Liquid mass flow controller

Liquid mass flow controller LCA-42-2-C-1 Porter Instr. 

Two separate 2.1 L reservoirs contain the catalyst and product phases and the contents are fed into the reactor through a standard liquid mass flow controller. The contents of the reactor can be sampled from a pressure fed sample tube. The pressurized liquid reactor products exit the reactor through a pressure control valve, which reduces the pressure to atmospheric, and the liquid contents are delivered to a continuous decanter where the phases separate. The catalyst phase then settles to the bottom where it is drained for recycle and reuse, while the product phase is collected into a 4.2 L reservoir. 

Control of liquid flow does not seem to be a problem. There are two versions of liquid flow control one is to use a micro-pump or double cylinder to pressurize the liquid and the other is to use a liquid mass flow controller. In either case, the control of liquid flow seems to be accurate enough for CVD. One design precaution is to minimize the volume of the liquid lines, otherwise changing the source composition takes a long time with a large waste of expensive precursors. 

Fig. 6 Schematic layout of the TEX-PEP reactor setup including gas and liquid (unlabeled and labeled hydrocarbons) feed, the reactor and PEP detectors and post-reactor analysis. For diffusion measiu-ements of binary mixtures a second liquid mass flow controller is added (MFC mass flow controller)...

At the time of the solvent methanol experiments a metering pump was used. In some experiments the pulsating action of the pump can be disturbing, so a high-pressure syringe-type pump can be used. Since mass flow controllers are available now, the combination of a gas-pressurized feed tank on an electronic scale for liquid level indication and a mass flow controller seems to be a good choice. Both the feed tank and separator can be heated or cooled. In the case of the solvent methanol experiments. 

Figure 12-26. The SIMULAR reaction calorimeter. Features include pumped liquid feed, gas mass flow control, gas evolution measurement, and distillation equipment. (Source Hazard Evaluation Laboratory Ltd.)...

The schematic diagram of the experimental setup is shown in Fig. 2 and the experimental conditions are shown in Table 2. Each gas was controlled its flow rate by a mass flow controller and supplied to the module at a pressure sli tly higher than the atmospheric pressure. Absorbent solution was suppUed to the module by a circulation pump. A small amount of absorbent solution, which did not permeate the membrane, overflowed and then it was introduced to the upper part of the permeate side. Permeation and returning liquid fell down to the reservoir and it was recycled to the feed side. The dry gas through condenser was discharged from the vacuum pump, and its flow rate was measured by a digital soap-film flow meter. The gas composition was determined by a gas chromatograph (Yanaco, GC-2800, column Porapak Q for CO2 and (N2+O2) analysis, and molecular sieve 5A for N2 and O2 analysis). The performance of the module was calculated by the same procedure reported in our previous paper [1]. 

P Ij The liquid volume flow to the micro reactor is controlled by an HPLC pump [38]. The gas flow was set by mass flow controllers. Temperature was monitored by resistance thermometers. 

The surface of the micro channels was anodically oxidized to create a pore structure and thereafter wet-chemically impregnated [61]. The liquid reaction solution was fed by an HPLC pump hydrogen was metered by a mass-flow controller. Pressure was kept constant... 

Figure 5.28 Schematic of the experimental set-up. Water/ethylene glycol/SDS reservoir (a) high-pressure liquid pumps (b) catalyst/ substrate HPLC injection valve with 200 pi sample loop (c) hydrogen supply, equipped with mass flow controller (d) micro mixer (e) heating jacket (f) tubular glass or quartz reactor (g) back-pressure regulator (h) [64],...

P 24] Aqueous NaOH solutions of 0.1,1.0 and 2.0 M were used, fed by pumps to the micro devices [5]. Carbon dioxide was supplied as a mixture with nitrogen, the flow rate being set by a mass-flow controller, liquid samples were taken and subjected to carbonate analysis (see original citation in [5]). 

P 28/The Hquid feed was introduced by a pump and the gas feed using a mass-flow controller [10], The reaction was carried out using liquid flows of 20.7-51.8 ml h and gas flows of 1.7-173 mlrnin . The gas and liquid velocities amounted to 0.02-1.2 and 0.03-3.0 m s , respectively. The reaction was performed in mixed flow regimes, including bubbly, slug and annular patterns. The specific interfacial areas amoimted to about 5000-15 000 m m . The reaction was conducted at room temperature. 

