Sulphuric Acid Plant Research Articles

Aspen Optimization of Heat Exchange Network for the Conversion System of Sulphuric Acid Made with the Sulphur

This paper takes the conversion system of sulphuric acid plant made with the sulphur as research object, utilizes Aspen Energy Analyzer software and pinch technology to improve and optimize for the current heat exchange network of conversion system. The heat exchange network optimized by Aspen software is under the premise of reaching the requirement of heat exchange, its heat transfer area, utilities and operating cost reaches the minimum, achieving energy saving, and it provides a new approach for the optimal design of heat exchange network.

Thermodynamic Evaluation of Energy Integration and Cogeneration in Ammonium Nitrate Production Complexes

The energy integration and cogeneration are commonly used in large nitrogen and phosphorous fertilizer production complexes for many years, due to the presence in the same site of production processes with highly exothermic main reactions, e.g. nitric and/or sulphuric acid plants and heat consuming processes, e.g. urea, ammonium nitrate, wet phosphoric acid, complex fertilizers, etc.) (Kongshaug, 1998). In this work the exergy method is used to analyze the dependence of the primary energy consumption and GHG emissions in the ammonium nitrate production on basic parameters of the subsystems (ammonia, nitric acid and ammonium nitrate production units and CHP) and on the allocation of the additional fuel (natural gas) burning and steam generation. The results show that the most effective allocation scheme depends on the relative efficiencies of the subsystems as well as on the boundary conditions and regulations of the GHG emissions.

Electrochemical method for sulphur dioxide removal from flue gases: Application on sulphuric acid plant in Tunisia

Abstract This article presents an electrochemical method for sulphur dioxide removal; the idea consists to couple the phenomenon of electrolysis upstream to the sulphuric acid plant. Otherwise, this proposition consists in modifying the hybrid cycle Westinghouse by the elimination of the sulphuric acid decomposition stage, which corresponds to 61% of the energy distribution of this cycle. The step of the decomposition is replaced by the exploitation of the quantity of sulphur dioxide emissions SO2 stemming from the process of sulphuric acid H2SO4 production. The industrial complex of Gabes in South Tunisia is selected to be the case study complex. In fact, most industries are chemical oriented, the fast growing numbers of H2SO4 factories have resulted in fairly serious air pollution, especially sulphur dioxide SO2 pollution. To confirm the efficiency of this process, a mass balance study was made on the sulphuric acid plant, which used a double contact/double absorption process; this study demonstrates that this new method can treat 8 t d−1 of sulphur dioxide, recover 12 t d−1 of sulphuric acid of title 50% and produce 6889 m3 d−1 of the hydrogen. This idea can achieve economical and environmental benefits. It is concluded that the usage of this electrochemical process can significantly reduce the SO2 air pollution in Gabes (South Tunisia) by the elimination of 46.94 t d−1 of SO2. The results obtained are ambitious for future application of the new process, which can succeed in the realisation of 3.92 million dollars of gain every day.

Utilization of waste heat in the desalination process

Several chemical, petroleum, and power plants emit water streams containing significant amounts of waste energy. A considerable amount of heat is developed in the sulphuric acid plant during sulphur burning, converting, drying and absorption stages. For example, one sulphuric plant produces cooling water at approximately 34°C. Approximately 65 MW of heat is created in a 1,000 t/d sulphur burning acid plant. This energy can be used to provide heat for desalination plants that are constructed near these sites. The most widely used desalination processes are membrane separation via reverse osmosis (RO) and three types of thermal desalination — multistage flash distillation, multiple-effect distillation, and multiple-effect distillation with thermal vapor compression. A detailed discussion on the technical developments and comparisons in the use of waste heat recovery for the three types of thermal desalination is presented. Various economic parameters used in calculating the unit production cost are presented as well as a comparative analysis of thermal desalination economics and the best utilization of waste heat.

New pumps for Zambian sulphuric acid plant

The global demand for copper has increased. As a result, a new sulphuric acid plant is being built in the Zambian Copperbelt to help with the refining of the copper mined in that region. APE Pumps, based in South Africa, supplied 18 pumps to help produce the acid which refines the copper and improve production.

