*4.1.4 Process improvement for maximum product valuation*

Aramco uses the PIMS linear programming (LP) software for planning refinery and olefins operations, enabling optimization of feedstock selection, product slate, plant design, and operational execution. It includes assay management, making it easier to add, modify, and re-cut assays, and helps refinery planners develop more accurate plans that deliver greater profitability. The estimated benefits from energy efficiency are in the range of 3–5% of total energy consumption.

## *4.1.5 New design standards for energy efficiency*

It is always more cost-effective in the long term to build energy efficiency and operating reliability into the original design of a new plant than to retrofit a poorly designed facility. Yet there appears an ingrained bias among corporate decisionmakers towards the latter approach, following short-term policies such as minimizing construction time at the cost of lower safety, reliability, and efficiency.

Recognizing this reality, Saudi Aramco revised its published corporate standards and procedures in the mid-2000s to include an energy efficiency study between the preliminary process design stage and the detail engineering stage. In order to provide flexibility, however, these standards were made "advisory" not "mandatory", to be followed at the discretion of the Project Manager. It is not hard to imagine the outcome.

To be effective, such standards must necessarily be mandatory, but with the flexibility to waive them by a senior corporate executive, and not at the sole discretion of the Project Manager.

Furthermore, the energy efficiency audit of the preliminary process design must be done by a qualified independent company reporting to the operating company,

not to the engineering contractor that produced the preliminary design in the first place. Without such terms, the standards will be toothless and ineffective in achieving the stated corporate goals.

Additionally, the incentive bonuses paid to the company's Project Manager and to the EPC contractor should be based not on beating the construction schedule, but on (a) trouble-free startup and commissioning and (b) meeting long term (e.g., 2–3 years) performance metrics for the facility.

An optimized new design will improve all performance metrics—yields, production rates, energy efficiency, reduced maintenance cost, etc. Even though the initial investment may be slightly higher by about 5%the long-term operating cost savings can be expected to be in the range of 15–20%.

Aramco, like most oil and gas companies worldwide, purchases process technology from international licensors. The scope of supply subject to the performance guarantee typically includes not only the reactors and catalysts but also the separations (distillation columns) and the heat exchange network. There are two issues that must be addressed. The first issue is that most licensors typically guarantee the performance of their units only if their design is followed exactly in all respects, with no deviations unless approved. Now it makes sense to purchase the guarantee for reactors and separations but makes no sense to accept voiding the guarantee if the operator modifies the HEN, or the pumping and compression network, or the utilities mix. Since 2001, the Energy Systems Unit (now a Division with over 50 staff) of Aramco has developed considerable expertise in optimizing HEN design as well as pumping, compression, and process-utility integration. All we need is to license the reactor/separator technology, and absolve the licensor for the performance of the HEN, pumps, and utilities. This is the direction in which the rest of the industry also needs to move to remain competitive.

The second issue is that as a matter of policy Aramco usually prefers to enter into joint venture agreements with international oil, gas, and petrochemical companies for new facilities. Usually, we have to compromise on which company's standards to follow and are often forced to sacrifice energy efficiency in return for some other concession.

#### **5. Terminals and distribution facilities**

These facilities are spread across all components and connect all components together by supplying either as feed to one sector which is the finished product of the other or the final product to the end-users. It includes a network of pipelines and storage facilities to deliver the wellhead fluids to upstream facilities, upstream products i.e., oil and gas to downstream facilities i.e., refineries, fractionation plants, and also finished products from downstream facilities for other consumers including end-users. As it includes mainly a network of pipelines, pumping systems, compression systems with various pressure requirements, consequently, energy losses are resulted mainly due to friction, pressure let-downs, types of drivers, etc.

#### **5.1 Applications in terminals and distribution**

Swing/transfer pipelines are the principal way of providing flexibility in transferring oil and gas to allow optimum dispatching of production among existing facilities in the most efficient manner. Aramco uses a Dammam-7, a new supercomputer among the top 10 most powerful in the world, to manage its facilities. These swing line connections are utilized to effectively optimize the value chain from GOSP to product shipment, and save energy whenever the opportunity arises.

#### *Energy Efficiency: The Overlooked Energy Resource DOI: http://dx.doi.org/10.5772/intechopen.101835*

This requires close coordination between operations foremen for various facilities. For lower production, fewer gas compressors are needed to handle the associated gas. Similarly, for higher loads, the gas compressor and pump operation need attention.

