Rotary Kiln System Health, Safety And Environmental Issues

User Generated

xbbbxv307

Writing

Description

Paraphrasing of the word file submitted. A side note, the material used in the file submitted is mica, while my chosen material is silica sand (or quartz) so whenever you come across mica, replace it with either silica sand or quartz. Also, this assignment has turnitin enable, so make sure that as little plagiarism as possible is found.

Unformatted Attachment Preview

Health, Safety and Environmental Issues Potentially the most dangerous threat to human health within the kiln system is the fluorine and hydrogen fluoride which would be produced if insufficient quantities of sodium sulphate are added. These substances are highly toxic, and corrosive, and are also capable of corroding equipment, and hydrogen fluoride also contributes towards acidification of the environment if it is not cleaned from the stack gases. Consequently, it is desired to react the fluorine with the bed material to form a solid before it reaches the kiln gas; experimental tests will be carried out in order to determine an optimal amount of sodium sulphate which is capable of maximising the amount of fluorine released which form solid compounds. It is believed that the ratio of 1 kg of sodium sulphate for every 3.4 kg of micaceous feed would be sufficient, but this is based on very tenuous assumptions, so laboratory tests are necessary. . Even with excess sodium sulphate, some fluorine near the surface will escape to the kiln gas stream before it has a chance to react with the bed, and while it is in this gas stream, it is likely to react with water vapour to form hydrogen fluoride. Being at very low concentrations (if enough sodium sulphate is present), this is not much of a problem at low temperatures, but the corrosiveness of fluorine and hydrogen fluoride increases dramatically with temperature, and so even this small concentration is likely to be capable of damaging unprotected equipment. Consequently, piping and equipment such as fans which come into contact with kiln gas at high temperatures are lined with a corrosion resistant metal (which is later chosen to be Inconel 600), and a refractory brick which is resistant to fluorine induced silica depletion is chosen. Any hydrogen fluoride in the kiln gas would be removed by reacting with limestone chips in the packed bed scrubber, to produce calcium fluoride. The kiln system operates below atmospheric pressure, at 0.8 bar, to ensure that ambient air leaks in, which is preferable to kiln gas leaking out. The exposure limits for fluorine and hydrogen fluoride are given in Table 4 below. Another problematic health hazard would be dust inhalation. At particle sizes of below around 4 µm, mineral dust can penetrate the lungs and cause fibrosis. Since mica has a fine particle size, this therefore poses a health risk to personnel. Therefore, all units which convey solids, such as screw conveyors, are enclosed to prevent dust escaping, and the kiln system operates at negative pressure, to prevent dust laden gas from leaking out. Cyclones are used to remove relatively coarse dust particles from the kiln gas stream, with the smaller particles being removed by a baghouse filter. Carbon monoxide is unlikely to be a problem, as excess air is used during combustion, and nitrous oxide should be reduced to safe levels by using a low NOx burner. Long term exposure limit (8 hr TWA reference period) Fluorine Hydrogen fluoride Mica – total inhalable Mica – respirable ppm 1 1.8 - mg/m3 1.6 1.5 10 0.8 Short term exposure limit (15 minute reference period) ppm 2 3 - mg/m3 2.5 2.5 - Table 4 – occupational exposure limits for the major hazardous substances in the kiln gas (HSE, 2007) . Overheating of the kiln, or rapid changes in temperature, also contribute a considerable safety hazard. The refractory must be heated or cooled slowly to avoid thermal shock which can cause damage, and the shell itself must be heated slowly so that differential thermal expansion between the shell and tyres doesn’t cause damage to the shell. Consequently, startup and shutdown protocols are used which take this into account, which are discussed later in the report, and cascade control is used to ensure steady and safe temperature ranges across the kiln. Refractory damage due to corrosion or thermal shock can compromise the insulation properties, which means that more heat can escape from the kiln interior and heat the shell. This reduces the strength of the steel, and so can cause structural damage of the kiln, which could result in a loss of containment. Consequently, the kiln shell is periodically monitored with a temperature gun to look for ‘hot spots’ indicative of a refractory failure, so the kiln can be shut down and the refractory replaced before irreversible damage is done to the shell. 5 - Process Control . 5.1 - Piping and Instrumentation Diagram Adequate process control is important to ensure that the product is manufactured economically, safely, and with little damage to the environment; this involves the control of a wide range of factors, such as the temperatures, pressures, and flow rates of several streams, and because of the interactions between these variables, the effects of control can become complex. Basic control systems have been selected for the entire lithium carbonate plant and are shown on the piping and instrumentation diagram (P&ID), but as the rotary kiln is the focus of the report, the control systems in this region are discussed in detail. The complete control system is shown at the end of the report on the P&ID as Figure A2. The nomenclature used in the P&ID will be described in this section. The plant is divided into four regions on the P&ID, and the code for each piece of equipment includes a number representing the region; the four regions are described below: . 