US 2276883 A
Description (OCR text may contain errors)
Patented Mar. 17, 1942 UNITED STATES 2,276,883. APPARATUS FOR' PREHEATING LIQUID CARBONACEOUS Ewald Schn and Alfred Schiwy,
MATERIAL Buer, and Ewald Wochner, Ludwigshafen-on-the-Rhine, Germany, assgnors toHStandard Catalytic Colnpany, a corporation of Delaware Application February 11, 1939, Serial No. 256,002
In Germany The present invention relates to the treatment of liquid distillable carbonaceous materials containing solid matter in dispersion with hydrogen or gases containing free hydrogen under high pressures of at least 50 atmospheres, preferably atj 5 least 100 atmospheres and at high temperatures above 300 C., usually between 400 and 550 C. and more particularly to improvements in tube preheaters to be used in the said treatment.
The present invention is of particular iin-310 portance for the destructive hydrogenation of bituminous coal in which the coal is made into a paste with oil, and preheated in a tube preheater. Further, the present invention may be applied with advantage in the destructive hydro-x15 genation of liquid initial materials, in which solid catalysts or other solid materials are suspended. The tube preheaters as hitherto used for the preheating of coal-oil pastes usually consisted of a long passageway composed of vertical tubes ,20 which at their upper and lower ends were connected with each other by return bends. Through the passageway thus made the material to be preheated was pumped and indirectly heated during its passage by heating gases.
In practical operation in tube preheaters of this type failures occurred, mainly consisting in failures of the return bends at the lower ends of the vertical tubes, due to damagesdone to the construction material which was partlyworn30 away. z
We have after intensive investigation of all 'of the phenomena which occur and of possible measures to avoid the damages to the preheater quite unexpectedly found that the damages to the pre- V 35 heater can be counteracted in an effective way by the application of return bends protected by a material having a Brinell hardness of more than 400 from attacks by the fluid substances. This protection may be effected by the application of-. 40 corrosion resistant materials having -a Brinell hardness of more than 400 for the construction, coating or lining of the return bendsor of internal parts protecting the bends against damages, or by providing at the endangered parts of the ..45 return bends buers formed by a construction material ofthe said hardness.
In the preheating of bituminous coal pastes, return bends in accordance with the present invention have, in particular, to be applied in the 50 temperature zone of 200 to 375 C. (the temperature being measured in the material to be heated), and outside this temperature zone other bends may be employed, if desired. More particularly, the temperature zone of 250 to 350 C., 55
May 1s, 1937 1 claim. `(o1.
has been found as a dangerous zone in respect of the damages, when treating bituminous coal. Inv the case ofpreheating coal-oil pastes the 'return bends should be preferably` protected by a matev rial having. a Brinell hardness of between 400 and 600, say about 550.v
The return bends in accordance with the present invention may be protected in various ways.
' The return bends of the ordinary type maybe constructed of, coated, or lined with a material having a Brinell hardness above 400.
The return bends may be provided with' interchangeable tube-like piecesv t" be insertedin the return bend, constructed of, coated or lined with materials having a Brinell hardness above 400.
A bend of this type is illustrated in Figure 1 of the accompanying drawing. The cast piece (A), in which the return of the direction of flow takes place, isl fixed in a piece (B), into which it can be introduced from the side through an opening which can be closed by a closure (C). The curvature of the passageway in the return bend may be Iiatter than inusual return bends for constructional reasons. The mixture ofv liquid and gas llows outpfrom tube (D), through the return bend into the tube (E). f
The return bends may also be so constructed, that, -for example, the passageway for thecarbonaceous material is provided with buckets, 'for example, one opposite each of the tubes conf nected by thereturn bend. In these buckets oil `is collected which forms a buffer against which the material passing through the preheater The oil collected in the bucket may also be converted into a coke-likemass Which is very resistant against erosion, and protectsthe underlying wall of the returnbend which in thisvcase may be constructed of a material of less hardness.
An exampleof this type of return bendis illustrated in Figure 2" of the accompanying drawing. In the return bend (A) made in one piece, the passageway for the carbonaceous material is'provided with twobuckets (C) and (C'). The bend isprovided with a closure (D). The space indicated with dots, is filled with coke, infcase the liquids to be heated have a tendency to cokify. The coke then acts as a protective layer.
This type of return bend may also be constructed in a diierent way by providing only one bucket opposite the tube through which the material flows in the direction of the bend or by providing the second bucket at the side of the bend Where the material coming out of the curve of the bend bumps against the wall, or by providing buckets at the sides and at the ends.
