Reboiler heat energy recovery using integration process industries to increase their efficiency

Transcription

1 International Journal of Advanced Biotechnology and Research IJBR ISSN , Online ISSN X, Vol-7, Special Issue-March, 016, pp Research Article Reboiler heat energy recovery using integration process industries to increase their efficiency N. Damandarya* 1, J.Khorshidi and M.Ghafari 3 1& -Department of Mechanics Engineering, Bandar Abbas Branch, Hormozgan University, IRAN. ndamandarya@yahoo.com 3- Industrial Consulting SARKHON and Qeshm Gas Refinery ABSTRACT Exergy analysis of key science processes and the integration process is one of the most powerful tools in the study of the process to be employed. The purpose of the analysis, the amount of wasted axis and exergy efficiency in processing plants that help of this tool could be the most suitable criteria to improve and optimize the energy consumption of selected. In this study, the reboiler of unit 600, Glycol condensation unit of Sarkhon and Qeshm refinery gas were examined for optimization. For this purpose, using the analysis of outlet gas from the abovementioned reboiler stack, at first the equation of burning combustion process according to the mole coefficients of compositions of consumed fuels was obtained that this equation was the basis of calculations. The heating value of fuel was calculated to the amount of 77544/834 kj. In the following also, Exergy loss related to the mentioned process was obtained to the amount of /371 kj. According to the values related to the heating value of the fuel and Exergy loss, Exergy efficiency was calculated to the amount of 75/37%, also the destruction of Exergy and irreversibility of the process was calculated to the amount of 4/63% and 83177/143 kcal per hour, respectively. Keywords:Heat Recovery, Boiler, Reboiler, Exergy, Exergy destruction, irrevocably, preheater heat exchanger INTRODUCTION Nowadays, large amounts of hot gas resulting from the combustion of fuel for boilers, furnaces reboiler and a variety of different industries produced. This enables energy recovery in gas that large amounts of primary energy consumption to be reduced. Exergy analysis that reviews the recycling of waste and obtain the value axis.andexergy efficiency in processing plants is done [1]. In recent years many studies have been conducted to analyze Exergy process The majority of research to get Exergy efficiency are as follows: NosratiNia, et al Reduction in steam consumption reboiler ethane removal tower Ilam refinery uses energy integration were examined reboiler steam consumption in the 13/11 percent And the return on investment from this year will be $ 64,98 []. Mohammad ghadimi, et al, using technology to improve network energy integration of the heat exchanger and reduce energy consumption in MasjedSoleiman Gas Refinery examined. Reboiler 8 percent reduced fuel consumption [3]. Amir Javid, et al. using energy integration process in order to economise on energy consumption in oil distillation towers examine Dadnd.kh result, percent water saving, energy saving 14.6 percent and 14.6 oil consumption is save percentage. [4]. Islam kashi, et al optimizing the recovery of benzene and toluene Exergy analysis distillation tower recycling unit in one of the country's complex aromatic analyzed.reduces according to the results, the increase in temperature reduces the thermal load reboiler which helps to reduce waste exergy in this region. Preheats the pinch action took place and led to the condenser was removed and Exergy loss decreased by 10% [5]. In the present work using flue gas analysis

2 reboiler 600 units, condensing units Glycol earthquake and Qeshm Gas Refinery, Exergy reactants and products reboiler fuel combustion process as well as the process Exergy efficiency was calculated on the amount of 37/75. Exergy and irreversibility of the process of the destruction doses of 63/4% and is 143/ The values they express and the need for heat recovery process can be used multiple ways examined the recovery of heat in the process. The study process Home Feed 600 units, condensing units Sarkhon and Qeshm gas refinery glycol, glycol probe that is sent to glycol recovery unit to effect separation of hydrocarbon liquid made of water glycol. The mixture is then separated into the tank of liquid hydrocarbon / glycol sent to high water Glycol Separation of hydrocarbon fluids to be done. Figure 1: Diagram of glycol regeneration process solated Glycol Glycol is transmitted to the device condensed hydrocarbon liquid and sent to the drainage system. The effect of reducing the pressure and temperature elevation, part of hydrocarbons, as a gas, and the separated liquid is dumped. Redundant gas to be sent to the torch burning. This mixture then enters the tank hydrocarbon glycols and glycol flash vaporization Hydrkrbn and become filled with water and vapor hydrocarbons. Vapor burner system Feller Post and glycol is condensed tower. Glycol output of the tank level control, control and into the reboiler. Reboiler has two rows of tubes 18-inch oven with chimney is removable by fuel gas, is fed. Glycols from the bottom of the tower and into the reboiler shell. The reboiler for heating and boiling mixture of glycol and water, in order to separate the excess water from the glycol are used. During this process, water vapor moved to the top of the tower and condensed glycol from the bottom of the tower reboiler goes out and transfer pumps glycol. To save power consumption and a Table :reboiler tube side flow profile [7] smaller footprint, the tower reboiler condensers have been installed and connected to it [6]. inner diameter Along The thickness of the outer casing 1/ 54 m 6/ 096 m 50/ 8 mm Heat transfer surface 33/7m The amount of heat in normal mode kcal per hour Design pressure 1Relative Bar Design temperature 150 C Table 1: Profile reboiler Tower condensed [6] In the present work reboiler 600 units, condensing units Glycol earthquake and Qeshm gas refinery to optimize and reduce fuel consumption are examined.exergy fuel combustion process one kilogram mole of the mentioned exergy efficiency is calculated. Exergy efficiency is achieved due to the need to express heat recovery, heat recovery process should be studied. View incoming and outgoing flows in the shell and tube reboiler 600 units are given in Tables and 3. Fuel Gas output 409 Flow g the reboiler tubes fuel Fuel Gas input Stream Name 44.8 Temperature c N. Damandarya, et al. 307

