Comprehensive utilization scheme of carbide slag and boiler flue gas in sodium carbonate production

Abstract

The invention relates to the field of chemical engineering, and discloses a comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production, the comprehensive utilization scheme comprises an ash melting machine, a lime bin and a carbide slag bin are arranged outside the ash melting machine, the lime bin and the carbide slag bin are respectively communicated with the ash melting machine through spiral feeding equipment, and a carbide slag elevator is arranged on the outer side of the carbide slag bin. An input port of the carbide slag elevator is communicated with the carbide slag hopper, an output port of the carbide slag elevator is positioned above the carbide slag bin, a lime milk sieve is arranged below a discharge port of the lime slaking machine, a lime milk barrel is arranged below the lime milk sieve, the lime milk barrel is connected with a lime milk pump, and an output pipe of the lime milk pump is communicated with the ammonia distillation system. According to the invention, the production load of the lime kiln can be reduced, the raw materials of limestone and coke can be saved, and the solid waste carbide slag generated by the PVC production device and the waste gas generated by the flue gas of the coal-fired boiler can be fully utilized.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production. Background Art

[0002] In the current domestic soda ash industry, natural soda has gradually entered the market. Due to its low production cost and high economic benefits, the ammonia-soda process for producing soda ash faces huge market competition and survival pressure. The green development trend of the soda ash industry has taken shape. In this context, it is proposed to use the solid waste calcium carbide slag produced by the PVC production device, and mix it with quicklime in a certain proportion to prepare ash milk, which is used for brine refining and ammonia distillation system to reduce the production load of the lime kiln. The gap in CO2 gas required for carbonization can be supplemented by using the flue gas generated by the coal-fired boiler in the power workshop, and producing high-concentration CO2 gas through carbon dioxide capture and concentration technology. This can not only reduce the amount of solid waste calcium carbide slag to be processed, but also reduce the emission of CO2 gas, and also reduce the use of limestone and coke, thereby achieving the purpose of energy conservation, emission reduction, cost reduction and efficiency improvement. Summary of the invention

[0003] In order to overcome the above-mentioned shortcomings, the present invention provides a comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production.

[0004] The technical solution adopted by the present invention is:

[0005] A comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production, comprising a ash dissolving machine, a lime bin and a carbide slag bin are provided outside the ash dissolving machine, the lime bin and the carbide slag bin are connected to the ash dissolving machine through spiral feeding equipment respectively, a carbide slag elevator is provided outside the carbide slag bin, the input port of the carbide slag elevator is connected to the carbide slag hopper, the output port of the carbide slag elevator is located above the carbide slag bin, a lime milk screen is provided below the discharge port of the ash dissolving machine, an ash milk barrel is provided below the lime milk screen, the ash milk barrel is connected to an ash milk pump, and the output pipe of the ash milk pump is connected to an ammonia distillation system.

[0006] The specific process is:

[0007] The transported calcium carbide slag is loaded into the calcium carbide slag hopper by a forklift, then transported to the calcium carbide slag bin by the calcium carbide slag elevator, and after being buffered in the slag bin, it enters the ash machine through the spiral feeding equipment.

[0008] At the same time, quicklime is transported from tank trucks, sent to the lime silo by pneumatic conveying devices, and enters the ash machine through spiral feeding equipment.

[0009] The feed ratio of carbide slag and quicklime is adjusted by the speed regulating device of the lime feed screw.

[0010] Carbide slag and quicklime are fully mixed in the ash dissolving machine, and condensed water at 48°C is injected for ash dissolving. The obtained ash milk is filtered through the ash milk screen to remove the sediment and then enters the ash milk barrel, and then the ash milk is pumped to the ammonia distillation system.

[0011] Beneficial effects of the present invention:

[0012] The present invention can not only reduce the production load of the lime kiln and save raw materials such as limestone and coke, but also make full use of the solid waste calcium carbide slag generated by the PVC production device and the waste gas generated by the flue gas of the coal-fired boiler. It is of great significance to accelerate the green transformation and realize the efficient utilization and recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0014] like Figure 1 As shown: a comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production, including a ash dissolving machine, the outside of which is provided with a lime bin and a carbide slag bin, the lime bin and the carbide slag bin are connected to the ash dissolving machine through spiral feeding equipment respectively, a carbide slag elevator is provided on the outside of the carbide slag bin, the input port of the carbide slag elevator is connected to the carbide slag hopper, the output port of the carbide slag elevator is located above the carbide slag bin, a lime milk screen is provided below the discharge port of the ash dissolving machine, an ash milk barrel is provided below the lime milk screen, the ash milk barrel is connected to an ash milk pump, and the output pipe of the ash milk pump is connected to the ammonia distillation system.

[0015] The specific process is:

[0016] The transported calcium carbide slag is loaded into the calcium carbide slag hopper by a forklift, then transported to the calcium carbide slag bin by the calcium carbide slag elevator, and after being buffered in the slag bin, it enters the ash machine through the spiral feeding equipment.

[0017] At the same time, quicklime is transported from tank trucks, sent to the lime silo by pneumatic conveying devices, and enters the ash machine through spiral feeding equipment.

[0018] The feed ratio of carbide slag and quicklime is adjusted by the speed regulating device of the lime feed screw.

[0019] Carbide slag and quicklime are fully mixed in the ash dissolving machine, and condensed water at 48°C is injected for ash dissolving. The obtained ash milk is filtered through the ash milk screen to remove the sediment and then enters the ash milk barrel, and then the ash milk is pumped to the ammonia distillation system.