Control Analysis of the Operation of a Copper Smelter and Two Sulphuric Acid Plants

A control strategy analysis for the operation of a copper smelter and two different acid plants is performed. The gas, reach in sulphur dioxide and dust, is generated by the combined operation of two Teniente Converters and four Peirce Smith converters. The gas is treated to reach certain temperature and solid contents, and then distributed into two sulphuric acid plants, where afer a cleaning stage; the sulphur dioxide is catalytically converted into sulphur trioxide that finally is absorbed in concentrated sulphuric acid. The main goal of this project is to increase the acid plants availability, and therefore to increase copper production, by decreasing the occurrence of environmental events and acid plant shutdowns. Preliminary results are discussed. Copyright © 2004IFAC

A simulation model of a sulphuric acid production process as an integrated part of an energy system

Power plant process simulation software is well-suited for the modelling of energy systems and more importantly, tools for analysing the energy efficiency are often built into the software. This work presents the development of a simulation model for a sulphuric acid plant using a commercial software package for power plant process simulation. This will be of value to for instance small consultant and engineering companies involved with audits and analysis of energy systems. For small sized companies the cost of acquiring and maintaining many different specialised software packages will be noticeable. However, companies involved with audits and analysis of energy systems will in most cases have access to at least one software package for power plant process calculations. The use of this kind of software for also modelling chemical plants would be valuable to these companies. The results of this work shows that it is possible to use an inexpensive but powerful power plant process simulation software for modelling a common chemical process as a part of a large energy system.

How CAPE tools can contribute to process sustainability

The concern of the EFCE for sustainability. Four recent case studies to illustrate how CAPE tools contribute to process sustainability: (1) ultimate plant operation at Wacker-Chemie (DE), (2) development of a new sulphuric acid plant with Air Liquide (FR), (3) plant retrofit for CO 2 abatement at Kemira (BE), (4) insertion of a new plant in an existing Solvay industrial site (Asia).

Heat recovery from sulphuric acid plants for seawater desalination

It is a well known fact that sulphuric acid production is a highly exothermic process. In that sense, combined with the increased energy cost, surprisingly little heat is recovered from the process. Most often the heat is just cooled off by means of seawater or in air coolers. When recovering heat from the absorption and drying tower coolers, only minor changes to the process are needed. With plate heat exchangers (PHEs), the heat in the sulphuric acid can be recovered with negligible temperature losses and minimum space requirements. The PHE can take crossing temperature programs temperature pinches of less than 5°C and still having k-values of about 2500 kW/(°C·m 2). The heat recovered can be used for district heating of cities, boiler feed water preheating or as heating media in connected processes or adjacent plants. A very interesting use of this heat is for the production of fresh water by desalination of sea or brackish water, when the sulphuric acid plants are situated close to the coast such as several installations in Middle East and Northern African countries. The thermal duties in the acid coolers are very well adapted for heat recovery in combination with production of fresh water by means of multi effect distillation (MED). Evaporation temperature in a MED system is typically lower than 80°C, and the heating energy required is in the range of 60–360 kWh per produced m 3 of fresh water, depending on the number of effects. There are many advantages, both installation-wise and operation-wise, using PHE for highly efficient sulphuric acid heat recovery and falling film plate evaporators for the thermal surface in the desalination system. The high k-value of the plate system gives smaller heat transfer areas and compact installations.

Pulmonary CT Findings in Acute Mercury Vapour Exposure

AIM: We describe the pulmonary computed tomography (CT) findings in acute mercury poisoning.MATERIALS AND METHODS: Initial (n= 8) and follow-up (n= 6) chest CT examinations in eight patients exposed to mercury vapour while cutting pipes in a sulphuric acid plant were reviewed. Of the eight patients, two were asymptomatic and had normal CT results, two were asymptomatic but had abnormalities on CT, and four had both acute symptoms and positive CT results. The patients were all men whose ages ranged from 37 to 54 years (mean, 49 years).RESULTS: Poorly defined nodules were present in five of six patients with positive CT findings, present alone in two patients or as part of a mixed pattern in three. They were random in distribution. Alveolar consolidation (n= 3) and areas of ground-glass opacity (n= 4) were observed and were more prominent in the most severely affected patients with the highest blood and urine level of mercury, predominantly in the upper and/or middle zone. These abnormal findings on CT resolved with (n= 1) or without (n= 5) steroid therapy. Pathological findings (n= 1) demonstrated acute interstitial changes predominantly with oedema.CONCLUSION: We report CT findings in eight patients acutely exposed to mercury vapour. The pulmonary injury was reversible on CT in these cases.Hashimoto, M. (2001). Clinical Radiology56, 17–21.

