Evaluation on Energy Efficiency Improvement in Geothermal Power Plant with The Application of Load-based Gas Removal System and Cooling Water Pump Control System

Efficient Geothermal Power Plant (GPP) operation can be achieved through the optimum use of steam for turbine and auxiliary (ejectors), and minimum possible condenser pressure for maximum energy conversion in the turbine. In all GPPs, a condenser vacuum is maintained by adequate circulation of cooling water and effective operation of ejectors, which absorb the accumulation of Non-Condensable Gas (NCG), mostly CO2 and H2S, and dispose it to the atmosphere. Typically, GPPs are designed for baseload (100% capacity) operation. Therefore, the performance of supporting equipment such as ejectors and cooling water pumps are not sensitive to load-set fluctuations or changes in NCG content. This fact consequently results in constant parasitic load and ejector's motive steam consumptions. Since 2017 many GPPs in Indonesia have no longer operated at constant full capacity following demand fluctuation, as stated in grid dispatcher's Daily Operating Plan. This condition brings up energy efficiency opportunity to reduce steam and electricity own use through modification or installation of the load-following controller in the ejector system and cooling water pumps. The study aimed to identify the best alternative in devising this adaptive feature in gas removal and circulating water systems from economic and technical aspects. Evaluation's methodology included the development of GPP process modeling and data validation, setting up an alternative framework, testing of GPP performance for each alternative with the calibrated model, and decision analysis from economic and technical aspects to select the best option. The evaluation showed that the ejector's motive steam flow controller was able to reduce auxiliary steam usage at maximum by 7% (equal to 0.7 MWe). In comparison, the circulation water flow controller with Variable Frequency Drive (VFD) could reduce pumps electricity use by 35% (0.76 MWe). The study results recommended the implementation of a motive steam flow controller over the pump's VFD, considering its economic performance, operation flexibility, and lower execution risk. A B S T R A KOperasi Pembangkit Listrik Tenaga Panas Bumi (PLTP) yang efisien dapat dicapai melalui penggunaan uap yang optimal pada turbin dan sistem pendukung (ejektor), serta pengaturan tekanan kondensor yang rendah untuk mencapai konversi energi maksimum di turbin. Pada hampir semua PLTP, kevakuman kondensor dijaga melalui sirkulasi air pendingin yang memadai, dan efektivitas operasi ejektor dalam menghisap akumulasi Non-Condensable Gas (NCG), yaitu CO2, dan H2S, serta dispersinya ke atmosfer. Pada umumnya PLTP didesain untuk beroperasi pada basis bebannya (100% kapasitas) sehingga kinerja peralatan penunjang seperti ejektor dan pompa tidak sensitif terhadap fluktuasi beban pembangkitan maupun perubahan kandungan NCG dari sumur. Hal ini mengakibatkan pemakaian listrik sendiri dan konsumsi uap ejektor pada PLTP cenderung tetap. Sejak 2017 banyak PLTP di Indonesia tidak lagi beroperasi dengan kapasitas penuh karena mengikuti fluktuasi permintaan grid seperti yang dinyatakan dalam Rencana Operasi Harian dari pengatur beban. Kondisi ini memberi peluang upaya efisiensi energi untuk mengurangi konsumsi listrik dan uap melalui modifikasi dan instalasi pengontrol load-following pada sistem kerja ejektor dan pompa sirkulasi air pendingin. Studi ini bertujuan untuk mengidentifikasi alternatif terbaik dalam merancang fitur adaptif ini, baik dari aspek ekonomi maupun teknis. Metodologi evaluasi mencakup pengembangan pemodelan proses PLTP dan validasi datanya, menyiapkan kerangka evaluasi alternatif, pengujian kinerja PLTP untuk setiap alternatif dengan model yang terkalibrasi, dan analisis pemilihan opsi terbaik secara ekonomi dan teknis. Hasil evaluasi menunjukkan bahwa pengontrol aliran uap motif pada ejektor mampu mengurangi penggunaan uap maksimum sebesar 7% (setara 0,7 MWe), sedangkan pengontrol aliran air sirkulasi dengan Variable Frequency Drive (VFD) dapat mengurangi penggunaan pompa listrik sebesar 35% (0,76 MWe). Hasil studi merekomendasikan penerapan sistem pengontrol aliran uap motif pada ejektor dibandingkan aplikasi VFD pada pompa dengan mempertimbangkan kinerja ekonomi, fleksibilitas operasi, dan risiko eksekusinya yang lebih rendah

