A system and method for treating coal gas water cycle concentrate in a fixed bed gasifier

Abstract

The application discloses a treatment system and method for coal gas water circulating concentrated liquid of a fixed bed gasifier. The structure of the treatment system is as follows: the gas outlet of the fixed bed gasifier is connected with the gas inlet of a coal gas water heat exchanger, the gas outlet of the coal gas water heat exchanger is connected with the gas inlet of a washing tower; the washing water circulating pipeline of the washing tower is connected with a coal gas water recovery pipeline, the circulating water outlet and inlet of the coal gas water heat exchanger are respectively connected with the top and bottom of a humidification tower, the connecting pipeline of the inlet and the humidification tower is also connected with the coal gas water recovery pipeline; the connecting pipeline of the circulating water inlet of the coal gas water heat exchanger and the humidification tower is connected with a concentrated liquid treatment device or a concentrated liquid evaporator through a concentrated liquid recovery pipeline, and the mixed gas outlet of them is connected with the fixed bed gasifier after passing through a dust remover. The application not only avoids or reduces the need for softened water, but also does not have any waste water leaving the production workshop in the process of the gasifier, truly realizes the clean and efficient conversion of coal, and meets the needs of the gas industry for clean fuel gas.

Description

Technical Field

[0001] This invention relates to a treatment system and method for coal gas-water circulating concentrate from a fixed-bed gasifier, belonging to the field of coal conversion and utilization technology. Background Technology

[0002] my country's energy resources are characterized by a scarcity of oil and gas, but an abundance of coal. This dictates that coal will remain an indispensable and fundamental energy source for the foreseeable future. The efficient conversion and utilization of coal is a crucial pathway to carbon emission reduction, and coal gasification will play an increasingly important role in the production of chemical synthesis feedstocks, liquid and gaseous fuel substitutes, and hydrogen. Currently, the industrial gasification furnaces widely used in my country still suffer from problems such as coal gas and water pollution emissions and high treatment costs for coal gas and water containing organic matter. Therefore, there is a need to provide an economical and green coal gas and water treatment process and system. Summary of the Invention

[0003] The purpose of this invention is to provide a treatment system and method for the gas-water circulating concentrate of a fixed-bed gasifier, which can internally circulate the water generated in the production process of a low-pressure gasifier using air as the gasifying agent, evaporate most of the water in the gas-water to become the reactant required for the gasification reaction, and reuse the remaining concentrate in the gasifier, so that the gasification unit does not discharge water to the outside.

[0004] The fixed-bed gasifier gas-water circulating concentrate treatment system provided by the present invention includes a gas-water heat exchanger, a scrubbing tower, a humidification tower, and a concentrate processor or concentrate evaporator;

[0005] The gas outlet of the fixed-bed gasifier is connected to the gas inlet of the gas-water heat exchanger, the gas outlet of the gas-water heat exchanger is connected to the gas inlet of the scrubbing tower, and the gas outlet of the scrubbing tower is connected to the downstream user.

[0006] The washing water circulation pipeline of the washing tower is connected to the gas-water recovery pipeline.

[0007] The circulating water outlet of the gas-water heat exchanger is connected to the top of the humidification tower, and the circulating water inlet is connected to the bottom of the humidification tower. The connecting pipe between the circulating water inlet and the humidification tower is also connected to the gas-water recovery pipe. An air / oxygen inlet is provided at the lower part of the side wall of the humidification tower, and the top is connected to the bottom of the fixed bed gasifier.

[0008] The circulating water inlet of the gas-water heat exchanger is connected to the humidification tower via a concentrate recovery pipeline, which is then connected to the concentrate processor or the concentrate evaporator. The mixed gas outlet of the concentrate processor or the concentrate evaporator is connected to the fixed-bed gasifier after passing through a dust collector.

[0009] In the above-mentioned processing system, the fixed-bed gasifier is a two-stage gas generator. The gas outlet of the upper stage gasifier is connected to the electrostatic precipitator for tar and the electrostatic precipitator for light oil, and the gas outlet of the lower stage gasifier is connected to the gas-water heat exchanger.

