Method and equipment for treating geothermal water in a medium-deep non-interference geothermal system

Abstract

The present invention relates to the technical field of water treatment methods, and specifically discloses a method for treating geothermal water in a medium-deep non-interference geothermal system and a geothermal water treatment device. The method comprises: 1) inputting the first inlet water into the inlet of a geothermal well; 2) inputting the second inlet water into the inlet of the geothermal well and simultaneously driving the first round of geothermal water in the geothermal well to be output from the outlet through a first driving mode to form the first outlet water; 3) adding dispersed substances into the first outlet water to form the third inlet water, wherein the dispersed substance concentration in the third inlet water is greater than the dispersed substance concentration in the second round of geothermal water; 4) inputting the third inlet water into the inlet of the geothermal well and simultaneously driving the second round of geothermal water in the geothermal well to be output from the outlet through a first driving mode to form the second outlet water; 5) repeating the above steps 3-4) until the geothermal water retained in the geothermal well becomes the Nth round of geothermal water. The technical problem of mechanical energy consumption of geothermal water lifted from underground to the ground by a pump can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment methods, and in particular to a geothermal water treatment method and geothermal water treatment equipment for a mid-deep non-interference geothermal system. Background Art

[0002] The medium-deep non-interference geothermal system drills into the medium-deep underground layer (usually at a depth of 1 km to 5 km) and injects water into the ground using a closed circulation pipeline without affecting the geological structure. The water is heated in the high-temperature underground environment and then pumped back to the ground for power generation or heating. Compared with traditional geothermal development methods, the medium-deep non-interference geothermal system has little impact on the environment, strong sustainability, and a wide range of applications. It is considered to be a clean, safe, and renewable new energy utilization method.

[0003] At present, during the operation of mid-deep undisturbed geothermal systems, geothermal water is completely dependent on pumps to be lifted from underground to the surface, resulting in high mechanical energy consumption. Summary of the invention

[0004] The purpose of the present invention is to provide a geothermal water treatment method and geothermal water treatment equipment for a medium-deep non-interference geothermal system, so as to solve the technical problem of reducing the mechanical energy consumption of geothermal water lifted from underground to the ground by a pump during the operation of the medium-deep non-interference geothermal system.

[0005] In a first aspect, a method for treating geothermal water in a medium-deep non-interference geothermal system is provided, comprising the following steps performed within a geothermal water repetitive cycle: 1) inputting a first inlet of a geothermal well of the medium-deep non-interference geothermal system, wherein the first inlet of the geothermal well is raw water, and the raw water is input into the geothermal well from the inlet to become a first round of geothermal water; 2) inputting a second inlet of the geothermal well and simultaneously driving the first round of geothermal water in the geothermal well to be output from the outlet through a first driving method to form a first round of geothermal water. The first outflow water is the first outflow water, and the second inflow water contains dispersed substances dispersed in the water. The dispersed substance concentration in the second inflow water is greater than the dispersed substance concentration in the first round of geothermal water. The geothermal water remaining in the geothermal well after the first outflow water is discharged from the outlet becomes the second round of geothermal water; 3) dispersed substances are added to the first outflow water to form the third inflow water, and the dispersed substance concentration in the third inflow water is greater than the dispersed substance concentration in the second round of geothermal water; 4) the third inflow water is input into the inlet of the geothermal well and the second round of geothermal water in the geothermal well is driven by the first driving method at the same time. Water is output from the outlet to form the second water output, and the geothermal water remaining in the geothermal well after the second water output is output from the outlet becomes the third round of geothermal water; 5) repeat the above steps 3)-step 4), the number of repetitions is an integer ≥0 and each time the above steps 3)-step 4) are repeated, the corresponding batch of water inlet, the round of geothermal water and the batch of water output are respectively accumulated by 1 on the original basis, until the geothermal water retained in the geothermal well becomes the Nth round of geothermal water, N is an integer ≥3; 6) drive the Nth round of geothermal water to be output from the outlet through the second driving mode to form the Nth water output, filter the dispersed matter in the Nth water output, so as to obtain raw water with the dispersed matter concentration reduced to the set range, and the raw water is used as the first water inlet of the next geothermal water repetition cycle; wherein, the density of the dispersed matter used is greater than the density of the raw water, and the first driving mode uses the gravity sinking of each batch of water in the i-th water inlet to lift the corresponding i-1th round of geothermal water, i is each integer from 2 to N.

[0006] In the second aspect, a geothermal water treatment device for a medium-deep non-interference geothermal system is provided, which is used for the geothermal water treatment method for a medium-deep non-interference geothermal system in the first aspect, and includes: a first water storage device, used to store all batches of water in the i-th inflow and input all batches of water in the i-th inflow into the inlet of the geothermal well; a second water storage device, used to store all batches of water in the j-th outflow, where j is an integer from 1 to N; a dispersed matter adding device, used to add dispersed matter to the water body of the first water storage device and / or the second water storage device; a filtering device, used to filter the dispersed matter in the N-th outflow to obtain raw water whose dispersed matter concentration drops to a set range.

