A steam energy cascade utilization sludge drying coupled power generation system and its working method

Abstract

The present invention discloses a sludge drying coupled power generation system for cascaded utilization of steam energy and a working method thereof. Each extraction port on an extraction steam turbine unit is connected to the inlet of a main pipe. The outlet of the main pipe is divided into two paths, one of which is connected to the inlet of the steam turbine through a steam turbine steam flow regulating valve, and the other is connected to one end of a turbine bypass. The outlet of the steam turbine and the other end of the steam turbine bypass are connected to the inlet of a pressure reducing desuperheater. A bypass steam flow regulating valve is provided on the turbine bypass. The outlet of the pressure reducing desuperheater is divided into two paths after passing through a steam indirect dryer and a drain tank. One of which is connected to the inlet of the pressure reducing desuperheater through a desuperheating water regulating valve, and the other is connected to an external unit thermal system. The steam turbine is connected to a generator. The system and method realize cascaded utilization of steam energy, have high utilization efficiency of extracted steam, and are good in economy.

Description

Technical Field

[0001] The invention belongs to the field of sludge disposal and relates to a steam energy cascade utilization sludge drying coupled power generation system and a working method thereof. Background Art

[0002] With the development and progress of society, the discharge of urban and industrial wastewater continues to increase, and the total amount of sludge after treatment in sewage treatment plants has also continued to increase. The sludge treatment situation is extremely challenging. At the same time, facing increasingly stringent environmental protection requirements, sludge treatment requires the reduction, stabilization, harmlessness, and resource utilization of sludge. Among existing sludge treatment technologies, sludge incineration technology has the advantages of high volume and weight reduction rates, fast processing speed, thorough removal of pathogens, and energy reuse, and is currently widely used.

[0003] Coal-fired power plants account for approximately 60% of my country's installed capacity. Integrating sludge drying with power generation in coal-fired power plants can not only increase the proportion of non-fossil energy consumption and fossil energy substitution, but also leverage the advantages of a clean and efficient platform for centralized coal-fired power generation pollutant management. Since municipal sewage sludge has a moisture content of approximately 80%, directly incinerating wet sludge poses a series of problems, such as coal bunker blockage. However, incinerating dried sludge has a minimal impact on the pulverizing, combustion, and boiler efficiency of existing coal-fired boilers. Therefore, smooth sludge incorporation requires reducing the sludge moisture content to below 40%. Steam indirect drying is one of the sludge drying technologies currently used for incinerating sludge in coal-fired power plants. To ensure the proper operation of indirect steam drying systems, high-quality steam extracted from the units is typically desuperheated and depressurized before being used in the indirect steam dryer to dry the sludge. Traditional methods of desuperheating and depressurization utilize desuperheaters and throttling, which waste energy. Improving the energy efficiency and economical operation of steam drying systems is a critical issue that needs to be addressed urgently. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a steam energy cascade utilization sludge drying coupled power generation system and its working method. The system and method realize the cascade utilization of steam energy, the utilization efficiency of extracted steam is high, and the economy is good.

[0005] To achieve the above-mentioned object, the steam energy cascade utilization sludge drying coupled power generation system and its working method described in the present invention include an extraction steam turbine unit, a main pipe, a generator, a steam turbine steam flow control valve, a steam turbine, a steam turbine bypass, a pressure reducing desuperheater, a bypass steam flow control valve, a desuperheating water control valve, a steam indirect dryer and a drain tank;

[0006] Each extraction port on the extraction steam turbine unit is connected to the inlet of the main pipe. The outlet of the main pipe is divided into two paths, one of which is connected to the inlet of the steam turbine through the steam turbine steam flow regulating valve, and the other is connected to one end of the steam turbine bypass. The outlet of the steam turbine and the other end of the steam turbine bypass are connected to the inlet of the pressure reducing desuperheater. A bypass steam flow regulating valve is provided on the steam turbine bypass. The outlet of the pressure reducing desuperheater is divided into two paths after passing through the steam indirect dryer and the drain tank. One of which is connected to the inlet of the pressure reducing desuperheater through the desuperheating water regulating valve, and the other is connected to the external unit thermal system. The steam turbine is connected to the generator.

[0007] The outlet of the pressure reducing desuperheater is divided into two routes after passing through the steam indirect dryer, drain tank and circulation pump.

[0008] Temperature and pressure detection systems are installed on the main pipe, on the pipeline between the main pipe and the extraction port of the extraction steam turbine unit, and on the pipeline between the pressure reducing desuperheater and the steam indirect dryer.

[0009] A control valve is provided on the pipeline between the main pipe and the extraction port of the extraction steam turbine unit.

[0010] Adjust the opening of the turbine steam flow control valve and the bypass steam flow control valve to adjust the steam parameters.

[0011] By adjusting the opening of the desuperheating water regulating valve, the desuperheating water flow at the inlet of the pressure reducing desuperheater is adjusted to make secondary adjustments to the steam parameters.

