Markku Hurme

Safety considerations in process synthesis

The aim of this work is to extend the computerized method for process pre-design to encompass safety aspects. Emphasis is on the choice between different process concepts. The synthesis method is integrated into an existing computer aided process design tool. The method is based on six databanks which contain hazardous properties of chemical compounds and knowledge of safe and unsafe process concepts. The first stage of the method is a rule-based synthesis where safety rules are combined with process rules. The second step includes a safety analysis of synthetized alternatives which is done by calculating safety indices based on the safety properties of chemicals processed and the structure and conditions of the process.

The effect of initial drop size on particle size in the supercritical antisolvent precipitation (SAS) technique

The objective of this study was to find the effect of the initial droplet size on the final particle size in the semi-continuous SAS technique. In this technique the solute of interest is first dissolved in a conventional solvent. Particle formation is accomplished by spraying this solution continuously through a nozzle into a chamber containing subcritical or supercritical carbon dioxide. The droplet sizes were calculated from four alternative equations. The theoretical particle sizes were calculated from the calculated droplet sizes assuming that one agglomerated microparticle is produced from each droplet. The theoretical mean particle sizes and the measured particle sizes were compared. The particle formation model was tested with poly(l-lactid acid) (l-PLA) in dichloromethane (DCM) and carbon dioxide. The smallest l-PLA particles were formed by spraying l-PLA/DCM solution into liquid CO2 below 304 K and 8.0 MPa. Under these conditions, the mean agglomerate particle diameter was less than 4 μm. When spraying the solution into supercritical CO2 at 308–323 K and 10–14 MPa, the mean particle size was 8–14 μm. Higher temperatures and pressures increased the mean particle size. The particles were strongly agglomerated at the highest temperature and pressure (333 K and 17 MPa). Recrystallization of l-PLA into small particles is possible below 308 K and 10 MPa using the SAS technique. According to the droplet formation models, the effects of temperature, pressure, CO2 velocity and density, nozzle diameter, interfacial tension between liquid and CO2, and Reynolds and Weber numbers on the droplet size is small. The calculated theoretical particle size agreed reasonably well with the final particle size at the near critical temperature and pressure of CO2. However, the droplet and particle formation models did not explain the observed changes of particle sizes with changes in operating conditions. It is suggested that the initial droplet sizes, formed at the nozzle, do not have an effect on the final particle size.

Synthesis of separation processes by case-based reasoning

A new approach to separation process synthesis and selection of single separations is presented. The method is based on the reuse of existing design cases by case-based reasoning (CBR). CBR is a method for finding the most similar existing separation designs and for applying the knowledge of their concept to solve new problems. The method has previously been applied for selecting single separations and simple sequences but has now been extended to cover synthesis of more complicated systems. The method is mainly intended to screening feasible process alternatives in preliminary process design for more detailed study by simulation.

Mass, energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste.

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442 and EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream.

Economic comparison of diagnostic antibody production in perfusion stirred tank and in hollow fiber bioreactor processes

The total operating costs of small‐scale monoclonal antibody production were calculated for two different upstream options and general downstream procedure based on protein A chromatography. The upstream options were a spin‐filter equipped stirred‐tank bioreactor (STR) and a hollow fiber bioreactor (HFB). Both the bioreactors were operated in perfusion mode. The total operating costs of the processes were 6,900 €/g for STR option and 6,400 €/g for the HFB option. In the both systems, the costs were dominated by expenses derived from the downstream section (almost 80%) that was almost identical in the both systems. In the upstream section, the investment depreciation was the largest cost item. The lower total costs of the HFB option were a result of lower investment costs and more concentrated product that led into savings also in downstream section. This study brings out the HFB as on viable alternative for stirred‐tank bioreactor, especially in small‐scale diagnostic monoclonal antibody production.

