Tail Gas Treatment Unit Research Articles

SRU TGTU Hydrogenation Catalyst Lifecycle Best Practices

This report highlights the best practices captured in the management of Tail-Gas Treatment Unit (TGTU)’s hydrogenation CoMo catalyst throughout its lifecycle, these best practices were developed based on success story in operating the TGTU, which provides technical framework to manage TGTU unit performance throughout TGTU catalyst lifecycle. The aforementioned TGTU CoMo catalyst management best practices span across the whole catalyst lifecycle, starting from cradle stage of activating/sulphiding the fresh oxide-form catalyst up to grave stage of unloading & handling the spent catalyst to a safe location. Furthermore, stressing points have been provided to record special procedure to activate catalyst’s active sites (Cobalt & Molybdenum) in a process commonly known as “sulphiding”, as well as “passivation” procedure during TGTU catalyst unloading due to the presence of pyrophoric material such as Iron Sulphide (FeS) in the TGTU converter. This developed best practices provide solid reference point for future TGTU catalyst management throughout its lifecycle. Therefore, it can be adopted and consistently applied across other TGTU-based Sulfur Recovery Unit (SRU) plants in order to maintain the optimum Sulfur Recovery Efficiency (SRE), minimize plant downtime due to catalyst replacement and prevent unwanted environmental issues such as SO<sub>x</sub> emissions).

A comparison between Claus and THIOPAQ sulfur recovery techniques in natural gas plants

A sulfur recovery process is one of the most important processes in the oil and gas industry to get rid of hydrogen sulfide (H2S) which is produced from the acid gas removal process of sour natural gas to convert it into sweet natural gas. Actual data from a gas field is used to obtain a realistic comparison between two sulfur recovery techniques, through which researchers and/or manufacturers can obtain information that will help them choose the most appropriate and cheapest method. A total feed acid gas flow rate of 5.1844 MMSCFD with an H2S concentration of 24.62% by mole percent was produced from amine acid gas removal units. Claus sulfur recovery technique is a traditional chemical process that uses thermal and catalytic reactors. Therefore, an acid gas enrichment unit is applied to increase the H2S concentration to approximately 50% mole to provide reliable and flexible operation in the thermal and catalytic reactors. Moreover, a tail gas treatment unit is applied to increase the overall conversion efficiency to 99.90% with the Claus technique instead of 95.08% without it to achieve high sulfur recovery and reliable operation through the conversion of carbonyl sulfide (COS) and mercaptans. Studies on the safety and simplicity of the Claus technique revealed many important hazards and a large number of transmitters (379) and control loops (128) in one Claus train. THIOPAQ sulfur recovery as a new technology is a biological desulfurization process that uses a natural mixture of sulfide-oxidizing bacteria. It is also a unique H2S removal process with an efficiency of 99.999%. In addition, studies on the safety and simplicity of the THIOPAQ technique have shown that the hazards, the number of transmitters (74), and the number of control loops (29) of a one THIOPAQ train are lower. The THIOPAQ technique showed higher efficiency, was safer, simpler, and had lower CAPEX and OPEX. This study was conducted using Aspen HYSYS V11 and actual data.

Comparison of oxidation absorption and reduction absorption process for sulfur recovery tail gas treatment of natural gas treatment plants in China Part Ⅰ: Technical section

BackgroundChina's newest SO2 emission policy for the natural gas industry forced natural gas treatment plant to add sulfur recovery tail gas treatment unit. In this context, the oxidation absorption process has been applied for the first time in Sichuan Basin. However, the advantages and disadvantages of this process compared with the traditional reduction absorption process have not been reported. MethodsThe two processes were compared from the technical angle in this paper. The data of one plant in Sichuan Basin was selected as the simulation condition. Significant findingsThe calculation results showed good agreement with plants data. The solution circulation amount of oxidation absorption process were 19 and 18.52 m3/h, which were just 20 %∼25 % of that for reduction absorption process. Meanwhile the acid gas returned amount was only about 14 % of reduction absorption process. However, the main process gas flow was 1.5 times of reduction absorption process. Regarding the utility consumptions, the oxidation absorption process had more advantages in electricity consumption, but it was inferior in fuel gas and circulating water consumption.

