Development of an Online Soft Analyzer for the Continuous Analysis of BTEX Emissions from the Furnace of Sulfur Recovery Units

2021 ◽  
Author(s):  
Satyadileep Dara ◽  
Salisu Ibrahim ◽  
Abhijeet Raj ◽  
Ibrahim Khan ◽  
Eisa Al Jenaibi
Keyword(s):  
Kinetic Model ◽  
Soft Sensor ◽  
Sulfur Recovery ◽  
Furnace Temperature ◽  
Fuel Gas ◽  
Gas Processing ◽  
Wide Range ◽  
Gas Consumption ◽  
Reaction Furnace ◽  
Co Emission

Abstract The oxidation of Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) in the furnace of SRUs at high temperature is an effective solution to prevent Claus catalyst deactivation in the downstream catalytic converters. However, the existing SRUs do not have the means to monitor BTEX emissions from Claus furnace due to lack of commercial online analyzers in the market. This often leads to excessive temperatures up to 1150 °C in the furnace to ensure BTEX destruction. Such high temperatures increase fuel gas consumption and CO emission and reduce sulfur recovery efficiency. To obtain continuous BTEX indication at the furnace exit, an online BTEX soft sensor model is developed to predict BTEX concentration at furnace exit. Subsequently, this soft sensor will be implemented in one of the SRUs of ADNOC Gas Processing. The BTEX soft sensor has been developed by constructing a compact kinetic model for aromatics destruction in the furnace based on the understanding of BTEX oxidation mechanisms derived using a detailed and well validated kinetic model developed previously. The kinetic model, including its rate parameters were incorporated into Hysys/Sulsim software, where both the reaction furnace and catalytic converters were simulated. The BTEX soft sensor has been validated with plant data from different ADNOC Gas Processing SRU trains under a wide range of feed conditions (particularly, with varying relative concentrations of H2S, CO2, and hydrocarbons in acid gas feed) in order to ensure its robustness and versatile predictive accuracy. The model predicts BTEX emissions from the reaction furnace under a wide range of operating conditions in the furnace with deviation not exceeding +/- 5 ppm. It also predicts the reaction furnace temperature (with a deviation of +/- 5%) and species composition from the furnace exit within a reasonable error margin. Presently, the model is in the process of being deployed in one of the SRUs of ADNO Gas Processing as an online soft sensor, where it can read the feed conditions, predict the BTEX exit concentration and write this value to the DCS. Thus, plant operators can monitor BTEX exit concentration on continuous basis and use it as a reliable basis to lower fuel gas co-firing rate in the furnace to achieve optimum furnace temperature that provide efficient BTEX destruction and low CO emission. The online soft analyzer, when deployed in SRU, will continuously predict BTEX emission from SRU furnace with high accuracy, which cannot be done experimentally in the plant or reliably using most of the existing commercial software. This approach can be used to seek favorable means of optimizing BTEX destruction to enhance sulfur recovery, while decreasing fuel gas consumption and carbon footprint in sulfur recovery units to reduce operating cost.

Investigating Three Different Models for Simulation of the Thermal Stage of an Industrial Split-Flow SRU Based on Equilibrium-Kinetic Approach with Heat Loss

2018 ◽  
Vol 14 (1) ◽  
Author(s):  
Mohammad Hossein Kardan ◽  
Reza Eslamloueyan
Keyword(s):  
Kinetic Model ◽  
Heat Loss ◽  
Conversion Efficiency ◽  
Waste Heat ◽  
Molar Ratio ◽  
Percentage Error ◽  
Sulfur Recovery ◽  
Waste Heat Boiler ◽  
Split Flow ◽  
Reaction Furnace

Abstract Modified Claus process is the most important process that recovers elemental sulfur from H2S. The thermal stage of sulfur recovery unit (SRU), including the reaction furnace (RF) and waste heat boiler (WHB), plays a critically important role in sulfur recovery percentage of the unit. In this article, three methods including kinetic (PFR model), equilibrium and equilibrium-kinetic models have been investigated in order to predict the reaction furnace effluent conditions. The comparison of results with industrial data shows that kinetic model (for whole the thermal stage) is the most accurate model for simulation of the thermal stage of the industrial split-flow SRU. Mean absolute percentage error for the considered kinetic model is 4.59 %. For the first time, the consequences of considering heat loss from the reaction furnace on calculated molar flows are studied. The results show that considering heat loss only affects better prediction of some effluent molar flow rates such as CO and SO2, and its effect is not significant on the results. Eventually the effects of feed preheating on some important parameters like sulfur conversion efficiency, H2S to SO2 molar ratio and important effluent molar flows are investigated. The results indicate that feed preheating will reduce the sulfur conversion efficiency. It is also noticeable that by reducing the feed temperature to 490 K, H2S/SO2 molar ratio reaches to its optimum value of 2.

