Test Facility

The test facility for assessment of absorbent performance comprises:

  1. A TGA apparatus (Q50 model, TA Instruments) fully automated, in which cycle stability tests are performed. A typical cycle consists of the following steps:

    • Exposure of the calcined material to CO2 flow at 600 or 650°C for 2-10 min,
    • Switching to Ar flow and heating with a rate of 10°C/min to 800°C to decompose the carbonate,
    • Cooling with a rate of 15°C/min to 600 or 650°C under Ar flow. The absorbent performance is directly assessed by the weight increase of the sample upon exposure to CO2.

  2. A fixed-bed reactor for studies of absorption and reaction processes under transient conditions. The reactor can be fed with gaseous reactants via two independent lines. Both gas lines have mass flow controllers for accurate preparation and control of mixtures with varying composition. A chromatographic 6-port valve can be used for introducing pulses to the reactor, while a 4-port valve is employed for step changes in the reactor feed. An on-line quadrupole mass spectrometer is used to monitor the composition of the effluent streams. Cycle stability tests in the reactor system are carried out using CO2 concentrations in the range of 5-15% in the carrier gas. 4% Ar is also added to the carrier gas (He) as a reference. The absorbent performance is indirectly assessed by the measurement of the CO2 response in the reactor product gas.

  3. An ambient-temperature fluidized-bed for assessment of attrition of natural and modified absorbents using N2 as fluidization medium. Attrition is measured by sieving of the bed material before and after fluidization and measuring its particle size distribution. The technique is used for fast screening of modified absorbents in order to select the most promising candidates, which will be studied in more detail at the facilities of the other partners.

*Physicochemical characterization of absorbent materials is carried out using XRD, SEM and N2 physisorption.

a) Flow sheet of test facility with circulating fluidised bed reactor

During the AER-Gas 2 project, the University Stuttgart has expanded its atmospheric single fluidized bed reactor to a (Dual Fluidized Bed) DFB gasifier/regenerator system. It has been an important requirement for USTUTT to perform their investigations under techno- economic realistic conditions which lead to the recon-struction of the existing fluidized bed gasifier to a DFB system. The design of the facility is based on funda-mental research for post combustion CO2 –capture with CaO as sorbent bed material. Therefore the reactor design is well transfer-able to the AER- process. To assure the suitability of the facility, previous scaled cold model testing has been performed. The scaled coupled fluidized bed operation was stable and at steady state for more than one day. Long term steady state AER experiments over 10h were successfully carried out.

b) Pictures of fluidised bed reactor

FLuidised bed reactor FLuidised bed reactor FLuidised bed reactor

The following figure shows the principle of the test facility for investigating the chemical and mechanical stability of AER materials.

Fig.: Principle of Fluidised Bed AER Reactor.
The electrically heated fluidised bed reactor allows to adjust the operation temperatures of the bubbling bed up to 900°C. Fluidisation of the sample (absorbent material) is maintained by a flow of air, to which CO2 can be added to simulate the gasification process (absorption of CO2). To study the influence of water, an evaporator for steam production is integrated. Downstream the reactor, a particle filter is located to separate attrition losses.
Fig.: Lab scale fluidised bed AER reactor at PSI.
The test apparatus has a system control, which allows running automatic absorption-desorption-cycles under continuous fluidisation of the bed. All relevant system parameters (temperatures, flows, pressure) are recorded and the outlet gas composition is measured using mass spectroscopy with a time resolution of 10 seconds. The absorbed and desorbed amounts of CO2 are calculated from the flows and concentrations in the gas outlet. For the classification of the size distribution, standard sieve analysis is used.

Experimental Apparatus for Performing Catalytic Reactions with Liquid Feeds (e.g., Phenol/H2O → CO/H2)


Experimental Apparatus for Conducting Studies on: Catalyst Screening, In-Situ Catalyst Surface Characterization, Kinetics and Mechanisms of Heterogeneous Catalytic Reactions by Transient Methods

Fluidised bed reactor

Description of the gasifier

Gasifier The 100 kW FICFB-gasifier is a dual fluidised bed reactor, where the gasification zone is a bubbling and the combustion zone is a transporting fluidised bed. The bed material is circulating between these two zones and transports heat and CO2. Wood pellets are used as fuel, dolomite or calcite as bed material, steam for the fluidisation of the gasification zone and the siphons, air for the combustion zone and oil to supply additional heat in the combustion zone.

Temperatures, pressures and CO and CO2 content of the product gas are measured and recorded continuously. Gas samples are taken and analysed by gas chromatography to measure the concentrations of H2, CO, hydrocarbons, N2 and O2 in the product gas. CO, CO2, NO, NO2 and O2 from the flue gas are measured and recorded continuously. Dust, tar, H2S and NH3 content of the product gas is measured after the heat exchanger.

Particulates and tar are measured with a method similar to the tar protocol.

More info at http://www.ficfb.at/

Description of the Combined-Heat and Power (CHP) Plant

In Guessing innovative FICFB process for combined heat and power production based on steam gasification has been demonstrated. Biomass is gasified in a dual fluidised bed reactor. The producer gas is cooled, cleaned and used in a gas engine. A detailed flow sheet is shown below and characteristic data of the demonstration plant are summarized in the table.
Biomass chips are transported from a daily hopper to a metering bin and fed into the fluidised bed reactor via a screw system and a screw feeder. The fluidised bed gasifier consists of two zones, a gasification zone and a combustion zone. The gasification zone is fluidised with steam which is generated by waste heat of the process to produce a nitrogen free producer gas. The combustion zone is fluidised with air and delivers the heat for the gasification process via the circulating bed material.


