Oxide formation of transformation-induced plasticity-aided steel during dew-point control

2007 ◽  
Vol 57 (2) ◽  
pp. 113-116 ◽  
Author(s):  
Xiang Shu Li ◽  
Sung-Il Baek ◽  
Chang-Seok Oh ◽  
Sung-Joon Kim ◽  
Young-Woon Kim
Keyword(s):  
Dew Point ◽  
Oxide Formation ◽  
Transformation Induced Plasticity ◽  
Point Control

The design of equipment for producing accurate control of artificial aerial environments at low cost

1959 ◽  
Vol 53 (2) ◽  
pp. 198-208 ◽  
Author(s):  
G. C. Evans
Keyword(s):  
Cooling System ◽  
Low Cost ◽  
Thermal Capacity ◽  
Dew Point ◽  
Atmospheric Environment ◽  
Air Supply ◽  
Point Control ◽  
Degree Of Control ◽  
Time Of Year ◽  
Field Experimentation

An account is given of the considerations which have been found in practice to govern the design of a small cabinet for growing plants under closely controlled conditions of atmospheric environment. Starting with questions of size, shape and material, the connexion between size of chamber and type of illumination is considered, followed by general policy on air supply. The main outlines of design having been laid down in this way, the various environmental factors to be controlled are reviewed. These include: (a) composition of the air, with particular reference to carbon dioxide; (b) light intensity. Various possible sources are reviewed, and the difficulties of imitating natural conditions of illumination are discussed, together with methods of measuring the illumination and checking for stability; (c) temperature. The degree of control needed for various purposes is considered, particularly in connexion with control of humidity, followed by systems of control, and the most advantageous arrangements for them. The cycle of operations of a control system is considered in some detail, and division of the system into a small relay-operated heater and a background heating or cooling system is advocated; (d) humidity. A similar division between background and relay-operated humidifiers is also advisable, and methods of achieving this are outlined. Dew-point control is shown to be most suitable for the background humidity, while a hot wick of low thermal capacity suffices for the relay-operated device. Finally, the principal uses of such cabinets are dealt with: (a) as adjuncts to field experimentation; (b) for work on plant pathology; (c) for producing standard plant material at any time of year; and rough estimates of running costs are given.

scholarly journals PSIV-11 Description of a novel Calorimetric unit to determine net energy in group housed pigs

2019 ◽  
Vol 97 (Supplement_2) ◽  
pp. 178-179
Author(s):  
Cristhiam J Muñoz ◽  
Hans H Stein
Keyword(s):  
Dew Point ◽  
Net Energy ◽  
Finishing Pigs ◽  
Line System ◽  
University Of Illinois ◽  
Air Supply ◽  
Oxygen Analyzer ◽  
Point Control ◽  
The University ◽  
Black Mountain

Abstract The Swine Calorimeter Unit (SCU) is being developed at the University of Illinois at Urbana-Champaign. The objective of the SCU unit is to be able to determine net energy (NE) of diets and ingredients fed on an ad-libitum basis to group-housed pigs in all phases of production. The SCU allows for calculating NE based on the indirect calorimetry procedure. There are 6 calorimetry chambers in the SCU. Each chamber is made air-tight by means of a gasketed surface, measures 1.8 × 2.1 × 2.7 m, has fully slatted floors, and a volume of 10.2 m3, with capacity to hold 4 to 10 growing-finishing pigs depending on size. There are manure screens and urine pans under the slatted floors. Each chamber is equipped with a fresh air supply system (Fantech, Lenexa, KS, and Accutrol LLC, Monroe, CT). Humidity and temperature in each chamber is controlled by a regulator unit (Parameter, Black Mountain, NC). The precision for maintenance of the temperature can be controlled with an accuracy of ± 0.1°C and relative humidity (RH) ±0.5%. These levels of precision are ensured by the use of a dew point control system. To measure the gas exchange in the chambers, the Classic Line system developed by Sable Systems International is used (Sable System International, North Las Vegas, NV). The air subsample first enters the methane analyzer, then the CO2 analyzer, and as the last step the oxygen analyzer. The gas analyzers provide readings in percentage units with high resolution (0.00001 to 0.01%) depending on gas concentrations. Those values are obtained in a determined period of time to be able to calculate total heat production from each chamber. Operation of the SCU will start in January 2019, and the initial objectives include comparisons of net energy in individually housed and group housed pigs. Figure1. Schematic of the Calorimeter chamber and its sub-systems. http://www.conferenceharvester.com/

