Syncrude Canada Ltd. Enhances Energy Efficiency of the Upgrader Expansion Project with Pinch Analysis

Alan Rossiter
Process Improvement Consultant, Houston, Texas

Fran King
Colt Engineering, Edmonton, Alberta, Canada

Bob Salyzyn
Syncrude Canada Ltd., Fort McMurray, Alberta, Canada

Prepared for presentation at AIChE's 1999 Spring National Meeting, Houston, Texas, March 14 - 18, 1999
Session/Paper Number: T3001a

UNPUBLISHED

Copyright © Syncrude Canada Ltd., December 1998

AIChE shall not be responsible for statements or opinions contained in papers or printed in its publications.

Abstract

The proposed expansion of the Syncrude Upgrader facility in Fort McMurray, Alberta, will result in close to doubling the plant's output of Syncrude Sweet Blend (SSB) crude oil. The design basis specification (DBS) for the first phase of the Upgrader Expansion included a pinch analysis of most of the Upgrader units. This identified many improvements. A number of these, giving cumulative energy savings of about 3% of total projected site energy use, were incorporated in the DBS. A number of additional ideas are still under review, and these have the potential to more than double the savings. This paper discusses how to apply pinch analysis within large projects of this type. It also includes an overview of the results obtained.

Background

The Syncrude Upgrader facility in Fort McMurray, Alberta, is at the forefront of developing alternatives to conventional crude oil. The facility is in the midst of a series of aggressive expansions which will result in close to doubling the plant's output of Syncrude Sweet Blend (SSB) crude oil to around 430,000 barrels per day. The Upgrader Expansion is part of a suite of strategic projects referred to as Syncrude 21. The total capital investment for the Syncrude 21 program is in the order of $6 billion (Canadian).

The scope for the design basis specification (DBS) for the first phase of the Upgrader Expansion included a pinch analysis of the new and revamped units, together with inter-unit analysis. Pinch techniques are used to analyze heat flows through process units to identify efficiency improvement opportunities. The approach can readily be extended to entire production complexes (e.g. refineries and petrochemical facilities)(1), which can lead to heat integration opportunities that cross conventional boundaries (e.g. heat integration from one process to another, or improved integration of processes and utility systems). The specific objectives of the pinch work in this study were to:

• identify opportunities for improving energy efficiency through heat integration.
• reduce CO2 emissions by minimizing fuel firing.
• use capital more efficiently by reducing the size and cost of new equipment and by freeing existing boiler and cooling tower capacity for expansion.

The above objectives are subject to operating flexibility, capital cost and risk factors.

Overall Approach

Syncrude has applied pinch analysis previously(2), specifically for an expansion study in 1987 and an Upgrader debottleneck design in 1996. Each pinch analysis identified significant efficiency improvement opportunities. A number of the ideas identified for the Upgrader debottleneck design in 1996 have been incorporated in the debottleneck project design and are currently being implemented. The two previous studies highlighted a number of important lessons in terms of maximizing the benefits from this type of work, notably:

1. The timing of a pinch study is important. If it is carried out too late there may be no way to incorporate the opportunities that are identified without adversely impacting the overall project schedule and budget. The work should be conducted as early as possible consistent with availability of basic process data.
2. Those who are in the best position to incorporate the results into the final design should have a significant role in performing the analysis. Ownership of the pinch analysis and its results is important if the work is to be accepted and the ideas derived from it are to be accepted.

Pinch Analysis Execution Strategy

Learning from this previous experience, Syncrude incorporated pinch analysis into the DBS activities, which are at the front end of the overall project development process. Initial designs, with heat and material balances, were available for most processes when the pinch work started, but the designs were not frozen.

The approach adopted by the project team was to have the process design engineers for each area of the plant responsible for applying pinch analysis to the process units in their area. The project team also committed additional resources to assist the process engineers. An overall pinch analysis coordinator (Fran King), who had previous experience in pinch analysis and the Syncrude operation was assigned full time. A pinch consultant (Alan Rossiter), who has extensive knowledge in pinch analysis and previous pinch analysis experience at Syncrude, was available to the project team for training, consultation and reviews.

Another key aspect of the pinch analysis work was software selection. The project team evaluated the major commercial pinch packages available at the time, and selected SuperTarget 4.0 from Linnhoff March. Key factors in the selection were user-friendliness, robustness and flexibility in data input.

Pinch Analysis Execution

The pinch analysis work started with a two-day intensive training course for the selected process design engineers. Over a period of approximately six months the process engineers successfully carried out analyses of several of the processes, with guidance from the external consultant, who was based in the project team office for much of this time. This work identified several process improvements, which were incorporated into the DBS designs as the work proceeded.

During the latter part of the process design engineering, staffing and schedule restraints resulted in a rework of the strategy for conducting the pinch analysis. The remaining process unit, inter-unit and total site pinch analyses were completed mostly by the external consultant and the coordinator, with the unit process engineers involved in reviewing the results. The external consultant again spent much of his time in the project team offices during this period, to conduct the analyses and facilitate information flow. This worked well as by that time the external consultant and coordinator were part of the project team and people felt comfortable with this approach.

