The Sulaway® unit
The Sulaway® unit is the heart of the Gazpack installation and is patented under patent number 20132230.
The saturated, raw (bio) gas comes directly into the Gas Purifier, via a pressurized process using our patented Sulabeads the raw biogas is converted into three different outgoing flows.
1: Clean gas
The system is selective in the removal of sulfur (H2S) and reduces the percentage to a level of less than 50 ppmV, thus producing a green gas stream which is ready to be used, for example to generate heat in green houses or in an industrial process of a factory. Moreover, the green gas is processed in such a way that it is suitable to add to the natural gas network.
2: H2S gas
The Gas Purifier also produces a gas stream which is highly saturated with sulfur (H2S). This gas stream is harnessed and burned off in the quencher. Extinguishing the resulting flame arc creates a sulfuric acid that is useful for a variety of applications including purifying ammonium saturated air. The quenching heat can be used for the heating of offices ,but also for digesting processes.
3: Sulphuric Acid
The third stream which comes out of the Gas Purifier is water. This water is used to extinguish the fire arc within the quencher and make sulphuric acid.
The essence of the Gazpack system is that it is a closed loop system where no waste products which would normally require costly removal and destroying processes are produced.
The Sulaway® unit is built according to the highest quality and safety standards in the industry. The main features of the package are explained below.
All pressure regulated instruments are pneumatically controlled. In case of alarm or shutdown the installation will be automatically stopped and all instruments will be directed to their safe positions.
The unit is completely enclosed by a gas tight enclosure. In case of emergency or gas leak the installation is stopped and a process is started to burn off excess gas in the system through an a incinerator, which is part of the quencher. There is always a backup supply of nitrogen to have a safe shutdown.
Several high power components are used inside the Sulaway® system. Yet the complete energy balance is well thought out. For example; heat generated by the compressor is used for regeneration of the Sulabeads. Also the water collected from the saturated gas is used in the quenching process, a small amount of additional water might be required.
Standby safety purge system
The nitrogen purge system of the Sulaway® unit is comprised of a nitrogen generator package. This package supplies the required nitrogen for the actuated instruments and always keeps a backup for safe shutdown of the unit.
For small capacities one might consider to buy the nitrogen locally.
The supply of the gas is not constant in flow capacity and composition. The gas package is start/stopped on increasing pressure versus inlet flow gas in one or two steps 0-50-100 by mounting two separate trains. The stock volume ( = gas receiver between digester and Sulaway® package) of the system must be adequate to avoid two frequent start stops for protecting e-motors and the e-distribution net. For larger packages ( > 3000 Nm3/h) fully redundant systems are advised.
The composition of the gas varies, which means that the system must be designed for the maximum load of the different influent gases consequentially peak load of H2S as well CO2 must be considered. For H2S peak load is taken care for by adding additional Sulabead® in the reverser and for CO2 by adding extra membranes.
PROCESS ENERGY SAVING
The reverser is designed for peak load, which means very often too large for the H2S load, which is compensated by reducing the heating period (energy saving).The membrane stacks are designed for peak load of CO2 and the second stage is bypassed at lower CO2 concentrations ( flow saving consequentially energy saving).