scholarly journals Investigating efficiency improvement in sulfur recovery unit using process simulation and numerical modeling

2021 ◽  
Vol 76 ◽  
pp. 18
Author(s):  
Farhad Fazlollahi ◽  
Sajjad Asadizadeh ◽  
Milad Ahmadi Khoshooei ◽  
Mohammad Reza Sardashti Birjandi ◽  
Majid Sarkari
Keyword(s):  
Numerical Modeling ◽  
Hydrogen Sulfide ◽  
Numerical Model ◽  
Process Simulation ◽  
Sulfur Recovery ◽  
Furnace Temperature ◽  
Acid Gas ◽  
Gas Streams ◽  
Recovery Unit ◽  
Reaction Furnace

Hydrogen sulfide exists mostly as a detrimental byproduct in the gas processing units as well as refineries, and it must be eliminated from natural gas streams. In a Sulfur Recovery Unit (SRU), hydrogen sulfide is converted into the elemental sulfur during the modified Claus process. Efficiency of sulfur recovery units significantly depends on the reaction furnace temperature. In this work, the effect of oxygen and acid gas enrichment on the reaction furnace temperature and accordingly on sulfur recovery is studied, using both numerical modeling and process simulation. Then, simulation and numerical model are benchmarked against the experimental data of an SRU unit. The validated model provides spotlight on optimizing the upstream sulfur removal unit as well as the oxygen purification process. Two cases of acid gas streams with low and high H2S content, 30% and 50%, are studied to investigate the effect of operating parameters on the overall recovery. Finally, average errors of the models are presented. According to the absolute difference with experimental values, the developed numerical model shows great potential for accurately estimating overall efficiency of the recovery unit.

Rationalization of Flares at Terminal Island

2021 ◽  
Author(s):  
Tehsin Akhtar ◽  
Bablu Kumar Maiti
Keyword(s):  
Thermal Radiation ◽  
Radiation Effects ◽  
Oil And Gas ◽  
Land Reclamation ◽  
Ground Level ◽  
Maintenance Cost ◽  
Offshore Platforms ◽  
Fuel Gas ◽  
Gas Processing ◽  
Gas Consumption

Abstract This study aims to assess potential opportunities for optimizing the number of flares operated by COMPANY at the Terminal Island with oil and gas processing, storage and export facilities, while considering ongoing and future developments on the island and possible integration with flare network of other downstream Company. The different flare systems cater to flaring requirements of HP, MP and LP systems in oil and gas processing plants at the island. The fundamental drivers for flare systems rationalization study are disadvantages associated with greater number of flares such as: More plot area usage for flares at expense of industrial expansion Increased HSE risks in terms of thermal radiation and dispersion of toxic gases More fuel gas consumption as purge and pilot gas Higher operational and maintenance costs In this study, existing flares at Terminal Island were studied and options were developed for each flare system with the aim of rationalizing the number of flares. These options included demolition of flares, diversion and redistribution of respective flare loads to other flares. Relocation of flares to offshore platforms / reclaimed areas in sea and replacement of elevated flare with enclosed ground flare, which has negligible thermal radiation was also considered. The rationalization options developed for each flare system were evaluated on the basis of factors such as recovered sterile area, reduction in purge gas (Hydrocarbon and Nitrogen) and pilot gas consumption, maintenance cost, operation cost, number of flares and estimated investment as CAPEX (for modification scope). The current and future flare loads were taken into account while developing these options. The flare design capacities, available capacities for accommodating additional flare loads, sterile area freed along with minimization of associated dispersion and thermal radiation effects at ground level after demolition of flares were also considered for generation of suitable rationalization options. A simplified and optimized flaring network at Terminal Island operated by COMPANY was developed by reducing the number of flares based on techno-economic screening, while safeguarding the operational and safety requirements. As concluded from the study, eight (8) nos. of flares occupying significant sterile radii can be demolished out of total fourteen (14) nos. of existing flares. The sterile area recovered (approximately 77,000 m2) as result of flares rationalization is of great value and importance for building new facilities. The land recovered can be used for future developmental projects on the island instead of opting for land reclamation. In addition, COMPANY's objectives to reduce environmental impact, associated HSE risks and thermal radiation intensity at surrounding areas / facilities will also be achieved.

