In some project, in get together to benzene glycol of 2 formic acid ester (PET) in the model that blow model and fill unit process of cargo bandling, a very effective measurement plan application makes supply side air and the model that blow model can be completely synchronous, reduced total air to use significantly thereby, improved productivity and quality.
Decide an issue
Demand side of the system blows model mould composition by 4, the mould that blow model supplies 3 independent fill routes. This factory has their inextricability a few serious operation problems.
To abecedarian, the mould that blow model is faster than fill line, and in most unit process of cargo bandling, mould must every 5 stop to 7 minutes and start. The factory cannot adjust line rate, when be started afresh, the mould that blow model often be out of order, or the bottle with unqualified generation.
In the meantime, the total air of the mould that blow model is supplied come from two 800 horsepower (HP) 4 class are centrifugal type air compressor, every can carry 1726scfm (aggregate 3452) , pressure is 550 to 580psig. This kind of air current is already enough to 4 moulds that blow model, can operate 3 only among them. Compressor of these two air works 5 days every week, everyday 24 hours (6240 hours) . As a result of start and stop ability finite, when having production every time, these two unit need to continue to move.
An issue that factory policymaker wants to solve is, the size of the can lade according to need and uninstalls empty press that increases in the system and type, the compressor of centrifugal type air that often need not run two 800HP thereby. In the meantime, they still want to know, when air demand is inferior, to can be uninstalled effectively and save the sources of energy, need device of nap of what kind of dimension.
Recommend use compressor of air of 500HP of 4 class double action, water-cooling, reciprocating type, rated power is 5100-580psig, be defeated by tolerance 1100-1200scfm. Because the aircrew of two 800 horsepower drops in the pressure when full load, people thinks their demand is too high, plan to install compressor of centrifugal type air in base then, use unit of new move back and forth to undertake nap.
Plant manager thinks the factory needs more specific support data to realize this one tremendous capital expenditure, ask adviser to undertake be assessmented in the round.
Make action plan
Advisory group undertook an analysis, put forward a series of measure to collect optimize compress air system and the data that realize energy-saving place to need.
The first pace, the air that the factory needs to move in every installs the recorder of power input on compressor, still need to install flowmeter after pneumatics computer room and freeze-dry machine. In addition, pressure sensor and logger are installed after this plan still asks to shrink to the exit of entrance of machine vent, drier, drier, mould that blow model enters the mouth and blow model mould in empty atmospheric pressure, every blow the exhaust of high-pressured entrance adjuster inside model mould.
Next, this group indicates a factory to install this to measure equipment, with a second frequency records all data at the same time, so that undertake,diagnose.
Next, the factory needs to build a setting of accurate optimal circumstance demand to measure a condition. For this, need is considering actuating pressure, bottle / dimension of the manufacturing level of the hour, container and blow gas to reclaim rate while, decide every job blows the air demand of gas mould. Express 1 overview how is this finished.
Use blow gas to reclaim the bottle of the mould that blow air of rate plan cipher out needs tolerance curve
There are 4 opportunities that blow model in the factory. Line 3a and 3b always move together. Line 4 or line 5 move together with line 3a and 3b.
Below the pressure of 550psig, to satisfy two kinds of afore-mentioned requirements, the air of the greatest maximum pressure that computation gives uses requirement (of 40% compress air to reclaim rate) will come in 2500scfm between 2600scfm.
The data of control plate discharge that blows model mould to go up each (watch 2) show, cop 4 and of 5 move slightly under computational discharge. However, the moving tolerance of line 3a and 3b is worth tall 300scfm than computation about.
Decorate according to current conduit, the 210scfm that studies the group cannot determine every pattern airs gas reclaims to whether be used actually, but maintenance index considers as. To the observation discovery of the operation, cop 3a and 3b blow the leak with the very serious existence inside model mould.
Obtain accurate opinion
This group obtained precious opinion, reached pressure of accurate going from place to place operates a curve thereby.
