Witzenmann GmbH

Östliche Karl-Friedrich-Str. 134

75175 Pforzheim, Germany

Phone +49 7231 581-0

Fax +49 7231 581-820

wi@witzenmann.com

www.witzenmann.com

HIGH- TEMPERATURE APPLICATIONS

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THE CATOFIN® PROCESS CATOFIN® is a licensed process for producing propylene from propane gas. Here, propylene is produced in a catalyst process by means of dehydrogenation, i.e. by reducing the amount of hydrogen in the propane. The process is an alternative to the traditional production method, which involves cracking crude oil in refineries. The advantages of the CATOFIN® method lies in the purity of the process. With proportions of propylene in excess of 85 %, the CATOFIN® process achieves the highest yield of all methods. A further positive side-effect: It functions with gas, i.e. without the scarce raw material crude oil. The global rights to the CATOFIN® process are held by the American company CB & I Lummus.

Expansion joints, hangers and supports or other flexible elements which are used for high-temperature applications in refineries, chemical plants or power stations must satisfy special requirements. In order to meet such requirements, a special design, raised bellows for the expansion joints for example, is usually required.

The projectThe Borealis Group, based in Austria, holds the licence for the construction and operation of a CATOFIN® Plant1 in Kallo, Belgium. For the modernisation of this plant, Borealis commissioned Witzenmann with the engineering and the production of a total of 26 large expansion joints with nominal diameters up to DN 1500, as well as with the corresponding spring and constant hangers. The challenge was to design and produce the components according to the latest specifications HJ-270 and H-270 for expansion joints in CATOFIN® plants of the license holder in the USA.

In reference to the operating efficiency of the planned facility, the specification was worded to the effect that compliance requires all engineering disciplines at Witzenmann to be pushed to the limit.

This modernisation is one of the first plants to be refurbished according to the more stringent CATOFIN® specification. Therefore, it was not possible to draw on current empirical values. In an extensive exchange with both the Belgian cus-tomer and the US-based licensor, high-precisions solutions were developed in order to meet the challenging demands.

Specific: Engineering of expansion joints with material 321H / 1.4878 in accordance with CATOFIN® specifications HJ-270 and H-270 from CB & I Lummus, as well as specific customer requirements.

PURCHASER: BOREALIS GROUP

ENGINEERING TO CB & I HJ-270 & H-270

The demands The main demand was a complex, interdependent package comprising:p Process-technology challenge with hot-formed, expanded

pipe connections without circumferential weld seamsp Expansion joints at high process temperatures with "cold"

bellows (insulation between bellows and internal sleeve) within an existing plant

p Maximal permitted length tolerances of 1 mm for all components and welded assemblies with up to 14,500 mm component lengths

p Short project time

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600 °C 595 °C

300 °C 287 °C

72 °C 50 °C

187 °C 182 °C

537 °C 540 °C

Practice confirms the theoryAccording to detailed FE calculations, the engineers at Witzenmann determined that the specified design work can, in some cases, cause elevated temperatures to be transferred to the bellows over the weld ends. The specified design was therefore altered (image on left) to the effect that the max. temperature values specified by Lummus are verifiably fulfilled in both the theoretical FE calculation and also in the subsequent practical operation. The structural design of the interior protection sleeve was able to significantly reduce the temperature effect.

Temperature measurementsThe temperature measurement shows how the temperature reduces from inside to outside. Only a non-critical temperature of 187°C prevails at the bellows during operation. Consequently the service life and reliability of the overall plant is signifi-cantly improved.

With hot-application lines from approx. 550 °C, a highly-alloyed, heat-resistant stainless steel, such as 1.4876 (Alloy 800 H) is normally used as the material. In the specifications provided by Lummus Technologies, 321 H / 1.4878 is stipulated for the expansion joint design of the bellows. At high temperatures, this has significantly lower strength values. Lummus as the licence holder therefore set out highly-detailed specifications for the bellows temperatures and the connection of components under the influence of the hot medium. This means that the specified material can still be used at these high operating temperatures. This specification significantly intensified the design and the structural challenges. Raised bellows with temperature insulation The high-temperature application requires special design work, e.g. raised bellows. This permits temperature insulation of the bellows from inside. The bellows were therefore able to be realised without the use of extremely expensive material.

Engineering: 3-D CFD calculationsThe 3-D CFD (computational fluid dynamics) calculation is used to calculate pres-sures, temperatures and flow velocities of moving media within fixed geometries. In this case for the purge connection, in order to calculate the temperature and flow distribution of the injected propane gas, so that a barrier flow to the media inside the bellows geometry can be reliably determined.

ENGINEERING AND MATERIALS

Material/costs diagram

Purge connections

Propane is blown from outside into the bellows area. This acts as a barrier flow for themedium. This reliably keeps the bellows area away from the hot medium and ensures that no carbonisation, which could lead to clogging of the intermediate area, occurs in the line.

THE WITZENMANN SOLUTIONIntelligent design achieves strength in the high-temperature range The improved design

Operational reliabilityis achieved though integrated engineering

1.48

78

321H

Cost factor 1

1.48

76

ALLOY 800H

Cost factor approx. 3.5

Cost

s in

$

20 136 252 368 484 600

Temperature in °C

Detailed view

Typical determination of the mechanical stresses at critical points

Structural extension of the sleeve

Insulation zone therefore starts earlier

Welding end

Interior protection sleeveInterior insulation

Interior sleeve

CalculationMeasurement

Interior insulation

Raised bellows

Blowing in of propane

Interior insulationBarrier flow

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Stre

ngth

in N

/mm

²

Temperature in °C

THE "COLD" ANCHORING

The challenge was to significantly reduce the heating of the anchorage parts by the media temperatures of 650 °C / 705 °C. The anchoring is usually welded directly onto the pipe socket. As a result, the medium temperature is transferred to the anchoring nearly unreduced. The result is a reduced load capacity of this hot anchoring. In addition, increased thermally-induced stresses since the anchoring part that lies outside of the insulation cools down very quickly. This then leads to elevated temperature gradients.

