Emission control not strict enough – burner supplier

3rd November 2006 By: Clement Deane

South Africa is gravely behind with regard to emissioncontrol and the policing thereof, burner equipment supplier The Combustion Group (TCG) tells Engineering News.

Representatives of the company explain that, with the government looking into controlling gas emissions through the Air Quality Act (39 of 2004), industry is required to monitor its emissions and contain anything that is harmful to the environment.

However, the company believes that the act is not being sufficientlyenforced and that companies are not monitoring their emissionseffectively.

An article published in The Mercury in August last year, entitled ‘Air Quality Act could be toothless watchdog for 5 to 10 years’, suggests that the Air Quality Act may not necessarily take effect, or be as effective, for up to another decade.

In the article, a senior CSIR air-quality scientist, Gregg Scott, comments that there is a misconception that the act had taken effect in early 2005, when President Thabo Mbeki had assented to it.

He says that government had taken the decision to implement the law in stages because of a shortage of qualified staff to implement or police the legislation.

Even so, it is believed that the law will drastically change the manage-ment of emissions when it does come into full effect.

The current task at hand is the effective monitoring and control of emissions from stacks.

Some of the products supplied by TCG are designed to monitor emissions from stacks and the datareceived from the stacks can be used to determine the efficiency of the burners.

Flame management and tech-nical sales representative Susan Shepherd says that, if the burners are maintained properly, there will be a saving for the client in terms of cost and efficiency.

Inefficient burners can lead to harmful gases being released into theatmosphere and, with the energysector seen as the number-one contributor to sulphur dioxide (SO2), carbon monoxide (CO), and carbon dioxide (CO2) emissions in South Africa, it is important that industry considers action towards limitingthe release of noxious gases.

The amount of harmful gasreleased is often directly related to the efficiency of the burners.

An efficient burner releases far less harmful gas than an inefficient one.

Therefore, companies see thebenefit in maintaining their burners, especially when reports show the emission of dangerous gases.

However, in most cases thisapplies only to SO2 and CO emissions.

TCG director Trevor Lotter says that, even if a burner were tooperate at optimum efficiency,nitrous oxide (NOX) emissions could still be emitted.

“There’s a problem withcompanies not seeing the benefitin limiting the emissions. They know that CO and SO2 escaping through the stacks mean that the machine isn’t running as effectively as it can. But, they’ll often decline a low-NOX burner because they do not see an efficiency boost with one.” The challenge now, says Lotter, is to create awareness in the drive for monitoring stack emissions.

He believes that companies need to have correlation curves for data reporting to monitor what is being let through in the process.

“South Africa has a problem with enforcing this legislation and there is still much left to do,” says Lotter.

The company is currently busywith a final tender on a project where a portion of the project requiresliquor destructors.

TCG is also looking into apotential project, with a big mininghouse, for the prevention ofmethane, which may mean the prospective earning of carbon credits.

Prevention and control
TCG represents a wide selectionof international corporations dedi-cated to burners and monitoring equipment and supplies products designed to monitor stack emissions, as well as products to monitorequipment efficiency.

One such product is the Paragon Scanner, which, designed bycommercial and industrial flame safeguard and combustion controls producer Fireye, is a microproces-sor-based flame analysis device that uses solid-state flame detection sensors.

It provides high-integrity sensing of multiple flame properties, including amplitude, flicker frequency for flame safeguard, and flame temperature, for emissions information.

According to European operations manager Dave Probyn, this allows experienced operators tobe informed of the changes in combustion, which occur occasionallyowing to phenomena such as fuelvariations and burner variations.

This information can be displayed on a PC screen to provide information about the burner opera-tion in a single, and multiburnerenvironment.

He explains that, in these environ-ments, the variations of the indivi-dual burners are often far too difficult to notice from the conventional instrumentation.

“The Paragon adds the feature of flame temperature measurement, which is quite relevant in acquiring low NOX, as NOX creation increasesquite dramatically from around1 500 ˚C upwards. By measuringthe temperature of individual flame, it provides advanced warning of combustion changes which arelikely to create unacceptable levels of emissions,” says Probyn.

With the fitting of an internaltemperature relay, which can beset to operate based on detectedtemperature, a warning can begenerated at the instrument which can be sent to the plant DCS toprovide an alarm signal.

According to Probyn, “These two measurements, flame quality and flame temperature, are further tools available, above and beyond the basic requirement of flame safeguard, to the plant operators in their endeavours to maintain clean, safe, and efficient combustion.” Other products on offer include Maxon’s SmartFire.

Supplier of burners and combustion equipment Maxon has developed a product that it says makes set-up and operation easy, whichautomatically compensate forchanges in operating conditions.

Also, the company says that this product improves the fuel-to-airratio efficiency, it has automatic, real-time continuous adjustment, and it minimises emissions.

Emission monitoring
The Forney corporation, in partnership with provider of mercuryemission monitoring solutions and CEM system equipment Tekran, has developed a product designed to accurately analyse and monitor mercury levels in stacks.

The Forney/Tekran Series 3300 analyser uses atomic fluorescence and gold amalgamation, which is more sensitive than atomic absorption or direct atomic fluorescence.

It eliminates interferences from the stack gas matrix, and, according to marketing manager of Forney Corporation Richard Hovan, theexclusive benefit of pure gold pre-cipitation means that the detectorbaseline drift does not affectresults.

Also, the product is inherently linear, with a dynamic range that has over five orders of magnitude greater than other technologies, states Hovan.

“Mercury control is only as effective as the method of monitoring for system loop control.” He states that the installation of a highly accurate and reliable mercury continuous emissions monitoring (HgCEM) system us critical for proper control.

“In addition,” says Hovan, “with the requirements of reporting and possible trading credits (typical for the US), an extra return on investment can be realised.” He explains that real-time continuous measurement of mercuryis far more challenging thanmeasurement of compounds such as nitrous oxide and SO2, and itrequires more selective and con-trolled technologies.

Complicating factors includeextremely low levels of mercury in the flue gas (gas that escapesthrough the stack), as well aspotential interferences of flue gasconstituents, such as the potentiallytoxic heavy-metal selenium, or other gasses including NOX, O2 and SO2.

Under these conditions, simply diluting the stack gas only reducesthe concentration of interfering constituents.

According to Hovan, the remaining stack gas concentrations are still high enough to impede the detection of mercury, potentially causinginconsistent reporting of mercury emissions.