System for producing sodium carbonate by using carbon dioxide and carbide slag in boiler flue gas

Abstract

The utility model discloses a system for producing sodium carbonate by using carbon dioxide and carbide slag in boiler flue gas, which is characterized in that the boiler flue gas discharged by a coal-fired boiler is purified and then enters a carbonization tower instead of part of lime kiln gas to react with ammoniacal salt water to generate NaHCO3, the NaHCO3 is calcined to generate a final product sodium carbonate, carbon is fixed to the final product, and the emission of CO2 is reduced; and meanwhile, the consumption of CO2 generated by calcining the limestone is reduced, so that the consumption of the limestone and the coke is greatly reduced. Calcium carbide slag generated by a calcium carbide method PVC production device is ground and screened to obtain coarse powder, fine powder and superfine powder, the coarse powder, the fine powder and the superfine powder are mixed in proportion to obtain a calcium carbide slag powder mixture with reasonable grain size distribution, the mixture is used for preparing lime milk, lime milk meeting the ammonia distillation requirement of a sodium carbonate system can be prepared without adding quick lime, the lime milk is used for the ammonia distillation system, and the production cost is reduced. Lime milk notches caused by reduction of lime yield are supplemented, and meanwhile, the utilization value of the solid waste carbide slag is improved.

Description

Technical fields:

[0001] This utility model relates to a system for producing soda ash, and in particular to a system for producing soda ash using carbon dioxide and carbide slag in boiler flue gas. Background technology:

[0002] The main reaction in the ammonia-soda process for producing soda ash is as follows: ammonia gas is passed into saturated refined brine to generate ammonia brine. The ammonia brine reacts with carbon dioxide to produce sodium bicarbonate, which precipitates out. The precipitated sodium bicarbonate is then dehydrated and calcined to produce sodium carbonate, the soda ash. The filtrate containing ammonium chloride is mixed with lime milk (Ca(OH)2) and heated. The released ammonia gas can be recovered and recycled. Currently, the necessary carbon dioxide in the existing process comes from limestone calcination. The quicklime produced by calcination is then nitrated to obtain lime milk. Obtaining these two materials not only consumes a large amount of limestone ore, but also requires a large amount of coke during calcination. Based on a unit consumption of 1.2 tons of limestone per ton of soda ash and 0.1 tons of coke per ton of soda ash, an annual production of 1 million tons of soda ash requires 1.2 million tons of limestone and 100,000 tons of coke. How to reduce consumption is crucial to the market competitiveness, survival, and development of ammonia-soda process soda ash production enterprises.

[0003] Currently, all industries are required to reduce carbon emissions. While thermal power plants, which account for a large proportion of carbon emissions, are striving to find ways to sequester carbon, they lack truly feasible methods. Some thermal power companies have already used methods such as pressure swing adsorption (PSA) to concentrate and recover CO2 from boiler flue gas, producing industrial-grade or food-grade CO2 for external sale. There are no other superior technologies. Although this technology constitutes carbon sequestration for the company itself, the sold CO2 is mostly used as filler gas or protective gas, ultimately returning to the atmosphere, and rarely achieving true carbon sequestration.

[0004] Acetylene (C2H2) is one of the important raw materials in basic organic synthesis industries. The process of producing acetylene from calcium carbide (CaC2) using water (wet process) is simple and mature, and accounts for a large proportion in my country. Adding water to 1 ton of calcium carbide can produce more than 300 kilograms of acetylene gas, while simultaneously generating 10 tons of industrial waste liquid with a solid content of approximately 12%, commonly known as calcium carbide slag slurry. After gravity sedimentation and filtration, the clarified liquid is partially recycled for production, while the remaining calcium carbide slag is used for cement production, mixed with fly ash to make bricks, or simply stockpiled. This not only significantly reduces the recycling value of calcium carbide slag, but also causes substantial environmental pollution due to its discharge and accumulation. The invention patent with publication number CN 119080407 A discloses the use of calcium carbide slag to prepare lime slurry for the ammonia stripping process in the ammonia-soda process for producing soda ash. The lime slurry is prepared by mixing calcium carbide slag and quicklime in a certain ratio. However, the lime slurry only meets the requirements of the ammonia stripping process in the ammonia-soda process when the ratio of calcium carbide slag to quicklime is 0.43. This process involves a low input of calcium carbide slag and has a low utilization rate. Utility Model Content:

[0005] The purpose of this invention is to provide a system for producing soda ash using carbon dioxide and carbide slag from boiler flue gas, thereby increasing the consumption and utilization value of carbide slag, reducing the consumption of limestone, and lowering production energy consumption.