[0010] In the above-mentioned processing system, a bypass is connected between the gas inlet pipe and the gas outlet pipe of the gas-water heat exchanger.

[0011] In the above-mentioned processing system, the shell side of the gas-water heat exchanger is connected to the gas transmission pipeline and flows at a sufficiently high speed, while the tube side is connected to the gas-water transmission pipeline. Fins can be arranged on the outside of the tubes to increase the heat transfer area on the gas phase side.

[0012] In the above-mentioned processing system, the upper part of the concentrated liquid evaporator is provided with a combustion furnace, the top of the combustion furnace is provided with a burner, and the burner is provided with a gas inlet and an air inlet;

[0013] The fuel for the burner can be the coal gas produced by the fixed-bed gasifier, and the coal gas and combustion air are burned to produce high-temperature flue gas.

[0014] A temperature-regulating gas bypass is arranged on the side of the combustion furnace. In this way, the gas introduced through the temperature-regulating gas bypass is used to adjust the outlet temperature when different water treatment volumes are reached, and the gas flow rate is proportional to the amount of concentrated water treated.

[0015] The temperature inside the concentrate evaporator gradually decreases from top to bottom. A bypass is provided in the high-temperature zone at the top of the concentrate evaporator, and a bypass orifice plate is provided on the bypass. The bypass is connected to the mixed gas pipeline at the outlet of the concentrate evaporator. The orifice plate leads out a small portion of hot gas and mixes it with the low-temperature mixed gas to ensure that the final outlet mixed gas is in a superheated state.

[0016] The outlet of the concentrate recovery pipeline extends into the concentrate evaporator and is fitted with several nozzles;

[0017] Atomizers are installed near the outlet end of both the concentrated liquid recovery pipeline and the air delivery pipeline connected to it.

[0018] By injecting concentrated water into the high-temperature flue gas leaving the burner in a certain proportion, the flue gas is cooled down, the concentrated water evaporates, and the atomized air is atomized to improve the atomization effect.

[0019] The bottom of the concentrate evaporator is connected to a condensation tank, and the outlet of the condensation tank is connected to the concentrate recovery pipeline, thereby returning the liquid to the concentrate recovery pipeline.

[0020] In the above-mentioned processing system, the burner can also be installed on the lower side of the concentrated liquid evaporator. The burner is provided with a gas inlet and an air inlet. The high-temperature flue gas from the burner outlet enters the lower part of the concentrated liquid evaporator. In this way, the hot flue gas rises and the water flows downward from the top, making countercurrent contact. This facilitates the contact of the residues after evaporation in the water with the high-temperature gas at the bottom, which is more conducive to the evaporation of all organic matter in the water.

[0021] In the above-described processing system, the bottom of the concentrate processor is connected to the concentrate recovery pipeline;

[0022] An air distributor is installed near the bottom of the concentrate processor; the concentrate processor is heated by steam.

[0023] The top of the concentrate processor is connected to an electric superheater, and the top of the electric superheater is connected to the dust collector.

[0024] In the above-described processing system, the top of the concentrate processor is connected to a mixing steam superheater;

[0025] Both the liquid shrinking processor and the mixed steam superheater are connected to the thermal oil heater via a thermal oil circulation pipeline. The thermal oil heater is located between the gas outlet of the fixed bed gasifier and the gas inlet of the scrubbing tower.

[0026] In the above-mentioned processing system, the bottom of the concentrate processor is connected to the coal pulverizing unit for coal pulverizing.

[0027] The high-viscosity residual liquid discharged from the bottom of the concentrate processor is mixed with pulverized coal in a certain proportion and sent to a mixer for mixing. The mixed, moist pulverized coal is then sent to an extrusion molding machine to form briquettes. After being stockpiled and stabilized, the briquettes are added to the fixed-bed gasifier along with lump coal as part of the raw materials.

