Renewable hybrid polygeneration system from various unconventional feedstock

Abstract

The production of low-carbon energy products from biomass gasification is encouraged, in order to expand our sources of energy and to mitigate the harmful impact of the pollutants on the climate and the environment. The benefits of a renewable hybrid polygeneration system that uses various types of unconventional feedstock in the energy mix are extraordinary. However, the location, logistics issues, availability and meteorological conditions of a plant can play a crucial role in order to investigate the full potential of these unconventional resources. In this study, the systematic issues regarding hybridization of CSP (concentrated solar power) with biomass gasification without energy storage to produce energy, liquid fuel and other chemicals is considered as an alternative process. The main goal was to develop a design guideline and recommendations for utilizing the CSP thermal energy as a heat source for the gasification process. This study also explored the role of CSP in the gasification process to balance the heat load requirement. The overall study was carried out by investigating various cases for the biomass gasification process with CSP and without CSP with target analysis via process synthesis and attainable region principles and the development of a simple simulation model using Aspen Plus®. The results were validated by comparing with already-available experimental data for biomass gasification in the literature. Systematic issues relating to the renewable hybrid polygeneration system were evaluated by conducting various case studies using target analysis and process simulation. From a material balance point of view, producing a specific molar ratio of hydrogen (H2) and carbon monoxide (CO) can be achieved by varying the steam to biomass ratio and the CSP heat injection. The target analysis of various types of biomass to dimethyl ether shows that co feeding biomass with methane can improve the performance of the process significantly, in terms of material, energy and work balance. The case study to produce ethanol from biomass then ethanol reforming to produce hydrogen, proves that 100% hydrogen efficiency can be achieved. However, the process releases a significant amount of energy and work potential, which might not be recovered economically, especially with small scale applications. Co feeding of water in ethanol reforming to produce more H2 is applied to recover this extra energy. If a low-cost heat source is available, such as solar heat or waste heat from other processes, then maximum of 187% selectivity of H2 based on ethanol can be achieved. The case study on solid waste to hydrogen shows that H2 production efficiency with CSP is about 12.5 kmol/MWth when using pinewood sawdust as a feedstock and 13.2 kmol/MWth in the case of municipal solid waste. Adding CSP to the system can boost H2 production to 50% - 146 g/kg when using wet pinewood sawdust (PW) as a feedstock, and 61% - 224 g/kg when using MSW. A case study of the biomass gasification using various gasifying agents to produce methane (CH4) rich syngas to be used in a normal gas turbine. The set target for this case study was 40% CH4 mole concentration. This case study proves that this target can be achieved by utilizing the heat generated from methanation to the gasifier. Applying CSP to the gasification process will also help to boost the CH4 produced after methanation by about 20%. The case study on solar energy to H2 concluded that with CSP, for steam gasification case, it is 117 g/kg of wet biomass and for CO2-gasification, it is 119 g/kg of wet biomass. For both cases, H2 production efficiency is 14-15 kmol per MWth. This case study provides a parametric analysis to transform biomass, solar and CO2 into valuable and carbon-neutral alternative fuels. The case study on the biomass integrated gasification combined cycle (IGCC) shows a higher net electricity output per unit of crop residue feed with solar-assisted IGCC and that it achieves a net thermal efficiency of about 53%. The investigation of a hybrid process proves that 0.55 MW of electricity can be produced per unit of solar-thermal energy input to the gasifier; having solar to electricity efficiency of approximately 55%. The case study on the hybrid CSP CO2-IGCC process shows that the peak net efficiency is 46%, which is slightly higher than seen with the steam-IGCC process (45%). A solar thermal to power efficiency rate of 55% is achieved in CSP CO2-IGCC process, which is less than seen with CSP steam-IGCC process (58%). Case study for sCO2 Brayton cycle of a CSP-assisted biomass gasification process shows that the net thermal efficiency of about 60% is attainable, which is better than any existing biomass based IGCC process. Further, it is shown that the performance of the system is superior to that of indirectly heated sCO2 without solar aid. The injected solar power boosts the power output as high as 52% and its conversion efficiency is about the same value. The peak net efficiency of the hybrid process is 45% and a solar to power efficiency is 58%. In terms of the liquid fuel production option, 17-18 kg of liquid fuel can be produced per GJ of solar energy injected into the process. In conclusion, the outcomes from case studies by target analysis and simulation model are promising. The case studies show that the renewable hybrid polygeneration system is an attractive option to convert renewables resources (biomass and solar) into clean power, liquid fuel, green H2 fuel, chemicals, etc. We concluded that the incorporation of CSP-thermal energy into the biomass gasification process with the concept of polygeneration process will provide us opportunities to explore the maximum potential of unconventional feedstock.

