JPS61184301A - Method and device for generating and recovering treatment heat - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for generating and recovering process heat by means of a heat exchanger.

[Background of the invention]

A series of process-technical tasks, namely coal gasification with air or oxygen with further addition of water vapor, gas conversion, e.g. by decomposing methane into a mixture of carbon oxides and hydrogen, and water conversion by thermochemical methods or high-temperature electrolytes. For separation, it is necessary to preheat additive materials such as air, oxygen or other gases, and water vapor to high temperatures.

For example, gasification of coal by oxidation is an endothermic reaction in stoichiometric combustion. This oxidative gasification is carried out using air or oxygen while adding water vapor. The high temperatures required for this gasification can be obtained by preheating only the partial combustion of the coal, or the partial combustion of the coal and the air or oxygen necessary for gasification and the added steam. High preheating temperatures for air or oxygen and water vapor favor the reaction dynamics.

A high preheating base layer of air, oxygen, other gases and water vapor can be produced by burning a part of the gas generated during coal gasification to heat the air preheater, oxygen preheater or gas preheater and steam superheater. can get. Since the gas produced is naturally lost to other processes, the capacity of the gasification plant must be determined not only for the amount of produced gas, but also for the production of the combustion gases required for preheating.

Conduits for preheated air or preheated oxygen and superheated steam are required between the gasification plant and the preheating plant. Pressure losses, heat losses and thermal expansion occur in these conduits, which are dependent on flow rate and pressure and lead to high material costs.

Additionally, the problem of space requirements for the conduits arises.

Analogous to the case of gas conversion of methane to carbon monoxide and hydrogen, for example, in the case of water separation the required reaction energy has to come from outside. What all three cases have in common is that supplying heat at a high temperature level either alleviates the problem or is only possible altogether.

(Objective of the Invention) The object of the present invention is to be able to transport heat at a high temperature level with little pressure loss and heat loss without requiring special equipment costs, and to achieve the highest possible processing heat generation and efficiency. The purpose of the present invention is to provide a recovery method and device.

SUMMARY OF THE INVENTION This object is achieved in the above-mentioned method by using a heat carrier that is fluid at low pressures and up to high temperatures, in particular sodium, which has a high heat capacity and high thermal conductivity. Heat is taken from a heat source at a high temperature in a closed circuit, and a high amount of heat is transported at a low pressure in a conduit with a small cross-section.
The same amount of heat is imparted to the materials used in the heat exchanger. Sodium has fluidity at about 100°C and boils only at about 890°C under normal pressure, so heat can be circulated within this temperature range without any change except for frictional loss. Furthermore, since the saturation temperature of sodium increases rapidly with increasing pressure, heat at higher temperatures is also transferred fluidly at relatively low pressures (eg 1000° C. at about 2.1 bar). The use of sodium in small cross-section conduits and low pressures solves the problems of thermal expansion, insulation and materials that arise over transport distances when carrying out the above method on an industrial scale.

In particular, air preheaters, oxygen preheaters or other gas preheaters and steam superheaters are heated by heat sources such as the flue gas stream of a furnace installation or the helium gas stream of a high temperature reactor. If the flue gas stream of the furnace plant is chosen as the heat source, the following advantages can be obtained: the coal gasification plant, the gas conversion plant and the water separation plant can be fed from the above smoke gas stream by means of sodium circulation. The advantage is that any fuel can be used, even if it is of low quality. Nuclear heat is incorporated in this method if the heat is extracted from the helium gas stream in the high temperature reactor.

If gasification is carried out with air, the produced gas reaches a higher heating value due to the high preheating temperature of the air and appropriate superheating of the water vapor.

That is, the amount of heat that preheats the air and superheats the steam is not released by the stoichiometric combustion that takes place in the gasification plant, so that the nitrogen fraction belonging to this part of the combustion air is not released during the gasification process. Not introduced. The transfer of heat from the smoke gases or helium to the gases and water vapor of the gas generation and gas conversion installations does not take place directly. That is, large volumes of flow are carried out in hot and pressurized large channel systems, the problems of thermal expansion, insulation and strength remain unsolved, and sufficient space may not be available for the equipment. .

In the case of coal gasification, gas conversion and water separation, high temperatures occur in the product gases and, moreover, the appreciable heat contained in them is Production gas connected to water separation equipment - sodium -
The heated sodium used in heat converters is used in process air preheaters, process steam generators, process steam superheaters as well as other gas preheaters.

Furthermore, when the processes are interconnected, for example coal gasification using oxygen and steam and water separation, the process heat can also be converted between these processes via the sodium cycle. Conceivable.

In the apparatus for carrying out the above method, a smoke gas-sodium heat exchanger is provided in the firebox of the steam generator or in the helium gas stream of the high temperature reactor, a process air preheater and (or) Sodium heated in process steam superheaters and/or other gas heaters are used.

In the steam generator firebox air or oxygen is preheated and a sufficient amount of heat is generated at a high temperature level to superheat the process steam. That is, the temperature here is 1000°C or higher. The smoke gas-sodium heat exchanger is installed in the firebox of the steam generator at a location suitable for a heat exchanger. on the other hand,
Since the highly loaded parts of the steam generator firebox are conventionally cooled by water, the wall temperature is substantially lower.

A further advantage is that there is no need to make equally special demands on the quality of the fuel used in the steam generator furnace.
Via the sodium cycle, heat generated from fuels that are not at all or poorly suited for coal gasification can also be used for coal gasification.

