Chemical stripper

The last step involves the removal of the photoresist layer using chemical strippers or by volatilizing it. If the photoresist adheres too well, then it can pose a problem in its removal. 

When deleading work is in progress, forced air systems must be shut down so that lead dust doesn t spread. Unpainted radiators need to be covered to protect them from lead dust, although it is important to have adequate heat, both for the comfort of the workers, and for new paint, encapsulants, or chemical strippers to work properly. You may need to provide electric space heaters if work is done during cold weather. If you use flame heaters, be sure to ventilate well and keep volatile chemicals a safe distance away. 

Windows should be kept closed. An alternative form of ventilation should be provided if volatile chemicals (strippers) are used. 

Heavy plastic sheeting Utility knife or scissors Wet/dry sandpaper, sanding sponge Misting bottle, pump sprayer Chemical stripper... 

Another commenter noted that window removal and offsite chemical stripping in a well-ventilated setting is an alternative to using heat or mechanical methods to remove lead paint onsite. Alternatively, chemical strippers can be used onsite, given adequate ventilation and protection for workers and building occupants. EPA is therefore persuaded that there are sufficient alternatives to these practices. 

REMOVE THE OLD FINISH. Wipe down the piece with a damp rag to remove any accumulated dust and dirt. Follow the instructions in How to Strip Paint on page 240, and opt for a gel and not a liquid stripper (it is prone to drain off furniture before it can work properly). Use a putty knife and steel wool to remove as much paint or varnish as possible. If you don t want to use a chemical stripper, reach for the random orbital sander (or spend hours building muscle and character sanding by hand). 

Uses. Tetrahydrofurfuryl alcohol is of interest in chemical and related industries where low toxicity and minimal environmental impact are important (134). For many years tetrahydrofurfuryl alcohol has been used as a specialty organic solvent. The fastest growing appHcations are in formulations for cleaners (135) and paint strippers (136), often as a replacement for chlorinated solvents (137). Other major appHcations include formulations for crop sprays, water-based paints, and the dyeing and finishing of textiles and leathers. Tetrahydrofurfuryl alcohol also finds appHcation as an intermediate in pharmaceutical appHcations. 

Exxate Solvents are Setting the Pace in Paint Strippers, Exxon Chemicals, 1989, p. 3. 

Eor use in paint strippers, one of its first appHcations, methylene chloride is blended with other chemical components to maximi2e its effectiveness against specific coatings. Typical additives include alcohols, acids, amines or ammonium hydroxide, detergents, and paraffin wax. Paint stripping formulations without methylene chloride have not as yet been shown to be as effective as those with methylene chloride. 

Distillation Columns. Distillation is by far the most common separation technique in the chemical process industries. Tray and packed columns are employed as strippers, absorbers, and their combinations in a wide range of diverse appHcations. Although the components to be separated and distillation equipment may be different, the mathematical model of the material and energy balances and of the vapor—Hquid equiUbria are similar and equally appHcable to all distillation operations. Computation of multicomponent systems are extremely complex. Computers, right from their eadiest avadabihties, have been used for making plate-to-plate calculations. 

Generahzed prediction methods for fci and Hi do not apply when chemical reaction occurs in the liqmd phase, and therefore one must use ac tual operating data for the particular system in question. A discussion of the various factors to consider in designing gas absorbers and strippers when chemical reac tious are involved is presented by Astarita, Savage, and Bisio, Gas Treating with Chemical Solvents, Wuey (1983) and by Kohl and Ricseufeld, Gas Purification, 4th ed., Gulf (1985). 

The SB method is not presented here, but is presented in detail in the sixth edition of Peny s Chemical Engineers Handbook. Extensions of the SB method to nonideal mixtures and complex configurations are developed by Eckert and Hlavacek [Chem. Eng. ScL, 33, 77 (1978)] and Eckert [Chem. Eng. Sci., 37, 425 (1982)] respectively but are not discussed here. However, the approximate and very useful method of Kremser [Nat. Pet. News, 22(21), 43 (May 21, 1930)] for application to absorbers and strippers is discussed at the end of this subsec tion. 