Synthesis and Activity Test of Cu/ZnO/Al2O3 for the Methanol Steam Reforming as a Fuel Cellâs Hydrogen Supplier

The  synthesis  of  hydrogen  from  hydrocarbons  through  the  steam reforming  of  methanol  on  Cu/ZnO/Al2O3  catalyst  has  been  investigated.  This process is assigned to be one of the promising alternatives for  fuel cell hydrogen process source. Hydrogen synthesis from methanol can be carried out by means of  methanol  steam  reforming  which  is  a  gas  phase  catalytic  reaction  between methanol and water. In this research, the  Cu/ZnO/Al2O3  catalyst  prepared by the dry  impregnation  was  used.  The  specific  surface  area  of  catalyst  was  194.69 m2/gram.The  methanol  steam  reforming  (SRM)  reaction  was  carried  out  by means of the injection of gas mixture containing methanol and water with 1:1.2 mol ratio and 20-90 mL/minute feed  flow rate to a fixed bed reactor loaded by 1 g of catalyst. The reaction temperature was 200-300 °C, and the reactor pressure was 1 atm. Preceding  the reaction, catalyst was reduced in the H2/N2  mixture at 160  °C.  This  study  shows  that  at  300  °C  reaction  temperature,  methanol conversion  reached  100%  at  28  mL/minute  gas  flow  rate.  This  conversion decreased  significantly  with  the  increase  of  gas  flow  rate.  Meanwhile,  the catalyst prepared for SRM  was stable in 36 hours of operation at 260  °C. The catalyst exhibited a good stability although the reaction condition was shifted to a higher gas flow rate

Utilizing Shear Factor Model and Adding Viscosity Term in Improving a Two-Dimensional Model of Fluid Flow in Non Uniform Porous Media

In a packed bed catalytic reactor, the fluid flow phenomena are very complicated because the fluid and solid particle interactions dissipate the energy. The governing equations  were developed in the  forms of  specific  models. The shear factor  model was introduced in the momentum equation for covering the effect  of  flow  and  solid  interactions  in  porous  media.   A  two  dimensional numerical  solution  for  this  kind  of  flow  has  been  constructed  using  the  finite volume  method.  The  porous  media  porosity  was  treated  as  non-uniform distribution  in  the  radial  direction.  Experimentally,  the  axial  velocity  profiles produce  the  trend  of  having  global  maximum  and  minimum  peaks  at  distance very close to the wall. This trend is also accurately picked up by the numerical result. A more comprehensive shear factor formulation results a better velocity prediction than other correlations do. Our derivation on the presence of porous media leads to an additional viscosity term. The effect of this additional viscosity term was investigated numerically. It is found that the additional viscosity term improves  the  velocity  prediction  for  the  case  of  higher  ratio  between  tube  and particle diameter

Synthesis and Activity Test of Cu/ZnO/Al2O3 for the Methanol Steam Reforming as a Fuel Cell's Hydrogen Supplier

The synthesis of hydrogen from hydrocarbons through the steam reforming of methanol on Cu/ZnO/Al2O3 catalyst has been investigated. This process is assigned to be one of the promising alternatives for fuel cell hydrogen process source. Hydrogen synthesis from methanol can be carried out by means of methanol steam reforming which is a gas phase catalytic reaction between methanol and water. In this research, the Cu/ZnO/Al2O3 catalyst prepared by the dry impregnation was used. The specific surface area of catalyst was 194.69 m2/gram.The methanol steam reforming (SRM) reaction was carried out by means of the injection of gas mixture containing methanol and water with 1:1.2 mol ratio and 20-90 mL/minute feed flow rate to a fixed bed reactor loaded by 1 g of catalyst. The reaction temperature was 200-300 °C, and the reactor pressure was 1 atm. Preceding the reaction, catalyst was reduced in the H2/N2 mixture at 160 °C. This study shows that at 300 °C reaction temperature, methanol conversion reached 100% at 28 mL/minute gas flow rate. This conversion decreased significantly with the increase of gas flow rate. Meanwhile, the catalyst prepared for SRM was stable in 36 hours of operation at 260 °C. The catalyst exhibited a good stability although the reaction condition was shifted to a higher gas flow rate

