Anders Åsblad

Potential for greenhouse gas reduction in industry through increased heat recovery and/or integration of combined heat and power

The potential for greenhouse gas (GHG) reduction in industry through process integration measures depends to a great extent on prevailing technical and economic conditions. A step-wise methodology developed at the authors department based on pinch technology was used to analyse how various parameters influence the cost-optimal configuration for the plants energy system, and the opportunities for costeffective GHG emissions reduction compared to this solution. The potential for reduction of GHG emissions from a given plant depends primarily on the design of the industrial process and its energy system (internal factors) and on the electricity-to-fuel price ratio and the specific GHG emissions from the national power generation system (external factors).

Surface evaporation of turbulent falling films

Abstract In refrigeration and heat pump applications, falling film evaporators should be very attractive due to high heat transfer coefficients with negligible pressure drop. In this paper results from an experimental study with refrigerant R12 are reported. The results are compared with existing correlations in the literature and the need for a new correlation is recognized. The following equation is derived with data from three different sources (including the present study and the study of Chun and Seban): Nu = 0,012 Re0.28Pr0.53. The equation has been validated with data from three additional studies.

A new methodology for greenhouse gas reduction in industry through improved heat exchanging and/or integration of combined heat and power

This paper presents a method that identi®es economically optimal combinations of enhanced heat recovery, integration of combined heat and power (CHP), and fuel switching, in an existing industrial energy system at various emission levels. Novel types of composite curves based on pinch technology, representing the existing temperature levels for supplying heat and the possible ones that may be attained after retro®tting, are used as tools for estimating the opportunities for CHP and the trade-off between improved heat exchangin

Influence of Different Pretreatment Methods on Biomass Gasification and Production of Fischer-Tropsch Crude Integrated with a Pulp and Paper Mill

In this paper, the influence on the system performance of different biomass pretreatment methods before gasification and subsequent production of Fischer-Tropsch crude is considered. Entrained flow gasification at high pressure is a well proven technology for coal as feedstock with the benefit of producing a practically tar free raw gas with a close to complete carbon conversion. The short residence time in this type of gasifier requires a fuel, which is relatively dry and has a small particle size, to be pressurized from ambient conditions up to 20-50 bar. The small particle size can be acquired by grinding but this is highly energy intensive and feeding is challenging. Torrefaction is a thermal pretreatment method carried out at around 300 °C which makes the biomass easier to grind, thus requiring less electricity, and makes the material less fibrous, while on the other hand requiring heat for the process. Pyrolysis is a process carried out at around 500 °C which lets the biomass decompose into a gaseous, a liquid and a solid part. The solid part can be grinded and fed into the gasifier together with the liquid and gaseous phases. This will further facilitate the feeding but with a further increased heat demand compared to torrefaction. The different pretreatment methods and their impact on the overall biorefinery energy system have been studied and evaluated using process integration methodology. The results show that the excess heat from an FT process with a biomass input of 300 MW(HHV) can replace the solid fuel boiler in a large chemical pulp and paper mill. With the preconditions given for this study, thermal pretreatment of the biomass can be beneficial in terms of system thermal efficiency.

Comparison between a detailed pinch analysis and the 'Heat Load Model for Pulp and Paper' - Case study for a Swedish thermo-mechanical pulp and paper mill

Pinch analysis has been used for several decades as a tool for making industrial processes more energy efficient by identifying process integration opportunities. Hakala et al. (2008) recognise that pinch analysis is a powerful tool when it comes to improving energy efficiency in mechanical pulp and paper mills, however often very time consuming due to the extensive need for input data. The heat load model for pulp and paper (HLMPP) tool was developed at Aalto University in Finland as a means of providing a flexible tool for a first quick scan of process integration potential. The intention of this study is to evaluate if the model can accurately estimate the data necessary for performing a pinch analysis for a Swedish thermo-mechanical pulp (TMP) and paper mill. Jonsson et al. (2010) used the HLMPP tool to evaluate the potential for steam savings for four Scandinavian TMP mills. It was found that the minimum steam demands were 2-20 % lower than the current consumptions in the mills. In this study, a detailed pinch analysis was carried out for one of the studied mills described by Jonsson (the mill with the lowest energy savings potential according to the HLMPP screening) to identify strengths and shortcomings of the HLMPP tool. An initial comparison shows that the pinch temperature and demand for hot and cold utility predicted by the HLMPP tool, as presented by Jonsson, differs from the detailed pinch analysis. However, further investigation showed that the HLMPP results can be aligned to the detailed data with good accuracy if more time and knowledge about the process is put in to the model.