If crucial data expresses 3 to show. A window of data is, the largest flow that enters a system is 2700scfm, pressure drops. Two rating that are fully loaded with compressor of centrifugal type air are 3532scfm, but can carry 2700scfm only. In addition, the mould that blow model is opened shut cycle to be 4 to 6 minutes. The manufacturing rate of the mould that blow model exceeds fill rate far.
If the watch is shown 4 times, compare with calculative 1405scfm photograph, the mould that blow model 4 measure below 1461scfm; Compare with calculative 800scfm photograph, 3a of the mould that blow model is measured below 1200scfm; Compare with calculative 800scfm photograph, 3b of the mould that blow model is making an appointment with 1300scfm next measurement.
Express the exhaust pressure when two 5 jobs in showing every air compressor boasts a standard in 3. System can the greatest pressure is susceptive 520 to 530psig. When 3 blow a model to work at the same time, the pressure of two compressor falls 465psig.
These measurement reached a few fundamental conclusion. Evaluate from air demand begin, the mould that blow model 4 with the 5 net flow that can affirm computation goes out it seems that (include to blow model air to reclaim rate) it is accurate. Reach with computation 1600 compare to 1700scfm photograph, the 3a of the mould that blow model that moves together and 3b measured value arrive for 2200scfm 2400scfm.
Suggest adopted step includes investigation and repair leak. After leak rehabilitate, the factory needs stability to be below proper demand. In addition, still need to monitor all air current that boast a standard and entrance pressure. The assessment that supplies to air is as follows as a result:
1) always ask to be in for tolerance 550 to 580psig between, machine of pneumatics of a centrifugal type provides rated flow, one reserves machine of centrifugal type pneumatics, and one is in 3200 to the measure is right a powerful person between 3300scfm inside.
2) move in 4 lines or line of mark of 5 line, 3A and 3B mark line suffer monitoring and in maintaining the good pattern that blow model, calculative is overall the biggest load.
3) inside P a powerful person right kind and dimension should be 3 class are uninstalled, aircrew of water-cooling of double action reciprocating type, tolerance is offerred below the 550 pressure to 580psig for 1, 500 to 1, 600 Scfm.
This will make quantity of total demand is achieved 3250 to 3350scfm, the biggest demand is 3000 to 3100scfm, among them compressor of air of a centrifugal type is in main negative charge, another is in reserve mode, such doing will reduce total input energy significantly. Of original proposal 1050 to device of 1100scfm fine tuning too small.
Solve crucial problem
This project solved 3 crucial problems:
1. How can you just eliminate be started often and stop? A kind of solution is increase bottle store carry a line. Another kind of method is to lower rate of the mould that blow model, make its approach fill rate. This can extend run time not only, and can reduce air demand. In other words, slowdown 10% , reduce air demand 10% . This kind of speed is adjusted is finished through adjusting speed, control equipment and oven appropriately.
2. Why cannot compressor of air of these two centrifugal type provide total capacity? This is with the question with conduit strict and pertinent question.
Graph 1 showed basic conduit measure and configuration. Red circle expresses across of a “ ” of dead head of 3 ” and “ , gather together current to be in charge of to 6 inches of collect, produce the onflow obstruction of pair of current and counterpressure thereby, will be fully loaded with quality to flow to reduce 2700scfm to arrive from 3532scfm 2800scfm.
Graph 2 showed the true means that removes issue of this kind of main pipeline. More important is, this system use belt is dynamic and centrifugal of air compressor discharging an amount regulating unit. This group still removed any interference to compressor of centrifugal type air, the method is will discharging capacity plant to move to a receiver, will discharge a canal to join with proper point of view of primary air receiver downstream.
Note: Use at discharged centrifugal collect canal to increase 20 inches from 6 inches, deliver in order to reduce rate (Ab) .
3. Does extreme pressure fall (465psig) main reason and what is correcting measure?
If this kind of circumstance pursues 3 with the graph 4 are shown (C) .
Graph the 3 pressure that showed drier from beginning to end. ΔP is an approximate invariable 5psig, the likelihood looks very tall, but because it is of a stability,press difference, the desiccator that may not be pollution so or filter the pressure loss that segregator causes.