[0006] The purpose of this utility model is achieved through the following technical solution: a system for producing soda ash using carbon dioxide and calcium carbide slag from boiler flue gas, comprising a CO2 compression unit, a calcining furnace gas compression unit, an ammonia brine preparation unit, a carbonation tower, a lime slurry storage tank, an ammonia stripping unit, and a unit for enriching and preparing CO2 product gas from boiler flue gas of a thermal power plant. It also includes a calcium carbide slag lime slurry preparation unit, a neutralization water storage tank, and a neutralization water pump. The product gas outlet of the unit for enriching and preparing CO2 product gas from boiler flue gas of a thermal power plant is connected to the inlet of the CO2 compression unit via a pipeline. The outlet of the CO2 compression unit is connected to the cleaning gas inlet and the intermediate gas inlet of the carbonation tower via pipelines. The outlet of the calcining furnace gas compression unit is connected to the... The lower gas inlet of the carbonization tower is connected via a pipeline; the outlet of the lime slurry pump in the calcium carbide slag lime slurry production unit is connected to the inlet of the lime slurry storage tank; the outlet of the preheated mother liquor of the ammonia stripping tower in the ammonia stripping unit is connected to the inlet of the lime slurry storage tank; the outlet pipeline of the lime slurry storage tank is connected to the feed pipeline of the ammonia stripping tower in the ammonia stripping unit; the ammonia separator of the ammonia stripping unit is connected to the ammonia absorption tower of the ammonia brine preparation unit; the ammonia brine cooler of the ammonia brine preparation unit is connected to the carbonization tower via a pipeline; the neutralized water outlet of the carbonization tower is connected to the inlet of the neutralized water storage tank; the outlet of the neutralized water storage tank is connected to the inlet of the neutralized water pump; and the outlet of the neutralized water pump is connected to the neutralized water inlet of the carbonization tower.

[0007] Furthermore, the calcium carbide slag lime slurry production unit includes a coarse powder feeding device, a fine powder feeding device, an ultrafine powder feeding device, a lime sintering feed screw feeder, a lime sintering machine, a water injection network, a lime slurry tank, and a lime slurry pump. The discharge ports of the coarse powder feeding device, the fine powder feeding device, and the ultrafine powder feeding device are all connected to the inlet of the lime sintering feed screw feeder, and the discharge port of the lime sintering feed screw feeder is connected to the inlet of the lime sintering machine. The outlet of the water injection network is connected to the lime sintering water inlet and the backwash water inlet of the lime sintering machine via pipelines. The lime slurry outlet of the lime sintering machine is connected to the inlet of the lime slurry tank. The outlet of the lime slurry tank is connected to the inlet of the lime slurry pump.

[0008] Furthermore, the coarse powder feeding device, the fine powder feeding device, and the ultrafine powder feeding device have the same structure, all including a hopper, a bucket elevator, and a silo. The discharge port of the hopper is connected to the inlet of the bucket elevator; the discharge port of the bucket elevator is connected to the inlet of the silo; and the discharge port of the silo is connected to the inlet of the ash-making feeding screw feeder.

[0009] Furthermore, the unit for enriching and preparing CO2 product gas from the flue gas of the thermal power plant boiler includes a thermal power plant boiler, a desulfurization and denitrification device, and a CO2 pressure swing adsorption device. The flue gas outlet of the thermal power plant boiler is connected to the flue gas inlet of the desulfurization and denitrification device, the flue gas outlet of the desulfurization and denitrification device is connected to the inlet of the CO2 pressure swing adsorption device, and the product gas outlet of the CO2 pressure swing adsorption device is connected to the inlet of the CO2 compression unit via a pipeline.

[0010] Advantages of this utility model:

[0011] (1) Reduce carbon emissions and reduce raw material consumption: This utility model purifies the CO2 content in the boiler flue gas from about 10% to 38-45%, and then replaces part of the lime kiln gas in the carbonization tower to react with ammonia brine to generate NaHCO3. After calcination, it generates the final product, soda ash, and fixes carbon in the final product, thereby reducing CO2 emissions. It also reduces the amount of CO2 consumed by calcining limestone, and thus greatly reduces the consumption of limestone and coke.

