Method and system for controlling alkalinity of coke oven gas wet desulphurization system

Abstract

The embodiment of the invention provides a coke oven gas wet desulfurization system alkalinity control method and system. The method comprises the following steps: monitoring desulfurization liquid alkalinity data of a coke oven gas desulfurization system in real time; monitoring out-tower gas hydrogen sulfide data of the coke oven gas desulfurization system in real time; determining the adding amount of sodium carbonate according to the monitored desulfurization liquid alkalinity data and tower gas hydrogen sulfide data; determining a sodium carbonate adding amount instruction according to the sodium carbonate adding amount, and adjusting the adding amount of alkali added to the coke oven gas desulfurization system in real time according to the sodium carbonate adding amount instruction.

Description

Technical Field

[0001] The present invention relates to the field of coke oven gas purification, and particularly to a method and a system for controlling the alkalinity of a wet desulfurization system for coke oven gas. Background Art

[0002] The essence of the sodium alkali method for desulfurizing coke oven gas is that soda ash reacts with hydrogen sulfide absorbed by the solution under the action of a catalyst, and then is oxidized and regenerated to form elemental sulfur, and some side reactions occur to form by-products such as sodium sulfate, sodium thiosulfate and sodium thiocyanate. During the desulfurization reaction process, soda ash will be gradually consumed, and soda ash needs to be replenished into the desulfurization system regularly to maintain the alkalinity stability so as to realize the continuous and stable operation of the desulfurization system.

[0003] In the process of realizing the present invention, the applicant found that there are at least the following problems in the prior art:

[0004] The intermittent alkali addition method of the traditional desulfurization system causes technical problems such as low utilization rate of soda ash, poor economy, high by-product salt concentration, large corrosion to equipment, and poor desulfurization effect at the end stage due to unstable alkalinity. Summary of the Invention

[0005] An embodiment of the present invention provides a method for controlling the alkalinity of a wet desulfurization system for coke oven gas to solve the technical problems of low utilization rate of soda ash, poor economy, high by-product salt concentration, large corrosion to equipment, and poor desulfurization effect at the end stage caused by the intermittent alkali addition method of the traditional desulfurization system.

[0006] To achieve the above object, on the one hand, an embodiment of the present invention provides a method for controlling the alkalinity of a wet desulfurization system for coke oven gas, including:

[0007] Real-time monitoring of the alkalinity data of the desulfurization liquid in the coke oven gas desulfurization system;

[0008] Real-time monitoring of the hydrogen sulfide data of the gas out of the tower in the coke oven gas desulfurization system;

[0009] According to the monitored alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the gas out of the tower, determine the soda ash dosage, and determine the soda ash dosage instruction according to the soda ash dosage;

[0010] According to the soda ash dosage instruction, adjust the dosage of the alkali added to the coke oven gas desulfurization system in real time.

[0011] Further, the determining the soda ash dosage according to the monitored alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the gas out of the tower includes:

[0012] When the currently monitored alkalinity data of the desulfurization liquid is less than 0.25 mol / L, determine the soda ash dosage according to the following soda ash dosage formula:

[0013] M = [(0.25 - N) × 20 + (S - 0.9) × 10 + G × δ] × 41.7 (1)

[0014] Wherein, M is the dosage of soda ash, in kilograms; N is the alkalinity of the desulfurization solution monitored last time, in moles per liter; S is the sulfur content on dry basis of the blended coking coal monitored last time, in %; G is the gas treatment flow rate, in 10,000 standard cubic meters per hour; δ is the correction factor. When the gas treatment flow rate ≤ 50,000 standard cubic meters per hour, δ = 1.0. When the gas treatment flow rate is greater than 50,000 standard cubic meters per hour, δ = G / 5.

[0015] Further, when the alkalinity data of the desulfurization solution monitored currently is less than 0.25 moles per liter, the dosage of soda ash is determined according to the formula for the dosage of soda ash. After that, it further includes:

[0016] If the fluctuation range of the hydrogen sulfide content in the outlet gas monitored currently relative to the hydrogen sulfide content in the outlet gas monitored last time is greater than 50% and the hydrogen sulfide content in the outlet gas monitored currently is greater than 50 mg / Nm 3 and less than or equal to 100 mg / Nm 3 , or the hydrogen sulfide content in the outlet gas monitored currently is greater than 100 mg / Nm 3 , then increase the dosage of soda ash by 20%. Otherwise, keep the dosage of soda ash unchanged.

[0017] Further, determining the dosage of soda ash according to the monitored alkalinity data of the desulfurization solution and the hydrogen sulfide data in the outlet gas includes:

[0018] When the alkalinity data of the desulfurization solution monitored currently is within the range of 0.25 to 0.35 moles per liter, if the fluctuation range of the hydrogen sulfide content in the outlet gas monitored currently relative to the hydrogen sulfide content in the outlet gas monitored last time is greater than 50% and the hydrogen sulfide content in the outlet gas monitored currently is greater than 50 mg / Nm 3 and the hydrogen sulfide content in the outlet gas monitored currently is less than or equal to 100 mg / Nm 3 , or the hydrogen sulfide content in the outlet gas monitored currently is greater than 100 mg / Nm 3 , then issue an instruction to increase the dosage of soda ash by 0.2 tons. Otherwise, set the dosage of soda ash to 0.

[0019] Further, determining the dosage of soda ash according to the monitored alkalinity data of the desulfurization solution and the hydrogen sulfide data in the outlet gas includes:

[0020] When the currently monitored alkalinity data of the desulfurization solution > 0.35 mol / L, if the fluctuation range of the currently monitored hydrogen sulfide content in the outlet tower gas relative to the previously monitored hydrogen sulfide content in the outlet tower gas is greater than 50% or the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , the soda ash dosage is increased by 0.1 ton; otherwise, the soda ash dosage is set to 0.

[0021] Furthermore, determining the soda ash dosage according to the monitored alkalinity data of the desulfurization solution and the hydrogen sulfide data of the outlet tower gas includes:

[0022] When the hydrogen sulfide data of the outlet tower gas obtained from the last three consecutive monitors are all greater than 100 mg / Nm 3 , the preset alkalinity control reference is set to 0.35 mol / L; or,

[0023] When the hydrogen sulfide data of the outlet tower gas obtained from the last three consecutive monitors are less than or equal to 50 mg / Nm 3 , the preset alkalinity control reference is set to 0.2 mol / L.

[0024] Furthermore, adjusting the addition amount of alkali added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction includes:

[0025] Generating a current or voltage control signal according to the soda ash dosage instruction;

[0026] Controlling the start duration of the metering pump through the current or voltage control signal to adjust the addition amount of alkali added to the coke oven gas desulfurization system in real time;

[0027] Furthermore, adjusting the addition amount of alkali added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction further includes:

[0028] When the liquid level of the alkali addition tank is lower than 0.8 m or the liquid level of the reaction tank of the coke oven gas desulfurization system is higher than 3.5 m, the operation of the metering pump is automatically stopped; the alkali addition tank stores the alkali liquor prepared to be added to the coke oven gas desulfurization system.

[0029] Furthermore, the real-time monitoring of the alkalinity data of the desulfurization solution in the coke oven gas desulfurization system includes:

[0030] Regularly calibrating the alkalinity on-line monitoring device according to the standard alkali liquor; the alkalinity on-line monitoring device is used to monitor and obtain the alkalinity data of the desulfurization solution.

[0031] On the other hand, an embodiment of the present invention provides an alkalinity control system for a wet flue gas desulfurization system of coke oven gas, including: a coke oven gas desulfurization system, an online alkalinity monitoring subsystem, an online hydrogen sulfide monitoring subsystem, an automatic alkalinity adjustment subsystem, and a continuous caustic addition subsystem;

[0032] The online alkalinity monitoring subsystem is connected to the coke oven gas desulfurization system, and is used for real-time monitoring of the desulfurization liquid alkalinity data of the coke oven gas desulfurization system;

[0033] The online hydrogen sulfide monitoring subsystem is connected to the coke oven gas desulfurization system, and is used for real-time monitoring of the hydrogen sulfide data of the outlet gas of the coke oven gas desulfurization system;

[0034] The automatic alkalinity adjustment subsystem is connected to the online alkalinity monitoring subsystem, the online hydrogen sulfide monitoring subsystem, and the continuous caustic addition subsystem, and is used for receiving the desulfurization liquid alkalinity data from the online alkalinity monitoring subsystem, and receiving the hydrogen sulfide data of the outlet gas from the online hydrogen sulfide monitoring subsystem, determining the soda ash dosage, and determining a soda ash dosage instruction according to the soda ash dosage;

[0035] The continuous caustic addition subsystem is connected to the coke oven gas desulfurization system, and is used for adjusting the addition amount of caustic added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction.