[0007] Through the above-mentioned method for treating geothermal water in a medium-deep non-interference geothermal system, it can be known that the concentration of dispersed matter in the i-th inlet water (i=2 to N) is greater than the concentration of dispersed matter in the i-1th round of geothermal water, and the higher the concentration of dispersed matter in the water body, the greater the density of the water body. Therefore, the density of the i-th inlet water must also be greater than the density of the i-1th round of geothermal water. In this way, all batches of inlet water in the i-th inlet water will sink by gravity in the geothermal well and lift the i-1th round of geothermal water, thereby reducing the mechanical energy required for the first driving method. Since N is an integer ≥3, within a geothermal water repetition cycle, the batches implementing the first driving method are also more than the batches implementing the second driving method. In summary, the method for treating geothermal water in a medium-deep non-interference geothermal system and the geothermal water treatment equipment of the present invention can solve the technical problem of reducing the mechanical energy consumption of lifting geothermal water from underground to the ground by pumps during the operation of a medium-deep non-interference geothermal system.

[0008] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be learned through practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings constituting a part of this specification are used to assist the understanding of the present invention. The contents provided in the drawings and the related descriptions in this specification can be used to explain the present invention, but do not constitute improper limitations on the present invention.

[0010] Figure 1 It is a schematic diagram of the principle of a method for treating geothermal water in a mid-deep non-interference geothermal system according to the present invention.

[0011] Figure 2 This is a schematic diagram of the installation of a geothermal water treatment device for a mid-deep non-interference geothermal system according to the present invention. Figure 2 The medium gray part represents the transparent entity, here specifically the transparent stratum.

[0012] Figure 3 This is a schematic diagram of the structure of a geothermal water treatment device for a mid-deep non-interference geothermal system according to the present invention. Figure 3 The medium gray part represents the transparent entity, specifically the transparent exterior wall.

[0013] Figure 4 It is a structural schematic diagram of a filtering device in a geothermal water treatment equipment of a mid-deep interference-free geothermal system of the present invention.

[0014] Marked in the figure are: geothermal well 1, first water inlet 21, second water inlet 22, third water inlet 23, first round of geothermal water 31, second round of geothermal water 32, third round of geothermal water 33, first water outlet 41, second water outlet 42, third water outlet 43, first water storage device 51, second water storage device 52, filtering device 53, intermediate storage tank 531, cross-flow filter 532, cross-flow filter element 532a, circulating pump 533, filter concentrator 534, tank body 534a, stirring device 534b, filter element 534c, energy recovery device 54, formation 6, isolation material 7. DETAILED DESCRIPTION

[0015] The present invention is described clearly and completely below in conjunction with the accompanying drawings. A person skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0016] The technical solutions and technical features provided in each section, including the following description, can be combined with each other without conflict. In addition, where possible, these technical solutions, technical features and related combinations can be assigned specific technical themes and protected by relevant patents.

[0017] The embodiments of the present invention involved in the following description are generally only a part of the embodiments rather than all the embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of patent protection.

[0018] Regarding the terms and units in this specification: The terms "include", "comprises" and any variations thereof in this specification and the corresponding claims and related parts are intended to cover non-exclusive inclusions. Other related terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0019] Figure 1 This is a schematic diagram of the principle of a method for treating geothermal water in a mid-deep layer non-interference geothermal system according to the present invention. Figure 1 , the method for treating geothermal water in a medium-deep non-interference geothermal system according to an embodiment of the present invention is described. Figure 1 As shown, the method for treating geothermal water in a medium-deep non-interference geothermal system comprises the following steps performed in a geothermal water repetitive circulation cycle:

[0020] 1) The first water inlet 21 is input into the inlet of the geothermal well 1 of the mid-deep undisturbed geothermal system. The first water inlet 21 uses raw water. The raw water becomes the first round of geothermal water 31 after being input into the geothermal well from the inlet of the geothermal well.

[0021] 2) The second inlet water 22 is input into the inlet of the geothermal well 1 and the first round of geothermal water 31 in the geothermal well 1 is driven to be discharged from the outlet through the first driving method to form the first outlet water 41. The second inlet water 22 contains dispersed substances dispersed in the water. The concentration of dispersed substances in the second inlet water 22 is greater than the concentration of dispersed substances in the first round of geothermal water 31. The geothermal water remaining in the geothermal well after the first outlet water 41 is discharged from the outlet becomes the second round of geothermal water 32.

[0022] 3) Adding dispersed matter to the first effluent 41 to form the third influent 23 , wherein the dispersed matter concentration in the third influent 23 is greater than the dispersed matter concentration in the second round of geothermal water 32 .

