I. Project Introduction City sludge is a byproduct of urban wastewater treatment processes. On one hand, city sludge has a large production volume, high moisture content, difficult to remove water, low harmlessness rate, and direct discharge is harmful to the environment. However, it has a high calorific value and can be resourcefully utilized. On the other hand, there is a high demand for sludge reduction; traditional treatment methods such as landfilling, composting, and incineration all require a high moisture content in sludge. Further dewatering of sludge can be achieved through thermal drying methods, but traditional thermal drying methods are costly and an economical method is urgently needed to replace them. Sludge hot water hydrolysis technology can further efficiently and economically reduce the moisture content of sludge. This technology is based on the principle of cell wall rupture, which can achieve low energy consumption and high efficiency in sludge dewatering and drying. II. Technological Innovation and Leadership This technical solution has the following characteristics: (1) Homogeneous Pulverization Unit: The homogenization unit has the functions of storing, diluting, and sludge conditioning. The unique design of the homogenizer and the mixing method of dilution water with flash steam ensure that the sludge is rapidly homogenized before entering the pump, facilitating subsequent transportation. (2) Hydrothermal Unit: In the hydrothermal unit, the sludge is heated and pressurized to undergo a hydrothermal reaction. The reactor can be either batch or continuous (including radial flow or tower type). The unique reactor structure and stirring device result in high efficiency of steam utilization, rapid and thorough reactions, and effective separation of solids and liquids after the reaction. (3) Flash Evaporation Unit: The flash evaporation unit mainly serves to relieve pressure and cool down, while the generated flash steam is introduced into the homogenization and sludge conditioning unit for recycling. (4) Heat Exchanger: The unique heat exchanger structure can effectively prevent blockage. After being flashed, the temperature of the sludge is reduced, facilitating subsequent dewatering. (5) Dewatering Unit: The dehydration unit employs efficient pressure filtration technology to reduce the moisture content of sludge after hot hydrolysis to about 30%. (6) Economic analysis: The investment and operating costs are much lower than those of dry incineration technology (dry incineration investment: 250,000 to 500,000 yuan per ton of sludge with a moisture content of 80%, dry incineration operating cost: 225 to 490 yuan per ton of sludge with a moisture content of 80%). After treatment by this technology, there is a significant change in the shape and viscosity of the sludge, as shown in Figure 2. The hot hydrolysis breaks down the cell walls of the sludge, making it easier for water to separate from the sludge particles. A simple low-speed centrifuge (3000r/min) can achieve a moisture content below 50% after centrifugation at temperatures above 170°C. If followed by an efficient pressure filtration stage after hot hydrolysis, the moisture content can be reduced to below 30% at temperatures above 170°C. III. Market and Benefit Analysis (1) Huge market capacity: During the "Twelfth Five-Year Plan" period, China's investment in sludge treatment and disposal facilities will reach 34.7 billion yuan. By 2015, the national urban sludge harmless treatment rate is required to reach over 50% (currently less than 1/4), which means the demand market for urban sludge hot hydrolysis equipment will exceed 1,000 units. (2) Excellent economic performance: The investment and operating costs are lower than those of dry-drying incineration technology, especially the operating costs are far below related subsidies, making it economically viable. (3) Good social benefits: The urban sludge hot hydrolysis technology process is sealed, with no odor produced, and the sludge reduction effect is significant. A hot hydrolysis equipment for treating 100t of urban sludge with a moisture content of 80% per day has an investment cost of 13 million yuan per set, a total investment of 18 million yuan, and an operating cost of 131 yuan/ton. The corresponding government subsidy is 150~400 yuan/ton, the sewage plant subsidy is 0~100 yuan/ton. The total subsidy is 180 to 400 yuan per ton.