[0036] The above technical solution has the following beneficial effects: realizing real-time monitoring and precise control of the desulfurization liquid alkalinity of the coke oven gas desulfurization system, maintaining the alkalinity in a range with higher desulfurization efficiency, effectively avoiding the problem of alkalinity fluctuation caused by intermittent caustic addition, effectively improving the alkalinity stability of the coke oven gas desulfurization system, reducing the consumption of soda ash and the generation amount of by-products during desulfurization, and stabilizing the desulfurization efficiency of the desulfurization system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 is a flowchart of a method for controlling the alkalinity of a wet flue gas desulfurization system of coke oven gas according to one of the embodiments of the present invention;

[0039] Figure 2 is a schematic structural diagram of an alkalinity control system for a wet flue gas desulfurization system of coke oven gas according to one of the embodiments of the present invention;

[0040] Figure 3 It is a schematic structural diagram of a wet desulfurization system for coke oven gas according to one embodiment of the present invention;

[0041] Figure 4 It is a schematic structural diagram of a continuous caustic adding subsystem according to one embodiment of the present invention.

[0042] The reference numerals are represented as: 20, coke oven gas desulfurization system; 21, online alkalinity monitoring subsystem; 22, online hydrogen sulfide monitoring subsystem; 23, automatic alkalinity adjustment subsystem; 24, continuous caustic adding subsystem. Specific embodiments

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] On the one hand, as Figure 1 shown, an embodiment of the present invention provides a method for controlling the alkalinity of a wet desulfurization system for coke oven gas, including:

[0045] Step S10, monitoring the alkalinity data of the desulfurization liquid of the coke oven gas desulfurization system in real time;

[0046] Step S11, monitoring the hydrogen sulfide data of the outlet tower gas of the coke oven gas desulfurization system in real time;

[0047] Step S12, determining the soda ash dosage according to the monitored alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet tower gas, and determining a soda ash dosage instruction according to the soda ash dosage;

[0048] Step S13, adjusting the addition amount of alkali added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction.

[0049] In some embodiments, the traditional method of adding alkali usually uses the alkalinity of the system on the previous day as the benchmark for adjustment. The data lacks timeliness and has a large adjustment error. The calculation of the alkali addition amount is based on the ratio between the molar amounts of sodium carbonate and hydrogen sulfide in a complete reaction, rather than the actual demand. Discrete or three-shift manual alkali addition is adopted. Relatively speaking, the amount of soda ash added to the system is large, which has a great impact on the wet desulfurization system, causing frequent fluctuations in the desulfurization liquid index and the hydrogen sulfide content in the outlet gas of the tower, which is not conducive to the stable operation of the system and consumes a large amount of labor costs. Compared with the traditional intermittent alkali addition method, the embodiments of the present invention adopt real-time monitoring of the alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet gas of the tower, and determine the soda ash addition amount and the soda ash addition amount command according to the alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet gas of the tower obtained by real-time monitoring, and adjust the addition amount of alkali added to the coke oven gas desulfurization system in real time, fully considering the fluctuations in the gas treatment flow rate of the system and the sulfur content in the dry basis of the coking coal, so as to avoid the problems of unstable alkalinity and low alkali addition control accuracy of the coke oven gas desulfurization system caused by the pulsating alkali addition of the traditional intermittent alkali addition method.

[0050] The embodiments of the present invention have the following technical effects: realizing real-time monitoring and precise control of the alkalinity of the desulfurization liquid in the coke oven gas desulfurization system, maintaining the alkalinity in a range with higher desulfurization efficiency, effectively avoiding the problem of alkalinity fluctuation caused by intermittent alkali addition, effectively improving the alkalinity stability of the coke oven gas desulfurization system, reducing the consumption of soda ash and the generation amount of by-products during desulfurization, and stabilizing the desulfurization efficiency of the desulfurization system. After testing, the stability of the alkalinity of the desulfurization liquid and the hydrogen sulfide content index of the outlet coke oven gas in each wet desulfurization system has been improved. On the one hand, the hydrogen sulfide in the outlet coke oven gas of each wet desulfurization system has been significantly reduced. During the testing period of the embodiments of the present invention, compared with the intermittent alkali addition method adopted, the average value of the hydrogen sulfide content in the outlet coke oven gas of the wet desulfurization system is 23.322 mg / Nm 3 , a decrease of 45.128 mg / Nm 3 , a decrease of 65.9%, and the pass rate of the hydrogen sulfide content in the outlet gas reaches 100% for the first time. On the other hand, the consumption of soda ash has also been significantly reduced. The alkali consumption of the desulfurization system is the amount of soda ash consumed corresponding to every ten thousand cubic meters of gas, which is 42.03 kg / 10,000 Nm 3 , a decrease of 3.09 kg / 10,000 Nm 3 , a decrease of 6.85%. The reduction of soda ash consumption per ten thousand cubic meters of coke oven gas treated can reach 27.07 tons / year, reducing the cost by about 57,200 yuan / year. In addition, with the decrease of the hydrogen sulfide in the outlet gas, the total sulfur dioxide emission at the discharge ports of each coke oven gas user also decreases. During the testing period, the reduction of sulfur dioxide emission per ten thousand cubic meters of coke oven gas treated can reach 7.44 tons / year, and the environmental protection benefit is obvious.

[0051] Further, the determining of the soda ash addition amount according to the monitored alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet gas of the tower includes:

[0052] When the currently monitored alkalinity data of the desulfurization liquid is less than 0.25 mol / L, determine the soda ash dosage according to the following soda ash dosage formula:

[0053] M = [(0.25 - N)×20 + (S - 0.9)×10 + G×δ]×41.7 (1)

[0054] Where M is the soda ash dosage in kilograms; N is the alkalinity of the desulfurization liquid monitored last time in mol / L; S is the sulfur content of the dry basis of the blended coal in the coke line monitored last time in %; G is the gas treatment flow rate in 10,000 Nm³ / h; δ is the correction coefficient. When the gas treatment flow rate ≤ 50,000 Nm³ / h, δ = 1.0. When the gas treatment flow rate is greater than 50,000 Nm³ / h, δ = G / 5. The sulfur content data of the blended coal comes from the analysis results of the laboratory. The sulfur content data of the blended coal is an index of the coal for coking into the furnace, which is directly related to the level of hydrogen sulfide in the incoming tower gas. The process of coke oven gas: During the coking process of the blended coal for coking added to the coke oven, coke and coke oven gas are obtained. The coke oven gas is sent to the chemical production for purification through pipelines and then sent to users as a heat source gas. Wet gas desulfurization is to reduce the hydrogen sulfide in the coke oven gas as much as possible to below the qualified standard. If there is more hydrogen sulfide entering the desulfurization tower, more soda ash needs to be added. Therefore, the sulfur content of the blended coal is indirectly related to the desulfurization system but is very important.

[0055] This formula not only considers the fluctuation of the alkalinity data, but also takes into account the influence of the fluctuation of the sulfur content of the dry basis of the corresponding blended coal in the coke line and the fluctuation of the gas treatment flow rate on the amount of alkali added, realizing more scientific and accurate regulation of the alkalinity index of the desulfurization system when the alkalinity data of the desulfurization liquid is less than 0.25.

[0056] Further, when the currently monitored alkalinity data of the desulfurization liquid is less than 0.25 mol / L, after determining the soda ash dosage according to the soda ash dosage formula, it further includes:

[0057] If the fluctuation amplitude of the currently monitored hydrogen sulfide content in the outlet tower gas relative to the hydrogen sulfide content in the outlet tower gas monitored last time is greater than 50% and the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 50 mg / Nm 3 and less than or equal to 100 mg / Nm 3 or the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , then increase the soda ash dosage by 20%, otherwise keep the soda ash dosage unchanged.

