TAS PumpMonitor is an independent system that quantifies the inefficiency cost of a pump, both currently and over its lifetime, identifies potential equipment failure before it manifests and calculates the optimum time to refurbish or replace the unit, thus minimising the total life cycle cost of the equipment.
It has been developed in South Africa by Technical Applications Software (TAS), based on 15 years of experience in developing software for the pump industry. Their products are currently in use with some of the largest pump manufacturers worldwide.
Centrifugal pumps are designed to operate within a very confined envelope:
- Each pump model has a unique performance curve based on tested readings taken at manufacture
- This curve describes the relationship between flow, head, power and efficiency over the entire flow range
- QBEP is the pump flow rate at its Best Efficiency Point (BEP) in mechanical terms
- Ideally a pump should operate between 80% and 110% of this flow
- A typical pump performance curve showing BEP and the optimum operating range:
Many pumps do not operate in the best efficiency zone for the following reasons:
- Incorrect design specifications
- Changes to system requirement
- Variable processes
- Ongoing pump wear
- ‘Quick fix’ solutions such as bypassing flow or throttling the discharge line
- Variable Speed Drives with inadequate control
- Insufficient understanding of, or focus on, pump management and its effect on production stability and costs.
LIFE CYCLE COSTS
For a typical centrifugal pump the breakdown of life cycle costs is:
- 5% capital
- 5-25% maintenance (depending on the nature of the product being pumped)
- 70-90% power
Operating pumps more efficiently, i.e. closer to the BEP, will save significant amounts of money every year arising from reduction of these cost elements. It will also have a positive effect on production stability and costs.
- Pumps consume 20% of the World’s total electrical power.
- Studies undertaken by government bodies in the EU and USA and independent articles in trade journals all indicate that potential savings of between 15-40% of this consumption are feasible arising from efficient operation.
- A pump operating outside its QBEP range will consume excessive power. This is because the pump efficiency drops off sharply both to the left and right of the BEP, and thus more power is wasted in the form of heat which is passed on to the fluid.
- Pumps operating close to optimum efficiency cost less to maintain and fail less often.
- Components such as seals, bearings and shafts seldom fail during normal operation if the pump is selected and operated correctly.
- Following the recommendations given by pump performance monitoring may result in a short-term increase in routine refurbishment in order to maintain cost-beneficial pump efficiency. However, total costs over the life of the pump will be reduced as a result
- Refurbishing before excessive wear has occurred allows components to be repaired not replaced
- Premature refurbishing, undertaken to avoid any failure and resultant production downtime, can be avoided.
- Operating pumps significantly away from their BEP will adversely effect the pump mechanically resulting in component deterioration and pump failure, incurring major costs in terms of lost
- In a process environment unstable pump operation has a negative effect on the operating efficiency and / or reliability of other equipment. For example, in the case of a mill circuit, wide fluctuations in pump performance lead directly to inefficiencies in the entire plant operation. Cyclones operate outside their optimum efficiency bands, result in greater re-circulating loads through the mill, and reduced product recoveries.
- Pumps could suffer catastrophic failures operating well off BEP, compromising plant safety
- Excessive redundancy is often designed into pumping systems to provide back-up capacity in case of failure. This results in unnecessary capital expenditure, which can be kept to a minimum by greater visibility of the operation of the pumps thus reducing the risk of breakdown.
Traditional on-site condition monitoring is inadequate on pumps:
- It is expensive in time, travel and scarce skilled manpower
- The time interval between tests is too great to detect and rectify problems timeously
- Instrumentation attached to the pump may be absent or inaccurate
- Once a problem has been detected destruction of the pump has already begun.
Remote Performance Monitoring with TAS PumpMonitor
PumpMonitor is a unique product based on TAS proprietary software and hardware and marketed exclusively by TAS Online.
- No other product enables the monitoring of pump performance remotely in the field cost effectively
- It is designed to provide hands-off monitoring of the pump operation at pre-set intervals (e.g. hourly)
- Data is collected automatically from transducers attached to the pump and sent to the TAS Online web site via the user’s existing communications infrastructure (e.g. SCADA) and/or GPRS
- PumpMonitor analyses these readings against the pump’s original performance curve and specifications to derive the current efficiency and its variance from BEP (i.e. the degree of wastage)
- This wastage is quantified and classified into wear, duty and volumetric loss in order to assist in problem identification, facilitate cost / benefit analysis of alternative solutions and allow remedial action to be taken before excessive costs are incurred or destruction of the pump commences.
