Low temperature pyrolysis reactor

A lab-scale fixed bed batch reactor allows to heat samples uniformly and slowly to a temperature of maximum 430°C. To compensate for heat losses through the external wall and to assist in uniform sample heating, a tube furnace (Nabertherm, RS 80/300/11, 1.8 kW) is placed around the reactor. The pyrolysis reactor consists of a stainless steel vertical tube of 7 cm diameter and 30 cm long, containing a grid at 15 cm to support the sample (in a glass cup) and 2 flanges at the top and bottom to easily fill and empty the reactor. The gas, heated by an electrical heater (Omega, AHP 7652, 750 W), which is controlled via a PID controller (Omega, CN 8500), enters the reactor at the bottom. The connecting tube between heater and reactor inlet is covered by an electrically heated tape to compensate for heat losses to the surroundings.

To clean the outlet gas consisting of nitrogen, organics, tars and possibly metals, a series of impingers is added. To prevent clogging of the pressure reduction valve placed at the outlet of the reactor a first impinger is placed before the pressure reduction valve. This impinger was designed to capture all tar components and to operate at elevated pressure (up to 5 bar gage pressure). After the impinger, an expansion valve is placed to reduce the pressure. After the expansion valve two impingers are placed to capture all metal emissions (if there are any). Thermocouples have been inserted in the centre (radial) of the reactor tube at different heights: one just below the grid (T1), one just above the grid near the sample (T2) and one 20 cm above the grid (T3). A manometer has been placed on top of the reactor tube (P2) to monitor the reactor pressure.