[0058] In some embodiments, alkalinity is one of the key factors affecting the wet desulfurization effect. When the alkalinity of the desulfurization liquid is less than 0.25 moles per liter, it means that the alkalinity of the desulfurization liquid is relatively weak, which may affect the progress of the desulfurization reaction. At this time, paying attention to the hydrogen sulfide content in the outlet gas and adjusting the soda ash dosage according to its change can maintain the efficiency of the desulfurization reaction in a timely manner by increasing the alkali amount under the condition of low alkalinity, and avoid the deterioration of the desulfurization effect caused by insufficient alkalinity. When the hydrogen sulfide content is between 50-100 mg / Nm 3 Although it exceeds the standard, the situation is relatively less serious. Combined with the fluctuation range of the hydrogen sulfide content in the outlet gas being greater than 50%, it can timely detect possible abnormal situations in the desulfurization system. A larger fluctuation range indicates that there are obvious changes in the desulfurization effect, which may be due to changes in the gas flow rate, composition, or the operating conditions of the desulfurization system itself. The combination of the two can quickly respond when the system undergoes large changes and stabilize the desulfurization effect. When the hydrogen sulfide content is greater than 100 mg / Nm 3 it indicates that the desulfurization effect has seriously deteriorated. At this time, it is more necessary to strengthen the desulfurization process by increasing the soda ash dosage to quickly reduce the hydrogen sulfide content to meet the environmental protection requirements and the needs of subsequent processes. At the same time, such a grading setting also avoids excessive adjustment of the soda ash dosage when the hydrogen sulfide content only slightly exceeds the standard, achieving a balance between precise control and cost-effectiveness. Increasing the soda ash dosage by 20% can usually improve the desulfurization efficiency to a certain extent and reduce the hydrogen sulfide content to a reasonable range.

[0059] The embodiments of the present invention have the following technical effects: When the hydrogen sulfide content increases and the fluctuation range is large, increasing the soda ash dosage in a timely manner can increase the alkalinity of the desulfurization liquid and enhance the driving force of the desulfurization reaction, thereby more effectively absorbing hydrogen sulfide in the gas, ensuring the desulfurization effect, and making the hydrogen sulfide content in the outlet gas as stable as possible at a low level to meet the requirements of subsequent processes and environmental protection emission standards; if the fluctuation and content of the hydrogen sulfide data in the outlet gas do not reach the set adjustment conditions, the soda ash dosage remains unchanged, which can avoid unnecessary addition of alkali liquid, prevent waste of alkali liquid caused by blindly increasing the alkali amount, reduce the consumption cost of soda ash, and at the same time avoid possible negative impacts on the system caused by excessive addition of alkali liquid, such as imbalance of desulfurization liquid components and increased equipment corrosion. It can monitor the key parameters of the desulfurization system in real time and make timely adjustments according to the parameter changes. When the alkalinity of the desulfurization liquid is low and the hydrogen sulfide data in the outlet gas shows abnormal fluctuations or exceeds the standard, quickly increasing the soda ash dosage helps to quickly restore the normal operation state of the system, improve the stability and reliability of the entire coke oven gas desulfurization system, and reduce the risk of reduced desulfurization efficiency and production interruption caused by system fluctuations. Thus, it achieves the effects of precise adjustment, ensuring the desulfurization effect, avoiding waste and excessive addition of alkali liquid, and timely responding to system changes to improve stability.

[0060] Furthermore, determining the soda ash dosage based on the monitored causticity data of the desulfurization solution and the hydrogen sulfide data of the outlet tower gas includes:

[0061] When the currently monitored causticity data of the desulfurization solution is within the range of 0.25 to 0.35 mol / L, if the fluctuation amplitude of the currently monitored hydrogen sulfide content in the outlet tower gas relative to the previously monitored hydrogen sulfide content in the outlet tower gas is greater than 50% and the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 50 mg / Nm 3 and the currently monitored hydrogen sulfide content in the outlet tower gas is less than or equal to 100 mg / Nm 3 , or the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , then an instruction to increase the soda ash dosage by 0.2 tons is given; otherwise, the soda ash dosage is set to 0.

[0062] In some embodiments, when the causticity of the desulfurization solution is in the range of 0.25 - 0.35 mol / L, although the causticity is relatively appropriate, if the fluctuation of the hydrogen sulfide content in the outlet tower gas is large or exceeds the standard, it indicates that the desulfurization effect is unstable. At this time, accurately increasing the soda ash dosage according to the hydrogen sulfide data can timely adjust the balance of the desulfurization reaction, enhance the desulfurization ability, maintain a stable and efficient desulfurization effect, and ensure that the hydrogen sulfide content of the outlet tower gas meets the process requirements and environmental protection standards as much as possible. Considering the causticity of the desulfurization solution, the hydrogen sulfide content in the outlet tower gas and its fluctuation comprehensively can flexibly respond to various changes in the coke oven gas desulfurization system. When the hydrogen sulfide data fluctuates greatly and exceeds a certain range, for example, the fluctuation amplitude is greater than 50% and the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 50 mg / Nm 3 and the currently monitored hydrogen sulfide content in the outlet tower gas is less than or equal to 100 mg / Nm 3 , or the hydrogen sulfide content in the outlet tower gas significantly exceeds the standard (greater than 100 mg / Nm 3 ), a rapid response can be made by increasing the soda ash dosage by a fixed amount (0.2 tons), effectively avoiding a significant decline in the desulfurization effect caused by system parameter fluctuations, improving the anti-interference ability and stability of the system. When the system parameters do not meet the adjustment conditions, the soda ash dosage is set to 0, avoiding adding soda ash when it is unnecessary, preventing alkali solution waste, and reducing the soda ash consumption cost. At the same time, when necessary, enough alkali solution can be added in time, avoiding the continuous deterioration of the desulfurization effect due to insufficient alkali solution, realizing the reasonable control of the alkali solution dosage, and contributing to maintaining the economic and efficient operation of the desulfurization system. The effects of maintaining a stable desulfurization efficiency, flexibly responding to system fluctuations, avoiding alkali solution waste and insufficiency are achieved.

[0063] Further, determining the soda ash dosage according to the monitored alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet tower gas includes:

[0064] When the currently monitored alkalinity data of the desulfurization liquid > 0.35 mol / L, if the fluctuation range of the currently monitored hydrogen sulfide content in the outlet tower gas relative to the previously monitored hydrogen sulfide content in the outlet tower gas is greater than 50% or the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , then increase the soda ash dosage by 0.1 ton, otherwise, set the soda ash dosage to 0.

[0065] In some embodiments, when the alkalinity of the desulfurization liquid is greater than 0.35 mol / L, it is already at a relatively high alkalinity level. At this time, if the fluctuation range of the hydrogen sulfide content in the outlet tower gas is greater than 50% or the hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , it indicates that the desulfurization effect is abnormal. Increasing the soda ash dosage by 0.1 ton can specifically strengthen the desulfurization reaction, improve the absorption capacity of hydrogen sulfide, ensure the desulfurization effect, and reduce the hydrogen sulfide content in the gas to a qualified level. If the fluctuation range of the hydrogen sulfide content in the outlet tower gas is not large and does not exceed the standard, set the soda ash dosage to 0, avoiding adding alkali liquor under unnecessary circumstances. This helps prevent waste of alkali liquor caused by excessive addition of alkali, reduces the consumption cost of soda ash, and also reduces the burden of subsequent treatment of excessive alkali liquor. According to the actual operating conditions of the desulfurization system, that is, the changes in the alkalinity of the desulfurization liquid and the hydrogen sulfide content in the outlet tower gas, timely and flexibly adjust the soda ash dosage. Even in the case of high alkalinity, it can still respond to abnormal changes in the system, effectively avoiding a decrease in desulfurization efficiency caused by fluctuations or exceeding the standard of hydrogen sulfide content, improving the stability and reliability of the entire wet desulfurization system, and ensuring the smooth operation of the system. Reasonably controlling the addition amount of alkali liquor avoids adverse effects such as corrosion of equipment caused by too high alkali liquor concentration, helps extend the service life of equipment, reduces equipment maintenance costs, and improves the operating efficiency and safety of equipment. Thus, it achieves precise regulation, ensures the desulfurization effect, prevents waste of alkali liquor, adapts to system changes, improves stability, and protects equipment.

