Exhaust gas processing device, diesel engine, and exhaust gas processing method

摘要

An exhaust gas purifying device includes a first branch pipe and a second branch pipe that cause exhaust gas exhausted from a diesel engine to branch into a plurality of passages and pass through the passages, a first exhaust gas purification unit and a second exhaust gas purification unit that purify the exhaust gas, an exhaust gas temperature sensor that detects a temperature of the exhaust gas, an atmospheric pressure sensor, and a processing unit that obtains a convergence portion pressure at a convergence portion from a relationship obtained in advance between the convergence portion pressure, a total flow rate of the exhaust gas, a convergence portion temperature, and an atmospheric pressure.

主权项

1. An exhaust gas processing device comprising:
an exhaust gas introduction passage that exhausts exhaust gas exhausted from a diesel engine; a plurality of first exhaust gas passages which are branched from the exhaust gas introduction passage and which exhaust the exhaust gas; an exhaust gas purification unit which is provided to each of the first exhaust gas passages and which purifies the exhaust gas; a second exhaust gas passage which is provided to a portion where the plurality of first exhaust gas passages converge and which exhausts the exhaust gas exhausted from the plurality of first exhaust gas passages; an exhaust gas temperature sensor that detects a temperature of the exhaust gas at a convergence portion where the plurality of first exhaust gas passages converge; an atmospheric pressure sensor that detects an atmospheric pressure; and a processing unit that obtains a convergence portion pressure which is a pressure at the convergence portion based on a total flow rate of the exhaust gas exhausted from the diesel engine, which is obtained while the diesel engine is operating, the temperature of the exhaust gas detected by the exhaust gas temperature sensor, and the atmospheric pressure detected by the atmospheric pressure sensor, wherein each of the exhaust gas purification units includes a reducing catalyst which is provided to each of the first exhaust gas passages and which reduces NOx in the exhaust gas by a reducing agent, each of the first exhaust gas passages includes a particular filter provided on an upstream side of each of the reducing catalysts in an exhaust gas flowing direction, and a pressure sensor which is arranged between each pair of the particular filter and the reducing catalysts and which detects a pressure in each of the first exhaust gas passages, and the processing unit obtains a flow rate of exhaust gas flowing through each of the first exhaust gas passages based on at least the convergence portion pressure and the pressure in each of the first exhaust gas passages, which is detected by the pressure sensor, whereby the processing unit supplies an appropriate amount of reducing agent to each NOx reducing catalyst to convert NOx in the exhaust gas based on the obtained flow rates through each of the first exhaust gas passages.