Cement kiln series reheating type low-temperature waste heat power generation system

Abstract

The invention discloses a cement kiln series reheating type low-temperature waste heat power generation system. Belongs to the technical field of cement production line waste heat recovery power generation. A waste heat boiler is connected with a cement kiln firing system, cement kiln waste heat is recovered, and low-pressure steam and high-pressure steam generated by a kiln tail waste heat boiler are sent to a kiln head boiler high-pressure and low-pressure public superheater to be reheated. The kiln head boiler generates hot water to be supplied to the kiln tail waste heat boiler, low-pressure steam and high-pressure steam are generated, the high-pressure steam of the kiln head boiler and the high-pressure steam of the kiln tail waste heat boiler are mixed and then enter the high-pressure public superheater, and high-pressure and high-temperature superheated steam is generated and sent to the back pressure type steam turbine to do work for power generation. Kiln head boiler low-pressure steam, kiln tail waste heat boiler low-pressure steam and back pressure turbine low-pressure steam are mixed and then enter a low-pressure public superheater, and low-pressure high-temperature superheated steam is generated and sent to a straight condensing turbine to do work and generate power. According to the system, the waste heat utilization structure is adjusted, the structure of the steam turbine is optimized, and the efficiency of the steam turbine and the waste heat generating capacity are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of waste heat recovery power generation in cement production lines and relates to a cement kiln series reheating type low-temperature waste heat power generation system. Background Art

[0002] With the continuous development of new dry process cement technology, the new generation of new dry process cement production line has the characteristics of lower heat consumption, lower power consumption and lower exhaust gas emission index. With the reduction of heat consumption of new dry process cement production line, the quality of residual heat source is also greatly reduced. The exhaust gas temperature at the outlet of the preheater at the end of the kiln is lower, about 240℃~260℃, and the exhaust gas volume is lower, about 1.27~1.35Nm3 / kg.cl; due to the improvement of grate cooler efficiency, the cooling air volume used by the grate cooler is reduced, and the exhaust gas temperature of the grate cooler at the head of the kiln is increased, about 380℃~420℃ (mid-air intake), and the exhaust gas volume is reduced to 0.65~0.75Nm3 / kg.cl. The overall waste heat condition is reduced by about 30~40% compared with the previous generation of new dry process cement production line, and the power generation per ton of clinker in the cement kiln is also greatly reduced accordingly.

[0003] At present, waste heat power generation systems of cement kilns mostly adopt single-pressure power generation systems, dual-pressure power generation systems, and flash evaporation power generation systems, and the system power generation efficiency is generally around 20%~22%; therefore, how to improve the waste heat power generation efficiency of cement kilns, and then increase the power generation of cement kilns per ton of clinker, and reduce the electricity demand of cement production lines has become a problem that needs to be considered. Summary of the invention

[0004] The technical solution of the present invention is: a cement kiln series reheat type low-temperature waste heat power generation system described in the present invention comprises a waste heat boiler, a high-pressure common superheater, a low-pressure common superheater, a back-pressure steam turbine, a pure condensing steam turbine, a condenser, a condensate pump, a steam seal heater, a deaerator and a boiler feed pump; The waste heat boiler includes a kiln tail waste heat boiler and a kiln head waste heat boiler, which are respectively connected to the cement kiln burning system; Furthermore, the kiln head waste heat boiler is divided into a high temperature section I and a high temperature section II.

[0005] Furthermore, one end of the kiln tail waste heat boiler is connected to the cement kiln firing kiln tail system, and the other end thereof is respectively connected to the high-pressure common superheater and the low-pressure common superheater of the kiln head waste heat boiler.

[0006] One end of the kiln head waste heat boiler is connected to the cement kiln firing kiln head system, and the other end thereof is respectively connected to the high pressure common superheater and the low pressure common superheater.

[0007] Furthermore, the high-pressure common superheater is located in the high-temperature I section of the kiln head waste heat boiler, which is connected to the back-pressure steam turbine.