[0012] (2) Comprehensive utilization of solid waste: The calcium carbide slag ash system grinds and screens the calcium carbide slag produced by the calcium carbide PVC production unit to obtain coarse powder, fine powder and ultrafine powder. After mixing them in proportion, a calcium carbide slag powder mixture with reasonable particle size distribution is obtained. The mixture is used to prepare lime milk without adding quicklime. The lime milk that meets the ammonia stripping requirements of the soda ash system can be prepared and used in the ammonia stripping system to supplement the lime milk gap caused by the reduction of lime production. At the same time, it improves the utilization value and consumption of solid waste calcium carbide slag. Attached image description:

[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a low-carbon soda ash production system that comprehensively utilizes carbon dioxide and calcium carbide slag slurry from boiler flue gas.

[0015] Figure 2 A schematic diagram of a unit for producing lime slurry from carbide slag.

[0016] Unit 1 for enriching and preparing CO2 product gas from flue gas of thermal power plant boilers; 1.1 Thermal power plant boiler; 1.2 Desulfurization and denitrification device; 1.3 CO2 pressure swing adsorption device; 2.4 Lime slurry making unit from carbide slag; 2.5 Lime slurry feeding screw feeder; 2.6 Lime slurry machine; 2.7 Water injection network; 2.8 Lime slurry tank; 2.9 Lime slurry pump; 2.0 Hopper; 2.0 Bucket elevator; 2.1 Silage bin; 2.0 Carbonation tower; 3. Ammonia stripping tower; 4. Ammonia absorption tower; 5. CO2 compression unit; 6. Lime slurry storage tank; 7. Neutralization water storage tank; 8. Neutralization water pump; 9. Calcining furnace gas compression unit; 10. Detailed implementation method:

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] Example 1: As Figure 1-2 As shown, a system for producing soda ash using carbon dioxide and calcium carbide slag from boiler flue gas includes a boiler flue gas enrichment and CO2 product gas preparation unit 1, a calcium carbide slag lime slurry preparation unit 2, a CO2 compression unit 6, a carbonation tower 3, a lime slurry storage tank 7, an ammonia stripping unit 4, and an ammonia brine preparation unit 5. In this embodiment, the CO2 compression unit 6 is a compressor. The product gas outlet of the boiler flue gas enrichment and CO2 product gas preparation unit 1 is connected to the inlet of the CO2 compression unit 6 via pipelines, and the outlet of the CO2 compression unit 6 is connected to the carbonation tower. The cleaning gas inlet and the intermediate gas inlet of 3 are connected by pipelines. The outlet of the calcining furnace gas compression unit 10 is connected by pipelines to the lower gas inlet of the carbonization tower 3. In this embodiment, the calcining furnace gas compression unit 10 is a compressor. The ammonia brine outlet of the ammonia brine cooler 5.6 of the ammonia brine preparation unit 5 is connected to the ammonia brine inlet of the carbonization tower 3. The neutralized water outlet of the carbonization tower 3 is connected to the inlet of the neutralized water storage tank 8. The outlet of the neutralized water storage tank 8 is connected to the inlet of the neutralized water pump 9. The outlet of the neutralized water pump 9 is connected to the neutralized water inlet of the carbonization tower 3.

