This work provides an experience-based review of how sulfuric acid plants work, how they should be designed and how they should be operated for maximum sulfur capture and minimum environmental impact. Using a combination of practical experience and deep physical analysis, Davenport and King review sulfur manufacturing in the contemporary world where regulatory guidance is becoming ever tighter and where new processes are being required to meet them , and where water consumption and energy considerations are being brought to bear on sulfuric acid plant operations. This 2e will examine in particular newly developed acid-making processes and new methods of minimizing unwanted sulfur emissions.
The target readers are recently graduated science and engineering students who are entering the chemical industry and experienced professionals within chemical plant design companies, chemical plant production companies, sulfuric acid recycling companies and sulfuric acid users. They will use the book to design, control, optimize and operate sulfuric acid plants around the world. Seller Inventory EOD More information about this seller Contact this seller 1. Published by Brand: Elsevier About this Item: Brand: Elsevier, Pages are intact and are not marred by notes or highlighting, but may contain a neat previous owner name.
The spine remains undamaged. More information about this seller Contact this seller 2. Published by Elsevier About this Item: Elsevier, Condition: Used: Good. More information about this seller Contact this seller 3. About this Item: Elsevier , Sulfur Burning 4. Metallurgical Offgas Cooling and Cleaning 5.
Regeneration of Spent Sulfuric Acid 6.
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SO2 Oxidation Heatup Paths Cooling 1st Catalyst Bed Exit Gas Optimum Double Contact Acidmaking Enthalpies and Enthalpy Transfers Control of Gas Temperature by Bypassing H2SO4 Making Acid Temperature Control and Heat Recovery Sulfur-from-Tailgas Removal Processes Minimizing Sulfur Emissions An exceptionally corrosive and dangerous acid, production of sulfuric acid requires stringent adherence to environmental regulatory guidance within cost-efficient standards of production.
This work provides an experience-based review of how sulfuric acid plants work, how they should be designed and how they should be operated for maximum sulfur capture and minimum environmental impact. Using a combination of practical experience and deep physical analysis, Davenport and King review sulfur manufacturing in the contemporary world where regulatory guidance is becoming ever tighter and where new processes are being required to meet them , and where water consumption and energy considerations are being brought to bear on sulfuric acid plant operations.
This 2e will examine in particular newly developed acid-making processes and new methods of minimizing unwanted sulfur emissions. The target readers are recently graduated science and engineering students who are entering the chemical industry and experienced professionals within chemical plant design companies, chemical plant production companies, sulfuric acid recycling companies and sulfuric acid users.
These require careful control of the acid temperature and the acid velocity in order to minimize corrosion. The equipment to provide the anodic passivation is expensive.
Past practice with the aforementioned types of heat exchangers has been limited to rejecting the heat into cooling water or recovering heat in a low level form such as hot water for boiler feed or district heating. Efforts have been made in the past to recover the heat generated when the sulfur trioxide is absorbed into sulfuric acid.
Patent 2,, describes an apparatus for condensing sulfuric acid. The ceramic tube material is used in contact with the sulfuric acid to prevent corrosion; however, a metallic tube is used concentrically about each ceramic tube to prevent mechanical stress and breakage of the ceramic tubes. The cooling medium, a high boiling point oil or boiling hot water, is allowed to become heated to high temperatures such as would be present in a steam boiler. When operated in this manner, the patent states that approximately 1.tornado.burnsforce.com/sienta-gua-de-estudio.php
Sulfuric Acid Manufacture
The heat exchangers are lined with, or constructed of, materials which are resistant to corrosion by the hot, concentrated sulfuric acid such as ceramic materials and porcelain, metals such as steel coated with polytetrafluoroethylene or other corrosion-resistant materials, or metals such as silicon iron and nickel alloys. The heat created by formation of sulfuric acid and the heat released by condensation is utilized to create high pressure steam which may be utilized as a source of power.
The British Patent also discusses recovery of the sulfuric acid in a more concentrated form. Only in the final condensation after completion of the conversion of sulfur dioxide to sulfur trioxide is the remaining sulfur trioxide condensed in the presence of a sufficient excess of steam to insure that substantially all of the sulfuric trioxide is removed from the gas stream. Both U. Patent 2,, and British Patent 1,, teach methods of recovering energy from the sulfuric acid process.
However, both patents require the use of exotic materials of construction and emphasize the use of ceramics, porcelain materials, coated metals, brittle metals such as silicon iron, and expensive nickel alloys for construction to prevent rapid corrosion and failure of the equipment. It is an object of this invention to provide a method for the recovery of heat which is now lost to cooling water in the sulfuric acid process. It is a further object of this invention to provide a method for recovery of the heat created in the sulfuric acid process when sulfur trioxide is absorbed into sulfuric acid.
It is yet another object of this invention to provide a method for the absorption of sulfur trioxide into hot, concentrated sulfuric acid while greatly reducing the corrosive effect of the sulfuric acid. It is yet another object of this invention to provide a method for recovering the heat of absorption of sulfur trioxide in sulfuric acid at a higher temperature level than has heretofore been practicable.