[0028] Based on the aforementioned fixed-bed gasifier gas-water circulating concentrate treatment system, the present invention also provides a method for treating the fixed-bed gasifier gas-water circulating concentrate, comprising the following steps:

[0029] The gas-water produced by the fixed-bed gasifier passes through the gas-water heat exchanger of the treatment system, is cooled, and then enters the scrubbing tower. After scrubbing, it enters the downstream unit.

[0030] The gas-water produced by the scrubbing tower is passed into the gas-water heat exchanger to exchange heat with the gas; the heated gas-water enters the humidification tower from the top and comes into countercurrent contact with the air / oxygen entering from the bottom. Part of the gas-water changes from liquid to steam and mixes with the air / oxygen. The resulting humid air containing water vapor enters the fixed-bed gasifier from the bottom as a gasifying agent.

[0031] The concentrated liquid produced during the circulation and evaporation of the coal gas and water is processed by the concentrated liquid processor or the concentrated liquid evaporator, and the mixed gas then enters the fixed bed gasifier after passing through the dust collector.

[0032] Specifically, when the fixed-bed gasifier is a two-stage furnace, the outlet gas temperature of the upper stage furnace is 100~150℃, and the outlet gas temperature of the lower stage furnace is 400~550℃.

[0033] When the fixed-bed gasifier is a single-stage gasifier, the outlet gas temperature is 350~600°C.

[0034] Specifically, the temperature of the mixed gas after being heated by the concentrate processor or the concentrate evaporator is higher than 200°C.

[0035] The present invention has the following beneficial technical effects:

[0036] In existing atmospheric pressure fixed-bed gasifiers, softened water must first be converted into steam before being mixed with air and fed into the gasifier. The moisture in the gasified gas at the outlet condenses, especially after gas washing, producing a significant amount of phenol-containing wastewater. This phenol-containing wastewater contains extremely complex impurities, making it very difficult to treat and costly to treat further. Ultimately, some organic matter inevitably enters the environment with the discharged water. This invention internally recirculates the condensate and washing liquid produced during the coal gasification process. The sensible heat of the coal gas itself heats the gas-water mixture, which saturates the air with steam, controlling the air humidity precisely to meet the gasifier's temperature control requirements. The circulating concentrate is also completely gasified into steam and enters the gasifier. All organic vapors are converted into usable combustible gases in the gasifier. This not only avoids or reduces the need for softened water but also ensures that no wastewater leaves the production workshop during the gasification process, achieving two goals at once. This truly realizes the clean and efficient conversion of coal while simultaneously meeting the gas industry's need for clean fuel gas. Attached Figure Description

[0037] Figure 1 This is one of the structural schematic diagrams of the gas-water circulating concentrate treatment system of the fixed-bed gasifier of the present invention.

[0038] Figure 2 This is a schematic diagram of the structure of the gas-water circulating concentrate treatment system of the fixed-bed gasifier of the present invention, in which the burner is located at the lower part of the concentrate evaporator.

[0039] Figure 3 This is the second schematic diagram of the treatment system for the gas-water circulating concentrate of the fixed-bed gasifier of the present invention.

[0040] Figure 4 This is the third schematic diagram of the structure of the treatment system for the gas-water circulating concentrate of the fixed-bed gasifier provided by the present invention.

[0041] The markings in the diagram are as follows:

[0042] 1 Fixed-bed gasifier, 2 Oil separator, 3 Scrubber, 4 Gas-water heat exchanger, 5 Gas-water recovery pipeline, 6 Humidification tower, 7 Concentrate recovery pipeline, 8 Concentrate evaporator, 9 Nozzle, 10 Atomizer, 11 Condensation tank, 12 Cyclone dust collector, 13 Bypass, 14, 19 Concentrate processor, 15 Air distributor, 16 Electric superheater, 17 Mixer, 18 Forming machine, 20 Mixed steam superheater, 21 Thermal oil heater. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

