scholarly journals Natural gas liquid (NGL) distillation process using driving force and thermal pinch analysis methods: Energy and economic assessment

Author(s):  
Munawar Zaman Shahruddin ◽  
Mohamad Hamidi Asri ◽  
Rohani Mohd Zin ◽  
Ahmad Nafais Rahimi ◽  
Muhammad Afiq Zubir ◽  
...  

Distillation column is one of the effective unit operations that is commonly used to separate chemical mixtures. The only drawback of this separation process is its huge energy consumption especially for a multicomponent separation process which involves a series of distillation columns. Therefore, an optimal sequence must be determined to address the issue. This research proposes the methodology to determine the optimal sequence of distillation columns by using driving force method. Then, thermal pinch analysis is applied to obtain further energy saving in the process. The case study selected is a distillation process to recover 5-component of natural gas liquid (NGL) mixture. Based on the input data, the driving force sequence is determined first and simulated together with a conventional sequence (direct sequence). Then, the extracted data from the simulation will be used for thermal pinch analysis via problem table algorithm (PTA). From the results of PTA, energy consumption between both sequences were compared including the energy consumption before and after the thermal pinch analysis. In addition, economic analysis has been performed as well to indicate which sequence has lower capital and operating costs based on the proposed heat exchanger network (HEN). According to the results, the combination of the driving force and thermal pinch analysis methods has successfully recorded 48% of energy savings and operating cost, and 58.2% capital cost saving compared to the conventional sequence (direct sequence). Therefore, it can be said that the proposed framework has a great potential to be employed towards the process and economic feasible distillation process.

2016 ◽  
Vol 78 (6-12) ◽  
Author(s):  
Ahmad Nafais Rahimi ◽  
Mohd. Faris Mustafa ◽  
Muhammad Zakwan Zaine ◽  
Norazana Ibrahim ◽  
Kamarul Asri Ibrahim ◽  
...  

The objective of this paper is to present the study and analysis of the energy saving improvement for the NGLs Direct-Splitter-Direct fractionation sequence plant by using driving force method. To perform the study and analysis, the energy efficient distillation columns (EEDCs) methodology is developed. Basically, the methodology consists of four hierarchical steps; Step 1: Existing Sequence Energy Analysis, Step 2: Optimal Sequence Determination, Step 3: Optimal Sequence Energy Analysis, and Step 4: Energy Comparison. The capability of this methodology is tested in designing an optimal energy efficient direct-splitter-direct sequence of NGLs fractionation unit. The results show that the maximum of 10.62 % energy reduction was able to achieve by changing the sequence suggested by the driving force method. It can be concluded that, the sequence determined by the driving force method is able to reduce energy used for a NGLs fractionation. All of this findings show that the methodology is able to design energy efficient for NGLs fractionation sequence in an easy, practical and systematic manner.


2015 ◽  
Vol 9 (7) ◽  
pp. 154
Author(s):  
Ahmad Nafais Rahimi ◽  
Mohd. Faris Mustafa ◽  
Muhammad Zakwan Zaine ◽  
Norazana Ibrahim ◽  
Kamarul Asri Ibrahim ◽  
...  

This paper presents the study of the optimal synthesis of energy efficient distillation columns (EEDCs) sequenceby using the driving force method. In order to perform the study and analysis, the EEDCs sequence methodologyhas been developed. Accordingly, the methodology consists of four hierarchical sequential steps; Step 1: ExistingSequence Energy Analysis, Step 2: Optimal Sequence Determination, Step 3: Optimal Sequence Energy Analysis,and Step 4: Energy Comparison. The capability of this methodology has been tested in designing minimumenergy distillation column sequence for hydrocarbon mixture separation process. The results show that themaximum of 39.6 % energy reduction was able to achieve by changing the sequence suggested by the drivingforce method. It can be concluded that, the sequence determined by the driving force method is able to reduceenergy requirement for hydrocarbon mixture separation process. All of this findings show that the methodologyis able to design minimum energy distillation column sequence for hydrocarbon mixture separation process in aneasy, practical and systematic manner.


2016 ◽  
Vol 78 (3-2) ◽  
Author(s):  
Muhammad Zakwan Zaine ◽  
Mohd. Faris Mustafa ◽  
Onn Hassan ◽  
Kamarul Asri Ibrahim ◽  
Norazana Ibrahim ◽  
...  

