JPH0146556B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for cooling a produced gas in a process for producing a gas containing hydrogen or methane, etc. by a process of steam reforming or partial oxidation of a substance containing carbon. (Prior art and its problems) In the process of producing gas containing hydrogen or methane by steam reforming or partial oxidation of carbon-containing substances, high-temperature produced gas is cooled to below atmospheric temperature. Conventionally, compression refrigerators have been used to separate and remove water through cooling and dehydration, which consumes a considerable amount of electricity to drive the compressor. . The present invention aims to reduce the power consumption required for cooling and dehydrating manufactured gas by rationally recovering waste heat from the gas manufacturing process and using that energy for cooling. . (Structure of the Invention) In order to achieve the above-mentioned object, the present invention provides a heat exchange section upstream of the cooling section of the production gas cooling and dehydration system in the gas production process, An absorption refrigeration system using the high temperature heat medium as a heat source is configured in the circulation system of the high temperature heat medium passing through the heat exchange section, and a low temperature heat medium passing through the absorption refrigeration system is sent to the cooling section of the cooling and dehydration system. The gist of this is to cool the production gas by guiding it. The following is a detailed description based on examples. In FIG. 1, reference numeral 1 indicates a cooling and dehydration system for produced gas in the gas production process, and 2 indicates a cooling and dehydration section. To specifically explain the illustrated example of the cooling and dehydration section 2, reference numeral 3 denotes a first cooling section that cools the produced gas to near room temperature using room temperature cooling water;
4 is a second cooling unit that further cools the production gas; 5;
6 is a dehydration section, 7 is a gas-gas heat exchanger,
In addition, the cooling unit 2 designated by reference numeral 3 may have any suitable configuration, such as being provided with a cooler such as an air fin. Therefore, a heat exchange section 8 is provided in front of the cooling and dehydration section 2 of the system 1, and an absorption system using the high temperature heat medium as a heat source is provided in a circulation system 9 for a high temperature heat medium passing through the heat exchange section 8. A refrigeration device 10 is configured, and the low-temperature heat medium passing through the absorption refrigeration device 10 is guided to the cooling and dehydration section 2 and supplied to the second cooling section 4. In addition to using water as the high-temperature/low-temperature heat medium, other suitable heat medium may also be used. Further, the absorption refrigerating apparatus 10 may be of either a single effect type or a double effect type as described later. Further, although not shown, the circulation system 9 may be constructed as an independent closed path, or as shown, the circulation system 9 may be configured as an independent closed path, or as shown, the water supply section 11 passes through the heat exchange section 8 to the boiler (not shown).
The boiler feed water preheating system 12 leading to the boiler feed water preheating system 12 may be configured as a branch route of another heat exchange system, such as branching to an appropriate location of the boiler feed water preheating system 12. (Operation) Next, the operation of the present invention will be explained based on the configuration shown in FIG. 1. It should be noted that the state quantities shown in FIG. 1 merely represent data of an example described later. First, the manufactured gas produced in the manufacturing process reaches the heat exchange section 8 at a high temperature, where the temperature decreases by heat exchange with water, which is a high temperature heat medium, and reaches the first cooling section 3. On the other hand, the heat exchange section 8 includes a water supply section 1.
The water supply from 1 and the circulating water that has passed through the absorption refrigeration system 10 are combined and introduced, and after the water is heated by exchanging heat with the production gas, part of it is guided toward the boiler, and the rest is circulated. You will be guided to line 9. Circulation system 9
The preheated feed water introduced into the absorption refrigerating apparatus 10 provides thermal energy to the regenerator of the absorption refrigerating apparatus 10 and becomes a heat source for the absorption refrigerating machine. The low-temperature heat medium supplied to the second cooling section 4 is cooled by this absorption refrigeration effect. As mentioned above, the gas that has reached the first cooling section 3 exchanges heat with room-temperature cooling water such as ordinary water or seawater to lower its temperature, and then enters the gas-gas indirect heat exchanger 7. The temperature of the gas is lowered by exchanging heat with the gas that has previously passed through the second cooling section 4 and has reached a low temperature.
It is dehydrated in the dewatering section 5 and reaches the second cooling section 4. In the second cooling section 4, the gas exchanges heat with the low-temperature heat medium cooled by the absorption refrigerating device 10 to further lower its temperature, and then is further dehydrated in the dehydration section 6. In the gas-gas indirect heat exchanger 7, it exchanges heat with the gas that has passed through the cooling section 3 and is sent out at about room temperature. On the other hand, the low-temperature heat medium whose temperature has increased by exchanging heat with the gas in the second cooling section 4 returns to the absorption refrigerating device 10, where it is cooled and used again to cool the gas. As described above, the present invention recovers the heat of high-temperature manufactured gas to operate the absorption refrigerating device 10, and cools the manufactured gas using the cold heat generated in the absorption refrigerating device 10. can. As mentioned above, the present invention can be applied to either a single effect system or a double effect system as the absorption refrigerating apparatus 10, and this will be explained next. Figure 2 shows a Düring diagram for a lithium bromide-water system. From this diagram, it can be seen that in a single-effect system, COP (cooling heat/heating source heat) reaches its maximum at about 90°C and does not reach saturation. Recognize. Therefore, when a single effect system is applied as the absorption refrigerating apparatus 10, the temperature of the preheated hot water introduced into the absorption refrigerating apparatus 10 in the circulation system 9 is set to 90°C.
It is effective to set it to a certain degree. Figure 3 shows the relationship between the heating source temperature and COP in the single effect method, and from this figure, as mentioned above, COP is 90
It can be seen that although it reaches its maximum at temperatures above 75°C, it can be operated with sufficient thermal efficiency at temperatures above about 75°C. As described above, the temperature of the preheated hot water introduced into the absorption refrigerating device 10 in the circulation system 9 is set to 75
By setting the temperature to approximately 100°C to 100°C, the low-cost single-effect absorption refrigerating apparatus 10 can be operated near the upper limit of its thermal efficiency. Figure 4a,
b shows another example of the main part of the system to which the single-effect absorption refrigerating device 10 is applied;
3 is a deaerator, and in a and b, 14 is a second heat exchange section installed upstream of the flow of produced gas in the boiler feed water preheating system 12 from the heat exchange section 8. Further, in b, 13' is a deaerator, and this deaerator 13' is a natural circulation type heating deaerator or a kettle type deaerator. As shown in FIGS. 4a and 4b, the second heat exchange section 1
The preheated water that has gone through step 4 has a temperature of about 200℃, so
If this high-temperature preheated feed water is used as a heating source, the dual-effect absorption refrigerating device 10 can be operated.
FIG. 4c shows the configuration of the main parts to which this method is applied, and like in a and b, the reference numeral 13 is a deaerator. In this way, a double-effect absorption refrigeration device 1
By applying 0, the COP becomes 1 or more, so it is effective when there is not enough waste heat of the production gas. Dual effect absorption refrigeration device 10 is COP
However, the equipment cost is high, so whether to apply the single effect method or the double effect method can be decided by taking into consideration the amount of waste heat and equipment cost. (Example) A production gas having the following composition was prepared at point A in Figure 1 at a pressure of 11.8 Kg/cm ² G, a temperature of 141°C, and a flow rate of 4820 N.
The state quantities of each part when flowing through the cooling and dehydration system 1 under the conditions of m ³ /Hr are as added to Figure 1, and the composition at point B in Figure 1 is as follows. , a highly dehydrated gas was obtained. still,
The state quantity of the produced gas at point B is pressure 10.5Kg/
cm ² G, temperature 28° C., and flow rate 3450 Nm ² /Hr.

