Cleaning method

Loosen and dissolve foulants from membrane surface Keep foulants in dispersed and soluble form Avoid fresh fouling 

Does not cause damage to membrane material Easily rinsed away after cleaning Chemically stable before, during and after use Cost effective 

Chemicals Commonly Used in Membrane Cleaning and Their Cleaning Actions 

Type of chemicals Common chemicals used Typical concentration (%) Cleaning actions (87) 

Enzymes Lipase Break down high-molecular-weight 

Solvent Name/Supplier Density, gm/cm Snrface Tension, dynes/cm Viscosity, Pa.s Wetting Index 

Deionized water + surfactant Deionized water + surfactant 0.998 29.7 1.08 31 

Azeotropes - 2 Minute Boil Sump, 2 Minute Rinse Sump 

Organic solvents Remove adhesive and solder paste residues have a wide-process window can clean at room temperature do not oxidize or corrode metals Solvents and solvent vapors may be flammable high cost may be slow drying limits on VOCs and ozone-depleting solvents (ODSs) require explosion-proof equipment 

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This procedure can be applied to most P2P mixes but is especially effective on the methods to follow. However, in super clean methods, such as the PdCl2 below, where lots of isosafrole is produced, the iso byproduct can interfere with crystal formation. Someone-Who-ls-Not-Strike once found that when an appreciable amount of isosafrole was formed to the detriment of MD-P2P, the oil screwed up the crystal matrix disallowing it to form. Confused, the chemist tried to rescue the uncrystallized oil from the aqueous solution by extracting out the oil to try other things. But when the solvent hit the solution, the P2P crystallized out. Go figure The... 

Fuel Cell Catalysts. Euel cells (qv) are electrochemical devices that convert the chemical energy of a fuel direcdy into electrical and thermal energy. The fuel cell, an environmentally clean method of power generation (qv), is more efficient than most other energy conversion systems. The main by-product is pure water. 

Another way to determine durabHity is to find successfuHy sealed, existing field instaHations. Sealant manufacturers often have case histories of successful instaHations. Adhesion performance can vary widely with sealant type, substrate type, and cleaning method. Eor this reason, it is important to understand the sealant s sensitivity to cleaning practices. Often with difficult-to-adhere substrates, a primer is used. Sealant manufacturers can provide recommendations as to which substrates require primers, what type of primers should be used, and how they should be appHed. 

Gleaning. Fouling films are removed from the membrane surface by chemical and mechanical methods. Chemicals and procedures vary with the process, membrane type, system configuration, and materials of constmction. The equipment manufacturer recommends cleaning methods for specific apphcations. A system is considered clean when it has returned to >75% of its original water flux. 

Nitrogen, unlike pyritic sulfur, is mosdy chemically bound in organic molecules in the coal and therefore not removable by physical cleaning methods. The nitrogen content in most U.S. coals ranges from 0.5—2.0 wt %. 

Use cleaning methods which don t require opening the filters... 

Both parties need to identify responsibilities for choosing the right equipment for the process, preparing equipment for the process, and decontaminating equipment. Consider whether chemical and process hazards have been addressed in the selection, preparation, and decontamination of equipment. Examine the need to contractually address containment and disposal of residual process fluids and decontamination materials. If food products or pharmaceuticals are involved, cleaning methods may also be an issue to address in the contract. 

Mechanical Cleaning Methods Possible Not possible Not possible... 

Chemical Cleaning Methods Possible Possible Possible... 

Electrolytic Cleaning—method of degreasing/descaling metal surfaces via electrolysis. The metal is utilized as an electrode. 

The early pioneers also include Benjamin Franklin and Charles de Coulomb. Franklin studied the effect of point electrodes in drawing electric currents. Coulomb discovered that a charged object gradually loses its charge i.e., he actually discovered the electrical conductivity of air. Coulomb s importance for the development of electrostatic air-cleaning methods is great, mainly because the present theories about electric charges and electric fields are based on his work. 

This type of bag-cleaning method is a fundamental characteristic of this type of collector. Terminology in the fabric filter field is not totally consistent or comprehensive. Table 13.2 presents acceptable definitions for common fabric filter terminology. 

Cleaning method The physical principle used to dislodge and remove the coliccred dust from the fabric,... 

Blinding A situation wherein fabric and dust cake permeability cannot be maintamed. The collected dust so adheres to or is so embedded m the fabric substrate that it cannot be removed by the cleaning method employed. This is evidenced by continually increasing pressure drop. 

Care is needed to ensnre that the cleaning method is compatible with the flame arrester in terms of the materials of constmction and the arresters overall rohnstness. Snitahle cleaning methods inclnde the nse of solvents, water, steam, compressed air, or nltrasonics. 

The decomposition of diacyl peroxides provides a fairly clean method for the production of alkyl radicals and, therefore, it has been used in most quantitative and preparative studies of the alkylation of heterocyclic compounds,... 

Ultrasonic cleaning (all grades). An ultrasonic cleaner suitable for cleaning wire rope is permitted in lieu of the acid cleaning methods described previously. 

Other cleaning methods. Other cleaning methods of proven reliability are permitted. 

Superior ventilation at point of dust/fume origin Priority to cleaning methods (vacuum, etc.) ... 

The filtration, or superficial face, velocities used in fabric filters are generally in the range of 1 to 10 feet per minute, depending on the type of fabric, fabric supports, and cleaning methods used. In this range, pressure drops conform to Darcy s law for streamline flow in porous media, which states that the pressure drop is directly proportional to the flow rate. The pressure drop across the... 

The foundation must support the weight of the baghouse. In addition, it must absorb the vibrations generated by the cleaning system. This is especially true when using the shaker-cleaning method, which can generate vibrations that can adversely affect the structural supports, foundation, and adjacent plant systems. 

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