System and method for preparing ammonia by heterogeneous catalytic hydrolysis of SCR denitration urea

Abstract

The invention discloses a system and method for preparing ammonia by SCR denitration urea heterogeneous catalytic hydrolysis, the system comprises a urea solution storage tank (1), an A urea solution delivery pump (2), a heterogeneous hydrolysis reactor (3) and a steam pipeline (4), and the heterogeneous hydrolysis reactor (3) adopts a tubular fixed bed reactor; wherein the urea solution storage tank (1) is connected with the heterogeneous hydrolysis reactor (3) through the A urea solution delivery pump (2) and a pipeline, and the steam pipeline (4) is connected with the heterogeneous hydrolysis reactor (3). The hydrolysis ammonia production system is simple in structure, a fixed bed tubular reactor is adopted, a urea solution is hydrolyzed under the action of a solid catalyst to generate ammonia gas and carbon dioxide, and the reaction is a liquid-solid two-phase reaction. At present, when most devices corresponding to urea homogeneous catalytic hydrolysis process reactions are modified, the system responsiveness can be improved, the system operation cost is reduced, and the waste liquid discharge amount is reduced.

Description

technical field [0001] The invention relates to the technical field of flue gas denitrification, in particular to a system and method for producing ammonia through heterogeneous catalytic hydrolysis of SCR denitrification urea, and belongs to the technical field of air pollution control. Background technique [0002] Selective catalytic reduction (SCR) denitrification technology has been widely used at home and abroad because of its high efficiency. The reducing agents commonly used in SCR denitrification technology include liquid ammonia, ammonia water and urea. Liquid ammonia and ammonia water are dangerous chemicals, which have great safety hazards in transportation and unloading. If leakage occurs, it will have an impact on the safe production of the power plant, surrounding residents and the ecological environment. And urea is a kind of non-toxic and harmless chemical product, it has good performance index and operation control safety, its chemical properties are stabl...

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Problems solved by technology

However, the urea catalytic hydrolysis technology generally uses liquid acid or alkali as the catalyst at present. The homogeneous catalyst has problems such as not easy to recycle, requiring regular investment, high operating costs, and corrosive to equipment.

[0004] The patent application with the application number 201510236369.7 discloses a three-phase fluidized urea catalytic hydrolysis ammonia production equipment and method, in which a three-phase fluidization reaction occurs in the hydrolysis ammonia production equipment, and the three phases participating in the reaction are composed of solid phase catalyst, It consists of liquid phase urea solution and gas phase steam. Although this method can solve the problem of catalyst recovery, it still has the following disadvantages: 1. The three-phase fluidization reaction is adopted. In addition to indirect heating of the feed liquid in the reactor, the steam will The steam is also used as the fluidization medium of the reactor, directly enters the reactor from the bottom, and the urea solution is sprayed from the top, which will cause mist entrainment, make the mass transfer and heat transfer in the reactor worse, and the chemical reaction takes a long time, making the system The response time to the ammonia demand signal is long; and the steam consumption is increased, the urea hydrolysis conversion rate is reduced and the system operating cost is increased; 2. Activated carbon is used as the catalyst carrier, and the activated carbon itself does not have catalytic performance, making its catalytic activity More generally, the reaction rate of catalytic hydrolysis is slow, which causes the system to respond to the ammonia demand signal for a long time, and there is no interaction between activated carbon and active components, making the active components easy to lose; 3. Three-phase fluidized hydrolysis reaction The structure of the device is complex, and the three-phase fluidization reaction aggravates the disturbance in the reactor, which is easy to cause the reactor to vibrate, and has high requirements for the base, resulting in high manufacturing and installation costs

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