The aim of the project is to analyze an energy survey of steel drawing mill which is situated in Linkoping and ensure that the energy in industrial processes is being used efficiently. The energy demand is measured for the unit processes using EnSAM application.
The unit processes is divided into support processes and production processes. The energy demand for each and every process is calculated with the acquired data and estimated the total electricity and oil demand for the whole year. The project consists of some limitations that makes difficult to work on energy saving measurements.
The method used in this project for finding out the energy demand is "Top down Approach". This approach breaks down the system into sub-system and gives the fine result of the energy demand. The results have been carried out in two ways. One with an energy survey and other with an energy saving calculation.
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The energy saving is done with an assumption in changing to low power consuming lights and by decreasing the operating time of the process. The appendix part shows the calculation of how much energy is used for the processes and the energy saved. By comparing the energy demand and energy saving, the amount of energy saved is calculated.
Table of contents
2. Objective and Limitationsâ€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦.â€¦â€¦..5
4.1 Energy Surveyâ€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦.â€¦...6
4.2 Energy Savingsâ€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦â€¦...7
The Steel industry is located in Linköping, Sweden, with a number of 80 employees in the company. It produces a wide range of cold-drawn bar steel and other metals for immediate delivery to Swedish engineering industry and exports to Nordic countries, Germany, the UK and the Benelux. The annual production is about 50,000 ton. The production is organized in campaigns of three weeks with production during 16 days. The production is closed during Midsummer and Christmas as well during a four-week holiday in summer.
One of the major challenges for the company is the large quantity of energy consumption. Due to its large industrial scale and size, the energy demand is considerably huge in the support and production process. For instance, the support process includes lighting, space heating, ventilation and compressed air, etc. In the production process, the company utilizes different energy-intensive machines, which consists bulk-throwing machine, folding machine, leveling bench, triple-straightening machine, and drawing bench. Hence, how to reduce the total energy use and how to improve the energy efficiency are the main concerns for the company.
Industry is the major energy-consuming sectors in Sweden with a 39% share (2004) in the final energy consumption (Eurostat, 2004). The share is much higher compared to other EU countries, especially in the industrial sectors. Within the total energy use, oil and electricity take up the highest proportion in terms of the type of energy consumed 67% of total (Eurostat, 2004). Furthermore, Sweden relies 36.5% of primary energy through imports, which 84% of imports are oil (Eurostat, 2004). However, the major energy sources for the company are electricity and oil, thus the energy intensity problem is more serious.
Since Sweden is participated in the European electricity market, the electricity price in Sweden raises while the European electricity price increases. In addition, the electricity generation in Sweden is mostly depending on the renewable sources such as nuclear-power (provides almost half of the electricity) and hydropower plants (Eurostat, 2004). Even though the primary price of renewable energies is low, the price of electricity is enforced to be higher in order to in accordance with the higher European electricity. Hence, the growing price of electricity is also accelerating the expenditures of company in energy use.
"Low carbon energy is a high priority in government policy" (Eurostat, 2004). With regard to increasing CO2 emissions, Sweden government posts a carbon tax on those CO2 producers. Industries are taking greater responsibilities for the CO2 emissions as they are the major energy consumers. This will result in an extra burden and cost for industries.
Objective and Limitations
The purpose of this project is to deliver an energy analysis comprising: energy survey (audit) and energy efficiency measurements to reduce the energy demand and save energy. Therefore the main objectives of this project are presented:
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Energy survey: Divide the given processes into unit processes: support processes and production processes, to calculate energy demand and the total annual energy consumption. Also find out the flaws and unnecessary processes in the energy use.
Energy efficiency measurements: After obtaining the data from energy survey, to propose the energy saving measurements and find out their priority.
In this project, there are many limitations that make it difficult to carry out the energy saving measurements, and it is significant to take these boundaries into consideration. The limitations are listed as follows:
The scope of the project limits the possibility to employ other models (exclude "unit process"), and also the optimization and simulation technologies are not used. Thus, it is difficult to suggest the optimal energy saving approach.
All the processes such as lighting, office equipment, and ventilation are assumed to running all the working hours.
The energy saving is based on assumption.
Lack of data for the working time. For instance, the measurements were made only for one week in November.
The energy losses in every process are neglected.
Limited information. All the information accessed are based on It's learning, no other reports are given.
