Delivery nozzle design

Figure 8. Extraction Effluent Delivery Nozzle Design with Component Parts.

For superheated steam, the sample points should be designed and installed to permit correct isokinetic sampling. A modified multiport nozzle design ensures that the velocity of the steam entering the sample nozzle is the same as the velocity of steam in the header. The design incorporates a small, high-quality water delivery tube, used to inject water and remove superheat before sample extraction. 

For the delivery of atomization gas, different types of nozzles have been employed, such as straight, converging, and converging-diverging nozzles. Two major types of atomizers, i.e., free-fall and close-coupled atomizers, have been used, in which gas flows may be subsonic, sonic, or supersonic, depending on process parameters and gas nozzle designs. In sonic or supersonic flows, the mass flow rate of atomization gas can be calculated with the following equation based on the compressible fluid dynamics ... 

The pressure drop in the Y or J-bend section could be from improper fluidization or a flaw in the mechanical design. There are often fluffing gas distributors in the bottom of the Y or along the J-bend that are designed to promote uniform delivery of the cataly.st into the feed nozzles. Mechanical damage to these distributors or too little or too much fluffing gas affect the catalyst density, causing pressure head downstream of the slide valve. 

The vapor pressure and the design of the canister nozzle determine the aerosol jet and eventually impaction. Low vapor pressure increases drng delivery from a particular spacer due to a reduced jet and therefore rednced impaction. Airomir salbutamol pMDl containing HFA propellant delivered less drug as fine particles (MMAD < 5 pm) compared with the Ventolin salbutamol pMDI containing chloroflnorocarbon (CFC) propellant but a higher output from a spacer, probably due to a lower jet velocity (29). 

Shock Tube as Vaccine Delivery System A unique form of powder delivery system, a biolistic system, has been developed [19]. This novel technology accelerates microparticles by a gas flow behind a traveling shockwave, so that they can attain sufficient momentum to penetrate the skin and thus achieve a pharmacological effect. One of the most recent developments is a mouse biolistic system, used in immunological studies. These studies require powdered vaccine to be delivered into the epidermis of the mouse with a narrow and highly controllable velocity distribution and a uniform spatial distribution. The preliminary results demonstrate the overall capability of a newly designed supersonic nozzle to deliver the particles to the skin targets with a more uniform velocity and spatial distribution. CTD has been utihzed to characterize the complete operation of a prototype mouse biolistic system. 

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