Khd Pyro Process: Complete Technical Guide

The KHD pyroprocess is the complete burning line of the Humboldt tradition: the two-string cyclone preheater, the precalciner where the calcination leaves the kiln, the rotary kiln that finishes the sintering, and the PYROFLOOR cooler that recovers the heat: the pyroprocess is the thermal heart of the cement plant: the place where the raw meal becomes the clinker: the flue of the plant: 100% of the clinker runs through this line, and the heat consumption of the whole factory is decided here: the engineers of the pyro line speak the language of the temperatures, the pressures, the gas flows and the free lime: the KHD pyroprocess is their subject and this guide is their map.

The Complete Cement Technical Package (931 files including the books, the courses, the Excel tools and the presentations: $249.99 one-time: instant download via the PayPal payment) includes this pyroprocess guide with its flow sheets, the design figures, the tables and the operation checklists: the logarithm of the knowledge for the process engineers, the production managers and the operators of the pyro line: this article walks the file: the architecture of the Humboldt line, the cyclones, the calciners, the kiln, the cooler, the process data, the control and the maintenance: the reader leaves with the complete map of the KHD pyroprocess in hand.

The KHD pyroprocess is not one machine but a tightly coupled chain: the preheater exchanges the heat of the gas against the raw meal, the calciner performs 90 to 95% of the decarbonation, the kiln sinters the last of the reaction, and the cooler quenches the clinker and preheats the combustion air: each part changes the feed and the conditions of the next: the process engineer who understands the chain understands the plant: this page is organized so that the beginner finds the architecture first, the equipment second, and the operation and the trouble cases last: the file itself follows the same order: the reader can follow the article with the document in hand.

1. The Architecture of the KHD Pyroprocess: The Humboldt Line

The KHD (Klöckner-Humboldt-Deutz) tradition of pyroprocessing grew from the Humboldt dryer and suspension technology into one of the complete line concepts of the industry: the line that carries the PYROCLON name covers the equipment from the raw meal silo to the clinker store:

• The PYROCLON preheater: the two-string cyclone tower with the suspension heat exchange in countercurrent gas and solids flow: the meal enters cold at the top string and leaves at 820 to 860 °C at the bottom;
• The PYROCLON-R precalciner: the calciner vessel between the bottom cyclones where the fuel burns with the tertiary air and raises the calcination degree to 90 to 95% before the kiln: the heart of the modern decarbonation;
• The rotary kiln: the long inclined-drum reactor where the last 5 to 10% of the calcination ends and the sintering of the alite begins: the burning zone at 1400 to 1450 °C;
• The PYROFLOOR cooler: the grate cooler with the walking floor plates that quench the clinker from about 1400 °C to about 100 °C and recover the heat into the secondary, the tertiary and the drying air;
• The tertiary air duct: the hot air pipe from the cooler roof to the calciner that provides the oxygen of the second combustion and reduces the NOx of the system;
• The bypass: the optional extraction of the kiln exit gas to remove the chlorides and the alkalis from the circulating load: the alkali barrier of the line;
• The firing system: the PYROJET multifuel burner at the kiln nose and the firing lances of the calciner: the gas, the coal, the petcoke and the alternative fuels: the fuel flexibility of the line;
• The kiln gas circuit: the ID fan at the tower top that draws the whole system under controlled suction: the driver of the gas flows and of the pressure profile;

The architecture shows the KHD philosophy: the calcination moved out of the kiln and into the precalciner, the refractory duty of the kiln reduced, and the production capacity increased per kiln diameter: the lines of today burn 3,000 to 12,000 tonnes of clinker per day with the single tower: the two strings of the cyclone tower feed one kiln: the design numbers of the strings appear in the sections that follow.

