Srt Technology 5f4f12

SRT ® Pyrolysis Furnace Module

Overview

The SRT® Short Residence Time pyrolysis furnace module from Lummus Technology was developed in the mid-1960s as a response to growing ethylene demand and the need for selectivity to olefins, consistent with long run lengths and high on-stream time. Since the first SRT I was developed, the design has evolved, culminating in the SRT VI design. It features a unique 2- radiant coil design that is mechanically simple and easy to operate. Olefin yields are consistently high for all feedstocks. Plants that use SRT technology currently represent about 40% of worldwide ethylene capacity. In the last decade, Lummus has built and commissioned more ethylene cracking furnaces

Process Features

Advantages

Radiant coil design:

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Performance Characteristics

than any other process licensor. The SRT technology consistently achieves designed capacity, meets yield guarantees, and operates for long run lengths (greater than 50 days) between coil decokings. The furnace module features a single-stage transferline exchanger designed for high capacity, low pressure drop, and maximum thermal efficiency. This patented “Quick Quencher” design has no tube sheet and provides long run times between mechanical cleanings. Many designs feature gas turbine integration with the furnace to significantly improve the plant energy balance. Recent projects are equipped with low NOx burners or catalytic DENOX to improve emissions.

Small inlet tubes Large outlet tubes

Client Benefits Higher selectivity to olefins ■ high capacity per coil long run length ■ simple mechanical design

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Quick Quencher Transferline Exchanger

No tube sheet ■ low residence time ■ low cost ■ long runs

Simple tube hanging system

Lower cost ■ reliable operation

Venturi flow control

Improves conversion control ■ evens flow distribution

Floor firing

Fewer burners ■ lower cost

Low NOx burners

Reduces emissions

BASF on-line decoking

Less maintenance ■ longer tube life ■ reduces emissions

Gas turbine integration

Significant energy improvement

Heavy oil processing system (HOPS)

Provides capability to crack heavy NGL

Pyrolysis yields wt % Hydrogen Methane Acetylene Ethylene Ethane MAPD Propylene Propane C4 s C5+ TOTAL

Ethane 3.93 3.82 0.43 53.00 35.00 0.06 0.89 0.17 1.59 1.11 100.00

Propane 1.56 25.30 0.64 39.04 3.94 0.53 11.34 5.00 5.39 7.26 100.00

Full Range Naphtha 0.91 15.70 0.78 30.80 3.30 1.00 14.00 0.28 8.70 24.53 100.00

Light AGO 0.63 11.20 0.47 26.50 3.40 0.80 13.40 0.25 8.80 34.55 100.00

SRT ® Pyrolysis Furnace Module

Process Description

Pyrolysis Heater Configuration, SRT Coil Configuration, and Quick Quencher

The feedstock is first heated in the convection section under flow control to each coil. Dilution steam is then added to each coil on flow control such that a constant steam-to-oil ratio is maintained. The total mix is further heated in the convection section before entering the radiant section. The feedstock is distributed to the parallel tubes in the first of the radiant coil via critical flow venturis. The effluent from the radiant coils is sent to the TLEs. The TLEs generate super-high-pressure steam via a thermosyphon system connected to a common steam drum for each heater. The boiler feedwater to the steam drum is preheated in the convection section of the cracking heater. The steam generated is superheated in a superheater coil integrated with the convection section of the heater. To control the superheater outlet temperature, the coil design allows for boiler feedwater injection into the partially superheated steam.

After the water injection, the steam is returned to the convection section for final superheating to the desired temperature. The fresh feed TLE effluents are oil quenched with individual quench fittings at the TLE outlets. The effluent from recycle cracking is not quenched, and additional heat is recovered in a secondary TLE. The source of combustion oxygen for the cracking heaters is a combination of ambient air and gas turbine exhaust. The gas turbine drives an electrical generator and is fired by methane offgas. The decoking design includes steam-air decoking of the radiant coil and air-only decoking of the TLE. On-line decoking of the TLE offers several mechanical, maintenance and capacity advantages over conventional TLE hydrojetting. Decoking effluent is sent directly to the firebox for combustion. This approach has been used in designs since 1978.

SRT VI Coil Configuration

Pyrolysis Heater Configuration

Feed

Convection Section BFW

Dilution Steam

Steam

Radiant Section Quenched Raw Product

For further information, please :

Quick Quencher

Lummus Technology 1515 Broad Street, Bloomfield, NJ 07003-3096 USA Tel. 1-973-893-1515 Fax. 1-973-893-2000 e-mail: [email protected] Website: www.lummus.cbi.com 11/01/07