absorption tower in the absorption section. The condensate from the final cooler of the separation tower enters the condensate separator, then the separator. In the separator, the material separates into light and heavy phases. Part of the light phase is returned to the top of the separation tower via the separation tower reflux pump, and part is sent to the acetic acid synthesis section via the dilute acetic acid pump. The heavy phase liquid in the separator is sent to the reactor in the acetic acid synthesis section by the heavy phase pump.

[0113] The bottom liquid of the separation tower is dry acetic acid with very low water content, which is sent to the product tower via the product tower feed pump. The vapor exiting from the top of the tower is condensed and cooled by the product tower condenser and flows into the product tower reflux tank. The finished acetic acid is collected from the side stream, cooled by the product cooler, and sent to the intermediate product storage tank.

[0114] The bottom feed of the finished product column is an acetic acid solution containing propionic acid and other metal-corroding iodides. It is pumped into the top of the stripping column using a feed pump, and the vapor from the top of the column is returned to the bottom of the finished product column. The propionic acid and other metal-corroding iodide solution is cooled by a cooler at the bottom of the stripping column and then discharged to the heavy acid tank, where it is pumped to the heavy acid storage tank in the tank area.

[0115] High-pressure tail gas from the high-pressure separator in the synthesis section enters the high-pressure absorption tower. Methanol enters the absorption feed pump, is cooled by the cooler, and is then sent to the high-pressure absorption tower, flowing from top to bottom. Mass transfer occurs between the two on the packing material inside the high-pressure absorption tower, and the main organic components such as iodomethane (CH3I) in the high-pressure tail gas are absorbed and sent to the reactor.

[0116] Low-pressure tail gas from the condensate separator in the distillation section enters the low-pressure absorption tower. Methanol from the absorption feed pump enters the low-pressure absorption cooler, is cooled with chilled water, and then enters the upper part of the low-pressure absorption tower, flowing from top to bottom. Mass transfer occurs between the two on the packing material inside the tower, and the main organic components, such as iodomethane (CH3I), are absorbed and sent to the reactor.

[0117] For examples, please refer to Figures 3 to 4 The feeding device 1 includes a semi-coke hopper 2 and a limestone hopper 3 connected by a metering belt conveyor 7. The semi-coke hopper 2 and the limestone hopper 3 are welded together. The metering belt conveyor 7 is located below the semi-coke hopper 2 and the limestone hopper 3. Inclined buffer plates 201 are provided on both inner walls of the semi-coke hopper 2. A discharge pipe 202 is connected to the center of the bottom of the semi-coke hopper 2. A first valve 2021 is installed on the discharge pipe 202. A discharge port 301 is opened at the bottom of the limestone hopper 3. A second valve 3011 is installed on the upper part of the discharge port 301. The lower part is provided with a tilting plate 302, and a weight sensor 3021 is embedded in the tilting plate 302. The interior of the limestone hopper 3 is provided with a drive chamber 303 on one side of the discharge port 301. A drive assembly 4 is installed in the drive chamber 303. The execution end of the drive assembly 4 is connected to the tilting plate 302. A connected stirring assembly 5 is provided on one side of the drive assembly 4. The stirring end of the stirring assembly 5 is located above the belt of the metering belt conveyor 7. A cleaning assembly 6 is provided on the side of the metering belt conveyor 7 away from the semi-coke hopper 2. The cleaning end of the cleaning assembly 6 is in contact with the bottom of the belt.

[0118] During the slag melting process, the first valve 2021 is activated via an external controller. The semi-coke that has been screened in the semi-coke hopper 2 falls from the feed pipe 202 onto the metering belt conveyor 7 below. The metering belt conveyor 7 monitors the amount of semi-coke falling and transmits the monitored data to the external controller to calculate the amount of limestone. Then, the second valve 3011 is opened, and the limestone in the limestone hopper 3 falls onto the tilting plate 302, where it is measured by the F35CS weight sensor 3021. When the specified amount is reached, the second valve 3011 closes, and the drive assembly 4 operates, continuously driving the tilting plate. The 302 reciprocating deflection ensures that the weighed limestone falls relatively evenly onto the metering belt conveyor. Simultaneously, it drives the stirring component 5 to mix the passing semi-coke and limestone, ensuring the reaction effect after entering the gasifier. After the belt of the metering belt conveyor 7 delivers the material to the gasifier, the cleaning component 6 cleans the material adhering to the surface, ensuring the cleanliness of the belt surface. The driven wheel drives the stirring column to reciprocate through the rotating shaft, causing the stirring blades to mix the passing semi-coke and limestone. The mixed semi-coke and limestone enter the interior of the gasifier from the top to react.

