Project EE – Water Quench Tower, CleanPulse Filter, Reagent Dosing and for Tyre Pyrolysis Plant in Poland

Problem

The developed world creates a huge quantity of waste tyres. Due to the quantity, durability and ecologically problematic disposal methods which exist, additional solutions to disposal are needed.

Our client is a process engineering company who were assisting investors to create a tyre pyrolysis plant in Poland. This process cooks tyres to output various products which have industry value such as an oily liquid to be used as fuel and a gas which can also be used as fuel. The waste tyres are granulated before pyrolysing.

The outgoing gases from the plant need treatment and this is where Filter Designs play their part

Solution

Our solution was a flue gas treatment plant. Our scope included:

• Ducting
• Hot gas quench tower, quenching from 1300˚C to 200˚C
• Duty standby water quench skid
• Air dilution and quench
• Hot gas bag filter with insulation and cladding
• Offline cleaning capable bag filter
• Fan
• Sodium bicarbonate injection
• Activated carbon injection
• Control system

Details

The process ends in a hot gas chamber with refractory lined ducting. From this point, Filter Designs connect to our quench tower. In this tower, the incoming gases are quenched with an atomised jet of water using a specialist lance. The temperature is controlled by increasing the flow of water to maintain a target temperature. This hysteresis can be tracked in a graph on the control panel.

The water supply is managed and controlled using a combination of control panel programming and the ‘quench’ skid.

The quench skid provides a reservoir of water and measures water flow, air flow and air pressure and a series of solenoids for control. It has a duty pump and standby pump to allow resilience to failure, since the quench cooling is critical to the downstream components.

As a secondary quench we use air. This allows ambient air into the system to further fine tune the target temperature and also as a backup system. This fails to an open position to provide cooling in the case of air or power loss.

To abate dioxins furans and heavy metals which may be present in the gas stream, we provide the facility to inject activated carbon. This is done on a suction line to the ducting before the bag filter and incorporates a feeder of in-house design. The feed rate is adjustable to suit final air volumes.

The skid is assembled in the fabrication works and is of our own proven in-house design.

The process creates acid gases, which we can neutralise by introducing sodium bicarbonate. Depending on the consumption which we evaluate at the design stage, we can provide a small hopper like the PAC skid above, or a bulk bag dosing station as in this image, or a silo which can have a single, double or triple outlet on sites with multiple streams.

In this case, the use required a bulk bag frame skid. This skid is again assembled in the fabrication works as a complete unit which minimises assembly time on site.

Due to the possibility of high CO in the gas composition, the filter is fitted with Stuvex explosion panels. These provide a weak spot in the filter which give way in the event of an explosion. Should such an event occur, a small wire encase in a brittle outer shell will fracture and indicate to the control panel which will then shut down the ID fan to prevent any flames being propagated or a fire fed with further oxygen.

Although this may seem dramatic, it is certainly better than the alternative which is that an explosion occurs within the filter, a large gas expansion occurs with nowhere for the gases to go other than either back down the process or escape by contorting the filter body.

The two explosion panels give some security and demonstrate due diligence for process risks.

The control panel is a modern processor controller system with HMI panel interface. This way, the flue gas treatment part of the project can be commissioned separately to the main system, but with Ethernet and profibus links, can integrate seamlessly with the main SCADA system and clients DCS.

One of the many HMI screens represents the system process and instrument drawing to give quick touchscreen access to the whole flue gas treatment plant.

This allows people who are not familiar with the system to navigate easily around the system.

Parts of the control system are more complex and are password protected. Many involved settings can be made here, but are restricted to engineers with suitable process understanding.