[0008] Furthermore, the low-pressure common superheater is located in the high-temperature II section of the kiln head waste heat boiler, which is connected to the back-pressure steam turbine and the pure condensing steam turbine respectively; The back-pressure steam turbine and the pure condensing steam turbine are arranged in series.

[0009] Furthermore, the pure condensing steam turbine is connected to a condenser.

[0010] The other end of the condenser is connected to a condensate pump, the other end of the condensate pump is connected to a steam seal heater, the other end of the steam seal heater is connected to a deaerator, and the other end of the deaerator is connected to a boiler feed water pump.

[0011] Furthermore, a generator is connected to the pure condensing steam turbine, and supporting auxiliary equipment is installed on the generator.

[0012] Furthermore, the condenser is continuously connected to a circulating water pump and a cooling tower through a pipeline.

[0013] Furthermore, the condenser, circulating water pump and cooling tower constitute a circulating cooling water system; Auxiliary equipment is connected to the circulating cooling water system.

[0014] The beneficial effects of the present invention are: 1. The boiler adopts a high- and low-pressure configuration system with high heat recovery efficiency; 2. The temperature of the low-pressure steam in the boiler is as high as the temperature of the high-pressure steam, and the system has high power generation efficiency; 3. The high-pressure steam passes through the back-pressure steam turbine and then is heated by the low-pressure common superheater of the kiln head boiler, and the system has high power generation efficiency; 4. The system has high power generation efficiency, saving self-used electricity and water consumption; 5. The system is flexible and reliable, and can be newly built or the existing inefficient waste heat power generation system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram of a conventional cement kiln low-temperature waste heat power generation system in the prior art (where 1 is a waste heat boiler at the end of the kiln, 2 is a waste heat boiler at the head of the kiln, 3 is a high-pressure common superheater, 4 is a pure condensing steam turbine, 5 is a generator, 6 is a condenser, 7 is a condensate pump, 8 is a steam seal heater, 9 is a deaerator, 10 is a boiler feed water pump, 11 is a circulating water pump, and 12 is a cooling tower); Figure 2 This is a diagram of a cement kiln series reheat type low-temperature waste heat power generation system of the present invention; In the figure: 1 is the waste heat boiler at the end of the kiln, 2 is the waste heat boiler at the head of the kiln, 3 is the high-pressure common superheater, 4 is the low-pressure common superheater, 5 is the back-pressure steam turbine, 6 is the pure condensing steam turbine, 7 is the generator, 8 is the condenser, 9 is the condensate pump, 10 is the steam seal heater, 11 is the deaerator, 12 is the boiler feed pump, 13 is the circulating water pump, and 14 is the cooling tower. DETAILED DESCRIPTION

[0016] The specific technical scheme of the present invention is further described in detail below with reference to specific examples.

[0017] As shown in the figure, a cement kiln series reheat type low-temperature waste heat power generation system described in the present invention includes a waste heat boiler (a waste heat boiler 1 at the end of the kiln and a waste heat boiler 2 at the head of the kiln), a high-pressure common superheater 3, a low-pressure common superheater 4, a back-pressure steam turbine 5, a pure condensing steam turbine 6, a generator 7, a condenser 8, a condensate pump 9, a steam seal heater 10, a deaerator 11, a boiler feed water pump 12, a circulating water pump 13 and a cooling tower 14; The waste heat boiler is connected to the cement kiln burning system to recover the waste heat of the cement kiln; The condensate pump 9 delivers the condensate to the deaerator 11; The deaerator 11 removes oxygen from the feed water; The back-pressure steam turbine 5 utilizes the waste heat boiler to generate power with high-pressure steam and discharges low-pressure and low-temperature steam; The pure condensing steam turbine 6 utilizes the waste heat boiler to produce low-pressure and high-temperature steam to generate electricity; The condenser 8 condenses the exhaust steam discharged from the pure condensing steam turbine 6 into water.