[0066] Further, determining the soda ash dosage according to the monitored alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet tower gas includes:

[0067] When the hydrogen sulfide data of the outlet tower gas obtained from the most recent three consecutive monitors are all greater than 100 mg / Nm 3 , set the preset alkalinity control reference to 0.35 mol / L; or,

[0068] When the hydrogen sulfide data of the outlet tower gas obtained from the most recent three consecutive monitors are less than or equal to 50 mg / Nm3 In this case, the preset alkalinity control reference is set to 0.2 mol / L.

[0069] In some embodiments, according to different concentration ranges of hydrogen sulfide in the off-tower gas, the preset alkalinity control reference is dynamically adjusted. When the hydrogen sulfide concentration is relatively high (greater than 100 mg / Nm 3 ) for three consecutive times, the alkalinity control reference is increased to 0.35 mol / L, which can provide a more favorable alkaline environment for the desulfurization reaction, enhance the absorption capacity of the desulfurizer for hydrogen sulfide, thereby more effectively reducing the hydrogen sulfide content in the gas, improving the desulfurization efficiency, and ensuring that the desulfurization effect meets the production and environmental protection requirements. When the hydrogen sulfide concentration is relatively low (less than or equal to 50 mg / Nm 3 ) for three consecutive times, the alkalinity control reference is reduced to 0.2 mol / L, which can not only maintain a certain desulfurization capacity but also avoid unnecessary consumption of lye and other potential problems caused by too high alkalinity, realizing the optimization of the desulfurization effect. By adjusting the alkalinity reference according to the actual hydrogen sulfide concentration, the waste of lye caused by maintaining a high alkalinity when the hydrogen sulfide concentration is low is avoided. The reasonable use of lye can reduce the consumption of desulfurizers such as soda ash, thereby reducing the operating cost of the wet desulfurization system for coke oven gas (coke oven gas desulfurization system). At the same time, the subsequent treatment costs such as wastewater treatment costs caused by excessive addition of lye are reduced. Appropriate alkalinity control helps to reduce the corrosion of equipment by too high alkalinity. When the alkalinity is controlled within a reasonable range, the degree of erosion of the equipment by alkaline substances can be reduced, the service life of the equipment can be extended, the frequency of equipment maintenance and replacement can be reduced, and thus the equipment maintenance cost can be reduced, ensuring the stable operation of the desulfurization system. This way of dynamically adjusting the alkalinity reference according to the actual monitoring data enables the desulfurization system to better adapt to the change of hydrogen sulfide content in the gas. It avoids large fluctuations in the desulfurization effect caused by fluctuations in the hydrogen sulfide content, improves the anti-interference ability and stability of the system, and ensures that the entire wet desulfurization system for coke oven gas can operate stably for a long time, providing stable gas quality for the subsequent process. Thus, the effects of flexibly adjusting the alkalinity reference, optimizing the desulfurization effect, reducing the operating cost, protecting the equipment, and improving the system stability are achieved.

[0070] Furthermore, according to the soda ash dosing instruction, the dosing amount of adding alkali to the coke oven gas desulfurization system is adjusted in real time, including:

[0071] Generating a current or voltage control signal according to the soda ash dosing instruction;

[0072] Controlling the start duration of the metering pump through the current or voltage control signal to adjust in real time the dosing amount of adding alkali to the coke oven gas desulfurization system;

[0073] Further, according to the soda ash dosage instruction, the addition amount of the alkali added to the coke oven gas desulfurization system is adjusted in real time, and it further includes:

[0074] When the liquid level of the alkali addition tank is lower than 0.8 meters or the liquid level of the reaction tank of the coke oven gas desulfurization system is higher than 3.5 meters, the operation of the metering pump is automatically stopped; the alkali addition tank stores the alkali liquid to be added to the coke oven gas desulfurization system.

[0075] In some embodiments, when the liquid level of the reaction tank is higher than 3.5 meters, automatically stopping the operation of the metering pump can avoid the overflow of the alkali liquid caused by the too high liquid level. The overflow of the alkali liquid will not only cause waste of materials, but also may corrode the equipment and pollute the environment. At the same time, stopping the metering pump can prevent the system from bearing too much pressure due to the too high liquid level, protect the reaction tank and related equipment, extend their service life, reduce the maintenance cost and safety risk. Stopping the metering pump when the liquid level of the alkali addition tank is lower than 0.8 meters can prevent the metering pump from idling due to insufficient alkali liquid in the alkali addition tank. Idling may damage the metering pump, affect its normal working performance, and even cause failures. In addition, it can also avoid insufficient alkalinity of the desulfurization system caused by insufficient alkali liquid supply, affect the desulfurization effect, and ensure the stable operation of the system. By real-time monitoring the liquid levels of the alkali addition tank and the reaction tank and automatically controlling the operation of the metering pump according to the liquid level conditions, the addition of the alkali liquid in the desulfurization system can be within a reasonable range, maintaining the stable operation of the system. This helps to ensure the normal progress of the desulfurization reaction, make the coke oven gas desulfurization effect reach the expected standard, improve the safety of the system at the same time, and reduce the possibility of safety accidents and production accidents caused by abnormal liquid levels. It achieves the effects of preventing the overflow of the alkali liquid and equipment damage, avoiding insufficient alkali addition or idling, and ensuring the safe and stable operation of the system.

[0076] Further, the real-time monitoring of the alkalinity data of the desulfurization liquid in the coke oven gas desulfurization system includes:

[0077] Regularly calibrating the alkalinity on-line monitoring device according to the standard alkali liquid; the alkalinity on-line monitoring device is used to monitor and obtain the alkalinity data of the desulfurization liquid.

[0078] In some embodiments, regular calibration can ensure the long-term accuracy of the monitoring data.

[0079] On the other hand, as Figure 2 shown, an alkalinity control system for a wet coke oven gas desulfurization system according to an embodiment of the present invention includes: a coke oven gas desulfurization system 20, an alkalinity on-line monitoring subsystem 21, a hydrogen sulfide on-line monitoring subsystem 22, an alkalinity automatic regulation subsystem 23, and a continuous alkali addition subsystem 24;

[0080] The alkalinity on-line monitoring subsystem 21 is connected to the coke oven gas desulfurization system 20, and the alkalinity on-line monitoring subsystem 21 is used to real-time monitor the alkalinity data of the desulfurization liquid in the coke oven gas desulfurization system 20;

[0081] The on-line hydrogen sulfide monitoring subsystem 22 is connected to the coke oven gas desulfurization system 20, and the on-line hydrogen sulfide monitoring subsystem 22 is used to monitor the hydrogen sulfide data of the gas out of the tower of the coke oven gas desulfurization system 20 in real time;

[0082] The alkalinity automatic regulation subsystem 23 is connected to the alkalinity on-line monitoring subsystem 21, the on-line hydrogen sulfide monitoring subsystem 22 and the continuous caustic soda adding subsystem 24, and is used to receive the desulfurization liquid alkalinity data from the alkalinity on-line monitoring subsystem 21, and receive the hydrogen sulfide data of the gas out of the tower from the on-line hydrogen sulfide monitoring subsystem 22, determine the soda ash dosage, and determine the soda ash dosage instruction according to the soda ash dosage;

[0083] The continuous caustic soda adding subsystem 24 is connected to the coke oven gas desulfurization system 20, and is used to adjust the adding amount of the alkali added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction.

[0084] Further, as Figure 3 shown, the coke oven gas desulfurization system 20 includes equipment such as a desulfurization tower, a regeneration tower, a circulation pump (desulfurization pump), and a reaction tank;

[0085] Further, the alkalinity on-line monitoring subsystem is used to monitor the real-time desulfurization liquid alkalinity from the coke oven gas desulfurization system, collect the desulfurization liquid alkalinity data of the coke oven gas desulfurization system, and the alkalinity on-line monitoring subsystem includes: an alkalinity on-line monitoring device, an alkalinity self-checking device, and a first monitoring signal remote transmission device;

[0086] The alkalinity on-line monitoring device is connected to the desulfurization liquid pipeline of the coke oven gas desulfurization system, and is used to monitor the desulfurization liquid alkalinity data of the coke oven gas desulfurization system in real time;

[0087] The alkalinity self-checking device is used to calibrate the alkalinity on-line monitoring device regularly according to the standard alkali solution to ensure the long-term accuracy of the desulfurization liquid alkalinity data;

[0088] The first monitoring signal remote transmission device is used to send the desulfurization liquid alkalinity to the alkalinity automatic regulation subsystem through a wireless or wired signal link including but not limited to wifi;

[0089] Further, the on-line hydrogen sulfide monitoring subsystem is used to monitor the hydrogen sulfide data of the gas out of the tower from the coke oven gas desulfurization system, and the on-line hydrogen sulfide monitoring subsystem includes: a hydrogen sulfide on-line monitoring device and a second monitoring signal remote transmission device;

[0090] The hydrogen sulfide on-line monitoring device is connected to the gas pipeline of the coke oven gas desulfurization system, and is used to monitor the hydrogen sulfide data of the gas out of the tower from the coke oven gas desulfurization system;

[0091] The second monitoring signal remote transmission device is used to send the hydrogen sulfide data of the gas out of the tower to the alkalinity automatic regulation subsystem by wireless or wired means including but not limited to wifi.

