Water spraying amount control system for primary high-temperature flue gas spray cooling tower of electric furnace

Abstract

The utility model provides a water spraying amount control system for a primary high-temperature flue gas spray cooling tower of an electric furnace, relates to the technical field of flue gas purification of the electric furnace, and aims to solve the problem that most of existing projects use a conventional control method for adjusting the water spraying amount according to a single temperature value of an outlet of the spray cooling tower. The problems of slow water spraying reaction (water spraying hysteresis), inaccurate temperature value caused by local supercooling or superheating due to non-uniform flue gas distribution, large temperature fluctuation of an outlet of a spray tower, serious scaling and hardening of smoke dust in the spray tower and a tower outlet pipeline, and increase of use and maintenance cost generally exist in the prior art, including a combustion settling chamber, a combustion chamber, a combustion chamber and a combustion chamber. A flue gas inlet dust removal pipeline is installed at the top of the left side of the combustion settling chamber, a steel structure stand column is installed at the top of the right side of the combustion settling chamber, and a cooling tower is installed on the steel structure stand column through a supporting base.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of electric furnace flue gas purification, especially relates to a kind of electric furnace primary high-temperature flue gas spray cooling tower water spraying control system. BACKGROUND

[0002] With the increasingly strict requirement of the state to environmental protection, the emission problem of dioxin in the process of electric furnace steelmaking also gradually attracts attention. The pollution prevention best technology proposed in the "Best Feasible Technology Guide for Pollution Prevention of Steelmaking Process in Steel Industry" issued by the State Environmental Protection Department is "flue gas quenching" and "high-efficiency filtration".

[0003] The electric furnace steelmaking process in China usually adopts the dust removal mode of "electric furnace fourth hole (horizontal charging electric furnace preheating section flue gas outlet) - heat preservation flue - combustion settling chamber - heat preservation flue - spray cooling cooling tower - dust removal air pipe - high-efficiency bag-type dust collector - dust removal fan - exhaust cylinder discharge". As the core equipment of the electric furnace primary high-temperature flue gas treatment system, the water spraying control of the spray cooling tower directly affects the dust removal efficiency of the subsequent high-efficiency bag-type dust collector. According to the heat balance equation, the water spraying amount in the spray cooling tower is related to the electric furnace flue gas temperature. The conventional control method currently used in most projects is to adjust the water spraying amount according to the single temperature value at the outlet of the spray cooling tower. There are problems such as slow water spraying reaction (hysteresis), inaccurate temperature value due to local overcooling or overheating caused by uneven distribution of flue gas, etc. The outlet temperature of the spray tower fluctuates greatly, and the dust in the spray tower and the outlet pipe is seriously scaled, which increases the use and maintenance cost. Therefore, it is particularly important to design a kind of electric furnace primary high-temperature flue gas spray cooling tower water spraying control system to solve the above technical problems. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims to solve the problem that most existing projects use the conventional control method of adjusting the water spraying amount according to the single temperature value at the outlet of the spray cooling tower, and the problem of slow water spraying reaction (hysteresis) and inaccurate temperature value due to local overcooling or overheating caused by uneven distribution of flue gas, and proposes a kind of electric furnace primary high-temperature flue gas spray cooling tower water spraying control system.

[0005] In order to achieve the above object, the utility model discloses the following technical scheme: a kind of electric furnace primary high-temperature flue gas spray cooling tower water injection quantity control system, including combustion settling chamber, the left side top position of combustion settling chamber is equipped with flue gas inlet dust removal pipeline, the right side top of combustion settling chamber is equipped with steel structure stand, the cooling tower is installed by support seat with steel structure stand, the bottom of cooling tower is communicated with the combustion settling chamber, the top of cooling tower is equipped with flue gas outlet dust removal pipeline, a thermocouple temperature sensor is installed in the flue gas inlet dust removal pipeline, a group of thermal resistance temperature sensors are installed in the flue gas outlet dust removal pipeline.

[0006] Preferably, a plurality of spray lances are installed on the cooling tower.

[0007] Preferably, a manhole door is installed above the spray lances.

[0008] Preferably, a water source interface is installed on the spray lances, and a gas source interface is installed on the right side of the water source interface.

[0009] Preferably, the thermocouple temperature sensor monitors the high-temperature flue gas temperature T1 entering the spray cooling tower, and the thermal resistance temperature sensor monitors the flue gas temperature T2 after the high-temperature flue gas is rapidly cooled in the spray cooling tower.

[0010] Compared with the prior art, the utility model has the advantages and positive effects that, in use, the system of the utility model can effectively reduce the measurement error of the outlet flue gas temperature difference, reduce the outlet temperature fluctuation, reduce the fluctuation range of the water injection quantity, reduce the maintenance cost of the equipment, and solve the problems of slow water injection response (water injection hysteresis exists), inaccurate temperature values caused by local overcooling or overheating due to uneven flue gas distribution, and the like, which are common in conventional control methods that adjust the water injection quantity based on a single temperature value at the outlet of the spray cooling tower. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a whole view of the electric furnace primary high-temperature flue gas spray cooling tower water injection quantity control system of the utility model.

