Compressed air is used in industry for instrument operation. Compressed air is also used for process purposes like intermingling with products, sulphonation, drying of polyester chips and other products.
Air has moisture at all stages. Air also has dust, oil, grease etc. These vary from country to country. However in India following limits are generally specified.
Moisture : Dew point required: -40 Deg. C to -80 Deg. C at atmospheric pressure . Dust : Between 1 microns to 5 microns Oil, grease : Less than 1 ppm.
Filtering or coalescing does removal of dust. For removal of oil/grease activated carbon filter is used. Moisture removal is done by knocking down the moisture in separator (Knock out drum) and then passing the air through a chiller for smaller dew point. However, desiccants are used for dew point of below – 40 Deg. Most common desiccants are as follows:
Organic vapour like benzene, toluene, acetone, and alcohol are many times allowed to escape to the atmosphere either during process or loading or transfer. Process Description:
Organic vapours along with air are sucked in to the carbon bed adsorbers. If the concentration is high, then a prechiller is used to remove excess organic solvent by chilling. The carbon bed adsorbs the organic matter and the air is vented out. Adsorption is a complex phenomenon and depends on:
Pressure
Temperature
Inlet concentration
Bed parameters
Velocities
Dynamic efficiency of adsorbent
The adsorbent used is activated carbon in granular forms.
Regeneration of carbon bed is done by using live steam or using hot nitrogen. The organic solvent evaporates and is condensed and separated by decantation.
Regeneration can also be achieved by using water ring vacuum pump followed by adsorption of the vapour in lean solution.
If the recovery desired is up to 70% then by simply chilling the vapour, solvent can be recovered. For still better results, cold adsorption with vacuum regeneration in employed where the recovery is up to 99%.
Systems supplied so far:
Benzene Vapour Recovery Systems : For tank farm for Kothari Sugar, Chennai.
Benzene Vapour Recovery Systems: At the benzene gantry loading 550 metric tonnes per day benzene for Bharat Petroleum Corp. Ltd. Mahul, Mumbai. Asia’s first BVRU installed in 2005.
Toluene Vapour Recovery Systems: For Asian Paints Ltd. at Patencheru, Ankleshwar and Bulandsahar. Three systems operational from 2001.
These are used for heat exchange of gaseous mediums operating at lower pressures with either hot medium like steam, thermal fluid or cold medium like water, chilled water. Finned tubes are extended heat transfer surfaces, and considerable reduction in area is achieved. These can also work in ambient air by convection for cooling of gasses/hot fluid. We can supply heat exchanger with wire wound finned tubes. Wires are made in loop forms and wound on the tubes. These are held to the surface of tubes by means of tension wires and either soldered or brazed. The contact between tube and fin is complete unlike crimped fins where a small air gap reduces the heat transfer coefficient. The fin structure is such that high turbulence is achieved on the fin size, which enhances the heat transfer coefficient.
We can give the tube/wires in any combination of material. We can also offer other finned tubes design, like G type, L type or integral fins.
We have the process data from the original finned tube manufactures and can offer the heat exchangers with complete process and mechanical design.
The manufacturing is carried as per TEMA and API- 660 The design of the finned tube cooler is performed using Acol or HTFS or Aerotron of B-Jack, both parts of ASPEN software.
The mechanical design is carried out using ASME Sect.VIII Div.1 or API-660.
This is similar to air drying plant except the process may not be purely physical separation and may require close monitoring. The regeneration process is most important and may be done using dry gas itself. Carbon dioxide requires to be dried to a dew point of –700C to –800C else even a small amount of moisture will choke the pipe line. Hence a molecular sieve bed is recommended. For LPG / natural gas dew point requirements are upto –1000C and molecular sieve beds are used.
All organic solvents have a small water content. The water content varies from 800 ppm in case of solvents like Benzene, Toluene, etc. to 13% w/w in the case of ethanol. This water needs to be dried to the extent of 5 to 10 ppm. Azeotropic distillation was the process employed which is time consuming and expensive. In this last 25 years, dessicant based drying has become a popular option. The wet solvent is passed through a bed of molecular sieve which renders the liquid dry. The method of drying the liquid is known as adsorption. The normal adsorption cycle is 8 hours. After 8 hours, the bed, now saturated with water is taken for regeneration. The regeneration is a method of removal of moisture from the molecular sieve. This can be achieved by decreasing the pressure in the bed (pressure swing) or by heating the bed to a temp. of 1800C to 2000C (thermal swing). Thermal swing provides better regeneration. However in the case of ethanol, pressure swing is preferred. In the case of thermal swing, the bed after heating needs to be cooled to a temp. of 400C. A write up on this will be provided on specific request along with PFD. We are the only company in India having dried a number of solvents.
Pressure vessels are storage tanks that are designed to operate at pressures above 15 psig.
Design Code : ASME Sect. VIII Div.1, Div.2, AD5500 & IS 2825.
Calculations done on PVEllite and drawings on AUTOCAD 2007. Material – Carbon Steel, all types of stainless steel, alloysteels and Aluminium.
Range : upto 30m3.
Weight : 30 M Tonnes.
Dia. 4500mm x length 15000mm
Thickness upto 60mm
Statutory approval : CCOE Nagpur.
Special Equipment : We are the only Licensee to design, manufacture and supply Lithium Transfer tanks in India. We have supplied 300 Nos. pressure vessels to FMC (India) Pvt. Ltd. along with equipment for the complete dilution plant.
We carry out the thermal design using software’s like ASPEN-HTFS (both TASC and Hetran module) Complete thermal calculations are provided including vibrations. Mechanical design is carried out using ASME Sect.VIII Div.1. latest edition and addendas. These calculations are carried out using ASPEN (TEAM module) and PVElite. We can also provide thermal calculations as per Chemcad, Design II, Hysis and can simulate the heat exchangers.
We have manufactured heat exchangers of the following types:
Fixed Tubesheet
Full Floating
Packed floating head
U Tube
Double Pipe
Hair Pin
Max. Area – 200 m2
Max. Dia. – 1600 mm
Max. Tube Length – 9000 mm
Max. Weight – 13 metric tonnes
Max. Design Pressure – 30 Kg/cm2g
Max. Design Temp. – 6500C
Max. Tube Dia. – 90 mm
Material – Carbon Steel, Clad Steel, SS304, 316, 316L, SS321
Mastech Machinery Supplying and manufacturing industrial dryers such as pharmaceutical fluid bed dryers, fluid bed dryers, chemical fluid bed dryers, tray dryers, electric drying, drying, stainless steel drying and fully automatic drying.
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