Kukhuthazwa ukukhiqizwa kwemikhiqizo yamandla kagesi aphansi avela biomass gasification, ukuze sandise imithombo yethu yamandla futhi sinciphise umthelela olimazayo wokungcolisa isimo sezulu kanye nemvelo. Izinzuzo zohlelo hybrid polygeneration oluvuselelekayo olusebenzisa izinhlobo ezahlukahlukene zokuphakelayo okungahambelani nokuxubana kwamandla zixakile. Kodwa-ke, indawo, izingqinamba zezinto ezisetshenziswayo, ukutholakala nezimo zezulu zesitshalo kungadlala indima ebaluleke kakhulu ukuphenya amandla aphelele alezi zinsizakusebenza ezingavumelani. Kulolu cwaningo, izingqinamba ezihlelekile maqondana nokuhlanganiswa CSP (amandla elanga agxiliwe) biomass gasification ngaphandle kokugcina amandla ukukhiqiza amandla, uphethiloli wamanzi namanye amakhemikhali kubhekwa njengenye inqubo. Inhloso enkulu bekuwukwakha umhlahlandlela wokuklanywa nezincomo zokusebenzisa amandla CSP afudumele njengomthombo wokushisa wenqubo yokwenza igesi. Lolu cwaningo luphinde lwahlola iqhaza CSP enqubeni gasification ukulinganisela imfuneko yokushisa. Ucwaningo lonke lwenziwa ngokuphenya amacala ahlukahlukene enqubo biomass gasification CSP futhi ngaphandle CSP ngokuhlaziywa okuqondiwe ngenqubo yokuhlanganiswa kanye nemithetho yesifunda efinyelelekayo kanye nokwakhiwa kwemodeli elula yokulingisa kusetshenziswa Aspen Plus®. Imiphumela iqinisekiswe ngokuqhathanisa nedatha yokuhlola esivele ikhona biomass gasification ezincwadini. Izingqinamba ezihlelekile eziphathelene nohlelo lwe-hybrid polygeneration oluvuselelekayo zahlolwa ngokwenza izifundo ezahlukahlukene zamacala kusetshenziswa ukuhlaziywa kokuqondiwe nenqubo yokulingisa. Ngokombono webhalansi yezinto ezibonakalayo, ukukhiqiza isilinganiso esithile molar hydrogen (H2) carbon monoxide (CO) kungatholakala ngokushintsha umusi ube biomass ratio kanye nomjovo wokushisa CSP. Ukuhlaziywa okuhlosiwe kwezinhlobo ezahlukahlukene biomass kuya dimethyl ether kukhombisa ukuthi ukondla biomass methane kungathuthukisa ukusebenza kwenqubo kakhulu, ngokuya ngempahla, amandla kanye nomsebenzi olinganiselayo. Ucwaningo olwenziwe ukukhiqiza ethanol kusuka biomass bese kuguqulwa ethanol ukukhiqiza hydrogen, kufakazela ukuthi ukusebenza kahle hydrogen ngo-100% kungatholakala. Kodwa-ke, le nqubo ikhipha inani elikhulu lamandla nomsebenzi, okungenzeka kungatholakali ngokomnotho, ikakhulukazi ngezicelo ezincane. Ukondliwa kwamanzi ngokubambisana ekuguqulweni ethanol ukukhiqiza H2 eyengeziwe kuyasetshenziswa ukuthola amandla lawa angeziwe. Uma kutholakala umthombo wokushisa ontengo ephansi, njengokushisa kwelanga noma ukushisa kwemfucumfucu kusuka kwezinye izinqubo, khona-ke ukukhethwa okungu-187% H2 okususelwa ethanol kungatholakala. Ucwaningo olwenziwe ngodoti oqinile hydrogen lukhombisa ukuthi ukusebenza kahle kokukhiqizwa H2 CSP cishe kungu-12.5 kmol / MWth uma usebenzisa pinewood sawdust njenge-feedstock 13.2 kmol / MWth uma kungudoti oqinile kamasipala. Ukungeza CSP ohlelweni kungakhuphula ukukhiqizwa H2 kuye ku-50% - 146 g / kg uma usebenzisa pinewood sawdust (PW) emanzi