Conversion of medical waste into value-added products using a novel integrated system with tail gas treatment: Process design, optimization, and thermodynamic analysis

The COVID-19 pandemic has generated substantial medical waste (MW), posing risks to society. Based on widespread MW incineration, this study proposes an integrated system with tail gas treatment to convert MW into value-added products with nearly zero emissions. Herein, steam generators and supercritical CO2 cycles were used to recover energy from MW to produce high-temperature/pressure steam and electricity. A simple power generation cycle achieved a net electricity efficiency of 22.4% through optimization. Thermodynamic analysis revealed that the most energy and exergy loss occurred in incineration. Furthermore, a pressurized reactive distillation column purified the resultant tail gas. The effects of inlet temperature, pressure, liquid/gas ratio, and recycle ratio on the removal and conversion efficiencies of NO2 and SO2 were evaluated. Nearly 100% of the SO2 and 75% of the NO2 generated by the incineration of MW have been converted into their acid forms. Based on the proposed tail gas treatment unit, high-purity CO2 (∼98% purity) was finally obtained.

Double-Diffusive Mixed Convection and Radionuclides Removals from the Tail Gas Treatment Unit in Nuclear Medicine Building: Multiple Sifting Structures and Porous Medium

This paper investigates the effect of porous-media arrangement, hot-plate arrangement, heat flux, and inlet flow on the mixed convection heat transfer, and uniformity of temperature and concentration in an open enclosure. This model is considered for use as an adsorption treatment unit for radioactive waste gas in a nuclear medicine building. The radioactive waste gas flows through the cavity from bottom to top. The two-dimensional governing equations have been solved using the finite volume method. The Prandtl number and aspect ratio of the cavity are fixed at 0.71 and 1, respectively. The problem has been governed by five parameters: −10 ≤ Br ≤ 10, 10−6 ≤ Da ≤ 102, 0.1 ≤ Kc ≤ 10, 10−2 ≤ Ri ≤ 10, and 0.1 ≤ Kr ≤ 10, and the layouts of the porous layer and hot plates. The simulation results indicate that the Type C (polymeric porous media) has excellent heat transfer characteristics with a 10% increase in the Nusselt number (Nu). The contours of streamlines, isotherms and heatlines indicate that, with the increase of Richardson number (Ri), the trend of Nu varies for different arrangements of hot plates. It is interesting to note that the convective heat transfer of Type F (surrounded arrangement) was found to have the lowest Nu number for the same Ri number. The convective heat transfer is more pronounced for Type E (symmetrical arrangement). The Nu number of Type E (symmetrical arrangement) is about 110% higher than that of Type F (surrounded arrangement) and it is about 35% higher than that of Type D (centralized arrangement). This type also has a more uniform temperature distribution, as indicated by the temperature variance. The findings of this study can guide preheating system optimization.

Design and Analysis of Exhaust Gas Treatment Device for Drilling Diesel Engine

In this paper, a kind of exhaust treatment device for drilling diesel engine with simple structure, low resistance, high filtration efficiency, wide collecting particle size range and low energy consumption was designed. Using RNG $$k - \varepsilon$$ turbulence model, the gas-phase flow field of the tail gas treatment unit and the gas-phase flow field of the conventional cyclone separator without corona pole were numerically calculated, and the three-dimensional velocity distribution law of the flow field in the tail gas treatment unit was studied. Compared with the conventional cyclone separator, the results show that the tangential velocity disturbance of the inner flow field is more obvious, the mean tangential velocity decreases, and the velocity in the outer vortex area decreases by 20%. Meanwhile, due to the influence of corona electrode, the eddy current flow in the treatment device is more disordered. The inner axial velocity of the processing device is slower in the down-flow area and larger in the up-flow area. Relatively speaking, the radial velocity magnitude is small, and the distribution is non-axisymmetric.

