Problems and improvement of zinc oxide desulfurization process


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Problems and improvement of zinc oxide desulfurization process

In the zinc oxide desulfurization process, in order to adapt to the characteristics of rotary kiln flue gas, ensure the normal operation of the desulfurization system and avoid secondary pollution, the process configuration of two-stage kinetic energy wave desulfurization + acid decomposition is adopted.

 Rotary kiln

1. Process of zinc oxide desulfurization

Rotary kiln The process of zinc oxide desulfurization system for tail gas treatment mainly includes slurry preparation, absorption desulfurization, slurry separation and acid decomposition.

(1) Slurry preparation

The zinc oxide material is mainly zinc oxide ash produced by rotary kiln, which is directly added into the pulping tank for slurry making. The prepared zinc oxide slurry is evenly mixed under the stirring of high-power slurry agitator according to a certain slurry proportion. The prepared zinc oxide slurry is transported to the primary and secondary high-efficiency desulfurization towers through the zinc oxide slurry transfer pump.

(2) Absorption desulfurization

Containing so two The tail gas is connected to the reverse nozzle of the kinetic energy wave high-efficiency desulfurization tower, and the flue gas flows from top to bottom. The circulating liquid is sent to the reverse nozzle by the mother liquor circulating pump through the upper liquid pipe, and is ejected from the nozzle in reverse direction with the airflow direction from the bottom to the top. The gas-liquid collision forms a foam area, and the gas-liquid reacts violently in the foam area to achieve the required desulfurization. The tail gas is absorbed and desulfurized by the primary and secondary kinetic energy wave high-efficiency desulfurization tower, and then discharged into the chimney. After absorption, the slurry enters into the liquid storage tank at the bottom of the tower, and is sent to the spray device on the top of the tower by circulating pump for circulating spray, and a part of the slurry is sent to acidolysis through the discharge pump.

(3) Slurry separation

The absorption slurry is transported to the belt filter for filtration through the desulfurization discharge pump, and the absorption slag, zinc sulfite filter residue and filtrate are produced. The zinc sulfite residue enters the acidolysis reactor for reaction, and the filtrate is recycled to the storage tank for slurry making.

(4) Acid decomposition

The filter residue discharged by the belt filter is directly transported to the compartment of the multistage horizontal analysis kettle (reaction tank), and the electrolytic waste liquid with acid content of about 170g / L is input into the compartment. The acid hydrolysis reaction of zinc sulfite starts from the compartment, and finally flows to the fourth compartment through overflow. The generated zinc slurry is sent to the zinc plant system, and the resolved so is obtained two The gas is sent to the acid making system through the extraction pipeline.

2. Existing problems and improvement measures

(1) High power consumption

Since the flue gas desulfurization system of rotary kiln was put into operation, the power consumption has been on the high side. The main reason is that three desulfurization circulating pumps need to be opened for the desulfurization system to meet the production demand; at the same time, there is no frequency conversion control for the regulation of the desulfurization induced draft fan, and the exhaust regulation of the rotary kiln system is only carried out by adjusting the inlet valve of the fan, resulting in waste of equipment work; when one rotary kiln is overhauled, Also have to start the induced draft fan for ventilation, improve the maintenance environment, but also cause the system in the abnormal work of high power consumption. thus it can be seen, Improvement measures of flue gas in rotary kiln system Very important.

In order to reduce the power consumption of rotary kiln system, it is planned to add frequency conversion control for desulfurization induced draft fan and desulfurization circulating pump, so as to achieve fine control of air volume and desulfurization efficiency, and reduce power waste during abnormal production.

(2) Poor filtration by belt filter

The zinc sulfite filtration system of the desulfurization system is mainly directly fed into the belt filter through the desulfurization discharge pump. Due to the limited filtration of the existing belt filter, the moisture content of the filter residue is as high as 45-50. When the filtration is deteriorated, the water content of the filter residue will be greater. It is suggested that a thickener should be set in front of the belt filter to transport the dense underflow to the filter, so as to improve the filtration and reduce the water carrying capacity of the system.

Zinc oxide desulfurization acid hydrolysis combined two-stage desulfurization process is advanced, high comprehensive utilization efficiency, no solid waste generated, less environmental pollution, and can effectively low concentration of so two The innovative application of belt filter and multi-stage horizontal analytical kettle can be used for reference by similar enterprises in China.

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