Reactor advanced loop

Fig. 1.26 Tie Buss loop reactor. (From http //www.buss-t.com/up/flle5/PDF5 RT/Brochure RT Advanced Loop Reactor operating principle.pdf. 2009 Buss ChemTech AG).

F. Baler, The Advanced Buss Loop Reactor Diss. ETH No. 14351. 

Baier, F.O. Mass Transfer Characterization of a Novel Gas-Liquid Contractor. The Advanced Bus Loop Reactor Ph.D. thesis, Swiss Federation Institute-ETH Zurich, Switzerland, 2002. 

Blenke, H. (1979), Loop reactors, Advances in Biochemical Engineering, 13 121-214. 

S.4.2.2 The Advanced Buss Loop Reactor (ABLR) This reactor has been described in detail by Baier (2(X)1). This unit includes two major modifications of the previous version termed BLR . A shorter venturi without a diffuser or draft tube has replaced the relatively long prior design. In this form, the combination of primary... 

Equipment used Advanced Buss Loop Reactor presumably without any dip of the diffuser in the dispersion in the holding vessel. 

Baier FO. (2001) Mass transfer characteristics of a novel gas-liquid contactor, the Advanced Buss Loop Reactor. Doctoral thesis. Swiss Federal Institute of Technology Zurich. 

Opre Z. (2009) Benefits of the advanced BUSS Loop reactor technology by removal of by-products through the gas circulation system http //www.dechema.de/index.php id=ll 6220 tagung=9 file=7717 site=achema2009 lang=en path=l%25252C79095. Accessed December, 2011. 

Rapsodie and EBR-II are respectively MOX-fiieled loop-type, and metal-fueled pool-type, reactors. Thus these dramatic transient experiments have shown that advanced fast reactors can be designed with passive safety properties. 

Chikazawa, Y., Kotake, S., Sawada, S., 2011. Comparison of advanced fast reactor pool and loop configurations from the viewpoint of construction cost. Nuclear Engineering and Design 241, 378—385. 

Kotake, S., Sakamoto, Y., Mihara, T., Kubo, S., Uto, N., Kamishima, Y., Aoto, K., Toda, M., 2010. Development of advanced loop-t)fpe fast reactor in Japan. Nuclear Technology 170, 133-147. 

With a purpose of probing a commercially feasible fast reactor system, a feasibility study on commercialized fast reactor cycle systems (FS) was initiated in 1999 (Aizawa, 2001). In the FS, survey studies were made to identify the most promising concept among various systems such as sodium-cooled fast reactors, gas-cooled fast reactors, heavy metal-cooled fast reactors (lead-cooled fast reactors and lead-bismuth cooled fast reactors), and water-cooled fast reactors with various fuels types such as oxide, nitride, and metal fuels. The FS concluded to select an advanced loop-type SFR with mixed oxide fuel named Japan sodium-cooled fast reactor (JSFR Kotake et al., 2005). 

The recommended core exit pressure of 0.2 MPa is attainable by assuming the uppermost elevation of the coolant loops is at atmospheric pressure, with the static head of the coolant loops, elevated about 10 m above the core, providing the difference. The core inlet temperature, 325 K, is achievable based on Advanced Test Reactor experience, and the core outlet temperature, 347 K, is based on the core geometry of a commercial PWR. The average core fuel rod heat flux... 

Regulatory Control For most batch processes, the discrete logic reqmrements overshadow the continuous control requirements. For many batch processes, the continuous control can be provided by simple loops for flow, pressure, level, and temperature. However, very sophisticated advanced control techniques are occasionally apphed. As temperature control is especially critical in reactors, the simple feedback approach is replaced by model-based strategies that rival if not exceed the sophistication of advanced control loops in continuous plants. 

To maximize the unit s profit, one must operate the unit simultaneously against as many constraints as possible. Examples of these constraints are limits on the air blower, the wet gas compresst>r. reactor/regenerator temperatures, slide valve differentials, etc. The conventional regulatory controllers work only one loop at a time and they do not talk to one another. A skilled operator can push the unit against more than one constraint at a time, but the constraints change often. To operate closer to multiple constraints, a number of refiners have installed an advanced process control (APC) package either within their DCS or in a host computer. 

The PBL reactor considered in the present study is a typical batch process and the open-loop test is inadequate to identify the process. We employed a closed-loop subspace identification method. This method identifies the linear state-space model using high order ARX model. To apply the linear system identification method to the PBL reactor, we first divide a single batch into several sections according to the injection time of initiators, changes of the reactant temperature and changes of the setpoint profile, etc. Each section is assumed to be linear. The initial state values for each section should be computed in advance. The linear state models obtained for each section were evaluated through numerical simulations. 

Temperature profiles versus time were taken for different positions at the reactor tube [19]. The maximum rise in temperature was about 23 °C. Improved pressure control was exerted by using advanced pressure control electronics [19]. In the regions of large temperature increase, pressure was slightly fluctuating this effect diminished downstream. By deliberately changing pressure (in a loop), the temperature response followed immediately [19]. This proved that control of pressure is crucial for obtaining stable temperature baselines. 

The equipment used in the unit operations is complex and microprocessor controlled to allow the execution of process recipes. However, advanced control schemes are rarely invoked. The microprocessor adjusts set points according to some sequence of steps defined by the equipment manufacturer or the process operator. Flows, pressures, and temperatures are regulated independently by off-the-shelf proportional-integral-derivative controllers, even though the control loops interact strongly. For example, fluorine concentration, substrate temperature, reactor pressure, and plasma power all influence silicon etch rates and uniformity, but they are typically controlled independently. 

The practical implementation of the above policies is not necessarily as straightforward as solving the above equations. As can be deduced from Equations 6.70-6.76, Pjjjj is a function of the propagation rate coefficients, the monomer concentrations, and most importantly, the total radical concentration. Hence, to precalculate the optimal monomer feed rates, the radical concentration must be specified in advance and kept constant via an initiator feed policy and/or a heat production policy. This is especially important considering that a constant radical concentration is not a typical polymer production reality. This raises the notion that one could increase the reactor temperature or the initiator concentration over time to manipulate the radical concentration rather than manipulate the monomer feed flowrates, that is, keep P j constant for simpler pump operation. Furthermore, these semibatch policies provide the open-loop or off-line optimal feed rates required to produce a constant composition product. The online or closed-loop implementation of these policies necessitates a consideration of online sensors for monomer... 

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