Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/02—Shaft or like vertical or substantially vertical furnaces with two or more shafts or chambers, e.g. multi-storey
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2/00—Lime, magnesia or dolomite
  • C04B2/10—Preheating, burning calcining or cooling
  • C04B2/12—Preheating, burning calcining or cooling in shaft or vertical furnaces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/26—Arrangements of controlling devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D19/00—Arrangements of controlling devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D21/00—Arrangement of monitoring devices; Arrangement of safety devices
  • F27D21/0014—Devices for monitoring temperature

Definitions

• the invention relates to a DC countercurrent regenerative lime kiln (GGR lime kiln) and method for operating the same.
• GGR lime kilns are used for burning limestone and according to FIG. 1 consist of at least two shafts 1, 2 which each have a preheating zone V, a firing zone B and a cooling zone K. Both shafts are connected to one another with an overflow channel 3. The material to be burned is fed from above into both shafts and pulled down as burned material.
• Both shafts are operated alternately as a combustion chamber and exhaust shaft, wherein the combustion chamber combustion air are supplied in cocurrent with the material and fuel and the resulting hot exhaust gases are fed together with the supplied from below, heated cooling air through the overflow in the exhaust duct, where the exhaust gases in the countercurrent to the material to be diverted upward and preheat the material.
• the function of the two shafts is reversed, i. the combustion chamber becomes the exhaust shaft and vice versa.
• Fuel fluctuations in the carbonate content of the raw material or variations in the heat losses of the furnace, a readjustment of the amount of fuel may be required.
• Another disturbance is formed by kerogenic constituents, which are often contained in the limestone to be fired. This is a polymeric, organic material which releases hydrocarbons when heated.
• these kerogen are not distributed homogeneously in the raw material, so a re-regulation of the specific heat input of the lime kiln up to 6% is necessary to achieve a constant product quality.
• the product quality is determined primarily by the residual C0 2 content of the quick lime and its reactivity. Both parameters should correspond as constant as possible to the specified reference values. However, these two properties of the lime can so far only be checked on the end product, so that a subsequent control intervention could take place only with a delay of 12 to 16 hours (throughput time of the material).
• a DC regenerative furnace is known for example from DE 29 27 834 AI.
• the measurement and control technology of such a furnace is also described by H. Ruch: "Measurement and control technology during lime burning” in cement-lime gypsum, Issue 6/1973, pages 257-263.
• the invention therefore an object of the invention to provide a method for operating a GGR lime kiln and a GGR lime kiln to ensure a high product quality of the burned lime with high reliability.
• the inventive method for operating a GGR lime kiln with at least two shafts, each having a preheating zone, a combustion zone and a Have cooling zone and an overflow channel connecting the two shafts consists essentially of the following process steps:
• the two shafts are operated alternately as a combustion shaft and exhaust shaft
• the hot gases produced in the combustion chamber reach the exhaust shaft via the overflow channel
• the GGR lime kiln according to the invention consists essentially of
• At least two shafts each having a preheating zone, a firing zone and a cooling zone, wherein the two shafts are operated alternately as a combustion shaft and exhaust shaft,
• a control device which is in communication with the fuel supply device, the combustion air supply device and the measuring device and is designed to control the flame length according to the method according to one or more of the preceding claims.
• the invention is based on the finding that the reactivity of the calcined lime can then be kept as constant as possible if the length of the flame forming in the combustion zone varies as little as possible, ie is also kept as constant as possible.
• the normal flame length 1 is shown, in which form the flames to the lower end of the combustion zone B and just do not reach into the overflow channel.
• the thermal energy is ideally distributed over the entire length of the burning zone of the combustion shaft.
• the excess air is set correctly. Too short a flame length, as darg Robinson in Figure 2, leads to high firing temperatures in the upper part of the combustion zone B and to a product quality with less
• the hot gases characteristic of the flame length parameter can be effected by a temperature measurement, a NOx -Messsung and / or a CO measurement.
• the parameter is determined by a temperature measurement in the area of the overflow channel.
• the average temperature of the hot gases be used in the overflow, taking into account the minimum temperatures of the hot gases in the overflow.
• an adjustable period of time at the beginning and at the end of each burning time entering into the determination expediently remains unconsidered, since these sections often have irregularities and can falsify the result.
• the determination of the average of the minimum temperature of the hot gases in the overflow channel as well as the determination of the average of the temperature of the hot gases can take place over an adjustable number of furnace cycles. In order to reduce variations in the measured values, it is also expedient if the moving average is determined in method steps a) and / or b).
• the amount of combustion air to be supplied is increased if the determined difference from the adjustable setpoint is too large and decreases if the determined difference from the setpoint is too small.
• the amount of fuel to be supplied is increased if the temperature of the hot gases in the overflow channel is too small and correspondingly reduced if the temperature of the hot gases is too high.
• a setpoint is specified, which is suitably adjusted depending on the throughput of the furnace and / or the grain size of the material to be fired. This setpoint is then used to control the amount of fuel and / or the control of the amount of combustion air.