[0019] The calcium carbide slag lime slurry production unit 2 includes a coarse powder feeding device, a fine powder feeding device, an ultrafine powder feeding device, a lime slagging feeder 2.1, a lime slagging machine 2.2, a water injection network 2.3, a lime slurry tank 2.4, and a lime slurry pump 2.5. The coarse powder feeding device, the fine powder feeding device, and the ultrafine powder feeding device have the same structure, each including a hopper 2.6, a bucket elevator 2.7, and a silo 2.8. The discharge port of the hopper 2.6 is connected to the inlet of the bucket elevator 2.7; the discharge port of the bucket elevator 2.7 is connected to the inlet of the silo 2.8. The discharge ports of the coarse powder feeding device, the fine powder feeding device, and the ultrafine powder feeding device are all connected to the inlet of the ash-making feeding screw feeder 2.1. The discharge port of the ash-making feeding screw feeder 2.1 is connected to the inlet of the ash-making machine 2.2. The coarse powder from the coarse powder feeding device, the fine powder from the fine powder feeding device, and the ultrafine powder from the ultrafine powder feeding device are fed into the ash-making machine 2.2 via the ash-making feeding screw feeder 2.1. The coarse powder, fine powder, and ultrafine powder can be fully mixed during the screw conveying process in the ash-making feeding screw feeder 2.1, which helps to ensure the uniformity of the ash slurry prepared in the ash-making machine. The outlet of the water injection network 2.3 is connected to the lime water inlet and the backwash inlet of the lime slurry machine 2.2 via pipelines. To prevent the pipelines inside the lime slurry machine 2.2 from being blocked by lime slurry, the lime slurry machine needs to be backwashed regularly. The lime slurry outlet of the lime slurry machine 2.2 is connected to the inlet of the lime slurry tank 2.4, and the outlet of the lime slurry tank 2.4 is connected to the inlet of the lime slurry pump 2.5. The outlet of the lime slurry pump 2.5 is connected to the inlet of the lime slurry storage tank 7. The preheating mother liquor outlet of the ammonia stripping tower 4.1 is connected to the inlet of the lime slurry storage tank 7, and the outlet pipeline of the lime slurry storage tank 7 is connected to the feed pipeline of the ammonia stripping tower 4.1 of the ammonia stripping unit 4. The ammonia outlet of the ammonia separator 4.4 of the ammonia stripping unit 4 is connected to the ammonia inlet of the ammonia absorption tower 5.7 of the ammonia brine preparation unit 5, so that the lime slurry is transported to the ammonia stripping unit 4 for ammonia recovery and reused in the ammonia absorption tower 5.7.

[0020] After grinding and screening, calcium carbide slag is divided into coarse powder, fine powder, and ultrafine powder. These powders are added to their respective hoppers 2.6. The powders then enter a bucket elevator 2.7 and are transported to their corresponding silos 2.8. After being buffered in the silos 2.8, the powders are fed into the ash-smelting machine 2.2 via a screw feeder 2.1. The coarse, fine, and ultrafine powders are thoroughly mixed in the ash-smelting machine 2.1 and ash-smelting machine 2.2, and then mixed and dissolved with ambient temperature condensate. The resulting ash slurry enters the ash slurry tank 2.4 and is then pumped to the ash slurry storage tank 7 by an ash slurry pump 2.5.

[0021] In one specific embodiment, the CO2 product gas enrichment unit 1 for boiler flue gas in thermal power plants includes a boiler 1.1, a desulfurization and denitrification device 1.2, and a CO2 pressure swing adsorption (PSA) device 1.3. The flue gas outlet of the boiler 1.1 is connected to the flue gas inlet of the desulfurization and denitrification device 1.2, and the flue gas outlet of the desulfurization and denitrification device 1.2 is connected to the inlet of the CO2 PSA device 1.3. The product gas outlet of the CO2 PSA device 1.3 is connected to the inlet of the CO2 compression unit 6 via a pipeline. The desulfurization and denitrification device 1.2 is a general-purpose desulfurization and denitrification device for boiler flue gas in thermal power plants. The CO2 PSA device 1.3 can be the CO2 PSA device disclosed in the utility model patent with patent number ZL202422625076.5, entitled "A PSA Device for Purifying and Recovering Carbon Dioxide in Boiler Flue Gas". After desulfurization and denitrification, the flue gas from the boiler 1.1 is drawn out by the internal fan of the PSA device 1.3. To avoid pressure fluctuations inside the chimney caused by the extracted flue gas, which would subsequently affect the data fluctuations at the monitoring points, an automatic air regulating valve is installed at the top of the chimney, with pressure and opening interlocked for control. The flue gas extracted from the chimney is concentrated by a CO2 pressure swing adsorption device 1.3 and is simultaneously output as product gas. The CO2 concentration in the product gas can be adjusted according to the adsorption pressure; according to the soda ash production process requirements of this embodiment, the target CO2 concentration is designed to be 38-45%. The obtained CO2 product gas replaces part of the lime kiln flue gas and enters the carbonation tower 3 to react with ammonia brine to generate NaHCO3, which is then calcined to produce the final product, soda ash, with carbon fixed in the final product.