Effect of temperature stress on main structure in waste incineration power generation plant

Waste incineration power station includes many functional structures, such as garbage discharge, storage, sorting and feeding units, boiler unit, tail gas treatment unit, leachate treatment unit, and coal storage unit. The structural forms of each part are different. Because of the particularity of garbage, structure units are required to be as close as possible and temperature joints should not be set up for the sake of possible leakage of exhaust gas or effluent liquor, so various structural units are integrated, which leads to the difficulty in structure design, and thermal stress cannot be neglected. In order to understand the effect temperature stress on main plant structures, a finite element model is established to study the distribution of thermal stress of the whole structure under three conditions: heating in summer, cooling in winter and heating in winter. It is found the influence of temperature on frame beam, column and steel space truss can be neglected, and the thermal stress on floor cannot be neglected [1]. The maximum stress is mainly distributed on both edges of floor along the longitude direction of structure. For those regions where stress concentration occurs, reinforcement bands or reinforcement mesh can be used to reduce the tensile stress. The analysis results show that this measure is effective and provides a reference for the design of the main structure of waste incineration power plant. This paper innovatively analyses the structure system of main workshop of refuse incineration power plant, which is composed of steel structure and concrete structure, and describes the skills and key points of complex system modeling. According to different seasons and heating temperature difference, the temperature stress on the surface of the structure is analyzed, which provides a reference for calculating degree stress and temperature difference of the similar structure system. The weak part of resistance to temperature stress in the structure system composed of concrete structure and steel structure is found out, and the corresponding solutions are put forward, which provides guidance for the construction of the main workshop of refuse incineration power station.

Case Study for the Optimization of a Tail Gas Treatment Unit

Case Study for the Optimization of a Tail Gas Treatment Unit

CO2 Capture from Sulphur Recovery Unit Tail Gas by Shell Cansolv Technology

A significant driver for the climate change effect is CO2 emission from the sources where fossil fuel is consumed to generate energy. Capturing and sequestration of CO2 from these emission sources is a practical way to mitigate GHG emission impact. However the cost of CCS projects has been a major obstacle to implementing these technologies worldwide. Two main aspects which influence the cost of a CO2 capture project are the CO2 utilization pathway and the CO2 capture technology selection.CO2-Enhanced Oil Recovery (EOR) can be a very good potential pathway to increase the revenue of the CCS project. CO2-EOR also can be an attractive way of using CO2 in areas such as Middle East where the oil and gas reservoirs are mature. However one of the main constraints can be limited access to CO2 especially where no power plant is close to a potential oil reservoir.For technology selection, the choice is typically between Pre- and Post-Combustion. Pre-combustion CO2 capture technologies have been deployed in oil refineries & gas processing plants for decades, but the main source for CO2 emissions in these facilities is often off-gas (also known as acid gas) which is usually sent to the flare system or incinerator. These off-gases are at low pressure, so a compression system is required to pressurize the gas before sending it to the Pre-combustion CO2 capture unit. On the other hand, Post-combustion CO2 capture technology can often require an additional desulfurization step to remove SO2 which can potentially result to higher operational and capital cost as well as waste management and complexity of operation. This paper will discuss the deployment of Shell Cansolv technology to capture CO2 from off-gas downstream of the Sulfur Recovery Unit (SRU) in a single train, potentially as a new CCS application in the oil and gas sectors.The off-gas from Tail Gas Treatment Unit (TGTU) downstream of the SRU will usually contain a higher amount of CO2 compared to coal and gas power plants. The absorption affinity of Shell Cansolv solvent at low pressure off-gas compared to other pre-combustion technologies allows the elimination of the primary compression system located upstream of the CO2 capture unit. Since there is H2S slippage from the TGTU absorber overhead, the amine should be characterized in terms of absorption affinity and stability in the reduced environment. The impact of H2S on amine performance in terms of degradation has been investigated in comparison to a post-combustion application where H2S is incinerated and converted to SOx. SOx contaminates amine to form Heat Stable Salt (HSS), so it needs to be removed prior to the post-combustion CO2 capture unit in a separate FGD unit (Flue Gas Desulfurization). Shell Cansolv DC amine in pre-combustion lineup absorbs both H2S and CO2 in a single absorber so incinerator and FGD unit is not required compared to post-combustion applications. Shell Cansolv DC amine has been tested to remove up to 99% CO2 which is higher than the 90% typical capture rate for most post-combustion applications. The other advantage of this application is the ability to operate at high temperature (∼60 C). This is often a key design parameter especially in the Middle East where most applications are considered hot climate applications. All design parameters of the CO2 capture unit such as liquid per gas ratio (L/G), stripping factor at the regenerator side and absorber packing height have been evaluated and optimized to reduce both capital and operational costs of the project. Eventually, in a case study, an economic comparison was conducted and the result indicated potentially more than 40% reduction in the cost of a CO2 capture unit as well as same magnitude increase in Net Present Value (NPV) compared to pre-combustion technology.