Another form of bend in accordance with the present invention is illustrated in Figure 3. The left half of the bend has the form of an ordinary 5 T-piece. The lengthening piece at the lower side contains an easily interchangeable part of great thickness (B) made of iron or resistant material.
The return bends may also be provided with Y one or more internal constructions of material l having a Brinell hardness of more vthan ,400, which protect the inner wall of the return bend by catching the fluid coming into the bend.
Examples of such constructions are illustrated in Figures 4 and 5. According to Figure 4 the l5 return bend is provided with an internal interchangeable part in the form vof a scoop (B). Figure 5 shows this scoop (B) constructedinthe middle of the passageway. Figure 6is'a section along the line a-b of Figure 5.
"The same constructionsv which here'have been shown for the lower return bends lmay of course also"be'appliedaatthe upper bends.
The `expression materials `having a Brinell hardness 4of more than 400"when-used in this 25 application means metallic substances of the said hardness andalso non-metallic materials the' hardness of `which While usually determined in' another way'is Yashiglfi Vas that ofa metallic ksubstance having a Brinell Yhardness of more* than 400. Y
As examples vof materials having a Brinell hardness of more than A00 maybe mentioned special castalloys with a high content of chromium 'and a small contenty of-silicon, molyb-35 denum or cobalt. The v-Brinell hardness values of these materialsare between 500 and 600 degrees,
" the tensilev strength isbetween -and 90 kilograms per-square millimetre. -The base-material` "may be vferritic withA intercalated carbides o'r-'40 'material similar to"ledeburite.
The cast pieces 4are of-such hardness-that "their surfaces can practically not' be `machined or otherwise worked. The carbon 'content of-the alloys should be 45 low and preferably below lvper cent.
Typical examples ofalloys employed Yaccording jto the present invention have Ythe followingcomposition:
Also alloys with a still higher content of chromium, for example, of 20 to 30 per cent of chromium together with, for example, molybdenum and, if desired, cobalt may advantageously be employed. The said alloys are usually hardened to attain the desired Brinell hardness.
` These materials are of particular advantage for the construction oi the saidV interchangeable tubellike pieces. Suitablek materials for this e purpose are also ceramic masses, for instance fire proof stone ware'or porcelain, or materials 1 treatment.
having as a main constituent aluminium oxide or silicon oxide, for example corundum or hard glass as quartz glass.
Using these substances as construction materials for the tube-like pieces to be inserted in the return bends these pieces can be more easily interchanged if it is necessary. The space between the preheater tube and the inserted tubular piece is ordinarily lled with coke, in case the liquids to vbe heated have a tendency to cokify, and the tubular piece may be merely removed by dashing it. But this dashing can be 'more easily carried out if the piece is made of the said non-metallic material.
AAs example of coating materials having said Brinell hardness may be mentioned special hard high melting enamels.`
That the enamels in many cases must be high melting is a special condition caused by the fact that the steels, usually special steels on which the coating is made require a heat treatment 'in order to obtain the desired properties. The
enamel can be brought on to thev parts of the apparatusprior to, during or afterthe said heat Since the coating with enamel also is'doney atelevated temperature, the heating of the apparatus thereby occurringcan form a part of the'heating reaction giving the .steel the desired properties.
Inilany caselthe-melting point of the enamel should be some hundred degrees higher than the temperature to which the apparatus is exposed in its use.
*Although thep-resentV invention is of particular importance for preheaters constructed of vertical tubes, ity .mayl also be applied with advantage for preheaters partly `orwholly constructed of horizontal or inclined tubes, since the return bends/will alwaysbe most exposedto damages, `andmore particularly' thoserparts of the:v bend iwhere Vthe impact of the material treated is strongest mustbe constructed in accordance with 'the present invention.
The rest of' the preheater may be constructed of a less resistant'material than the return bends.
The process is offparticular advantage vin the treatment` of initial materials containing chlorine s or when applying catalysts or additions having a'corrosive action suchlas hydrogen'chloride, ammonium chloride and the like.
What we claim is: An apparatus for preheating liquid ,distillable carbonaceous materials containing solidmatter '-linr` dispersion with gasesselected from the group consisting of hydrogenA andgases containing free hydrogen, before treating them under highipressure of at leastI 50 atmospheresand at'high'ftemperaturesabove 3009 C.,--which consists -ina tube 'preheater providedrwith return`l bends furnished .therein andmade of a ceramic material-as hard vaslsubstances having a `Brinell hardness of -more I.than 400.
with interchangeable.tube-shaped vpieces'xed -EWALD SCHN. ALFRED SCHIWY. EWALD LWOEHNER.