[0044] like Figure 1 The diagram shown is a structural schematic of a treatment system for coal gas-water circulating concentrate from a fixed-bed gasifier provided by the present invention. The specific structure is as follows:

[0045] The fixed-bed gasifier 1 is a two-stage furnace. The gas outlet of the upper stage furnace is connected to the electrostatic precipitator for tar and the electrostatic precipitator for light oil (oil remover 2). The outlet of oil remover 2 is connected to the gas inlet of the scrubbing tower 3. The gas outlet of the lower stage furnace is connected to the gas-water heat exchanger 4 (gas flows through the shell side). The gas outlet of the gas-water heat exchanger 4 is connected to the gas inlet of the scrubbing tower 3. The gas outlet of the scrubbing tower 3 is connected to the downstream user. The washing water circulation pipeline of the scrubbing tower 3 is connected to the gas-water recovery pipeline 5. The circulation water outlet of the gas-water heat exchanger 4 is connected to the top of the humidification tower 6, and the circulation water inlet is connected to the bottom of the humidification tower 6. The connection pipeline between the circulation water inlet and the humidification tower 6 is also connected to the gas-water recovery pipeline 5, thereby sending part of the gas-water (containing phenol wastewater) generated by the scrubbing tower 3 to the gas-water heat exchanger 4 for cooling the gas. The lower part of the side wall of the humidification tower 6 is equipped with an air / oxygen inlet, and its top is connected to the bottom of the fixed-bed gasifier 1. The heated coal gas water comes into countercurrent contact with the air entering from the bottom, and part of the coal gas water changes from liquid to steam and mixes with the air. When it leaves the top of the humidification tower 6, the water vapor content of the air reaches saturation or near saturation. The humid air containing water vapor goes to the bottom of the fixed-bed gasifier 1 and is used as a gasifying agent in the gasifier. The condensate generated during the indirect cooling process of the coal gas before the scrubbing tower 3 also enters the coal gas water recovery pipeline 5 together with the scrubbing wastewater.

[0046] The circulating water inlet of the gas-water heat exchanger 4 is connected to the humidification tower 6 via the concentrate recovery pipeline 7, which is then connected to the upper part of the concentrate evaporator 8. The upper part of the concentrate evaporator 8 is equipped with a combustion chamber, and a burner is installed at the top of the combustion chamber. The burner has a gas inlet and an air inlet. The fuel for the burner can be gas produced by a fixed-bed gasifier. The gas and combustion air burn together to produce high-temperature flue gas. Gas can also be introduced into the concentrate evaporator 8 via a temperature-regulating gas bypass for adjusting the outlet temperature at different water treatment volumes. The gas flow rate is proportional to the volume of concentrate being treated.

[0047] The outlet of the concentrate recovery pipeline 7 extends into the interior of the concentrate evaporator 8 and is equipped with several nozzles 9. Atomizers 10 are installed on the concentrate recovery pipeline 7 and the air delivery pipeline connected to it near the outlet. Concentrated water is injected proportionally into the high-temperature flue gas leaving the burner, cooling the flue gas, evaporating the concentrated water, and atomizing the air to improve the atomization effect. A condensate guide tank 11 is connected to the bottom of the concentrate evaporator 8, and the outlet of the condensate guide tank 11 is connected to the concentrate recovery pipeline 8, thus returning the liquid to the concentrate recovery pipeline 7. The concentrate evaporator 8 is connected to a cyclone dust collector 12. After the flue gas-steam mixture leaving the concentrate evaporator 8 passes through the cyclone dust collector 12 to separate the dust, the gas enters the fixed-bed gasifier 1. A small portion of the hot gas can be drawn out through a bypass orifice plate and remixed with the low-temperature flue gas-steam mixture to ensure that the final outlet mixture is in a superheated state.

[0048] A bypass 13 is connected between the gas inlet pipe and the gas outlet pipe of the gas-water heat exchanger 4. Its function is to regulate the gas flow to the gas-water heat exchanger 4, thereby achieving the purpose of regulating the humidity content in the air.

