CA1255854A - Cold weather coke oven door sealant - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An improved method of sealing coke oven doors and the like which utilizes as the sealant sodium silicate, the improvement which comprises using as the sodium silicate the following composition:
Soft Water 2 - 4%
Sodium Hydroxide 3 - 6%
Sodium Borate 1 - 4%
X 4 - 8%
Sodium Silicate 80 - 90%
wherein X is a freezing point depressant from the group consisting of alkali metal formates, inorganic phosphates, water-soluble hydroxy carboxylic acids, mannitol and methanol.

Description

~25~54 Canndian Patent 1 173 778 and its corresponding United States Patent 4,425,191 deal with the utilization of intumescent chemical sealants Eor preventing the escape of gases Erom such industrial devices as coke ovens. Canadian Patent 1 173 778 describes the problem solved in the following language;
"It is well known especially from Environmental Reports and the news media that the sealing oE ovens which produce noxious fumes, smoke, dust, etc., is a diEEicult art. Only recently the coke industry in the major steel producing area oE the United States has been threatened with a complete shutdown because oE its inability to comply with the new Environmental Regulations of the Environmental Protection Agency of the United States of America and the Department of Environmental ~esources of the Commonwealth of Pennsylvania.
'An example of a coke oven which presently has sealing problems is a coke oven with a so-called Koppers Door. The coke oven with the Koppers Door utilizes an S-shaped seal for sealing the door against the jamb of the oven. Because of irregularities in the jamb and seal, gases from within the coke oven readily leak past the jamb. In cases where the seal has been damaged by loading and unloading of coal and coke, gouges occur therein, which greatly increase the flow of noxious gases and fumes from the coke oven to the surrounding air. This leakage from damaged ovens is especially undesirable since the degree of pollution caused thereby is many fold than of an oven in preferred condition. However, during long use coke ovens are damaged by the constant loading and unloading and seal cleaning, therefore, a larger and larger percentage of the ovens leak at ever increasing rates.
"Another door widely used in the coke industry is the Wilputte Door.
The Wilputte Door has a diaphragm seal and a jamb with an adjustable screw ' .

;5~54 ~or makLng contact more readily between the jamb and the door. The Wllputte Door also suffers ~rom the same sort of problems that the Koppers Door does.
great need is also felt ~or an improved sealing arrangement therein.
"Recent tests have shown that many of these doors in present operation in their present configurations do not permit operation within the guidelines set by the Department of Enviromnental Resources and the Environmental Protection Agency. The fact of the lack of capability of meeting these requirements is well known and has threatened to shut down the steel industry for lack oE coke. ThereEore, a great need is felt for an improved door sealing arrangement which would permit operation within the guidelines oE the Environmental Protection Agency of the Department of Environmental Resources.
"There are a great number of other applications where leakage from ovens and other heated chambers can be cured by use of my invention such as soaking pits used for the soaking of iron ingots during the manufacture of iron and steel, furnaces and other examples which are too numerous to mention herein."
The prepared sealant used in Canadian 1 173 778 is sodium silicate which at elevated temperatures intumesces. It is indicated that the preferred sodium silicate is applied at a viscosity between 400 and 950 centipoise.
One of the problems encountered in using sodium silicates of the type described above is that in cold weather they thicken or freeze, whereby they become incapable of being easily applied as a coke oven door sealant.
The present invention overcomes this difficulty by providing a sodium silicate composition having improved properties which makes it . ., - , .
, ' :.

~s~
~ 66S30-3~7 usable as a cGke oven cloor sealant at low tempera~.lres.
Thus this invention provides a sealant composition for coke, oven doors and the like whi~h comprise a sodium silicate composi-tion containing:
Ingrelients ~_~y_weiqht Soft Water 2 - 4%
Sodium Hydroxide 3 - 6%
Sodium Borate 1 - 4'~
X 4 - 8%
Sodium Silicate 80 ~ 90%
wherein X is a freezing point depressant chosen from the group con~isting of alkali metal formates, stable inoryanic phosphates, water-soluble hydroxy carboxylic acids, mannitol and methanol.
A preferred composition of the invention is a sodium silicate-containing material having the formula:
Soft Water 3%
Sodium Borate 2%
Sodium Hydroxide 5%
Sodium Formate 5%
Sodium Silicate 85%.
A number of different sodium salts and known pour point depressants were evaluated. Some of these materials proved satis-factory while others were not. These results are presented below using various inqredients in the formula below:
Soft Water 2 - 4%
Sodium Hydroxide 3 - 6%
Sodium Borate 1 - 4%

',~
.
- , ~
- . .' ..... ' . . , ' . ' ' ~ . ' , ' :' ., , ~ .

~S~35~s 66~30-387 X 4 -- 8%
Soclium Silica-te 80 - gor~.
In the following test the various compositions were evaluatecl by uslng a technique that broaclly reproduces the procedure used when these compositis~ns are used as coke oven door sealants. The procedure used for a coke oven door involves removiny the remaining sealant from the hot door edge areas after opening, application of fresh sealant as a sprayed-on foam to the ~ cleanecl edge areas, followec1 by door closing. Thus the spray has to give a goocl stable foam on a hot surface; the spray is obtalned using a conventional compressed-air system. The test technique used to evaluate these compositions was to apply them by spraying to a steel panel (8" x 14" x ~") at a temperature of about 135C.
In addition to observing the foam properties, ease of removal on cooling was also checked.

' TABI.E I
. _ Freeze Viscosity X Stability Point C (mPa-s) Spr~ sults Sodium chloride Stable -22 155 Good foam Sodium formate Stable -18 135 Good foam Sodium bromide Stable -17 153 Good ~oam Urea Stable -12 120 Good foam Sodium acetate Unstable Sodium Benzoate Unstable Sodium carbonateUnstable Sodium sulphate Unstable Tetrasodium phosphate Unstable Trisodium phosphate Stable -12 llO Fair foam Acetic acid Unstable Citric acid Stable -5 170 Formic acid Unstable Mannitol Stable -5 8~
Methanol Stable -7 55 Ethylene glycol Unstable Propylene glycol Unstable - .
-- : , ' 5~

In the above Eormulas :it should be noted that sodium brom:Lde and urea are not preEerred since they tend to present problems of toxic e:Efects. Also sodium chlor:ide should not be used in a preferred practice of the invention due to its possible deteriorating e:Efects on coke oven Eire bricks.

-- 6 ~

Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A sealant composition for sealing coke oven doors and the like which utilizes as the sealant sodium silicate, which comprises a sodium silicate composition containing, by weight:
Soft Water 2 - 4%, Sodium Hydroxide 3 - 6%
Sodium Borate 1 - 4%
X 4 - 8%
Sodium Silicate 80 - 90%
wherein X is a freezing point depressant chosen from the group consisting of alkali metal formates, stable inorganic phosphates, water-soluble hydroxy carboxylic acids, mannitol and methanol.

2. A sealant composition according to claim 1 having the following composition, by weight:
Soft Water 3%
Sodium Borate 2%
Sodium Hydroxide 5%
Sodium Formate 5%
Sodium Silicate 85%.

3. A sealant composition according to claim 1 wherein X is a freezing point depressant chosen from the group consisting of alkali metal formates, trisodium phosphate, water-soluble hydroxy carboxylic acids, mannitol and methanol.