CN-121972092-A - Liquid ammonia impurity removal method and system based on selective oxidation

CN121972092ACN 121972092 ACN121972092 ACN 121972092ACN-121972092-A

Abstract

The invention provides a method and a system for removing impurities from liquid ammonia based on selective oxidation, wherein the method comprises the steps of obtaining impurity composition data of liquid ammonia to be treated, determining a catalyst type, an oxygen content control range and a reaction temperature required by the liquid ammonia in a selective oxidation process, establishing a selective oxidation reaction zone corresponding to the pretreated liquid ammonia in a reactor based on the catalyst type and the oxygen content control range, setting an oxygen content control value of the selective oxidation reaction zone in the oxygen content control range, controlling the reaction temperature, carrying out selective catalytic oxidation reaction of the pretreated liquid ammonia in the selective oxidation reaction zone, and carrying out gas-liquid separation on a mixed product after the reaction to obtain target liquid ammonia. According to the scheme, the non-selective oxidation of the liquid ammonia body can be furthest inhibited, the efficient removal of impurities is realized, and the method is energy-saving and environment-friendly.

Inventors

Jian Jinxiang
ZENG YANGWEN
CHENG ZHIQIANG
CHEN JINRONG

Assignees

惠州市华达通气体制造股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260317

Claims (10)

