Control of an adiabatic continuous reactor by feeding catalyst

1980 ◽  
Vol 45 (11) ◽  
pp. 2903-2918 ◽  
Author(s):  
Josef Horák ◽  
Zina Valášková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Reaction Temperature ◽  
Continuous Reactor ◽  
Control Element ◽  
Inlet Temperature ◽  
Switching Cycle ◽  
Point Temperature ◽  
Set Point ◽  
Constant Rate ◽  
Laboratory Reactor

Algorithms have been presented, analyzed and experimentally tested to stabilize the reaction temperature at constant inlet temperature and composition of the feed by controlled dispensing of the catalyst. The information for the control element is the course of the reaction temperature. If the temperature of the reaction mixture is below the set point, the catalyst is being fed into the reactor at a constant rate. If the reaction temperature is higher the catalyst dispenser is blocked; dispensing of the catalyst is not resumed until the set point temperature has been reached again. The amount of catalyst added is a function of the duration of the switching cycle. The effect has been discussed of the form of this function on the course of the switching cycle. The results have been tested experimentally on a laboratory reactor controlled in an unstable steady state.

Control of the adiabatic flow reactor by feeding the catalyst solution

1979 ◽  
Vol 44 (8) ◽  
pp. 2352-2365
Author(s):  
Josef Horák ◽  
Zina Sojková ◽  
František Jiráček
Keyword(s):  
Steady State ◽  
Constant Temperature ◽  
Reaction Temperature ◽  
Control Algorithm ◽  
Flow Reactor ◽  
Operating Temperature ◽  
Temperature Deviation ◽  
Adiabatic Flow ◽  
Dosing Frequency ◽  
Laboratory Reactor

Control algorithm of the operating temperature is described in the reactor, which is operated at constant temperature and composition of the inlet mixture. The temperature is controlled by dosing a constant volume of the catalyst solution. The dosing frequency is determined according to the reaction temperature (deviation of the temperature from the desired value and the sign of the derivative of temperature). The control algorithm has been verified experimentally for the laboratory reactor in unstable steady state.

Recent Studies of Tire Braking Performance

1973 ◽  
Vol 1 (2) ◽  
pp. 121-137 ◽  
Author(s):  
J. L. McCarty ◽  
T. J. W. Leland
Keyword(s):  
Steady State ◽  
Rapid Cycling ◽  
Single Cycle ◽  
Steering Angle ◽  
Slip Ratio ◽  
Factors Affecting ◽  
Braking Performance ◽  
Constant Rate

Abstract The results from recent studies of some factors affecting tire braking and cornering performance are presented together with a discussion of the possible application of these results to the design of aircraft braking systems. The first part of the paper is concerned with steady-state braking, that is, results from tests conducted at a constant slip ratio or steering angle or both. The second part deals with cyclic braking tests, both single cycle, where brakes are applied at a constant rate until wheel lockup is achieved, and rapid cycling of the brakes under control of a currently operational antiskid system.

Resistance to Outflow of Cerebrospinal Fluid Determined by Bolus Injection Technique and Constant Rate Steady State Infusion in Humans

Neurosurgery ◽  
1985 ◽  
Vol 16 (3) ◽  
pp. 336-340 ◽  
Author(s):  
Michael Kosteljanetz
Keyword(s):  
Cerebrospinal Fluid ◽  
Steady State ◽  
Bolus Injection ◽  
Point Of View ◽  
Injection Technique ◽  
Communicating Hydrocephalus ◽  
Constant Rate ◽  
High Degree ◽  
Infusion Technique

Abstract Two methods for the determination of resistance to the outflow of cerebrospinal fluid, the bolus injection technique and the constant rate steady state infusion technique, were compared. Thirty-two patients with a variety of intracranial diseases (usually communicating hydrocephalus) were studied. There was a high degree of correlation between the resistance values obtained with the two methods, but values based on the bolus injection technique were systematically and statistically significantly lower than those obtained with the constant rate infusion test. From a practical point of view. both methods were found to be applicable in a clinical setting.