scholarly journals Studi Penambahan Etilena Glikol dalam Menghambat Pembentukan Metana Hidrat pada Proses Pemurnian Gas Alam

2020 ◽  
Vol 14 (2) ◽  
pp. 198
Author(s):  
Muslikhin Hidayat ◽  
Danang Tri Hartanto ◽  
Muhammad Mufti Azis ◽  
Sutijan Sutijan
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Natural Gas ◽  
Operating Temperature ◽  
Hydrate Formation ◽  
Control Unit ◽  
Dew Point ◽  
Heavy Hydrocarbon ◽  
Aspen Hysys ◽  
Point Control

The gas processing facilities are designed to significantly reduce the impurities such as water vapor, heavy hydrocarbon, carbon dioxide, carbonyl sulfide (COS), benzene-toluene-xylene (BTX), mercaptane, and the sulfur compounds. A small amount of those compounds in natural gas is not preferable since they disturb the next processes.  It was proposed to decrease natural gas's operating temperature to -20 ⁰F to remove the impurities from natural gas. The decrease of the natural gas's operating temperature has some consequences to the gas mixers such as hydrate formation at high pressure and low temperature, solidification of ethylene glycol (EG) solution, and the icing of the surface due to low temperature on the surface of chiller (three constraints). The Aspen Hysys 8.8 was used to obtain the suitable flowrate and concentration of the EG solution injected into the natural gas. Peng-Robinson's model was considered the most appropriate thermodynamic property model, and thus it has been applied for this research. The calculation results showed that the EG solution injection would reduce the hydrate formation due to water vapor absorption in the natural gas by EG. The EG solution's flowrate and concentration were varied from 20,000-2,000,000 lb/hr and 80-90 wt.%. When the separation was carried out at the operating temperature of -20 ⁰F, the EG solution's concentration fulfilling the requirement was of 80-84 wt.% with the flowrate of EG solution of 900,000 lb/hr and even more. This amount is not operable. More focused investigation was done for the variation of the operating temperature. Increasing operating temperature significantly reduced the flowrate of EG solution to about 200,000 lb/hr. An alternative process was proposed by focusing on two concentration cases of 80 and 85 % of weight at the low flow rate of EG solution, respectively. These simulations were intended to predict impurities' concentration in the effluent of Dew Point Control Unit (DPCU). The concentrations of BTX, heavy hydrocarbon, mercaptane, and COS flowing out of DPCU were 428.1 ppm, 378.4 ppm, 104 ppm, and 13.3 ppm, respectively. The concentrations of BTX and heavy hydrocarbon are greater than the minimum standard required. It is needed to install an absorber to absorb BTX and heavy hydrocarbon. However, the absorber capacity will be much smaller than if the temperature of natural gas is not decreased and not injected by the EG solution.Keywords: DPCU gas treatment; ethylene glycol solution; hydrate formation; simulationA B S T R A KUnit pengolahan gas dirancang untuk mengurangi sebagian besar senyawa pengotor seperti uap air, hidrokarbon berat, karbon dioksida, karbonil sulfida (COS), benzena-toluena-xilena (BTX), merkaptan, dan senyawa sulfur lainnya. Keberadaan senyawa tersebut dalam gas alam berbahaya karena mengganggu proses selanjutnya walaupun dalam jumlah sedikit. Untuk membersihkan gas alam dari senyawa pengotor, maka suhu operasi gas diturunkan menjadi -20 °F. Penurunan suhu operasi gas dapat menyebabkan pembentukan hidrat pada tekanan tinggi dan suhu rendah, pembekuan larutan etilena glikol (EG), dan pembentukan lapisan es pada permukaan chiller. Aspen Hysys 8.8 digunakan untuk memperkirakan berapa kecepatan alir dan konsentrasi larutan EG yang diinjeksikan ke gas alam. Model Peng-Robinson adalah model termodinamika yang diterapkan untuk penelitian ini. Hasil simulasi menunjukkan bahwa injeksi larutan EG dapat mengurangi pembentukan hidrat karena larutan EG menyerap uap air dalam gas alam. Kecepatan alir dan konsentrasi larutan EG divariasikan dari 20.000-2.000.000 lb/jam dan 80-90 % (%b/b). Saat pemisahan dilakukan pada suhu operasi -20 °F, konsentrasi larutan EG yang memenuhi syarat adalah 80-84 % (%b/b) dengan kecepatan alir larutan EG 900.000 lb/jam atau lebih. Jumlah ini sangat banyak dan kurang layak untuk dioperasikan. Penelitian difokuskan pada variasi suhu operasi. Peningkatan suhu operasi diikuti dengan pengurangan kecepatan aliran larutan EG secara signifikan yaitu menjadi sekitar 200.000 lb/jam. Alternatif proses diusulkan dengan berfokus pada penggunaan kecepatan alir larutan EG yang rendah dengan konsentrasi larutan EG sebesar 80 dan 85 % (%b/b). Simulasi dapat memprediksi konsentrasi pengotor yang keluar dari Dew Point Control Unit (DPCU). Konsentrasi BTX, hidrokarbon berat, merkaptan, dan COS yang mengalir keluar dari DPCU berturut-turut adalah 428,1 ppm, 378,4 ppm, 104 ppm, dan 13,3 ppm. Konsentrasi BTX dan hidrokarbon berat tersebut lebih besar dari standar minimum yang disyaratkan. Oleh karena itu, diperlukan pemasangan absorber untuk menyerap BTX dan hidrokarbon berat. Namun, kapasitas absorber akan jauh lebih kecil apabila dibandingkan dengan kondisi tanpa menurunkan suhu dan menginjeksikan oleh larutan EG.Kata kunci: DPCU; larutan etilena glikol; pembentukan hidrat; simulasi 