The corporate energy conservation team helped develop such operating practices and incorporated them into the company's Standards and Procedures manuals. In addition, the team undertook a company-wide communications initiative to make sure production engineers, operations, and shift coordinators in the field were made aware of these revised documents.

## *5.1.1 Turboexpanders in high-pressure pipelines*

Turbo-expanders are well-proven technologies for pressure-energy recovery (discussed previously under Upstream Sector applications) and are widely used in the processing industry to produce work or generate electricity. In distribution, high pressure (700–100 psig) pipelines are typically used to transport "wet gas" from upstream gas processing plants to centralized fractionation plants where highvalue C2–C5 components are separated from methane by cryogenic distillation. Instead of letting down the inlet pressure across throttling valves, they can be passed through a turboexpander for power recovery. This is essentially free power that easily justifies capital investment. Up to 20–25% additional power can be generated by preheating the inlet gas prior to expansion using low-grade heat that has no other beneficial use (e.g., necessary cooling of HP steam condensate return, if available nearby, to avoid water hammer).

#### *5.1.2 Pump load management*

One of the biggest sources of essentially free power savings is to minimize the number of pump trains being operated in parallel. Two important considerations must be kept in mind: net positive suction head (NPSH), which generally becomes an issue when the flow falls below 60% of flow at the best efficiency point, and the flow achievable by using N pumps in parallel will be less than N times the flow through a single pump. The methodology used is to develop the composite performance curves for the pump network, and match them to the system pressure drop curve.

#### *5.1.3 Drag reducing agents to reduce pipeline frictional losses*

Pipeline drag reducing additives have proven to be an extremely powerful tool in fluid transportation. High molecular weight polymers are used to reduce the frictional pressure loss ratio in crude oil pipelines, refined fuel, and aqueous pipelines. The drag reducer used in the Mostorod to Tanta crude oil pipeline in Egypt reportedly achieved a 35.4% reduction in pressure drop and a 23.2% flow increase. The experimental application of DRA by Arab Petroleum Pipelines Company (SUMED) in a pipeline from Suez to Alexandria in Egypt achieved a flow increase ranging from 9 to 32% [11].

Aramco is using DRA technology (**Figure 21**) for the Riyadh-Qassim pipeline capacity expansion project and for future projects.

#### *5.1.4 Proper piping networks design*

For proper design of piping networks, the key optimization parameters that should be considered include pipe sizing and design code, materials, piping

**Figure 21.** *ΔP reduction vs. DRA dosage.*

connection, connection to the header, maintenance, etc. Saudi Aramco has engineering standards and best practices (SAES & SABP) which are continuously updated to improve the energy efficiency of the upcoming as well as existing facilities.

#### *5.1.5 Utilization of high-temperature heat from exhaust of gas turbine-driven rotating machinery*

While pumps and compressors are usually driven by electric motors, when the units are large enough and run mostly at a steady state, it can be advantageous to use gas turbine drives, with the hot exhaust (which must be above the process pinch temperature) being used for process thermal heating or even local steam generation linked to the site Utility System. Aramco has successfully implemented several such projects.

#### *5.1.6 Let-down of imported HP fuel gas pressure using turbo-expander*

Power recovery turbines (**Figure 22**) are one of the largest sources of clean power generation in many industrial facilities and high-pressure distribution pipelines in particular. The high-pressure fuels gas is let down to lower psig to supply the HP fuel gas header, and a part is further let down to supply the LP fuel gas header. An expander/generator can be installed between the HP sales gas and the HP fuel gas header to recover some power. Turbo-expander generators offer great promise from an energy efficiency perspective in that they have the potential to provide power at very high isentropic efficiencies over 90% and are extremely reliable, with availability factors approaching 99%. Furthermore, the inlet HP gas should be preheated if possible, using low-grade heat (defined as less than 350°F) such as steam condensate return from the refinery). Up to 20–25% additional power generation is possible at zero emission of CO2.

Although the reported data so far are limited, potential energy efficiency improvement in the T&D sector is estimated to be 10–15% of baseline consumption.

*Energy Efficiency: The Overlooked Energy Resource DOI: http://dx.doi.org/10.5772/intechopen.101835*

**Figure 22.** *Model of typical turbo-expander generator equipment.*