Unsteady states in metallurgical sulphuric acid plants after SO2 concentration drop in the feed gas

AbstractThe paper presents results of dynamic mathematical model simulations for selected two characteristic flowsheets of metallurgical SO2 oxidation plant after temporary decrease of reactant concentration in the feed gas. An analysis of dynamic resistance of the plant for the concentration drop, from the point of view of the dynamic autothermal properties is given.

Mortality and cancer morbidity in workers exposed to sulphur dioxide in a sulphuric acid plant.

To evaluate the risk of non-malignant respiratory disease and tumours at exposure to sulphur dioxide, a retrospective cohort study was performed on a group of 400 male workers, employed for at least six months during the period 1961-1981, in a sulphuric acid factory. Since 1969, fairly extensive measurements have been performed in the respiratory zone of the workers. The median level of total dust, over the years, was 2.2 mg/m3 (time-weighted average), of respirable dust 0.6 mg/m3, of sulphur dioxide 3.6 mg/m3, and of arsenic 11 micrograms/m3. There was a significantly increased total mortality in the period 1961-1985. Applying greater than or equal to 5 years latency period there were 47 observed deaths, giving a standardized mortality rate (SMR) of 1.57 (P = 0.002). The increased mortality was due to violence and intoxication (observed 9, SMR = 2.83; P = 0.006) and cardiovascular disease (SMR = 1.51, P = 0.05). The total tumour morbidity was not increased (observed 17, SMR = 1.17, P greater than 0.5) and there was no rise of either non-malignant or malignant lung diseases. However, there was an increase of bladder cancer (observed 5, SMR = 4.36, P = 0.006).

Controlling SO2 emissions during start-up of multi-bed sulphuric acid converters

The catalytic converter in sulphuric acid plant is normally designed to work high conversions to avoid recycle, and the associated integrated heat recovery system makes the process relatively tightly constrained. Because of this, considerable care is needed during start-up in order to avoid excessive emissions which would fail to satisfy criteria set by the factory inspectorate. For a fast, clean start-up it is necessary to have a detailed appreciation of the reactor dynamics; the simulation developed here demonstrates how this can be done. In parti cular, it is possible to explore the level of detail necessary to enable operational policies for start-up to be explored. It is shown that, by suitable programming of the flow rates in the system, appropriate to the initial bed temperatures, clean fast start-ups are possible which avoid excessive stack gas emissions of sulphur dioxide.

Studies on aluminium diffusion treated steel for heat exchanger tubes

Aluminium diffusion treated steel by pack process using ferroaluminium was studied for its heat exchanger tube applications properties. The laboratory and inplant corrosion studies reveal that the diffusion treated low carbon steel is extremely resistant to hot corrosion due to sulphurous gases encountered in heat exchanger tubes of sulphuric acid plants at the operating temperatures. The diffusion treated tubes have shown adequate physical properties for heat exchanger tube bundle fabrication.

The Current State of Automation and Areas for Future Development in the Electrolytic Zinc Industry

Abstract The paper discusses how automation is steadily proceeding throughout all areas of the electrolytic zinc industry. Fluid bed roasters with integral sulphuric acid plants are now on computer control. Highly efficient, continuous leaching and purification stages, with feed-forward predictive and optimisation computer control, precede electrolytic cells with on-stream solution analysers and automatic stripping of deposited zinc. Controlled electric induction furnaces feed continuous casting lines, equipped with automatic stacking and strapping machines, after computer based metal analysis has confirmed metal purity or alloy composition. The paper also discusses the use of computer models tied to process control systems, and the equipment and solution measurements that could be automated with advantage, using modern micro-based controllers and analysers.

Anodic corrosion protection of sulphuric acid plants with regard to the recovery of heat

AbstractAnodic protection makes it possible to keep materials which can be passivated in a “passive” state or to bring them into this state, even in unfavourable conditions.With sulphuric acid concentrations of 93–99% this method permits the use of inexpensive, stainless austenitic steels, e.g. 1.4541 and 1.4591, at temperatures of up to 160 °C. The temperature range from 120 °C to 160 °C, in particular, is suitable for heat recovery.Anodic protection by the APR‐system provides safe and low‐cost protection for air coolers and bare tube coolers in sulphuric acid plants. The results of laboratory, pilot plant and commercial trials show that in this way a safe operation of sulphuric acid coolers is possible on a long‐term basis.