[0119] For examples, please refer to Figures 4 to 5 The drive cavity 303 has a horizontal plate 3031 inside. The drive assembly 4 includes a forward and reverse motor 406 installed at the top inside the drive cavity 303. The output end of the forward and reverse motor 406 is connected to a drive shaft 404. The bottom end of the drive shaft 404 passes through the horizontal plate 3031 and is connected to a transverse bevel gear 403. A vertical bevel gear 402 is meshed with one side of the transverse bevel gear 403. A connecting shaft 401 passes through the center of the vertical bevel gear 402. One end of the connecting shaft 401 passes through the wall of the limestone hopper 3 and is connected to the tilting plate 302. The drive shaft 404 is located on the transverse bevel gear 403. A drive wheel 405 is provided above the gear 403. The drive wheel 405 is connected to the stirring assembly 5. The outer wall of the horizontal plate 3031 is welded to the inner wall of the drive cavity 303. The forward and reverse motor 406 is fixed to the drive cavity 303 by bolts. The transmission shaft 404 is connected to the output flange of the forward and reverse motor 406. The horizontal bevel gear 403 and the drive wheel 405 are both fixedly sleeved on the transmission shaft 404. The vertical bevel gear 402 is fixedly sleeved on the connecting shaft 401. The two ends of the connecting shaft 401 are rotatably connected to the inner wall of the drive cavity 303 and fixedly connected to the outer wall of the flip plate 302, respectively.

[0120] When the forward and reverse motor 406 in the drive assembly 4 is working, its output end drives the transmission shaft 404 to rotate reciprocally. The transmission shaft 404 drives the horizontal bevel gear 403 and the drive wheel 405 to rotate reciprocally. The horizontal bevel gear 403 drives the meshing vertical bevel gear 402 to rotate. The connecting shaft 401 follows the rotation of the vertical bevel gear 402 and drives the tilting plate 302 to deflect reciprocally, so that the weighed limestone falls evenly onto the metering belt conveyor 7 below. At this time, the rotation of the drive wheel 405 will drive the stirring assembly 5 on one side to rotate.

[0121] For examples, please refer to Figure 4 , Figure 5 and Figure 7 The mixing assembly 5 includes a rotating shaft 501 located on one side of the drive shaft 404. A driven wheel 502 is mounted on the rotating shaft 501, and the driven wheel 502 is meshed with the driving wheel 405. The bottom end of the rotating shaft 501 passes through the bottom surface of the limestone hopper 3 and is connected to a mixing column 503. The outer wall of the mixing column 503 is provided with mixing blades 5031. The mixing column 503 is located above the belt of the metering belt conveyor 7. The bottom of the limestone hopper 3 is provided with baffles 305 on both sides of the mixing column 503. The bottom ends of the two baffles 305 are connected to the belt of the metering belt conveyor 7. With surface contact, the top of the rotating shaft 501 is rotatably connected to the lower surface of the horizontal plate 3031, the driven wheel 502 is fixed to the rotating shaft 501, the stirring column 503 is fixedly connected to the bottom of the rotating shaft 501, the stirring blade 5031 is threaded and welded to the outer wall of the stirring column 503, and the top outer side of the stirring column 503 is symmetrically welded with fixing rods 504, and the top of the two fixing rods 504 is embedded with ball bearings 5041. The bottom surface of the limestone hopper 3 is provided with an annular groove 304, and the upper half of the two ball bearings 5041 is located in the annular groove 304 and is rotatably connected to it.

[0122] When the drive wheel 405 in the drive assembly 4 reciprocates, it drives the meshing driven wheel 502 to rotate. The driven wheel 502 drives the rotating shaft 501 to reciprocate, and the rotating shaft 501 drives the stirring column 503 to reciprocate. The rotating stirring blades 5031 mix the semi-coke and limestone on the metering belt conveyor 7. At the same time, because the material will move to both sides during mixing, baffles 305 are set on both sides of the stirring column 503 to prevent the material from falling from both sides of the belt, so as to achieve synchronous mixing when limestone is added.

