PENGARUH PENAMBAHAN BIOAKTIVATOR EM-4 TERHADAP PRODUKSI BIOGAS DARI LIMBAH CAIR INDUSTRI TAHU

Tofu industrial waste is generally divided into two forms of waste, namely solid waste and liquid waste. The liquid waste of the tofu industry contains organic material that can be decomposed anaerobically into methane gas (CH4), other gases, and water which is commonly called biogas. One of the potential biocatalysts as a source of microorganisms in biogas production is Effective Microorganisms 4 (EM-4). This research was conducted by adding EM-4 with a concentration of 0.5%; 1%; and without EM-4 into 15 liters of tofu liquid waste in the digester for fermentation for 7 days. Observation of the pressure on the manometer seen from the difference in the height of the liquid manometer U and the combustion process was carried out on the 7th day (constant pressure). The maximum pressure of biogas for 7 days at 1% EM4 of 927,864 kg/m.s2 produces a blue flame, has an unpleasant odor, does not cause smoke with a fire height of 12,602 mm. So it can be concluded that the greater concentration of EM-4 used, the greater the pressure of biogas and fire

Tests of changes in the resistance of heating water flow in the home heating system

The article presents the results of experimental research on the change of resistance of heating water flow in the home heating system under the influence of boiler work configuration changes. For the tests was used the research object in the form of a solid fuel heating boiler with automatic fuel feeding. The research facility was installed in an open-type heating network designed to reproduce the layout of the house heating system. During the tests, boiler operation was simulated for a few selected thermal loads most often found in individual heating. During the tests, the boiler worked with the power of: 10%, 30%, 50%, 80% and 100% of nominal boiler power. For each of the selected options, a series of flow resistance measurements were made using a U-type liquid manometer tube made by researchers. The obtained results of experimental research can be used as an aid in the case of designing home heating networks equipped with a solid fuel boiler.

Construction and Leakage Detection of a Dome-Type Biogas Digester in a Village at Abuja, Nigeria

This work presents construction and leakage detection of dome-type biogas digester. The constructed biogas digester with local materials is rated at 10m3 capacity. The biogas digester foundation, cylindrical wall and dome vault were about 10 cm thick and made of high strength concrete in kilogram at ratio of cement, sharp sand and aggregate of 12 mm size as 111:1:1.2. The constructed biogas digester was pressure tested by using liquid manometer. The pressure gauge level difference of 48 cm (4.7 KN/m2) was obtained, which later dropped to less than 20 cm (1.96 KN/m2)indicating presence of leakage in the biogas digester. Cracks in the biogas digester were located after a careful examination at the cylindrical wall and dome top, which were scaled and sealed with wet cement. The pressure test wasagain conducted and yielded pressure gauge level difference of 60 cm(5.88 KN/m2), without dropping for over 20 minutes, which implies no leakage in the biogas digester.

Research about a High-Sensitivity Automatic Liquid Manometer

An automatic liquid manometer which operates on the basis of a position-detecting system is described. A slanting laser beam is directed to the meniscus of liquid in a glass tube manometer without a float and is reflected by the meniscus. The reflected spotlight is focused on a position-sensitive detector (PSD) through a lens. The application of external pressure to the manometer causes the position of the meniscus to change, and the pressure can be gotten indirectly by this position. The relationship of the output of PSD to the displacement of meniscus was investigated, and the fuzzy control rules were determined to make the meniscus back to its original position fast and stable. The system has been tested with good results.

Study on Generation Mechanisms of Abnormal Vibrations of Flow Dynamic Conveyers

The FDC (Flow Dynamics Conveyer) has often been used in power plants and iron works because of its superiority in quietness compared with a roller type conveyer. Moreover, it is excellent in low noise and low power. The FDC consists of a trough and a belt, and the air is supplied from numerous holes provided on the trough. However, large vibrations occur when the flow rate reaches a certain value. This abnormal vibration is defined to be a self-excited vibration caused by leakage flow. It is well known that abnormal vibrations occur when the flow channel spreads out at the edges. The purpose of this study is to clarify the generation mechanism of the abnormal vibration. The experimental setup is made of steel. The trough is made of a thick plate and the belt is made of a thin plate with a thickness of 1.2mm. The air is supplied by a blower and the flow rate is adjusted by a ball valve. The flow rate is measured by a venturi tube and a liquid manometer. The loads are given by piling thick steels one by one with a weight of 1kg. The vibration of the belt center is measured by a laser displacement meter and the data are processed by a FFT analyzer. The experiment was carried out to examine the effects of various parameters such as the taper angle θ, the floating amount H generated by loads and flow rates on abnormal vibrations. Firstly, vibrations of the belt were obtained by changing loads and flow rates. When the flow rate is constant, the taper angle θ increases and the floating height of the belt H decreases with increasing loads. The area of abnormal vibrations could be obtained in the θ—H plane. Secondarily, the damping coefficients were obtained based on the free vibration method by changing loads and flow rates when abnormal vibrations did not occur. As a result, it was found that the damping ability decreases with an increase in the taper angle and a decrease in the floating height. Furthermore it was clarified that the abnormal vibrations occur for θ > αH (α: constant value).