Coke oven raw gas high-temperature purification and waste heat gradient utilization method and system

Abstract

The invention discloses a coke oven raw gas high-temperature purification and waste heat gradient utilization method and system, and relates to the field of coke oven raw gas treatment.The method comprises the steps that first-time heat recovery is conducted on raw gas, the temperature of the raw gas is controlled to be reduced to a first temperature threshold value, and first-time cooled raw gas is obtained; performing fine dust removal, and controlling the temperature of the raw gas after dust removal to be within a second temperature threshold value; performing secondary heat recovery, and controlling the temperature of the raw gas subjected to dust removal to be cooled to a third temperature threshold value to obtain the raw gas subjected to secondary cooling and liquid tar subjected to primary condensation; cooling the secondarily cooled raw coke oven gas to a fourth temperature threshold by spraying circulating ammonia water to obtain tertiary cooled raw coke oven gas and a mixed solution of secondarily condensed liquid tar and circulating ammonia water; and separating tar and ammonia water. According to the invention, the coke oven raw gas can be subjected to high-temperature purification, the waste heat of the raw gas can be subjected to gradient utilization, and the heat value utilization efficiency of the raw gas is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of coke oven raw gas treatment, and in particular to a method and system for high-temperature purification of coke oven raw gas and waste heat gradient utilization. Background Art

[0002] The coke oven body consists of three main parts: the carbonization chamber, the combustion chamber, and the heat storage chamber. The combustion chamber and the carbonization chamber are arranged alternately. Each carbonization chamber must go through a cyclic production process of coal loading, high-temperature carbonization, coke pushing, coke interception and coke quenching during the coking process. The main production stage of the coal in the carbonization chamber is the high-temperature carbonization stage of coal. In this stage, the carbonization chamber will produce a by-product of raw coal gas, and the temperature and flow of the raw coal gas will also fluctuate with the different stages of high-temperature carbonization. In the last 1 / 3 of the coking cycle, raw coal gas is not produced, so the temperature of the riser used to transmit raw coal gas will be greatly reduced, resulting in a large fluctuation in the temperature of the riser. In the entire coking production, the coking production process needs to be carried out alternately according to the coke pushing sequence, so that the aggregated raw coal gas output and temperature are in a dynamic equilibrium state.

[0003] In the actual production process, the temperature of the raw gas produced by the coke oven is about 650-850℃ when it enters the riser from the carbonization chamber. The heat it contains accounts for 36% of the total heat expenditure of the coke oven and about 51% of the unrecovered waste heat resources of the coke oven, which has a high value and potential for waste heat recovery.

[0004] The raw coal gas produced in the coking process is the gas produced by carbonization of coal in the carbonization chamber. Its main components include water vapor, tar vapor, crude benzene, ammonia, hydrogen sulfide and cyanide, etc. The dusty tar in the raw coal gas begins to condense below the tar phase transition temperature to form a high-viscosity asphalt-like substance, which will cause coking of equipment and pipelines.

[0005] In the prior art, the mainstream treatment process for raw coal gas is to spray circulating ammonia water in the bridge pipe to directly cool the raw coal gas, and then gather the raw coal gas to the gas collecting pipe after the temperature of the raw coal gas is reduced to 80-85°C, so that most of the tar gas is condensed and precipitated, and then flows with the ammonia water to the tar-ammonia separation tank for separation together with the dust, and the circulating ammonia water, tar and tar residue are obtained. This treatment method wastes a lot of the calorific value of the raw coal gas.

[0006] Due to the limitation of condensation of tar gas in coke oven raw gas, the waste heat recovery technology of coke oven raw gas is currently limited to the utilization of waste heat of raw gas above the tar phase change temperature, and the utilization efficiency of the calorific value of raw gas is low. Summary of the invention

[0007] The present invention provides a method and system for high-temperature purification of raw gas from a coke oven and utilization of residual heat gradient, which can solve the problem of low utilization efficiency of the calorific value of raw gas from a coke oven in the prior art while purifying the raw gas at high temperature.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] In a first aspect, the present invention provides a method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient, the method comprising:

[0010] The first waste heat recovery device recovers the raw gas collected from the coke oven carbonization chamber for the first time, and controls the temperature of the raw gas to be cooled to a first temperature threshold, thereby obtaining the raw gas with the first cooling; the first temperature threshold is greater than the tar phase change temperature;

[0011] The raw gas subjected to the first cooling is finely dedusted by a high-temperature electrostatic precipitator, and the temperature of the raw gas after dedusting is controlled within a second temperature threshold; the second temperature threshold is less than the first temperature threshold and greater than the tar phase change temperature;

[0012] The second waste heat recovery device performs a second heat recovery on the dedusted raw gas, and controls the temperature of the dedusted raw gas to be cooled to a third temperature threshold, thereby obtaining the second cooled raw gas and the first condensed liquid tar; the third temperature threshold is greater than the acid dew point of the raw gas;

[0013] The raw coal gas subjected to the second cooling is cooled to a fourth temperature threshold by spraying the circulating ammonia water, thereby obtaining the raw coal gas subjected to the third cooling, and a mixture of the liquid tar condensed for the second time and the circulating ammonia water; the fourth temperature threshold is less than the steam vaporization point;

[0014] The liquid tar condensed for the first time and the mixed liquid of the liquid tar condensed for the second time and the circulating ammonia water are subjected to a tar-ammonia water separation operation to obtain pure tar and separated circulating ammonia water.

[0015] In a possible implementation, the first temperature threshold is 500-520°C.

[0016] In a possible implementation, the third temperature threshold is 140-160°C.

[0017] In a possible implementation, each carbonization chamber of the coke oven is connected to a riser, and one end of the plurality of risers away from the carbonization chamber is connected to a high-temperature gas collecting pipe, and the first waste heat recovery device is a high-temperature heat exchanger; the first waste heat recovery device is used to recover the raw gas collected from the coke oven carbonization chamber for the first time, specifically:

[0018] After the riser collects the raw coal gas generated by the plurality of carbonization chambers into the gas collecting pipe, the high-temperature heat exchanger performs the first heat recovery on the raw coal gas.

[0019] In a possible implementation, each carbonization chamber of the coke oven is connected to a riser, and one end of the plurality of risers away from the carbonization chamber is connected to a high-temperature gas collecting pipe, and the first waste heat recovery device includes a riser heat exchanger provided on each of the risers; the first waste heat recovery device performs a first heat recovery on the raw gas collected from the carbonization chamber of the coke oven, specifically:

[0020] Before the riser collects the raw coal gas generated by the plurality of carbonization chambers into the gas collecting pipe, the raw coal gas is subjected to a first heat recovery through the plurality of riser heat exchangers.

[0021] In a possible implementation, the first waste heat recovery device generates high-grade saturated steam during the first heat recovery process; and the second waste heat recovery device generates low-grade saturated steam during the second heat recovery process.

[0022] In a possible implementation, the first waste heat recovery device is connected to the second waste heat recovery device to jointly produce saturated steam.

[0023] In a possible implementation, the method further includes:

[0024] The low-grade saturated steam generated by the second waste heat recovery device is input into the first waste heat recovery device for heating to obtain high-grade superheated steam.