2. The PYROCLON Preheater: The Two Strings and the Suspension

The PYROCLON preheater is the vertical heat exchanger of the line: the raw meal drops through the rising gas stream, is dispersed by the gas at each cyclone inlet, exchanges the heat in milliseconds of contact, and is separated again by the next cyclone: the four to five stages of the tower give the gas a cascade of solids to heat:

• Stage order: the standard PYROCLON tower runs 4 to 5 two-string stages: the meal in at the top stage at 60 to 90 °C, the gas exit at 280 to 340 °C, the meal out of the lowest stage at 820 to 860 °C;
• The two strings: the tower splits into two parallel paths (strings A and B) below the top stages: the kiln gas goes to one string, the calciner gas to the other: the strings even the residence time and the pressure of the gas;
• The pendulum flaps: the seal flaps on the cyclone outlets maintain the cyclone closure against the gas suction during the flow surges: the constant seal of the solids legs;
• The gas ducts: the vertical riser ducts between the stages carry the gas at 14 to 22 m/s: the velocity lifts and disperses the meal: the duct is the true heat exchanger, the cyclone only the separator;
• The PYROCLON wall: the semicalcined meal builds a self-protecting coating on the duct walls above the calciner, allowing the external insulation and reducing the heat losses: the design signature of the KHD calciner area;
• The PYROTOP stage: the high-efficiency top cyclone of the family separates the finest dust to keep the dust emission of the preheater gas low: the good separation protects the ID fan and the filter;

The preheater works because of the enormous contact area of the dispersed meal: one kilogram of the meal at 30 microns presents hundreds of square meters of heat exchange surface: the suspension heat exchange is fast, the pressure drops are the price, and the cyclone efficiency decides the heat losses of the line: the temperatures of the tower measure the health of the whole pyroprocess: the tower profile is the first page the process engineer opens every morning.

3. The Cyclone Design Figures of the PYROCLON: The Separation and the Pressure

The cyclones of the preheater are not structural boxes but process instruments: their separation efficiency decides the dust recirculation, the heat losses and the fan power of the line: the classical design figures of the pyro cyclones summarize the engineering:

Design parameter	Typical value	Effect on the line
Gas velocity at the cyclone inlet	14 – 22 m/s	Separation efficiency versus pressure drop
Gas velocity in the cyclone body	4 – 6 m/s	Stable vortex, low erosion of the shell
Pressure drop per cyclone stage	600 – 1200 Pa	Total tower draft 3500 to 6500 Pa
Separation efficiency per stage	85 – 95%	Heat losses and dust circulation
Diameter of the cyclone body	2.5 – 6 m	Determined by the gas flow of the stage
Meal residence in the riser	1.5 – 3 s	Time for the heat exchange and the reactions

Two facts about the cyclone matter to the operator: first, the pressure drop rises with the square of the gas velocity, so every uncontrolled gas flow increase costs fan power and risks the dust recirculation; second, the separation efficiency controls the heat economy, because every percent of the dust carried with the gas bypasses the countercurrent exchange and wastes heat to the stack: the PYROTOP stage and the calibrated inlet velocities keep both figures in the design envelope: the process engineer reads the draft of each stage from the instrument and knows exactly where the dust loading sits.

4. The PYROCLON-R Precalciner: The Calcination Leaves the Kiln

The precalciner is the vessel where the kiln was relieved: the fuel burns in suspension with the hot meal, the calcination reaction CaCO3 to CaO and CO2 runs at 850 to 900 °C, and the kiln receives the meal already 90 to 95% decarbonated: the result is the modern capacity: the same kiln shell with double the clinker:

• The position: the PYROCLON-R sits in the riser duct between the lowest cyclone and the kiln feed chute: the meal drops in from the cyclone, the kiln gas rises from below, the tertiary air enters from the side: the three streams meet in the vessel;
• The calcination reaction: the limestone decomposes endothermically: about 1780 kJ per kg of the pure CaCO3: the calciner fuel supplies exactly this heat, which explains the fuel split of the modern line: 55 to 65% of the total fuel in the calciner, 35 to 45% at the kiln burner;
• The temperature profile: the calciner exit gas runs 850 to 880 °C: above this the energy is wasted, below this the decarbonation falls: the calciner exit temperature is the setpoint that balances the fuel, the air and the feed;
• The LowNOx operation: the tertiary air enters below the fuel injection in the staged design: the lower part of the vessel burns fuel-rich at low oxygen, the upper part finishes the combustion: the NOx of the calciner fuel is held below 200 to 400 mg/Nm3 by the staging itself;
• The retention volume: the vessel volume gives the solids 6 to 15 seconds of residence: the calcination kinetics need the time at temperature: the volume of the calciner is the capacity of the line;
• The CO2 atmosphere: the high CO2 partial pressure inside the vessel slows the decarbonation, which is why the temperature and the retention time are designed together: the equilibrium of the calcination;

