Sulfuric acid is strongly corrosive, it will severely damage the human body. Therefore, careful attention must be paid to the handling.
In addition, injuries and respiratory by gas such as sulfuric acid
facilities SO2 and SO3, there is also a danger of burns due to contact
with high temperature equipment such as a furnace and converter. And these of prevention, we will discuss measures at the time of injury.
Sulfuric acid 1. Legal regulations
Fire Service Act:
The sulfuric acid and oleum, but selfishness, there was strict
regulations as a risk of the Fire Service Act, since 1990 I became a
"non-hazardous material."
However, sulfuric acid at a concentration of more than 60% has become
necessary to report to the local fire department as a "firefighting
inhibitor". For such specific filings, please contact your local fire department.
Poisonous and Deleterious Substances Control Law: Sulfuric acid in excess of 10 percent concentration will be crackdown target of this law as a deleterious substance.
Manufacturing, which tries to import you must issue a registration
application to the Minister of Health, Labour and Welfare through the
prefectural governor. That tries to sell you registration application to the prefectural governor. Manufacture, storage, sale, there are regulations for transportation and disposal.
Especially if are planning the construction of a sulfuric acid plant,
it must be a satisfying design the regulation of manufacturing plants
and storage plants.
Other than, Specific chemical substances such as disability prevention rule Petrochemical complex, etc. Disaster Prevention Law Let's keep in mind also to such.
2. Equipment Precautions
Guests can prevent in the protective equipment, than the measures from
happening accident, it is important prevention of accidents is the best.
In this sense, drying tower, absorption tower, acid coolers, acid
piping, devices that handle approximately sulfuric acid such as貯酸tank
let's always prepared to be "corrosion to leave a hole." In the sense of prevention of accidents,
1) can be as long as 2 to adopt a highly corrosion-resistant material
(such as Teflon)) In the case of metal material, regularly conduct the
wall thickness measurement and internal inspection, 3 know the amount of
corrosion) it is also happening leakage accident dikes so that it does
not lead to human accident, protection wall, 4 it should be installed,
such as double tube) acid facilities are separated as much as possible
from such passage, but unavoidable time by a notice that it is a
"danger" The ceiling to put 5) that travel on foot at risk, migratory
floor is provided, it should be in so as not to climb directly to the
ceiling board
3. When working Note
Sulfuric acid is a strong acid, causing Gekijin of chemical injury on contact with the skin for dehydration action is strong. Therefore, at the time of handling of sulfuric acid, you must use the appropriate safety protective equipment.
Protection as the protection of the face shield ... eyes (in a normal
protective glasses alone, is not allowed because there is a risk of
sulfuric acid from entering from the gap) Protection of protection made of vinyl raincoat ... body of rubber gloves ... hand
During maintenance work to deal with sulfuric acid, in advance Always place immediately water hose beside, it is essential to work while flowing water at all times. When the sulfuric acid even took the body a little, as soon as possible, be washed with a large amount of water is required.
In addition, during maintenance work on, such as tanks and pipes of
sulfuric acid, there is a need to start working with even assuming "here still filled with sulfuric acid" even after internal to the sky. Often, the was a "going was in the sky" is, it may cause a slightly remaining serious accident for sulfuric acid.
In addition, containing a metal tanks and pipes of sulfuric acid may
hydrogen gas produced by the corrosion are accumulated, This may cause
an explosion.
In the accident at I heard India, in an attempt to cut the lid with a
gas burner and try to open the tank during the stop, hydrogen explosion
will occur, there are cases that died four people.
Hydrogen is lighter, so we accumulated in the top of the container, and
from to open the upper part by a means that does not use the fire,
let's habit is to begin working with the fire after you ventilate the
interior by ventilation, if possible.
4. Safety equipment
First of measures against burns of sulfuric acid, it is to "wash with water."
In this sense, in the sulfuric acid plant, tower, acid cooler, such as
acid piping, in the high places of the possibility of contact with the
sulfuric acid, is required to be installed eye washer, the body washer.
They are, as it is not to be obstructive to not come out of water in
case of emergency, let's get in the habit of flowing water to determine
the daily time. Also, in addition to these, let's provided here and there the nozzle out of the water and I open the manual valve. This is, at the same time as the meaning of safety, also required at the time of maintenance work to deal with sulfuric acid.
To measures of when the leakage of sulfuric acid occurs, let's standing dry sand and slaked lime.
Especially sand, if caused to absorb the sulfuric acid prior to
watering to the leaking sulfuric acid, is useful because you reduce the
amount of sulfuric acid flowing into the drainage.
5. Injury time measures
I've described above, first of measures against burns of sulfuric acid, is to "wash as soon as possible water". And to wash away the sulfuric acid from the skin, there is a sense that the cooling because it burns.
Since sulfuric acid has a strong dehydrating action, and has remained
even slightly, leaving a trail of serious burns to the skin and
eventually concentrated. In this sense, it is essential that washing with water quickly even one minute one second. After sufficient washing with water, ask them to allowance and let diagnosis your doctor. If possible, let's examine a doctor with experience in medicine flaw in advance.
Sulfur 1. Legal regulations
Fire Service Act: Sulfur is a hazardous material second class on the Fire Service Act.
Since the specified quantity is 100kg, it must be carried out in the
facility as defined in the Fire Service Act when the amount of sulfur
and storage, transportation, and handling of more than this.
Also, then you need to place the workers with a qualification of
"hazardous materials handlers" (Class A or Class B second class) in the
operation site, you must have posted as stipulated in other laws and
regulations. For installation standards and other sulfur tank, Dangerous Goods Administration Study Group Author, Tokyo Fire Department supervision "Fast Facts illustration hazardous materials facility standards" It is the best. Amazon, you can net purchase at Kinokuniya other.
2. Equipment Precautions
Sulfur, and ignition easy, occurs toxic SO2 gas by combustion. In addition, since it has been kept to 130 ~ 150 ℃ in steam in order to keep the molten state, let's attention to the burn.
Storage tank and pump, with regard to the structure of the pipe or the like, " new facilities -3 Please see others "sulfur tank" of ".
Sulfur, allow it to easily solidified at room temperature, it is what
it is less likely to result in a safety problem even if leaked.
However, since it easily ignited, always Keep away from ignition
source, it is important to try to extinguish quickly if you have any
chance ignition. In the case of fire in the sulfur tank, you will first blowing steam. If still no signs of fire fighting, it will inject the water.
Usually, since it has ignited in sulfur internal tank walls and
ceiling, until the occurrence of SO2 comes to a complete stop and let's
continue the fire fighting.
3. When working Note
Molten sulfur to hydrogen sulfide odor, but usually it is not at the required level of gas mask.
However, hydrogen sulfide, because the concentration is no longer felt
to be high and the contrary sense of smell, is dangerous. In around the sulfur tank, let's implement the measurement of hydrogen sulfide concentration as necessary.
This measurement, because the method is simple and quick by the
detection tube, pump of the detector tube and measurement, let's
standing in the field. As detector tube manufacturers Komyorikagakukogyo Co., Ltd. Co., Ltd. Gas Tech And so on.
Small amount of molten sulfur is also attached to the skin, abuses
there is no other than the faint of skin to worry about cause burns,
because it is dangerous to incur a large amount, wear protective goggles
and gloves (leather is desirable) at a position other than the helmet ,
let's so as not to expose the skin.
In addition, drained from the tank and piping was carried enough, under
the attitude that "if either is filled to happens if had been" even
after you disconnect, work to face and hands, and be careful on the
position of the body Let's place.
4. Injury time measures
Poisoning of hydrogen sulfide, because there is a danger of life, to
move the injured person to a well-ventilated place, let's subjected to
examination of as soon as the doctor can. In the case of burns, as well as the general of the burn, it is important to "as soon as possible cool". This is enough even in water.
Gas 1. Danger and discovery
In the sulfuric acid plant, which flows through the containing harmful
components gas facilities such as SO2 and SO3, and aspiration of these
components by leakage accident and and respiratory failure, sometimes
leading to severe cases suffocation death.
