Autoclave typical system

Carbonate leaching under ambient conditions is extremely slow with poor recoveries. Therefore, the ore is typically leached in an autoclave with air providing most of the needed oxygen. The leach Hquor is separated from the soHd in a countercurrent—decantation system of thickeners, and the uranium is precipitated from the clarified sodium carbonate solution with addition of sodium hydroxide (eq. 9) (23). 

Two resin systems based on this chemical concept are commercially available from Shell Chemical Company/Technochemie under the COMPIMIDE trademark COMPIMIDE 183 (34) [98723-11-2], for use in printed circuit boards, and COMPIMIDE 796 [106856-59-1], as a resin for low pressure autoclave mol ding (35). Typical properties of COMPIMIDE 183 glass fabric—PCB laminates are provided in Table 8. COMPIMIDE 183 offers a combination of advantageous properties, such as a high glass transition temperature, low expansion coefficient, and flame resistance without bromine compound additives. 

The most common heterogeneous catalytic reaction is hydrogenation. Most laboratory hydrogenations are done on liquid or solid substrates and usually in solution with a slurried catalyst. Therefore the most common batch reactor is a stirred vessel, usually a stirred autoclave (see Figure 2.1.1 for a typical example). In this system a gaseous compound, like hydrogen, must react at elevated pressure to accelerate the process. 

For the synthesis of MoS-L, typically sodium molybdate was dissolved in distilled water to form solution A and a surfactant (QH NBr) was also dissolved in distilled water under mild heating and stirring to form solution B. Solutions A and B were then mixed and to the mixture was added thioacetamide (CH3CSNH2) under stirring. After complete dissolution of thioacetamide, the final reaction mixture with an empirical composition of NajMoCVxCnHj NBnBJCl CSNH TOl O (x=2.0-4.0) was sealed in a PTFE-lined stainless steel autoclave and heated at 85 °C for 6 days. The solid product with a golden-yellow color was recoved from the reaction system by filtration, washed copiously with distilled water and ethanol and dried at ambient temperature. 

Typically, the reactor was loaded with 50 mg of 5% PVAI2O3 catalyst (prereduced 2 hours at 400°C under H2), and 10 mg dihydrocinchonidine (HCd). 10 ml ethyl pyruvate (freshly distilled) and 20 ml toluene (Fluka puriss) were then added to the reactor. The autoclave was sealed and the system was purged with argon (2.0 MPa) 5 times while stirring. 

The reactions were carried out in a 0.1 liter stirred autoclave operating in a batch mode and equipped with a system for sampling of liquid during the reaction. The autoclave was charged with the substrate together with solvent and the freshly calcinated zeolite (calcination overnight at 500°C or 400°C in air, prior to use) and then heated to the desired temperature. The amounts of zeolite and of distilled water depend both on the nature and the concentration of substrate. Samples were withdrawn periodically and analyzed by g.l.c..Two typical examples are described below ... 

The autoclave reactor is a small cylindrical reactor, built to withstand high pressures, used to evaluate the kinetics of high-temperature, high-pressure reactions and the production of small quantities of specialty chemicals. The reactor is typically packed with a supported catalyst, and reactant is added by injection. Pressure in the system is elevated by increasing the temperature of the autoclave. Additional pressure, if needed, can be obtained with the injection of additional gaseous reactant or an inert. 

The autoclave is usually a heterogeneous batch reactor mainly used for high-pressure kinetic studies. The autoclave is typically a solid catalyzed gas-liquid reaction system. 

This reactor allows easy data collection for high-temperature, high-pressure reaction systems that have difficult flow properties. This includes reactants that are solid at room temperature or mixtures of solids and liquids. Typical reactions performed in autoclaves are coal liquefaction, petroleum residuals and coal liquids upgrading, and high molecular weight hydrogenation experiments. 

Autoclave sterilization is one of the most difficult common sterilization environments for a medical adhesive, and it is commonly used in hospitals and health care facilities for reusable devices. Autoclaves sterilize with high-pressure steam. Temperatures inside the sterilization chamber typically can reach 130°C with pressures above ambient. Certain adhesive systems, such as polyurethanes, may show hydrolytic degradation in such environments especially after multiple cycles. Epoxies perform the best under multiple autoclave exposures. However, on certain substrates, light-cured acrylics and cyanoacrylates will also perform fairly well. 

CjAHg is the only stable ternary phase in the CaO-AUOj H,0 system at ordinary temperatures, but neither it nor any other hydrogarnet phase is formed as a major hydration product of typical, modern Portland cements under those conditions. Minor quantities are formed from some composite cements and, in a poorly crystalline state, from Portland cements. Larger quantities were given by some older Portland cements, and are also among the normal hydration products of autoclaved cement-based materials. CjAHg is formed in the conversion reaction of hydrated calcium aluminate cements (Section 10.1). 

Main factors which affect a hydrothermal reaction are the initial eomposition, reaction temperature and time. In mild hydrothermal synthesis, reaction temperatures lower than 240 °C are respected for both safety of high pressure in normal autoclaves and protection of softness of Teflon line. In our specific synthesis system, high temperature favorites the reaction and the most important factor was the base concentration in the initial reaction mixtures. The reaction time associated with reaction temperature affected the reaction. Crystallization kinetic experiment for a typical reaction showed that a reaction time more than lOh gave well-crystallized product and the further crystal growth needed additional time. Table 1 lists the starting reaction compositions and phase identification of products obtained at 240 °C for lOh. 

A supercritical fluid has intermediate properties of liqirid and gas. Typically, the alcogel is placed in an autoclave filled with ethanol. The system is pressurized to 750-850 psi with CO2 and cooled to 5-10°C. Liqirid CO2 is then flushed through the vessel until all the ethanol has been removed from the vessel and from within the gels. When the gels are ethanol-free, the vessel is heated to a temperature above the critical temperature of C02(31°C). As the vessel is heated, the pressure of the system rises. The pressure of CO2 is carefully monitored to maintain a pressure slightly above the critical pressure of CO2 (1050 psi). The system is held at these conditions for a short time, followed by the slow, controlled release of CO2 to ambient pressure. The length of time required for this process is dependent on the thickness of the gels this process may last anywhere from 12h to 6 days. 

The package plant instrument specification details the instrumentation requirements and standards to be applied to any equipment packages. Typical equipment packages include Water for Injection (WEI) systems, chiller packages, gas scrubber packages, tablet presses, packaging machines, freeze dryers, autoclaves, and so on. Each specification should contain, or provide detailed reference to, the following information ... 

The major process for poly(vinyl chloride) production is the suspension system. Typical reaction temperatures are 50-65 C. As the reaction proceeds, a conversion ( 76%) is reached at which the only monomer left in the system is that absorbed in the polymer particles. This occurs when the monomer concentration is about 30 wt % in the particles. The occurrence of this phenomenon is signaled by a drop in the reactor pressure. Normal pressures in the autoclaves are initially about 150 psig (pounds per square inch, gauge), and it is usual to carry out polymerizations until the pressure drops to about 20-70 psig, depending on the reaction temperature. Water may be injected into the reaction vessel as the polymerization proceeds, to compensate for the volumetric contraction between monomer and polymer. This also helps prevent the reaction mixture from becoming too viscous. As well, the water addition enhances the cooling capacity of the reactor because it increases the heat transfer area on the walls. 

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