[0022] The ammonia brine preparation unit 5 includes a dilute ammonia brine tank 5.1, a dilute ammonia brine pump 5.2, an ammonia brine clarification tank 5.3, an ammonia brine pump 5.4, an ammonia brine filter 5.5, an ammonia brine cooler 5.6, and an ammonia absorption tower 5.7. The dilute ammonia brine tank 5.1, the dilute ammonia brine pump 5.2, the ammonia absorption tower 5.7, the ammonia brine clarification tank 5.3, the ammonia brine pump 5.4, the ammonia brine filter 5.5, and the ammonia brine cooler 5.6 are connected in sequence by pipelines.

[0023] The ammonia stripping unit 4 includes an ammonia stripping tower 4.1, a mother liquor cooling corrugated heat exchanger 4.2, a circulating water cooling corrugated heat exchanger 4.3, and an ammonia separator 4.4. The ammonia stripping tower 4.1, the mother liquor cooling corrugated heat exchanger 4.2, the circulating water cooling corrugated heat exchanger 4.3, and the ammonia separator 4.4 are connected in sequence by pipelines.

[0024] Example 2: A method for producing soda ash using the system of Example 1, comprising the following steps:

[0025] (1) CO2 product gas preparation and compression:

[0026] The CO2 product gas is prepared using a unit that enriches and prepares CO2 from boiler flue gas in a thermal power plant: After desulfurization and denitrification, the flue gas from boiler 1.1 is drawn out by an internal fan of a pressure swing adsorption (PSA) device 1.3. The flue gas drawn from the chimney is enriched by the CO2 PSA device 1.3 and simultaneously output as product gas. The CO2 concentration in the product gas can be adjusted according to the adsorption pressure. According to the soda ash production process requirements of this embodiment, the target CO2 concentration is designed to be 38-42%.

[0027] After being compressed by a compressor, the CO2 product gas is sent to the pre-carbonization and carbonization sections for alkali production.

[0028] The furnace gas from the calcining furnace is washed, cooled, and purified of ammonia before entering the furnace gas separator. It then passes through the gas distribution pipe and, according to production needs, incorporates some CO2 product gas. The gas then passes through the inlet silencer and filter before entering the compressor for compression. The compressed gas is sent to the lower section of the carbonization tower for alkali production. Excess gas is returned to the gas supply pipe via pipeline regulation and then incorporated into the furnace gas system.

[0029] (2) Preparation of lime slurry using a calcium carbide slag lime slurry unit: Coarse powder from the coarse powder feeding device, fine powder from the fine powder feeding device, and ultrafine powder from the ultrafine powder feeding device are fed into the lime slurry machine 2.2 via a lime slurry feeding screw feeder 2.1. The coarse, fine, and ultrafine powders are fully mixed during the screw conveying process within the lime slurry feeding screw feeder 2.1 to obtain a calcium carbide slag powder mixture. The calcium carbide slag powder mixture is added to the lime slurry machine with room temperature water and mixed evenly to obtain lime slurry. The concentration of the prepared lime slurry is 7.75–8.5 kmol / m³. 3 The viscosity is 0.2–0.3 mPa·s. The calcium carbide slag powder mixture with different particle size distributions consists of coarse powder, fine powder, and ultrafine powder in the following mass percentages: 0.5 mm ≤ d 粒径 Coarse powder <2mm accounts for 35% to 50%, and powder ≤10um accounts for 10%. 粒径 Fine powder <0.5mm accounts for 16% to 37%, d 粒径 The ultrafine powder with a particle size <10μm accounts for 23% to 41%, and the sum of the mass percentages of the coarse powder, the fine powder, and the ultrafine powder is 100%. The mass ratio of the calcium carbide slag powder mixture to the room temperature water is 1:2 to 1:3; the temperature of the room temperature water is 15℃ to 25℃.