To protect the anchoring system of the expansion joints against the effects of heat, Witzenmann developed a "cold" anchoring with minimised heat introduction and a patent application has been filed.

The focus of the patent application was to achieve a low heat introduction into the anchoring, and to design the anchor box in such a way that the resultant stress peaks are reduced. Instead of a solid weld seam, there are now only 4 defined contact points to with the anchor box is connected to the pipe socket. The reaction force of the two anchors is thus uniformly distributed over the 4 contact points. Following the 3D FEM calculation, the anchor box and the fastening points were designed and tested. This permitted the use of the specified material (1.4878), despite increased process tem-peratures inside the expansion joint.

SAFETY THROUGH DETAILSAnchorage system, patent pending Centring pins and more...

Centring the anchoring

Preparing the measuring points

Temperature measurements during operation

The centring pin ensures that when installed in the horizontal position, the floating anchoring system cannot sag and is always centred on the patented contact surfaces in order to guarantee uniform force transfer. The spacer plates shown in the image are intended as installation supports during installation. Confirmed by practiceIn consultation with the customer, several temperature sensors were attached to various expansion joints. 3 months after set up, Witzenmann engineers were back on site to check whether everything is in order, the plant runs trouble-free and whether a read-justment might be necessary. The actually determined plant values were compared with the theoretically calculated values and fully confirm the engineering. The Witzenmann design therefore permits full compliance with the specified temperatures. Practice meets theory!

For the first time, a CATOFIN® expansion joint was calculated under practical conditions and confirmed through measurements!

01 Anchor box of the floating anchoring system (patent pending) Bellows insulated on the inside "cold anchoring" Insulated bellows connection with blow-in nozzles Centring of the anchor box Purge manifold

02

03

04

05

06

Strength diagram 1.4878 / 1.4876

Integrated expansion joint for angular rotation DN 900

with purge ring

The floating anchoring system touches on the welding socket of the bellows in just four small areas

CATOFIN® expansion joint

On the expansion joint, measure-ments were taken at total of 9 points in real operation, in order to be able to compare the temperature profiles with the calculated values

1.4878 1.4876

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HIGH PRECISION TO 14,500 MM

Alongside the engineering and design work, producing components accurate to a mm was a further focal point of this project. A production tolerance of ±1 mm had to be maintained over total lengths from 2300 to 14,500 mm and DN 1500 / DN 900. Because Borealis had specified that the components must be put together on site like a puzzle, in order to keep the installation as simple as possible. To achieve this level of precision, the individual components - above all the anchors, which are ultimately crucial to the total length - are measured using laser technology and adjusted for an accurate fit during production.

ASSEMBLY TOLERANCES IN THE MM-RANGEThe new expansion joints had to be accurately inserted on site into the existing pipeline system

Adjustable anchorage system

Assemblyof the pipeline

14 metre overall length places high demands on both produc-tion and logistics.

Elbow with dummy leg

Integrated expansion joint withtrunnion

Adjustable anchoring between trunnion and steel frame

Elbow with trunnion

The forces caused by thermal expansion are introduced into the anchoring system via an adjustable steel structure (trunnion). The design work is such that it can be readjusted via clamping nuts – consequently, a slight adjustment is possible during installation on site.

Trunnion with adjustable anchoringTrunnions are used whenever a floating anchoring system is difficult to implement in terms of design. Heat is introduced into the load-carrying anchors via the trunnions. In order to reduce the thermal induced stresses, these were partially insulated (hot box design).

3D pipeline model with flexible elements

14500 ±1

PipelineTrunnion cap

Insulation Clamping nut

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INSTALLATION AND SET UP

The correct (installation) positon of the expansion joint, the problem-free installation, first test run, setting and adjustment of the spring and constant hangers, ... all are tasks of the Witzenmann engineers on-site before the plant can be commissioned.

Installing a lined high-

temperature expansion joint

with pantograph anchoring.

A Witzenmann engineer

checks the accuracy of the

mounting saddle.

Following installation of the expansion joint,

the safety bars (brown), which keep the

bellows at the calculated fitting length, are

removed.

Overall system

A Witzenmann engineer carrying out fine-adjustment of a

constant hanger. A wide range of spring and constant hangers

are designed, produced and installed for the Borealis project.

Precisely matched to the overall system of pipelines, expan-

sion joints and support components.

A project is completed only when everything fits and is running.

Further examples of high-temperature applications

p Bayernoil: DN 600 – FCC expansion joints from 1.4876 and bellows from 2.4856 / 1.4878 with 780 °C maximum operating temperature, medium: hydrocarbons

p Total Leuna: DN 1200 – FCC expansion joints lined with concrete for 780 °C

p MiRO Karlsruhe: DN 1500 – Flue-gas expansion joints from 1.4910 (heat- resistant stainless steel) for 780 °C, total length =12,000 mm, a 3-joint system was supplied for minimising the connection forces for a turbine (energy recuperation)

p Carbon black for the production of printing ink and tyres.

Temperatures: 670 °C and higher