[0025] In a possible implementation, a plurality of carbonization chambers are distributed in a straight line in the coke oven, and each of the carbonization chambers is connected to a riser; the first waste heat recovery device includes a first recoverer and a second recoverer; and the method further includes:

[0026] The plurality of riser tubes are divided into a first group of tubes and a second group of tubes according to the positions of the riser tubes; the first recovery device is used to perform a first heat recovery on the first group of tubes and generate high-grade saturated steam during the first heat recovery process; the second waste heat recovery device is used to perform a second heat recovery and generate low-grade saturated steam during the second heat recovery process;

[0027] The low-grade saturated steam is input into the second recovery vessel for heating to obtain high-grade superheated steam.

[0028] In a second aspect, the present invention provides a system for high-temperature purification of raw gas from a coke oven and utilization of residual heat gradient, comprising:

[0029] The first waste heat recovery device is used to recover the first heat of the raw gas collected from the coke oven carbonization chamber, and control the temperature of the raw gas to cool to a first temperature threshold to obtain the raw gas with the first cooling; the first temperature threshold is greater than the tar phase change temperature;

[0030] a high-temperature electrostatic precipitator, connected to the first waste heat recovery device, for finely removing dust from the raw coal gas after the first cooling, and controlling the temperature of the raw coal gas after the dust removal to be within a second temperature threshold; the second temperature threshold is less than the first temperature threshold and greater than the tar phase change temperature;

[0031] a second waste heat recovery device, connected to the high-temperature electrostatic precipitator, for performing a second heat recovery on the dedusted raw gas, and controlling the temperature of the dedusted raw gas to cool to a third temperature threshold, to obtain the second cooled raw gas and the first condensed liquid tar; the third temperature threshold is greater than the acid dew point of the raw gas;

[0032] an ammonia spraying cooling device, connected to the second waste heat recovery device, for spraying circulating ammonia water to cool the raw coal gas subjected to the second cooling to a fourth temperature threshold; the fourth temperature threshold is less than the steam gasification point;

[0033] a gas-liquid separation device, connected to the ammonia spray cooling device, for performing gas-liquid separation on the second cooled raw gas after being treated by the ammonia spray cooling device, to obtain the third cooled raw gas, and a mixture of the second condensed liquid tar and the circulating ammonia water;

[0034] The tar-ammonia water separation device is connected to the second waste heat recovery device and the gas-liquid separation device, and is used to perform tar-ammonia water separation operations on the liquid tar condensed for the first time, and the mixed liquid of the liquid tar condensed for the second time and the circulating ammonia water to obtain pure tar and separated circulating ammonia water.

[0035] The method and system for high-temperature purification of raw coke oven gas and gradient utilization of waste heat provided by the embodiment of the present invention utilizes the waste heat of the raw coke oven gas in a gradient manner during the purification process of the raw coke oven gas, fully recovers the waste heat of the raw coke gas, and effectively improves the calorific value utilization efficiency of the raw coke gas.

[0036] The present invention recovers the heat of the raw gas for the first time before the raw gas is finely purified, and recovers the heat of the raw gas for the second time after the fine purification, thereby effectively improving the utilization range of the waste heat temperature of the raw gas.

[0037] In the process of utilizing the residual heat gradient of the raw coal gas, the present invention also performs fine dust removal on the dust in the raw coal gas, so that the dust content of the collected pure tar is lower, and the quality of the recovered tar is effectively improved.

[0038] When the present invention utilizes circulating ammonia water to cool the raw coal gas, it is only necessary to cool the raw coal gas of the second cooling to the fourth temperature threshold, wherein the temperature of the raw coal gas of the second cooling is within the range of the third temperature threshold, the third temperature threshold is greater than the acid dew point of the raw coal gas, and the fourth temperature threshold is less than the steam gasification point; compared with the prior art in which circulating ammonia water directly cools the raw coal gas collected from the carbonization chamber to below the steam gasification point, the present invention can effectively reduce the consumption of circulating ammonia water resources and electric power resources.

[0039] The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient of the present invention can ensure the coking of coke ovens and coke production while overcoming the effects of resistance changes on the coking process, tar clogging of pipelines and process changes, thereby ensuring the normal operation of the coking process.

[0040] The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient of the present invention can also overcome the problems of water leakage, coking corrosion and graphite formation of the riser heat exchanger caused by large temperature fluctuations in the coking process.

[0041] The method for high-temperature purification of raw coke gas and waste heat gradient utilization of the present invention can also reduce the operating difficulty of each device in the system for high-temperature purification of raw coke gas and waste heat gradient utilization of the coke oven, reduce the difficulty and requirements of high-temperature resistance, corrosion resistance, high thermal conductivity and thermal stress resistance required for equipment material selection, extend the coking cycle, shorten the decoking time, and ensure stable operation of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flowchart of the steps of a method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient provided by an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the system structure in a system for high-temperature purification of raw coke oven gas and waste heat gradient utilization provided by an embodiment of the present invention when the first waste heat recovery device is a high-temperature heat exchanger and the second waste heat recovery device is a low-temperature heat exchanger;

[0044] Figure 3 A schematic diagram of the system structure in a system for high-temperature purification of raw coke oven gas and waste heat gradient utilization provided by an embodiment of the present invention when the first waste heat recovery device is a riser heat exchanger and the second waste heat recovery device is a low-temperature heat exchanger;

[0045] Figure 4 A schematic diagram of the system structure for generating saturated steam in a system for high-temperature purification of raw coke oven gas and waste heat gradient utilization provided by an embodiment of the present invention when the first waste heat recovery device is a high-temperature heat exchanger, the second waste heat recovery device is a low-temperature heat exchanger, and the high-temperature heat exchanger and the low-temperature heat exchanger share a set of water circulation system and steam drum;

[0046] Figure 5A schematic diagram of the system structure for generating saturated steam in a system for high-temperature purification of raw coke oven gas and waste heat gradient utilization provided by an embodiment of the present invention when the first waste heat recovery device is a riser heat exchanger, the second waste heat recovery device is a low-temperature heat exchanger, and the high-temperature heat exchanger and the low-temperature heat exchanger share a set of water circulation system and steam drum;

[0047] Figure 6 A schematic diagram of the system structure in which a first waste heat recovery device is a high-temperature heat exchanger, a second waste heat recovery device is a low-temperature heat exchanger, and the high-temperature heat exchanger and the low-temperature heat exchanger share only one set of water circulation system in a system for high-temperature purification of raw gas from a coke oven and a waste heat gradient utilization provided by an embodiment of the present invention, and steam drums are respectively provided to generate high-grade saturated steam and low-grade saturated steam;

[0048] Figure 7 A schematic diagram of the system structure in which the first waste heat recovery device in a coke oven raw gas high-temperature purification and waste heat gradient utilization system provided by an embodiment of the present invention is a riser heat exchanger, the second waste heat recovery device is a low-temperature heat exchanger, and the high-temperature heat exchanger and the low-temperature heat exchanger only share a set of water circulation system, and steam drums are respectively provided to generate high-grade saturated steam and low-grade saturated steam;

[0049] Figure 8 A schematic diagram of the system structure when the first waste heat recovery device is a high-temperature heat exchanger in a system for high-temperature purification of raw coke oven gas and waste heat gradient utilization provided by an embodiment of the present invention, and the generated saturated steam is passed into the high-temperature heat exchanger for reheating to generate high-grade superheated steam;

[0050] Fig. 9 A schematic diagram of the system structure when the first waste heat recovery device is a riser heat exchanger in a system for high-temperature purification of raw coke oven gas and waste heat gradient utilization provided by an embodiment of the present invention, and the generated saturated steam is passed into a high-temperature heat exchanger for reheating to generate high-grade superheated steam;

[0051] Fig.10 A schematic diagram of the system structure in which a coke oven raw gas high-temperature purification and waste heat gradient utilization system is provided in an embodiment of the present invention, in which when the first waste heat recovery device is a riser heat exchanger, high-grade saturated steam is generated by the first recovery device and high-grade superheated steam is generated by the second recovery device.

