Facilty Design & Management / Energy Management / Regulatory Guidance

Controlling Emissions the BAT Way

The release of volatile organic compounds into the atmosphere is coming under intense scrutiny

With an ever-increasing number of processing plants coming on stream worldwide to keep up with the rapidly expanding pharmaceutical and biotechnology industries, the focus on the release of volatile organic compounds (VOCs) into the atmosphere is coming under intense scrutiny by environmental authorities.

VOC is the common descriptor for a wide variety of hydrocarbon-containing chemicals. They are numerous, varied and ubiquitous, and the risks associated with them are aggravated by the fact that hazardous concentrations are usually very low and the health issues they can cause can be accumulative and slow to develop. The release of VOCs from industrial processes not only poses a direct potential hazard to human health, but their release also has more widespread environmentally damaging consequences including their carbon footprint, as well as the financial costs involved in their replacement.

IMPACT OF THE IED
The European Commission's Industrial Emissions Directive (IED) published in November 2010 standardizes the maximum emissions levels across a very broad range of industries throughout the European Union (EU). The IED reorganized seven existing and overlapping directives related to industrial emissions — including the Solvent Emissions Directive (SED) — into a single, clear and coherent legislative instrument. Its implications will be cascaded through national governments into local or provincial legislation of EU member countries and enforced by inspectors in their local authorities.

One of the main reasons for the recast of the Directive was an inadequate and incoherent application of “Best Available Techniques” (BAT) to optimize all-round environmental performance across the EU. Additionally, because the relevant provisions were spread across seven different legal instruments, it was deemed to place an unnecessary administrative burden on manufacturers.

Many primary industrial sectors in the EU are already well regulated in terms of emissions, but the aim of the IED is to harmonize and standardize how they are regulated and how BAT is utilized across the entire region by setting minimum emissions benchmarks and improving the quality and consistency of implementation.

The IED will describe how emissions control, measuring and monitoring should take place and will be driven by an increase in the use of BATs via revised “BAT Reference” (BREF) documents in order to obtain better consistency of implementation across the EU. The BAT approach is aimed at identifying and applying the best technology available worldwide and applying it as cost effectively as possible on an industrial scale to reduce emissions and achieve a high level of environmental protection. The BREF documents contain the maximum emissions values for many industries, from refining to pharmaceutical manufacture.

The IED principally focuses on 13 specific pollutants or polluting substances to air — among them NOx, SO2 and carbon monoxide — but also one category of particular relevance to plants involved in the manufacture of pharmaceutical ingredients: VOCs.

A major source of man-made VOCs is solvents. As with other VOCs, when solvents increase in temperature, as is often the case in production processes, they evaporate and enter the atmosphere where they can be damaging to the environment, create nuisance odors, potentially cause a variety of health problems. There are several different technologies to reduce or remove solvents from exhaust streams mainly involving destruction or recovery and reuse depending on the recovery value and concentration of the solvents.

CONTROLLING EMISSIONS
One of the most effective ways — and a recognized BAT — to abate solvent vapors is to condense and capture them using liquid nitrogen as a cooling media in a process called low temperature or cryogenic condensation. Liquid nitrogen has tremendous cooling capacity, so when it is used to cool the condenser, VOC emissions can rapidly be reduced to very low levels. Subject to purity requirements, recovered solvents can sometimes then be reused in the industrial process.

BAT IN ACTION AT AESICA
Aesica is a leading UK-based contract manufacturer for formulated products and active pharmaceutical ingredients (APIs). Its products are used in the formulation of medications such as anti-inflammatories, analgesics and anti-depressants, among many others. Founded in 2004 and with approximately 1,300 employees, Aesica is a fast-growing company with a global footprint including operations spanning Europe, North America and Asia. It was purchased last year by Consort Medical Plc, though there are no plans for a name change at present.

The company is committed to being a good corporate citizen and holding itself to the highest standards of environmental management. It has been recognized with industry awards for its environmental performance, and as it continues to expand its portfolio, Aesica makes every effort to maintain or raise its emission control standards.

Aesica's state-of-the-art facilities in Cramlington in the UK are continuously developing and manufacturing new APIs and formulated products for a growing number of markets. These new products sometimes present fresh emission control challenges, particularly in relation to organic solvents. Organic solvents are required as reaction media in many vital pharmaceutical production processes including separation, filtration, distillation and purification of synthesis products. The pharmaceutical industry is one of the largest users of organic solvents and as such, has an obligation to constantly review and implement BAT in order to comply with existing VOC emissions legislation.

There are several methods to combat VOC emissions in production gas streams resulting from the use of solvents: heat exchangers employing the use of refrigerants to condense the solvents; adsorption through the use of activated carbon; incineration of the emissions via a thermal oxidizer or employment of absorption technology via water or chemical scrubbers. However, each has its limitations and disadvantages. Refrigerants themselves are under scrutiny for their contribution to global warming and remain targets for increasingly rigorous legislation. The working fluid from chemical scrubbers may absorb the solvents, but the contaminated liquid then has to be sent off site for treatment or incineration. Technology involving activated carbon, again, ultimately only shifts and increases the disposal problem and results in further costs to the manufacturer; and thermal oxidization, while destroying VOCs via thermal combustion, consumes natural gas and results in the creation of carbon dioxide (CO2) which is then vented into the atmosphere.