If you have the generation of gas leak accident in equipment operation,
but SO3 in the gas as long as it is a converter or later leakage source
of discovery and it causes the white smoke of concentrated sulfuric
acid reacts with H2O in the air it is easy, in front of the boiler and
sulfur combustion furnace around than it is SO2 only, discovery of the
leakage point is difficult. For this purpose, it is recommended that you standing ammonia water.
When you soak the ammonia water in rags will close in the vicinity of
the location where leakage is suspected, if there is a leakage, it
causes the white smoke of sulfite Ammon by the reaction of SO2 and NH3
in the gas, it becomes possible to visually discover You. Ammonia water, put on poly jug, it would be good to try sprinkling in the vicinity of the location where leakage is suspected.
2. Notes on work
Let's always work to wear a gas mask filled with adsorbent such as activated carbon. As a manufacturer, Ltd. Shigematsuseisakusho It is famous.
3. Injury time measures
Move the injured person to a well-ventilated place, let's subjected to the treatment of the doctor as soon as possible.
It can cause a pulmonary edema from the rare post-injury time passed,
so some people over to respiratory It is also necessary that do not hit
the work.
1. SO3 white smoke jet accident
October 1992, from the factory length of the Malaysian company many
years of relationship, we have received a sudden international
telephone.
"Help, Ono san!"
At the time of re-start after the regular repair, and will start-up and
operation of the sulfur while stopping the circulation pump of the
absorption tower, a large amount of SO3 unabsorbed is ejected from the
chimney, the adjacent competitors factory (for export flows into was a
clothing manufacturer), a large number of employees, most of them fell a
young woman is difficulty breathing, Toka he was a great uproar in the
national news. Of course, sulfuric acid plant is shut down indefinitely.
Why? After absorption tower circulation pump has not stopped, it would not move combustion air blower? And when I heard the reason, "because the periodic maintenance that while releasing the interlock, had forgotten to return to the original" thing with.
It is a simple mistake To hear. However, the result is serious.
"From the DOE (Department of environment, Ministry of the Environment),
until it receives a complete preventive measures are said not to resume
operations, it can not be trusted even out the proposed measures, since
you are an expert of the plant maker DOE and because also would be
convinced, and I say that just to me to make the proposed measures to
come. "
Director, because it was the president with even people missed, the
next day to discuss the correspondence, it was that I'll go anyway.
With that as soon take the airplane ticket, I went to the local 3 days after the phone call.
Customer and consultation in the field, to make the idea of "also
came a large amount of SOx newly established capable of absorbing
scrubber after absorption tower", PFD, Process description, Construction
schedule other, it has created a DOE submitted documents in the field.
We came back in the stay of 10 days. In subsequent information, DOE is Toka he is convinced in my Report, who admitted operations resume. (When you think from now, you will of much use also Under the table)
Lessons
learned: In developing countries, even in the safety device, because
sometimes resulting in a start while the removed, by the going.
(Even if I say that, it takes the measures to the bottom and plant cost
will be enormous, and this will become a competitive disadvantage. It
is a place to some extent it may not forced referred to as a "no
choice". Difficult)
2. Impeller melts!
This is a construction completion and operation beginning of the trouble of sulfuric acid plant overseas.
Because the DC / DA method, drying tower, intermediate absorption
tower, and the final absorption tower, but I tower are arranged 3
groups, among drying tower and the first absorption tower that, in
particular impeller of drying tower of the pump, nearly 45 It is from
being gone clean melt in the day.
Studio is a long-established chemical pump manufacturer in Japan, is
particularly company in the circulation pump for the sulfuric acid,
which boasts Japan's track record.
The material of the impeller that has been used is one that
manufacturers have been developed purposely as "a sulfate plant
circulation pump", previously it is of being used more than two years at
large facilities in Japan and overseas.
However, anyway it sends the spare parts, it is no longer is also
melted, while repeating the feed for the next ... and gave a corrosion
test of the pump impeller for material just to make sure the
manufacturer's lab.
The result is over without a problem. Manufacturer name is "than there is this customer-specific special circumstances?".
Suddenly it Omoitachi, "there is a track record for more than two
years," the place where I had taught a third of operating conditions
that, either, exhaust gas of copper smelting was the raw material. However, the raw material of the plant that caused the trouble, is recovering molten sulfur from petroleum.
"Than sulfuric acid is too beautiful?"
"There is no such a thing, I just paid the same pump also in the country P, Inc."
P company, has to do with my company, also know well technician.
the phone to talk I was at the circumstances "recently to think of it,
since the current value of the pump motor is down, plan is to check with
close temporary stop" is called.
Question to visit the open day, where I had to show an impeller, full
of holes by corrosion, state that seen through the other side.
"It was dangerous!"
Manufacturer of salespeople, and cause differences of raw materials, it was admitted at last.
When sulfur is of raw materials, product sulfuric acid is a very clean,
is enough to pass the purification of sulfuric acid standard.
The stainless steel-based alloys, it is likely that corrosion
resistance is imparted by the non-conductive film is formed on the
surface by oxidizing ions in the sulfuric acid, but this non-conductive
film produced in (very little of the impurities) sulfuric acid clean It
will be considered are not.
(Smelting gas sulfuric acid, is considered a NOx generated in trace
amounts of dust and electrostatic precipitator pole becomes the
oxidizing ions)
Trouble is, no longer keep up with the supply to the exchange of
frequent spare impeller manufacturer, place that supplied the impeller
"for dilute sulfuric acid" with the intention of "band-aid", it can be
seen that this is long-lasting, it has been resolved at last. It was a great achievement of the injury.
Lessons learned:
1. "Examples of other companies" is not necessarily true for the corrosion of sulfuric acid.
2. "Clean sulfuric acid" is, in the stainless steel-based material is corrosive.
3. Unexpected unexpected to " sulfur by-product of "
This is a by-product from the coke oven gas of certain steel mills of
China, is the trouble with sulfuric acid plant as a raw material to sour
gas that contains H2S.
In addition to the H2S in the sour gas, CH4, C2H6, C6H6, CS2, contains miscellaneous gas of ammonia ... and so on.
By burning them in a furnace SO2, H2O, cooled to from the CO2, N2, and
sends it after the wet dust collector into the drying tower.
Equipment of commissioning is also complete, it is plant start finally.
The flowing air, and ignited in sour gas, but was gradually ... will
Yuku raise the combustion furnace exit gas temperature by adjusting the
gas / air ratio, does not increase the gas temperature is quite. SO2 concentration also remains low.
In was considered "because the amount of air is too much for the amount
of gas, combustion gas temperature does not rise is dilution", I was
squeezing the air. However, the temperature also SO2 concentration does not increase. I Yuki down rather.
"Do sour gas concentration is low for?" "Whether nitrogen is too much?"
Etc., and examine various but I do not know.
In the meantime, the site received a report with the "cooling tower
circulating liquid is cloudy" from engineers who had been patrol, and I
come to the site.
Certainly, it has liquid is cloudy. What would? And, when you look good well, it looks fine particles of sulfur.
I noticed the "Oh!".
The combustion furnace exit gas temperature does not increase, not
because the air is too much, it was because air rather was insufficient. Therefore, look combustion H2S gas is conducted to the cooling tower, where Claus reaction 2H2S + SO2 → 3S + 2H2O
The causes, are you sulfur is deposited.
(Flow meters of sour gas and air had been attached, because the
composition of the gas is uncertain, accurate flow rate ratio of the raw
material gas and air do not know)
Immediately stop the operation, and inspect, by-product sulfur, past
the cooling tower, has been deposited on the collecting electrode of
mist Cottrell, the electrode plate was covered in thick sulfur of smack
yellow .
Then round three days, still cold Shanghai of March, we clean the
Cottrell inside of sulfur using the water in the colleagues and two
people.
