CN-117049473-B - Natural gas hydrogen production method and hydrogen production control system thereof

CN117049473BCN 117049473 BCN117049473 BCN 117049473BCN-117049473-B

Abstract

The invention relates to the field of natural gas hydrogen production, in particular to a natural gas hydrogen production method and a hydrogen production control system thereof. A new adsorption material, doped graphene silica gel, is provided. The doped graphene silica gel is made of porous materials and can conduct electricity, the gas adsorption performance of the doped graphene silica gel in a conducting state can be changed along with the change of voltage, so that the adsorption performance of the doped graphene silica gel can be further controlled by means of adjusting the voltage, the pressure swing adsorption effect is further improved, and energy sources are saved. The invention firstly carries out deoxidization operation in the pressure swing adsorption process, so that almost no oxidizing gas exists in the pressure swing adsorption process, no danger is caused in the voltage loading process, and the pressure swing adsorption safety is greatly improved. Meanwhile, the preparation method of the doped graphene silica gel is simple in preparation process, less in consumable and low in cost.

Inventors

HUANG HAORAN
LI XINZHONG
LIU DONGMEI
ZHANG YUN

Assignees

芜湖朗卓新材料科技有限公司

Dates

Publication Date: 20260508
Application Date: 20230725

Claims (3)

1. A method for producing hydrogen from natural gas, comprising the steps of: Natural gas introduction, primary desulfurization, secondary desulfurization, steam conversion, carbon monoxide conversion, catalytic desulfurization and hydrogen purification; the natural gas is introduced into a first-stage desulfurizing tower for first-stage desulfurization, and most of sulfur elements in the natural gas are removed by the first-stage desulfurization; Then the gas is subjected to secondary desulfurization, sulfur elements in the natural gas are hydrogenated to prepare H 2 S for removal, and the removed H 2 S enters a catalytic desulfurization tower for catalytic desulfurization; Catalytic desulfurization is carried out, H 2 S is contacted with a catalyst, and the catalyst carries out chemical reaction and adsorption on sulfur element, so that hydrogen is extracted; steam conversion is carried out on the natural gas after the secondary desulfurization to obtain carbon monoxide and hydrogen, and then the gas enters a carbon monoxide conversion tower to be further converted to obtain carbon dioxide and hydrogen; Hydrogen after catalytic desulfurization and carbon monoxide conversion enters a hydrogen purification tower to carry out hydrogen purification, and the purified hydrogen is output through a hydrogen output pipeline; The hydrogen purification step adopts a pressure swing adsorption method, and the pressure swing adsorption at least comprises the following steps: Deoxidizing by reduction, pressurizing and adsorbing, decompressing and desorbing, flushing at low pressure and pressurizing; pressurizing and adsorbing, namely filling hydrogen into a pressurizing and adsorbing tower to adsorb, and adsorbing impurity gas by an adsorbing material in the adsorbing tower; decompression desorption, namely decompressing after discharging hydrogen, and desorbing and discharging impurity gas in the decompressed adsorption material; Flushing the adsorption material at low pressure to regenerate the adsorption material; pressurizing, namely charging gas to enable impurity gas to be compressed upwards to the top of the adsorption tower, The adsorption material is a doped graphene electrostatic adsorption material; the graphene-doped electrostatic adsorption material is graphene-doped silica gel, graphene is doped into silica gel particles to obtain a porous electrostatic controllable adsorption material which is graphene-doped silica gel, The preparation method of the doped graphene silica gel comprises the following steps: Taking a certain amount of sodium silicate, adding 3-5 times of water for dilution, and filtering to obtain sodium silicate solution; Weighing sodium silicate solution, adding sodium bicarbonate solution with 2-3 times of mass under ultrasonic oscillation, adding graphene powder under oscillation, continuously stirring for 3-5min to make the liquid fully and uniformly mixed, continuously oscillating for 1-2 hr, standing for precipitation after oscillation is completed, regulating pH value of precipitate to 3.2-3.5, standing for more than 24 hr, oven drying at normal temperature to obtain graphene doped silica gel particles, The pressurized adsorption is carried out in an adsorption tower, wherein a plurality of layers of adsorption materials are arranged in the adsorption tower, and the adsorption materials are doped with graphene silica gel; in the pressurized adsorption process, a voltage control unit is used for loading voltage to the doped graphene silica gel, and the size of the loaded voltage is adjusted according to the concentration of impurity gas; in the decompression desorption process, a voltage control unit is used for loading voltage to the doped graphene silica gel, the size of the loaded voltage is adjusted according to the concentration of gas, the concentration of sodium bicarbonate solution is 3-4%, and dilute sulfuric acid is used for adjusting the pH value.
2. The method for producing hydrogen from natural gas according to claim 1, further comprising a step of measuring doped graphene silica gel, wherein the step of measuring doped graphene silica gel is performed before all the steps, and specifically comprises the following steps: Firstly, placing doped graphene silica gel in a vacuum environment, measuring the variation of the maximum adsorption capacity of the doped graphene silica gel along with the loading voltage under the condition of determining the concentration of impurity gas, finding the loading voltage with the maximum adsorption capacity, wherein the loading voltage with the maximum adsorption capacity is the optimal adsorption voltage, and the loading voltage with the lowest adsorption capacity is the optimal desorption voltage; And (3) changing the concentration of the impurity gas, and measuring the optimal adsorption voltage and the optimal desorption voltage under different impurity gas concentrations, thereby obtaining a function U M (c) of the optimal adsorption voltage along with the change of the impurity gas concentration and a function U m (c) of the optimal desorption voltage along with the change of the impurity gas concentration.
3. The method for producing hydrogen from natural gas according to claim 2, wherein in the process of pressure adsorption, a voltage control unit is used to load voltage on the doped graphene silica gel, the magnitude of the loaded voltage is adjusted according to the concentration of the impurity gas, and a function U M (c) of the optimal adsorption voltage along with the change of the concentration of the impurity gas is utilized; in the decompression desorption process, a voltage control unit is used for loading voltage to the doped graphene silica gel, the size of the loaded voltage is adjusted according to the concentration of the gas, and the loaded voltage is not higher than 100v in the doped graphene silica gel measurement step by utilizing a function U m (c) of the optimal desorption voltage along with the change of the concentration of the impurity gas.