3 Pressure BAR FlowKg Mole/Hr Kg/HrThe mass flow rate M 3 /Hrvolumetric flow Kg/MoleMolecular Weight MethaneMol.% EthanMol.% PropaneMol.% BhutanMol.% PentaneMol.% HexaneMol.% Table3: reboiler shell side flow profile [7] Flow cool side reboiler shell glycol + water Low water glycol Glycol water filling output inlet Stream Name Liquid Liquid Phase Type Glycol flow Water flow Total flowkg Mole/Hr mass flow rate Kg/Hr volumetric flowm 3 /Hr Temperature 1.5 PressureBARA Kg/Mole Molecular Weight DensityKg/M 3 Governing equations Exergy and Exergy efficiency equation to get the first one kilogram per mole of fuel burning earns And then the heating value of the fuel and reactants and products and thus ExergyExergy efficiency is calculated. 1-Earning equation for a kilo of hair burning of fuel According to the reactants according to Table 5 the mole percent and the overall equation burning of hydrocarbons as well as Formula 1, taking into account the following assumptions, equation Mole of fuel burned per kilogram achieved. Complete combustion reaction, a mixture of ideal gases, taking into account the temperature of 5 C as the reference temperature T0 for both reactants and products and citizenship Cp of temperature. C n H n+ + O nco + n+1h O 1 Products MW kg mol N Table 4: Molecular weight and mole fraction Products Using Formula 1, the equation for burning a kilogram mole of each of the reactants is obtainedthen, according to the reboiler fuel gas consumption in dark gray and Qeshm gas refinery unit 600 is a combination of several gas.the the mole percent of each of which is given in Table 5,The field equations for a kilo of MoleOf each of the reactants with respect to the the mole percent of of each component are obtained.in the final equation for burning a kilo of fuel mole of the aforementioned solutions, achieved. Mole fraction N CO H O O N. Damandarya, et al. 308

4 Table 5: molecular weight and the mole percent of reactants [8] Reactant MW kg Mol.% mol Mole fraction N CH C H C H C H C H C Table 6: mole fraction of combustion air and products for a kilo of Mole Reactions Products NO. O N CO H O O N the mole percent of reactants C1 C C3 C4 C5 C6 Figure : Diagram of Molly reactants Calorific value fuel Fuel heating value LHV, one of the parameters needed to calculate the second law efficiency that is, the amount of heat that is released by burning it completely with dry air. N. Damandarya, et al. 309

5 Calculate the heating value fuel To obtain the fuel heating value, due to the constant pressure, reactants and products, as well as the calculation. And its numeric value is calculated according to the formula. Computing Cp dt In this section, according to the coefficient Cp each component of the reactants and products using Formula 3, for the reactants and products can be obtained. It should be noted that the above formula is the temperature in Kelvin. Get the value H rxn 3 Table7: enthalpy of products[ 9-10] Products h f in5 c h p T ht h f h N h CO H O O N Table8: enthalpy of reactants [9-10] Reactants h f in 5 c h C pt h T h f h N h CH C H 6 C H 8 C H 10 C 5 H P N h - C H 6 1 O N N h R N. Damandarya, et al. 310

6 Reactants h f in 5 c h C pt h T h f h N h CH C H 6 C H 8 C H 10 C 5 H C H 6 1 O N N h R Exergy calculation reactants and combustion products kg mol of the fuel and exergy efficiency Exergy calculated reaction Exergy balance used in a process suggests that how much potential can be used or exergy in the form of input parameters to be entered, by the process, is used. 1-Exergy loss Exergy loss or irreversible quantitative criterion for measuring the inefficiency of the process. After calculating the reactants and products Exergy, Exergy loss reaction can be obtained as follows: -The second law efficiency The second law of return calculation Exergy efficiency as defined in Formula 7 is carried out.according to calculations, the amount of reaction Exergy efficiency is 75.37% the amount necessary to optimize the processes taken place in the reboiler specifies. CONCLUSION In the present work reboiler 600 units and Qeshm gas refinery earthquake were investigated, For this purpose, the exhaust flue gas analysis of the reboiler,the equation was burning combustion process according to the molar ratio composition of fuels used was found that the equation was the basis of calculations.using the equation to obtain C p dt the quantities of reactants and products of burning and, also, H rxn Heating value fuel to the amount of _77544/834 calculated.then as Exergy losses related to the process for the amount of /371 respectively.according to the values of the heating value of the fuel and waste Exergy, Exergy efficiency was calculated to amount 75/37.The amount of heat necessary for N. Damandarya, et al. 311

7 the process of recycling states.exergy and irreversibility of this process as well as the Parameter Q Combustion Q C CpdT R CpdT P H rxn destruction of foreign 4/63 percent and 83177/143 respectively. value b R b P η th E dest 4.63 Table9: Results I Figure 3: Diagram of process Exergy destruction Figure 4: Diagram of the irreversibility of the process N. Damandarya, et al. 31

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