[0092] The alkalinity automatic regulation subsystem is used to compare the alkalinity of the desulfurization liquid in the coke oven gas desulfurization system returned by the alkalinity on-line monitoring subsystem and the hydrogen sulfide data of the gas out of the tower returned by the hydrogen sulfide on-line monitoring subsystem with the alkalinity control reference and the hydrogen sulfide control target, and at the same time compare with the previous hydrogen sulfide data of the gas out of the tower to calculate the soda ash dosage of the system;

[0093] Further, the alkalinity automatic regulation subsystem is specifically used for:

[0094] When the currently monitored alkalinity data of the desulfurization liquid is less than 0.25 mol / L, determine the soda ash dosage according to the following soda ash dosage formula:

[0095] M = [(0.25 - N) × 20 + (S - 0.9) × 10 + G × δ] × 41.7

[0096] Where, M is the soda ash dosage, in kilograms; N is the previously monitored alkalinity of the desulfurization liquid, in mol / L; S is the sulfur content on dry basis of the blended coal in the coke line monitored previously, in %; G is the gas treatment flow rate, in 10,000 Nm³ / h; δ is the correction coefficient.

[0097] And, when the currently monitored alkalinity data of the desulfurization liquid is less than 0.25 mol / L, determine the soda ash dosage according to the soda ash dosage formula, and then it is also used for: if the fluctuation range of the currently monitored hydrogen sulfide content in the gas out of the tower relative to the previously monitored hydrogen sulfide content in the gas out of the tower is greater than 50% and the currently monitored hydrogen sulfide content in the gas out of the tower is greater than 50 mg / Nm 3 And less than or equal to 100 mg / Nm 3 Or the currently monitored hydrogen sulfide content in the gas out of the tower is greater than 100 mg / Nm 3 , then increase the soda ash dosage by 20%, otherwise keep the soda ash dosage unchanged.

[0098] When the currently monitored alkalinity data of the desulfurization liquid is in the range of 0.25 to 0.35 mol / L, if the fluctuation range of the currently monitored hydrogen sulfide content in the gas out of the tower relative to the previously monitored hydrogen sulfide content in the gas out of the tower is greater than 50% and the currently monitored hydrogen sulfide content in the gas out of the tower is greater than 50 mg / Nm 3 And the currently monitored hydrogen sulfide content in the gas out of the tower is less than or equal to 100 mg / Nm 3, or if the currently monitored hydrogen sulfide content in the off-tower gas is greater than 100 mg / Nm 3 , then issue an instruction to increase the soda ash dosage by 0.2 tons; otherwise, set the soda ash dosage to 0.

[0099] When the currently monitored alkalinity data of the desulfurization liquid > 0.35 mol / L, if the fluctuation range of the currently monitored hydrogen sulfide content in the off-tower gas relative to the previously monitored hydrogen sulfide content in the off-tower gas is greater than 50% or the currently monitored hydrogen sulfide content in the off-tower gas is greater than 100 mg / Nm 3 , then increase the soda ash dosage by 0.1 tons; otherwise, set the soda ash dosage to 0.

[0100] Furthermore, the alkalinity automatic regulation subsystem is specifically configured to: when the hydrogen sulfide data of the off-tower gas obtained from the last three consecutive monitors are all greater than 100 mg / Nm 3 , set the preset alkalinity control reference to 0.35 mol / L; or, when the hydrogen sulfide data of the off-tower gas obtained from the last three consecutive monitors are less than or equal to 50 mg / Nm 3 , set the preset alkalinity control reference to 0.2 mol / L.

[0101] Furthermore, as Figure 4 shown, the continuous soda ash addition subsystem is connected in parallel with the intermittent soda ash addition system of the coke oven gas desulfurization system. Among them, the intermittent soda ash addition system includes: an intermittent soda ash addition pipe, a caustic soda dissolving tank, and a caustic soda solution pump.

[0102] The coke oven gas desulfurization system can be supplemented with soda ash through two soda ash addition methods simultaneously or by any one of the soda ash addition methods. When the continuous soda ash addition system fails, it does not affect the normal operation of the coke oven gas desulfurization system.

[0103] Furthermore, as Figure 4 shown, the continuous soda ash addition subsystem is used to continuously add soda ash to the coke oven gas desulfurization system. The continuous soda ash addition subsystem includes: a continuous soda ash addition tank, a metering pump, a continuous soda ash addition pipe, a liquid level monitoring device for the addition tank, and a liquid level monitoring device for the reaction tank of the coke oven gas desulfurization system; the liquid level monitoring device includes, but is not limited to, a remote liquid level gauge.

[0104] Among them, the continuous alkali addition subsystem is used to control the interlocking action of the metering pump and the liquid level of the alkali addition tank monitored by the alkali addition tank liquid level monitoring device, specifically: when the liquid level of the alkali addition tank monitored by the alkali addition tank liquid level monitoring device is lower than 0.8m (meter), the metering pump is automatically stopped to achieve automatic stop of the pump when the liquid level of the alkali addition tank is low; the continuous alkali addition subsystem is also used to control the interlocking action of the metering pump and the reaction tank liquid level of the coke oven gas desulfurization system, specifically: when the liquid level of the reaction tank is higher than 3.5m, the metering pump is automatically stopped to prevent the reaction tank from overflowing due to the reaction tank liquid level being too high and the metering pump not being stopped, thereby ensuring the safe operation of the system.

[0105] Furthermore, the continuous alkali addition subsystem includes a regular automatic flushing unit; the regular automatic flushing unit is used to regularly open the compressed air or clean water flushing valve to flush the alkali addition pipeline of the continuous alkali addition subsystem and backflush the bottom of the continuous alkali addition tank.

[0106] The above technical solutions of the embodiments of the present invention are described in detail below with reference to specific application examples. For technical details not introduced during the implementation process, please refer to the relevant description above.

[0107] The inventors found that the intermittent alkali addition method of the traditional desulfurization system leads to unstable alkalinity and has the following disadvantages:

[0108] (1) A large amount of alkali is added in a short period of time, resulting in excess alkali in the desulfurization circulating fluid, which leads to a large number of side reactions. The proportion of soda ash consumed by side reactions increases, resulting in low soda ash utilization rate. Under the same coal gas desulfurization effect, the alkali consumption increases and the economy is poor;

[0109] (2) Side reactions will generate a large amount of secondary salts such as sodium sulfate, sodium thiocyanate, and sodium thiosulfate. When the concentration of secondary salts is controlled within the range of 130-250g / L, the desulfurization efficiency is optimal. An increase in the concentration of secondary salts will not only reduce the desulfurization efficiency, but also easily precipitate crystals and adhere to the desulfurization tower wall and filler, causing the desulfurization tower to be blocked. In severe cases, it will cause the entire desulfurization cycle system to collapse, and the coal gas can only be transported through the emergency bypass pipeline. The coal gas that has not been desulfurized does not meet environmental protection standards.

[0110] (3) Excessive concentration of secondary salts will increase the specific gravity and viscosity of the desulfurization circulating fluid, affecting the flotation of sulfur foam;

[0111] (4) When adding alkali, the alkalinity and pH value of the desulfurization circulating liquid are too high, which is extremely corrosive to the desulfurization tower, pipelines and ancillary facilities, easily causing equipment corrosion, reducing equipment service life, increasing equipment maintenance frequency, and increasing maintenance safety risks;

[0112] (5) After the addition of alkali is completed and before the next addition of alkali, the alkalinity in the desulfurization circulating fluid gradually decreases, the final desulfurization efficiency deteriorates, and the stability of the desulfurization effect is affected.

