Fixed bed reactor for catalytic reduction of hexavalent uranium by hydrazine nitrate, and application thereof

Abstract

The invention discloses a novel multi-section adiabatic fixed bed reactor device for producing tetravalent uranium through catalytic reduction of hexavalent uranium by hydrazine nitrate. The main function of the device is to control the reaction liquid residence time distribution, the reaction temperature and the acidity in a reaction process in the form of a multi-section adiabatic fixed bed reactor so as to enable the reaction liquid to be in the optimal operation interval, so that minimization of solid high-level radioactive waste discharge is achieved, and the purposes that the content oftetravalent uranium at an outlet meets the requirement and a catalyst is prevented from being oxidized and inactivated due to excessive consumption of hydrazine nitrate. In the optimal implementationscheme, the conversion rate of hexavalent uranium at the outlet of the reactor is greater than 98%, the conversion rate of hydrazine nitrate is lower than 35%, and the content of tetravalent uranium at the outlet of the reactor is greater than 200 g / L.

Description

technical field [0001] The invention relates to a multi-stage adiabatic fixed-bed reactor for reducing hexavalent uranium to generate tetravalent uranium, in particular to a reactor that can be used to reduce hexavalent uranium to generate tetravalent uranium by using hydrazine nitrate as a reducing agent device. Background technique: [0002] With the large-scale development and application of nuclear power, the clean treatment and efficient recycling of nuclear spent fuel have become the key to the further development of nuclear power. At present, the technology mainly adopted by domestic and foreign reprocessing plants is the Purex process. In the process of this process, the valuable uranium and plutonium elements are first extracted into the organic phase through the extraction unit, so as to be separated from most of the splinter elements to achieve the purpose of decontamination; The valence plutonium is reduced to trivalent and enters the water phase, but the hexav...

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Problems solved by technology

The characteristics of the reaction process are: 1. The reaction temperature must be controlled at 40-60 degrees. The reaction temperature is lower than 40 degrees. The consumption rate of hydrazine nitrate in the reaction process is too fast, so that there is a risk of deactivation of the catalyst due to the low concentration of hydrazine nitrate in the later stage of the reaction; 2. The acid concentration must be maintained at 0.5-0.8M in the reaction process. Nitric acid participates in the reduction reaction of hexavalent uranium, and also inhibits the decomposition of hydrazine nitrate. When the acid concentration is lower than 0.5M, the hydrazine nitrate will be consumed excessively. When the acid concentration is higher than 0.8M, the catalyst will be oxidized and deactivated by nitric acid. danger

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