• Fig. 2 is a schematic representation of the GGR lime kiln with too short
• Fig. 3 is a schematic representation of the GGR lime kiln with too long
• Fig. 4 is a representation of the temperature profile in the region of the overflow.
• the two shafts 1, 2 of the lime shaft kiln illustrated in FIGS. 1 to 3 each have fuel feed devices 4, 5 and combustion air feed devices 6, 7.
• the fuel feed devices 4, 5 are formed, for example, by lances which open in the transition area between preheating zone V and combustion zone B in the material bed.
• the cooling zone K is supplied from below via cooling air supply means 8, 9 with cooling air.
• the two shafts 1, 2 fed via not shown supply means from above to burning lime, while the finished burned and cooled material is withdrawn at the bottom of the two shafts, so that the material migrates continuously from top to bottom.
• the throughput time is usually 12 to 24 hours.
• the two shafts 1, 2 are always operated alternately as a combustion shaft and exhaust shaft.
• the shaft 1 is shown as a combustion shaft.
• combustion air and fuel are supplied via the combustion air supply device 6 or via the fuel supply device 4, so that one or more flames F form in the combustion zone B.
• the flame length 1 corresponds to the length of the combustion zone B. In other words, the flames extend straight to the lower end of the intended combustion zone B range.
• the hot exhaust gases produced during combustion and the cooling air supplied from below and heated in the cooling zone K are discharged as hot gases 12 via the overflow channel 3 into the shaft 2 functioning as an exhaust gas shaft.
• the shaft 2 neither combustion air nor fuel supplied. In this way, the hot exhaust gases can flow through the material in the shaft 2 in countercurrent and are discharged via the Abieit responded 11.
• the combustion air and fuel supply in the shaft 1 is turned off and the exhaust gas discharge device 10 is opened.
• the combustion in the shaft 2 is started by supplying fuel via the fuel supply device 5 and supplying combustion air via the combustion air supply device 7.
• the then resulting hot gases are then discharged in the reverse direction via the shaft 1.
• a measuring device 13 is further provided, which may be formed in particular for measuring the NO x content or the CO content of the hot gases 12.
• it is a temperature measuring device for direct or indirect measurement of the temperature of the hot gases A 12.
• thermocouples are used, which are in the flow of hot gases 12 or are arranged in the region of the lining of the overflow channel 3.
• the use of an optical pyrometer with which the temperature of the hot gases is measured indirectly via the measurement of the heat radiation of the lining in the overflow channel is particularly suitable.
• a sudden, very characteristic rash on the measuring device can be detected by the color of the flame, which can be unambiguously and, above all, assigned immediately to the undesired situation.
• the measuring device 13 is connected to a control device 14, which in turn is connected to the fuel feed devices 4, 5 and the combustion air feed devices 6, 7 and serves to regulate the ratio of fuel to the combustion air as a function of the measured value determined by the measuring device.
• the reactivity of the burned lime is directly related to the length of the flame F forming in the burning zone B.
• the reactivity of the calcined lime is in the predetermined desired range (setpoint) when the flames reach the lower edge of the combustion zone B, as shown in Fig. 1. 2 and 3, the operating situation of the lime kiln shown in Fig. 1 at short flame (flame length in Fig. 1) and at too large a flame length (flame length 1 2 in Fig. 3) is shown.
• a change in the flame length is, for example, when the ratio of fuel to combustion air changes. Such a change can already result solely from the liberated at irregular times kerogenic components of the lime, resulting in undesirable fluctuations in the reactivity of the final product.
• the invention proposes to determine a parameter of the hot gases to the earliest possible measurement, which is characteristic of the forming flame length , although a NO x or CO measurement is fundamentally considered, the control due to a temperature measurement has the decisive advantage that no additional measuring devices are required, since a temperature measurement is required anyway.
• the 4 shows the temperature profile measured via the measuring device 13 (upper curve).
• the lower curve indicates which of the two shafts 1 or 2 is burning at a certain time.
• the shaft burns 1 and at 20 the shaft 2.
• a steep rise in temperature follows in each period a steep rise in temperature.
• the temperature profile can be very different from oven to oven and also very irregular.
• the parameter is determined by the difference of the average of the temperature of the hot in the overflow channel and the average of the minimum temperatures of the hot gases forms in the overflow channel.
• This temperature difference .DELTA. ⁇ is then compared with an adjustable setpoint or desired range and used to control the combustion air to be supplied. In this case, the amount of combustion air is increased if the determined difference from the adjustable setpoint / range is too large and reduced if it is too small.
• the desired value for the determined parameter and / or the average temperature of the hot gases in the overflow are expediently adapted to the throughput of the furnace and / or the grain size of the material to be fired.
• the lime kiln can be automatically controlled, whereby an extremely constant reactivity and a constant residual C0 2 content of the end product is achieved.
• the subsequent determination of the properties, such as reactivity or residual C0 2 content then serve only to control.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Structural Engineering (AREA)
• Thermal Sciences (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• Organic Chemistry (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)
• Furnace Details (AREA)
• Muffle Furnaces And Rotary Kilns (AREA)
• Regulation And Control Of Combustion (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)