[0012] The working method of the steam energy cascade utilization sludge drying coupled power generation system of the present invention comprises the following steps:

[0013] The steam parameters required by the indirect steam dryer are obtained based on the actual load of the indirect steam dryer. The steam parameters required by the main steam pipe when the steam turbine steam flow control valve is closed and the bypass steam flow control valve is opened are calculated. The extraction port is selected based on the steam parameters of each extraction port of the current extraction steam turbine unit to avoid the impact of unit load bypass on the extraction parameters. The steam pressure of the selected extraction port should be 10% to 20% higher than the main pipe pressure.

[0014] According to the steam temperature and pressure in the main pipe and at the inlet of the steam indirect dryer, the opening of the turbine steam flow control valve and the bypass steam flow control valve is adjusted, thereby adjusting the steam flow at the turbine inlet and in the turbine bypass. The steam is cooled and decompressed by the steam turbine, achieving a one-time adjustment of the steam parameters, and the steam turbine drives the generator to generate electricity;

[0015] The steam that has undergone primary adjustment enters the pressure reducing desuperheater. According to the steam temperature and pressure at the inlet of the steam indirect dryer, the opening of the desuperheating water regulating valve is adjusted to perform secondary adjustment on the steam to meet the normal production of the steam indirect dryer.

[0016] The drain water produced by the steam indirect dryer is discharged into the drain tank. The water output from the drain tank is divided into two paths, one of which enters the external unit thermal system, and the other enters the pressure reducing desuperheater as cooling water.

[0017] The present invention has the following beneficial effects:

[0018] The steam energy cascade utilization sludge drying coupled power generation system and its working method described in the present invention select a steam extraction port during specific operation to reduce the extraction of high-grade steam while meeting the normal production of the steam indirect dryer, thereby reducing the impact of steam extraction on the thermal efficiency of the extraction steam turbine unit; the steam turbine system is used to adjust the steam parameters to improve the energy utilization efficiency while meeting the production requirements, reduce the power consumption of the drying center, realize the cascade utilization of steam energy, effectively improve the energy utilization efficiency, have good economy, and promote energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Among them, 1 is the steam turbine, 2 is the generator, 3 is the pressure reducing desuperheater, 4 is the steam indirect dryer, 5 is the drain tank, 6 is the circulating pump, 7 is the desuperheating water regulating valve, 8 is the steam turbine steam flow regulating valve, and 9 is the bypass steam flow regulating valve. DETAILED DESCRIPTION

[0021] The present invention is described in further detail below with reference to the accompanying drawings:

[0022] refer to Figure 1 The steam energy cascade utilization sludge drying coupled power generation system and its working method of the present invention include an extraction steam turbine unit, a main pipe, a generator 2, a steam turbine steam flow regulating valve 8, a steam turbine 1, a steam turbine bypass, a pressure reducing desuperheater 3, a bypass steam flow regulating valve 9, a desuperheating water regulating valve 7, a steam indirect dryer 4 and a drain box 5; each extraction port on the extraction steam turbine unit is connected to the inlet of the main pipe, and the outlet of the main pipe is divided into two paths, one of which is connected to the steam turbine through the steam turbine steam flow regulating valve 8. 1, and the other is connected to one end of the turbine bypass. The outlet of the steam turbine 1 and the other end of the turbine bypass are connected to the inlet of the pressure reducing desuperheater 3. A bypass steam flow regulating valve 9 is provided on the turbine bypass. The outlet of the pressure reducing desuperheater 3 is divided into two paths after passing through the steam indirect dryer 4, the drain tank 5 and the circulating pump 6. One path is connected to the inlet of the pressure reducing desuperheater 3 through the desuperheating water regulating valve 7, and the other path is connected to the external unit thermal system. The steam turbine 1 is connected to the generator 2.

[0023] Temperature and pressure detection systems are installed on the main pipe, on the pipeline between the main pipe and the extraction port of the extraction steam turbine unit, and on the pipeline between the pressure reducing desuperheater 3 and the steam indirect dryer 4; a control valve is installed on the pipeline between the main pipe and the extraction port of the extraction steam turbine unit.

[0024] Adjust the opening of the turbine steam flow control valve 8 and the bypass steam flow control valve 9 to adjust the steam parameters once; adjust the opening of the desuperheating water control valve 7 to adjust the desuperheating water flow at the inlet of the pressure reducing desuperheater 3 to adjust the steam parameters twice.

[0025] The working method of the steam energy cascade utilization sludge drying coupled power generation system of the present invention comprises the following steps:

[0026] The steam parameters required by the indirect steam dryer 4 are obtained based on the actual load of the indirect steam dryer 4. The steam parameters required by the main steam pipe when the steam turbine steam flow control valve 8 is closed and the bypass steam flow control valve 9 is opened are calculated. The extraction port is selected based on the steam parameters of each extraction port of the current extraction steam turbine unit to avoid the impact of unit load bypass on the extraction parameters. The steam pressure of the selected extraction port is 10% to 20% higher than the main pipe pressure.

