Regenerating tower
Air compressor
Air compressor outlet (After-cooler is bypassed)
Drying tower
Cooler assembly
HOC dryer intlet
Hot air
Adsorber-2
Adsorber-1
Exchanger
Moist air
Moisture separator
Dry air
HOC dryer outlet
Filter
Figure 3 HOC-type compressed air dryer schematic
Conclusion India, the world’s third largest energy consumer, albeit with very low per capita figures, has shown tremendous zeal and commitment as part of international communities’ efforts in combating climate change. Towards this end, the honourable PM at COP26 presented Nationally Determined Contribution (NDC) as five nectar elements (Panchamrit). The five elements briefly are: u Reach 500 GW non-fossil energy capacity by 2030. v 50% of its energy requirements will be from renewable energy by 2030. w Reduction of total projected carbon emissions by one billion tonnes from now to 2030. x Reduction of the carbon intensity of the economy by 45% by 2030, over 2005 levels. y Achieving the target of net zero emissions by 2070. Although transitioning to complete renewables or zero-carbon sources is the aim as technologies mature and become cost-competitive, it is prudent in the interim to focus on opportunities towards improving the energy effi - ciency of existing refinery facilities. Such improvements are key to carbon emissions reduction as enshrined in the third and fourth elements. In the present opportunity, emphasis is being placed on more effective energy usage in the hydrocarbon process - ing industry. As a consequence, areas in which energy is wasted are being closely monitored, and methods for energy recovery are being investigated. Global average planet temperature has increased by 1.5°C from pre-industrial times. India has made signifi - cant efforts towards sustainable growth and outlined its
baseline performance data of the instrument air dryer, which is designed for a fixed cycle time, is described as follows: Baseline definition: instrument air dryer with fixed cycle time • No. of instrument air dryers: 4 @ 5,000 Nm3 /hr • Heater rating per dryer: 160 KW • Adsorption cycle time: 8 hr • Regeneration cycle time: 8 hr (6 hr heating + 2 hr cooling) • Operating hours per annum: 8,760 hr • No. of adsorption cycles per year: 8,760/8 hr = 1,095 cycles One thousand ninety-five adsorption cycles in a dryer will require 1,095 regeneration cycles. Post-retrofit with dew point feature: Dryer performance improvement By employing the ‘dew point demand controller’ in the dryer system, the adsorption time is expected to be prolonged by one to three hours. The corresponding reduction in the regen- eration cycle and power savings are tabulated in Table 1 The data in the bespoke base case table validates the benefits of prolonging the adsorption cycle by one, two, and three hours. It infers that there is an appreciable amount of energy savings with the implementation of the dew point feature in the instrument air dryer. Figure 4 illustrates energy savings (in %) achieved with an increase in cycle time. By employing the ‘dew point demand controller’ in the dryer system, the average increment in adsorption time will be in the order of 1.5 hours for at least the initial three years of adsorbent life.
Post-retrofit with dew point feature: Dryer performance improvement
Parameter
Base case
Post-retrofit with dew point feature (adsorption cycle prolonged by)
(fixed cycle time)
1 hour
2 hours
3 hours
Regeneration cycle/annum Reduction in regen cycle
1,095 Base 1,051 Base
973
876
796
Base –122
Base – 219
Base – 299
Power for one dryer, MWhr/annum Power savings per dryer, MWhr/annum
934
841
764
Base – 117
Base – 210
Base – 287
Table 1
80
PTQ Q1 2025
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