731 research outputs found
First Prize "Zdenek Burianec Memorial"
No full textPrimo premio "Zdenek Burianec Memorial Award" presso "the 10th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction" con l'attività di ricerca: "Flavio Manenti, Model Based Projective Monitoring of Process Unit Performances under Uncertainties, Chemical Engineering Transactions"
Buzzi-Ferraris and Manenti Talk About Their New Book
No full textMedia Interview at ChemistryViews.
Wiley-VCH Verlag GmbH & Co. KGa
Considerations on nonlinear model predictive control techniques
No full textThe nonlinear model predictive control (NMPC) is an on-line application based on nonlinear convolution models. It is an appealing control methodology, but it is difficult to implement and its solution is not so performing since it unavoidably means to solve a usually large-scale, constrained, and multidimensional optimization. To increase the difficulty, this optimization problem is subject to computationally heavy differential and algebraic constraints constituting the same convolution model and the least squares nature of the objective function easily leads to narrow valleys and multimodality issues.Beyond a short review of the state-of-the-art, the paper is aimed at highlighting the possibility to exploit at best the intrinsic features of the specific system one is going to control using the NMPC. The idea is to give the NMPC the possibility to automatically select the best combination of algorithms (differential solvers and optimizers) in accordance with the specific problem to be solved. From this perspective, the NMPC could be easily extended to many scientific fields traditionally far from process systems and computer-aided process engineering and the user has not to worry about which specific differential solvers and optimizers are needed to solve his/her problem. © 2011 Elsevier Ltd
Natural gas operations: Considerations on process transients, design, and control
No full textThis manuscript highlights tangible benefits deriving from the dynamic simulation and control of operational transients of natural gas processing plants. Relevant improvements in safety, controllability, operability, and flexibility are obtained not only within the traditional applications, i.e. plant start-up and shutdown, but also in certain fields apparently time-independent such as the feasibility studies of gas processing plant layout and the process design of processes. Specifically, this paper enhances the myopic steady-state approach and its main shortcomings with respect to the more detailed studies that take into consideration the non-steady state behaviors. A portion of a gas processing facility is considered as case study. Process transients, design, and control solutions apparently more appealing from a steady-state approach are compared to the corresponding dynamic simulation solutions
DOUBLE-ZONE SHELL AND TUBE EQUIPMENT, RELATED PLANT CONTAINING SAID EQUIPMENT AND PROCESS FOR PRODUCING A CHEMICAL IN SAID PLANT
No full textEquipment (1A) comprising: a first and a second tube plate (6 7) a tube bundle (2) comprising exchanger tubes (8) a shell (3) provided with at least a first at least a second and at least a third shell-side connection (13 14 15) for feeding and removing said shell-side fluid a first distributor (4) connected to said first tube plate (6) a second distributor (5) connected to said second tube plate (7) a partition wall (58) on the shell side configured to divide said shell (2) into a first and a second zone (18 19) said partition wall (58) defining a perimeter duct (21) having a first and a second opening (23 24) configured to put in fluid communication said first and said second zone (18 19) through said perimeter duct (21); first and second diaphragms (27 28) installed in said first and second zones (18 19) respectively adapted to support said heat exchanger tubes (8) and/or to perform deviations of the flow of said shell-side fluid in order to increase the heat exchange said perimeter duct (21) essentially annular in shape surrounding the portion of said tube bundle passing through said second zone (19) so that said first (13) and third shell-side connections (15) are respectively directly connected to the first zone (18) and to the second zone (19) and said second shell-side connection (14) is directly connected to the perimeter duct (21)
Start-up operations of MED desalination plants
No full textThis paper is related to the previous work (Manenti et al., “Parametric Simulation and Economic Assessment of Heat Integrated Geothermal Desalination Plant”, Desalination, 317, 193–205, 2013) and extends the steadystate simulation and process layout optimization by investigating the procedure to start up multi-effect distillation (MED) desalination plants. The operations involved in the startup procedure, such as seawater supply, energy supply and vacuum generation along the process are considered together with the status of controls to prevent any possible overlapping of these relevant aspects. Segregation of the operations is demonstrated to be essential to prevent any redundancy in the oscillatory behavior of process units that can easily lead to dangerous instabilities of the plant. Moreover, whenever geothermal sources are used for sustainable production of desalinated water, it is fundamental to account for some peculiarities such as certain limitations in controllability and operability of the geothermal source. General guidelines to start up desalination processes are provided; special attention is given to geothermal-supplied plants
Transient Operations in Acid Gas Injection Units
No full textProcess industries might have different reasons for analyzing operational transients and, jointly, carrying out process operator training simulators. For instance, unsteady events can easily lead to upset operating conditions such as vibrations, pressure loads, high local fluid velocity and mechanical erosion, which jeopardize safety and equipment reliability. Also, process performances can be compromised during transients as operating conditions can depart from optimal ones.