The precalciner changed the mass balance of the kiln: the kiln gas now carries 30 to 40% of the total combustion gas of the line, and the rest leaves through the calciner: the two gas streams must be balanced in the design, because the kiln string and the calciner string of the preheater handle the two halves of the flow: the operator watches the two drafts, the two temperatures and the single calcination degree: the balance of the strings is the daily art of the pyro line.

5. The Combustion and the NOx of the PYROCLON-R: The Staged Flame

The NOx of the pyroprocess forms mostly by the thermal mechanism in the flame of the kiln burner and by the fuel mechanism in the calciner: the KHD LowNOx design attacks both, and the control figures of the line follow the well-known band of the industry:

NOx formation path	Mechanism	Typical share in a kiln line
Thermal NOx	N2 + O2 at flame temperatures above 1600 °C	60 – 70% of the kiln burner NOx
Fuel NOx	Nitrogen of the fuel oxidized in the flame	Dominant in the calciner flame
Prompt NOx	Radical CH reactions in the fuel-rich core	Small share at the kiln burner

The control levers of the operator follow the mechanisms:

• The flame shaping: the PYROJET burner momentum and the swirl create the short intense flame with the internal recirculation: the peak temperature lowered by 100 to 200 degrees without losing the sintering heat: the thermal NOx drops;
• The staged calciner: the fuel-rich lower zone of the PYROCLON-R reduces the NOx already formed in the kiln gas and keeps the fuel NOx low: the reducing zone of the vessel is the NOx filter of the line;
• The oxygen control: the kiln exit O2 held at 1.5 to 2.5% and the calciner excess air at 2 to 3%: every extra oxygen above the need feeds the NOx: the minimum excess air is both the economy and the emission control;
• The kiln gas recirculation: the option of returning a share of the preheater exit gas into the kiln flame dilutes the combustion: the derating trade-off: applied where the permit demands the single digit NOx figures;
• The kiln inlet seal and the false air: every cubic meter of the false air entering the kiln inlet costs the NOx control: the seal maintenance is an emission discipline: the craftsman of the pyro line owns the gaskets;

The NOx figures of a well-tuned KHD line with the LowNOx calciner and the standard fuel sit typically in the 300 to 700 mg/Nm3 band without the SNCR: with the urea injection of the SNCR system the plant reaches the 100 to 200 mg/Nm3 class: the numbers are the design targets, the process measurement confirms the reality: the emission report is the scoreboard of the burning line.

6. The Rotary Kiln of the KHD Line: The Sintering Vessel

The rotary kiln of the pyro line receives the 90 to 95% calcined meal and delivers the clinker: the last decarbonation and the sintering run in the inclined rotating drum at 3.5 to 5.0 rpm:

• The geometry: the typical line of 3,000 to 5,000 tonnes per day runs a kiln of 4.0 to 5.0 meters diameter and 56 to 70 meters length: the slope 3.0 to 4.0%: the length-diameter ratio 11 to 15;
• The zones of the kiln: the inlet zone where the last calcination ends at 900 to 1100 °C, the upper and lower transition zones, the burning zone at 1400 to 1500 °C where the alite forms, and the cooling zone at the nose;
• The heat input: 35 to 45% of the total fuel enters at the main burner with the primary air at 8 to 12% of the combustion air: the flame reaches 1700 to 2000 °C, the clinker bed 1450 to 1500 °C;
• The coating: the liquid phase of the clinker at 24 to 30% wets the burning-zone bricks and builds the protective coating: the coating is the refractory of the kiln: the stable operation keeps the coating stable;
• The shell and the support: the kiln shell rides on the tyres and the support rollers, driven by the girth gear and the pinion: the shell temperature 200 to 350 °C where the coating and the bricks protect the steel;
• The residence time: the material moves 20 to 40 minutes through the kiln: the bed depth and the rpm decide the movement: the retention time and the fill degree are the two dials of the kiln transport;