[0052] Reference numerals and descriptions:

[0053] 1. Carbonization chamber; 2. Riser; 3. High-temperature gas collecting pipe; 4. High-temperature heat exchanger; 5. High-temperature electrostatic precipitator; 6. Riser heat exchanger; 61. First recovery device; 62. Second recovery device; 7. Low-temperature heat exchanger; 8. Ammonia injection gas collecting pipe; 9. Gas-liquid separator; 10. Tar-ammonia water separation device; 11. Deaerator; 12. Feedwater pump; 13. Circulation pump; 14. Steam drum; 15. Valve. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "multiple" means two or more. In addition, the use of "based on" or "according to" means openness and inclusiveness, because the process, steps, calculations or other actions "based on" or "according to" one or more of the conditions or values ​​may be based on additional conditions or values ​​beyond the described values ​​in practice.

[0056] In the prior art, due to the limitation of condensation and coking of tar gas in coke oven raw gas, the technology for recovering and utilizing waste heat from raw gas in coke oven is limited to utilizing waste heat from raw gas above the tar phase change temperature. The specific utilization methods include jacketed direct recovery of waste heat from raw gas, heat pipe direct recovery of waste heat from raw gas, centralized direct recovery of waste heat from raw gas, and semiconductor temperature difference power generation. In the prior art, after recovering and utilizing waste heat from raw gas above the tar phase change temperature, the temperature of the raw gas is still reduced to 80-85°C by spraying with circulating ammonia water, so as to pass the temperature range of the tar gas phase change in the tar raw gas, and prevent the tar from condensing and coking to cause pipeline blockage.

[0057] The inventors have found through research that if the waste heat of raw coal gas below the tar phase change temperature is to be utilized, then it is necessary to overcome the problems caused by tar condensation and coking. Specifically, the tar condensation process is a gas-liquid phase change process, and theoretically it should be a liquid mixture with a certain fluidity. However, since raw coal gas contains impurities such as dust, the asphalt material formed by the condensed tar and dust is more viscous, which will cause pipeline blockage when transported in the pipeline. Therefore, in order to utilize the waste heat of raw coal gas below the tar phase change temperature, it is necessary to remove impurities such as dust in the raw coal gas before the tar in the raw coal gas changes phase.

[0058] In the coke oven raw gas treatment process, since the tar in the raw gas is a mixture of multiple substances, its components are complex, and the precipitation temperatures of each component are different. Specifically, a small amount of tar in the coal tar below 500°C will undergo phase change precipitation, the amount of tar precipitation in the coal tar below 450°C will increase, and a large amount of tar in the coal tar below 450°C will precipitate. In this application scenario, the inventors have found that three tar recovery schemes can be adopted. The first scheme is to directly spray circulating ammonia water to cool the raw gas, remove dust and recover tar. The second scheme is: waste heat utilization technology of raw gas above 500°C. The third scheme is: first perform high-temperature dust removal on the raw gas collected from the carbonization chamber, and then utilize the waste heat.

[0059] The first solution has the following problems:

[0060] This method directly uses the method of spraying circulating ammonia water to cool the raw gas collected from the carbonization chamber, and does not utilize the waste heat of the raw gas, which wastes the heat carried by the raw gas. That is, it not only wastes the thermal energy of the raw gas, but also increases the consumption of water resources and electricity.

[0061] The tar collected by this method has a large dust content. If it is directly hydrogenated, the activity of the catalyst will be greatly reduced, and even the catalyst will be deactivated. The high dust content of tar reduces the added value of tar as a fuel or raw material, and increases the difficulty and cost of subsequent treatment of tar. The coal tar produced by the existing coking production process is mostly transported by tar delivery, which has low tar quality and low economic benefits.

[0062] The second solution has the following problems:

[0063] The difficulty in recycling waste heat from waste gas is that it contains coal tar and a large amount of fine dust. The tar in the waste gas begins to condense below 500°C, and the condensed liquid tar mixes with the dust to form a high-viscosity paste-like substance, which is very easy to adhere to the inner wall of the heat exchanger, which will reduce the heat exchange effect of the heat exchanger in a short period of time, causing pipeline blockage, and directly affecting the operation of the waste gas treatment system. Therefore, this method can only recycle part of the waste heat of waste gas above 500°C, and this part of heat accounts for about 1 / 3 of the entire waste heat of waste gas. For waste heat from waste gas below 500°C, a large amount of circulating ammonia water needs to be sprayed for cooling. Compared with the first solution, this method can recycle waste heat from waste gas above 500°C, slightly reducing the amount of circulating ammonia water and electricity consumption.

[0064] Regarding the waste heat utilization scheme at the riser of the carbonization chamber, due to the large temperature fluctuation range of the riser in the coking production process, the temperature in the carbonization chamber can drop to a minimum of about 200°C and a maximum of 1000°C in each production cycle. When the temperature of the raw coal gas is lower than 500°C, the tar gas will phase change into liquid tar, and the mixture of condensed coked tar and dust will decompose to form graphite when heated again. Therefore, this scheme has problems of water leakage, coking corrosion and graphite formation when utilizing waste heat at the riser.

[0065] In this scheme, the temperature at the riser needs to be maintained above the dew point of the tar vapor, and the waste heat recovery equipment at the riser needs to have the characteristics of high temperature resistance, corrosion resistance, high thermal conductivity and thermal stress resistance. Therefore, the process operation of this scheme is difficult.

[0066] This solution does not improve the quality of tar, and the dust content of the tar obtained by this solution is the same as that of the tar obtained by the first solution.

[0067] The third solution has the following problems:

[0068] Since coking production will produce coke and raw gas, for production safety, it is necessary to maintain positive pressure in the carbonization chamber of the coke oven during the production cycle. Therefore, the riser connected to the carbonization chamber also needs to operate at positive pressure. In this application scenario, it is difficult for high-temperature dust removal equipment used to remove dust from raw gas to use filtering dust removal equipment with high resistance, such as: particle bed filtering dust removal, high-temperature ceramic filter cartridge filtering dust removal, and high-temperature metal filter cartridge filtering dust removal. At the same time, tar coking will also cause the resistance of the filtering dust removal equipment to increase again, which is more detrimental to the production process. In the prior art, high-temperature dust removal usually uses a high-temperature cyclone dust collector, but this equipment can only perform coarse dust removal on raw gas, and the dust removal efficiency is low.

[0069] The temperature of the raw coal gas collected from the carbonization chamber is generally 650-850℃, that is, the inlet temperature of the high-temperature cyclone dust collector is 650-850℃, which causes the raw coal temperature after dust removal to be too high. Therefore, the subsequent raw coal gas transmission and processing equipment also needs to use high temperature resistant materials. The operating temperature of the whole system is high and the flow rate of the raw coal gas is fast, resulting in greater equipment wear.

[0070] The dust removal principle of the high-temperature cyclone dust collector adopted in the production process of this scheme is to use the centrifugal force generated by high-speed rotation to separate gas and solid. If the cyclone dust collector is to work, it is necessary to increase the flow rate of the process section and increase the fan pressure. In this way, it is difficult to ensure that the carbonization chamber of the coking chamber and the riser connected to it and other equipment maintain positive pressure operation, resulting in the inability to meet the requirements of coking in the coke oven.