Graph the 4 pressure after showing drier and entry of the mould that blow model. The mould that blow model asks pressure of the smallest entrance is 480psig, but, this cannot blow the consign below the condition that model mould runs continuously in 3. Below 465psig pressure, blow a model to shut (D) .
Acknowledge a problem
Store: Below pressure of the biggest 550psig, always store effectively estimate 3100 gallon (414 Cu.ft. ) . Avoid to blow the =480psig of concessional pressure loss of problem of modular low pressure.
The formula of computational disintegration time:
Pour out of a quantity to be 400scfm completely
The net flow that air compressor provides currently (as far as possible best) = 2700scfm, need 3100 gallon.
In all consign 2700scfm, little 400scfm. Below optimal circumstance, through using the air that store at be in short supply, the storage tank that computation gives maintains time to be 5 to 6 minutes.
If blow a model to continue to run above 6 minutes, systematic pressure will drop 480psig is the following.
Lack effective memory
The problem that another need solves is the memory with effective lack. Store at present cannot maintain 3 successive even the mould of two rectangles moves. It is too small also, cannot make the system maintains pressure inside time of permission new to load, make compressor of centrifugal type air is in thereby stop and undertake uninstalling mixing during new to load to load.
The basis watchs the version of result and plant personnel, the plant is current because of low-pressure problem, during blowing model mould to start carry to go especially, meeting occurrence bottle is unqualified phenomenon.
To solve this problem, storage capacity arrives from 414cu.ft make an appointment with 1000cu.ft. . Worst circumstance may be 3 moulds that blow model are opened, two moulds that blow model are shut. Discharge drops make an appointment with 1400scfm, the line 3a that remains 1600scfm only and 3b (after maintenance) . Current, air compressor is in a centrifugal type to play model status completely, but once blow model mould to start, must new to load. The mould that blow model needs 1.5 minutes from begin total flow demand, shunt excitation blows model air to reclaim alive system. Initiative demand will be very low, increase to make an appointment with 1800scfm next, reclaim as blowy gas finally of the system start drop 1400scfm.
High pressure is centrifugal of type air compressor blow / the entrance is worth control from blow completely be fully loaded with need about 3 minutes. From any signal that blow a model to start air compressor defer can increase the to load time that this allows.
Unit of new move back and forth from carry 50% load to react to the permission of 100% load time is less than a minute for nothing, but do not need such short period, because this may bring about taller maintenance problem. Capacity of the storage after revising increases, will allow such doing, the memory after revising increases will allow such doing, wh whichever unit is online operation, arrive from 550psig inside a powerful person of 580 Psig, go to discharge adjustment 548psig. When in enraging compressor to blow modular process in 3 when centrifugal type sky, full load setting is 550psig, the operation should be done very well.
The condition gives to fall in these:
Although time = is poured out of completely in 1400scfm when, also be 3.8 minutes about.
Maintain the greatest pressure to arrive from 550psig of 480psig discharge pressure, at worst, this kind of memory allows to exceed 3.5 minutes. Inside a minute of cycle time that predicts in device of move back and forth, pressure can drop only make an appointment with 2psig.
Because high-pressured air system is used technically at blowing model process, if was installed,run a system, can install assorted to load / uninstall signal, from blow model to start / break alarm activations, rose to compress further air is supplied and play the time between model.
Had relevant data and dynamic to all sorts of operations of crucial equipment process understanding —— this is considered as baffling —— to become clear almost rise, successful way becomes clear rise.
After the system is balanced, important is index of monitoring key function, install ” of “ red flag, adopt in time correct measure. Blow model mould monitoring to PET, we suggest at least the pressure that monitoring blows model mould every and discharge. Next, have its and computational level comparative. Do not allow demand growth. If the graph is shown 5 times, the correct discharge of the mould that blow model is measured should be before air container. If be done not have on control plate, air receiver will conduce to the problem of low in-house pressure in eliminating the mould that blow model (E) .
Remember please, this exercise involves high-pressured PET to produce a course, but no matter what pressure, production or process are, when the target be when balance any systems with proper measurement and data, this strategy can act well.