Page 177 - CW E-Magazine (23-4-2024)

Special Report Special Report

Energy conservation ideas for the chemical, thermal shock or poor workmanship. quently and due to frequent operation large old machines, e.g., compressors,
It is a good practice to measure surface at high velocity, hot condensate fl ow motors, gas turbines, etc., replace old
petrochemical and refi ning units temperature of furnace and boilers perio- through it, as well as presence of iron spare parts with high effi ciency spare
rust, frequency of failure is normally parts to reduce energy footprint and
dically by portable thermometer, pre-
pare temperature contours, identify hot high, leading to either passing of steam improve economics. It is feasible in
INTRODUCTION specifi c energy and water consumption JOY M. SHAH spots and repair refractory lining for through trap or non-operation of trap. many applications.
nergy is always limited in mother targets. improvement in furnace, heaters and The fi rst leads to signifi cant energy
earth. Again higher urbanisa- and integrate with plant steam header boiler effi ciency. loss. Regular monitoring of trap per- EMS-15: Compressors and pumps
Etion leads to higher per capita EMS-1: All the plants of integrated and recover balance heat to produce formance and its repair or replacement are designed for anti-surge fl ow
energy consumption. Therefore, only complex are designed by different refrigeration for heating, ventilation, EMS-8: Boiler drum blowdown is is one of best practices for energy con- requirement or minimum circulation.
way to meet future demand of energy licensors. Licensors optimise their pro- and air conditioning (HVAC). one of the major reasons of energy loss servation. Normally, the trap is not a During the design stage, the designer
is through energy conservation and cess, but some ineffi ciencies remain and is required to control Total Dis- tagged item and are many in numbers. might be careful to ensure that mini-
improvement of energy effi ciency. in-built due to non-availability of heat EMS-4: It is possible to route part solved solids (TDS) as well as silica Tag all the traps, monitor periodically mum energy is wasted to meet this
Higher energy consumption leads to source or sink within the process. Carry of hot condensate directly to deaerator level. TDS goes up due to addition of for proper performance and repair, or requirement. However, in actual prac-
global warming. To keep us cool, it is out pinch analysis or HENA to iden- without cooling and polishing after risk pH control chemicals and silica goes up replace them. In case of frequent failure tice, the fl ow and head might change,
now essential to adopt the practice of tify energy saving opportunities within assessment and analysis of contamina- due to feed silica and cycle of concentra- at some of the locations, identify root leading to excessive anti-surge fl ow or
energy conservation in all aspects of plant as well as by site-wide integra- tion possibility of condensate. tion. Optimising boiler drum chemical cause, check feasibility of eliminating minimum fl ow recirculation. It is best
activities, including, industrial activities. tion. addition and auto control of boiler trap at that location, check for upgrada- practice to check such circulation fl ow
EMS-5: Many furnaces, boilers drum blow down can reduce signifi cant tion of the type of trap, or change and carry out operation at minimum
Similarly, water is a scarce resource EMS-2: Check operating capa- and heat recovery steam generators energy loss and chemical loss. location of trap. Once trap performance circulation fl ow for compressors and
in the world and especially in India. city/load vs. design capacity/load of (HRSGs) are operating at very high monitoring and its maintenance are pumps. Look for provision of auto-
Only 4% of available water in the world pumps, fans and compressors. In case oxygen in fl ue gas due to improper EMS-9: Steam and electrical trac- established, recovery of condensate mation to achieve minimum fl ow, as
is serving 16% of the world’s popula- of large gap, check for use of Variable control of secondary air and high draft. ing is provided to maintain tempera- from steam trap will be possible for and when required.
tion in India. Frequency Drives (VFDs) for reducing Optimisation of excess air in fl ue gas ture of fl uid to avoid congealing or conservation of energy and water.
speed, and, thereby, power consump- by improved secondary air control and solidifi cation. Many fl uid freezing EMS-16: Capacity of reciprocating
In any chemical or hydrocarbon tion. Alternatively, look for reduction draft can lead to signifi cant energy con- points are near ambient temperature. EMS-12: Motor effi ciency deterio- compressors is adjusted to required
complex, energy saving potential exists of impeller size of pump and compres- servation. Caution: Check and arrest In hot weather, this steam or electrical rates over time due to many reasons. It capacity by suction loaders in 2-4 steps.
(see Figure 1). sors or change of blade angle or use leakage of air in convection zone before tracing can be stopped, especially when is good practice to monitor effi ciency Many times the operator does not use
lighter material for fans. optimising excess air. there is continuous fl ow. of motors, especially induction motors, the suction loader’s capacity control
In this series of articles, I have and decide on replacement require- due to fear of failure and capacity con-
identifi ed the most common energy EMS-3: Hot condensate is cooled EMS-6: Stack temperature of fur- EMS-10: Insulation for high tem- ment. Replacement of standard motors trol is done by discharge to suction
and water conservations as well as either in water cooler or air cooler for nace or boiler was designed higher in perature service gets damaged over by newer generation high effi ciency circulation. Provision of step-less
energy and water effi ciency improve- recovery and polishing. Flash this con- old design due to usage of inferior qua- time due to aging or soaking in water, motors can be economical over long capacity control for reciprocating
ment schemes that I have practised for densate to produce low pressure steam lity of fuel. It can also be higher due to although cladding is intact. Measure- run. compressors is one of the solutions for
continuous improvement and meeting (4 kg/cm g or 15 kg/cm g pressure) imbalance of load. It can also be due ment of surface temperature of insula- energy saving. Alternatively, if perma-
2
2
to fouling of convection bank tubes. tion cladding of steam/hot lines and EMS-13: Compression refrigeration nent reduction in capacity is required,
% This is one of the major reasons for low equipment for repair of the same is one units consume high energy. Monitor there are many levers available.
100 effi ciency. When fuel is changed to low of the best practices. Normally, we mea- effi ciency of refrigeration machines
sulphur and clean fuel or natural gas sure cladding temperature from bottom, periodically, and regular clean cooler EMS-17: For fl exibility and reliabi-
Economic
80 potential Technical is used, furnace stack temperature can which might be low as compared to the and condenser tube. Auto cleaning of lity of operation, energy saving as well
potential be reduced by addition of convection top of equipment or pipelines, which condensers and coolers is also used to as due to technical limitations, multiple
Existing Thermodynamic bank load, adjusting deaerator pressure may be misguiding. Insulation of hot reduce rate of deterioration of effi ciency equipment are provided and are ope-
60 energy potential
use as well as additional surface area of fl anges, valves and fi ttings are not done of machine. Many times, replacement rated in parallel, e.g., air/nitrogen/
economiser. Stack temperature can also while commissioning due to the risk of low effi ciency old refrigeration unit natural gas compressors, circulating
40 be reduced by addition of air preheater. of leakage. Once the process is esta- by high effi ciency new machines is also water (CW)/raw water (RW) pumps,
Now many options are available for blished, identify and insulate them. economically justifi ed. and air fi nned exchangers. When multi-
20 online and periodic cleaning of convec- ple equipment are operated in parallel,
tion bank tubes. EMS-11: Steam traps are provided EMS-14: Many times, replace- rationalisation of load on machines,
0 on steam line at strategic locations to ment by high effi cient machine/spares sequencing for start-up for required
EMS-7: Furnace and boiler refrac- accumulate and remove condensate will not be an economical decision. fl ow requirement, as well as provision
Fig. 1: Energy saving potential tory gets damaged over time due to from steam line. The traps operate fre- However, while increasing capacity of of VFD for at least one machine for

176 Chemical Weekly April 23, 2024 Chemical Weekly April 23, 2024 177

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