Linear active disturbance rejection control of waste heat recovery systems with organic Rankine cycles

In this paper, a linear active disturbance rejection controller is proposed for a waste heat recovery system using an organic Rankine cycle process, whose model is obtained by applying the system identification technique. The disturbances imposed on the waste heat recovery system are estimated through an extended linear state observer and then compensated by a linear feedback control strategy. The proposed control strategy is applied to a 100 kW waste heat recovery system to handle the power demand variations of grid and process disturbances. The effectiveness of this controller is verified via a simulation study, and the results demonstrate that the proposed strategy can provide satisfactory tracking performance and disturbance rejection

Applications of thermal energy storage to waste heat recovery in the food processing industry

A study to assess the potential for waste heat recovery in the food industry and to evaluate prospective waste heat recovery system concepts employing thermal energy storage was conducted. The study found that the recovery of waste heat in canning facilities can be performed in significant quantities using systems involving thermal energy storage that are both practical and economical. A demonstration project is proposed to determine actual waste heat recovery costs and benefits and to encourage system implementation by the food industry

CFD Modeling of Waste Heat Recovery on the Rotary Kiln System in the Cement Industry

The cement production process is one of the most energy and cost intensive in the world. In order to produce clinker, a cement industry requires the substantial energy consumption. About 70% of energy consumption lies on the unit of rotary kiln system. The higher amount of energy consumption is due to the lack of work efficiency tools leading the waste heat. This reserach was focus on modeling of the waste heat recovery in the rotary kiln system using CFD. Analysis of mass and energy balance was used to determine the sources of heat loss from kiln system. The results showed that the distribustion of the input heat to the system is a good agreement with the output energy and gave the significant insights oft the reasons for the low overall system efficiency. The system efficiency is obtained of 53 %. The major heat loss sources have been determined as kiln exhaust (21.88% of total input), cooler exhaust to stack (9.62 % of total input) and heat loss astemated as heat from kiln surface (13.54 % of total input). The amount of heat energy can be absorbed by air amounted to 163,080 Kcal / hour and can be used as air for combustion of fuel. Based on data calculation, the amount of coal can be saved amounted to 738 kg / day

Design sensitivity analysis of using various flow boiling correlations for a direct evaporator in high-temperature waste heat recovery ORCs

High-temperature waste heat (250°C-400°C) sources being created by industrial operations such as metallurgical industry, incinerators, combustion engines, annealing furnaces, drying, baking, cement production etc. are being utilized in Organic Rankine cycle (ORC) waste heat recovery systems. Alongside indirect ORC evaporators having intermediate heat carrier loops, ORC waste heat recovery can also be done through a direct evaporator (e.g. tube bundles) applied on a heat source. In an evaporator design problem, the accuracy of the design method has a significant impact on the end result. In that manner, for revealing the design accuracy error margin of using various flow boiling heat transfer methods, a design sensitivity analysis is performed by means of using 13 different flow boiling heat transfer correlations. All correlations are implemented separately into an iterative evaporator calculation and the resulting sizing solutions are compared for a representative high-temperature waste heat recovery evaporator case. The volumetric flow rate of the waste heat is 80000 Nm³/h and the inlet temperature is 375°C. The considered working fluid is cyclopentane and the deduced optimal evaporation temperature (OET) is 227°C. The minimum corresponding total transferred heat in the evaporator is at least 3,5 MW in all calculations

Waste heat recovery via organic rankine cycle: results of a era-SME technology transfer project

The main goal of the EraSME project “Waste heat recovery via an Organic Rankine Cycle”, completed by partners Howest (Belgium), Ghent University (Belgium) and University of Applied Sciences Stuttgart (Germany) between 1 January 2010 and 31 December 2012, was to find an entrance in Flanders for the Organic Rankine Cycle (ORC) technology in applications with sufficient amounts of waste heat at high enough temperatures. The project was preceded by a similar study that focused on renewable energy sources. Several tools were developed to aid in the viability assessment, the selection, and the sizing of ORC installations. With these methods, a fast determination of feasibility is possible. The outcome is based on the size, nature and temperature of the waste heat stream as well as the electricity price. An estimate can be given of the net power output, the investment costs and the economic feasibility. The tool is linked to a database of ORC manufacturer specifications. Another objective of the project was to keep track of the evolution in ORC market supply, both commercial and precommercial. We also looked beyond the product line of the main manufacturers. Some ORCs are developed for specific applications. ORC technology was benchmarked against alternatives for waste heat recovery, such as: steam turbines, heat pumps and absorption cooling. ORC in or as a combined heat and power (CHP) system was also examined. A laboratory test unit of 10kWe nominal power was installed during the project, which is now used in further research on dynamic behavior and control. It is still the only ORC demonstration unit in Flanders and has been very instructive in introducing representatives from industry, researchers and students to the technology. A considerable part of the project execution consisted of case studies in response to industrial requests from several sectors. Detailed and concrete feasibility studies allowed us to define the current application area of waste heat recovery ORC in a better way. A knowledge center for waste heat recovery (www.wasteheat.eu) was initiated to consolidate the know-how and to advise potential users

