WO2020029041A1

WO2020029041A1 - System for recovering waste heat from pure low temperature flue gas of cement plant

Info

Publication number: WO2020029041A1
Application number: PCT/CN2018/099054
Authority: WO
Inventors: 刘祥斌
Original assignee: 江苏东九重工股份有限公司
Priority date: 2018-08-06
Filing date: 2018-08-06
Publication date: 2020-02-13

Abstract

A system for recovering waste heat from pure low temperature flue gas of a cement plant, comprising: a rotary kiln (1), a kiln front clinker cooler (5), and a heated device system (12). The rotary kiln (1) is connected to a kiln rear preheater (2). The kiln rear preheater (2) is connected to a kiln rear waste heat recovery device (3). The kiln front clinker cooler (5) is connected to a kiln front waste heat recovery device (6) by a second dust collector (10.2). The kiln front waste heat recovery device (6) is sequentially connected to a chimney (11) by a third dust collector (10.3) and a second induced draft fan (9.2). The kiln rear waste heat recovery device (3) is internally provided with a kiln rear heat transfer surface assembly (4). The kiln front waste heat recovery device (6) is internally provided with a kiln front heat transfer surface assembly (7) . The kiln rear heat transfer surface assembly (4), the heated device system (12), and the kiln front heat transfer surface assembly (7) are sequentially connected to each other. This system has a simplified structure and reduces costs.

Description

Pure low temperature flue gas waste heat recovery system in cement plant

Technical field

The invention relates to a flue gas waste heat recovery system, and more particularly to a pure low-temperature flue gas waste heat recovery system in a cement plant.

Background technique

At present, in the waste heat recovery system of the new dry process cement clinker production line, the pure low-temperature exhaust gas of about 350 ° C discharged from the kiln head clinker cooler and the kiln end preheater is provided by a kiln head steam waste heat boiler (AQC furnace for short) and Kiln tail steam waste heat boiler (SP furnace for short) realizes waste heat recovery of pure low temperature exhaust gas.

The heat transfer medium of the steam waste heat boiler is water, which is usually composed of steam superheater, evaporator, economizer, steam drum and pipeline system. Steam waste heat boilers have high requirements on the quality of water. The failure of water quality will affect the normal operation of steam waste heat boilers. Steam waste heat boilers have many components, large structures, large metal consumption, and high investment costs. Operating pressure of steam waste heat boilers High, high pressure requirements for pipelines, and high daily operation and maintenance costs.

Summary of the invention

The purpose of the present invention is to provide a pure low-temperature flue gas waste heat recovery system in a cement plant. The pure low-temperature flue gas waste heat recovery system of the cement plant solves the problem that the prior art adopts steam waste heat boilers with many components, huge structures, large metal consumption, High investment costs, high operating pressure of steam waste heat boilers, high pressure requirements on pipelines and piping, and high daily operation and maintenance costs.

In order to achieve the above-mentioned object of the invention, a pure low-temperature flue gas waste heat recovery system of the cement plant of the present invention includes a rotary kiln, a kiln head clinker cooler, a heating equipment system, a flue gas outlet of the rotary kiln, and a flue gas from a preheater at the end of the kiln. Gas inlet connection, the flue gas outlet of the preheater at the kiln end is connected to the flue gas inlet of the waste heat recovery equipment at the kiln end; the flue gas outlet of the kiln head clinker cooler is connected to the flue gas of the kiln head waste heat recovery equipment through a second dust collector The inlet is connected, and the flue gas outlet of the waste heat recovery equipment of the kiln head is connected to the chimney through the third dust collector and the second induced draft fan in turn; the kiln end waste heat recovery equipment is provided with several sets of kiln end heat transfer surface groups and the kiln head waste heat recovery equipment. There are several sets of kiln head heat transfer surface groups connected in series. The outlet end of the kiln tail heat transfer surface group is connected to the inlet of the heating equipment system through a heat transfer tube, and the outlet of the heat equipment system is used to transfer heat to the kiln head through the heat transfer tube. The inlet end of the surface group is connected, and the outlet end of the kiln head heat transfer surface group is connected to the inlet end of the kiln tail heat transfer surface group through a heat transfer tube. A heat transfer medium is filled in the thermal equipment system. The flue gas outlet of the kiln tail waste heat recovery equipment is respectively connected to the raw meal mill, the first dust collector and the coal mill through a first induced draft fan. The pipe between the kiln end preheater and the kiln tail waste heat recovery equipment is connected to the first induced draft fan; the pipe between the third dust collector and the kiln head waste heat recovery equipment is connected to the kiln head clinker cooler; the second induced fan The pipe between the third dust collector and the clinker is cooled by a third induced draft fan; the heat transfer medium and the flue gas flow in the opposite direction; the preheater at the kiln end is composed of several cyclones; the heat transfer medium is organic Heat carrier; organic heat carrier is a thermal oil.