[0030] (3) Ammonia recovery by passing lime slurry into the ammonia stripping tower: The heated mother liquor enters the preheating section of the ammonia stripping tower and exchanges heat with the gas coming from the distillation section, distilling off most of the CO2 and some free ammonia from the mother liquor. The preheated mother liquor from the preheating section flows into the lime slurry storage tank 7. The lime slurry pumped by the lime slurry pump enters the lime slurry storage tank 7 and mixes with the preheated mother liquor to form a blended liquid. The bound ammonia in the preheated mother liquor reacts with the calcium hydroxide in the lime slurry, decomposing to release free ammonia. The ammonia gas and blended liquid generated in the lime slurry storage tank 7 enter the tower from the upper part (12 turns) of the distillation section of the ammonia stripping tower. Low-pressure steam enters the tower from the bottom and comes into countercurrent contact with the blended liquid, heating and distilling off the free ammonia. The ammonia gas distilled from the ammonia stripping tower 4.1 is cooled and separated by the mother liquor cooling corrugated heat exchanger 4.2, the circulating water cooling corrugated heat exchanger 4.3, and the ammonia gas separator 4.4 before being sent to the ammonia absorption tower 5.7. The low-pressure steam temperature is 150-170℃, the low-pressure steam pressure is 0.25-0.35MPa, the lime slurry temperature is 80-100℃, the pressure at the bottom of the ammonia stripping tower is ≤0.065MPa and not lower than 0MPa, and the pressure in the middle of the ammonia stripping tower is ≤0.036MPa and not lower than 0MPa.

[0031] (4) The recovered ammonia gas and refined brine are reacted in an ammonia absorption tower to prepare ammonia brine: The refined brine is contacted countercurrently with the carbonization tail gas, absorbing NH3 and CO2 to become dilute ammonia brine, which flows by gravity into the dilute ammonia brine tank 5.1 and is pumped by the dilute ammonia brine pump 5.2 into the upper part of the ammonia absorption tower 5.7. From top to bottom, it passes through five washing trays and a cooling absorption section, absorbing NH3 and CO2 from the distilled mixed gas entering from the 10th cycle of the ammonia absorption tower to become hot ammonia brine. The hot ammonia brine exits from the 9th cycle and flows by gravity into the ammonia brine clarification tank 5.3 for clarification. The clarified ammonia brine is pumped by the ammonia brine pump 5.4 into the ammonia brine filter 5.5, and then into the ammonia brine cooler 5.6. After cooling, it is sent to the carbonization tower 3. The turbidity of the ammonia brine sent to the carbonization tower is ≤80ppm, and the temperature of the ammonia brine is 38~43℃.

[0032] (5) CO2 product gas and ammonia brine are fed into a carbonation tower for carbonation reaction to produce sodium bicarbonate:

[0033] Step 1 Pre-carbonization: The finished ammonia brine from step (4) enters the carbonization tower 3 from the 28th ring and comes into countercurrent contact with the CO2 product gas (cleaning gas) from step (1) in the tower. The gas stirs the liquid in the tower, dissolving the scale such as NaHCO3 in the tower. After the liquid (i.e. ammonia brine) absorbs part of the CO2 and is pre-carbonized, carbonized ammonia brine (i.e. neutralized water) is obtained. The neutralized water enters the neutralized water storage tank 8 from the bottom of the tower by pressure.

[0034] Step 2 Carbonization: Neutralized water from neutralized water storage tank 8 is pumped back into carbonization tower 3 via the 28th ring of neutralization water pump 9. CO2 product gas (middle section gas) from step (1) enters carbonization tower via the 7th ring; furnace gas (lower section gas) from calcination furnace enters carbonization tower via the bottom. Inside carbonization tower, lower section gas and middle section gas react with neutralized water in a countercurrent flow to form NaHCO3 crystals, which become coarser after cooling. The alkali solution (i.e., the extract) from the bottom of carbonization tower is sent to the calcination process. In order to obtain a suspension with high NaCl conversion rate, coarse NaHCO3 crystals, and low impurity content, and to reduce the loss of ammonia and carbon dioxide at the top of the tower, a large amount of cooling water (circulating water and direct flow water) is circulated in the cooling water tanks of carbonization tower (a total of 8 rings of tanks). The influent flow rate and the outlet water layer are adjusted according to the tower temperature and the outlet alkali temperature. In this embodiment, cooling water exits from the third (lower layer), sixth (middle layer), and eighth (upper layer) rings of the water tank and returns to the circulating water network. The CO2 volume concentration of the cleaning gas is 38-42%, the CO2 volume concentration of the lower section gas is ≥74%, the oxygen volume percentage of the lower section gas is ≤2%, and the temperature of the lower section gas is 30-45℃; the CO2 volume concentration of the middle section gas is 38-42%, the oxygen volume percentage of the middle section gas is ≤2%, and the temperature of the middle section gas is 35-45℃; the temperature of the carbonization tower in ring 5 is 35-45℃ during the carbonization stage; the temperature of the carbonization tower in ring 12 is 58-70℃ during the carbonization stage; the temperature of the carbonization tower in ring 17 is 60-72℃ during the carbonization stage; the temperature of the carbonization tower in ring 23 is 50-60℃ during the carbonization stage; and the NaCl conversion rate can reach 76%.