I was was before delivery of the plant, Chinese and Japan of the
original 請会 company also chilly as the "idea of you mistake", I did
not get to help out at all.
As lessons learned from this accident, in subsequent similar sulfuric acid plant, gas analyzer after leaving the furnace, it was decided to also be sure to install O2 gauge not only the SO2 meter. If the attached O2 meter, it is "O2 = 0%" or "air is not enough!" And because it should have found immediately.
4. Carbon steel cooling tower parts of the delivery time
In the country of new equipment, raw material gas includes a halogen,
it was decided to use a Teflon impregnated carbon steel superficial to
the first gas cooling tower.
From performance and price, but I decided to import the made in France,
after the arrival in Japan, and received contact from the Japanese
branch of manufacturers and "has cracked the gas inlet nozzle".
Of course, we should not and not replaced. If you say case replacement immediately, "We said that it take five months," the manufacturer says with.
Not a joke, there are only three months until the operation of the equipment. "Is it not somehow in a month?" "Try Kakea~tsu and France"
Since the branch office of humans are Japanese, (because it is France 8
hours late, night) in the early morning every day and will demand the
payment by phone to the local factory addressed, Lachi does not fall.
From the customer, "You, Once hit the ass in Tomarikon to the
manufacturer's factory?" But was told and the sarcasm, just immediately
after the 9.11 terrorist attacks, overseas business trip the era of
self-restraint. It does not take.
"Because pay three times the nozzle price, is not you? Expedited delivery" was also offer a.
To them "from the local plant manager," the employee had a contact with
the "no longer stomach 2 months near at all vacation. Even got much
money, you can not work if there are no employees"
I'll say that. You see, vacation! Vacation is a top priority of the French. Japanese would Komaro, but bankruptcy used by Americans anyway.
I've decided to prepared to pay the penalty, a blessing in disguise, if
trouble occurs in the construction of the upstream of the
desulfurization equipment, the construction period was delayed more than
six months. Thanks, we have achieved somehow exchange of nozzle before commissioning.
It was a good study. Later, I "made in France of the machine, only buy Na when a delivery room," the men had commanded.
Come to think of it, there was a local trading company of the president
of Malaysia of the relationship a long time ago, "I am, no matter how
you do not buy is made in France and the Italian-made products even
cheaper," he had said. The reason is, that the delivery time of the because bullshit. America is also quite irresponsible, United Kingdom Well Well, can most credit or "but Japan and Germany."
After a great deal, we have imported a special machine from France for the plant of pharmaceutical products. Because it was customer's specified by the manufacturer. But this is totally no problem. By companies that are in the Alsace region, it is a Germany-based and from the name. Alsace is historically land that France and Germany have been repeating the territorial dispute. I was thinking like "kana because that contains the blood of the Germans."
5. Chemical injury accident
Concentrated sulfuric acid, and damage to the human body, can cause severe burns. After healing also, it will remain ugly keloid-like traces.
Also my body, the side of the upper arm and the navel, there are burn marks. Both, is the wounds received in Nigeria.
This such as lighter, my cousin when I was a junior high school
student, was killed instantly in an accident that wear a sulfuric acid
from the head.
In Bangladesh, my place of work to be in operation guidance, tank
exploded in a welding spark, local people 5 people was also an accident
that death.
In Nigeria, also one of the bank's Japanese supervisor was injured
quite a large amount, it has been forced to hospital for a while.
This is, if you are working to remove the piping of sulfuric acid
together with local people, to have still contains sulfuric acid inside
by mistake as "empty", with sulfuric acid which is blowing in order to
loosen the bolts of the flange It is the thing which was injured.
Moreover, "the flange bolts, be loosened from the opposite side of the
body," "Even in the sky, in going in that are filled sulfuric acid
inside" that, did not observe that you are taught in safety education .
Concentrated sulfuric acid, because it itself is dangerous, equipment
it should be structure and material that does not go out and leak
easily.
In the past, it did not get in quite such measures for economic
reasons, because the current to enter the equipment is hand inexpensive
of good material, it is safe when compared to the old days.
To prevent the accident? Over facilities, it should be all "Fool-proof".
This is a good word, "fool even okay", in other words, so as not to
cause an accident even if the erroneous operation, or it is to design
the equipment so that not occur erroneous operation.
From behavioral, it is never "that you do not neglect the principle."
Also in the above Nigeria of accident, that it had ignored the note and
procedures that are taught in safety education was the cause of the
accident.
Eteshite human beings, is what they want to omit the procedure according to get used to.
If you have cut corners to say is "troublesome because," "since the
accident until now has not happened once," accident only when such is
the one that occurs.
And, for the time that had happened Should acid leakage, it is to keep
the proper protective equipment and sufficient number secure.
Everyone, is a matter of course. Yes, accidents happen because not doing commonplace things commonplace. When the nuclear accident in Fukushima, and never will be so much serious and did not imagine. Since TEPCO is a leading company, because I thought that the safety procedures also training also be sufficiently.
However, even pump that cools the ② furnace did not imagine tsunami of
①20m, is located in the place also power supply is low, has become
unusable everyone in the tsunami (backup was not secured in a safe
place) ③ " etc. of blunder corresponding manual was not about the
situation in which cooling water is stopped Maru "in the tsunami is now
clearly one after another. Large companies also do not take credit.
Everyone, in the accident, to a painful eye is yours. Please do not compromise in regard safety.
6. " developing countries work in. "
Domestic as well, and it has worked in the "developing countries" overseas.
The secret to achieve the work vigorously? → is "patience". Never angry Do not be. Here's not in Japan, because the opponent's not a Japanese. (In other words, "common sense" of Japan, in developing countries's the "insane")
In Malaysia, concrete sulfur pits, underground water has been entering the molten sulfur from the beginning full of cracks. Since the temperature of sulfur is also 150 ℃, of course water boils, it becomes steam. and "It's a hot spring, like," I was laughing with.
It is because you are using a "cold a minus to cement" = moisture
absorption to defective cement that became bad of coagulation. We want to focus on cost than quality. Cheap thing only is not ready, after the "on-site white somehow."
And I did not want Yari because the corrosion, but we cover all of the inner surface of the concrete layer in steel plate. And then, now Rashiku sloppy welding, steam has spouting along the weld line.
After I complain to the contractor, "In so cheap contract, very welder
and I do not hire something of qualified personnel" We Usobui with.
The fact that? I'm allowed to welding work on amateur unqualified!
Local construction work is the customer's jurisdiction. Apparently, construction managers of the customer are, they apparently have put bosom by kickback the contract money. But when you hear, in Malaysia it Toka's what "the scope of common sense."
This, rampant of kickback or bribe, so common in developing countries. In Nigeria, it was called a "dash" to a bribe to pass to the police officers and officials.
Even doodling To when to end whether bureaucracy you do not know, dash
if I get even gold, or What a sense that it is sudden acceleration?
Poor maintenance of infrastructure is also common.
In Nigeria, anyway power failure occurs frequently, but was also construction commissioning was hard.
Sulfuric acid facilities, I have a need to keep the preheat the
converter and the combustion furnace before the start, this will take
about 48 hours. Summary of the sudden if you are willing Na temperature has been rising, and "power failure".
Temperature of the converter is lowered, electricity is the place came
also temperature increase start, repetition of ... down is also "a power
outage!" And the temperature after a while.
The most frequent record, 35 times a power failure in one month. Indeed, the last became the mental state of "Kamidanomi".
Poor quality of "Made in local".
Steel pipe for boiler, to buy is called in the Japanese JIS and steel
pipe which corresponds to the STB (Made in India) has been assembling a
hot air dryer.
Once I started to completion after water pressure test, and I still
break in the longitudinal and "bread", "bread" from among you do not
reach the default pressure! Apparently, it seemed to contain impurities in the drawing direction. Hurriedly and imported from Japan, I've not managed to meet the deadline to complete, it is ridiculous deficit.
7. Of gas heat exchanger high temperature corrosion
Complaints came from customers.