Results

There were a number of opportunities identified that were incorporated directly into the process design. A number of other opportunities were identified, but require a more detailed analysis of the operating risks before they can be incorporated.

(i) Opportunities Incorporated in DBS Design

There were several significant design changes identified by the pinch analysis that were incorporated in the process design basis. The cumulative energy saving from these changes amounts to approximately 460 MBtu/hr or ~3% of the total projected site energy use. Associated with this is a reduction of about 235 ktonnes/yr or ~2% of the total projected site CO2 emissions. The design changes include:

1. Process heat integration modifications were incorporated in three plants resulting in energy savings of about 275 MBtu/hr. In two of these cases the changes were minor. However in the third the change amounted to a complete re-design of the process's heat recovery scheme and resulted in savings equivalent to about 35% of the total energy consumption for that plant. The resulting design for this process was simpler than the original design, and there was little or no increase in capital cost.
2. One inter-unit heat recovery project was incorporated resulting in energy savings of about 135 MBtu/hr.
3. A 50# steam generator which was to have been decommissioned as part of the expansion project is now to be retained, resulting in energy savings of about 40 MBtu/hr at zero capital cost.
4. Steam generating pressure was raised from 300 psig to 600 psig in one process resulting in energy savings of about 10 MBtu/hr.
5. A low-cost scheme was incorporated for enhancing H2S/NH3 separation in the sour water stripping units. This is not strictly an energy conservation scheme – rather a product quality project.

The return on investment for the individual changes ranges from 25% to greater than 100%.

(ii) Opportunities Requiring Further Evaluation During Subsequent Engineering Phases

A number of opportunities identified are still being evaluated, due to the fact that more detailed analysis of the operating risks is required. If implemented, these additional opportunities could result in more than doubling the energy and CO2 emissions savings. Pinch analysis will also be used in the next phase of engineering to assist in finalizing the process design. Areas that will be evaluated further include:

(a) Intra-unit (i.e. within single processes)

1. heat exchanger network changes in several units.
2. additional steam generation opportunities.
3. changes in driver selections (to maximize use of backpressure steam turbines).
4. capital cost reduction by using state-of-the-art heat transfer equipment.

(b) Inter-unit/total site (i.e. across process boundaries and utility systems)

At and above the 600 psig steam level:

• net heat is needed from utilities (fired heaters and high pressure steam).
• inter-unit heat integration does not save energy, but may save capital (e.g. by eliminating furnaces).

Below the 600 psig steam level:

• surplus heat is available to increase net steam generation.
• additional steam generation or reduced steam use by the processes can either reduce utility boiler load or generate more power (e.g. in condensing turbines).
• increased 50 psig steam generation or reduced 50 psig steam demand backs down the existing 900 psig->50 psig backpressure steam turbines and reduces utility boiler firing.
• inter-unit heat integration can save energy, but is likely to cost capital.

Several possible furnace options and modifications to the site's steam system and cooling systems were identified based on these observations. These are summarized below and will be reviewed further as the engineering work proceeds:

1. recovery of high level heat from one process to reduce furnace duties and associated capital costs in two other processes.
2. recovery of lower level heat to offset 50 psig steam use in several locations across the site, and modifying the steam system to accommodate the changed steam balance (e.g. add condensing steam turbines).
3. use of 50 psig steam to preheat furnace and boiler air.
4. shifting up to 1,000 MBtu/h from cooling water to air cooled heat exchangers (eliminates up to 5 cooling tower cells; results in modest capital savings and significant operating savings).

Conclusions

A significant number of distinct opportunities for improving the Syncrude Upgrader Expansion Project's energy efficiency were identified through the pinch analysis. Opportunities incorporated into the process design basis have resulted in savings of about 3% of the total projected site energy use, as well as significant reductions in CO2 emissions. The remaining opportunities require further evaluation, but could potentially more than double the savings.

The success of this pinch analysis should be measured not only in the number of opportunities identified to save energy, or even the magnitude of those savings. Equally important is that fact that many of these ideas were incorporated into the process design basis, thus ensuring that the benefits are obtained in the plant, when built. This is largely the result of the approach that was taken to the work, integration of the pinch analysis into the process design basis phase of the project, and involvement of the unit engineers closely with the pinch analysis work. Another important benefit that was derived through this approach was that several of the process design engineers developed a measure of proficiency in the use of pinch analysis, which should be a great asset for them in the future.

The change in approach part way through the process design is a reminder of the fact that real world constraints often prevent us from completing projects in the "ideal" way. Re-deployment of resources meant that some of the process engineers who participated in the pinch training were unable to complete the pinch analysis of their assigned units. However, by utilizing an integrated team approach the pinch analysis was still completed with a significant number of opportunities incorporated into the process design basis.

References

1. "Process Integration: Planning Your Total Site," Allan Rudman, Chemical Technology Europe, January/February 1995.
2. "Syncrude Canada Applies Pinch Analysis in Tar Sands Upgrader Debottlenecking Projects", Peter Bourque, Alan Rossiter and Francisco Alanis, AIChE Petrochem & Technochem Expo '97, Houston, TX, March 11-12, 1997.

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