A top-down approach is employed to carry out the energy survey. This approach is essentially the breaking down of a system to compositional sub-systems. In a top-down approach, each sub-system is refined in greater detail until the total specification is reduced to base elements.
The concept of "unit process" is applied in this project, which means all the processes of energy consumption can be divided into unit processes. As mentioned earlier, these processes are categorized by support processes and production processes. This division helps to structure the total energy used by the company and simplify the analysis.
Regarding the given data, the invoice shows the costs of purchased electricity and oil, power charge, and the annual energy consumptions during the year 2006. The measurement values for the switchgear represent how much electricity they distribute. The five production days during November and July (four non-working weeks) are used as a reference to calculate the power demand during production and non-production periods.
All the calculations are carried out by the software "EnSAM", thus to structure the unit process and gain the energy measurements.
The energy survey is conducted to figure out the energy balance of the steel mill which includes total energy demand and the consumption in different process.
The total energy input of the mill can be calculated from the company invoices which show the major energy source of the mill, oil and electricity. The invoices showed that in the year 2007, total energy demands of the mill are 3800020 kwh/year electricity and 2128000 kwh/year oil. Also, according to the invoices, total money spend on the energy of the mill can be find out which is 3203117.49 kwh/year.
With the total energy input known, according to the top-down approach, with the energy survey software EnSAM, each process in the mill should be analyzed and the energy consumption of these processes should be find out with the detailed data that provides by the steel mill and the seasonable calculation.
In order to make full use of EnSAM, processes in the mill have been categorized into the support processes and production processes which can be found below.
With the using of the provided data from the energy manager, calculations have been carried out and each process has been analyzed.
First comes the operation time. Since the production is organized in campaigns of three weeks with production during 16 days and there are 4 weeks holidays, and one day mid summer holiday and seven days of Christmas holidays. The total operation hour is 4000 and the office hour is 2250. The annual hours' including the holidays is 7896 hours.
With the use of the operation time, the follow processes energy demand can be calculated, i.e. the lighting system, with the data of light numbers and power use/lamp, multiply with the operation time, the energy consumption of the lighting system could be found out. The detail calculation will be found out in the appendix.
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In the production processes, given data are the measurement of the machines power use in every 3minutes in 7 days. And we found that these values have been changed a lot during the monitoring time, so to calculate the energy consumption with the average value may be not quite appropriate considering the veracity of the results. Therefore the calculation will be performed with probability of operation power to gain the exact values. For example, drawing machine 2. The probability of power between 10.7 kW and 96.32 kW is 8.8 %. So the power need is (10.7+96.32)/2=53.51, 53.51*0.088 = 4.708. We have calculated every power and added them to get the total power of this machine. In the end multiplying with the operation time get the energy consumption of each machine.
The results from the probability are shown in appendix.
According to the energy survey, the energy sources for the whole steel mill are electricity and oil. Rationalization of the whole energy using system will be the purpose for the energy saving part.
With the analysis and discussion, there are some strategies can be carried out in order to save the energy without affecting the production.
Reducing the operation time of some of the processes in the mill, i.e. the lighting system, change the lights into voice-activated and vibration censor which will probably reduce the operation time of the lights and achieve the energy saving purpose; and the ventilation systems, which could be turned off after the production time in order to reduce the energy consumption.
For the compressed air system, the load of the machines can be considered to reduce some times.
Under this pre-condition of not affecting the production processes, replace the light with low power ones to reduce the energy consumption.
Improve the efficiency of the machines and rearrange the operation of these machines in order to lower the energy need.
The energy saving calculation is done for lighting and ventilation and it is found that 105650 kwh and 53456 kwh electricity is saved per year.
The approximate calculations have been carried out in appendix, with the assumption of the factors i.e. operation time and power of the lights.
Difference in Energy demand
After analyzing several given data's the energy demand of the whole year is divided by using top down approach method into support process and production process for electricity and oil. The total electricity demand for each process is calculated by using the average value of the measurement given.
The energy saving calculation is done by some assumptions. The energy saving for lighting and ventilation are 281800 and 52000.when we compare to energy demand the electricity consumption is reduced in both the cases. The bar chart above shows the energy demand before and after saving.
This implies by changing the high power consuming lamps to energy efficient lamps and sensor lamps and decrease in operating hours leads to a vital change in energy consumption of the steel industry and large amount of money saving which can be used in efficient way.