CN-121409030-B - Gradient efficient constant-temperature heat exchange process for strong acid electrolyte

CN121409030BCN 121409030 BCN121409030 BCN 121409030BCN-121409030-B

Abstract

The invention discloses a strong acid electrolyte gradient high-efficiency constant-temperature heat exchange process which comprises steam depressurization, primary heating and secondary heating. The invention releases the steam energy in two stages, namely, the primary heating utilizes the latent heat of the steam after depressurization to heat the process water to 80 ℃, and the secondary heating uses 80 ℃ hot water to heat the electrolyte through the titanium plate heat exchanger. The invention utilizes the gas-liquid mixer to inject the acid gas mixture into the electrolyte flow through the negative pressure generated by the vortex paddle to form a gas-liquid two-phase flow, intensifies the heat transfer process, improves the heating speed and one-time heat exchange temperature rise, generates a gas washing effect to greatly reduce the scale formation and blockage of the acid side of the heat exchanger and reduces the cleaning cost, adopts the control system and the optimization algorithm design to realize the process control method with precise control, low energy consumption and high stability, has the emergency treatment capability and predictive maintenance function, and solves a plurality of key problems of efficiency, corrosion, scaling, acid mist recovery and the like in the heating of the strong acid electrolyte.

Inventors

ZHU YUEYUN
KANG QINKE
XIE XIONG
LONG ZHIHUA
LAI HUIQI
LI YING
HUANG RUI
YIN JIAN

Assignees

新邵辰州锑业有限责任公司

Dates

Publication Date: 20260508
Application Date: 20251020

Claims (10)