Fig 18. Experimental trickle-bed system A, tube bundle for liquid flow distribution B, flow distribution packing of glass helices C, activated carbon trickle bed 1, mass flow controllers 2, gas or liquid rotameters, 3, reactor (indicating point of gas phase introduction) 4, overflow tank for the liquid phase feed 5, liquid phase hold-up tank 6, absorber pump 7, packed absorption column for saturation of the liquid phase 8, gas-liquid disengager in the liquid phase saturation circuit. (Figure from Haure et ai, 1989, with permission, 1989 American Institute of Chemical Engineers.)... 

Catalysts were tested for oxidations of carbon monoxide and toluene. The tests were carried out in a differential reactor shown in Fig. 12.7-1 and analyzed by an online gas chromatograph (HP 6890) equipped with thermal conductivity and flame ionization detectors. Gases including dry air and carbon monoxide were feed to the reactor by mass flow controllers, while the liquid reactant, toluene was delivered by a syringe pump. Thermocouple was used to monitor the catalyst temperature. Catalyst screening and optimization identified the best catalyst formulation with a conversion rate for carbon monoxide and toluene at room temperature of 1 and 0.25 mmolc g min1. Carbon monoxide and water were the only products of the reactions. 

A pressurized tank (10 bar) is used for the storage of distilled water fed to the reactor. To feed liquid water, a specific mass flow controller (Quantim, Brooks) is used. 

Figure 9. Configuration of the DS-IC system A, clean air input B, mass-flow controller C, permeation device chamber D and H, vents E, needle valve-rotameter F, needle valve G, mass-flow meter I, diffusion scrubber Jy scrubber liquid reservoir K, needle valve-rotameter L, suction pump M, injection valve Ny peristaltic pump O, eluent flow F, downstream chromatographic components and Q, sample loop. (Reproduced from reference 96.

A standard experimental set up was used for the catalytic experiments. The flow rates of helium, which was used as carrier gas and oxygen were regulated by mass flow controllers (Brooks). Both gases were used as delivered, without any further purification. The pressure at the reactor inlet was measured by means of a mercury manometer. The liquid reactant was pumped to the reactor by means of an injection pump. The tubing from the pump to the reactor was made of teflon, all others were stainless steel ( "o.d., 2 mm i.d.)... 

Reactant feeds are generated by vaporizing liquid flows from HPLC pumps with manometric pulse dampeners or high-pressure syringe pumps and mixing this vapor with gas components metered through mass flow controllers. This reaction feed is then divided between the 48 channels equally by using flow restrictors such as silica capillaries or micromachined channels (Fig. 3.12). The capillaries feed into the inlet stand-offs of the reactor modules. 

Experiments to measure pressure drop and flooding limits were performed in a set-up accommodating monoliths with diameters of 43 mm (Fig. 8.16), while the length of the monoliths varied up to total length of 1 meter. The liquid was distributed by a nozzle the gas was introduced in countercurrent mode via mass flow controllers in the system. At the outlet of the monolith, a special device was mounted (Fig. 8.17), which improved draining of the monolith. The pressure drop along the column was measured using differential pressure transmitters. All experiments were performed at room temperature and atmospheric pressure. 

Comparing this approach with previous work - except the studies on solid electrolytes - ionic liquids have two distinct advantages over aqueous or organic solvents (i) Due to their extremely low vapor pressure ionic liquids can be used without any problem in standard plasma vacuum chambers, and the pressure and composition in the gas phase can be adjusted by mass flow controllers and vacuum pumps. As the typical DC or RF plasma requires gas pressures of the order of 1 to 100 Pa, this cannot be achieved with most of the conventional liquid solvents. If the solvent has a higher vapor pressure, the plasma will be a localised corona discharge rather than the desired extended plasma cloud, (ii) The wide electrochemical windows of ionic liquids allow, in principle, the electrodeposition of elements that cannot be obtained in aqueous solutions, such as Ge, Si, Se, A1 and many others. Often this electrodeposition leads to nanoscale products, as shown e.g. by Endres and coworkers [60]. 

A typical setup for kinetic measurements is given in Fig. 8. Basically a feed, a reactor and an analysis section are required. Nowadays mass flow controllers for both liquid and gas result in stable molar flowrates, ideally for kinetic studies. Pressure controllers maintain a constant feed pressure for the flow controllers, while backpressure controllers maintain the pressure in the reactors. Various methods of product analysis are available and depend highly on the system under investigation. 

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