Fig. : Flow sheet of CHP-plant Güssing.
Fuel Power 8000kW
Electrical Output 2000kW
Thermal output 4500kW
Electrical efficiency 25,0%
Thermal effiency 56,3%
Electrical/thermal output 0,44-
Total efficiency 81,3%

Table : Characteristic data of the plant.

The producer gas is cooled and cleaned by a two stage cleaning system. A water cooled heat exchanger reduces the temperature from 850°C – 900°C to about 140°C – 150°C. The first stage of the cleaning system is a fabric filter to separate the particles and some of the tar from the producer gas. These particles are returned to the combustion zone of the gasifier. In a second stage the gas is liberated from tar by a scrubber.
Spent scrubber liquid saturated with tar and condensate is vaporized and fed for thermal disposal into the combustion zone of the gasifier. The scrubber is used to reduce the temperature of the clean producer gas to about 40 °C which is necessary for the gas engine. The clean gas is finally fed into a gas engine to produce electricity and heat. If the gas engine is not in operation the whole amount of producer gas can be burnt in the boiler to produce heat. The flue gas of the gas engine is catalytically oxidised to reduce the CO emissions. The sensible heat of the engine’s flue gas is used to produce district heat; the one of the flue gas from the combustion zone is used for preheating air, superheating steam as well as to deliver heat to the district heating grid. A gas filter separates the particles before the flue gas is released via a stack to the environment.



1) Hardness test for mechanical strength

An alternative way to characterise the mechanical strength of the sorbent material is to evaluate the crushing strength of the particles. This method is fast and simple as one  particle is exposed to increasing pressure by a flat head until it breaks down, recording the necessary force. A major benefit is that raw material particles as well as differently treated particles (partially calcined, completely calcined, particles exposed to multicycle tests, coated particles) can be tested in a quick and consistent way.




The equipment is a digital gauge force of type Shimpo FGE/V-10X with a test stand. The capacity is 10lb, 5.000 kg or 50.00 N, with a resolution of 0.01 lb, 0.001 kg or 0.01 N respectively.


2) Particle coating


The Vector MFL.01 Bench Top Laboratory Fluid Bed unit installed at IFE is a process controlled, self-contained fluid bed (Fig.1) and is designed for use in developmental work being well suitable for the processing of small quantities in a lab scale.

A single spray gun is provided for use in either top spray or bottom spray configuration. Either spray technique can be used for coating and granulation or drying of a broad range of materials. The integrated peristaltic pump, mounted on the front panel of the unit, delivers solution to the spray gun assembly via tubing and allows for variable flow operation. The standard expansion chamber is constructed of borosilicate laboratory grade glass.



Product Container Capacity:    400mL - 1200mL

Process Air Volume:                40 - 165 Liters / minute

Wurster Coating:                     20g - 250g

Top Spray Granulation:            100g - 600g

Temperature Range:                 25 – 100°C





Micro Fluidized bed (FB) system (MFL 0.1 Vectorcorporation).





The coating method developed at IFE for limestone bed materials has shown interesting results. Mechanical properties of a specific limestone material were increased by 18% while the absorption properties of the materials were not significantly modified. However, results were shown to be strongly influenced by the nature of the coating solution and many process parameters such as residence time in the fluidized bed coating reactor and the calcination temperature. IFE intends to start a patent application on the coating method and publish the results in international journals as soon as the process is optimized.


a) Facilities for Testing the Mechanical Stability of CO2 Sorbent Materials
i) Mill

Simple mechanical stability tests with ball mill

In order to identify CO2 sorbent materials with promising mechanical stability, a simple and fast method was developed at ZSW using a commercially available ball mill (see photo). This test method is related to the Hardgrove test, a standard test method (DIN 51742) for the characterisation of the hardness of coals.

The production of fine particles is determined after operating the mill under standard conditions. Mechanically stable materials show a low extent of attrition.

ball mill

Ball mill at ZSW for Hardgrove related stability tests of CO2 sorbent materials

ii) Lab-scale fluidised bed reactor

The test facility enables the determination of the attrition behaviour of a CO2 sorbent bed material under fluidising conditions with simultaneous CO2 sorption reactions (calcination and carbonation). Thus, the bed material is not only mechanically stressed but also thermally and chemically by changing the CO2 partial pressure of the feed gas or/and by temperature loops.

The lab-scale fluidised bed reactor is a heat resistant steel tube and it is completely enclosed in an electric heated oven. During the test, the whole particle charge remains in the reactor. Fluidising gas (CO2, N2, air or mixtures thereof) is externally pre-heated. The fluidising gas exhaust is cleaned at the reactor top by three fine porous ceramic candle filters.

bed reactor

Lab-scale fluidised bed reactor for mechanical stability tests of CO2 sorbent bed materials at ZSW

Conversion of the sorbent until steady state (“total” conversion) is enabled by long calcination / re-carbonation periods. By measuring the feed gas flow (Mass Flow Controllers) and the product gas composition (BINOS), the CO2 up-take and release is calculated from C balance. The extent of attrition is determined on the base of a pre and post sieve analysis. With respect to the envisaged technical process realisation, the attrition is defined as the amount of fines with particle size < 200 µm generated during the whole test run.

b) Thermal Gravimetric Analysis (TGA)

The sorbent properties are analysed under ideal and defined conditions by TGA. Multi-cycle tests as well as kinetic measurements are performed.

Experiments Specifications
  • Simultaneous Thermal Analysis (STA)
  • special furnace for water vapour atmosphere (up to 100 °C)
  • high temperature tube furnace (up to 1500 °C)
  • resolution 5 µg
  • sample capacity 15 g
  • vacuum 10-2 mbar
  • software-controlled gas supply