Multi-stage cooling process and device for coke oven crude gas
Technical Field
The invention relates to the technical field of coke oven high-temperature raw gas cooling, tar fraction separation and waste heat recovery, in particular to a multi-stage cooling process and a multi-stage cooling device for raw gas of a coke oven.
Background
The coking industry is developed along with the development of steel enterprises, is one of basic industries of the steel industry, is also an energy-consuming user, and the heating consumption in the coking process accounts for about 45-50% of the gas yield, so the coking industry is also an important industry for energy conservation and emission reduction. About 25% of coal is coked by coke, and various chemical products and coal gas are generated. The recovery of the chemical products has important significance for comprehensive utilization of coal resources and economic construction.
The common method in the existing coke oven crude gas cooling process is as follows: raw coke oven gas at 650-750 ℃ from a coke oven carbonization chamber passes through a coke oven riser and then enters a gas collecting tank. Spraying circulating ammonia water in the gas collecting tank to directly contact and cool the raw gas, and rapidly cooling the raw gas to 80-90 ℃ by virtue of the large vaporization of the circulating ammonia water, then cooling the raw gas to 25-35 ℃ in a primary cooler and then conveying the raw gas to the subsequent process. A large amount of heat energy is not utilized in the process, and a large amount of circulating ammonia water is needed.
Disclosure of Invention
The invention aims to provide a multi-stage cooling process and a multi-stage cooling device for coke oven crude gas, which can synchronously realize coke oven crude gas cooling, waste heat recovery and tar fraction separation.
The technical scheme adopted by the invention for solving the problems is as follows:
the utility model provides a multistage cooling device of coke oven raw gas, it is main including the coke oven carbonization chamber, the one-level heat exchanger, the one-level flash tank, the second grade heat exchanger, the second grade flash tank, tertiary heat exchanger, tertiary flash tank, the primary cooler, wherein, the raw gas export of coke oven carbonization chamber links to each other with the raw gas entry of one-level heat exchanger, the raw gas export of one-level heat exchanger links to each other with the feed inlet of one-level flash tank, the raw gas export of one-level flash tank top links to each other with the raw gas entry of second grade heat exchanger, the raw gas export of second grade heat exchanger links to each other with the raw gas entry of tertiary heat exchanger, the raw gas export of tertiary heat exchanger links to each other with the feed inlet of tertiary flash tank, tertiary flash tank top links to each other with.
Furthermore, an inlet and a steam outlet of the deoxygenated water are respectively arranged on the first-stage heat exchanger, the second-stage heat exchanger and the third-stage heat exchanger.
Furthermore, the deoxygenated water flow control valves are mounted at the deoxygenated water inlets of the first-stage heat exchanger, the second-stage heat exchanger and the third-stage heat exchanger. Furthermore, the system also comprises three temperature display controllers for controlling flow regulation, and two ends of each temperature display controller for controlling flow regulation are respectively connected with a deoxygenated water flow control valve and a raw coke oven gas outlet at a deoxygenated water inlet of the same heat exchanger.
The invention also provides a multistage cooling process of the coke oven raw gas, which is to cool the raw gas from 650-750 ℃ to 80-90 ℃, recover the waste heat of the gas to generate high-pressure, medium-pressure and low-pressure steam, and separate high-temperature, medium-temperature and low-temperature fractions of tar at the same time, and comprises the following specific operation steps:
(1) cooling high-temperature raw gas at 650-750 ℃ from a coke oven carbonization chamber by a primary heat exchanger, cooling the raw gas to 275-285 ℃, performing gas-liquid separation by a primary flash tank, separating high-temperature fractions at the bottom, and leading the raw gas separated at the top to a secondary heat exchanger;
(2) cooling the raw gas from the first-stage flash tank through a second-stage heat exchanger, cooling the raw gas to 165-175 ℃, performing gas-liquid separation through the second-stage flash tank, separating medium-temperature fractions at the bottom, and leading the raw gas separated at the top to a third-stage heat exchanger;
(3) and cooling the raw gas from the secondary flash tank through a tertiary heat exchanger, cooling the raw gas to 80-90 ℃, performing gas-liquid separation through the tertiary flash tank, separating low-temperature fractions at the bottom, cooling the raw gas separated at the top to a primary cooler, and cooling to 25-35 ℃ before sending to the subsequent process.
According to the scheme, the steam is generated in the primary heat exchanger, the secondary heat exchanger and the tertiary heat exchanger through the deoxygenated water of 3.5MPa, 1.0MPa and 0.35MPa respectively to recover the heat of the raw coke oven gas.
According to the scheme, the flow of the deoxygenated water which is respectively introduced into the primary heat exchanger, the secondary heat exchanger and the tertiary heat exchanger is introduced, the temperature of the raw gas at the outlet of the primary heat exchanger is controlled to be 275-285 ℃, the temperature of the raw gas at the outlet of the secondary heat exchanger is controlled to be 165-175 ℃, and the temperature of the raw gas at the outlet of the tertiary heat exchanger is controlled to be 80-90 ℃.
According to the scheme, high-temperature fractions (asphalt and anthracene oil fractions), medium-temperature fractions (wash oil, naphthalene oil and phenol oil fractions) and low-temperature fractions (light oil fractions and water) are respectively separated from the bottom of the multi-stage flash tank.