On this subject, the paper analyzes and models in depth an acid gas injection unit involving a series of centrifugal compressors. A detailed dynamic simulation is developed to enhance the comprehension of rotating units throughout the process transients. Moreover, an appropriate plant-wide control scheme is proposed in order to rapidly dampen the surge conditions due to the process transients
Processo per operare su un fluido di lavoro secondo un ciclo termodinamico frigorifero
No full textProcesso per operare su un fluido di lavoro secondo un ciclo termodinamico frigorifero
comprendente le fasi cicliche di:
5 a) evaporare un fluido di lavoro allo stato liquido in una unità di evaporazione (10)
generando un flusso di vapore; il fluido di lavoro presentando condizioni iniziali di
temperatura e pressione;
b) comprimere almeno una porzione del flusso di vapore proveniente dalla fase a)
in una unità di compressione (20) aumentando temperatura e pressione del flusso di vapore;
10 c) condensare cedendo calore verso un ambiente esterno almeno una porzione del
fluido di vapore compresso proveniente dalla fase b) mediante una unità di condensazione
(30) generando un flusso di condensato;
d) laminare almeno una porzione del flusso di condensato proveniente dalla fase c)
mediante una unità di laminazione (40) abbassando temperatura e pressione del flusso di
15 condensato per ottenere il fluido di lavoro sostanzialmente alle condizioni iniziali di
temperatura e pressione;
e) inviare il fluido di lavoro proveniente dalla fase d) alla fase a);
la fase a) prevede surriscaldare il flusso di vapore mediante dissoluzione di almeno un
soluto non volatile nel fluido di lavoro e riscaldamento della soluzione ottenuta fino a
20 raggiungimento della temperatura di ebollizione della soluzione e conseguente produzione
di vapore surriscaldato essenzialmente costituito dal fluido di lavoro, detta soluzione
presentando una temperatura di ebollizione superiore alla temperatura di ebollizione del
fluido di lavoro
Process for operating a working fluid according to a steam thermodynamic cycle to produce work
No full textIn order to overcome the aforementioned problems, a process and related system
3
was devised to operate a working fluid producing superheated vapour without the use of
additional critical units or intermediate phases to reduce the apparatus footprint and
improve process efficiency.
5 Thus, the subject matter of the present invention is a process for operating a working
fluid according to a steam thermodynamic cycle to produce work comprising the cyclic
steps of:
a) compressing a working fluid by means of a pumping unit (10) increasing
temperature and pressure of the working fluid, the working fluid having initial temperature
10 and pressure conditions;
b) heating the compressed working fluid by means of a first heating unit (20);
c) evaporating the working fluid at the heated and compressed liquid state in an
evaporation unit (30) generating a steam flow;
d) expanding the steam flow from step c) in an expansion unit (40);
15 e) condensing at least a portion of the expanded steam fluid from step d) by means
of a condensation unit (50) to obtain the working fluid substantially at the initial
temperature and pressure conditions;
f) sending the working fluid from step e) to step a);
characterised in that step c) provides for superheating the steam flow by at least partially
20 dissolving at least one non-volatile solute in the working fluid and heating the solution
obtained until the boiling temperature of the solution is reached and consequent production
of superheated steam essentially consisting of the working fluid.
Advantageously, the process and system of the present invention make it possible
25 to improve the efficiency of heat exchange in the cycle and to reduce the total volume of
4
the system for the same power compared to the prior art.
Advantageously, the process and system of the present invention allow for
improved efficiencies compared to Rankine cycles with superheated steam.
Advantageously, the process and system of the present invention for the respective
5 system on which the process is implemented also allow a:
• Reduction in investment costs
• Reduction in operating costs
• Reduction in maintenance costs
• Reduction in monitoring and control cost
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