Drying Energy Consumption Research Articles

Energy efficient combined superheated steam dryer/MED

In a world of depleting fossil fuel resources, energy conscious research activities have become relevant for all industrial applications. Drying as an energy intensive process, is one example when conventional air drying is replaced by superheated steam (SHS) drying. This work presents a novel arrangement which reduces the SHS drying energy consumption. The analysis is applied to a milk powder producing plant that includes both concentration and drying processes. These are powered by a gas turbine of the simple Brayton cycle type. The raw feed is preheated before being concentrated in a single effect evaporator driven by a mechanical vapour compressor (MVC). The drying SHS in the dryer operates in a recycled mode while the evaporated water is purged and compressed in a two stage MVC equipped with an intercooler and aftercooler. The purged compressed steam is used to boost the SHS temperature from the circulating blower exit up to the required inlet temperature of the dryer. Use is made of the waste energy of the gas turbine exhaust. The balance of the recovered energy drives a multiple effect desalination (MED) unit to produce fresh water. The analysis coveres a range of dryer inlet temperatures of 150–275°C. The preheater surface area and feed concentrator shaft power per ton of powder (TP)/h are 30.4 m 2 and 34.5 kW, respectively. For the dryer, the ratio of SHS COP t/air COP t ranges from 2.51-1.94 for 150–275°C inlet temperature respectively. The overall power required/TP h is 502–423 kW, and the fresh water produced varied from 10.82–12.51 gallons/kWh for a 150–275°C inlet temperature respectively. The water produced can satisfy the requirements of about 40% of the milking heads.

Friction, heat and mass transfer for paper drying

The process of paper drying has been investigated on an experimental basis. The mass transfer coefficient through rough, permeable paper drying fabrics has been shown to be considerably reduced below that from an open surface by between 60–75%, whilst the composition of the paper sheet and increases in felt tension were found to have a minor effect on the observed drying rates (< 10%). The turbulence data for the smooth curved hill arrangement supported the prevailing literature in terms of both skin friction coefficient and velocity profiles. The findings of this study have been applied in a mathematical model, relating key operating conditions to achievable drying rates, and highlight the opportunity for the reduction of energy consumption in paper drying.

Energetical Optimalisation of the Grain Drying Processes by the Control of Airflow Rate

The control of the grain driers is very important, both to save the quality of the agricultural products and to reduce the energy consumption of drying. The drying process of the different kernel products has to be divided into phases. The influence of the air flow rate on the drying characteristics of the maize kernels was investigated. The subject of this research work was to keep the relative humidity of the output drying air constant and hereby to increase the power efficiency of grain driers. The mathematical model described in this study is helpful in designing the energy and quality saving grain driers.

Energy recovery in drying applications

Theoretical and experimental studies were performed for decreasing energy consumption in corn drying by using an adsorption-desorption cycle. Local natural zeolite (clinoptilolite) was used as the adsorbent and comparisons were made for various operational conditions. It was concluded that the adsorption-desorption cycle has a promising future for energy recovery in drying applications.

Peanut Drying Energy Consumption — A Simulation Analysis

Abstract During the past few years the cost of conventional sources of energy has dramatically increased and future supplies are uncertain. Available energy sources must be used in the most efficient manner. However, with any changes in recommended peanut drying procedures, product quality must be maintained. An analysis of various factors affecting energy consumption and drying time of peanuts was performed, using a computer simulation model. The analysis included consideration of ambient conditions, dryer controls, and initial peanut moisture. The analysis indicated that the airflow rate used in many commercially available farm dryers is necessary to adequately dry high moisture peanuts, but that a lower airflow rate would be adequate for low-moisture peanuts. A lower airflow rate would reduce energy consumption. Increasing the temperature rise of the drying air would speed drying but would also lower milling quality. Energy consumption was lowest early in the drying season when ambient drying potential was high.

Peanut Drying Energy Consumption

Abstract Total energy consumption and drying times were determined for drying peanuts with various equipment and procedures commonly used by the peanut industry. Total peanut drying times were significantly shorter with 3.73 kW, single-trailer (ST) dryers than with 7.46 kW, double-trailer (DT) dryers. Total energy consumption was significantly higher per tonne of peanuts dried for drying with ST dryers. Total energy consumption and drying times were not significantly different for drying in side-air-entry or rear-air-entry trailers. Precleaning reduced energy requirements for drying and slightly reduced total drying times. Drying peanuts at 40.56°C decreased drying times but required considerably more energy than drying at 35°C. Type of temperature control, constant (Co) or cycling (Cy), had no effect on drying times or energy consumption.

Quality Changes During high low temperature drying

ADSTRACT INCREASING emphasis on grain quality and energy conservation has created a need to develop drying systems that will deliver a better quality product with lower energy consumption for drying. There is also the problem of increasing the capacity of a drying system as the system expands to size. A combination high-temperature, low-temperature drying system as described by Cloud et al. (1976) and Morey et al. (1976) may provide some solutions to these three concerns. The purpose of this study was to determine on a field scale the effects of combination high-temperature, low-temperature drying on quality of grain as compared to conventional high-temperature drying. Quality factors considered included the grading factors of broken corn and foreign material, and test weight, breakage sus-ceptibility as measured by the Stein breakage test, germination, and mold development. Combination drying treatments included use of a high-temperature cross-flow batch dryer to deliver grain hot to a bin equipped for low-temperature dry-ing. The moisture content of the corn delivered from the dryer must be at a level that can be safely handled in a low-temperature system (18 to 22 percent) after being cooled. The results of this work are intended to assist in pro-ducing guidelines for management of combination drying systems which will most effectively improve grain quality.