[0049] In addition, a bypass is provided in the upper high-temperature zone of the concentrate evaporator 8, and a bypass orifice plate is provided on the bypass. The bypass is connected to the mixed gas pipeline of the concentrate evaporator 8. Since the temperature in the concentrate evaporator 8 gradually decreases from top to bottom, the orifice plate draws out a small portion of hot gas and mixes it with the low-temperature mixed gas to ensure that the final outlet mixed gas is in a superheated state.

[0050] use Figure 1 When the system shown processes the gas-water circulating concentrate from a fixed-bed gasifier, the following steps can be followed:

[0051] In the two-stage fixed-bed gasifier 1, the gas exiting the gasifier from the upper stage has a relatively low temperature, typically 100-150°C. The gas passes through an electrostatic precipitator for tar and an electrostatic precipitator for light oil, separating the tar from the gas. The gas exiting the lower stage does not undergo the drying and carbonization process to cool down, resulting in a higher temperature, typically 400-550°C. In this invention, the sensible heat of the lower stage gas is used to heat the gas-water mixture. In the gas-water heat exchanger 4, the hot gas flows within the heat exchange tubes and is heated by the hot gas outside the tubes. Fins can be installed on the outside of the heat exchange tubes to improve the heat transfer capacity on the gas phase side. After being cooled by the gas-water mixture, the lower stage gas mixes with the lower stage low-temperature gas. In the scrubbing tower 3, large organic molecules, including phenol, contained in the gas are transferred to the water. A portion of the circulating scrubbing water (containing phenol wastewater) is discharged from the scrubbing water circuit and sent to the gas-water recovery pipeline 5. In the gas-water recovery pipeline 5, the gas-water is first sent to the gas heat exchanger 4 to heat it, and then the heated water is sent to the upper part of the humidification tower 6. In the humidification tower 6, air pressurized by a blower enters from the bottom of the tower and flows upward, coming into countercurrent contact with the spray water falling from the top. Some of the gas-water evaporates to produce water vapor, which mixes with the air. When the air leaves the top of the humidification tower, the temperature is between 50 and 75°C, and the water vapor in the air is saturated or nearly saturated. The humid air enters the bottom of the fixed-bed gasifier 1 and reacts with the coal as a gasification reactant to produce coal gas. The unevaporated water phase is collected at the bottom of the humidification tower 6, pressurized by a pump, and recirculated back to the gas-water heat exchanger 4 for reheating.

[0052] As the gas-water mixture circulates in the recovery loop, the organic matter in the water is concentrated, and the concentration of fine dust increases. A certain flow rate of concentrated liquid is discharged from the concentrated liquid recovery pipeline 7 according to a specific concentration ratio (i.e., the ratio of phenol-containing wastewater to the discharged concentrated liquid), and then sent to the concentrated liquid evaporator 8 for further treatment. If the phenol-containing wastewater from the scrubbing tower 3 and other sources is 10 tons / hour, assuming a concentration ratio of 10, the amount of concentrated liquid discharged from the circulation recovery loop is 1 ton / hour. Assuming the original phenol concentration in the phenol-containing water is 2000 ppm, due to the lower evaporation rate at the lower circulation temperature, after a 10-fold concentration, the phenol concentration in the concentrated liquid will be close to 20000 ppm, or 2%.

[0053] The burner at the top of the concentrate evaporator 8 uses a small portion of the gas produced by the gasifier, which is pressurized and burned with combustion air to generate high-temperature flue gas. At the top of the evaporator, the concentrate is atomized by atomizing air and sprayed into the high-temperature flue gas stream. The atomizing nozzles consist of one or more layers. The atomized concentrate is evaporated, and the flue gas temperature decreases. Packing material is installed inside the bed of the concentrate evaporator 8 to improve the gas-liquid contact effect. The ratio of gas to concentrate is controlled, and the temperature of the flue gas gradually leaving the evaporator is maintained above 200°C, and more often above 250°C. At this temperature, water and almost all organic matter in the concentrate are converted into gas, some solid salts such as ammonium salts are decomposed, and other solids become dust in the gas.