njenge-feedstock, 61% - 224 g / kg uma usebenzisa MSW. Ucwaningo lwamacala biomass gasification kusetshenziswa ama-ejenti ahlukahlukene e-gasifying ukukhiqiza syngas acebile methane (CH4) azosetshenziswa turbine ejwayelekile yegesi. Umgomo obekiwe walolu cwaningo 40% CH4 yokuhlushwa kwemvukuzane. Lolu cwaningo lwamacala lufakazela ukuthi le nhloso ingafinyelelwa ngokusebenzisa ukushisa okwenziwe kusuka ku-methanation kuye ku-gasifier. Ukufaka CSP kunqubo gasification kuzosiza ukukhulisa CH4 ekhiqizwa ngemuva kwe-methanation cishe ngama-20%. Ucwaningo olwenziwe ngamandla elanga eya H2 luphethe ngokuthi CSP, ngecala steam gasification, 117 g / kg ye-biomass emanzi CO2-gasification, 119 g / kg biomass emanzi. Kuwo womabili amacala, ukusebenza kahle kokukhiqizwa H2 kungu-14-15 kmol MWth ngayinye. Lolu cwaningo lwamacala luhlinzeka ngokuhlaziywa kwe-parametric ukuguqula biomass, solar CO2 ibe ngamafutha asemqoka futhi angathathi hlangothi ekhabhoni. Ucwaningo olwenziwe kumjikelezo ohlangene biomass gasification ohlangene (IGCC) lukhombisa ukukhishwa okuphezulu kukagesi ngamayunithi kokuphakelayo kwezinsalela zezitshalo IGCC esizwa ngelanga nokuthi ifinyelela ukusebenza kahle kwenani lokushisa okungaba ngama-53%. Ukuphenywa kwenqubo hybrid kufakazela ukuthi 0.55 MW kagesi ungakhiqizwa ngeyunithi ngayinye yokufakwa kwamandla kagesi welanga gasifier; ukuba nelanga kugesi osebenza kahle cishe 55%. Ucwaningo lwamacala ngenqubo ye-hybrid CSP CO2-IGCC ikhombisa ukuthi ukusebenza kahle kwenetha okungu-46%, okuthe ukuphakama kancane kunokubonwa ngenqubo steam-IGCC (45%). Izinga elishisayo lokushisa ngamandla elisebenza ngamandla 55% liyatholwa kwinqubo CSP CO2-IGCC, engaphansi kokubonwa ngenqubo CSP steam-IGCC (58%). Ucwaningo olwenziwe ngomjikelezo sCO2 Brayton wenqubo biomass gasification esizwa CSP ikhombisa ukuthi ukusebenza kahle kwe-thermal okungaba 60% kuyatholakala, okungcono kunanoma iyiphi inqubo ekhona biomass based IGCC. Ngaphezu kwalokho, kukhonjiswa ukuthi ukusebenza kohlelo kuphakeme kunalokho sCO2 okungaqondile okungaqondile ngaphandle kosizo lwelanga. Amandla elanga ajikiwe akhuphula amandla kagesi afinyelela 52% futhi ukusebenza kwawo ngokuguqulwa kucishe kube nenani elifanayo. Ukusebenza kahle kwenetha kwenqubo hybrid kungama-45% kanti amandla elanga asebenza kahle ngamandla 58%. Ngokuya ngenketho yokukhiqiza uphethiloli ongamanzi, 17-18 kg kaphethiloli ongamanzi ingakhiqizwa GJ ngayinye yamandla elanga afakiwe kule nqubo. Ekuphetheni, imiphumela evela ocwaningweni lwamacala ngokuhlaziywa kokuhlosiwe nemodeli yokulingisa iyathembisa. Ucwaningo lwamacala lukhombisa ukuthi uhlelo oluvuselelekayo hybrid polygeneration luyindlela ekhangayo yokuguqula izinsizakusebenza ezivuselelekayo (biomass nelanga) zibe ngamandla ahlanzekile, uphethiloli oketshezi, uphethiloli oluhlaza H2, amakhemikhali, njll. Siphethe ngokuthi ukufakwa kwamandla CSP thermal Inqubo biomass gasification ngomqondo wenqubo yokuzalwa kabusha izosinikeza amathuba okuhlola amandla amakhulu feedstock engajwayelekile.