Salivary Flow Induction by Buccal Permucosal Pilocarpine in Anesthetized Beagle Dogs

1992 ◽  
Vol 71 (11) ◽  
pp. 1762-1767 ◽  
Author(s):  
M.L. Weaver ◽  
J.M. Tanzer ◽  
P.A. Kramer
Keyword(s):  
Steady State ◽  
Salivary Flow ◽  
Salivary Secretion ◽  
Reversed Phase ◽  
Use Of Data ◽  
Constant Rate ◽  
First Pass ◽  
Steady State Plasma Concentration ◽  
Anesthetized Dogs ◽  
Drug Solution

We tested whether permucosal delivery of pilocarpine nitrate could be used to elicit significant salivary secretion. Pilocarpine (pKa 6.6 at 37°C) was applied as solutions (pHs 5.6, 6.6, 7.6; 15 mg/mL) to the buccal mucosa (2.8 cm2) of 6 anesthetized dogs. Saliva was collected continuously from cannulated submandibular and parotid ducts and blood sampled during and after drug administration. Plasma pilocarpine levels were determined by reversed-phase HPLC. Absorption rates were determined by use of data from separate zero-order intravenous infusions to the same dogs. Pilocarpine was buccally absorbed at a constant rate of 72.9 ± 38.5 μg/kg/h following its application at pH 7.6. At this pH of the drug solution, the time to appearance of pilocarpine in blood plasma was 0.31 ± 0.08 h, and the time to appearance of salivary flow was 0.86 ± 0.32 h. A threshold dose of 32.9 ± 7.5 ug/kg was required to induce secretion with the pH 7.6 drug, the steady-state plasma concentration was 28.9 ± 19.3 ng/mL, and the steady-state submandibular flow rate was 0.14 ± 0.11 mL/ min/gland pair. Salivary flow induction was symmetrical and reached levels as high as 0.35 mL/min/submandibular gland pair without apparent tachyphylaxis. Results at pHs 5.6, 6.6, and 7.6 were consistent with the hypothesis that pilocarpine is primarily absorbed as un-ionized drug. The data indicate that transmucosal delivery of pilocarpine, avoiding "first pass" hepatic loss, may hold promise for the treatment of xerostomia.

Determination of Safe Pumping Temperature for Waxy Crude Pipelines

2006 ◽  
Author(s):  
Jinjun Zhang ◽  
Jianlin Ding ◽  
Kang Xu ◽  
Huajun Fan
Keyword(s):  
Flow Rate ◽  
Pour Point ◽  
Heating Temperature ◽  
Safety Margin ◽  
Low Flow ◽  
Stable Operation ◽  
Inlet Temperature ◽  
New Approach ◽  
Point Temperature ◽  
Waxy Crude

Flow risk of a hot waxy crude pipeline mainly comes from restart failure, i.e. oil gelation resulted from prolonged pipeline shutdown, and unstable operation at low flow rate. Once the unstable operation happens, the friction loss of the pipeline increases with decreasing flow rate and finally flow may cease if treated improperly. To avoid these flow risks, the pumping temperature of the crude is generally required to be kept above a minimum allowable temperature, and conventionally the pour point temperature is taken. This practice is effective but quite rough. Obviously, to control the inlet temperature of a heating station at the pour point temperature implies different safety margin for winter and summer operation. For large throughput hot oil pipelines, reduction of the heating temperature even by a little bit may save a great amount of fuel. Therefore, how to save fuel while ensuring safe operation has been a valuable topic for long time. On the other hand, many factors impacting the flow safety are stochastic and with uncertainty, so analysis without considering this feature can hardly yield convincible results, though this has been the common case for many years. In this paper, by taking the stochastic feature into account, a Stable Operation Index (SOI) and a Pipeline Restartability Index (PRI) were proposed to assess the flow safety of a pipeline concerning the low-flowrate stable operation and restartability after shutdown. Combining these two indexes, a Pipeline Flow Safety Index (PFSI) was adopted to assess the flow risks of hot waxy crude pipelines. On this basis a new approach to quantitatively determining the safe pumping temperature was developed and illustrated by a case study. Encouraging results show that this new approach has the potential to replace the simple rule of pour point as a guide to determining the safe pumping temperature of waxy crude pipelines.

scholarly journals APLIKASI KONTROL PID PADA PROSES PENGOLAHAN AIR LAUT MENGGUNAKAN METODE REVERSE OSMOSIS BERBASIS DCS

JURNAL ELTEK ◽  
2019 ◽  
Vol 17 (2) ◽  
pp. 32
Author(s):  
Hariyadi Singgih Singgih ◽  
Subiyantoro Subiyantoro ◽  
Siswoko Siswoko
Keyword(s):  
Steady State ◽  
Reverse Osmosis ◽  
Rise Time ◽  
Delay Time ◽  
Settling Time ◽  
Set Point ◽  
Pressure Transmitter

