Flow splitting

By employing accurate test-design procedures (Pan and Wypych, 1992a), it is possible to model and design each pipe branch separately so that the system ultimately is well balanced. However, such a system may not be reliable over time due to uneven wear in the pipes/bends, changes in material property and/or on-site conditions. 

Splitters. The following common splitters have been introduced to improve the efficiency of flow splitting. 

The riffles plates will be subjected to wear and over time could affect flow splitting efficiency. 

The above devices are flow intrusive, subjected to wear and the splitter itself cannot control changing downstream conditions. A potentially more direct and efficient approach is to monitor the change in flow conditions downstream of a splitter (Barnes and Mumane, 1995) and employ active splitters (Selves et al., 1995) to control the split ratio of air and hence, material. Some of the active splitters being investigated and developed by Selves et al., 1995 include  

General Considerations. Some other important considerations that should be made when designing a flow splitting system are listed below. 

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This is pressure drop (including friction loss) between run and branch, based on velocity in the mainstream before branching. Actual value depends on the flow split, ranging from 0.5 to 1.3 if mainstream enters run and from 0.7 to 1.5 if mainstream enters branch. 

Figure 5-13. Diagram of a double-flow compressor with flow split internally.

Tray Thickness (Net Required for Bubble Cdps) Type of Flow Split, Cross Inlet Weirs (Y No) ... 

Figure 1.5 Photograph of the liquid-flow splitting unit for liquid/liquid processing with three tanks and six separation-layer micro mixers [8].

Schenk, R., Hessel, V., Hoemann, C., Kiss, )., Lowe, H., Schoneeld, F., Numbering-up of micro devices a first liquid-flow splitting unit, Chem. Eng. Technol. 26, 12 (2003) 1271-1280. 

Figure 4.52 Observed flow splitting performance for a 1000 pm X 100 pm micro channel system [31].

OS 68] [R 19] [P 50] A numbering-up of five mini mixers, tested at the pilot stage, was used [134]. Automation of the entire process was required liquid-flow splitting to the single reactors was ... by no means trivial... [134]. The capacity of one mini reactor was 30 ml s , i.e. 1081 h . The complete setup hence should be operated close to 5001 h . The micro-reactor plant was operated at intervals as the preceding step was carried out batchwise. The operation of the micro-reactor plant started in August 1998 after a period of only about 1.5 years for development. 

In contrast, the amount of material being conveyed inside each pipe branch of a flow splitting application is very high and hence, design cannot be based on air-only analyses alone. For example, Low et al., 1987 have proposed the following empirical relationship to determine the head loss of a pipe branch. 

Good flow splitting design is dependent on the accurate prediction of the pressure drop caused by the various bends, branches and straight sections of pipe. This can be achieved by employing the above branch model(s), proven for the particular material and application, coupled with the accurate pipeline test-design procedure described in Sec. 2.4 of this chapter. 

When nano LC is combined with mass spectrometer detection, attamole detection can be achieved for low abundance components in biological fluids, drug metabolites, and natural products such as Chinese herb medicines. Nano LC-MS-MS has become an essential tool for complex biological and drug metabolite studies. Nano LC-MS presents two significant differences from conventional analytical HPLC (1) large enhancement factor for sample detection and (2) direct interface to MS without flow splitting. The enhancement in MS ion counts relative to a conventional 4.6 mm ID column is proportional to the ratio of the square of the column diameter ... 

For a 75 /.mi ID nano LC column as an example, the MS detection enhancement factor (ion count) in comparison to a 4.6 mm column is much higher than (4.6/0.075)2 = 3761 because of the reduction in sample molecular zone dilution and because a nano LC solvent flow rate at 0.02 to 2 /iL/min can be 100% directly sprayed into the MS ion source. No post-column flow splitting is required for nano-LC-MS as that required when 1 mL/min is used in a 4.6 mm ID column. This large enhancement of MS detection and the ability to directly interface with MS presents nano LC-MS as the best tool for life science research. 

Many commercial split flow capillary LC systems incorporate a nano flow sensor mounted online to the capillary channel. The split flow system can be easily modified from a conventional system and performs satisfactorily for capillary LC applications. However, the split flow system may require thermal control and the LC solvent requires continuous degassing. In addition, the system may not work reliably at a high flow split ratios and at pressures above 6000 psi due to technical limitations of the fused silica thermal conductivity flow sensor. The split flow system based on conventional check valve design may not be compatible with splitless nano LC applications. The conventional ball-and-seat check valve is not capable of delivering nano flow rates and is not reliable for 7/24 operation at low flow. 

When water flow encounters a loop or grid, two features occur - (1) the flow splits into a determinable ratio, and (2) the pressure drop across each of the two legs will be the same. 

Three principal variations in the process design of DAF systems are full-flow, split-flow, and recycle operation (Fig. 14). Full-flow operation consists of pressurizing the entire waste... 

The flow entering the reactor includes both fresh feed and the recycle stream. Measuring the flow split at point L (point K will not do if e 0) we then have... 

A computational model will be developed for numerous water quality parameters in the Platte River, Nebraska. In many locations, this river splits into multiple channels that are joined back together downstream. One significant split is the Kearney Canal diversion, illustrated in Figure E6.7.1, where 20% of the flow splits off into a second river at the city of Overton, only to return 20 km downstream at the city of Kearney. A tracer pulse was put into the river at location x = 0 and time t = 0, upstream of the diversion. Downstream of the diversion s return, the pulse at location x = 25 km is given in Figure E6.7.2. Develop a model for this reach that contains equal size tanks-in-series for the main channel and a similar number of tanks-in-series with the addition of a possible plug flow for the side channel, as illustrated in Figure E6.7.3. 

The GC was calibrated using a mixture of known quantities of d-limonene, d-limonene oxide (cis and trans), 2-octanone, and carvone. GC analyses were performed by injecting 1 pi samples with 1 40 split (column flow split flow), into a Hewlett-Packard 5840A GC equipped with a flame ionization detector. A fused silica capillary column 50m x 0.25 mm i.d., coated with OV-101 as a liquid phase was used. Column temperature was programmed from 50-250 C at 10 C/min, and helium was used as the carrier gas. 

Split/splitless injection. When capillary columns are used with small flow rates, even the smallest of injection volumes can saturate the column. Injectors that can operate in two modes, with or without flow splitting, are used (called split/... 

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