Abstract
The use of natural gas can reduce the amount of coke needed to produce cast iron. In a common tuyere natural gas is pressed against the surface of the air passage by a stream of hot blow and mixes poorly with it. It leads to incomplete burning of natural gas and its pyrolysis. One way to improve the mixing of natural gas and hot blow is to install the swirler in the air passage. In this case, however, intensification of natural gas burning inside the tuyere can lead to a burnout of the inner cylinder. In Ansys Fluent 18.2, using insulation insert with a swirler made in the form of a collar step at different places along the length of the insert, simulation of gas dynamics and its thermal state is carried out to solve the problem of mixing natural gas and hot blow in the air passage of tuyere. Simpler assumptions were adopted. Among which the simulation area included not only the fluid medium inside the air passage, but also the insulation insert, i.e. the associated problem of heat exchange was solved, and the processes of transfer of heat to water of the cooling system are taken into account in extended boundary conditions. The simplified calculation area scheme was created in the DesignModeler application, and the calculated grid was created in the AnsysMeshing application. The boundary conditions were set for blow (natural gas), as well as for the border of the insert with an air gap separating it from the internal cylinder and the fluid with the tuyere nose. Taking into account the symmetry of the computation region, the calculations were made for the half of tuyere. It has been found that mixing of natural gas and hot blow improves as the swirler moves along the length of the insert to the exit from the air passage. At the same time, in the swirler place the diameter of air passage is not less than downstream of the tuyere. The swirler`s shift toward the exit from air passage reduces the thermal load on the insert, thereby increasing its service life.
Highlights
One way to improve the mixing of natural gas and hot blow is to install the swirler in the air passage
In Ansys Fluent 18.2, using insulation insert with a swirler made in the form of a collar step at different places along the length of the insert, simulation of gas dynamics and its thermal state is carried out to solve the problem of mixing natural gas and hot blow in the air passage of tuyere
Among which the simulation area included the fluid medium inside the air passage, and the insulation insert, i.e. the associated problem of heat exchange was solved, and the processes of transfer of heat to water of the cooling system are taken into account in extended boundary conditions
Summary
Левицкий И.А., к.т.н., доцент кафедры энергоэффективных и ресурсосберегающих промышленных технологий. Одним из способов улучшения перемешивания природного газа и горячего дутья является установка завихрителя в дутьевом канале. Для решения проблемы перемешивания природного газа и горячего дутья в дутьевом канале воздушной фурмы проведено моделирование газодинамики и ее теплового состояния в среде AnsysFluent 18.2 при использовании теплоизолирующей вставки с завихрителем, выполненном в виде кольцевого выступа в разных местах по длине вставки. Установлено, что перемешивание природного газа и горячего дутья улучшается по мере смещения завихрителя по длине вставки к выходу из дутьевого канала. В обычной фурме природный газ прижимается к поверхности дутьевого канала потоком горячего дутья и плохо смешивается с ним, что приводит к неполному сжиганию природного газа и его пиролизу. Одним из вариантов улучшения перемешивания природного газа и горячего дутья является установка завихрителя в дутьевом канале или локальное измене-. В связи с этим необходимо одновременно проводить мероприятия по улучшению горения природного газа и теплозащите внутреннего стакана фурмы различными способами: футеровкой, вставками, нанесением покрытий и др. [24]
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