[0123] For examples, please refer to Figure 4 , Figure 6 and Figure 8The cleaning component 6 includes a mounting plate 601 welded to the frame of the metering belt conveyor 7. A groove 6011 is formed on one side of the top of the mounting plate 601. A slider 602 slides within the groove 6011. A bracket 603 is welded to the side of the slider 602 away from the groove 6011. A brush 6031 is adhered to the top of the bracket 603 and contacts the belt of the metering belt conveyor 7. A snap-fit ​​cavity 6012 is formed on one side of the mounting plate 601 located within the groove 6011. An electromagnet 604 is mounted on the side of the mounting plate 601 away from the bracket 603. One side of the electromagnet 604 is located within the snap-fit ​​cavity 6012. A movable plate 606 is provided within the snap-fit ​​cavity 6012. The top and bottom of the movable plate 606 are both threaded onto guide rods 605. The movable plate 606 is close to the electromagnet 601. An iron sheet 6061 is embedded in the center of one side of the 04, and the iron sheet 6061 is magnetically connected to the electromagnet 604. Springs 6051 are sleeved on the outer side of the two guide rods 605 near the electromagnet 604. A locking block 607 is provided in the center of the other side of the movable plate 606. A slot 6021 is opened on the side of the slider 602 away from the bracket 603. The locking block 607 passes through the locking cavity 6012 and is locked and connected to the slot 6021. The outer wall of the movable plate 606 is in contact with the inner wall of the locking cavity 6012 and is slidably connected. The movable plate 606 is slidably connected to the guide rod 605. Both ends of the two guide rods 605 are fixedly connected to the inner wall of the locking cavity 6012. The two ends of the two springs 6051 are fixedly connected to the locking cavity 6012 and the movable plate 606 respectively. The locking block 607 is welded to the movable plate 606.

[0124] When the belt on the metering belt conveyor 7 feeds the material into the gasifier, the belt passes through the brush 6031 on the cleaning component 6. The brush 6031 cleans the surface of the belt, reducing the amount of material adhering to its surface. When the brush 6031 wears out after prolonged use and needs to be replaced, the electromagnet 604 is powered by an external controller. The electromagnet 604 generates magnetism, attracting the iron sheet 6061. Due to the magnetism, the iron sheet 6061 moves the movable plate 606 along the inner wall of the locking cavity 6012. The moving movable plate 606 moves the locking block 607 and presses the spring 6051 along the guide rod 605. At this time, the locking block... 607 is disengaged from the slot 6021. At this time, the worker pulls the bracket 603 outward. The bracket 603 moves along the slide groove 6011 via the slider 602 and is removed from the mounting plate 601. Then, the old brush 6031 is removed from the bracket 603, and the new brush 6031 is reattached to the bracket 603. The slider 602 is aligned with 6011 and pushed in. Then, the electromagnet 604 is de-energized. Under the elasticity of the spring 6051, the movable plate 606 and the locking block 607 are reset. The locking block 607 is reinserted into the slot 6021, completing the installation. The installation steps are simple and quick, and the brush 6031 can be replaced at any time to ensure the cleanliness of the belt surface.

[0125] The working principle of this invention is as follows:

[0126] During the slag melting process, the first valve 2021 is activated via an external controller. The semi-coke, already screened, falls from the feed pipe 202 onto the metering belt conveyor 7 below. The metering belt conveyor 7 monitors the amount of semi-coke falling and transmits the monitored data to the external controller to calculate the amount of limestone. Then, the second valve 3011 is opened, and the limestone in the limestone hopper 3 falls onto the tilting plate 302, where it is measured by a weight sensor 3021 (model F35CS). When the specified amount is reached, the second valve 3011 closes. At this time, the forward and reverse motor 406 in the drive assembly 4 operates, and its output drives the transmission shaft 404 to reciprocate. Shaft 404 drives the horizontal bevel gear 403 and the drive wheel 405 to reciprocate. The horizontal bevel gear 403 drives the meshing vertical bevel gear 402 to rotate. The connecting shaft 401 follows the rotation of the vertical bevel gear 402 to drive the tilting plate 302 to reciprocate, so that the weighed limestone can fall evenly onto the metering belt conveyor 7 below. At this time, the rotation of the drive wheel 405 will drive the meshing driven wheel 502 to rotate. The driven wheel 502 drives the rotating shaft 501 to reciprocate. The rotating shaft 501 drives the stirring column 503 to reciprocate. The rotating stirring blades 5031 mix the semi-coke and limestone on the metering belt conveyor 7.