[0071] The high-temperature cyclone dust collector in this scheme can only perform rough dust removal on the raw coal gas, resulting in the viscosity of the tar condensate in the raw coal gas after dust removal still being relatively high during the subsequent waste heat utilization. In this case, in order to reduce the condensation of the condensate, extend the coking cycle, and shorten the decoking time, the temperature of the waste heat utilization outlet needs to be set higher, about 350°C.

[0072] Compared with the second option, although the waste heat utilization technology adopted in this option has expanded the temperature range of waste heat utilization of raw coal gas, some waste heat will still be wasted; at the same time, the second option subsequently adopted the method of spraying circulating ammonia water to cool down to pass the temperature range of tar phase change. Therefore, the second option does not have a solution for waste heat utilization below 500°C, and the existing process blockage problem will be far less than the waste heat utilization solution of cooling down to about 350°C in this option.

[0073] That is to say, compared with the second option, although the third option relatively expands the utilization range of the waste heat temperature of the raw coal gas, it will also increase the severity of equipment blockage.

[0074] In order to solve the problem of low calorific value utilization efficiency of coke oven raw gas in the prior art while purifying the raw gas at high temperature, an embodiment of the present invention provides a method and system for high temperature purification of coke oven raw gas and waste heat gradient utilization.

[0075] like Figure 1 As shown, in the first aspect, an embodiment of the present invention provides a method for high-temperature purification of raw gas from a coke oven and utilization of residual heat gradient, the method comprising:

[0076] Step 101: recovering the raw gas collected from the coke oven carbonization chamber for the first time through a first waste heat recovery device, and controlling the temperature of the raw gas to cool to a first temperature threshold, thereby obtaining the raw gas with the first cooling.

[0077] The first temperature threshold is greater than the tar phase transition temperature.

[0078] The temperature of the raw gas collected from the coke oven carbonization chamber is generally between 650 and 850°C. The tar phase transition temperature refers to the critical temperature at which tar condenses from gas to liquid. During the first heat recovery, it is necessary to ensure that the temperature of the raw gas is maintained above the tar phase transition temperature to prevent the tar gas in the raw gas from condensing into liquid and forming a high-viscosity paste with the dust in the raw gas.

[0079] Preferably, the first temperature threshold is 500-520°C.

[0080] In an embodiment of the present invention, the temperature of the raw gas after the first heat recovery treatment is controlled to be between 500 and 520°C, which can ensure that the tar in the raw gas after the first cooling is still in a gaseous state, and can ensure that the temperature of the raw gas collected from the coke oven carbonization chamber is fully utilized, thereby improving the recovery efficiency of the waste heat of the raw gas above 500°C.

[0081] Step 102: finely remove dust from the raw gas that has been cooled for the first time by a high-temperature electrostatic precipitator, and control the temperature of the raw gas after the dust removal to be within a second temperature threshold.

[0082] The second temperature threshold is smaller than the first temperature threshold and larger than the tar phase transition temperature.

[0083] Specifically, compared with the high-temperature cyclone dust collector, the high-temperature electrostatic precipitator used in the present invention can perform fine dust removal on raw coal gas with higher dust removal efficiency, thereby making the dust content of the tar after condensation smaller and the quality of the obtained tar higher.

[0084] The second temperature threshold is between 470 and 500°C, that is, the temperature at the outlet of the high-temperature electrostatic precipitator is maintained between 470 and 500°C. In this temperature range, the phase change of tar is relatively small, which can ensure the efficient and stable operation of the high-temperature electrostatic precipitator. Even if a small amount of tar condenses and precipitates, it will not affect the normal operation of the high-temperature electrostatic precipitator and extend the service life of the high-temperature electrostatic precipitator.

[0085] Step 103, performing a second heat recovery on the dedusted raw gas through a second waste heat recovery device, and controlling the temperature of the dedusted raw gas to cool to a third temperature threshold, thereby obtaining the second cooled raw gas and the first condensed liquid tar.

[0086] Among them, the third temperature threshold is greater than the acid dew point of the raw coal gas.

[0087] Specifically, the acid dew point of raw gas refers to the temperature at which the surface evaporation rate and surface condensation rate of acidic gas in raw gas reach equilibrium. When the temperature is lower than the acid dew point of raw gas, the acidic gas (such as sulfuric acid vapor) in the raw gas will condense on the surface of the metal heating surface to form acid droplets, causing corrosion of the metal heating surface.

[0088] During the second heat recovery of the raw gas after dust removal through the second waste heat recovery device, the temperature of the raw gas is controlled to be maintained within the third temperature threshold range, which can effectively prevent the acidic gas in the raw gas from condensing on the metal surface due to heat, thereby causing corrosion to the subsequent transmission system, thereby extending the service life of the subsequent transmission system.

[0089] Preferably, the third temperature threshold is 140-160°C.

[0090] In the embodiment of the present invention, the temperature of the raw gas after the second heat recovery is controlled between 140 and 160°C, which can not only ensure that the acidic gas in the raw gas cooled for the second time is still in a gaseous state, but also ensure that the temperature of the purified raw gas below 500°C is fully utilized, thereby improving the recovery and utilization efficiency of the waste heat of the raw gas below 500°C.

[0091] Step 104, cooling the raw coal gas cooled for the second time to a fourth temperature threshold by spraying circulating ammonia water, thereby obtaining the raw coal gas cooled for the third time and a mixture of the liquid tar condensed for the second time and the circulating ammonia water.

[0092] The fourth temperature threshold is less than the steam vaporization point.

[0093] Specifically, the vaporization point refers to the temperature point at which liquid is converted into vapor, usually the boiling point. In this embodiment, the fourth temperature threshold is 80-85°C.

[0094] Spraying recycled ammonia water can not only cool down the raw gas after the second cooling, but also neutralize the acid gas in the raw gas to prevent the acid gas from condensing and corroding the metal. One reason for controlling the temperature of the raw gas below the steam vaporization point is to avoid the vaporization of the recycled ammonia water, and another reason is to meet the process temperature requirements of the subsequent raw gas treatment.

[0095] Step 105 , performing a tar-ammonia separation operation on the liquid tar condensed for the first time and the mixed liquid of the liquid tar condensed for the second time and the circulating ammonia water to obtain pure tar and separated circulating ammonia water.

[0096] In this embodiment, the raw coal gas cooled for the third time enters the raw coal gas treatment process, which specifically includes condensation and blowing sections, etc.; the liquid tar condensed for the first time, and the mixture of liquid tar and circulating ammonia water condensed for the second time are passed into the tar-ammonia water separation tank for further separation and treatment to obtain pure tar, circulating ammonia water and tar residue.

[0097] Specifically, in the present invention, there are no specific limitations on the specific structures of the first waste heat recovery device and the second waste heat recovery device, as well as the waste heat utilization method. Commonly used waste heat boiler forms can achieve the functions of the first waste heat recovery device and the second waste heat recovery device of the present invention.

[0098] In the present invention, there is no specific limitation on the removal of dust obtained by the high-temperature electrostatic precipitator and the secondary utilization of the dust, and conventional transportation, collection and secondary utilization methods all meet the requirements of the present invention.