Choice of measured parameters and testing correctness of problem formulation in balancing industrial chemical processes

A computational method suitable for the indirect choice of measured parameters and for testing the correctness of problem formulation in multicomponent mass and enthalpy balances of industrial chemical processes is described. The algorithm is based on automatic generation of an occurence matrix (equation-variable) from a problem-oriented form of input data. A sophisticated logic is used to prevent a generation of rows in the matrix corresponding to dependent equations. Further, the Steward's algorithm is applied to test the solvability of the equation system. Results are obtained in the form of the number of overdetermined equations and underdetermined parameters, as well as a specification of sets with always one parameter redundant or missing. The algorithm was programmed in FORTRAN for the computer ICL 4–72, and has been tested on the sulphuric acid plant.

24 Reactor dynamics and strategies for minimising SO 2 emissions during start-up of a contact sulphuric acid plant

A dynamic simulation model based on ordinary differential equations, which describes the unsteady behaviour of the fixed-bed reactors of a contact sulphuric acid plant, is presented. Simulations to investigate the influence of variable flow start-up and initial fixed-bed reactor temperatures, show that fast start-ups from low temperatures can be achieved without excessive emission of unconverted SO 2 through a suitable manipulation of the sulphur burn-rate.

Collection of atomic mercury by electrostatic precipitators

ELECTROSTATIC precipitators are widely used to remove dust particles from gases and the mechanism of this is well understood. One major application is in the cleaning of a sulphur dioxide produced in smelting of metalliferous sulphide ores before its conversion to sulphuric acid and the precipitated material is often found to contain mercury. We have shown that the concentration of mercury is below the saturation level and therefore present as atoms so the accepted mechanism for solid particle collection is not involved in mercury removal. We have investigated the phenomenon in the laboratory using air as the carrier gas at room temperature, and by large scale tests carried out in an 800 tonne d−1 sulphuric acid plant treating the gases formed by roasting zinc sulphide concentrate. In both types of test a discharge wire and earthed collector tube precipitator configuration was used. In the plant tests the roaster gas contained 9% sulphur dioxide and was saturated with water. In both the laboratory and plant tests the gas streams were unsaturated with respect to elemental mercury vapour.

Selection and Design of Texasgulf Canada’s Copper Smelter and Refinery

M. P. Amsden was born in British Columbia and graduated from the University of British Columbia with a BASe. in mining engineering in 1959. After three years of mill flotation work at Giant Yellowknife Mines Ltd. he joined Lakefield Research of Canada Ltd. as a project engineer. He joined Texasgulf to work on the Timmins metallurgy in 1965 and has been flotation engineer, assistant mill superintendent, mill superintendent, manager of metallurgy, and is now Vice President and Assistant General Manager. Texasgulf Canada is constructing a new copper smelter and electrolytic refinery at Timmins in Northern Ontario. The smelter design is based on the advanced technology of the Mitsubishi Continuous Smelting Process, while the refinery design is based on the Jumbo tank system presently operating in the new No.3 Tankhouse of the Onahama Smelting and Refining Co. Ltd. in Japan. The construction of this smelter-refinery complex is to be done in two stages. First stage construction will be completed in mid-1979 providing an estimated annual productive capacity of 65,000 short tons ofcathode copper. The smelter and refinery along with ancillary facilities are expected to start up in late 1979. Design production should be realized in 1980 . The second stage of plant construction is expected to begin sometime in the early 1980 's. Capacity will then be expanded to 130,000 short tons per year of cathode copper. The second stage smelter expansion will consist mainly of the addition of a second continuous smelting line of furnaces and a duplicate of the sulphuric acid plant. The refinery will be expanded by doubling the number of jumbo tanks and installing some additional electrode handling equipment. . About 18 months after start-up a copper sulfate plant will be incorporated into the refinery. Later, a separate precious metals recovery plant will be constructed. The reasons for phased plant construction were two fold : 1. Due to inflation and rising construction costs, the current capital outlay required for the copper smelting complex is high. It is economically advantageous for Texasgulf to build a smaller 65,000 STPY plant first, which can be expanded at a later date to 130,000 STPY. Concentrates produced in excess of smelter capacity will continue to go to a customs smelter. 2. It is expected that it will be possible to improve on the design features of the second furnace line through experience gained during the operation of the first furnace line. The Mirsubishi process is relatively new and, therefore, offers promise for further development. It is expected that numerous small modifications will be made during the next few years to improve furnace operation. Any significant improvements made in operating technology at the Naoshima smelter and Onahama electrolytic refinery in Japan subsequent to 1977 probably will be incorporated in the new Timmins plant. The results of full-scale smelting and refining tests carried out on Texasgulf concentrates at Naoshima and Onahama in late 1976 have already been incorporated into present plant design.