## 1 Introduction
The SCR method is widely used in power plant boilers. It sprays the ammonia diluted to a specific concentration into the flue gas. Under the action of catalysts, NO\({}_{\text{x}}\) is reduced to nitrogen and water. The designed reducing agent used in most power plants is liquid ammonia. However, domestic relevant departments have stipulated that if the storage capacity of ammonia exceeds 10 tons, it would be defined as a hazard installation. Additionally, most CFPUs apply liquid ammonia as a reducing agent in SCR reactor, and the storage capacity of liquid ammonia is generally designed to meet the requirements of 5 to 7 days of 100% load, which is more than 10 tons [32]. Therefore, the ammonia production area of CFPUs is commonly regarded as a hazard installation. According to the requests of related policies and regulations, the denittation reductant is changed from liquid ammonia to urea to eliminate the risks of transportation and storage of liquid ammonia. It is foreseeable that many CFPUs would apply urea to produce ammonia instead of using liquid ammonia. The urea hydrolysis process could eradicate the potential danger caused by storage and transportation of liquid ammonia and have technical advantages of centralized layout, stability and reliability, which makes it an ideal technology to replace liquid ammonia. The medium pressure and high-temperature steam of boilers is usually used as the heat source for hydrolysis reaction in the urea hydrolyzer of coal-fired power plant. The steam quality is high, and its exergy loss as the external heating source is severe. Before entering the hydrolyzer, the steam needs to be cooled and depressurized by spraying demineralized water. While increasing the consumption of demineralized water, it also causes the fluctuation of the operation of the hydrolysis unit, which affects the production of ammonia gas. When coupling different thermal systems, it is necessary to consider the coupling scheme in detail to maximize the power generation. In particular, when integrating coal-fired power plants with other power plants, due to the complexity of coal-fired power systems, the arrangement of their energy-consuming auxiliary equipment needs to be thought, taking the layout of urea hydrolysis unit (UHU) as an example in this article. This study develops a deep integration of a 500 t/d WTEU and a 660 MW CFPU based on the steam-water cycle and hydrolysis of urea into ammonia process, according to the existing research on the integration of a waste incineration plant and a coal-fired power plant [31, 33]. The performance of this integrated design is evaluated by thermo dynamic analysis and economic analysis methods, which is described by the previous works [25; 34; 35]. In the hybrid system, the energy produced by waste incineration is delivered to the CFPU, which dramatically increases the power output of WTE system. The chief goals and innovations of this work could be concluded as follows: (1) Establish a novel integrated WTE system based on urea hydrolysis process and optimized steam-water cycle. (2) Transfer the heat source of UHU to the WTE system to reduce energy consumption and to improve UHU security and flexibility. (3) Deliver the energy of MSW to the steam-water cycle of CFPU. (4) Examine the advantages of the integrated system through thermodynamic and economic analysis methods. (5) Discuss the net power output of different integrated modes.