[0099] In the present invention, the utilization route and method of circulating ammonia water are not specifically limited. This part is an auxiliary supporting process relative to the process flow of the present invention. The present invention assumes that conventional circulating ammonia water supporting equipment and processes meet the requirements of the present invention.

[0100] In the present invention, the specific operation process and operation method of the tar-ammonia water separation operation are not further limited, and the present invention assumes that conventional tar-ammonia water separation operations meet the requirements of the present invention.

[0101] In the present invention, the subsequent treatment process of the raw gas cooled for the third time, i.e., the raw gas cooled to 80-85°C, is not further limited. The treatment process adopts the conventional treatment process of the coking enterprise, and the relevant chemical products and clean coke oven gas can be obtained later. Compared with the prior art, the dust content of the clean coke oven gas obtained by the present invention is also reduced, and the quality is higher.

[0102] Optionally, in one embodiment of the present invention, each carbonization chamber of the coke oven is connected to a riser, and one end of the plurality of risers away from the carbonization chamber is commonly connected to a high-temperature gas collecting pipe, and the first waste heat recovery device is a high-temperature heat exchanger.

[0103] The first waste heat recovery device is used to recover the raw gas collected from the coke oven carbonization chamber for the first time, specifically:

[0104] After the raw coal gas produced by multiple carbonization chambers is collected in the gas collecting pipe by the riser, the raw coal gas is subjected to the first heat recovery through the high-temperature heat exchanger.

[0105] Optionally, in another embodiment of the present invention, each carbonization chamber of the coke oven is connected to a riser, and one end of the multiple risers away from the carbonization chamber is commonly connected to the high-temperature gas collecting pipe, and the first waste heat recovery device includes a riser heat exchanger arranged on each riser.

[0106] The first waste heat recovery device is used to recover the raw gas collected from the coke oven carbonization chamber for the first time, specifically:

[0107] Before the riser collects the raw coal gas produced by multiple carbonization chambers into the gas collecting pipe, the raw coal gas is firstly heat-recovered through multiple riser heat exchangers.

[0108] Optionally, in one embodiment of the present invention, the first waste heat recovery device generates high-grade saturated steam during the first heat recovery process, and the second waste heat recovery device generates low-grade saturated steam during the second heat recovery process.

[0109] Among them, high-grade saturated steam usually refers to saturated steam produced under higher pressure. Under high pressure, water molecules need more energy to escape and become steam, so the steam produced has higher temperature and energy.

[0110] Low-grade saturated steam is the opposite of high-grade saturated steam. Low-grade saturated steam is saturated steam produced at a lower pressure. At low pressure, the energy required for water molecules to escape and become steam is lower, so the steam temperature and energy produced are also lower.

[0111] Saturated steam refers to the steam when the process of liquid turning into steam reaches a state of equilibrium.

[0112] That is, in this embodiment, the first waste heat recovery device recovers the waste heat of the raw gas above 500°C to generate high-grade saturated steam, and the second waste heat recovery device recovers the waste heat of the raw gas below 500°C to generate low-grade saturated steam.

[0113] The use of high-quality saturated steam is of great significance in industrial production. It can heat quickly and evenly, improve product quality and production efficiency. Specifically, it includes: thermal power generation, industrial heating, building heating, cooking and food processing, steam recovery, steam cascade utilization and other fields.

[0114] The utilization of low-grade saturated steam is an important way to save energy, reduce emissions and achieve sustainable development. Specifically, it includes screw expansion engine technology, power generation methods using low-pressure saturated steam, new steam-assisted condensing turbine power generation technology, Xuan Steel's low-pressure saturated steam power generation project, and research and application of low-pressure saturated steam energy-saving recycling.

[0115] Optionally, in another embodiment of the present invention, the first waste heat recovery device is connected to the second waste heat recovery device to jointly produce saturated steam.

[0116] Specifically, in this embodiment, there is no need to subdivide the high-grade saturated steam and the low-grade saturated steam, and only saturated steam needs to be obtained.

[0117] Optionally, in another embodiment of the present invention, the method further includes:

[0118] The low-grade saturated steam generated by the second waste heat recovery device is input into the first waste heat recovery device for heating to obtain high-grade superheated steam.

[0119] Saturated steam means that under a certain pressure, liquid and gas exist in a state of equilibrium at the same time. In this state, the liquid will continue to evaporate, and the gas will continue to condense until the two reach a dynamic equilibrium. At this time, the temperature and pressure of the steam are fixed, which are called saturation temperature and saturation pressure.

[0120] Superheated steam is formed when the temperature exceeds the saturation temperature. In this state, the temperature and pressure of the steam are no longer fixed, but increase with the increase of heat.

[0121] Superheated steam has higher thermal energy and heat capacity, so it is widely used in industry and energy fields.

[0122] Optionally, in another embodiment of the present invention, a plurality of carbonization chambers are distributed at intervals along a straight line in the coke oven, and each carbonization chamber is connected to a riser; and the first waste heat recovery device includes a first recoverer and a second recoverer.

[0123] The method further includes:

[0124] The multiple riser tubes are divided into a first group of tubes and a second group of tubes according to the positions of the riser tubes; the first recovery device is used to perform the first heat recovery on the first group of tubes and generate high-grade saturated steam during the first heat recovery process; the second waste heat recovery device is used to perform the second heat recovery and generate low-grade saturated steam during the second heat recovery process.

[0125] The low-grade saturated steam is input into the second recovery vessel for heating to obtain high-grade superheated steam.

[0126] That is to say, in the embodiment of the present invention, high-grade saturated steam is produced by utilizing the riser heat exchangers corresponding to the riser tubes corresponding to the first 1 to n carbonization chambers of the coke oven; and high-grade superheated steam is produced by utilizing the riser heat exchangers corresponding to the riser tubes corresponding to the nth to last carbonization chambers of the coke oven in cooperation with the second waste heat recovery device.

[0127] Wherein, n is a positive integer.

[0128] In practical applications, the method for high-temperature purification of raw gas from coke ovens and utilization of waste heat gradient of the present invention firstly performs the first heat recovery on the raw gas collected from the carbonization chamber of the coke oven through a first waste heat recovery device. During the first heat recovery process, the temperature of the raw gas is controlled to be maintained above the tar phase transition temperature to avoid condensation and liquefaction of tar in the unpurified raw gas; secondly, fine dust removal is performed on the raw gas after the first heat recovery to remove dust and other impurities in the raw gas. During this process, it is necessary to ensure that the temperature of the raw gas is above the tar phase transition temperature to avoid condensation and liquefaction of tar in the raw gas and blockage of the transmission pipeline; thirdly, the purified raw gas is subjected to a second heat recovery by a second waste heat recovery device. Amount of recovery is carried out. In this process, the temperature of the raw gas is controlled to be maintained above the acid dew point of the raw gas. While obtaining the liquefied tar of the first condensation, the condensation and liquefaction of the acid gas in the raw gas, which may cause corrosion of the transmission pipeline, is avoided. After that, the raw gas after the second heat recovery is sprayed with circulating ammonia water to cool down the raw gas, and the acid gas in the raw gas is neutralized. At the same time, the temperature of the raw gas needs to be controlled to be maintained below the steam gasification to avoid the gasification of ammonia water, and a mixture of the liquid tar condensed for the second time and the circulating ammonia water is obtained. Finally, the liquefied tar condensed for the first time and the mixture of the liquid tar condensed for the second time and the circulating ammonia water are separated to obtain pure tar and separated circulating ammonia water.

