Furnaces – Process – Burning pulverized fuel
Reexamination Certificate
2002-10-01
2004-06-15
Rinehart, Kenneth (Department: 3749)
Furnaces
Process
Burning pulverized fuel
C110S1010CF, C110S1010CC, C110S187000, C110S191000
Reexamination Certificate
active
06748883
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a control system for controlling the feeding and burning of a pulverized fuel in a glass melting furnace and, more specifically to a control system that feeds pulverized fuel in a glass melting furnace.
2. Related Prior Art
Melting glass has been done for different kinds of furnaces as well as types of fuels, depending on the final characteristics of the product and also regarding the thermal efficiency of the melting and refining processes. Unit melter furnaces have been used to melt glass (by means of gas fuel), these furnaces have several burners along the sides of the furnace, the whole unit looks like a close box where there is a chimney that can be placed either in the beginning of the feeder or at the very end of the furnace, it means, going downstream. However there is an enormous heat loss in the glass leaving high-temperature operating furnaces. At 2500° F., for example, the heat in the flue gases is 62 percent of the heat input for a natural gas fired furnace.
In order to take advantage of the remaining heat of the flue gases, a more sophisticated and expensive design come out, named as the regenerative furnace. It is well known that, in order to operate a regenerative glass melting furnace, a plurality of gas burners are associated with a pair of sealed regenerators disposed side-by-side. Each regenerator has a lower chamber, a refractory structure above the lower chamber and an upper chamber above the structure. Each regenerator has its corresponding port connected to the respective upper chamber with a melting and refining chamber of the furnace. The burners are arranged to burn fuel, such as natural gas, liquid petroleum, fuel oil or other gaseous or liquid fuels which are suitable for use in the glass melting furnace and thereby supply heat for melting and refining the glass making materials in the chamber. The melting and refining chamber is fed with glass making materials at one end thereof at which is located a doghouse and has a molten distributor disposed at the other end thereof, which comprises a series of ports through which molten glass may be removed from the melting and refining chamber.
The burners may be mounted in a number of possible configurations, for example a through-port configuration, a side-port configuration or an under-port configuration. Fuel, e.g. natural gas, is fed from the burner into the incoming stream of pre-heated air called “combustion air” also, coming from each regenerator during the firing cycle or reversal sequence, and the resultant flame and products of combustion produced in that flame extend across the surface of the melting glass, and transfer heat to that glass in the melting and refining chamber.
In operation, the regenerators are cycled alternately between combustion air and exhaust heat cycles. Every 20 minutes, or 30 minutes, depending on the specific furnaces, the path of the flame is reversed. The objective of each regenerator is to store the exhausted heat, which allows a greater efficiency and a higher flame temperature that could not be achieved with normal ambient air.
For operating the glass melting furnace, the fuel is fed to the burners and, the combustion air supplied is controlled by measuring the airflow generated at the exit of the combustion fan and at the top of the structure, the, quantity of oxygen and combustible material present to ensure that within the melting chamber or at points along the melting chamber, the combustion air fed is less than that required for complete combustion of the fuel being supplied.
In the past, the fuel used to melt glass was fuel oil, coming from distillation of petroleum. For many years this kind of fuel was used, but the tighten of environmental regulations have been pushing for reduction of fuel oil, since this kind of oil has impurities coming from the petroleum crude oil, such as, sulphur, vanadium, nickel, and some other heavy metals. This kind of fuel oil produce pollutants such as SOx, NOx and particulates. Recently the glass industry has been using natural gas as a cleaner fuel. All the heavy metals and sulphur coming in the liquid stream of petroleum residuals from distillation are not contained in natural gas. However, the high temperature produced in the flame of natural gas has been very effective for producing more NOx than other pollutants. In this sense, a lot of effort has been done in order to develop low NOx burners for firing natural gas. Additionally, different technologies have been developed to prevent the NOx formation. An example of this is the Oxy-fuel Technology, which utilizes oxygen instead of air for the combustion process. This technology has the inconvenient of requiring a unit melter furnace with a special preparation of the refractories since air infiltration need to be prevented. The use of oxygen also produce a higher temperature flame, but in the absence of nitrogen the NOx production is drastically reduced.
Another inconvenient for the oxy-fuel process is the cost of the oxygen itself. In order to make it cheaper it needs to place an oxygen plant besides the furnace in order to feed the required oxygen by the melting process.
However, the continuing upward spiral of energy costs (primarily natural gas) have forced the major float glass manufacturers to add “surcharges” to truckloads of flat glass. Natural gas prices have increased over 120% this year (in Mexico only or elsewhere), far above previous estimates.
The general consensus among Glass Industry insiders is that Distributors will be forced to take a close look at these new ‘surcharges’, and most likely be forced to pass them along.
Taking into account the previous art, the present invention is related to apply different technologies to reduce the melting cost, using a solid fuel coming from the petroleum residuals of distillation towers, such as petroleum coke, in order to be used for glass production in an environmentally clean way
The main difference of this type of fuel regarding fuel oil and natural gas is the physical state of the matter, since fuel oil is a liquid phase, natural gas is a gas phase while petroleum coke for instance is a solid. Fuel oil and petroleum coke have the same kinds of impurities, since both of them are coming from residuals of distillation tower of crude oil. The significant difference is the amount of impurities contained in each of these. Petroleum coke is produced in three types of different processes called delayed, fluid and flexi. The residuals from the distillation process are placed in drums and then heated up to from 900° to 1000° Fahrenheit degrees for up to 36 hours in order to take out most of the remaining volatiles from the residuals. The volatiles are extracted from the top of the coking drums and the remaining material in the drums is a hard rock make if around 90 percent of carbon and the rest of all the impurities from the crude oil used. The rock is extracted from the drums using hydraulic drills and water pumps.
A typical composition of petroleum coke is given as follows carbon about 90%; hydrogen about 3%; nitrogen from about 2% to 4%; oxygen about 2%; sulphur from about 0.05% to 6%; and others about 1%.
Use of Petroleum Coke
Petroleum solid fuels have already been used in cement and steam power generation industries. According to the Pace Consultants Inc. the use of petroleum coke in the year 1999 for cement and power generation were between the 40% and 14% respectively.
In both industries, the burning of petroleum coke is used as a direct fire system, in which the atmosphere produced by the combustion of the fuel is in direct contact with the product. In the case of cement production, a rotary kiln is needed in order to provide a thermal profiled require by the product. In this rotary kiln, a shell of molten cement is always formed avoiding the direct contact of the combustion gases and flames with the refractories of the kiln, avoiding attack thereof. In this case, the calcined product (cement) absorbs the combustion gases, avoid
Abelman ,Frayne & Schwab
Rinehart Kenneth
Vitro Global, S.A.
LandOfFree
Control system for controlling the feeding and burning of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control system for controlling the feeding and burning of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control system for controlling the feeding and burning of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3348283