Muara Tawar combined cycle power plant consists of three gas turbines, three heat recovery steam generators and one steam turbine. An update of gas turbine blades in 2016 effected on decreasing gas turbine flue gas temperature by 8°C up to 20°C. This study aims to analyse the effect of decreasing gas turbine flue gas temperature on output power of steam turbine. The output power of steam turbines is simulated by using Cycle-Tempo software, based on combined cycle heat balance. Variations of decreasing gas turbine flue gas temperature are configured on three gas turbines, two gas turbines and one gas turbine. The result shows that every 2°C decrease in flue gas temperature of three gas turbines will decrease output power of steam turbines by 0.787%. Whereas if decrease in flue gas temperature of two gas turbines and one gas turbine will decrease output power of steam turbine by 0.532% and 0.267% respectively. Meanwhile, the simulation results show that the decrease in the output power of the steam turbine after update of the gas turbine blades, 72.8% is caused by a decrease in gas turbine flue gas temperature and 27.2% by other factors.

The most popular building material today is concrete. Concrete is used for buildings, industrial structures, bridges, railroad sleepers, roads, dams and more. Along with the development of concrete technology is increasingly developing and innovative so as to achieve better characteristics, cheaper prices and environmentally friendly. In the early days of the development of concrete it is explained to us about the origin from ancient times to civilization to the present century of its development. In current developments, concrete already has a very high compressive strength up to 200-800 MPa, this is also called Ultra Hight Concrete (UHC). It is developed by the Reactive Powder concrete (RPC) method. Where in the research conducted, the manufacture of reactive material, namely Reactive Powder concrete (RPC) was given with a compressive strength of up to 52 MPa. The components of the RPC mixture consist of cement, fine aggregate, silica fume, superplasticizer and water. To produce a compressive strength of 52 MPa, the composition of the mixture used previous research. Detailed RPC concrete mix proportions are given in this study. Preparation and testing of materials are made in the laboratory of the Faculty of Civil Engineering in Untan. The results that will be obtained are the physical and mechanical properties of RPC Concrete. As previously explained, the manufacture of RPC concrete requires basic ingredients that include cement, fine aggregate, silica fume, superplasticizer and water mixed together. Of course, with basic ingredients with good and correct composition, the physical and mechanical properties of RPC concrete will reach the planned quality. Cement sold in the market today has PPC and PCC types. Therefore, the cement which is a binder of powder materials into a solid one plays a very important role in the formation of the best physical and mechanical properties of RPC concrete. With cement as a binding material, it is certain that the strength of RPC concrete is determined by the binding capacity of the type of cement to be used, thus RPC concrete will be obtained according to the planned quality of the plan. From the cement brands on the Indonesian market consisting of PPC and PCC cement types, it can be concluded that one of the cements using the PCC type cement brand has better physical and mechanical properties than the PPC type cement brand. And all brands of cement with PCC type produce compressive strength > 52 MPa. So, in the manufacture of RPC concrete it is recommended to use a cement brand with PCC type.

A closed cooling water system is one of the systems contained in gas turbines. The main function of this system is to cool the lubricating oil and winding generator. Decreased performance of closed cooling water system can cause the gas turbine protection system to be active and cause the gas turbine trip. The study began with data collection, both design data for the heat exchanger cooler fan and operating data from the closed cooling water system on the gas turbine. An experiment was carried out by varying the blade pitch angle cooler fan to measure the work parameters in the field and analyzing the results of these measurements against the performance of the heat exchanger cooler fan. Variations of blade pitch angle cooler fan were done by limiting the working parameters of the cooling fan motor. The result of this study was an increase in the blade pitch angle cooler fan results in an increase in the flow rate of the cooler fan, this also affected the heat transfer rate of the heat exchanger cooler fan which grew when the blade pitch angle cooler fan was raised. The increase of blade pitch angle cooler fan also resulted in a decrease in the temperature of closed cooling water on the heat exchanger cooler fan outlet.

No abstract

Intense competition in today's industrial world requires companies to keep abreast of developments. The more years, higher the need for labor costs. To reduce high production costs, one step is to cut existing labor. By cutting the number of workers, the workload that will be borne by workers will also increase. PT. SPINDO, is a manufacturing company engaged in the production of the steel pipe industry. To expand market reach, a breakthrough was made to open a new depot located in the city of Samarinda. At the beginning of the opening along with the Covid-19 outbreak, market demand was minimal. The impact on the work load in the depot is also low. The Full Time Equivalent method is a calculation process that uses working time as a reference in determining workload. In this research, the workload value most of the employees at PT. SPINDO Depo Samarinda is included in the underload category. So that man power planning is needed by cutting the number of existing employees to balance work load and the number of manpower. After the manpower planning was carried  out, the work load that was previously unbalanced was balanced because the workload had been distributed to the employees.