Description

Natural gas hydrogen production method and hydrogen production control system thereof Technical Field The invention relates to the field of natural gas hydrogen production, in particular to a natural gas hydrogen production method and a hydrogen production control system thereof. Background The natural gas hydrogen production technology is based on the technology of natural gas steam conversion, and is characterized in that natural gas is pretreated, methane and water vapor are converted into carbon monoxide, hydrogen and the like in a reformer, after waste heat is recovered, carbon monoxide is converted into carbon dioxide and hydrogen in a converter. In the shift tower, the reaction temperature is controlled in the presence of catalyst to react carbon monoxide and water in the converted gas to produce hydrogen and carbon dioxide. Because of the problem of low gas purity in the hydrogen production of natural gas, the hydrogen purification is required to be carried out finally; the current hydrogen purification mainly adopts a pressure swing adsorption method, the main influencing factor of which is the adsorption performance of the adsorption material, and how to develop new adsorption materials and how to further improve the adsorption performance of the adsorption materials is an important technical problem to be solved at present. Disclosure of Invention In order to solve the problems, the invention provides a method for producing hydrogen by natural gas, which comprises the following steps: Natural gas introduction, primary desulfurization, secondary desulfurization, steam conversion, carbon monoxide conversion, catalytic desulfurization and hydrogen purification; the natural gas is introduced into a first-stage desulfurizing tower for first-stage desulfurization, and most of sulfur elements in the natural gas are removed by the first-stage desulfurization; Then the gas is subjected to secondary desulfurization, sulfur elements in the natural gas are hydrogenated to prepare H 2 S for removal, and the removed H 2 S enters a catalytic desulfurization tower for catalytic desulfurization; Catalytic desulfurization is carried out, H 2 S is contacted with a catalyst, and the catalyst carries out chemical reaction and adsorption on sulfur element, so that hydrogen is extracted; steam conversion is carried out on the natural gas after the secondary desulfurization to obtain carbon monoxide and hydrogen, and then the gas enters a carbon monoxide conversion tower to be further converted to obtain carbon dioxide and hydrogen; hydrogen after catalytic desulfurization and carbon monoxide conversion enters a hydrogen purification tower to be purified, and the purified hydrogen is output through a hydrogen output pipeline. The hydrogen purification step adopts a pressure swing adsorption method, and the pressure swing adsorption at least comprises the following steps: Deoxidizing by reduction, pressurizing and adsorbing, decompressing and desorbing, flushing at low pressure and pressurizing; deoxidizing by reduction, oxidizing oxygen and oxidizable gas in the hydrogen product gas, and improving the safety of the subsequent pressure adsorption and pressure reduction desorption steps; pressurizing and adsorbing, namely filling hydrogen into a pressurizing and adsorbing tower to adsorb, and adsorbing impurity gas by an adsorbing material in the adsorbing tower; decompression desorption, namely decompressing after discharging hydrogen, and desorbing and discharging impurity gas in the decompressed adsorption material; Flushing the adsorption material at low pressure to regenerate the adsorption material; pressurizing, namely charging gas, so that impurity gas is upwards compressed to the top of the adsorption tower. The adsorption material is a doped graphene electrostatic adsorption material; The graphene-doped electrostatic adsorption material is graphene-doped silica gel, and graphene is doped into silica gel particles to obtain the porous electrostatic controllable adsorption material which is graphene-doped silica gel. The preparation method of the doped graphene silica gel comprises the following steps: Taking a certain amount of sodium silicate, adding 3-5 times of water for dilution, and filtering to obtain sodium silicate solution; Weighing sodium silicate solution, adding sodium bicarbonate solution with the mass of 2-3 times under ultrasonic oscillation state, adding graphene powder under oscillation, continuously stirring for 3-5min to enable the liquid to be fully and uniformly mixed, continuously oscillating for 1-2 hours, standing for precipitation after oscillation is completed, regulating the pH value of the precipitate to 3.2-3.5, standing for more than 24 hours, and drying at normal temperature to obtain graphene-doped silica gel particles. The concentration of sodium bicarbonate is 3-4%, and dilute sulfuric acid is used for regulating the pH value. The pressurized adsorption is carried out in an adsor