Matteo Morandin

Integration opportunities for substitute natural gas (SNG) production in an industrial process plant

This paper investigates opportunities for integration of a Substitute Natural Gas (SNG) process based on thermal gasification of lignocellulosic biomass in an industrial process plant currently importing natural gas (NG) for further processing to speciality chemicals. The assumed SNG process configuration is similar to that selected for the ongoing Gothenburg Biomass Gasification demonstration project (GoBiGas) and is modelled in Aspen Plus. The heat and power integration potentials are investigated using Pinch Analysis tools. Three cases have been investigated: the steam production potential from the SNG process excess heat, the electricity production potential by maximizing the heat recovery in the SNG process without additional fuel firing, and the electricity production potential with increased steam cycle efficiency and additional fuel firing. The results show that 217 MWLHV of woody biomass are required to substitute the site’s natural gas demand with SNG (162 MWLHV). The results indicate that excess heat from the SNG process has the potential to completely cover the site’s net steam demand (19 MW) or to produce enough electricity to cover the demand of the SNG process (21 MWel). The study also shows that it is possible to fully exploit the heat pockets in the SNG process Grand Composite Curve (GCC) resulting in an increase of the steam cycle electricity output. In this case, there is a potential to cover the site’s net steam demand and to produce 30 MWel with an efficiency of 1 MWel/MWadded heat. However, this configuration requires combustion of 36 MWLHV of additional fuel, resulting in a marginal generation efficiency of 0.80 MWel/MWfuel (i.e. comparing the obtained electricity production potentials with and without additional fuel firing).

Superimposition of Elementary Thermodynamic Cycles and Separation of the Heat Transfer Section in Energy Systems Analysis

In a wide variety of thermal energy systems, the high integration among components derives from the need to correctly exploit all the internal heat sources by a proper matching with the internal heat sinks. According to what has been suggested in previous works to address this problem in a general way, a “basic configuration” can be extracted from the system flowsheet including all components but the heat exchangers, in order to exploit the internal heat integration between hot and cold thermal streams through process integration techniques. It was also shown how the comprehension of the advanced thermodynamic cycles can be strongly facilitated by decomposing the system into elementary thermodynamic cycles which can be analyzed separately. The advantages of the combination of these approaches are summarized in this paper using the steam injected gas turbine (STIG) cycle and its evolution towards more complex system configurations as an example of application. The new concept of “baseline thermal efficiency” is introduced to combine the efficiencies of the elementary cycles making up the overall system, which demonstrates to be a useful reference to quantify the performance improvement deriving from heat integration between elementary cycles within the system.

Integration of a Biomass-to-Hydrogen Process in an Oil Refinery

In this article, the substitution of a fossil fuel-based hydrogen (H2) production unit with a biomass-based process in a large European refinery is studied. Pinch Analysis is performed and several cases are evaluated in terms of energy and CO2 balances. Integration opportunities yield an increase of the energy efficiency from 70 to 79 %. In addition to H2, a maximum of 77 t/h of HP steam or 21.8 MW of electricity can be exported to the refinery. Maximum potential for reduction of CO2 emissions amounts to 758 kt/y and is found when H2 and electricity are coproduced.

Integration of Biomass Gasification-Based Olefins Production in a Steam Cracker Plant—Global GHG Emission Balances

This paper investigates two options for integration of biomass-based olefin production with a fossil-based steam cracker plant at the heart of a chemical cluster. The work was conducted in the form of a case study considering the possible future partial replacement of a fraction of the cracker olefins with approx. 220 kt/y of biomass-based olefins (ethylene, propylene, and butylene) (approx. 25 % of total capacity) produced via gasification, methanol synthesis, and the methanol-to-olefins (MTO) process. Two options were compared with base case operation with fossil-only feedstock: (i) purchase of methanol produced off-site, and (ii) on-site methanol production. In both cases, the MTO section was assumed to be located at the cracker site, making use of existing olefin separation equipment. Consequences of such partial feedstock substitution for the steam, fuel gas, and electric power balances of the cracker plant were investigated. Potentials for generation of steam and electric power were estimated by assuming integration with a heat recovery steam cycle. Greenhouse gas (GHG) emission balances of the proposed options were estimated by applying a system boundary expansion approach. The GHG emission reduction potentials are shown to be between 50 % and 70 %, compared with the base case. The reduction potential depends on the choice of reference grid electricity generation technology but the major contribution comes from the introduction of renewable feedstock.

Application of Process Integration to the Synthesis of Heat and Power Utility Systems Including Combined Heat and Power (CHP) and Industrial Heat Pumps

This chapter discusses the main aspects of application of Pinch Analysis to the analysis and synthesis of heat and power utility systems for industrial processes. The chapter first reviews the basic concepts for the use of the Process Grand Composite Curve as a targeting tool. The chapter then discusses the application of this tool for synthesis and design of utility systems of main relevance in industrial practice, such as centralised heating systems, Combined Heat and Power (CHP) production system and industrial heat pumps.

A Generalized Approach to Handle Heat Exchange Restrictions in Energy Targeting

This paper focuses on the development of a generalized method for describing and handling any type of heat exchange restrictions between subsets of thermal streams when dealing with automatic energy targeting. A graph theory representation of the heat exchange opportunities between stream subsets called heat integration graph is introduced. This graph is used to identify subsystems consisting of one or more stream subsets which can be treated as separate thermal cascades. These correspond to maximal subgraphs that are completely connected components of the heat integration graph, also called “cliques”. The stream subsets belonging to more than one clique, here called “pivot”, are those which thermal streams have to be optimally distributed to two or more cliques. The hot utility target of a system can then be found by solving a linear programming optimization in which the constraints that guarantee a feasible thermal cascade in all the maximal subgraphs are included. The procedure is applied here to a numerical example of a sugarcane mill in which some heat exchange restrictions are considered between process units.

A cost targeting method for studying investment on heat exchanger network for collection of industrial excess heat

This paper discusses the design of water based heat collection system for recovery of industrial excess heat. The focus in on the problem of finding the optimal combinations of excess heat sources minimizing heat exchanger network capital costs for different amounts of total recovered heat. A cost targeting approach based on vertical heat transfer between hot process streams and the heat collection medium in Pinch Analysis diagrams is used. The set of process streams where heat shall be recovered is found by solving an optimization problem where heat recovery is maximized while minimizing the capital costs simultaneously. A genetic algorithm based optimization tool is used. The analysis is conducted for three plants belonging to a chemical cluster. The results are compared with results from previous investigations in which the process excess heat sources were chosen based on their incremental heat contribution. The new approach presented in this work allows identifying a much larger set of solutions as well as considerably lower capital costs for similar amount of recovered heat in cases when process streams largely differ in terms of temperature levels and heat transfer properties.