Brief introduction to the Flameless Gasification technology and thermolysis process

Flameless Gasification Complex
Main blocks of the thermolysis equipment

Project Image

Complex configuration
The complex for Flameless Gasification of organic materials such as coals, peat and oil shale is composed of the following blocks:

Description of the process
(thermolysis)

The manufacturing process of the processing of organic raw materials in the form of coal, peat and oil shale (the raw materials) by thermolysis technology looks according to scheme as follows.

The incoming for processing, prepared and sorted municipal solid waste (excluding food waste, biomass and the inert materials) are stored. From the store, by certain parts, the feedstock is fed into the hopper receiver, then proceeds further to the screws, where it undergoes drying – the process, in which the raw material is heated to the appropriate temperature by the heat coming from the reactors, getting rid eventually of unwanted moisture, still existed in the incoming raw materials.

Through the screw washes, the dried raw material is delivered into the multistage Thermolysis reactor for flameless gasification at a temperature of 400 - 950°C. Each Thermolysis reactor consists of two low-temperature carbonization chambers. As a result of low-temperature carbonization reaction, the synthesis gas is derived and then driven further into the gas enrichment section, where gas cleaning treatment (from impurities and minor-products) is taking place. Carbonization at a low temperature and fumigation of the input material takes place in both low-temperature carbonization chambers at different temperatures. Heating, required for the coking process, is carried out with the help of heaters in outer Thermolysis casing chambers.

Monitoring and control of the reactors’ functioning and the guarantee of their safe operation are realized through a number of measuring probes and safety system, organized into a single dispatcher system. The gas-transmission system is protected from overpressures by a due number of measurement and control membranes. In case of internal pressure increase or other emergency situation, the formed gas is drawn off to the torch. In addition, there is a water and steam system for urgent interruption of the low-temperature carbonization reaction.

There is a cascade of two sequential screw aggregates connected to the reactor. The further thermal decomposition of waste is taking place there, along with the primary coke material and liberation of synthesis gas. As well as the Thermolysis reactor, the coking units are equipped with heating casing used for direct heating. The received solid residue (coke and ash) after appropriate cooling (by steam and water) is transferred to the sealed containers. After cooling, the ash and mineral particles are separated and utilized. In the gas enrichment section the synthesis gas comes through the system of scrubbers, separators, reservoirs and pumps. Each reactor is connected to the scrubber – the absorption gas treatment unit. The gas streams from both lines are joined and routed through the absorption purification cascades, where during circulation the condensate is absorbed from coking gas and the gas is cooled down.

At thermolysis technology the organic substances are parted into short-chain hydrocarbons; the ferric oxides, as well as oxides of other inorganic substances are reduced (e.g. oxides of sulfur compounds).

During the synthesis gas treatment, a complete condensation of aliphatic and aromatic substances is achieved. The content of detrimental impurities (e.g. HCL) is reduced by limewater neutralization, in compliance with prescribed requirements.

Process

With the help of oil separators the oily actuation medium and water are separated. The wastewater additionally purified by active carbon and by biological treatment of the Thermolysis installation. After that the wastewaters can be directed into the sewage system of the industrial zone.

The exhaust air from Thermolysis process is purified in biological purification system. To eliminate the smell emissions, associated with exhaust gases from wastewater purification and multi-stage waste drying process, they are drawn away from the working areas through the piping system with integrated biological gaskets.

After all cleaning treatments the process gas flow gets into the gas storage. This gas storage is used to receive and buffer the synthesis gas obtained during Thermolysis process, to ensure the power supply, to feed the reactor torches and coking units, as well as to deliver gas to the consumer through the compressor station. Through back-mixing of worked-out gas its quality in reactor lines is balanced.

The resulting synthesis gas is, at the request of the customer and with the help of additional equipment (option), can be used for generation of energy or for production of various chemical products.

Protection system consists of a torch, which serves, in case of emergency, as a reliable withdrawal of synthesis gas from coking installation and gas storage. The connecting pipes are equipped with armature, which, in case of power disconnection, autonomously opens. To prevent accidental pressure lifting, the reactors and torch joints are equipped with safety membranes.

To feed the installations the wastewater is re-transferred from the water treatment systems and used. Through the air tap the exhaust air is discharged into the atmosphere. The organic residues are cyclically withdrawn and charged into Thermolysis process. The water circulation system for process gas purification contains the cooling installations, connected to the heat carrier that runs using the ambient air.

Schemes of the process of Flameless Gasification

Having passed the stage of sorting and grinding to the required parameters, the input material comes from the industrial site to the thermolysis installation for production of syngas.
Prepared raw materials from the on-site storage are formed into the loading parts and conveyed into the thermolysis installation.
In the attached to thermolysis reactor separation unit, the received syngas is refined from fine mineral particles and dust.
Monitoring and control of the reactors’ functioning and guarantee of their safe operation are realized through a number of measuring probes and safety system, organized into a single dispatcher system.
To continue, go to the next tab    
In the gas enrichment section, the syngas comes through the system of scrubbers, separators, reservoirs and pumps. Each reactor is connected to the scrubber - absorption gas treatment unit.
The initial reduction of harmful impurities (e.g. HCL) is taking place in the second stage of gas treatment, by neutralizing with the limewater according to the prescribed requirements.
The third stage of cleaning of syngas from harmful impurities.
The complete condensation of aliphatic and aromatic substances is achieved in the fourth stage of gas cleaning. In a bound state with actuation medium the harmful substances and light particles are withdrawn during the final circulation cycle.   To continue, go to the next tab    
With the help of oil separators, the oily actuation medium and water are separated.
The wastewater additionally purified by active carbon and by biological treatment of the Thermolysis installation. After that the wastewaters can be directed into the sewage system of the industrial zone.
To eliminate the smell emissions, associated with exhaust gases from wastewater purification and multi-stage waste drying process, they are drawn away from the working areas through the piping system with integrated biological gaskets.

Some comparisons

Table 1

Comparing the characteristics
of technologies for processing oil shale

  Technology
FUSHUN Кивитер Галотер
(Enefit140, Petroter)
PETROSIX THERMOTEC
Country China Estonia Estonia Brazil Poland
Company different EESTI ENERGIA, VКG EESTI ENERGIA, VКG   POLAND ENERGY
Retort type vertical vertical horisontal vertical inclined
Volume of oil shale processing, tons / day 100 1 000 3 000 6 200 и 1 600 block one 520
Fraction size, mm 10 - 75 25 - 125 0 - 25 6 - 50 0 - 125
Resin yield, by Fischer-Tropsch, % 65 75 - 80 73 - 78 85 - 90 --
Carbon content in ash, % n.d. 8,0 1,5 n.d. 0,01
Moisture content in ash, % n.d. 30,0 15,0 n.d. 1,0 - 3,0

Table 2

Comparison of indicators of introductions
of various technologies for processing of oil shale

  FUSHUN Галотер
(Enefit140, Petroter)
THERMOTEC
Type of equipment FUSHUN UТТ 3000 THERMO 190
Company SINOPEC EESTI ENERGIA, VКG POLAND ENERGY
Oil shale processing volume, tons / day 3 000 * 3 000 * 3 000 *
Size of fraction of oil shale for processing, mm 10 - 75 0 - 25 0 - 125
Commodity output:
- Electric power, MW per year
or
- Shale oil, ton / year
- Methanol or ammonia, tons
or
- Benzine, ton / year

n.d.

45 000 *
No

No

930 000 *

135 000 *
No

No

1 580 000 *

No
330 000 *

145 000 *


Source: reviews of specialized literature
* at an efficiency of the power plant of 0.40 and oil shale processing in Estonia