Electricity Generation from Low and Medium Temperature Industrial Excess Heat in the Kraft Pulp and Paper Industry

The recovery and utilisation of industrial excess heat has been identified as an important contribution for energy efficiency by reducing primary energy demand. Previous works, based on top-down studies for a few sectors, or regional case studies estimated the overall availability of industrial excess heat. A more detailed analysis is required to allow the estimation of potentials for specific heat recovery technologies, particularly regarding excess heat temperature profiles. This work combines process integration methods and regression analysis to obtain cogeneration targets, detailed excess heat temperature profiles and estimations of electricity generation potentials from low and medium temperature excess heat. The work is based on the use of excess heat temperature (XHT) signatures for individual sites and regression analysis using publicly available data, obtaining estimations of the technical potential for electricity generation from low and medium temperature excess heat (60–140 °C) for the whole Swedish kraft pulp and paper industry. The results show a technical potential to increase the electricity production at kraft mills in Sweden by 10 to 13%, depending on the level of process integration considered, and a lower availability of excess heat than previously estimated in studies for the sector. The approach used could be adapted and applied in other sectors and regions, increasing the level of detail at which industrial excess heat estimations are obtained when compared to previous studies.

The Effect of Excess Heat Utilization on the Production Cost of Cement

Industrial excess heat is a largely untapped resource that has the potential for external use that would be beneficial to the cement industry. Therefore, this work studied the excess heat utilization for the optimization of production cost in a cement plant within a period of three years. The study of plant layout in the selected plant in Nigeria (Ewekoro II Cement Plant of 200 tonnes/hour) was carried out to identify areas where excess heat is generated. The temperature and static pressure of precalciner, kiln, and cyclone were taken using a temperature probe, pitot tube, digital manometer, and light-emitting diode temperature reader. These parameters were used to obtain the mass flow rate and heat transfer needed for the heat energy analysis of the system. The kiln was maintained at constant tonnage per hour through a clinker truck weighed using the weighbridge. The result showed that the heat generated from the kiln was 577,640,260 MJ/hr. through excess air draft of 780,000 m3/hr (89.4%) at 250 °C and induced draft fan of 900,000 m3/hr at 350 °C. The result showed that excess heat can be utilized in pre-heater and air quenched cooler boilers, steam turbines and auxiliaries, and generators. The total estimated heat that could be saved amounted to 344,648,250 MJ with a total annual capacity of 2.25 million tonnes of cement. A saving of over two billion dollars could be achieved in production cost per year.

Prototipe Pengaman Kebakaran Rumah Menggunakan Thermal Camera

80% of cases of building or house fires in Indonesia are caused by electrical short circuits. Currently, there are only MCB and ELCB devices protecting for building electrical installations, but these devices cannot protect the conditions that cause fires. In a short circuit, there will be heating of the short cable or device. In this study, researchers used a thermal camera that can be placed on an electrical panel to be able monitor the temperature of electrical panel which includes cables, MCB, or can be placed on other devices. When the detected object temperature exceeds a predetermined limit, the device will provide a warning in the form of sound and text and can automatically cut off electricity in the building's electricity network. This research produces a prototype of a power grid safety device using a Raspberry Pi that can be applied to buildings and objects that have the potential to emit excess heat that can cause fires. Systems it will be able to monitor, provide warnings and can automatically cut off the electricity network when the temperature of the observed object exceeds the specified limit and has the potential to emit excess heat which can cause a fire.

An optimisation approach for spatial allocation of energy sources to district heating networks

District heating networks (DHN) combined with low-carbon heat sources are a promising way to reduce greenhouse gas emissions from heating. However, few works have addressed the problem of allocating localised thermal energy supplies to DHN heating demands considering the spatial proximity constraint of transporting heat energy. The work improves an existing spatiotemporal analysis method by introducing an adapted form of Hitchcock transportation problem and linear programming to solve the optimal allocation problem in network of supplies and demands. The new method is compared with the original method and is found to improve the accuracy of estimating the allocable industrial excess heat supply in a Swiss case study. The method could be applied to diverse thermal sources, such as industrial excess heat, geothermal, lakes and rivers, etc.