1 – Flotation region 2 – Magnetic separator region 3 – Rotary kiln region (the scope of this report) 4 – Leaching and precipitation region . The P&ID nomenclature for unit operations, valves, instrumentation, and piping will be described below. Unit Operations The generic labelling for a unit operation is ‘X-0000’. ‘X’ consists of one or two letters representing the equipment, the first number represents the plant region as defined above, the second number represents the system code, and the last two numbers is a two digit identifier number unique to the unit. The system codes used are described as follows: 1 – Process liquid/slurry 2 – Process gas 3 – Process solids (powder or cake) 4 – Fuel gas 5 – Heating/cooling utilities 6 - Air . The letters used to represent each type of unit operation are shown below: BF – Baghouse filter C – Cyclone D – Dryer (spray or tube press) F – Fan FL – Flotation Cell HE – Heat exchanger M – Mill (hammer or pin) MS – Magnetic separator) P – Pump PB – Packed Bed Scrubber RC – Rotary cooler RK – Rotary kiln SC – Screw conveyor SF – Screen/filter T – Tank . An example of the use of this nomenclature is the kiln gas cyclone on the P&ID. It is a cyclone, so it is represented by the letter ‘C’. It handles the process gas, so the first number is ‘2’, and is in the kiln area of the plant, and so the second number is ‘3’. The last two numbers is a unique identifier number, which is 08 in this case. The code for the kiln gas cyclone is therefore C-2308. In some cases, some pieces of equipment like fans and pumps are standby units, which automatically come into operation if the main unit fails; this is represented by a suffix of ‘-b’. For example, the code for the backup fan for the preheater cyclone is F-2315-b. Valves Valves have a five or six digit code on the P&ID, the generic form of which is ‘V0000X’. ‘V’ is constant for all valves, and is simply used to show that the code is representing a type of valve. The first number represents the region of the plant the valve is located in (1-4), and the last three numbers are a unique identifier code. In the case of a generic block valve, that is the entirety of a code, but in the case of other types of valves, such as a control valve, there is an additional letter at the end of the code (‘X’ in the generic code above) which represents the type of valve; these types are shown below, along with a symbol representing each valve: No suffix – Block valve V – Vent D – Drain G – Globe valve C – Control valve P – Pressure relief valve PC – Pressure control valve X – Spectacle blind K – Check valve / pendulum flap gate B – Bleed (sampling point) . An example of this usage is the check valve after the primary fan used to keep the kiln system at 0.8 bar pressure. It is in the kiln section of the plant, and so the first number is ‘3’, and it is a check valve, so its last letter is ‘K’. The identifier code is ‘086’. The complete code for this valve is therefore V3086K. Piping The generic code for piping is ‘00”-X-000-00X-X’. The first two numbers is the pipe nominal diameter in inches, the first letter is the commodity which the pipe is carrying. The first of the subsequent three numbers represents the region of the plant (1-4), with the next two being the identifier code. In the ‘00X’ part of the code, the first two numbers represent the piping specification (which for all pipes considered in this report, is ‘10S’) which represents the thickness, and the letter in the ‘00X’ part represents the construction material. The final letter of the code represents the insulation specifications, with ‘N’ meaning no insulation, ‘H’ meaning insulation for heat conservation, and ‘PP’ is insulation for personnel protection, which is used when there is a reasonable chance that personnel could come into contact with hot surfaces. The commodities defined by the first letter in the code are shown below: A – Air F – Fuel gas G – Process gas P – Powder ST – Steam W – Water L – Process liquid/slurry . The materials of construction of the pipes are given a simplified code of A, B, C, or D, which are described below A – Mild steel B – Grade 304 stainless steel C – Grade 304 stainless steel with 1 mm Inconel 600 lining D – Grade 310 stainless steel with 2 mm Inconel 600 lining . The gas outlet pipe immediately after the kiln will be used as an example. The nominal diameter of the pipe is 30”, and it transports process gas, so the first letter in the code is ‘G’. It is in the kiln section of the plant (‘3’), and has an identifier code of 15. The piping specification is 10S, and the material of construction is Grade 310 stainless steel with 2 mm Inconel 600 lining (‘D’). Because the kiln gas pipe is unlikely to come into contact with personnel during operation, heat conservation grade insulation (‘H’) will be used rather than personnel protection grade. This results in a code of 30”-G-315-10SD-H. The