[0054] Before leaving the evaporator, especially during the start-up phase, any unevaporated liquid falls to the bottom of the evaporator. The collected liquid is then guided back to the concentrate recovery line 7 by the alternating operation of the upper and lower valves of the condensate collection tank 11.

[0055] After the flue gas and steam mixture leaving the evaporator passes through the cyclone dust collector 12 to separate the dust, the gas enters the fixed bed gasifier 1.

[0056] In this way, all the coal gas and water produced during the coal gasification process are absorbed in the coal gasification workshop.

[0057] Alternatively, the burner can be placed on the lower side of the concentrated water evaporator, such as... Figure 2 As shown, the hot flue gas rises upwards and the water flows downwards from the top, creating a counter-current contact. This allows the residues in the water after evaporation to come into contact with the high-temperature gas at the bottom, which is more conducive to evaporating all organic matter in the water.

[0058] like Figure 3 The diagram shown is a structural schematic of another fixed-bed gasifier gas-water circulating concentrate treatment system provided by the present invention, whose structure is similar to... Figure 1 The systems shown are basically the same in structure, except that the fixed-bed gasifier is a single-stage gasifier, and the gas outlet is directly connected to the gas heat exchanger 4. A concentrate processor 14 is connected to the concentrate recovery pipeline. An air distributor 15 is located near the bottom of the concentrate processor 14, which is heated by steam. The top of the concentrate processor 14 is connected to an electric superheater 16, and the top of the electric superheater 16 is connected to a cyclone dust collector 12.

[0059] use Figure 3 When the system shown processes the gas-water circulating concentrate from a fixed-bed gasifier, the following steps can be followed:

[0060] In a single-stage gasifier, the gas exiting the top of the gasifier is in the range of 350~600°C. This gas first enters the gas-water heat exchanger 4 for cooling, and then is sent to the scrubbing tower 3 for washing. The phenol-containing wastewater obtained from the washing cycle is sent to the gas-water recovery pipeline 5. The evaporated water vapor saturates the air from the blower, and the humid air is used for the gasifier reaction. The process is similar to... Figure 1 The process is the same for the system shown.

[0061] The concentrate processor is divided into two main parts: the lower part is for liquid heating, and the upper part is for gas heating, using steam heating and electric heating respectively. The concentrate processor 14 operates under pressurized conditions as much as possible. Pressurization allows water evaporation to occur at higher temperatures and also maximizes the volatilization of organic matter in the water. The concentrate from the concentrate recovery pipeline 7 is sent to the lower part of the concentrate processor 14, where it is heated and evaporated. Some organic matter is also evaporated along with the vapor. The evaporated gas rises with the air to the upper part of the processor, where it is heated by the electric superheater 16 to superheat the mixed steam and prevent condensation. After dust removal, the mixed gas pipeline leaving the processor is well insulated to maintain a temperature above the dew point of water and organic matter. This fluid has a smaller flow rate than the humid air exiting from the top of the humidification tower 6. A separate pipeline directly sends the concentrate processor outlet gas to the high-temperature point inside the gasifier, allowing the organic vapor to contact the oxide layer inside the gasifier and undergo a chemical reaction to convert it into carbon dioxide and water vapor.

[0062] The organic molecules in the liquid remaining at the bottom of the concentrate processor 14 are larger, and the viscosity of the residual liquid is further increased. A portion of the higher viscosity liquid is periodically removed from the bottom of the concentrate processor. The residual liquid at the bottom of the concentrate processor is sent to the pulverized coal forming unit (including the mixer 17 and the forming machine 18 connected in sequence) to obtain coal briquettes, which are used as part of the raw material for the gasifier.

[0063] In this way, all the coal gas and water produced during the coal gasification process are absorbed in the coal gasification workshop.