[0129] The method and system for high-temperature purification of raw coke oven gas and gradient utilization of waste heat provided by the embodiment of the present invention utilizes the waste heat of the raw coke oven gas in a gradient manner during the purification process of the raw coke oven gas, fully recovers the waste heat of the raw coke gas, and effectively improves the calorific value utilization efficiency of the raw coke gas.

[0130] The present invention recovers the heat of the raw gas for the first time before the raw gas is finely purified, and recovers the heat of the raw gas for the second time after the fine purification, thereby effectively improving the utilization range of the waste heat temperature of the raw gas.

[0131] In the process of utilizing the residual heat gradient of the raw coal gas, the present invention also performs fine dust removal on the dust in the raw coal gas, so that the dust content of the collected pure tar is lower, and the quality of the recovered tar is effectively improved.

[0132] When the present invention utilizes circulating ammonia water to cool the raw coal gas, it is only necessary to cool the raw coal gas of the second cooling to the fourth temperature threshold, wherein the temperature of the raw coal gas of the second cooling is within the range of the third temperature threshold, the third temperature threshold is greater than the acid dew point of the raw coal gas, and the fourth temperature threshold is less than the steam gasification point; compared with the prior art in which circulating ammonia water directly cools the raw coal gas collected from the carbonization chamber to below the steam gasification point, the present invention can effectively reduce the consumption of circulating ammonia water resources and electric power resources.

[0133] The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient of the present invention can ensure the coking of coke ovens and coke production while overcoming the effects of resistance changes on the coking process, tar clogging of pipelines and process changes, thereby ensuring the normal operation of the coking process.

[0134] The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient of the present invention can also overcome the problems of water leakage, coking corrosion and graphite formation of the riser heat exchanger caused by large temperature fluctuations in the coking process.

[0135] The method for high-temperature purification of raw coke gas and waste heat gradient utilization of the present invention can also reduce the operating difficulty of each device in the system for high-temperature purification of raw coke gas and waste heat gradient utilization of the coke oven, reduce the difficulty and requirements of high-temperature resistance, corrosion resistance, high thermal conductivity and thermal stress resistance required for equipment material selection, extend the coking cycle, shorten the decoking time, and ensure stable operation of the process.

[0136] In a second aspect, an embodiment of the present invention further provides a system for high-temperature purification of raw gas from a coke oven and utilization of residual heat gradient, the system comprising:

[0137] The first waste heat recovery device is used to recover the first heat of the raw gas collected from the coke oven carbonization chamber, and control the temperature of the raw gas to cool to a first temperature threshold to obtain the raw gas with the first cooling.

[0138] Wherein, the first temperature threshold is greater than the tar phase transition temperature;

[0139] The high-temperature electrostatic precipitator is connected to the first waste heat recovery device and is used for fine dust removal on the raw coal gas after the first cooling, and controlling the temperature of the raw coal gas after the dust removal to be within the second temperature threshold.

[0140] Wherein, the second temperature threshold is less than the first temperature threshold and greater than the tar phase transition temperature;

[0141] The second waste heat recovery device is connected to the high-temperature electrostatic precipitator and is used for performing a second heat recovery on the raw gas after dust removal and controlling the temperature of the raw gas after dust removal to cool to a third temperature threshold to obtain the second cooled raw gas and the first condensed liquid tar.

[0142] Among them, the third temperature threshold is greater than the acid dew point of the raw coal gas.

[0143] The ammonia spray cooling device is connected to the second waste heat recovery device and is used to spray circulating ammonia water to cool the second cooling raw gas to a fourth temperature threshold. The fourth temperature threshold is less than the steam gasification point;

[0144] The gas-liquid separation device is connected to the ammonia spray cooling device and is used to separate the gas and liquid of the second cooled raw gas after being treated by the ammonia spray cooling device to obtain the third cooled raw gas and a mixture of the second condensed liquid tar and circulating ammonia water.

[0145] The tar-ammonia water separation device is connected to the second waste heat recovery device and the gas-liquid separation device, and is used to perform tar-ammonia water separation operations on the liquid tar condensed for the first time and the mixed liquid of the liquid tar condensed for the second time and the circulating ammonia water to obtain pure tar and separated circulating ammonia water.

[0146] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0147] Example 1

[0148] like Figure 2 As shown, in Example 1 of the present invention, the raw gas at 650-850° C. generated in each carbonization chamber 1 of the coke oven is collected into the high-temperature gas collecting pipe 3 through the riser 2 connected to the carbonization chamber 1 .

[0149] The first waste heat recovery device is a high-temperature heat exchanger 4 , and the second waste heat recovery device is a low-temperature heat exchanger 7 .

[0150] The main differences between the high temperature heat exchanger 4 and the low temperature heat exchanger 7 are their operating temperature range, material selection, corrosion resistance requirements, heat exchange efficiency, etc. Specifically, the high temperature heat exchanger 4 is mainly used in high temperature industrial fields, and the operating temperature is generally above 400°C.

[0151] The raw gas at 650-850°C collected in the high-temperature gas collecting pipe 3 is introduced into the high-temperature heat exchanger 4 for the first waste heat utilization, and the temperature at the outlet of the high-temperature heat exchanger 4 is set within 500-520°C.

[0152] The raw gas after heat exchange in the high-temperature heat exchanger 4 is passed into the high-temperature electrostatic precipitator 5 for fine dust removal, so as to remove particulate matter such as dust and coke particles in the raw gas before the tar phase changes, and the temperature at the outlet of the high-temperature electrostatic precipitator 5 can be controlled to be maintained between 470 and 500°C.

[0153] The raw coal gas after fine dust removal is introduced into the low-temperature heat exchanger 7 for waste heat utilization again, and the temperature at the outlet of the low-temperature heat exchanger 7 is set between 140 and 160°C to obtain liquid tar of the first condensation and raw coal gas of the second cooling.

[0154] The ammonia spray cooling device is arranged in the ammonia spray gas collecting pipe 8, and the gas-liquid separation device is a gas-liquid separator 9. When the raw gas cooled for the second time passes through the ammonia spray gas collecting pipe 8, the raw gas is cooled to 80-85°C by spraying circulating ammonia water through the ammonia spray cooling device, and then the raw gas sprayed with ammonia water is subjected to gas-liquid separation treatment through the gas-liquid separator 9 to obtain the treated raw gas and a mixed liquid of the second condensed liquid tar and circulating ammonia water.

[0155] The treated raw gas is further processed using the existing raw gas recovery. The mixed liquid of the second condensed liquid tar and circulating ammonia water, as well as the first condensed liquid tar, are passed into the tar ammonia water separation tank for separation to obtain pure tar, separated circulating ammonia water and tar residue.

[0156] Example 2

[0157] like Figure 3 As shown, in Example 2 of the present invention, the only difference from Example 1 is that the first waste heat recovery device includes a plurality of riser heat exchangers 6, each riser heat exchanger 6 is matched with one of the risers 2, and is used to directly perform the first heat recovery on the raw gas at the position of the riser 2 to obtain the raw gas with a temperature of 500-520°C, and then pass it into the high-temperature electrostatic precipitator 5 through the high-temperature gas collecting pipe 3.

[0158] like Figures 4 to 10 As shown, further, the first waste heat recovery device and the second waste heat recovery device also include supporting devices. The supporting devices include water tanks, desalted water preparation equipment, deaerators 11, water supply pumps 12 and other water supply equipment; also include steam drums 14, circulating pumps 13 and other water vapor separation equipment; each device is connected by a pipeline, and a valve 15 is also provided on the pipeline between the water supply devices to control the water supply speed.