piping was given codes only for pipes carrying fluids in the rotary kiln section, as this was the scope of the piping calculations performed earlier in this report. Instrumentation An example of an instrument symbol (in this case a pressure indicator) is shown below: In the top hemisphere, the first letter represents the factor being measured (in this case, pressure), with the subsequent letters representing the function of the measurement; in the above example, it is an indicator. In the bottom hemisphere, the first number representing the region of the plant which the instrument is located in, and the subsequent two numbers represent the control loop that the instrument is part of. The process variables represented by the first letter of the top hemisphere of the instrument symbol are shown below: T – Temperature P – Pressure F – Flow rate M – Moisture L – Level dP – Differential pressure . The functions represented by the subsequent letters in the top hemisphere (which can be between one and three letters) are shown below: I – Indicator T – Transmitter C – Control AHH – very high level alarm ALL – very low level alarm SD – Shut down . When ‘control’ is used as the second letter, this means that the variable being measured (the first letter) is the control variable; in this case, there is also an implicit indicator used to measure the variable, and a transmitter to convert this data into a form in which the control system can use, but these are not included in the P&ID for the sake of brevity. When programmable logic controller (PLC) is used for complex control loops, several variables can be used as inputs; in this case, all of the inputs which are control variables are designated as ‘C’, whereas all other inputs which are used in the calculations, but are not being controlled by the PLC, are designated as ‘T’. An example of this is shown below. . The above example is used for controlling the temperature of the combustion air and recirculated kiln gas mixture entering the kiln (which is represented by the TC 346 balloon). It uses the flow rate of the natural gas stream and the current temperature of the recirculated kiln gas stream (both represented by transmitters) to determine the set point for the control variable. The PLC then produces an output signal which is used to control the recirculation fan speed to control the flow rate (not shown on the above example). For a particular variable being controlled, all other factors used in this particular control loop are given the same control loop code, including the PLC, if one is used. In the case of indicators, even though they are not used in control, all indicators on a given section of pipe (with no unit operations or pipe branches in between) are given the same control loop number. If there are several instruments which measure the same variable on a pipe length (as there are sometimes with pressure gauges, used to check that valves have closed during shutdown), they are given suffixes, such as A or B, on the end of their control loop number to differentiate them. . 5.2 - Rotary Kiln Process Control There are many parameters which must be finely tuned to ensure efficient, productive, and safe operation of the rotary kiln. The first control system encountered in the kiln section of the plant is control of the stoichiometric ratio of micaceous feed and sodium sulphate. In order to dampen out variations in the flow rates and moisture contents of the filter cake produced from the filter press at the end of the magnetic separation section, a buffer hopper is installed (T-204) before the screw conveyor (SC-3205) which feeds the mica into the kiln system. The flow rate into the solids mixer is controlled by the speed of this screw conveyor; this must be kept roughly constant, in order to reduce variation in temperature and flow rate downstream. The screw conveyor will attempt to transport mica at a rate that results in steady state in the buffer hopper; two alarms have been installed on the hopper which warn when high or low levels are reached, in which case the set point of the screw conveyor changes to counteract this. As the sodium sulphate must be added at a specific ratio (3.4 kg of mica feed to 1 kg of sodium sulphate), the flow control of sodium sulphate powder into the solid mixer takes into consideration the flow rate of the mica feed, and a PLC is used to adjust a control valve to allow the desired amount of sodium sulphate through (control loop 301). . The temperature of the solid feed entering the kiln must be controlled at around 300°C. This is achieved in control loop 305 by measuring the temperature of the solids in the underflow of the cyclone preheater C3302. This information is then used to change the motor speed of the fans on the preheater overflow, which changes the fraction of kiln gas which is diverted to the preheater. Due to the residence time being in seconds rather than minutes or hours, cascade control is unnecessary, and simple feedback control is sufficient. Controlling the flow rate of the solids into the kiln is also important, as it is desired to keep the heat transfer duties constant, and a large disturbance in flow rate can cause a thermal shock, damaging the refractory. This is achieved in control loop 314 by varying the speed of screw conveyor SC-3304, which is fed by a hopper, T3303. As a steady state between the inlet and