1. The gradient high-efficiency constant-temperature heat exchange process for the strong acid electrolyte is characterized by comprising the following steps of: S1, steam depressurization The high-pressure steam generated by the steam boiler is subjected to depressurization treatment through a pressure reducer, the steam pressure is monitored in real time through a pressure sensor, and a control host dynamically adjusts the opening of a pressure reducing valve according to a set value to ensure that the pressure fluctuation range is less than or equal to +/-0.2 Bar; s2, first-stage heating The depressurized steam is injected into the liquid surface of the heat preservation water tank, a multipoint temperature sensor TS is arranged in the heat preservation water tank, a control host adjusts the opening of a steam electromagnetic valve through a PID algorithm, wet air generated above the liquid surface of the heat preservation water tank is mixed with acid mist of an electrolysis system in a gas mixing bin, the temperature of the mixed gas is monitored by TIC, and the mixing proportion of the acid mist and the wet air is controlled through a proportional valve; S3, two-stage heating The strong acid electrolyte is pressurized by the acid liquid hydraulic module and then mixed with the acid mixed gas by the gas-liquid mixer to obtain the electrolyte with gas, and the electrolyte is obtained after heat exchange by the titanium plate heat exchanger; the heating process of the S3 adopts the following control strategies: Flow cooperative control, namely monitoring the flow of hot water and electrolyte in real time through a flow switch FS, and controlling a host machine to dynamically adjust the frequency of a water pump; Temperature cascade control, namely, the main loop uses the temperature of the electrolyte outlet as a reference, the auxiliary loop uses the temperature of the hot water inlet as feedback, and the steam supply quantity is adjusted through a PID algorithm; emergency mode, when the electrolyte temperature is lower than 35 ℃, the wet air flow is automatically increased.
2. The strong acid electrolyte gradient efficient constant temperature heat exchange process according to claim 1, wherein the control strategy of S3 is implemented by a control system, the control system comprising the following modules: the control host adopts industrial PLC to match with HMI touch screen, integrates analog input/output module, and receives each sensor signal; The actuating mechanism comprises a steam electromagnetic valve, a water pump frequency converter and a pneumatic regulating valve, which all support 4-20mA signal control; the actuating mechanism specifically comprises the following components: The heating hydraulic module consists of two parallel conveying pipelines, wherein any conveying pipeline is provided with a stop valve and a water pump, and the water pump is provided with a flow switch FS; The acid liquid hydraulic module comprises a stop valve and an acid liquid pump, and the acid liquid pump is provided with a flow switch FS; s2, a stop valve and a steam electromagnetic valve are arranged on a pipeline of the high-pressure steam in the S2; S3, a pressure gauge PG and a temperature display controller TIC are arranged on the water outlet pipe section and the electrolyte outlet pipe section of the titanium plate heat exchanger, the pressure gauge PG is arranged on the water inlet pipe section of the titanium plate heat exchanger, a temperature sensor TS is arranged below the liquid level of the heat preservation water tank, and electromagnetic valves are arranged on the electrolyte inlet pipe section and the electrolyte outlet pipe section of the titanium plate heat exchanger; and a flow valve for heating the hydraulic module and the acid hydraulic module.
3. The strong acid electrolyte gradient efficient constant temperature heat exchange process according to claim 2, wherein the control system comprises the following algorithm model: (1) Multivariable predictive control model Establishing a dynamic mathematical model of the heat exchange system, taking steam pressure P steam , hot water flow F water and electrolyte inlet temperature T in-acid as input variables, and taking electrolyte outlet temperature T out (T) as target variables, wherein T out (t)=f(P steam ,F water ,T in-acid ) +epsilon; Where ε is the error term and includes all factors that lead to a difference between the model predicted value f (P steam ,F water ,T in-acid ) and the true measured value T out (T); Adopting a rolling optimization algorithm, predicting the temperature trend of 5 minutes in the future every 30 seconds, and adjusting the action of an executing mechanism in advance; (2) Adaptive PID parameter tuning Aiming at the nonlinear characteristics of the heat exchanger, a fuzzy self-adaptive PID controller is designed: Partitioning the deviation e and the deviation change rate e c , and performing strong proportional action, integral action or differential action according to the situation, so that the control parameters of the system can be automatically adjusted when the system characteristic changes or greatly interferes; (3) Energy efficiency optimization algorithm Calculating the thermal efficiency of the system in real time: ; Wherein eta is energy utilization efficiency, Q acid is heat absorbed by acid, Q steam is heat released by steam, F acid is mass flow of acid, c p is constant pressure specific heat capacity of acid, T out-acid is outlet temperature of acid, T in-acid is inlet temperature of acid, F steam is mass flow of steam, h steam is vaporization latent heat of steam; setting a self-adaptive threshold value, namely automatically triggering a cleaning prompt or adjusting a gas-liquid mixing ratio if eta is lower than the set threshold value, wherein the threshold value of the cleaning prompt is not fixed; When the efficiency is reduced, the system can not only alarm, but also give a preliminary reason diagnosis based on the correlation analysis.
4. The strong acid electrolyte gradient efficient constant temperature heat exchange process according to claim 3, wherein the mechanism of the rolling optimization algorithm is as follows: ① The state estimation, wherein the control system utilizes the latest sensor data every 30 seconds to estimate the internal state of the model in real time through a Kalman filter so as to correct the model error; ② The optimizing device takes 'stabilizing the outlet temperature of the electrolyte at a set value' as a main target, and simultaneously takes 'minimum steam consumption' as an economic target, and calculates a series of optimal future control actions including the opening degree of a steam valve and the variation of the frequency of a water pump; ③ And performing and feeding back, namely performing the calculated first step control action only, and then repeating the whole process in the next sampling period.