1. A method for removing impurities from liquid ammonia based on selective oxidation, comprising: Obtaining impurity composition data of liquid ammonia to be treated, and carrying out desulfurization pretreatment on the liquid ammonia to be treated to obtain pretreated liquid ammonia, wherein the impurity composition data are used for determining the type of a catalyst, an oxygen content control range and a reaction temperature required by the liquid ammonia in a selective oxidation process; Introducing the pretreated liquid ammonia into a corresponding reactor, and establishing a selective oxidation reaction zone corresponding to the pretreated liquid ammonia in the reactor based on the catalyst type and the oxygen content control range; setting an oxygen content control value of the selective oxidation reaction zone in the oxygen content control range according to the catalyst type and the component characteristics of hydrocarbon in the pretreated liquid ammonia; based on the oxygen content control value and the reaction temperature, carrying out a selective catalytic oxidation reaction of the pretreated liquid ammonia in the selective oxidation reaction zone to obtain a mixed product after reaction, and carrying out gas-liquid separation on the mixed product to obtain target liquid ammonia.
2. A method for removing impurities from liquid ammonia based on selective oxidation according to claim 1, wherein establishing a corresponding selective oxidation reaction zone of the pretreated liquid ammonia in the reactor based on the catalyst type and the oxygen content control range comprises: filling a copper oxide-cobalt oxide composite catalyst in the catalyst type into a fixed bed layer of the reactor to form a catalyst bed layer; introducing oxygen-containing carrier gas into the catalyst bed so as to enable the oxygen concentration in the catalyst bed to be within the oxygen content control range; when the oxygen concentration in the catalyst bed reaches the oxygen content control range, synchronously controlling the bed temperature of the catalyst bed at a preset reaction temperature to form the selective oxidation reaction zone.
3. A method for removing impurities from liquid ammonia based on selective oxidation according to claim 2, wherein introducing an oxygen-containing carrier gas into said catalyst bed so that the oxygen concentration in said catalyst bed is within said oxygen content control range comprises: introducing mixed carrier gas to the inlet end of the catalyst bed, wherein the mixed carrier gas consists of inert gas and oxygen; an oxygen concentration sensor is disposed at the catalyst bed inlet end to monitor in real time the oxygen concentration in the mixed carrier gas; and dynamically adjusting the mixing proportion of the mixed carrier gas based on the oxygen concentration so as to enable the oxygen concentration in the catalyst bed to be in the oxygen content control range.
4. A method for removing impurities from liquid ammonia based on selective oxidation according to claim 1, wherein setting an oxygen content control value of said selective oxidation reaction zone within said oxygen content control range according to said catalyst type and a component characteristic of hydrocarbon in said pretreated liquid ammonia comprises: extracting impurity components with the lowest oxidation reaction activity from the hydrocarbon according to the component characteristics; Identifying a selective oxidation activity window corresponding to the catalyst type, and determining the minimum oxygen concentration required by the impurity component to reach a preset removal rate based on the catalyst type; And selecting a value between the lowest oxygen concentration and the upper limit of the selective oxidation activity window as the oxygen content control value in the oxygen content control range.
5. A method for removing impurities from liquid ammonia based on selective oxidation according to claim 4, wherein extracting the impurity component having the lowest oxidation reactivity in said hydrocarbon based on said component characteristics comprises: analyzing the molecular structure of each impurity component in the component characteristics to determine the oxidation reaction activation energy corresponding to each impurity component; And determining the impurity component corresponding to the highest oxidation reaction activation energy in the oxidation reaction activation energy as the impurity component with the lowest oxidation reaction activity in the hydrocarbon.
6. The method for removing impurities from liquid ammonia based on selective oxidation according to claim 1, wherein the step of obtaining target liquid ammonia after gas-liquid separation of the mixed product comprises the steps of: Introducing the mixed product into a gas-liquid separator for separation to obtain a gas product and primarily separated liquid ammonia; Sending the primary separation liquid ammonia into a flash evaporation device to remove gas components in the primary separation liquid ammonia, so as to obtain liquid ammonia after flash evaporation; Introducing the liquid ammonia after flash evaporation into a rectifying tower for purification to remove volatile impurities in the liquid ammonia after flash evaporation, thereby obtaining rectifying liquid ammonia; condensing the rectified liquid ammonia to obtain the target liquid ammonia.
7. The method for removing impurities from liquid ammonia based on selective oxidation according to claim 6, wherein condensing the rectified liquid ammonia to obtain the target liquid ammonia comprises: introducing the rectified liquid ammonia into a condenser, and cooling the rectified liquid ammonia to a temperature below a preset liquid ammonia condensation temperature through a circulating cooling medium in the condenser so as to completely liquefy the rectified liquid ammonia; Introducing the completely liquefied rectification liquid ammonia into a surge tank to release trace non-condensable gas in the rectification liquid ammonia; and after the release of the trace noncondensable gas is completed, collecting liquid ammonia in the surge tank as the target liquid ammonia.
8. A method for removing impurities from liquid ammonia based on selective oxidation according to claim 1, wherein a selective catalytic oxidation reaction of said pretreated liquid ammonia occurs in said selective oxidation reaction zone based on said oxygen content control value and said reaction temperature to obtain a mixed product after reaction, comprising: Introducing the pretreated liquid ammonia into the selective oxidation reaction zone at a preset flow rate; synchronously adjusting the oxygen concentration in the selective oxidation reaction zone and the reaction temperature to be the oxygen content control value and the reaction temperature correspondingly; continuously passing the pretreated liquid ammonia through a catalyst bed layer of the selective oxidation reaction zone to perform catalytic oxidation reaction under the condition of maintaining the oxygen content control value and the reaction temperature; synchronously collecting the gas-liquid mixture after the reaction from the outlet of the selective oxidation reaction zone as the mixed product.
9. The method for removing impurities from liquid ammonia based on selective oxidation according to claim 1, wherein the desulfurizing pretreatment of the liquid ammonia to be treated is performed to obtain pretreated liquid ammonia, comprising: Introducing the liquid ammonia to be treated into a prepared desulfurizing tower so that sulfide in the liquid ammonia to be treated is subjected to selective adsorption reaction in the desulfurizing tower to obtain primary purified liquid ammonia; And introducing the primary purified liquid ammonia into a preset activated carbon adsorption device, and removing trace organic sulfur components in the primary purified liquid ammonia by using the activated carbon adsorption device to obtain the pretreated liquid ammonia.
10. A liquid ammonia impurity removal system based on selective oxidation, characterized in that a liquid ammonia impurity removal method based on selective oxidation according to any one of claims 1 to 9 is adopted, said system comprising: The raw material processing module is used for acquiring impurity composition data of liquid ammonia to be processed, and carrying out desulfurization pretreatment on the liquid ammonia to be processed to obtain pretreated liquid ammonia, wherein the impurity composition data are used for determining the type of a catalyst, an oxygen content control range and a reaction temperature required by the liquid ammonia in a selective oxidation process; The environment configuration module is used for introducing the pretreated liquid ammonia into a corresponding reactor, and establishing a selective oxidation reaction zone corresponding to the pretreated liquid ammonia in the reactor based on the type of the catalyst and the oxygen content control range; The parameter setting module is used for setting an oxygen content control value of the selective oxidation reaction zone in the oxygen content control range according to the catalyst type and the component characteristics of hydrocarbon in the pretreated liquid ammonia; And the separation and purification module is used for carrying out the selective catalytic oxidation reaction of the pretreated liquid ammonia in the selective oxidation reaction zone based on the oxygen content control value and the reaction temperature to obtain a mixed product after reaction, and carrying out gas-liquid separation on the mixed product to obtain target liquid ammonia.