outlet of the hopper is needed, the set point for control loop 314 is chosen accordingly. If there are long term variations in the feed flow rates into the kiln section, then a steady state will not be reached, and the level in the hopper will increase or decrease without limit. Once these deviations reach a critical value, low or high level alarms are activated, and the set point of the screw conveyor is changed in attempt to obtain a steady state. The temperature control of the kiln is very complex, particularly because of the adjustable recirculation ratio and preheated air addition. Measuring the temperature of the outlet gases and solids with thermocouples can be used as an indication of the heat transfer rates within the kiln; using a heat transfer model similar to the one used in this report, these two temperatures can be used to infer whether the solids have been above 850°C for more than an hour. The gas has a much shorter residence time than the solids, with the gas residence time in the range of seconds, compared to a total of approximately 1.5 hours for the kiln. Therefore, any disturbances in the temperature and flow rate of the feed or kiln gas will take a long time to have an effect on the final temperature of the solids; a feedback control loop between the outlet solids temperature alone and the firing rate of the burner is therefore impractical. Cascade control is therefore used as the outlet temperature of the kiln gas is much quicker to respond to changes in inlet conditions for both the feed and the gas. Measurements of the solids outlet temperature are used to calculate the set point for the kiln gas outlet temperature control, which is the kiln gas temperature at which the control system expects the solids outlet temperature to reach the desired value. The kiln gas temperature is then controlled to try to maintain this set point, by varying the flow rate of natural gas which passes to the burner. If the solids outlet temperature still deviates from its set point, the set point of the kiln gas is adjusted, and is attempted to be maintained by varying the firing rate. The natural gas flow rate is set by the desired outlet temperatures of the kiln gas and solids. This must be combusted with 35% excess air, so the air flow rate must be controlled taking into account the natural gas flow rate. It is also desired to utilise the heat retrieved from the rotary cooler by the cooling air, in order to reduce the firing rate of the burner necessary for a given flame temperature and kiln gas heat content. There will be significant variations in the preheated air temperature due to the dynamics of the solids cooling operation upstream, along with differences in ambient temperatures, but it is desired to keep the temperature of the air that is to form part of the precombustion gas mixture constant (at 300°C), to reduce variation in flame temperature. The flow rate and temperature of this air stream is a product of the ambient air stream and the preheated air stream, and because the temperature and flow rate of the preheated air stream is believed to be around the required value for this mixed air stream, it will consist of predominantly the preheated air stream. A PLC controller (control loop 371) is used to ensure that this mixed air stream has the optimum flow rate and temperature for the amount of natural gas being burned. If the temperature and flow rate of the mixed air stream is too great, then the PLC increases the opening in control valve V3199C which diverts some of the preheated air away into the atmosphere. If this is insufficient in reducing the flow rate, or if the temperature set point changes to be lower, then the globe valve on the preheated air stream can be throttled to make it narrower, increasing the amount of preheated air diverted away from the mixed air stream. If the temperature is too high and the flow rate insufficient, then the PLC opens control valve V3171C to let in ambient air to cool the mixed air temperature and supplement the flow rate. If the temperature is too low and the flow rate too high, then valve V3171C is throttled closed. If the both the temperature and flow rate is too low, or if the flow rate is too low and increasing it with ambient air would decrease the temperature below the set point, control valve V3199C is throttled closed; if this is insufficient, there is no other way by which this particular control loop can reach the set point, and this would then have to be mitigated by the recirculated kiln gas. The recirculated kiln gas is also controlled with a PLC, using control loop 346; it is desired to keep the temperature of the kiln gas and combustion air mixture entering the burner constant, with a constant air flow rate determined by the natural gas flow rate. This is achieved by measuring the temperature of the recirculated kiln gas, the temperature of the precombustion mixture of air and kiln gas, and the flow rate of the natural gas, and using this information to control the flow rate of the kiln gas by changing the motor speed of the recirculation fan (F-2312). This also accommodates for disturbances in the air flow rate, if control loop 371 has failed to maintain its temperature set point. The oxygen content of the precombustion gas mixture must be kept constant at around 16%, as too much kiln gas would disrupt combustion; consequently, globe valve