Multipass converter

In the 21st century an attempt is made in this presentation of a new, unconventional and innovative approach to produce sulphuric acid and sulphonating agent without a sulphur furnace, multipass converters, heat exchangers or expensive towers. A special feature of this process will be zero emission of sulphur dioxide, eliminating more than one million tonnes of acid rain at the current production of Sulphuric Acid in the world. 

Optical multipass cells have been used for the enhancement of CW Raman scattering(4) however, these cells are typically not well-suited for use with high power, pulsed lasers. A new multipass cell for use with a pulsed Nd YAG laser is proposed whereby the 1.06 micron laser output is admitted into a multipass cell cavity where it is partially converted to 532nm with a Brewster s angle cut second harmonic generating crystal The 532nm pulse is trapped in the mirrored cavity while the 1.06 micron pulse is dumped. This multipass cell concept has been demonstrated with the experimental set-up shown in figure 1. 

In the third stage the 708 nm light is converted to 6.02 pm via third Stokes Raman shift in a high pressure hydrogen cell. The 0.5 mJ, 7 ns long pulses are injected into a multipass cavity inside the gas target in order to effectively illuminate the muon stop region. 

Fig. 8. The components of the laser system. The high power XeCl excimer laser pulse triggered my the muon entrance detector is converted in two steps to a high quality 7 ns long pulse of 708 nm which is shifted to the desired 6 pm light inside the multipass Raman cell. The light is injected into a multipass cavity to effectively illuminate the muon stop volume inside the PSC solenoid. High resolution frequency selection is provided by injection of a cw Ti Sa laser...

Apart from the benefits of the high pressure mixing of SO3 with water to produce sulfuric acid, the proposed cold process for the manufacture of sulfuric acid has also been conceived to avoid the complexity of requiring a sulfur furnace and the related heat recovery system, the multipass static converter, counter current heat exchangers, the interpass absorption tower (IPAT), drying tower (DT), final absorption tower (FAT), mist eliminators, acid coolers, and alkali scrubber. The resulting plant is, as a result, of much lower cost in equipment and land use. 

The key component of an LOAS instrument is the spectrophone. Its construction depends critically on the state of aggregation of the sample. The SP for gas samples consists of a gas cell with input and output windows for laser radiation and a microphone, fixed on an inside or outside wall of the cell. As in the case of MAS with SDLs. the sensitivity can be improved by the use of multipass SPs. Plane capacitor or electronic microphones are the most widely used. The sensitive element of these microphones is a thin (1-10 pm) elastic membrane made of Mylar. Teflon, or metallic foil. The membrane serves as one electrode of a dielectric capacitor (membranes made of dielectric materials have metallic coatings). Thus, the acoustic vibrations of a gas mixture in the cell can be directly converted to an electrical signal. Commercial microphones with sensitivities of 5-50mV/Pa are utilized in routine applications of LOAS specially constructed and optimized ones are used for ultrasensitive analyses. 

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