[0113] In view of the above situation, to overcome the defects of the prior art, an embodiment of the present invention provides a method for controlling the alkalinity of a wet desulfurization system for coke oven gas, so as to solve the disadvantages caused by the unstable alkalinity resulting from the intermittent alkali addition method of the traditional desulfurization system. An alkalinity control system is designed. On the basis of the wet desulfurization system for coke oven gas (coke oven gas desulfurization system), a continuous alkali addition subsystem, an online alkalinity monitoring subsystem, an online hydrogen sulfide monitoring subsystem, and an automatic alkalinity regulation subsystem are added. The online alkalinity monitoring subsystem monitors and feeds back the alkalinity of the wet desulfurization system for coke oven gas to the automatic alkalinity regulation subsystem in real time. The automatic alkalinity regulation subsystem controls the continuous alkali addition subsystem to regulate the alkali addition amount, realizing precise regulation of the alkalinity of the coke oven gas desulfurization system. And through the large alkalinity data model, the system alkalinity setting is optimized, so that the alkalinity is maintained in the range with higher desulfurization efficiency, effectively avoiding the problem of alkalinity fluctuation caused by intermittent alkali addition, effectively improving the alkalinity stability of the coke oven gas desulfurization system, reducing the consumption of soda ash and the generation amount of by-products during the desulfurization process, and stabilizing the desulfurization efficiency of the desulfurization system.

[0114] To achieve the above object, an embodiment of the present invention provides a method for controlling the alkalinity of a wet desulfurization system for coke oven gas, which is adopted by the alkalinity control system of the wet desulfurization system for coke oven gas. The alkalinity control system of the wet desulfurization system for coke oven gas includes a coke oven gas desulfurization system (i.e., the wet desulfurization system for coke oven gas), a continuous alkali addition subsystem, an online alkalinity monitoring subsystem, an online hydrogen sulfide monitoring subsystem, and an automatic alkalinity regulation subsystem;

[0115] The coke oven gas desulfurization system is a set of wet desulfurization system for coke oven gas including complete processes and equipment, such as Figure 3 shown, including: desulfurization tower, regeneration tower, circulation pump, reaction tank and other equipment;

[0116] The continuous alkali addition subsystem is used to continuously add soda ash to the coke oven gas desulfurization system, such as Figure 4 shown, including: continuous alkali addition tank, metering pump, liquid level control, alkali liquid pipeline and other devices.

[0117] The online alkalinity monitoring subsystem is used to monitor the real-time alkalinity of the desulfurization liquid from the coke oven gas desulfurization system and collect the alkalinity data of the desulfurization liquid of the coke oven gas desulfurization system. The online alkalinity monitoring subsystem includes: an online alkalinity monitoring device, an alkalinity self-checking device, and a first monitoring signal remote transmission device. Among them, the online alkalinity monitoring device can include, but is not limited to, pH meters and other acidity and alkalinity measuring instruments; the pH meter is an online monitoring instrument that can measure the pH value of the desulfurization liquid in real time, so as to reflect the acidity and alkalinity of the desulfurization liquid; the electrode of the pH meter is inserted into the desulfurization liquid, and the change of the alkalinity of the desulfurization liquid is understood through the pH value displayed by the instrument. The alkalinity self-checking device calibrates the accuracy of the online alkalinity monitoring device through a pre-configured standard solution. The first monitoring signal remote transmission device is used to send the alkalinity of the desulfurization liquid to the automatic alkalinity regulation subsystem through wireless or wired signal links such as wifi.

[0118] The hydrogen sulfide on-line monitoring subsystem is used to monitor the hydrogen sulfide data of the gas out of the tower from the coke oven gas desulfurization system. The hydrogen sulfide on-line monitoring subsystem includes a hydrogen sulfide on-line monitoring device and a second monitoring signal remote transmission device. Among them, the hydrogen sulfide on-line monitoring device includes, but is not limited to, an electrochemistry sensor type monitoring device, an infrared absorption type monitoring device, a laser spectroscopy type monitoring device, etc. The electrochemistry sensor type monitoring device uses the oxidation-reduction reaction of hydrogen sulfide gas on the electrochemistry sensor to generate a current signal proportional to the hydrogen sulfide concentration, and determines the hydrogen sulfide concentration by measuring the current signal. The infrared absorption type monitoring device is based on the absorption characteristics of hydrogen sulfide molecules for infrared light of a specific wavelength. When the infrared light passes through the gas containing hydrogen sulfide, the infrared light of the specific wavelength will be absorbed by hydrogen sulfide, and the hydrogen sulfide concentration is calculated by detecting the absorption degree of the infrared light. The laser spectroscopy type monitoring device emits a laser beam of a specific wavelength. When the laser propagates in the gas containing hydrogen sulfide, the hydrogen sulfide molecules will absorb the laser of a specific frequency and generate an absorption spectrum. The hydrogen sulfide concentration is accurately measured by analyzing the change of the laser absorption spectrum. The second monitoring signal remote transmission device sends the hydrogen sulfide data of the gas out of the tower to the alkalinity automatic regulation subsystem by wireless or wired means such as wifi;

[0119] The alkalinity automatic regulation subsystem, namely the automatic control platform, after receiving the desulfurization liquid alkalinity of the coke oven gas desulfurization system returned by the alkalinity on-line monitoring subsystem and the hydrogen sulfide content data of the gas (hydrogen sulfide data of the gas out of the tower) returned by the hydrogen sulfide on-line monitoring subsystem, compares them with the alkalinity control reference and the hydrogen sulfide control target, and at the same time compares with the previous monitoring data, and calculates the soda ash dosage of the system according to the following logic to achieve precise regulation of the alkalinity of the coke oven gas wet desulfurization system. Specifically:

[0120] When the alkalinity data (desulfurization liquid alkalinity) returned by the alkalinity on-line monitoring subsystem is lower than 0.25 mol / L, the soda ash amount is calculated by the formula. The specific formula for the alkali addition amount (i.e., the soda ash dosage) is:

[0121] M = [(0.25 - N) × 20 + (S - 0.9) × 10 + G × δ] × 41.7

[0122] Among them, M is the soda ash dosage, in kilograms; N is the desulfurization liquid alkalinity monitored last time, in mol / L; S is the sulfur content in the dry basis of the blended coal in the coke line monitored last time, in %; G is the gas treatment flow rate, in 10,000 standard cubic meters per hour; δ is the correction coefficient;

[0123] And send the obtained amount of alkali added (i.e., the amount of soda ash added) to the continuous alkali addition subsystem to start the soda ash supplementary addition program; if the fluctuation range of the hydrogen sulfide content in the outlet gas returned by the on-line hydrogen sulfide monitoring subsystem compared with the hydrogen sulfide content in the outlet gas of the previous time is greater than 50% and the currently returned hydrogen sulfide content in the outlet gas > 50 mg / Nm 3 (milligrams per standard cubic meter) but ≤ 100 mg / Nm 3 , or the hydrogen sulfide content in the outlet gas > 100 mg / Nm 3 then return an instruction to increase the soda ash addition amount by 20% to the continuous alkali addition subsystem; otherwise, do not make any output return;

[0124] When the alkalinity data returned by the on-line alkalinity monitoring subsystem is within the range of 0.25 - 0.35 mol / L, if the fluctuation range of the currently returned hydrogen sulfide content in the outlet gas by the on-line hydrogen sulfide monitoring subsystem compared with the hydrogen sulfide content in the outlet gas of the previous time is greater than 50% and the currently returned hydrogen sulfide content in the outlet gas > 50 mg / Nm 3 but ≤ 100 mg / Nm 3 , or the currently returned hydrogen sulfide content in the outlet gas > 100 mg / Nm 3 then return an instruction to increase the soda ash addition amount by 0.2 t (tons) to the continuous alkali addition subsystem; otherwise, return an instruction to stop the soda ash addition;

[0125] When the alkalinity data returned by the on-line alkalinity monitoring subsystem > 0.35 mol / L, if the fluctuation range of the currently returned hydrogen sulfide content in the outlet gas by the on-line hydrogen sulfide monitoring subsystem compared with the hydrogen sulfide content in the outlet gas of the previous time is greater than 50%, or the currently returned hydrogen sulfide content in the outlet gas > 100 mg / Nm 3 then return an instruction to increase the soda ash addition amount by 0.1 t (tons) to the continuous alkali addition subsystem; otherwise, return an instruction to stop the soda ash addition.