"Recently, the whole of the ventilation resistance increases, it does not flow as I think the gas, production volume is down."
A.
When you take a look, there is a large resistance to the shell side of
the hot gas heat exchange of carbon steel (receive the gas from the
converter first layer to the tube side).
At the time of periodic repair, if you saw it cut open the shell, has a
whopping internal tightly packed with a thin film of iron oxide, flaky
debris that it is broken.
Thin film, have overlapped in many layers round the outside of the tube, like "Baumkuchen". At a glance, it found an oxidation product tube has high-temperature oxidation.
Indeed, since the gas temperature from the first layer converter is
about 600 ℃, carbon steel will be high-temperature oxidation. Such oxidation products are also not uncommon. However, it is amazing the amount. It does not stand still only construction after eight years.
We've heard your operations situation from the customer, here Toka he
frequency of stop-start many, deliberate long-term stop five times a
year by the production plan.
I found in it. On the surface of the long carbon steel exposed to high temperatures, of course oxidation products occurs.
When you stop the plant decreases the temperature of the heat
exchanger, the steel portion of the tube is then deflated, the portion
of the oxide from the shrinkage rate is small steel, it will peel off
from the surface.
Usually, this "generation and cooling peeling" includes, but is should
not only occur during the annual periodic maintenance, it is 5 times a
year here, that is five times faster generation of standard amenities. In other words, the eight years of this equipment will mean that hits 40 years of ordinary equipment.
Eventually, it was replaced with a new heat exchanger that was all the tube SUS304.
After that, our opinion, gas heat exchanger in a small equipment has
changed the design criteria to be from the beginning made of SUS304.
And this customer, but there was one quarrel and around the expense of the heat exchanger update, it is omitted.
8. Acid circulation piping corrosion of
In new sulfuric acid plant, as the material of the circulation pipe of
drying tower, absorption tower, it was specified the use of SUS316.
Since the customer's is a company that has been involved in stainless
steel production, and Toka I want to contribute to the consumption of
stainless steel, even a little.
However, operations start early, corrosion accident of the piping was frequent.
Elbow, cheese, such as downstream of the valve, it is remarkable to place, especially caused turbulence in the liquid.
Stainless steel, if the room temperature or less can be used in the
long-term in SUS316, but does not recommend using it in place of more
than 70 ℃ as the circulation pipe. For each impurity other factors in sulfuric acid, because there is otherwise with the case of long-lasting.
Actually this equipment, was in charge of the senior rather than me. SUS316 Once I heard the reason for the use, things and because it was specified customers as described above.
Most of the piping it was exchanged in Teflon lining pipe after all. From the customer, not issued gold because the responsibility of all us, and it has been told.
and "you, but, was the specified material of'm your" When you argue
with, "When your company that would be a professional company? we are
wrong, the duty should be there to point out that" the logic of the .
This is a fairly rough logic. Legal I do not know whether to but, but there is no not have such a feeling somehow.
"Failure both if unfortunate. If the expert, and useless compromise in technology surface"
It is a lesson that.
9. " Experts do not believe. "
The tight is the words, but in particular young people, "" blind faith
"absolutely useless" I want you to remember in the sense that.
It is not directly related to sulfuric acid technology, but young, and
there was that it tried to improve the facilities to get the SO3 by
distillation of fuming sulfuric acid.
Because what kind of material was good or unknown, prepare a variety of
test piece, put in the existing facilities, we have the corrosion test.
A result that was taken out after a certain period of time, violently
corrosion as "higher material" at the time, towards the banal material
is that the small amount of corrosion, it was what is contrary to
"common sense" at the time.
I asked to visit us in the material manufacturer's Technical Director (Dr.), and sought an opinion on this result. This person, at the time was famous in Japan as a leading expert in the knowledge of metal material for sulfuric acid.
His view "this result is weird. I wonder how the test was bad. I would
recommend this kind of Conditions if material XXXX" thing.
In his Suggested materials, where it drove by design and manufacture
this equipment, the equipment in about two months corrosion can damage,
it became the driving stop.
Again, where it was again the material test by installing a dedicated
test equipment, it became almost the same result as the first test.
Even if there is fame of how much "guru", it was learned and it is important to believe the facts as facts.
Another is relatively recent, from I become officers.
In desulfurization of coke oven gas, facilities that my subordinates
was in charge, all without put out the performance, now end up
recreating some last line that was struggling. At the same time relationship that had received an order for more than one facility, it measures cost also became huge.
The reason for this was issued from the manufacturer of the oxidation
apparatus of the circulating fluid for the "expected performance", and
that in and is a "specialized manufacturer", "there are a large number
of achievements", the person in charge was this even got to "swallow It
was "thing.
However (it is that it was found later, but), because actual results up
to now, even though height and circulating liquid composition and other
conditions of the tower did different things fundamentally and this
time, without having to pre-verification there it was that it had to
blind faith to "study results of experts".
I will Yes "expert". However, he is not a God. It is to know knowledge is limited.
So I, for the customers when the technical advice "as above, but I
think, whether or not adopted, please judge your company's
responsibility" we have always said.
10. Impatient Na-Na get angry, give up
I have to work with quite long China local.
Initially, this word that was to ask from the direction of the local representative of the trading company. It seems to knowledge of business in China.
until the promised deadline to answer is no. Or it brings up again the conclusion of the previous meeting. Come was unabashedly a request not in the contract. How thought to stick to common sense out of the theory to the ...
And, here we are a few people, over there in the 10 times the number of people, you have been bubbling over unanimously.
In Shanghai Baoshan steel plant project, the construction period up to
completion after receipt of order in the first place was 4 years 6
months.
Was told to complain and "yeah! So if I do not I get a acceptance
nearly five years even if the delivery?" From equipment manufacturers.
From the instrument manufacturers "When you start the more, this time
ordering our instrument was probably all specifications are revised, can
not by the delivery of the same thing." It was also said to be.
And, impossible to achieve inspection criteria one after another.
"China-made equipment, the Well of you? Irassharu made in so strict
standards, and import I want to," To tell you the irony and, undertone,
in spear, and it while it says "I can not be in China."
Even if their own is possible, but I do it to the Japanese.
Because say that too insane, "such claims, I will not deviate from the
common sense of the world" When chide with, "Ono teacher, Japan has a
population of 130 million people. We Chinese are 1.3 billion people. Our
people would be common sense of the world, "he said. No early, it does not come true.
Still, I, than the Japanese colleague who accompanied were, did not feel uncomfortable too strongly.
Maybe, "to say only this, Chants I wish I wonder there is a reason"
and, what because you have respect for the other party in its own way.
Even so, when you show off to juniors who are involved in business in
China for more than experience in active duty, that of the "now is also
true."
Will the "Chinese funny"?
No, no, if you think it is now close to the position of third party,
too homogeneous, be that those of Japanese society of "supposed to be
seen not say" is heterogeneous in the world. In that sense, "more of us the world of common sense," it was Kyoben Shanghai technicians of words, might was right.
11. There is no money from?
1990, we have come to the sulfuric acid plant commissioning of Panzhihua steel plant of the mountains of Sichuan.
We are making the sulfuric acid from the secondary raw sour gas at the time of desulfurization coke oven gas.
Our basic design and supply of some know-how equipment, in charge of
commissioning the company detailed design of Germany, the Chinese side
was the charge of the construction and supply equipment.
From the Chinese side "of the blower capacity There are three times the
required amount, what? What should I do when" It was asked. "Since the budget is tight," and Toka he has been looking for second-hand goods.
"From the blower outlet, please add the circulating gas piping back to the drying tower" I have been advised. Because too raise the gas temperature in many so recycling, it is dangerous if you do not cooling.
However flowmeter of the process gas because that is attached to the
outlet of the drying tower, is also required flowmeter to recycling
line. Than that "money to buy a flow meter is ...", I was raised doing in the service until the orifice of the design. Install the differential pressure gauge of visual, we were working to flow.