[0023] 4) The third water inlet 23 is input into the inlet of the geothermal well 1 and the second round of geothermal water 32 in the geothermal well 1 is driven to be output from the outlet through the first driving method to form the second output water 42. The geothermal water remaining in the geothermal well 1 after the second output water 42 is output from the outlet becomes the third round of geothermal water 33.

[0024] 5) Repeat the above steps 3)-4), the number of repetitions is an integer ≥ 0 and each time the above steps 3)-4) are repeated, the corresponding batches of incoming water, rounds of geothermal water and batches of output water are respectively accumulated by 1 on the original basis, until the geothermal water retained in the geothermal well becomes the Nth round of geothermal water, N is an integer ≥ 3.

[0025] 6) The Nth round of geothermal water is driven to be output from the outlet through the second driving mode to form the Nth effluent water, and the dispersed matter in the Nth effluent water is filtered to obtain raw water with the dispersed matter concentration reduced to the set range, and the raw water is used as the first inlet water 21 of the next geothermal water repetition cycle.

[0026] Among them, the density of the dispersed medium used is greater than the density of the raw water, and the first driving method completely or partially relies on the gravity sinking of all batches of water in the i-th water inflow to lift the corresponding i-1th round of geothermal water, where i is an integer from 2 to N.

[0027] To simplify, Figure 1 In the example, N is set to 3. That is, the actual number of repetitions in the above step 5) is 0, which is equivalent to the fact that step 5) does not exist. However, it should be pointed out in advance that the value of N can usually be set to be greater than 3.

[0028] like Figure 1 As shown, a geothermal water repetitive cycle is represented as six states AF, namely state A, state B, state C, state D, state E, and state F.

[0029] In state A, the first water storage device 51 is inputting the second water inflow 22 to the inlet of the geothermal well 1. At the same time, the mid-deep non-interference geothermal system drives the first round of geothermal water 31 in the geothermal well 1 through the first driving mode to be output from the outlet of the geothermal well 1 to form the first water outflow 41. The above state A actually continues the state F of the previous geothermal water repetitive cycle.

[0030] Since the concentration of dispersed matter in the second inflow water 22 is greater than that in the first round of geothermal water 31, and the density of dispersed matter used in the geothermal water treatment method of the mid-deep non-interference geothermal system is greater than that of raw water, the density of the second inflow water 22 must also be greater than that of the first round of geothermal water 31. Thus, in state A, the first driving mode can completely or partially utilize the gravity sinking of the second inflow water 22 to lift the first round of geothermal water 31.

[0031] After the first output water 41 is output from the outlet of the geothermal well 1, it is first subjected to energy recovery (power generation or heat exchange, etc.) and then enters the second water storage device 52 for temporary storage.

[0032] In state B, the second incoming water 22 has replaced the first round of geothermal water 31 and becomes the second round of geothermal water 32; at the same time, the first outflow water 41 in the second water storage device 52 begins to enter the first water storage device 51. The third incoming water 23 is formed by adding dispersed substances to the first outflow water 41. At this time, the first water storage device 51 is used to store the third incoming water 23.

[0033] In state C, the first water storage device 51 is inputting the third water inlet 23 into the inlet of the geothermal well 1. At the same time, the mid-deep interference-free geothermal system drives the second round of geothermal water 32 in the geothermal well 1 through the first driving mode to be output from the outlet of the geothermal well 1 to form the second water outlet 42.

[0034] Since the concentration of dispersed matter in the third inflow water 23 is greater than that in the second round of geothermal water 32, and the density of dispersed matter used in the geothermal water treatment method of the mid-deep non-interference geothermal system is greater than that of raw water, the density of the third inflow water 23 must also be greater than that of the second round of geothermal water 32. Thus, in state C, the first driving mode can completely or partially utilize the gravity sinking of the third inflow water 23 to lift the second round of geothermal water 32.

[0035] After the second water 42 is output from the outlet of the geothermal well 1, it first undergoes energy recovery (power generation or heat exchange, etc.) and then enters the second water storage device 52 for temporary storage.

[0036] In state D, the third incoming water 23 has basically replaced the second round of geothermal water 32 and becomes the third round of geothermal water 33; at the same time, the second outgoing water 42 in the second water storage device 52 is ready to enter the first water storage device 51 for storage.

[0037] In state E, the third round of geothermal water 33 is driven by the second driving mode to be output from the outlet to form the third water outlet 43. At the same time, the third water outlet 43 is input into the filtering device 53. The filtering device 53 filters the dispersed substances in the third water outlet 43 to obtain raw water with the dispersed substance concentration reduced to a set range. The raw water is then input from the inlet of the geothermal well 1 as the first water inlet 21 of the next geothermal water repetition cycle.