- It also measures the success of the chosen remedial actions and predicts refurbishment intervals for each pump in its specific function.
- The system then allows authorised users real time remote access to the pump performance data via the Internet, giving ongoing visibility into the current operation
- This information service is supported by the TAS Online consultancy team, who provide users with periodic management reports and technical assistance in dealing with alarm conditions.
TAS PumpMonitor empowers the pump operator to select the optimum cost justifiable course of action, based on the quantified magnitude and characteristics of the efficiency loss. Some typical remedial options:
- Overhaul the pump
- Replace the impeller
- Line the pump’s wearing parts
- Replace the pump with a different model
- Trim the impeller or change the pump speed
- Install a variable speed drive
- Change the control methodology
- Make changes to the pumping system (pipes, valves)
- For balance flow type pumps, identify the optimum time to replace wearing parts
- Replace bypass or throttling valves in the system with a variable speed drive.
COST / BENEFIT ISSUES
Costs associated with the installation and ongoing operation of TAS PumpMonitor will obviously vary from site to site depending on a number of variables e.g. type and size of pump, characteristics of the product being pumped, current status of instrumentation and communications, geographical location and accessibility etc.
Similarly, the payback period for the initial capital investment will be affected by these and other factors such as maintenance history, power unit costs, degree of pump utilization etc.
These factors are examined during an initial Site Audit, conducted by TAS Online, in which costs and potential savings are estimated and a business case for installation established.
However, certain guidelines hold true for the vast majority of pumping operations:
- In large pumping applications with minimal pump wear (e.g. clear water), the costs of installing TAS PumpMonitor and the capital costs of initial relevant remedial action can be recovered from power savings alone in the short term. Payback periods of under 1 year are frequently experienced.
- In other applications with greater pump wear, savings in maintenance and plant downtime would increase while power savings may be less dramatic.
- In both cases, ongoing monitoring costs are far exceeded by savings after the initial costs of instrumentation and installation have been absorbed.
- Maintenance and refurbishment costs may rise marginally in the short term as inefficient equipment is replaced or refurbished at an earlier stage. These will subsequently return to previous levels or lower.
- Certain ancillary costs can be reduced or eliminated:
- PumpMonitor can derive flows accurately after initial calibration so relatively expensive flow meters are not required
- On-site performance testing, either for routine checking or after installation / refurbishing, is more accurately undertaken through PumpMonitor.
- The saving in power consumption will have a positive environmental impact and allow the user to accumulate Carbon Credits
- If a phased approach is preferred, initial savings can be used to fund later stages of implementation.
PumpMonitor analyses the incoming data, quantifies the current level of wastage and classifies it as detailed above. These analyses facilitate cost / benefit evaluation of possible solutions and allow remedial action to be taken before excessive costs are incurred or destruction of the pump commences.
They also establish a baseline against which the success of improvements such as pump coating, trimming impellers or changing the pump speed or model can be measured.
Shortcomings in pump configuration are also exposed e.g. incorrect pump and / or motor selection, one or more pumps in a group operating in series or parallel which is largely or totally redundant.
Taken together this body of information provides full visibility of pump performance to the operator and/or management. This facilitates operation as close to BEP as possible within production constraints which, in turn, delivers major power consumption and maintenance cost savings.
In addition, the use of TAS PumpMonitor offers many indirect benefits:
- Operation of the system and interpretation of the output require minimal user expertise. It also enables best practices for pump operation in a given environment to be established, monitored and, if necessary, amended.
- Early warning is provided of significant changes in performance and / or impending equipment failure with a number of important consequences:
- Improved safety
- Improved plant reliability, which reduces costly production downtime.
- Less redundancy needs to be designed into new pump stations and surplus pumps from existing installations can be moved to other sites giving long term capital cost reduction
- Improved plant stability.
- Wasteful travel by skilled staff to perform on-site inspections is greatly reduced. Also such test results are often incomplete due to insufficient on site instrumentation.
- Disputes between the pump user & the OEM can be resolved by reference to independent performance data stored by PumpMonitor
- TAS PumpMonitor information can also be used to facilitate a power load shifting project.