[Table] (Effects of the invention) As described above, the present invention cools high-temperature production gas.
During dehydration, the heat held by this gas, that is, the waste heat, is recovered to operate an absorption refrigeration system, and the cold heat generated in the absorption refrigeration system is used to cool the gas, so it is not possible to use conventional compression. Compared to a cooling method using a type refrigerator, this method has the effect of significantly reducing power consumption. Furthermore, since the temperature of the gas is also lowered by recovering such waste heat, the cooling load on the first cooling section 3 and other coolers such as air fins is reduced, and from this point of view as well, operating costs can be reduced. There is an effect. Furthermore, in the present invention, a single-effect method or a double-effect method can be selected as the absorption refrigerating device depending on the situation, so when the amount of waste heat is large, a low-cost single-effect absorption refrigerating device can be used. It is possible to operate near the upper limit of its efficiency, and even when the amount of waste heat is small, it has the advantage of being able to operate as a dual-effect absorption refrigerating device.

[Brief explanation of drawings]

Fig. 1 is a systematic explanatory diagram of an embodiment of a configuration to which the present invention is applied, Fig. 2 is a Duering diagram of lithium bromide-water system, and Fig. 3 is a heating source temperature of a single-effect absorption refrigerating device. COP relationship diagram, Figure 4 a, b,
c is an explanatory diagram of another embodiment of the configuration to which the present invention is applied. Code 1... Cooling, dehydration system, 2... Cooling, dehydration section,
3...First cooling section, 4...Second cooling section, 5, 6...
Dehydration section, 7... Gas-gas heat exchanger, 8... Heat exchange section, 9... Circulation system, 10... Absorption refrigeration device, 11
...Water supply section, 12...Boiler feed water preheating system, 13,
13'... deaerator, 14... second heat exchange section.

Claims (1)

[Claims] 1. Cooling of produced gas in a gas production process;
In the dehydration system, a heat exchange section is provided in front of the cooling and dehydration section of the system, and an absorption refrigeration system that uses the high temperature heat medium as a heat source is installed in the circulation system of the high temperature heat medium passing through the heat exchange section. A method for cooling manufactured gas in a gas manufacturing process, characterized in that the low-temperature heat medium passing through the absorption refrigeration system is guided to the cooling and dehydration section of the cooling and dehydration system to cool the manufactured gas. 2 Cooling of manufactured gas in the gas manufacturing process,
In the dehydration system, a heat exchange section is provided in front of the cooling section of the system, and a boiler feed water preheating system is configured from the water supply section to the boiler via the heat exchange section, and , a preheated feed water circulation system is configured, and an absorption type refrigerating device using the preheated feed water as a heat source is configured in the circulation system, and the low temperature heat medium passing through the absorption type refrigerating device is cooled and dehydrated by the cooling section of the dehydration system. 1. A method for cooling manufactured gas in a gas manufacturing process, characterized by cooling the manufactured gas by guiding the manufactured gas to the gas.