Metode pemurnian air laut menggunakan pengaturan kecepatan motor dalam proses reverse osmosis sangat dibutuhkan, dikarenakan proses penyaringan dalam membran reverse osmosis membutuhkan tekanan yang sesuai dengan kemampuan membran. Selain itu juga dibutuhkan kontrol ketinggian air untuk mengotomatisasi tangki yang telah penuh dan mempertahankan ketinggian air. Solusi untuk mengurangi permasalahan ini digunakan DCS yang berfungsi untuk memonitor dan mengontrol plant dari jarak jauh, Metode kontrol yang digunakan pada DCS untuk menstabilkan set point menggunakan metode kontrol PID Ziegler-Nichols. Dalam penelitian ini dirancang mini plant kontrol ketinggian air dan tekanan menggunakan metode PID Ziegler-Nichols yang diimplementasikan pada DCS-PCS7. Sensor yang digunakan untuk ketinggian air adalah HC-SR04, dan untuk sensor tekanan menggunakan pressure transmitter. Dengan aplikasi kontrol PID diperoleh kestabilan set point dengan parameter kontrol ketinggian air : Kp=134.4, Ti=0 dan Td=1. Waktu untuk mencapai set point 120 detik dan  error steady state sebesar 0.94% tanpa gangguan. Untuk parameter Kontrol tekanan air sebesar: Kp=3, Ti=0 dan Td=1.375 dan Delay time = 4s, Rise time = 7s, Settling time = 25s, Osilasi output PID rendah, Error steady state = 1.03% tanpa gangguan.    

scholarly journals Thermal behavior of premises equipped with different alveolar structures

2015 ◽  
Vol 19 (3) ◽  
pp. 929-938
Author(s):  
Nour Lajimi ◽  
Noureddine Boukadida
Keyword(s):  
Heat Transfer ◽  
Thermal Behavior ◽  
Air Temperature ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Point Temperature ◽  
Set Point ◽  
Alveolar Structure ◽  
Vertical Walls

This paper presents a numerical study of local thermal behavior. Vertical walls are equipped with alveolar structure and/or simple glazing in East, South and West frontages. Local temperature is assumed to be variable with time or imposed at set point temperature. Results principally show that the simple glazing number has a sensitive effect on convection heat transfer and interior air temperature. They also show that the diode effect is more sensitive in winter. The effect of alveolar structure and simple glazing on the power heating in case with set point temperature is also brought out.

scholarly journals Pengkondisian Suhu Air Perebusan Kedelai Pada Pembuatan Tempe Dengan Metode PID

2021 ◽  
Vol 6 (3) ◽  
pp. 40
Author(s):  
Siroju Insan ◽  
Tarmukan Tarmukan ◽  
Mila Fauziyah
Keyword(s):  
Steady State ◽  
Rise Time ◽  
Delay Time ◽  
Set Point

Tempe merupakan makanan tradisional yangpopuler di Indonesia. Salah satu bahan dari tempe adalahkacang kedelai. Cara pembuatannya terdiri dari pengupasan,perebusan, inokulasi, dan peragian. Proses perebusandilakukan dengan merebus kedelai ke dalam air dengan suhutertentu. Tujuan perebusan ialah sebagai proses hidrasi agarkedelai dapat menyerap air sebanyak mungkin. Prosesperebusan yang umum digunakan saat ini masih manualsehingga hasilnya kurang maksimal. Hal ini karena suhu dariproses perebusan secara manual tidak stabil. Oleh karena itu,penelitian ini dilakukan untuk mengontrol suhu pada prosesperebusan agar tetap stabil. Penelitian ini menggunakanmetode kontrol PID untuk mengatur suhu dengan caramengatur besar bukaan valve gas LPG pada tungku. Suhu daritungku dideteksi menggunakan sensor suhu RTD PT100 untukdibandingkan dengan nilai set point. Dengan menggunakanmetode Ziegler-Nichols didapatkan nilai penguatan Kp=50.64,Ki=1.266, dan Kd= 506.4. Dari nilai konstanta Kp, Ki, dan Kdtersebut diperoleh respon output dengan nilai nilaiOvershoot=0.4%, delay time=7.19, rise time=14.38, settlingtime=15.06, error steady-state (atas)=0.67%, dan errorsteady-state (bawah)=1.78%.

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