Abstract: A heat exchanger having two or more tube bundles extending parallel to the shell with a central longitudinal space between the tube bundles. The tube bundles have a longitudinal axis is symmetry in such space. The tubes in each bundle are laid out in concentric arcs. The arcs of each bundle have a common center of curvature which is displaced from the axis of symmetry and also from the center of curvature of each other tube bundle. The corners between the tube bundles may contain fill-in tubes. This allows compact tube packing while preserving relatively uniform fluid velocities.

Abstract: A distributor for distributing sulphuric acid on a packed tower. The distributor has an array of horizontal parallel distributing pipes in a single horizontal plane spanning a tower containing a packing and located above the packing. The pipes extend through the tower shell at one end and are accessible through a clean-out port at the other end. Feed enters the pipes at one end and the clean-out port at the other end permits cleaning without entering the tower. There are holes in the pipes arranged in a number of rows each angled downwardly. Each hole has a simple corrosion resistant insert to protect against hole erosion.

Abstract: A continuous process for the generation of sulphur trioxide from oleum suitable for use in the sulphonation of organic compounds which comprises continuously introducing oleum feed to a sulphur trioxide desorption tower; continuously introducing a recycled dry feed air stream to said desorption tower, whereby a gaseous mixture of sulphur trioxide in air is produced; collecting spent oleum from said desorption tower; introducing said gaseous mixture to a sulphonation reactor; and recycling spent gaseous mixture from said reactor to said desorption tower as said feed air stream. The process offers reduced environmental pollution and operating costs.

Abstract: An absorption tower for absorbing sulphur trioxide in sulphuric acid having distinct upper and lower packed absorption zones wherein substantially all of the sulphur trioxide is absorbed by the sulphuric acid in the lower zone, while in the upper zone the depleted gas stream is significantly cooled. The two zones receive feed acids of different temperatures and different acid irrigation rates. The tower allows of improved energy recovery while providing for environmentally acceptable emission standards.

Abstract: A combined sulphur burning furnace and water-cooled boiler arrangement for producing a cooled, gaseous sulphur dioxide-air mixture in which the furnace is located below the boiler tubes arrangement in a vertical, cylindrical shell. The hot gases produced in the furnace exit axially into an upper chamber defined by the water-tube arrangement and pass through the cooling water-tube arrangement in radial outward flow to an outer chamber provided with cold-side by-pass control means and then exit the shell. The apparatus provides for savings in ducting, foundations, piping and the like; and permits more efficient sulphur burning and cooling.

Abstract: In a system using the double absorption process for sulphuric acid manufacture, a single acid circulation system and a single cooler are employed. Acid from the exit of the air drying tower and final absorber tower are mixed in a common reservoir, while acid from intermediate absorber tower is discharged to a separate reservoir. Acid from the common reservoir is split between the intermediate and final absorber towers and product line. Acid from the separate reservoir is cooled and split between the drying tower and intermediate absorber tower. The circulation arrangement reduces the cooling to one relatively high temperature location and simplifies acid strength and level control. Only half of the bulk of the circulating acid has to be cooled and the effect of seasonal fluctuating temperatures in the drying tower is minimized.

Abstract: In a system using the double absorption process for sulphuric acid manufacture, a single acid circulation system and a single cooler are employed. Acid from the exit of the air drying tower is circulated to and flows through the final absorber where it absorbs the inlet SO.sub.3 gas before joining with the acid from the intermediate absorber. The mixed stream is then cooled and split between the drying tower and the intermediate absorber. The circulation arrangement reduces the cooling to one relatively high temperature location, eliminates the transfer of SO.sub.2 to the effluent gas from acid in the normal single system, and simplifies acid strength and level control.

Abstract: Process for the production of liquid sulphur dioxide in a sulphur dioxide facility forming part of a sulphuric acid plant wherein a portion of the sulphur dioxide produced in a sulphur burning furnace is directed to a sulphur dioxide liquefaction means and the resultant tail gas is recycled to the furnace. Relatively high sulphur dioxide concentrations are maintained in all parts of the sulphur dioxide production cycle allowing higher strength sulphur dioxide gases to be generated without overheating the furnace and also lower power requirements in the sulphur dioxide liquefaction step.

Abstract: A process for producing concentrated sulphuric acid from a hot gas stream comprising water and sulphur trioxide which process comprises feeding a first portion of said gas stream through a first sulphur trioxide absorption zone and a second portion through a second sulphur trioxide absorption zone; feeding a recycled sulphuric acid stream to said first sulphur trioxide absorption zone whereby substantially all of the sulphur trioxide and sulphuric acid are removed from said first portion of said gas stream to produce an enlarged sulphuric acid stream; recycling a first portion of said enlarged sulphuric acid stream through said first sulphur trioxide absorption zone; feeding a second portion of said enlarged sulphuric acid stream to said second sulphur trioxide absorption zone; and collecting sulphuric acid product from said second sulphur trioxide absorption zone; wherein the ratio of gases to sulphuric acid in said second sulphur trioxide absorption zone is such that the sulphuric acid product leaving said

Abstract: In conventional processes for manufacturing phosphoric acid, sulphuric acid is reacted with phosphate rock to produce weak phosphoric acid which is concentrated using steam from the associated sulphuric acid manufacturing operation. Low grade heat from the absorbers and drier of the sulphuric acid manufacturing plant has been wasted. According to the invention waste heat from the drier and one or more absorbers of the sulphuric acid manufacturing plant is used in all the evaporators of the phosphoric acid plant. The evaporators all operate at low pressures and their heaters are arranged in series, to enable the heat to be used at the relatively low temperatures available. The valuable steam is thus freed for other uses.

Abstract: A heat exchanger having a disc and doughnut baffle configuration, in which the tubes are laid out in a set of concentric rings. Each ring of a set contains the same number of tubes as each other ring of the set, and the tubes in each ring are spaced uniformly apart. Each tube in each ring is located circumferentially midway between the two adjacent tubes of each neighboring ring and is separated from each of the two adjacent tubes in each adjacent ring by a ligament distance h. The distance h is held constant for all tubes in the set, by varying the radial spacing between rings, and the distance between any two adjacent tubes in any ring of the set is made greater than or equal to 2 h. The ligament gaps h which are constant therefore determine the minimum flow area between adjacent rings, and therefore the mass flow velocity through the tube bundle is constant.

Abstract: In a process for manufacturing sulphuric acid by catalytic conversion of gaseous sulphur dioxide to sulphur trioxide in the presence of dry air and under high pressure, the improvement comprising feeding the converted gas stream under high pressure to an absorbing unit, circulating essentially sulphur dioxide-free sulphuric acid through the absorbing unit to absorb the sulphur trioxide and unconverted sulphur dioxide from said converted gas stream, depressurizing the acid, simultaneously stripping the sulphur dioxide from the acid by means of air or a sulphur dioxide-free gas and removing moisture from said air or sulphur dioxide-free gas by means of said acid, cooling the resulting essentially sulphur dioxide-free acid and recirculating at least part of it to the absorbing unit. In a preferred embodiment, the process comprises the additional step of condensing part of the sulphur trioxide and unconverted sulphur dioxide constituting the converted gas stream and feeding the remainder to the absorbing unit.