Modified Regeneration Scheme for Energy Efficient Gas Dehydration

2021 ◽  
Author(s):  
Haseeb Ali ◽  
Saqib Sajjad
Keyword(s):  
Molecular Sieve ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Energy Savings ◽  
Waste Heat ◽  
Fuel Gas ◽  
Additional Advantage ◽  
Gas Processing ◽  
Gas Compression ◽  
Gas Consumption

Abstract Molecular Sieve Dehydration units are used for dehydration of natural gas prior to gas processing or transportation. A molecular sieve dehydration system consists of multiple adsorbers which remove water during adsorption cycle until they get saturated with water. Regeneration of a saturated adsorber is performed by passing a hot regeneration gas stream through the adsorber. The hot regeneration gas after passing though the adsorber is then cooled before sending to regeneration gas compression. If an aircooled exchanger is used to cool the hot regeneration gas, heat available in the hot spent regeneration gas ends up in the atmosphere. In this context, an in-house study was performed to examine techno-economic viability of waste heat recovery from the hot spent regeneration gas using a modified regeneration scheme at one of the gas processing sites. The modified scheme involves installation of a new waste heat recovery (WHR) exchanger to exchange the heat available in the hot regeneration gas with regeneration heater's inlet regeneration gas thereby reducing the fuel gas consumption in the regeneration heater as well as power consumption in regeneration gas cooler fans. The study comprised design and operation data collection and analysis followed by assessment of key challenges. The key challenges include performance of the heater in WHR case (i.e. lower fuel gas consumption), space availability for the new WHR exchanger and modifications in the existing system. A thermodynamic model was developed for running various operating scenarios and estimating the WHR potential, including heater's specific fuel gas consumption analysis at varying temperatures, to establish realistic fuel gas savings. Overall, the study has indicated significant energy savings with good financial indicators for the proposed regeneration scheme. It has also showed reduction of peak heat duty of heater & cooler, thus providing an additional advantage of reduced CAPEX for future projects.

Ambient Condition Effects on NOx and CO Emissions From Process Heaters

2008 ◽  
Author(s):  
Wesley R. Bussman ◽  
Charles E. Baukal
Keyword(s):  
Atmospheric Pressure ◽  
Ambient Air ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Ambient Conditions ◽  
Fuel Gas ◽  
Natural Draft ◽  
Actual Operating ◽  
Wide Range ◽  
Pollution Emissions

Because process heaters are typically located outside, their operation is subject to the weather. Heaters are typically tuned at a given set of conditions; however, the actual operating conditions may vary dramatically from season to season and sometimes even within a given day. Wind, ambient air temperature, ambient air humidity, and atmospheric pressure can all significantly impact the O2 level, which impacts both the thermal efficiency and the pollution emissions from a process heater. Unfortunately, most natural draft process burners are manually controlled on an infrequent basis. This paper shows how changing ambient conditions can considerably impact both CO and NOx emissions if proper adjustments are not made as the ambient conditions change. Data will be presented for a wide range of operating conditions to show how much the CO and NOx emissions can be affected by changes in the ambient conditions for fuel gas fired natural draft process heaters, which are the most common type used in the hydrocarbon and petrochemical industries. Some type of automated burner control, which is virtually non-existent today in this application, is recommended to adjust for the variations in ambient conditions.

scholarly journals Effect of air combustion preheater on furnace efficiency by using refinery simulator

2021 ◽  
Vol 7 (3) ◽  
pp. 75-87
Author(s):  
Dr.Yosif J. Kadhem Almosawi ◽  
Warqaa A. Kadhem Alshimmary
Keyword(s):  
Crude Oil ◽  
Pressure Control ◽  
Operating Conditions ◽  
Oil Refining ◽  
Fuel Gas ◽  
Air Preheater ◽  
Heating Efficiency ◽  
Gas Consumption ◽  
The Right ◽  
Heating Up

One of the basic crude oil refining steps is the heat up to high temperature about 3700 C, which is done in the furnace. The balance between fuel and air required to combustion provide an economical and efficient heating. In this research operating data of heating up the furnace are collected by using an interactive simulator of Drilling System Company (ORTIS) which gives a flexibility of operation cannot be obtained in real furnace, these data are related to find the operation paths under different control system of manual, automatic and working automatic without pre-heating are used . Using of combustion air preheater, by exchanging heat with the flue gases, leading to increase furnace heating efficiency from 85% to 93% also the fuel supplied to the burners is more less than working without preheater. As the simulator used in this research very closed to real operating system of furnace which cover all the variables of furnace inside temperatures, excess air analyzer, and fuel gas control and inside pressure control. The using of interactive simulator is very useful in stating the right operating conditions. The use of pre-heating of combustion air is best economical method to reach heating the crude oil to the required temperature with minimum fuel gas consumption, which directly affects the efficiencies of the furnace in each case.

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