[0159] In order to reduce manufacturing costs, the first waste heat recovery device and the second waste heat recovery device can share a set of water supply equipment during design to supply water between different heat exchangers at the same time, that is, the first waste heat recovery device and the second waste heat recovery device share a water circulation system. The first waste heat recovery device and the second waste heat recovery device can also share the steam drum 14 and part of the pipeline.

[0160] C in the figure represents the desalted water obtained by treatment with the desalted water preparation equipment, B in the figure represents the pure tar obtained after the tar-ammonia separation operation is performed by the tar-ammonia separation device 10, and A in the figure represents the raw gas obtained by separation by the gas-liquid separator 9.

[0161] Example 3

[0162] like Figure 4As shown, in Example 3 of the present invention, the first waste heat recovery device is a high-temperature heat exchanger 4, and the second waste heat recovery device is a low-temperature heat exchanger 7. The high-temperature heat exchanger 4 and the low-temperature heat exchanger 7 share a water circulation system and a steam drum 14.

[0163] The flow balance of the high-temperature heat exchanger 4 and the low-temperature heat exchanger 7 is controlled by the valve 15. The desalted water C is treated by the deaerator 11 to obtain desalted and deoxygenated water. The desalted and deoxygenated water is converted into a steam-water mixture in the high-temperature heat exchanger 4 and the low-temperature heat exchanger 7 and introduced into the steam drum 14. The steam-water mixture is separated in the steam drum 14 to obtain saturated steam of 0.4-1.2 MPa and output from the steam drum 14.

[0164] Example 4

[0165] like Figure 5 As shown, in Example 4 of the present invention, the only difference from Example 3 is that the first waste heat recovery device is a riser heat exchanger 6, and the riser heat exchanger 6 and the low-temperature heat exchanger 7 share a water circulation system and a steam drum 14.

[0166] The flow balance of the riser heat exchanger 6 and the low-temperature heat exchanger 7 is controlled by the valve 15. The desalted water C is treated by the deaerator 11 to obtain desalted and deoxygenated water. The desalted and deoxygenated water is converted into a steam-water mixture in the riser heat exchanger 6 and the low-temperature heat exchanger 7 and introduced into the steam drum 14. The steam-water mixture is separated in the steam drum 14 to obtain saturated steam of 0.4-1.2 MPa and output from the steam drum 14.

[0167] Example 5

[0168] like Figure 6 As shown, in embodiment 5 of the present invention, the only difference from embodiment 3 is that the high-temperature heat exchanger 4 and the low-temperature heat exchanger 7 share only one water circulation system, and do not share the same steam drum 14.

[0169] Specifically, the steam drum 14 corresponding to the high-temperature heat exchanger 4 is configured to generate high-grade saturated steam, and the steam drum 14 corresponding to the low-temperature heat exchanger 7 is configured to generate low-grade saturated steam. Thus, the step-by-step utilization effect of saturated steam of different grades is achieved, and the economic benefits of heat exchange of the high-temperature heat exchanger 4 and the low-temperature heat exchanger 7 are better utilized.

[0170] Example 6

[0171] like Figure 7 As shown, in Example 6 of the present invention, the only difference from Example 4 is that the riser heat exchanger 6 and the low-temperature heat exchanger 7 only share one water circulation system, and do not share the same steam drum 14.

[0172] Specifically, the steam drum 14 corresponding to the riser heat exchanger 6 is configured to generate high-grade saturated steam, and the steam drum 14 corresponding to the low-temperature heat exchanger 7 is configured to generate low-grade saturated steam. Thus, the step-by-step utilization effect of saturated steam of different grades is achieved, and the economic benefits of heat exchange of the high-temperature heat exchanger 4 and the low-temperature heat exchanger 7 are better utilized.

[0173] Example 7

[0174] like Figure 8 As shown, in Example 7 of the present invention, the difference from Example 3 is that the low-grade saturated steam generated in the low-temperature heat exchanger 7 is passed into the high-temperature heat exchanger 4 for reheating, and continues to exchange heat with the raw coal gas in countercurrent from bottom to top to generate high-grade superheated steam.

[0175] Example 8

[0176] like Fig. 9 As shown, in Example 7 of the present invention, the difference from Example 4 is that the low-grade saturated steam generated in the low-temperature heat exchanger 7 is introduced into the riser heat exchanger 6 for reheating, and continues to exchange heat with the raw coal gas in countercurrent from bottom to top to generate high-grade superheated steam.

[0177] Example 9

[0178] like Fig.10 As shown, in Example 9 of the present invention, the first waste heat recovery device is a riser heat exchanger 6, and multiple carbonization chambers 1 and combustion chambers in the coke oven are cross-spaced and distributed, a riser 2 is provided on the top of each carbonization chamber 1, and a riser heat exchanger 6 is provided on each riser 2.

[0179] In this embodiment, two steam drums 14 are respectively provided, and the two steam drums 14 share a water supply system, but each uses a water circulation system. Desalted and deoxygenated water enters from the bottom of the first n riser heat exchangers 6, and performs downstream heat exchange with the raw coal gas guided upward. The desalted and deoxygenated water is converted into a steam-water mixture in the riser heat exchanger 6, and is transported to the steam drums 14 corresponding to the first n riser heat exchangers 6 to obtain high-grade saturated steam.

[0180] The low-grade saturated steam obtained by heat exchange in the low-temperature heat exchanger 7 is introduced into the riser heat exchanger 6 after the nth riser heat exchanger 6, and performs countercurrent heat exchange with the raw coal gas from bottom to top to obtain high-grade superheated steam.

[0181] The first n riser heat exchangers 6 are the first recovery devices 61 , and the riser heat exchanger 6 after the nth riser heat exchanger 6 is the second recovery device 62 .

[0182] In summary, the method and system for high-temperature purification of raw gas from coke ovens and gradient utilization of waste heat of the present invention fully recovers the waste heat of the raw gas by gradient utilization of the waste heat of the raw gas collected from the carbonization chamber of the coke oven, thereby effectively improving the utilization efficiency of the waste heat of the raw gas.

[0183] The present invention collects high-temperature raw coal gas first and then utilizes the waste heat. The temperature difference of the raw coal gas in the collected high-temperature gas collecting pipe is small, the operating condition reaches dynamic stability, the equipment has no risk of coking, and there is no risk of reheating stone grinding, which is more conducive to equipment operation and control.

[0184] The present invention collects high-temperature raw coal gas first and then utilizes the waste heat, which can overcome the difficulty in selecting materials for the riser heat exchanger caused by large temperature fluctuations in the riser, the difficulty in process operation, water leakage, coking corrosion and graphite formation; and when the riser does not exchange heat, it also has the advantages of less coking and low failure rate.

[0185] The present invention performs fine dust removal before the tar phase change temperature in the raw coal gas, thereby ensuring that the equipment before the tar phase change does not produce coking problems and the operating stability of the working condition is high.

[0186] The present invention uses a high-temperature electrostatic precipitator to perform fine dust removal on raw coal gas before the tar phase change temperature under a dry method, thereby reducing the dust content of the tar collected by subsequent condensation, increasing the fluidity of the condensed tar, and improving the tar quality and economic benefits. At the same time, with the reduction of dust content, the subsequent process equipment and pipeline blockage problems are reduced, wear is reduced, the difficulty of process operation is reduced, and the service life of equipment and pipelines is increased.

