Document EJE877JEjBByx9dazkRbEwng

tr * t/>m engineering Getting out the last traces of VCM Tenneco process uses activated carbon to remove vinyl chloride monomer from PVC plant gas streams. It's one of several methods producers are licensing More than a year's experience with its parity. Further, there was no evidence of through the vapor space of the lank to carbon adsorption method of controlling vinyl chloride polymerization in the ad keep VCM concentrations down and pre vinyl chloride emissions from polyvinyl sorption unit or within the carbon. vent a flammable mixture from forming. chloride plants has convinced Tenneco Trouble Spots: Aside from leaks, Depending on the level of stripping of Chemicals (Saddle Brook, N.J.) that it which manufacturers try to keep to a the slurry downstream, VCM concentra has found the best route. So it is setting minimum, there are several points where tions in the nitrogen purged may reach 15 3 out to license the method to others. VCM can escape to the atmosphere: at mol percent. When the cancer-causing properties of the reactor, the slurry tanks, and equip Various equipment in (he process is vinyl chloride monomer became known, ment purge streams. also purged with inert gar to reduce the explains Robert S. Miller, manager of PVC is made primarily by either sus explosion hazard and to remove the last polymers research, the firm had to de pension or emulsion polymerization tech traces of VCM. These off-gas purge velop its own technology to control emis niques. Generally, in these processes streams generally contain 10-30 mol per sions. Now it is marketing the know-how VCM and the polymerization initiator cent vinyl chloride. in the U.S. and in European countries are dispersed in water by the use of sus New Twist: Vinyl chloride has been that are following the U.S. lead in setting pending or emulsifying agents. The poly around a long time and so has activated stringent emission standards. merization temperature is selected to ob carbon. But up to now. researchers have The firm is just one of a number of tain the desired molecular weight. But worked with pure monomer. Tenneco's U.S. producers that have developed li not all of the vinyl chloride is converted contribution has been to make the pro censing packages in an effort to recoup into PVC. Usually 17-20% of monomer cess work with recovered vinyl chloride, part of the millions they have spent to de that does not react remains at the end of says Gottesman. He explains that this velop the new technology. the polymerization cycle. Much of that material can contain residual initiators, B.F. Goodrich is licensing its steam can be recovered and recycled to the catalyst fragments, and suspending stripping process, which removes VCM front end of the process. But as much as agents, so that it is prone to polymerize from PVC suspension resins. Diamond and foul the carbon system. ti Shamrock has developed a proprietary technique for removing residual VCM ..-.tv Making the process work is a matter of selecting the right operating conditions from PVC dispersion resins. Monsanto and the right type of activated carbon. has been licensing its PVC reactor clean Another method of scrubbing VCM ing know-how for more than a year. from stack gas, called oxyphotolysis, has Lonza (Basle, Switzerland) is offering a been investigated by Robintech of Fort 2 procedure for preventing suspension Worth. Tex. (C W Technology Newsletter, resin polymer buildup on reactor walls. July 9. J975). The firm says it is still eval And several others have developed in uating the economics of installing the strumentation to monitor the amount of unit, which so far has not been used com VCM in the air and in PVC. mercially. Thirsty Carbon: Tenneco's develop Although carbon adsorption is the pro ment is aimed at recovering the residual cess (hat Gottesman believes wilt attract VCM in vent gas streams (CIV, Sept. 18, the widest interest, the company is arm }974, p. 66). A unit built by Chemical De ing itself with a variety of other tech sign (LnckporL N.Y.) was installed at nology. "We have filed 13 patent appli Tenneco's PVC plant in Pasadena. Tex., cations on widely differing subjects," says in early 1975. Gottesman. "They include a spray appa A year's experience with the equip ratus for cleaning PVC reactors, processes ment, says Roy T. Gottesman, associate for removing VCM from suspension and director of research and development, TENNECO'S GOTTESMAN: New process emulsion