According to the above technical solutions, compared with the prior art, the present invention has the following advantages:

1. The waste heat recovery system uses heat-conducting oil as the heat transfer medium, which eliminates the need for water treatment systems and equipment, effectively reduces the metal consumption of the equipment, and greatly saves initial investment costs and subsequent operation and maintenance costs.

2. The pure low-temperature flue gas and heat transfer medium of the waste heat recovery system flow in opposite directions from each other, forming a pure countercurrent heat exchange. The system approach point temperature is within 30 ° C, which significantly improves the thermal efficiency of the system.

3. The waste heat recovery system obtains a very high operating temperature under a very low working pressure, which greatly reduces the operating pressure and safety requirements of the system, and improves the reliability of the system and equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural flowchart of the present invention.

In the picture: 1. rotary kiln, 2. kiln tail preheater, 3. kiln tail waste heat recovery equipment, 4. kiln tail heat transfer surface group, 5. kiln head clinker cooler, 6. kiln head waste heat recovery equipment, 7. Kiln head heat transfer surface group, 8. Heat transfer tube, 9.1. First induced draft fan, 9.2. Second induced draft fan, 9.3. Third induced draft fan, 10.1. First dust collector, 10.2. Second dust collection Device, 10.3. Third dust collector, 11. Chimney, 12. Thermal equipment system, 13. Heat transfer medium, 14. Raw meal mill, 15. Coal mill.

detailed description

The drawings disclose, without limitation, a schematic structural diagram of a specific embodiment of the present invention. The technical solution of the present invention will be further described below with reference to the drawings and specific embodiments.

As shown in Figure 1, this cement plant's pure low-temperature flue gas waste heat recovery system includes a rotary kiln, a kiln head clinker cooler, and a thermal equipment system. The flue gas outlet of the rotary kiln is connected to the flue gas inlet of the preheater at the end of the kiln. The flue gas outlet of the kiln end preheater is connected to the flue gas inlet of the kiln end waste heat recovery equipment; the flue gas outlet of the kiln head clinker cooler is connected to the flue gas inlet of the kiln head waste heat recovery equipment through the second dust collector 10.2 The flue gas outlet of the kiln head waste heat recovery equipment is connected to the chimney in turn through the third dust collector 10.3 and the second induced draft fan 9.2; the kiln tail waste heat recovery equipment is provided with several sets of kiln tail heat transfer surface groups in series, and the kiln head waste heat recovery equipment There are several sets of kiln head heat transfer surface groups connected in series. The outlet end of the kiln tail heat transfer surface group is connected to the inlet of the heating equipment system through a heat transfer tube, and the outlet of the heat equipment system is used to transfer heat to the kiln head through the heat transfer tube. The inlet end of the surface group is connected, and the outlet end of the kiln head heat transfer surface group is connected to the inlet end of the kiln tail heat transfer surface group through a heat transfer tube. A heat transfer medium is filled in the thermal equipment system. The flue gas outlet of the kiln tail waste heat recovery equipment is connected to the raw meal mill, the first dust collector 9.1, and the coal mill through the first induced draft fan 10.1, respectively. The pipeline between the kiln tail preheater and the kiln tail waste heat recovery equipment is connected to the first induced draft fan 9.1. The pipe between the third dust collector 10.3 and the kiln head waste heat recovery equipment is connected to the kiln head clinker cooler. The pipeline between the second induced draft fan 9.2 and the third dust collector 10.3 is connected to the kiln head clinker cooler through the third induced draft fan 9.3. The heat transfer medium and the flue gas flow in the opposite direction, and the kiln tail preheater consists of several cyclones. The cylinder is constituted, the heat transfer medium is an organic heat carrier, and the organic heat carrier is a thermal conductive oil. The lower temperature heat transfer medium from the heat equipment system first passes through the kiln head heat transfer surface group of the kiln head waste heat recovery equipment to complete the first stage of heat exchange to form a higher temperature heat transfer medium and then passes through the heat transfer tube. The kiln tail heat transfer surface group sent to the kiln tail waste heat recovery equipment participates in the second stage of heat exchange; forms a high temperature heat transfer medium and finally enters the heat equipment system; the high temperature heat transfer medium passes through the heat equipment system and becomes a lower temperature. The heat transfer medium is returned to the kiln head and the waste heat recovery equipment participates in the system's waste heat recovery again to form a closed thermal cycle. In the waste heat recovery equipment, the flue gas and the heat transfer medium flow in opposite directions from each other, forming a countercurrent heat exchange with high heat recovery efficiency.