[0187] The present invention adopts a high-temperature electric dust collector for fine dust removal, which has high dust removal efficiency and low equipment resistance and does not affect the coke output of the coke oven coking machine.

[0188] By adopting the scheme of the present invention, the temperature range of circulating ammonia water cooling raw gas is smaller, the amount of circulating ammonia water used is greatly reduced, the evaporation caused by cooling is also reduced, and the subsequent raw gas processing volume is reduced, while the process water consumption and electricity consumption are reduced.

[0189] The raw gas produced by the coke oven has a temperature of about 650-850℃ when entering the riser. When meeting the resistance requirements at such a high temperature, the high-temperature dust removal equipment can only be directly connected to simple-structured dust removal equipment, such as cyclone dust collectors, gravity sedimentation dust collectors, etc., which have low dust removal efficiency. The internal structure of the high-temperature electrostatic precipitator is complex, and the high-temperature material selection and expansion control are difficult. At present, there are almost no large-scale high-temperature electrostatic precipitators on the market that can be used at such high temperatures.

[0190] The present invention utilizes the waste heat of raw coal gas in a gradient manner, thereby reducing the inlet temperature of raw coal gas in a high-temperature electrostatic precipitator. The expansion of the equipment is relatively reduced at 500-520°C, and low-alloy heat-resistant steel with better economy can be selected, thereby reducing the difficulty of equipment design and operation. At the same time, the difficulty and requirements of equipment material selection are reduced. For example, the requirements for high temperature resistance, corrosion resistance, high thermal conductivity and thermal stress resistance can all be reduced. The coking cycle is also extended, the decoking time is shortened, and the stable operation of the process is ensured.

[0191] The present invention performs fine dust removal and ammonia spray cooling dust removal on raw coal gas, which not only increases the dust removal efficiency but also improves the coal gas quality.

[0192] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for high-temperature purification of coke oven raw gas and utilization of waste heat gradient, characterized in that: include: The first waste heat recovery device recovers the raw gas collected from the coke oven carbonization chamber for the first time, and controls the temperature of the raw gas to be cooled to a first temperature threshold, thereby obtaining the raw gas with the first cooling; the first temperature threshold is greater than the tar phase change temperature; The raw gas subjected to the first cooling is finely dedusted by a high-temperature electrostatic precipitator, and the temperature of the raw gas after dedusting is controlled within a second temperature threshold; the second temperature threshold is less than the first temperature threshold and greater than the tar phase change temperature; The second waste heat recovery device performs a second heat recovery on the dedusted raw gas, and controls the temperature of the dedusted raw gas to be cooled to a third temperature threshold, thereby obtaining the second cooled raw gas and the first condensed liquid tar; the third temperature threshold is greater than the acid dew point of the raw gas; The raw coal gas subjected to the second cooling is cooled to a fourth temperature threshold by spraying the circulating ammonia water, thereby obtaining the raw coal gas subjected to the third cooling, and a mixture of the liquid tar condensed for the second time and the circulating ammonia water; the fourth temperature threshold is less than the steam vaporization point; The liquid tar condensed for the first time and the mixed liquid of the liquid tar condensed for the second time and the circulating ammonia water are subjected to a tar-ammonia water separation operation to obtain pure tar and separated circulating ammonia water.

2. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: The first temperature threshold is 500-520°C.

3. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: The third temperature threshold is 140-160°C.

4. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: Each carbonization chamber of the coke oven is connected to a riser, and one end of the plurality of risers away from the carbonization chamber is connected to a high-temperature gas collecting pipe. The first waste heat recovery device is a high-temperature heat exchanger. The first waste heat recovery device is used to recover the raw gas collected from the carbonization chamber of the coke oven for the first time, specifically: After the riser collects the raw coal gas generated by the plurality of carbonization chambers into the gas collecting pipe, the high-temperature heat exchanger performs the first heat recovery on the raw coal gas.

5. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: Each carbonization chamber of the coke oven is connected to a riser, and one end of the plurality of risers away from the carbonization chamber is connected to a high-temperature gas collecting pipe. The first waste heat recovery device includes a riser heat exchanger arranged on each of the risers. The first waste heat recovery device is used to recover the raw gas collected from the carbonization chamber of the coke oven for the first time, specifically: Before the riser collects the raw coal gas generated by the plurality of carbonization chambers into the gas collecting pipe, the raw coal gas is subjected to a first heat recovery through the plurality of riser heat exchangers.

6. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: The first waste heat recovery device generates high-grade saturated steam during the first heat recovery process; and the second waste heat recovery device generates low-grade saturated steam during the second heat recovery process.

7. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: The first waste heat recovery device is connected to the second waste heat recovery device to jointly produce saturated steam.

8. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 6, characterized in that: The method further comprises: The low-grade saturated steam generated by the second waste heat recovery device is input into the first waste heat recovery device for heating to obtain high-grade superheated steam.

9. The method for high-temperature purification of raw coke oven gas and utilization of waste heat gradient according to claim 1, characterized in that: A plurality of carbonization chambers are distributed in a straight line in the coke oven, and each of the carbonization chambers is connected to a riser; the first waste heat recovery device includes a first recoverer and a second recoverer; the method further includes: The plurality of riser tubes are divided into a first group of tubes and a second group of tubes according to the positions of the riser tubes; the first recovery device is used to perform a first heat recovery on the first group of tubes and generate high-grade saturated steam during the first heat recovery process; the second waste heat recovery device is used to perform a second heat recovery and generate low-grade saturated steam during the second heat recovery process; The low-grade saturated steam is input into the second recovery vessel for heating to obtain high-grade superheated steam.

10. A system for high-temperature purification of raw coke oven gas and utilization of waste heat gradient, characterized in that: include: The first waste heat recovery device is used to recover the first heat of the raw gas collected from the coke oven carbonization chamber, and control the temperature of the raw gas to cool to a first temperature threshold to obtain the raw gas with the first cooling; the first temperature threshold is greater than the tar phase change temperature; a high-temperature electrostatic precipitator, connected to the first waste heat recovery device, for finely removing dust from the raw coal gas after the first cooling, and controlling the temperature of the raw coal gas after the dust removal to be within a second temperature threshold; the second temperature threshold is less than the first temperature threshold and greater than the tar phase change temperature; a second waste heat recovery device, connected to the high-temperature electrostatic precipitator, for performing a second heat recovery on the dedusted raw gas, and controlling the temperature of the dedusted raw gas to cool to a third temperature threshold, to obtain the second cooled raw gas and the first condensed liquid tar; the third temperature threshold is greater than the acid dew point of the raw gas; an ammonia spraying cooling device, connected to the second waste heat recovery device, for spraying circulating ammonia water to cool the raw coal gas subjected to the second cooling to a fourth temperature threshold; the fourth temperature threshold is less than the steam gasification point; a gas-liquid separation device, connected to the ammonia spray cooling device, for performing gas-liquid separation on the second cooled raw gas after being treated by the ammonia spray cooling device, to obtain the third cooled raw gas, and a mixture of the second condensed liquid tar and the circulating ammonia water; The tar-ammonia water separation device is connected to the second waste heat recovery device and the gas-liquid separation device, and is used to perform tar-ammonia water separation operations on the liquid tar condensed for the first time, and the mixed liquid of the liquid tar condensed for the second time and the circulating ammonia water to obtain pure tar and separated circulating ammonia water.

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