processes, the destruction of shows that less than 4 ppm. of vinyl chlo cuts PVC plants* VCM loss to below 4 ppm. VCM by ozonolysis and the removal of ride monomer is escaping in the adsorber monomer from dispersion latex by spar effluent stream. Dunng that time, the ac 4% VCM can remain in the PVC slurry ging" tivated carbon in the unit has undergone from the reactor. That can be removed by If others' experience is any indication, more than 1,300 adsorption and regener specialized stripping techniques, such as there is a big demand for the know-how. ation cycles. That makes it good enough the ones Goodrich. Diamond Shamrock B.F. Goodrich Chemical says it has to meet the proposed Environmental Pro and Tenneco now offer. signed agreements with six corporatibns tection Agency standard of 10 ppm. . Residual VCM from that cleanup in Sweden, Italy, Japan and the U.S. for Moreover, after 10 months of contin phase is one of the potential, sources of its suspension-resin stripping technology. uous service, samples of carbon with feed for the carbon adsorption step. Diamond Shamrock became a licensor drawn from the adsorber showed that it Another source is the slurry tanks, in March, offering its proprietary tech retained 90% of its original adsorptive ca- where operators flush air or nitrogen nique for removing residual VCM from August 1L 1976 CHEMICAL WEEK 35 RSV 0006777 You can have plenty; get it fast! Aminate reacts with acids to generate carbon dioxide and pro duce solutions of the correspond ing salt. It's used in the manufacture oftetrazene.an ingredientfor small arms primers. Further applications: in photo graphic emulsions, azo dyes, depilation of animal skins, textile softening agents, flameproofing agents. Also as a blowing agent in manufacture of foam as a vinyl sta bilizer, and in the preparation of aminoplast resins. Let your chemical imagination roam. Find all the uses you want, because we have all the Aminate you could want. Available as a fine, white, odorless crystalline powder. Delivery is fast. The price is right. For full details, write today to the IMG Chemical Group. Inc., Sobin Park, Boston. Mass. 02210. line @2) CHEflllCAl GROURlnc. CSC INDUSTRIAL CHEMICALS DIVISION AtubMiafyo* *oi<n*orvai Mminiit CAefracai Corpofitton 36 CHEMICAL WEEK August 11. 1976 'ngineering dispersion resins. Different techniques are required for the two systems because of differences in particle size. The company explains that in the suspension process, monomer droplets sus pended in water typically produce PVC particles ranging in size from 90 to 130 microns, in the dispersion or emulsion process, a colloidal dispersion of mono mer dropleis creates PVC particles aver aging 0.5 micron in size. These smaller particles afe more sensitive to heat and mechanical disturbance than suspension resins, thus different technology is re quired. Says Diamond Shamrock, "We are us ing it ourselves. Wc have a number of people seriously interested, including some from outside the U.S. We do not at the moment have any licensees. But it is a relatively new offer." It seems doubtful that anyone will reap a financial bonanza from the new tech nology. Rather, licensors see their effort as one of trying to recover part of their development cost. Diamond Shamrock adds: "Licensing this kind of technology is not going to be a giant money-maker for anybody, as far as we can see. once you put the income generated up against what it cost to de velop it in the first place. We hope wc will be able to defray our developmental costs--that is, spread them out through (he industry." Insight into energy A new 900-page United Nations study of energy use has turned up extensive data on the use and distribution of com mercial energy since 1950- Among the findings: The U.S., y/ith 5% of the world's population, used 30% of the world's com mercial energy in 1974, compared with 45% in 1950. Its per-capita gasoline con sumption was nine times the world aver ts*- The U.S.S.R,, the world's secondlargest user, increased its share from 11.5% in 1950 to 16.6% in 1974. China and Japan are the third- and fourth-largest consumers, respectively. China still relies mainly on solid fuel. Ja pan is a leading importer of all types of energy. The report updates earlier studies on commercial energy production, trade and 1 consumption and includes preliminary data on the production of primary fossil* fuels for 1975. It is available from the UN Sales Sec tion (New York) for J30. RSV 0006778