Chinese-made liquid level gauge attached to the pump tank of the absorption tower is also broken again and again. The wetted parts and Toka's are using a diaphragm of SUS316.
When you advice as "should I frog Hastelloy-C", as the "if made in
China, you can buy five or more made in Japan one minute", "China is not
made in", "please buy from Japan", to say The did not hear.
Then, in Shanghai of sulfuric acid equipment, orders the work to switch
the thing was pyrite raw material sulfur raw materials, after four
years of completion, was visited in aftercare at the request from the
customer. It is that of 2000.
This seat was asked "because blower capacity is excessive you want to
an inverter motor. Is it true, but say that it pays for itself in one
year?".
While I think that I wish not to change much, "Better yet, please had
made the blower" You have advised, and whether you run ...
Eteshite in developing countries, say that "in the next few years will rise to profit" will not be welcome. Since we are replaced by more and more To leave the company, by the time you make a profit because his is not.
Private companies and foreign is to same is true in China, because I
want state-owned enterprises is also quite personnel changes, you will
of similar. In other words, to raise the short-term performance, "to keep the current investment" it is's the best.
"Because there is no money" ... really, "I do not want to lower performance."
Of travelers from China of this year's Spring Festival, "爆買 physician", Is there in the place where it is.
12. Black out (power outage)
As I wrote, even "work in developing countries", in the work in
developing countries, infrastructure is different is very difficulty in
whether or not been established. And do you say, but such infrastructure is what "still developing" So, "developing countries". Many and will be in direct problem the most, it is a power outage. The commissioning of Nigeria of sulfuric acid equipment, there was 35 times of power outage in January. It is preheated, barely power failure If you think the temperature went up. Barely been started, and ignited sulfur power failure If you think ... that began to be sulfuric acid. In addition, the troubled, it the prospect of recovery do not know. Because you repeat too, it has increasingly young I also become pessimistic. In Malaysia, construction initially at (1985) point, there was occasional power outage. However, in the current 30 years, it is that of the no it as good go at all To. Again, it's neat development. Young people, the electricity will be folded anywhere, anytime I think something in common.
But, even in Japan, I have (which is before from now 60 years!)
Childhood in, because the power failure was not uncommon, it was what
had been equipped with a sure candles in the house. Come to think of it, the essentials candle in each house as well in Nigeria.
Night, becomes a power outage in the middle of it is a mah-jong in
Japanese to each other that had been dispatched in commissioning, and
make a candle to the four corners of the table, we also can do as "Qi",
"Pong" in the dark. When the electricity is restored see each other's face, it had become completely black with soot. It called Black out in English that of a power failure.
Since the lighting of emergency is also small, and will meet in a power
outage the night in developing countries, you really will experience
the "jet-black darkness." Scary thing.
Calculation:
During the operation management of the sulfuric acid plant, or you need
a huge amount of computational work at the time of new construction and
renovation of facilities. Here I am not going to describe all of them.
Please refer to a relatively opportunities are many, and so a brief description of some for a useful calculation.
- Dilution during the amount of water in the sulfuric acid
- Ditto acid temperature
- Heat loss from the equipment
- Emissions possible SOx amount (K value regulation)
- Etc.
Of sulfuric acid dilution water :
1) concentrated sulfuric acid (98.3% H2SO4) was diluted with water, Calculate the amount of water when making 62.5% H2SO4.
Traditionally, for each amount of sulfuric acid for obtaining a
concentration of the target by mixing different concentrations of
sulfuric acid, a convenient method of "square law" is famous.
This is, each of sulfuric acid concentration A% before mixing and B%,
and a sulfuric acid concentration C% of the target place as described
below, and the subtraction in an oblique direction, respectively.
As a result, (CB) :( AC) = concentration A% of the amount of sulfuric
acid: It becomes the concentration B% of the amount of sulfuric acid.
For example, 98% H2SO4 (A) and 20% H2SO4 (B) are mixed with 94% H2SO4 when making the (C) is
CB = 94-20 = 74 AC = 98-94 = 4
In other words, it is the result that should I you mixed the 98% sulfuric acid = 74 parts and 20% sulfuric acid = 4 parts.
Therefore, the solution of the question
To 98.3% 62.5 parts of sulfuric acid, and it will may be added 35.8 parts of water (57.8% of concentrated sulfuric acid).
* In the case of mixing of fuming sulfuric acid are each displayed in
all SO3 amount, and then apply the rectangle method in the same manner.
For example, "a mixture of fuming sulfuric acid and 94% sulfuric acid of 25% free-SO3, 98% get a sulfuric acid" case:
| 86.22 |
| 3.27 |
| 80.0 |
|
| 76.73 |
| 6.22 |
∴25% freeSO3 fuming sulfuric acid: 94% sulfuric acid = 3.27: 6.22 I will be mixed in a ratio of.
At the time of diluted sulfuric acid temperature :
2) in the case of the above example, Calculate the temperature of the product 62.5% sulfuric acid. 98.3% sulfuric acid is 40 ℃, the water I and 25 ℃.
This is First, you must calculate the heat of dilution of sulfuric acid. There are several ways, engineering sulfuric acid (moat, Nakagawa AD, Inc., 1967) According to the,
If you want to dilute the H2SO4 of 1 mol of water n mol, the dilution heat
Q = 17860n / (n + 1.7983) ··· (1)
Q: cal / mol-H2SO4 n: mol-H2O / mol-H2SO4
When generation to the sulfuric acid concentration = 100A%
A = 98.08 / (18.02n + 98.08) Therefore, n = (98.08 / 18.02) (1 / A-1)
When you assign this to the equation (1)
Q = 97209 (1-A) / (5.4428 -3.6445A)
Therefore, 100% H2SO4 → 98.3% H2SO4 dilution heat of: Q1 = 97209 * (1-0.983) / (5.4428 -3.6445 * 0.983) = 888cal / mol-H2SO4
100% H2SO4 → 62.5% H2SO4 dilution heat of: Q2 = 97209 * (1-0.625) / (5.4428 -3.6445 * 0.625) = 11,518cal / mol-H2SO4
∴98.3% H2SO4 → 62.5% H2SO4 of dilution heat ΔQ = Q2 - Q1 = 10,630cal / mol-H2SO4 = 108 kcal / kg-H2SO4
98.3% When will the amount of the sulfuric acid and 1kg, Heat of dilution Hd = 108 * 0.983 = 106kcal
98.3% held by the sensible heat of sulfuric acid H1 = 0.344 * 1 * 40 = 14 kcal Water holding sensible heat H2 = 1 * 0.578 * 25 = 14 kcal
∴ held sensible heat of the generated 62.5% sulfuric acid H3 = 106 + 14 + 14 = 134kcal Assuming this temperature and 120 ℃, specific heat = 0.553kca / kg / ℃, generating 62.5% sulfuric acid = 1.578kg so
Generated 62.5% sulfuric acid temperature = 134 / 1.578 / 0.553 = 153 ℃
Boiling point of 62.5% H2SO4 is so 145 ℃, it will be sulfuric acid boil.
In such a case, and to cool the sulfuric acid immediately after mixing
in a shell-and-tube cooler, it will be that the heat exchange is
hindered because of the bubble of steam in the tube, and diluted and
cooling is divided into two stages How it is taken. → "Various sulfuric acid production process", " dilute sulfuric acid See "
For example, * first stage 98.3% → 80% * The second stage 80% → 62.5%
As a method of calculating the heat of dilution, there is also a way to use a chart of Othmer and Fusullo et al. Numerical value of the data to be used is different in each subtle, practically no problem. (Of course, such as the heat transfer area of cooler you should look at a sufficient margin)
Ceramic internal of an absorbing tower, Chiba, Japan
At the beginning :
Sulfuric acid facilities, is the fight against every day is corrosion and oxidation.
When you mistake the selection of material, it can not write leads to all stop of injury or equipment. Maximum attention is required.
