(1) Coal gasifier
The coal gasifier can be divided into four modes by the movement pattern of the coal in the gasifier: fixed bed (moving bed), fluidized bed, entrained bed and molten bed. While it can be summarized to atmospheric and high pressure styles according to the gasification operating pressure. Based on the feeding method, the coal gasifier contains solid and liquid feeding manners. In the light of the residue-discharge mode, it can be classified into solid and liquid patterns. In industry, the typical coal gasifiers include UGI gas furnace, Lurgi gas furnace, Winkler gas furnace, Texaco gas furnace and Dow Chemical gas furnace. Depending on various technology needs, the coal gasifiers provide air gas, mixed gas, water gas and semi-water gas.
In the coal gasifier device, the volume fractions of CO, CO2, CH4 and H2 are important parameters of process control, and the ability to accurately measure these variables is considered to be one of the most important indicators of the energy efficiency of the entire unit. First, the gas composition analysis can be used to determine the reaction state in the furnace, for example, the content of O2 is a critical control parameter in the production of semi-water gas. Additionally, it is necessary that the concentrations of CO and H2 are confirmed to be under the explosive limit before ignition, preventing any explosion. As we know, it is necessary to carry out N2 exchange until the feeding operation, but stilly, the O2 content in the furnace must be determined because the feeding coal slurry enters firstly, and it may reacts with O2 causing an explosion.
Figure 1. Schematic of the coal gasifier
(1. Coal grinding and drying, 2. Coal pressurizing, 3. Gasification furnace, 4. Syngas cooling tower, 5. Dry dust removing, 6. Wet scrubbing, 7. Desulfurization and de-carbonization, 8. Slag removal system, 9. Preliminary water treatment)
Figure 2. Schematic of Winkler coal gasifier
(1. Hopper, 2. Gasifier, 3. Heat transfer device, 4 – 5. Cyclone dust extractor, 6. Washing tower, 7. Cleaning device, 8. Tar-water separator, 9. Pump)
(2) Biomass gasifier
The main materials of the biomass gasifier are agricultural and wood wastes, which have the feature of wide sources and low price. Fuel gases produced by biomass gasifiers are mainly used for power generation (IGCC) or sent to city residents for cooking and heating through the pipe network.(2) Biomass gasifier
Similar with the coal gasifier, the accurate measurements of the gas composition (CO, CO2, H2 and CH4) of the biomass gasifier can help to improve the gasification quality and the gas production efficiency. In addition, the total heating value of the mixed fuel gas is also an important parameter in energy calculation for pricing. According to various concentrations of fuel gases’ components, the total heating value Q is computed by the following equation, and the total energy value can be easily obtained with an additional volume flow meter.
Q = 126[CO] + 108[H2] + 359[CH4] + 665[CnHm] MJ/m3
Figure 3. Diagram of fuel gases produced by biomass gasifiers used for power generation (IGCC)
(1. Pretreatment, 2. Fluidized bed gasifier, 3. Tar cracking furnace, 4. Gas purification, 5. Gas compression, 6. Gas turbines generating units)
Figure 4. Schematic diagram of fuel gases produced by biomass gasifiers sent to city residents.
(1. Feeder, 2. Biomass gasifier, 3. Condensing tower, 4. Absorption tower, 5. Separation tower, 6. Defogging tower, 7. Water sealed device, 8. Wet gas holder, 9. Flame arrestor)
Hubei Cubic-Ruiyi Instrument Co.,Ltd
Add: Fenghuang No.3 Road, Fenghuang Industrial Park
Eastlake Hi-tech Development Zone Wuhan 430205, China
Tel: 0086-27-81628831 /Fax: 0086-27-87401159