Self-sustainable bio-methanol & bio-char coproduction from 2nd generation biomass gasification

Methanol is an important intermediate in the synthesis of different chemicals. It is mainly produced by reforming of natural gas in centralized facilities with productive capacities on the order of 109 tons per day. Production of methanol from biomass suffers from the cost and logistics of the transportation of biomass and it has not yet maturated into commercial scale. The techno-economic feasibility of the co-production of bio-methanol and bio-char is assessed through detailed computer simulations using process simulator Aspen HYSYS® together with the gasification simulator GASDS. This work further elaborates the previous results on the bio-methanol production process, presenting particularities and updates on previously reported values. The production model is seen to be valid, with payback times that go from 3 to 6 years according to the capacity of the plant (100 to 1000 kt of biomass per year). Self-sustainability is possible but a 50/50 mix of producing and buying electricity yields the most economic choice. © Copyright 2017, AIDIC Servizi S.r.l

Fuzzy adaptive control system of a non-stationary plant with closed-loop passive identifier

Abstract Typically chemical processes have significant nonlinear dynamics, but despite this, industry is conventionally still using PID-based regulatory control systems. Moreover, process units are interconnected, in terms of inlet and outlet material/energy flows, to other neighboring units, thus their dynamic behavior is strongly influenced by these connections and, as a consequence, conventional control systems performance often proves to be poor. This paper proposes a hybrid fuzzy PID control logic, whose tuning parameters are provided in real time. The fuzzy controller tuning is made on the basis of Mamdani controller, also exploiting the results coming from an identification procedure that is carried on when an unmeasured step disturbance of any shape affects the process behavior. In addition, this paper compares a fuzzy logic based PID with PID regulators whose tuning is performed by standard and well-known methods. In some cases the proposed tuning methodology ensures a control performance that is comparable to that guaranteed by simpler and more common tuning methods. However, in case of dynamic changes in the parameters of the controlled system, conventionally tuned PID controllers do not show to be robust enough, thus suggesting that fuzzy logic based PIDs are definitively more reliable and effective

H2S in geothermal power plants: from waste to additional resource for energy and environment

Geothermal energy is a sustainable and clean energy source. Unfortunately, utilization of high-enthalpy geothermal systems is generally associated with emissions of gases like carbon dioxide (CO2), hydrogen sulfide (H2S), hydrogen (H2), nitrogen (N2), methane (CH4), and argon (Ar). The emission of some of these gases, particularly CO2, H2S and H2, is one of the main environmental concerns associated with the use of geothermal energy. The sequestration of these gases and their geological storage is the most diffuse viable option for reducing emissions. However, there is interesting technology, called AG2STM, that allows to convert H2S and CO2 into syngas. In this work, the match of this technology with geothermal power plant is analyzed as a new potential industrial route. The study is based on two different geothermal power plants located in Hellisheiði and Nesjavellirn (Iceland) that globally emit 61,800 t of CO2 and 28,200 t/y of H2S. The simulations provide some interesting results: (I) the total conversion of H2S that avoids its underground re-injection with the related environmental problem, (II) the reduction of CO2 emissions (about 8 %) and (III) the increasing of the global thermal energy produced with the same amount initial geothermal energy. The latter is due to the possibility to burn extra hydrogen coming from the AG2STM process. Finally, other advantages of this match are the production of an extra medium pressure steam and the possible reuse of the amount of H2 related to the geothermal plants emissions. Copyright © 2018, AIDIC Servizi S.r.l