Language
News Details
What are the methods for controlling the temperature of a small fixed bed reactor?
Release time:
Aug 02,2022
A device for the reaction of fluid through a bed formed by a static solid material is called a fixed bed reactor, especially a gas-solid catalytic reactor for the reaction of gas-reactive materials through a bed formed by a solid catalyst, such as catalytic reforming and natural gas conversion in the refining industry.Compared with a backmix reactor (such as a fluidized bed), the fluid flow in a fixed bed reactor is close to horizontal flow, so a small amount of catalyst and a smaller reactor volume can be used to obtain a larger production capacity; in addition, the catalyst is not easy to wear and can be used for a long time (unless inactivated).However, the quality indicators involved during the operation of the reactor, such as selectivity, have a highly nonlinear dependence on the bed temperature distribution.Therefore, the problem of temperature control has become the focus and difficulty of fixed bed reactors.
Most small fixed-bed reactors are cylindrical in shape, and the temperature has a certain distribution along the axial and radial directions.In order not to damage the catalyst due to excessive temperature, the high temperature of the reaction bed is first controlled.There are three main methods：
(1) The temperature and concentration of the reaction outlet are controlled by introducing part of the feed into the middle of the cylindrical reactor.
(2) The peak temperature of the reaction bed is controlled by adjusting the reflux of the reactor.The simulation results show that under strong interference, the temperature peak can be controlled within the required range.
(3) Adopt the compensation method.Temperature is a variable with great hysteresis. If the temperature of the fixed bed reactor is not controlled in time, it may cause over-temperature or flameout due to instability.Compensation can be used for processes with large pure hysteresis, but this method requires knowing the characteristics of the comparison object, which is usually difficult to do.
For the catalytic reaction process of multivariate fixed bed, classical analysis methods can also be used to design the control system, such as frequency domain analysis method, root trajectory analysis method, etc., which can obtain good adjustment quality.
Another name for a fixed bed reactor is a filled bed reactor.Solids are usually granular and accumulate in a bed of a certain height (or thickness).The bed formed by the accumulation of solids is stationary, and the fluid flows through the bed to achieve full contact between the fluid and the solid, resulting in a chemical reaction.During operation, wastewater is introduced from the bottom of the reactor, and air and wastewater are introduced into the reactor together.Such reactors are usually used to treat wastewater to remove carbon-containing biochemical oxygen demand, and can also be used for wastewater nitrification.
This reactor is used for synthesis, wastewater treatment and catalytic combustion.There are many mathematical models, which can be roughly divided into homogeneous models and heterogeneous models.According to whether backmix is considered, each type can be divided into non-backmix model and backmix model, and according to whether the radial concentration gradient and temperature gradient of the reactor are considered, it can be divided into one-dimensional model and two-dimensional model.
Related News
E-mail: lzc838@139.com
Tel: +86-535-6981618 +86-13583533296 (Mr. Li)
Address: No. 98 Chaoyang Road, Menlou Industrial Park, Fushan District, Yantai City, Shandong Province, China
© Shandong Zhongsheng Pharmaceutical and Chemical Equipment Co., Ltd. SEO Business License