Urea solution online preparation device for SCR (Selective Catalytic Reduction) systems of marine diesel engines

Abstract

The invention belongs to the technical field of application of SCR (Selective Catalytic Reduction) systems of marine diesel engines, and specifically relates to a urea solution online preparation device for SCR systems of marine diesel engines. Urea dry powder and deionized water are added into a urea preparation chamber; by means of an electric stirrer, the deionized water and the urea dry powder are intensively mixed; and by using a urea concentration sensor, the density of the urea solution is monitored in real time, so that the stirred urea solution can satisfy the demands of the SCR systems. By using a stirring chamber conveying pump, the prepared urea solution is pumped in to a storage chamber; and by using a liquid level sensor and a temperature sensor, the urea solution in the storage chamber is monitored. According to the urea solution online preparation device, the full-automatic online preparation of the urea solution is realized through the accurate measurement on the urea dry powder and the deionized water, so that the urea cabin volume is effectively decreased, the body space is saved and the benefit is brought to the storage of the urea.

Description

technical field [0001] The invention belongs to the technical field of marine diesel engine SCR system applications, and in particular relates to a urea preparation device for a marine diesel engine SCR system. Background technique [0002] Selective catalytic reduction (selective catalytic reduction, SCR) is the mainstream technology to reduce the nitrogen oxide content in marine diesel engine exhaust. The operation of the SCR system needs to consume urea solution as a reducing agent. In order to ensure the normal operation of the marine SCR system, a separate urea solution tank is usually set up to store the urea solution. However, due to the large exhaust flow rate of the marine diesel engine and the large consumption of urea solution, considering the operating characteristics of the ship, it is impossible to replenish the urea solution at any time. The separate urea solution tank will occupy a considerable space on the hull and reduce the payload of the ship. At the sam...

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Problems solved by technology

However, due to the large exhaust flow rate of the marine diesel engine and the large consumption of urea solution, considering the operating characteristics of the ship, it is impossible to replenish the urea solution at any time. The separate urea solution tank will occupy a considerable space on the hull and reduce the effective load of the ship.

At the same time, urea solution has certain instability, and factors such as ambient temperature and storage container materials will affect its physical and chemical properties.

Setting up a separate urea solution tank on a ship to store urea solution will increase the cost of ship construction and operation. If the main propulsion of a ship is a low-speed diesel engine with a rated power of 13200kW and a rated speed of 111r / min, and sailing in a cold environment, the The amount of urea solution required for the operation of the ship's SCR system is about 340L / h. If a separate urea solution tank is used to store the urea solution, in order to ensure the normal operation of the SCR system for a long period of time, the volume of the urea solution tank should be at least 40m 3 , at the same time, in order to ensure the stability of the ambient temperature, it is necessary to install a high-power heater in the urea tank, such as figure 1 As shown, the urea solution cabin is composed of a urea tank body A, a urea solution filling port B, a solution sewage outlet C, a urea solution outlet D, a urea solution return port E, a temperature sensor F and an electric heater G; The volume of the solution tank is large, resulting in tight space, which affects the overall spatial layout of the cabin, and due to the impact of volume and materials, the production cost of the urea tank is relatively high

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