Priority Applications (11)

Applications Claiming Priority (2)

Publications (1)

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Cited By (23)

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• 2009
  • 2009-12-15 DE DE102009058304A patent/DE102009058304B4/de not_active Withdrawn - After Issue
• 2010
  • 2010-09-15 RU RU2012129962/02A patent/RU2538844C2/ru active
  • 2010-09-15 WO PCT/EP2010/063559 patent/WO2011072894A1/de not_active Ceased
  • 2010-09-15 MX MX2012006908A patent/MX2012006908A/es active IP Right Grant
  • 2010-09-15 CN CN201080053913.XA patent/CN102630294B/zh active Active
  • 2010-09-15 SI SI201030758T patent/SI2478314T1/sl unknown
  • 2010-09-15 US US13/501,341 patent/US9011143B2/en active Active
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  • 2010-09-15 JP JP2012543539A patent/JP5778170B2/ja not_active Expired - Fee Related
  • 2010-09-15 EP EP10755140.0A patent/EP2478314B1/de active Active
  • 2010-09-15 ES ES10755140.0T patent/ES2511055T3/es active Active
  • 2010-09-15 BR BR112012009041-0A patent/BR112012009041B1/pt not_active IP Right Cessation
  • 2010-09-15 MY MYPI2012001598A patent/MY163138A/en unknown
• 2012
  • 2012-04-10 IN IN3079DEN2012 patent/IN2012DN03079A/en unknown

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