Perry William Johnson

University of Sydney

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T.A.G. Langrish

University of Sydney

H. Li

W. L. Conger

University of Kentucky

A.H. Akbarzadeh

McGill University

Tim Ag Langrish

University of Sydney

Cooperative Institutions

University of Sydney

Australian Research Council

East China University of Technology

University of Canterbury

University of Kentucky

McGill University

Sharif University of Technology

University of New Brunswick

Amirkabir University of Technology

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Availability (exergetic) analysis of coal gasification processes. Part I. Theoretical considerations

Fuel Processing Technology (1981)

Perry William Johnson W. L. Conger

10.1016/0378-3820(81)90027-8

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Citations (2)

Interpreting exergy analysis as applied to spray drying systems

International Journal of Exergy (2020)

Perry William Johnson T.A.G. Langrish

The comparison of different energy recovery systems employed on a spray dryer is challenging. This work compares two cases with a base case of a dryer alone, to identify any available improvements and interpretation of the factors used within exergy analysis, for system-wide optimisation. While exergy analysis results indicate natural gas boiler systems (case 1) are superior to compressor-driven recovery systems (case 2) (13% better evaporation efficiency), this paper demonstrates the significant potential to improve either system, and that dryers are one of the limiting units within the process (38% exergy improvement potential). The improvement potential for both cases is quite high (~90% of total added exergy), particularly as the inlet gas temperature increases. This paper demonstrates a method of simplifying exergy analysis to make it more accessible to engineers as a tool for optimising thermal and non-thermal systems that include a dryer as a significant part of the system.

Exergy efficiency

Limiting

10.1504/ijex.2020.10027135

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Citations (2)

Energy and Exergy Analysis in Spray Drying Systems

Perry William Johnson

Energy Analysis

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Inversion Temperature and Pinch Analysis, Ways to Thermally Optimize Drying Processes

Drying Technology (2011)

Perry William Johnson T.A.G. Langrish

Abstract This work studies the compatibility and suitability of a combined inversion temperature and pinch analysis with the process selection for air and superheated steam spray drying of milk solids. The inversion temperature is a good starting point for an energy analysis because it is a simplified rate-based approach to comparing the steam and air drying systems. pinch analysis enables process integration, at least on a heat recovery and heat exchanger network level. The resulting inversion temperature for the studied system was estimated as 182°C for the dryer inlet temperature. However, mass and energy balances showed that a minimum inlet temperature for spray drying of 184°C was required for the superheated steam dryer in order to ensure that the outlet solids temperature above the dew point temperature. The inversion temperature is still very relevant in the early stages of a design process because it allows a quick assessment of which drying medium should result in a smaller dryer. It was evident that the steam system is better from an energy perspective because of the recoverable latent heat of the water vapor carried out of the dryer with the recycled steam. The steam system has between 82 and 92% of thermal energy recovery potential as condensable steam, compared with 13–30% energy recovery of the air system. However, other important design and operational factors are not discussed here in detail. Combining the inversion temperature and pinch analysis suggests that superheated steam drying both gives better energy recovery and is likely to give smaller dryers for all operational conditions. Keywords: Energy analysisInversion temperatureOptimizationPinch analysisSpray drying

10.1080/07373937.2010.512427

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Citations (14)

Exergy analysis of a spray dryer: Methods and interpretations

Drying Technology (2017)

Perry William Johnson T.A.G. Langrish

Exergy analysis has been used to assess the intrinsic exergy efficiency of a spray drying system modeled to produce 1.25 kg s−1 of skim milk powder. From an exergy perspective, the dryer has a low exergy efficiency of 38% (on an evaporation basis), while the efficiencies associated with the mass transfer and heat transfer are 94% (thermomechanical efficiency) and 30% (transiting exergy efficiency), respectively. The improvement potential of 575 kW, of the 722 kW energy flow in the feed, also shows that the exergy efficiencies of spray dryers are intrinsically small. Reviewing exergy efficiency factors, there appears to be no universal efficiency factor for an exergy analysis. The inevitable (INE) exergy loss method is a potential shortcut technique based on the Carnot efficiency and first law analysis. There are some limitations on using the INE method for processes that are not exclusively thermal; in those cases, an entropy balance (second law property) is more appropriate. The INE method still shows potential as a starting basis of comparison because it shows the scale and the efficiency together, which is important for targeting areas for process improvement without doing a full exergy analysis. This work is a short review of the work on dryer exergy efficiency, mainly focusing on the various factors which are used, followed by a discussion and case study testing each factor to find a potential optimization method and a discussion on each factors merits.

Exergy efficiency

Carnot cycle

10.1080/07373937.2017.1349790

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Citations (17)

Avoiding headaches from in-plant air problems

Pollution Engineering (1995)

Perry William Johnson

The key to solving in-plant hazardous air pollution is identifying the problem. Welding gases (especially nitrogen dioxide), solvent vapors, mineral dust and metal plating operations all pose hazards to workers. First, the problem must be identified, then its impact and severity must be evaluated, and finally the feasible options to control the air contaminants of concern must be assessed before selecting the best solution. Significant improvements to air quality in most industrial plants can be made easily and cost effective.

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Pinch and exergy analysis in drying: A thermodynamic backbone for process optimisation and environmental assessment

Chemeca 2011: Engineering a Better World: Sydney Hilton Hotel, NSW, Australia, 18-21 September 2011 (2011)

Perry William Johnson Tim Ag Langrish

This work studies the usefulness and suitability of both pinch and exergy analysis in determining process bottlenecks and low energy efficient areas in the area of drying technology. These techniques have been applied to an ideal short-form spray dryer in the dairy industry. An air dryer and a superheated steam system were compared to demonstrate the effectiveness and usefulness of these techniques in determining bottlenecks, and possible process changes. Results from the pinch analysis when comparing steam and air drying, indicate that the steam system has a thermal-energy recovery potential between 82-92%, compared with the 13-30% of the air system. The pinch temperature for a dryer is typically that of the outlet, but this is not always the case. Combining the pinch and exergy analysis provides an insight into ways to modify dryer design and analyse the integration of drying systems.

Pinch analysis

Exergy efficiency

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The thermal characteristics of a closed two-phase thermosyphon at low temperature difference

Heat Recovery Systems and CHP (1991)

H. Li A.H. Akbarzadeh Perry William Johnson

Thermosiphon

Condenser (optics)

Working fluid

10.1016/0890-4332(91)90055-9