The preferred embodiments of the present invention described above with reference to the accompanying drawings are only used to illustrate the embodiments of the present invention, rather than as a limitation on the foregoing inventive objectives and the content and scope of the appended claims. Any simple modifications, equivalent changes and modifications made by the embodiments still belong to the technical and right protection scope of the present invention.

Claims

A pure low-temperature flue gas waste heat recovery system for a cement plant, which is characterized by comprising a rotary kiln, a kiln head clinker cooler, and a heating equipment system. The flue gas outlet of the rotary kiln is connected to the flue gas inlet of a preheater at the end of the kiln. The flue gas outlet of the preheater at the kiln end is connected to the flue gas inlet of the waste heat recovery equipment at the kiln end; the flue gas outlet of the kiln head clinker cooler is connected to the flue gas inlet of the waste heat recovery equipment at the kiln head through a second dust collector. The flue gas outlet of the head waste heat recovery equipment is connected to the chimney in turn through a third dust collector and a second induced draft fan; the kiln tail waste heat recovery equipment is provided with a series of kiln tail heat transfer surface groups in series, and the kiln head waste heat recovery equipment is provided with several groups The kiln head heat transfer surface group in series, the exit end of the kiln tail heat transfer surface group is connected to the inlet of the heat equipment system through the heat transfer tube, and the outlet of the heat equipment system is connected to the inlet of the kiln head heat transfer surface group through the heat transfer tube. The end of the kiln head heat transfer surface group is connected to the inlet end of the kiln tail heat transfer surface group through a heat transfer tube, and a heat transfer medium is filled in the heat equipment system.
The pure low-temperature flue gas waste heat recovery system of a cement plant according to claim 1, characterized in that the flue gas outlet of the kiln tail waste heat recovery equipment is respectively connected to the raw meal mill, the first dust collector, and the coal mill through a first induced draft fan.
The pure low temperature flue gas waste heat recovery system according to claim 2, characterized in that the pipeline between the kiln tail preheater and the kiln tail waste heat recovery equipment is connected to the first induced draft fan.
The pure low temperature flue gas waste heat recovery system according to claim 1, characterized in that the pipeline between the third dust collector and the kiln head waste heat recovery equipment is connected to the kiln head clinker cooler.
The pure low temperature flue gas waste heat recovery system according to claim 1, characterized in that the pipeline between the second induced draft fan and the third dust collector is connected to the kiln head clinker cooler through the third induced draft fan.
The pure low temperature flue gas waste heat recovery system according to claim 1, characterized in that the heat transfer medium and the flue gas flow direction are opposite.
The pure low temperature flue gas waste heat recovery system according to claim 1, characterized in that the preheater at the kiln end is composed of a plurality of cyclones.
The pure low temperature flue gas waste heat recovery system according to claim 1, characterized in that the heat transfer medium is an organic heat carrier.
The pure low-temperature flue gas waste heat recovery system according to claim 8, characterized in that the organic heat carrier is a heat-conducting oil.