Thermal energy storage for industrial waste heat recovery

The potential is examined for waste heat recovery and reuse through thermal energy storage in five specific industrial categories: (1) primary aluminum, (2) cement, (3) food processing, (4) paper and pulp, and (5) iron and steel. Preliminary results from Phase 1 feasibility studies suggest energy savings through fossil fuel displacement approaching 0.1 quad/yr in the 1985 period. Early implementation of recovery technologies with minimal development appears likely in the food processing and paper and pulp industries; development of the other three categories, though equally desirable, will probably require a greater investment in time and dollars

Low-grade heat recovery in industrial processes

Bakalářská práce je zaměřena na možnosti využití odpadního tepla z průmyslových procesů. Počáteční část se zabývá teoretickým úvodem do problematiky přenosu tepla. V další části jsou uvedeny nejčastější zdroje odpadního tepla. Ve třetí části práce jsou shrnuty metody pro využití odpadního tepla. Poslední, praktická část ukazuje zavedení systému na využití odpadního tepla do reálného provozu.The bachelor thesis is focused on the waste heat recovery options from industrial processes. The first part is the theoretical introduction into the problematics of the heat transfer. In the next part the most common waste heat sources are presented. The third part summarizes the methods for waste heat recovery. The last, practical part presents the implementation of the waste heat recovery system into the real operation.

Techno-economical and Environmental Study of Utilizing Alternative Fuel and Waste Heat Reuse in a Cement Plant

In this work, a cement plant was simulated to estimate heat losses and pollution emission in the process. Also, a waste heat recovery system was introduced to use two main sources of heat losses, i.e. flue gas and hot air streams and produce steam and power. Moreover, the use of natural gas as an alternative to the current energy source, fuel oil, was studied in two cases, associated with and without waste heat recovery system. Results showed that 34.28% of initial energy was lost in the base case, 48% of which is from flue gas and hot vent air streams. Also, changing the fuel source from fuel oil to natural gas results in CO2 emission rate to decrease from 118,693 to 115,367 kg/hr, and emission of NO2 and SO2 was reduced to nearly 100%. In addition to environmental benefits, economical analyses suggest the use of waste heat recovery system as well as change of fuel for this plant.Key words: Cement plant; Waste heat recovery; Alternative fuel; HYSYS simulation; Air pollution reductio

Waste Heat Recovery in Food and Drinks Industry (Abstract only)

Most baking processes in the food manufacturing sector involve use of gas-fired ovens. Only about one-third of the total energy used in these ovens adds value to the final product. The remaining two-thirds is discharged with the exhaust gases at 150-250o C and thus represents an opportunity for heat recovery. However, the low temperature range, fouling and presence of corrosive materials in the exhaust streams make heat recovery technically challenging and uneconomical. The existing low grade heat recovery technolgies mostly use gas to liquid heat transfer to produce hot water for use in other areas of the manufacturing plant. The performance of these systems is governed by hot water demand in the factory and is therefore not recommended if there are frequent fluctuations in demand or if a more efficient technology, such as combined heat and power, is already in place. This study involves design, manufacturing and testing of a novel low-temperature gas to gas heat recovery system using an array of heat pipe heat exchangers, for industrial-scale baking ovens at a large confectionary manufacturing plant. Unlike gas to liquid heat transfer, a gas to gas heat transfer system provides direct savings in oven fuel consumption, independent of the hot water and other energy demands elsewhere in the plant. The heat recovery potential of the system is estimated using a thermodynamic model developed based on energy and mass balance for the ovens. The design enables recovery of up to 50% of the energy available through the exhaust stack, increasing the energy efficiency of the overall process to 60% and reducing food manufacturing costs by one third