What are the applications of deodorization towers in the energy industry
Information summary:The application of deodorization towers (whose core function is to remove odorous substances and harmful components from gases through adsorption, absorption, catalysis, etc.) in the energy industry is essentially to adapt to the "environmental compliance" and "safe operation" requirements of the entire energy production, processing, storage and transportation chain - various links in the energy i
The application of deodorization towers (whose core function is to remove odorous substances and harmful components from gases through adsorption, absorption, catalysis, etc.) in the energy industry is essentially to adapt to the "environmental compliance" and "safe operation" requirements of the entire energy production, processing, storage and transportation chain - various links in the energy industry are prone to produce sulfur-containing compounds (such as H ? S, thiols), volatile organic compounds (VOCs), amines, hydrocarbons and other odorous/harmful gases. Deodorization towers can solve these problems in a targeted manner. The specific application scenarios can be decomposed according to energy types and process links as follows:
1、 Fossil Energy Sector: Addressing Odor and Safety Hazards in the "Mining, Refining, and Storage" Processes
Fossil fuels (coal, oil, natural gas) are the most widely used fields for deodorization towers, targeting sulfur-containing odorous gases (such as H ? S, which is a typical odor source and has toxicity and corrosiveness) and hydrocarbon odors, covering the entire process from mining to terminal utilization:
1. Coal industry: Focus on odor control in the "coal washing" and "coking" processes
Coal washing plant: coal slurry/coal gangue waste gas treatment
In the process of coal washing, the slime water (including coal particles and organic impurities) will produce hydrogen sulfide (H ? S), ammonia (NH ∨) and humus odor due to microbial decomposition in the sedimentation tank and concentration tank, especially in the summer when the high temperature diffuses seriously, affecting the plant and surrounding environment. Deodorization tower (often using a combination of "spray absorption+activated carbon adsorption" process) can collect these waste gases, absorb H ? S and NH ∝ through alkaline spray solution (such as NaOH solution), and then adsorb residual organic odors through activated carbon to ensure that the exhaust gas meets the emission standards (in accordance with the "Emission Standards for Odor Pollutants" GB 14554-93).
2.Coking plant: treatment of coke oven gas and chemical product processing waste gas
Coking is the core process of converting coal into coke, which produces a large amount of coke oven gas (containing H ? S, thiols, benzene, naphthalene, etc.) and chemical products (such as tar, crude benzene) processing exhaust gas. These gases not only have strong odors, but also H ? S is highly corrosive (which can damage subsequent equipment), and benzene like substances are carcinogenic VOCs.
The application of deodorization tower in this stage can be divided into two categories:
Pre treatment deodorization: The coke oven gas is first subjected to a "wet desulfurization deodorization tower" (such as ammonia absorption method) to remove most of the H ? S, avoiding corrosion of subsequent gas purification equipment (such as benzene washing tower);
3.Terminal exhaust deodorization: For the exhaust gas generated from crude benzene distillation and tar processing, a "catalytic oxidation deodorization tower" (such as precious metal catalysts, which oxidize thiols and benzene into harmless SO ?, CO ?, and water) or an "adsorption deodorization tower" (activated carbon/molecular sieve adsorption) is used to ensure that the exhaust gas is odorless and meets VOCs standards.
2. Petrochemical industry: covering the entire process of "refining" and "chemical derivatives"
The petroleum refining (such as crude oil distillation and catalytic cracking) and downstream chemical processes (such as olefin production and aromatic hydrocarbon processing) will produce complex odorous gases such as sulfur-containing ethers, thiophenols, aldehydes, ketones, etc., and some gases (such as hydrogen sulfide and acrylonitrile) are toxic and must be treated in a deodorization tower before being discharged:
Refinery: Sour water stripping and catalytic cracking tail gas deodorization
The "acidic water" (containing high concentrations of H ? S and NH3) generated during the refining process, after being separated by the stripping device, will release high concentrations of H ? S gas. At this time, a "amine deodorization tower" (such as MDEA solvent absorbing H ? S to generate rich amine solution for regeneration and recycling, and H ? S being recovered to produce sulfur sulfide) is needed to eliminate odors and achieve resource recovery;
In addition to SO ?, the regenerated flue gas of the catalytic cracking unit also contains a small amount of thiols and sulfides, which need to be treated through an "alkali elution deodorization tower" or an "activated carbon adsorption deodorization tower" to avoid the diffusion of tail gas odors.
Petrochemical industry: Deodorization of tail gas from olefin/aromatic hydrocarbon plants
Ethylene cracking, styrene production and other facilities will produce odorous exhaust gases containing VOCs such as benzene, toluene, ethylbenzene, styrene, etc. These gases not only have unpleasant odors, but also belong to the precursor of photochemical smog. Deodorization towers often adopt a combination process of "adsorption desorption+catalytic combustion": VOCs are first captured by activated carbon adsorption towers, saturated, and then desorbed with hot air. The high concentration VOCs after desorption then enter the catalytic combustion tower for oxidation into CO ? and water, achieving "no odor+zero VOC emissions", which complies with the "Pollutant Emission Standards for Petrochemical Industry" GB 31571-2015.
