Process Description

Tehran Oil Refinery was established in 1974 by an American company (FLUOR) that involves two similar plants, northern and southern refinery. The steam networks in two oil refineries are similar. A 0.4064 m diameter, 44.8 bar pressure and a 0.2032 m diameter, 4.1 bar pressure steam lines interconnect the north and south refinery steam systems to provide operational flexibility and assist in the start-up of north refinery. In this regard northern refinery steam network is simulated.

There are four boilers which provide 266.4 t/h high pressure steam at 44.8 bar. These headers involve high pressure (44.8 bar), medium pressure (20.68 bar), and 4.1 bar. The high-pressure steam distribution system has let down stations to provide the refinery with 20.68 and 4.1 bar steam. The 44.8 bar steam is used primarily as the energy source to drive three 7500 KW condensing type turbine generators and other back pressure and condensing turbine drives throughout the refinery. The refinery is independent of any outside power supply and facilities are therefore designed to meet all energy requirements for continuous operation of the refinery. Also two condensate headers, hot and cold condensate, are applied at 100°C and 125°C.

Twenty-two steam turbines drivers between HP, MP headers are applied. They do not produce power but they are connected to pumps and compress each other. There are 21 steam consumers and 9 steam producer at different level of steam which connected to different headers. The deaerator must be continuously vented to insure proper deaeration and removal of the non-condensable gases. Also the temperature of the water in the deaerator storage space must be at the saturation temperature corresponding to 0.34 bar. In this plan as it shown in Fig. 29.5, the bigger turbines are steam turbines and the small turbines are steam-only driver turbines. In addition the green color shows deactivate plans. Also the red arrows display steam consuming process and the blue arrows steam producing processes. Table 29.2 indicates the name of process which is connected with steam network in northern refinery (Khodaie and Nasr, 2008).

Fig. 29.5 Tehran oil refinery steam network.
Table 29.2 Steam consumer and producer plants in the oil refinery.

NO

Consumer

NO

Producer

201

Crude, vacuum

201

Crude, vacuum

202

Unifier platform

202

Unifier platform

203

Visbreaker

203

0

204

Isomax

204

Isomax

206

LPG unit

206

LPG unit

207

Nitrogen plant

207

0

208

Hydrogen plant

208

Hydrogen plant

216

H2S removal

216

0

223

Tankage

223

Tankage

221

Power station

221

Power station

221

Let-down

221

Let-down

222

Building

222

Building

222

Losses

222

Losses

Source: Khodaie and Nasr (2008).

Source: Khodaie and Nasr (2008).

29.5.1 Scenarios

Four scenarios are suggested in Table 29.3. The first scenario is the base case and the three others are the suggested ones for steam network optimization by replacing renewable energies. The second scenario, Steam Generation by Biomass (SGB), generates MP and LP steam. In the third scenario, Steam Generation at Different levels via Biomass and Solar (SGDBS), the solar generates LP steam and the biomass is replaced for MP steam generation. The fourth scenario, Steam Generation at Same level by Biomass and Solar (SGSBS), is the partial generation of LP steam. It is noted that the processes which can be fed are Unifier plant, Nitrogen plant, Visbreaker, Isomax, LPG, and hydrogen units.

Table 29.3 Suggested scenarios.

Scenario

Description

Base Case

Steam generation through four boilers

SGB

MP and LP steam generation through biomass energy

SGDBS

MP steam generation by biomass and LP steam generation via solar energy

SGSBS

LP steam generation through biomass and solar energies partially

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Getting Started With Solar

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