An additional object of this invention is to provide a heat recovery system consisting of a heat recovery tower, heat exchanger and associated equipment such as pumps and piping for use in a sulfuric acid plant which may be constructed of cost effective alloy materials rather than the porcelain, ceramic, and coated materials heretofore proposed for high temperature operation, all of which have mechanical, heat transfer and economic limitations. These and other objects are obtained through a novel process in which the sulfur trioxide passing from the converter in a sulfuric acid plant is absorbed into hot concentrated sulfuric acid in a heat recovery tower and the heat is recovered for useful purposes in a heat exchanger.
The heat recovery tower has top and bottom inlets and top and bottom exits. The sulfur trioxide containing gas stream from the converter, after being cooled, enters the heat recovery tower through the bottom inlet and flows upward through the tower and the hot sulfuric acid stream enters the heat recovery tower through the top inlet and flows downward through the tower.
The acid concentration is defined as being the weight percent of sulfuric acid. The counterflow of the gas stream and sulfuric acid maximizes the driving force for efficiently absorbing the sulfur trioxide into the sulfuric acid. Cocurrent flow of gas and acid can be utilized, but is less efficient. The absorption of sulfur trioxide into sulfuric acid is a process which is known to those having experience in the manufacture of sulfuric acid and will thus not be further described. This process will be referred to herein as the absorption of sulfur trioxide into sulfuric acid and the heat generated by the process will be referred to as the heat of absorption.
The heat of absorption includes the heat liberated when water is added to dilute the recycled sulfuric acid, a process step which may occur within or external to the heat recovery. After the absorption of sulfur trioxide, the sulfuric acid stream passes through a heat exchanger wherein the heat of absorption is recovered through heat exchange with other fluids. It is desirable that the heat exchanger be fabricated from a metal to facilitate the transfer of heat from the sulfuric acid stream to other fluids. It has been discovered that certain alloys exhibit excellent corrosion resistance in the concentration range previously defined.
Stainless steel alloys are generally superior to high nickel alloys. Excellent corrosion resistance has been found , for selected stainless steel alloys with austenitic, ferritic or duplex structures.
Thirty alloys were tested at service conditions typical of the heat recovery system. It has been determined that the corrosion resistance of these alloys can be characterized in terms of the percentages of major alloying constituents. The alloys best suited for service in this heat recovery system had compositions which gave a corrosion index CI greater than In a conventional sulfuric acid plant the heat of absorption of sulfur trioxide into sulfuric acid, is lost to cooling towers. By use of the process and apparatus of this invention, a high percentage of this previously lost energy may be recovered and profitably used.
The heat may be used, for example, to produce low pressure steam for process heating or to power a turbogenerator for the generation of electricity. In a tonne per day sulfur burning sulfuric acid plant approximately 6 megawatts of additional electrical power can be produced from the heat recovered in the heat recovery tower.
Figure 1 illustrates a process flow diagram for a sulfuric acid plant which includes the apparatus of this invention. The sulfuric acid process is well known; thus, portions of the sulfuric acid plant will not be described in detail herein. The drawing shows a sulfuric acid plant which burns sulfur to supply the gas stream containing sulfur dioxide to the sulfuric acid plant.
Looking now at Figure 1, blower 12 supplies air through drying tower 14 to the sulfur burner 10 in which the sulfur is burned, to provide a gas stream containing sulfur dioxide. The sulfur dioxide laden feed gas stream exits from the sulfur burner 10 and passes through a first heat exchanger 22, before entering the converter The feed gas is cooled in first heat exchanger 22 to a temperature near the desired inlet temperature to the converter.
First heat exchanger 22 is used to generate steam for driving a turbogenerator 23 for the generation of electrical power, but other uses are also practical. Converter 30,a vessel for the catalytic conversion of sulfur dioxide into sulfur trioxide, typically has a plurality of catalyst beds which are divided into a first oxidation stage 32 and a second oxidation stage Between any two catalyst beds there is heat exchange to remove. These heat exchangers are not shown in Figure 1. In a typical sulfuric acid plant, between the first oxidation stage 32 and the second oxidation stage 34 the gas stream passes through an interpass absorption tower to remove the sulfur trioxide from the gas stream to provide a gas stream to the second oxidation stage 34 that is lean in sulfur trioxide.
The oxidation reaction is a reversible reaction which approaches an equilibrium; thus, some of the sulfur trioxide must be removed from the gas stream to enable the remaining sulfur dioxide to be oxidized easily.
Sulfuric acid manufacture – Davenport & King - PDF Drive
Economizer 54 is used to cool the gas stream exiting from the first oxidation stage 32 to a temperature which is above the dew point of the gas stream. The sulfur trioxide in the gas stream is then absorbed into a sulfuric acid stream and heat is generated by the process. The absorption typically takes place in an absorption tower in which the acid temperature is maintained at a low level, to minimize corrosion of related piping and heat exchangers.
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However, the maintenance of the low temperature in the absorption tower makes it difficult to recover energy in an economically viable manner, that is in a useful form. In accordance with this invention, a heat recovery tower 60 is provided downstream of the economizer The cooled sulfur trioxide laden gas stream enters the the lower portion of heat recovery tower 60 and flows upward through a bed of packing While this description is of a packed tower, it is contemplated that other gas-liquid contacting devices such as tray towers can be used.