Medium-scale Plant Research Articles

Simulation Study of Integrated Solar Combined Cycle Systems: Medium Scale Plant in Irbid City

Simulation Study of Integrated Solar Combined Cycle Systems: Medium Scale Plant in Irbid City

Turbo-assisted direct solar air heater for medium temperature industrial processes using Linear Fresnel Collectors. Assessment on daily and yearly basis

The study analyzes an innovative concentrating solar thermal system aimed at the direct production of hot air for industrial applications. Air is heated inside linear Fresnel collectors in an open to atmosphere circuit, not requiring the use of a primary heat transfer fluid and a heat exchanger, with their associated cost and maintenance. Matching an automotive turbocharger with the solar field avoids auxiliary energy consumption for pumping the airflow. The detailed quasi-steady numerical model implemented, including commercial collector and turbocharger technical features, allows to scrutinize the daily and yearly operating time profile of a medium scale plant with a 633.6 m2 solar field. Considering the typical meteorological year of the selected location (Madrid, Spain), the numerical results indicate that hot air is provided at a remarkable quasi-constant temperature between 300 °C and 400 °C despite the solar variations, delivering 330 MW h per year without overheating the receiver evacuated tubes.

A Practical Methodology for the Design and Cost Estimation of Solar Tower Power Plants

Concerns over the environmental influence of greenhouse gas (GHG) emissions have encouraged researchers to develop alternative power technologies. Among the most promising, environmentally friendly power technologies for large-scale applications are solar power tower plants. The implementation of this technology calls for practical modeling and simulation tools to both size the plant and investigate the scale effect on its economic indices. This paper proposes a methodology to design the main components of solar power tower plants and to estimate the specific investment costs and the economic indices. The design approach used in this study was successfully validated through a comparison with the design data of two operational commercial power tower plants; namely, Gemasolar (medium-scale plant of 19.9 MWe) and Crescent Dunes (large-scale plant of 110 MWe). The average uncertainty in the design of a fully operational power tower plant is 8.75%. A cost estimation showed the strong influence of the size of the plant on the investment costs, as well as on the economic indices, including payback period, internal rate of return, total life charge costs, and levelized cost of electricity. As an illustrative example, the methodology was applied to design six solar power tower plants in the range of 10–100 MWe for integration into mining processes in Chile. The results show that the levelized cost of electricity decreases from 156 USD/MWhe for the case of a 10-MWe plant to 131 USD/MWhe for the case of a 100-MWe plant. The internal rate of return of plants included in the analyses ranges from 0.77% (for the 10-MWe case) to 2.37% (for 100-MWe case). Consequently, the simple payback ranges from 16 years (for the 100-MWe case) to 19 years (for the 10-MWe case). The sensitivity analysis shows that the size of the solar receiver heavily depends on the allowable heat flux. The degradation rate and the discount rate have a strong influence on economic indices. In addition, both the operation and the deprecation period, as well as the price of electricity, have a crucial impact on the viability of a solar power tower plant. The proposed methodology has great potential to provide key information for prospective analyses for the implementation of power tower technologies to satisfy clean energy needs under a wide range of conditions.

Medium-scale Plant Experiment of Sewage Sludge-based Phosphorus Fertilizers from Large-scale Thermal Processing

ABSTRACTPhosphorus (P) recycling from sewage sludge for agricultural needs has to meet requirements for agricultural implementation, such as short and long-term P-plant-availability under field conditions. Field experiments often bring no evaluable results, because agricultural soils got a high potential of P-supply even if they are classified as low in P-supply according to the CAL extraction method. The present study presents a possible way to investigate the P-plant-availability of P-recycling-fertilizers under field-like conditions. The plant experiments are firstly performed in small Mitscherlich pots in growth chambers and subsequently in containers with a high soil volume of 170 kg under greenhouse conditions, in which plants can grow until ripening. The tested P-recycling-fertilizers were produced from sewage sludge in a large-scale thermal process. It was a two-step treatment process performed with a pyrolysis of sewage sludge at 550°C (SSC-550) and a subsequent thermochemical post-treatment at 950°C with Na2SO4 (SSA-Na) and HCl + Na2SO4 (SSA-HCl/Na) as additives. The results show, that the P-recycling-products from pyrolysis got an adequate long-term but a 65% lower short-term P-plant-availability compared to triple-superphosphate. SSA-Na and SSA-HCl/Na show both a high short and long-term P-plant-availability comparable to triple-superphosphate. This can be explained by their highly plant-available P-compound CaNaPO4.