scholarly journals Operational Experience With the World’s First Offshore Turboexpanders With Magnetic Bearings

1996 ◽  
Author(s):  
Harald Underbakke
Keyword(s):  
Magnetic Bearings ◽  
Dew Point ◽  
First Year ◽  
Operational Experience ◽  
Buffer Gas ◽  
Electrical Systems ◽  
The North ◽  
The North Sea ◽  
Point Control ◽  
Process Interaction

The first offshore turboexpanders with magnetic bearings have now been in operation on the Sleipner A platform in the North Sea since October 1993. Four machines are installed, each at 3.3 MW, running at 16,500 RPM for natural gas dew point control. During the commissioning phase and the first year of operation a number of problems were discovered, mainly due to the application of magnetic bearings in a new environment, and some unexpected bearing / process interaction phenomenon. To solve the problems it was necessary to do modifications to electrical systems, mechanical parts, operational procedures and buffer gas systems. After a 1.5 year period of modifications, all 4 machines are now running with 99 % availability.

scholarly journals Perbandingan Performa Refrigeran Propana dan Amonia pada Siklus Refrigerasi Dew Point Control Unit (DPCU)

2021 ◽  
Vol 15 (1) ◽  
pp. 94
Author(s):  
Mochammad Syahrir Isdiawan ◽  
Aditya Nurfebriartanto ◽  
Rafitri Rusmala
Keyword(s):  
Low Temperature ◽  
Control Unit ◽  
Dew Point ◽  
Simple Cycle ◽  
Refrigeration Cycle ◽  
Evaporator Temperature ◽  
Gas Condensation ◽  
Aspen Hysys ◽  
Condenser Temperature ◽  
Point Control

