1. Gas turbines
MS3002 is for GTG 1 & 2 in VR. The equipments used are diesel engine, torque convertor, accessory gear box, gas turbine, load gear box, generator, complete set of lube oils. High pressure air is added to one side of compressors while in the opposite direction fuel addition takes place in the combustion chamber. The combustion consist of 15 stage compressors and 6 combustion chambers and products are directed to nozzles under high pressure turbines. Gases from high pressure are reduced to low pressure and given out. MS5001 is for GTG 3 & 4 in VREP –I. This consists of 17 compressors and 10 combustion chambers and 2 stage turbines are used for output.
2. Generators
It is coupled with the gas turbine through gear box that reduces turbines speed.
The DC current enters the generator and then the automatic voltage regulator to keep voltage constant. The various electrical instruments are 1 KV switch gear, LT switch gear, 3 KV switch gear, uninterrupted power supply and CT switch gear.
3. Heat recovery steam generator
Deaerator provides water for HRSGs. They are used to recover heat from turbine exhaust gases. They is natural circulation single pressure horizontal duct fired water tube boiler. The firing facility is also and steam production in HSRG is done. The power from CPP is supplied to DM plant, feed water facilities and Deaerator .
PLANT CAPACITIES
GTGs : 7.18 & 21.31 MW HSRGs : 27 & 60 T/Hr
5. Flare system Equipment:
Flare tip, Flare stack, Fluidic seal , Flame front generator, Water seal drum, Knock out drum , Blow down pumps
Objective :
Flare facilities are provided in order to avoid releasing of in burnt hydrocarbons to the atmosphere. Facilities exists for injecting steam to stack for smokeless flare for refinery.
In view of additional hydrocarbon load subsequent to VRCFP commissioning, additional flare facilities are provided in order to avoid releasing of un- burnt hydrocarbons to the atmosphere.
This flare system also comprise of a separate AAG flare which is non smokeless type.
The liquid hydrogen discharges and separates to slop tank and knock out drums.
The existing system consists extremely toxic gases coming from VR & VREP I. CDU I, CDU II, FCCU I. FCCU II, FCCU III & PRU total load is 698.5 tonnes/hr.
Unit process flow description
1. Collection of gases
Gasses from CDU III, VBU, FCCU I, PRU, SRU, DHTS, CDU II, FCCU II, CDU I are passed from the headers to the final knock out drum and then condensed hydrocarbon is separated in the KO header to water seal drum and then the gases
go to the flare stack where it is burnt. The flare seal is at stream of flare tip.
2. New flare knock out drum
It is used to trap liquid droplets. Knock out drum receives liquid and vapour where the liquid droplets are trapped in the KO drum and vapour goes away. Water is recovered by slope tanks blow down pumps.
3. Blow down pumps
They are motor driven centrifugal pumps. The hydrocarbon liquid in the KO drum is given to the slope header where BCW requirement is controlled.
4. Water seal drum
Water seal drum is situated at the base of flare stack. It maintains pressure in flare header to prevent flame flash back. The water is supplied continuous and level is maintained and entry of air is restricted.
5. Flare stack
The top point is sent to the flare tip while the bottom is sent to flare system
bottom. Then it is sent to check O2in gases. Continuous flue gas purge is provided to keep pressure constant.
6. Flare seal
It is a gas lead pipe and it has an inverted cylinder over the lead pipe. The top of the cylinder is closed while the bottom is opened. The lighter gases are collected in the upper bend while heavier gases settle down in the lower bend.
7. New flare tip
The tip is on the top of flare system. The upper part of tip is high heat resistant stainless steel and remainder is carbon steel. The flame is retained at emission rates. The 3 pilot burners are equally spaced. Then the upper manifold injects steam into flame at the tip outlet to promote smokeless combustion.
8. New flame font generator
For ignition of pilot, this is installed. It does gas and air mixing, it has a separate
valve foe gas and air and 3 valves to direct ignition.
Plant capacities
New flare : 698.5 MT/Hr Old flare : 284.716 MT/Hr VRCFP flare : 490.6 MT/Hr
6. Cryogenic nitrogen unit Equipment:
Air compressors, moisture separator, air purification unit, regeneration reactor, distillation column, expansion turbine, heat exchangers, cold box, vaporisers.
Process :
1. Air suction and compressor
Air suction filter is compressed by main air centrifugal compressors to control the pressure.
2. Air pre-cooling
The shell and tube heat exchangers cool the air by chilled water and the moisture separator condenses water and separates moisture and sends the dry water to the knock out drum. The cooling water which is cooled by waste N2, comes out of cold box in the evaporation cooling tower. The chilled water is pumped into after cooler and the return water is circulated back to evaporation cooling tower where
the losses are balanced.
3. Drying
Chilled air is passed to the adsorber where saturated moisture , CO2 are removed by using aluminium and molecular sieves.
4. After filters
After elimination of aluminium and molecular sieve dust the degeneration steam is mixed with waste air from cold box and heated. The hot gases passed through the sieves to regenerate absorbents.
5. After cooling
Purified air is cooled down by return gases in heat exchangers. Cooled by GAN the waste gases from condenser return to the turbines.
6. Distillation
In the distillation column O2rich liquid and gaseous N2is obtained from bottom and top of the distillation column respectively. The rich liquid is throttled and then vaporised and then condensed.
7. GAN & LIN
A part of GAN obtained from the top part is warmed to ambient temperature while other part is condensed thus obtaining liquid nitrogen. A part of the bottom LIN is sent to LIN high pressure storage system while other part is sent as reflux back to the column,
Plant capacities
Design capacity : 245 Nm3/Hr