RASHTRIYA CHEMICALS & FERTILIZERS LTD., TROMBAY UNIT -  A  CASE  STUDY

ENERGY CONSERVATION

1.        THE COMPANY PROFILE

Rashtriya Chemicals and Fertilizers Limited, Chembur, a Government of India Undertaking is one of the
largest integrated Fertilizer and Industrial chemicals complex in the country.  It was incorporated on 6th
March’1978 on reorganization of the erst-while Fertilizer Corporation of India Ltd. and National
Fertilizer Limited.  
RCF has always selected the best available technology at the time of inception of every plant and
followed it up with up-gradation from time to time to improve energy efficiencies and make the plants
ecofriendly and competitive.

Installed Capacities of RCF Plants
Plants                                        Present                Year of
               Capacity                Commissioning
A.        Trombay-I                        
Ammonia (Revamped)                   350                        1965
Nitrophosphate (15:15:15)           1100                        1965
Sulphuric Acid (DC DA)                300                          1966
Nitric Acid                                      320                         1965

B.        Trombay-II        

Methanol (Revamped)                   150                        1966

C.        Trombay - III (Diversification)

Ammonium Bicarbonate                12                        1968
Sodium Nitrate/Nitrite                     12                        1972
Methylamines                                12                        1974
Conc. Nitric Acid                             60                        1972
Phosphoric Acid                            100                       1975


D.        Trombay-IV

Ammonium Nitrate Phosphate      1200                        1979
(20.8:20.8:0)
Nitric Acid                                       750                        1979

E.        Trombay-V

Ammonia                                    900                             1981
Urea                                           1000                           1981


Energy Consumption:

RCF is a highly energy intensive unit, using the energy in the form of  
Ø        associated gas,
Ø        electricity and
Ø        process steam.  
Commissioning of Ammonia I syn Loop & other energy reduction programmes the power & Associated
gas bills have reduced. The average electricity demand of Trombay complex during 2001 - 2002 was
2,83,314.80 MWH.  Associated gas which is used both as feed and fuel has annual consumption of the
order of 442 Million SM3.    About 30175 MT of Sulphur and    235661 MT of Rock Phosphate is also
consumed annually.    

Ø        The average annual fuel and Electricity bills are of the order of    Rs. 125 crores & Rs. 106.89
crores respectively at the present rates of inputs.

The annual energy bill for the R.C.F Trombay complex is given below in the table that follows:


Total Electricity Bill                            Total Fuel Bill                       Total Energy Bill
(In Rs. Lakhs)                                       (In Rs.Lakhs)                         (In Rs. Lakhs)
1999-00                12674                              15450                               28124
2000-2001            12362                              16344                               28706
2001-2002            10689                              12509                               23198


3.        Energy Conservation commitment, policy and set up.

Considerable efforts have been made to reduce consumption of raw materials and energy in age-old
energy intensive plants since beginning.  A system of reporting and reviewing was initiated in order to
optimise the energy consumption, raw material consumption as well as utility consumption.  

An Energy Cell with qualified  engineers and an Energy Manager has been set up to analyze the day
to day energy consumption and variation in the factory. Jobs of carrying out energy conservation
programs are also part of the energy cell. Regular reports are being generated to identify the areas of
improvement with respect to energy conservation and also equipment’s which are causing production
constraints.  On the basis of these reports, a number of proposals for energy conservation already
have been under taken and implemented.  

Energy conservation opportunities are usually identified based on energy audits, case histories of
successful conservation measures implemented by other plants and through suggestions received
from the operating and technical personnel etc.


4.        Energy Conservation Achievements

A selected number of energy conservation measures, undertaken in the year    2001 – 2002, which
have given substantial energy savings, are given below:

4.1        Optimization of Steam Net work

In RCF Trombay unit, Steam is produced and consumed at five different pressure levels i.e.
105ata/40ata/26ata/20ata/12ata. It was observed that whereas in one plant steam is surplus and in
another plant there is a shortage of steam. By carefully analyzing overall steam production and
consumption pattern, the steam distribution network has now been organized in such a way that steam
wastage’s have been minimized. This has brought down our boiler load considerably and thereby
reduction in energy consumption.

To have energy conservation on Thermal Front
v        Regular Inspection of Steam Traps and steam leakages and repairs thereof is carried out.
v        Periodic monitoring of insulation status  and their repairs.

4.2        In spite of the risks involved, RCF have decided to shut-down one boiler from 2002 which led
to an electrical energy saving of             21 MWH/day thereby now meeting all factory steam demand
through only one boiler.

4.3        In Ammonia-V motor driven Benfield pump has been stopped and in its place steam turbine
driven pump has been taken in line thereby reducing electric power consumption.  (35 MWH/day).

4.4        A new 4”  line  was laid for diverting excess air in Ammonia-V Process Air Compressor (PAC) to
Ammonia-I for operating Inert Gas Plant (IGP) and factory grid.  With this modification Ammonia-I are
able to stop their motor driven Instrument Air Compressors (daily saving of 8.5 MWH).  However, to
meet the instrument air requirement in case of upset in Ammonia-V PAC, ‘auto start’ arrangement of
IAC in Ammonia-I has also been made.

4.5        In Methanol Plant Boiler Feed Water Pump and Boiler Water Circulation Pump are being run
by turbine drives by consuming in-house steam and thereby stopping the electrical drives (daily saving
of 1.5 MWH).

4.6        In Methanol Plant one Instrument Air Compressor (42 KW) has been stopped by diverting
instrument air from CPT air compressor which has a higher capacity (daily saving of 4 MWH).

4.7        In Ammonia-V "Mass Spectrometer" analyzer for on-line analysis of 13 process streams has
been installed and commissioned successfully in February 2002.  This would facilitate precise control
of all critical parameters.