[0018] The waste heat boiler includes a kiln head waste heat boiler 2 and a kiln tail waste heat boiler 1, which are connected to the cement kiln firing system to absorb waste heat in the cement kiln exhaust gas. The heating surface layout of the waste heat boiler needs to be configured according to the thermal parameters of the back pressure steam turbine 5 and the pure condensing steam turbine 6. The waste heat is used to heat the feed water, and high-temperature and high-pressure steam is generated and sent to the back pressure steam turbine. At the same time, the low-temperature and low-pressure steam generated by the kiln head and kiln tail waste heat boilers and the low-temperature and low-pressure steam discharged from the back pressure steam turbine 5 are heated to generate high-temperature and low-pressure steam that is sent to the pure condensing steam turbine 6 to generate power.

[0019] The system also includes a pure condensing steam turbine 6, a generator 7 and its supporting auxiliary equipment, such as an oil system of the pure condensing steam turbine 6, a cooling system of the generator 7, etc.

[0020] The system further comprises cooling equipment such as a condenser 8 and a cooling tower 14, which cool the exhaust steam entering the pure condensing steam turbine 6 after doing work into condensed water.

[0021] Specifically, the kiln tail waste heat boiler 1 is connected to the cement kiln firing kiln tail system to generate high-pressure steam and low-pressure steam, which are respectively transported to the kiln head waste heat boiler 2, the high-pressure common superheater 3 and the low-pressure common superheater 4.

[0022] The kiln head waste heat boiler 2 is connected to the cement kiln firing kiln head system, generates hot water and sends it to the kiln tail waste heat boiler 1, generates high-pressure steam and low-pressure steam and sends them to the kiln head waste heat boiler 2, the high-pressure common superheater 3 and the low-pressure common superheater 4 respectively.

[0023] The high-pressure common superheater 3 is located in the high-temperature I section of the kiln head waste heat boiler 2, and heats the high-pressure steam of the kiln tail waste heat boiler 1 and the high-pressure steam of the kiln head waste heat boiler 2 and then sends them to the back-pressure steam turbine 5 to generate power.

[0024] The low-pressure common superheater 4 is located in the high-temperature II section of the kiln head waste heat boiler 2, and heats the low-pressure steam of the kiln tail waste heat boiler 1, the low-pressure steam of the kiln head waste heat boiler 2 and the exhaust steam of the back-pressure steam turbine 5, and then sends them to the pure condensing steam turbine 6.

[0025] The back-pressure steam turbine 5 introduces high-pressure and high-temperature steam from the kiln head waste heat boiler 2 to generate electricity, and the exhaust steam is sent to the low-pressure common superheater 4 of the kiln head waste heat boiler 2.

[0026] The pure condensing steam turbine 6 introduces low-pressure and high-temperature steam from the kiln head waste heat boiler 2 to generate electricity, and the exhaust steam is condensed in the condenser 8.

[0027] The condensate pump 9 heats the condensate from the power station condenser 8 through the steam seal heater 10 and then sends it to the deaerator 11 for deoxygenation. After deoxygenation, it is sent to the public hot water section of the kiln head waste heat boiler 2 through the boiler feed water pump 12.

[0028] The circulating water pump 13 and the cooling tower 14 form a circulating cooling water system to condense the exhaust steam of the pure condensing steam turbine 6 in the condenser 8 into condensed water. The back pressure steam turbine 5 and the pure condensing steam turbine 6 are arranged in series.