[0038] In state F, the first incoming water 21 has replaced the third round of geothermal water 33 of the previous geothermal water recirculation cycle and becomes the first round of geothermal water 31 ; meanwhile, the second incoming water 22 has been stored in the second water storage device 52 .

[0039] In the above geothermal water recirculation cycle, the geothermal water is lifted three times. The following is an explanation of the relevant energy consumption in the above geothermal water recirculation cycle.

[0040] First assume that geothermal well 1 is a U-shaped geothermal well with a depth of 2000m and a parallel section length of 500m. The inner diameter of geothermal well 1 is 200mm. The total length of the geothermal well = 2*2000m+500m=4500m. The volume of the geothermal well = π*(0.1 m)²*4500m≈141.37m³. The density of raw water is 1000kg / m³. The density of the second water inlet 22 increases by 5% based on the density of raw water. The density of the third water inlet 23 increases by 5% based on the density of the second round of geothermal water.

[0041] If the first round of geothermal water 31 (raw water) is extracted from the geothermal well 1 entirely by pumping, the required mechanical energy consumption is calculated as follows:

[0042] I. Calculate the mass of the first round of geothermal water 31:

[0043] Mass = density * volume = 1000kg / m³ * 141.37m³ = 141370kg.

[0044] II. Calculate gravitational potential energy:

[0045] Potential energy = m*g*h.

[0046] Among them, m=mass, g=gravitational acceleration (9.81m / s²), h is the average lifting height, h=depth / 2+parallel section length / 2=2000m / 2+500m / 2=1000m+250m=1250m.

[0047] Potential energy = 141370kg*9.81m / s²*1250m=1733308875J≈1.73GJ.

[0048] III. Estimation of Friction Losses:

[0049] Friction losses depend on several factors including flow rate, pipe roughness, etc. As a rough estimate, assume that friction losses are 20-30% of the gravitational potential energy.

[0050] Take 25%: friction loss ≈ 0.43GJ.

[0051] IV. Total energy requirements:

[0052] Total energy = potential energy + friction loss = 1.73GJ + 0.43GJ = 2.16GJ.

[0053] V. Consider the efficiency of the pump:

[0054] Assume the pump efficiency is 80%

[0055] The actual energy required = total energy / efficiency = 2.16GJ / 0.8 = 2.7GJ.

[0056] VI. Results:

[0057] In theory, about 2.7 GJ of energy is required to extract all the first round of geothermal water 31 (raw water) from the U-shaped geothermal well, which is equivalent to about 750 kWh of electricity.

[0058] Assuming that the density of the second water inflow 22 increases by 5% on the basis of the original water density, that is, the density of the second water inflow 22 is 1050kg / m³, it can be calculated that:

[0059] I. Pressure difference caused by density difference:

[0060] Pressure difference = density difference * gravitational acceleration * depth = (1050-1000) kg / m³ * 9.81 m / s² * 2000 m = 981000 Pa ≈ 0.981 MPa.

[0061] II. Friction loss:

[0062] Assuming that friction loss is 25% of the total energy, friction pressure loss ≈ pressure difference*25%=0.981MPa*0.25≈0.245Mpa.

[0063] III. Effective pressure difference:

[0064] Effective pressure difference = pressure difference caused by density difference - friction pressure loss = 0.981MPa-0.245MPa=0.736MPa.

[0065] IV. According to the Darcy–Weisbach equation, the velocity during the second water inflow 22 replacing the first round of geothermal water 31 (raw water) is estimated to be 0.5 m / s-3 m / s, which meets the requirements of a mid-deep undisturbed geothermal system.

[0066] V. Results:

[0067] The second water inflow 22 with an input density of 1050kg / m³ can theoretically allow the first round of geothermal water 31 (raw water) to flow out of the U-shaped geothermal well naturally and achieve complete replacement. This process is self-driven and does not require additional pump support. In other words, the first round of geothermal water 31 can be lifted without relying on pumps, thereby saving 750kWh of electricity.

[0068] Similarly, the second round of geothermal water 32 can be raised without relying on a pump, thereby saving at least an additional 750 kWh of electricity.

[0069] Assuming that the density of the third round of geothermal water 33 is 1102.5kg / m³ (i.e., the density is increased by 5% on the basis of 1050kg / m³), it can be calculated that the mechanical energy consumption required to completely rely on the pump to lift the third round of geothermal water 33 from the geothermal well 1 is 830kWh of electrical energy. The specific calculation process is:

[0070] I. Calculate the mass of the first round of geothermal water 31:

[0071] Mass = density * volume = 1102.5kg / m³ * 141.37m³ = 155860.125kg.

[0072] II. Calculate gravitational potential energy:

[0073] Potential energy = m*g*h.

[0074] Where m = mass, g = acceleration due to gravity (9.81 m / s²), and h = average lift height = 1250 m.

[0075] Potential energy = 155860.125kg*9.81m / s²*1250m=1,911,011,484.375J≈1.91GJ.