V3148G is installed on the recirculation gas line, which can be throttled to change the amount of kiln gas which the control system is able to use. The solids in the rotary cooler are cooled both by internal air and an external water spray. The same problem with using simple feedback control for temperature control of the solids in the rotary kiln is encountered again in the cooler; due to the long residence time of the solids, it is more practical to use cascade control, to use the offset in the solids outlet temperature to produce the set point of the cooling medium outlet temperature, and directly control that instead. Because the water is sprayed in an open environment, and because a lot of the water would evaporate meaning that temperature measurements alone are not a good indication of heat transfer rate, it was decided to not control the flow rate of the water spray, and instead just have a globe valve (V3210G) which can be throttled manually to accommodate large changes in heat transfer requirements; the air flow rate will be used for smaller, more precise adjustments to the heat transfer rate from the solids. Therefore, given an appropriate manually adjusted external water spray flow rate, the outlet temperature of the solids is used to calculate the set point for the outlet air temperature. This set point will be achieved by varying the motor speed of fan to F-6332 to alter the flow rate of air through the cooler. This can accommodate disturbances in the air inlet temperature, solids inlet temperature and flow rates, and water spray flow rates and temperatures. Since the fan immediately after the kiln gas outlet, F-2310, is not used in any other control system, it can be used to control the separation in cyclone C-2308. For given particle properties and size distribution, and given gas temperature and flow rate, the separation efficiency of the cyclone can be deduced from the pressure drop across the hydrocyclone; therefore, fan F-2310 will be throttled to keep the pressure drop at the value at which it is believed to give the ideal balance between separation efficiency and pumping energy costs. Samples of the underflow and overflow will be taken periodically to obtain particle size distributions of each stream, and the solids loading in the overflow, to determine whether the pressure drop set point must be changed. The temperature of the kiln gas before it enters the scrubber is reduced to 150°C using a water cooled heat exchanger. Feedback control is used without cascade control or feedforward control, since the residence time of gas in the heat exchanger is small enough that disturbances in the input are detected in the output relatively quickly. Measurements of the outlet temperature of the gas are used to adjust a control valve to change the flow rate of cooling water passing through the heat exchanger. The pressure of the kiln system, the preheater, and the associated kiln gas streams must be kept at around 0.8 bar to minimise potentially harmful kiln gases from leaking into the surrounding environment. A pressure measurement device is located in the exit hood of the kiln, and the data from this is used to control the motor speed of fan F-2316 after the heat exchanger; this fan and its associated backup are the most powerful in the kiln system, and are used to pump out enough air from the kiln to ensure that an 0.8 bar pressure is maintained, and to remove any air leaking into the system. The level of the kiln (the fill volume fraction of solids) is controlled by using a sensor which can identify the level, and this information is transmitted to a controller, which changes the kiln rotation rate to increase or decrease the average velocity of the solids; since feed rate is constant, this changes the fill volume fraction. . 5.3 - Kiln Startup Because the refractory lining is vulnerable to thermal shock, and because the effects of differential thermal expansion must be mitigated, it is very important to start up the kiln in the correct manner and rate, to minimise the risk of damage. If the increase in shell temperature is too rapid, this could result in excessive differential expansion between the kiln and the tyres, resulting in ovality. The controlled rate of temperature increase is achieved by altering both the firing rate and using large amounts of excess air to cool the flame temperature. Unless stated, no kiln gas is recirculated during startup (globe valve V3148G is closed). The kiln startup procedure was adapted from Resco (2004), and is detailed below. . 1 - Circulate ambient air through the kiln for at least 24 hours. 2 - Place sacrificial thermocouples along the length of the refractory surface, recording temperature at least once every 30 minutes. All temperatures mentioned in the startup section indicate the refractory temperature measured by these thermocouples. 3 - Begin to rotate the kiln at around 1 revolution every 90 minutes. 4 - Increase the temperature of the refractory at a maximum of 56°C per hour up to a temperature of 180°C. Any water which has accumulated in the kiln will begin to evaporate. From this stage onwards, use fan F-2316 to maintain a kiln pressure of 0.8 bar, and to divert 4.2 kg/s of kiln gas through the preheater cyclone, so it warms up at the same rate as the kiln. 5 - Hold at 180°C for 9 hours, to evaporate any water, and to ensure that the refractory temperature has reached a steady state. 