Excess heat capacity and entropy of mixing along the hydroxyapatite-chlorapatite and hydroxyapatite-fluorapatite binaries

The heat capacity, Cp, of synthetic hydroxyapatite [Ca5(PO4)3OH–OH-Ap], as well as of ten compositions along the OH-Ap-chlorapatite (Cl-Ap) join and 12 compositions along the OH-Ap-fluorapatite (F-Ap) join have been measured using relaxation calorimetry (heat capacity option of the Physical Properties Measurement System—PPMS) and differential scanning calorimetry (DSC) in the temperature range of 5–764 K. Apatites along the Cl-OH and F-OH joins were synthesized at 1100 °C and 300 MPa in an internally heated gas pressure vessel via an exchange process between synthetic fluorapatite or chlorapatite crystals (200–500 μm size) and a series of Ca(OH)2-H2O solutions with specific compositions and amounts relative to the starting apatite. The standard third-law entropy of OH-Ap, derived from the low-temperature heat capacity measurements, is S° = 386.3 ± 2.5 J mol−1 K−1, which is ~ 1% lower than that resulting from low-temperature adiabatic calorimetry data on OH-Ap from the 1950’s. The heat capacity of OH-Ap above 298.15 K shows a hump-shaped anomaly centred around 442 K. Based on published structural and calorimetric work, this feature is interpreted to result from a monoclinic to hexagonal phase transition. Super ambient Cp up to this transition can be represented by the polynomial: $$C_{p}^{{\text{OH - Ap}}} {}_{{298K - 442K}}\left( {{\text{J mol}}^{ - 1} {\text{K}}^{- 1}} \right) = {1013.7-13735.5T^{{ - 0.5}}} + 2.616718\,10^{7} T^{{ - 2}} - 3.551381\,10^{9} T^{{ - 3}} .$$ C p OH - Ap 298 K - 442 K J mol - 1 K - 1 = 1013.7 - 13735.5 T - 0.5 + 2.616718 10 7 T - 2 - 3.551381 10 9 T - 3 . . The DSC data above this transition were combined with heat capacities computed using density functional theory and can be given by the Cp polynomial: $$C_{p}^{{\text{OH - Ap}}} {}_{{ >\,442K}}\left( {{\text{J mol}}^{ - 1} {\text{K}}^{- 1}} \right) = {877.2-11393.7 T^{ - 0.5}} + {5.452030\,10^{7}} \,T^{- {2}} - {1.394125\,10^{10}} \,T^{- {3}}$$ C p OH - Ap > 442 K J mol - 1 K - 1 = 877.2 - 11393.7 T - 0.5 + 5.452030 10 7 T - 2 - 1.394125 10 10 T - 3 . Positive excess heat capacities of mixing, ∆Cpex, in the order of 1–2 J mol−1 K−1, occur in both solid solutions at around 70 K. They are significant at these conditions exceeding the 2σ-uncertainty of the data. This positive ∆Cpex is compensated by a negative ∆Cpex of the same order at around 250 K in both binaries. At higher temperatures (up to 1200 K), ∆Cpex is zero within error for all solid solution members. As a consequence, the calorimetric entropies, Scal, show no deviation from ideal mixing behaviour within a 2σ-uncertainty for both joins. Excess entropies of mixing, ∆Sex, are thus zero for the OH-Ap–F-Ap, as well as for the OH-Ap–Cl-Ap join. The Cp–T behaviour of the OH-Ap endmember is discussed in relation to that of the F- and Cl-endmembers.

Exploitation of Excess Low-Temperature Heat Sources from Cogeneration Gas Engines

The chapter presents an innovative technical solution for the use of low-temperature excess heat from the combined heat and power (CHP) of gas engines using gas or liquid fuel for district heating, building heating or industry. The primary fuel efficiency of CHP gas engines for heat production can be significantly increased by using the low-temperature excess heat of the exhaust gasses and the cooling system of the CHP gas engine, which are released into the environment thereby also reducing CO2 emissions. District heating hot water systems generally work with higher temperatures of the heating water, which is transported to the heat consumer via the supply line, and the cooled heating water is returned to the CHP gas engine via the return line. In order to make use of the excess low-temperature heat of the exhaust gasses and the cooling system of the CHP gas engine, a condenser must be installed in the exhaust pipe in which the water vapor contained in the exhaust gasses condenses and a mixture of water and glycol is heated, which later leads to the evaporator of the high-temperature heat pump (HTHP). The cooled heating water is returned from the heat consumer via the district heating return pipe to a condenser of one or more HTHPs connected in series, where it is reheated and then sent to a CHP gas engine, where it is reheated to the final temperature. The Aspen plus software package is used to run a computer simulation of one or more HTHPs connected in series and parallel to the district heating system and to demonstrate the economics of using the excess heat from the exhaust gasses and the cooling system of the CHP gas engine.