Natural gas, that has been processed and met certain specifications, is sent to consumers through pipeline. Gas condensation within the pipeline should be avoided because it has negative impacts. Hydrocarbon dew point is a measure of the easiness of gas condensation. To meet the hydrocarbon dew point, heavy hydrocarbon should be extracted in dew point control unit (DPCU). The extraction is done by gas cooling in gas chiller followed by separating the liquid formed in low temperature separator (LTS). The gas chiller functions as an evaporator in the DPCU refrigeration cycle. Propane is a common refrigerant in the DPCU. In addition, ammonia is also a potential refrigerant due to its normal boiling point being close to the hydrocarbon dew point. Refrigeration cycle performance depends on evaporator temperature, condensor temperature, and the inherent pressure-enthalpy (PH) characteristic of the selected refrigerant. This study aimed to compare the performance from ammonia and propane against the change of evaporator and condenser temperature. This study was a dry research using Aspen Hysys V11.0 simulation software (academic license). The refrigeration cycle was a simple cycle with fixed variables in the form of evaporator load, saturated liquid at outlet condenser, and saturated vapour at outlet evaporator. This study indicated that at the same evaporator load, evaporator temperature, and condenser temperature, ammonia refrigeration cycle was better than the propane because coefficient of performance (COP) of ammonia was higher than propane. This study also modeled COP changes of propane and ammonia as mathematical equation. Quantitatively, it appeared that COP of propane was more sensitive than ammonia against both evaporator and condenser temperature changes.Keywords: ammonia; condenser; evaporator; propane; refrigeration cycle; simulationA B S T R A KGas alam yang telah diolah dan sesuai spesifikasinya dikirim ke konsumen melalui pipa. Kondensasi gas dalam pipa harus dihindari karena menimbulkan dampak negatif. Titik embun hidrokarbon menjadi ukuran kemudahan proses kondensasi gas. Untuk mencapai titik embun hidrokarbon yang diinginkan, maka hidrokarbon berat harus diekstraksi di dew point control unit (DPCU). Ekstraksi dilakukan dengan cara mendinginkan gas di gas chiller lalu memisahkan cairan yang terbentuk di low temperature separator (LTS). Gas chiller tersebut berfungsi sebagai evaporator pada siklus refrigerasi DPCU. Propana adalah refrigeran yang umum digunakan di DPCU. Selain itu, amonia juga menjadi refrigeran yang potensial karena kedekatan titik didih normalnya terhadap titik embun hidrokarbon yang diinginkan. Performa siklus refrigerasi dipengaruhi oleh temperatur evaporator, temperatur kondensor, dan karakteristik tekanan-entalpi (PH) yang melekat pada refrigeran yang dipilih. Penelitian ini bertujuan untuk membandingkan performa siklus refrigerasi propana dan amonia terhadap perubahan temperatur evaporator dan kondensor. Penelitian ini merupakan penelitian kering yang menggunakan perangkat lunak simulasi Aspen Hysys V11.0 (lisensi akademik). Siklus refrigerasi yang digunakan adalah simple cycle dengan variabel tetap berupa beban evaporator, kondisi cair jenuh outlet kondensor, dan kondisi uap jenuh outlet evaporator. Hasil penelitian ini menunjukkan bahwa pada beban evaporator, temperatur evaporator, dan temperatur kondensor yang sama, maka siklus refrigerasi amonia lebih baik dari propana karena COP amonia lebih tinggi dari propana. Penelitian ini juga memodelkan nilai COP propana dan amonia sebagai persamaan matematika. Secara kuantitatif, terlihat bahwa COP amonia lebih stabil dari propana terhadap perubahan temperatur evaporator dan kondensor.Kata kunci: amonia; evaporator; kondensor; propana; siklus refrigerasi; simulasi

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