5. A strong acid electrolyte gradient high efficiency constant temperature heat exchange process according to claim 3, wherein the adaptive PID parameter tuning comprises the following steps: Dividing the temperature deviation |e| and the deviation change rate |e c | into three fuzzy sets of large, medium and small, wherein e c is the change rate between the two adjacent detected temperature deviations e, the large of the |e| is a set of >5 ℃, the medium of the |e| is a set of 1-5 ℃, the small of the |e| is a set of <1 ℃, the large of the |e c | is a set of >10%, the medium of the |e c | is a set of 1-10%, and the small of the |e c | is a set of < 1%; Wherein e=t setpoint -T actual ,T setpoint is a set temperature value, T actual is an actual temperature value, namely an electrolyte outlet temperature value measured by a temperature sensor TIC in real time; when |e|E is 'big', a strong proportion effect is adopted, namely K p is greatly increased, and deviation is rapidly eliminated; When |e|epsilon "medium" and |e c |epsilon "small", K p is reduced, proper integral action is introduced, and static difference is eliminated smoothly; when |e|epsilon 'small' and |e c |epsilon 'large', the differential action is increased, and overshoot is restrained; And (3) resisting integral saturation, namely suspending the integral action by the algorithm when the actuating mechanism reaches the limit position and the deviation is not eliminated, and preventing the large overshoot during recovery.
6. The strong acid electrolyte gradient efficient constant temperature heat exchange process according to claim 2, wherein the control system further provides the following multi-level safety protection means: the primary equipment layer is used for protecting the frequency converter of key equipment from overcurrent and overload; Secondary process layer: The low flow interlock is that any flow switch FS detects that the flow is lower than 50% of rated value, immediately triggers an emergency stop sequence, namely, cuts off a steam electromagnetic valve, stops a related pump and activates an emergency cooling system; High temperature interlocking, namely immediately cutting off a heat source when the temperature of an electrolyte outlet exceeds 60 ℃ or the temperature of a heat preservation water tank exceeds 90 ℃; pressure interlocking, namely, when the steam pressure exceeds a safety limit value or the pressure difference delta P of the titanium plate heat exchanger is continuously higher than 0.15MPa, the system alarms and automatically operates in a load-reducing mode or stops; And the third-level system layer is that a HIM panel of the control host is provided with a one-key emergency stop button, and all interlocking events are recorded in detail, including trigger time, trigger points and action results, and are used for post analysis.
7. The strong acid electrolyte gradient efficient constant temperature heat exchange process according to claim 6, wherein the safety protection means further comprises the following intelligent emergency modes: ① If the electrolyte flow suddenly drops, immediately cutting off the steam supply and starting emergency cooling; ② When the pressure difference delta P of two sides of the titanium plate heat exchanger is more than 0.1MPa, judging the blocking risk, automatically reducing the flow and giving an alarm; ③ When the control system detects that the temperature of the acid side inlet of the titanium plate heat exchanger is continuously lower than 35 ℃, the system automatically judges that primary heating is insufficient, and at the moment, the system can perform the following operations of gradually opening a wet air inlet proportional valve of a gas mixing bin; ④ If the temperature can not be raised within the set time, an alarm of 'the initial temperature of the electrolyte to be checked' is sent to the central control room, and the production load is reduced so as to maintain the stable outlet temperature.
8. The strong acid electrolyte gradient efficient constant temperature heat exchange process according to claim 1 is characterized in that the gas-liquid mixer comprises a cyclone bin (1), the cyclone bin (1) comprises a circular cyclone region at the lower part and an inverted cone-shaped air inlet region at the upper part, a vortex paddle (2) is connected at the center of the cyclone region through a rotating shaft, an electrolyte inlet pipe (3) and an electrolyte outlet pipe (4) are tangentially connected to the outer ring of the cyclone region, and an air inlet pipe (5) is connected to the top of the air inlet region; The vortex paddle (2) is inclined at 30-45 degrees, the vortex paddle (2) is driven to rotate by the pressurized electrolyte, and vacuum in an air inlet area is caused, so that the acid mixture in the gas mixing bin is led into the cyclone bin (1) to be mixed with the electrolyte, and the electrolyte with gas is obtained, wherein the volume ratio of the gas to the liquid in the electrolyte with gas is 0.05-0.08:1.
9. The strong acid electrolyte gradient high-efficiency constant temperature heat exchange process according to claim 1 is characterized in that an electrolyte outlet pipe (4) of the gas-liquid mixer is directly connected with an electrolysis system through a pipeline, and when the temperature of the gas electrolyte in the electrolyte outlet pipe (4) reaches 45-50 ℃, the gas electrolyte is directly connected into the electrolysis system for emergency use; the wet air inlet pipe, the acid mist inlet pipe and the outlet pipe of the gas mixing bin are all provided with one-way valves.
10. The gradient high-efficiency constant-temperature heat exchange process of the strong acid electrolyte according to claim 1 is characterized in that seamless steel pipes are adopted as conveying pipelines of steam and hot water in S1, S2 and S3, and a PP material is adopted as a strong acid electrolyte pipeline in S3; The electrolytic system is also connected with an electrolyte replenishing tank through a pipeline.