[0127] Simultaneously, because the material will move to both sides during mixing, baffles 305 are installed on both sides of the mixing column 503 to prevent the material from falling off the belt. Under the movement of the metering belt conveyor 7, the material is sent into the gasifier. The belt passes over the brush 6031 on the cleaning component 6, which cleans the surface of the passing belt. When the brush 6031 wears out after prolonged use and needs replacement, the electromagnet 604 is powered by an external controller. The energized electromagnet 604 generates magnetism, attracting the iron sheet 6061. Due to the magnetism, the iron sheet 6061 drives the movable plate 606 to move along the inner wall of the snap-fit ​​cavity 6012. The movable plate 606 drives the locking block 607 to move and presses the spring 6051 along the guide rod 605. At this time, the locking block 607 disengages from the slot 6021. Then, the worker pulls the bracket 603 outward. The bracket 603 moves along the slide groove 6011 via the slider 602 and is removed from the mounting plate 601. Then, the old brush 6031 is removed from the bracket 603, and the new brush 6031 is reattached to the bracket 603. The slider 602 is aligned with 6011 and pushed in. Then, the electromagnet 604 is de-energized. Under the elasticity of the spring 6051, the movable plate 606 and the locking block 607 are reset. The locking block 607 is reinserted into the slot 6021, completing the installation.

[0128] Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the invention and are not intended to limit it. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions, and variations to the embodiments as needed without departing from the principles and spirit of the invention, but such modifications, substitutions, and variations are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for preparing acetic acid using carbon dioxide, characterized in that, The method includes the following steps: Step S1: Slag gasification. Oxygen from the air separation unit is mixed with carbon dioxide from the outside in the mixing flame arrestor. The mixed gasifying agent is injected into the gasifier from the bottom of the gasifier through the nozzle for gasification. The crude CO gas from the gasifier is dedusted by a cyclone separator, then enters a metal filter, and then enters the waste heat boiler. The crude CO gas after exiting the waste heat boiler enters the gas scrubbing tower, where it is cooled and scrubbed by the gasification circulating cooling water. The crude CO gas after exiting the tower is sent to the next process section. Step S2, deoxygenation: The crude CO gas from step S1 is pressurized and passes through a heat exchanger, an organic sulfur hydrogenation conversion reactor, and a deoxygenation reactor. While removing organic sulfur, some of the oxygen is converted and sent to the next process. Step S3, Low-temperature methanol washing; The gas from step S2 passes through the low-temperature methanol washing unit to obtain synthesis gas, which is then sent to the next process. Step S4, low-temperature separation: The syngas from step S3 is purified by the molecular sieve adsorber of the purification system to obtain raw material gas, and then filtered to remove mechanical impurities before entering the cryogenic separation unit to obtain product gas, and then compressed to obtain CO gas. Step S5: Acetic acid is generated. CO gas enters the reactor. Methanol is pressurized by the methanol feed pump in the intermediate storage tank area and mixed with dilute acetic acid from the distillation process and the returned iodomethane mixture. The mixture then enters the reactor and reacts with CO to generate acetic acid. The slag gasification system includes a gasifying agent inlet system, a feeding device (1), a gasifier body, a slag discharge system, a cooling water system, a self-generated steam system, and a CO dust removal and heat recovery system. The low-temperature methanol wash includes a cold zone, a hot zone, a methanol emission collection system, a methanol storage system, and a refrigeration system; The feeding device (1) includes a semi-coke hopper (2) and a limestone hopper (3) connected by a metering belt conveyor (7). The outer walls of the semi-coke hopper (2) and the limestone hopper (3) are connected. The metering belt conveyor (7) is located below the semi-coke hopper (2) and the limestone hopper (3). Inclined buffer plates (201) are provided on both inner walls of the semi-coke hopper (2). A discharge pipe (202) is connected to the center of the bottom of the semi-coke hopper (2). A first valve (2021) is installed on the discharge pipe (202). A discharge port (301) is opened at the bottom of the limestone hopper (3). A second valve (3011) is installed on the upper part of the discharge port (301). The lower part of 01) is provided with a flip plate (302), and the flip plate (302) is embedded with a weight sensor (3021). The interior of the limestone hopper (3) is provided with a drive chamber (303) on the side of the discharge port (301). A drive assembly (4) is installed in the drive chamber (303). The execution end of the drive assembly (4) is connected to the flip plate (302). A connected stirring assembly (5) is provided on one side of the drive assembly (4). The stirring end of the stirring assembly (5) is located above the belt of the metering belt conveyor (7). A cleaning assembly (6) is provided on the side of the metering belt conveyor (7) away from the semi-coke hopper (2). The cleaning end of the cleaning assembly (6) is in contact with the bottom of the belt.

2. The method for preparing acetic acid using carbon dioxide according to claim 1, characterized in that, The semi-coke hopper (2) is welded to the limestone hopper (3). The drive chamber (303) is provided with a horizontal plate (3031). The drive assembly (4) includes a forward and reverse motor (406) installed at the top of the drive chamber (303). The output end of the forward and reverse motor (406) is connected to a drive shaft (404). The bottom end of the drive shaft (404) passes through the horizontal plate (3031) and is connected to a transverse bevel gear (403). A vertical bevel gear (402) is meshed with one side of the transverse bevel gear (403). A connecting shaft (401) passes through the center of the vertical bevel gear (402). One end of the connecting shaft (401) passes through the wall of the limestone hopper (3) and is connected to the tilting plate (302). A drive wheel (405) is provided on the drive shaft (404) above the transverse bevel gear (403). The drive wheel (405) is connected to the stirring assembly (5).