Mass, energy and material balances of SRF production process. Part 3: Solid recovered fuel produced from municipal solid waste

This is the third and final part of the three-part article written to describe the mass, energy and material balances of the solid recovered fuel production process produced from various types of waste streams through mechanical treatment. This article focused the production of solid recovered fuel from municipal solid waste. The stream of municipal solid waste used here as an input waste material to produce solid recovered fuel is energy waste collected from households of municipality. This article presents the mass, energy and material balances of the solid recovered fuel production process. These balances are based on the proximate as well as the ultimate analysis and the composition determination of various streams of material produced in a solid recovered fuel production plant. All the process streams are sampled and treated according to CEN standard methods for solid recovered fuel. The results of the mass balance of the solid recovered fuel production process showed that 72% of the input waste material was recovered in the form of solid recovered fuel; 2.6% as ferrous metal, 0.4% as non-ferrous metal, 11% was sorted as rejects material, 12% as fine faction and 2% as heavy fraction. The energy balance of the solid recovered fuel production process showed that 86% of the total input energy content of input waste material was recovered in the form of solid recovered fuel. The remaining percentage (14%) of the input energy was split into the streams of reject material, fine fraction and heavy fraction. The material balances of this process showed that mass fraction of paper and cardboard, plastic (soft) and wood recovered in the solid recovered fuel stream was 88%, 85% and 90%, respectively, of their input mass. A high mass fraction of rubber material, plastic (PVC-plastic) and inert (stone/rock and glass particles) was found in the reject material stream.

Mass, energy and material balances of SRF production process. Part 2: SRF produced from construction and demolition waste.

In this work, the fraction of construction and demolition waste (C&D waste) complicated and economically not feasible to sort out for recycling purposes is used to produce solid recovered fuel (SRF) through mechanical treatment (MT). The paper presents the mass, energy and material balances of this SRF production process. All the process streams (input and output) produced in MT waste sorting plant to produce SRF from C&D waste are sampled and treated according to CEN standard methods for SRF. Proximate and ultimate analysis of these streams is performed and their composition is determined. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. By mass balance means the overall mass flow of input waste material stream in the various output streams and material balances mean the mass flow of components of input waste material stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. The results from mass balance of SRF production process showed that of the total input C&D waste material to MT waste sorting plant, 44% was recovered in the form of SRF, 5% as ferrous metal, 1% as non-ferrous metal, and 28% was sorted out as fine fraction, 18% as reject material and 4% as heavy fraction. The energy balance of this SRF production process showed that of the total input energy content of C&D waste material to MT waste sorting plant, 74% was recovered in the form of SRF, 16% belonged to the reject material and rest 10% belonged to the streams of fine fraction and heavy fraction. From the material balances of this process, mass fractions of plastic (soft), paper and cardboard, wood and plastic (hard) recovered in the SRF stream were 84%, 82%, 72% and 68% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC) and rubber material was found in the reject material stream. Streams of heavy fraction and fine fraction mainly contained non-combustible material (such as stone/rock, sand particles and gypsum material).

Computer aided design of occupationally healthier processes

Abstract Computer alded approaches for assessing inherent occupational health hazards and ranking process concepts based on their health properties were developed for the first stages of a process lifecycle; the process development, preliminary design, and basic engineering steps. The methods are tailored to the process design lifecycle steps in terms of their principle and information requirement. The methods can be integrated with existing computer aided design tools as described. A case study is given to illustrate the approach.

Technical Analysis of Accident in Chemical Process Industry and Lessons Learnt

A study of past accidents in the chemical process industry (CPI) has been carried out. It is found that the majority (73%) of the accidents were caused by technical and engineering failures. Based on the causes of accident and types of equipment failures, five common features of accident in the CPI were identified. The analysis reveals that the contribution of the design to accidents is significant and the advancement of knowledge/technology is not shared effectively by practitioners. Dependency on the add-on control strategy should be reduced and inherently safer or passive engineered must be considered as premier risk reduction strategy to lessen the safety load, for better design and to prevent accident effectively.

Performance of biofuel processes utilising separate lignin and carbohydrate processing.

Novel biofuel pathways with increased product yields are evaluated against conventional lignocellulosic biofuel production processes: methanol or methane production via gasification and ethanol production via steam-explosion pre-treatment. The novel processes studied are ethanol production combined with methanol production by gasification, hydrocarbon fuel production with additional hydrogen produced from lignin residue gasification, methanol or methane synthesis using synthesis gas from lignin residue gasification and additional hydrogen obtained by aqueous phase reforming in synthesis gas production. The material and energy balances of the processes were calculated by Aspen flow sheet models and add on excel calculations applicable at the conceptual design stage to evaluate the pre-feasibility of the alternatives. The processes were compared using the following criteria: energy efficiency from biomass to products, primary energy efficiency, GHG reduction potential and economy (expressed as net present value: NPV). Several novel biorefinery concepts gave higher energy yields, GHG reduction potential and NPV.