6 - Raise the temperature at a maximum rate of 28°C per hour up to a temperature of 316°C. If water is expected to be in the kiln, and no steam has been detected up to this point, hold at this temperature until the steam appears and dissipates. 7 - Increase the rotation rate of the kiln to 0.6 rpm. 8 - Raise the temperature at a maximum rate of 28°C per hour up to a refractory temperature of 1000°C (which will be only slightly less than the gas temperature due to the absence of cooling bed material). 9 - Increase the rotation rate to 1.23 rpm. Begin to recirculate 24% of the kiln gas, and change the firing rate and excess air ratio to maintain the gas temperature and flow rate. 10 - Gradually introduce the solids through the preheater and into the kiln. Increase the firing rate and decrease the excess air ratio to counteract the cooling effect of the solids, in an attempt to keep the refractory temperature at 1000°C. The rate of solids addition must be slow enough to ensure that there is not a considerable temperature profile across the length of the kiln and that the temperature change in any part of the refractory, due to the addition of cool solids or the increase in firing rate, does not exceed 56°C per hour. 11 - Continue to increase the rate of solids addition and the firing rate until the operating temperatures and flow rates are reached. . 5.4 - Kiln Shutdown As with kiln startup, during shutdown excessive thermal shock must be avoided, and so temperature changes in all parts of the refractory must be gradual. During a planned shutdown, the following procedure is followed: . 1 - Reduce the flow rate of solids into the kiln, and reduce the firing rate of the burner and increase excess air accordingly, to keep the refractory temperature close to 1000°C, with no part of the refractory having a rate of temperature change greater than 56°C. Continue until there is no flow of solids through the kiln. 2 - Reduce the recirculation rate of the kiln gas to zero by throttling down globe valve V3148G, increasing firing rate and excess air ratio to maintain kiln gas flow rate and temperature. 3 - Hold the wall temperature at 1000°C for 2 hours, while still firing the burner with no flow of solids. This is to effectively purge the kiln of kiln gas containing fluorine and hydrogen fluoride without changing the temperature. 4 - Decrease the rotation rate to 0.6 rpm. 5 - Reduce the motor speed of fan F-2316 to increase the pressure in the kiln close to atmospheric; this reduces air leakage into the kiln, and so reduces the rate of cooling. 6 - Switch off the burner and close valves V3151, V3174, and V3052, closing the gas inlets and outlets, and switch off all fans. This traps hot gas within the kiln. 7 - Decrease the rotation rate to 4 revolutions per hour 8 - Allow the kiln to cool naturally from air leaking in through the leaf seals, and from air convection on the outer shell. 9 - Once the kiln temperature is close to ambient, the rotation rate is decreased to zero, and valves V3174 and V3052 are opened again, to allow for ambient air to purge the kiln of combustion gas. Emergency shutdowns occur due to the failure of a critical piece of equipment, or if process conditions have reached dangerous levels. In this case, it may not be possible to maintain solids and gas flow through the kiln. During an emergency shutdown, the motor controlling screw conveyor SC-3304 is switched off, the fans and the burner is switched off, and gas inlet and outlet valves V3151, V3174, V3052, and V3148G are closed. The kiln continues to rotate at 1.23 rpm to convey all solids present out of the kiln, and after this is accomplished, the rotation rate is lowered to 4 revolutions per hour, and the kiln is allowed to cool naturally. As with the planned shutdown, once the temperature of the kiln approaches ambient, the rotation is stopped completely, and the kiln is purged with air. Due to the uncontrolled rate of cooling, the risk of refractory damage is much higher in the case of an emergency shutdown. Manual emergency shutdowns are carried out when it is noticed that a critical piece of equipment has failed, or that there is a serious leak in the kiln or kiln gas piping. The kiln is also shut down when the feed flow rate or inlet gas flow rate is disrupted. Automatic shutdown mechanisms are employed if excessively high pressure is measured in the kiln, or if the temperature of the kiln rises too high or falls too low; these factors of the process are under control, and so if these alarms are breached, then this is either due to a failure in the process or a failure of the control system. Both are serious, and so the kiln must be shut down for safety reasons, and the problem must then be identified and fixed. In particular, if localised high temperatures on the kiln shell are detected, this implies a refractory lining failure, and so the kiln must have the lining fixed once the emergency shutdown is complete, or the steel shell could overheat, compromising its structural integrity.
Purchase answer to see full attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.

Explanation & Answer

Attached.

AAA
by Aaa Aaa

Submission date: 16-Mar-2019 03:17AM (UT C-0400)
Submission ID: 1094278775
File...


Anonymous
Very useful material for studying!

Studypool
4.7
Trustpilot
4.5
Sitejabber
4.4

Related Tags