Experimental study on the ignition time of electric heaters with thermal insulation structure

Highlights: • A thermal insulation structure consisted of three layers was used to reduce the heat loss of electric heaters. • The performance of electric heater with thermal insulation structure was investigated through combustion tube experiments. • The experiment results showed ignition time can be shorted obviously by using thermal insulation structure. • The heat loss was reduced and ignition energy was saved during ignition process. • The better air injection rate was 3 L/min in the experimental condition. Ignition is one of the most important techniques used to ignite crude oil during the in-situ combustion process. However, one problem with this process is that the ignition time is long. To address this problem, this study provides a solution by using a thermal insulation structure consisting of three layers placed inside an electric heater. To investigate the performance of the thermal insulation structure, combustion tube experiments were conducted over a range of air injection rates of 1 L/min to 5 L/min at ambient pressure. The experimental results demonstrated that the average diminution of heat loss is about 52.68% and the time required to ignite the oil reservoir was shortened by approximately 20 min. Therefore, the ignition energy was saved by using the thermal insulation structure. Furthermore, the ignition effect was also strongly influenced by the air injection rate. The maximum temperature increase and front combustion propagation speed increased with the increase of the air injection rate. In this study, the better air injection rate was 3 L/min. Under this condition, not only can the best ignition effect be guaranteed but also stable propagation of the combustion front can be ensured.