3. The method for preparing acetic acid using carbon dioxide according to claim 2, characterized in that, The outer wall of the horizontal plate (3031) is welded to the inner wall of the drive cavity (303). The forward and reverse motor (406) is fixed to the drive cavity (303) by bolts. The transmission shaft (404) is connected to the output flange of the forward and reverse motor (406). The horizontal bevel gear (403) and the drive wheel (405) are both fixedly sleeved on the transmission shaft (404). The vertical bevel gear (402) is fixedly sleeved on the connecting shaft (401). The two ends of the connecting shaft (401) are rotatably connected to the inner wall of the drive cavity (303) and fixedly connected to the outer wall of the flip plate (302), respectively.

4. The method for preparing acetic acid using carbon dioxide according to claim 2, characterized in that, The stirring assembly (5) includes a rotating shaft (501) located on one side of the drive shaft (404). A driven wheel (502) is installed on the rotating shaft (501). The driven wheel (502) is meshed with the driving wheel (405). The bottom end of the rotating shaft (501) passes through the bottom surface of the limestone hopper (3) and is connected to a stirring column (503). The outer wall of the stirring column (503) is provided with stirring blades (5031). The stirring column (503) is located above the belt in the metering belt conveyor (7). The bottom of the limestone hopper (3) is provided with baffles (305) on both sides of the stirring column (503). The bottom ends of the two baffles (305) are in contact with the belt surface of the metering belt conveyor (7).

5. The method for preparing acetic acid using carbon dioxide according to claim 4, characterized in that, The top end of the rotating shaft (501) is rotatably connected to the lower surface of the horizontal plate (3031). The driven wheel (502) is fixed to the rotating shaft (501). The stirring column (503) is fixedly connected to the bottom end of the rotating shaft (501). The stirring blade (5031) is threaded and welded to the outer wall of the stirring column (503). The top outer side of the stirring column (503) is symmetrically welded with fixing rods (504). The top ends of the two fixing rods (504) are each embedded with a ball bearing (5041). The bottom surface of the limestone hopper (3) is provided with an annular groove (304). The upper half of the two balls bearings (5041) are located in the annular groove (304) and are rotatably connected to it.

6. The method for preparing acetic acid using carbon dioxide according to claim 1, characterized in that, The cleaning component (6) includes a mounting plate (601) welded to the frame of the metering belt conveyor (7). A groove (6011) is provided on one side of the top of the mounting plate (601). A slider (602) is slidably provided in the groove (6011). A bracket (603) is welded to the side of the slider (602) away from the groove (6011). A brush (6031) is attached to the top of the bracket (603). The brush (6031) is in contact with the belt of the metering belt conveyor (7). A snap-fit ​​cavity (6012) is provided in the mounting plate (601) on one side of the groove (6011). An electromagnet (604) is installed on the side of the mounting plate (601) away from the bracket (603). One side of the electromagnet (604) is located in the snap-fit ​​cavity (6012).

7. The method for preparing acetic acid using carbon dioxide according to claim 6, characterized in that, The snap-fit ​​cavity (6012) is provided with a movable plate (606). The top and bottom of the movable plate (606) are both inserted through the guide rod (605). An iron piece (6061) is embedded in the center of the side of the movable plate (606) near the electromagnet (604). The iron piece (6061) is magnetically connected to the electromagnet (604). Springs (6051) are sleeved on the outside of the side of the two guide rods (605) near the electromagnet (604). A snap-fit ​​block (607) is provided in the center of the other side of the movable plate (606). A slot (6021) is opened on the side of the slider (602) away from the bracket (603). The snap-fit ​​block (607) passes through the snap-fit ​​cavity (6012) and is snap-fitted to the slot (6021).

8. The method for preparing acetic acid using carbon dioxide according to claim 7, characterized in that, The outer wall of the movable plate (606) is in contact with the inner wall of the snap-fit ​​cavity (6012) and is slidably connected. The movable plate (606) is slidably connected with the guide rod (605). Both ends of the two guide rods (605) are fixedly connected to the inner wall of the snap-fit ​​cavity (6012). Both ends of the two springs (6051) are fixedly connected to the snap-fit ​​cavity (6012) and the movable plate (606) respectively. The snap block (607) is welded to the movable plate (606).

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