The kiln is the most expensive single machine of the plant and the most unforgiving: its availability is the production of the factory: the modern KHD kiln design, the two-support and the statically determined shells, shortened the alignment issues and the thermal stress of the older generations: the operator of the kiln respects the couple of hours of the residence: every input change of today appears in the clinker in 30 minutes: the patience of the pyro process.

7. The PYROFLOOR Cooler: The Walking Floor and the Quench

The PYROFLOOR cooler quenches the clinker and recovers the heat: the hot clinker leaves the kiln at 1350 to 1450 °C and must be cooled below 100 °C while the combustion air of the whole line preheats from its heat:

• The quench zone: the first rows of the cooler receive the full clinker at aeration pressures of 6000 to 9000 Pa: the rapid quench fixes the alite structure of the clinker: the slow cooling degrades the strength and the reactivity;
• The walking floor: the PYROFLOOR plates move the clinker with the hydraulic steps instead of the sliding grates: the plates reciprocate, the clinker advances, the wear is reduced, and the maintenance time is minimized: the design edge of the PYROFLOOR family;
• The aeration compartments: the under-grate plenum divides into compartments, each with its own fan and its damper: the air distribution follows the clinker bed: the coarse clinker gets more air, the fines less: the control of the even cooling;
• The air recovery: the secondary air returns to the kiln burners at 800 to 1100 °C, the tertiary air to the calciner, the surplus hot air to the coal mill or the raw mill drying: the heat recovery to the process;
• The clinker grinding: the final section of the cooler and the crusher reduce the lumps: the cooled clinker goes to the storage and the mill: the cooler rejects keep the clinker transport trouble-free;
• The cooler efficiency: the modern grate coolers reach 70 to 75% heat recovery: the exit clinker temperature of 80 to 120 °C marks the good cooler: every 10 °C of the exit temperature costs or saves the line;

The cooler is often called the fourth gas stream: it is the air supplier of the kiln, the calciner and the mills: its exit air goes to the dust collection, its heat goes to the process, and its failures starve every downstream user: the cooler instrumentation, the grate speed, the aeration pressure and the clinker bed height make the daily control picture of the pyro line.

8. The Tertiary Air and the Gas Flows: The Balance of the Streams

The pyroprocess is a system of gas streams, and the mass balance of the air decides the heat and the emissions: the tertiary air duct from the cooler roof to the calciner completes the loop:

Air stream	Destination	Typical share of total combustion air
Primary air	Kiln burner nozzle	8 – 12%
Secondary air	Kiln hood into the burner	15 – 30%
Tertiary air	Precalciner	25 – 45%
Cooler excess air	Mill drying, dust filter	10 – 25%

The balance sheet reads in the cooler: the total aeration must satisfy the kiln, the calciner and the mills, and the surplus leaves through the cooler dedusting: the operating figures that the shift reports carry include the tertiary air temperature (750 to 950 °C at the calciner), the cooler hood pressure (slightly negative to prevent the dust puffing) and the kiln inlet gas temperature (950 to 1100 °C): the three numbers bracket the state of the whole line: the tertiary air duct with its dampers and its refractory is the valve of the system, and its leaks are the hidden dollars of the heat balance: the sealing and the insulation of the duct protect both the calcination and the fan headroom.