[0064] like Figure 4 The diagram shown is a structural schematic of another fixed-bed gasifier gas-water circulating concentrate treatment system provided by the present invention, whose structure is similar to... Figure 3 The structures of the systems shown are basically the same, except that the top of the concentrate processor 19 is connected to the mixing steam superheater 20, and both the concentrate processor 19 and the mixing steam superheater 20 are connected to the heat transfer oil heater 21 through the heat transfer oil circulation pipeline. The heat transfer oil heater 21 is located on the bypass 13.

[0065] use Figure 4 When the system shown processes the gas-water circulating concentrate from a fixed-bed gasifier, the following steps can be followed:

[0066] In a single-stage gasifier, the gas exiting the top of the gasifier is in the range of 350~600°C. This gas first enters the gas-water heater for cooling, and then is sent to the washing tower 3 for washing. The phenol-containing wastewater obtained from the washing cycle is sent to the gas-water recovery pipeline 65. The evaporated water vapor saturates the air from the blower, and the humid air is used for the gasifier reaction. The process is similar to... Figure 1 The process is the same for the system shown.

[0067] The concentrated water obtained from the gas-water recovery pipeline 5 is sent to the pressurized concentrate processor 19. The heat transfer oil can be used for heating the concentrate processor and superheating the mixed steam. In the heat transfer oil heater 21, the heat transfer oil is first partially heated by the hot gas, increasing its temperature. The heat transfer oil pump then sends the heat transfer oil to the concentrate processor 19, where it evaporates the concentrate. The mixed gas leaving the evaporator is heated by another stream of heat transfer oil in the superheater to prevent steam condensation. Finally, the water and organic steam are sent to the high-temperature zone of the gasifier for gasification. The residual liquid at the bottom of the concentrate processor 19 is sent to the pulverized coal forming unit to obtain briquettes, which are used as part of the gasifier's feedstock. If the heat transfer oil is heated to 300°C by the hot gas, it is sent to the concentrate processor 19 and the mixed steam superheater 20. The concentrate is first heated and evaporated by the heat transfer oil in the processor, with an evaporation temperature of 105~135°C. The generated water vapor and organic steam are superheated to 200°C and sent to the gasifier.

[0068] In this way, all the coal gas and water produced during the coal gasification process are absorbed in the coal gasification workshop.

Claims

1. A treatment system for gas-water circulating concentrate from a fixed-bed gasifier, comprising a gas-water heat exchanger, a scrubbing tower, a humidification tower, and a concentrate processor or a concentrate evaporator; The concentrate processor uses steam heating; The upper part of the concentrated liquid evaporator is provided with a combustion furnace, and a burner is provided on the top of the combustion furnace or on the lower side of the concentrated liquid evaporator. The gas outlet of the fixed-bed gasifier is connected to the gas inlet of the gas-water heat exchanger, the gas outlet of the gas-water heat exchanger is connected to the gas inlet of the scrubbing tower, and the gas outlet of the scrubbing tower is connected to the downstream user. The washing water circulation pipeline of the washing tower is connected to the gas-water recovery pipeline. The circulating water outlet of the gas-water heat exchanger is connected to the top of the humidification tower, and the circulating water inlet is connected to the bottom of the humidification tower. The connecting pipe between the circulating water inlet and the humidification tower is also connected to the gas-water recovery pipe. An air / oxygen inlet is provided at the lower part of the side wall of the humidification tower, and the top is connected to the bottom of the fixed bed gasifier. The circulating water inlet of the gas-water heat exchanger is connected to the humidification tower via a concentrate recovery pipeline and is connected to the concentrate processor or the concentrate evaporator. The mixed gas outlet of the concentrate processor or the concentrate evaporator is connected to the fixed bed gasifier after passing through a dust collector. The bottom of the concentrate processor is connected to the concentrate recovery pipeline.

