Abstract: A method for reprocessing waste acid from methods for producing nitro-aromatics, in particular for producing dinitrotoluene (DNT) or trinitrotoluene (TNT), to recover concentrated and purified sulfuric acid and nitric acid, wherein in a first stage, the waste acid is separated in a stripping column countercurrently with water vapor from the bottom of the stripping column into at least one vapor phase, which contains nitric acid and possibly nitro-organics, and a pre-concentrated sulfuric acid, and the vapor phase and the pre-concentrated sulfuric acid are condensed and/or reprocessed in downstream method stages, wherein in the first stage of the method, in addition to the stripping, the nitric acid contained in the stripping vapor is concentrated in the presence of additional concentrated sulfuric acid so that nitric acid in a highly concentrated form suitable for feeding back into the nitration process is obtained directly in the first stage.

Abstract: The invention relates to a method for reprocessing waste acid from methods for producing nitro-aromatics, in particular for producing dinitrotoluene (DNT) or trinitrotoluene (TNT), to recover concentrated and purified sulfuric acid and nitric acid, wherein in a first stage, the waste acid is separated in a stripping column countercurrently with water vapor from the bottom of the stripping column into at least one vapor phase, which contains nitric acid and possibly nitro-organics, and a pre-concentrated sulfuric acid, and the vapor phase and the pre-concentrated sulfuric acid are condensed and/or reprocessed in downstream method stages, wherein in the first stage of the method, in addition to the stripping, according to the invention the nitric acid contained in the stripping vapor is concentrated in the presence of additional concentrated sulfuric acid so that nitric acid in a highly concentrated form suitable for feeding back into the nitriding process is obtained directly in the first stage.

Abstract: Apparatus and methods for indicating seal leakage between two components are provided. In one aspect, apparatus and methods for directing material penetrating a leaking nozzle repair shield seal to a predetermined indication point such that a user viewing such indication point is alerted to the leaking seal condition is provided. In one aspect of the present invention, a channel having six distinct sections directs the material to the indication point. These six channel sections include two annular sections extending about the periphery of a main cylindrical section and an inwardly facing surface of a flange of the nozzle repair shield. These six channel sections further include a reservoir and interconnecting channel sections. Also, a sleeve for encircling the outwardly facing surface of the main cylindrical section of the nozzle repair shield is provided and the indication point may be provided in the form of a reservoir.

Abstract: A method for recovering diluted waste sulfuric acid by extractive rectification with concentrated sulfuric acid which is re-concentrated for reutilization. Waste sulfuric acid from the nitration process is fed into a first column, optionally together with another waste sulfuric acid in a DNT washing acid, and divided into an overhead product containing nitric acid and nitro-organic compounds and a prepurified sulfuric acid in the bottom product. The prepurified sulfuric acid withdrawn from the bottom of the first column is fed to the top of a second column, into the bottom zone of which another waste sulfuric acid is fed in the form of a diluted sulfuric acid recovered from the nitric acid concentration system so the prepurified sulfuric acid from the first column is further purified in the second column and is preconcentrated along with the diluted sulfuric acid recovered from the extractive rectification of nitric acid.

Abstract: A valve seat and a valve assembly incorporating such valve seat form tight dual seals with glass lined nozzle of a reagent or reaction vessel. This reduces or eliminates cavities and crevices between the value seat and the nozzle where residues or contaminants can accumulate. Additionally, the present valve assembly comprises flush ports to permit the valve seat and the valve to be cleaned-in-place. This eliminates the need to disassemble the valve seat and/or the valve to remove the contaminants, thereby minimizing process “down time.

Abstract: In order to decrease thermal interference related to heating or cooling fluid (14) contained in the exterior double envelope of the container, the invention consists of positioning the measurement point away toward the interior of the container by forming a local deformation in the wall (12) in the form of a non-penetrating recessed area (21) which serves as a housing for a contact temperature measurement probe (17). The wall (12) of the recessed area becomes progressively thinner until it is minimal at the level of the base (22), against which the temperature measurement is taken, resulting in a more precise, quicker reading. This invention is of interest within the chemical industry, particularly to manufacturers and users of temperature measurement devices.

Abstract: The closing device (16) moves between a position that opens a valve and a position that closes a valve (14), which is specifically a drainage valve used on a chemical reactor (1), a storage vat, a column or other container, and it comprises an interior housing (30) designed to hold a measurement or detection probe (27). It has an opening (38) that is accessible when it is in the operating position inside the valve and which provides access to its interior housing, allowing the probe to be inserted or removed without the need for prior disassembly of either the valve or the closing device. This invention is of interest to the chemical industry, particularly manufacturers and users of temperature measurement devices.

Abstract: A valve seating (23) is made from a fluoridated polymer, for example, solid glass-coated PTFE or reinforced PFA. At least one electrode (24) is attached to or integral with the valve seating and made of conductive material, such as graphite-TEFLON®, that is compatible with the valve seating. The valve seating is especially for use in conjunction with a device for verifying the integrity of an enamel coating of the “enamel-test” type. The valve seating is then used on the waste valve (11) of the container to be checked and two electrodes (24) are disposed so as to be in contact with the contents (8).

Abstract: The heat exchanger according to the invention consists of two flat or slightly incurved parallel surfaces formed in two sheets of metal (2) and (3). The longitudinal edge pieces (8) and (9) and transverse edge pieces (12) and (13) have rounded edges. The entire exterior surface is coated with enamel. These exchangers may be used in groups of several parallel units arranged inside a tubular body, or they may be disposed in a radiating pattern inside a cylindrical tank in a chemical reactor, forming a complex exchanger. This invention is of interest to manufacturers of industrial heat exchangers, particularly exchangers designed for the chemcial, pharmaceutical or agricultural/food industries.