9. The PYROJET Burner and the Firing System: The Fuel Flexibility

The firing system of the KHD line must burn the natural gas, the coal, the petcoke and the alternative fuels with the same stable flame: the PYROJET multichannel burner gathers the streams:

• The construction: the circular multichannel burner with the central fuel lance, the inner swirl air channel and the outer axial air channels: the adjustable swirl vanes change the flame shape without stopping the kiln: the flexible flame, the flexible fuel;
• The momentum: the burner velocity of 80 to 180 m/s at the nozzle gives the flame the penetration into the clinker bed and the recirculation that shapes the flame: the momentum per fuel flow is the design ratio that the plant keeps when switching the fuels;
• The primary air: 8 to 12% of the combustion air at the nozzle: the low primary air keeps the secondary air share high and the flame temperature high: the modern burners run fine with 6 to 10%: the heater air of the flame;
• The multifuel operation: the separate channels for the gas and the pulverized coal allow the changeover without the shutdown: the petcoke with its low volatile content needs the higher momentum and the finer grind: the fuel mix ratios appear in the control system;
• The alternative fuels: the solids, the liquids and the gas from the waste streams enter the main stream or the side lances: the flame temperature profile and the combustion efficiency change with the mix: the kiln process tolerates the lower flame temperatures, the emissions do not: the monitoring of the CO and the TOC of the clinker;
• The ignition and the safety: the burner management system with the flame scanners, the purging sequences and the interlocks: the furnace explosion prevention is the first discipline of the firing system: the sequence of the light-up is written in stone, never improvised;

The burner is the instrument of the burning: it shapes the flame, the flame shapes the coating, and the coating decides the refractory life and the clinker quality: the burner settings, the axial-swirl ratio and the position of the nozzle are the recorded parameters of the shift log: the stable burner, the stable kiln: the PYROJET family documented in the package file with the adjustment drawings and the fuel tables.

10. The Process Data of the PYROCLON Line: The Instrument Envelope

The complete pyro line carries the classical instrument package, and the normal operating figures of a modern KHD line at 100% load are the language of the shift handover:

Process point	Normal value in operation	Meaning when it drifts
Preheater gas exit temperature	280 – 340 °C	Falling with the clogging of the top stages
Calciner exit temperature	850 – 880 °C	Falls with the feed surge, rises with the fuel excess
Calciner exit gas O2	2.0 – 3.5%	Low O2 signals the incomplete combustion
Kiln inlet gas temperature	950 – 1100 °C	Low with the excessive calciner fuel share
Kiln exit gas O2	1.0 – 2.5%	The burning-zone atmosphere of the kiln
Burning zone temperature	1350 – 1450 °C	The sintering of the alite phase
Cooler exit clinker temperature	80 – 120 °C	High exit temperature = insufficient aeration
Tertiary air temperature at the calciner	750 – 950 °C	Falls with the coating of the duct or the cooler bed loss
Kiln drive current	Stable band, rises with the kiln load	The torque of the kiln: the picture of the charge and the coating

The table is the quick map of the process: the veteran operator reads the line from the five numbers, the O2, the burning zone, the kiln inlet temperature, the calciner exit temperature and the cooler pressure: the process data of the file include the recorded normal envelopes per line size, so the new engineer of a plant can compare his own instruments against the reference: the deviations are the work list of the day.

11. The Operation and the Control of the KHD Pyro Line

The control strategy of the PYROCLON line follows the chain of the process: the calciner temperature, the kiln exit O2, the burning zone and the kiln drive regulate the fuel, the feed and the air of the line:

• The calciner exit temperature loop: the first priority: the calciner fuel follows the temperature: the feed surges displace the setpoint: the calciner fuel answers within seconds, the kiln burner within minutes;
• The kiln exit O2 loop: the kiln fuel follows the O2 of the kiln exit gas: the target 1.5 to 2.5%: below the target the CO rises and the ring formation begins, above it the NOx and the heat loss rise;
• The burning zone temperature: the pyrometer reads the clinker and the flame: the target 1350 to 1500 °C: the operator trims the kiln fuel and the burner settings, watching the free lime of the clinker;
• The kiln drive current: the torque of the kiln reflects the charge, the coating and the granulation: the sudden rise signals the ring or the flooding, the drop signals the bare shell: the current is the oldest and most honest instrument of the kiln;
• The feed loop: the kiln feed follows the demanded production with the smooth ramps: the feed rate changes are limited to avoid the thermal waves: the kiln feed and the fuel move in the fixed ratio envelopes;
• The draft control: the ID fan holds the kiln inlet pressure at the setpoint (about minus 3 to 8 mbara design) and the preheater top pressure: the fan speed, the damper and the bypass of the strings balance the two strings;
• The alarm philosophy: the CO alarms above 0.5% trigger the immediate investigation, the kiln inlet temperature alarms protect the feed end, and the cooler under-pressure alarms protect the heat recovery: the operators respond with the predefined procedures, not with the improvisation;

The stability is the goal: the stable line produces the stable clinker with the stable heat consumption: the KHD process control packages add the expert systems that recommend the setpoints from the process history, but the shift operator remains the decision maker: the control sections of the file carry the loop diagrams, the tuning tables and the response curves of each controller.

12. The Circulation of the Volatiles: The Sulfur, the Alkalis and the Chlorine

The pyroprocess is also a chemical cycle: the volatiles evaporate at the high temperatures, condense in the cooler tower stages, and return with the meal to the hot end: the vicious circle runs inside every line and sets the limits of the operation:

• The sulfur cycle: the sulfur of the fuel and the raw material forms SO2 and sulfate: the alkali sulfates condense in the preheater and recirculate: the buildup of the sulfate causes the coating of the riser ducts and the cyclone blockages;
• The alkali cycle: the potassium and the sodium leave the burning zone as the vapor and condense on the meal in the tower: the enrichment factor of the recirculated meal can multiply the feed concentration by 5 to 10 times: the operating limit of the alkali content in the kiln feed;
• The chloride cycle: the chlorine is the most troublesome: it concentrates in the kiln inlet and the lowest cyclones and forms the hard chloride-rich coatings: the critical temperature window of the kiln inlet gas, 1000 to 1200 °C, must be avoided by the stable operation; the chloride input must be limited at the feed;
• The bypass operation: where the raw materials and the fuels carry the high chlorides, the line needs the kiln gas bypass: 2 to 10% of the kiln exit gas extracted, quenched and dedusted with the chloride-rich dust removed from the system: the bypass ratio balances the chloride removal against the heat loss;
• The ring and the coating control: the volatiles feed the sulfur rings in the kiln inlet and the coating of the calciner walls: the stable temperatures, the low excess air and the regular burn-off cycles keep the deposits within the manageable thickness;

The volatile circulation explains many mysteries of the pyro line: the sudden preheater blockages, the kiln exit temperature drifts and the changing composition of the kiln dust: the KHD pyroprocess file documents the enrichment factors, the allowable feed limits and the bypass design calculations: the chemistry of the cycles is read before the hammer of the cleaning crew is used: the cycle knowledge is the prevention.

13. The Maintenance and the Reliability of the Pyro Line

The pyroprocess is continuous: its maintenance happens during the annual shutdown, and the reliability between the stops decides the production of the year: the maintenance calendar of the KHD line is the discipline of the plant:

• The refractory inspection: every shutdown maps the brick condition in the kiln, the calciner and the ducts: the shell temperature scanning during the operation locates the thin spots: the refractory life of the burning zone 6 to 12 months, of the transition zones 12 to 24 months: the planned replacement beats the emergency one;
• The cyclone cleaning schedule: the preheater blockages are removed during the stops with the air cannons and the manual cleaning: the recorded blockages guide the addition of the air cannons: the cleaning of the tower is the first job of the shutdown week;
• The shell and the mechanics: the shell thickness surveys, the ovality measurements and the roller adjustments keep the kiln round and aligned: the bearing temperatures and the vibration of the drive are the watchdogs of the mechanical year;
• The cooler wear items: the aeration plates, the clinker crusher hammers and the hydraulic units of the PYROFLOOR: the wear stock follows the throughput: the plate life of 12 to 24 months with the correct aeration;
• The fan and the duct integrity: the ID fan impeller erosion by the dust and the duct lining repairs: the fan vibration monitoring detects the unbalance before the bearing failure: the draft of the line depends on the fan health;
• The instrumentation calibration: the pyrometers, the gas analyzers and the pressure transmitters of the line are calibrated against the reference at every stop: the control of the line is only as good as its instruments: the calibration register of the pyro line;