A Review on Zeolite Application for Aromatic Production from Non-Petroleum Carbon-Based Resources

The application of zeolite catalyst has been expanded to support on-purpose sustainable technology. This review focused on zeolite application to produce aromatic compounds from non-petroleum carbon-based resources, including methanol, CO2, CO, and biomass. For COx resources, the two main routes for producing aromatics products are discussed, i.e., the olefinic and the oxygenates-mediated route. Moreover, several improvement strategies for enhancing catalytic performance are also discussed, i.e., the addition of metal components, tuning the metal and zeolite structure, and modifying the reaction process. Finally, prospects for future development are formulated

A Review on Zeolite Application for Aromatic Production from Non-Petroleum Carbon-Based Resources

The application of zeolite catalyst has been expanded to support on-purpose sustainable technology. This review focused on zeolite application to produce aromatic compounds from non-petroleum carbon-based resources, including methanol, CO2, CO, and biomass. For COx resources, the two main routes for producing aromatics products are discussed, i.e., the olefinic and the oxygenates-mediated route. Moreover, several improvement strategies for enhancing catalytic performance are also discussed, i.e., the addition of metal components, tuning the metal and zeolite structure, and modifying the reaction process. Finally, prospects for future development are formulated

Utilizing Shear Factor Model and Adding Viscosity Term in Improving a Two-Dimensional Model of Fluid Flow in Non Uniform Porous Media

In a packed bed catalytic reactor, the fluid flow phenomena are very complicated because the fluid and solid particle interactions dissipate the energy. The governing equations were developed in the forms of specific models. The shear factor model was introduced in the momentum equation for covering the effect of flow and solid interactions in porous media. A two dimensional numerical solution for this kind of flow has been constructed using the finite volume method. The porous media porosity was treated as non-uniform distribution in the radial direction. Experimentally, the axial velocity profiles produce the trend of having global maximum and minimum peaks at distance very close to the wall. This trend is also accurately picked up by the numerical result. A more comprehensive shear factor formulation results a better velocity prediction than other correlations do. Our derivation on the presence of porous media leads to an additional viscosity term. The effect of this additional viscosity term was investigated numerically. It is found that the additional viscosity term improves the velocity prediction for the case of higher ratio between tube and particle diameter

Utilization of Modified Zeolite as Catalyst for Steam Gasification of Palm Kernel Shell

Syngas from biomass gasification is being developed for alternative feedstock in the chemical industry. Palm kernel shell which is generated from palm oil industry can be potentially used as raw material for gasification process. The purpose of this study was to investigate the use of modified natural zeolite catalysts in steam gasification of palm kernel shells. Mordenite type zeolite was modified by acid leaching to be used as a tar cracking catalyst. Steam gasification was conducted at the temperature range of 750–850 °C and the steam to biomass ratio was in the range of 0–2.25. The result showed that steam gasification of palm kernel shell with the addition of zeolite catalyst at 750 °C and steam to biomass ratio 2.25 could reduce tar content up to 98% or became 0.7 g/Nm3. In this study, gasification of palm kernel shells produced syngas with the hydrogen concentration in the range of 52–64% and H2/CO ratio of 2.7–5.7. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Exceptional Aromatic Distribution in the Conversion of Palm-Oil to Biohydrocarbon Using Zeolite-Based Catalyst

A series of four catalysts, i.e. ZSM-5 (Si/Al = 25) (Z1), a combination of ZSM-5 (Si/Al = 25) and zeolite Y (Si/Al = 25) (Z2), zeolite Y (Si/Al = 25) (Z3), and ZSM-5 (Si/Al = 80) (Z4), was successfully prepared for catalytic cracking of palm oil. All three catalysts utilized silica as a binder without other additional components. Catalytic cracking tests showed that the aromatic distribution was very high, according to the following order: Z4 (98%) > Z1 (90%) > Z2 (84%) > Z3 (60%). It was shown that ZSM-5 promotes the formation of aromatics better than zeolite Y does. From 98% of aromatics products in Z1, 71% were benzene, toluene, and xylene (BTX). It appears that the formation of aromatics needs milder acidity since a higher number of acids extends the cracking reaction, resulting in the formation of more gaseous and heavy aromatics products. The results of this study show potential for the sustainable production of bio-hydrocarbons with exceptional aromatic distributions, which may fulfill the demands of the petroleum, petrochemical, and fine chemical sectors