Compared with the prior art, the invention has the beneficial effects that: the coke oven raw gas is cooled from 650-750 ℃ to 80-90 ℃ by adopting multi-section grading cooling, high-pressure steam, medium-pressure steam and low-pressure steam are generated, and a tar high-temperature fraction, a medium-temperature fraction and a light oil fraction are separated. The invention has the following advantages: (1) the waste heat of the raw gas is fully recovered; (2) the crude separation of fractions in the raw gas is realized; (3) the multistage condensation temperature can be regulated and controlled, and the disadvantages that the heat of high-temperature raw coke oven gas is not recovered and a large amount of circulating ammonia water is consumed in the prior art are overcome.
Drawings
FIG. 1 is a multi-stage cooling process and an apparatus for crude gas of a coke oven according to the present invention. In the figure, 1-coke oven carbonization chamber, 2-first-stage heat exchanger, 3-first-stage flash tank, 4-second-stage heat exchanger, 5-second-stage flash tank, 6-third-stage heat exchanger, 7-third-stage flash tank, 8-primary cooler and 9-temperature display controller for controlling flow regulation.
Detailed Description
For a better understanding of the invention, the contents of the invention will be further elucidated with reference to the drawings and examples, but the invention is not limited to the following examples.
As shown in figure 1, the multi-stage cooling device for the coke oven crude gas comprises a coke oven carbonization chamber 1, a first-stage heat exchanger 2, a first-stage flash tank 3, a second-stage heat exchanger 4, a second-stage flash tank 5, a third-stage heat exchanger 6, a third-stage flash tank 7 and a primary cooler 8, wherein a crude gas outlet of the coke oven carbonization chamber 1 is connected with a crude gas inlet of the first-stage heat exchanger 2, a crude gas outlet of the first-stage heat exchanger 2 is connected with a feed inlet of the first-stage flash tank 3, the top of the first-stage flash tank 3 is connected with a crude gas inlet of the second-stage heat exchanger 4, a crude gas outlet of the second-stage heat exchanger 4 is connected with a feed inlet of the second-stage flash tank 5, the top of the second-stage flash tank 5 is connected with a crude gas inlet of the third-stage heat exchanger.
Further, an inlet and a steam outlet for deoxygenated water are respectively formed on the primary heat exchanger 2, the secondary heat exchanger 4 and the tertiary heat exchanger 6; and the deoxygenated water flow control valves are respectively arranged at the deoxygenated water inlets of the primary heat exchanger 2, the secondary heat exchanger 4 and the tertiary heat exchanger 6, and a temperature display controller 9 for controlling flow regulation is respectively arranged between the deoxygenated water flow control valve at the deoxygenated water inlet of the same heat exchanger and the raw coke oven gas outlet.
Examples
Taking 80 ten thousand tons/year coke plant as an example, the device is adopted to carry out a multistage cooling process on raw coke gas, and the specific operation steps are as follows:
(1) cooling high-temperature raw gas at 650-750 ℃ from a coke oven carbonization chamber 1 by a primary heat exchanger 2, cooling the raw gas to 275-285 ℃, performing gas-liquid separation by a primary flash tank 3, separating high-temperature fractions at the bottom, and leading the raw gas separated at the top to a secondary heat exchanger 4;
(2) cooling the raw gas from the primary flash tank 3 through a secondary heat exchanger 4, cooling the raw gas to 165-175 ℃, performing gas-liquid separation through a secondary flash tank 5, separating medium-temperature fractions at the bottom, and leading the raw gas separated at the top to a tertiary heat exchanger 6;
(3) and cooling the raw gas from the secondary flash tank 5 by the tertiary heat exchanger 6, cooling the raw gas to 80-90 ℃, performing gas-liquid separation by the tertiary flash tank 7, separating light oil fractions at the bottom, cooling the raw gas separated at the top to a primary cooler 8, cooling to 25-35 ℃, and conveying to the subsequent process.
The main operational data involved in the multi-stage cooling process in the examples are shown in table 1.
TABLE 1 multistage Cooling Process operating data
Comparative example
Taking 80 ten thousand tons/year coke-oven plant as an example, the existing coke oven crude gas cooling process is adopted, and the specific operation steps are as follows:
(1) strongly spraying 650-750 ℃ high-temperature raw gas from a coke oven carbonization chamber 1 in a gas collecting pipe and a bridge pipe by using circulating ammonia water with the pressure of 0.25-0.3 MPa and the temperature of 72-78 ℃ through a spray head, and cooling the gas to 82-86 ℃;
(2) cooling the mixture to 25-35 ℃ in a primary cooler, and then conveying the mixture to the subsequent process.
The main operating data referred to in the comparative example are shown in table 2.
Table 2 prior art operating data
Initial temperature of raw gas
|
680℃
|
Initial pressure of raw gas
|
0.1MPa
|
Flow rate of raw gas
|
48518.2Nm3/h
|
Temperature of circulating ammonia water
|
75℃
|
Pressure of circulating ammonia water
|
272.5kPa
|
Flow rate of circulating ammonia water
|
457990.86kg/h
|
Ammonia content (wt%) of circulating ammonia water
|
0.3% |
Through simulation calculation, the raw gas and the quality composition of each fraction of the prior art adopted in the comparative example and the multistage cooling process adopted in the embodiment of the invention are shown in the table 3.
TABLE 3 crude gas and quality composition of each fraction
Note: with bitumen composition based on true boiling distillation data and API gravity, TBP stands for true boiling
In the embodiment, compared with the prior art, after the multistage cooling process is adopted, 2287.3 tons of steam with the pressure of 3.5MPa, 556.3 tons of steam with the pressure of 1.0MPa and 435.7 tons of steam with the pressure of 0.35MPa can be generated for each ten thousand tons of coal processed.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that those skilled in the art can make several modifications and variations without departing from the inventive concept of the present invention, and these modifications and variations are all within the scope of the present invention.