Method for jointly producing sulphuric acid and cement clinker by using sulphur gas to reduce gypsum

Abstract

The invention relates to a method for jointly producing sulphuric acid and cement clinker by using sulphur gas to reduce gypsum. The method comprises the steps of preparing high-temperature sulphur gas, proportioning and preheating raw materials, reducing gypsum, preparing cement clinker by using gypsum reduction products, preparing sulphuric acid by using tail gas and the like. The method disclosed by the invention has complete technology, the purity of the sulphur gas component can be kept at 95-100%, maximal conversion efficiency of calcium sulfate in a calcining kiln is effectively controlled by controlling the optimal conversion ratio of calcium sulfate into calcium sulfide in a reduction furnace at 25-27%, and the calcination is convenient to control; and the method has the advantages of simple technological procedure, high practicality of system control indexes, convenient operation and management, low investment of equipment, low energy consumption, high automation degree and the like.

Description

technical field [0001] The invention relates to chemical production, in particular to a method for producing sulfuric acid and co-producing cement clinker by reducing gypsum with sulfur gas. Background technique [0002] Existing chemical production and coal-fired flue gas desulfurization by-product a large amount of process waste residue gypsum, a small amount of these gypsum waste residues are used as building materials, cement retarders, etc., and a large amount is mainly stored. In order to reduce environmental pressure, the resource utilization of gypsum has been the direction of scientific and technological workers' efforts for many years. The chemical decomposition of gypsum to produce sulfuric acid by-product portland cement clinker is a major issue of gypsum resource utilization. According to this process, the chemical industry produces by-product gypsum. The gypsum is decomposed to produce calcium oxide and sulfur dioxide. The sulfur dioxide can be converted into ...

AI Technical Summary

Problems solved by technology

[0018] (4) In the reduction furnace, the content of calcium sulfide is already much higher, so it does not need to be recycled into the reduction furnace, which will increase the consumption of fluidized power

[0019] (5) The material discharged from the reduction furnace and added to the calciner kiln will increase the energy consumption of calcining and reduce the decomposition rate of calcium sulfate because the proportion of calcium sulfide is too high

[0023] The above method discloses some operational control indicators for phosphogypsum to undergo sulfur reduction reaction to decompose phosphogypsum before roasting, but there are problems such as difficult operation, high energy consumption, and poor implementability in actual industrial applications:

In addition, during the cooling process of the calcium sulfide block before grinding, the unreacted excess sulfur gas will condense into the calcium sulfide product, and there is a risk of spontaneous combustion or explosion during the grinding process

[0026] (3) Calcium sulfide in the reduced solid product is cooled and ground, and then mixed with phosphogypsum before roasting, it must be preheated again, which not only increases the grinding power consumption, but also increases the preheating energy consumption, and the system energy consumption is high.

[0027] (4) There is excess gaseous sulfur in the gas phase of the reduction reactor, which will cause sulfur to solidify when brought into the subsequent sulfuric acid production system, which will block the equipment pipeline and make cleaning difficult

[0029] The above method discloses some operational control indicators for sulfate to be decomposed by sulfur reduction reaction before high-temperature reaction to obtain sulfide, but in the actual industrial application, there are also problems such as difficult operation, high energy consumption, and poor implementability. :

And during the cooling process of the sulfide material block before grinding, the unreacted excess sulfur gas will condense into the sulfide product, and there is a natural or explosion hazard during the grinding process

[0032] (3) After cooling and grinding the sulfide in the reduced solid product, it must be preheated before mixing with sulfate to enter the high-temperature reaction, which not only increases the grinding power consumption, but also increases the preheating energy consumption, and the system consumes a lot of energy.

[0033] (4) There is excess gaseous sulfur in the gas phase of the reduction reactor, which will cause sulfur to solidify when brought into the subsequent sulfuric acid production system, which will block the equipment pipeline and make cleaning difficult

[0035] (1) There is a lack of refining process for liquid sulfur. Liquid sulfur usually contains high impurities, which can easily cause scaling and blockage of pipelines and heat exchange equipment

[0036] (2) The liquid sulfur is indirectly heated and vaporized by the high-temperature sulfur-containing flue gas in the heat exchanger. Due to the long heat exchange pipeline, it is difficult to completely discharge the liquid sulfur when the system is shut down, and it will solidify and block the pipeline, which cannot be removed. Difficult to run continuously and stably for a long period

[0037] (3) The material grade of the gasifier is high, the manufacturing requirements are high, and the cost is high: the sulfur gasifier is installed at the exhaust outlet of the gypsum calcining kiln, where the SO 2 The temperature of the flue gas is as high as 900-1100°C. Therefore, the materials of the gasifier tube side and the shell side need to be resistant to high temperature and sulfur corrosion. The gasifier is equivalent to a heat exchanger structure, and the equipment structure is complicated and difficult to process.

[0038] (4) The process of arranging the sulfur gasifier behind the flue gas of the rotary kiln affects the comprehensive utilization of heat energy in the flue gas of gypsum calcination, so that additional heating and combustion systems are required for gypsum reduction, and additional fans are required to increase power consumption. , the overall energy consumption of the system is increased, which is an uneconomical combined process

[0039] (5) Fluidized bed tail gas contains residual sulfur gas, which will cause sulfur solidification when brought into the subsequent sulfuric acid production system, which will block equipment pipelines and make cleaning difficult

[0040] (6) Furnace gas SO 2 Low concentration, high system investment: The hot furnace gas generated by the additional fuel hot blast stove is mixed with sulfur gas as the power and reduction gas for jet fluidization, which increases the total gas volume for gypsum calcination and gypsum reduction, and makes the furnace gas in the whole system SO 2 As the concentration decreases, the production capacity of subsequent sulfuric acid production system equipment will decrease, the conversion efficiency will decrease, and the conversion heat balance will be affected.

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