More often than not the rate at which residual absorbed gas can be driven from the liqmd in a stripping tower is limited by the rate of a chemical reaction, in which case the liquid-phase residence time (and hence, the tower liquid holdup) becomes the most important design factor. Thus, many stripper-regenerators are designed on the basis of liquid holdup rather than on the basis of mass transfer rate. 

Rousseau, R. W. and Staton, S. J., Analyzing Chemical Absorbers and Strippers, Chemical Engineering, July 18, 1988. 

Fig. 8.7 shows a second example (Cycle A2) of carbon dioxide removal by chemical absorption from a CCGT plant, but one in which the semi-closed concept is introduced— exhaust gas leaving the HRSG is partially recirculated. This reduces the flow rate of the gas to be treated in the removal plant, so that less steam is required in the stripper and the extra equipment to be installed is smaller and cheaper. This is also due to the better removal efficiency achievable—for equal reactants flow rate—when the volumetric fraction of CO2 in the exhaust gas is raised from the 4-6% value typical of open cycle gas turbines to about 12% achievable with semi-clo.sed operation. 

The chemical solvent DIPA acts as secondary treatment to remove H2S and CO2. The DIPA allows pipeline quality residual levels of acid gas 10 be achieved easily. A stripper is required to reverse the reactions of the DIPA w ith CO2 and H2S. This adds to the cost and complexity of the sys... 

The reboiler provides the heat input to an amine stripper, which reverses the chemical reactions and drives off the acid gases. Amine reboilers may be either a kettle reboiler (see Chapter 3) or an indirect fired heater (see Chapter 5). 

Amine strippers use heat and steam to reverse the chemical reactions with CO2 and H2S. The steam acts as a stripping gas to remove the COo and HjS from the liquid solution and to cairy these gases to the overhead. To promote mixing of the solution and the steam, the stripper is a trayed or packed tower with packing normally used for small diameter columns. 

The Rijnmond area is that part of the Rhine delta between Rotterdam and the North Sea. The Commission for the Safety of the Population at large (COVO) commissioned the study for six chemicals and the operations associated with them acrylonitrile, liquid ammonia, liquid chlorine, LNG, propylene, and part of a separation process (diethanolamine stripper of a hydrodesulfurizer). The study objectives were to evaluate methods of risk assessment and obtain experience with practical applications of these methods. The results were to be used to decide to what extent such methods can be used in formulating safety policy. The study was not concerned with the acceptability of risk or the acceptability of risk reducing measures. 

Adsorbers, distillation colunuis, and packed lowers are more complicated vessels and as a result, the potential exists for more serious hazards. These vessels are subject to tlie same potential haz. uds discussed previously in relation to leaks, corrosion, and stress. However, llicse separation columns contain a wide variety of internals or separation devices. Adsorbers or strippers usually contain packing, packing supports, liquid distributors, hold-down plates, and weirs. Depending on tlie physical and chemical properties of the fluids being passed tlirough tlie tower, potential liazards may result if incompatible materials are used for llie internals. Reactivity with llie metals used may cause undesirable reactions, which may lead to elevated temperatures and pressures and, ullinialely, to vessel rupture. Distillation columns may contain internals such as sieve trays, bubble caps, and valve plates, wliicli are also in conlacl with tlie... 

The figures reported in Table 13 represent an optimum quality target for industrial production of FAES. Nevertheless, the Dryex system affords the possibility of further reducing the content of 1,4-dioxane to below the limit of 10 ppm (referred to 100% AM content). In this case, the Dryex system operates as a stripper of the H20/dioxane mixture, being the physical and chemical characteristics of dioxane allow its removal from water solution at reduced pressure with relative ease. 

Prepare an outline design of the reactor and carry out the chemical engineering design of the stripper, specifying the interfacial contact area which will need to be provided between the carbon dioxide stream and the product stream to enable the necessary mass transfer to take place. 

In this paper, we focus on synthesis and application of esters of bio-based organic acids. Organic acid esters are used or have potential for use in many industrial and consumer applications including solvents, paint strippers, surfactants, fragrances, and fuel stabilizers2. The chemicals used in these... 

A typical chemical absorption scheme is shown in Figure 4. A low C02 concentrated flue gas is introduced in the absorber in crosscurrent with lean solvent from the stripper at 50-55°C and ambient pressure. C02 reacts with amines in the absorber according to the overall reaction ... 

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