Energy savings is a major challenge in distillation operations. However, there is still one problem, which is how do we improve the energy efficiency of the existing distillation column systems without major modifications. Recently, a new energy efficient distillation columns methodology that will be able to improve energy efficiency of the existing separation systems without having major modifications has been developed. Therefore, the objective of this paper is to present a new improvement of the existing methodology by designing an optimal sequence of energy efficient distillation columns using a driving force method. Accordingly, the methodology is divided into four hierarchical sequential stages: i) existing sequence energy analysis, ii) optimal sequence determination, iii) optimal sequence energy analysis, and iv) energy comparison and economic analysis. The capability of this methodology is tested in designing an optimal synthesis of energy efficient distillation columns sequence of an aromatics separation unit. The existing aromatics separation unit consists of six compounds (Methylcyclopentane (MCP), Benzene, Methylcyclohexane (MCH), Toluene, m-Xylene and o-Xylene) with five direct sequence distillation columns being simulated using a simple and reliable short-cut method and rigorously tested within an Aspen HYSYS® simulation environment. The energy and economic analyses show that the optimal sequence determined by the driving force method has a better energy reduction with a total of 6.78% energy savings and a return of investment of 3.10 with a payback period of 4 months. It can be concluded that, the sequence determined by the driving force method is not only capable in reducing energy consumption, but also has a better economic cost for an aromatic separation unit


2016 ◽  
Vol 78 (6-12) ◽  
Author(s):  
Muhammad Zakwan Zaine ◽  
Mohd. Faris Mustafa ◽  
Kamarul Asri Ibrahim ◽  
Norazana Ibrahim ◽  
Mohd. Kamaruddin Abd. Hamid

Distillation operations became a major concern within sustainability challenge, which it becomes a primary target of energy saving efforts in industrially developed countries. However, there is still one problem, which is how do we improve the energy efficiency of the existing distillation columns systems by considering the sustainability criteria without having major modifications. Therefore, the objective of this paper is to present new improvement of existing methodology by including a sustainability analysis to design an optimal sequence of energy efficient distillation columns. Accordingly, the methodology is divided into four hierarchical sequential stages: i) existing sequence sustainability analysis, ii) optimal sequence determination, iii) optimal sequence sustainability analysis, and iv) sustainability comparison and design modification. The capability of this methodology is tested in designing an optimal sustainable energy efficient distillation columns sequence of aromatics separation unit using a simple and reliable short-cut method within Aspen HYSYS® simulation environment. The energy and sustainability analysis is performed and shows that the optimal sequence determined by the driving force method has better energy reduction with total of 6.78 % energy savings and 0.16 % sustainability reduction compared to existing sequence with. In addition, the economic analysis shows that the return of investment of 3.10 with payback period of 4 months. It can be concluded that, the sequence determined by the driving force method is not only capable in reducing energy consumption, but also has better sustainability index for aromatic separation unit.


2014 ◽  
Vol 699 ◽  
pp. 822-827
Author(s):  
Yasmin Syazwani Yusri ◽  
Rohani Mohd. Zin ◽  
Ruzitah Mohd Salleh

In Natural Gas Liquid (NGL) recovery, distillation process is the most common and widely used separation method. The productions of ethane, propane, butane and stabilized condensate are achieved through a series of conventional distillation columns which require massive amount of energy consumption, contributing more than 40% of the overall plant energy thus increasing the operating cost. This work focuses on energy saving in natural gas liquid processing by comparing the integrated side-stripper column with the conventional separation trains at steady state using a commercial simulator, Aspen Plus HYSYS. Energy analysis from the study shows that the integrated column arrangement which implement the side-stripper configuration achieved favourable result as it offers the highest percentage in energy reduction which is up to 68% (for reboiler) and 70% (for condenser). Consequently, this can be linked to the reduction of operating cost for hot and cool duties and trim down the overall production cost for existing NGL recovery plant.


Author(s):  
Fatemeh Safari ◽  
Arjomand Mehrabani-Zeinabad

Distillation is one of the most widely used separation units that consumes the largest amount of energy in chemical and petrochemical industries. Heat integration of thermally coupled distillation column is one of the methods to reduce energy-consumption. This paper provides a comparison between two simple columns with direct configuration and thermally coupled distillation column with direct sequence backward integration arrangement for separation of a ternary mixture based on energy-consumption. The influence of changing numbers of first and second column trays on heating and cooling rate of each column are investigated based on a developed mathematical model using conservation law of mass and energy and bubble-point method. The average relative error between calculated and industrial temperatures in some trays is about 0.74%. The condenser duty of high pressure column is about 9.73×109 kJ/h to provide heating of low pressure column. According to the simulation results, the thermally coupled construction saves energy about 50% more.