[0012] Figure 2 It is a local structure schematic view of a spray lance connection point in the electric furnace primary high-temperature flue gas spray cooling tower water injection quantity control system of the utility model.

[0013] Figure 3 It is a spray lance distribution structure schematic view in the electric furnace primary high-temperature flue gas spray cooling tower water injection quantity control system of the utility model.

[0014] Figure 4The utility model discloses a water spraying amount logical flow chart. Legend: 1, combustion settling chamber;2, flue gas inlet dust removal pipeline;3, steel structure stand;301, support seat;4, cooling tower;401, spray spray gun;402, manhole door;403, water source interface;404, gas source interface;5, flue gas outlet dust removal pipeline;6, thermocouple temperature sensor;7, thermal resistance temperature sensor. DETAILED DESCRIPTION

[0015] In order to more clearly understand the above-mentioned purpose, features and advantages of the utility model, the utility model is further described below in combination with drawings and examples. It should be explained that the examples and features in the examples of the present application can be combined with each other without conflict.

[0016] In the following description, a lot of specific details are set forth in order to fully understand the utility model, but the utility model can also be implemented in other ways different from the description, therefore, the utility model is not limited to the specific examples disclosed in the following description.

[0017] The utility model provides a kind of electric furnace primary high-temperature flue gas spray cooling tower water spraying control system, electric furnace primary high-temperature flue gas spray cooling tower 4 water spraying control system, including combustion settling chamber 1, the left side top position of the combustion settling chamber 1 is equipped with flue gas inlet dust removal pipeline 2, the right side top of the combustion settling chamber 1 is equipped with steel structure stand 3, the steel structure stand 3 is equipped with cooling tower 4 by support seat 301, the bottom of the cooling tower 4 is connected with the combustion settling chamber 1, the top of the cooling tower 4 is equipped with flue gas outlet dust removal pipeline 5, one thermocouple temperature sensor 6 is installed in the flue gas inlet dust removal pipeline 2, a group of thermal resistance temperature sensors 7 are installed in the flue gas outlet dust removal pipeline 5, still be equipped with multiple spray spray guns 401 on the cooling tower 4, the top of the spray spray gun 401 is equipped with manhole door 402, still be equipped with water source interface 403 on the spray spray gun 401, the right side of the water source interface 403 is equipped with gas source interface 404, the thermocouple temperature sensor 6 monitored is the high-temperature flue gas temperature T1 of the spray cooling tower 4, the high-temperature flue gas temperature T2 after the high-temperature flue gas in the spray cooling tower 4 rapid cooling is monitored by the thermal resistance temperature sensor 7;

[0018] 1 temperature sensor thermocouple (armored K type, range 0~1300 DEG C) is arranged on the dust removal pipeline of the flue gas inlet of spray cooling tower 4, for detecting the high-temperature flue gas temperature (T1) of the spray cooling tower 4 into the spray cooling tower 4.

[0019] A group of temperature sensor redundant PT100 thermistor (range 0~500℃) is arranged on the dust removal pipeline of the flue gas outlet of the spray cooling tower, for monitoring the temperature T2 (T2a, T2b) of the flue gas after rapid cooling in the spray cooling tower 4. The temperature sensor installed on the dust removal pipeline of the flue gas outlet of the spray cooling tower 4 may not be uniform due to different positions of the flue gas flow rate and temperature distribution, resulting in differences between the two measured values, especially in the presence of local airflow disturbance. Therefore, the weighted average method in the data fusion algorithm is used to process the data of the double temperature sensors, which can eliminate the influence of local airflow disturbance.

[0020] The calculation formula of the outlet high-temperature flue gas temperature T2 of the spray cooling tower with water spraying amount:

[0021] T2=K1T 2a +K2T 2b

[0022] T2- the outlet high-temperature flue gas temperature of the spray cooling tower for calculating the water spraying amount

[0023] T 2a - the high-temperature flue gas temperature detected by the first PT100 thermistor at the outlet of the spray cooling tower, T 2b - the high-temperature flue gas temperature detected by the second PT100 thermistor at the outlet of the spray cooling tower, K1, K2- weight coefficients, which are determined by analyzing the flow rate, turbulence, temperature distribution, etc. of the flow field simulation through three-dimensional modeling of the airflow in the spray cooling tower by computational fluid dynamics (CFD) software.

[0024] The water spraying amount W calculated according to the heat balance formula:

[0025]

[0026] W- the required water spraying amount calculated by the conventional theory, Qg- the heat release amount of high-temperature flue gas, r- the latent heat value of water at 100℃, Cw- the mass specific heat capacity of water, Cv- the mass specific heat capacity of water vapor at 100℃, Tw- the temperature of the spray water, T2- the outlet high-temperature flue gas temperature of the spray cooling tower (after weighted average processing).