The maintenance budget of the pyro line is typically 30 to 40% of the whole plant maintenance spend: the shutdown planning, the spare part strategy and the condition monitoring convert the budget into the availability: the KHD pyroprocess file includes the maintenance checklists per equipment, the wear part lists and the shutdown sequence plans: the reliability of the line is engineered on paper before it is won on the site.

14. The Frequently Asked Questions

What does the KHD pyroprocess mean exactly?

It is the complete thermal line of the Humboldt tradition: the PYROCLON cyclone preheater, the PYROCLON-R precalciner, the rotary kiln and the PYROFLOOR cooler: the chain that converts the raw meal into the clinker: the pyroprocess includes also the firing system, the tertiary air duct, the bypass and the gas circuit: the term covers the equipment and the process together.

Why is the calcination moved from the kiln into the precalciner?

Because the calcination is the most energy hungry reaction of the line and the kiln is the most expensive vessel: moving 90 to 95% of the calcination into the calciner allows the smaller kiln per tonne, the shorter retention and the doubled capacity of the same shell: the fuel split 55 to 65% to the calciner follows the energy of the reaction.

What is the difference between the two strings of the preheater?

One string receives the kiln gas, the other the calciner gas: the two strings split the gas flows so each stream heats its own column of meal with the proper temperature: the string balance appears in the draft and the temperature readings of the two columns: the imbalance points to the blockage or the draft problem of one string.

How does the LowNOx calciner reduce the NOx?

By the staged combustion: the lower part of the vessel burns the fuel in the fuel-rich atmosphere with the reduced oxygen, which suppresses the NOx formation and even reduces the NOx already formed in the kiln gas: the upper part completes the combustion with the tertiary air: the staging is the chemical and the mechanical design together.

Why does the kiln exit O2 matter so much?

It is the window to the burning zone: too low, and the fuel leaves unburned, the CO rises and the sulfur rings grow; too high, and the heat escapes, the NOx rises and the flame cools: the 1.5 to 2.5% band is the compromise of the combustion, the chemistry and the economy: the O2 analyzer is the oldest friend of the operator.

Does the package include the Excel tools for the pyroprocess?

The Complete Cement Technical Package includes the pyroprocess calculators: the heat balance sheets, the cyclone sizing estimates and the cooler air balance tools: the engineers input the measured temperatures and the gas flows and receive the heat consumption and the efficiency figures: the 931 files of the package, the tools included.

What is the most common emergency in the pyro line?

The preheater blockage and the kiln shell overheating: both announce themselves early, the tower by the falling temperatures and the rising drafts, the shell by the infrared scanning: the emergency procedures of the package guide the shutdown, the cleaning and the restart: the discipline of the response saves the equipment and the shift.

15. Conclusion

The KHD pyroprocess: the two-string tower, the staged calciner, the kiln and the walking cooler: the chain of the temperatures that converts the meal into the clinker: the process engineer of the pyro line holds the map of this chain, the instrument readings and the patience of the retention time: the knowledge of the architecture, the cyclones, the combustion, the gas balance and the volatile cycles is the difference between the line that runs and the line that is run by its problems.

The Complete Cement Technical Package includes the KHD pyroprocess guide with the flow sheets, the design figures, the tables and the operation checklists: the one-time 249.99: the instant download: the library of the cement: the pyroprocess file: the work of the professional: the cement knowledge, the measured: the line of the package, the fire of the plant: the career of the engineer, fired right.

This file is part of the Complete Cement Technical Package (931 files) available from cementequipment.org. Respective rights holders; library copy for the licensed single user.