Author(s):  
Mehdi Mehrpooya ◽  
Parimah Bahramian ◽  
Fathollah Pourfayaz ◽  
Hadi Katooli ◽  
Mostafa Delpisheh

Abstract The production of liquefied natural gas (LNG) is a high energy-consuming process. The study of ways to reduce energy consumption and consequently to reduce operational costs is imperative. Toward this purpose, this study proposes a hybrid system adopting a mixed refrigerant for the liquefaction of natural gas that is precooled with an ammonia/water absorption refrigeration (AR) cycle utilizing the exhaust heat of a molten carbonate fuel cell, 700°C and 2.74 bar, coupled with a gas turbine and a bottoming Brayton super-critical carbon dioxide cycle. The inauguration of the ammonia/water AR cycle to the LNG process increases the cooling load of the cycle by 10%, providing a 28.3-MW cooling load duty while having a 0.45 coefficient of performance. Employing the hybrid system reduces energy consumption, attaining 85% overall thermal efficiency, 53% electrical efficiency and 35% fuel cell efficiency. The hybrid system produces 6300 kg.mol.h−1 of LNG and 146.55 MW of electrical power. Thereafter, exergy and sensitivity analyses are implemented and, accordingly, the fuel cell had an 83% share of the exergy destruction and the whole system obtained a 95% exergy efficiency.


Author(s):  
J Harrod ◽  
P J Mago

Due to the soaring costs and demand of energy in recent years, combined cooling, heating, and power (CCHP) systems have arisen as an alternative to conventional power generation based on their potential to provide reductions in cost, primary energy consumption, and emissions. However, the application of these systems is commonly limited to internal combustion engine prime movers that use natural gas as the primary fuel source. Investigation of more efficient prime movers and renewable fuel applications is an integral part of improving CCHP technology. Therefore, the objective of this study is to analyse the performance of a CCHP system driven by a biomass fired Stirling engine. The study is carried out by considering an hour-by-hour CCHP simulation for a small office building located in Atlanta, Georgia. The hourly thermal and electrical demands for the building were obtained using the EnergyPlus software. Results for burning waste wood chip biomass are compared to results obtained burning natural gas to illustrate the effects of fuel choice and prime mover power output on the overall CCHP system performance. Based on the specified utility rates and including excess production buyback, the results suggest that fuel prices of less than $23/MWh must be maintained for savings in cost compared to the conventional case. In addition, the performance of the CCHP system using the Stirling engine is compared with the conventional system performance. This comparison is based on operational cost and primary energy consumption. When electricity can be sold back to the grid, results indicate that a wood chip fired system yields a potential cost savings of up to 50 per cent and a 20 per cent increase in primary energy consumption as compared with the conventional system. On the other hand, a natural gas fired system is shown to be ineffective for cost and primary energy consumption savings with increases of up to 85 per cent and 24 per cent compared to the conventional case, respectively. The variations in the operational cost and primary energy consumption are also shown to be sensitive to the electricity excess production and buyback rate.


2016 ◽  
Author(s):  
S. Tesch ◽  
T. Morosuk ◽  
G. Tsatsaronis

The increasing demand for primary energy leads to a growing market of natural gas and the associated market for liquefied natural gas (LNG) increases, too. The liquefaction of natural gas is an energy- and cost-intensive process. After exploration, natural gas, is pretreated and cooled to the liquefaction temperature of around −160°C. In this paper, a novel concept for the integration of the liquefaction of natural gas into an air separation process is introduced. The system is evaluated from the energetic and exergetic points of view. Additionally, an advanced exergy analysis is conducted. The analysis of the concepts shows the effect of important parameters regarding the maximum amount of liquefiable of natural gas and the total power consumption. Comparing the different cases, the amount of LNG production could be increased by two thirds, while the power consumption is doubled. The results of the exergy analysis show, that the introduction of the liquefaction of natural gas has a positive effect on the exergetic efficiency of a convetional air separation unit, which increases from 38% to 49%.


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