Optimum recommended material at the current time of each device, " new facilities "and" equipment update in ", please refer Because it is stated for each device.
That want to keep in first remember corrosion by sulfuric acid,
For the metal material:
1. Corrosion by sulfuric acid, significantly different concentrations, temperature, dissolved components.
In the metal material, generally, "the amount of corrosion temperature increases 10 ℃ is two-fold," It is said that. Since this is said to metal corrosion = chemical reaction of sulfuric acid and the metal, because the reaction rate is increased due to the rise of temperature.
There are no related at all relationship of concentration and the amount of corrosion. High concentration of sulfuric acid, it can not be said always to have strong corrosive.
Although strong lead = dilute sulfuric acid which are corroded rapidly to but no problem in practical use dilute sulfuric acid in carbon steel = room temperature in concentrated sulfuric acid resulting in soluble in concentrated sulfuric acid
In addition, it also varies in the dissolved components.
Sulfuric acid of sulfur combustion type, you may even those close to the dissolved impurities less purified sulfuric acid, but it is not said to be a "good because few impurities".
I, luxury nickel alloy circulating acid pump impeller, "even though not anything in the refining gas sulfuric acid plant, is severely corroded by sulfur burning sulfuric acid plant" was the experience of. That this is, during the refining gas is a very small amount, but that metals such as Cu, etc. have been dissolved NO2, these raw materials are beautiful too far sulfur to make a non-conductive coating, it could not be non-conductive coating but it has been estimated to cause.
So, "Examples of self-factory" will be greatly helpful, but "Examples of other plants" must not be to blindly reference.
If consult, let's strictly compared with the conditions of the factory conditions and their own factory.
2. Note the turbulence.
In particular, in the piping, you may site = elbow caused the flow of turbulence, cheese, corrosion downstream such as = valve seen violently. Especially often seen in stainless steel, these sites when a concern you should keep exchanged like Teflon lined.
3. Note that even material itself is changing.
With the advancement of technology, the material itself is improved in the constant component is changing subtly. Once upon a time was not a problem material also might cause problems now.
We do not talk about details because belonging to the know-how, when you update the process equipment using a stainless steel alloy, even though such should have been using the material "the same as the original", severe corrosion accident occurred.
When you try to study, has become very small compared to the original C (carbon) content of the new material, this was the cause of the corrosion.
JIS provisions of the C content of stainless steel, because there is only an upper limit, manufacturers I had been reduced more and more To the amount of C is, the "improvement for the service."
So, it is really "the same as the old days" thing of? And you do not have to change? Let's leave well to check the material manufacturer.
Inorganic materials (ceramics, glass, etc.) and organic synthetic resin:
These materials, when compared to metals, it is insensitive to changes in the concentration of sulfuric acid and temperature. If there is corrosion resistance in concentrated sulfuric acid, most things no problem even in dilute sulfuric acid.
However, for fuming sulfuric acid, Teflon and carbon it is not recommended.
For more details, it said in particulars.
References :
For documentation that summarizes the various corrosion-resistant material with sulfuric acid, it has settled well is old "sulfuric acid Handbook" is the best. (But it is out of print)
Other, there is also a book called "chemical equipment corrosion-resistant material table", which summarizes the corrosion-resistant material for various chemicals in addition to sulfuric acid. (This also has become out of print)
At present, materials such as corrosion curve of metal, probably most of the fastest way is to get the technical documentation is offered to manufacturers.
(Without permission, it had to publish anti-corrosion data to the net every manufacturers such as Mitsubishi Materials and Japan metallurgy, but no longer now. The reason is unknown.) * After this, we will continue to write the corrosion resistance and applications for each material.
Metal material:
"Metal material is corrosion with any time to varying degrees."
This also is true that I would like you to remember. It will not be long-lasting equipment to understand the "difference of degree."
Carbon steel :
SS Toka SGP in JIS, is a material that is expressed, such as the STPG.
The least expensive as the metal material, will that easy to come by.
Is this,
1) concentrated sulfuric acid 2) Same as above oleum 3 at room temperature (room temperature)) molten sulfur
There is practically sufficient corrosion resistance.
However, since the corrosion of certain parts of the flow will be greater than the stationary state, the use of the pipe is avoided, it should be used in the product storage tank.
(Room temperature of the piping SUS304 or 316, would be sure Teflon lining in high temperature of piping)
Other, but it has been used for the following sites, in the case of new construction and remodeling Let's say right.
(If economically afford)
A) converter around duct → converter is the first layer outlet duct SUS304
B) gas heat exchanger → tube and channel cover SUS304
C) combustion furnace and towers of the casing → SUS304
D) sulfur tank → ceiling SUS304 Stainless steel :
There are very many kinds, but I will in time in roughly SUS304 and 316 for sulfuric acid.
This of most applications
1) at room temperature of concentrated sulfuric acid, piping fuming sulfuric acid, pump, valve 2) converter around gas butterfly valve 3) molten sulfur valve It is. Other, there is also above A) ~ D) applications.
In addition 4) drying tower, absorption tower circulation acid piping
There is also in that factory used to, but since there is also a case that caused the trouble by being violently corrosion, as long as there is no past performance at the factory, is not recommended. Generally speaking, it is to have good when the low acid temperature.
Stainless steel, the temperature of the acid, the amount of impurities, the flow rate, can vary greatly, such as in the corrosion behavior presence or absence of flow of turbulence. In addition, it is also affected by the carbon content of the stainless steel itself. Performance of a factory, also necessarily fact that does not apply to other plants, it is a place well hear.
It is a special purpose, but the heat-resistant stainless steel such as SUS310S will be used in the boiler bypass gas valve in the sulfur burning.
High nickel alloys :
There are a wide variety of alloys for each manufacturer, but what is often used in sulfuric acid
1) Hastelloy-C group 2) Carpenter-20 (Alloy20)
3) pump manufacturer that has developed (such as Pilomet)
Below, we'll explain.
1) Hastelloy-C group
It is developed corrosion-resistant alloy of the United States Haynes International Inc.. Although initially it was Tadano "C",
Then various kinds have been developed.
The is often used in concentrated sulfuric acid C276
C22
It is two.
(In Haynes's home page is located that there is a corrosion resistance to "B3" because sulfuric acid, but this is the original as for anti-HCl)
C276:
Components
Ni 57, Cr 14.5-16.5, Mo 15.0-17.0, W 3-4.5, Fe 4.0-7.0, Co≤2.5, Si≤0.08, Mn≤1.0, C≤0.01, V≤0.35
It is widely used in the plate cooler for the tower circulation acid.
According to our catalog Haynes "by preventing particle deposition in the weld heating section, and has a high degree of corrosion resistance without treatment after welding" "and localized corrosion, and there is an oxidizing, resistant to reducing substances." → Haynes catalog C276 → corrosion curve of C276
Just "metal material is corrosion with any time to varying degrees," he said. C276 is no exception. In the plate cooler, the entrance of San is corrosion most early (because the temperature is the highest).
Therefore, after you have used a few years, you need to check is opened.
Also this time, also help to extend the life of the entire cooler to the entrance and exit of the acid in reverse. → " maintenance "," acid cooler "
C22:
Components
Ni 56, Cr 22, Mo 13, W 35, Fe 3, Co≤2.5, Si≤0.08, Mn≤0.50, C≤0.010, V≤0.35
This also seems to be used to the plate cooler.
In the catalogs of Haynes, "especially" C276 has excellent corrosion resistance than "pitting, crevice corrosion, you have stated that there is strong resistance to stress corrosion cracking", concentration for sulfuric acid in the same catalog - temperature - corrosion amount Look at the graph and, but should not be seen as there is much difference in the 98% H2SO4. →
2)Carpenter-20 (Alloy 20)
It has been developed by the United States Carpenter Technologies Corp., component Ni 34, Cr 20, Mo 2.5, Cu3.5, Fe balance, Nb≤1 (≥C * 8), Si≤1, Mn≤2, C≤ 0.06
Hastelloy-C22 as well as has been touted as "pitting, crevice corrosion, resistant to stress corrosion cracking" but it seems to the extent that is now being used in wire mesh demister of the tower exit.