[0076] III. Estimation of Friction Losses:

[0077] Assume that friction losses are 25% of the gravitational potential energy.

[0078] Friction loss≈1.91GJ*0.25=0.48GJ.

[0079] IV. Total energy requirements:

[0080] Total energy = potential energy + friction loss = 1.91GJ + 0.48GJ = 2.39GJ.

[0081] V. Consider the efficiency of the pump:

[0082] Assume the pump is 80% efficient.

[0083] The actual energy required = total energy / efficiency = 2.39GJ / 0.8 = 2.99GJ.

[0084] VI. Results:

[0085] To extract all the geothermal water with a density of 1102.5kg / m³ from the U-shaped geothermal well, theoretically, about 2.99GJ of energy is required, which is equivalent to about 830kWh of electricity (2.99GJ*277.778kWh / GJ≈830kWh).

[0086] visible, Figure 1 The mechanical energy consumed by the three-time lifting pump for geothermal water in one geothermal water recirculation cycle is 830kWh. However, if the existing solution is adopted, the mechanical energy consumed by the three-time lifting pump is 3*750kWh=2250kWh. In one geothermal water recirculation cycle, the mechanical energy consumption of lifting geothermal water from underground to the ground by pumping is 2250kWh-830kWh=1420kWh.

[0087] Therefore, the method for treating geothermal water in a medium-deep layer non-interference geothermal system according to the embodiment of the present invention is Figure 1 In a geothermal water repetitive circulation cycle shown, the mechanical energy consumption of lifting geothermal water from underground to the surface through a pump during the operation of a mid-deep undisturbed geothermal system can be significantly reduced.

[0088] Furthermore, if the N value is set to be greater than 3, for example, a reasonable range is to set the N value to any integer between 5 and 8 (based on 1000 kg / m³, the density increases by 5% each time, and the fifth water inlet density is 1276.2815625 kg / m³), the mechanical energy consumption of the pump can be further reduced.

[0089] The energy consumption of common water filtration systems is usually in the range of 0.1kWh / m³-1kWh / m³. Taking the middle value of 0.5kWh / m³, filtering 141.37m³ of water once consumes about 70kWh. In other words, the energy consumption increased by filtering dispersed substances in the Nth effluent water using the above-mentioned medium-deep non-interference geothermal system geothermal water treatment method is basically negligible compared to the energy saved.

[0090] Generally speaking, the dispersion system formed by the dispersed substance and water in the i-th inflow is a colloid or a suspension. Here, the dispersion system formed by the dispersed substance and water in the i-th inflow is set as a colloid or a suspension, which can ensure the density adjustment ability of the i-th inflow (the density adjustment range of the solution is relatively limited), and the dispersed substance in the colloid or suspension can be separated by physical means, which is easier to recycle.

[0091] Preferably, the particle size of the dispersant in the dispersion is 0.1 micron-50 micron. Selecting a dispersant with a particle size range of 0.1 micron-50 micron can provide many advantages for the mid-deep non-interference geothermal system: it can form a stable dispersion with geothermal water, maintain good fluidity and heat transfer efficiency; it is suitable for filling formation pores of various sizes (although the desired situation is that the pipe body of the geothermal well 1 is completely isolated from the formation, but, limited by the current construction technology for U-shaped geothermal wells, the intersection of the parallel section and the vertical section of the U-shaped geothermal well may still be exposed to a certain extent); the sedimentation rate is controllable, which is convenient for subsequent filtration treatment; it will not significantly increase the system pressure loss or equipment wear; it allows the use of a variety of materials as dispersants (for example, the dispersant can be selected from any one of iron oxide, silicon dioxide, aluminum oxide, silicon carbide, glass microspheres, and montmorillonite), providing design flexibility; and this range is wide enough to achieve a particle size gradient design between batches (described later in this manual), thereby optimizing system performance and long-term stability.

[0092] As an improvement, the particle size range of the dispersed substances in each batch of water in the entire i-th water inflow can also be set to show a gradient upward trend with the increase of i value. For example, if N is set to 5, the particle size range of the dispersed substances in each batch of water in the entire i-th water inflow can be set as follows: the second water inflow: 0.1 micron-5 micron; the third water inflow: 10 micron-20 micron; the fourth water inflow: 25 micron-35 micron; the fifth water inflow: 40 micron-50 micron. It is best that the particle size ranges do not overlap to facilitate the separation of dispersed substances in different particle size ranges.