Moreover, the high heat capacity of sodium and the low flow resistance of sodium in the fluidized state allow heat to be transferred at high temperature levels over large distances, such as the distance between the generator and the coal gasification equipment. Sodium is particularly suitable for this purpose. Such heat transfer with large gas flows is not possible due to difficulties caused by thermal expansion and insulation, pressure losses in the gas flow and high material costs for the grooves or conduits.

In contrast, sodium has a high thermal conductivity, which allows the heat transfer circuit to operate at a lower pressure, resulting in a heat exchanger with less pressure loss in the stream of air, steam, or gas being heated. It is possible to configure

Since high temperatures occur during the gasification of coal in the gas conversion plant and/or water separation plant, the appreciable heat contained in the product gas is, according to the invention, removed from the coal gasification plant and/or the water separation plant. (or) a production gas-sodium heat exchanger connected to a gas conversion facility and/or a water separation facility, and a process steam generator in which heated sodium is used;
or) used by process air preheaters.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the schematic block diagrams of the accompanying drawings.

This example is a coal gasification facility combined with a steam power generator. Pulverized coal is produced in a crushing facility 1 and is led into a gasification reactor 2. Gasification reactor 2
The production gas is led off from the production gas line 3 via the production gas line 3. The air required for gasification is forced into the process air conduit 5 by means of the compressor 4 and flows into the gasification reactor 2 . A process air preheater 6 is provided in the process conduit 5 and is supplied with heat from a sodium circulation circuit 7 in which a sodium circulation pump 8 is provided. The water vapor required for gasification is produced in a process steam generator 22, which is supplied with feed water via a pump 23 and a conduit 24. When steam is supplied to the process steam generator 22, the generator acts as a process steam heater.

For sodium, the heat from the sodium heater 9 is transferred to the steam generator 11.
taken from the smoke gas of the furnace 10.

The steam produced in the evaporator 13 of the steam generator is first conducted through a superheater 14 and then into a steam turbine 16 having a high pressure section and a low pressure section. Steam turbine 16 drives generator 12 . An intermediate superheater 15 is provided between a high pressure section and a low pressure section of the steam turbine 16. The steam turbine 16 has a branch that serves to preheat the feed water in the feed water heater 19 . Steam exiting the steam turbine 16 is condensed in a condenser 17 , forced into a feed water heater 19 by a condensate pump 18 , and introduced into the steam generator 11 by a condensate pump 20 . It will be destroyed.

The sodium circuit 7 takes the heat contained in the production gas into a heat exchanger 21 and sends the same heat together with the heat coming out of the sodium heater 9 to the air preheater 6 and the process steam generator 22. Give again. Steam generator 1 in block diagram
The sodium heater 9 in the air preheater 6 and the heat exchanger 21 in the production gas stream and into which sodium enters the air preheater 6
and the processing steam generator 22 are connected in parallel.

Depending on the amount of heat generated and the temperature, a series connection is implemented in these heat exchangers.

Heat is generated by a nuclear reaction and transferred to the sodium circulation circuit 7 via the helium circulation circuit. A high temperature reactor is provided in place of the heat source provided by burning coal in the furnace 12.

In the case of gasifying with oxygen instead of air, the coal gasification equipment 2 is provided with a preliminary 7 via a compressor 4 and a conduit 5.
Oxygen heated in the heater 6 is supplied.

Instead of the coal gasification facility 2, a gas conversion facility or a water separation facility is also provided. In this way, the supply of coal from the crushing equipment 1 is omitted. Instead, methane is produced in gas separation facilities, and steam or other chemical components are produced in water separation facilities.
It is preheated to a high temperature by a sodium circulation circuit.

〔Effect of the invention〕

The method and device according to the invention allow heat at very high temperature levels resulting from coal burning in a conventional furnace or nuclear fission carried out in a high temperature reactor to be transmitted over a distance determined by the size of the device. It can be carried. This includes coal gasification, gas conversion and water separation. With the sodium circulation circuit according to the invention, these methods can be carried out on a technically large scale.

[Brief explanation of the drawing]

The 1% figure is a schematic block diagram of an embodiment of the present invention. 2...Coal gasification reactor 6...Processed air preheater 9...Fume gas-sodium-heat exchanger (sodium heater) 21...Produced gas-sodium-heat exchanger 22...
processing steam generator

Claims (1)

[Claims] 1. A method for generating and recovering process heat using a heat exchanger, characterized in that a heat carrier having fluidity up to a high temperature at a low pressure is used in the heat exchanger. how to. 2. The method according to claim 1, wherein sodium is used as a heat carrier. 3. A method according to claim 1 or 2, wherein the process heat is extracted from the flue gas stream of the furnace installation. 4. A method according to claim 1 or 2, wherein the process heat is extracted from the helium gas stream of the high temperature reactor. 5. A method according to claim 1 or 2, wherein the process heat is recovered from the production gas stream of a coal gasification facility. 6. A method according to claim 1 or 2, wherein the heat of production is recovered from the production gas stream of the gas conversion facility. 7. A method according to claim 1 or 2, wherein the process heat is recovered from the product gas stream of the water separation facility. 8. Smoke gas-sodium heat exchangers in the firebox of the steam generator or in the helium gas stream of the high-temperature reactor, and process air preheaters and/or process steam superheaters involving heated sodium. , and/or other gas heaters. 9 Coal gasification equipment and/or gas conversion equipment, and (
or) production gas - sodium - connected to water separation equipment.
Process heat generation and recovery device, characterized in that it consists of a process steam generator involving a heat exchanger and heated sodium, and/or a process air preheater, and/or other gas heaters.