Benefiting from waste heat recovery

Northmore Gordon — Tue, 19 Nov 2019 02:54:38 +0000

Do you have waste heat and don’t know what to do with it?

Energy costs are hurting business. Yet often there are concentrated sources of energy going to waste in manufacturing environments. Recovering waste heat back into processes can save substantial amounts of energy cost, and increase the spare heating capacity of existing systems.

Data matters

Doing heat recovery well requires good data and a good understanding of the existing systems, combined with a methodical approach to determining the optimum solution. Especially where there are multiple heat sources and heat sinks.

A Pinch Analysis is the gold standard for optimising heat recovery in your plant, but discrete feasibility studies are also very useful.

How can waste heat be recovered and used?

Waste heat can be available from a range of sources, including exhaust air from gas burners, de-superheating a refrigerant prior to latent heat rejection, oil coolant systems on air compressor and refrigeration compressors, wastewater discharge, furnace exhaust, refrigeration condensers, and many other sources.

Direct heat exchange using a tube or plate heat exchanger is a simple method for heat recovery, however, there are other methods. For example, a waste heat source at a relatively low temperature can be used to heat a process flow to a higher temperature using a heat pump. Indirect heat exchange can be achieved using a hot oil circuit where the heat source is too hot for direct heat exchange with the heat sink.

Waste heat can also be used in many ways:

re-heat combustion air for a furnace or oven
Use directly in a dryer
Heat water in pasteurisers
Generate electricity using an Organic Rankine Cycle or Steam turbine to drive a generator
Generate hot water up to 100°C or steam at up to 160^oC by extracting heat from a lower temperature waste heat source..

Optimising waste heat recovery

Where a site has numerous heat sources and sinks, a “Pinch” analysis can be used to determine the optimum combination of heat recovery alternatives for that site. PinCH analysis attempts to identify similar heat loads nearest to available heat sources and minimise the use of artificial heating (e.g. from natural gas or electricity). The optimum combination from a heat recovery perspective is not always practical in a retrofit though, so the key is to determine how to get as close to the optimum as possible in a practical and cost-effective way.

Implementing waste heat recovery

Implementation should take into account a number of factors:

The operating characteristics of the process, to ensure the implementation doesn’t impact on output, product quality, process reliability or productivity.
Staging of projects if possible, to minimise process disruption and spread capital spend.
Heat quality available (temperature and rate of supply) and proximity to heating loads
Measurement, monitoring, and verification so that energy savings can be measured over time, and energy-saving or carbon abatement certificates can be created
Future plans for expansion or plant upgrades

Make informed and smart decisions about heat recovery.

Northmore Gordon is passionate about helping large industrial and commercial customers increase energy productivity. We have done a number of pre-feasibility studies and business cases specifically investigating waste heat recovery options. We can help you identify and quantify your heat sinks and sources, determine the optimum solution for your situation, and develop an investment-grade business case.

For more specific details on heat recovery contact Andrew at a.clarke@northmoregordon.com

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Creating a gas measurement and monitoring plan for your industrial site

Northmore Gordon — Tue, 09 Jul 2019 04:25:28 +0000

Gas costs are hurting business and have been for some time. Making informed and smart decisions using good data can help reduce operating costs. The measurement and monitoring of energy flows such as gas, steam, hot water, hot air or electricity is needed, however it can be technically challenging and often expensive.

For these reasons, a well-thought-out measurement and monitoring plan is an essential part of any industrial site, and can be achieved using a 5-step process:

Step 1 – Specify the goal and understand what is already known.
Step 2 – Prioritise what to measure.
Step 3 – Investigate and select energy management software and long term data storage
solution.
Step 4 – Specify and select suitable meters and their communication system.
Step 5 – Develop a budget and implementation plan

Step 1 – Specify the goal and understand what is already known.
This is the essential part of a metering and monitoring upgrade as it determines the useful data and how it will be used. Other equally valid goals could be:

“Determine the Coefficient of Performance (COP) of the refrigeration system to assist in developing a business case for its replacement”
“Understand how much one area of the plant costs to run”
“Establish plant energy performance KPIs and track them”

Once the objective is clear, spend time determining what data is available and what additional metering is necessary. In many cases some metering is already in place but unused.

Step 2 – Prioritise what to measure.
Keeping in mind the initial goal, determine the highest priority energy flows that need to be measured. Start by building a preliminary energy balance on either the site, a specific utility, a plant area or an individual piece of equipment. It isn’t necessarily the largest energy users that are the priority.

Step 3 – Investigate and select energy management software and long term data storage solution
Before jumping in to select meters, consider how to collect and store the data, as well as who needs the information. The purpose of metering is to provide data that is usable, and insights are acted upon. Data collection may use a pre-existing data management or SCADA system, or a new online portal.
The range of people needing to access the data might range from plant operators, plant managers, energy managers, or compliance personnel.

Step 4 – Specify and select suitable meters and their communication system.
There are hundreds of different meters available on the market, and all of them have different benefits and drawbacks. Consider things like precision, repeatability, flow range, method of installation and format of the data being reported.

Step 5 – Develop a budget and implementation plan.
The budget and implementation plan of the metering and monitoring project must consider:

Schedule of works to be completed.
Plant down time and commissioning requirements.
Communication and data storage installation.
Safety of the works carried out.
New procedures or responsibilities to utilise the data
Meter validation and ongoing meter maintenance.

Meter validation is often overlooked. To test if the meter is accurate, first compare its data with what is expected, or with other meters up or downstream. At Northmore Gordon we often find meters in the field that have been incorrectly reporting energy usage for years!

Make informed and smart decisions about energy usage.
Acting on the data is what really matters. Software tools exist that are designed to aggregate data from industrial data management systems and present it in a way that is easy to understand. If information is easy to understand, it is more likely to be trusted and acted upon.

Northmore Gordon is passionate about helping large industrial and commercial customers increase energy productivity. We can help you design a metering, monitoring and energy management solution for your specific needs.

For more specific details on gas metering and monitoring, you might want to check out the NSW OEH publication co-authored by Northmore Gordon: “Gas Measurement and Monitoring Guide” or contact me.

Alex Holdsworth
Consultant, Northmore Gordon
a.holdsworth@northmoregordon.com

The post Creating a gas measurement and monitoring plan for your industrial site appeared first on Northmore Gordon.

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Benefiting from waste heat recovery

Creating a gas measurement and monitoring plan for your industrial site