Cost analysis of pig slaughtering: A Hungarian case study

The scale of Hungarian slaughterhouses is small in international comparison and the cost of slaughter and cutting a pig of average live weight is relatively high at 16.1-19.4 EUR on average. The aim of this study is to evaluate the cost of pig slaughter and cutting through the case study of a medium-scale plant in Hungary. Based on data from the enterprise, a calculation was performed in relation to the “output” quantity of pig slaughter and cutting, as well as its value and the cost and cost structure of processing. The capacity of the examined plant and its utilisation were analysed and cost reductions were estimated for various increases of output. In 2015, the direct cost of slaughter and cutting was 18.9 EUR per pig for the medium-scale plant which processed 100 thousand pigs. When the purchase cost of pigs is excluded, labour costs accounted for the highest share (30%) of costs, followed by services (29%) and energy costs (21%). For this reason, the level of wages and employer’s contributions has a rather high significance. Analysis showed that significant increases in Hungarian minimum wage and guaranteed living wage in 2017 resulted in an estimated 7% increase in the cost of slaughter and cutting compared to 2015, despite the decrease of contributions. The capacity utilisation of the plant was a low 28% when compared to a single 8-hour shift considered full capacity. The cost of slaughter and cutting was estimated to be reduced to 14.2-17.0 EUR per pig if the plant operated at full capacity. This may be considered a lower bound estimate of cost because there are numerous restricting factors on optimising capacity utilisation, such as: 1) number of live animals available for purchase and related logistics; 2) cooling capacity availability; 3) labour availability; 4) market position of the enterprise and potential for marketing additional pig meat products. Enterprises of this scale are recommended to consider producing more value-added products and, accordingly, investing in product development.
 JEL Classification: Q13, Q19

An automated medium scale prototype for anaerobic co-digestion of olive mill wastewater

Olive oil production constitutes one of the most important agro-industrial business for Mediterranean countries, where 97% of the international production is focused. Such an activity, mainly carried out through three phase olive oil mill plants, generates huge amounts of solid and liquid by-products further than olive oil. Physico-chemical features of these by-products depend on various factors such as soil and climatic conditions, agricultural practices and processing. As currently carried out, the disposal of these by-products may lead to numerous problems taking into account management, economic and particularly environmental aspects. Indeed, olive mill wastewater is not easily biodegradable due to its high chemical and biochemical oxygen demand, its high content in phenolic compounds, high ratio C/N and low pH, leading consequently to soil and water source pollution. Considering, the above-mentioned statements, olive mill waste disposal constitutes nowadays a challenge for oil industry stakeholders. It becomes necessary to look for alternative solutions in order to overcome environmental problems and ensure the sustainability of oil industry. Anaerobic co-digestion of olive mill wastewater with other agro-industrial matrices could be one of these solutions; since it offers the possibility to produce green energy and break down toxicological compounds contained in these wastewater for a better disposal of the digested matrices as soil conditioner. In this contest, this note reports the functioning principle of an automated medium scale plant for anaerobic co-digestion of olive mill wastewater.

Design of an Energy Monitoring System for a Medium-Scale Plant

In this study, energy monitoring system of a medium scale industrial plant is achieved through a computer interface both in real time and retrospective using recent data. In order to measure the energy, a measurement card is designed to convert the voltage and current signals in suitable levels for a programmable logic controller (PLC). Current and voltage signals received from the measurement card are sensed by the analogue channels of the PLC. A zero-crossing detector is also designed to measure the power factor of the system. Time difference between the signals which are obtained from the zero-crossing detector is measured by using FM 350-01 counter module. All data received are transferred into a database located at the host computer by the PLC using RS485/RS232 communication protocol. Data obtained from the system can be monitored momentarily through an interface that is designed in C# programming language. Furthermore, retrospective energy analysis of the system is made possible by saving the data obtained continuously. Thus, active, reactive and apparent power values can be observed for a specific time interval. By using the retrospective energy analysis system, time periods in which the energy is more consumed can be determined. Thanks to this feature, work load of the plant can be programmed to specific times when the energy is cheaper in order to reduce the energy costs.

Design Study of Dry Wall Fast Ignition Laser Fusion Reactor with High Repetition Laser

The design of a laser fusion reactor with a dry wall chamber has been carried out. According to a simple point model calculation, sufficient pellet gain (G > 100) can be achieved with the injection energy of 400kJ under relatively conservative parameters (α = 2, ηc = 0.05, ηh = 0.2). Assuming the pulse heat load limit of a dry wall to be 2J/cm2, chamber radius of R = 5.64m is achievable. 1-D thermal analysis also supports the feasibility of this design. Then a medium scale plant (400MWe electric output) can be designed with moderate construction cost, which suits for the first-step reactor, if the laser repetition rate can be increased to 30 Hz. Since laser fusion reactors have flexibility in changing its output, this design enables them to be in flexible use according to the time-varying electric demand as the present fossil fuel power plants. This design is remarkable because it gives a new property to the fusion reactors.

Small projects for developing countries

A review is given of all aspects of the implementation of small to medium scale plant projects in non-industrialised and developing countries. The review is undertaken from the point of view of the process engineer who may be involved at any stage of the project. The particular characteristics of projects of small size in such countries are outlined, and then every stage, from inception to production, is examined in detail, to illustrate the problems that may be encountered at each one. Emphasis is laid on the pre-contract stages, since these tend to be vital to the success of the project in such countries.