Petroleum and natural gas industries - Offshore production installations - Process safety systems

2019 ◽  
1973 ◽  
Vol 13 (05) ◽  
pp. 297-306 ◽  
Author(s):  
A. Rosman

Abstract To develop reliable design data for glycol contactors, gas-liquid equilibria in the system water-methane-triethylene glycol (TEG) were investigated experimentally. Equilibrium values vary little at the very high TEG concentrations used in modern contactor design, but increase significantly with increasing water concentration in the contacting TEG, and with increasing equilibrium temperature. Various methods of data correlation are described and compared with experimental data. The correlation provides the means for extending the results of this investigation to other pressures and temperatures. Introduction Water removal is a fundamental operation in natural gas processing. Hydrate formation, corrosion, and the formation of liquid water that might separate in the transmission lines are some of the problems caused by an excess of water in the gas. Of the methods available for gas dehydration, water absorption is by far the most generally used. Glycols, especially triethylene glycol (TEG), are the preferred absorbents. A survey of the literature on the water dew point of natural gas over glycol solutions reveals point of natural gas over glycol solutions reveals significant disagreements. A sampling of published dewpoint data for gas in equilibrium with TEG (Fig. 7) illustrates the prevailing confusion. Scant, but still contradictory, information was published for glycol concentrations in excess of 99.8 weight percent. Data in that range are needed in designing percent. Data in that range are needed in designing modern glycol contactors where the water dewpoint temperature must be reduced by more than 100 deg. F. The main reason for discrepancies in experimental results is the difficulty of measuring accurately very small amounts of water in gas. Water is easily adsorbed on the surfaces of experimental apparatus. Normally acceptable data scatter looms large in relation to the low water concentrations that must be measured. Attempts to establish water dew points on the basis of plant performance have been points on the basis of plant performance have been more successful. However, accuracy is limited by the difficulty in establishing the relative contribution of various factors that interrelate in plant operation. plant operation. Faced with these doubts, contactor designers have chosen to provide for TEG circulation rates that are overly high so as to insure more than adequate water removal. Such a practice is undesirable, however, where space and power are at a premium, as on offshore production platforms. Thus, the range of this investigation was governed by the need to extend equilibrium information to the contact temperatures and TEG concentrations necessary m optimize glycol contactors on offshore production platforms. production platforms. New procedures were developed for sampling and analyzing very small concentrations of water in gas and in TEG. To avoid experimental difficulties encountered by previous authors, equilibrium was reached and samples were taken under dynamic conditions. Experimental equilibrium results were smoothed and correlated by several methods. Thermodynamic equations were used to check on the internal consistency of data and to calculate equilibrium constants at conditions outside the range of the investigation itself. The White expression, fitted to the COFRC experimental data, adequately describes the results within the range of temperatures and concentrations studied. DEFINITIONS AND METHODS At water dewpoint temperature, the water contained in a natural gas reaches saturation. Part of that water will condense if the gas is brought to a lower temperature or to a higher pressure. Thus, the "dewpoint temperature" describes the water content of the gas. When dewpoint gas contacts TEG, the water content of the gas decreases. The lower water content corresponds to saturation water at a lower temperature; that is, the dew point will be lower. The initial dewpoint temperature is the contacting temperature. The temperature corresponding to the lowered water content is the equilibrium dewpoint temperature, and the difference between the two temperatures is the dewpoint depression. SPEJ P. 297


2019 ◽  
Vol 8 (3) ◽  
pp. 3723-3731

It is known that the price of natural gas liquids (NGL) is higher than that of natural gas from which it is derived, so more modifications needed for existing plants to derive more NGL is economically accepted point of view. The main objective of the present work is to present the method applied on Trans gulf (T/G) gas plant to overcome its performance decrease happened after the plant feed gases becoming leaner than its design margin and hence it led to a great decrease in the plant NGL recovery. This achieved by introducing a new simple modification to the existing process scheme obtained by using a condensate stream to enrich the reflux of the de-ethanizer tower so more recovery is obtained. In order to accomplish that goal, some changes in the existing process operating conditions were needed. A simulation is used in this study to examine the existing and the introduced modification utilizing ASPEN-HYSYS software version 8.4 using Peng-Robinson equation of state (EOS). The simulation of the existing plant results in a better understanding of the plant behavior in the different iterations to reach the maximum benefits. The plant after suffering from low butane recovery from its feed gas and which considered as a figure to the plant efficiency, it increased by this method from 38 % to reach 86-90 % butane recovery and its LPG production increased by 170% to be ≈ 122 tonne/day instead of ≈ 44 tonne/day while only losing ≈ 16 tonne/day of condensate production. An optimization to the new method is done in this paper so that it doesn't intercept with the existing plant equipment performance for the process safety triggers. Also, the last section of the study describes the economic point of view and the return on investment (ROI) how it was paid back only in 7 days. This modification can be taken as a guideline for both new and existing LPG plants which use only propane refrigeration systems for LPG recovery to increase their profits with the lowest cost possible.


2009 ◽  
Vol 49 (2) ◽  
pp. 570
Author(s):  
Ron Reinten

Safety is a core value at Esso Australia. We strive to observe the highest standards of safety to ensure that nobody gets hurt in our operations. We believe this goal can be achieved through a broadly shared commitment to personal and process safety—both of which are managed using our operations integrity management system (OIMS). In the Gippsland region of Victoria, Esso Australia operates oil and gas production facilities ranging from sub-sea completions to substantial staffed offshore facilities, an onshore crude stabilisation, three gas processing plants and a natural gas liquids fractionation plant, all interconnected by a network of offshore and onshore pipelines. Every day Esso’s Gippsland operations produce millions of litres of crude oil and millions of cubic meters of natural gas. Having all this fuel energy flowing through these plants each day at high pressures, and widely ranging temperatures, it is imperative that it is safely controlled and contained by the process equipment. How do we do this? With process safety systems. Process safety is a crucial component of OIMS that ensures Esso’s assets are operated and maintained in keeping with corporate and industry safety standards. In this presentation we show how process safety is managed within OIMS and how the people within Esso individually and collectively contribute to it. Our work in this area has recently been captured in a training package that includes a DVD shown at the conference. It was created to raise the awareness and understanding of all Esso employees about the principles that underpin Esso’s approach to process safety. This abstract outlines how we approach process safety across the life-cycle of our facilities and the role people play in managing this very important aspect of our work. Our training reinforces the message that responsibility for effective management of process safety lies with every employee and how OIMS is designed to assist people to achieve the desired results where all risks are appropriately managed. We have sought to connect the concepts used to manage personal safety, which are well understood by the workforce, with those that are needed to understand how to manage process safety.


2021 ◽  
Vol 61 (2) ◽  
pp. 567
Author(s):  
Clinton Smith

Sequestration of carbon dioxide (CO2) is an increasingly popular method of reducing the environmental impact of natural gas and blue hydrogen development projects. While the hazards associated with natural gas processing are well understood, high pressure CO2 presents unique challenges which must be overcome by designers to make sequestration a safe and practical option. Many of these hazards are ultimately due to the CO2 phase envelope. Compression of CO2 for injection into a reservoir can involve the creation of a dense phase fluid, which shares some of the properties of both liquid and gas. Upset conditions can also create either liquid or solid CO2. These can create unforeseen consequences such as potential blockage and overpressure of vent piping, condensation and freezing of free water and inaccurate level transmitter readings. Further, the partial pressures of CO2 involved mean that corrosion rates for any carbon steel exposed in the presence of free water may be as high as 1mm per week. These safety challenges and potential solutions to them will be explored in this study.


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