By-Product Hydrogen June 8, 2011
The chemical industry produces significant quantities of by-product hydrogen. Production of chlorine, sodium-chlorate and ethylene/styrene are the largest sources. Chemical manufacturers can put this by-product hydrogen to a variety of uses, including transport. If hydrogen is not put to use it is vented or burned. Chemical manufacturers are failing to capture the full potential value of this gas if vented or burned. With electricity representing approximately 70% of the production cost of chlorine, taking a waste product and turning it into clean energy on site is a very attractive proposition. With a fuel cell system, the by-product hydrogen can be used to produce clean, zero-emission electricity that is either put into the grid, or used to fuel hydrogen vehicles. Cologne, a phase 0 city within the CHIC project, utilizes by-product hydrogen to fuel two 18 meter articulated buses. About 230 chemical companies of all sizes and sectors are based in the Cologne area. The ChemCologne region is one of the major centers of chemical industry in Europe.
The Electrolysis Process November 15, 2010
In the water electrolysis process the hydrogen is produced by electrochemically splitting water molecules (H2O) into their constituents hydrogen (H2) and oxygen (O2). The decomposition of water takes place in a socalled electrolysis cell and consists of two partial reactions that take place at two electrodes. The electrodes are placed in an ion-conducting electrolyte (usually an aqueous alkaline solution with 30 % potassium hydroxide KOH). Gaseous hydrogen is produced at the negative electrode (cathode) and oxygen at the positive electrode (anode). The necessary exchange of charge occurs through the flow of OH-ions in the electrolyte and current (electrons) in the electric circuit. In order to prevent a mixing of the product gases, the two reaction areas are separated by a gas-tight, ion-conducting diaphragm membrane. Energy for the water splitting is supplied in the form of electricity. To achieve the desired production capacity, numerous cells are connected in series forming a module. Larger systems can be realised by adding up several modules. Two types of electrolysers are common, atmospheric and pressurised units. An advantage of the atmospheric electrolyser, working at ambient pressure, is its lower energy consumption but the required space for the unit is relatively high. Pressurised electrolysers deliver hydrogen [...]
In the water electrolysis process the hydrogen is produced by electrochemically splitting water molecules (H2O) into their constituents hydrogen (H2) and oxygen (O2). The decomposition of water takes place in a socalled electrolysis cell and consists of two partial reactions that take place at two electrodes. The electrodes are placed in an ion-conducting electrolyte (usually an aqueous alkaline solution with 30 % potassium hydroxide KOH). Gaseous hydrogen is produced at the negative electrode (cathode) and oxygen at the positive electrode (anode). The necessary exchange of charge occurs through the flow of OH-ions in the electrolyte and current (electrons) in the electric circuit. In order to prevent a mixing of the product gases, the two reaction areas are separated by a gas-tight, ion-conducting diaphragm membrane. Energy for the water splitting is supplied in the form of electricity. To achieve the desired production capacity, numerous cells are connected in series forming a module. Larger systems can be realised by adding up several modules. Two types of electrolysers are common, atmospheric and pressurised units. An advantage of the atmospheric electrolyser, working at ambient pressure, is its lower energy consumption but the required space for the unit is relatively high. Pressurised electrolysers deliver hydrogen [...]
Steam Reforming November 15, 2010
Steam reforming using hydrocarbons (i.e. natural gas, liquid petroleum gas and naphtha) as feed is the most common process to produce hydrogen. Until recently, steam reforming plants were designed for production capacity ranging from 200 up to 100,000 Nm3/h. By using a newly developed type of reformer it is now possible to serve ranges of 50 up to 200 Nm3/h economically by compact, small-scale hydrogen generation plants based on steam reforming of natural gas. This capacity range is well suited for supplying small vehicle fleets with hydrogen. The ability for multiple start-up and shut-down operation is important to allow a maximum of flexibility. Steam Reformer Process The process is divided into the generation of a hydrogen rich reformate stream by means of steam-methanereforming (SMR) and the following hydrogen purification by means of pressure swing adsorption (PSA). The process route consists mainly of Pre-Treatment of the Feed The hydrocarbon feedstock is desulphurised using e.g. activated carbon filters, pressurised and, depending on the reformer design, either preheated and mixed with process steam or directly injected with the water into the reformer without the need of an external heat exchanger. The fresh water is first softened and demineralised by an ion-exchange water [...]
Steam reforming using hydrocarbons (i.e. natural gas, liquid petroleum gas and naphtha) as feed is the most common process to produce hydrogen. Until recently, steam reforming plants were designed for production capacity ranging from 200 up to 100,000 Nm3/h. By using a newly developed type of reformer it is now possible to serve ranges of 50 up to 200 Nm3/h economically by compact, small-scale hydrogen generation plants based on steam reforming of natural gas. This capacity range is well suited for supplying small vehicle fleets with hydrogen. The ability for multiple start-up and shut-down operation is important to allow a maximum of flexibility. Steam Reformer Process The process is divided into the generation of a hydrogen rich reformate stream by means of steam-methanereforming (SMR) and the following hydrogen purification by means of pressure swing adsorption (PSA). The process route consists mainly of Pre-Treatment of the Feed The hydrocarbon feedstock is desulphurised using e.g. activated carbon filters, pressurised and, depending on the reformer design, either preheated and mixed with process steam or directly injected with the water into the reformer without the need of an external heat exchanger. The fresh water is first softened and demineralised by an ion-exchange water [...]