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VM-EMS user reference
VisualMesa EMS user reference

Energy Management System for Users     (view PDF)

Solution for Energy Cost Reduction

The VisualMesa Energy Management System (VM-EMS) is an online solution that facilitates cost-effective operation of an industrial site's utility system, including production and use of steam, fuel, power, and water and consideration of emissions. It facilitates the management and operation of those systems, by reducing cost by solving daily operating inefficiencies, and providing all the necessary information for targeted monitoring and optimization of site-wide operations from a single interface. The following examples show how VM-EMS improves daily management of a site's utility system operations and maintenance:

The VisualMesa Energy Management System offers two products to model, monitor, and optimize of energy systems:

  • VisualMesa Energy Real-Time Optimizer (ERTO)
  • VisualMesa Energy Monitor (EM)

VisualMesa Energy Management System products have been successfully implemented in various types of energy systems including steam, fuel, electricity, hydrogen, emissions, water and district cooling. The products are built on the same VisualMesa Energy Management System core functions that were in continuous development for over 30 years. The products share the same user interface providing the user a uniform platform to work with. VisualMesa Energy Management System products are easy to use and maintain as the site changes over time.

  • Utility Operators will be able to:
    • Deliver optimized production and consumption of steam, fuel, power, and water, while, in parallel, tracking emissions at individual equipment, unit, and site-wide levels to ensure regulatory compliance.
    • Identify and solve problems quickly through user interface alerting and automatically updated recommendations for improving operation.
  • Engineers will be able to:
    • Evaluate changes to the utility system operations and reduce the operating cost.
    • Evaluate the cost and benefit of new or modified equipment or utility supply and purchase contracts to justify capital investment.
    • Evaluate the effects of a plant shutdown in terms of cost, reliability, and emissions, in order to plan for optimized operation of the utility system in advance.
    • To detect, track and determine the cause of imbalances in the utility system.
  • Maintenance personnel will be able to:
    • Identify failing meters in need of replacement or calibration
    • Reduce time spent seeking the source of imbalances in the utility system.

VM-EMS solution provides increased value in the following seven ways:

  1. Monitoring
  2. Real Time Optimization
  3. Accounting and Imbalance Detection
  4. Key Performance Indicators (KPIs)
  5. KPI Operator Alerts
  6. Engineering Case Studies - "What If?" Analysis
  7. Maintenance

1.    Monitoring

VisualMesa Energy Monitor (EM) provides a single interface (and integrates with third party dashboards) for monitoring steam, electric power, fuel and water systems, as well as emissions from an equipment to site-wide level. By displaying real time data, the user can understand the current operation and is immediately made aware of problems and potential improvements. The following example shows how a typical process unit is displayed inside EM:

The operator receives detailed information by clicking on a piece of equipment, meter, or header on the model interface in order to display desired trends and operational data.

In addition, EM alerts the user to measurements that have changed significantly during a particular time period, so, an operator or engineer can quickly identify and diagnose the cause of any real-time change. For example, a boiler house operator can understand the reason of an increase in the steam demand at any moment, contact staff responsible for operations in the area where change has occurred, and adjust to more efficient boiler operation through targets which are automatically updated in the Em operator interface.

The following figure shows the "Big Changes" report in the EM operator interface. The particular view shown indicates all measured steam values that have changed more than 5 klb/h within the last 3 hours:

2.    Real Time Optimization

VisualMesa Energy Real-Time Optimizer (ERTO) is based on a rigorous model with built-in mathematics and optimization routines designed to recommend lowest cost real-time utility system operation which meets required process plant utility demand and critical constraints. The energy cost which the online, real-time optimization minimizes is defined as follows:

      Total Energy Cost = Fuel Cost + Power Cost + Other Cost

"Other Cost" may include demineralized water costs, such as oxygen scavenger and other chemicals, CO2 emission cost, and any other incremental costs which should be taken into account to ensure accuracy of the optimization. The results of the optimization can be implemented through operator directives or through closed-loop control with operator directives for manual changes, such as pump drive swaps.

Typical operator directives resulting from real-time optimization include changes to steam production (biasing of boilers or generators) and changes to manual set points on steam turbines required in order to provide steam to different pressure levels most cost-effectively. Such directives to operators also include optimization of fuel, such as natural gas, process off gas, and fuel gas, based upon availability, cost and emissions constraints for each, and in light of the electric power purchase cost and price for power exported to the grid, as applicable.

The following picture shows an example of the operator directives that ERTO automatically updates, indicating the changes required for operators to achieve lowest cost real-time operation:

The operators can review specific changes directed by ERTO in the user interface in order to better understand how their specific changes will impact the utility system as a whole. The operator can see the final result of the optimization directives by selecting the "Optimization View" in the ERTO menu in the user interface.

The "Delta View" allows the user to see the specific changes in the utility system that will occur as a consequence of implementation of the optimization directives. In the "Delta View", ERTO highlights with those streams that will change as a result of the optimization directives being followed, so the user can see and follow the specific optimization results graphically.

The figure above shows the recommended change in boiler production ratio or "bias" as a result of the optimizer reducing total boiler load, which most often occurs as consequence of other changes, such as steam turbine and electric motor trade outs or "swaps." In this example, ERTO has directed the operators to reduce Boiler-1 and 2 by 48.8 and 45.2 klb/h, respectively.