Description

Liquid ammonia impurity removal method and system based on selective oxidation Technical Field The invention relates to a method and a system for removing impurities in liquid ammonia based on selective oxidation, and belongs to the technical field of energy-saving and environment-friendly industrial gas purification. Background With the continuous expansion and deepening of the application of liquid ammonia in the fields of high-purity agricultural nitrogen fertilizer, medical intermediates, fine chemical industry, electronic industry and the like, the purity requirement is increasingly strict, and especially, the residual trace hydrocarbon and sulfur impurities in the liquid ammonia can not only reduce the quality of a final product, but also cause the problems of catalyst poisoning, side reaction increase and the like in the subsequent catalysis process, thereby directly reducing the production efficiency and increasing the running cost. Patent technology CN105523570A discloses a preparation method of PPT-grade ultra-pure ammonia water, which comprises the steps of vaporization, purification and filtration, resin adsorption, washing, water-gas separation, multistage absorption and ultrafiltration. In the ultra-pure ammonia water obtained by the method, the particle concentration of more than or equal to 0.5 mu m is less than 3p/ml, the particle concentration of more than or equal to 0.2 mu m is less than 30 p/ml, and the single metal ion content is less than 30ppt. However, the method has simple process flow, undefined specific implementation process and control parameters and unsatisfactory impurity removal effect. The existing liquid ammonia impurity removal mostly adopts a catalytic oxidation technology, and hydrocarbon and other impurities are oxidized and converted into harmless substances by using a supported or composite catalyst in an oxygen-containing atmosphere, and although the method can realize higher removal efficiency under proper conditions, the existing catalyst lacks selective adsorption capacity for target impurities due to unreasonable control parameters, so that the liquid ammonia is difficult to realize selective removal of specific impurities in an environment containing multiple impurities. Disclosure of Invention The invention provides a method and a system for removing impurities from liquid ammonia based on selective oxidation, which adopt intelligent data analysis and combine a plurality of catalysts to furthest inhibit the liquid ammonia body from non-selective oxidation and realize the efficient removal of impurities. In order to achieve the above object, the invention provides a method for removing impurities in liquid ammonia based on selective oxidation, comprising the following steps: Obtaining impurity composition data of liquid ammonia to be treated, and carrying out desulfurization pretreatment on the liquid ammonia to be treated to obtain pretreated liquid ammonia, wherein the impurity composition data are used for determining the type of a catalyst, an oxygen content control range and a reaction temperature required by the liquid ammonia in a selective oxidation process; Introducing the pretreated liquid ammonia into a corresponding reactor, and establishing a selective oxidation reaction zone corresponding to the pretreated liquid ammonia in the reactor based on the catalyst type and the oxygen content control range; setting an oxygen content control value of the selective oxidation reaction zone in the oxygen content control range according to the catalyst type and the component characteristics of hydrocarbon in the pretreated liquid ammonia; based on the oxygen content control value and the reaction temperature, carrying out a selective catalytic oxidation reaction of the pretreated liquid ammonia in the selective oxidation reaction zone to obtain a mixed product after reaction, and carrying out gas-liquid separation on the mixed product to obtain target liquid ammonia. Optionally, based on the catalyst type and the oxygen content control range, establishing a selective oxidation reaction zone corresponding to the pretreated liquid ammonia in the reactor, wherein the selective oxidation reaction zone comprises: filling a copper oxide-cobalt oxide composite catalyst in the catalyst type into a fixed bed layer of the reactor to form a catalyst bed layer; introducing oxygen-containing carrier gas into the catalyst bed so as to enable the oxygen concentration in the catalyst bed to be within the oxygen content control range; when the oxygen concentration in the catalyst bed reaches the oxygen content control range, synchronously controlling the bed temperature of the catalyst bed at a preset reaction temperature to form the selective oxidation reaction zone. Optionally, introducing an oxygen-containing carrier gas into the catalyst bed to bring the oxygen concentration in the catalyst bed within the oxygen content control range, including: introducing mixed carrier g