4.8        Synthesis Gas interconnecting lines between Ammonia-I and Ammonia-V was suitably
incorporated with required instrumentation and on number of occasions this has resulted in speedy
start-ups of Ammonia-I/Ammonia-V plants and also reduction in unproductive energy consumption
during their start-ups.

4.9        Modified cooling water supply arrangement has been made for Ammonia-I IGP and IAC from
New Nitric Acid Plant.  This has facilitated total stoppage of cooling water system in Ammonia-I.


4.10        In CNA Plant only one Cooling Tower pump is now being operated to meet the requirement
and while the other pump is kept stopped. (daily saving of 0.8 MWH).


The Energy conservation Schemes implemented so far in the last few years have shown continual
reduction in the energy consumption of all plants per se (through various specific schemes
implemented). However the specific energy consumption have shown an increasing trend primarily
because of the low load operation of plants due to feed stock (Associated Gas) limitations. The
annualised specific energy consumptions of major energy consuming plants at R.C.F Trombay
complex is given below in the table that follows:

Specific Energy Consumption ( MKcal/MT)

PLANT                        1999-00                2000 –2001                2001-2002
AMMONIA-I                    11.23                        10.425                        11.644
AMMONIA- V                  12.56                        12.248                        12.480
UREA-V                            9.26                          8.959                          9.641
METHANOL                      9.28                          9.074                          9.233


b)        Details of Schemes implemented.

Ammonia

i)        An Inert Gas Plant(IGP), Producing Nitrogen by Cryogenic separation of air, exists in Ammonia I
plant. A dedicated air compressor used to run to supply air to this IGP.
However it was observed that due to low load running of   Ammonia V plant (Gas constraints), air from
Process air compressor used to be vented.
A 4” line from scrap was made available and hooked up for supplying the excess air at Ammonia V
PAC to IGP. This made the air compressor, previously supplying air to IGP to be shut down thus saving
electric energy.
ii)        Ammonia I plant remains shutdown most of the time in the year owing to severe shortage of
Associated gas. But to keep the other utilities in the plant like IGP, control room A/C etc. in running
condition, cooling water system (one pump and one fan) used to be kept in line.
Modification was carried out, to connect cooling water line from New Nitric Acid plant cooling water
header to IGP and control room A/C thus stopping the cooling water system of Ammonia I during
prolong Shutdowns.
iii)        There exists an instrument air compressor in Ammonia storage, which supplies instrument air to
the storage area.
Due to excess instrument air available in the factory grid, it was decided to connect the grid air to
Ammonia storage. 1” line was connected to Ammonia storage from the grid for supplying instrument air
& thus stopping the instrument air compressor in storage area saving 283 KWH/Day.
iv)        The gasification section of Ammonia I used to import 12 ata steam from the factory grid ( which
was subsequently let down to 4.5 ata) to be used in deaerator, Process condensate strippr & stack.
In new Synthesis section, the BFW back pressure steam turbine, exhaust at 4.5 ata steam was getting
vented.
A line was laid from the BFW turbine outlet to gasification section to consume the excess 1MT/hr of 4.5
ata steam .


Ammonia V

i)        There exists two drives to drive the Benfield pump in Ammonia V plant. A electric motor
consuming 35 KWH and a back pressure steam turbine operating at 36 ata and exhaust 4.5 ata output
(18 MT/hr of 36 ata steam).
Initially when this turbine was being taken inline the 4.5-ata steam used to get vented thus loosing
energy & making the system uneconomical. Due to this motor driven pump used to taken line. However
after modifications carried out in-house, the 4.5 ata steam was consumed in the plant thus utilizing the
energy from steam at the outlet of turbine.

Concentrated Nitric Acid (C.N.A).

i)        Two cooling Tower pumps of 60 hp used to run to provide water to C.N.A cooling water system.
After detailed study on cooling water requirement of the plant & pump capacity, the 60 hp motor was
replaced with a 75 hp motor. This excess hp made only pump to be run to suffice the cooling water
requirement of the plant.

Methanol

i)        Use of entire available purge gas from synthesis section as fuel in reformer was started from July
2001. This could be achieved by realignment of 25 Nos. combustion air bellows of burners with main
header.
Associated gas fuel had reduced and a net recurring reduction of 0.1 MKcal / MT is being realised.
ii)        The BFW (steam driven) pump was never run on continuous basis earlier. This pump (steam
driven) was used for few hours only during the start up or shut down of the plant.
With in house generated steam (on optimising), the turbine was taken in line and is kept running
continuously.
iii)        BFW circulation pump in the plant used to run occasionally on turbine drive. After optimising on
in-hose generated steam, the excess steam was used to drive the BFW circulation pump thus stooping
the 35 KW motor.

iv)        Stopping of Instrument air compressor of 42 KW motor rating.
This was achieved by in-house over hauling of its counter part compressors (CPT) as well as cleaning
CPT inter & after coolers.

Suphala

Stoppage of GB 721 / 723 Blowers.
The Blowers GB 721 / 723 used to run to provide air flow to the process system which in turn used to
cool the complex fertilizer product. With modification carried out in-house other blowers were made to
provide air for cooling purpose, thus stooping GB 721 / 723 Blowers.

New Steam Generation Plant.

RCF has 3 nos. of Centralised Steam Boilers generating 170 MTPH of steam at 105 ata each. Due to
Associated gas (Chief Raw material) constraints most of the plants are forced to run on reduced load
thus curtailing the boiler load between 120 to 160 TPH.
Inspite of Risk involved, RCF has decided to run only one boiler keeping the stand-by (Supportive)
boiler shut down. This has led to an electrical saving of 21 MWH/Day.










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Source:Bureau of Energy Efficiency,India
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