3) pump manufacturer that has developed (such as Pilomet)
Ltd. Matsuda pump Works of Pilomet, such as Lewmet of rice Lewis is something that has been developed as a material for sulfuric acid pump.
However, even these, you must be careful because you may be subject to corrosion by the "impurities" of temperature, other than the sulfate concentration.
Tantalum :
Tantalum, 100 ℃ almost completely in the following concentrated sulfuric acid (corrosion weight = 0) is shown a corrosion resistance, shows no practical problem corrosion resistance at 200 ℃ or less.
However, for very expensive, it has been used parts that are used special a small amount, for example, the diaphragm of the diaphragm type pressure liquid to a sulfuric acid plant.
Also by heating concentrated dilute sulfuric acid is used as a lining material in concentrated cans in equipment for the production of concentrated sulfuric acid.
However, the fuming sulfuric acid it must be careful because it is corrosion even at low temperatures.
Cast iron :
Selfish, cast iron had been widely used as piping material and material of acid pump for concentrated sulfuric acid.
(Fuming sulfuric acid, next to SiO2 is silicon content in the cast iron oxidation, this can not be used because that would divide the material itself swells)
The low temperature of concentrated sulfuric acid at a low cost and has in its own way, but in cast iron distinctive of "su" problem, one day you suddenly or cause a sulfuric acid leak accident.
Production of cast iron, so typical 3K is the work, has been migrated production from early to subcontract overseas, seems to have become the maintenance of quality it is also difficult.
As for the concentrated sulfuric acid, and high-silicon cast iron containing around 15% Si, there was a low chromium cast iron containing 1% less than the Cr, almost all stainless steels and high nickel alloys currently are alternative such as Teflon lining You.
High silicon cast iron, seems to the electrode of current even electrolysis equipment being used.
Lead :
Lead is also a material that has been widely used in the nitric acid-type era sulfuric acid.
The dilute sulfuric acid there is corrosion resistance, but it can not be used because it soluble in concentrated sulfuric acid.
Even in contact sulfuric acid, although in dilute sulfuric acid portion of gas purification equipment other than sulfur raw materials (such as the casing of mist Cottrell) was used, this was also replaced by the FRP and other organic material. Again and price, it seems that is a problem that the weight is increased.
By decreased demand, craftsman itself to work also declined. Lead, because there is a use as a shielding material of nuclear power plants in other than sulfuric acid plant, there in is like Some craftsman in its own way, under the influence of this accident, I will also decrease.
It had been also hard lead with increased hardness by the addition of 3-12% of antimony in the lead used in such dispersion tube of pump and cooling tower, which was also no longer mostly seen now.
Lead, the hardness lead both, it is now replaced by the plastics and ceramics such as Teflon and PP.
Other metals:
In other metals, gold, platinum is about to have a sufficient corrosion resistance to concentrated sulfuric acid.
Platinum, seems to have been used as a spray of dilute sulfuric acid in the nitric acid-type equipment such as lead room selfishness. (It is sometimes so stolen)
Other metals, it can safely keep in stores almost all the "unavailable" for the concentrated sulfuric acid.
For the dilute sulfuric acid, titanium, zirconium seems there is also some of the corrosion resistance, etc., but does not have expensive late almost used. Inorganic materials :
Acid porcelain :
Acid porcelain, lining material and sites that is in direct contact with the sulfuric acid, such as towers and pump tank as brick, has been used to tower packings such as interface Rochus saddle.
The component basis, is what good be considered the same as porcelain for tableware (such as Arita). Come to think of it, is a leading manufacturer of acid porcelain Iwaojikikogyo Co., Ltd. is located in Arita. Originally, it seems to be a ceramics manufacturers such as tableware.
Concentrated sulfuric acid, there is a nearly complete corrosion resistance in dilute sulfuric acid. In my experience, acid brick that was used 50 Toshi-yo also, apparently no different at all new.
Recently, domestic to that of the quality of the clay has been reduced, it seems to have fallen somewhat from those quality-old. The color of the bricks, was a complete white things of long ago, those of recently has been tinged with pale reddish brown. I will be thought that due to the impurities.
Brick is possible semi-permanent use, but the joint material to be used during construction will be affected in the sulfuric acid. Around from the gap of the joint material in the back of the sulfuric acid is brick, the casing is damaged by corrosion of the carbon steel of the casing. To prevent this, in recent years it has been made to put a Teflon sheet between the bricks and the casing.
→ "equipment update," " drying tower, absorption tower "reference
As the standard of acid porcelain, following JIS, and Iwaojikikogyo Ltd. Please refer to the catalog.
JIS R1501 general General Rules of the chemical industry for the oxidation porcelain
JIS R1503 test methods for the chemical industry acid porcelain
JIS R1528 for the chemical industry acid porcelain fillings
JIS R1536 for the chemical industry acid heat-resistant bricks
The oxidation porcelain manufacturer, NGK Insulators, Ltd. is also available.
In addition, you heard that in recent years has been around also made in China acid brick, I have never used still.
Glass :
Glass also, dilute sulfuric acid, there is a nearly complete corrosion resistance in both of concentrated sulfuric acid. (Especially in the case of hard glass = borosilicate glass)
However, since weak fragile to shock, it is rare to be used as such.
Those of the wall thickness is used for sight glass in the middle of the piping.
Also, heat-resistant glass which has improved thermal shock resistance by lowering the thermal expansion coefficient, is used for the absorption tower for purification of concentrated sulfuric acid production. This, Corning Pyrex is famous.
However, because it is expensive, recently it has been replaced by glass-lined below.
Glass lining (GL):
Glass cast iron, by lining the inside of carbon steel or stainless steel, is what was to maintain the mechanical strength and corrosion resistance.
If the pipe is inserted into the metal pipe after heating the glass tube, to those brought into close contact by applying pressure from the inside, while others baked covered with a glaze vitreous inside of the metal tube.
Prepared by the course of the latter method in such a large container. This will things to be rather referred to as "enamel".
Concentrated sulfuric acid corrosion resistance, of course, since it helps to minimize pollution of sulfuric acid by the dissolution of the metal, which is used in the purification of concentrated sulfuric acid manufacturing equipment instead of quartz glass.
In the case of printing method, since it may rarely a pinhole, you must perform a sure pin hole test at the time of completion.
In addition, it said that the excellent mechanical strength, because there is a risk of peeling is give and blow lining glassy, such blow is taboo.
And such as suddenly put the high temperature of the liquid, care must be taken because there is that glass is peeled off by thermal shock.
As those of similar applications, there is a Teflon lining, but more of the glass lining is excellent in heat resistance, it is used in higher temperature applications. It Would not it be okay to the boiling point.
For other chemicals sulfuric acid, weak alkali because it is glass, also violently it is affected because the phosphoric acid in the fluorine is difficult to use. It is also affected to a high temperature of steam.
Currently, for to alkali, so it seems there is also a special case, such as for a pair of steam please try to consult with the manufacturer.
As a manufacturer, there is a following.
Ltd. Kobelco Eco-Solutions
NGK Insulators Ltd.
Hakkosangyo Co., Ltd.
AGC Technology Solutions Co., Ltd. - insertable GL piping only Fire-stone :
This is a kind of pumice that lava was Deki solidified, those of Niijima production of Izu Islands have been conventionally used.
Lightly (specific gravity 1.2-1.4), because there are easy and acid resistance processing, it will be used in gas purification part in equipment other than sulfur combustion.
In applications other than sulfuric acid, since it also has excellent fire resistance, it is used as the acid lining material of the chimney. It is also used as a general of residential building materials.
As manufacturers and contractors, anti-fire stone Industry Co., Ltd., has Niijima Bussan Co., Ltd..