[0093] The main advantages of this setting are: first, the use of smaller-sized dispersed matter in the early batches of all the i-th water inflow can reduce the initial aggregation effect. As time goes by, the dispersed matter particle size gradually increases, but since the dispersed matter with smaller particle size has been distributed, the aggregation tendency of the dispersed matter with larger particle size will be reduced. Second, the dispersed matter with smaller particle size at the beginning provides a large surface area, which is conducive to the heat recovery of geothermal water; the dispersed matter with larger particle size later further increases the overall heat capacity of geothermal water. At the same time, the dispersed matter with larger particle size uses the heat transfer mode established by the dispersed matter with smaller particle size to achieve heat output, and the heat transfer efficiency is higher. Third, the dispersed matter with smaller particle size at the beginning will fill the tiny pores in the rock or formation (mainly at the junction of the parallel section and the vertical section of the U-shaped geothermal well), which helps to reduce the flow resistance of geothermal water. Fourth, the dispersed matter with smaller particle size at the beginning will have a slower sedimentation rate, which helps them to be more evenly distributed in the system; the dispersed matter with larger particle size later, although the sedimentation rate is faster, will be "supported" by the dispersed matter with smaller particle size, slowing down its sedimentation.

[0094] As a preferred embodiment, silicon carbide is particularly used as the dispersant. Silicon carbide particles have many advantages as dispersants in geothermal water: they have extremely high thermal conductivity, which can significantly improve the heat transfer efficiency; excellent wear resistance and chemical stability enable them to maintain performance for a long time in harsh environments; high temperature stability and low thermal expansion coefficient ensure reliability in temperature changes; good fluidity is conducive to system operation; at the same time, its environmental friendliness, controllable particle size distribution and long-term cost-effectiveness make silicon carbide an ideal dispersant material in the present invention, which can effectively improve system efficiency.

[0095] In addition, optionally, a dispersant for increasing the separation of dispersed particles and preventing aggregation may be added to the dispersion system, for example, sodium polyacrylate (PAAS).

[0096] Based on the above, the second water inlet 22 can be prepared from the following raw materials (% is weight ratio):

[0097] Water: 94.2%-94.7%;

[0098] Silicon carbide powder: 5%-5.5%;

[0099] Sodium polyacrylate: 0.3%-0.5%.

[0100] The contents of each raw material in the second influent water 22 are converted into volume percentages and the thermal conductivity of each raw material is weighted averaged according to the volume percentage. The thermal conductivity of the second influent water 22 is calculated to be 3.89 W / (m·K), which is much higher than the thermal conductivity of water 0.6 W / (m·K).

[0101] Furthermore, in order to prevent the mixing of each batch of water in the entire i-th water inflow with the corresponding i-1th round of geothermal water, before the i-th water inflow is input into the inlet of the geothermal well 1, a section of isolation material 7 can be injected into the inlet of the geothermal well 1. The isolation material 7 can maintain an isolation layer between the i-th water inflow and the i-1th round of geothermal water. The isolation layer can effectively prevent the i-th water inflow from directly mixing with the i-1th round of geothermal water, ensuring that the dispersed systems with different dispersed substance concentrations are relatively independent and maintaining the concentration gradient of the dispersed systems with different dispersed substance concentrations.

[0102] After the use of isolation material 7 is proposed here, the use of chemical gel is a possible solution. Chemical gel sealing technology has been widely used in oil exploration and development, mainly used for sealing formations and wellbores under high-strength pressure and acidic gas corrosion conditions (which is similar to the use environment of isolation material 7). However, chemical gel is formed by adding curing agent, retarder, weighting agent and other materials to the gel base liquid, so there is a problem of inconvenience in using it at the entrance of geothermal wells.

[0103] In this regard, another creative idea in the present invention is that the isolation material uses a foam material. Foam materials have many advantages as isolation materials, the most prominent of which is the convenience of injection and removal. This material can usually be injected into the geothermal well in liquid form (this can maintain the closedness of the mid-deep non-interference geothermal system, and the thickness of the isolation layer is not easy to control), and then foams itself in the well to form an effective isolation barrier. This feature makes the operation process simple and efficient, without the need for complex equipment or procedures. After flowing out of the geothermal well, the foam material can be separated from the effluent through a simple physical filtration procedure, so that it can be easily removed without causing long-term effects on the mid-deep non-interference geothermal system. In addition, the foam material also has the advantages of low density, strong compressibility, good thermal stability, high chemical stability, and no clogging of geothermal wells. It can maintain a good isolation effect in a high-temperature and high-pressure geothermal environment. At the same time, it has strong adaptability and can effectively fill irregular spaces to ensure the integrity of the isolation. These characteristics make the foam material an ideal choice of isolation material in the present invention.

[0104] The foam material can be selected from foam materials having at least the following characteristics: a) being water-proof; b) being able to withstand the temperature at a depth of several kilometers underground; and c) being light in weight and able to float on the surface of water without deformation. For example, the foam material can be selected from polyetheretherketone or polyimide.

[0105] Figure 2 This is a schematic diagram of the installation of geothermal water treatment equipment for a mid-deep non-interference geothermal system according to the present invention. Figure 3 It is a structural schematic diagram of geothermal water treatment equipment for a mid-deep interference-free geothermal system according to the present invention. Figure 2-Figure 3 The medium grey areas represent the transparent entities.

