Journal of Heat Recovery Systems最新文献

Combining a closed-cycle gas turbine (CCGT) power conversion system and a point-focusing distributed solar receiver system, consisting of parabolic dish reflectors with focal-mounted heat source exchangers and a centralized prime-mover, represents a power plant concept well suited to the needs of a small urban/industrial community. Utilizing the attractive sensible heat rejection characteristics of the Brayton cycle, the plant with a rating up to say 10 MWe, operating in a combined heat and power mode, would provide continuous total energy needs. The proposed simple hybrid solar-fossil cogeneration plant would have freedom from the requirements of oil and gaseous fuels.

This project at ABM Chemicals demonstrates the use of a glass tube heat exchanger to recover heat directly from a spray dryer exhaust to pre-heat the inlet air. It was originally envisaged that this would reduce the energy consumption of the dryer by around 20%.

Funding was granted by the Energy Efficiency Office of the Department of Energy under the Energy Efficiency Demonstration Scheme for both a feasibility study and the installation and monitoring of the project. The heat recovery was installed in June 1983 and an initial monitoring exercise carried out. Technical problems have prevented further monitoring and this interim report discusses the background to the project and the results to date.

Because of the corrosive and fouling nature of the exhaust and the arrangement of the ductwork, the most cost-effective option for this particular installation, was a glass tube air-to-air heat exchanger. Depending upon the production outputs, the expected savings were in the range 3.6–5.5 TJ/yr. These savings are worth £10,700 to £16,300/yr from reduced gas consumption and give a simple payback against the £27,000 installation cost, of between 1.7 and 2.5 yr. In other situations it might also be possible to reduce installation costs, which would also lead to a payback of less than two years.

Measurement of the performance of the heat exchanger showed that the amount of heat being recovered, 3.0 TJ/yr, was less than anticipated. Under these conditions the savings would give a 3 yr payback. This reduced performance is believed to be due to a higher-than-anticipated level of fines in the exhaust. This has led to fouling of the heat transfer surfaces, and eventually to the failure of a number of the glass tubes. Measures are currently in hand to reduce the carryover and further monitoring of the replacement exchanger is planned.

This project is one of a package of demonstrations for heat recovery in spray dryers. A similar project at Clayton Aniline uses a run-around coil heat exchanger to recover energy from the dryer exhaust, and a project at BIP Chemicals demonstrates the use of a separate heat source to pre-heat the dryer inlet air.

Within the U.K., widespread adoption of heat recovery on spray dryers would lead to energy savings of 100,000 tonnes of coal equivalent/yr (tce/yr). It is estimated that within the next 5 yr around 20% of

The use of liquid fluidised bed heat exchangers (LFBE) as a promising method of physically eliminating scaling of heat transfer surfaces due to geothermal fluids is described.

The methodology employed by other researchers for the development of a heat transfer design equation to predict bed-side convection coefficients is analysed. It appears that such a methodology is inappropriate.

An analytical mathematical method for determining the constants in the design equation to predict fluidisation-related convection coefficients is developed and proposed for the analysis of pertinent experimental data. Preliminary results employing the method are included and a complete analysis is underway.

The operating histories and performance of a large (180 MW_e) central condensing plant and five small (5 MW_e) wellhead backpressure power plants are presented. The thermodynamic performance of the central plant is compared with an estimated possible performance based upon the work of Michaelides [2]. Both types of plant have been shown to be reliable despite some problems due to the contaminants which are associated with geothermal steam.