In contrast, a BAT technology that has demonstrated itself not only as highly effective at solvent emissions abatement, but at mitigating disposal issues and being significantly more environmentally friendly, involves the use of cryogenic nitrogen. Emission abatement by liquid nitrogen relies on condensing the solvents in the process gas into liquid droplets which can be removed from the exhaust gas stream. The extremely low temperature of liquid nitrogen means that it is possible to capture 99 percent of virtually every known solvent, making it a highly effective emissions compliance technology. The unique additional advantage, however, is that the resultant gaseous nitrogen can then be used directly in chemical processes, frequently acting as an inerting agent to prevent flammable atmospheres. Without a cryogenic condenser, heat in the form of steam is often used to vaporize the nitrogen, thus costing money.

One of the most commonly used and highly efficient solvents — dichloromethane (DCM) — is released, for instance, from reactor vessels during the production of pharmaceuticals. While it is only suspected of having carcinogenic properties at high doses, precautionary limits have been put on its emissions by the EU. DCM, for example, can be condensed and captured at -85°C using this cryogenic technology
Like most chemical and pharmaceutical manufacturers, Aesica uses gaseous nitrogen as an inerting and purging agent to prevent explosions or fires when flammable solvents are present. Gaseous nitrogen is typically generated by evaporating liquid nitrogen, which is stored at cryogenic temperatures (-177° C). Usually supplied in cryogenic form for ease of transport and storage, liquid nitrogen also possesses a lot of cooling potential. So, the same nitrogen supplied in liquid form can be employed not only for the cooling power it provides for solvent capture, but also for use in its gaseous form for inerting, purging and fire prevention processes. As the LIN remains uncontaminated in the emissions abatement process and does not come into direct contact with the solvents, it is entirely usable for these other processes. Additionally, the virtually complete recovery of solvents is achieved with no contamination from fluids that would be used as part of a scrubbing technique, for example, so the valuable solvents can be recycled and reused by the manufacturer, helping to reduce operating costs.

Linde's cryo-condensation VOC emissions control technology, CIRRUS®VEC, helps Aesica meet its VOC abatement challenges. The benefits of the solution extend beyond environmental protection to include low energy consumption, solvent recycling capabilities and a lower carbon footprint as “waste” cold can be used and clean nitrogen can be recycled. As Mike Battrum, group engineering manager for Aesica comments: “We are committed to minimizing the environmental impact of our production activities. We reviewed the options for solvent emissions control for one of our exhaust gas streams and Linde's cryo-condensation technology seemed ideally suited. One of the key advantages for our business is that by making use of the cold energy in the liquid nitrogen we already consumed, we achieve our environmental objectives with minimal additional running cost and energy consumption, so it is a very elegant and efficient solution.”

The modular, simple and compact design of the system has provided Aesica the flexibility to add to its existing system and increase VOC abatement capabilities in the future. As Mike Battrum explains: “Aesica is rapidly expanding and diversifying its production capabilities with new products for a growing number of customers. The ability to cut the emissions of a wide range of very volatile solvents will enable Aesica to meet market need and environmental needs while being commercially competitive well into the future.”

DETECTION AND MONITORING
Beyond the technologies employed within the plant to control emissions, the monitoring, detection and analysis of industrial VOCs also demands continuous innovation to assist companies in complying with tightening legislation and mitigating the financial implications of VOC emissions. Certainly the financial factor is a significant incentive to keep VOCs inside the process. If emitted, they not only pose possible health issues and generally become an atmospheric irritation, but companies are rapidly becoming aware that every gram that is lost means money lost.

By measuring emissions from specific vent points, processing plants are able to determine if any of their raw materials, process intermediates or end-products are being emitted and if so, determine the emission source and address the underlying processing problem. In the pharmaceutical industry, this applies to a broad spectrum of components.

Increasing regulatory requirements have created more rigorous demands in measurement and, with new compounds to evaluate, laboratories performing environmental analysis of air quality are constantly confronted with new challenges. They find themselves under continuous pressure to expand their scope and expertise. Innovative, next-generation calibration gas mixtures are essential to enable new air quality analysis technologies and meet the needs of laboratories engaged in process control, emissions monitoring and research.

Most industrial processing plants generally have their own unique signature of emissions based on their specific processes, the raw materials used and the final product being produced. With the ever-increasing awareness of the potential for negative health effects from the air we breathe, the requirements for low-level traceable calibration standards are becoming of greater importance. Emerging knowledge and technologies are the driving forces behind the measurement of many more compounds and at ever-lower concentrations.

Calibration is vital for accurate measurement in order to produce reliable information about the quality of the environment around us. Technologically complex and sophisticated gas standards for calibration are becoming essential to deliver greater efficiency and confidence to labs.

THE FUTURE
As often happens when legislation is updated in a specific country or region, other countries outside its range adopt certain principles as a blueprint or starting point for their own local legislation. This is why many of the changes taking place in environmental legislation in the EU reflect developments in the United States, where authorities like the Environmental Protection Agency (EPA) are also striving to level the playing fields across industries.

For example, a trend that is likely to be taken up in the EU in the future is the move towards speciation analysis in the VOC arena. Speciation analysis is defined as the separation and quantification of different chemical forms of a particular element. Until recently, determining total element concentrations was thought to be sufficient for environmental considerations, but now it has been recognized that it is important to understand the toxicological properties of the sample's various components in order to manage environment risk more accurately.

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