[0126] Furthermore, the continuous alkali addition subsystem is connected in parallel with the intermittent alkali addition device (pure manual alkali addition system or intermittent alkali addition system) of the coke oven gas desulfurization system, and can supplement soda ash to the coke oven gas desulfurization system through two alkali addition methods simultaneously or by any one of the alkali addition methods. When the continuous alkali addition system fails, it does not affect the normal operation of the coke oven gas desulfurization system.

[0127] Further, the continuous caustic adding subsystem includes: a metering pump, a liquid level monitoring device for the caustic adding tank, and a liquid level monitoring device for the reaction tank of the coke oven gas desulfurization system; the continuous caustic adding subsystem is used to control the interlocking action of the metering pump with the liquid level of the caustic adding tank monitored by the liquid level monitoring device for the caustic adding tank, specifically: when the liquid level of the caustic adding tank monitored by the liquid level monitoring device for the caustic adding tank is lower than 0.8 m (meter), automatically stop the operation of the metering pump to achieve automatic pump stop when the liquid level of the caustic adding tank is low; the continuous caustic adding subsystem is also used to control the interlocking action of the metering pump with the liquid level of the reaction tank of the coke oven gas desulfurization system, specifically: when the liquid level of the reaction tank is higher than 3.5 m, automatically stop the operation of the metering pump to prevent the reaction tank from overflowing due to the failure of the interlocking stop of the metering pump when the liquid level of the reaction tank is too high, and ensure the safe operation of the system.

[0128] Further, the continuous caustic adding subsystem includes a regular automatic flushing unit; the regular automatic flushing unit is used to regularly open the compressed air or clean water flushing valve to flush and clean the caustic adding pipeline of the continuous caustic adding subsystem and backflush the bottom of the continuous caustic adding tank.

[0129] Further, the on-line alkalinity monitoring device is connected to the desulfurization liquid pipeline of the coke oven gas desulfurization system to monitor the alkalinity data of the desulfurization liquid; the on-line hydrogen sulfide monitoring device is connected to the gas pipeline of the coke oven gas desulfurization system to monitor the hydrogen sulfide data of the outlet tower gas; and the alkalinity data of the desulfurization liquid is remotely transmitted to the alkalinity automatic regulation subsystem through the first monitoring signal remote transmission device, and the hydrogen sulfide data of the outlet tower gas is remotely transmitted to the alkalinity automatic regulation subsystem through the second monitoring signal remote transmission device.

[0130] Further, the on-line alkalinity monitoring subsystem regularly and automatically detects the caustic standard solution to calibrate the alkalinity monitoring value.

[0131] Further, the alkalinity automatic regulation subsystem automatically inputs an instruction to the continuous caustic adding subsystem according to the alkalinity change of the coke oven gas desulfurization system, so that the alkalinity of the desulfurization liquid of the coke oven gas desulfurization system is stabilized at a set value.

[0132] Further, the continuous caustic adding subsystem adjusts the starting duration of the metering pump in real time according to the instruction issued by the alkalinity automatic regulation subsystem to control the soda ash dosage of the corresponding system and achieve precise regulation of alkalinity.

[0133] Further, the alkalinity automatic regulation subsystem re-sets the system alkalinity set value according to the hydrogen sulfide data of the outlet tower gas. Specifically: when the hydrogen sulfide data of the outlet tower gas is > 100 mg / Nm for 3 consecutive times 3 the alkalinity control reference is adjusted to 0.35, unit mol / L; when the hydrogen sulfide data of the outlet tower gas is ≤ 50 mg / Nm for 3 consecutive times 3 the alkalinity control reference is adjusted to 0.2, unit mol / L. The alkalinity control reference is the target set value for adjustment.

[0134] The automatic alkalinity regulation subsystem performs the following steps: 1. Data analysis: Analyze the alkalinity data of the desulfurization liquid collected by the on-line alkalinity monitoring subsystem and the hydrogen sulfide data of the outlet tower gas collected by the on-line hydrogen sulfide monitoring subsystem; 2. Alkalinity regulation: The intelligent alkalinity control module remotely adjusts the alkali liquid flow rate according to the alkalinity data of the desulfurization liquid to keep the alkalinity stable at the set value; 3. Feedback regulation: The intelligent alkalinity control module adjusts the alkalinity set value according to the hydrogen sulfide data of the outlet tower gas. 4. Parameter optimization: The intelligent alkalinity control module optimizes the alkalinity setting through statistical analysis of the alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet tower gas. 5. System status identification: Monitor the operation process of the alkalinity control system, and send a reminder to the management personnel when the alkali liquid flow rate, the alkalinity of the desulfurization liquid, and the hydrogen sulfide content in the gas are abnormal.

[0135] The embodiment of the present invention has the following technical effects: realizing the real-time monitoring and precise control of the alkalinity of the desulfurization liquid in the coke oven gas desulfurization system, optimizing the alkalinity setting of the system through the large alkalinity data model, keeping the alkalinity in the range with higher desulfurization efficiency, effectively avoiding the problem of alkalinity fluctuation caused by intermittent alkali addition, effectively improving the alkalinity stability of the coke oven gas desulfurization system, reducing the consumption of soda ash and the generation amount of by-products during desulfurization, and stabilizing the desulfurization efficiency of the desulfurization system.

[0136] The following is described by another embodiment:

[0137] The embodiment of the present invention provides a method for controlling the alkalinity of a wet desulfurization system for coke oven gas, including an alkalinity control system, characterized in that: the alkalinity control system includes a coke oven gas desulfurization system, a continuous alkali addition subsystem, an on-line alkalinity monitoring subsystem, an on-line hydrogen sulfide monitoring subsystem, and an automatic alkalinity regulation subsystem;

[0138] The continuous alkali addition subsystem is connected in parallel with the intermittent alkali addition system of the coke oven gas desulfurization system, and can supplement soda ash to the coke oven gas desulfurization system through two alkali addition methods simultaneously or by any one of the alkali addition methods. When the continuous alkali addition system fails, it does not affect the normal operation of the coke oven gas desulfurization system.

[0139] The continuous alkali addition subsystem includes a metering pump shutdown interlock and a control of the liquid level in the alkali addition tank. The metering pump is set in interlock with the liquid level in the reaction tank of the coke oven gas desulfurization system to prevent the reaction tank from overflowing due to the failure to interlock and stop the metering pump when the liquid level in the reaction tank is too high. When the liquid level in the alkali addition tank is high, the liquid inlet is automatically stopped;

[0140] The continuous alkali addition subsystem is provided with a regular automatic flushing program, and the compressed air or clean water flushing valve is regularly opened to flush and clean the alkali addition pipeline of the continuous alkali addition subsystem and backflush the bottom of the continuous alkali addition tank;

[0141] The online alkalinity monitoring device is connected to the desulfurization liquid pipeline of the coke oven gas desulfurization system to monitor the alkalinity data of the desulfurization liquid; the online hydrogen sulfide monitoring device is connected to the gas pipeline of the coke oven gas desulfurization system to monitor the hydrogen sulfide data of the outlet gas; and the monitored data can be transmitted remotely to the automatic control platform of the alkalinity automatic regulation subsystem.

[0142] The alkalinity automatic regulation subsystem automatically regulates the continuous caustic addition flow rate according to the alkalinity change of the coke oven gas desulfurization system, so that the alkalinity of the desulfurization liquid in the coke oven gas desulfurization system is stabilized at the set value.

[0143] The automatic control platform includes an alkalinity intelligent control module, a remote caustic liquid flow regulator, an alkalinity analysis module, and a hydrogen sulfide analysis module; it includes the following steps:

[0144] Step 1, data analysis: Analyze the alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet gas collected by the online alkalinity monitoring subsystem and the online hydrogen sulfide monitoring subsystem.

[0145] Step 2, alkalinity regulation: The alkalinity intelligent control module remotely regulates the caustic liquid flow rate according to the alkalinity data of the desulfurization liquid to stabilize the alkalinity at the set value.

[0146] Step 3, feedback regulation: The alkalinity intelligent control module adjusts the alkalinity set value according to the hydrogen sulfide data of the outlet gas.