Description

Gradient efficient constant-temperature heat exchange process for strong acid electrolyte Technical Field The invention relates to the technical field of acidic wet electrolysis, in particular to a gradient efficient constant-temperature heat exchange process of a strong acid electrolyte. Background In industrial processes such as electrolysis, electroplating, hydrometallurgy, etc., it is often necessary to heat the electrolyte of strong acids (e.g., sulfuric acid, hydrochloric acid, mixed acids) to maintain optimal reaction rates and process stability. However, the high corrosiveness of strong acid media presents a serious challenge to the safety and durability of the heating scheme. At present, two main heating modes of strong acid electrolyte are: 1) Direct steam heating, namely directly introducing steam into an electrolyte tank. The method has the advantages of high heat exchange efficiency and low equipment investment, but has the fatal defects that high-temperature and high-speed steam can severely impact and corrode an injector and a pipeline, so that the service life of equipment is extremely short, meanwhile, steam condensate water can dilute electrolyte to influence the process concentration, acid supplementing needs to be frequently regulated, the operation complexity is increased, and potential safety hazards exist. 2) And the indirect heat exchanger is used for heating, namely a plate-type or tube-type heat exchanger is adopted, and hot water or steam is used as a heating medium for indirectly heating the electrolyte. This approach, while avoiding the dilution problem, still faces the following challenges: ① The problems of low heat exchange efficiency and scaling are that the viscosity of the strong acid electrolyte is higher, and a stable laminar flow thermal boundary layer is easy to form on the heat exchange wall surface, which is the main resistance of heat transfer. Resulting in low heat exchange efficiency, a higher heat medium temperature or a larger heat exchange area is often required. In addition, the trace impurities possibly contained in the acid liquor are easy to deposit and scale on the wall surface, so that the efficiency is further reduced, frequent shutdown and cleaning are required, and the continuous production is influenced. ② The material cost and corrosion risk are that high-grade corrosion-resistant materials (such as titanium, hastelloy, tantalum and the like) are required to be adopted at the contact part of the heat exchanger in order to resist acid liquor corrosion, so that the cost is high. Once the heat exchanger is broken and leaked, expensive heating media (such as steam) or softened water enters an electrolysis system or acid liquor leaks out, so that great economic loss and safety accidents are caused. In addition, acid mist is usually generated in the electrolysis process, and direct discharge can corrode factory equipment, harm personnel health and pollute the environment. The existing acid mist treatment mostly adopts an independent alkali liquor spray tower, which is a terminal treatment mode, and chemical products are required to be consumed and wastewater is generated, so that the recycling of resources can not be realized. ③ The heat exchange temperature control difficulty is high, the accuracy is low, because the heat transfer wall heating mode is adopted, the flow and the flow velocity of a heating medium are often changed or the heat transfer wall area is often changed in the aspect of heat control only by production experience, the control mode often has overheat or supercooling phenomenon, the control hysteresis effect is very prominent, the defects of high energy consumption, inaccurate temperature, large fluctuation and the like are caused, and meanwhile, when various emergency conditions (such as suddenly reduced heating efficiency, equipment limit conditions and the like) and technological risks are faced, obvious and effective emergency treatment capacity and predictive maintenance functions are not provided. Therefore, a new process for heating the strong acid electrolyte, which can realize efficient heat exchange, long-term safety of equipment, low maintenance operation, resource recycling and intelligent operation, is urgently needed in the field. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a gradient high-efficiency constant-temperature heat exchange process for a strong acid electrolyte. In order to achieve the above purpose, the present invention adopts the following technical scheme: a strong acid electrolyte gradient high-efficiency constant temperature heat exchange process comprises the following steps: S1, steam depressurization The high-pressure steam generated by a steam boiler is subjected to depressurization treatment through a pressure reducer, and the required vapor pressure is 3-5Bar, for example, under the rated working condition, the steam pressure is reduced from the init