Preparation system for vehicle urea solution and preparation method for vehicle urea solution

Abstract

The invention discloses a preparation system for a vehicle urea solution and a preparation method for the vehicle urea solution. The preparation system comprises a dissolving tank, a first coarse filtration device, a first hyperfiltration device, a buffering tank, an active carbon exchange device, a cation exchange device, an anion exchange device, a second coarse filtration device, a second hyperfiltration device and a finished product tank which are connected in order. The preparation method comprises the following steps: urea is prepared into a urea solution, then the urea solution goes through the first coarse filtration device, the first hyperfiltration device, the active carbon exchange device, the cation exchange device, the anion exchange device, the second coarse filtration device and the second hyperfiltration device in order, metal ion impurities, mechanical impurities and other impurities in the urea solution are removed, and a finished product vehicle urea solution is obtained and stored in the finished product tank. The preparation system can achieve no discharging of any three wastes truly, metal ion impurities, mechanical impurities and other impurities in the urea solution can be removed, and the purity of the prepared vehicle urea solution is high.

Description

technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a system for preparing urea for vehicles and a method for preparing urea for vehicles. Background technique [0002] Judging from the current engine technology at home and abroad, it is already difficult to modify the engine for heavy-duty compression-ignition diesel vehicles used by public transport, sanitation, postal and other departments to meet the national IV emissions. The world's major automobile manufacturers have turned their attention to the selective catalytic reduction technology (SCR, Selective Catalytic Reduction), which has great development potential, and denitrifies the flue gas to meet the requirements of stage IV emissions. The principle of selective catalytic reduction technology SCR is: the urea solution for vehicles is stored in a special storage tank with a capacity of 100L, and the urea solution is sprayed to the hot engine exhaust with compre...

AI Technical Summary

Problems solved by technology

At present, SCR reducing agents mainly include hydrocarbons and their derivatives, ammonia and urea solution. According to Tao Jianzhong’s comparison of these three reducing agents, the following advantages and disadvantages are obtained: hydrocarbons and their derivatives are cheap and easy to obtain, but the used The catalyst is a relatively expensive metal catalyst, and is susceptible to catalyst poisoning due to the influence of sulfur content. The active temperature range is narrow, the reduction efficiency is not high, and it is easy to cause secondary pollution. In contrast, ammonia and urea not only have high reduction efficiency, but the activation temperature And there is no particularly strict requirement on sulfur content, but compared with ammonia and urea, urea has the advantage of being non-toxic and easy to transport. Therefore, urea is more suitable as a reducing agent for NOx control in SCR technology of heavy-duty diesel engines

However, the urea crystallization purification method has high costs, a large amount of wastewater treatment, and unstable product quality; the selective adsorption of urea solution is usually combined with urea synthesis, and the equipment investment cost is high

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