Author: Nick Carter, chartered engineer, is technical director of Simdean Envirotec Ltd Industrial pollution and odour control specialist Simdean Envirotec has launched a plasma-based hazardous waste destruction system into Ireland and the UK and which has been developed principally for the pharmaceutical, oil, chemical and gas industries. The system provides an alternative to incineration and landfill, the only options currently available. Both are controversial and both are contested on environmental and health grounds. This is because of the high levels of dioxins contained in the ash that is left after hazardous waste has been incinerated: polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). These dioxins, which are environmental pollutants and a health risk, are formed not from a single compound but a mixture of different constituents that combine during high level combustion. The ash containing the dioxins is either transported to treatment plants or sent for landfill. A proportion of the dioxins also escape into the environment via exhaust gases from the incineration plant. [caption id="attachment_23295" align="alignright" width="300"]Simdean 1 Plasma reactor[/caption] The new plasma system’s novel technology completely eliminates even the most concentrated hazardous waste, avoiding all issues and problems associated with incineration and landfill while providing a significant cost advantage over both of these methods of disposal.

The plasma technology

The company behind the patented plasma system – Environmental Systems and Treatment (EST) - was established in Israel in 2004 by a team of scientists and engineers. The team worked for six years on the development of the plasma technology before launching it as a commercial enterprise in 2010. The system uses extremely high temperatures (2000°C – 4500°C) to instantaneously destroy a wide range of wastes, leaving only the constituent atoms. These are then transformed into a non-hazardous ionised gas for emission to the atmosphere. In some cases they are also used as a basis for separate commercial products. The system is equally effective in treating wastes in the form of liquids, slurries or contaminated gases including halogenated waste and halogen acids. The plasma installation is capable of integrating into the client’s production line, eliminating the need to transport or store waste products, which is expensive, complicated and damaging to the environment. The process, which can easily be modified and calibrated to suit most production lines, is safe, user-friendly and simple to operate. Emissions from the system process comply with all international standards and regulations.asim1

System overview

The system’s technology consists of four parts:
  • Plasma reactor: decomposition of the waste by the plasma stream;
  • Cooling system: rapid cooling (quench system) of the output gaseous mixture. This prevents the formation of undesirable byproducts such as dioxins and NOx;
  • Main scrubbing system: additional cooling of the gaseous mixture from 450°C to 80°C and main absorption of the halogen acids by process water;
  • Ecological scrubbing system: additional cleaning of the exit gas so that any emissions to the atmosphere are non-hazardous and meet environmental regulations.

The plasma process

  • The waste stream is treated by the plasma stream generated in the reactor. The high temperature in the plasma field can be adjusted depending on the type of chemical waste;
  • The extreme temperature instantaneously disintegrates the waste molecules, leaving only the constituent atoms. High-temperature plasma is generated by initiating a powerful electrical discharge into air or other gas, such as nitrogen, argon and steam;
  • The hot gas mixture undergoes a rapid cooling phase in order to prevent formation of non-desirable compounds such as dioxins, furans and NOx;
  • Output products include water, CO2 and halogen acids (in the case of halogenated waste treatment). These products are fed into a scrubbing system, where they undergo absorption of the halogen acids and additional cooling;
  • The gas stream is recovered by the ecological scrubbing system. The exit gas is clean so that any emissions to the atmosphere are non-hazardous and meet all environmental regulations.

Applications

  • Hazardous organic waste;
  • Toxic waste;
  • Medical biochemical waste;
  • Halogenated waste;
  • Gaseous waste;
  • Liquid and suspension waste;
  • Industrial and laboratory solvent waste;
  • PCBs.

Downstream treatment of liquid/chemical waste/suspension

  • The liquid and slurry wastes are supplied to the reactor by a special pump. They pass through an atomiser and go directly to a plasma jet generated by a DC non-transferred plasma torch;
  • The interaction between the waste streams and the high-temperature plasma jet destroys practically all thermo-stable components contained in the waste, gasifies  organic compositions to CO2 and H2O and forms halogen acids;
  • The formed products of hot gas mixture are then exposed to rapid cooling (quenching). As a result of the cooling process the system produces water vapour, CO2 and gaseous halogen acids;
  • After quenching, the gas flow proceeds to a specific gas cleaning system, wherein the decomposition products are separated into liquid and gas phases. If required the acid gas solutions can be used as a separate reusable commercial product;
  • Finally the exhaust gases (containing no organic components) are disposed via an exhaust stack, in accordance with local environmental standards.
Treated materials The technology currently treats hazardous organic chemical waste, toxic chemical waste, medical and biochemical chemical waste, halogenated chemical waste and gaseous chemical waste. Liquid chemical waste/suspension:
  • Contaminated solvents such as methylene chloride, toluene and xylene;
  • Chemical waste from the production of halogenated organic material (e.g. bromo-chloro-fluoro-organic);
  • Chemical waste from the production processes in the chemical, pharmaceutical and pesticide industries;
  • Heavy fraction from refinery processes.

Upstream gas waste treatment

Here contaminated gas is supplied to a special gas reactor directly from the production line. This happens in real time due to suction pressure levels in the reactor. The same essential processes of molecular disintegration, cooling, main scrubbing and ecological scrubbing are then followed. Treated materials The system is designed to treat gases such as methyl chloride, methyl bromide, ethyl oxide, dioxides, isopropyl alcohol (IPA), pollutant gas emissions containing methylene chloride and others. Gas waste treatment specifications
  • Unit Dimensions:  width 1.80 length 1.10, height 2.50
  • Electricity Supply : 380/415V 3Ph  50 Hz
  • Power requirement: 30-40 KW
System utility requirements
  • Cooling water: 5-7 m3 /hr, 280°C ( closed loop )
  • Deionised  water: 300 lit (needed only once)
  • Process Compressed air – 6 barg,
  • Instrument air- 6 barg
Materials of construction
  • Contact parts – stainless steel
  • Programmable - fully controlled with advanced PLC including an HMI touch screen
Communication  The system’s local PLC can be connected to the main control room or SCADA system if required Installation
  • As part of the existing production-line
  • Connected to the customer’s absorption system – with potential to produce a recycled gasLayout 1

Operation and safety

The system is user-friendly, easy to operate and maintain, and safe according to HAZOP Resume:
  • Interlocks for safety operation;
  • The system is sealed against surrounding environment and is constantly over pressurised;
  • Operates continuously in accordance with customers’ specific needs – provides full control of process parameters by state of the art touch panel;
  • Operation on demand – inertia free system;
  • Designed in compliance with European standards (CE), including power supply and PLC control.

Environmental benefits

The safe elimination of hazardous liquid and gaseous waste is one of the top issues on today’s environmental agenda. To date reliance on incineration and landfill could not be avoided – but now there is an alternative technology that can be quickly incorporated into existing production lines to deliver immediate environmental and financial benefits. With the plasma system and its principle of zero waste discharge, it’s not only hazardous waste that’s eliminated but also all of the contentious issues that accompany incineration and landfill. www.simdean.co.uk