[0147] Step 4, parameter optimization: The alkalinity intelligent control module optimizes the alkalinity setting through statistical analysis of the alkalinity data of the desulfurization liquid and the hydrogen sulfide data of the outlet gas.

[0148] Step 5, system state identification and adjustment: Monitor the operation process of the alkalinity control system, and send a reminder to the management personnel when the caustic liquid flow rate, the alkalinity of the desulfurization liquid, and the hydrogen sulfide content in the gas are abnormal.

[0149] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0150] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the protection scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy.

[0151] In the foregoing detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention lies in less than the full scope of features of the single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing alone as a separate preferred embodiment of the invention.

[0152] The above-described disclosed embodiments are described to enable any person skilled in the art to make or use the present invention. For those skilled in the art, various modifications to these embodiments are obvious, and the general principles defined herein can also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0153] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that each embodiment can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, this term is encompassed in a manner similar to the term "including". In addition, any use of the term "or" in the claims or specification is intended to mean "non-exclusive or".

[0154] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for controlling the alkalinity of a wet flue gas desulfurization system for coke oven gas, characterized in that, Including: Real-time monitoring of the causticity data of the desulfurization liquid in the coke oven gas desulfurization system; Real-time monitoring of the hydrogen sulfide data of the gas leaving the tower in the coke oven gas desulfurization system; Based on the monitored causticity data of the desulfurization liquid and the hydrogen sulfide data of the gas leaving the tower, determine the soda ash dosage, and determine the soda ash dosage instruction according to the soda ash dosage; According to the soda ash dosage instruction, adjust the addition amount of alkali added to the coke oven gas desulfurization system in real time.

2. The method for controlling the alkalinity of the wet flue gas desulfurization system of coke oven gas according to claim 1, characterized in that The step of determining the soda ash dosage based on the monitored causticity data of the desulfurization liquid and the hydrogen sulfide data of the gas leaving the tower includes: When the currently monitored causticity data of the desulfurization liquid is less than 0.25 mol / L, determine the soda ash dosage according to the following soda ash dosage formula: M = [(0.25 - N) × 20 + (S - 0.9) × 10 + G × δ] × 41.7 Where, M is the soda ash dosage, in kilograms; N is the causticity of the desulfurization liquid monitored last time, in mol / L; S is the sulfur content in the dry basis of the blended coal in the coke line monitored last time, in %; G is the gas treatment flow rate, in 10,000 standard cubic meters per hour; δ is the correction coefficient.

3. The method for controlling the alkalinity of the wet desulfurization system of coke oven gas according to claim 2, wherein, When the currently monitored causticity data of the desulfurization liquid is less than 0.25 mol / L, after determining the soda ash dosage according to the soda ash dosage formula, it further includes: If the fluctuation range of the detected hydrogen sulfide content in the outlet gas from the tower relative to the previously detected hydrogen sulfide content in the outlet gas from the tower is greater than 50% and the currently detected hydrogen sulfide content in the outlet gas from the tower is greater than 50 mg / Nm 3 and less than or equal to 100 mg / Nm 3 , or the currently detected hydrogen sulfide content in the outlet gas from the tower is greater than 100 mg / Nm 3 , then increase the soda ash dosage by 20%, otherwise keep the soda ash dosage unchanged.

4. The method for controlling the alkalinity of the wet desulfurization system of coke oven gas according to claim 1, characterized in that, The step of determining the soda ash dosage based on the monitored causticity data of the desulfurization liquid and the hydrogen sulfide data of the gas leaving the tower includes: When the currently monitored causticity data of the desulfurization liquid is within the range of 0.25 to 0.35 mol / L, if the fluctuation range of the currently monitored hydrogen sulfide content in the outlet tower gas relative to the previously monitored hydrogen sulfide content in the outlet tower gas is greater than 50% and the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 50 mg / Nm 3 and the currently monitored hydrogen sulfide content in the outlet tower gas is less than or equal to 100 mg / Nm 3 , or the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , then a command to increase the soda ash dosage by 0.2 tons is issued, otherwise the soda ash dosage is set to 0.

5. The method for controlling the alkalinity of the wet desulfurization system of coke oven gas according to claim 1, characterized in that, The step of determining the soda ash dosage based on the monitored causticity data of the desulfurization liquid and the hydrogen sulfide data of the gas leaving the tower includes: When the currently monitored causticity data of the desulfurization liquid > 0.35 mol / L, if the fluctuation range of the currently monitored hydrogen sulfide content in the outlet tower gas relative to the previously monitored hydrogen sulfide content in the outlet tower gas is greater than 50% or the currently monitored hydrogen sulfide content in the outlet tower gas is greater than 100 mg / Nm 3 , then increase the soda ash dosage by 0.1 ton, otherwise, set the soda ash dosage to 0.

6. The method for controlling the alkalinity of the wet flue gas desulfurization system of coke oven gas according to claim 1, characterized in that, The step of determining the soda ash dosage based on the monitored causticity data of the desulfurization liquid and the hydrogen sulfide data of the gas leaving the tower includes: In the case where the hydrogen sulfide data of the outlet gas from the tower obtained in the most recent three consecutive monitors are all greater than 100 mg / Nm 3 set the preset alkalinity control reference to 0.35 moles per liter; or, When the hydrogen sulfide data of the gas leaving the tower obtained from the last three consecutive monitors is less than or equal to 50 mg / Nm 3 , set the preset alkalinity control reference to 0.2 moles per liter.

7. The method for controlling the alkalinity of the wet desulfurization system of coke oven gas according to claim 1, wherein The step of adjusting the addition amount of alkali added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction includes: Generating a current or voltage control signal according to the soda ash dosage instruction; Controlling the starting duration of the metering pump through the current or voltage control signal to adjust the addition amount of alkali added to the coke oven gas desulfurization system in real time.

8. The method for controlling the alkalinity of the wet flue gas desulfurization system of coke oven gas according to claim 7, characterized in that, The step of adjusting the addition amount of alkali added to the coke oven gas desulfurization system in real time according to the soda ash dosage instruction further includes: When the liquid level of the alkali addition tank is lower than 0.8 m or the liquid level of the reaction tank in the coke oven gas desulfurization system is higher than 3.5 m, automatically stop the operation of the metering pump; the alkali addition tank stores the alkali liquid prepared to be added to the coke oven gas desulfurization system.

9. The method for controlling the alkalinity of the wet desulfurization system of coke oven gas according to claim 1, wherein, The step of real-time monitoring of the causticity data of the desulfurization liquid in the coke oven gas desulfurization system includes: Regularly calibrating the causticity on-line monitoring device according to the standard alkali liquid; the causticity on-line monitoring device is used to monitor and obtain the causticity data of the desulfurization liquid.

10. An alkalinity control system for a wet desulfurization system of coke oven gas, characterized in that, Including: Coke oven gas desulfurization system (20), causticity on-line monitoring subsystem (21), hydrogen sulfide on-line monitoring subsystem (22), causticity automatic regulation subsystem (23) and continuous alkali addition subsystem (24); The causticity on-line monitoring subsystem (21) is connected to the coke oven gas desulfurization system (20), and the causticity on-line monitoring subsystem (21) is used to real-time monitor the causticity data of the desulfurization liquid in the coke oven gas desulfurization system (20); The on-line hydrogen sulfide monitoring subsystem (22) is connected to the coke oven gas desulfurization system (20), and the on-line hydrogen sulfide monitoring subsystem (22) is used to monitor in real time the hydrogen sulfide data of the gas leaving the tower of the coke oven gas desulfurization system (20); The automatic alkalinity regulation subsystem (23) is connected to the on-line alkalinity monitoring subsystem (21), the on-line hydrogen sulfide monitoring subsystem (22) and the continuous caustic soda adding subsystem (24), and is used to receive the desulfurization liquid alkalinity data from the on-line alkalinity monitoring subsystem (21), and receive the hydrogen sulfide data of the gas leaving the tower from the on-line hydrogen sulfide monitoring subsystem (22), determine the caustic soda dosage, and determine the caustic soda dosage instruction according to the caustic soda dosage; The continuous caustic soda adding subsystem (24) is connected to the coke oven gas desulfurization system (20), and is used to adjust in real time the adding amount of the caustic soda added to the coke oven gas desulfurization system (20) according to the caustic soda dosage instruction.

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