Organic material :
Teflon :
Originally with Teflon, it is that of PTFE that DuPont has developed in 1938.
PTFE = polytetrafluoroethylene (-CF2-CF2-) n
It has high chemical resistance, heat resistance, and is also has excellent properties such as low coefficient of friction, a part of the F in order to improve this because of the poor workability hydrogen, chlorine, other which was replaced by the olefin has been developed. Collectively, these are called "fluorine resin".
FEP = tetrafluoroethylene-hexafluoropropylene copolymer (-CF2-CF2-) n - (- CF2-C2F4-) m
ETFE = tetrafluoroethylene-ethylene copolymer (-CF2-CF2-) n - (- CH2-CH2-) m
PFA = tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (-CF2-CF2-) n - (- CF2-CF2OCF3-) m
PVDF = polyvinylidene fluoride (-CF2-CH2-) n
In DuPont, it will be referred to PTFE, PFA, FEP, the "Teflon", but other fluorine resin are wearing each different name, in Japan we practice called everyone "Teflon".
Although as a concentrated sulfuric acid and all organic materials in the best, without being corroded with time differences between the metal, without also contaminating the sulfuric acid by dissolution of the components, it is an ideal material.
However, other than PTFE and PFA has difficulty in heat resistance, and can not be used in oleum for transmitting the SO3.
As a lining material of many metal inner face, piping, it is used valve, such as a vessel.
As a lining material of the valve, NICHIAS Co., Ltd. is a PFA, Valqua Industries Co., Ltd. is I am using PTFE and PFA.
In addition, as a thin tube acid cooler it is used to.
When used as a gasket, the left but it will be used, flexible pinch cushioning material such as rubber in order to increase, also it has to not mix a filler of mineral in order to avoid cold flow.
Drying tower, absorption tower, and such as a pump tank for them, in towers and vessels lining the acid brick, the corrosion due to the fact that touch is across the sheet directly to the (seat lining) shell sulfuric acid between the brick and steel shell It has been made to prevent. However, Teflon because it does not adhere to brick in steel, you can paste it or use the process the surface or adhesive.
From the characteristic that it does not contaminate the product, purified sulfuric acid, has been often used for high-purity sulfuric acid.
The nature of the typical Teflon class I is shown below.
Viton :
Viton is the same fluorine rubber DuPont has developed a Teflon.
Compared to teflon, flexible, on rich in elasticity, strong acids include concentrated sulfuric acid, withstand strong alkali, excellent heat resistance (~ 250 ℃), the nature of Teflon as oil resistance, excellent in solvent resistance It also features.
Structurally, the base is what is obtained by copolymerizing hexafluoropropylene in polyvinylidene fluoride.
(-CF2-CH2-) n - (- CF2-C2F4-) m
Currently, there are those obtained by copolymerizing other tetrafluoroethylene and perfluoroalkyl vinyl ether according to the application.
In the sulfuric acid plant, it is common as a gasket of concentrated sulfuric acid for the plate cooler.
FRP :
FRP stands for Fiber Reinforced Plastics.
Because it is sometimes referred to as "fiber reinforced plastic", although it is considered that the combination of a wide variety, as being practical use,
Plastic = unsaturated polyester resins, epoxy resins, polyamides, polymethyl methacrylate fiber = glass fiber, carbon fiber, aramid fiber (Kevlar)
And so on.
Lighter than the metal, there also have strength and excellent corrosion resistance, but it will not be able to withstand it will be carbonized in concentrated sulfuric acid.
Only, it is intended to be used in an atmosphere of dilute sulfuric acid and wet SO2 gas. Washing tower, mist Cottrell of the casing, it will be used, such as the gas duct of the gas purification system.
Is it been put to practical use in sulfuric acid facilities,
Unsaturated polyester resin + glass fiber
It is a combination of.
There is a kind also in unsaturated polyester, isophthalic acid-based, bisphenol-based, there is a vinyl ester. 2 who has excellent corrosion resistance as compared to the isophthalic acid system later, it seems no problem in isophthalic acid system for the sulfuric acid plant.
If you want to use in gas purification system, in the conditions, including fluorine in the gas, because there is a danger that glass fiber is corroded, and synthetic resins such as PP as the fibers on the surface in contact with the gas, you can use the carbon fiber.
As a manufacturer, in the major
Showa Denko Co., Ltd.
Oriental Gas Kiko Co., Ltd.
Fuji Resin Industry Co., Ltd.
There is such, but since that can be anyone production if there is a resin and glass fiber, to say that small and medium-sized manufacturers is infinite number is not an exaggeration.
PVC (polyvinyl chloride):
It is one that is used in large quantities is referred to as a "PVC".
FRP Again, it can not be used will be carbonized in concentrated sulfuric acid. Is for the dilute sulfuric acid it is possible to use.
However, it is degraded by ultraviolet light, so easy to crack in the piping of the outdoors will require regular updates.
For reinforcement, which was inserted PVC in the carbon steel pipe (LP tube), while others that were plated FRP on the outside of the PVC pipe.
PVC, because it contains chlorine, from concern to generate dioxin when incinerated, seems to have been reduced use.
PE (polyethylene):
This also is what is used in large quantities as plastics.
There are HDPE and LDPE but, HDPE (high density polyethylene) made of tank and pipes are used in the sulfuric acid plant.
PE, although at high temperatures will be attacked by concentrated sulfuric acid, there is no problem in practical use at room temperature.
Therefore, the storage tank of purified sulfuric acid and, it has been used as a 20L plastic tank for the product sulfuric acid sales.
The polyethylene tank, Dairaito Ltd. is famous ones.
Those lining the PE to carbon steel piping, have been used to dilute sulfuric acid. Even for concentrated sulfuric acid, I think that it can be used as long as it is a low temperature.
PP (polypropylene):
Also PP should say representative also of thermoplastic resin along with the PE, has been put to practical use as a piping material, it seems to have become the alternative of PVC pipe.
This is also used to dilute sulfuric acid is possible, concentrated sulfuric acid, it can not be especially used in high temperature.
Rubber :
Natural rubber even though the rubber, there are synthetic rubber various Although it is a wide variety, corrosion resistance is generally to sulfuric acid "It is attacked by concentrated sulfuric acid, withstand the dilute sulfuric acid."
It is. ( Viton I except = fluorine rubber)
Therefore, it is hardly used for the sulfuric acid plant of sulfur raw materials, and are used in gas purification equipment by other raw materials. Majority is used as a lining material of carbon steel.
Carbon :
It is referred to as "carbon", but one that is improved is by impregnating synthetic resin in the synthetic graphite strength and air-tightness those used in the sulfuric acid plant, properly to be referred to as "impervious graphite" It is.
Phenol resin is common as a resin, but some impregnated with Teflon.
Heat transfer is very good, the dilute sulfuric acid there is a sufficient corrosion resistance, but it is attacked violently by generating CO2 in hot concentrated sulfuric acid. Therefore,
1) cooler 2 of sulfuric acid dilution equipment) and is used to dilute sulfuric acid cooler and gas cooler of gas purification equipment.
It used if concentrated sulfuric acid of 90 ℃ about the absorption tower outlet but should of possible, increased concentration of product sulfuric acid is abnormally in tourists operation mistake when it was used as a selfish product acid cooler, Become a fuming sulfuric acid Have closed, this time there was an accident that the entire cooler melts. Since there is such a thing, it is not recommended to concentrated sulfuric acid cooler.
As the heat exchanger for the sulfuric acid plant, it is often for shell / tube type that is easy to clean the scale, but as the heat exchanger will have this also in addition to the block type or plate type.
As a manufacturer, therefore expensive electricity rates, which account for large proportion of the cost, Japan independent manufacturers no longer. Both currently is a joint venture with overseas manufacturers.
Nippon Carbon Melthene (Ltd.) = Japan (Nippon Carbon) + France (Melthene)
Graphite Chemical Co., Ltd. = Japan (Tokai Carbon) + US (SGL)
And so on.