2. The processing system according to claim 1, characterized in that: The fixed-bed gasifier is a two-stage gas generator. The gas outlet of the upper stage is connected to the electrostatic precipitator for tar and the electrostatic precipitator for light oil, and the gas outlet of the lower stage is connected to the gas-water heat exchanger. The shell side of the gas-water heat exchanger is connected to the gas transmission pipeline, and the tube side is connected to the gas-water transmission pipeline.

3. The processing system according to claim 1, characterized in that: A bypass is connected between the gas inlet pipe and the gas outlet pipe of the gas-water heat exchanger.

4. The processing system according to any one of claims 1-3, characterized in that: The burner located at the top is equipped with a gas inlet and an air inlet; A temperature-regulating gas bypass is arranged on the side of the combustion furnace. A bypass is provided in the upper high-temperature zone of the concentrated liquid evaporator, and a bypass orifice plate is provided on the bypass. The bypass is connected to the mixed gas pipeline at the outlet of the concentrated liquid evaporator. The outlet of the concentrate recovery pipeline extends into the concentrate evaporator and is fitted with several nozzles; Atomizers are installed near the outlet end of both the concentrated liquid recovery pipeline and the air delivery pipeline connected to it. The bottom of the concentrate evaporator is connected to a condensation tank, and the outlet of the condensation tank is connected to the concentrate recovery pipeline.

5. The processing system according to any one of claims 1-3, characterized in that: The burner located on the lower side section is equipped with a gas inlet and an air inlet, and the high-temperature flue gas from the burner outlet enters the lower interior of the concentrate evaporator. The outlet of the concentrate recovery pipeline extends into the concentrate evaporator and is fitted with several nozzles; Atomizers are installed near the outlet end of both the concentrated liquid recovery pipeline and the air delivery pipeline connected to it. The bottom of the concentrate evaporator is connected to a condensation tank, and the outlet of the condensation tank is connected to the concentrate recovery pipeline.

6. The processing system according to any one of claims 1-3, characterized in that: An air distributor is located near the bottom of the concentrate processor. The top of the concentrate processor is connected to an electric superheater, and the top of the electric superheater is connected to the dust collector.

7. The processing system according to any one of claims 1-3, characterized in that: The top of the concentrate processor is connected to a mixing steam superheater; Both the concentrate processor and the mixed steam superheater are connected to the thermal oil heater via a thermal oil circulation pipeline. The thermal oil heater is located between the gas outlet of the fixed bed gasifier and the gas inlet of the scrubbing tower.

8. The processing system according to claim 6, characterized in that: The bottom of the concentrate processor is connected to the pulverized coal forming unit.

9. A method for treating the concentrated liquid from the gas-water circulation system of a fixed-bed gasifier, comprising the following steps: The gas-water produced by the fixed-bed gasifier is fed into the gas-water heat exchanger of the treatment system according to any one of claims 1-8, and after being cooled, it enters the scrubbing tower and enters the downstream unit after being scrubbed. The gas-water produced by the scrubbing tower is fed into the gas-water heat exchanger to exchange heat with the gas; the heated gas-water enters the humidification tower from the top and comes into countercurrent contact with the air / oxygen entering from the bottom. Part of the gas-water changes from liquid to steam and mixes with the air / oxygen. The resulting humid air containing water vapor enters the fixed-bed gasifier from the bottom as a gasifying agent. The concentrated liquid produced during the gas-water circulation-evaporation process is processed by the concentrated liquid processor or the concentrated liquid evaporator, and the mixed gas then enters the fixed-bed gasifier after passing through the dust collector.

10. The processing method according to claim 9, characterized in that: When the fixed-bed gasifier is a two-stage furnace, the outlet gas temperature of the upper stage furnace is 100~150℃, and the outlet gas temperature of the lower stage furnace is 400~600℃. When the fixed-bed gasifier is a single-stage gasifier, the outlet gas temperature is 450~700℃; The temperature of the mixed gas after being heated by the concentrate processor or the concentrate evaporator is higher than 200°C.

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