A process simulation study of hydrogen and sulfur production from hydrogen sulfide using the Fe–Cl hybrid process

Presently, most of the acid gas (H2S) streams from amine gas sweetening and refinery upgrading operations are treated using the modified Claus process. In this process, sulfur and low-quality steam are produced by partial oxidation of H2S. Despite the modified Claus process's success in accomplishing the above tasks, it still has some disadvantages. Additional tail gas treatment unit is needed to improve its efficiency. Also, a valuable commodity, hydrogen, is not recovered.In this work, a process simulation study on the Idemitsu Kosan Co. Fe–Cl hybrid process is carried out. The process is capable of producing sulfur and hydrogen from H2S gas streams. The process was modeled and validated using pilot-scale plant data before been scaled up using the typical acid gas composition profile of one of Abu Dhabi's sulfur recovery plants. The effects the absorber solution flow rate and concentration have on the process’ operability were investigated. Operating at high ferric ions concentration was found to be more beneficial compared to high solution flow rate operations. The ferrous ion constituent of the solution proves to be instrumental in the downstream electrolysis process. Cost estimates of the process indicate the suitability of the process to be implemented in Abu Dhabi gas plants to produce sulfur, and most importantly, hydrogen to be used as fuel or chemical feedstock.

Economic assessment of Temperature Swing Adsorption systems as Claus Tail Gas Clean Up Units

Current regulations of SOx emissions require Sulfur Recovery Units (SRUs) to achieve recoveries in excess of 99.9%. Capital cost of existing commercial Claus Tail gas clean up technologies capable of achieving that benchmark can amount to 45% of the total capital cost of the SRU. Adsorption based processes hold significant potential for achieving the targeted recovery at lower costs considering their high selectivity towards removal of ppm level contaminants. This work assesses the economics of a Tail Gas Treatment Unit relying on a Temperature Swing Adsorption module for treating a typical industrial feed. An optimization problem is formulated and solved to determine the designs that minimize Net Present Worth (NPWC) of total capital investment,operating and bed replacement costs ensued during a 30 years project life. The total capital investment contribution of the optimized TGTU is around $20M comprising ~65% of the NPWC value. Operating costs ranged between $3.0 and $3.6 per tonne of sulfur. Both figures compare favorably with commercial technologies.

A Simulation of a Claus Tail Gas Treatment Unit in a Petroleum Refinery

More treatment is needed for sulfur recovery unit tail gas, due to its high pollution. In this research, an Iranian petroleum refinery was selected as a case study. In the proposed refinery, incineration is used for treatment of tail gas. As incineration is not an environment-friendly process, an amine-based process has been selected as the best method for treatment of tail gas. The selected process was simulated with HYSYS and Aspen-Plus software. Different parameters and their changes were investigated through the simulation and optimum conditions were achieved. Also, comparison of results of two simulation softwares was done.

96/03656 Catalysts for hydrogenation of heavy oils and hydrogenation of heavy oils using them

Presently, most of the acid gas (H2S) streams from amine gas sweetening and refinery upgrading operations are treated using the modified Claus process. In this process, sulfur and low-quality steam are produced by partial oxidation of H2S. Despite the modified Claus process's success in accomplishing the above tasks, it still has some disadvantages. Additional tail gas treatment unit is needed to improve its efficiency. Also, a valuable commodity, hydrogen, is not recovered.In this work, a process simulation study on the Idemitsu Kosan Co. Fe–Cl hybrid process is carried out. The process is capable of producing sulfur and hydrogen from H2S gas streams. The process was modeled and validated using pilot-scale plant data before been scaled up using the typical acid gas composition profile of one of Abu Dhabi's sulfur recovery plants. The effects the absorber solution flow rate and concentration have on the process’ operability were investigated. Operating at high ferric ions concentration was found to be more beneficial compared to high solution flow rate operations. The ferrous ion constituent of the solution proves to be instrumental in the downstream electrolysis process. Cost estimates of the process indicate the suitability of the process to be implemented in Abu Dhabi gas plants to produce sulfur, and most importantly, hydrogen to be used as fuel or chemical feedstock.