[0106] like Figure 2-Figure 3 As shown, a geothermal water treatment equipment for a medium-deep non-interference geothermal system is arranged in a ground plant and is used for the above-mentioned geothermal water treatment method for a medium-deep non-interference geothermal system, comprising: a first water storage device 51, used to store all batches of water in the i-th inflow and input all batches of water in the i-th inflow into the inlet of a geothermal well 1 (the geothermal well 1 is opened in the formation 6 and adopts a U-shaped geothermal well, which is a common form of geothermal well); a second water storage device 52, used to store all batches of water in the j-th outflow, where j is an integer from 1 to N; a dispersed matter adding device, used to add dispersed matter to the water body of the first water storage device 51 and / or the second water storage device 52; a filtering device 53, used to filter the dispersed matter in the N-th outflow to obtain raw water with the dispersed matter concentration reduced to a set range.

[0107] The above-mentioned mid-deep non-interference geothermal system geothermal water treatment equipment is usually also provided with an energy recovery device 54 in the ground plant, such as a geothermal generator or a heat exchanger.

[0108] Figure 4 The structure diagram of the filtering device in the geothermal water treatment equipment of the mid-deep non-interference geothermal system of the present invention is shown in FIG. Figure 4 As shown, the filtering device 53 specifically includes an intermediate storage tank 531 and a cross-flow filter 532, the intermediate storage tank 531 is connected to the second water storage device 52, the filtered water inlet and the concentrated water outlet of the cross-flow filter 532 are respectively connected to the intermediate storage tank 531, and the filtered water outlet of the cross-flow filter 532 is connected to the inlet of the geothermal well 1.

[0109] The working principle of the above-mentioned filtering device 53 is: the Nth water output first enters the intermediate storage tank 531, the water to be filtered in the intermediate storage tank 531 is input into the water to be filtered inlet of the cross-flow filter 532 through the circulation pump 533 and filtered through the cross-flow filter element 532a of the cross-flow filter 532, the filtered water is output from the filtered water outlet of the cross-flow filter 532 and flows to the inlet of the geothermal well 1, and the concentrated water returns to the intermediate storage tank 531 from the concentrated water outlet of the cross-flow filter 532 and is circulated and filtered again.

[0110] In addition, the filter device 53 is further provided with a filter concentrator 534 after the cross-flow filter 532 to improve the concentration efficiency of the filter device 53. The filter concentrator 534 can further filter and concentrate the concentrated water in the intermediate storage tank 531 to obtain dispersed matter. The specific structure of the filter concentrator 534 includes a tank body 534a, a stirring device 534b disposed in the tank body 534a, and a filter element 534c installed in the tank body 534a.

[0111] When the particle size range of the dispersed substances in each batch of influent water in the i-th influent water shows a gradient upward trend with the increase of the i value, the filter element may include N-1 types of filter element units, and the filtration accuracies of different types of filter element units are also distributed in a gradient.

[0112] For example: Assume that the particle size range of the dispersed substances in each batch of water in the entire i-th water inflow is set as follows: the second water inflow: 0.1 micron-5 micron; the third water inflow: 10 micron-20 micron; the fourth water inflow: 25 micron-35 micron; the fifth water inflow: 40 micron-50 micron. At this time, the filtration accuracy of the first filter element unit can be set to allow dispersed substances below 5 microns to pass through but not allow dispersed substances ≥10 microns to pass through, the filtration accuracy of the second filter element unit can be set to allow dispersed substances below 20 microns to pass through but not allow dispersed substances ≥25 microns to pass through, the filtration accuracy of the third filter element unit can be set to allow dispersed substances below 35 microns to pass through but not allow dispersed substances ≥40 microns to pass through, and the filtration accuracy of the fourth filter element unit can be set to allow dispersed substances below 50 microns to pass through. When the filter concentrator 534 is working, it first filters through the first filter element unit to obtain a filtrate enriched with 0.1 micron-5 micron dispersed matter, and then filters through the second filter element unit to obtain a filtrate enriched with 10 micron-20 micron dispersed matter, and so on.

[0113] It can be seen that when the particle size range of the dispersed substances in each batch of the i-th influent water shows a gradient upward trend with the increase of the i value, the filter element includes N-1 types of filter element units, and the filtration accuracies of different types of filter element units are also distributed in a gradient, so that dispersed substances in different particle size ranges can be recovered respectively.

[0114] The above is a description of the relevant contents of the present invention. A person skilled in the art will be able to implement the present invention based on these descriptions. Based on the above contents of this specification, all other embodiments obtained by a person skilled in the art without making any creative work shall fall within the scope of patent protection.