[0029] The main changes of the present invention are as follows: (1): The steam turbine is changed from a pure condensing low-parameter supplementary steam turbine to a high-pressure and high-temperature back-pressure steam turbine 5 and a low-pressure and high-temperature pure condensing steam turbine 6 arranged in series; (2): Steam parameters are improved. The high-pressure steam pressure is increased from 0.7~1.5MPa to above 1.5MPa; the low-pressure steam pressure is increased from 0.1~0.3MPa to above 0.3MPa, and the steam temperature is changed from 170~185℃ to above 350℃, which improves the efficiency of the steam turbine; (3): The kiln head waste heat boiler 2 is provided with a high pressure common superheater 3 and a low pressure common superheater 4; (4): The kiln tail waste heat boiler 1 adopts a dual pressure system; (5): The high-pressure steam from the waste heat boiler 1 at the end of the kiln is sent to the high-pressure common superheater 3 of the waste heat boiler 2 at the head of the kiln for reheating, and the low-pressure steam from the waste heat boiler 1 at the end of the kiln is sent to the low-pressure common superheater 4 of the waste heat boiler 2 at the head of the kiln for reheating; (6): The exhaust steam from the back-pressure steam turbine 5 is sent to the low-pressure common superheater 4 for reheating; (7): The pure condensing steam turbine 6 adopts a low-pressure and high-temperature design.

Claims

1. A cement kiln series reheat type low temperature waste heat power generation system, characterized in that: It includes a waste heat boiler, a high-pressure common superheater (3), a low-pressure common superheater (4), a back-pressure steam turbine (5), a pure condensing steam turbine (6), a condenser (8), a condensate pump (9), a steam seal heater (10), a deaerator (11) and a boiler feed water pump (12); The waste heat boiler comprises a kiln tail waste heat boiler (1) and a kiln head waste heat boiler (2), which are respectively connected to the cement kiln firing system.

2. According to claim 1, a cement kiln series reheat type low-temperature waste heat power generation system is characterized by: The kiln head waste heat boiler (2) is divided into a high temperature section I and a high temperature section II.

3. The cement kiln series reheat type low-temperature waste heat power generation system according to claim 1 is characterized in that: One end of the kiln tail waste heat boiler (1) is connected to the cement kiln firing kiln tail system, and the other end is respectively connected to the kiln head waste heat boiler (2), the high pressure common superheater (3) and the low pressure common superheater (4); One end of the kiln head waste heat boiler (2) is connected to the cement kiln firing kiln head system, and the other end thereof is respectively connected to the high-pressure common superheater (3) and the low-pressure common superheater (4).

4. A cement kiln series reheat type low temperature waste heat power generation system according to claim 2, characterized in that: The high-pressure common superheater (3) is located in the high-temperature I section of the kiln head waste heat boiler (2), and is connected to the back-pressure steam turbine (5).

5. The cement kiln series reheat type low temperature waste heat power generation system according to claim 2, characterized in that: The low-pressure common superheater (4) is located in the high-temperature II section of the kiln head waste heat boiler (2), and is respectively connected to the back-pressure steam turbine (5) and the pure condensing steam turbine (6); The back-pressure steam turbine (5) and the pure condensing steam turbine (6) are arranged in series.

6. The cement kiln series reheat type low temperature waste heat power generation system according to claim 1, characterized in that: The pure condensing steam turbine (6) is connected to a condenser (8); The other end of the condenser (8) is connected to a condensate pump (9), the other end of the condensate pump (9) is connected to a steam seal heater (10), the other end of the steam seal heater (10) is connected to a deaerator (11), and the other end of the deaerator (11) is connected to a boiler feed water pump (12).

7. A cement kiln series reheat type low temperature waste heat power generation system according to claim 6, characterized in that: A generator (7) is also connected to the pure condensing steam turbine (6).

8. The cement kiln series reheat type low temperature waste heat power generation system according to claim 7, characterized in that: Matching auxiliary equipment is also mounted on the generator (7).

9. The cement kiln series reheat type low temperature waste heat power generation system according to claim 1, characterized in that: The condenser (8) is also continuously connected to a circulating water pump (13) and a cooling tower (14) via a pipeline.

10. A cement kiln series reheat type low temperature waste heat power generation system according to claim 9, characterized in that: The condenser (8), the circulating water pump (13) and the cooling tower (14) constitute a circulating cooling water system; Auxiliary equipment is connected to the circulating cooling water system.

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