3.    Accounting and Imbalance Detection

ERTO performs a rigorous balance of all the energy producers and consumers, calculating the imbalances using real-time data. The imbalances are graphically represented in blocks called "balloons," which are added anywhere metering allows a mass balance to be calculated. Balloons graphically indicate where mass balances are large or small based upon size and color, and imbalances are typically saved to the historian with every automatic run of the model. ERTO's capability to more precisely monitor where metering error is large or is changing over time is the first step toward proactive energy loss minimization.

Using the ERTO graphical capabilities, the users can quickly discern size of the imbalance in each header. The following figure indicates the imbalance calculated by ERTO in the fuel system for both the natural gas and the refinery gas headers in the balloons on the right side of the diagram. The balloon is indicating that the refinery gas imbalance is significant and may require investigation, based upon its larger size and change in background color.

By clicking on any balloon, the EM mass balance report is displayed, indicating the specific measurements contributing to the balance, as well as the total balance error, on a mass and percentage basis. This provides an easy way to track and correct or replace failing measurements in the system, which reduces loss and increases production capacity. The figure below shows the mass balance report for a 150 psig header, for example.

Tracking the history of the balloon mass balances assists the energy management team, including operations, engineering, and meter technicians, in ongoing analysis and improvement site-wide utility metering. The following figure shows the steam balance trending capability ERTO also provides which demonstrates each local mass balance's impact on the site-wide imbalance over time.

This figure above shows the reduction in the 30F402.PV flow measurement in the lower chart correlates to a reduction of the overall imbalance, but no correlation exists between the 10F211 measurement and the overall imbalance in the upper chart. So, ERTO highlights the specific meter requiring calibration or verification, which is 30F402.PV in this case.

In the figure above, the 60F417.PV flow measurement in the lower chart shows a strong correlation to the overall imbalance, whereas the measurement in the upper chart, 70F417.PV, shows no correlation to the imbalance. Therefore, ERTO indicates calibration or verification of the 60F417.PV is recommended in this case.

ERTO mass balance trending capability improves accuracy of instrumentation and measurement, which directly contributes to more timely identification and elimination of actual losses.

ERTO provides the ability to understand the incremental cost of utilities providing heat and horsepower to a plant or unit, as shown in the example below. This "Process Plant Cost" block calculates the amount of energy consumed or generated per unit plant feed or per unit production.

ERTO can calculate the lost opportunity or Energy Cost Gap, which is the difference between the cost of current utility operation and the lower cost that would be provided if operators were to implement the current directives for optimum operation calculated by ERTO

All the energy streams imported to or exported from the process units are included in the "Process Plant Cost" block, including accounting for their costs. So, if a process unit has a consumption of 55.5 klb/h of 600 psig steam, as in the example below, ERTO calculates the actual real-time cost of the steam, $324.68/hour in this case. With the cost of all streams into and out of the process plant, the "PPC-ALKY" in the case below, ERTO also provides the incremental cost of utilities for the process plant as a whole, as well.

Such exposure of real-time incremental cost on both the stream and plant level provides new and powerful information for system operators, engineers, and management to leverage in decision-making. Such information would not otherwise be available without ERTO.

4.    Key Performance Indicators (KPIs)

The online execution of EM can be used to calculate important Key Performance Indicators or "KPIs" related to energy. Typical KPIs calculated by the EM model and saved to history include the following:

  • Steam header imbalance
  • Incremental cost of steam for each header
  • Energy consumption per unit load or feed
  • Difference between theoretical and actual equipment performance

5.    KPI Operator Alerts

VM-EMS provides the basis for em's generation of useful real-time KPI's and KPI Operator Alerts. Operators are routinely alerted to large changes in real-time utility system operation, such as steam balances and equipment shutdowns. In the same way than EM can alert the operator of big changes, EM provides additional alerts when certain KPIs are outside defined range. Such alerts are activated either if the real-time value is outside the defined range or if the deviation of the current value from the mean is outside a defined range for a given time frame.

In either case, the operator is immediately directed to the KPI for which any real-time alert is given by EM. The following figure shows an alert caused by the real-time efficiency of the first stage of a compressor violating the defined low limit alarm. The calculated value of 61.55% has fallen below the Low Limit defined as 63%.

6.    Engineering Case Studies - "What If?" Analysis

Based on the same model used for optimization in ERTO, Engineering Case Studies can be executed for such important functions as planning for shutdowns and turnarounds, determining cost and benefit of capital investment, and seasonal operation planning. The following examples illustrate such use:

  • Planning for an upcoming equipment shutdown by simulating the expected operation in a case study to determine the most economic, reliable and environmentally safe operation of the site-wide utilities under the new condition.
  • Evaluating the cost and benefit for replacing a turbine driven pump with an electric motor.
  • Evaluating the benefit for adding a steam turbine generator against the capital investment.
  • Evaluation of a steam, power or fuel supply contract under negotiation, given expected seasonal operation of the utilities.

Improved investment and planning provided by ERTO's Case Study capability can easily double the value ERTO provides through optimization alone.

7.    Maintenance

ERTO calculates real-time equipment performance, such as boiler and turbine efficiencies, including the benefit provided and time required for cost recovery if maintenance were to be performed.

8.    Summary

VisualMesa Energy Management System provides multiple unique capabilities to industrial utility system operators, engineers, and maintenance personnel not available from any other technology solution available. Savings from real-time monitoring and optimization alone routinely provide ample return on investment to justify investment in the VisualMesa Energy Management System.

New and powerful information provided and the time saved through more structured approach to utility operation on the basis of VM-EMS's rigorous thermodynamic model increases operational reliability and can help ensure achievement of environmental targets.

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