[0027] According to the steam temperature and pressure in the main pipe and at the inlet of the steam indirect dryer 4, the opening of the turbine steam flow regulating valve 8 and the bypass steam flow regulating valve 9 are adjusted, thereby adjusting the steam flow at the inlet of the steam turbine 1 and in the turbine bypass. The steam is cooled and decompressed by the steam turbine 1, achieving a one-time adjustment of the steam parameters. The steam turbine 1 drives the generator 2 to generate electricity.

[0028] The steam after the primary adjustment enters the pressure reducing desuperheater 3. According to the steam temperature and pressure at the inlet of the steam indirect dryer 4, the opening of the desuperheating water regulating valve 7 is adjusted to perform secondary adjustment on the steam to meet the normal production of the steam indirect dryer 4.

[0029] The drain water produced by the steam indirect dryer 4 is discharged into the drain tank 5. The water output from the drain tank 5 is divided into two paths, one of which enters the external unit thermal system, and the other enters the pressure reducing desuperheater 3 as cooling water.

[0030] Under normal operation, steam is extracted through the selected steam extraction port. When the load of the steam indirect dryer 4 or the unit load changes, so that the extracted steam does not match the steam parameters required by the steam indirect dryer 4, the steam extraction port is reselected.

Claims

1. A steam energy cascade utilization sludge drying coupled power generation system, characterized in that: It comprises an extraction steam turbine unit, a main pipe, a generator (2), a steam turbine steam flow regulating valve (8), a steam turbine (1), a steam turbine bypass, a pressure reducing desuperheater (3), a bypass steam flow regulating valve (9), a desuperheating water regulating valve (7), a steam indirect dryer (4) and a drain tank (5); Each extraction port on the extraction steam turbine unit is connected to the inlet of the main pipe, and the outlet of the main pipe is divided into two paths, one of which is connected to the inlet of the steam turbine (1) through the steam turbine steam flow control valve (8), and the other is connected to one end of the steam turbine bypass. The outlet of the steam turbine (1) and the other end of the steam turbine bypass are connected to the inlet of the pressure reducing desuperheater (3). A bypass steam flow control valve (9) is provided on the steam turbine bypass. The outlet of the pressure reducing desuperheater (3) is divided into two paths after passing through the steam indirect dryer (4) and the drain tank (5). One of which is connected to the inlet of the pressure reducing desuperheater (3) through the desuperheating water control valve (7), and the other is connected to the external unit thermal system. The steam turbine (1) is connected to the generator (2); The outlet of the pressure reducing desuperheater (3) is divided into two routes after passing through the steam indirect drying machine (4), the drain tank (5) and the circulation pump (6); Temperature and pressure detection systems are provided on the main pipe, on the pipe between the main pipe and the extraction port of the extraction steam turbine unit, and on the pipe between the pressure reducing desuperheater (3) and the steam indirect dryer (4); A control valve is provided on the pipeline between the main pipe and the extraction port of the extraction steam turbine unit.

2. The steam energy cascade utilization sludge drying coupled power generation system according to claim 1 is characterized in that: The openings of the turbine steam flow regulating valve (8) and the bypass steam flow regulating valve (9) are adjusted to adjust the steam parameters.

3. The steam energy cascade utilization sludge drying coupled power generation system according to claim 1 is characterized in that: By adjusting the opening of the desuperheating water regulating valve (7), the flow rate of desuperheating water at the inlet of the pressure reducing desuperheater (3) is adjusted, and the steam parameters are adjusted secondary.

4. A method for operating the steam energy cascade utilization sludge drying coupled power generation system as claimed in claim 1, characterized in that: The following steps are involved: The steam parameters required by the steam indirect dryer (4) are obtained according to the actual load of the steam indirect dryer (4), and the steam parameters of the steam main pipe required when the steam turbine steam flow regulating valve (8) is closed and the bypass steam flow regulating valve (9) is opened are calculated; the extraction port is selected according to the steam parameters of each extraction port of the current extraction steam turbine unit to avoid the influence of the unit load disturbance on the extraction parameters, and the steam pressure of the selected extraction port is 10% to 20% higher than the main pipe pressure; According to the steam temperature and pressure in the main pipe and at the inlet of the steam indirect dryer (4), the opening of the steam turbine steam flow regulating valve (8) and the bypass steam flow regulating valve (9) are adjusted, thereby adjusting the steam flow at the inlet of the steam turbine (1) and in the steam turbine bypass, and the steam is cooled and decompressed by the steam turbine (1), thereby achieving a one-time adjustment of the steam parameters, and the steam turbine (1) drives the generator (2) to generate electricity; The steam that has undergone the primary adjustment enters the pressure reducing desuperheater (3), and the opening of the desuperheating water regulating valve (7) is adjusted according to the steam temperature and pressure at the inlet of the steam indirect dryer (4), and the steam is subjected to secondary adjustment to meet the normal production of the steam indirect dryer (4); The drain water generated by the steam indirect dryer (4) is discharged into the drain tank (5). The water output from the drain tank (5) is divided into two paths, one of which enters the external unit thermal system, and the other enters the pressure reducing desuperheater (3) as cooling water.

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