Claims

1. A method for treating geothermal water in a medium-deep non-interference geothermal system, characterized by: The following steps are performed during a geothermal water recirculation cycle: 1) The first water inlet is input into the inlet of the geothermal well of the mid-deep undisturbed geothermal system. The first water inlet uses raw water. The raw water is input into the geothermal well from the inlet to become the first round of geothermal water; 2) Inputting the second inlet water into the inlet of the geothermal well and driving the first round of geothermal water in the geothermal well to be discharged from the outlet through the first driving method to form the first outflow water, the second inlet water contains dispersed substances dispersed in the water, the concentration of dispersed substances in the second inlet water is greater than the concentration of dispersed substances in the first round of geothermal water, and the geothermal water remaining in the geothermal well after the first outflow water is discharged from the outlet becomes the second round of geothermal water; 3) Adding dispersed matter to the first effluent to form the third influent, the dispersed matter concentration in the third influent is greater than the dispersed matter concentration in the second round of geothermal water; 4) The third inflow water is input into the inlet of the geothermal well and the second round of geothermal water in the geothermal well is driven to be output from the outlet through the first driving method to form the second outflow water. The geothermal water remaining in the geothermal well after the second outflow water is output from the outlet becomes the third round of geothermal water; 5) Repeat the above steps 3-4), the number of repetitions is an integer ≥ 0 and each time the above steps 3)-4) are repeated, the corresponding batches of incoming water, the rounds of geothermal water and the batches of output water are respectively accumulated by 1 on the original basis, until the geothermal water retained in the geothermal well becomes the Nth round of geothermal water, N is an integer ≥ 3; 6) The Nth round of geothermal water is driven to be output from the outlet through the second driving mode to form the Nth outflow water, and the dispersed matter in the Nth outflow water is filtered to obtain raw water with the dispersed matter concentration reduced to the set range, and the raw water is used as the first inflow water of the next geothermal water recirculation cycle; The density of the dispersed medium used is greater than the density of the raw water, and the first driving mode uses the gravity sinking of all the batches of water in the i-th water inflow to lift the geothermal water corresponding to the i-1th round, where i is an integer from 2 to N; The dispersion system formed by the dispersoid and water in the i-th influent is a colloid or a suspension; the particle size of the dispersoid in the dispersion system is 0.1 microns-50 microns; and the particle size range of the dispersoid in each batch of influent in all the i-th influents shows a gradient upward trend with the increase of the i value.

2. The method for treating geothermal water in a medium-deep non-interference geothermal system according to claim 1, characterized in that: The dispersant is selected from any one of iron oxide, silicon dioxide, aluminum oxide, silicon carbide, glass microspheres and montmorillonite.

3. The method for treating geothermal water in a medium-deep non-interference geothermal system according to claim 1, characterized in that: The dispersion system also contains a dispersant for increasing the separation of dispersed particles and preventing aggregation.

4. The method for treating geothermal water in a medium-deep non-interference geothermal system according to claim 1, characterized in that: Before the i-th water inflow is input into the inlet of the geothermal well, a section of insulating material is first injected into the inlet of the geothermal well, and the insulating material can maintain an insulating layer between the i-th water inflow and the i-1-th round of geothermal water.

5. The method for treating geothermal water in a medium-deep non-interference geothermal system according to claim 4, characterized in that: The insulating material uses a foaming material which is injected into a geothermal well in a liquid form and then foams itself in the geothermal well.

6. The method for treating geothermal water in a medium-deep non-interference geothermal system according to claim 1, characterized in that: N is any integer from 5 to 8.

7. Medium-deep non-interference geothermal system geothermal water treatment equipment, characterized by: The method for treating geothermal water in a medium-deep non-interference geothermal system as described in any one of claims 1 to 6 comprises: a first water storage device for storing all batches of water in the i-th inflow and inputting all batches of water in the i-th inflow into the inlet of the geothermal well; a second water storage device for storing all batches of water out of the j-th outflow, where j is an integer from 1 to N; a dispersed matter adding device for adding dispersed matter to the water body of the first water storage device and / or the second water storage device; a filtering device for filtering the dispersed matter in the N-th outflow to obtain raw water with the dispersed matter concentration reduced to a set range; the filtering device comprises an intermediate storage device; A tank and a cross-flow filter, the intermediate storage tank is connected to the second water storage device, the filtered water inlet and the concentrated water outlet of the cross-flow filter are respectively connected to the intermediate storage tank, and the filtered water outlet of the cross-flow filter is connected to the geothermal well inlet; a filter concentrator is also arranged after the cross-flow filter, and the filter concentrator is used to further filter and concentrate the concentrated water in the intermediate storage tank to obtain dispersed matter, the filter concentrator comprises a tank body, a stirring device arranged in the tank body and a filter element installed in the tank body, the filter element comprises N-1 kinds of filter element units, and the filtering accuracies of different kinds of filter element units are also distributed in a gradient, and dispersed matter in different particle size ranges can be recovered respectively.

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