2013 Kumareswaran Design of a Plant to Manufacture Sulfuric Acid from Sulfur
In accordance with requirements to be fulfilled under module CH 4202 (Comprehensive Design Project), Group 01 was tasked with designing a plant to manufacture Sulfuric acid from Sulfur. The report that follows contain a detailed methodology of the approach adopted in this regard- which includes a comprehensive survey of available literature and an overall selection of a manufacturing process; the feasibility of the design in terms of safety, environmental and economic aspects; a detailed balance of mass and energy of process and utility flows required, and a set of diagrams depicting the process flow and flow sheets of mass and energy.
The initial review of literature revealed that the current production capacity of Sulfuric acid was around 200 million tonnes per year, and is currently growing at about 1.2% per year. A majority of its production is driven towards fertilizer and related products. Based on local market demand projections, the group was able to deduct that if the Sulfur based effluents that are currently disposed from the Ceylon Petroleum Corporation refinery at 25 MTPD were to be completely regenerated in the form of Sulfuric acid by installing a manufacturing plant of the nature proposed in this report, not only could the acid needs of the local industry be completely met, Sri Lanka could become a net exporter of Sulfuric acid, with over 50% of production still in excess.
The production was scaled up to correspond to 35 MTPD of Sulfur input, to account for future growth in demand for oil refining in Sri Lank (and the resultant petrochemicals), as well as increased local demand for Sulfuric acid itself which is likely to occur following the production of sulfuric acid locally. It was calculated that the plant could be constructed at a cost of USD 7.6 Million in 2013, and have operating costs up to USD 6.7 million each year at full capacity, which was adjusted for inflation which the group took to be around 10%.
The group recommends that by 2018 the plant could be run at full capacity at which point, with the forecast rise in price per kg of Sulfuric acid, sales would produce up to USD 13.6 Million. In this set up the plant is expected to start accumulating profits in the first quarter of 2020, delivering a pay back of 7 years and 1 month. In terms of economic feasibility, the project could be concluded as being viable; however, the group recommends that a more exhaustive calculation procedure be used to estimate cash flows if closer inspection is required with reduced assumptions.
ivBased on the literature review, it was revealed and concluded by the group that the double contact double absorption process (DCDA) is an optimum choice for a process to manufacture Sulfuric acid in terms of its economic feasibility, product purity and environmental impact. The group in its analysis for a suitable site has selected the general area of Sapugaskanda as a suitable location for installation of the plant, taking into account its close proximity to the CPC as well as the Colombo harbor as well as established infrastructure and availability of water and other utilities.
Among the findings made by the group during the mass and energy balance was the fact that Oleum could be used as a drying agent (a form of chemical drying) to dry air and Sulfur Dioxide streams instead of jacketing with steam . However, the group cautions that using Oleum/Sulfuric acid would initially prove questionable as steady state flow requirements were found to exceed steady state production of Oleum/ Sulfuric acid. Upon reaching steady operation with abundant storage capacity, however, the group recommends that Oleum/Sulfuric should be used to chemically induce moisture removal.
The group was able to reveal from the mass and energy balance that the cooling utility would amount to 2.6 MW requiring 260 MT/hr of cooling water. However, the group has identified several potential options for energy recovery within the plant itself, and if performed this utility could be optimally reduced up to 700 MW or 60 MT/hr. It is recommended that a detailed pinch analysis be conducted to determine this figure more accurately. Though energy could be recovered as saturated steam, the group has identified that due to the magnitude of the temperatures required for process heating, the saturated steam recovered would have to be superheated first. Alternatively it is recommended by the group is that thermic fluids be used in this regard, while the excess steam capacity could be utilized for in house generation of power. The group recommends the conduction of a proper cost benefit analysis comparing the capital costs of installing a power plant and using thermic fluid for process heating, as opposed to those associated with using superheated steam entirely for process heating.
As a concluding remark a reflection on the personal benefits and underlying reasons for performance could be made. The group notes the personal benefits of obtaining valuable insights in to the financial side of process engineering as well as a holistic sense of plant design in terms of conducting mass and energy balances and investigating safety and environmental issues. The group observes that continuous feed back and coordination being the underlying current of successful performance of a project of this magnitude.