[0020] The ACa0 content in the carbide slag component is low, and the particles are too large, resulting in poor fluidity after slurrying. In order to ensure the smooth operation of the ammonia evaporation system, the carbide slag needs to be mixed with the lime produced by the lime kiln for use.

[0021] In order to determine the best blending ratio, a small amount of carbide slag and quicklime were weighed in different proportions and added to the test device. Condensate water at 48°C was added according to the water addition amount of the ash dissolving machine. An electric stirrer was used to fully stir the mixture. The slurrying time was 8 minutes (residence time in the ash dissolving machine). The specific gravity, slurry temperature after dissolution, and concentration were measured.

[0022] The test results are as follows:

[0023] Sample 1 2 3 4 5 6 7 Carbide slag amount (kg) (1) 1.8 1.62 1.46 1.23 1.05 2.26 2.26 Amount of quicklime (kg) (2) 1.84 2 2.14 2.28 2.42 2.26 2.26 Mixing ratio (1) / (2) 0.98 0.81 0.68 0.54 0.43 1.0 1.0 Effective decomposition rate (%) 82 82 82 82 82 82 82 Water addition amount (kg) 8.4 8.5 8.6 8.6 8.55 9.06 8.04 <![CDATA[Specific gravity (kg / m 3 )]]> 1144 1147 1147 1167 1145 1150 1202 Water temperature (℃) 48 48 48 48 48 48 48 Slurry temperature (℃) 76 78 83 90 91 92 82 Slurry concentration (tt) 129.48 140.2 142.2 154.12 157.72 152.16 169.76 Pulping time (min) 8 8 8 8 8 8 8

[0024] Test conclusion:

[0025] 1. The ratio of carbide slag to quicklime is 1:1, and the specific gravity is 1150kg / m 3 When the slurry is mixed with calcium carbide slag, the fluidity is good, but the slurry concentration is low, only 152.16tt; the ratio of calcium carbide slag to quicklime is 1:1, and the specific gravity is 1202kg / m 3 The slurry concentration is 169.76tt, but the slurry is viscous and has poor fluidity.

[0026] 2. With the increase of carbide slag blending amount, the slurry sedimentation speed is accelerated, the number of particles increases, and the slurry fluidity is significantly deteriorated. This shows that the particles in carbide slag account for a large proportion and have a compression effect, which may have a great impact on the ammonia distillation system.

[0027] 3. When the mixing ratio of carbide slag and quicklime is 0.43 (test data of the 5th group), both the sensory appearance and fluidity are good, and it is also very close to the evaporated ammonia ash milk (concentration 157tt, temperature 91℃), which can meet the needs of evaporated ammonia production.

[0028] In the production of ammonia and alkali, the CO2 concentration in the cleaning gas is required to be around 40%, so the boiler flue gas needs to be purified, concentrated and recovered before it can be used. At present, CO2 capture and concentration technology has become increasingly mature, and its main methods include chemical absorption technology, physical absorption technology, membrane separation technology, adsorption method, deep cold separation method, etc. Through technical comparison, the adsorption method has the advantages of high capture efficiency, low energy consumption and simple operation. It is suitable for the capture and concentration of low-concentration carbon dioxide. Therefore, the adsorption method is preferred for flue gas concentration and recovery. SO2 and NO in flue gas X The content is extremely low. It neither participates in chemical reactions during the soda ash production process nor is it brought into the product, so it has no impact on product quality.

[0029] Brief description of CO2 pressure swing adsorption process:

[0030] The flue gas produced by the coal-fired boiler is dust-removed and purified by the pre-treatment device, and then pressurized by the compressor unit before entering the gas concentration system. The 45% CO2 gas produced is sent to the carbonization device, and the tail gas produced by the concentration is discharged after meeting the standards.

Claims

1. A comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production, characterized in that: It includes a ash dissolving machine, which has a lime bin and a carbide slag bin on the outside. The lime bin and the carbide slag bin are connected to the ash dissolving machine through spiral feeding equipment respectively. A carbide slag elevator is provided on the outside of the carbide slag bin. The input port of the carbide slag elevator is connected to the carbide slag hopper. The output port of the carbide slag elevator is located above the carbide slag bin. A lime milk screen is provided below the discharge port of the ash dissolving machine. An ash milk barrel is provided below the lime milk screen. The ash milk barrel is connected to an ash milk pump. The output pipe of the ash milk pump is connected to the ammonia distillation system.

2. The comprehensive utilization scheme of carbide slag and boiler flue gas in soda ash production according to claim 1 is characterized in that: The specific process is: The transported calcium carbide slag is loaded into the calcium carbide slag hopper by a forklift, then transported to the calcium carbide slag bin by the calcium carbide slag elevator, and after being buffered in the slag bin, it enters the ash machine through the spiral feeding equipment. At the same time, quicklime is transported from tank trucks, sent to the lime silo by pneumatic conveying devices, and enters the ash machine through spiral feeding equipment. The feed ratio of carbide slag and quicklime is adjusted by the speed regulating device of the lime feed screw. Carbide slag and quicklime are fully mixed in the ash dissolving machine, and condensed water at 48°C is injected for ash dissolving. The obtained ash milk is filtered through the ash milk screen to remove the sediment and then enters the ash milk barrel, and then the ash milk is pumped to the ammonia distillation system.

Images