3. Natural gas industry: Ensuring the safety and compliance of "extraction pipeline transportation terminal"
Natural gas (mainly composed of methane) itself is odorless, but during the extraction, processing, and storage processes, H ? S and organic sulfur (such as methyl mercaptan and ethyl sulfide) are mixed in. H ? S not only has a foul odor, but also corrodes gas pipelines and equipment, and even generates SO ? during combustion, polluting the environment; In addition, natural gas end-users (such as residents and industries) need to add "odorants" (such as tetrahydrothiophene) before use. If there is a pipeline leak or terminal equipment maintenance, a deodorization tower is required to treat the leaked gas:
Gas field extraction: deodorization of wellhead associated gas
The concentration of H ? S in the "associated gas" (including natural gas, H ? S, and condensate oil) produced from gas field wellheads may reach thousands of ppm. It needs to be removed from H ? S and organic sulfur through "desulfurization and deodorization towers" (such as alcohol amine method and molecular sieve adsorption method) to reduce the total sulfur content of natural gas to the national standard (GB 17820-2018 requires the total sulfur content of civilian natural gas to be ≤ 20mg/m 3), while eliminating odors.
Natural gas treatment plant: purification of exhaust gas and treatment of leaked gas after odorization
The "acid gas tail gas" (high concentration H ? S gas generated during the regeneration of the desulfurization unit) from the natural gas treatment plant needs to be treated with a "Claus process deodorization recovery device" (essentially a combination of deodorization tower and combustion furnace to convert H ? S into sulfur); If the odorant (tetrahydrothiophene) leaks in the factory area, the "activated carbon deodorization tower" needs to be activated to adsorb the leaked odorous gas and avoid the odor affecting the surrounding area.
LNG receiving station: BOG (evaporated gas) deodorization
When LNG (liquefied natural gas) is stored, BOG will be generated due to low-temperature leakage. If there is a small amount of organic sulfur or odorant residue in LNG, BOG will carry an odor. Deodorization towers (often using low-temperature adsorption processes such as molecular sieves) can remove odor components before BOG recovery or discharge, ensuring safe discharge.
2、 In the field of renewable energy: targeted solutions to the fermentation odor of biomass/biogas
Although renewable energy sources such as biomass and biogas belong to clean energy, the fermentation process of raw materials such as straw, livestock manure, and kitchen waste will produce strong odor gases. Deodorization towers are key equipment for the "environmental protection landing" of such projects
1. Biomass power generation/heating: raw material pretreatment and combustion exhaust deodorization
Biomass (such as straw and sawdust) will produce odorous gases such as ammonia, hydrogen sulfide, and fatty acids (such as butyric acid) due to microbial decomposition during storage, crushing, and drying processes; If the "biomass gasification" process is used, the tail gas of the gasifier will still contain a small amount of tar and phenolic substances, with strong odors.
Application scenarios of deodorization tower:
Raw material workshop: Collect the diffuse odors in the workshop through a "spray absorption deodorization tower" (such as acidic spray liquid absorbing NH3, alkaline spray liquid absorbing H2S);
Gasification tail gas: First, most of the tar is removed by the "tar trap", and then it enters the "activated carbon adsorption deodorization tower" to adsorb residual phenols and hydrocarbons, avoiding the generation of odors during tail gas emissions.
2. Biogas Engineering: Biogas Purification and Fermentation Tail Gas Deodorization
Biogas (mainly composed of methane, used for power generation or civilian use) is produced by the fermentation of livestock and poultry manure and kitchen waste. During the fermentation process, high concentrations of H ? S (500-5000ppm), ammonia, and indole (skatole) are generated. H ? S can corrode the engine and pipelines of biogas generators, while indole is a typical source of "fecal odor" and must be treated through deodorization towers
Biogas purification and deodorization: using "dry desulfurization and deodorization tower" (such as iron oxide desulfurizer) or "wet absorption deodorization tower" (such as NaOH solution) to remove H ? S, while adsorbing some organic odorous substances, so that the biogas meets the requirements of generator intake (H ? S ≤ 200ppm);
Fermentation workshop exhaust gas: Odorous gases emitted from fermentation tanks and storage tanks are treated through a "biological filter deodorization tower" (using microorganisms to decompose H ? S, ammonia, and indole as harmless substances). This process has low cost, no secondary pollution, and is suitable for long-term operation of large-scale biogas projects.
3、 Energy storage and terminal applications: solving temporary odors in the "leakage/maintenance" process
In addition to the production and processing process, temporary odor control measures are also required for energy storage and transportation (such as oil tankers, oil pipelines) and terminal applications (such as gas stations, industrial boilers) in case of leaks or maintenance
Gas Station/Oil Depot: Oil and Gas Recovery and Leakage Deodorization
During the unloading of oil from gas station tank trucks and refueling of cars, volatile "oil and gas" (including gasoline and diesel components, which belong to VOCs and have unpleasant odors) will be emitted. It needs to be treated through an "oil and gas recovery device+activated carbon deodorization tower": the oil and gas are first recovered through an adsorption tank, and a small amount of unrecovered oil and gas enters the deodorization tower for adsorption to avoid the spread of odors; During oil depot maintenance, the "oily wastewater and exhaust gas" generated from tank cleaning also need to be treated by a spray deodorization tower before being discharged.
Industrial boilers/kilns: Deodorization of exhaust gases from fuel combustion
Some industrial boilers use "high sulfur fuels" (such as high sulfur coal and heavy oil), and the combustion exhaust gas may contain small amounts of thiols and sulfides (incomplete combustion products) in addition to SO ?, resulting in unpleasant odors in the exhaust gas. At this time, a "catalytic deodorization tower" (such as vanadium titanium catalyst, which oxidizes organic sulfur to SO ? and further removes it through the desulfurization device) needs to be installed after the desulfurization tower to ensure that the exhaust gas is odorless.