[0027] The spray cooling tower is subject to large thermal load changes, so the temperature difference between the inlet and outlet will fluctuate within a certain range, and the conventional control system has a lagging response, resulting in large outlet temperature fluctuations. The introduction of a feedforward compensation mechanism in the control system can adjust the water spraying amount in advance according to the size of the temperature difference, avoiding outlet temperature overshoot or fluctuations. △T

[0028] W 总= W+W1

[0029] ​W1 = α. (△T - T3)

[0030] △T=T2-T1

[0031] In the formula W 总 - Corrected total spray volume

[0032] W-Conventional theoretical calculation of required spray volume

[0033] W1 - Feedforward compensation spray volume

[0034] α-compensation coefficient

[0035] T2 - High-temperature flue gas temperature at the outlet of the spray cooling tower (after weighted average processing)

[0036] T1-Spray Cooling Tower Inlet High-Temperature Flue Gas Temperature

[0037] T3 - Threshold for initiating feedforward compensation

[0038] Note: The compensation coefficient α is a value used to control the adjustment range of the compensation flow. Generally, it needs to be continuously improved and perfected by using accumulated practical engineering data experience. The threshold T3 for starting feedforward compensation is determined by recording the outlet temperature response under different ΔT during system thermal inertia testing.

[0039] Example 1

[0040] Let dT / dt be the differential term in the control system. In the spray cooling tower water volume control system, dT / dt represents the rate of change of the spray cooling tower outlet temperature T2 with time, that is, the change in the outlet flue gas temperature of the spray cooling tower per unit time (unit: ℃ / s).

[0041]

[0042] In the formula, T2(t) represents the current outlet temperature of the spray cooling tower (after weighted average processing).

[0043] T2(t-Δt) - The outlet temperature of the spray cooling tower at the previous sampling time (after weighted average processing)

[0044] Δt - Sampling time interval (must be longer than the temperature sensor response time, 1~2 seconds is recommended)

[0045] The spray cooling tower water volume control system senses the acceleration (dT / dt) of temperature changes and adjusts the water pump motor frequency in a timely manner to avoid temperature fluctuations caused by the lag of conventional control systems.

[0046] When dT / dt is negative, it indicates that the outlet temperature of the spray cooling tower is dropping rapidly. The water spray control system needs to reduce the water spray volume in advance to prevent overcooling from causing condensation or scaling.

[0047] When dT / dt is positive, it means that the outlet temperature of the spray cooling tower does not reach the expected cooling rate, and the water spray amount needs to be increased to accelerate the cooling.

[0048] Parameter Action dimension Control focus △T Current temperature difference Steady-state accuracy control dT / dt Change trend Dynamic response and stability

[0049] Beneficial effects:

[0050] The following table is the data comparison of the spray cooling tower water spray control system before and after the reconstruction of the 120-ton electric furnace steelmaking unit in the ultra-low emission reconstruction project of a steel plant.

[0051] Project Conventional control system Optimized control system Spray tower outlet temperature measurement error ±15℃ ±5℃ Spray tower outlet temperature fluctuation range ±25℃ ±8℃ △T sudden increase to 60℃ Outlet temperature first rises to 300℃ and then falls Outlet temperature stabilizes at 260±5℃ Change of water injection amount From 10m³ / h to 18m³ / h From 10m³ / h to 15m³ / h Water injection consumption (average) 20.5m³ / h 16.7m³ / h Fouling rate in the spray tower and pipeline 3.2mm / month 0.8mm / month Moisture content of coarse ash at the bottom of the spray tower 8% 3% Equipment wear and tear Frequent start-stop of water pump, shortening of service life Smooth operation, reduction of maintenance cost

Claims

1. An electric furnace primary high-temperature flue gas spray cooling tower water injection amount control system comprising a combustion settling chamber (1), characterized in that, The left top of the combustion settling chamber (1) is provided with a flue gas inlet dust removal pipeline (2), the right top of the combustion settling chamber (1) is provided with a steel structure column (3), the steel structure column (3) is provided with a cooling tower (4) through a support base (301), the bottom of the cooling tower (4) is communicated with the combustion settling chamber (1), the top of the cooling tower (4) is provided with a flue gas outlet dust removal pipeline (5), a thermocouple temperature sensor (6) is arranged in the flue gas inlet dust removal pipeline (2), a group of thermal resistance temperature sensors (7) are arranged in the flue gas outlet dust removal pipeline (5).

2. The once-through flue gas spray cooling tower water injection control system of claim 1, wherein, A plurality of groups of spray lances (401) are further arranged on the cooling tower (4).

3. The once-through flue gas spray cooling tower water injection control system of claim 2, wherein, An inspection manhole door (402) is arranged above the spray lance (401).

4. The once-through flue gas spray cooling tower water injection control system of claim 2, wherein, A water source interface (403) is further arranged on the spray lance (401), and a gas source interface (404) is arranged on the right side of the water source interface (403).

5. The once-through flue gas spray cooling tower water injection control system of claim 1, wherein, The thermocouple temperature sensor (6) monitors the high-temperature flue gas temperature T1 entering the spray cooling tower (4), and the thermal resistance temperature sensor (7) monitors the temperature T2 of the flue gas after the high-temperature flue gas is rapidly cooled in the spray cooling tower (4).

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