Design and Performance Investigation of a Compact Catalytic Reactor Integrated with Heat Recuperator

The catalytic combustion has the advantage of lower auto-ignition temperature and helps to expand the combustible limit of lean premixed gas. However, the intake needs to be preheated to certain temperature commonly through an independent heat exchanger. Similar to the principles of non-catalytic RTO combustion, this paper presents a similar approach whereby the combustion chamber is replaced by a catalytic combustion bed. A new catalytic reactor integrated with a heat recuperator is designed to enhance the heat recirculation effect. Using a two-dimensional computational fluid dynamics model, the performance of the reactor is studied. The reaction performances of the traditional and compact reactors are compared and analyzed. Under the same conditions, the compact reactor has better reaction performance and heat recirculation effect, which can effectively decrease the ignition temperature of feed gas. The influences of the inlet velocity, the inlet temperature, the methane concentration, and the thermal conductivity of porous media on the reaction performance of integrated catalytic reactor are studied. The results show that the inlet velocity, inlet temperature, methane concentration, and thermal conductivity of porous media materials have important effects on the reactor performance and heat recirculation effect, and the thermal conductivity of porous media materials has the most obvious influence. Moreover, the reaction performance of multiunit integrated catalytic reactor is studied. The results show that the regenerative effect of multiunit integrated catalytic reactor is further enhanced. This paper is of great significance to the recycling of low calorific value gas energy and relieving energy stress in the future.

Insights into the role of strontium in toluene catalytic combustion over La1-xSrxCoO3 perovskites catalysts

A series of LaCoO3 pervoskite catalysts substituted by Sr in A site (La1-xSrxCoO3) were prepared via a facile sol-gel method. The catalytic activity of these pervoskite catalysts for the deep...

A hydrogen generator coupled to a hydrogen heater for small scale portable applications

This study aims to build and test a small scale portable device able to couple a hydrogen generation system (based on a NaBH4 solution as liquid H2 carrier) to a hydrogen heater (based on the exothermic catalytic combustion of the released H2). The hydrogen generating system is based on the hydrolysis of stabilized solutions of NaBH4 (fuel solutions) which are pumped into the hydrolysis reactor. The generated H2 feeds the catalytic combustor. Two catalysts have been developed for the H2 generation and the combustion reactions able to operate at room temperature without need of additional energy supply. For the NaBH4 hydrolysis a Co-B catalyst was supported on a perforated and surface treated stainless steel (SS316) home-made monolith. For the flameless H2 catalytic combustion a Pt catalyst was prepared on a commercial SiC foam. The device was automatized and tested for the on-demand production of heat at temperatures up to 100ºC. In steady state conditions the NaBH4 solution flow is controlling the H2 flux and therefore the heater temperature. Once the steady-state is reached the system responds in a few minutes to up and down temperature demands from 80 to 100 ºC. The catalysts have shown no deactivation during the tests carried out in several days.

Kinetics of low-temperature catalytic combustion of ethylene at wet conditions for postharvest storage applications

The study addresses the reduction of ethylene levels in postharvest storage applications using a Pd-Zn-Sn/TiO2 catalyst, which is capable of reacting trace concentrations of ethylene at temperatures as low as 278 K and at relative humidity as high as 90%. The rate law is derived from data collected using a constant volume batch reactor and a model for a storage room with associated packed bed reactor is developed. The amount of catalyst required to maintain an ethylene concentration of 0.1 ppmv in a room containing 20 tons of fruit having an ethylene metabolism of 0.1 ul/kg hr was calculated as a function of air temperature and water content. While the catalyst is capable of continuously removing ethylene from saturated, refrigerated air, the amount of catalyst required can be reduced significantly by incorporating conventional air conditioning solutions upstream of the catalyst bed. Such combined systems and their functions are discussed