[0035] (6) Sodium bicarbonate is filtered and calcined to obtain soda ash product.

[0036] Example 3: Using the method of Example 2, high-grade soda ash was prepared. The specific implementation parameters and quality index test results are shown in the table below:

[0037]

[0038]

[0039]

[0040] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A system for producing soda ash using carbon dioxide and calcium carbide slag from boiler flue gas, comprising a CO2 compression unit, a calcining furnace gas compression unit, an ammonia brine preparation unit, a carbonation tower, a ash slurry storage tank, an ammonia stripping unit, and a boiler flue gas concentration unit for producing CO2 product gas, characterized in that, It also includes a calcium carbide slag lime slurry production unit, a neutralization water storage tank and a neutralization water pump. The product gas outlet of the boiler flue gas enrichment and CO2 product gas preparation unit is connected to the inlet of the CO2 compression unit via a pipeline. The outlet of the CO2 compression unit is connected to the cleaning gas inlet and the middle section gas inlet of the carbonization tower via pipelines. The outlet of the calcining furnace gas compression unit is connected to the lower section gas inlet of the carbonization tower via a pipeline. The outlet of the lime slurry pump in the calcium carbide slag lime slurry production unit is connected to the inlet of the lime slurry storage tank; the outlet of the preheated mother liquor of the ammonia stripping tower in the ammonia stripping unit is connected to the inlet of the lime slurry storage tank; the outlet pipeline of the lime slurry storage tank is connected to the feed pipeline of the ammonia stripping tower in the ammonia stripping unit; the ammonia separator of the ammonia stripping unit is connected to the ammonia absorption tower of the ammonia brine preparation unit; the ammonia brine cooler of the ammonia brine preparation unit is connected to the carbonation tower via a pipeline; the neutralized water outlet of the carbonation tower is connected to the inlet of the neutralized water storage tank; the outlet of the neutralized water storage tank is connected to the inlet of the neutralized water pump; and the outlet of the neutralized water pump is connected to the neutralized water inlet of the carbonation tower.

2. The system for producing soda ash using carbon dioxide and carbide slag in boiler flue gas according to claim 1, characterized in that, The calcium carbide slag lime slurry production unit includes a coarse powder feeding device, a fine powder feeding device, an ultrafine powder feeding device, a lime sintering screw feeder, a lime sintering machine, a water injection network, a lime slurry tank, and a lime slurry pump. The outlets of the coarse powder feeding device, the fine powder feeding device, and the ultrafine powder feeding device are all connected to the inlet of the lime sintering screw feeder, and the outlet of the lime sintering screw feeder is connected to the inlet of the lime sintering machine. The outlet of the water injection network is connected to the lime sintering water inlet and the backwash water inlet of the lime sintering machine via pipelines. The lime slurry outlet of the lime sintering machine is connected to the inlet of the lime slurry tank. The outlet of the lime slurry tank is connected to the inlet of the lime slurry pump.

3. The system for producing soda ash using carbon dioxide and carbide slag in boiler flue gas according to claim 2, characterized in that, The coarse powder feeding device, the fine powder feeding device, and the ultrafine powder feeding device have the same structure, each including a hopper, a bucket elevator, and a silo. The discharge port of the hopper is connected to the inlet of the bucket elevator; the discharge port of the bucket elevator is connected to the inlet of the silo; and the discharge port of the silo is connected to the inlet of the ash-making feeding screw feeder.

4. The system for producing soda ash using carbon dioxide and carbide slag in boiler flue gas according to claim 1, characterized in that, The unit for enriching and preparing CO2 product gas from flue gas in a thermal power plant boiler includes a thermal power plant boiler, a desulfurization and denitrification device, and a CO2 pressure swing adsorption device. The flue gas outlet of the thermal power plant boiler is connected to the flue gas inlet of the desulfurization and denitrification device, the flue gas outlet of the desulfurization and denitrification device is connected to the inlet of the CO2 pressure swing adsorption device, and the product gas outlet of the CO2 pressure swing adsorption device is connected to the inlet of the CO2 compression unit via a pipeline.

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