Name | Natural gas desulfurizer |
Synonyms | Natural gas desulfurizer |
As an emerging energy source, natural gas is increasingly widely used. In China's environmental protection standards, it is strictly stipulated that when using natural gas energy, the H2S content in natural gas gas should not exceed 20mg/m3. Whether in industrial or civilian gases, H2S must be removed as much as possible.
When natural gas is produced from anaerobic fermentation plants, especially during medium or high temperature fermentation, it carries a large amount of H2S. Due to the presence of a large amount of water vapor in natural gas, the combined action of water and H2S in natural gas accelerates the corrosion of metal pipelines, valves, and flow meters
Blocking. In addition, S02 generated after H2S combustion is combined with the water vapor in the combustion product to form Sulfurous acid, which will cause corrosion on the metal surface of the designer, and will also cause pollution to the atmospheric environment and affect human health. Therefore, before using natural gas, it is necessary to remove H2S from it. The commonly used natural gas desulfurization methods in the industry include dry desulfurization, wet desulfurization, biological desulfurization, and other desulfurization methods,
1、 Overview
As an emerging energy source, natural gas has become increasingly widely used. In China's environmental protection standards, it is strictly stipulated that when using natural gas energy, the H2S content in natural gas must not exceed 20mg/m3. Regardless of whether in industrial or civilian gases, H2S must be removed as much as possible.
When natural gas is produced from anaerobic fermentation plants, especially at medium or high temperatures, it carries a large amount of H2S. Due to the presence of a large amount of water vapor in natural gas, the combined action of water and H2S in natural gas accelerates the corrosion and blockage of metal pipelines, valves, and flow meters. In addition, the $02 generated after H2S combustion is combined with the water vapor in the combustion products to form Sulfurous acid, which will corrode the metal surface of the equipment, and also cause pollution to the atmospheric environment, affecting human health. Therefore, before using natural gas, it is necessary to remove H2S from it.
2、 Desulfurization principle
1. Dry desulfurization
Dry desulfurization is a simple, efficient, and relatively low-cost desulfurization method that is generally suitable for natural gas desulfurization with small natural gas volume and low hydrogen sulfide concentration. The basic principle of the equipment for dry desulfurization of hydrogen sulfide (H2S) in natural gas is to oxidize H2S to sulfur or sulfur using O2
A method of oxidation, also known as dry oxidation. The composition of dry process equipment is to place fillers in a container, with a filler layer consisting of activated carbon, iron oxide, etc. The gas passes through the packing layer inside the container at a low flow rate, and hydrogen sulfide (H2S) is oxidized to sulfur or sulfur oxygen
After vaporization, the remaining gas is left in the packing layer, and the purified gas is discharged from the other end of the container.
Dry desulfurization mainly includes components such as the main steel structure, desulfurizer filler, observation window, pressure gauge, temperature gauge, etc. Desulfurization towers are usually designed as one for use and one for backup, with alternating use, i.e. one for desulfurization and one for regeneration.
Natural gas containing hydrogen sulfide (H2S) enters the bottom of the desulfurization tower, and during the process of passing through the desulfurization filler layer to reach the end of the project, H2S is separated from the desulfurization tower
The sulfur agent undergoes the following chemical reactions:
Step 1: Fe203 • H20+3 H2S=Fe2S3+4 H20 (desulfurization)
Step 2: Fe2S3+3/2 02+3 H20=Fe203 • H20+2 H20+3S (regeneration)
Natural gas containing hydrogen sulfide first reacts with a desulfurizer with a relatively high load at the bottom inlet. The upper part of the reactor is a desulfurizer layer with a low load. Through well-designed natural gas airspeed and line speed, dry desulfurization can achieve good precision desulfurization effect.
Before natural gas enters the dry desulfurization tower, a condensate tank or natural gas particle filter should be installed. This device can eliminate natural gas
The inclusion of particulate matter in natural gas causes it to contain a certain amount of humidity before entering the desulfurization process
When discoloration of the desulfurization agent or excessive pressure loss in the system is observed, another desulfurization tower should be used alternately. The current desulfurization tower undergoes natural ventilation after venting natural gas to regenerate the desulfurization agent. When the regeneration effect is poor, the waste desulfurizer should be discharged from the bottom of the tower body. At the same time as the waste filler is discharged from the bottom, fresh desulfurized filler of the same volume should be added to the reactor.
2. Wet desulfurization
Thermal desulfurization can be classified into three types: physical absorption method, chemical absorption method, and oxidation method. The physical and chemical methods have the problem of hydrogen sulfide reprocessing. The oxidation method uses alkaline solution as the absorbent, and adds oxygen carrier as the catalyst to absorb H2S and oxidize it into elemental sulfur. The wet oxidation method is to dissolve the desulfurizer in water, enter the equipment, and mix with natural gas. Hydrogen sulfide (H2S) in natural gas reacts with liquid to generate elemental sulfur and absorb hydrogen sulfide, including sodium hydroxide, Calcium hydroxide Sodium carbonate, Iron(II) sulfate, etc. The mature oxidation desulfurization method has a desulfurization efficiency of over 99.5%.
In large-scale desulfurization projects, wet desulfurization is generally used first for coarse desulfurization, followed by dry desulfurization for fine desulfurization.
The main body of the wet desulfurization tower includes a washing tower, a hydrogen sulfide sampling and monitoring system, an alkali solution configuration tank, a water supply soft water device, a liquid level control system, support components, and connectors. The desulfurization system achieves full automation by monitoring the concentration of hydrogen sulfide in the outlet gas and monitoring the pH value
Dynamic operation
During operation, natural gas passes through the desulfurization tower from bottom to top, and Na2C03 solution (or NaOH solution) is sprayed downwards from the neck, causing sufficient chemical reaction between H2S gas and alkaline solution.
Alkali liquor is stored below the desulfurization tower and automatically added through a metering pump. The dosing control of dead gas is automatically operated by monitoring the H2S concentration in the outlet gas.
When using sodium carbonate (Na2C03) reagent for desulfurization, the following reactions mainly occur:
H2S+Na2C03=NaHS+NaHGO3 (1)
C02+Na2C03+H20=2 NaHCO3 (2)
Due to the large amount of CO2 contained in natural gas, it also consumes alkaline solution. The system should be able to control reaction conditions (including reaction temperature and pH value), set the optimal reaction conditions, and minimize the consumption of alkaline solution as much as possible.